Article

Thymol attenuates the worsening of atopic dermatitis induced by Staphylococcus aureus membrane vesicles

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Staphylococcus aureus membrane vesicles (MVs) aggravate atopic dermatitis (AD) through the delivery of bacterial effector molecules to host cells and the stimulation of inflammatory responses. This study investigated the inhibitory effect of thymol, a phenolic monoterpene found in essential oils derived from plants, on the worsening of AD induced by S. aureus MVs both in vitro and in vivo. The sub-minimal inhibitory concentrations of thymol disrupted S. aureus MVs. Intact S. aureus MVs induced the expression of pro-inflammatory cytokine (interleukin (IL)-1β, IL-6, and tumor necrosis factor-α) and chemokine (IL-8 and monocyte chemoattractant protein-1) genes in cultured keratinocytes, whereas thymol-treated S. aureus MVs did not stimulate the expression of these genes. Topical application of thymol-treated S. aureus MVs or treatment with thymol after intact S. aureus MVs to AD-like skin lesions diminished the pathology of AD. This included decreases in epidermal/dermal thickness and infiltration of eosinophils/mast cells, and inhibited expression of pro-inflammatory cytokine and chemokine genes in mouse AD model. Moreover, thymol significantly suppressed the Th1, Th2, and Th17-mediated inflammatory responses in AD-like skin lesions induced by S. aureus MVs, and reduced the serum levels of immunoglobulin (Ig) G2a, mite-specific IgE, and total IgE. In summary, thymol disrupts S. aureus MVs and suppresses inflammatory responses in AD-like skin lesions aggravated by S. aureus MVs. Our results suggest that thymol is a possible candidate for the management of AD aggravation induced by S. aureus colonization or infection in the lesions.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Since then, several studies characterized the EV protein content of other S. aureus strains, revealing from 90 to 617 identified proteins, including numerous virulence factors ( Table 1). 01ST93 Non-cytotoxic to host cells (Hep-2) [31] 03ST17 143 Non-cytotoxic to host cells (Hep-2, HaCaT) [31,38] Cytotoxic to host cells (HaCaT) [62] Immunomodulation in vitro and in vivo (e.g., ↑ IL-1β, IL-6, IL-8, TNF-α, and MCP-1) [38,62] Mast cell recruitment and exacerbation of skin inflammation 06ST1048 Cytotoxic to host cells (Hep-2) [29,31] 143 Delivery of Spa protein through EVs (Hep-2) [29] 8325-4 Induction of the MAPK pathway (THP-1 and MLE-12) [63] Cytotoxicity to host cells (HeLa) [64] Hemolytic activity [63,64] 8325-4Δhla Low cytotoxic to host cells (HeLa) [64] Weaker induction of MAPK pathway (THP-1 and MLE-12) ...
... Since then, several studies characterized the EV protein content of other S. aureus strains, revealing from 90 to 617 identified proteins, including numerous virulence factors ( Table 1). 01ST93 Non-cytotoxic to host cells (Hep-2) [31] 03ST17 143 Non-cytotoxic to host cells (Hep-2, HaCaT) [31,38] Cytotoxic to host cells (HaCaT) [62] Immunomodulation in vitro and in vivo (e.g., ↑ IL-1β, IL-6, IL-8, TNF-α, and MCP-1) [38,62] Mast cell recruitment and exacerbation of skin inflammation 06ST1048 Cytotoxic to host cells (Hep-2) [29,31] 143 Delivery of Spa protein through EVs (Hep-2) [29] 8325-4 Induction of the MAPK pathway (THP-1 and MLE-12) [63] Cytotoxicity to host cells (HeLa) [64] Hemolytic activity [63,64] 8325-4Δhla Low cytotoxic to host cells (HeLa) [64] Weaker induction of MAPK pathway (THP-1 and MLE-12) ...
... For instance, disrupted EVs produced by S. aureus ATCC 25923 strain were shown to be four times less cytotoxic than intact EVs [65]. Again, whole and lysed EVs derived from strain 03ST17 were both cytotoxic and proinflammatory, however, these properties were more intense when EVs were intact [38,62]. Nevertheless, in some cases, EV integrity does not influence their cytotoxic properties, as it is the case of S. aureus M060 EVs, that in both intact and disrupted states had the same cytotoxicity levels towards HaCaT cells [65]. ...
... This observation suggests that thymol possibly acts on the membranes of the bacterial EVs and disrupts them. We recently showed that thymol disrupted EVs derived from S. aureus 03ST17 obtained from the skin lesions of an atopic dermatitis patient [21]. Thymol-treated S. aureus EVs did not induce the expression of pro-inflammatory cytokine genes in keratinocytes in vitro. ...
... However, EDTA-disrupted S. aureus EVs inhibited the [6,12]. Moreover, thymol-treated S. aureus EVs suppressed the inflammatory responses in vitro and in vivo [21]. Based on these results, we hypothesized that thymol inhibited the inflammatory responses induced by the S. aureus EVs via the disruption of the membranes of the EVs. ...
... The expression of all tested cytokine genes was significantly increased at ≥5 μg/mL of S. aureus ATCC 25923 EVs, whereas the expression of these genes was significantly increased at ≥10 μg/mL of S. aureus M060 EVs (Fig. 4). Moreover, the expression levels of the pro-inflammatory cytokine genes in HaCaT cells incubated with S. aureus ATCC 25923 EVs were similar to those in cells incubated with EVs derived from S. aureus 03ST17 isolated from atopic dermatitis lesions [21]. Thymol inhibited the expression of the IL-1β, IL-6, IL-8, and MCP-1 genes in HaCaT cells incubated with both S. aureus EVs, but its inhibitory effects on the expression of TNF-α gene was not observed in cells incubated with S. aureus ATCC 25923 EVs. ...
Article
Staphylococcus aureus extracellular vesicles (EVs) deliver effector molecules to host cells and induce host cell pathology. This study investigated the disruption of S. aureus EVs by thymol along with its inhibitory effects on the cytotoxicity and inflammatory responses induced by EVs derived from two different S. aureus strains in cultured keratinocytes. Membrane disruption of the S. aureus EVs treated with thymol was determined using transmission electron microscopy. Human keratinocyte HaCaT cells were incubated with either intact or thymol-treated S. aureus EVs and then analyzed for cytotoxicity and pro-inflammatory cytokine gene expression. Thymol inhibited the growth of S. aureus strains and disrupted the membranes of the S. aureus EVs. The cytotoxicity and the expression levels of the pro-inflammatory cytokine genes towards HaCaT cells differed between the EVs derived from two S. aureus strains. Thymol-treated S. aureus EVs inhibited the cytotoxicity and the expression of the pro-inflammatory cytokine genes when compared to intact S. aureus EVs. Thymol-treated S. aureus EVs delivered lesser amounts of the EV component to host cells than intact EVs. Our results suggest that the thymol-induced disruption of the S. aureus EVs inhibits the delivery of effector molecules to host cells, resulting in the suppression of cytotoxicity and inflammatory responses in keratinocytes. Thymol may attenuate the host cell pathology induced by an S. aureus infection via both the antimicrobial activity against the bacteria and the disruption of the secreted EVs.
... Since then, several studies characterized the EV protein content of other S. aureus strains, revealing from 90 to 617 identified proteins, including numerous virulence factors ( Table 1). 01ST93 Non-cytotoxic to host cells (Hep-2) [31] 03ST17 143 Non-cytotoxic to host cells (Hep-2, HaCaT) [31,38] Cytotoxic to host cells (HaCaT) [62] Immunomodulation in vitro and in vivo (e.g., ↑ IL-1β, IL-6, IL-8, TNF-α, and MCP-1) [38,62] Mast cell recruitment and exacerbation of skin inflammation 06ST1048 Cytotoxic to host cells (Hep-2) [29,31] 143 Delivery of Spa protein through EVs (Hep-2) [29] 8325-4 Induction of the MAPK pathway (THP-1 and MLE-12) [63] Cytotoxicity to host cells (HeLa) [64] Hemolytic activity [63,64] 8325-4Δhla Low cytotoxic to host cells (HeLa) [64] Weaker induction of MAPK pathway (THP-1 and MLE-12) ...
... Since then, several studies characterized the EV protein content of other S. aureus strains, revealing from 90 to 617 identified proteins, including numerous virulence factors ( Table 1). 01ST93 Non-cytotoxic to host cells (Hep-2) [31] 03ST17 143 Non-cytotoxic to host cells (Hep-2, HaCaT) [31,38] Cytotoxic to host cells (HaCaT) [62] Immunomodulation in vitro and in vivo (e.g., ↑ IL-1β, IL-6, IL-8, TNF-α, and MCP-1) [38,62] Mast cell recruitment and exacerbation of skin inflammation 06ST1048 Cytotoxic to host cells (Hep-2) [29,31] 143 Delivery of Spa protein through EVs (Hep-2) [29] 8325-4 Induction of the MAPK pathway (THP-1 and MLE-12) [63] Cytotoxicity to host cells (HeLa) [64] Hemolytic activity [63,64] 8325-4Δhla Low cytotoxic to host cells (HeLa) [64] Weaker induction of MAPK pathway (THP-1 and MLE-12) ...
... For instance, disrupted EVs produced by S. aureus ATCC 25923 strain were shown to be four times less cytotoxic than intact EVs [65]. Again, whole and lysed EVs derived from strain 03ST17 were both cytotoxic and proinflammatory, however, these properties were more intense when EVs were intact [38,62]. Nevertheless, in some cases, EV integrity does not influence their cytotoxic properties, as it is the case of S. aureus M060 EVs, that in both intact and disrupted states had the same cytotoxicity levels towards HaCaT cells [65]. ...
Chapter
Full-text available
Staphylococcus aureus is a pathogen of great importance to clinical and veterinary medicine. Recently, there has been a growing interest in S. aureus extracellular vesicles (EVs) in the pathogenesis of this bacterium. Released by living cells into the extracellular milieu, EVs are membranous structures carrying macromolecules such as proteins, nucleic acids, and metabolites. These structures play several physiological roles and are, among others, considered a mechanism of intercellular communication within S. aureus populations but also in trans kingdom interactions. S. aureus EVs were shown to transport important bacterial survival and virulence factors, such as β-lactamases, toxins, and proteins associated with bacterial adherence to host cells, and to trigger the production of cytokines and promote tissue inflammation. In this chapter, we will review the main studies regarding S. aureus EVs, including their composition and roles in host-pathogen interactions, and the possible applications of EVs for vaccines and therapy development against staphylococcal infections.
