RESUMO
BACKGROUND: Glomerular fibrosis is the common end result of glomerulonephritis (GN) regardless of etiology. In our rat model for anti-glomerular basement membrane GN, severe fibrosis follows glomerular inflammation. We investigated the association between expression of extracellular matrix (ECM) proteins and progression of glomerular fibrosis. METHODS: Expression of ECM genes in glomeruli was determined at RNA and protein levels. Immunofluorescence was applied to identify cell sources for the molecules. RESULTS: DNA microarray for ECM genes, quantitative RT-PCR and Western blot revealed significant upregulation of osteopontin (OPN), a multifunctional molecule, in the glomeruli only after onset of glomerular fibrosis. Two-dimensional electrophoresis showed that the expressed OPN was in three major isoforms. Immunofluorescence showed that fibrotic tissues in glomeruli accumulated massive deposits of extracellular OPN. Both in vivo and in vitro experiments showed that a novel population of multinucleated α-smooth muscle actin(+)CD90(-) myofibroblast-like cells, which surrounded fibrotic tissue, was the main source of OPN during progression of fibrosis. Since senescence-associated ß-galactosidase activity was detected in those cells both in vitro and in vivo, these cells probably were terminally differentiated senescent myofibroblasts. CONCLUSION: OPN has been implicated in fibrosis in several organs. Our results suggest potential roles of OPN and its main source, the senescent myofibroblasts, in glomerular fibrosis.
Assuntos
Doença Antimembrana Basal Glomerular/metabolismo , Doença Antimembrana Basal Glomerular/patologia , Glomérulos Renais/metabolismo , Glomérulos Renais/patologia , Osteopontina/metabolismo , Animais , Modelos Animais de Doenças , Feminino , Fibrose , Expressão Gênica , Osteopontina/genética , Ratos , Ratos Endogâmicos WKY , Regulação para Cima/genéticaRESUMO
BACKGROUND: Involvement of Th2 T cells/NFkappaB in minimal change disease (MCD) has been postulated. A promising but unconfirmed glomerular permeability factor (GPF) from MCD T cells has been described. We explored whether GPF was the consequence of Th2 cell activation. METHODS: Peripheral blood leukocytes (PBL) from 16 MCD patients and 7 normal controls were analyzed and the results were statistically compared. RESULTS: Flow cytometry demonstrated a significant expansion of CD4+ T cell population and dramatically increased CD69+ cells among CD4+ T cells in MCD, suggesting coincident activation of T cells with onset of the disease. RT-PCR on RNA from either freshly isolated PBL or post in vitroactivation showed high-level expression of the Th2 cytokine interleukin-4 in all MCD patients. Importantly, both antibody microarray assay on sera and RT-PCR on mRNA of PBL revealed expression of a CXC chemokine GRO-gamma (growth-related oncogene) in all MCD patients as compared with one of 7 controls. CONCLUSIONS: Our results reveal an association between onset of MCD and activation of Th2 cells. The GRO family has been implicated in the function of endothelial cells, and its expression is under NFkappaB regulation. Thus, GRO-gamma is a promising candidate for Th2-associated GPF in MCD.
