MMP9 and diabetic kidney disease: Further research indicated that the therapeutic effects of TSF in DKD may be attributed, at least partially, to its anti-inflammatory action by downregulating tumor necrosis factor alpha and upregulating pro-inflammatory cytokine interleukin-10 expression, as well as its antifibrotic action by inhibiting the expression of transforming growth factor beta 1 (TGF-β1), enhancing the expression of matrix metallopeptidase 9 (MMP-9), and reducing the expression of collagen type IV (42, 43).