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Last updated: 13th August 2010

Expression and distribution of antimicrobial peptides in the skin of healthy beagles.
Santoro D, Bunick D, Graves TK, Campbell KL
Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
Veterinary dermatology 2010 Jul
Abstract Antimicrobial peptides (AMPs) are small proteins involved in defense against pathogenic organisms. Defensins and cathelicidin are the most frequently studied human AMPs. Our goals were to determine the distribution of AMPs and evaluate their mRNA expression in normal canine skin. Skin biopsies were taken from six healthy beagles. The relative transcript level of canine cathelicidin (cCath) and beta-defensin (cBD)-1, cBD2 and cBD3 mRNA was quantified using quantitative real-time polymerase chain reaction. Indirect immunofluorescence (IIF), using polyclonal antibodies against cBD2, cBD3 and cCath, was used to evaluate protein localization in the skin of healthy dogs. The Pfaffl method, using experimentally determined primer efficiencies of amplification, was used to determine the expression level of cCath, cBD1 and cDB3 relative to cDB2. The levels of cCath, cBD3 and cBD1 mRNA were 358, 296 and 177 times higher than those of cBD2, respectively. Using IIF, cBD2 and cBD3 protein fluorescence was detected in all layers of the epidermis, whereas cCath was detected predominantly in the stratum granulosum and corneum. In addition, antimicrobial peptide detection was limited to the infundibular portion of the pilosebaceous units. We have validated useful methods to evaluate AMPs in canine skin. Further studies are needed to compare AMP expression in healthy dogs with that of dogs with inflammatory skin conditions.
Drosotoxin, a selective inhibitor of tetrodotoxin-resistant sodium channels.
Zhu S, Gao B, Deng M, Yuan Y, Luo L, Peigneur S, Xiao Y, Liang S, Tytgat J
Group of Animal Innate Immunity, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101, China.
Biochem Pharmacol. 2010 Oct 15;80(8):1296-302.
The design of animal toxins with high target selectivity has long been a goal in protein engineering. Based on evolutionary relationship between the Drosophila antifungal defensin (drosomycin) and scorpion depressant Na(+) channel toxins, we exploited a strategy to create a novel chimeric molecule (named drosotoxin) with high selectivity for channel subtypes, which was achieved by using drosomycin to substitute the structural core of BmKITc, a depressant toxin acting on both insect and mammalian Na(+) channels. Recombinant drosotoxin selectively inhibited tetrodotoxin-resistant (TTX-R) Na(+) channels in rat dorsal root ganglion (DRG) neurons with a 50% inhibitory concentration (IC(50)) of 2.6+/-0.5muM. This chimeric peptide showed no activity on K(+), Ca(2+) and TTX-sensitive (TTX-S) Na(+) channels in rat DRG neurons and Drosophila para/tipE channels at micromolar concentrations. Drosotoxin represents the first chimeric toxin and example of a non-toxic core scaffold with high selectivity on mammalian TTX-R Na(+) channels.
Functional analysis of an alpha-helical antimicrobial peptide derived from a novel mouse defensin-like gene.
Kawaguchi A, Suzuki T, Kimura T, Sakai N, Ayabe T, Sawa H, Hasegawa H
Department of Molecular Pathobiology, Research Center for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan; Global COE program, Research Center for Zoonosis Control, Hokkaido University, Sapporo 001-0020, Japan; Department of Pathology, National Institute of Infectious Diseases, Musashimurayama-shi, Tokyo, Japan.
Biochemical and biophysical research communications 2010 Aug;398 (4):778-784
Gene-encoded antimicrobial peptides (AMPs) are an essential component of the innate immune system in many species. Analysis of beta-defensin gene expression in mouse tissue using primers that were specific for conserved sequences located outside of the beta-defensin translated region identified a novel small gene. The novel gene had an open reading frame of 114bp and encoded a predicted protein of 37 amino acid residues. A search of the genome database revealed that the gene locus and the sequence of exon 1 of this novel gene were similar to subgroup 1 mouse beta-defensins. A small peptide, K17 (FSPQMLQDIIEKKTKIL), derived from the amino acid sequence of this novel gene was synthesized. Circular dichroism (CD) spectroscopic analysis of chemically synthesized peptide demonstrated that the peptide exhibited random coil conformation in aqueous solution, but the peptide adopted helical conformation in the presence of trifluoroethanol or sodium dodecyl sulfate, a membrane-mimicking environment. The peptide exhibited bactericidal activity against Salmonella enterica serovar Typhimurium (Gram negative) and Staphylococcus aureus (Gram positive); it was not cytotoxic in cultures of mammalian cells or hemolytic in cultures of erythrocytes. These results suggested that K17 may be a candidate therapeutic for the treatment of bacterial infection.
