Chicken avian β-defensin 8 modulates immune response via the mitogen-activated protein kinase signaling pathways in a chicken macrophage cell line (original) (raw)
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Asian-Australasian journal of animal sciences, 2018
Defensins are a large family of antimicrobial peptides and components of the innate immune system that invoke an immediate immune response against harmful pathogens. Defensins are classified into alpha-, beta-, and theta-defensins. Avian species only possess beta-defensins (AvBDs), and approximately 14 AvBDs (AvBD1-AvBD14) have been identified in chickens to date. Although substantial information is available on the conservation and phylogenetics, limited information is available on the expression and regulation of AvBD8 in chicken immune tissues and cells. We examined AvBD8 protein expression in immune tissues of White Leghorn chickens (WL) by immunohistochemistry and quantitative reverse transcription-PCR (RT-qPCR). In addition, we examined AvBD8 expression in chicken T-, B-, macrophage-, and fibroblast-cell lines and its regulation in these cells after lipopolysaccharide (LPS) treatment by immunocytochemistry and RT-qPCR. Our results showed that chicken AvBD8 protein was strongly...
Frontiers in Microbiology
Defensins are natural antimicrobial peptides. The avian beta-defensin AvBD7 isolated from the chicken bone marrow possess broad antibacterial spectrum and strong resistance to proteolysis. However, its ability to fight systemic infections of major concern for public health, such as salmonellosis, is unknown. As a first approach, fluorescence labeling of AvBD7 allowed to track its systemic distribution after intraperitoneal injection in mice using whole body live imaging. It was associated to peritoneal cells and to deeper organs such as the liver. In the next step, the use of labeled AvBD7 allowed to observe its interaction with murine macrophages in culture. After incubation, it was able to penetrate inside the cells through an endocytosis-like mechanism. Furthermore, natural AvBD7 contributed to the control of intracellular multiplication of a multidrug resistant Salmonella strain, after incubation with infected macrophages. Finally, administration in a model of systemic lethal Salmonella infection in mice led to significant improvement of mouse survival, consistently with significant reduction of the liver bacterial load. In conclusion, the results reveal a hitherto unknown intracellular antibacterial effect of AvBD7 in Salmonella target cells and support AvBD7 as a candidate of interest for the treatment of infectious diseases caused by multidrug-resistant pathogenic Enterobacteriaceae.
Biocidal activity of chicken defensin-9 against microbial pathogens
Biochemistry and Cell Biology, 2016
In this study we identified the expression patterns of β-defensin-9 in chickens from Saudi Arabia, evaluated the antimicrobial activities of synthetic chicken β-defensin-9 (sAvBD-9) against pathogenic bacteria and fungi, and investigated the mode of action of sAvBD-9 on bacterial cells. The AvBD-9 gene of Saudi chickens encodes a polypeptide of 67 amino acids, which is highly similar to the polypeptide in duck, quail, and goose (97%, 86%, and 87%, respectively) and shares a low sequence similarity with the mammalian defensins. AvBD-9 is expressed in various organs and tissues of Saudi chickens and inhibits the growth of both Gram-negative and Gram-positive bacteria, as well as showing activity against unicellular and multicellular fungi (Aspergillus flavus, A. niger, and Candida albicans). sAvBD-9 completely inhibited the growth of both Gram-positive and Gram-negative bacterial strains as well as Candida albicans. The haemolytic effects of sAvBD-9 were limited. Morphological analysi...
Initial Insights into Structure-Activity Relationships of Avian Defensins
Journal of Biological Chemistry, 2011
Background: Avian defensins are antimicrobial peptides of a bird's immunity. Results: The target of chicken AvBD2 defensin is not chiral. Its structure is not amphipathic. The reduced and AvBD2-K31A forms dramatically decrease antibacterial activity. Conclusion: AvBD2 may disrupt the bacterial membrane through a nonchiral, nonspecific interaction. Significance: Knowledge of the structure-function relationships of avian defensins is a prerequisite for their use as alternatives to antibiotics. * The work was supported by "Biotechnocentre" Grant 3200068 from the Région Centre, France, by a doctoral fellowship from Institut National de la Recherche Agronomique and Région Centre, by a postdoctoral fellowship from CNRS. Financial support from the TGE RMN THC Fr3050 for conducting the research is gratefully acknowledged. □ S This article contains supplemental Figs. S1-S6 and Tables S1-S3.
Molecular Immunology, 2009
The cationic, cysteine-rich peptides called -defensins play a major role in the innate immune response. Here, we describe the identification and characterization of the duck -defensin-2 homologue, Anas platyrhynchos avian -defensin 2 (Apl AvBD2). The 195 base pair open reading frame (ORF) of Apl AvBD2 has 83% identity with Gga AvBD2 (chicken) and 85% identity with Mga AvBD2 (turkey) at nucleotide level. The gene corresponding to the coding region is comprised of three exons and two introns in both Apl AvBD2 and Gga AvBD2. The predicted secondary structure of Apl AvBD2 has the classical "defensin core motif" formed by the -sheet rich structure. Apart from mild expression in tissues like kidney, lung, brain, bursa of Fabricious and ovary, Apl AvBD2 mRNA show a very high level constitutive expression in bone marrow and spleen, indicating that it is a myeloid defensin. Purified recombinant Apl AvBD2 demonstrated in vitro antibacterial activity against both Gram-positive and Gram-negative bacteria, with a minimum bactericidal concentration (MBC) of 3.7 M against Micrococcus luteus NCIM 2871 and Escherichia coli NCIM 2685, and of 2.2 M against Reimerella anatipestifer. The immunomodulatory potential of Apl AvBD2 was shown by chemotaxis of DT-40 chicken B-lymphocytes. The widespread tissue distribution and the potent bactericidal and chemotactic activity make Apl AvBD2 an important molecule in the innate immune response in ducks. It may play a vital role in the immune response of these birds against bacterial and viral pathogens.
