Recognition of purified beta 1,3/1,6 glucan and molecular signalling in the intestine of Atlantic salmon

Abstract

Atlantic salmon was orally intubated with a highly purified β-glucan product (MacroGard®) to study the recognition of the molecule by the receptor genes, the regulation of the downstream signalling genes and global proteins, and the micromorphological changes in the intestine. The β-glucan receptor genes of Atlantic salmon, sclra, sclrb, sclrc and cr3, seem to recognize the molecule, and initiate the downstream ITAM-motif signalling, as evident from the significantly high mRNA levels of ksyk, mapkin2, il1b and mip2a levels. Among the altered proteins, the Apoa4 (involved in carbohydrate and lipid metabolism); Tagln, Actb (uptake of β-glucan); Psma2 (associated with substrate recognition); and Ckt (energy metabolismrelated) were the overexpressed ones. The underexpressed proteins included the Uk114, Rpl9, Ctsb and Lgal that are connected to proliferation, LPS-stimulation, Il1b and lactose recognition, respectively. Furthermore, the mRNA levels of igt and the number of immune cells in the distal intestine were found to increase upon β-glucan uptake by the fish. This study provides some clues on the mechanisms by which the β-glucan evokes response in Atlantic salmon, particularly at the intestinal level.

The effect of β‐1,3‐glucan derived from Euglena gracilis (Algamune™) on the innate immunological responses of Nile tilapia (Oreochromis niloticus L.)

“…Orally administrated β‐glucans can interact with the gut mucosal immune system, eliciting intestinal inflammation, hence increasing the mucosal immune responses (Kiron et al., ), and activity of leucocytes such as macrophage antigen‐presenting cells (APCs) and intraepithelial lymphocytes (Løkka & Koppang, ; Petit & Wiegertjes, ; Volman et al., ). The mechanisms of how dietary β‐glucan is uptaken by APCs have not been fully characterized for fish.…”

“…Orally administrated β-glucans can interact with the gut mucosal immune system, eliciting intestinal inflammation, hence increasing the mucosal immune responses (Kiron et al, 2015), and activity of leucocytes such as macrophage antigen-presenting cells (APCs) and…”

Beta-glucan enhances the response to SVCV infection in zebrafish

“…Oral administration in the fish diet is the most common way of supplementing β-glucans to fish. There are a number of reports examining the expression of immune response genes in salmon and other fish species where βglucan enriched diets increased the levels of transcripts of a number of key genes of both innate and adaptive immune response (Douxfils, 2017;Kiron, 2016;Pionnier, 2014;Rodríguez, 2009).…”

Response of the intestinal mucosal barrier of carp (Cyprinus carpio) to a bacterial challenge by Aeromonas hydrophila intubation after feeding with β‐1,3/1,6‐glucan

“…Bacterial richness in the gut, analysed by RT‐PCR‐DGGE, was higher 24 hr after intubation with BSK‐10 in MacroGard ® fed fish. It has been previously reported that the mucosal system can be influenced by dietary β‐glucans (Kiron et al., ; Marel et al., ). The expression of the mucin gene Muc5B was significantly increased in the skin of carp after feeding with β‐glucans (Marel et al., ), and higher numbers of goblet cells and immune cells were present in the distal intestine in Atlantic salmon after feeding of a MacroGard ® enriched diet (Kiron et al., ).…”

“…It has been previously reported that the mucosal system can be influenced by dietary b-glucans (Kiron et al, 2016;Marel et al, 2012). The expression of the mucin gene Muc5B was significantly increased in the skin of carp after feeding with b-glucans (Marel et al, 2012), and higher numbers of goblet cells and immune cells were present in the distal intestine in Atlantic salmon after feeding of a MacroGard â enriched diet (Kiron et al, 2016). Therefore, dietary b-glucans seem to influence not only the mucus secretion in the gut, but also in carp skin.…”