1.
AMP-18 facilitates assembly and stabilization of tight junctions to protect the colonic mucosal barrier.
Source
Department of Medicine, University of Chicago, Chicago, Illinois.
Abstract
BACKGROUND:
Inflammatory bowel disease (IBD) is characterized by an injured epithelium. Development of agents that could enhance mucosal healing is a major goal in IBD therapeutics. The 18-kDa antrum mucosal protein (AMP-18) and a 21-mer peptide derived from AMP-18 stimulate accumulation of tight junction (TJ) proteins in cultured epithelial cells and mouse colonic mucosa to protect the mucosal barrier, suggesting it might be a useful agent to treat IBD.
METHODS:
We searched for molecular mechanisms by which AMP peptide or recombinant AMP-18 act on TJs in intact cell monolayers, or those disrupted by low-calcium medium. Roles of the p38 mitogen-activated protein kinase (MAPK) / heat shock protein (hsp)25 pathway and PKCζ were investigated by immunoblotting and confocal microscopy.
RESULTS:
AMP peptide activated p38 MAPK, which subsequently phosphorylated hsp25. Accumulated phospho-hsp25 was associated with perijunctional actin. AMP-18 also induced rapid phosphorylation of PKCζ and its colocalization with perijunctional actin in Caco2/bbe cells, which was accompanied by translocation and formation of complexes of "polarity proteins" in the TJ-containing detergent-insoluble fraction. Treatment with AMP-18 also stimulated accumulation of ZO-1, ZO-2, and JAM-A in nascent TJs known to associate with the multimeric p-PKCζ/Par6/ Cdc42/ECT2·GTP/Par3 polarity protein complex.
CONCLUSIONS:
AMP-18 facilitates translocation and assembly of multiple proteins into TJs and their association with and subsequent stabilization of the actin filament network. We speculate that improved barrier function induced by AMP-18 is mediated by enhanced TJ assembly. Thus, AMP-18 may provide a promising lead to develop agents effective in healing injured colonic epithelium in IBD. (Inflamm Bowel Dis 2012;).
Copyright © 2012 Crohn's & Colitis Foundation of America, Inc.
Intracellular Detection and Evolution of Site-Specific Proteases Using a Genetic Selection System.
Source
Department of Chemistry, Purdue University, 560 Oval Dr., West Lafayette, IN, 47907, USA, kverhoev@umich.edu.
Abstract
Development of endoproteases, programmed to promote degradation of peptides or proteins responsible for pathogenic states, represents an attractive therapeutic strategy, since such biocatalytic agents could be directed against a potentially unlimited repertoire of extracellular proteinaceous targets. Difficulties associated with engineering enzymes with tailor-made substrate specificities have, however, hindered the discovery of proteases possessing both the efficiency and selectivity to act as therapeutics. Here, we disclose a genetic system, designed to report on site-specific proteolysis through the survival of a bacterial host, and the implementation of this method in the directed evolution of proteases with a non-native substrate preference. The high sensitivity potential of this system was established by monitoring the activity of the Tobacco Etch Virus protease (TEV-Pr) against co-expressed substrates of various recognition level and corroborated by both intracellular and cell-free assays. The genetic selection system was then used in an iterative mode with a library of TEV-Pr mutants to direct the emergence of proteases favoring a nominally poor substrate of the stringently selective protease. The retrieval of mutant enzymes displaying enhanced proteolytic properties against the non-native sequence combined with reduced recognition of the cognate hexapeptide substrate demonstrates the potential of this system for evolving proteases with improved or completely unprecedented properties.
Neutralization of IL-17 ameliorates uveitis but damages photoreceptors in a murine model of spondyloarthritis.
Abstract
ABSTRACT:
INTRODUCTION:
Uveitis, or intraocular inflammatory disease, is a frequent extra-articular manifestation of several forms of arthritis. Despite the frequent co-occurrence of uveitis and arthritis, little is understood of the eye's predisposition to this disease. We recently described a previously unreported uveitis in a murine model of spondyloarthropathy triggered by autoimmunity to aggrecan, a prominent proteoglycan (PG) macromolecule in cartilage. In contrast to the joint and spine wherein interferon-gamma (IFNgamma) deficiency reduced disease, IFNgamma deficiency worsened uveitis. Given the regulatory role of IFNgamma on the Th17 response and the current focus of anti-interleukin-17 therapeutics in patients with uveitis and spondyloarthritis, we sought to determine the extent to which interleukin (IL)-17 mediates uveitis in the absence of IFNgamma.
