Future directions in the treatment of IgA nephropathy

Abstract

In IgA nephropathy (IgAN), there is a defect of clearance of immune complexes. Some of these patients ate genetically predisposed to the development of the nephritis. Poorly solubilized polymeric IgA immune complexes are then deposited in the mesangium. Recent data indirectly suggest IgA-immune complexes from patients with IgAN are different from those of healthy subjects and they can exert pathophysiologic effect on target cells. Mesangial reactivity to the immune complexes triggers off release of cytokines, with decreased prostaglandin E2 synthesis and increase in thromboxane A2 production promoting mesangial cell proliferation. Angiotensin II (ATII)-induced mesangial cell contraction with efferent arteriolar vasodilatation initiates glomerular injury and may eventually lead to glomerulosclerosis due to increased synthesis of transforming growth factor- β (TGF-β) and platelet-derived growth factor PDGF). This paper highlights the possible therapeutic strategies in the future based on the recently reported pathogenetic findings in IgAN. These strategies include: (i) decreasing the synthesis of IgA-immune complexes; (ii) limiting the mesangial uptake of IgA-immune complexes; (iii) antagonizing the effect of PDGF and TGF-β to reduce mesangial proliferation and glomerulosclerosis; and (iv) reducing the noxious glomerular injury due to infiltrating neutrophils. The effective treatment of IgAN requires a further clarification of the pathogenesis of the nephropathy. Future therapeutic attempts to slow down the rate of renal deterioration in IgAN rest on the better understanding of the mechanisms mediating inflammatory injury in the kidney.