[Show abstract][Hide abstract] ABSTRACT: We report for the first time the design and synthesis of a novel cyclotide able to activate the unique receptor of angiotensin (1-7) (AT1-7), the MAS1 receptor. This was accomplished by grafting an AT1-7 peptide analog onto loop 6 of cyclotide MCoTI-I using isopeptide bonds to preserve the α-amino and C-terminal carboxylate groups of AT1-7, which are required for activity. The resulting cyclotide construct was able to adopt a cyclotide-like conformation and showed similar activity to that of AT1-7. This cyclotide also showed high stability in human serum thereby providing a promising lead compound for the design of a novel type of peptide-based in the treatment of cancer and myocardial infarction.
[Show abstract][Hide abstract] ABSTRACT: Evidence points to a role for the renin-angiotensin system in the regulation of hematopoiesis. We showed that angiotensin 1-7 (A(1-7)) accelerated recovery and engraftment of bone marrow progenitors. Multilineage bone marrow recovery results in platelet and white blood cell recovery. The effects of A(1-7) are synergistic with Neupogen® and Epogen, both in the bone marrow and in the periphery. Treatment with A(1-7) reduces the dose of Neupogen required to stimulate recovery following myelosuppression. Clinical studies show that TXA127 (clinical formulation of A(1-7)) treatment restores the hematopoietic parameters after chemotherapy, allows the maintenance of chemotherapy dose intensity, and increases progenitor mobilization in combination with Neupogen. In conclusion, A(1-7) is an effective, multilineage stimulant of bone marrow recovery.
[Show abstract][Hide abstract] ABSTRACT: To develop allopregnanolone as a therapeutic for Alzheimer's disease, we investigated multiple formulations and routes of administration in translationally relevant animal models of both sexes. Subcutaneous, topical (transdermal and intranasal), intramuscular, and intravenous allopregnanolone were bolus-administered. Pharmacokinetic analyses of intravenous allopregnanolone in rabbit and mouse indicated that peak plasma and brain levels (3-fold brain/plasma ratios) at 5min were sufficient to activate neuroregenerative responses at sub-sedative doses. Slow-release subcutaneous suspension of allopregnanolone displayed 5-fold brain/plasma ratio at Cmax at 30min. At therapeutic doses by either subcutaneous or intravenous routes, allopregnanolone mouse plasma levels ranged between 34-51ng/ml by 30min, comparable to published endogenous human level in the third trimester of pregnancy. Exposure to subcutaneous, topical, intramuscular, and intravenous allopregnanolone, at safe and tolerable doses, increased hippocampal markers of neurogenesis including BrdU and PCNA in young 3xTgAD and aged wildtype mice. Intravenous allopregnanolone transiently and robustly phosphorylated CREB within 5min and increased levels of neuronal differentiation transcription factor NeuroD within 4h. Neurogenic efficacy was achieved with allopregnanolone brain exposure of 300-500hr*ng/g. Formulations were tested to determine the no observable adverse effect level (NOAEL) and maximally tolerated doses (MTD) in male and female rats by sedation behavior time course. Sex differences were apparent, males exhibited ≥40% more sedation time compared to females. Allopregnanolone formulated in sulfobutyl-ether-beta-cyclodextrin at optimized complexation ratio maximized allopregnanolone delivery and neurogenic efficacy. To establish the NOAEL and MTD for Allo-induced sedation using a once-per-week intravenous regenerative treatment regimen: In female rats the NOAEL was 0.5mg/kg and MTD 2mg/kg. The predicted MTD in human female is 0.37mg/kg. In male rats the NOAEL and MTD were less than those determined for female. Outcomes of these PK/PD studies predict a safe and efficacious dose range for initial clinical trials of allopregnanolone for Alzheimer's disease. These findings have translational relevance to multiple neurodegenerative conditions.
