No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
UV Damage of Collagen: Insights from Model Collagen Peptides
Abstract
Fibrils of Type I collagen in the skin are exposed to ultraviolet (UV) light and there have been claims that collagen photo-degradation leads to wrinkles and may contribute to skin cancers. To understand the effects of UV radiation on collagen, Type I collagen solutions were exposed to the UV-C wavelength of 254 nm for defined lengths of time at 4°C. Circular dichroism (CD) experiments show that irradiation of collagen leads to high loss of triple helical content with a new lower thermal stability peak and SDS-gel electrophoresis indicates breakdown of collagen chains. To better define the effects of UV radiation on the collagen triple-helix, the studies were extended to peptides which model the collagen sequence and conformation. CD studies showed irradiation for days led to lower magnitudes of the triple-helix maximum at 225 nm and lower thermal stabilities for two peptides containing multiple Gly-Pro-Hyp triplets. In contrast, the highest radiation exposure led to little change in the T(m) values of (Gly-Pro-Pro)(10) and (Ala-Hyp-Gly)(10) , although (Gly-Pro-Pro)(10) did show a significant decrease in triple helix intensity. Mass spectroscopy indicated preferential cleavage sites within the peptides, and identification of some of the most susceptible sites of cleavage. The effect of radiation on these well defined peptides gives insight into the sequence and conformational specificity of photo-degradation of collagen.
... These results are consistent with our previous study showing the protective effect of Amaranthus cruentus seed oil on the deregulation of collagen biosynthesis and prolidase activity in UVA-irradiated fibroblasts [19]. ...
... While Sq is slightly less effective than Amaranthus cruentus seed oil in restoring the UVA-induced inhibition of collagen biosynthesis [19], its ability to maintain prolidase activity in these conditions at a near-control level highlights its significant protective role. These discoveries open up new possibilities for incorporating Sq into dermatological formulations not only to reduce UVA-induced skin damage but also as a regenerative or anti-aging agent. ...
... Sq at the studied concentrations evokes a protective effect on UVA-induced decrease in TGF-β 1 and increase in p-38 expression. This aligns with existing evidence that antioxidants derived from natural sources, such as green tea, pomegranate extract, or Amaranthus cruentus seed oil, can counteract oxidative stress and restore cellular signaling pathways affected by UVA [19,21,22]. The study confirms a positive correlation between receptor expression (β1-integrin and IGF-IR), prolidase activity, and collagen biosynthesis. ...
Squalane, a highly stable derivative of squalene, has received attention for its potential application in dermatology and cosmetics due to its biocompatibility, moisturizing properties, and antioxidant activity. This study investigates the effects of squalane on UVA-induced oxidative stress, inflammation, deregulation of collagen metabolism, and some growth signaling pathways in human dermal fibroblasts (HDFs). It has been found that squalane at concentrations of 0.005–0.015% counteracted the UVA-induced inhibition of oxidative stress, collagen biosynthesis, prolidase activity, expression of the β1-integrin receptor, insulin-like growth factor-I receptor (IGFR), transforming growth factor-β (TGF-β), phosphorylated kinases ERK1/2, and increase in the expression of p38 kinase in HDFs. Moreover, squalane at the studied concentrations counteracted UVA-induced increase in the expression of NF-κB and COX-2 in HDFs, suggesting its anti-inflammatory activity. Interestingly, squalane augmented the UVA-induced expression of nuclear factor erythroid 2-related factor 2 (Nrf2). The functional significance of squalane activities was found in a model of wound healing in HDFs. Squalane at the studied concentrations stimulated fibroblast migration, facilitating the repair process following exposure of the cells to UVA radiation. These results demonstrate the ability of squalane to counteract UVA-induced cell damage and suggest its potential to support skin regeneration, highlighting its application in anti-aging, post-sun repair, and regenerative care formulations.
... CLG is one of the most important proteins in the human body because it is responsible for maintaining the appropriate structure of tissues and organs and constitutes as much as one-third of the total body protein mass [7]. It occurs, among the main organs in the body that provide appropriate elasticity and strength [8][9][10][11]. It is also an essential building block of the skin; without CLG, it would not be able to perform its functions properly. CLG proteins in the dermis are constantly being rebuilt, and [28]). ...
... There is a natural mechanism in the regulates the production of collagen. Enzymes-metalloproteinases-play an important role in this process, e.g gen molecule damaged by UV rays is cut into pieces by MMP 1 (matrix metallop I) [11,55]. Such fragments created from cut peptides (e.g., tripeptides) become for fibroblasts, which will be able to produce new, properly constructed colla metic procedures are largely based on this knowledge, the mechanism of which stroy old CLG fibers, then produce signal peptides from them, and then stimu blasts to produce new CLG [53]. ...
... Moreover, the basement membrane participates in the exchange of between blood vessels and avascular epithelium and in the differentiation of cells [45]. The basement membrane consists of i. lamina lucidum, which lies b epithelial cells; it contains characteristic glycoproteins such as fibronectin, lam entactin, which ensure adhesion, i.e., adhesion of the basement membrane to Enzymes-metalloproteinases-play an important role in this process, e.g., a collagen molecule damaged by UV rays is cut into pieces by MMP 1 (matrix metalloproteinase I) [11,55]. Such fragments created from cut peptides (e.g., tripeptides) become feedback for fibroblasts, which will be able to produce new, properly constructed collagen. ...
Collagen (CLG) belongs to the family of fibrillar proteins and is composed of left-handed α polypeptide chains, which, twisting around themselves and their axis, form a right-handed superhelix. In the chemical structure, it contains mainly proline, hydroxyproline, glycine, and hydroxylysine. It occurs naturally in the dermis in the form of fibers that provide the skin with proper density and elasticity. The review aimed to present the types of collagen protein, factors affecting its structure and its unusual role in the functioning of the human body. Also, an overview of cosmetic products containing collagen or its derivatives, the characteristics of the formulas of these products, and the effects of their use were presented. Throughout the market, there are many cosmetic and cosmeceutical products containing CLG. They are in the form of fillers administered as injections, belonging to the group of the oldest tissue fillers; products administered orally and for topical use, such as creams, gels, serums, or cosmetic masks. Analyzed studies have shown that the use of products with collagen or its peptides improves the general condition of the skin and delays the aging process by reducing the depth of wrinkles, improving hydration (in the case of oral preparations), reducing transepithelial water loss (TEWL), as well as improving skin density and elasticity. In addition, oral application of bioactive CLG peptides has shown a positive effect on the nails, reducing the frequency of their breakage.
... In human skin, type I and type III collagens (COL1 and COL3) are the dominant subtypes. COL1 is a heterotrimer having two α1 and one α2 chains (Jariashvili et al., 2012), which is always threatened by UV-induced damage (Shoulders and Raines, 2011;Jariashvili et al., 2012). Several lines of evidence have suggested that UV exposure could induce oxidative degradation of collagen, and consequently expedites the skin damage during aging (Tanaka et al., 2009;Jariashvili et al., 2012). ...
... In human skin, type I and type III collagens (COL1 and COL3) are the dominant subtypes. COL1 is a heterotrimer having two α1 and one α2 chains (Jariashvili et al., 2012), which is always threatened by UV-induced damage (Shoulders and Raines, 2011;Jariashvili et al., 2012). Several lines of evidence have suggested that UV exposure could induce oxidative degradation of collagen, and consequently expedites the skin damage during aging (Tanaka et al., 2009;Jariashvili et al., 2012). ...
... COL1 is a heterotrimer having two α1 and one α2 chains (Jariashvili et al., 2012), which is always threatened by UV-induced damage (Shoulders and Raines, 2011;Jariashvili et al., 2012). Several lines of evidence have suggested that UV exposure could induce oxidative degradation of collagen, and consequently expedites the skin damage during aging (Tanaka et al., 2009;Jariashvili et al., 2012). One of the assumptions of collagen degradation is the disruption of peptide bonds within collagen under UV exposure, rather than damaging the helical structure (Kamińska and Sionkowska, 1996). ...
Capsaicin, a major ingredient in chili pepper, has broad pharmaceutical applications, including relieving pain, anti-inflammation, and treating psoriasis. In dermatological biology, capsaicin has been shown to prevent the ultraviolet (UV)-induced melanogenesis via TRPV1 receptor. To strengthen the roles of capsaicin in skin function, the damaged skin, triggered by exposure to UV, was reversed by capsaicin in both in vitro and in vivo models. In cultured dermal fibroblasts, the exposure to UV induced a decrease of collagen synthesis and increases expression of matrix metalloproteinases (MMPs), generation of reactive oxygen species (ROS), and phosphorylation of Erk and c-Jun, and these events subsequently led to skin damage. However, the UV-mediated damages could be reversed by pre-treatment with capsaicin in a dose-dependent manner. The effect of capsaicin in blocking the UV-mediated collagen synthesis was mediated by reducing generation of ROS in dermal fibroblasts, instead of the receptor for capsaicin. Hence, capsaicin has high potential value in applying as an agent for anti-skin aging in dermatology.
... One of the main effects is direct bond cleavage, which mainly affects side chains with aromatic rings or sulfur moieties. This disruption can fragment the amino acid backbone or modify its side chain, potentially altering its chemical and functional properties (Jariashvili et al., 2012). For example, UV-C readily cleaves aromatic rings in tryptophan and tyrosine, leading to the formation of various photoproducts. ...
... Such fragmentation can have far-reaching consequences beyond physical breakdown, as these peptide fragments may possess distinct biological properties and act as signaling molecules. This implies that UV-C processing has the potential to impact cellular processes by generating protein fragments (da Silva et al., 2023;Fujii et al., 2004;Jariashvili et al., 2012). ...
... Raw proteins were purified using a Ni-NTA Sepharose column with elution buffer (20 mM sodium phosphate buffer pH 7.4, 500 mM NaCl, 500 mM imidazole). Collagen protein THRC was obtained after trypsin digestion of the purified protein to remove the folding domain as previously described [34]. The degraded fragments were removed by dialysis using 50 mM PBS buffer (pH 7.4). ...
... THRC dressings have been applied to the photodamaged mice wounds, which are rapidly healed without complications in a short period. Photo-injured skin is severely damaged in both the epidermis and the dermis, resulting in acute inflammation and collagen fiber breakage [34]. Skin erythema and edema were observed as acute post-inflammatory reactions, which were significantly reduced after 4 days of treatment with THRC dressings, while the reported wound care products of a petroleum-based ointment or a novel silicone gel showed persistent redness on day 7 [12,37]. ...
Skin rejuvenation procedures such as microneedling and laser resurfacing have gained global popularity in medical cosmetology, leading to acute skin wounds with persistent pain, erythema, and edema. A variety of dressings have been explored to repair these postoperative skin injuries; however, their inadequate biocompatibility and bioactivity may raise concerns about undesirable efficacy and complications. Herein, we developed biocompatible and nonirritating triple-helical recombinant collagen (THRC) dressings for accelerated healing of microneedle-injured and photodamaged acute skin wounds. Circular dichroism (CD) measurements of THRC from various batches exhibited triple-helical structure characteristics of collagen. Cell experiments using L929 fibroblasts revealed that THRC dressings possess superior biocompatibility and bioactivity, significantly elevating the proliferation and adhesion of fibroblasts. In vivo, skin irritation tests of New Zealand rabbits demonstrated that the THRC dressings are gentle, safe, and non-irritating. Histological analysis of the animal model studies in photodamaged skin wounds using H&E and Masson’s trichrome staining revealed that 4 days of treatment with the THRC dressings effectively healed the damaged dermis by accelerating re-epithelialization and enhancing collagen deposition. In vivo studies of microneedle-injured rat defects showed that THRC dressings of varying concentrations exhibit the same rapid epithelialization rates at 48 h as commercial bovine collagen dressings. The highly biocompatible and bioactive recombinant collagen dressings may provide an advanced treatment of acute skin wounds, indicating attractive applications in postoperative care of facial rejuvenation.
... At the initial stage of UV irradiation, the triple helix of collagen was stabilized by UV-induced cross-linking. As the irradiation continued, the triple helix became disrupted and denatured, and the ultimate tensile strength and elongation of collagen tendons got decreased with increasing UV exposure time [18]. Serious lesion also occurred in collagen fibril D-bands, while the height difference of overlapping and gap regions was reduced from 3.7 nm to 0.8 nm, and the fibril diameter was decreased by an average of 8-10% [19]. ...
... Masson staining images of the untreated group showed plenty collagen debris and short aggregates, which could result from collagen polypeptide chain breakage and degradation of collagen fibers due to severe UV irradiations (Fig. 4) [16][17][18]. In contrast, Masson staining images of the three treated group all showed a significant increase in the amount of well-ordered dense collagen fibers with interspersing fibroblasts, which well resembled the normal dermis. ...
Sunburn is one of the most common skin lesions caused by excessive UV exposure, and its incidence is highly correlated with the risks of skin cancer. A variety of drugs including corticosteroids and NSAIDs have been developed to treat acute sunburn, however, they have raised severe concerns such as poor healing efficacy and long recovery time. We have for the first time extracted non-denatured type I collagen from yak hide, which displays a canonical triple helical structure with melting temperature of 42.7 °C. The highly pure yak collagen type I (YCI) self-assembles to form well-ordered nanofibers with periodic d-bands. YCI is highly biocompatible, and it significantly promotes the proliferation and adhesion of HFF-1 cells. The sunburn healing effects of YCI has been investigated using acute skin injury mouse model. Histological analysis shows that 4 days’ treatment of YCI has resulted in the recovery of sunburned mice skin to a healthy state, indicated by pronounced acceleration of epithelization and collagen deposition. The collagen volume fraction as well as the hydroxyproline (Hyp) content of YCI-treated sunburned skin have been found to be greatly increased, confirming the enhanced regeneration of collagen. YCI creams and dressings have also shown superior healing capacity of sunburn by remarkably shortening the recovery time. Notably, the denatured collagen-targeted staining results indicated a large quantity of denatured collagen in sunburned mice, which became substantially reduced after the YCI treatment. FITC-labeled YCI has been further found to penetrate into the dermis of sunburned mice. The highly biocompatible and bioactive non-denatured YCI provides an improved treatment of sunburn, indicating very promising applications of YCI in cosmetics and dermatology.
