Anti-inflammatory and anti-fibrotic effects of modafinil in nonalcoholic liver disease

Abstract

Small- and intermediate-conductance Ca2+-activated K+ channels, K(Ca)2.3 and K(Ca)3.1, are involved in cellular signaling processes associated with inflammation and fibrosis. K(Ca)2.3 and K(Ca)3.1 are upregulated by proinflammatory cytokines and profibmtic growth factors. Cyclic AMP, which downregulates K(Ca)2.3 and K(Ca)3.1, is elevated by modafinil in cells; accordingly, we investigated whether modafinil exerts anti-inflammatory and antifibrotic responses via K(Ca)2.3- and K(Ca)3.1-mediated pathways in high-fat diet (HFD)- or thioacetamide-induced liver disease models in mice. Modafinil was administered orally in the form of a racemate, (R)-isomer, or (S)-isomer. We also determined whether the treatment targeted the profibrotic activity of hepatic stellate cells using immortalized human hepatic stellate cells (LX-2 cells). Modafinil improved HFD- or thioacetamide-induced changes compared to the control, leading to a reduced inflammatory response, collagen deposition, and alpha-smooth muscle actin expression both in vivo and in vitro. However, modafinil did not relieve HFD-induced steatosis. There were no significant differences in the effects of the (R)- and (S)-isomers of modafinil. K ca 2.3 and K(Ca)3.1 were upregulated and catalase was downregulated in liver tissues from thioacetamide- or HFDinduced liver disease models or in TGF-beta-treated LX-2 cells. TGF-beta-induced upregulation of K(Ca)2.3, K(Ca)3.1, collagen, and a-smooth muscle actin and downregulation of catalase were reversed by modafinil, polyethylene glycol catalase, N-acetylcysteine, siRNA against K(Ca)2.3 or K(Ca)3.1, and Epac inhibitors. Our investigation revealed that modafinil attenuated inflammatory and fibrotic progression via K(Ca)2.3- and K(Ca)3.1-mediated pathways in nonalcoholic hepatitis, suggesting that inhibiting K(Ca)2.3- and K(Ca)3.1-mediated signaling may serve as a novel therapeutic approach for inflammatory and fibrotic liver diseases.