METHODS:
Antigen specific T cell cytokine production was measured in splenocyte cultures using multiplex-ELISA. Transgenic (Tg) mice expressing the T cell receptor (TCR) recognizing the dominant arthritogenic epitope in the G1 domain of PG (TCR-Tg), also lacking IFNgamma, were immunized with PG. Mice were then systemically administered an anti-IL-17 neutralizing antibody. The onset and severity of peripheral arthritis was evaluated by clinical scoring criteria and histology. Uveitis was assessed using intravital videomicroscopy, which visualizes leukocyte trafficking within the vasculature and tissue of the iris, and by histology.
RESULTS:
TCR-Tg splenocytes stimulated in vitro with recombinant G1 peptide demonstrated exacerbated production of cytokines such as macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, IL-1beta, and most notably IL-17A as a consequence of IFNgamma deficiency. In vivo, IL-17 inhibition prevented the component of PG-induced arthritis that occurs independently of IFNgamma. 4 Blockade of IL-17 ameliorated the ongoing leukocyte trafficking responses within the iris vasculature and tissue, which coincided with reduced infiltration of leukocytes within the anterior and posterior eye segments. However, the anti-IL-17 treatment resulted in unanticipated photoreceptor toxicity.
CONCLUSIONS:
These data support a protective, regulatory role for IFNgamma in suppression of IL-17-mediated intraocular disease and to a lesser extent, joint disease. The unanticipated photoreceptor toxicity raises some caution regarding the use of anti-IL-17 therapeutics until the mechanism of this potential effect is determined.
CHEMICAL OPTIMIZATION OF NEW LIGANDS OF THE LOW-DENSITY LIPOPROTEIN RECEPTOR AS POTENTIAL VECTORS FOR CENTRAL NERVOUS SYSTEM TARGETING.
Abstract
Drug delivery to the central nervous system is hindered by the presence of physiological barriers such as the blood-brain barrier. To accomplish the task of nutrient transport, the brain endothelium is endowed with various transport systems, including receptor-mediated transcytosis (RMT). This system can be used to shuttle therapeutics into the CNS in a non-invasive manner. Therefore, the low-density lipoprotein receptor (LDLR) is a relevant target for delivering drugs. From an initial phage display biopanning, a series of peptide ligands for the LDLR was optimized leading to size reduction and improved receptor binding affinity with the identification of peptide 22 and its analogues. Further real-time biphoton microscopy experiments on living mice demonstrated the ability of peptide 22 to efficiently and quickly cross the BBB. This validation of peptide 22 led us to explore its binding on the extracellular LDLR domain from an NMR-oriented structural study and docking experiments.
Spatiotemporal control of cell fate and cardiac differentiation.