... There have also been some reports demonstrating the important role of MVs in the pathogenesis of AD due to Staphylococcus aureus. The suggested mechanisms included transfer of crucial microbial proteins and induction of inflammatory responses in the host cells, accompanied by increased pro-inflammatory cytokines/chemokines, Th1, Th2, and Th17-induced inflammatory changes, endothelial cell activation and monocyte recruitment [140][141][142]. Interestingly, disruption of microbial MVs release has been found to alleviate AD pathogenesis [141]. ...
... The suggested mechanisms included transfer of crucial microbial proteins and induction of inflammatory responses in the host cells, accompanied by increased pro-inflammatory cytokines/chemokines, Th1, Th2, and Th17-induced inflammatory changes, endothelial cell activation and monocyte recruitment [140][141][142]. Interestingly, disruption of microbial MVs release has been found to alleviate AD pathogenesis [141]. Therapeutic importance of EVs has been also elucidated in contact hypersensitivity via inhibition of cytotoxic T cells and T helper cells and regulatory T cells [143]. ...
Article
Full-text available
Skin is the largest human organ and is continuously exposed to various exogenous and endogenous trigger factors affecting body homeostasis. A number of mechanisms, including genetic, inflammatory and autoimmune ones, have been implicated in the pathogenesis of cutaneous diseases. Recently, there has been considerable interest in the role that extracellular vesicles, particularly exosomes, play in human diseases, through their modulation of multiple signaling pathways. Exosomes are nano-sized vesicles secreted by all cell types. They function as cargo carriers shuttling proteins, nucleic acids, lipids etc., thus impacting the cell-cell communications and transfer of vital information/moieties critical for skin homeostasis and disease pathogenesis. This review summarizes the available knowledge on how exosomes affect pathogenesis of cutaneous diseases, and highlights their potential as future targets for the therapy of various skin diseases.
... Numerous natural compounds inhibiting virulence factor production of S. aureus, either alone or in combination with traditional antibiotics, have been reported [21]. For example, thymol (2isopropyl-5-methylphenol), a constituent of thyme herb (Thymus vulgaris L.), possesses a wide spectrum of antimicrobial activity [22][23][24][25][26][27][28][29] and reduces the biofilm formation of S. aureus strains [30][31][32][33]. Furthermore, it is known to inhibit staphyloxanthin production in MRSA [34]. ...
Article
Full-text available
Staphylococcus aureus is a major human bacterial pathogen that carries a large number of virulence factors. Many virulence factors of S. aureus are regulated by the accessory gene regulator (agr) quorum-sensing system. Phenol-soluble modulins (PSMs) are one of the agr-mediated virulence determinants known to play a significant role in S. aureus pathogenesis. In the present study, the efficacy of thymol to inhibit PSM production including δ-toxin in S. aureus was explored. We employed liquid chromatography–mass spectrometry (LC–MS) to quantify the PSMsα1–PSMα4, PSMβ1 and PSMβ2, and δ-toxin production from culture supernatants. We found that thymol at 0.5 MIC (128 μg/mL) significantly reduced the PSMα and δ-toxin production in S. aureus WKZ-1, WKZ-2, LAC USA300, and ATCC29213. Downregulation in transcription by quantitative real-time (qRT) PCR analysis of response regulator agrA and receptor histidine kinase agrC upon 0.5 MIC thymol treatment affirmed the results of LC–MS quantification of PSMs. In silico molecular docking analysis demonstrated the binding affinity of thymol with receptors AgrA and AgrC. Transmission electron microscopy images revealed no ultrastructural alterations (cell wall and membrane) in thymol-treated WKZ-1 and WKZ-2 S. aureus strains. Here, we demonstrated that thymol reduces various PSM production in S. aureus clinical isolates and reference strains with mass spectrometry.
... Several studies have shown the anti-inflammatory effect of thymol in various models of inflammation. It has been reported that thymol has anti-inflammatory properties through inhibiting the expression of pro-inflammatory cytokines such as IL-1β, IL-6, tumor necrosis factor-α, and chemokines (IL-8 and monocyte chemoattractant protein-1) in atopic dermatitis induced by Staphylococcus aureus membrane vesicles (Kwon et al. 2018). In another study, Mohammadi et al. found that thymol had protective effects in an experimental model of asthma through suppressing the protein carbonyl content, MDA and 8-OHd (Mohammadi et al. 2018). ...
Article
Full-text available
Aim The aim of the present study was to evaluate the anti-inflammatory effect of thymol in acetic acid-induced rat colitis through inhibiting the NF-κB signaling pathway. Methods Colitis was induced by intra-rectal administration of 2 mL of diluted acetic acid (4%) solution using a flexible plastic rubber catheter in Wistar rats. Colitis was induced on the first day and all treatments were applied 5 days after the induction of colitis. Thymol was dissolved in 0.2% tween 80 in saline and administered orally at doses of 10, 30, and 100 mg/kg per day. Macroscopic and histopathologic investigations were done. The expression of myeloperoxidase (MPO) and tumor necrosis factor-α (TNF-α) was determined by immunohistochemistry (IHC) assay. The protein expression level of pNF-κB p65 was measured by the Western blot technique. Results Treatment with thymol reduced mucosal and histological damages compared to the acetic acid group. Our results showed that thymol markedly inhibited the production of MPO and TNF-α in the colon tissue of the acetic acid-induced group. In addition, thymol decreased acetic acid-induced up-regulation of pNFκB p65 protein. Conclusions: The results of our study suggest that thymol exerts an anti-inflammatory effect in acetic acid-induced rat colitis by inhibiting the NF-κB signaling pathway and downregulating TNF-α and MPO expressions.
... Thus, S. aureus-EVs may be regarded as one of the therapeutic targets for the management of AD aggravation. Notably, EVs derived from thymol-treated S. aureus or Lactobacillus plantarum alleviated the AD-like skin lesions including epidermal thickening and IL-4 level [171,172], indicating their potential to treat AD. ...
Article
Full-text available
Extracellular vesicles (EVs), naturally secreted by almost all known cell types into extracellular space, can transfer their bioactive cargos of nucleic acids and proteins to recipient cells, mediating cell-cell communication. Thus, they participate in many pathogenic processes including immune regulation, cell proliferation and differentiation, cell death, angiogenesis, among others. Cumulative evidence has shown the important regulatory effects of EVs on the initiation and progression of inflammation, autoimmunity, and cancer. In dermatology, recent studies indicate that EVs play key immunomodulatory roles in inflammatory skin disorders, including psoriasis, atopic dermatitis, lichen planus, bullous pemphigoid, systemic lupus erythematosus, and wound healing. Importantly, EVs can be used as biomarkers of pathophysiological states and/or therapeutic agents, both as carriers of drugs or even as a drug by themselves. In this review, we will summarize current research advances of EVs from different cells and their implications in inflammatory skin disorders, and further discuss their future applications, updated techniques, and challenges in clinical translational medicine.
... Its antimicrobial, antiseptic activity against oral bacteria and wound-healing properties mean that is widely used for therapeutic purposes [7]. Thymol has also been reported to exhibit antioxidant, antispasmodic, anti-platelet aggregation and anti-inflammatory properties [8]. ...
Article
Full-text available
Purpose: Allergic rhinitis is an immunoglobulin-E (Ig-E)-mediated response driven by type 2 helper T cells. Hesperidin and thymol are biological agents that possess antioxidant and anti-inflammatory characteristics. The purpose of this study was to investigate the effects of hesperidin and thymol in rats with ovalbumin-induced allergic rhinitis. Methods: Thirty adult Sprague-Dawley rats were randomly assigned into five groups, each containing six animals. The first group constituted the negative control group, while the remaining groups were exposed to an ovalbumin-induced model of allergic rhinitis. In the provocation stage, 4 mL/kg saline was administered to the positive control group, 10 mg/kg desloratadine to the reference group, 100 mg/kg hesperidin to the hesperidin group, and 20 mg/kg thymol to the thymol group, all by gastric lavage for 7 days. Nasal symptoms were scored on day 22. Rats were then sacrificed, and intracardiac blood specimens were collected to measure plasma total Ig-E, IL-5, IL-13, total antioxidant capacity (TAC), and total oxidant status (TOS) levels. Nasal tissues were extracted for histopathological and immunochemical examination. Results: Nasal symptom scores were highest in the positive control group, while hesperidin and thymol ameliorated these symptoms to the same extent as desloratadine. Ig-E, IL-5, IL-13, and TOS levels increased, while TAC levels decreased significantly in the allergic rhinitis group compared to the other groups. Significant improvement in these parameters was observed in both the hesperidin and thymol groups. At histopathological and immunohistochemical examination of the nasal cavity, severe allergic inflammation and severe TNF-α expression was determined in rats from the allergic rhinitis group. Mild inflammatory changes and mild TNF-α expression were observed in all three treatment groups. Conclusion: Both hesperidin and thymol were effective in suppressing allergic symptoms and inflammation in the treatment of allergic rhinitis.
... For example, it has been reported that Staphylococcus aureus-derived EVs increase the production of pro-inflammatory cytokines in dermal fibroblasts, activate endothelial cells, and induce monocyte recruitment [55,56]. In addition, EVs derived from thymol-treated Staphylococcus aureus showed their therapeutic potential for AD by alleviating skin lesions in AD [57]. SLE is a chronic inflammatory disease caused by the production of various autoantibodies due to viral infection, hormonal abnormalities etc. ...
Article
Full-text available
Extracellular vesicles (EV) deliver cargoes such as nucleic acids, proteins, and lipids between cells and serve as an intercellular communicator. As it is revealed that most of the functions associated to EVs are closely related to the immune response, the important role of EVs in inflammatory diseases is emerging. EVs can be functionalized through EV surface engineering and endow targeting moiety that allows for the target specificity for therapeutic applications in inflammatory diseases. Moreover, engineered EVs are considered as promising nanoparticles to develop personalized therapeutic carriers. In this review, we highlight the role of EVs in various inflammatory diseases, the application of EV as anti-inflammatory therapeutics, and the current state of the art in EV engineering techniques.