... unfolding, aggregation, or fracturing (which makes them more susceptible to proteolytic enzymes and accelerates their degradation), increase in hydrophobicity, alteration of light scattering properties, or optical rotation (Davies and Truscott, 2001;Pattison et al., 2012). In the specific case of collagen, photodegradation results in the cleavage of peptide bonds and formation of tyrosine from phenylalaline (main compound of collagen; Torikai and Shibata, 1999;Jariashvili et al., 2012). ...
... Hide and bone glues as well as beeswax were discoloured by UV light due to the alteration and photodegradation of their protein and lipid components (Bekbölet, 1990;Kochevar, 1990;Cheeseman and Slater, 1993;Torikai and Shibata, 1999;Davies and Truscott, 2001;Jariashvili et al., 2012;Pattison et al., 2012;Pereira and Abreu, 2018;Vykydalová et al., 2020). Their transformation in adhesive manufacture did not change their susceptibility to degradation under UV light. ...
Functional studies of prehistoric stone tools are often hindered by the surface preservation of the artefacts. Archaeological residues and use-wear can differ from their experimentally reproduced counterparts to an extent that their identification is not possible by simple comparison. An understanding of how stone tools and residues change over time is thus essential for a better view of past human technology. In open-air site contexts, UV light is the first degradation agent to impact lithic tools before their burial. Even though UV light has been mentioned as an alteration process and its effects on certain mineral and organic materials are known from other scientific fields, it has never been thoroughly studied in archaeology. This study provides a synthesis of the effect of UV light on organic materials and presents the results of the first controlled experiment ever carried out in archaeology to investigate the impact of UV light on flint tools and adhesives.
... Numerous studies have indicated that at least two factors are primarily involved in extrinsic aging, namely (1) ultraviolet (UV) radiation and (2) stress. It has been clearly demonstrated that these stimuli cause a reduction in cell number and collagen synthesis in dermal fibroblasts [11][12][13][14][15], but the mechanisms involved in the regulation of cell growth and collagen synthesis are not fully established. ...
... In addition, the release of lactate dehydrogenase (LDH) was significantly increased in UVB-irradiated or Dex-treated Hs68 cells, indicating that reduced cell viability by UVB or Dex is associated with cell death ( Figure 1B). number and collagen synthesis in dermal fibroblasts [11][12][13][14][15], but the mechanisms involved in the regulation of cell growth and collagen synthesis are not fully established. ...
Skin dermis comprises extracellular matrix components, mainly collagen fibers. A decrease in collagen synthesis caused by several factors, including ultraviolet (UV) irradiation and stress, eventually causes extrinsic skin aging. Olfactory receptors (ORs) were initially considered to be specifically expressed in nasal tissue, but several ORs have been reported to be present in other tissues, and their biological roles have recently received increasing attention. In this study, we aimed to characterize the role of ORs in cell survival and collagen synthesis in dermal fibroblasts. We confirmed that UVB irradiation and dexamethasone exposure significantly decreased cell survival and collagen synthesis in Hs68 dermal fibroblasts. Moreover, we demonstrated that the mRNA expression of 10 ORs detectable in Hs68 cells was significantly downregulated in aged conditions compared with that in normal conditions. Thereafter, by individual knockdown of the 10 candidate ORs, we identified that only OR51B5 knockdown leads to a reduction of cell survival and collagen synthesis. OR51B5 knockdown decreased cAMP levels and dampened the downstream protein kinase A/cAMP-response element binding protein pathway, downregulating the survival- and collagen synthesis-related genes in the dermal fibroblasts. Therefore, OR51B5 may be an interesting candidate that plays a role in cell survival and collagen synthesis.
... Таким фактором является механическое напряжение и воздействие на кожу ультрафиолета (отсутствие механического растяжения фибробластов координированно увеличивает выработку коллагеназы и уменьшает выработку коллагена). Кроме того, даже кратковременное УФ-облучение снижает выработку коллагена примерно на 80% и увеличивает уровень матричных металлопротеиназ в сотни раз [1,[5][6][7][8]. ...
The aim of the study was to evaluate the viability and proliferative activity of fibroblasts, as well as gene expression (collagen type 1 (COL1), elastin (ELN), matrix metalproteinase type 1 (MMP1), matrix metalproteinase type 3 (MMP3) and versican (VCAN )) after exposure to six different collagen preparations - dermal fillers. Materials and methods. The standard MTT test was used to measure cell viability, proliferation and cytotoxicity. Gene expression was measured using real-time reverse transcription polymerase chain reaction (RT-rtPCR). Results. The results obtained showed that the effectiveness of the studied drugs does not depend on the concentration of collagen in the final solution. When performing the MTT test, the greatest proliferative activity was observed for fibroblasts incubated with the Collost micro drug. For the Linerase drug, after 48 hours, a higher expression of collagen was observed compared to other drugs. It should be noted that there was no expression of the mmp1 gene after 24 hours in all samples except those treated with Collapro30+ and Collapro55+. Based on the results of pairwise comparison, no significant differences between groups in MMP3 gene expression (24 hours and 48 hours after incubation) were revealed. Also, in samples treated with Collapro30+, Collapro45+ and Collapro55+, versican is expressed at a higher level on the first day of the study. In turn, on the second day, versican is expressed at a higher level in the Collapro45+ and Linerase preparations.
... These results indicate that preferential Gly -Pro bond cleavage is an intrinsic property of collagen mimetic peptides. The latter conclusion is supported by the literature, since the Gly -Pro peptide bonds of (PPG) 10 and (POG) 10 peptides were also found to be particularly fragile following UV irradiation in solution (Jariashvili et al. 2012). UV light, especially in the highest energy region UV-C (280-160 nm wavelength), is known to trigger damage to biological molecules through the formation of free radicals, but can also cleave covalent bonds after direct photoabsorption and electronic excitation of biomolecules. ...
Little is known regarding radiation-induced matrikines and the possible degradation of extracellular matrix following therapeutic irradiation. The goal of this study was to determine if irradiation can cut collagen proteins at specific sites, inducing potentially biologically active peptides against cartilage cells. Chondrocytes cultured as 3D models were evaluated for extracellular matrix production. Bystander molecules were analyzed in vitro in the conditioned medium of X-irradiated chondrocytes. Preferential breakage sites were analyzed in collagen polypeptide by mass spectrometry and resulting peptides were tested against chondrocytes. 3D models of chondrocytes displayed a light extracellular matrix able to maintain the structure. Irradiated and bystander chondrocytes showed a surprising radiation sensitivity at low doses, characteristic of the presence of bystander factors, particularly following 0.1 Gy. The glycine-proline peptidic bond was observed as a preferential cleavage site and a possible weakness of the collagen polypeptide after irradiation. From the 46 collagen peptides analyzed against chondrocytes culture, 20 peptides induced a reduction of viability and 5 peptides induced an increase of viability at the highest concentration between 0.1 and 1 µg/ml. We conclude that irradiation promoted a site-specific degradation of collagen. The potentially resulting peptides induce negative or positive regulations of chondrocyte growth. Taken together, these results suggest that ionizing radiation causes a degradation of cartilage proteins, leading to a functional unbalance of cartilage homeostasis after exposure, contributing to cartilage dysfunction.
Supplementary Information
The online version contains supplementary material available at 10.1007/s00411-024-01086-z.
... Excess sun exposure can damage collagen fibers, reducing their thickness and strength, leading to wrinkles on the skin's surface. Research has shown that UV radiation can affect collagen and alter its molecular structure [116,117]. This contributes to the appearance of skin aging, with a reduction in skin elasticity and tone, giving way to the increased appearance of wrinkles, sagging eyelids, and bags under the eyes [118]. ...
Featured Application
The valorization of kiwi and kiwi by-products’ bioactives as ingredients in the application of functional foods and cosmetics with anti-inflammatory and antioxidant health benefits.
Abstract
Kiwi’s increased popularity as a healthy fruit with several agro-food applications has increased the amount of bio-waste produced like leaf, peel, and seed by-products, usually combined to form a kiwi pomace, which increases the environmental footprint of kiwi fruit and waste management costs. The aim of the present study is to thoroughly review and outline the nutritional content and bioactive components of both kiwi fruit and its by-products, as well as the innovative approaches to obtain and valorize kiwi’s bioactives, phytochemicals, vitamins, and nutrients in several functional food products, nutraceuticals, and cosmetics applications with health-promoting properties. The antioxidant and anti-inflammatory properties and mechanisms of action of the extracted polyphenols, flavonoids, flavones, organic acids, and other bioactive components in both the fruit and in its functional products are also elucidated. Emphasis is given to those bioactive ingredients and extracts from kiwi by-products that can be valorized in various functional foods, supplements, nutraceuticals, nutricosmetics, cosmeceuticals, and cosmetics-related applications, with antioxidant and anti-inflammatory health-promoting properties. Characteristic examples with reported health benefits are the functional kiwi fruit jelly (FKJ),fermented kiwi fruit products like wine, starchy kiwi fruit flour (SKF), and kiwi-derived functional protein bars, cheese and flour, as well as several nutraceuticals and functional cosmetics with kiwi bioactives improving their antioxidant, antiaging, and photoprotective properties, collagen synthesis, skin density, hydration, elasticity, and the wound healing process, while beneficially reducing skin roughness, wrinkles, hyperpigmentation, keratinocyte death, and DNA and cell damage. The limitations and future perspectives for these kiwi bioactive-based applications are also discussed.
... The toxic nature of such solvents and the hightemperature conditions of solubilization renders the solubilization non-sustainable and limits the applications of collagen. However, it is non-soluble in water owing to its ordered structure supported by inter-and intra-molecular H-bonds, 17 hydrophobic interactions, ionic interactions and van der Waal's forces. 18,19 Therefore, new sustainable methods of dissolution, modication or preparation/extraction of collagen peptides/ collagen hydrosylates, and subsequent regeneration need to be devised to widen the application of collagen. ...
Collagen is a protein that is hard to dissolve in water and many other solvents, which limits its applications. Herein, deep eutectic solvents (DESs), i.e. choline chloride : lactic acid (ChCl : LA) = 1 : 1 and ethylene glycol : zinc chloride (EG : ZnCl2) = 4 : 1, are effectively used to dissolve type I collagen under different conditions. Type I collagen is readily soluble at a concentration of 9.5–22.5 w/v% in DESs, and the solubility is governed by the nature of the DES, temperature (45 °C, 70 °C and 90 °C) and the absence or presence of HCl(aq.) (5 × 10⁻⁵ M). The dissolved material is regenerated by employing ethanol as an anti-solvent at 4 °C and investigated for alteration in the polymeric structure using Fourier-transform infrared spectroscopy (FTIR), circular dichroism (CD), UV-vis spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and SDS-PAGE techniques. The increase in temperature and the presence of dilute HCl(aq.) result in a relatively greater disruption of the H-bonded structure of collagen, causing the unwinding of its triple-helical structure coupled with reduction in the helical content of polyproline type-II helices, which exposed vital amino acid residues in the regenerated material. Such an unwinding is accompanied by the formation of low molecular weight polypeptides, which are readily soluble in water and show antimicrobial activity comparable to or more than that exhibited by a model antibiotic Kanamycin towards both Gram-negative and Gram-positive bacteria. DESs are reused for at least 3 cycles for collagen solubilization without alteration in their inherent structure and collagen solubilizing ability, whereas the material regenerated from reused DESs shows properties similar to that shown by the material regenerated from virgin DESs. In this manner, a new sustainable strategy for solubilizing collagen and the direct preparation of essential and active low molecular weight collagen peptides directly from collagen in a single step is established. An inventive approach to using collagen is made possible by the observation that lower molecular weight peptides formed from the sustainable dissolution of collagen with exposed aromatic amino acid residues can demonstrate antibacterial activity.
... At the molecular level, UVA is known to decrease collagen synthesis. 23 Furthermore, skin inflammation and sensitivity are increased, as measured by the skin inflammation markers interleukin-1 alpha (IL-1ɑ) and tumor necrosis factor-alpha (TNF-α), and skin sensitivity marker histamine. 24 DNA damage is detected, measured by thymine dimers. ...
Objective:
This study aimed to investigate the ultraviolet (UV) protection/repair benefits of a patented Amino Acid Complex (AAComplex).
Methods:
I) AAComplex was incubated with dermal fibroblasts, with/without UVA, and collagen I was measured with a GlasBoxPlus device. II) A lotion, with/without AAComplex (1%) was applied topically to skin explants, following UVA irradiation, and quantified for health-related biomarkers (TNFalpha, histamine, and MMP-1). III) A broad spectrum sunscreen with SPF 46 and a skincare serum containing AAComplex (2%) were assessed using epidermal equivalents, in the presence of UV irradiation, for effects on IL-1alpha, thymine dimers, Ki-67, filaggrin and Nrf2.