Abstract
Congestive heart failure is a leading cause of morbidity and mortality in the United States and worldwide [1]. Although not the only cause of congestive heart failure, loss of myocardium due to obstructive coronary artery disease is a major contributor to this condition [2,3]. The loss of myocardium is mainly regional and, therefore, localized therapy holds the most promise. In recent years, many clinical studies have been initiated to deliver localized therapy in the form of various cell types for reconstitution of the myocardium [4-6]. However, there is much debate on the optimal cell type, whether or not stem cells can differentiate into functional myocardium and the long-term effects of these non-myocytes. In addition to exogenous cell delivery, paracrine effects arising from delivery of angiogenic factors and other biochemical agents suggest that the myocardium retains the ability to remodel and heal [7,8]. Understandably, there has been tremendous focus on both growth factor- and gene therapy-based therapeutics. While a source of great promise, direct growth factor delivery to the myocardium will most likely be inefficient as several studies have noted that many of these small proteins are carried away in the highly vascularized cardiac tissue [9,10]. Gene therapy, while providing an excellent analytical tool, has not met with enthusiasm clinically, mostly due to the inability to quantify delivery and nonspecific targeting in vivo. This body of work supports two crucial conclusions: (1) appropriate biological cues that act locally on the myocardium can improve functional outcomes, and (2) spatiotemporal control over the delivery and presentation of these cues remains challenging and inefficient. The current body of work on cardiac drug delivery and stem cell therapy support two crucial conclusions: (1) appropriate biological cues that act locally on the myocardium can improve functional outcomes, and (2) spatiotemporal control over the delivery and presentation of these cues remains challenging and inefficient. Using specialized biomaterials, we are able to address this. Our laboratory has used functional nanoparticles to deliver regenerative cues with both spatial and temporal control. By adding biomimetic signals to the surface of the nanoparticles, we are able to enhance nonphagocytic cell uptake, achieve cell-specific targeting, and deliver molecules in a time-controlled manner. Furthermore, by combining our nanoparticles with self-assembling peptide nanofibers, we can achieve some of these in 3D while retaining implanted cells. Following infarction, and during cell differentiation and survival, there are unique sequences of events that contribute to the pathophysiology of the processes. By enhanced understanding of these signals, and the spatiotemporal control needed to deliver them, it will help design better therapeutics for cardiac regeneration. Using high-throughput screening, we have identified several carbohydrates that bind with high affinity to both cardiomyocytes and cardiac progenitor cells. For example, n-acetylglucasmine (GlcNAc) and related sugars bound with high affinity to both of these important cell types. Modification of the sugars with phospholipds allowed incorporation of into hydrophobic nanoparticles with high fidelity. When delivered to cardiomyocytes or cardiac progenitor cells, these biologically-modified nanoparticles enhanced uptake by several fold. In addition to using sugars, we also used metal affinity chromatography chemistry to link Nickel-NTA to the outside of nanoparticles. This not only allowed for conjugation of Histidine-tagged proteins to the outside for temporal delivery, but also allowed for conjugation of cell-specific targeting agents as well. Indeed, when His-VE-Cadherin was used as a model targeting agent, binding and uptake by endothelial cells increased significantly. For cell therapy, incorporation of proper signals to the micoenvironment is critical. One such signal that greatly impacts differentiation is the Notch1 pathway. We were able to immobilize Jagged1, the ligand of Notch1, on to self-assembling peptide nanofibers. Inclusion of this bioactive signal significantly enhanced cardiogenic differentiation. Morever, by including time release nanoparticles, we were able to improve differentiation and survival significantly more, underscoring the need to spatiotemporal control of drug delivery for enhancing cell therapy.
The role of the Src family kinase Lyn in the immunomodulatory activities of cathelicidin peptide LL-37 on monocytic cells.
Source
Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada.
Abstract
Cathelicidin LL-37 is a multifunctional, immunomodulatory and antimicrobial host-defense peptide of the human immune system. Here, we identified the role of SFKs in mediating the chemokine induction activity of LL-37 in monocytic cells. LL-37 induced SFK phosphorylation; and chemical inhibitors of SFKs suppressed chemokine production in response to LL-37 stimulation. SFKs were required for the downstream activation of AKT, but Ca(2+)-flux and MAPK induction were SFK-independent. Through systematic siRNA knockdown of SFK members, a requirement for Lyn in mediating LL-37 activity was identified. The involvement of Lyn in cathelicidin activities was further confirmed using Lyn-knockout mouse BMDMs. The role of SFKs and Lyn was also demonstrated in the activities of the synthetic cationic IDR peptides, developed as novel, immunomodulatory therapeutics. These findings elucidate the common molecular mechanisms mediating the chemokine induction activity of natural and synthetic cationic peptides in monocytic cells and identify SFKs as a potential target for modulating peptide responses.
Clinical Relevance of Anti-exenatide Antibodies: Safety, Efficacy, and Cross-reactivity with Long-term Treatment.
Source
Elcelyx Therapeutics, Inc., San Diego, CA Eli Lilly and Company, Indianapolis, IN, USA Diabetes Center, VU University Medical Center, Amsterdam, the Netherlands American Diabetes Association, Alexandria, VA, USA Amylin Pharmaceuticals, Inc., San Diego, CA.
