OBJECTIVEIdiopathic nephrotic syndrome (INS) is a common glomerular disease. The pathogenesis of the disease remains unclear. Recent studies indicate that transforming growth factor beta (TGF beta) is the main cytokine involved in glomerular disease. It plays an important role in the development of INS and in occurrence of glomerulosclerosis. The present study aimed to study changes and significance of TGF beta in children with idiopathic nephrotic syndrome (INS).

METHODSTotally 35 cases with INS (13 males, 22 females) were studied. The age of onset was between 2 years and 1 months and 14 years with an average of 8 years and 3 months. The active stage group had 35 cases and the remission stage groups had 25 cases. The cases in active stage group had first onset of the disease with obvious clinical symptoms and abnormal laboratory findings without use of corticosteroids. The cases in remission stage group were asymptomatic without abnormal laboratory findings. Protein in urine was negative over 4 weeks after oral administration of prednisone for 8 weeks. Twenty five cases were steroid responsive and 10 cases were steroid non-responsive among the 35 cases. Thirty healthy young children were enrolled as control. TGF beta was detected by ELISA in peripheral blood mononuclear cell (PBMC) culture medium. The TGF beta mRNA gene expression was measured by in situ PCR in PBMC.

RESULTS(1) Concentration of TGF beta(247 +/- 26) ng/L and TGF beta mRNA expression (0.57 +/- 0.18) in active stage of simple type or nephritis type INS were higher than those of remission stage and control (P < 0.01). Concentration of TGF beta[(125 +/- 16) ng/L] and TGF beta mRNA expression (0.30 +/- 0.12) in remission stage were higher than that of control (P < 0.05). (2) The level of TGF beta protein in nephritis type [(275 +/- 26) ng/L] was significantly higher than that in simple type [(220 +/- 18) ng/L] in active stage INS (t = 6.45, P < 0.01). No significant difference in TGF beta mRNA expression was found between the nephritis type (0.58 +/- 0.15) and simple type (0.55 +/- 0.16) in active stage INS, either (P > 0.05). But these two types were different from the control (P < 0.01). (3) Concentration of TGF beta and TGF beta mRNA expression after therapy was clearly lower than that before therapy in steroid responsive group (P < 0.01). Whereas no significant change was seen in steroid non-responsive group. Both indicators were higher in steroid non-responsive group than in steroid responsive group whether before or after therapy.

CONCLUSIONTGF beta may play an important role in the mechanism of INS and its level in PBMC can be used as an immunological indicator for the illness state, therefore, determination of TGF beta level and mRNA may be of some clinical significance.