Results:
I) Collagen I synthesis in dermal fibroblasts was significantly decreased after UVA compared to without UV. The presence of AAComplex prevented this decrease. II) UVA irradiation of skin explants increased histamine, TNFα, and MMP-1. Hydrocortisone aceponate cream significantly decreases all 3 biomarkers. AAComplex contained lotion also significantly decreased all 3 biomarkers, the no AAComplex control lotion only reduced histamine. III) With the regimen of sunscreen + AAComplex contained skincare serum, the significant reduction in IL-1alpha was observed along with a complete recovery of Ki-67 and stimulation of filaggrin and Nrf2T. No thymine dimer positive cell was observed indicating the most positive skin impact from the regiment. Conclusion: This research using different human skin models demonstrated that AAComplex can provide protection and damage repair caused by UV, at the ingredient level also when formulated in a serum or lotion formula. Skin may be best protected from UV damage when the regimen is used. J Drugs Dermatol. 2024;23(5):366-375. doi:10.36849/JDD.7916.
... Nuzzi et al. [10] examined the vitreous proteome and found significantly increased levels of oxidative stress biomarker thiobarbituric acid-reactive substances (TBARS) both in pseudophakic eyes compared phakic eyes and in eyes with a PVD compared to those without one. An increase in reactive oxygen species has been shown to damage collagen fibrils and promote vitreous liquefaction and may be the result of pseudophakic intraocular lenses not offering the same UV photoprotection as the natural crystalline lens affected by cataract [11,12]. Further vitreous proteome analysis of pseudophakic eyes has shown altered biochemical vitreous composition and a reversal of the normal vitreous humour viscosity profile which may induce instability of the vitreous gel and consequent PVD development [13]. ...
Purpose
It is commonly accepted that phacoemulsification surgery is a risk factor for the development of posterior vitreous detachment (PVD) and may accelerate the process. This is an important consideration particularly in cases involving young patients who pre-operatively have no PVD, given the increased risk of retinal tears and detachments.
Methods
A comprehensive literature search was conducted to identify studies reporting incidence of PVD post-uncomplicated phacoemulsification surgery. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement was used for search strategy. Of 3071 titles, 7 studies met the inclusion criteria; The outcomes measured were PVD occurrence by (1) time, (2) type, (3) age, (4) gender and (5) axial length, with all statistical analysis performed using Review Manager.
Results
A total of 2034 eyes were included for analysis with a mean follow-up time of 28.3 months. 33.3% of patients developed a PVD, either partial or complete, with rates increasing in a time dependent manner. No significant difference was noted in sub-group analysis by age, gender or axial length.
Conclusions
The results from our systematic review show that uncomplicated phacoemulsification accelerates the physiological process of PVD development. Pre-operative evaluation of the vitreoretinal interface should be performed with careful post-operative follow-up advised in those without a pre-existing PVD.
... Collagen is the main structural protein of connective tissue, providing the skin with proper tension, elasticity, and flexibility. Excessive exposure to the sun, extreme temperatures, and certain compounds in cosmetics can affect the structure of collagen fibers, resulting in a worsened skin condition [29]. Collagen biosynthesis was evaluated using measurement of L-5-[ 3 H]-proline incorporation into collagen proteins. ...
The effect of Amaranthus cruentus L. seed oil (AmO) on collagen biosynthesis and wound healing was studied in cultured human dermal fibroblasts exposed to UVA radiation. It was found that UVA radiation inhibited collagen biosynthesis, prolidase activity, and expression of the β1-integrin receptor, and phosphorylated ERK1/2 and TGF-β, while increasing the expression of p38 kinase. The AmO at 0.05–0.15% counteracted the above effects induced by UVA radiation in fibroblasts. UVA radiation also induced the expression and nuclear translocation of the pro-inflammatory NF-κB factor and enhanced the COX-2 expression. AmO effectively suppressed the expression of these pro-inflammatory factors induced by UVA radiation. Expressions of β1 integrin and IGF-I receptors were decreased in the fibroblasts exposed to UVA radiation, while AmO counteracted the effects. Furthermore, AmO stimulated the fibroblast’s migration in a wound healing model, thus facilitating the repair process following exposure of fibroblasts to UVA radiation. These data suggest the potential of AmO to counteract UVA-induced skin damage.
... Furthermore, the absence of new low molecular weight bands in the lanes of the irradiated samples suggests that far-UVC radiationinduced chain scission is random and/or results in fragments smaller than 40 kDa. These results are consistent with existing literature on the effect of 221 and 254 nm UV radiation on type I collagen, which reports collagen chain scission at high fluences [33][34][35][36][37][38]. A subset of the aforementioned studies also describe UV-induced collagen cross-linking, and suggest that cross-linking dominates at low fluences and chain scission at high fluences [34,35,37]. ...
For more than 100 years, germicidal lamps emitting 254 nm ultraviolet (UV) radiation have been used for drinking-water disinfection and surface sterilization. However, due to the carcinogenic nature of 254 nm UV, these lamps have been unable to be used for clinical procedures such as wound or surgical site sterilization. Recently, technical advances have facilitated a new generation of germicidal lamp whose emissions centre at 222 nm. These novel 222 nm lamps have commensurate antimicrobial properties to 254 nm lamps while producing few short- or long-term health effects in humans upon external skin exposure. However, to realize the full clinical potential of 222 nm UV, its safety upon internal tissue exposure must also be considered. Type I collagen is the most abundant structural protein in the body, where it self-assembles into fibrils which play a crucial role in connective tissue structure and function. In this work, we investigate the effect of 222 nm UV radiation on type I collagen fibrils in vitro. We show that collagen’s response to irradiation with 222 nm UV is fluence-dependent, ranging from no detectable fibril damage at low fluences to complete fibril degradation and polypeptide chain scission at high fluences. However, we also show that fibril degradation is significantly attenuated by increasing collagen sample thickness. Given the low fluence threshold for bacterial inactivation and the macroscopic thickness of collagenous tissues in vivo, our results suggest a range of 222 nm UV fluences which may inactivate pathogenic bacteria without causing significant damage to fibrillar collagen. This presents an initial step toward the validation of 222 nm UV radiation for internal tissue disinfection.
... Collagen is the main structural protein of connective tissue, providing the skin with proper tension, elasticity, and flexibility. Excessive exposure to the sun, extreme temperatures, and certain compounds in cosmetics can affect the structure of collagen fibers, resulting in worsened skin condition [15]. Collagen biosynthesis was evaluated by measurement of L-5-[ 3 H]-proline incorporation into collagen proteins. ...
The effect of Amaranthus cruentus L. seed oil (AmO) on collagen biosynthesis and wound healing was studied in cultured human dermal fibroblasts exposed to UVA radiation. It has been found that UVA radiation inhibited collagen biosynthesis, prolidase activity, expression of β1-integrin receptor, phosphorylated ERK1/2 and TGF-β, while increased the expression of p38 kinase. The AmO at 0.05-0.15% counteracted the above effects induced by UVA radiation in fibroblasts. UVA radiation also induced the expression and nuclear translocation of pro-inflammatory NF-κB fac-tor and enhanced the COX-2 expression. AmO effectively suppressed the expression of these pro-inflammatory factors induced by UVA radiation. Expressions of β1 integrin and IGF-I re-ceptors were decreased in the fibroblasts exposed to UVA radiation, while AmO counteracted the effects. Furthermore, AmO stimulated fibroblast’s migration in a wound healing model, thus facilitating the repair process following exposure of fibroblasts to UVA radiation. This data suggest the potential of AmO to counteract UVA-induced skin damage.
... The amount of collagen in the skin is not fixed and can be lost due to a variety of factors such as age, photodamage, physical trauma, etc. Of these, collagen loss due to aging is the most prevalent and unavoidable (60,61). The importance of collagen to the structure of the skin has been proven in many ways, and its content in the skin directly reflects the health of the skin. ...
Aging is a universal and irreversible process, and the skin is an important feature that reflects the aging of the organism. Skin aging has been a focus of attention in recent years because it leads to changes in an individual’s external features and the loss of many important biological functions. This experiment investigated the improvement effect of black tea extract (BTE) on the skin of aging mice under D-galactose induction. After 6 weeks of administration, the changes in skin bio-chemical indices and tissue structure were compared with the blank and positive control groups. It was observed that BTE increased water and hyaluronic acid (HA) content, decreased malondialdehyde (MDA) content, enhanced superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities in the skin of aging mice, and improved the structure of aging damaged skin tissues and increased the content of total collagen. The experimental results showed that BTE can play a significant anti-aging effect on the skin, which can be used as a functional food for aging inhibition.
... Biomimetic hydrogels can exhibit extensive background absorbance when using UV-based imaging techniques, making the quantitative study of drug diffusion from solution to gel challenging [10,35]. In addition, extended UV-light exposure may be detrimental for the drug and the hydrogels as well as any added human cells [10,36]. By using a fluorescence-based technique and developing a miniaturized drug diffusion and cellular uptake chip, these limitations were mitigated. ...
Novel tumor-on-a-chip approaches are increasingly used to investigate tumor progression and potential treatment options. To improve the effect of any cancer treatment it is important to have an in depth understanding of drug diffusion, penetration through the tumor extracellular matrix and cellular uptake. In this study, we have developed a miniaturized chip where drug diffusion and cellular uptake in different hydrogel environments can be quantified at high resolution using live imaging. Diffusion of doxorubicin was reduced in a biomimetic hydrogel mimicking tissue properties of cirrhotic liver and early stage hepatocellular carcinoma (373 ± 108 µm ² /s) as compared to an agarose gel (501 ± 77 µm ² /s, p = 0.019). The diffusion was further lowered to 256 ± 30 µm ² /s ( p = 0.028) by preparing the biomimetic gel in cell media instead of phosphate buffered saline. The addition of liver tumor cells (Huh7 or HepG2) to the gel, at two different densities, did not significantly influence drug diffusion. Clinically relevant and quantifiable doxorubicin concentration gradients (1–20 µM) were established in the chip within one hour. Intracellular increases in doxorubicin fluorescence correlated with decreasing fluorescence of the DNA-binding stain Hoechst 33342 and based on the quantified intracellular uptake of doxorubicin an apparent cell permeability (9.00 ± 0.74 × 10 –4 µm/s for HepG2) was determined. Finally, the data derived from the in vitro model were applied to a spatio-temporal tissue concentration model to evaluate the potential clinical impact of a cirrhotic extracellular matrix on doxorubicin diffusion and tumor cell uptake.
Graphical abstract
... Fully formed fibrils range from 30 31 to 300 nm in diameter and are stabilized by non-covalent interactions between collagen 32 molecules [29][30][31]. In the ECM, collagen fibrils form a network which can be modelled 33 experimentally by a fibrillar gel [32] (Fig. 1). To the authors' knowledge, this study presents the first investigation into the effect 35 of 222 nm far-UVC radiation on type I collagen. ...
For more than 100 years, germicidal lamps emitting 254 nm ultraviolet (UV) radiation have been used for drinking-water disinfection and surface sterilization. However, due to the carcinogenic nature of 254 nm UV, these lamps have been unable to be used for clinical procedures such as wound or surgical site sterilization. Recently, technical advances have facilitated a new generation of germicidal lamp whose emissions centre at 222 nm. These novel 222 nm lamps have commensurate antimicrobial properties to 254 nm lamps while producing few short- or long-term health effects in humans upon external skin exposure. However, to realize the full clinical potential of 222 nm UV, its safety upon internal tissue exposure must also be considered. Type I collagen is the most abundant structural protein in the body, where it self-assembles into fibrils which play a crucial role in connective tissue structure and function. In this work, we investigate the effect of 222 nm UV radiation on type I collagen fibrils in vitro . We show that collagen’s response to irradiation with 222 nm UV is fluence-dependent, ranging from no detectable fibril damage at low fluences to complete fibril degradation and polypeptide chain scission at high fluences. However, we also show that fibril degradation is significantly attenuated by increasing collagen sample thickness. Given the low fluence threshold for bacterial inactivation and the macroscopic thickness of collagenous tissues in vivo , our results suggest a range of 222 nm UV fluences which may inactivate pathogenic bacteria without causing significant damage to fibrillar collagen. This presents an initial step toward the validation of 222 nm UV radiation for internal tissue disinfection.
... Although the collagen content of the skin normally diminishes with age due to decreased synthesis by dermal broblasts and increased degradation by collagenases, 6 the process is accelerated by UV-R-induced free radicals. 7,8 Moreover, the ensuing tissue repair response to oxidative stress greatly enhances the activity of collagenases, furthering collagen loss. 9 Accordingly, the additive effects of age and UV-R greatly reduce the collagen content in the skin, lessening the structural integrity of the dermis, thereby causing accelerated wrinkle formation. ...
Purpose:
A rise in market demand for anti-aging skin care products has resulted in a proliferation of cosmeceuticals, including products that contain vitamin C. Many topicals containing vitamin C claim to reduce the appearance of wrinkles. However, these claims have not been systematically evaluated.
Methods:
A systematic review of literature published between January 2015 and September 2022 was performed per PRISMA guidelines. Scopus, Web of Science, and PubMed were queried for records relevant using the following Medical Subject Heading (MeSH) terms: “Topical Vitamin C OR Ascorbic acid”, “Vitamin C efficacy”, “dermatology”, “cosmetology”, and “skin anti-aging”. Variables of interest included: study type, study location, study duration, sample size, patient description, type and ingredients of the topical formulation, outcome measurement, results, and adverse events.
Results:
After deduplication, consideration of inclusion and exclusion criteria, and title/abstract screening, 5,428 initial records were reduced to 7 articles, including 4 meeting Level IB criteria, one meeting Level IIA criteria, and 2 meeting Level IIB criteria. Methods for assessing clinical improvements included global photodamage score, skin topography assessment, reflectance confocal microscopy (RCM) skin analysis, Dynamical Atlas, and participant self-assessment. Conclusions: While 4 of the 7 studies met Level IB evidence, further high-quality, prospective, and comparative studies are indicated to better elucidate the role of topical vitamin C in wrinkle reduction. All the studies used vitamin C in combination with other ingredients or therapeutic mechanisms, thereby complicating any specific conclusions regarding the efficacy of vitamin C. Citation: Sanabria B, Berger LE, Mohd H, et al. Clinical efficacy of topical vitamin C on the appearance of wrinkles: a systematic literature review. J Drugs Dermatol. 2023;22(9):898-904. doi:10.36849/JDD.7332.
