Increased IL-12 and decreased IL-33 serum levels are associated with increased Th1 and suppressed Th2 cytokine profile in patients with diabetic nephropathy (CURES-134)

The role played by recently discovered novel cytokine IL-33 in controlling T-helper (Th)1 and Th2 cytokines under conditions of diabetic nephropathy (DN) is less well studied. In the present study, we estimated the levels of IL-33 along with both Th1 and Th2 cytokines in the serum of normal glucose tolerant (NGT), diabetic subjects with (DN) or without nephropathy (DM) and correlated it with the clinical risk factors of diabetes and nephropathy. 222 study subjects were recruited from the Chennai Urban Rural Epidemiology Study (CURES): 61 NGT, 79 DM and 82 DN. IL-33 level was estimated by ELISA while other Th1 (IL-12, IFN-gamma and IL-2) and Th2 (IL-4, IL-5 and IL-13) cytokines were measured using a Bio-plex bead assay. DM subjects showed a mixed Th1-Th2 profile (increased IFN-g, IL-12, IL-4 and IL-13 and decreased IL-33) while DN subjects showed enhanced Th1 profile (increased IFN-g, IL-2 and IL-12) with suppression of Th2 cytokine (decreased IL-33 and IL-13). The IL-33 levels showed a serial decline with increasing severity of insulin resistance and microalbuminuria. DN was associated with enhanced Th1 response and suppression of Th2 responses which might be due to inreased levels of IL-12 and decreased levels of IL-33 cytokines respectively.