Abstract:

Objective To investigate the relationship between renal tubulointerstitial lesion (TIL) and insulin resistance in IgA nephropathy. Methods Forty-six patients with IgA nephropathy diagnosed by renal biopsy were involved (IgA nephropathy group), and another 10 patients with minimal change nephrotic syndrome were served as controls. The expression of WT1 of glomerular foot cells and transforming growth factor-β1(TGF-β1) of renal tubulointerstitium in renal tissue samples was detected by immunohistochemical staining, and TIL was classified by Katafuchi halfquantity criteria.The level of urinary β2-microglobulin was measured by radioimmunoassay. The insulin sensitivity index (ISI) was calculated according to the levels of fasting blood glucose and insulin. The correlation between ISI and TIL classification, expression of TGF-β1 in renal tubulointerstitium and level of urinary β2-microglobulin was analysed by Spearman rank correlation analysis. Results Compared with control group, ISI and expression of WT1 of glomerular foot cells of IgA nephropathy group were lower, and expression of TGF-β1 in renal tubulointerstitium was higher (P<0.01 for all). Correlation analysis revealed that ISI was negatively related to TIL classification and expression of TGF-β1 in renal tubulointerstitium, and was positively related to expression of WT1 of glomerular foot cells. Conclusion TIL is positively related to insulin resistance of IgA nephropathy, indicating that improving insulin resistance may postpone the progression of IgA nephropathy.

Key words: IgA nephropathy, insulin resistance, insulin sensitivity index, tubulointerstitial lesion