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.