[Show abstract][Hide abstract] ABSTRACT: Significance: Diabetes is a disorder that is well known to delay wound repair resulting in the formation of colonized chronic wounds. Over their lifetime, diabetic patients have a 25% incidence of foot ulcers (DFUs), which contribute to increased risk of morbidity, including osteomyelitis and amputations, and increased burden to the healthcare system. Recent Advances: The only active product approved for the treatment of diabetic ulcers, Regranex®, is not widely used due to minimal proven efficacy and recent warnings added to the Instructions for Use. A novel topical agent that accelerates healing and increases the proportion of fully healed DFUs, DSC127 [aclerastide; active ingredient, NorLeu3-angiotensin (1-7) (NorLeu3-A(1-7))], is recruiting patients in Phase III clinical trials (NCT01830348 and NCT01849965). NorLeu3-A(1-7) is an analog of the naturally occurring peptide, angiotensin 1-7. The mechanisms of action include induction of progenitor proliferation, accelerated vascularization, collagen deposition, and re-epithelialization. Critical Issues: Current modalities for the treatment of DFUs include strict offloading, bandaging, debridement and, on a limited basis, application of Regranex. Novel potent therapies are needed to combat this significant burden to the diabetic patient and the healthcare system. Future Direction: Preclinical and clinical research shows that DSC127 is highly effective in the closure of diabetic wounds and is superior to Regranex in animal studies. Clinical development of DSC127 as a topical agent for the healing of DFU is underway. Further investigation into the mechanisms by which this product accelerates healing is warranted.
[Show abstract][Hide abstract] ABSTRACT: In the event of a nuclear disaster, the
individuals proximal to the source of radiation will be exposed to combined radiation injury. As irradiation delays cutaneous repair, the purpose of this study was to elucidate the effect of combined radiation and burn injury (CRBI) on apoptosis and inflammation at the site of skin injury. Male C57Bl/6 mice were exposed to no injury, thermal injury only, radiation only (1 and 6 Gy) and CRBI (1 and 6 Gy) and euthanized at various times after for skin collection. TUNEL staining revealed that the CRBI 6 Gy group had a delayed and increased apoptotic response. This correlated with decreased recovery of live cells as compared to the other injuries. Similar response was observed when cleaved-caspase-3 immunohistochemical staining was compared between CRBI 6 Gy and thermal injury. TNFR1, caspase 8, Bax and IL-6 mRNA expression revealed that the higher CRBI group had delayed increase in mRNA expression as compared to thermal injury alone. RIPK1 mRNA expression and necrotic cell counts were delayed in the CRBI 6 Gy group to day 5. TNF-α and NFκB expression peaked in the CRBI 6 Gy group at day 1 and was much higher than the other injuries. Also, inflammatory cell counts in the CRBI 6 Gy group were lower at early time points as compared to thermal injury by itself. These data suggest that CRBI delays and exacerbates apoptosis and inflammation in skin as well as increases necrosis thus resulting in delayed wound healing.
[Show abstract][Hide abstract] ABSTRACT: Introduction:
Thrombocytopenia is an abnormally low number of platelets in the blood resulting from either too few platelets being produced or existing platelets being destroyed. Severe thrombocytopenia leads to excessive bleeding and can be the result of numerous medical conditions or a side effect of medications or treatments. Although platelet transfusions are typically administered to correct thrombocytopenia, transfusions represent a temporary and unsustainable solution. As there is a limited supply of platelet units available for transfusion, along with the significant financial cost and risk of infection, investigation to uncover mechanisms that boost platelet production may have important clinical and therapeutic implications. Treatment with angiotensin 1 - 7 (A(1 - 7)) has been shown in a preclinical and clinical evaluations to have a positive effect on platelet recovery.
The authors provide an overview of the current treatment options available for platelet recovery and highlight the need for alternatives. Following on, the authors discuss the use of A(1 - 7) as a potential therapeutic option for platelet recovery, including its safety and efficacy.
