MMP1 and systemic sclerosis: In addition, CXCL17 is an antibacterial mucosal chemokine, which can not only exert antibacterial activity through a peptide-mediated way to disrupt bacterial membrane, but also reduce the expression of type I collagen by upregulating the expression of matrix metalloproteinase 1 (MMP1) and miR-29 in fibroblasts, thus participating in the occurrence of systemic sclerosis (SSc) [20,21].