CD1D and clostridium difficile infection: In addition to mediating colonization resistance, the gut microbiota also affects CDI by shaping iNKT cell functions, including immunoglobulin class switching by providing diverse antigens through CD1d presentation and releasing PAMPs, while iNKT cells, in turn, modulate microbial composition via cytokine secretion, which could potentially affect the occurrence of CDI (115, 116).