Extrarenal cytokines modulate the glomerular response to IgA immune complexes.
الكلمات الدالة
نبذة مختصرة
Clinical episodes of IgA nephropathy coincide recurrently with microbial infections. Cytokines produced during such infections may play a role in the pathogenesis of IgA-associated glomerulonephritis. To test this hypothesis, we examined the influence of passively administered proinflammatory cytokines (IL-1, IFN-gamma and IL-6) on the development of glomerulonephritis in an experimental model of IgA nephropathy. Glomerular IgA immune deposits were induced in mice by administration of IgA anti-phosphorylcholine (PC) with either a PC-containing carbohydrate antigen of Pneumococcal C polysaccharide (PnC) or a protein antigen of PC-conjugated bovine serum albumin (PC-BSA). The effect of IL-1 on the IgA-PC-BSA induced glomerular changes resulted in an increase of mesangial hypercellularity that was associated with mild proteinuria and hematuria. Mice treated with IL-1 and IgA-PnC developed diffuse proliferative glomerulonephritis with proteinuria and hematuria. In contrast, IL-6 treatment with IgA-PC-BSA of IgA-PnC failed to exert any significant renal effect. The combination of IL-6 and IL-1, however, intensified the mesangial hypercellularity of the IgA-PC-BSA, and induced severe proliferative glomerulonephritis with inflammatory monocytes and neutrophils infiltrates in the IgA-PnC treated mice. These glomerular changes were also accompanied by increased proteinuria and hematuria. Similarly, the combination of IFN with IL-1 produced histologic changes and compromised renal function more than IFN or IL-1 exerted independently. These results suggest that extrarenal cytokines influence the renal response to IgA immune deposits. We also conclude that a synergy of multiple cytokines and nephritogenic antigens immobilized in glomerular IgA immune deposits may lead to rapid progression of IgA-associated glomerulonephritis.