Detecting Intestinal Goblet Cells of the Broadgilled Hagfish Eptatretus cirrhatus (Forster, 1801): A Confocal Microscopy Evaluation

Abstract

The fish intestine operates as a complicated interface between the organism and the environment, providing biological and mechanical protections as a result of a viscous layer of mucus released by goblet cells, which serves as a barrier against bacteria, viruses, and other pathogens, and contributes to the functions of the immune system. Therefore, goblet cells have a role in preserving the health of the body by secreting mucus and acting as sentinels. The ancient jawless fish broadgilled hagfish (Eptatretus cirrhatus, Forster, 1801) has a very basic digestive system because it lacks a stomach. By examining the presence, localization, and co-localization of 5-HT, TLR2, iNOS, and Piscidin1, this study intends to provide insight into the potential immune system contributions arranged by the gut goblet cells of broadgilled hagfish. Our results characterize intestinal goblet cells of broadgilled hagfish, for the first time, with the former antibodies, suggesting the hypothesis of conservation of the roles played by these cells also in primitive vertebrates. Moreover, this study deepens the knowledge about the still little-known immune system of hagfish.

Confocal Identification of Immune Molecules in Skin Club Cells of Zebrafish (Danio rerio, Hamilton 1882) and Their Possible Role in Immunity

“…The 5-HT expression, as already reported by Zaccone et al [ 22 ], can be associated with an immune function, since this neurotransmitter is a powerful immunomodulator involved in several biological processes, such as the stimulation of mucus production by the goblet cells of mucous membranes [ 42 ]. Further modulating social responses to stressors in fish [ 43 , 44 ], 5-HT is involved in immune mechanisms [ 45 ], regulating the inflammatory response, recruiting immune cells, and stimulating the production of cytokines [ 46 ].…”

Mucus secretions in Cnidarian, an ecological, adaptive and evolutive tool

“…Indeed, mucus is involved in several biological processes essential for almost all aquatic metazoan acting as the first contact stratum with surrounding media from Cnidaria to Chordata (Stabili et al, 2015;Alesci et al, 2022). The mucus layers provide a multifunctional and protective hydrogel interface between the organisms' epithelial cells and the external environment (Cabillon and Lazado, 2019;Kramar et al, 2019).…”

“…It is a key feature of the innate immune system in most aquatic and terrestrial metazoic phyla, playing a vital role in the prevention of microbial disease. In addition, while acting as a protective barrier, mucus allows the exchange of oxygen, carbon dioxide and nutrients and metabolites, lubricating the surfaces, reducing damage due to lesions, reducing dehydration of the epithelia and providing the polymer matrix which allows the transport of ciliary mucus particles (Reverter et al, 2018;Alesci et al, 2022). The properties of the secreted mucus generally depend on its composition consisting of exudates, such lipids, and mucins, polymeric glycoproteins that give the mucus its ability to gel, both released by mucocytes of the epithelium (Brown and Bythell, 2005).…”

Effects of chlorogenic acid on growth, metabolism, antioxidation, immunity, and intestinal flora of crucian carp (Carassius auratus)

“…The increase of intestinal villus height and density can cause the extension of the contact area with nutrients and promote nutrient absorption. The mucus layer formed by glycoproteins secreted by goblet cells and immune molecules (such as antimicrobial peptides and cytokines) is the first line of defense against the invasion of pathogenic substances ( Alesci et al, 2022 ). As shown in Figures 4A,B , intestinal villi were leaf-like.…”