Segmental regulation of intestinal motility by colitis and the adaptive immune system in the mouse ileum and colon.

Gastrointestinal motility disturbances are a hallmark of inflammatory bowel disease (IBD); however, their mechanisms remain unclear. This study utilized a dextran sulfate sodium (DSS)-induced colitis mouse model, deficient in mature B and T lymphocytes, to assess intestinal motility and the role of the adaptive immune system in health and IBD. In healthy mice, the absence of adaptive lymphocytes reduced acetylcholine (ACh) sensitivity in the ileum. During colitis, it decreases motility by reducing the intensity and frequency of spontaneous contractions while increasing cholinergic responsiveness. In the proximal colon, adaptive immunity deficiency led to increased contractility and reduced ACh sensitivity in homeostasis, while colitis reduced contractile capacity. In the mid-colon, immune-deficient mice have reduced ACh sensitivity in homeostasis and exacerbated contractile responses during colitis. In the distal colon, adaptive immunity loss reduced contractility in health and cholinergic responsiveness during colitis. These motility alterations were associated with altered acetylcholinesterase and M2/M3 muscarinic receptor expression. Notably, adaptive lymphocyte deficiency resulted in reduced tissue damage and lower TNF-α expression in the colon during colitis paralleling intestinal motility changes. Overall, the adaptive immune system critically regulates motility and inflammation across different intestinal segments in IBD.