Sphingosine kinase-1 is required for toll mediated beta-defensin 2 induction in human oral keratinocytes.
Benakanakere MR, Zhao J, Galicia JC, Martin M, Kinane DF
Department of Pathology, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
PLoS ONE 2010 ;5 (7):e11512
BACKGROUND: Host defense against invading pathogens is triggered by various receptors including toll-like receptors (TLRs). Activation of TLRs is a pivotal step in the initiation of innate, inflammatory, and antimicrobial defense mechanisms. Human beta-defensin 2 (HBD-2) is a cationic antimicrobial peptide secreted upon gram-negative bacterial perturbation in many cells. Stimulation of various TLRs has been shown to induce HBD-2 in oral keratinocytes, yet the underlying cellular mechanisms of this induction are poorly understood. PRINCIPAL FINDINGS: Here we demonstrate that HBD-2 induction is mediated by the Sphingosine kinase-1 (Sphk-1) and augmented by the inhibition of Glycogen Synthase Kinase-3beta (GSK-3beta) via the Phosphoinositide 3-kinase (PI3K) dependent pathway. HBD-2 secretion was dose dependently inhibited by a pharmacological inhibitor of Sphk-1. Interestingly, inhibition of GSK-3beta by SB 216763 or by RNA interference, augmented HBD-2 induction. Overexpression of Sphk-1 with concomitant inhibition of GSK-3beta enhanced the induction of beta-defensin-2 in oral keratinocytes. Ectopic expression of constitutively active GSK-3beta (S9A) abrogated HBD-2 whereas kinase inactive GSK-3beta (R85A) induced higher amounts of HBD-2. CONCLUSIONS/SIGNIFICANCE: These data implicate Sphk-1 in HBD-2 regulation in oral keratinocytes which also involves the activation of PI3K, AKT, GSK-3beta and ERK 1/2. Thus we reveal the intricate relationship and pathways of toll-signaling molecules regulating HBD-2 which may have therapeutic potential.
De novo Designed Lipopolysaccharide Binding Peptides: Structure Based Development of Antiendotoxic and Antimicrobial Drugs.
Bhattacharjya S
School of Biological Sciences, Nanyang Technological University, 637551, Singapore.
Current medicinal chemistry 2010 Jul
Lipopolysaccharide (LPS), the glycolipid of the outer membrane of Gram-negative bacteria, is critically involved in health and diseases. LPS facilitates the survival of pathogens by imposing a permeability barrier against antibiotics and antimicrobial peptides. LPS, also termed as endotoxin, functions as a potent inducer of innate immunity. Interception of endotoxin in systemic circulation by immune cells e.g. macrophages is essential to mount surveillance against invading microbes. However, a hyper-activated immune response may lead to the overwhelming production of tissue damaging cytokines TNF-α, IL-1, IL-6 and free radicals that may cause multiple organ failures or septic shock syndromes. The sepsis or septic shock is the major cause of mortality; 120,000 deaths/year occur in the United States alone, in the intensive care units. To-date, no therapeutic is available to combat sepsis mediated lethality. Furthermore, bacterial resistance against commonly used antibiotics has been increasing at an alarming rate necessitating a search for antibacterial agents with novel mode of actions. LPS could be a valid drug target for the development of antiendotoxic and antimicrobial compounds. In this article, recent advances in structural basis of LPS recognition by its receptor proteins and mode of actions of antimicrobial peptides defensins and cathelicidins are reviewed. Our research has identified, through de novo design, antimicrobial and endotoxin interacting β-boomerang peptides. Structure-activity correlations (SAR) of these peptides have been discussed, highlighting future design to achieve potent LPS neutralizing molecules.