Abstract
Aims Antibody formation to therapeutic peptides is common. This analysis characterizes the time-course and cross-reactivity of anti-exenatide antibodies and potential effects on efficacy and safety. Materials and Methods Data from ITT patients in 12 controlled (n=2225, 12-52wks) and 5 uncontrolled (n=1538, up to 3yrs) exenatide BID trials and 4 controlled (n=653, 24-30wks) exenatide once weekly (QW) trials with 1 uncontrolled period (n=128, 52wks) were analyzed. Results Mean titers peaked early (6-22wks), and subsequently declined. At 30wks, 36.7% of exenatide BID patients were antibody-positive; 31.7% exhibited low titers (≤125) and 5.0% had higher titers (≥625). Antibody incidence declined to 16.9% (1.4% higher titer) at 3yrs. Similarly, 56.8% of exenatide QW patients were antibody-positive (45.0% low/11.8% higher titer) at 24-30wks, declining to 45.4% positive (9.2% higher titer) at 52wks. Treatment-emergent anti-exenatide antibodies from a subset of patients tested did not cross-react with human GLP-1 or glucagon. Other than injection-site reactions, adverse event rates in antibody-positive and antibody-negative patients were similar. Efficacy was robust in both antibody-negative and antibody-positive patients (mean HbA(1c) : -1.0% and -0.9%, respectively, exenatide BID; -1.6% and -1.3% exenatide QW). No correlation between change in HbA(1c) and titer was observed for exenatide BID, although mean reductions were attenuated in the small subset of patients (5%) with higher titers. A significant correlation was observed for exenatide QW, with no difference between antibody negative and low-titer patients but an attenuated mean reduction in the subset of patients (12%) with higher titers. Conclusions Low titer anti-exenatide antibodies were common with exenatide treatment (32% exenatide BID, 45% exenatide QW patients), but had no apparent effect on efficacy. Higher titer antibodies were less common (5% exenatide BID, 12% exenatide QW) and within that titer group, increasing antibody titer was associated with reduced average efficacy that was statistically significant for exenatide QW. Other than injection-site reactions, anti-exenatide antibodies did not impact the safety of exenatide.
Copyright © 2012 John Wiley & Sons A/S.
Therapeutic potential of host defense peptides in antibiotic-resistant infections.
Source
Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, British Columbia, Canada. bob@cmdr.ubc.ca.
Abstract
The emergence of infections caused by multi-drug resistant (MDR) pathogens pose a major burden to modern healthcare. Exacerbating this issue is the substantial decline in development of new classes of antibiotics by pharmaceutical companies. This has led to renewed interest in the therapeutic potential of natural anti-infective agents such as host defense peptides (HDPs). The broad antimicrobial and immunomodulatory activities of HDPs and their synthetic derivatives, coupled with the fact that they do not readily induce microbial resistance, makes them extremely valuable leads in the development of new treatment strategies for MDR infections. This review examines our knowledge of the mechanisms behind multi-drug resistance as well as the properties of HDPs and their therapeutic potential, especially in the case of MDR infections. Challenges to their development as new therapeutics are also discussed.
- PMID:
- 22236127
- [PubMed - as supplied by publisher]
Ghrelin and the brain-gut axis as a pharmacological target for appetite control.
Source
Ghrelin Research Group, Institute of Health and Biomedical Innovation, Queensland. i.seim@qut.edu.au.
Abstract
Appetite regulation is highly complex and involves a large number of orexigenic and anorexigenic peptide hormones. These are small, processed, secreted peptides derived from larger prepropeptide precursors. These peptides are important targets for the development of therapeutics for obesity, a global health epidemic. As a case study, we consider the ghrelin axis. The ghrelin axis is likely to be a particularly useful drug target, as it also plays a role in energy homeostasis, adipogenesis, insulin regulation and reward associated with food intake. Ghrelin is the only known circulating gut orexigenic peptide hormone. As it appears to play a role in diet-induced obesity, blocking the action of ghrelin is likely to be effective for treating and preventing obesity. The ghrelin peptide has been targeted using a number of approaches, with ghrelin mirror-image oligonucleotides (Spiegelmers) and immunotherapy showing some promise. The ghrelin receptor, the growth hormone secretagogue receptor, may also provide a useful target and a number of antagonists and inverse agonists have been developed. A particularly promising new target is the enzyme which octanoylates ghrelin, ghrelin O-acyltransferase (GOAT), and drugs that inhibit GOAT are likely to circumvent pharmacological issues associated with approaches that directly target ghrelin or its receptor.
