PDCD1LG2 and clostridium difficile infection: In this study, the CDI signature was negatively associated with the ICB treatment key target genes(i.e. PDCD1 and CD200), and the expression level of some ICB-related genes ( i.e. PDCD1LG2,CD86, CD48, CD40, and IDO1) elevated significantly with an increase of the CDI risk score.