[The relationship between HalphaD-5 and HbetaD-2 in infertile women´s fimbriae tubes with adhesions and atresias]
Hu SW, Mao C, Zhang D, Lan Z, Wang CF, Luo S
Department of Reproductive Endocrinology, West China Second Hospital, Sichuan University, Chengdu 610041, China.
Sichuan Da Xue Xue Bao Yi Xue Ban 2010 May;41 (3):480-2
OBJECTIVE: To investigate the expression and relationship of human alpha defensin-5 (HalphaD-5) and human beta defensin-2 (HbetaD-2) in human fimbriae tubes with adhesions and atresias. METHODS: The tissue samples were collected from 30 human fimbriae tubes with adhesions and atresias, and 30 cases without adhesions and atresias. The expression of HalphaD-5 and HbetaD-2 in fimbriae tube tissue were measured by immunohistochemical SP methods. Image pro-plus 6.0 software was used to test the average IOD value of positive staining. Differences of HalphaD-5 and HbetaD-2 expressions were analyzed by independent-samples T test. The relationship between HalphaD-5 and HbetaD-2 was analyzed by Pearson correlation. RESULTS: We found that HalphaD-5 and HbetaD-2 mainly expressed in the epithelial cells which face to lumen, mostly in the cytochylema. Both two groups expressed HalphaD-5 and HbetaD-2, but the degrees were different. Compared with human fimbriae tubes without adhesions or atresias, the expressions of HalphaD-5 and HbetaD-2 increased significantly in adhesion cases (P(HalphaD--5) = 0.000, P(HbetaD--2) = 0.02). In the group without adhesion, there was a positive correlation between HalphaD-5 and HbetaD-2 (r = 0.404, P = 0.027), while in the adhesion group, there was no correlation between HalphaD-5 and HbetaD-2 (P = 0.089). CONCLUSION: HalphaD-5 and HbetaD-2 may protect fimbriae tubes during the pathological process of microorganisms attack.
NmDef02, a novel antimicrobial gene isolated from Nicotiana megalosiphon confers high-level pathogen resistance under greenhouse and field conditions.
Portieles R, Ayra C, Gonzalez E, Gallo A, Rodriguez R, Chacón O, López Y, Rodriguez M, Castillo J, Pujol M, Enriquez G, Borroto C, Trujillo L, Thomma BP, Borrás-Hidalgo O
Center for Genetic Engineering and Biotechnology, Havana, Cuba.
Plant Biotechnol. J. 2010 Aug;8 (6):678-90
Plant defensins are small cysteine-rich peptides that inhibit the growth of a broad range of microbes. In this article, we describe NmDef02, a novel cDNA encoding a putative defensin isolated from Nicotiana megalosiphon upon inoculation with the tobacco blue mould pathogen Peronospora hyoscyami f.sp. tabacina. NmDef02 was heterologously expressed in the yeast Pichia pastoris, and the purified recombinant protein was found to display antimicrobial activity in vitro against important plant pathogens. Constitutive expression of NmDef02 gene in transgenic tobacco and potato plants enhanced resistance against various plant microbial pathogens, including the oomycete Phytophthora infestans, causal agent of the economically important potato late blight disease, under greenhouse and field conditions.
Purification and Characterization of Avian {beta}-Defensin 11 (AvBD11): an Antimicrobial Peptide of the Hen Egg.
Hervé-Grépinet V, Réhault-Godbert S, Labas V, Magallon T, Derache C, Lavergne M, Gautron J, Lalmanach AC, Nys Y
INRA, UR83 Recherches Avicoles, F-37380 Nouzilly, France; UMR INRA 85 - CNRS 6175 - Université François Rabelais, Physiologie de la Reproduction et des Comportements, Plate-forme de Protéomique Analytique et Fonctionnelle, F-37380 Nouzilly, France; INRA, UR 1282 Infectiologie Animale et Santé Publique, F-37380 Nouzilly, France.