- PMID:
- 22236122
- [PubMed - as supplied by publisher]
Mining PeptideAtlas for Biomarkers and Therapeutics in Human Disease.
Source
Institute for Systems Biology, 401 Terry Ave. North, Seattle, WA 98109. jboyle@systemsbiology.org.
Abstract
Mass spectrometry information has long offered the potential of discovering biomarkers that would enable clinicians to diagnose disease, and treat it with targeted therapies. PeptideAtlas currently provides access to large-scale spectra data and identification information. This data, and the generation of targeted peptide information, represents the first step in the process of locating disease biomarkers. Reaching the goal of clinical proteomics requires that this data be integrated with additional information from disease literature and genomic studies. Here we describe PeptideAtlas and associated methods for mining the data, as well as the software tools necessary to support large-scale integration and mining.
- PMID:
- 22236120
- [PubMed - as supplied by publisher]
Emerging themes and therapeutic prospects for anti-infective peptides.
Source
Divisions of Infectious Diseases and Molecular Medicine, Los Angeles County Harbor-UCLA Medical Center, Torrance, California 90509; email: MRYeaman@ucla.edu.
Abstract
Pathogens resistant to most conventional anti-infectives are a harbinger of the need to discover and develop novel anti-infective agents and strategies. Endogenous host defense peptides (HDPs) have retained evolution-tested efficacy against pathogens that have become refractory to traditional antibiotics. Evidence indicates that HDPs target membrane integrity, bioenergetics, and other essential features of microbes that may be less mutable than conventional antibiotic targets. For these reasons, HDPs have received increasing attention as templates for development of potential anti-infective therapeutics. Unfortunately, advances toward this goal have proven disappointing, in part owing to limited understanding of relevant structure-activity and selective toxicity relationships in vivo, a limited number of reports and overall understanding of HDP pharmacology, and the difficulty of cost-effective production of such peptides on a commodity scale. However, recent molecular insights and technology innovations have led to novel HDP-based and mimetic anti-infective peptide candidates designed to overcome these limitations. Although initial setbacks have presented challenges to therapeutic development, emerging themes continue to highlight the potential of HDP-based anti-infectives as a platform for next-generation therapeutics that will help address the growing threat of multidrug-resistant infections.
Angiotensin II Reduces Food Intake by Altering Orexigenic Neuropeptide Expression in the Mouse Hypothalamus.
Source
Heart and Vascular Institute (T.Y., L.S.-P., S.S., P.D.), Tulane University School of Medicine, New Orleans, Louisiana 70112; and Departments of Pharmacology and Experimental Therapeutics (R.D.W., D.R.K.) and Anesthesiology and the Cardiovascular Center of Excellence (D.R.K.), Louisiana State University Health Sciences Center, New Orleans, LA 70112.
Abstract
Angiotensin II (Ang II), which is elevated in many chronic disease states such as end-stage renal disease and congestive heart failure, induces cachexia and skeletal muscle wasting by increasing muscle protein breakdown and reducing food intake. Neurohormonal mechanisms that mediate Ang II-induced appetite suppression are unknown. Consequently, we examined the effect of Ang II on expression of genes regulating appetite. Systemic Ang II (1 μg/kg · min) infusion in FVB mice rapidly reduced hypothalamic expression of neuropeptide Y (Npy) and orexin and decreased food intake at 6 h compared with sham-infused controls but did not change peripheral leptin, ghrelin, adiponectin, glucagon-like peptide, peptide YY, or cholecystokinin levels. These effects were completely blocked by the Ang II type I receptor antagonist candesartan or deletion of Ang II type 1a receptor. Ang II markedly reduced phosphorylation of AMP-activated protein kinase (AMPK), an enzyme that is known to regulate Npy expression. Intracerebroventricular Ang II infusion (50 ng/kg · min) caused a reduction of food intake, and Ang II dose dependently reduced Npy and orexin expression in the hypothalamus cultured ex vivo. The reduction of Npy and orexin in hypothalamic cultures was completely prevented by candesartan or the AMPK activator 5-aminoimidazole-4-carboxamide ribonucleoside. Thus, Ang II type 1a receptor-dependent Ang II signaling reduces food intake by suppressing the hypothalamic expression of Npy and orexin, likely via AMPK dephosphorylation. These findings have major implications for understanding mechanisms of cachexia in chronic disease states such as congestive heart failure and end-stage renal disease, in which the renin-angiotensin system is activated.