... Although the collagen content of the skin normally diminishes with age due to decreased synthesis by dermal broblasts and increased degradation by collagenases, 6 the process is accelerated by UV-R-induced free radicals. 7,8 Moreover, the ensuing tissue repair response to oxidative stress greatly enhances the activity of collagenases, furthering collagen loss. 9 Accordingly, the additive effects of age and UV-R greatly reduce the collagen content in the skin, lessening the structural integrity of the dermis, thereby causing accelerated wrinkle formation. ...
... The remodeling of the ECM is due to the upregulation of matrix metalloproteinases (MMPs) and decreased collagen synthesis (in particular, type I [16]), inhibitors of matrix metalloproteinases (TIMPs), and transforming grow factor-β (TGF-β) [17][18][19]. ...
The effects of UV radiation on the skin and its damage mechanisms are well known. New modalities of exogenous photoprotection have been studied. It was demonstrated that Polypodium leucotomos extract acts as an antioxidant, photoprotectant, antimutagenic, anti-inflammatory, and immunoregulator. It is effective when taken orally and/or applied topically to support the prevention of skin cancers. It also has an important role in preventing photoaging. This review aims to report the mechanisms through which Polypodium leucotomos acts and to analyze its uses in oncodermatology with references to in vitro and in vivo studies. Additionally, alternative uses in non-neoplastic diseases, such as pigmentary disorders, photosensitivity, and atopic dermatitis, have been considered.
... In addition, UV light is highly toxic, and free radicals are produced during UV light irradiation. The free radicals may cause progressive damage to human skin, 70 destroy the structure of vitamin A 71 and vitamin C, 72 damage the structure of collagen, 73 and even lead to more serious genetic damages. 74 There is no doubt that visible light is less toxic than UV light, 75 and the visible light can penetrate deeper tissue. ...
Bio-based stimuli responsive materials have been widely studied as highly versatile materials in biomedical applications. In this review, different types of bio-based stimuli-responsive materials are introduced (most of them are carbohydrate polymers). The response mechanisms are explained and the advantages/drawbacks of the materials are discussed. Particularly in bio-based stimuli-responsive drug delivery and in bio-based drug anticounterfeiting fields, the response mechanisms and advantages are discussed, and the shortcomings are also mentioned.
... Furthermore, it was observed that at longer UV irradiation intervals the swelling capacity decreases, more significantly in 3D-printed Col scaffolds. According to DSC results, UV radiation causes a possible collapse of the structure and damage of collagen [55,56]. ...
UV-irradiation method has grown as an alternative approach to in situ synthetize silver nanoparticles (AgNPs) for avoiding the use of toxic reducing agents. In this work, an antimicrobial material by in situ synthesizing AgNPs within 3D-printed collagen-based scaffolds (Col-Ag) was developed. By modifying the concentration of AgNO3 (0.05 and 0.1 M) and UV irradiation time (2 h, 4 h, and 6 h), the morphology and size of the in situ prepared AgNPs could be controlled. As a result, star-like silver particles of around 23 ± 4 μm and spherical AgNPs of 220 ± 42 nm were obtained for Ag 0.05 M, while for Ag 0.1 M cubic particles from 0.3 to 1.0 μm and round silver precipitates of 3.0 ± 0.4 μm were formed in the surface of the scaffolds at different UV irradiation times. However, inside the material AgNPs of 10–28 nm were obtained. The DSC thermal analysis showed that a higher concentration of Ag stabilizes the 3D-printed collagen-based scaffolds, while a longer UV irradiation interval produces a decrease in the denaturation temperature of collagen. The enzymatic degradation assay also revealed that the in situ formed AgNPs act as stabilizing and reinforcement agent which also improve the swelling capacity of collagen-based material. Finally, antimicrobial activity of Col-Ag was studied, showing high bactericidal efficiency against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. These results showed that the UV irradiation method was really attractive to modulate the size and shape of in situ synthesized AgNPs to develop antimicrobial 3D-printed collagen scaffolds with different thermal, swelling and degradation properties.
... Notably, chronic ultraviolet (UV) exposure determines an impairment in collagen deposition and distribution [70,71]. UV-A radiation seems to be mostly responsible for inducing wrinkling pigmentary changes and loss of elasticity, due to its penetration deep in the dermis [72,73]. ...
Adipose-derived stromal cells (ADSCs) have well-established regenerative and immunomodulatory properties. For such reasons, ADSCs are currently under investigation for their use in the setting of both regenerative medicine and autoimmune diseases. As per dermatological disorders, MSC-based strategies represent potential therapeutic tools not only for chronic ulcers and wound healing, but also for immune-mediated dermatoses. However, a growing body of research has been focusing on the role of MSCs in human cancers, due to the potential oncological risk of using MSC-based strategies linked to their anti-apoptotic, pro-angiogenic and immunosuppressive properties. In the dermatological setting, ADSCs have shown not only to promote melanoma growth and invasiveness, but also to induce drug-resistance. On the other hand, genetically modified ADSCs have been demonstrated to efficiently target therapies at tumor sites, due to their migratory properties and their peculiar tropism for cancer microenvironment. The present review briefly summarizes the findings published so far on the use of ADSCs in the dermato-oncological setting, with the majority of data being available for melanoma.
... The enhancement of kidney functions was attributed to the antioxidant property of ADE. It was reported that, UV radiation-induced structural changes include modifications and fragmentation of collagen monomers (Jariashvili et al. 2012). These changes may have functional consequences impacting collagen functions as mechanical properties, resistance to protease digestion (Rabotyagova et al. 2008). ...
Date was considered a high nutritional value fruit due to its high content of active ingredients. Frequent exposure to cosmetic radiations including UVC caused deleterious effects and tissue damage and organ affection. This study investigated the efficacy of Ajwa date extract (ADE) in protection against UVC-induced kidney injury in rats. Five groups of rats were included in this study. Group I: Rats were exposed to UVC radiation at a dose 5 kJ (1 h/day) for 28 days. Group II: Rats were pretreated orally with ADE (10 mg/kg/day) 1 h before exposure to UVC radiation with dose 5 kJ. Group III: Rats were pretreated with ADE (15 mg/kg) 1 h before exposure to UVC radiation. Group IV: Rats were exposed to UVC radiation then treated with ADE (10 mg/kg). Group V: Rats exposed to UV radiation then treated with ADE (15 mg/kg) after 1 h from exposure. Analyzing the active constituents of ADE by GC/MS showed that, quercetin, myricetin kaempferol, thymine, and catechol are the most active ingredients. Biochemical markers obtained showed that, serum 8-oxoguanine as marker for DNA damage was increased, and total antioxidant activity and glutathione reduced were decreased (p < 0.01), while neutrophil (p < 0.001), conjugated diene (p < 0.05), and interferon-γ (p < 0.01) were increased after exposure to UVC. However, all the parameters changed were reversed by ADE-treated rats compared with untreated; the higher dose was more effective and protective effect was better than treated effect. Kidney total proteins and reduced glutathione and procollagen levels were decreased while malondialdehyde was increased after exposure to UVC (p < 0.01). These abnormalities were normalized by ADE treatment and protected. It was concluded that, flavonoids from Ajwa extract protected against deleterious effects of UVC by enhancing antioxidant activities and reducing infiltration of neutrophils that caused kidney injury.
... In addition, UV irradiation is also used for science purposes (e.g., cross-linking and sterilizing procedures) [85][86][87]. As UV can cause significant structural and mechanical alterations in collagen properties [88][89][90][91], it is significant to investigate these alterations using cutting edge scientific methods such as the AFM indentation method. Furthermore, the nanomechanical properties determi-nation of the basilar membrane after cochlear implantation reveals localized stiffening. ...
Atomic Force Microscopy nanoindentation method is a powerful technique that can be used for the nano-mechanical characterization of bio-samples. Significant scientific efforts have been performed during the last two decades to accurately determine the Young’s modulus of collagen fibrils at the nanoscale, as it has been proven that mechanical alterations of collagen are related to various pathological conditions. Different contact mechanics models have been proposed for processing the force–indentation data based on assumptions regarding the shape of the indenter and collagen fibrils and on the elastic or elastic–plastic contact assumption. However, the results reported in the literature do not always agree; for example, the Young’s modulus values for dry collagen fibrils expand from 0.9 to 11.5 GPa. The most significant parameters for the broad range of values are related to the heterogeneous structure of the fibrils, the water content within the fibrils, the data processing errors, and the uncertainties in the calibration of the probe. An extensive discussion regarding the models arising from contact mechanics and the results provided in the literature is presented, while new approaches with respect to future research are proposed.
... The biomimetic gels used in this study are previously uncharacterised in terms of their UV-absorbance properties or UV signal stability. As one of the two main components, collagen has been reported as UV sensitive (random cleavage of peptide bonds) at wavelengths close to 250 nm (Jariashvili et al., 2012;Miles et al., 2000). Our initial studies showed that collagen at acidic pH (3.4 -4.2)) had very low UV-absorbance (<0.1) at 280, 300 and 320 nm and low absorbance (<0.25) at 255 nm (data not shown) ("Collagen Type I, Rat Tail | 3D Cell Figure 5. UV absorbance profiles at 255, 280, 300 and 320 nm for the biomimetic hydrogels A: fibrosis gel and B: cirrhosis gel as well as UV-stability of the C: fibrinogen stock solution. ...
Hydrogels of varying complexity are routinely used as scaffolds and 3D structures for in vitro tumor models to increase physiological relevance within pre-clinical cancer research. Relatively simple hydrogels such as agarose are well characterised, meanwhile biomimetic gels containing collagen and fibrin(ogen) have been studied to a much lesser extent. In this study, hydrogels mimicking the biophysical characteristics of liver cancer progression were investigated in terms of their UV-properties and influence on diffusion coefficients of different substances. UV-imaging technology was used to both visualize and quantify the diffusion process in a simple and rapid way. In general, agarose gel diffusion agreed well with predictions using the Stokes-Einstein equation meanwhile the biomimetic gels reduced diffusion coefficients by up to 70%. For doxorubicin, spatio-temporal tissue concentration modelling was used to translate in vitro diffusion to the more clinical context of tumor penetration in a solid liver tumor supplied by arterial blood.
... It is important to note that in preventive treatment cells are supported in the basic functions of energy production, associated with mitochondrial health and cellular self-renewal and detoxification as cellular readouts. If MeO-MBM improves the overall health status of various cell types in skin, the assumption was that with beneficial properties of an active ingredient after UV irradiation, the development of inflammatory reactions and the build-up of edema were decreased by reducing the blood flow in living skin, as healthy skin has optimal nutrient and oxygen supply to support the vital functions of the different cell types in skin more quickly and counteracts the stress more efficient [31][32][33]. Therefore, we conducted an in vivo study to determine the effect of MeO-MBM on the microcirculation of blood compared to hydrocortisone, a well-described anti-inflammatory drug, to reduce signs of UV-induced skin irritation. ...
IntroductionSun protection is important in skin care and requires special attention as inefficient protection might trigger skin pathologies including polymorphic light eruption (PLE). The reduce-improve-protect (RIP) concept to avoid the onset of ultraviolet (UV) irradiation-induced diseases or damage to human skin is important. Methoxy-monobenzoylmethane (MeO-MBM), which is neither a UVB nor a UVA filter, converts to the UV filter avobenzone under UV irradiation and further acts as a photoantioxidant during its conversion process and initially as an antioxidant material. The aim of this study was to understand the mechanisms by which MeO-MBM improves the condition of UV-stressed skin through its photoantioxidant properties. The improvement of the skin condition by the activity of MeO-MBM as active ingredient was also investigated.Methods
Potential molecular targets were identified by in silico docking to numerous cellular membrane receptors on the cell surface or nuclear membrane, followed by microarray analysis of 164 genes after MeO-MBM treatment of normal human epidermal keratinocytes (NHEK). We conducted randomized, double-blinded, intra-individual comparison vs. placebo studies on ten volunteers, aged between 34 and 65 years, to assess the effect of MeO-MBM in vivo. The effect after UV-induced inflammation was assessed in a protective and curative set-up with 2% MeO-MBM vs. 1% hydrocortisone and placebo based on the change in blood flow. The barrier function of the skin was assessed by the change in transepidermal water loss (TEWL), skin scaling and skin thickness after the treatment with MeO-MBM. Additionally, the effect of MeO-MBM after UV-induced stress on the activation of ferritin in human explants was determined ex vivo.ResultsA docking simulation of MeO-MBM showed a potential interaction with the retinoic acid receptor gamma and further revealed downregulation of proteins related to inflammation. In the protective treatment set-up, after 24 h MeO-MBM significantly reduced the delta blood flow compared to placebo, while this reduction was more prominent with hydrocortisone. In the curative treatment set-up, a greater reduction in delta blood flow was also observed with MeO-MBM compared to placebo and similar to hydrocortisone. Treatment with MeO-MBM revealed an improvement in skin barrier function as a result of decreased TEWL, reduced skin scaling and increased skin thickness. Immunohistochemistry staining of ferritin on human skin explants further showed that the treatment with MeO-MBM reduced the ferritin expression.Conclusion
Based on these results, MeO-MBM is capable of exerting an anti-aging activity via the retinoic acid receptor gamma. Its anti-inflammatory and anti-oxidative activity manifested via the downregulation of multiple anti-inflammatory genes as well as the reduction of ferritin in skin tissue. This study shows that the multidimensional functionality of MeO-MBM offers an effective approach to combat acute and chronic deleterious effects of oxidative UV damage while simultaneously enhancing the skin barrier function.