Antimicrobial agents and chemotherapy 2010 Jul
Natural antimicrobial peptides are present in different compartments (eggshell, egg white, vitelline membranes) of the hen egg and are expected to be involved in the protection of the embryo during its development and to contribute to production of pathogen-free eggs. In the present study, we used vitelline membranes from hen (Gallus gallus) eggs, as a source of avian beta-defensin 11 (AvBD11). A purification scheme using affinity chromatography and reverse phase chromatography was developed. Purified AvBD11 was analysed by a combination of mass spectrometry approaches to characterize its primary sequence and structure. A monoisotopic molecular specie at [M+H](+) = 9,271.56 Daltons was obtained and its N and C-terminal sequences were determined. We also examined post-translational modifications and identified the presence of 6 internal disulfide bonds. AvBD11 was found to exhibit antimicrobial activity towards both Gram-positive and Gram-negative bacteria.
A possible role of hepcidin in the pathogenesis of anemia in heart allograft recipients.
Przybylowski P, Malyszko J, Malyszko JS
Department of Cardiovascular Surgery and Transplantology Jagiellonian University, John Paul II Hospital, Cracow, Poland.
Transplant. Proc. 2010 Jun;42 (5):1803-7
Hepcidin, a small defensin-like peptide produced by hepatocytes, is modulated in response to anemia, hypoxia, or inflammation. We studied hepcidin correlations with markers of iron status and of inflammation among 134 prevalent recipients of heart allografts (OHT). In addition, we assessed the prevalence of anemia and its relation to hepcidin. Soluble transferrin (sTfR), interleukin (IL)-6, cystatin C, and hepcidin receptors were measured using commercially available kits. According to the World Health Organization definition, the prevalence of anemia was 40%. Anemic OHT showed significantly higher values of serum creatinine, cystatin C, hepcidin, IL-6, ferritin, soluble transferrin receptor, NT-proBNP, everolimus treatment, and significantly lower quantities of cholesterol, low-density lipoprotein, ejection fraction, hemoglobin, erythrocyte count, and estimated glomerular filtration rate (GFR) (Modification of Diet in Renal Disease, CKD-EPI). Hepcidin correlated with total iron binding capacity, ferritin, IL-6, hemoglobin, erythrocyte count, cystatin C, NT-proBNP, creatinine, and GFR. Multiple regression analysis showed hepcidin to be independently related only to ferritin, explaining 76% of the variation in hepcidin. The prevalence of anemia is relatively great among the population of heart allograft recipients. In these patients the pathogenesis of anemia is multifactorial. Elevated hepcidin levels in heart transplant recipients may be due to low-grade inflammation, which is frequently encountered in this population, as well as probably to impaired renal function, but it does not seem to be a major pathogenic factor for anemia among this population.
[Eosinophil: a new effector of innate immunity?]
Driss V, Legrand F, Loiseau S, Capron M
V. Driss : Inserm U547, Université Lille 2, Institut fédératif de recherche 142, Institut Pasteur de Lille, France ; Inserm U837, Institut de recherche sur le cancer de Lille, Université Lille 2, Institut fédératif de recherche 114, Lille, France. F. Legrand : Inserm U547, Université Lille 2, Institut fédératif de recherche 142, Institut Pasteur de Lille ; Laboratoire d´immunologie du CHRU de Lille, Université Lille 2, Centre de biologie pathologie, Lille ; Inserm U995, Faculté de médecine, Université Lille 2, Institut fédératif de recherche 114, Lille. S. Loiseau, M. Capron : Inserm U547, Université Lille 2, Institut fédératif de recherche 142, Institut Pasteur de Lille, France ; Inserm U995, Faculté de médecine, Université Lille 2, Institut fédératif de recherche 114, 1, place de Verdun, 59045 Lille Cedex, France.
Medecine sciences : M/S ;26 (6-7):621-626
The eosinophil leukocyte has long been considered as a second class cell. It appears now that its functions extend far beyond solely the release of cytotoxic mediators involved in a protective role in some parasitic infections or in pathological manifestations during allergic diseases. The recent demonstration that eosinophils express innate immune receptors (TLR, gdTCR) and mediators (a-defensins), in addition to the numerous receptors involved in adaptive immunity, confers to eosinophils the potential to directly recognize danger signals including pathogens. Thus, both such a functional plasticity together with its strategic tissue localization indicate that eosinophils likely play a previously unsuspected role in anti-infectious response.