Year:From to
Publication Type:Article Review

Results 231 - 240 of 3087

<< Previous | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | Next >>

Last updated: 13th August 2010

Multifunctional host defense peptides: Antimicrobial peptides, the small yet big players in innate and adaptive immunity.
Auvynet C, Rosenstein Y
Instituto de Biotecnologia, Universidad Nacional Autónoma de México, Cuernavaca, Mor. Mexico.
FEBS J. 2009 Nov;276(22):6497-508.
The term 'antimicrobial peptides' refers to a large number of peptides first characterized on the basis of their antibiotic and antifungal activities. In addition to their role as endogenous antibiotics, antimicrobial peptides, also called host defense peptides, participate in multiple aspects of immunity (inflammation, wound repair, and regulation of the adaptive immune system) as well as in maintaining homeostasis. The possibility of utilizing these multifunctional molecules to effectively combat the ever-growing group of antibiotic-resistant pathogens has intensified research aimed at improving their antibiotic activity and therapeutic potential, without the burden of an exacerbated inflammatory response, but conserving their immunomodulatory potential. In this minireview, we focus on the contribution of small cationic antimicrobial peptides - particularly human cathelicidins and defensins - to the immune response and disease, highlighting recent advances in our understanding of the roles of these multifunctional molecules.
alpha-Defensins increase lung fibroblast proliferation and collagen synthesis via the beta-catenin signaling pathway.
Han W, Wang W, Mohammed KA, Su Y
Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, GA, USA.
FEBS J. 2009 Nov;276(22):6603-14.
alpha-defensins are released from granules of leukocytes and are implicated in inflammatory and fibrotic lung diseases. In the present study, the effects of alpha-defensins on the proliferation and collagen synthesis of lung fibroblasts were examined. We found that alpha-defensin-1 and alpha-defensin-2 induced dose-dependent increases in the incorporation of 5-bromo-2'-deoxy-uridine into newly synthesized DNA in two lines of human lung fibroblasts (HFL-1 and LL-86), suggesting that alpha-defensin-1 and alpha-defensin-2 stimulate the proliferation of lung fibroblasts. alpha-defensin-1 and alpha-defensin-2 also increased collagen-I mRNA (COL1A1) levels and protein contents of collagen-I and active/dephosphorylated beta-catenin without changes in total beta-catenin protein content in lung fibroblasts (HFL-1 and LL-86). Inhibition of the beta-catenin signaling pathway using quercetin prevented increases in cell proliferation and the protein content of collagen-I and active/dephosphorylated beta-catenin in lung fibroblasts, and in COL1A1 mRNA levels and collagen release into culture medium induced by alpha-defensin-1 and alpha-defensin-2. Knocking-down beta-catenin using small interfering RNA technology also prevented alpha-defensin-induced increases in cell proliferation and the protein content of collagen-I and active/dephosphorylated beta-catenin in lung fibroblasts, and in COL1A1 mRNA levels. Moreover, increases in the phosphorylation of glycogen synthase kinase 3beta, accumulation/activation of beta-catenin, and collagen synthesis induced by alpha-defensin-1 and alpha-defensin-2 were prevented by p38 mitogen-activated protein kinase inhibitor SB203580 and phosphoinositide 3-kinase inhibitor LY294002. These results indicate that alpha-defensin-1 and alpha-defensin-2 stimulate proliferation and collagen synthesis of lung fibroblasts. The beta-catenin signaling pathway mediates alpha-defensin-induced increases in cell proliferation and collagen synthesis of lung fibroblasts. alpha-defensin-induced activation of beta-catenin in lung fibroblasts might be caused by phosphorylation/inactivation of glycogen synthase kinase 3beta as a result of the activation of the p38 mitogen-activated protein kinase and phosphoinositide 3-kinase/Akt pathways.
Functional polymorphisms of DEFB1 gene in type 1 diabetes Brazilian children.