... However, after several hours of colonization, S. aureus decreased the number of TJs and, subsequently, that of two other types of epidermal junctions, adherent junctions (AJs) and desmosomes, whereas under the same conditions, S. epidermidis showed a minor effect. Other studies focused on cell viability and inflammation revealed that pathogenic strains such as S. aureus or C. acnes or their metabolites induced cell cytotoxicity and increased the production of pro-inflammatory cytokines in skin cells [113,114]. ...
Article
Full-text available
The skin is the exterior interface of the human body with the environment. Despite its harsh physical landscape, the skin is colonized by diverse commensal microbes. In this review, we discuss recent insights into skin microbial populations, including their composition and role in health and disease and their modulation by intrinsic and extrinsic factors, with a focus on the pathobiological basis of skin aging. We also describe the most recent tools for investigating the skin microbiota composition and microbe-skin relationships and perspectives regarding the challenges of skin microbiome manipulation. 7W31iGBvVzoZokWgqPedthVideo abstract
... Moreover, 24 decreased the production of pro-inflammatory cytokines through the suppression of nuclear factor-κB (NF-κB) and mitogenactivated protein kinases (MAPKs). Thus, it is possible that inflammatory responses caused by thymol-treated S. aureus EVs are inhibited by both the suppression of the transmission of effector molecules (e.g., peptidoglycans) to the host and the inflammatory signaling pathways related to inflammation (Figure 4; Kwon et al., 2018Kwon et al., , 2019. ...
Article
Full-text available
Both Gram-positive and Gram-negative bacteria can secrete extracellular vesicles (EVs), which contain numerous active substances. EVs mediate bacterial interactions with their hosts or other microbes. Bacterial EVs play a double-edged role in infections through various mechanisms, including the delivery of virulence factors, modulating immune responses, mediating antibiotic resistance, and inhibiting competitive microbes. The spread of antibiotic resistance continues to represent a difficult clinical challenge. Therefore, the investigation of novel therapeutics is a valuable research endeavor for targeting antibiotic-resistant bacterial infections. As a pathogenic substance of bacteria, bacterial EVs have gained increased attention. Thus, EV inhibitors are expected to function as novel antimicrobial agents. The inhibition of EV production, EV activity, and EV-stimulated inflammation are considered potential pathways. This review primarily introduces compounds that effectively inhibit bacterial EVs and evaluates the prospects of their application.
Article
Full-text available
Please cite this article as: Martirosyan D., Jahanbakhshi F., Ashoori M. R., Alkhamis S., Pezeshki S., Mikaeili A. S., Mirmiranpour H. Effect of oral administration and topical gel application of thymol and low-level laser therapy on oxidative stress, inflammatory biomarkers and dermatitis in patients with type 2 diabetes mellitus. ABSTRACT Background: Unmanaged diabetes mellitus, as a chronic metabolic disease, has dangerous consequences. The
Article
Full-text available
Extracellular vesicles (EVs), as nanoscale membranous vesicles containing DNAs, RNAs, lipids and proteins, have emerged as promising diagnostic and therapeutic agents for skin diseases. Here, we summarize the basic physiology of the skin and the biological characteristic of EVs. Further, we describe the applications of EVs in the treatment of dermatological conditions such as skin infection, inflammatory skin diseases, skin repair and rejuvenation and skin cancer. In particular, plant-derived EVs and clinical trials are discussed. In addition, challenges and perspectives related to the preclinical and clinical applications of EVs are highlighted.
Article
Atopic dermatitis (AD) can occur in both children and adults, and the symptoms include itching and eczema, which in turn cause patients to suffer. Ophiopogonin D (OP-D) is a steroidal glycoside from Radix Ophiopogon japonicus, which is well known as an effective anti-inflammatory herbal medicine in many Asian countries. In this study, we aimed to investigate the anti-inflammatory effects of OP-D, using an AD mouse model and inflamed HaCaT cells. Through a histopathological analysis, we were able to confirm the suppressive effects of OP-D on skin thickening and the mast cell activation in AD-like mouse back skin tissues stimulated by DNCB. In addition, we detected significant decreases in cytokine expression levels through multiplex assessment assays of the OP-D-treated mice blood. We observed the anti-inflammatory effect of OP-D in the spleen, causing weight loss in the spleen and in the mRNA expression levels related to diverse cytokines. In human keratinocytes inflamed by TNF-α, OP-D inhibited p38 and ERK protein activation and showed a reduction of NF-κB nuclear translocation. Furthermore, OP-D attenuated pro-inflammatory cytokine mRNA expressions in TNF-α-inflamed HaCaT cells. Accordingly, we came to the conclusion that OP-D is a potential natural drug which can be used in order to treat inflammatory skin diseases, such as AD.
Article
The genus Thymus (Lamiaceae) comprises about 214 species throughout the world, mainly found in North Africa, Europe, and temperate Asia zone. They are traditionally used as food additives and folk medicines. This review comprehensively summarizes information about traditional uses, chemical constituents and biological activities of this genus and provides recommendations for future investigations. All information was gathered from scientific databases including Google Scholar, Sci‐Finder, Web of Science, ScienceDirect, and CNKI. Volatile oils are the most concerned constituents of this genus. Flavonoids, phenylpropanoids, tannins, organic acids, terpenoids, and phytosterols were also summarized. This genus plants possessed a variety of activities including antimicrobial, antioxidant, anti‐inflammatory, cytotoxic, analgesic and anti‐diabetic. In brief, this review will be helpful to provide valuable data for explorations and create more interests towards Thymus genus in the future.
Article
Full-text available
Purpose: The purpose of this study was to investigate the effects of 17 essential oils (EOs) on Escherichia coli (E. coli), including their antibacterial activity according to the concentration used and its extraction site.Methods: All 17 EOs were prepared by step dilution at concentrations of 0.5% (v/v) and 1% (v/v). EOs were dispensed into 96-well plates with bacterial culture aliquots and incubated for 18 h; then, their absorbance was measured using a microplate reader.Results: Culture absorbance showed that thyme white (TM), palmarosa (PR) and rosemary verbenone (RM) at concentrations of 0.5% (v/v) and 1% (v/v) showed high antibacterial activity, similar to that of ampicillin. Melisa true (MS), RM, PR, lavender Bulgarian (LV), lemon (LM), peppermint premium (PM) and eucalyptus bluegum (EC) also showed increased antibacterial activity in a concentration-dependent manner. Finally, TM, MS, RM, PR, and lemongrass (LG) extracted from leaves showed higher antibacterial activity than extracts from other organs.Conclusion: TM extracted from leaves showed an excellent antibacterial effect; it exhibited bacterial growth at the same level of ampicillin. It is a natural substance that suppresses the action of bacteria in the inflammatory reaction of the skin and that may be used as a raw material for customized cosmetics.
Article
Full-text available
The additive manufacturing (AM) of bio inspired ceramics has been explored since 1980s. AM is widely used for producing tissue engineering scaffolds and custom bio implants. Direct ink writing is an extrusion-based AM process that overcomes the limitations in traditional scaffold fabricating methods and gives better control over porosity, complexity, reproducibility, flexibility of various materials and patient specific shape. In DIW the material is fed as paste/gel form using an extrusion setup. This paper provides a survey on fabrication of bio ceramic parts by different types of direct ink writing such as writing with molten material, writing in room temperature, writing with photopolymer, and curing by UV light source etc. This paper highlights the advancements in DIW and discusses about various bio-ceramic materials, binders, and compares the mechanical and bio properties of scaffolds fabricated using DIW. Also, this paper describes the experimental works conducted by the authors in DIW of a bio-ceramics. Ó 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the 28th International Conference on Processing and Fabrication of Advanced Materials.
Article
Full-text available
Acute lung injury (ALI) is a life-threatening syndrome which causes a high mortality rate worldwide. In traditional medicine, lots of aromatic plants—such as some Thymus species—are used for treatment of various lung diseases including pertussis, bronchitis, and asthma. Thymol, one of the primary active constituent derived from Thymus vulgaris (thyme), has been reported to exhibit potent anti-microbial, anti-oxidant, and anti-inflammatory activities in vivo and in vitro. The present study aims to investigate the protective effects of thymol in lipopolysaccharide (LPS)-induced lung injury mice model. In LPS-challenged mice, treatment with thymol (100 mg/kg) before or after LPS challenge significantly improved pathological changes in lung tissues. Thymol also inhibited the LPS-induced inflammatory cells influx, TNF-α and IL-6 releases, and protein concentration in bronchoalveolar lavage fluid (BALF). Additionally, thymol markedly inhibited LPS-induced elevation of MDA and MPO levels, as well as reduction of SOD activity. Further study demonstrated that thymol effectively inhibited the NF-κB activation in the lung. Taken together, these results suggested that thymol might be useful in the therapy of acute lung injury.
Article
Full-text available
The potential of plant essential oils (EOs) in anticancer treatment has recently received many research efforts to overcome the development of multidrug resistance and their negative side effects. The aims of the current research are to study (i) the cytotoxic effect of the crude EO extracted from Origanum vulgare subsp hirtum and its main constituents (carvacrol, thymol, citral and limonene) on hepatocarcinoma HepG2 and healthy human renal cells HEK293; (ii) the antibacterial and phytotoxic activities of the above EO and its main constituents. Results showed that cell viability percentage of treated HepG2 by EO and its main constituents was significantly decreased when compared to untreated cells. The calculated inhibition concentration (IC50) values for HepG2 were lower than healthy renal cells, indicating the sort of selectivity of the studied substances. Citral is not potentially recommended as an anticancer therapeutic agent, since there are no significant differences between IC50 values against both tested cell lines. Results showed also that oregano EO and its main constituents have a significant antibacterial activity and a moderate phytotoxic effect. The current research verified that oregano EO and its main constituents could be potentially utilized as anticancer therapeutic agents.
