Chitosan Oligosaccharide Reduces Intestinal Inflammation That Involves Calcium-Sensing Receptor (CaSR) Activation in Lipopolysaccharide (LPS)-Challenged Piglets

Chitosan oligosaccharide (COS) is a degradation product of chitosan with antioxidative, anti-inflammatory, and antibacterial effects. This study was conducted to investigate the effects of dietary COS on the intestinal inflammatory response and the calcium-sensing receptor (CaSR) and nuclear transcription factor kappa B (NF-κB) signaling pathways that may be involved using a lipopolysaccharide (LPS)-challenged piglet model. A total of 40 weaned piglets were used in a 2 × 2 factorial design; the main factors were dietary treatment (basal or 300 μg/kg COS) and inflammatory challenge (LPS or saline). On the morning of days 14 and 21 after the initiation of treatment, the piglets were injected intraperitoneally with Escherichia coli LPS at 60 and 80 μg/kg body weight or the same amount of sterilized saline, respectively. Blood and small intestine samples were collected on day 14 or 21, respectively. The results showed that piglets challenged with LPS have a significant decrease in average daily gain and gain:feed and histopathological injury in the jejunum and ileum, whereas dietary supplementation with COS significantly alleviated intestinal injury induced by LPS. Piglets fed the COS diet had lower serum concentrations of tumor necrosis factor alpha (TNF-α), interleukin (IL) 6, and IL-8 as well as lower intestinal abundances of pro-inflammatory cytokine mRNA but higher anti-inflammatory cytokine mRNA compared with piglets fed the basal diet among LPS-challenged piglets (p < 0.05). Dietary COS increased intestinal CaSR and PLCβ2 protein expressions in both saline- and LPS-treated piglets, but decreased p-NF-κB p65, IKKα/β, and IκB protein expressions in LPS-challenged piglets (p < 0.05). These findings indicate that COS has the potential to reduce the intestinal inflammatory response, which is concomitant with the activation of CaSR and the inhibition of NF-κB signaling pathways under an inflammatory stimulus.