Avian host defense peptides

Cuperus, Tryntsje; Coorens, Maarten; Dijk, Albert van; Haagsman, Henk P.

doi:10.1016/j.dci.2013.04.019

Cited by 169 publications

(185 citation statements)

References 188 publications

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“…In chicken, 14 b-defensin (GAL1-14) and 4 cathelicidin (Fowlicidin1-3 and cathelicidin-B1) genes have been identified in the chicken (Xiao et al, 2004(Xiao et al, , 2006Lynn et al, 2007). Although there are some discrepancies between studies analyzing the tissue expression of chicken HDPs, the crucial role of HDP in chicken innate immunity is well-documented, particularly chicken bdefensins, which show widespread antimicrobial activity against bacteria and fungi (Cuperus et al, 2013). Additionally, chicken b-defensins have been found to be important in immune regulation, such as anti-inflammation by blocking LPS-induced inflammation and promotion of wound-healing.…”

Section: Introductionmentioning

confidence: 99%

Expression of β-defensins in intestines of chickens injected with vitamin D3 and lipopolysaccharide

Zhang

et al. 2015

Genet. Mol. Res.

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ABSTRACT. The objective of this study was to evaluate the effect of vitamin D 3 (VD 3 ) on the regulation of chicken intestinal b-defensin genes under normal and lipopolysaccharides (LPS) conditions. Four treatment groups were used, including a negative control group, VD 3 -injection group, LPS-injection group, and both VD 3 -injection and LPS-injection group. At 4, 24, and 48 h post-injection, intestines were collected and RNA was isolated to measure the chicken b-defensin genes with putative vitamin D responsive elements using quantitative polymerase chain reaction. Expressions of all 7 chicken b-defensin genes was detectable in the intestines. Significant increases in GAL-6, -7 and -9 were found following LPS injection treatment at 4, 24, and 48 h post-injection, respectively, whereas VD 3 injection did not affect the expression of any investigated genes under normal conditions. However, the expression of were synergistically upregulated by VD 3 in combination with LPS. These results suggest that VD 3 enhances the immune immunity during LPS challenge by inducing the expression of chicken b-defensin genes when birds are exposed to immune stressors.

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Section: Introductionmentioning

confidence: 99%

Expression of β-defensins in intestines of chickens injected with vitamin D3 and lipopolysaccharide

Zhang

et al. 2015

Genet. Mol. Res.

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“…Many cathelicidin functions have been described over the years that can play a role in their protective effects during infections (20,21). First, cathelicidins are well known for their antimicrobial activity, although this activity has been questioned, because many cathelicidins show a reduced antimicrobial activity when tested under more physiological conditions (22,23).…”

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Cathelicidins Inhibit Escherichia coli–Induced TLR2 and TLR4 Activation in a Viability-Dependent Manner

Coorens

Schneider

Groot

et al. 2017

The Journal of Immunology

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Activation of the immune system needs to be tightly regulated to provide protection against infections and, at the same time, to prevent excessive inflammation to limit collateral damage to the host. This tight regulation includes regulating the activation of TLRs, which are key players in the recognition of invading microbes. A group of short cationic antimicrobial peptides, called cathelicidins, have previously been shown to modulate TLR activation by synthetic or purified TLR ligands and may play an important role in the regulation of inflammation during infections. However, little is known about how these cathelicidins affect TLR activation in the context of complete and viable bacteria. In this article, we show that chicken cathelicidin-2 kills Escherichia coli in an immunogenically silent fashion. Our results show that chicken cathelicidin-2 kills E. coli by permeabilizing the bacterial inner membrane and subsequently binds the outer membrane-derived lipoproteins and LPS to inhibit TLR2 and TLR4 activation, respectively. In addition, other cathelicidins, including human, mouse, pig, and dog cathelicidins, which lack antimicrobial activity under cell culture conditions, only inhibit macrophage activation by nonviable E. coli. In total, this study shows that cathelicidins do not affect immune activation by viable bacteria and only inhibit inflammation when bacterial viability is lost. Therefore, cathelicidins provide a novel mechanism by which the immune system can discriminate between viable and nonviable Gramnegative bacteria to tune the immune response, thereby limiting collateral damage to the host and the risk for sepsis.

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“…Chicken cathelicidin-2 (CATH-2), one of the four cathelicidins produced by chickens, is a potent antimicrobial peptide (15), but its antifungal activity has not yet been described. Interestingly, the processed peptide does not have any sequence homology with LL-37, and even though both peptides possess an amphipathic ␣-helical structure, CATH-2 has a pronounced kink due to a proline residue, which divides the peptide into two ␣-helical segments.…”

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confidence: 99%

Fungicidal Mechanisms of Cathelicidins LL-37 and CATH-2 Revealed by Live-Cell Imaging

Ordoñez

Amarullah

Wubbolts

et al. 2014

Antimicrob Agents Chemother

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Antifungal mechanisms of action of two cathelicidins, chicken CATH-2 and human LL-37, were studied and compared with the mode of action of the salivary peptide histatin 5 (Hst5). Candida albicans was used as a model organism for fungal pathogens. Analysis by live-cell imaging showed that the peptides kill C. albicans rapidly. CATH-2 is the most active peptide and kills C. albicans within 5 min. Both cathelicidins induce cell membrane permeabilization and simultaneous vacuolar expansion. Minimal fungicidal concentrations (MFC) are in the same order of magnitude for all three peptides, but the mechanisms of antifungal activity are very different. The activity of cathelicidins is independent of the energy status of the fungal cell, unlike Hst5 activity. Live-cell imaging using fluorescently labeled peptides showed that both CATH-2 and LL-37 quickly localize to the C. albicans cell membrane, while Hst5 was mainly directed to the fungal vacuole. Small amounts of cathelicidins internalize at sub-MFCs, suggesting that intracellular activities of the peptide could contribute to the antifungal activity. Analysis by flow cytometry indicated that CATH-2 significantly decreases C. albicans cell size. Finally, electron microscopy showed that CATH-2 affects the integrity of the cell membrane and nuclear envelope. It is concluded that the general mechanisms of action of both cathelicidins are partially similar (but very different from that of Hst5). CATH-2 has unique features and possesses antifungal potential superior to that of LL-37.

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Avian host defense peptides

Cited by 169 publications

References 188 publications

Expression of β-defensins in intestines of chickens injected with vitamin D3 and lipopolysaccharide

Expression of β-defensins in intestines of chickens injected with vitamin D3 and lipopolysaccharide

Cathelicidins Inhibit Escherichia coli–Induced TLR2 and TLR4 Activation in a Viability-Dependent Manner

Fungicidal Mechanisms of Cathelicidins LL-37 and CATH-2 Revealed by Live-Cell Imaging

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