Epoxyeicosatrienoic Acid administration or Soluble Epoxide Hydrolase inhibition attenuates renal fibrogenesis in obstructive nephropathy

Epoxyeicosatrienoic acids (EETs) are arachidonic acid metabolites with biological effects, including anti-apoptotic, anti-inflammatory, and anti-fibrotic functions. Soluble epoxide hydrolase (sEH)-mediated hydrolysis of EETs to dihydroxyeicosatrienoic acids (DHET) attenuates these effects. Recent studies have demonstrated inhibition of sEH prevents renal tubulointerstitial fibrosis and inflammation in chronic kidney disease (CKD) model. Given the pathophysiological role of the EET pathway in CKD, we investigated if administration of EETs regioisomers and/or sEH inhibition will promote anti-fibrotic and reno-protective effects in renal fibrosis following UUO. EETs administration abolished tubulointerstitial fibrogenesis, as demonstrated by reduced fibroblast activation and collagen deposition after UUO. Inflammatory response was prevented as demonstrated by decreased neutrophil and macrophage infiltration and expression of cytokines in EETs-administered UUO kidneys. EETs administration and/or sEH inhibition significantly reduced M1 macrophage markers while M2 macrophage markers were highly upregulated. Furthermore, UUO-induced oxidative stress, tubular injury, and apoptosis were all downregulated following EETs administration. Combined EETs administration and sEH inhibition however, had no additive effect in attenuating inflammation and renal interstitial fibrogenesis after UUO. Taken together, our findings provide a mechanistic understanding of how EETs prevent kidney fibrogenesis during obstructive nephropathy, and suggest EETs treatment as a potential therapeutic strategy to treat fibrotic diseases.