... Collagen mimetic peptides commonly contain multiple repeats of the tri-peptide sequence (Gly-X-X') which is a key motif in collagen fibrils [93]. Experiments using these peptides show that molecules rich in the repeating collagen motif are relatively resistant to environmental doses of UVR and require much higher doses (9000 J/cm 2 ) [147] or shorter wavelengths (254 nm) [70,200] to elicit changes in their ultrastructure. Higher order proteins structures are however important as purified collagen gels, exhibited increased stiffness and reduced elasticity after exposure to physiological doses of UVB [201]. ...
Exposure to sub-lethal doses of ionising and non-ionising electromagnetic radiation can impact human health and well-being as a consequence of, for example, the side effects of radiotherapy (therapeutic X-ray exposure) and accelerated skin ageing (chronic exposure to ultraviolet radiation: UVR). Whilst attention has focused primarily on the interaction of electromagnetic radiation with cells and cellular components, radiation-induced damage to long-lived extracellular matrix (ECM) proteins has the potential to profoundly affect tissue structure, composition and function. This review focuses on the current understanding of the biological effects of ionising and non-ionising radiation on the ECM of breast stroma and skin dermis, respectively. Although there is some experimental evidence for radiation-induced damage to ECM proteins, compared with the well-characterised impact of radiation exposure on cell biology, the structural, functional, and ultimately clinical consequences of ECM irradiation remain poorly defined.
... Deidentified 62-year-old abdominal cadaveric human fullthickness skin was obtained from ConnectLife, NY. For our study, abdominal tissue was chosen because it is an anatomical site that typically experiences little ultraviolet radiation from the sun, which is known to induce collagen degradation [62,63]. In accordance with the Department of Health and Human Services regulations, 45 CFR 46.101:b:4, an exempt approval (3002-13) was attained to perform research using deidentified tissue samples. ...
Chronological skin aging is a complex process that is controlled by numerous intrinsic and extrinsic factors. One major factor is the gradual degradation of the dermal collagen fiber network. As a step toward understanding the mechanistic importance of dermal tissue in the process of aging, this study employs analytical and multiscale computational models to elucidate the effect of collagen fiber bundle disintegration on the mechanical properties and topography of skin. Here, human skin is modeled as a soft composite with an anisotropic dermal layer. The anisotropy of the tissue is governed by collagen fiber bundles with varying densities, average fiber alignments, and normalized alignment distributions. In all finite element models examined, collagen fiber bundle degradation results in progressive decreases in dermal and full-thickness composite stiffness. This reduction is more profound when collagen bundles align with the compression axis. Aged skin models with low collagen fiber bundle densities under compression exhibit notably smaller critical wrinkling strains and larger critical wavelengths than younger skin models, in agreement with in vivo wrinkling behavior with age. The propensity for skin wrinkling can be directly attributable to the degradation of collagen fiber bundles, a relationship that has previously been assumed but unsubstantiated. While linear-elastic analytical models fail to capture the postbuckling behavior in skin, nonlinear finite element models can predict the complex bifurcations of the compressed skin with different densities of collagen bundles.
... Thus, a set of experiments at increasing linker:gelatin ratios was planned, i.e., 100 mg of dry gelatin in the presence of 1, 2, 5, and 10 µmol of cross linker (the use of 20 µmol results in a heterogeneous mixture for almost every compound). Before the UV irradiation of gelatin-tetrazole homogeneous DMSO solution, it is important to remove oxygen from the reaction environment, together with a reduction in the UV-C component, in order to avoid UV-related oxidative damage to the polypeptide network [66][67][68]. Therefore, the solutions were bubbled with flowing nitrogen for 15 min before irradiation and maintained under an inert atmosphere during the photoinduced reaction. ...
Gelatin is a costless polypeptide material of natural origin, able to form hydrogels that are potentially useful in biomaterial scaffold design for drug delivery, cell cultures, and tissue engineering. However, gelatin hydrogels are unstable at physiological conditions, losing their features only after a few minutes at 37 °C. Accordingly, treatments to address this issue are of great interest. In the present work, we propose for the first time the use of bi- and trifunctional tetrazoles, most of them unknown to date, for photoinduced gelatin cross-linking towards the production of physiologically stable hydrogels. Indeed, after UV-B irradiation, aryl tetrazoles generate a nitrilimine intermediate that is reactive towards different functionalities, some of them constitutively present in the amino acid side chains of gelatin. The efficacy of the treatment strictly depends on the structure of the cross-linking agent used, and substantial improved stability was observed by switching from bifunctional to trifunctional cross-linkers.
... Recent work by Schuh et al. has observed that type-I collagen crosslinking impacts adhesion and biofilm formation of S. mutans and S. sanguinis in an in-vitro model, and that strong crosslinking of the collagen matrix results in a significant reduction of biofilm formation for both initial colonizers (Schuh et al. 2021). It remains highly likely that modifications of collagen by genetic diseases (Ibrahim et al. 2019), UV exposure (Jariashvili et al. 2012), and radiation therapy (Gonz Alez-Arriagada et al. 2019; Muñoz et al. 2020), amongst others, will also impact bacterial adhesion and biofilm formation. However, further research is necessary to explore the impact of these factors in diseases such as dental caries and periodontal disease. ...
Collagen is the most abundant structural protein in the body and the main component of the extracellular matrix of most tissues, including dentine and periodontal tissues. Despite the well-characterized role of collagen and specifically type-I collagen, as a ligand for host cells, its role as a substrate for bacterial adhesion and biofilm formation is less explored. Therefore, the purpose of this review is to discuss recent findings regarding the adhesion of oral bacteria to collagen surfaces and its role in the progression and severity of oral and systemic diseases. Initial oral colonizers such as streptococci have evolved collagen-binding proteins (cbp) that are important for the colonization of dentine and periodontal tissues. Also, periodontal pathogens such as Porphyromonas gingivalis and Tannerella forsythia utilise cbps for tissue sensing and subsequent invasion. The implications of bacteria-collagen coupling in the context of collagen biomaterials and regenerative dentistry approaches are also addressed. Furthermore, the importance of interdisciplinary techniques such as atomic force microscopy for the nanocharacterization of bacteria-collagen interactions is also considered. Overall, understanding the process of oral bacterial adhesion onto collagen is important for developing future therapeutic approaches against oral and systemic diseases, by modulating the early stages of biofilm formation.
... However, the exposed treatment exhibited an overall higher mortality (50%) relative to the other treatments, indicating that high light intensities at noon may be detrimental to the juveniles. The body walls of stichopodid sea cucumbers are composed of type 1 collagen (Abedin et al. 2013;Cui et al. 2007;Zhong et al. 2015), which are known to undergo extreme damage when exposed to UV light (Jariashvili et al. 2012;Miles et al. 2000). Physiological stress and tissue damage due to UV exposure may have caused the juvenile mortalities observed in the exposed treatment. ...
Stichopus cf. horrens is an emergent culture species. It is known to be nocturnal and negatively phototactic; hence, determining its behavioral and growth responses to different light regimes is essential in optimizing culture protocols. This study examined the interactive effects of shading and relative food availability on the feeding pattern, absolute growth rates, and survival of juvenile S. cf. horrens. Six-month-old juveniles (4.27 to 19.41 g) were reared in replicate aquaria with three different shading treatments (covered, exposed, and half-covered aquaria) under ambient light conditions for 30 days. Juveniles in the exposed treatment with high microalgal biomass (13.44 ± 4.57 mg/g) had the highest growth rates (0.10 ± 0.05 g/day) but also the highest mortality (50%). In contrast, juveniles in the covered treatment had the lowest growth (−0.07 ± 0.03 g/day) but the highest survival (100%). Growth rates in the half-covered treatment were comparable with the exposed, and survival was higher than in the covered treatment. These indicate a trade-off between growth associated with more food and mortality risks due to light-induced stress. Juveniles in the half-covered treatment showed a significant preference to stay in the shaded portion whenever they were inactive during the day, suggesting avoidance to high light intensities (4726.51 ± 1582.43 Lux). Results of this study suggest that careful calibration of light intensities in nursery systems may help enhance juvenile growth. For indoor systems that may have limited space or surfaces for microalgal growth, cultured benthic diatom can be added to the partially covered tanks to increase the food available for the juveniles.
Numerous physiological processes in the human skin are mediated by nitric oxide, a gaseous signalling molecule. Almost every type of skin cell may produce nitric oxide, it is possible to generate nitric oxide without the need of enzymes. Nitric oxide plays a crucial role in regulating apoptosis, keratinocyte differentiation and proliferation, the protective properties of the epidermal barrier, and the structure and functions of the microcirculatory bed. Nitric oxide is involved in immunological and inflammatory responses, hair growth regulation, and wound healing processes. It mediates ultraviolet-induced processes such as erythema and edema development and participates in melanogenesis. Furthermore, the ability of nitric oxide to bind reactive oxygen species and prevent lipid peroxidation gives it antioxidant qualities. This coordinated action of nitric oxide on gene expression and membrane integrity effectively protects cells from ultraviolet A-induced apoptosis and necrosis. Furthermore, nitric oxide can be considered as a molecule that inhibits the development of cancer and photoaging. It directly harms microorganisms and indirectly activates the immune system, exhibiting antibacterial, antiviral, and antifungal qualities. Notably, nitric oxide is effective against antibiotics-resistant bacteria. All of the aforementioned findings suggest that nitric oxide is a gaseous mediator that can protect skin function.
The proof of principle of the therapeutic potential of heat shock protein 47 (HSP47) for diseases characterized by defects in collagen I synthesis is here demonstrated in osteogenesis imperfecta (OI), a prototype of collagen disorders. Most of the OI mutations delay collagen I chain folding, increasing their exposure to posttranslational modifications that affect collagen secretion and impact extracellular matrix fibril assembly. As a model, we used primary fibroblasts from OI individuals with a defect in the collagen prolyl 3-hydroxylation complex, since they are characterized by the synthesis of homogeneously overmodified collagen molecules. We demonstrated that exogenous recombinant HSP47 (rHSP47) is taken up by the cells and localizes at the ER exit sites and ER-Golgi intermediate compartment. rHSP47 treatment increased collagen secretion, reduced collagen posttranslational modifications and intracellular collagen retention, and ameliorated general ER proteostasis, leading to improved cellular homeostasis and vitality. These positive changes were also mirrored by an increased collagen content in the OI matrix. A mutation-dependent effect was found in fibroblasts from 3 probands with collagen I mutations, for which rHSP47 was effective only in cells with the most N-terminal defect. A beneficial effect on bone mineralization was demonstrated in vivo in the zebrafish p3h1-/- OI model.
Stichopus cf. horrens is an emerging sea cucumber species in tropical aquaculture. However, stocking density must be optimized. This study investigated the effects of stocking density (278 ind. m−2, 556 ind. m−2, and 1111 ind. m−2) and the presence or absence of polyvinyl chloride (PVC) pipes as shelters on the growth performance and survival of juveniles (0.4 to 1.0 cm) in the field over 30 days. The activity pattern, sheltering behavior, and aggregation density of juveniles (1.5 to 2.0 cm) at different stocking densities (144 ind. m−2, 289 ind. m−2, and 578 ind. m−2) were further evaluated in the laboratory for 15 days. Results revealed negative density-dependent effects on the absolute growth rate (AGR) and the coefficient of variation in length among the juveniles. The presence of PVC pipes did not significantly improve AGR of juveniles in all density treatments by day 30. However, survival rates were higher in sheltered treatments compared to the non-sheltered. During inactive hours, aggregations of juveniles were observed on the undersides of the PVC pipes, with high-density aggregations prevalent only at medium and high stocking densities, but not at low stocking densities. The direct physical contact during these aggregations likely exacerbated the effects of crowding and increased the risk of exposure to the cytotoxic chemicals produced by conspecifics. Designing shelter models that reduce the probability of encounter during shelter-seeking, while enhancing epiphytic growth and grazing efficiency, is crucial for mitigating the negative effects of density on this high-value sea cucumber species.
Leather tanning involves several processes of converting putrescible hide to stable leather resistant to harsh environmental conditions. Severe conditions such as high temperatures and UV radiation, when exposed to the leather materials, cause degradation and decrease physical, chemical, and structural properties. The effect of gamma irradiation on viscoelastic properties and stability of tanned leather against thermal and photodegradation was studied using the Dynamic Mechanical Analysis (DMA) technique. The thermal stability of chrome and mimosa-tanned leather was inferred from the peak of storage modulus graphs. Gamma irradiation of samples with low doses increased the storage modulus of chrome and mimosa-tanned leathers. Doses up to 20 kGy decreased the stability of thermally aged chrome-tanned leather. However, for mimosa-tanned, there was an increase at higher doses as a result of gamma irradiation inducing additional bonds that enhance the stability of the tanned leather. Nevertheless, there is a variation in the stability of chrome-tanned leather at different doses of irradiation.
Background
Actinidia polygama (silver vine) has been used in oriental medicine to treat gout, rheumatoid arthritis, and inflammation. Actinidia polygama water extract (APWE) is named PB203.
Objective
To investigate whether PB203 has anti-photoaging effects and to understand the molecular mechanism underlying such effects.
Methods
The antioxidant effect was assessed by 1,1-diphenyl-2-picrylhydrazyl assay and 2′,7′-dichlorodihydrofluorescein diacetate staining in ultraviolet B (UVB)-irradiated HaCaT cells with or without PB203 treatment. Type I collagen, matrix metalloproteinase-1 (MMP-1), tissue inhibitor of metalloproteinase (TIMP-1), hyaluronic acid (HA), hyaluronan synthase 1 (HAS1) and HAS2 levels were measuring by enzyme-linked immunosorbent assay or reverse transcription quantitative polymerase chain reaction. Also, we investigate the effects of PB203 on wrinkle formation, and the potential mechanisms underlying such effects were investigated in UVB-induced wrinkle mouse model mice.
