We conducted further studies to explore whether CXXC5 exerted antifibrotic effects through the negative regulation of CD40/CD40L and found that CD40 and CD40L were upregulated in the pulmonary fibrosis model both in vitro and in vivo, but CD40 and CD40L were downregulated after CXXC5 overexpression. This evidence concerns the gene CD40 and pulmonary fibrosis.