Guimarães RL, Segat L, Rocha CR, Brandão LA, Zanin V, Araujo J, Naslavsky MS, de Lima Filho JL, Crovella S
Laboratory of Immunopathology Keizo Asami (LIKA), Federal University of Pernambuco, Recife, Brazil.
Autoimmunity 2009 Aug;42 (5):406-13
We analyzed three functional 5' un-translated region beta-defensin 1 (DEFB1) single nucleotide polymorphism (SNPs) in a group of 170 type 1 diabetes (T1D) patients. In order to evaluate the SNPs influence on the disease onset and the development of other autoimmune disorder, such as celiac disease (CD) and autoimmune thyroid disease (AITD), patients were stratified according to the presence of AITD, CD, and both AITD and CD. As control group, we studied 191 healthy children and adolescent not presenting a familiar historic of T1D, CD or AITD. DEFB1 SNPs were in Hardy-Weinberg equilibrium both in healthy controls and T1D patients, as well in the T1D patients stratified according to the presence of other autoimmune disorder(s). Allele, genotype, and haplotype frequencies of T1D patients globally considered were comparable to healthy controls ones. No evidence of any association of DEFB1 SNPs with the onset of AIDT, CD, and both AITD and CD on T1D patients was evidenced. Only a minor trend was found for an increased frequency of the - 20 G allele in T1D patients only presenting AITD vs. T1D patients not presenting AITD or CD, as well as an increase of those haplotypes comprising the - 20 G allele when compared with the GCA haplotype. We also evaluated the influence of functional DEFB1 SNPs on the age of T1D onset: no significant statistical conclusion was achieved. Further studies are envisaged, in order to elucidate the possible role of functional DEFB1 polymorphisms in the onset of TD1 and other autoimmune-related disorders.
Association of Higher DEFB4 Genomic Copy Number With Crohn's Disease.
Bentley RW, Pearson J, Gearry RB, Barclay ML, McKinney C, Merriman TR, Roberts RL
Department of Pathology, University of Otago, Christchurch, New Zealand.
Am J Gastroenterol. 2010 Feb;105(2):354-9.
OBJECTIVES:Human beta-defensin 2 (hBD-2 or DEFB4) is a highly inducible, antimicrobial peptide, which may have an important role in the innate immune response at epithelial surfaces. Genomic copy number of DEFB4 is polymorphic, with most individuals possessing 3-5 copies. Increased DEFB4 copy number is a susceptibility factor for psoriasis, whereas a single study in a Crohn's disease (CD) cohort reported that decreased DEFB4 copy number is associated with colonic inflammation. Here, we analyze association of DEFB4 copy number with CD in a New Zealand case-control cohort of European origin.METHODS:DEFB4 gene copy number was determined using TaqMan quantitative PCR in 466 CD patients and 329 controls. DNA samples, independently genotyped for DEFB4 copy number by alternative methods, were used to validate the assay.RESULTS:Increased DEFB4 genomic copy number was seen in CD patients compared with controls. Individuals with >4 copies had a significantly higher risk of developing CD than those with <4 copies (odds ratio 1.54; 95% confidence interval 1.13-2.09, P=5e-05). DEFB4 genomic copy number did not differ by disease location within the CD cohort (P=0.948), nor did analysis of CD patients who had undergone surgery detect association of decreased DEFB4 genomic copy number (<4) in colonic CD compared with ileal CD (P=0.120).CONCLUSIONS:Our results indicate that elevated DEFB4 copy number is a risk factor for CD (irrespective of intestinal location), and challenge previous data supporting positive association of lower DEFB4 genomic copy number with colonic CD.Am J Gastroenterol advance online publication, 6 October 2009; doi:10.1038/ajg.2009.582.
Human defensins and LL-37 in mucosal immunity.
Doss M, White MR, Tecle T, Hartshorn KL
Boston University School of Medicine, Department of Medicine, Boston, Massachusetts, USA.
J Leukoc Biol. 2010 Jan;87(1):79-92.
