Antimicrobial Peptides as Mediators of Innate Immunity in Teleosts

Abstract

Antimicrobial peptides (AMPs) have been identified throughout the metazoa suggesting their evolutionarily conserved nature and their presence in teleosts is no exception. AMPs are short (18–46 amino acids), usually cationic, amphipathic peptides. While AMPs are diverse in amino acid sequence, with no two AMPs being identical, they collectively appear to have conserved functions in the innate immunity of animals towards the pathogens they encounter in their environment. Fish AMPs are upregulated in response to pathogens and appear to have direct broad-spectrum antimicrobial activity towards both human and fish pathogens. However, an emerging role for AMPs as immunomodulatory molecules has become apparent—the ability of AMPs to activate the innate immune system sheds light onto the multifaceted capacity of these small peptides to combat pathogens through direct and indirect means. Herein, this review focuses on the role of teleost AMPs as modulators of the innate immune system and their regulation in response to pathogens or other exogenous molecules. The capacity to regulate AMP expression by exogenous factors may prove useful in modulating AMP expression in fish to prevent disease, particularly in aquaculture settings where crowded conditions and environmental stress pre-dispose these fish to infection.

The zebrafish as a model for gastrointestinal tract–microbe interactions

“…Zebrafish produce antimicrobial peptides, of which β-defensins, cathelicidins, hepcidins, and histone-derived peptides are also found in mammals, and piscidins are fish specific (Katzenback, 2015;Zou, Mercier, Koussounadis, & Secombes, 2007). Zebrafish produce antimicrobial peptides, of which β-defensins, cathelicidins, hepcidins, and histone-derived peptides are also found in mammals, and piscidins are fish specific (Katzenback, 2015;Zou, Mercier, Koussounadis, & Secombes, 2007).…”

Prostaglandin E 2 suppresses hCAP18/LL‐37 expression in human macrophages via EP2/EP4: implications for treatment of Mycobacterium tuberculosis infection

“…Our results were obtained with human macrophages and are difficult to compare with those obtained in zebrafish and mice. The zebrafish genome does not contain an ortholog of hCAP18 (39), and cathelicidin is therefore not a part of the zebrafish innate immune response against Mtb. Furthermore, mouse immunity against Mtb differs from humans in several ways.…”

Composition of leucocytes in peripheral blood of Patagonian toothfish (Dissostichus eleginoides, Smitt, 1898) (Nototheniidae)

“…Relative content of these cells are small. They participate in microbe phagocytosis of microorganisms, synthesis of mediators of the immune response and nonspecific factors of immunity (Manning & Nakanishi 1996;Galaktionov 2005;Havixbeck & Barreda 2015;Katzenback 2015). There were also insignificant portions of immature blast forms.…”