Tadaatsu Imaizumi1, Ryo Hayakari1, Tomoh Matsumiya1, Hidemi Yoshida1, Kazushi Tsuruga2, Shojiro Watanabe2, Shogo Kawaguchi3, Hiroshi Tanaka1,4. 1. a Departments of Vascular Biology , Hirosaki University Graduate School of Medicine , Hirosaki , Japan. 2. b Department of Pediatrics , Hirosaki University Hospital , Hirosaki , Japan. 3. c Department of Gastroenterology and Hematology , Hirosaki University Graduate School of Medicine , Hirosaki , Japan. 4. d Department of School Health Science, Faculty of Education , Hirosaki University , Hirosaki , Japan.
Abstract
BACKGROUND: Chloroquine has been reported to protect against renal damage in lupus nephritis (LN); however, its detailed mechanism in glomerular inflammation remains unclear. Upregulation of the type-I interferon (IFN) system plays a pivotal role in LN pathogenesis, therefore, we examined whether chloroquine inhibits toll-like receptor 3 (TLR3)/IFN-β signaling in cultured normal human mesangial cells (MCs). METHODS: We examined chloroquine effect on the representative TLR3/IFN-β-signaling axis, TLR3/IFN-β/retinoic acid-inducible gene-I (RIG-I)/CCL5 in MCs treated with polyinosinic-polycytidylic acid (poly IC), a synthetic viral dsRNA analog and analyzed the expression of these molecules using reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA). Furthermore, we subjected MCs to RNA interference against NF-κB p65. RESULTS: Pretreatment of cells with chloroquine attenuated IFN-β, RIG-I and CCL5 expression and phosphorylation of STAT1 induced by poly IC, but not IFN-β-induced phosphorylation of STAT1 and RIG-I expression induced by IFN-β. Knockdown of p65 inhibited the poly IC-induced IFN-β expression, and chloroquine pretreatment decreased the nuclear poly IC-induced translocation of NF-κB p65 in MCs. CONCLUSION: These results suggest that chloroquine attenuates mesangial TLR3 signaling in the early phase of NF-κB activation. Considering that TLRs/type-I IFNs signaling is implicated in LN pathogenesis, our results may further support regional renoprotective effects of chloroquine in treating LN.
BACKGROUND:Chloroquine has been reported to protect against renal damage in lupus nephritis (LN); however, its detailed mechanism in glomerular inflammation remains unclear. Upregulation of the type-I interferon (IFN) system plays a pivotal role in LN pathogenesis, therefore, we examined whether chloroquine inhibits toll-like receptor 3 (TLR3)/IFN-β signaling in cultured normal human mesangial cells (MCs). METHODS: We examined chloroquine effect on the representative TLR3/IFN-β-signaling axis, TLR3/IFN-β/retinoic acid-inducible gene-I (RIG-I)/CCL5 in MCs treated with polyinosinic-polycytidylic acid (poly IC), a synthetic viral dsRNA analog and analyzed the expression of these molecules using reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA). Furthermore, we subjected MCs to RNA interference against NF-κB p65. RESULTS: Pretreatment of cells with chloroquine attenuated IFN-β, RIG-I and CCL5 expression and phosphorylation of STAT1 induced by poly IC, but not IFN-β-induced phosphorylation of STAT1 and RIG-I expression induced by IFN-β. Knockdown of p65 inhibited the poly IC-induced IFN-β expression, and chloroquine pretreatment decreased the nuclear poly IC-induced translocation of NF-κB p65 in MCs. CONCLUSION: These results suggest that chloroquine attenuates mesangial TLR3 signaling in the early phase of NF-κB activation. Considering that TLRs/type-I IFNs signaling is implicated in LN pathogenesis, our results may further support regional renoprotective effects of chloroquine in treating LN.