GLP-1 Based Therapies: Differential Effects on Fasting and Postprandial Glucose.
Source
Elcelyx Therapeutics, Inc., San Diego, CA, USA Amylin Pharmaceuticals, Inc., San Diego, CA, USA Diabetes Center, VU University Medical Center, Amsterdam, the Netherlands.
Abstract
Glucagon-like peptide-1 (GLP-1), a gut derived hormone secreted in response to nutrients, has several glucose and weight regulating actions including enhancement of glucose stimulated insulin secretion, suppression of glucagon secretion, slowing of gastric emptying, and reduction in food intake. Due to these multiple effects, the GLP-1 receptor system has become an attractive target for type 2 diabetes therapies. However, GLP-1 has significant limitations as a therapeutic due to its rapid degradation (plasma half-life of 1-2 minutes) by dipeptidyl peptidase-4 (DPP-4). Two main classes of GLP-1 mediated therapies are now in use: DPP-4 inhibitors that reduce the degradation of GLP-1 and DPP-4 resistant GLP-1 receptor (GLP-1R) agonists. The GLP-1R agonists can be further divided into short-acting and long-acting formulations which have differential effects on their mechanisms of action, ultimately resulting in differential effects on their fasting and postprandial glucose lowering potential. This review summarizes the similarities and differences between DPP-4 inhibitors, short-acting GLP-1R agonists and long-acting GLP-1R agonists. We propose that these different GLP-1 mediated therapies are all necessary tools for the treatment of type 2 diabetes and that the choice of which one to use should depend on the specific needs of the patient. This is analogous to the current use of modern insulins, as short, intermediate, and long-acting versions are all used to optimize the 24-hour plasma glucose profile as needed. Given that GLP-1 mediated therapies have advantages over insulins in terms of hypoglycemia risk and weight gain, optimized use of these compounds could represent a significant paradigm shift for the treatment of type 2 diabetes.
© 2012 Blackwell Publishing Ltd.
Characterization of Insulin Degrading Enzyme and Other Amyloid-β Degrading Proteases in Human Serum: A Role in Alzheimer's Disease?
Source
Departments of Pharmacology and Experimental Therapeutics, Boston University Medical Campus, Boston, MA, USA Departments of Anesthesiology, The Second People's Hospital of Shenzhen, PR China.
Abstract
Sporadic Alzheimer's disease (AD) patients have low amyloid-β peptide (Aβ) clearance in the central nervous system. The peripheral Aβ clearance may also be important but its role in AD remains unclear. We aimed to study the Aβ degrading proteases including insulin degrading enzyme (IDE), angiotensin converting enzyme (ACE) and others in blood. Using the fluorogenic substrate V (a substrate of IDE and other metalloproteases), we showed that human serum degraded the substrate V, and the activity was inhibited by adding increasing dose of Aβ. The existence of IDE activity was demonstrated by the inhibition of insulin, amylin, or EDTA, and further confirmed by immunocapture of IDE using monoclonal antibodies. The involvement of ACE was indicated by the ability of the ACE inhibitor, lisinopril, to inhibit the substrate V degradation. To test the variations of substrate V degradation in humans, we used serum samples from a homebound elderly population with cognitive diagnoses. Compared with the elderly who had normal cognition, those with probable AD and amnestic mild cognitive impairment (amnestic MCI) had lower peptidase activities. Probable AD or amnestic MCI as an outcome remained negatively associated with serum substrate V degradation activity after adjusting for the confounders. The elderly with probable AD had lower serum substrate V degradation activity compared with those who had vascular dementia. The blood proteases mediating Aβ degradation may be important for the AD pathogenesis. More studies are needed to specify each Aβ degrading protease in blood as a useful biomarker and a possible treatment target for AD.