Results
PB203 alleviated the UVB-induced reactive oxygen species production, phosphorylation of JNK, ERK, and p38, and formation of AP-1. In addition, PB203 inhibited the decreases in type I collagen and TIMP-1 levels, and the increase in MMP-1 levels in UVB-exposed HaCaT cells. In UVB-induced wrinkle mouse model, PB203 inhibited the decreases in elastin and type I collagen levels as well as the increases in MMP-1 expression, wrinkle formation, and skin dehydration. Furthermore, PB203 increased the expression of filaggrin, HAS1, and HAS2, improving the skin barrier function.
Conclusion
Taken together, we found that PB203 is as a potent candidate to serve as a functional ingredient or therapeutic agent to improve UVB-mediated skin aging.
Novel tumor-on-a-chip approaches are increasingly used to investigate tumor progression and potential treatment options. To improve the effect of any cancer treatment it is important to have an in depth understanding of drug diffusion, penetration through the tumor extracellular matrix and cellular uptake. In this study, we have developed a miniaturized chip where drug diffusion and cellular uptake in different hydrogel environments can be quantified at high resolution using live imaging. Diffusion of doxorubicin was reduced in a biomimetic hydrogel mimicking tissue properties of cirrhotic liver and early stage hepatocellular carcinoma (373 ± 108 µm ² /s) as compared to an agarose gel (501 ± 77 µm ² /s, p = 0.019). The diffusion was further lowered to 256 ± 30 µm ² /s ( p = 0.028) by preparing the biomimetic gel in cell media instead of phosphate buffered saline. The addition of liver tumor cells (Huh7 or HepG2) to the gel, at two different densities, did not significantly influence drug diffusion. Clinically relevant and quantifiable doxorubicin concentration gradients (1–20 µM) were established in the chip within one hour. Intracellular increases in doxorubicin fluorescence correlated with decreasing fluorescence of the DNA-binding stain Hoechst 33342, and based on the quantified intracellular uptake of doxorubicin an apparent cell permeability (9.00 ± 0.74 x 10 − 4 µm/s for HepG2) was determined. Finally, the data derived from the in vitro model were applied to a spatio-temporal tissue concentration model to evaluate the potential clinical impact of a cirrhotic extracellular matrix on doxorubicin diffusion and tumor cell uptake.
Introduction: Channa striata collagen-chitosan wound dressing (3:1 v/v) was founded contaminate by bacterial and fungal. Therefore, to suppress bacterial and fungal contamination in Channa striata collagen-chitosan composite dressing, it needs several efforts such as sterilization under Ultra-Violet Light Exposure. The study aimed to determine UV-light exposure duration to supress bacterial and fungal growth on C. striata collagen-chitosan composite dressing. Methods: C. striata collagen was extracted from skin and scales using 2% HCl for 48 hours, then neutralized using NaOH 1 M until collagen fibers appeared. Chitosan powder dissolved in 2% acetic acid. Afterward C. striata collagen and chitosan liquid (1:3 v/v) were mixed and formed until wound dressing was reached. Wound dressing was sterilized under UV exposure for 0, 5, 10, 15, and 30 minutes. Chitosan dressing was used as a negative control. Results: The results of the study showed that the total number of bacteria and fungi decreased significantly with increasing time of exposure of UV light on composites dressing with a value of p=0.001 for bacterial growth and a value of p= 0.005 for fungus growth. The UV exposure on collagen-chitosan dressing to reduce bacterial and fungal growth proved effective in 10 minutes. Conclusions: The UV light exposure treatment can reduce bacterial and fungal contamination on collagen-chitosan composites on each addition duration exposure descriptively.
Excessive ultraviolet (UV) exposure is the primary environmental factor that contributes to skin aging. Orbitides have been considered as important functional components in linseed and they are complex and multiple. In this study, linseed orbitides were divided into oxidized linseed orbitides (OLOs) and reduced linseed orbitides (RLOs), and used to investigate protection against Ultraviolet B‐induced photoaging in zebrafish. Firstly, the results of the zebrafish embryo acute toxicity test showed that the OLOs had obvious embryo toxicity compared with RLOs. And RLOs had better effect in Ultraviolet B‐treated zebrafish, which may significantly reduce the ROS levels and inhibit the degradation of collagen. Besides, we also found that RLOs could effectively inhibit the oxidation of proteins and lipids and regulate the activity of antioxidant enzymes. Furthermore, neutrophils recruitment to the dorsal and caudal fin regions was observed in UVB‐treated zebrafish, and RLOs effectively alleviated this migration. In conclusion, RLOs has strong photoprotective effects and potential to be used as antiphotoaging ingredients.
Introduction: Ultraviolet B (UVB) radiation can cause damage to the skin's dermis layer, which can lead to collagen fragmentation. Damage to collagen generates wrinkles, which are a sign of aging. Objective: The purpose of this study was to determine how Siam Weeds cream (Chromolaena odorata L.) altered the thickness and density of collagen in the skin of BALB/c mice after UVB exposure. Methods: There were four groups of 24 BALB/c mice altogether: normal control, negative control (Cream Base with UVB), positive control (UVB), and treatment (C. odorata cream and UVB). Just before and after the mice were exposed to UVB at 500 mJ/cm2, the Siam Weeds cream formulation was applied at a concentration of 1%. Mice were slaughtered, and a back skin excisional biopsy was conducted to analyze collagen. Results: the treatment group differed significantly both in thickness and density of collagen against the positive control group and the negative control group (p<0.05) and There was no statistically significant difference between the treatment and normal control groups (p<0.05). Conclusion: A 1% dosage of C. odorata cream can improve the thickness and density of collagen in UVB-exposed mice's skin.
Fish skin collagen films are widely used as adhesives in medicine and cosmetology. Ultraviolet (UV) irradiation can be considered as an effective sterilization method for biomaterials, however, it may also lead to material photodegradation. In this work, the influence of xanthohumol and propanediol on the physico-chemical properties of collagen films before and after UV irradiation was studied.
Collagen for this research was extracted from silver carp skin and thin films were fabricated by the solution casting methods.
The structure of films was researched using infrared spectroscopy. The surface properties of films were investigated using Atomic Force Microscopy (AFM) and contact angle measurements. Mechanical properties were measured as well. It was found that the addition of xanthohumol and propanediol modified the roughness of collagen films and their mechanical properties. UV irradiation led to the water loss from the film and modification of the collagen structure.
In the presence of propanediol and xanthohumol the water loss after UV irradiation was smaller than in UV-irradiated collagen films without these additives.
As a principal matrisomal protein, collagen is involved in the regulation of the structural framework of extracellular matrix (ECM) and therefore is potentially crucial in determining the biophysical character of the ECM. It has been suggested that collagen architecture plays a role in ovarian cancer development, progression and therapeutic responses which led us to examine the collagen morphology in normal and cancerous ovarian tissue. Also, the behaviour of ovarian cancer cells cultured in four qualitatively different collagen gels was investigated.
The results here provide evidence that collagen I morphology in the cancerous ovary is distinct from that in the normal ovary. Tumour-associated collagen I showed streams or channels of thick elongated collagen I fibrils. Moreover, fibril alignment was significantly more prevalent in endometrioid and clear cell cancers than other ovarian cancer subtypes. In this work, for the first-time collagen I architecture profiling (CAP) was introduced using histochemical staining, which distinguished between the collagen I morphologies of ovarian cancer subtypes. Immunohistochemical examination of ovarian normal and cancerous tissues also supported the notion that focal adhesion and Rho signalling are upregulated in ovarian cancers, especially in the high-grade serous tumours, as indicated by higher expression of p-FAK and p190RhoGEF. The results also support the concept that collagen I architecture, which might be collagen I concentration-dependent, influences proliferation in ovarian cancer cells. The study provides evidence that modification of collagen I architecture integrity is associated with ovarian cancer development and therapeutic responses.
Photoaged skin exhibits signs of inflammation, DNA damage and changes in morphology that are visible at the macroscopic and microscopic levels. Photoaging also affects the extracellular matrix (ECM) including hyaluronan (HA), the main polysaccharide component thereof. HA is a structurally simple but biologically complex molecule that serves as a water‐retaining component and provides both a scaffold for a number of the proteins of the ECM and the ligand for cellular receptors. The study provides an overview of the literature concerning the changes in HA amount, size and metabolism, and the potential role of HA in photoaging. We also suggest novel HA contributions to photoaging based on our knowledge of the role of HA in other pathological processes, including the senescence and inflammation‐triggered ECM reorganization. Moreover, we discuss potential direct or indirect intervention to mitigate photoaging that targets the hyaluronan metabolism, as well as supplementation.
Social and social–ecological network analysis (S(E)NA) have recently emerged as new methods in the environmental governance (EG) literature. By investigating networks of connections between actors, S(E)NA advances the understanding of who is involved in EG and how. We provide an overview of the EG literature applying S(E)NA and map (1) the citation network emerging from cross-references and (2) the similarity network emerging from word similarities between publications.
We show that S(E)NA application in EG is in the process of developing into a field of research where publications frequently cite each other. We identify 20 publications which occupy positions as sources, storers, or bridges of knowledge in the citation network. While we see S(E)NA applied in diverse resource contexts, these are mainly discussed on the local spatial level, with a focus on “policy” or “collaboration.” We discover that “power structures” and “the production of knowledge” are themes influencing the whole field.
Keywords: bibliometric network analysis, environmental management, Latent Dirichlet Allocation, social network analysis, topic detection.
The study of the influence of UV irradiation on collagen solutions has shown the destabilization of the collagen molecule by calorimetric method. It is reflected both in changes of thermodynamic parameters of transition (Tm, ΔH, Cp=f(t)) and in the appearance of a low temperature peak, that is practically irreversible against rescanning. All these indicate that the important defects in the molecule occur. The ESR measurements have shown that the above-mentioned thermal changes are connected with the occurrence of free radicals in solution under UV irradiation. They interact with proline (Pro) residues of the protein with the appearance of secondary free radicals, with following migration to glycine (Gly) residues. The emergence of the free radicals at the Pro and then at the Gly residues may cause the dramatic structural defect resulting from the UV irradiation, which significantly alters the network of hydrogen bonds in the triple helix of the collagen molecule. All this is connected with destabilization of the collagen molecule, because the defects in amino acid residues probably lead to cleavage of covalent bonds near the damaged sites maintaining the triple helical structure. The presence of ascorbic acid in collagen solution protects the collagen molecule from occurring of secondary free radicals.
NMR spectroscopy is used to investigate the heterotrimeric nature of a collagen model peptide. Two distinct peptide chains (A and B) were synthesized to model a site in heterotrimeric basement membrane type IV collagen. For NMR studies, four amino acids in the B chain were labeled with 15N/13C. Circular dichroism spectroscopy and differential scanning calorimetry thermal stability results on a solution with both A and B peptides (molar ratio 2A:1B) are consistent with the presence of one heterotrimeric triple-helical molecular species. Heteronuclear single quantum coherence experiments on homotrimers of the B peptide show trimer peaks which disappear at temperatures higher than 10 degrees C, while the 2A:1B mixture has trimer peaks with increased stability and altered chemical shifts. The reduction in the number of Leu trimer peaks from three to one and the increased stability of trimer resonances confirm the participation of B chains in an AAB heterotrimer molecule.
Procedures for the preparation of soluble collagen from rat skin and tail tendon were reviewed and revised to permit the preparation of native monomeric collagen with intact nonhelical ends. The degree of intactness was estimated from the tyrosine content, which is present only in the nonhelical ends, and by mobility of the COOH-terminal cyanogen bromide peptide of the alpha1 chain on sodium dodecyl sulfate gels. The amount of covalently cross-linked polymeric material present was estimated by molecular sieve chromatography of denatured samples. Rapid purification in the cold was sufficient to prevent or greatly reduce proteolytic alteration. Fractionation by salt precipitation at acid pH was effective in reducing the content of polymeric material. Rat tail tendon yielded completely intact native collagen, but some high molecular weight aggregates remained. Collagen from the skin of lathyritic rats was easier to obtain free of aggregates, but contained about 1 less tyrosine residue per alpha1 chain even when isolated in the presence of enzyme inhibitors. Proton NMR spectra of denatured acidic solutions of these preparations showed that 4 to 5 tyrosine residues per alpha chain were present, confirming the chemical analysis. Spectra of the native molecule showed that about the same number of tyrosine residues per chain are in rapid motion, unlike residues in the helical portion of the molecule, a result which shows that the nonhelical ends of the native molecule are unstructured in acidic solution.
The 2 A crystal structure reported here of the collagen-like model peptide, T3-785, provides the first visualization of how the sequence of collagen defines distinctive local conformational variations in triple-helical structure.
Differential scanning calorimetry has revealed the presence of a new denaturation endotherm at 32 °C following UV irradiation
of collagen, compared with 39 °C for the native triple helix. Kinetic analyses showed that the new peak was a previously unknown
intermediate state in the collagen helix-coil transition induced by UV light, and at least 80% of the total collagen was transformed
to random chains via this state. Its rate of formation was increased by hydrogen peroxide and inhibited by free radical scavengers.
SDS-polyacrylamide gels showed evidence of competing reactions of cross-linking and random primary chain scission. The cross-linking
was evident from initial gelling of the collagen solution, but there was no evidence for a dityrosine cross-link. Primary
chain scission was confirmed by end group analysis using fluorescamine. Electron microscopy showed that the segment long spacing
crystallites formed from the intermediate state were identical to the native molecules. Clearly, collagen can undergo quite
extensive damage by cleavage of peptide bonds without disorganizing the triple helical structure. This leads to the formation
of a damaged intermediate state prior to degradation of the molecules to short random chains.