Article
Full-text available
Thymol (2-isopropyl-5-methylphenol) is a natural ingredient used as flavor or preservative agent in food products. The antibacterial mechanism of thymol against Gram-positive, Staphylococcus aureus was investigated in this work. A total of 15 membrane fatty acids were identified in S. aureus cells by gas chromatography–mass spectrometry. Exposure to thymol at low concentrations induced obvious alterations in membrane fatty acid composition, such as decreasing the proportion of branched 12-methyltetradecanoic acid and 14-methylhexadecanoic acid (from 22.4 and 17.3% to 7.9 and 10.3%, respectively). Membrane permeability assay and morphological image showed that thymol at higher concentrations disrupted S. aureus cell membrane integrity, which may decrease cell viability. Moreover, the interaction of thymol with genomic DNA was also investigated using multi-spectroscopic techniques, docking and atomic force microscopy. The results indicated that thymol bound to the minor groove of DNA with binding constant (Ka) value of (1.22 ± 0.14) × 104 M−1, and this binding interaction induced a mild destabilization in the DNA secondary structure, and made DNA molecules to be aggregated. Graphical AbstractThymol exerts its antibacterial effect throught destruction of bacterial cell membrane and binding directly to genomic DNA
Article
Full-text available
Systemic type 2 inflammation encompassing T helper 2 (TH2)-type responses is emerging as a unifying feature of both classically defined allergic diseases, such as asthma, and a range of other inflammatory diseases. Rather than reducing inflammation with broad-acting immunosuppressants or narrowly targeting downstream products of the TH2 pathway, such as immunoglobulin E (IgE), efforts to target the key proximal type 2 cytokines - interleukin-4 (IL-4), IL-5 and IL-13 - represent a promising strategy to achieve therapeutic benefit across multiple diseases. After several initial disappointing clinical results with therapies targeting IL-4, IL-5 or IL-13 in asthma, applying a personalized approach achieved therapeutic benefit in an asthma subtype exhibiting an 'allergic' phenotype. More recently, efficacy was extended into a broad population of people with asthma. This argues that the Type 2 inflammation is broadly relevant across the severe asthma population if the key upstream drivers are properly blocked. Moreover, the simultaneous inhibition of IL-4 and IL-13 has shown significant clinical activity in diseases that are often co-morbid with asthma - atopic dermatitis and chronic sinusitis with nasal polyps - supporting the hypothesis that targeting a central 'driver pathway' could benefit multiple allergic diseases.
Article
Full-text available
Atopic dermatitis (AD) is associated with the effects of T helper type 2 (Th2) and Th22 cytokines. Recent studies, however, have also implicated Th17 in acute AD. Functional studies of Th2 and Th22 cytokines revealed their roles in generating molecular changes during AD; IL-17A's role, however, has yet to be defined. The report by Nakajima et al. (this issue) begins to define that role by demonstrating IL-17A's ability to induce Th2 inflammation in acute disease.
Article
Full-text available
Staphylococcus aureus (SA) has peculiar abilities to colonize the skin in atopic dermatitis (AD) patients. We sought to determine the colonization rates of SA in acute and chronic skin lesions of AD patients, to find any difference in colonization rates according to age and to find the influences of total immunoglobulin E (IgE) and eosinophil counts to the colonization of SA. We evaluated the total IgE level and eosinophil counts, and cultured SA from the skin lesions of 687 AD patients (131 acute and 556 chronic skin lesions) and 247 control urticaria patients (July 2009 to November 2010; Samsung Medical Center Dermatology Clinic, Seoul, Korea). The SA colonization rates were 74%, 38% and 3% in acute, chronic skin lesions and control skin, respectively, and they were increased with age in AD patients. The colonization rate in chronic skin lesions was higher in the high IgE/eosinophilia groups as compared to the normal IgE/eosinophil groups. The SA colonization rate was higher in AD patients and especially in acute lesions, and had a tendency to increase with age. As the colonization rates were only higher in the high IgE/eosinophilia groups of chronic skin lesions, we suggested that SA may invade the skin through barrier defects in acute skin lesions, but the colonization in chronic lesions may be orchestrated through many different factors.
Article
Full-text available
Acinetobacter baumannii is increasingly becoming a major nosocomial pathogen. This opportunistic pathogen secretes outer membrane vesicles (OMVs) that interact with host cells. The aim of this study was to investigate the ability of A. baumannii OMVs to elicit a pro-inflammatory response in vitro and the immunopathology in response to A. baumannii OMVs in vivo. OMVs derived from A. baumannii ATCC 19606(T) induced expression of pro-inflammatory cytokine genes, interleukin (IL)-1β and IL-6, and chemokine genes, IL-8, macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1, in epithelial cells in a dose-dependent manner. Disintegration of OMV membrane with ethylenediaminetetraacetic acid resulted in low expression of pro-inflammatory cytokine genes, as compared with the response to intact OMVs. In addition, proteinase K-treated A. baumannii OMVs did not induce significant increase in expression of pro-inflammatory cytokine genes above the basal level, suggesting that the surface-exposed membrane proteins in intact OMVs are responsible for pro-inflammatory response. Early inflammatory processes, such as vacuolization and detachment of epithelial cells and neutrophilic infiltration, were clearly observed in lungs of mice injected with A. baumannii OMVs. Our data demonstrate that OMVs produced by A. baumannii elicit a potent innate immune response, which may contribute to immunopathology of the infected host.
Article
Full-text available
Gram-negative bacteria produce outer membrane vesicles that play a role in the delivery of virulence factors to host cells. However, little is known about the membrane-derived vesicles (MVs) produced by gram-positive bacteria. The present study examined the production of MVs from Staphylococcus aureus and investigated the delivery of MVs to host cells and subsequent cytotoxicity. Four S. aureus strains tested, two type strains and two clinical isolates, produced spherical nanovesicles during in vitro culture. MVs were also produced during in vivo infection of a clinical S. aureus isolate in a mouse pneumonia model. Proteomic analysis showed that 143 different proteins were identified in the S. aureus-derived MVs. S. aureus MVs were interacted with the plasma membrane of host cells via a cholesterol-rich membrane microdomain and then delivered their component protein A to host cells within 30 min. Intact S. aureus MVs induced apoptosis of HEp-2 cells in a dose-dependent manner, whereas lysed MVs neither delivered their component into the cytosol of host cells nor induced cytotoxicity. In conclusion, this study is the first report that S. aureus MVs are an important vehicle for delivery of bacterial effector molecules to host cells.
Article
Full-text available
Recently, we found that Staphylococcus aureus produces extracellular vesicles (EV) that contain pathogenic proteins. Although S. aureus infection has been linked with atopic dermatitis (AD), the identities of the causative agents from S. aureus are controversial. We evaluated whether S. aureus-derived EV are causally related to the pathogenesis of AD. Extracellular vesicles were isolated by the ultracentrifugation of S. aureus culture media. The EV were applied three times per week to tape-stripped mouse skin. Inflammation and immune dysfunction were evaluated 48 h after the final application in hairless mice. Extracellular vesicles-specific IgE levels were measured by ELISA in AD patients and healthy subjects. The in vitro application of S. aureus EV increased the production of pro-inflammatory mediators (IL-6, thymic stromal lymphopoietin, macrophage inflammatory protein-1α, and eotaxin) by dermal fibroblasts. The in vivo application of S. aureus EV after tape stripping caused epidermal thickening with infiltration of the dermis by mast cells and eosinophils in mice. These changes were associated with the enhanced cutaneous production of IL-4, IL-5, IFN-γ, and IL-17. Interestingly, the serum levels of S. aureus EV-specific IgE were significantly increased in AD patients relative to healthy subjects. These results indicate that S. aureus EV induce AD-like inflammation in the skin and that S. aureus-derived EV are a novel diagnostic and therapeutic target for the control of AD.
Article
Full-text available
AD, atopic dermatitis; LTA, lipoteichoic acid; SPA, staphylococcal protein A
Article
Full-text available
Targeting bacterial virulence factors is now gaining interest as an alternative strategy to develop new types of anti-infective agents. It has been shown that thymol, when used at low concentrations, can inhibit the TSST-1 secretion in Staphylococcus aureus. However, there are no data on the effect of thymol on the production of other exotoxins (e.g., alpha-hemolysin and enterotoxins) by S. aureus. Secretion of alpha-hemolysin, SEA and SEB in both methicillin-sensitive and methicillin-resistant S. aureus isolates cultured with graded subinhibitory concentrations of thymol was detected by immunoblot analysis. Hemolysin and tumor necrosis factor (TNF) release assays were performed to elucidate the biological relevance of changes in alpha-hemolysin, SEA and SEB secretion induced by thymol. In addition, the influence of thymol on the transcription of hla, sea, and seb (the genes encoding alpha-hemolysin, SEA and SEB, respectively) was analyzed by quantitative RT-PCR. Thymol inhibited transcription of hla, sea and seb in S. aureus, resulting in a reduction of alpha-hemolysin, SEA and SEB secretion and, thus, a reduction in hemolytic and TNF-inducing activities. Subinhibitory concentrations of thymol decreased the production of alpha-hemolysin, SEA and SEB in both MSSA and MRSA in a dose-dependent manner. These data suggest that thymol may be useful for the treatment of S. aureus infections when used in combination with beta-lactams and glycopeptide antibiotics, which induce expression of alpha-hemolysin and enterotoxins at subinhibitory concentrations. Furthermore, the structure of thymol may potentially be used as a basic structure for development of drugs aimed against these bacterial virulence factors.
Article
Full-text available
Thymol (THY) was found to have in vitro antifungal activity against 24 fluconazole (FLC)-resistant and 12 FLC-susceptible clinical isolates of Candida albicans, standard strain ATCC 10231 and one experimentally induced FLC-resistant C. albicans S-1. In addition, synergism was observed for clinical isolates of C. albicans with combinations of THY-FLC and THY-amphotericin B (AMB) evaluated by the chequerboard microdilution method. The interaction intensity was determined by spectrophotometry for the chequerboard assay, and the nature of the interactions was assessed using two non-parametric approaches [fractional inhibitory concentration index (FICI) and DeltaE models]. The interaction between THY-FLC or THY-AMB in FLC-resistant and -susceptible strains of C. albicans showed a high percentage of synergism by the FICI method and the DeltaE method. The DeltaE model gave results consistent with FICI, and no antagonistic action was observed in the strains tested.
