Ying Zhou1,2, Bingning Dong1, Kang Ho Kim1, Sungwoo Choi1,3, Zhen Sun1, Nan Wu1,4, Yifan Wu5, Jessica Scott1,2, David D Moore1,2,3. 1. Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX. 2. Integrative Molecular and Biomedical Sciences Graduate Program, Baylor College of Medicine, Houston, TX. 3. Program in Development Biology, Baylor College of Medicine, Houston, TX. 4. Texas Children's Hospital, Houston, TX. 5. Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX.
Abstract
BACKGROUND AND AIMS: Hepatic endoplasmic reticulum (ER) stress, whether triggered by intrinsic or extrinsic factors, can be resolved by the unfolded protein response (UPR). Sustained UPR activation leads to cell death and inflammatory response and contributes to liver disease progression. Hepatic tissue macrophages are key players in orchestrating liver inflammation, and ER stress can enhance macrophage activation. However, it is not well defined how the interplay between ER stress and inflammation is regulated during hepatic stress response. APPROACH AND RESULTS: Here we demonstrate that vitamin D receptor (VDR) activation mitigates hepatic ER stress response, whereas VDR knockout mice undergo persistent UPR activation and apoptosis in response to chemical ER stress inducer. Moreover, VDR deficiency promotes hepatic macrophage infiltration and increases gene expression and systematic levels of proinflammatory cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor α. VDR expression is induced in hepatic macrophages by ER stress, and VDR plays a dual regulatory role in macrophages by protecting against ER stress and promoting anti-inflammatory polarization. Co-culture with VDR-activated bone marrow-derived macrophages suppresses UPR target genes in primary hepatocytes treated with ER stress inducers. Thus, the immunomodulatory functions of VDR in macrophages are critical in hepatic ER stress resolution in mice. CONCLUSIONS: VDR signaling in macrophages regulates a shift between proinflammatory and anti-inflammatory activation during ER stress-induced inflammation to promote hepatic ER stress resolution.
BACKGROUND AND AIMS: Hepatic endoplasmic reticulum (ER) stress, whether triggered by intrinsic or extrinsic factors, can be resolved by the unfolded protein response (UPR). Sustained UPR activation leads to cell death and inflammatory response and contributes to liver disease progression. Hepatic tissue macrophages are key players in orchestrating liver inflammation, and ER stress can enhance macrophage activation. However, it is not well defined how the interplay between ER stress and inflammation is regulated during hepatic stress response. APPROACH AND RESULTS: Here we demonstrate that vitamin D receptor (VDR) activation mitigates hepatic ER stress response, whereas VDR knockout mice undergo persistent UPR activation and apoptosis in response to chemical ER stress inducer. Moreover, VDR deficiency promotes hepatic macrophage infiltration and increases gene expression and systematic levels of proinflammatory cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor α. VDR expression is induced in hepatic macrophages by ER stress, and VDR plays a dual regulatory role in macrophages by protecting against ER stress and promoting anti-inflammatory polarization. Co-culture with VDR-activated bone marrow-derived macrophages suppresses UPR target genes in primary hepatocytes treated with ER stress inducers. Thus, the immunomodulatory functions of VDR in macrophages are critical in hepatic ER stress resolution in mice. CONCLUSIONS:VDR signaling in macrophages regulates a shift between proinflammatory and anti-inflammatory activation during ER stress-induced inflammation to promote hepatic ER stress resolution.
Authors: Amir Ajoolabady; Simin Liu; Daniel J Klionsky; Gregory Y H Lip; Jaakko Tuomilehto; Sina Kavalakatt; David M Pereira; Afshin Samali; Jun Ren Journal: Trends Pharmacol Sci Date: 2021-12-08 Impact factor: 14.819