TcdB from Hypervirulent Clostridioides difficile Induces Neuronal Loss and Neurotransmitter Alterations in the Intrinsic Enteric Nervous System

Clostridioides difficile infection (CDI) is a predominant cause of intestinal infections. The intrinsic enteric nervous system (ENS) occupies the intestinal tissue in large numbers and intricately regulates various aspects of intestinal function. Nonetheless, the specific effects of CDI on the intrinsic ENS remain underexplored. Herein, we employed the TcdB variant (TcdB2) derived from hypervirulent C. difficile to elucidate the impact of CDI on neurons located in colonic wall. We found that TcdB2 directly induced dose-dependent cytopathic effects on enteric neurons both in vitro and in adult mice colons. Notably, an increased expression of choline acetyltransferase (ChAT) and neural nitric oxide synthase (nNOS) in colonic neurons prior to the onset of cytopathic changes following treatment with TcdB2 were observed, both in vivo and in vitro. These findings suggest that during CDI, TcdB not only causes neuronal loss but also alters the composition of neurotransmitters in the ENS.