Defensins are widespread in nature and have activity against a broad range of pathogens. Defensins have direct antimicrobial effects and also modulate innate and adaptive immune responses. We consider the role of human defensins and the cathelicidin LL-37 in defense of respiratory, gastrointestinal, and genitourinary tracts and the oral cavity, skin, and eye. Human beta-defensins (hBD) and human defensins 5 and 6 (HD5 and -6) are involved most obviously in mucosal responses, as they are produced principally by epithelial cells. Human alpha-defensins 1-4 (or HNPs 1-4) are produced principally by neutrophils recruited to the mucosa. Understanding the biology of defensins and LL-37 is the beginning to clarify the pathophysiology of mucosal inflammatory and infectious diseases (e.g., Crohn's disease, atopic dermatitis, lung or urinary infections). Challenges for these studies are the redundancy of innate defense mechanisms and the presence and interactions of many innate defense proteins in mucosal secretions.
Expression pattern of antibacterial genes in the Musca domestica.
Wang Y, Jin X, Zhu J, Zeng A, Chu F, Yang X, Ma Y
Institute of Pathogen Biology and Department of Pathogen Biology, Guangdong Pharmaceutical University, Guangzhou 510006, China.
Sci. China, C, Life Sci. 2009 Sep;52 (9):823-30
This work studied the transcriptional patterns of three antibacterial genes, attacin, defensin and cecropin, during the development of Musca domestica. Quantitative analysis by real-time PCR was performed on mRNA levels in different development stages and challenged 3rd-instar larva at different time points after challenge of Musca domestica. The results revealed a predominance of the transcripts of all three genes during the 3rd-instar larvae and the adults. In the meanwhile, it revealed the greatest increase in mRNA. The transcript levels increased to 801 times, 1009 times and 2500 times respectively for cecropin, attacin and defensin in 3rd-instar larvae after challenging susceptible bacterium. The results suggested that the transcriptional patterns of Musca domestica antibacterial genes were different during the different growth stages as well as the microbial challenge encountered in 3rd-instar larvae.
The variant red coat colour phenotype of Holstein cattle maps to BTA27.
Dreger DL, Schmutz SM
Department of Animal and Poultry Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada.
Anim Genet. 2010 Feb 1;41(1):109-112.
The variant red phenotype in Holstein cattle is indistinguishable from the traditional e/e recessive red phenotype caused by a mutation in melanocortin 1 receptor, but is inherited as a dominant trait in relation to black. Co-segregation analysis in four half-sib families segregating for variant red was conducted, excluding melanocortin 1 receptor, agouti signalling protein, attractin and melatonin receptor 1A as causative genes. However, variant red co-segregated with markers in a region of BTA27 that includes beta-defensin 103 (DEFB103). Two newly identified microsatellites and 5 SNPs 5' of DEFB103 were used for linkage mapping in four segregating families (LOD = 3.26). One haplotype was inherited in VR cattle in a 6-generation pedigree.
Candida famata modulates toll-like receptor, beta-defensin, and proinflammatory cytokine expression by normal human epithelial cells.
Bahri R, Saidane-Mosbahi D, Rouabhia M
Groupe de Recherche en Ecologie Buccale, Faculté de Médecine Dentaire, Pavillon de Médecine Dentaire, Université Laval, Québec, Canada.
