COMBINED FARNESOID X RECEPTOR AGONIST AND SOLUBLE EPOXIDE HYDROLASE INHIBITOR TREATS PROGRESSIVE RENAL FIBROSIS

Abstract

Renal fibrosis plays a critical role in the progression of chronic kidney disease (CKD) to end‐stage renal disease (ESRD) and is considered an independent predictor for clinical outcomes. Unfortunately, there has been little success in developing anti‐fibrotic therapies that can slow the progression of CKD to ESRD. We investigated the efficacy of a dual‐acting molecule, FXRA/sEHi, in arresting renal fibrosis progression using a unilateral ureteral obstruction (UUO) renal fibrosis model. FXRA/sEHi acts simultaneously as farnesoid X receptor agonist and a soluble epoxide hydrolase inhibitor. C57BL/6J male mice went through either UUO or sham surgery (n=8/group). Mice were treated with either FXRA/sEHi (10mg/kg/d) or vehicle given in drinking water. Interventional FXRA/sEHi treatment was started 3 days after UUO induction and continued for 7 days. Plasma and kidney tissue were collected at the end of the experimental period. Biochemical, histopathological, immunohistopathological, and gene expression studies were carried out to determine the antifibrotic actions for FXRA/sEHi. The UUO group exhibited elevated BUN compared to the sham group (77±10 vs. 44±15 mg/dL) and FXRA/sEHi treatment reduced BUN by 40%. UUO mice demonstrated marked renal fibrosis with higher kidney hydroxyproline content (267±46 vs. 53±14 μg/mg protein) and collagen positive area (4.3±0.1% vs. 0.7±0.3%) compared to sham. UUO mice demonstrated renal inflammation with elevated kidney MCP‐1, renal CD45 positive immune cell infiltration, and renal profibrotic gene expression (TNF‐a, IL‐6, IL‐1b). Interventional FXRA/sEHi treatment reduced renal inflammation in UUO mice. Renal fibrosis in UUO was associated with epithelial‐to‐mesenchymal transition (EMT) as UUO mice exhibited a 2 to 20‐fold higher protein and gene expression of mesenchymal markers a‐SMA, FSP‐1, and FN, as well as a marked decrease in the epithelial marker, E‐cadherin compared to the sham group. UUO mice treated with FXRA/sEHi had markedly reduced EMT. UUO mice also had tubular epithelial barrier injury with increased renal KIM‐1, NGAL expression and lower claudin‐1 and claudin‐3 expression compared to sham. FXRA/sEHi treatment reduced tubular injury markers by 25–50% and maintained tubular epithelial integrity by restoring claudin expressions in UUO mice. Vascular inflammation was evident in UUO mice with 9 to 20‐fold higher ICAM and VCAM gene expression compared to sham that was reduced by 40–50% with FXRA/sEHi treatment. Peritubular vascular density assessed by CD31 expression was reduced by 35% in UUO mice and FXRA/sEHi mitigated vascular loss. Overall, these findings demonstrate that FXRA/sEHi is a promising dual‐acting antifibrotic agent that arrests the progression of epithelial and vascular renal fibrotic pathological events.