Critical issues related to transfersomes - novel vesicular system.
Source
HOD, Department of Pharmaceutics, Nalanda College of Pharmacy, India.
Abstract
It has become increasingly apparent that vesicular drug delivery elicits modest possessions in drug targeting. Transfersomes are a form of elastic or deformable vesicle, which were first introduced in the early 1990s. Elas ticity can be achieved by using an edge activator in the lipid bilayer structure. Molecules greater than 500 Da normally do not cross the skin. This prevents epicutaneous delivery of the high molecular weight therapeutics as well as non-invasive transcutaneous immunisation. Transdermal route will always remain a lucrative area for drug delivery. With the advent of new categories of drugs like peptides this route has captured more focus to combat the problems related to their delivery through oral route. But the transdermal route is equally filled with the hopes and disappointments as the transport of drug through this route faces many problems especially for the large molecules. To answer this problem many approaches were adopted. One of the very recent approaches is the use of ultra-deformable carrier systems (transfersomes). They have been used as drug carriers for a range of small molecules, peptides, proteins and vaccines, both in vitro and in vivo. Transfersomes penetrate through the pores of stratum corneum which are smaller than its size and get into the underlying viable skin in intact form. This is because of its deformable nature. The aim of this article is explanation the formation of micelle and vesicles, various types of vesicles, specifically focusing on transfersomes.
- PMID:
- 22230977
- [PubMed - in process]
Stapled peptides for intracellular drug targets.
Source
Departments of Chemistry and Chemical Biology, Stem Cell and Regenerative Biology, and Molecular and Cellular Biology, Harvard University, and Program in Cancer Chemical Biology, Dana - Farber Cancer Institute, Boston, Massachusetts, USA.
Abstract
Proteins that engage in intracellular interactions with other proteins are widely considered among the most biologically appealing yet chemically intractable targets for drug discovery. The critical interaction surfaces of these proteins typically lack the deep hydrophobic involutions that enable potent, selective targeting by small organic molecules, and their localization within the cell puts them beyond the reach of protein therapeutics. Considerable interest has therefore arisen in next-generation targeting molecules that combine the broad target recognition capabilities of proteintherapeutics with the robust cell-penetrating ability of small molecules. One type that has shown promise in early-stage studies is hydrocarbon-stapled α-helical peptides, a novel class of synthetic miniproteins locked into their bioactive α-helical fold through the site-specific introduction of a chemical brace, an all-hydrocarbon staple. Stapling can greatly improve the pharmacologic performance of peptides, increasing their target affinity, proteolytic resistance, and serum half-life while conferring on them high levels of cell penetration through endocytic vesicle trafficking. Here, we discuss considerations crucial to the successful design and evaluation of potent stapled peptide interactions, our intention being to facilitate the broad application of this technology to intractable targets of both basic biologic interest and potential therapeutic value.
Copyright © 2012 Elsevier Inc. All rights reserved.
- PMID:
- 22230563
- [PubMed - in process]
Influence of natural and synthetic histone deacetylase inhibitors on chromatin.
Source
Parkville, Victoria, Australia; paul.licciardi@mcri.edu.au.
Abstract
Histone deacetylase inhibitors (HDACI) have emerged as a new class of anticancer therapeutics. The hydroxamic acid, suberoylanilide hyroxamic acid (Vorinostat, Zolinza™) and the cyclic peptide, depsipeptide (Romidepsin, Istodax™) were approved by the US Food and Drug Administration (FDA) for the treatment of cutaneous T-cell lymphoma in 2006 and 2009, respectively. At least 15 HDACI are currently undergoing clinical trials either alone or in combination with other therapeutic modalities for the treatment of numerous hematological and solid malignancies. Further, the potential utility of HDACI has been extended to non-oncologic applications including auto-immune disorders, inflammation, diseases of the central nervous system and malaria. Given the promise of HDACI, there is growing interest in the potential of dietary compounds that possess HDAC inhibition activity. This review is focused on the identification of and recent findings with HDACI from dietary, medicinal plant and microbial sources. We discuss the mechanisms of action and clinical potential of natural HDACI.