Article
Full-text available
Menstrual toxic shock syndrome is a rare but potentially life-threatening illness manifest through the actions of Staphylococcus aureus toxic shock syndrome toxin 1 (TSST-1). Previous studies have shown that tampon additives can influence staphylococcal TSST-1 production. We report here on the TSST-1-suppressing activity of 34 compounds that are commonly used additives in the pharmaceutical, food, and perfume industries. Many of the tested chemicals had a minimal impact on the growth of S. aureus and yet were potent inhibitors of TSST-1 production. The TSST-1-reducing compounds included surfactants with an ether, amide, or amine linkage to their fatty acid moiety (e.g., myreth-3-myristate, Laureth-3, disodium lauroamphodiacetate, disodium lauramido monoethanolamido, sodium lauriminodipropionic acid, and triethanolamine laureth sulfate); aromatic compounds (e.g. phenylethyl and benzyl alcohols); and several isoprenoids and related compounds (e.g., terpineol and menthol). The membrane-targeting and -altering effects of the TSST-1-suppressing compounds led us to assess the activity of molecules that are known to inhibit fatty acid biosynthesis (e.g., cerulenin, triclosan, and hexachlorophene). These compounds also reduced S. aureus TSST-1 production. This study suggests that more additives than previously recognized inhibit the production of TSST-1.
Article
Full-text available
After exposure of the skin to microbes, the host develops skin-specific inflammation and an acquired immune response, in which keratinocytes (KC) and Langerhans cells play critical roles respectively. We established two animal models. (i) We examined the importance of KC-derived IL-18 for the systemic IgE response by using a skin transplantation model. As previously reported, transgenic mice (KCASP1Tg), that over-express caspase-1 in their KC, display high serum levels of IgE, and spontaneously develop chronic dermatitis by production of IL-18 and IL-1beta. We examined the capacity of transplantation of cutaneous lesions from KCASP1Tg to induce IgE production in wild-type or mutant mice with a syngeneic background. Transplantation of active cutaneous lesions, that expressed high levels of IL-18 and IL-1beta, induced long-lasting IgE production in wild-type mice without elevation of circulating IL-18 and IL-1beta. Furthermore, IL-18R-, CD4- or stat6-deficient mice transplanted with the lesions did not produce IgE, indicating that this IgE response is initiated by IL-18, and dependent on host-derived CD4(+) T cells and stat6. (ii) We investigated IL-18 secretion from KC upon stimulation with microbe products. Freshly isolated KC from wild-type mice secreted IL-18 in response to Protein A purified from Cowan 1 strain of Staphylococcus aureus (SpA), which often exacerbates human skin diseases, including atopic dermatitis. Cutaneous application of SpA increased serum levels of IL-18 and IgE. These results indicate that local accumulation of IL-18 triggers systemic IgE responses without exposure to antigen.
Article
Full-text available
The in vitro and in vivo antileishmanial and cytotoxic activities of thymol and structural derivatives in comparison to those of Glucantime were studied. The results showed here suggest that thymol and hemisynthetic derivatives have promising antileishmanial potential and could be considered as new lead structures in the search for novel antileishmanial drugs.
Article
Full-text available
In the present paper, we report the antimicrobial efficacy of three monoterpenes [linalyl acetate, (+)menthol, and thymol] against the gram-positive bacterium Staphylococcus aureus and the gram-negative bacterium Escherichia coli. For a better understanding of their mechanisms of action, the capability of these three monoterpenes to damage biomembranes was evaluated by monitoring the release, following exposure to the compounds under study, of the water-soluble fluorescent marker carboxyfluorescein from unilamellar vesicles with different lipidic compositions (phosphatidylcholine, phosphatidylcholine/phosphatidylserine [9:1], phosphatidylcholine/stearylamine [9:1], and phosphatidylglycerol/cardiolipin [9:1]). Furthermore, the interaction of the terpenes tested with dimyristoylphosphatidylcholine multilamellar vesicles as model membranes was monitored by means of differential scanning calorimetry. Finally, the results were related to the relative lipophilicity and water solubility of the compounds examined. Taken together, our findings lead us to speculate that the antimicrobial effect of (+)menthol, thymol, and linalyl acetate may result, at least partially, from a perturbation of the lipid fraction of microorganism plasma membrane, resulting in alterations of membrane permeability and in leakage of intracellular materials. Besides being related to physicochemical characteristics of the drugs (such as lipophilicity and water solubility), this effect seems to be dependent on lipid composition and net surface charge of microbial membranes. Furthermore, the drugs might cross the cell membranes, penetrating into the interior of the cell and interacting with intracellular sites critical for antibacterial activity.
Article
Full-text available
Atopic dermatitis (AD) is a common inflammatory skin disease of unknown etiology. Cutaneous infection with microbes such as Staphylococcus aureus and/or skin cleansing with detergent exacerbates clinical AD. Here, we generated an AD animal model by destroying skin barrier function with detergent and subsequent topical application of protein A from S. aureus (SpA). NC/Nga mice, which genetically have reduced skin barrier function, and BALB/c mice having intact skin barrier function, were susceptible to this combination and developed severe and moderate AD, respectively, associated with dermal accumulation of eosinophils and mast cells. Both types of mice showed an increase in serum levels of IL-18, but not IgE. The epidermis of the NC/Nga mice rapidly expressed T helper type 1 (Th1)-associated chemokines, including ligands for CXCR3 and CCR5, after application of both SpA and detergent, but not after application of detergent alone. Although treatment with detergent induced moderate Th1 cell response, additional SpA treatment was a prerequisite for induction of the differentiation of naive T cells toward unique Th1 cells, termed “super Th1 cells,” capable of producing both Th1 (IFN-γ) and T helper type 2 cytokine (IL-13), as well as IL-3, and expressing CXCR3 and CCR5. Induction of super Th1 cells required IL-18 stimulation. Blockade of IL-18 prevented AD development, whereas blockade of IL-3 partially prevented AD development, suggesting a contribution of IL-18-dependent IL-3 production to AD with cutaneous mastocytosis. il18 −/−BALB/c mice similarly evaded SDS/SpA-induced AD. Thus, IL-18 might be important for the development of infection-associated AD by induction of IL-3 from super Th1 cells. • IL-3 • protein A • IFN-γ • super Th1 cells • intrinsic atopic dermatitis
Article
Full-text available
Atopic dermatitis is a chronic inflammatory skin disease associated with cutaneous hyperreactivity to environmental triggers and is often the first step in the atopic march that results in asthma and allergic rhinitis. The clinical phenotype that characterizes atopic dermatitis is the product of interactions between susceptibility genes, the environment, defective skin barrier function, and immunologic responses. This review summarizes recent progress in our understanding of the pathophysiology of atopic dermatitis and the implications for new management strategies.
Article
Full-text available
The role of staphylococcal superantigens in the pathophysiology of atopic dermatitis (AD) has been the focus of intense interest during the past decade. Although the increased prevalence of Staphylococcus aureus and its bacterial toxins in AD skin is well established, exploitation of the known mechanisms of superantigens in this disease for the development of novel therapies remains an active area of research. With the emergence of multi-drug resistant S. aureus, the need for a better understanding of the pathophysiology of bacterial superantigens in AD has become increasingly important. This review examines the mechanisms of S. aureus colonization and infection, of which the most important are defective skin barrier function, increased S. aureus adherence, and the decreased innate immune responses found in AD skin. The contribution of superantigens to the pathophysiology of AD is then discussed. Important immunologic mechanisms in this context include the role of superantigens in promoting T helper-2 skin inflammation, IgE production, T-regulatory cell subversion, expansion and migration of skin-homing T cells, and IgE anti-superantigen production. Lastly, these findings are discussed with reference to current therapeutic approaches, of which the most important include anti-inflammatory and antimicrobial medications, and future strategies, which are expected to consist of immune-modulators and synthetic antibacterials.
Article
Staphylococcus aureus colonization contributes to skin inflammation in diseases such as atopic dermatitis, but the signaling pathways involved are unclear. Herein, epicutaneous S. aureus exposure to mouse skin promoted MyD88-dependent skin inflammation initiated by IL-36, but not IL-1α/β IL-18, or IL-33. By contrast, an intradermal S. aureus challenge promoted MyD88-dependent host defense initiated by IL-1β rather than IL-36, suggesting that different IL-1 cytokines trigger MyD88 signaling depending on the anatomical depth of S. aureus cutaneous exposure. The bacterial virulence factor PSMα but not α-toxin or δ-toxin, contributed to the skin inflammation, which was driven by IL-17-producing γδ and CD4⁺ T cells via direct IL-36R signaling in the T cells. Finally, adoptive transfer of IL-36R-expressing T cells to IL-36R-deficient mice was sufficient for mediating S. aureus-induced skin inflammation. Together, this study defines a previously unknown pathway by which S. aureus epicutaneous exposure promotes skin inflammation involving IL-36R/MyD88-dependent IL-17 T cell responses. Staphylococcus aureus colonization during atopic dermatitis contributes to skin inflammation, but the underlying mechanisms are unclear. Liu et al. demonstrate that epicutaneous S. aureus exposure drives skin inflammation, which is mediated by bacterial PSMα and host IL-36R/MyD88-induced production of IL-17 by T cells.
Article
Background: Colon cancer is one of the most deadly and common carcinomas occurring worldwide and there have been many attempts to treat this cancer. The present work was designed in order to evaluate thymol as a potent drug against colon cancer. Materials and methods: Cytotoxicity of thymol at different concentrations was evaluated against a human colon carcinoma cell line (HCT-116 cells). Fluorescent staining was carried out to evaluate the level of ROS as well as mitochondrial and DNA fragmentation and immunoblot analysis were performed to confirm apoptosis and mitoptosis. Results and conclusion: Results of the study demonstrated that thymol efficiently created an oxidative stress environment inside HCT-116 cells, a colorectal carcinoma cell line, through induction of ROS production along with intense damage to DNA and mitochondria, as observed through Hoechst and rhodamine 123 staining, respectively. Moreover, expression of PARP-1, p-JNK, cytochrome-C and caspase-3 proteins was up-regulated, suggesting HCT-116 cells underwent mitoptotic cell death. Therefore, thymol could be used as a potent drug against colon cancer due to its lower toxicity and prevalence in natural medicinal plants.
