CSPG4 Mediates Inflammatory, Cell Death, and Senescence Responses in Enteric Glia Exposed to Clostridioides difficile Toxins

Clostridioides difficile infection (CDI) is a persistent public health problem worldwide. C. difficile toxins A (TcdA) and B (TcdB) can affect enteric glial cells, an important component of the enteric nervous system. Here, we aimed to identify the profile of C. difficile toxin receptors expressed by enteric glia and investigate the contribution of the chondroitin sulfate proteoglycan receptors (CSPG4) in mediating inflammatory response, cell death, and senescence in enteric glia exposed to TcdA or TcdB. We found that human, mouse, and rat enteric glia express all of the previously recognized C. difficile toxin receptors. However, in vitro, C. difficile toxins significantly increased CSPG4 expression in enteric glia. In vivo, CDI also increased CSPG4 expression in colonic and cecal tissues. Blockage of CSPG4 significantly decreased IL-6 and S100B gene expression, as well as reduced the nuclear translocation of NFκB and STAT3 in enteric glia exposed to TcdB, but not TcdA. Interestingly, blockade of CSPG4 also decreased senescence-associated beta-galactosidase (SA-β-galactosidase) activity and other senescence markers (γH2AX, p16 and p21) in enteric glia exposed to TcdA or TcdB. However, CSPG4 blockade reduced cell death promoted by TcdA, but not TcdB. Taken together, these findings show that enteric glia, by expressing all known C. difficile toxin receptors, can respond directly to TcdA or TcdB. However, CSPG4 seems to play an important role in cell death and inflammatory response promoted by TcdA and TcdB, respectively, as well as senescence induced by both toxins.