Interest in self-association of peptides and proteins is motivated by an interest in the mechanism of physiologically higher
order assembly of proteins such as collagen as well as the mechanism of pathological aggregation such as β-amyloid formation.
The triple helical form of (Pro-Hyp-Gly)10, a peptide that has proved a useful model for molecular features of collagen, was found to self-associate, and its association
properties are reported here. Turbidity experiments indicate that the triple helical peptide self-assembles at neutral pH
via a nucleation-growth mechanism, with a critical concentration near 1 mm. The associated form is more stable than individual molecules by about 25 °C, and the association is reversible. The rate
of self-association increases with temperature, supporting an entropically favored process. After self-association, (Pro-Hyp-Gly)10 forms branched filamentous structures, in contrast with the highly ordered axially periodic structure of collagen fibrils.
Yet a number of characteristics of triple helix assembly for the peptide resemble those of collagen fibril formation. These
include promotion of fibril formation by neutral pH and increasing temperature; inhibition by sugars; and a requirement for
hydroxyproline. It is suggested that these similar features for peptide and collagen self-association are based on common
lateral underlying interactions between triple helical molecules mediated by hydrogen-bonded hydration networks involving
hydroxyproline.
The influence of UV radiation (253.7nm) on collagen fluorescence in the absence, and presence, of β-carotene was investigated. It was found that UV radiation of 253.7nm causes irreversible destruction of tyrosyl and phenylalanyl residues. The fluorescence of collagen (excitation at 275nm, emission at 305nm) decreased rapidly during irradiation and a new fluorescence large band at 400–500nm formed under UV radiation. Smaller changes in the fluorescence of collagen in the presence of β-carotene suggest that it makes collagen less sensitive to the action of UV radiation.
The effects of ultraviolet irradiation on collagen and its model peptides were studied. Degradation of collagen was predominant in the system using gel filtration chromatography. The fragmentation was presumably due to oxidation of proline, since collagen is a proline-rich protein and proline residues on collagen markedly decreased with irradiation. To clarify the fragmentation mechanism, poly(L-proline) and (Pro-Pro-Gly)10 as models of a collagen molecule were used and their oxidation was investigated. Glutamic acid, gamma-aminobutyric acid (GABA), and ammonia from the hydrolysates of the irradiated prolyl peptides were identified by amino acid analysis. It was presumed that GABA was generated from a 2-pyrrolidone structure by acid hydrolysis. To confirm this prediction, N-tert-butoxycarbonyl (Boc)-L-proline and N-tert-Boc-L-prolylglycine were exposed to ultraviolet light, and the irradiation products were isolated and characterized. Then, N-tert-Boc-2-pyrrolidone was identified from both UV-irradiated N-tert-Boc-L-proline and N-tert-Boc-L-prolylglycine. We proposed that the formation of the 2-pyrrolidone compound must contribute to the fragmentation of prolyl peptide on the basis of its structural property.
This work describes photochemical modification of collagen films, which are widely used in medical and consumer applications. Modification of collagen films by UV irradiation (254 nm) was investigated using differential scanning calorimetry and scanning electron microscopy. It was found that the denaturation temperature of collagen decreased during irradiation and the surface of the films was changed. Changes of denaturation temperature and surface of films under UV irradiation point to the loss of water bonded to collagen. This is confirmed by IR spectra.
Collagen type I is the most abundant extracellular matrix protein in the human body, providing the basis for tissue structure and directing cellular functions. Collagen has complex structural hierarchy, organized at different length scales, including the characteristic triple helical feature. In the present study, the relationship between collagen structure (native vs. denatured) and sensitivity to UV radiation was assessed, with a focus on changes in primary structure, changes in conformation, microstructure and material properties. A brief review of free radical reactions involved in collagen degradation is also provided as a mechanistic basis for the changes observed in the study. Structural and functional changes in the collagens were related to the initial conformation (native vs. denatured) and the energy of irradiation. These changes were tracked using SDS-PAGE to assess molecular weight, Fourier transform infrared (FTIR) spectroscopy to study changes in the secondary structure, and atomic force microscopy (AFM) to characterize changes in mechanical properties. The results correlate differences in sensitivity to irradiation with initial collagen structural state: collagen in native conformation vs. heat-treated (denatured) collagen. Changes in collagen were found at all levels of the hierarchical structural organization. In general, the native collagen triple helix is most sensitive to UV-254 nm radiation. The triple helix delays single chain degradation. The loss of the triple helix in collagen is accompanied by hydrogen abstraction through free radical mechanisms. The results received suggest that the effects of electromagnetic radiation on biologically relevant extracellular matrices (collagen in the present study) are important to assess in the context of the state of collagen structure. The results have implications in tissue remodeling, wound repair and disease progression.
The influence of UV radiation on the shape of infrared spectra of collagen from a rat tail tendon was studied. The spectra were resolved into Gaussian components by means af an iterative computer program. Characteristic absorption peaks for the resolved components were obtained. After UV irradiation the infrared amide bands of collagen were shifted to lower frequencies. This indicates that structural changes in this protein take place.Changes of absorbance of the components bands, under UV irradiation, point to the loss of water bonded to collagen, degradation of main chains with scission of the amide, CH2N, CH2 and CO bonds, abstraction of the side groups as COOH, CO, COO−1, and change of the ratio of the helical to the coil conformation of collagen molecules.IR analysis may provide some information about the photochemical transformations in collagen, although they occur with rather low efficiency.
Polyimides are high performance polymers designed for use at temperatures near the limits expected for purely organic materials. An understanding of the factors which influence the stability and rates of degradation of polyimides at elevated temperatures is therefore important. This review covers the literature of the last 10 years dealing with the high temperature (>300°C) degradation of polyimides. The effects of monomer structure, end groups and additives on polyimide stability are described. The influence of the method of preparation, choice of solvents, substrates and other environmental concerns on ultimate stability of these materials is also considered. Studies of the stabilization of polyimides are described as well.
The influence of deleterious UV radiation on collagen molecules in the absence and presence of ascorbic acid using UV-vis and FT-IR spectroscopy has been studied. Intensity of UV-vis absorption spectrum of collagen with a maximum at 275 m due to the aromatic residues (tyrosine and phenylalanine) increases with the increasing dose of UV radiation. This effect is significantly hindered in the presence of antioxidant ascorbic acid. Intensities of FT-IR bands (amide A, B, I and II) of collagen decrease with the increase of the UV radiation dosage. Intensities of bands are also decreased in the presence of ascorbic acid. Results suggest that increasing the concentration of ascorbic acid increases the photo-stability of collagen, and the collagen becomes less sensitive to UV radiation. It is possible that hydrogen bonds form between the groups N-H of collagen and C=O of ascorbic acid. It is believed that under UV radiation free radicals appear in acid soluble collagen and resulting in photodegradation of the macromolecule restore due to the ability of ascorbic acid donating one or two electrons. Increasing the dose of radiation causes more molecules of ascorbic acid to slow down, and their antioxidant effect is diminished accordingly.
Electron paramagnetic resonance (EPR) method has shown that hydrogen atoms and acetic acid free radicals appear in surrounding acetic acid-water solution of collagen under ultraviolet (UV) irradiation. These free radicals interact with the collagen molecule; consequently, seven superfine components of EPR spectrum with the split of aH = 11.3G and g-factor 2.001 appear. It is assumed that this spectrum is related to the free radical occurred on the proline residue in collagen molecule. In order to discover .OH hydroxyl radicals even in minor concentration, spin trap 5.5-dimethyl-1-pyrroline N-oxide (DMPO) has been applied. During the irradiation of collagen water solution in the presence of spin trap, EPR spectrum of the DMPO/.OH adduct has not been identified, while the above mentioned spectrum has been observed once the hydrogen peroxide H2O2 and FeSO4 were added to the sample. That means that water photolysis does not take place in collagen water-solution due to UV irradiation. It was suggested that occurrence of hydrogen radical is connected with the electron transmission to the hydrogen ion. The possible source of free electrons can be aromatic residues, photo ionization of which takes place in collagen molecule due to UV irradiation.
Insoluble collagen from rat tail tendon was digested with cyanogen bromide. The resultant peptides were dissolved in 0.1% SDS solution and separated by gel filtration and gel electrophoresis. Cross-linking occurred in CNBr-cleaved peptides when they were exposed to ozone or biologically effective UV (300 nm) radiation. The enhancement of a blue fluorescence at 430 nm (excited at 350 nm) was found to be associated with oxidized, cross-linked peptides. Polymeric peptides, formed in collagen with aging, also exhibited enhanced blue fluorescence.
High-molecular-mass aggregates were made soluble from insoluble collagens of bovine Achilles tendon and rat tail tendon by limited thermal hydrolysis. These polymeric collagen aggregates were cross-linked by 390-nm-fluorescent 3-hydroxy-pyridinium residues (excited at 325 nm) in the former tendon and by unknown non-fluorescent residues in the latter. With the solubilized insoluble-collagens from both tendons, as well as with acidsoluble collegen from rat tail tendon, other 350–385-nm fluorescence intensities (excited at 300 nm) were found to be higher in monomeric hains than in dimeric and polymeric chains.
Low levels of ozone inhibited fibril formation of acid-soluble collagen particularly from young rat tail tendon, recting with tyrosine residues and the 350–385-nm fluorophores. Aldehyde groups, involved in cross-linking, were not effectively modified by ozone. β-Components (α-chain dimers) were not efficiently dissociated even by higher doses of ozone compared to γ-components (α-chain trimers). Polymeric chain aggregates from bovine Achilles tendon collagen, whose 3-hydroxy-pyridinium cross-links are cleaved by ozone, were more readily dissociated by ozone than those from rat tail tendon collagen.
Ultraviolet (300-nm) light, which destroyed the 350–385-nm fluorophores, inhibited fibril formation less effectively than ultraviolet (275-nm) light, which is absorbed by tyrosine residues, and did not dissociate collagen polymers from rat tail tendon. On the other hand, ultraviolet (320-nm) light, absorbed by 3-hydroxy-pyridinium cross-links which were repidly photolyzed, partially dissociated polymeric collagen aggregates from bovine Achilles tendon after subsequent heating.
Effects of ultraviolet light on physical, chemical and immunologic properties of acid-soluble and enzyme (proctase)-treated collagen were studied. Ultraviolet irradiation in air caused an initial increase in viscosity of both collagen preparations, rapidly followed by a loss of viscosity and a loss of negative optical rotation. Ultraviolet irradiation in nitrogen, however, led to a rapid increase in viscosity until a gel formed. With prolonged irradiation, this gel also depolymerized. Enzyme-treated collagen was less sensitive to the effects of ultraviolet irradiation than was acid-soluble collagen. Immunologic reactivity of enzyme-treated collagen was rapidly lost with short exposures to ultraviolet irradiation. Ultraviolet irradiation also inhibited fiber formation. These results suggest that photochemical modifications occur at telopeptide regions or remaining aromatic residues of enzyme-treated collagen during early stages of irradiation. The transition temperature of the melting curve of collagen became broad but there was no loss of negative optical rotation, suggesting that scission of collagen molecules into shorter fragments which retain helical configurations occurred with longer periods of irradiation. Splitting of the polypeptide chain probably occurs between nitrogen and the α-carbon.
Using an improved method of gel electrophoresis, many hitherto unknown
proteins have been found in bacteriophage T4 and some of these have been
identified with specific gene products. Four major components of the
head are cleaved during the process of assembly, apparently after the
precursor proteins have assembled into some large intermediate
structure.
The structure of a protein triple helix has been determined at 1.9 angstrom resolution by x-ray crystallographic studies of a collagen-like peptide containing a single substitution of the consensus sequence. This peptide adopts a triple-helical structure that confirms the basic features determined from fiber diffraction studies on collagen: supercoiling of polyproline II helices and interchain hydrogen bonding that follows the model II of Rich and Crick. In addition, the structure provides new information concerning the nature of this protein fold. Each triple helix is surrounded by a cylinder of hydration, with an extensive hydrogen bonding network between water molecules and peptide acceptor groups. Hydroxyproline residues have a critical role in this water network. The interaxial spacing of triple helices in the crystal is similar to that in collagen fibrils, and the water networks linking adjacent triple helices in the crystal structure are likely to be present in connective tissues. The breaking of the repeating (X-Y-Gly)n pattern by a Gly-->Ala substitution results in a subtle alteration of the conformation, with a local untwisting of the triple helix. At the substitution site, direct interchain hydrogen bonds are replaced with interstitial water bridges between the peptide groups. Similar conformational changes may occur in Gly-->X mutated collagens responsible for the diseases osteogenesis imperfecta, chondrodysplasias, and Ehlers-Danlos syndrome IV.
Riboflavin-sensitized photodynamic modification of collagen led to significant formation of cross-linked molecules. Sodium azide or 1,4-diazabicyclo(2,2,2)octane, which are known to be singlet oxygen quenchers, and catalase could not inhibit the modification. Surprisingly, the collagen modification was accelerated in the presence of superoxide dismutase. The aggregation was accompanied by the loss of tyrosine and histidine residues in the collagen. An inhibitory effect of dissolved oxygen on the modification of collagen was observed. Similarly, the loss of tyrosine residues in the irradiated collagen was inhibited in the presence of dissolved oxygen. Dityrosine formation was also observed with the loss of tyrosine. These results indicate that photodynamic modification of tyrosine probably contributes to the riboflavin-sensitized cross-linking of collagen through the formation of dityrosine.