Article
Background: Skin colonization or infection with Staphylococcus aureus is known to trigger aggravation of atopic dermatitis (AD). However, the exact mechanisms by which S. aureus can worsen AD are unknown. Objective: We investigated whether and how S. aureus-derived membrane vesicles (MVs) contribute to worsening of AD. Methods: Immunohistochemical and immunoelectron microscopic analyses were performed to detect staphylococcal protein A (SPA) in the epidermis of AD lesions. HaCaT cells were treated with S. aureus MVs and were analysed for the expression of cytokine genes. Immunopathology and cytokine gene profiles were analysed after topical application of S. aureus MVs to AD-like skin lesions in a mouse model. Results: The MV component SPA was detected in the keratinocytes as well as in the intercellular space of the epidermis of AD lesions colonized with S. aureus. Intact MVs from S. aureus delivered their components to keratinocytes and stimulated pro-inflammatory cytokine gene expression in vitro. A knock-down of Toll-like receptor 2 or nucleotide-binding oligomerization domain 2 using small interfering RNAs suppressed interleukin-8 gene expression. Topical application of intact S. aureus MVs to AD-like skin lesions in the mouse model induced massive infiltration of inflammatory cells and the resulting eczematous dermatitis. This inflammatory reaction was associated with a mixed Th1/Th2 immune response and enhanced expression of chemokine genes in AD-like skin lesions. Conclusions and clinical relevance: This study showed the importance of S. aureus MVs as a potent mediator for worsening of AD among many exogenous worsening factors of AD. Thus, S. aureus MVs may be regarded as one of the therapeutic targets for the management of AD aggravation.
Article
Atopic dermatitis (AD) is a multifactorial skin disease with skin barrier damage, progressive sensitization to environmental antigens, and TH2-skewed mediated systemic immune response.1 Synthesis of filaggrin and filaggrin-like stratum corneum proteins is reduced both on lesional and on nonlesional skin of patients with AD irrespective of their FLG genotype.2
Article
Numerous plants have been documented to contain phenolic compounds. Thymol is one among these phenolic compounds that possess repertoire of pharmacological activities including anti-inflammatory, anticancer, antioxidant, antibacterial and antimicrobial activities. Despite of the plethora of affects elicited by thymol, its activity profile on gastric cancer cells is not explored. In this study, we discovered that thymol exerts anticancer effects by suppressing cell growth, inducing apoptosis, producing intracellular reactive oxygen species (ROS), depolarizing mitochondrial membrane potential (MMP), and activating proapoptotic mitochondrial proteins Bax, cysteine aspartases (caspases), and poly ADP ribose polymerase (PARP) in human gastric AGS cells. The outcomes of this study displayed that thymol, via intrinsic mitochondrial pathway was responsible for inducing apoptosis in gastric AGS cells. Hence, thymol might serve as a tentative agent in the future to treat cancer.
Article
Atopic dermatitis (also known as atopic eczema) is a chronic inflammatory skin disease that is characterised by intense itching and recurrent eczematous lesions. Although it most often starts in infancy and affects two of ten children, it is also highly prevalent in adults. It is the leading non-fatal health burden attributable to skin diseases, inflicts a substantial psychosocial burden on patients and their relatives, and increases the risk of food allergy, asthma, allergic rhinitis, other immune-mediated inflammatory diseases, and mental health disorders. Originally regarded as a childhood disorder mediated by an imbalance towards a T-helper-2 response and exaggerated IgE responses to allergens, it is now recognised as a lifelong disposition with variable clinical manifestations and expressivity, in which defects of the epidermal barrier are central. Present prevention and treatment focus on restoration of epidermal barrier function, which is best achieved through the use of emollients. Topical corticosteroids are still the first-line therapy for acute flares, but they are also used proactively along with topical calcineurin inhibitors to maintain remission. Non-specific immunosuppressive drugs are used in severe refractory cases, but targeted disease-modifying drugs are being developed. We need to improve understanding of the heterogeneity of the disease and its subtypes, the role of atopy and autoimmunity, the mechanisms behind disease-associated itch, and the comparative effectiveness and safety of therapies.
Article
The aim of this work was to investigate the modifications of cell membrane fatty acid composition and volatile molecule profiles of Listeria monocytogenes, Salmonella enteritidis, Escherichia coli, during growth in the presence of different sub-lethal concentrations of thyme and oregano essential oils as well as carvacrol, thymol, trans-2-hexenal and citral. The results evidenced that the tested molecules induced noticeable modifications of membrane fatty acid profiles and volatile compounds produced during the growth. Although specific differences in relation to the species considered were identified, the tested compounds induced a marked increase of some membrane associated fatty acids, particularly unsaturated fatty acids, trans-isomers, and specific released free fatty acids. These findings can contribute to the comprehension of the stress response mechanisms used by different pathogenic microorganisms often involved in food-borne diseases in relation to the exposure to sub-lethal concentrations of natural antimicrobials. Copyright © 2015 Elsevier Ltd. All rights reserved.
Article
Patients with atopic dermatitis (AD) are commonly colonized/infected with Staphylococcus aureus, and this bacterium is known to worsen the dermatitis. In this issue, Brauweiler et al. demonstrate a newly discovered mechanism by which Th2 cytokines involved in AD augment the toxicity of the lytic staphylococcal protein alpha toxin. This review presents mechanisms by which Th2 cytokines may interact with S. aureus to the detriment of the dermatitis.
Article
Salmonella is a common bacterial enteropathogen responsible for many deaths every year. In the present study, we evaluated the mechanism of action of thymol against Salmonella ser. Typhimurium, as well as its potential to induce intracellular killing and recovery from oxidative stress in macrophages. The minimum inhibitory concentration (MIC) of thymol against S. Typhimurium was found to be 750 mg/l, and the CFU count decreased in a time-dependent manner. Excessive release of cellular materials and potassium ion also occurred in a time-dependent manner. Scanning electron microscopy showed disruption of membrane integrity. Intracellular killing capacity of macrophages was enhanced upon thymol treatment compared to control untreated cells. Thymol significantly reduced production of nitric oxide in a time-dependent manner, as well as the glutathione level. Disruption of membrane integrity was confirmed as the principle mechanism of action of thymol against S. Typhimurium. Further, its potent role in inducing intracellular killing of S. Typhimurium and recovery from oxidative stress in macrophages suggests that thymol can be applied as a naturally occurring drug against S. Typhimurium in place of synthetic drugs.
Article
Background: Atopic dermatitis (AD) and psoriasis patients are frequently colonized with Staphylococcus aureus (S. aureus) that produce the staphylococcal exotoxin α-toxin. However, only patients with AD suffer from bacterial superinfections with this pathogen, which implicates immunological differences in AD vs psoriasis in combating these bacteria. S. aureus recognition is partially mediated by intracellular nucleotide-binding oligomerization domain receptors (NLRs), which link α-toxin to caspase-1 activation through the formation of the NLRP3 inflammasome and to IL-1β secretion. Objective: To investigate (i) NLRP3 expression in the context of different T-helper cytokine milieus and (ii) its function in response to sublytic α-toxin stimulation in patients with AD and psoriasis compared with healthy controls. Methods: NLRP3 expression and function were investigated in lesional AD and psoriasis skin as well as in primary keratinocytes (HPKs) and monocytes upon stimulation with Th1, Th2, Th17 and Th22 cytokines or staphylococcal α-toxin, respectively, at the mRNA and protein (ELISA, immunohistochemistry and immunofluorescence) level. Results: NLRP3 and caspase-1 expressions were reduced in lesional AD skin compared to psoriatic and healthy skin. IL-4, IL-5 and IL-13 downregulated NLRP3 and ASC, whereas interferon-γ upregulated NLRP3 in HPKs. In monocytes, caspase-1 expression was reduced by Th2 cytokines and enhanced by a Th1 milieu. Caspase-1-dependent IL-1β secretion was impaired in monocytes from patients with AD compared to patients with psoriasis and healthy controls by α-toxin stimulation following priming with lipoteichoic acid. Conclusion: Impaired NLRP3 expression and function may partially explain how skin colonization and infection with S. aureus can contribute to chronic skin inflammation in AD.
Article
The purpose of this investigation was to compare the genotypic profiles of Staphylococcus aureus isolated from atopic dermatitis (AD) patients and from control subjects, and to study the relationship between clinical severity, immune response, and genomic pattern of S. aureus isolated from AD patients. We selected 32 patients with AD and S. aureus skin colonization and 31 atopic controls with no history of AD who where asymptomatic carriers of S. aureus. Microarray-based genotyping was performed on S. aureus isolates. In AD patients, clinical severity was assessed using the Scoring Atopic Dermatitis index and total IgE levels and staphylococcal superantigen-specific IgE levels (SEA, SEB, SEC, TSST1) were determined. The genes lukE, lukD, splA, splB, ssl8, and sasG were more frequent in isolates from AD patients. CC30 was more common in isolates from atopic controls than in AD patients. There was a correlation between total IgE and clinical severity, but an association between clinical severity, immune response, and the presence of S. aureus superantigen genes, including enterotoxin genes, could not be demonstrated. Finally, a correlation was found between AD severity and other S. aureus genes, such as sasG and scn. S. aureus factors besides superantigens could be related to the worsening and onset of AD.
Article
Thymol is a natural monoterpene phenol primarily found in thyme, oregano, and tangerine peel. It has been shown to possess anti-inflammatory property both in vivo and in vitro. In the present paper, we studied the anti-inflammatory effect of thymol in lipopolysaccharide (LPS)-stimulated mouse mammary epithelial cells (mMECs). The mMECs were stimulated with LPS in the presence or absence of thymol (10, 20, 40 μg/mL). The concentrations of tumor necrosis factor α (TNF-α), interleukin (IL)-6, and IL-1β in the supernatants of culture were determined using enzyme-linked immunosorbent assay. Cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), extracellular signal-regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), nuclear factor-κB (NF-κB), and inhibitor protein of NF-κB (IκBα) were measured using western blot. The results showed that thymol markedly inhibited the production of TNF-α and IL-6 in LPS-stimulated mMECs. The expression of iNOS and COX-2 was also suppressed by thymol in a dose-dependent manner. Furthermore, thymol blocked the phosphorylation of IκBα, NF-κB p65, ERK, JNK, and p38 mitogen-activated protein kinases (MAPKs) in LPS-stimulated mMECs. These results indicate that thymol exerted anti-inflammatory property in LPS-stimulated mMECs by interfering the activation of NF-κB and MAPK signaling pathways. Thereby, thymol may be a potential therapeutic agent against mastitis.
