PSVI-24 Carnitine and polyunsaturated fatty acids alter cytokine expression in poly (I:C) infected porcine enteroids.

Abstract Carnitine and polyunsaturated fatty acids such as arachidonic acid (ARA) and docosahexaenoic acid (DHA) may have preventive and therapeutic values in animals suffering from intestinal inflammation due to their anti-inflammatory properties. Intestinal inflammation is one of the most critical factors limiting production efficiency in animal husbandry. Environmental stress and pathogenic infections are the leading causes of intestinal inflammation. To reduce stresses and resist infections, the abandonment of antibiotics has attracted widespread attention to the application of anti-inflammatory substances in feed. Thus, understanding the role of carnitine, ARA and DHA in regulating the intestinal immune system and inflammation are warranted. The objective of this study was to assess the effect of prophylactic treatment of enteroids with carnitine or ARA and DHA on expression of cytokines induced by polyinosinic-polycytidylic acid (Poly (I:C)), a synthetic analog of double-stranded RNA (which can induce the pattern recognition receptor associated with viral infections; TLR3). The assessments were performed in enteroids isolated from the ileum of neonatal piglets. The enteroids, after expansion in vitro, first were incubated in the presence or absence of carnitine (1 mM), ARA (1 µM) or DHA (1 µM), and then treated with or without poly (I:C) (10 µg/mL) after 24 h. Cytokines expression was examined using RT-PCR after 72 h. Carnitine effects on genes associated with barrier function (OCLN and ZO-1) and carnitine transport (OCTN2) were evaluated also. Addition of carnitine increased IL6, ILβ and OCLN expression (p < 0.05) or tended to increase OCTN2 expression (p < 0.1). Infection by poly (I:C) increased TNFα, IL6 and TLR3 expression, and decreased ILβ, ZO-1 and OCTN2 expression or tended to decrease OCLN expression, but no interaction was detected between carnitine and poly(I:C) infection. Pre-incubation with ARA increased IL6 and TLR3 expression or tended to increase TNFα expression. Pre-incubation with DHA increased IL6 expression or tended to increase TLR3 expression but had no impact on TNFα expression. Again, infection by poly (I:C) increased TNFα, IL6 and TLR3 expression, but the increases were influenced by ARA and DHA. Expression of IL6 and TLR3 were on average 1.2-fold higher in enteroids treated with ARA or DHA. In conclusion, carnitine may improve intestinal tight junctions and carnitine transport. Carnitine, ARA and DHA may promote proliferation of intestinal epithelial cells, reduce susceptibility to viral infection and strengthen immune responses via modifying cytokine expression. Future work should confirm whether changes in expression translate into altered biologic function. Supported by Animal Health and Production and Animal Products (grant no. 2023-67015-39663/1030033) from the USDA National Institute of Food and Agriculture, and by the North Carolina Agricultural Research Hatch projects 1016618 and 02780.