Calcitriol Inhibits HCV Infection via Blockade of Activation of PPAR and Interference with Endoplasmic Reticulum-Associated Degradation

• Main Authors: Yu-Min Lin, Hung-Yu Sun, Wen-Tai Chiu, Hui-Chen Su, Yu-Chieh Chien, Lee-Won Chong, Hung-Chuen Chang, Chyi-Huey Bai, Kung-Chia Young, Chiung-Wen Tsao
• Format: Article
• Language: English
• Published: MDPI AG 2018-01-01
• Series: Viruses
• Subjects: calcitriol; hepatitis C virus infection; peroxisome proliferator-activated receptor; endoplasmic reticulum-associated degradation; nitrative stress
• Online Access: http://www.mdpi.com/1999-4915/10/2/57

Vitamin D has been identified as an innate anti-hepatitis C virus (HCV) agent but the possible mechanisms for this issue remain unclear. Here, we clarified the mechanisms of calcitriol-mediated inhibition of HCV infection. Calcitriol partially inhibited HCV infection, nitric oxide (NO) release and lipid accumulation in Huh7.5 human hepatoma cells via the activation of vitamin D receptor (VDR). When cells were pretreated with the activators of peroxisome proliferator-activated receptor (PPAR)-α (Wy14643) and -γ (Ly171883), the calcitriol-mediated HCV suppression was reversed. Otherwise, three individual stimulators of PPAR-α/β/γ blocked the activation of VDR. PPAR-β (linoleic acid) reversed the inhibition of NO release, whereas PPAR-γ (Ly171883) reversed the inhibitions of NO release and lipid accumulation in the presence of calcitriol. The calcitriol-mediated viral suppression, inhibition of NO release and activation of VDR were partially blocked by an inhibitor of endoplasmic reticulum-associated degradation (ERAD), kifunensine. Furthermore, calcitriol blocked the HCV-induced expressions of apolipoprotein J and 78 kDa glucose-regulated protein, which was restored by pretreatment of kifunensine. These results indicated that the calcitriol-mediated HCV suppression was associated with the activation of VDR, interference with ERAD process, as well as blockades of PPAR, lipid accumulation and nitrative stress.