PSXII-6 - Effect of caffeic acid supplementation on growth performance, inflammatory response, antioxidant capacity, and intestinal barrier function in LPS-challenged piglets

Abstract: During weaning, piglets are prone to intestinal injury due to low immune function and intestinal function hypoplasia, which ultimately affect normal growth. Caffeic acid (CA), a kind of natural plant polyphenol, enhances intestinal health with the potential for a therapeutic effect on intestinal diseases. However, there is limited information about whether CA can improve the intestinal injury and growth performance in piglets. Here, a 28-day study was conducted to investigate the protective effect of CA against intestinal injury induced by intraperitoneal injection of Escherichia coli lipopolysaccharide (LPS) in a piglet model. A total of 18 piglets (7.36 ± 0.34 kg BW) were randomly assigned into 3 groups: the control group (CON) and LPS-challenged group (LPS) were fed with the basal diet, and CA+LPS group (CAL) was fed with the basal diet supplemented with 500 mg/kg CA. On the 21st and 28th day of the experiment, piglets in the LPS and CAL groups were administrated with LPS (80 μg/kg BW), while piglets in the CON group were administrated with the same volume of normal saline. Three hours after administration on the 28th day, all piglets were slaughtered, and samples of blood and colon were collected. The results showed that CA supplementation increased the average daily gain (ADG) of piglets by about 80 g before the LPS challenge, and restored the LPS-induced decline in ADG of piglets by 50% on days 21 to 28. In serum, CA supplementation significantly decreased the level of pro-inflammatory cytokines including interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, and increased the levels of IL-10 (P < 0.05). Meanwhile, the antioxidative enzyme activities of total antioxidant capacity (T-AOC), catalase (CAT), and glutathione peroxidase (GSH-Px) were increased, while the level of H₂O₂ was decreased (P < 0.05). In colon tissue, qPCR results showed that CA supplementation significantly down-regulated the mRNA expression of IL-1β and IL-6 (P < 0.05), and up-regulated the mRNA expression of IL-10, NAD(P)H Quinone Dehydrogenase 1 (NQO1), SOD1, and GPX2 (P < 0.05), which indicated that CA treatment enhanced the antioxidant capacity and anti-inflammatory response in piglets. In addition, CA supplementation also enhanced intestinal mucosal barrier function, as indicated by the improvement of intestinal morphology and integrity, and increased the expression of tight junction proteins including ZO-1 and Claudin-1 in LPS-challenged piglets (P < 0.05). Taken together, these results indicate that CA supplementation could effectively alleviate LPS-induced intestinal injury by improving antioxidant capacity, anti-inflammatory response, and intestinal barrier function, thus improving the growth performance of piglets.