|BECKER, SAGE - Iowa State University
Submitted to: International Veterinary Immunology Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 9/11/2023
Publication Date: N/A
Technical Abstract: The short-chain fatty acid (SCFA) butyrate is a microbial-produced metabolite associated with enhanced mucosal immunity and increased barrier integrity. Butyrate functions through a variety of mechanisms, including signaling through cell surface G protein-coupled receptors. Despite many studies investigating the impact of SCFAs on pig health and production, the function of SCFA receptors and their role in the immunomodulatory activities of butyrate is minimally characterized in pigs. In particular, blood monocytes likely migrate into the intestine and differentiate in response to local cues, including butyrate and LPS. To identify whether SCFA receptors are present on porcine monocytes and the impact of butyrate on SCFA receptor expression by monocytes, porcine blood-derived monocytes were cultured with LPS +/- butyrate for 4h. Under basal conditions, SCFA receptors FFAR2, HCAR2, and FFAR3, which encode for GPR43, GPR109a, and GPR41, respectively, were all expressed by peripheral monocytes to varying degrees. HCAR2 had highest expression in monocytes when compared to FFAR2 and FFAR3. FFAR3 was minimally expressed, to the extent that it is almost non-detectable. Butyrate exposure did not alter FFAR3 gene expression but did increase expression of HCAR2 and FFAR2. Butyrate alone (1 mM) increased FFAR2 gene expression over monocytes exposed to LPS only. Additionally, co-stimulation of monocytes with LPS and butyrate (0.25 mM) slightly decreased HCAR2 gene expression compared to LPS alone; however, LPS with 1 mM butyrate increased HCAR2 gene expression when compared to LPS alone. Co-stimulation of low and high doses of butyrate with LPS increased FFAR2 gene expression compared to LPS alone. Overall, our data suggests butyrate can modulate peripheral blood monocyte SCFA receptor expression, and expression is further modulated by LPS exposure. Understanding how SCFA receptors are expressed and how butyrate affects SCFA receptor responses in peripheral blood monocytes is important for understanding how SCFAs modulate intestinal health in pigs.