PSLBII-26 Butyrate receptor gene expression in myeloid cells of the lower porcine gastrointestinal tract

Abstract Butyrate is a microbial-produced metabolite associated with increased barrier integrity, enhanced mucosal immunity, and modulation of immune cell function. Butyrate driven immunomodulation occurs through a variety of mechanisms, including signaling via cell surface G protein-coupled receptors. Myeloid lineage cells serve as one of the first lines of defense during infection. Foodborne pathogens, such as Salmonella, will circumvent host defenses by invading and then persisting within myeloid cells. Despite studies investigating changes in Salmonella infection when butyrate production is increased in the intestinal tract, the effect of butyrate on myeloid lineage cell function in the pig gastrointestinal tract is minimally characterized. A first step to understanding the ability of butyrate to modulate porcine intestinal myeloid-lineage cell function is to characterize butyrate receptor distribution within myeloid cells in the pig intestine. In situ hybridization (RNAScope) on formalin-fixed, paraffin-embedded tissues was utilized to determine mRNA expression patterns of butyrate receptors FFAR2, FFAR3, and HCAR2 in 10-wk-old pigs. FFAR2, FFAR3, and HCAR2 were expressed in pig ileum, cecum, and colon under basal conditions. Co-detection of protein and mRNA targets by immunofluorescence using confocal microscopy was utilized to investigate whether butyrate receptor genes were expressed in intestinal myeloid cells. Protein target IBA-1 and mRNA target SIRPA were used as markers for myeloid cells along with co-detection of FFAR2, FFAR3, or HCAR2. A subset of the myeloid cells in pig ileum, cecum, and colon expressed FFAR2, FFAR3, or HCAR2 under basal conditions. Further investigation is warranted to identify butyrate receptor expression on myeloid cells during infection, particularly cells infected with Salmonella. Identifying immune cells expressing butyrate receptors lends itself to improved utilization of butyrate to modulate porcine intestinal immune status.