J. Cell. Physiol. 2010 Jan;222 (1):209-18
Candida albicans is no longer the only yeast involved in infectious disorders, as others, such as C. famata, commonly associated with foods as well as terrestrial and marine environments, are being recognized as potential emerging pathogens that cause human candidiasis. We investigated the interaction between C. famata and human epithelial cells using monolayer cultures and an engineered human oral mucosa (EHOM). C. famata was able to adhere to gingival epithelial cells but failed to adopt the hyphal form in the presence/absence of proteins. Interestingly, when cultured onto the engineered human oral mucosa (EHOM), C. famata formed a biofilm and invaded the connective tissue. When normal human gingival epithelial cells were put in contact with C. famata, they expressed high levels of Toll-like receptors (TLR)-2, -4, and -6, but not TLR-9 mARN. The upregulation of TLRs was paralleled by an increase of IL-1beta and TNFalpha, but not IFNgamma mARN expression, suggesting the involvement of specific pro-inflammatory cytokines (IL-1beta and TNFalpha) in the defense against infection with C. famata. The active role of epithelial cells in the innate immunity against C. famata infection was enhanced by their capacity to express high levels of human beta-defensin (HBD)-1, -2, and -3. The upregulation of pro-inflammatory cytokines and antimicrobial peptide expression may explain the growth inhibition of C. famata by the gingival epithelial cells. Overall results provide additional evidence of the involvement of C. famata in the activation of innate immunity and the contribution of human epithelial cells in local defenses against such exogenous stimulations as C. famata infections.
Increased expression of human beta-defensin 3 in mollusca contagiosum.
Meyer-Hoffert U, Schwarz T, Schröder JM, Gläser R
Department of Dermatology, University Hospital Schleswig-Holstein, Campus Kiel, Germany.
Clin Exp Dermatol. 2010 Mar;35(2):190-2.
The human beta defensins (hBDs)-2 and -3 are inducible antimicrobial peptides present in human skin. Besides an important role in fighting bacteria, they also have an antiviral function. Molluscum contagiosum (MC) is a cutaneous viral disease caused by the MC virus. Lesions show a tendency towards spontaneous regression, which might be caused by antiviral proteins such as defensins. We report a marked increase in hBD-3 immunoreactivity in MC lesions in contrast to hBD-2, which was only marginally increased. We suggest a role for the hBD-3 peptide in MC pathogenesis.
Growth factors/cytokines/defensins and apoptosis in periodontal pathologies.
Laurina Z, Pilmane M, Care R
Riga Stradins University, Institute of Stomatology, 20 Dzirciema Street, Riga, Latvia, LV 1007.
Stomatologija. 2009;11(2):48-54.
In the recent past there has been an increased emphasis on morphogenetic tissue research of periodontal tissues. The aim of this study was to find qualitative and quantitative correlations in distribution and appearance of growth factors/cytokines/defensins and apoptosis in periodontal pathologies. MATERIAL AND METHODS. Tissue was obtained from 5 controls and 6 chronical periodontitis patients 30-50 years of age referred to Latvian Institute of Stomatology. Histological investigations were performed at the Institute of Anatomy and Anthropology of Riga Stradins University. RESULTS. Epithelial cells abundantly expressed IL10 in patients. The expression of b-defensins was very variable in both sulcular and gingival epithelium. TUNEL positive cells were observed in patients and control specimens with dominance in control group. Gingival epithelium showed moderate expression of bFGF whereas few to moderate cells were positive for bFGF in sulcular epithelium. Fibroblast growth factor receptor (FGF-1R) was abundant in gingival epithelium and in connective tissue cells, but almost not detectable in sulcular epithelium. Insulin-like growth factor receptor was not expressed in gingival epithelium and was weakly seen in basal layer of sulcular epithelium. Basic nerve growth factor expresion in both types of epithelium was numerous to abundant. Staining for the NGFR in the gingival epithelium was variable, with prevalence to be moderate whereas sulcular epithelium was free from any factor immunoreactivity. CONCLUSION. 1. Finding of apoptotic cells are variable and seems to correlate with the expression of defensins in oral epithelium in patients with periodontitis. 2. FGFR was expressed more than the bFGF, but in case with NGFR and bNGF situation was opposite. Although IGFRI was found in sulcular epithelium with no expression in gingival one suggesting about stimulation in regeneration/adaptation in periodontitis affected tissue. 3. The expression of growth factors and their receptors in sulcular epithelium was lower than into the gingival epithelium and seems to be specific for periodontitis.