Article
Atopic dermatitis (AD) and allergic contact dermatitis (ACD) are common allergic and inflammatory skin diseases caused by a combination of eczema, scratching, pruritus, and cutaneous sensitization with allergens. This paper examines whether oleanolic acid acetate (OAA) modulates AD and ACD symptoms by using an existing AD model based on the repeated local exposure of mite extract (Dermatophagoides farinae extract, DFE) and 2,4-dinitrochlorobenzene to the ears of BALB/c mice. In addition, the paper uses a 2,4-dinitrofluorobenzene-sensitized local lymph node assay (LLNA) for the ACD model. The oral administration of OAA over a four-week period attenuated AD symptoms in terms of decreased skin lesions, epidermal thickness, the infiltration of immune cells (CD4(+) cells, eosinophils, and mast cells), and serum IgE, IgG2a, and histamine levels. The gene expression of Th1, Th2, Th17, and Th22 cytokines was reduced by OAA in the lymph node and ear tissue, and the LLNA verified that OAA suppressed ACD. The oral administration of OAA over a three-day period attenuated ACD symptoms in terms of ear thickness, lymphocyte proliferation, and serum IgG2a levels. The gene expression of Th1, Th2, and Th17 cytokines was reduced by OAA in the thymus and ear tissue. Finally, to define the underlying mechanism, this paper uses a TNF-α/IFN-γ-activated human keratinocytes (HaCaT) model. OAA inhibited the expression of cytokines and chemokines through the downregulation of NF-ĸB and MAPKs in HaCaT cells. Taken together, the results indicate that OAA inhibited AD and ACD symptoms, suggesting that OAA may be effective in treating allergic skin disorders.
Article
Orchestrating when and how the cutaneous innate immune system should respond to commensal or pathogenic microbes is a critical function of the epithelium. The cutaneous innate immune system is a key determinant of the physical, chemical, microbial, and immunologic barrier functions of the epidermis. A malfunction in this system can lead to an inadequate host response to a pathogen or a persistent inflammatory state. Atopic dermatitis is the most common inflammatory skin disorder and characterized by abnormalities in both skin barrier structures (stratum corneum and tight junctions), a robust T(H)2 response to environmental antigens, defects in innate immunity, and an altered microbiome. Many of these abnormalities may occur as the consequence of epidermal dysfunction. The epidermis directly interfaces with the environment and, not surprisingly, expresses many pattern recognition receptors that make it a key player in cutaneous innate immune responses to skin infections and injury. This review will discuss the role epidermal innate receptors play in regulation of skin barriers and, where possible, discuss the relevance of these findings for patients with atopic dermatitis.
Article
Atopic dermatitis patients have an increased number of type 2 helper (T(H)2) cells in their peripheral blood and superficial Staphylococcus aureus colonization. The purpose of this study was to clarify the effects of peptidoglycan (PEG) from S aureus on the induction of the TH2 immune response in mice. Mice were primed with PEG- and ovalbumin (OVA)-pulsed Langerhans cells (LCs) and given a booster OVA injection 2 days later via the hind footpad. Five days later, the cytokine response in the draining popliteal lymph nodes was investigated by reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA). IL-12 production from cultured LCs was detected by ELISA and Western blot analysis. Administration of PEG- and OVA-pulsed LCs into the hind footpads of the mice induced a T(H)2-prone immune response as represented by the enhanced interleukin (IL) 4 expression in the lymph nodes. We further showed that higher levels of IL-12 p40 production by PEG-stimulated LCs relative to IL-12 p70 (p35/p40) production were associated with the induction of the T(H)2 immune response.The LC-derived IL-12 p40 protein induced by PEG stimulation was detected mainly as monomeric and homodimeric IL-12 p40 subunits; other heterodimers including the L-12 p40 subunit, such as IL-23, were undetected. These results suggest that PEG may have the ability to induce the development of T(H)2 cells through insufficient production of IL-12 p70 and excessive production by LCs of homodimeric IL-12 p40, a known antagonist of bioactive IL-12 p70, offering a possible explanation for the role of S aureus colonization in patients with atopic dermatitis.
Article
The bactericidal action of thymol and cymene on two Bacillus cereus strains (INRA-AVTZ415 and INRA-AVZ421) was studied. Increasing concentrations of thymol (0.2–1.0 mmol l−1) or cymene (0.2–2.0 mmol l−1) showed higher bactericidal effect on exponential growth phase B. cereus cells suspended in HEPES buffer (pH 7), at 30°C. The two strains tested presented different sensitivity to these natural antimicrobials. When thymol and cymene were combined, it resulted in a greater bactericidal effect on B. cereus cells than when these compounds in the essential oil fraction of aromatic plants were applied separately. There was a synergistic effect of both natural antimicrobials on the viability of exponential growth phase B. cereus cells in pH 7 HEPES buffer, at 30°C. Survivor curves did not follow a first-order kinetics, which makes it difficult to establish processing conditions. Experimental data were modeled using a frequency distribution function (Weibull). This model guaranteed a good description of the experimental results and allowed predictions of time to a specific decrease in bacterial populations. This study indicates the potential use of thymol and cymene applied separately or simultaneously for preservation of minimally processed foods, as well as the validity of the Weibull distribution to describe the resulting nonlinear data and establish effective treatment conditions with these compounds.
Article
Antioxidants minimize oxidation of the lipid components in foods. There is an increasing interest in the use of natural and/or synthetic antioxidants in food preservation, but it is important to evaluate such compounds fully for both antioxidant and pro-oxidant properties. The properties of thymol, carvacrol, 6-gingerol, hydroxytyrosol and zingerone were characterized in detail. Thymol, carvacrol, 6-gingerol and hydroxytyrosol decreased peroxidation of phospholipid liposomes in the presence of iron(III) and ascorbate, but zingerone had only a weak inhibitory effect on the system. The compounds were good scavengers of peroxyl radicals (CCl3O2; calculated rate constants > 106m−1 sec−1) generated by pulse radiolysis. Thymol, carvacrol, 6-gingerol and zingerone were not able to accelerate DNA damage in the bleomycin-Fe(III) system. Hydroxytyrosol promoted deoxyribose damage in the deoxyribose assay and also promoted DNA damage in the bleomycin-Fe(III) system. This promotion was inhibited strongly in the deoxyribose assay by the addition of bovine serum albumin to the reaction mixtures. Our data suggest that thymol, carvacrol and 6-gingerol possess useful antioxidant properties and may become important in the search for ‘natural’ replacements for ‘synthetic’ antioxidant food additives.
Article
The Lindera obtusiloba has been used in traditional medicine for the treatment of inflammation and dermatitis. In this study, we investigated the effect of topical application of Lindera obtusiloba water extract (LOWE) on the house dust mite extract (Dermatophagoides farinae extract, DFE) and 2,4-dinitrochlorobenzene (DNCB)-induced atopic dermatitis (AD). We established AD model in BALB/c mice by repeated local exposure of DFE/DNCB to the ears. After a topical application of LOWE on the skin lesions, the epidermal thickness, mast cell infiltration, and serum immunoglobulin E (IgE) and histamine were measured. In addition, the gene expression of interleukin (IL)-4, IL-13, IL-31, and tumor necrosis factor (TNF)-α in the ears was assayed. LOWE reduced AD symptoms based on ear thickness, histopathological analysis, and serum IgE levels. LOWE inhibited mast cell infiltration into the ear and elevation of serum histamine in AD model. Moreover, LOWE suppressed DFE/DNCB-induced expression of IL-4, IL-13, IL-31, and TNF-α in the ears. Our results showed that topical application of LOWE exerts beneficial effects in AD symptoms, suggesting that LOWE might be a candidate for the treatment of AD.
Article
Atopic dermatitis (AD) is a chronic inflammatory skin disease with specific immune and inflammatory mechanisms. Atopy is among the major features of the diagnosis criteria for AD but is not an essential feature. Thus, patients diagnosed with AD can be atopic or non-atopic. This review focuses on the role of IgE, mast cells, and eosinophils in the pathogenesis of AD. The known functions of IgE in allergic inflammation suggest that IgE and IgE-mediated mast cell and eosinophil activation contribute to AD, but direct evidence supporting this is scarce. The level of IgE (thus the degree of allergic sensitization) is associated with severity of AD and contributed by abnormality of skin barrier, a key feature of AD. The function of IgE in development of AD is supported by the beneficial effect of anti-IgE therapy in a number of clinical studies. The role of mast cells in AD is suggested by the increase in the mast cell number and mast cell activation in AD lesions and the association between mast cell activation and AD. It is further suggested by their role in mouse models of AD as well as by the effect of therapeutic agents for AD that can affect mast cells. The role of eosinophils in AD is suggested by the presence of eosinophilia in AD patients and eosinophil infiltrates in AD lesions. It is further supported by information that links AD to cytokines and chemokines associated with production, recruitment, and activation of eosinophils.
Article
Staphylococcus aureus heavily colonizes the lesions of patients with atopic dermatitis (AD) and is known to trigger a worsening of AD. However, the exact mechanism by which S. aureus promotes AD is unknown. Thymic stromal lymphopoietin (TSLP), which is highly expressed by keratinocytes in skin lesions of patients with AD and bronchial epithelial cells in asthmatic patients, represents a critical factor linking responses at interfaces between the body and the environment to allergic type 2 immune responses. We sought to examine the ability of synthetic lipopeptides and S. aureus to induce TSLP expression in human keratinocytes and identify the pathway of induction. We stimulated primary human keratinocytes with lipopeptides and S. aureus-derived materials. The release and gene expression of TSLP were measured by means of ELISA and quantitative PCR, respectively. Diacylated lipopeptide upregulated the expression of TSLP and other proinflammatory molecules. Heat-killed S. aureus and the subcellular fractions of S. aureus induced TSLP's release, with the membranous fraction having the greatest activity. Small interfering RNA-mediated knockdown of either Toll-like receptor (TLR) 2 or TLR6 inhibited the diacylated lipopeptide- and S. aureus membrane-induced TSLP gene expression. S. aureus membrane- and diacylated lipopeptide-induced release of TSLP was enhanced by T(H)2/TNF-α cytokines and partially suppressed by IFN-γ and TGF-β. The results suggest that ligands for the TLR2-TLR6 heterodimer in S. aureus membranes, including diacylated lipoproteins, could promote T(H)2-type inflammation through TSLP production in keratinocytes, providing an overall picture of the vicious cycles between colonization by S. aureus and AD in the T(H)2-skewed sensitization process, exacerbation of the disease, or both.