Glycine is found as every third residue along the entire length of triple helices in fibrillar collagens, but the triple-helix regions of nonfibrillar collagens and other proteins usually contain one or more interruptions in this repeating pattern. A set of four peptides was designed to model the effect of interruptions in the (Gly-X-Y)n repeating pattern on triple-helix formation, stability, and folding. Into the middle of the stable triple-helical peptide (Pro-Hyp-Gly)10, an interruption was introduced representing one of the four possible categories: a glycine deletion, a deletion of a hydroxyproline (Y position), an alanine insertion, or a glycine to alanine substitution. As shown by sedimentation equilibrium, NMR, and CD studies, the introduction of an interruption still allowed formation of trimers in solution, but with marked decrease in stability. The degree of destabilization and the thermodynamic basis for the loss of stability depended on the type of interruption. The glycine substitution and alanine insertion were the least disruptive, followed by the hydroxyproline deletion, with the glycine deletion being the most destabilizing. Our results suggest that the breaks in these peptides affect both the triple-helical conformation and the monomer conformation. These studies provide a basis for considering the structural and functional consequences of different kinds of interruptions in collagen.
To review and distinguish between skin changes produced by aging and changes produced by habitual exposure to sun.
The literature was searched from 1969 to 1999 for articles on dermatoheliosis and sun-damaged skin. Surprisingly few were found comparing the difference between elderly skin and sun-damaged skin. A few articles focused on certain small aspects of sun-damaged skin. Many excellent articles described particular changes (e.g., actinic keratosis), but few covered all the changes due to aging and to sun.
Skin changes due to aging can be distinguished from those due to sun damage. All changes due to sun exposure can be grouped under the term dermatoheliosis; five parts of the skin are involved: epidermis (actinic keratosis), dermis (solar elastosis), blood vessels (telangiectasia), sebaceous glands (solar comedones), and melanocytes (diffuse or mottled brown patches). Habitual exposure to sun and a white skin are prerequisites for developing these changes. Knowing the difference between changes caused by sun and by aging can help physicians predict which patients are most likely to get skin cancers.
Knowledge of these common skin changes will help physicians diagnose and manage the skin abnormalities of elderly people and of people with dermatoheliosis.
The use of polypeptide models has proved to be a valuable tool to obtain accurate information on the collagen triple helix. Here we report the high resolution crystal structure of a collagen-like polypeptide with repeating sequence Pro-Hyp-Gly. The structure has been refined to an R(factor) of 0.137 and an R(free) of 0.163 using synchrotron diffraction data extending up to 1.4 A resolution. The polypeptide triple-helical structure binds a large number of water molecules, in contrast with a previous structure determination at lower resolution. The highly hydrated nature of this polypeptide confirms a number of previous studies conducted both in solution and in the crystal state. In addition, neighboring polypeptide triple helices are directly bound in the crystal through Hyp-Hyp hydrogen-bonding interactions. This finding supports the idea that Hyp residues may be important for the assembly of the triple helices in the collagen fibrils and may stabilize the fibrils by mediating direct contacts between neighboring molecules.
Measured by ultra-slow scanning calorimetry and isothermal circular dichroism, human lung collagen monomers denature at 37 degrees C within a couple of days. Their unfolding rate decreases exponentially at lower temperature, but complete unfolding is observed even below 36 degrees C. Refolding of full-length, native collagen triple helices does occur, but only below 30 degrees C. Thus, contrary to the widely held belief, the energetically preferred conformation of the main protein of bone and skin in physiological solution is a random coil rather than a triple helix. These observations suggest that once secreted from cells collagen helices would begin to unfold. We argue that initial microunfolding of their least stable domains would trigger self-assembly of fibers where the helices are protected from complete unfolding. Our data support an earlier hypothesis that in fibers collagen helices may melt and refold locally when needed, giving fibers their strength and elasticity. Apparently, Nature adjusts collagen hydroxyproline content to ensure that the melting temperature of triple helical monomers is several degrees below rather than above body temperature.
Triple-helical structures of (Pro-Hyp-Gly)n (n = 10, 11) at 100 K and room temperature (RT) were analyzed at 1.26 A resolution by using synchrotron radiation data. Totals of 49 and 42 water molecules per seven triplets in an asymmetric unit were found for the structures at 100 K and RT, respectively. These water molecules were classified into two groups, those in the first and second hydration shells. Although there was no significant difference between water molecules in the first shell at 100 K and those at RT, a significant difference between those in the second shell was observed. That is, the number of water molecules at RT decreased to one half and the average distance from peptide chains at RT became longer by about 0.3 A. On the other hand, of seven triplets in an asymmetric unit, three proline residues at the X position at 100 K clearly showed an up-puckering conformation, as opposed to the recent propensity-based hypothesis for the stabilization and destabilization of triple-helical structures by proline hydroxylation. This puckering was attributed to the interaction between proline rings and the surrounding water molecules at 100 K, which is much weaker at RT, as shown by longer average distance from peptide chains.
It has been shown by microcalorimetry that UV-irradiation cardinally alters the temperature dependence of heat capacity of a collagen solution and decreases the enthalpy of collagen heat denaturation. By using the method of electron spin resonance (ESR), it was found that the primary products of UV-irradiated acid-soluble collagen are the atomic hydrogen and the anion radical of acetic acid. The latter, under the influence of long-wavelength UV light, is transformed into the methyl radical, which interacts with acetic acid to produce acetic acid radical. The above free radicals interact with the collagen molecule, as a result of which seven superfine components with the split of deltaH = 1.13 mT are obtained in the ESR spectrum. It is assumed that this spectrum is related to the free radical that occurred in the proline residue of the collagen molecule. In this particular case, this is a major structural defect in the triple helix of collagen, which results in instability of the macromolecule.
Free radicals/reactive oxygen species (ROS) generated in skin by UV irradiation were measured by electron spin resonance (ESR). To increase the sensitivity of measurement the short life free radicals/ROS were scavenged and accumulated by using the nitroxyl probe 3-carboxy-2,2,5,5-tetrametylpyrrolidine-1-oxyl (PCA). The spatial distribution of free radicals/ROS measured in pig skin biopsies with ESR imaging after UV irradiation corresponds to the intensity decay of irradiance in the depth of the skin. The main part of free radicals/ROS were generated by UVA (320-400 nm) so that the spatial distribution of free radicals reaches up to the lower side of the dermis. In vivo measurements on human skin were performed with a L-band ESR spectrometer and a surface coil integrating the signal intensities from all skin layers to get a sufficient signal amplitude. Using this experimental arrangement the protection of UVB and UVA/B filter against the generation of free radicals/ROS in skin were measured. The protection against ROS and the repair of damages caused by them can be realized with active antioxidants characterized by a high antioxidative power (AP). The effect of UV filter and antioxidants corresponding to their protection against free radicals/ROS in skin generated by UVAB irradiation can be quantified by the new radical sun protection factor (RSF). The RSF indicates the increase of time for staying in the sun to generate the same number of free radicals/ROS in the skin like for the unprotected skin. Regarding the amount of generated free radicals/ROS in skin as an biophysical endpoint the RSF characterizes both the protection against UVB and UVA radiation.
X-ray crystallography of collagen model peptides has provided high-resolution structures of the basic triple-helical conformation and its water-mediated hydration network. Vibrational spectroscopy provides a useful bridge for transferring the structural information from X-ray diffraction to collagen in its native environment. The vibrational mode most useful for this purpose is the amide I mode (mostly peptide bond C=O stretch) near 1650 cm-1. The current study refines and extends the range of utility of a novel simulation method that accurately predicts the infrared (IR) amide I spectral contour from the three-dimensional structure of a protein or peptide. The approach is demonstrated through accurate simulation of the experimental amide I contour in solution for both a standard triple helix, (Pro-Pro-Gly)10, and a second peptide with a Gly --> Ala substitution in the middle of the chain that models the effect of a mutation in the native collagen sequence. Monitoring the major amide I peak as a function of temperature gives sharp thermal transitions for both peptides, similar to those obtained by circular dichroism spectroscopy, and the Fourier transform infrared (FTIR) spectra of the unfolded states were compared with polyproline II. The simulation studies were extended to model early stages of thermal denaturation of (Pro-Pro-Gly)10. Dihedral angle changes suggested by molecular dynamics simulations were made in a stepwise fashion to generate peptide unwinding from each end, which emulates the effect of increasing temperature. Simulated bands from these new structures were then compared to the experimental bands obtained as temperature was increased. The similarity between the simulated and experimental IR spectra lends credence to the simulation method and paves the way for a variety of applications.
A wide variety of enzymes can undergo a reversible loss of activity at low temperature, a process that is termed cold inactivation. This phenomenon is found in oligomeric enzymes such as tryptophanase (Trpase) and other pyridoxal phosphate dependent enzymes. On the other hand, cold-adapted, or psychrophilic enzymes, isolated from organisms able to thrive in permanently cold environments, have optimal activity at low temperature, which is associated with low thermal stability. Since cold inactivation may be considered “contradictory” to cold adaptation, we have looked into the amino acid sequences and the crystal structures of two families of enzymes, subtilisin and tryptophanase. Two cold adapted subtilisins, S41 and subtilisin-like protease from Vibrio, were compared to a mesophilic and a thermophilic subtilisins, as well as to four PLP-dependent enzymes in order to understand the specific surface residues, specific interactions, or any other molecular features that may be responsible for the differences in their tolerance to cold temperatures. The comparison between the psychrophilic and the mesophilic subtilisins revealed that the cold adapted subtilisins have a high content of acidic residues mainly found on their surface, making it charged. The analysis of the Trpases showed that they have a high content of hydrophobic residues on their surface. Thus, we suggest that the negatively charged residues on the surface of the subtilisins may be responsible for their cold adaptation, whereas the hydrophobic residues on the surface of monomeric Trpase molecules are responsible for the tetrameric assembly, and may account for their cold inactivation and dissociation. © 2007 Wiley Periodicals, Inc. Biopolymers 89: 354–359, 2008.
This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Peptides have been an integral part of the collagen triple-helix structure story, and have continued to serve as useful models for biophysical studies and for establishing biologically important sequence-structure-function relationships. High resolution structures of triple-helical peptides have confirmed the basic Ramachandran triple-helix model and provided new insights into the hydration, hydrogen bonding, and sequence dependent helical parameters in collagen. The dependence of collagen triple-helix stability on the residues in its (Gly-X-Y)n repeating sequence has been investigated by measuring melting temperatures of host-guest peptides and an on-line collagen stability calculator is now available. Although the presence of Gly as every third residue is essential for an undistorted structure, interruptions in the repeating (Gly-X-Y)n amino acid sequence pattern are found in the triple-helical domains of all nonfibrillar collagens, and are likely to play a role in collagen binding and degradation. Peptide models indicate that small interruptions can be incorporated into a rod-like triple-helix with a highly localized effect, which perturbs hydrogen bonds and places the standard triple-helices on both ends out of register. In contrast to natural interruptions, missense mutations which replace one Gly in a triple-helix domain by a larger residue have pathological consequences, and studies on peptides containing such Gly substitutions clarify their effect on conformation, stability, and folding. Recent studies suggest peptides may also be useful in defining the basic principles of collagen self-association to the supramolecular structures found in tissues. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 345–353, 2008.
This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
The folding of collagen in vitro is very slow and presents difficulties in reaching equilibrium, a feature that may have implications for in vivo collagen function. Peptides serve as good model systems for examining equilibrium thermal transitions in the collagen triple helix. Investigations were carried out to ascertain whether a range of synthetic triple-helical peptides of varying sequences can reach equilibrium, and whether the triple helix to unfolded monomer transition approximates a two-state model. The thermal transitions for all peptides studied are fully reversible given sufficient time. Isothermal experiments were carried out to obtain relaxation times at different temperatures. The slowest relaxation times, on the order of 10-15 h, were observed at the beginning of transitions, and were shown to result from self-association limited by the low concentration of free monomers, rather than cis-trans isomerization. Although the fit of the CD equilibrium transition curves and the concentration dependence of T(m) values support a two-state model, the more rigorous comparison of the calorimetric enthalpy to the van't Hoff enthalpy indicates the two-state approximation is not ideal. Previous reports of melting curves of triple-helical host-guest peptides are shown to be a two-state kinetic transition, rather than an equilibrium transition.
Physiology of the skin II
- P Pugliese
Pugliese, P. Physiology of the skin II. Allured Publishing Corporation; 2001. p. 109-137.
- Y Kato
- K Uchida
- Kawakishi Shj
Kato Y, Uchida K, Kawakishi ShJ. Agric Food Chem. 1992; 40:373-379.
- T Miyata
- T Sohde
- Al Rubin
- Kh Stenzel
Miyata T, Sohde T, Rubin AL, Stenzel KH. Biochimica et Biophisica Acta. 1971; 229:672-680.
- N Metreveli
- L Namicheishvili
- K Jariashvili
- M Dgebuadze
- E Chikvaidze
- A Sionkowska
Metreveli N, Namicheishvili L, Jariashvili K, Dgebuadze M, Chikvaidze E, Sionkowska A. Journal
of Photochemistry and Photobiology B: biology. 2008; 93:61-65.
Treatise on collagen
- Gn Ramachandran
Ramachandran, GN. Treatise on collagen. Ramachandran, GN., editor. Academic Press; New
York, US: 1967. p. 103-183.
- A Sionkowska
- A Kaminska
Sionkowska A, Kaminska A. Journal of Photochemistry and Photobiology, A: chemistry. 1998;
120:207-210.
- N Metreveli
- L Namicheishvili
- K Jariashvili
- G Mrevlishvili
- A Sionkowska
Metreveli N, Namicheishvili L, Jariashvili K, Mrevlishvili G, Sionkowska A. International Journal
of Photoenergy. 2006:Article ID 76830, 1-4.
- Kja Davies
- Wa Pryor
Davies KJA, Pryor WA. Free Radical Biology & Medcine. 2005; 39:1263.
Treatise on Collagen Ramachandran
- G N Ramachandran