Mapping the high-throughput SEREX technology screening for novel tumor antigens.
Source
Department of Gynecology and Obstetrics, West China Second Hospital, Sichuan University, Chengdu, 610041, People's Republic of China. xia-zhao@126.com.
Abstract
Advances in novel tumor-associated antigen (TAA) screening strategy have accelerated the identification and characterization of biomarkers and potential target molecules for tumor subtyping, diagnosis and therapeutics, which may facilitate early detection and diagnosis of the diseases individually and enhance treatment approaches for cancer. Over the past decades, a plethora of non-invasive methodologies dedicated to identify novel target molecules have been primarily focusing on the discovery of human tumor antigens recognized by the autologous antibody repertoire or cytotoxic T lymphocytes, among which serological analysis of recombinant cDNA expression libraries (SEREX) technology is chronologically first established and is of outstanding sensitivity and antigen coverage. This approach involves immunoscreening cDNA libraries extracted from fresh tumor tissues with sera from cancer patients to identify gene products recognized by IgG antibody. SEREX-defined clones can be directly sequenced and their expression profiles can be readily determined, allowing for immediate structural definition of the antigenic target and subsequent identification of TAAs and their cognate autoantibodies. This review is not only devoted to outline the SEREX technology and its advantages, drawbacks and recent modifications currently available for discovering provocative tumor antigens, but also to translate these SEREX-defined peptides into valuable cancer-specific signatures that would aid in the development of diagnostics, prognostics and therapeutics for cancer patients.
- PMID:
- 22221053
- [PubMed - as supplied by publisher]
TFAP2E-DKK4 and chemoresistance in colorectal cancer.
Source
Department of Medicine II, Universitätsmedizin Mannheim, Ruprecht-Karls-Universität Heidelberg, Mannheim, Germany. matthias.ebert@umm.de
Abstract
BACKGROUND:
Chemotherapy for advanced colorectal cancer leads to improved survival; however, predictors of response to systemic treatment are not available. Genomic and epigenetic alterations of the gene encoding transcription factor AP-2 epsilon (TFAP2E) are common in human cancers. The gene encoding dickkopf homolog 4 protein (DKK4) is a potential downstream target of TFAP2E and has been implicated in chemotherapy resistance. We aimed to further evaluate the role of TFAP2E and DKK4 as predictors of the response of colorectal cancer to chemotherapy.
METHODS:
We analyzed the expression, methylation, and function of TFAP2E in colorectal-cancer cell lines in vitro and in patients with colorectal cancer. We examined an initial cohort of 74 patients, followed by four cohorts of patients (total, 220) undergoing chemotherapy or chemoradiation.
RESULTS:
TFAP2E was hypermethylated in 38 of 74 patients (51%) in the initial cohort. Hypermethylation was associated with decreased expression of TFAP2E in primary and metastatic colorectal-cancer specimens and cell lines. Colorectal-cancer cell lines overexpressing DKK4 showed increased chemoresistance to fluorouracil but not irinotecan or oxaliplatin. In the four other patient cohorts, TFAP2E hypermethylation was significantly associated with nonresponse to chemotherapy (P<0.001). Conversely, the probability of response among patients with hypomethylation was approximately six times that in the entire population (overall estimated risk ratio, 5.74; 95% confidence interval, 3.36 to 9.79). Epigenetic alterations of TFAP2E were independent of mutations in key regulatory cancer genes, microsatellite instability, and other genes that affect fluorouracil metabolism.
CONCLUSIONS:
TFAP2E hypermethylation is associated with clinical nonresponsiveness to chemotherapy in colorectal cancer. Functional assays confirm that TFAP2E-dependent resistance is mediated through DKK4. In patients who have colorectal cancer with TFAP2E hypermethylation, targeting of DKK4 may be an option to overcome TFAP2E-mediated drug resistance. (Funded by Deutsche Forschungsgemeinschaft and others.).
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