Assuntos
Quimiocinas CXC/metabolismo , Ativação Linfocitária/fisiologia , Nefrose Lipoide/imunologia , Células Th2/fisiologia , Antígenos CD/metabolismo , Antígenos de Diferenciação de Linfócitos T/metabolismo , Antígenos CD4/metabolismo , Contagem de Linfócito CD4 , Estudos de Casos e Controles , Criança , Pré-Escolar , Citocinas/metabolismo , Feminino , Expressão Gênica , Membrana Basal Glomerular/metabolismo , Humanos , Lectinas Tipo C , Masculino , Permeabilidade , Células Th2/metabolismoAssuntos
Injúria Renal Aguda/etiologia , Necrose Tubular Aguda/etiologia , Rim/patologia , Lipectomia/efeitos adversos , Mieloma Múltiplo/diagnóstico , Injúria Renal Aguda/patologia , Injúria Renal Aguda/terapia , Biópsia por Agulha , Feminino , Seguimentos , Humanos , Imuno-Histoquímica , Testes de Função Renal , Necrose Tubular Aguda/patologia , Necrose Tubular Aguda/terapia , Lipectomia/métodos , Pessoa de Meia-Idade , Diálise Renal/métodos , Medição de Risco , Índice de Gravidade de DoençaRESUMO
The anti-glomerular basement membrane (GBM) Ab has been regarded as a prototypical example of pathogenic autoantibodies. However, the mechanism for elicitation of this Ab remains unknown. In the present paper, we report that the Ab to diverse GBM Ags was induced by a single nephritogenic T cell epitope in a rat model. The T cell epitope pCol(28-40) of noncollagen domain 1 of collagen type IV alpha3 chain not only uniformly induced severe glomerulonephritis but also elicited anti-GBM Ab in 76% of the immunized rats after prominent glomerular injury. Furthermore, we demonstrated that the anti-GBM Ab was not related to the peptidic B cell epitope nested in pCol(28-40); that is, 1) elimination of the B cell epitope, either by substitution of the critical residues of the B cell epitope or by truncation, failed to abrogate anti-GBM Ab production, and 2) the anti-GBM Ab, eluted from the diseased kidneys, reacted only with native GBM, but not with pCol(28-40). Confocal microscopy and immunoprecipitation further demonstrated that the eluted anti-GBM Ab recognized conformational B cell epitope(s) of multiple native GBM proteins. We conclude that autoantibody response to diverse native GBM Ags was induced by a single nephritogenic T cell epitope. Thus, anti-GBM Ab may actually be a consequence of T cell-mediated glomerulonephritis.
Assuntos
Autoanticorpos/biossíntese , Autoantígenos/imunologia , Colágeno Tipo IV/imunologia , Epitopos de Linfócito T/imunologia , Glomérulos Renais/imunologia , Transferência Adotiva , Animais , Doença Antimembrana Basal Glomerular/imunologia , Especificidade de Anticorpos , Autoantígenos/administração & dosagem , Membrana Basal/imunologia , Membrana Basal/metabolismo , Sítios de Ligação de Anticorpos , Colágeno Tipo IV/administração & dosagem , Epitopos de Linfócito B/metabolismo , Epitopos de Linfócito T/administração & dosagem , Feminino , Imunoglobulina G/metabolismo , Glomérulos Renais/metabolismo , Fragmentos de Peptídeos/imunologia , Estrutura Terciária de Proteína , Ratos , Ratos Endogâmicos WKY , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/transplanteRESUMO
Glomerular diseases show diverse epidemiological characteristics throughout the world, which has been suggested to be caused by differences in genetics of the underlying populations or environmental exposure to the putative antigens or agents that either trigger or induce the disease. Recently, an alteration in immune balance of the T helper 1 (T(H)1) and T helper 2 (T(H)2) subsets has been implicated as a mechanism to explain the relative increase in allergic diseases in industrialized nations. According to the Hygiene Hypothesis, overcrowding and poor hygiene early in life may protect from atopic diseases because exposure to microbes predisposes in favor of a T(H)1-dominant response. Conversely, dominance of the T(H)2 subset would be responsible for the increasing incidence of allergies. We present the hypothesis that this imbalance may help explain the predilection for membranoproliferative glomerulonephritis (GN) and mesangial proliferative GN to be associated with developing and/or poor nations, whereas immunoglobulin A nephropathy and minimal change disease are observed more commonly in industrialized nations. The implication of the Hygiene Hypothesis is that clinical expression of immune-mediated renal disease would depend on the prevailing T(H)1/T(H)2 balance, rather than the etiologic agent, and it may help explain the epidemiological pattern of glomerular diseases worldwide.