The profibrotic effects of MK-8617 on tubulointerstitial fibrosis mediated by the KLF5 regulating pathway.

The discovery of hypoxia-inducible factor (HIF)-prolyl hydroxylase inhibitor (PHI) has revolutionized the treatment strategy for renal anemia. However, the presence of multiple transcription targets of HIF raises safety concerns regarding HIF-PHI. Here, we explored the dose-dependent effect of MK-8617 (MK), a kind of HIF-PHI, on renal fibrosis. MK was administered by oral gavage to mice for 12 wk at doses of 1.5, 5, and 12.5 mg/kg. In vitro, the human proximal tubule epithelial cell line HK-2 was treated with increasing doses of MK administration. Transcriptome profiling was performed, and fibrogenesis was evaluated. The dose-dependent biphasic effects of MK on tubulointerstitial fibrosis (TIF) were observed in chronic kidney disease mice. Accordingly, high-dose MK treatment could significantly enhance TIF. Using RNA-sequencing, combined with in vivo and in vitro experiments, we found that Kriippel-like factor 5 (KLF5) expression level was significantly increased in the proximal tubular cells, which could be transcriptionally regulated by HIF-la with high-dose MK treatment but not low-dose MK. Furthermore, our study clarified that HIF-1 alpha-KLF5-TGF-beta 1 signaling activation is the potential mechanism of high-dose MK-induced TIF, as knockdown of KLF5 reduced TIF in vivo. Collectively, our study demonstrates that high-dose MK treatment initiates TIF by activating HIF-1 alpha-KLF5-TGF-beta 1 signaling. These findings provide novel insights into TIF induction by high-dose MK (HIF-PHI), suggesting that the safety dosage window needs to be emphasized in future clinical applications.