A study of urinary tryptase expression in patients with diabetic nephropathy and its pathological significance / 医学研究生学报

ABSTRACT

Objective Increased renal mast cells have been found in significant correlation with clinicopathological features of diabetic nephropathy ( DN) .However, the exact pathological significance of mast cells still remained to be elucidated.As one of the most abundant serine proteases, tryptase is specifically expressed by mast cells.The study was to observe the expression of tryptase in the urine of patients with diabetic nephropathy and realize the pathological significance of urinary tryptase and renal mast cells in the development of diabetic nephropathy. Methods Urine samples from 103 patients with diabetic nephropathy who were hospitalized at the clinical unit of the nephrology centre of Jingling Hospital from January 2012 to June 2013 were collected.According to concentra-tion of urinary albumin excretion rate, the patients were conducted to early-stage DN group (microalbuminuria,n=10), middle-stage DN group (proteinuria stage, n=31) and end-stage DN group (renal insufficiency stage,n=62).Meanwhile, urine samples from 20 normal persons were taken as the normal control group.Tryptase level in each urine sample was measured by using an ELISA kit.The average tryptase levels were compared among different groups and the correlation between urinary tryptase level and clinical indices was analyzed. Results ①In most cases, tryptase was not detected in the urine samples from normal persons(0.7 ±1.4 ng/mg creati-nine).However, the urinary trypatse level increased significantly with the development of diabetic nephropathy (11.6 ±10.5 ng/mg creatinine for early stage, 29.7 ±19.2 ng/mg creatinine for middle stage, and 44.6 ±43.4 ng/mg creatinine for late stage group).②The urinary tryptase level was found in significant correlation with ser-um creatinine (r=0.325, P<0.01), serum cystatin C (r=0.391, P<0.01), serum urea nitrogen (r=0.27, P<0.01), 24 hour uri-nary protein (r=0.389, P<0.01), urine C3 (r=0.276, P<0.05), urine retinol-binding protein (r=0.365, P<0.01), urine lysozyme (r=0.461, P<0.01), urine N-acetyl-β-glucosaminidase level (r=0.568, P<0.01), urinary kidney injury molecule-1 (r=0.434, P<0.05) and interleukin-18 level (r=0.375, P<0.05).No significant correlation was found between urinary tryptase level and age, gender, fasting blood sugar, postprandial blood sugar, HbA1c, triglyceride, high density lipoprotein or low density lipo-protein. Conclusion Mast cells play an important role in the development of diabetic nephropathy and might be a novel and effective target for the treatment of DN.