Up-regulation of urinary markers predict outcome in IgA nephropathy but their predictive value is influenced by treatment with steroids and azathioprine.

OBJECTIVE: Steroids and immunosuppressants can delay progression of renal function in IgAN, but their possible effect in local cytokines has not been studied.
MATERIAL AND METHODS: Histology in 53 IgAN patients (M/F 35/18 age 40.5 years (17 - 65)) was evaluated using the Oxford classification system. IL-1β, -2, -4, -5, -6, -10, -12 and -17, INF-γ and MCP-1 were measured subsequently by multiplex cytokine assay in first morning urine samples taken at the day of renal biopsy. After a 6-month course with RAASinhibitors + fish oils (FO), 35/53 patients, Group A, responded and continued on the same treatment, while in 18/53 who did not respond, Group B, steroids + azathiopine were added.
RESULTS: The presence of endocapillary proliferation had significant correlation with the urinary excretion of pro-inflammatory and pro-fibrotic cytokines (IL-1β, MCP-1, IL-17, INF-γ, IL-6 and IL-10). Serum creatinine at time of diagnosis had significant correlation with proteinuria (p = 0.02), urinary levels of IL-1β (p = 0.03), IL-2 (p = 0.01) and MCP-1 (p = 0.03). GFR was reduced from 65 ± 29 to 57 ± 34 ml/min, p = 0.005 in Group A and remained stable in Group B patients (GFR from 63 ± 24 to 61 ± 30 ml/min, p = NS). Most of the measured cytokines in the urine predicted deterioration of renal function in Group A, but the urinary excretion of IL-6 seemed to predict renal function outcome in both groups of patients.
CONCLUSION: Several cytokines are excreted in the urine of patients with IgAN, and their levels predict the outcome of the disease. Steroids + aza may exert their beneficial effect through suppression of the production or activation of most cytokines.