title: Glomerular expression of myxovirus resistance protein 1 in human mesangial cells: possible activation of innate immunity in the pathogenesis of lupus nephritis.
abstract: Since viral infections activate type I interferon (IFN) pathways and cause subsequent release of IFN-dependent proinflammatory chemokines and cytokines, the innate immune system plays an important role in the pathogenesis of lupus nephritis (LN). It has been reported that human myxovirus resistance protein 1 (Mx1), a type I IFN-dependent transcript, acts against a wide range of RNA viruses. Although the expression of Mx1 in biopsy specimens obtained from patients with dermatomyositis and cutaneous lupus has been described, the expression of Mx1 in human mesangial cells (MCs) has remained largely unknown. We treated normal human MCs in culture with polyinosinic-polycytidylic acid (poly IC), an authentic double-stranded RNA, and analyzed the expression of Mx1 by reverse transcription-polymerase chain reaction and western blotting. To elucidate the poly IC-signalling pathway, we subjected the cells to RNA interference against IFN-β. We also conducted an immunofluorescence study to examine mesangial Mx1 expression in biopsy specimens from patients with LN. Poly IC-induced Mx1 expression in MCs are shown both time- and dose-dependently, and RNA interference against IFN-β inhibited poly IC-induced Mx1 expression. Intense glomerular Mx1 expression was observed in biopsy specimens from patients with LN, whereas negative staining occurred in specimens from patients with IgA nephropathy or purpura nephritis. These preliminary observations support, at least in part, the theory of innate immune system activation in the pathogenesis of LN.
authors.affiliation: Department of Pediatrics, Hirosaki University Hospital, Hirosaki, Japan.
authors.forename: Shojiro
authors.initials: S
authors.lastname: Watanabe
authors.forename: Tadaatsu
authors.initials: T
authors.lastname: Imaizumi
authors.forename: Kazushi
authors.initials: K
authors.lastname: Tsuruga
authors.forename: Tomomi
authors.initials: T
authors.lastname: Aizawa
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ito
authors.forename: Tomoh
authors.initials: T
authors.lastname: Matsumiya
authors.forename: Hidemi
authors.initials: H
authors.lastname: Yoshida
authors.forename: Kensuke
authors.initials: K
authors.lastname: Joh
authors.forename: Etsuro
authors.initials: E
authors.lastname: Ito
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tanaka
mesh_terms: D002478:Cells, Cultured; D006801:Humans; D007113:Immunity, Innate; D008181:Lupus Nephritis / Q000209:etiology*; D050527:Mesangial Cells / Q000276:immunology* / Q000378:metabolism; D064547:Myxovirus Resistance Proteins / Q000032:analysis / Q000235:genetics*; D011070:Poly I-C / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis
chemical_list: C579071:MX1 protein, human; D064547:Myxovirus Resistance Proteins; D012333:RNA, Messenger; D011070:Poly I-C
keywords: human myxovirus resistance protein 1; interferon-β; lupus nephritis; mesangial cell