Cannabinoid-2 receptor activation ameliorates hepatorenal syndrome.

Study Rationale: Hepatorenal syndrome (HRS) is a life-threatening complication of end-stage liver disease characterized by the rapid decline of kidney function. Herein, we explored the therapeutic potential of targeting the cannabinoid-2 receptor (CB-R) utilizing a commonly used mouse model of liver fibrosis and hepatorenal syndrome (HRS), induced by bile duct ligation (BDL).

Methods: Gene expression analysis, histological evaluation, determination of serum levels of renal injury-biomarkers were used to characterize the BDL-induced organ injury; laser speckle analysis to measure microcirculation in the kidneys.

Key Results: We found that liver injury triggered marked inflammation and oxidative stress in the kidneys of BDL-operated mice. We detected pronounced histopathological alterations with tubular injury paralleled with increased inflammation, oxidative/nitrative stress and fibrotic remodeling both in hepatic and renal tissues as well as endothelial activation and markedly impaired renal microcirculation. This was accompanied by increased CB-R expression in both the liver and the kidney tissues of diseased animals. A selective CB-R agonist, HU-910, markedly decreased numerous markers of inflammation, oxidative stress and fibrosis both in the liver and in the kidneys. HU-910 also attenuated markers of kidney injury and improved the impaired renal microcirculation in BDL-operated mice.

Conclusions: Our results suggest that oxidative stress, inflammation and microvascular dysfunction are key events in the pathogenesis of BDL-associated renal failure. Furthermore, we demonstrate that targeting the CB-R by selective agonists may represent a promising new avenue to treat HRS by attenuating tissue and vascular inflammation, oxidative stress, fibrosis and consequent microcirculatory dysfunction in the kidneys.