Immunogenetics, 2007
Antimicrobial peptides (AMPs), essential components of innate immunity, are found in a range of phylogenetically diverse species and are thought to act by disrupting the membrane integrity of microbes. In this paper, we used evolutionary signatures to identify sites that are most relevant during the functional evolution of these molecules and introduced amino acid substitutions to improve activity. We first demonstrate that the anti-microbial activity of chicken avian β-defensin-8, previously known as gallinacin-12, can be significantly increased against Escherichia coli, Listeria monocytogenes, Salmonella typhimurium, Salmonella typhimurium phoP− mutant and Streptococcus pyogenes through targeted amino acid substitutions, which confer increased peptide charge. However, by increasing the AMP charge through amino acid substitutions at sites predicted to be subject to positive selection, antimicrobial activity against Escherichia coli was further increased. In contrast, no further increase in activity was observed against the remaining pathogens. This result suggests that chargeincreasing modifications confer increased broad-spectrum activity to an AMP, whilst positive selection at particular sites is involved in directing the antimicrobial response against specific pathogens. Thus, there is potential for the rational design of novel therapeutics based on specifically targeted and modified AMPs.
Frontiers in cellular and infection microbiology, 2015
Host Defense Peptides (HDPs) are small cationic peptides found in several organisms. They play a vital role in innate immunity response and immunomodulatory stimulation. This investigation was designed to study the antimicrobial activities of β-defensin peptide-4 (sAvBD-4) and 10 (sAvBD-4) derived from chickens against pathogenic organisms including bacteria and fungi. Ten bacterial strains and three fungal species were used in investigation. The results showed that the sAvBD-10 displayed a higher bactericidal potency against all the tested bacterial strains than that of sAvBD-4. The exhibited bactericidal activity was significant against almost the different bacterial strains at different peptide concentrations except for that of Pseudomonas aeruginosa (P. aeruginosa) and Streptococcus bovis (Str. bovis) strains where a moderate effect was noted. Both peptides were effective in the inactivation of fungal species tested yielding a killing rate of up to 95%. The results revealed that...
PloS one, 2016
Defensins are frontline peptides of mucosal immunity in the animal kingdom, including birds. Their resistance to proteolysis and their ensuing ability to maintain antimicrobial potential remains questionable and was therefore investigated. We have shown by bottom-up mass spectrometry analysis of protein extracts that both avian beta-defensins AvBD2 and AvBD7 were ubiquitously distributed along the chicken gut. Cathepsin B was found by immunoblotting in jejunum, ileum, caecum, and caecal tonsils, while cathepsins K, L, and S were merely identified in caecal tonsils. Hydrolysis product of AvBD2 and AvBD7 incubated with a panel of proteases was analysed by RP-HPLC, mass spectrometry and antimicrobial assays. AvBD2 and AvBD7 were resistant to serine proteases and to cathepsins D and H. Conversely cysteine cathepsins B, K, L, and S degraded AvBD2 and abolished its antibacterial activity. Only cathepsin K cleaved AvBD7 and released Ile4-AvBD7, a N-terminal truncated natural peptidoform of...
Immunogenetics, 2005
Antimicrobial peptides are essential components of innate immunity and are generally thought to act by disrupting the membrane integrity of microbes. Here we report the discovery of two novel chicken β-defensins, gallinacin (Gal)-11 and Gal-12, found by hidden Markov model profile searching of the chicken genome. We have sequenced the genes and elucidated the 3′UTR of Gal-11. Differential mRNA expression of these novel genes has been shown across a panel of chicken tissues. Gal-11 mRNAwas highly expressed in the small intestine, the liver, the gall bladder and the spleen and also showed moderate expression in several other areas of the chicken anatomy, whilst Gal-12 mRNAwas found only in the liver and the gall bladder. Antimicrobial activity of synthetic Gal-11 has been demonstrated against a range of bacteria and is predominantly active against the intestinal pathogens Salmonella typhimurium and Listeria monocytogenes.
Current status of defensins and their role in innate and adaptive immunity
FEMS Microbiology Letters, 2002
Naturally occurring antimicrobial cationic polypeptides play a major role in innate and adaptive immunity. These polypeptides are found to be either linear and unstructured or structured through disulfide bonds. Among the structured antimicrobial polypeptides, defensins comprise a family of cysteine-rich cationic polypeptides that contribute significantly to host defense against the invasion of microorganisms in animals, humans, insects and plants. Their wide-spread occurrence in various tissues of these diverse organisms, and their importance in innate and adaptive immunity have led to their identification, isolation and characterization. A large volume of literature is available on defensins' occurrence, structural characterization, gene expression and regulation under normal and pathological conditions. Much has also been published regarding their antimicrobial, antiviral and chemoattractive properties, and their molecular and cellular interactions. In this review, we describe the current status of our knowledge of defensins with respect to their molecular, cellular and structural biology, their role in host defense, future research paradigms and the possibility of their utilization as a new class of non-toxic antimicrobial agents and immuno-modulators. ß