SMAD7 and renal fibrosis: Meanwhile, it has been demonstrated that collagen expression is directly correlated with miR-17-5p expression but in renal fibrosis and HSC-T6 cell lines (Yu et al., 2015; Fu et al., 2021), which is consistent with our results, since the regression of the pro-fibrotic miR-17-5p and progression of the anti-fibrotic Smad-7 relative expressions have been manifested in the piperine-treated group.