Concentrations of secreted protein acidic and rich in cysteine in serum and urine and its expression in kidney tissues of patients with IgA nephropathy / 第二军医大学学报

ABSTRACT

Objective: To investigate the concentrations of secreted protein acidic and rich in cysteine(SPARC) in the serum and urine of patients with IgA nephropathy and its expression in the kidney tissues. Methods: The concentrations of SPARC, tumor necrosis factor-a (TNF-a),interleukin 1β (IL-1β), and interleukin 6 (IL-6) in the serum and urine were measured with enzyme-linked immunosorbent assay(ELISA). The contents of SPARC protein in the culture medium of human mesangial cell (HMC) and human renal tubular epithelial cell (HKC), which had been treated with IL-6, were determined by ELISA. The expression and distribution of SPARC in IgA nephropathy and normal kidney tissues were observed by immunohistochemistry assay. Results: The concentrations of SPARC in serum and urine of IgA nephropathy patients were higher than those of the normal control subjects ([2.43±±1.22] μg/ml vs [0.69±0.21] 2μg/ml, [7.73±2.81] μg/ml vs [1.17±1.03]ρg/ml, P<0.01). The serum levels of TNF-α, IL-1β and IL-6 in IgA nephropathy group were significantly higher than those in the control group (P< 0.05); the urinary levels of TNF-α and IL-6 in IgA nephropathy group were also higher than those in the controls (P<0.01). SPARC protein secreted by HKC was higher than that by HMC (P<0.01). SPARC was weakly positive in normal distal cortical tubules. SPARC protein expression in tubular epithelial cells of IgA nephropathy patients was obviously higher than that of the normal controls. Conclusion: The secretion of SPARC by renal tubular epithelial cells is increased in patients with IgA nephropathy, which results in elevation of serum SPARC and may have a protective feedback inhibitory effect on HMC proliferation.