Current evidence provides a good basis for continued research and evaluation of the benefits of A(1 - 7) treatment in stimulating platelet recovery following myelosuppression. A(1 - 7) therapy has the potential to make a significant contribution to healthcare by providing standalone and additive treatments to address unmet medical needs and life-threatening diseases by utilizing the regenerative arm of the renin-angiotensin system.
No preview · Article · Feb 2014 · Expert Opinion on Investigational Drugs
[Show abstract][Hide abstract] ABSTRACT: The renin-angiotensin system (RAS) has long been a known endocrine system that is involved in regulation of blood pressure and fluid balance. Over the last two decades, evidence has accrued that shows that there are local RAS that can affect cellular activity, tissue injury, and tissue regeneration. There are locally active ligand peptides, mediators, receptors, and signaling pathways of the RAS in the bone marrow (BM). This system is fundamentally involved and controls the essential steps of primitive and definitive blood-cell production. Hematopoiesis, erythropoiesis, myelopoiesis, thrombopoiesis, formation of monocytic and lymphocytic lineages, as well as stromal elements are regulated by the local BM RAS. The expression of a local BM RAS has been shown in very early, primitive embryonic hematopoiesis. Angiotensin-converting enzyme (ACE-1, CD143) is expressed on the surface of hemangioblasts and isolation of the CD143 positive cells allows for recovery of all hemangioblast activity, the first endothelial and hematopoietic cells, forming the marrow cavity in the embryo. CD143 expression also marks long-term blood-forming CD34+ BM cells. Expression of receptors of the RAS is modified in the BM with cellular maturation and by injury. Ligation of the receptors of the RAS has been shown to modify the status of the BM resulting in accelerated hematopoiesis after injury. The aim of the present review is to outline the known functions of the local BM RAS within the context of primitive and definitive hematopoiesis as well as modification of BM recovery by administration of exogenous ligands of the RAS. Targeting the actions of local RAS molecules could represent a valuable therapeutic option for the management of BM recovery after injury as well as neoplastic disorders.
Preview · Article · Oct 2013 · Frontiers in Endocrinology
[Show abstract][Hide abstract] ABSTRACT: Angiotensin (1-7) [A(1-7)] is a bioactive peptide of the renin angiotensin system that stimulates the number of bone marrow progenitors and hematopoietic recovery after myelosuppression. We evaluated the combination of A(1-7) with colony-stimulating factors, Neupogen and Epogen, on bone marrow progenitors and the recovery of circulating formed elements following chemotherapy.
Mice were injected with gemcitabine followed 2 days later with A(1-7). Circulating blood cells and bone marrow progenitors were measured over time.
Combination of A(1-7) with Neupogen (the latter given only 3 days starting at the white blood cell nadir) decreased the amount of Neupogen needed for optimal recovery by 10-fold. The progenitors measured include CFU-GEMM, CFU-GM, CFU-Meg and BFU-E. A(1-7) increased recovery of all progenitors when given alone or in combination with Neupogen above that with Neupogen alone. Combination of A(1-7) with Epogen slightly increased (not significantly) red blood cell concentrations above those achieved by Epogen alone. However, in this model, A(1-7) or A(1-7) in combination with Epogen increased all erythroid progenitors with the largest effect on early erythroid progenitors (immature BFU-E).
Neupogen and Epogen acted synergistically with A(1-7) to increase the concentration of myeloid, megakaryocytic and erythroid progenitor cells in the bone marrow following chemotherapy suggesting that A(1-7)'s multilineage effect on early progenitors in the marrow facilitates proliferation in response to lineage-specific growth factors.