Article
Bacterial infection with Staphylococcus aureus is a known trigger for worsening of atopic dermatitis (AD); the exact mechanisms by which bacterial infection worsens dermatitis are unknown. We sought to characterize the amounts of the biologically active bacterial lipoprotein lipoteichoic acid (LTA) in infected AD lesions. Eighty-nine children with clinically impetiginized lesions of AD were enrolled in this study. A lesion was graded clinically by using the Eczema Area and Severity Index (EASI), wash fluid obtained from the lesion for quantitative bacterial culture, and measurement of LTA and cytokines. The staphylococcal isolate was tested for antibiotic susceptibilities. The patients were treated with a regimen that included topical corticosteroids and systemic antibiotics, and the lesion was reanalyzed after 2 weeks. S aureus was identified in 79 of 89 children enrolled in the study. The bacterial colony-forming unit (CFU) counts correlated with the EASI lesional score (P = .04). LTA levels as high as 9.8 mug/mL were measured in the wash fluid samples, and the amounts correlated with the lesional EASI scores (P = .01) and S aureus CFU (P < .001). Approximately 30% of clinically impetiginized AD lesions contained greater than 1 mug/mL LTA, amounts that exert effects on various cell types in vitro. Moreover, injection of skin tissue ex vivo with amounts of LTA found in AD lesions resulted in epidermal cytokine gene expression. Pharmacologic levels of LTA are found in many infected atopic dermatitis lesions.
Article
The skin of patients with inflammatory skin diseases such as atopic dermatitis is frequently colonized with Staphylococcus aureus. Colonization with S aureus has been reported to exacerbate atopic dermatitis. Recent studies have demonstrated that S aureus isolated from the skin of patients with atopic dermatitis releases bacterial toxins that act as superantigens. We have previously applied the staphylococcal superantigen staphylococcal enterotoxin B (SEB) on intact human skin and found that the application led to induction of dermatitis. The purpose of the study was to determine whether superantigen-induced dermatitis is primarily due to a T cell-superantigen-mediated reaction or represents nonspecific cytokine-driven inflammation. We applied SEB, vehicle, and sodium lauryl sulfate on normal skin in healthy (n = 6) and atopic subjects (n = 6) and biopsy specimens were taken from all treated areas. The biopsy specimens from all subjects and peripheral blood from the atopic subjects were analyzed for the T-cell receptor (TCR) Vbeta repertoire with mAbs against TCR Vbeta 2, 3, 8.1, 12, 14, and 17. From all subjects, both healthy and patients with atopic dermatitis, skin biopsy specimens from SEB-treated areas demonstrated selective accumulation of T cells expressing SEB-reactive TCR Vbeta 12 and 17 (P <.05). This selective up-regulation was not found in the sodium lauryl sulfate-treated areas. Our data strongly support that superantigen-induced T-cell activation is involved in the dermatitis seen after experimental application of SEB on intact skin.
Article
Staphylococcus skin infection is characterized by the infiltration of numerous neutrophils within the epidermis; however, the precise mechanism of epidermal infiltration of neutrophils during skin infection with staphylococci is not well understood and the factors regulating the neutrophil recruitment are yet to be determined. We investigated the effects of staphylococci on cytokine production from keratinocytes, specifically to elucidate the mechanisms of neutrophil infiltration within the epidermis in cutaneous microbial infection. Cytokine production from human keratinocytes was examined after stimulation with heat-killed Staphylococcus aureus, S. epidermidis and S. intermedius. Interleukin (IL)-6 and IL-8 were detected in the culture supernatants by enzyme-linked immunosorbent assay but IL-1beta, monocyte chemotactic protein-1 and tumour necrosis factor-alpha were not. IL-6 and IL-8 mRNAs were also confirmed by reverse transcription-polymerase chain reaction in the keratinocytes stimulated with killed staphylococci for 1, 3, 6, 10 and 24 h. These results could explain the epidermal infiltration of neutrophils in cutaneous infection with staphylococci, suggesting that the analysis of cytokines might add valuable information for the pathogenesis of cutaneous infection with Staphylococcus species.
Article
Staphylococcal alpha-toxin is a cytolytic toxin secreted by many strains of Staphylococcus aureus that has proinflammatory and cytotoxic effects on human keratinocytes. alpha-toxin exerts its effects by forming a transmembrane pore that behaves like an ionophore for ions such as calcium. Because cellular membrane disruption with resultant intracellular calcium mobilization is a potent stimulus for the synthesis for the lipid mediator platelet-activating factor, the ability of alpha-toxin to induce platelet-activating factor production was assessed, and whether the epidermal platelet-activating factor receptor could augment toxin-induced signaling in epithelial cells examined. Treatment of the human keratinocyte-derived cell line HaCaT with alpha-toxin resulted in significant levels of platelet-activating factor, which were approximately 50% of the levels induced by calcium ionophore A23187. alpha-toxin also stimulated arachidonic acid release in HaCaT keratinocytes. Pretreatment of HaCaT cells with platelet-activating factor receptor antagonists, or overexpression of the platelet-activating factor metabolizing enzyme acetylhydrolase II blunted alpha-toxin-induced arachidonic acid release by approximately one-third, suggesting a role for toxin-produced platelet-activating factor in this process. Finally, retroviral-mediated expression of the platelet-activating factor receptor into the platelet-activating factor receptor-negative epithelial cell line KB resulted in an augmentation of alpha-toxin-mediated intracellular calcium mobilization and arachidonic acid release. These studies suggest that alpha-toxin-mediated signaling can be augmented via the epidermal platelet-activating factor receptor.
Article
The aim of this study was to evaluate the susceptibility of methicillin-susceptible and methicillin-resistant staphylococci (MSS, MRS) to oregano essential oil, carvacrol and thymol. The commercial aerial parts of Origanum vulgare L. were hydrodistilled and the essential oil analysed by gas- chromatography/electron impact mass spectrometry. The inhibition efficacy of this essence and its major components was assayed against 26 MSS and 21 MRS, using an agar dilution method. The methicillin resistance was thoroughly typed by Epsilometer test (E-test), polymerase chain reaction for mecA gene detection and PBP2' latex agglutination test. The results clearly demonstrated that the comparison between the susceptibility of MSS and MRS to oregano oil, carvacrol and thymol showed no significant differences (Fisher's exact test, P > 0.05). The best minimum inhibitory concentration values were reported for carvacrol (0.015-0.03%, v/v) followed by thymol (0.03-0.06%, v/v) and oregano oil (0.06-0.125%, v/v).
Article
Background: The cathelicidin family of antimicrobial peptides is an integral component of the innate immune response that exhibits activity against bacterial, fungal, and viral pathogens. Eczema herpeticum (ADEH) develops in a subset of patients with atopic dermatitis (AD) because of disseminated infection with herpes simplex virus (HSV). Objective: This study investigated the potential role of cathelicidins in host susceptibility to HSV infection. Methods: Glycoprotein D was measured by means of real-time RT-PCR as a marker of HSV replication in skin biopsy specimens and human keratinocyte cultures. Cathelicidin expression was evaluated in skin biopsy specimens from patients with AD (n = 10) without a history of HSV skin infection and from patients with ADEH (n = 10). Results: The cathelicidin peptide LL-37 (human cathelicidin) exhibited activity against HSV in an antiviral assay, with significant killing (P < .001) within the physiologic range. The importance of cathelicidins in antiviral skin host defense was confirmed by the observation of higher levels of HSV-2 replication in cathelicidin-deficient (Cnlp-/-) mouse skin (2.6 +/- 0.5 pg HSV/pg GAPDH, P < .05) compared with that seen in skin from their wild-type counterparts (0.9 +/- 0.3). Skin from patients with ADEH exhibited significantly (P < .05) lower levels of cathelicidin protein expression than skin from patients with AD. We also found a significant inverse correlation between cathelicidin expression and serum IgE levels (r2 = 0.46, P < .05) in patients with AD and patients with ADEH. Conclusion: This study demonstrates that the cathelicidin peptide LL-37 possesses antiviral activity against HSV and demonstrates the importance of variable skin expression of cathelicidins in controlling susceptibility to ADEH. Additionally, serum IgE levels might be a surrogate marker for innate immune function and serve as a biomarker for which patients with AD are susceptible to ADEH. Clinical implications: A deficiency of LL-37 might render patients with AD susceptible to ADEH. Therefore increasing production of skin LL-37 might prevent herpes infection in patients with AD.
Article
Atopic dermatitis (AD) is a chronic inflammatory skin disease with immunopathologic features that vary depending on the duration of the lesion. The lesioned skin of AD patients shows an increased number of inflammatory cells such as eosinophils, mast cells and mononuclear cells in the dermis and superficial Staphylococcus aureus colonization. The purpose of this study was to determine the effects of peptidoglycan (PEG) from S. aureus on eosinophil induction in murine skin. PEG was applied to the barrier-disrupted abdominal skin of mice every 5 days. Twenty days later, the number of eosinophils in the abdominal skin was counted. The cytokine response in the skin was investigated by RT-PCR and immunohistological analysis. The regulated-upon activation in normal T cells expressed and secreted (RANTES) production from cultured epidermal cells was measured by ELISA. The skin of mice treated with PEG showed a significantly increased number of eosinophils compared with that of mice treated with vehicle alone. In addition, application of PEG to the abdominal skin of mice increased the expression of mRNA for RANTES, but not that of mRNA for eotaxin, eotaxin-2 and monocyte chemotactic protein-3 in the skin. Immunohistologic analysis demonstrated that the levels of RANTES transcripts corresponded with those of protein synthesis in the epidermis. In vitro experiments using epidermal Langerhans cells (LCs) and keratinocytes (KCs) showed that RANTES production was induced by LCs but not by KCs stimulated with PEG. Furthermore, an intraperitoneal injection of anti-RANTES antibody neutralized the induction of eosinophils in the skin. These results suggest that PEG may have an ability to induce eosinophil infiltration in the skin through RANTES production by LCs, and would explain the role of S. aureus colonization in AD patients.