A Low Concentration of Butyrate has a Protective Action Against the Deleterious Effects of Clostridioides difficile Toxins on Enteric Glia

Abstract

Microbiota, which plays a vital role in susceptibility to Clostridioides difficile infection (CDI), synthesizes butyrate. Enteric glia is a component of the enteric nervous system (ENS) and is affected by C. difficile toxins A (TcdA) and B (TcdB). Here, we evaluated whether butyrate modulates the response of enteric glia to C. difficile toxins. In vitro, rat enteric glia were incubated with TcdA or TcdB alone, or in combination with butyrate 1 h before the toxin challenge. After 18 h incubation, enteric glia were collected to analyze cell death and expression of Bcl2 (an antiapoptotic factor), S100B, and IL-6 by qPCR. C. difficile toxins induced enteric glia death, increased levels of caspase 3/7, downregulated Bcl2, and upregulated the expression of pro-inflammatory mediators (S100B and IL-6). In high concentration, butyrate (200 µM) potentialized the effects of C. difficile toxins in promoting enteric glia death and caspase 3/7 activity. In contrast, a low butyrate concentration (0.2 µM) decreased enteric glia death and caspase 3/7 activity induced by C. difficile toxins. In addition, a low concentration of butyrate (0.2 µM) upregulated Bcl2 expression compared to control cells and decreased the downregulation of Bcl2 and upregulation of IL-6 induced by TcdB. Further, a low butyrate concentration (0.2 µM) also diminished S100B upregulation induced by TcdA. Our findings suggest that low and high concentrations of butyrate can differentially affect the susceptibility of enteric glia to C. difficile toxins. These findings bring new perspectives on how microbiota-derived products may modulate the response of enteric glia to C. difficile toxins.