No preview · Article · Oct 2013 · Cancer Chemotherapy and Pharmacology
[Show abstract][Hide abstract] ABSTRACT: Sjögren’s syndrome (SjS) is a chronic autoimmune disease characterized initially by lymphocytic infiltration and destruction of exocrine glands, followed by systemic organ damage and B-cell lymphoma. Conventional treatment is based on management of symptoms and there is a shortage of therapies that address the underlying causes of inflammation at source exocrine tissue. The aim of this study was to test a novel protein polymer-based platform consisting of diblock copolymers composed from Elastin-like Polypeptides (ELPs) fused with FKBP12, to deliver a potent immunosuppressant with dose-limiting toxicity, rapamycin (Rapa) also known as Sirolimus, and evaluate its effects on the inflamed lacrimal gland (LG) of non-obese diabetic mouse (NOD), a classic mouse model of SjS. Both soluble and diblock copolymer ELPs were fused to FKBP12 and characterized with respect to purity, hydrodynamic radii, drug entrapment and release. Both formulations showed successful association with Rapa; however, the nanoparticle formulation, FSI, released drug with nearly a 5 fold longer terminal half-life of 62.5 h. The strong interaction of FSI nanoparticles with Rapa was confirmed in vivo by a shift in the monoexponential pharmacokinetic profile for free drug to a biexponential profile for the nanoparticle formulation. When acutely administered by injection into NOD mice via the tail vein, this FSI formulation significantly suppressed lymphocytic infiltration in the LG relative to the control group while reducing toxicity. There was also a significant effect on inflammatory and mammalian target of Rapamycin (mTOR) pathway genes in the LG and surprisingly, our nanoparticle formulation was significantly better at decreasing a proposed tear biomarker of SjS, cathepsin S (CATS) compared to free drug. These findings suggest that FSI is a promising tool for delivering Rapa for treatment of SjS in a murine model and may be further explored to meet the unmet medical challenge of SjS.
[Show abstract][Hide abstract] ABSTRACT: Purpose of review:
The recent advances in our understanding of Alzheimer's disease pathophysiology and the renin angiotensin system pathways suggest that angiotensin receptor blockers (ARBs) are ideal drugs to explore for Alzheimer's disease therapy.
New evidence suggests that the brain renin angiotensin system has two opposing pathways: a damaging pathway and a neuro-protective pathway. Both pathways are involved in the amyloid hypothesis (Aβ cascades) and vascular mechanisms of Alzheimer's disease. Studies in animal models suggest that ARBs have cognitive protective effects that are related to their ability to decrease production and oligomerization and increase degradation of Aβ and their vascular effects (improve blood-brain barrier, restore endothelial function, decrease inflammation, and increase cerebral blood flow). Human observational studies have further suggested that ARB use is associated with decreased risk of Alzheimer's disease and protection against future cognitive decline. Our work has suggested that ARB use is associated with decreased amyloid deposition in the brain in Alzheimer's disease and can provide cognitive protection in those with mild cognitive impairment, a prodromal state for Alzheimer's disease, and dementia.
To date, no robust clinical trial of ARBs in Alzheimer's disease has been performed. All things being equal, it is reasonable to consider ARBs in those with cognitive risks.
No preview · Article · May 2013 · Current opinion in cardiology
[Show abstract][Hide abstract] ABSTRACT: Purpose:
This randomized, double-blind, placebo-controlled Phase 2 study evaluated safety and efficacy of A(1-7) for reduction in Grade 3-4 thrombocytopenia in patients receiving myelosuppressive chemotherapy. Pharmacodynamic activity of A(1-7) in platelet production and retention of scheduled dose intensity were also determined.
Thirty-four patients with ovarian, Fallopian tube, or peritoneal carcinoma receiving gemcitabine and carboplatin or cisplatin were evaluated. Patients were randomized to receive study drug subcutaneously at 100 mcg/kg (n = 11), 300 mcg/kg (n = 13), or placebo (n = 10) following chemotherapy for up to six cycles. Hematologic variables were obtained throughout each treatment cycle.
There were no drug-related safety issues. There were no instances of Grade 4 thrombocytopenia in patients who received 100 mcg/kg treatment compared to 6 % of chemotherapy cycles for patients receiving placebo (p = 0.07). The maximal percentage increase in platelet concentration from baseline was higher for patients who received 100 mcg/kg A(1-7) compared to placebo (p = 0.02). This increase was accompanied by a reduction in the nadir absolute neutrophil count (p = 0.04). Relative dose intensity for the combination chemotherapy was higher for patients who received 100 mcg/kg A(1-7) compared to placebo (p = 0.04). There were no differences in outcomes for patients receiving 300 mcg/kg dose compared to placebo.
