title: Glomerular clusterin is associated with PKC-alpha/beta regulation and good outcome of membranous glomerulonephritis in humans.
abstract: Mechanisms for human membranous glomerulonephritis (MGN) remain elusive. Most up-to-date concepts still rely on the rat model of Passive Heymann Nephritis that derives from an autoimmune response to glomerular megalin, with complement activation and membrane attack complex assembly. Clusterin has been reported as a megalin ligand in immunodeposits, although its role has not been clarified. We studied renal biopsies of 60 MGN patients by immunohistochemistry utilizing antibodies against clusterin, C5b-9, and phosphorylated-protien kinase C (PKC) isoforms (pPKC). In vitro experiments were performed to investigate the role of clusterin during podocyte damage by MGN serum and define clusterin binding to human podocytes, where megalin is known to be absent. Clusterin, C5b-9, and pPKC-alpha/beta showed highly variable glomerular staining, where high clusterin profiles were inversely correlated to C5b-9 and PKC-alpha/beta expression (P=0.029), and co-localized with the low-density lipoprotein receptor (LDL-R). Glomerular clusterin emerged as the single factor influencing proteinuria at multivariate analysis and was associated with a reduction of proteinuria after a follow-up of 1.5 years (-88.1%, P=0.027). Incubation of podocytes with MGN sera determined strong upregulation of pPKC-alpha/beta that was reverted by pre-incubation with clusterin, serum de-complementation, or protein-A treatment. Preliminary in vitro experiments showed podocyte binding of biotinilated clusterin, co-localization with LDL-R and specific binding inhibition with anti-LDL-R antibodies and with specific ligands. These data suggest a central role for glomerular clusterin in MGN as a modulator of inflammation that potentially influences the clinical outcome. Binding of clusterin to the LDL-R might offer an interpretative key for the pathogenesis of MGN in humans.
authors.affiliation: Renal Immunopathology Laboratory, Fondazione D'Amico per la Ricerca sulle Malattie Renali, Nuova Nefrologia Research Association, c/o San Carlo Borromeo Hospital, Milan, Italy.
authors.forename: M P
authors.initials: MP
authors.lastname: Rastaldi
authors.forename: G
authors.initials: G
authors.lastname: Candiano
authors.forename: L
authors.initials: L
authors.lastname: Musante
authors.forename: M
authors.initials: M
authors.lastname: Bruschi
authors.forename: S
authors.initials: S
authors.lastname: Armelloni
authors.forename: L
authors.initials: L
authors.lastname: Rimoldi
authors.forename: R
authors.initials: R
authors.lastname: Tardanico
authors.forename: S
authors.initials: S
authors.lastname: Sanna-Cherchi
authors.forename: S Sanna
authors.initials: SS
authors.lastname: Cherchi
authors.forename: F
authors.initials: F
authors.lastname: Ferrario
authors.forename: V
authors.initials: V
authors.lastname: Montinaro
authors.forename: R
authors.initials: R
authors.lastname: Haupt
authors.forename: S
authors.initials: S
authors.lastname: Parodi
authors.forename: M L
authors.initials: ML
authors.lastname: Carnevali
authors.forename: L
authors.initials: L
authors.lastname: Allegri
authors.forename: G
authors.initials: G
authors.lastname: Camussi
authors.forename: L
authors.initials: L
authors.lastname: Gesualdo
authors.forename: F
authors.initials: F
authors.lastname: Scolari
authors.forename: G M
authors.initials: GM
authors.lastname: Ghiggeri
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D001798:Blood Proteins / Q000494:pharmacology; D002478:Cells, Cultured; D051152:Clusterin / Q000378:metabolism*; D015938:Complement Membrane Attack Complex / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D015433:Glomerulonephritis, Membranous / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008297:Male; D010766:Phosphorylation; D050199:Podocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D011379:Prognosis; D011493:Protein Kinase C / Q000378:metabolism*; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha / Q000378:metabolism*; D011973:Receptors, LDL / Q000378:metabolism
chemical_list: D001798:Blood Proteins; D051152:Clusterin; D015938:Complement Membrane Attack Complex; D011973:Receptors, LDL; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha