The role of histones in the immune responses of aquatic invertebrates

Abstract

Histones are primary components of eukaryotic chromatin and highly abundant in all animal cells. In addition to their important role in chromatin structure and transcriptional regulation, histones contribute to innate immune responses. In several aquatic invertebrate species, as well as in many other invertebrate and vertebrate species, the transcripts for core histones are upregulated in response to immune challenge and exposure to environmental stressors. Histones show antimicrobial activity against bacteria and parasites in vitro and in vivo and have the ability to bind bacterial lipopolysaccharide and other pathogen-associated molecules. Several mechanisms regulating and facilitating the antimicrobial action of histones against pathogens have been described in vertebrate and some invertebrate species, including the production of Extracellular Traps (ETs) and the accumulation of histones in lipid droplets that can be selectively released in response to immune stimuli. Further studies are needed to determine the mechanisms of action of histones in immune responses in aquatic invertebrates and investigate the potential use of histones in the treatment of infectious diseases in aquaculture.