Steroid therapy reduces mesangial matrix accumulation in advanced IgA nephropathy

Background. Steroid therapy for IgA nephropathy (IgAN) has been reported to ameliorate the long-term prognosis of IgAN, but its mode of action has not been fully elucidated. In this study, we examined the effect of steroids on glomerular morphological changes in IgAN. Methods. We examined 16 patients with biopsy-proven IgAN (male/female = 11/5, mean age 32.1 years) who were divided into prognosis groups according to criteria set by the Japanese Society of Nephrology. Initially, they received a loading dose of steroids, followed by a daily dose of 10-15 mg prednisolone. After 12 months, they underwent a second biopsy, and their histological and clinical features were examined. Results. Before and after therapy, systolic blood pressure, diastolic blood pressure, serum creatinine and creatinine clearance all remained unchanged. However, urinary protein excretion decreased dramatically, from 1.6 +/- 1.7 to 0.4 +/- 0.2 g/day (P < 0.005). Furthermore, computerized imaging revealed a significant reduction of the mesangial matrix index (MMI) from 14.5 +/- 5.2 to 9.5 +/- 3.6% (P < 0.001). The numbers of sclerosing glomeruli did not change. Conclusions. Steroid therapy reduces mesangial matrix accumulation and reduces urinary protein excretion in advanced IgAN.