A 100 mcg/kg dose of A(1-7) was shown to produce pharmacodynamic effects on peripheral blood platelet counts, preserve planned dose intensity, and reduce Grade 3-4 thrombocytopenia following gemcitabine and platinum chemotherapy. These findings are consistent with A(1-7)-induced stimulation of thrombogenesis in the bone marrow following marrow-toxic chemotherapy.
No preview · Article · Jan 2013 · Cancer Chemotherapy and Pharmacology
[Show abstract][Hide abstract] ABSTRACT: The renin-angiotensin system (RAS) plays an important role in wound repair; however, little is known pertaining to RAS expression in response to thermal injury and the combination of radiation plus burn injury (CRBI). The purpose of this study was to test the hypothesis that thermal injury modifies expression of RAS components and CRBI delayed this up-regulation of RAS. Skin from uninjured mice was compared with mice receiving local thermal injury or CRBI (injury site). Skin was analyzed for gene and protein expression of RAS components. There was an initial increase in the expression of various components of RAS following thermal injury. However, in the higher CRBI group there is an initial decrease in AT(1b) (vasoconstriction, pro-proliferative), AT(2) (vasodilation, differentiation), and Mas (vasodilation, anti-inflammatory) gene expression. This corresponded with a delay and decrease in AT(1) , AT(2) , and MAS protein expression in fibroblasts and keratinocytes. The reduction in RAS receptor positive fibroblasts and keratinocytes correlated with a reduction in collagen deposition and keratinocyte infiltration into the wounded area resulting in a delay of reepithelialization following CRBI. These data support the hypothesis that delayed wound healing observed in subjects following radiation exposure may be in part due to decreased expression of RAS.
No preview · Article · Dec 2012 · Wound Repair and Regeneration
[Show abstract][Hide abstract] ABSTRACT: The Immunotoxicology Specialty Section of the Society of Toxicology (SOT) celebrated the 50(th) Anniversary of the SOT by constructing a poster to highlight the milestones of Immunotoxicology during that half-century period. This poster was assembled by an ad hoc committee and intertwines in words, citations, graphics, and photographs our attempts to capture a timeline reference of the development and progressive movement of immunotoxicology across the globe. This poster was displayed during the 50(th) Annual SOT Meeting in Washington DC in March, 2011. The poster can be accessed by any Reader at the SOT Website via the link http://www.toxicology.org/AI/MEET/AM2011/posters_rcsigss.asp#imss. We dedicate this poster to all of the founders and the scientists that followed them who have made the discipline of Immunotoxicology what it is today.
No preview · Article · Oct 2012 · Journal of Immunotoxicology
[Show abstract][Hide abstract] ABSTRACT: Abstract Objective: We tested the hypothesis that women with GDM and their fetuses would demonstrate alterations in markers of eNOS uncoupling, oxidative stress, and endothelial dysfunction and these changes would correlate with the levels of hyperglycemia through a pilot observational case-control study of women with GDM and their fetuses. Methods: Levels of sICAM-1, sVCAM-1, CRP, NO, eNOS, p22-phox, and SOD gene expression, and EPC counts in both maternal and cord blood were measured at the time of delivery in women with and without GDM. Results: We demonstrated the presence of decreased maternal circulating EPC counts, increased soluble adhesion molecules in maternal blood, decreased SOD expression in both maternal and cord blood and increased eNOS expression in both maternal and cord blood in women with GDM. Conclusions: These data suggest that the molecular mechanisms behind oxidative stress in women with GDM and their fetuses appear similar to those hypothesized for non-pregnant adults with type 2 DM.
No preview · Article · Oct 2012 · The journal of maternal-fetal & neonatal medicine: the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians