Abstract: ［Abstract］Objective〖HTSS〗To investigate the expression of zinc alpha 2 glycoprotein(ZAG) in kidney tissue and urine of patients who had diabetic nephropathy(DN) and to analyze its relationship with clinicopathological parameters.
〖HTH〗〖WTHZ〗Methods〖HTSS〗Eighty-nine patients with diabetic nephropathy diagnosed by renal biopsy were included in this study. The patients were divided into two groups according to the degree of tubulointerstitial injury: the mild/moderate tubulointerstitial injury DN group（57 cases）and the severe tubulointerstitial injury DN group（32 cases）. The distant renal tissues far away from the tumor tissue of patients with benign renal tumor were taken as control. The expression of ZAG， transforming growth factor-β(TGF-β) in kidney tissue was detected by immunohistochemistry and urine ZAG level was assessed by enzyme-linked immunosorbent assay. The correlation between ZAG expression and clinicopathological indexes was analyzed.
〖HTH〗〖WTHZ〗Results〖HTSS〗Compared with the control group, there was a significant increase of glycated hemoglobin A1c(HbA1c), body mass index（BMI）, cholesterol, systolic blood pressure（SBP）, diastolic blood pressure（DBP）, urine protein excretion, tubulointerstitial injury score, and the urine ZAG level in mild/morderate DN group and severe DN group, but estimated glomerular filtration rate(eGFR) and albumin were lower than those in the control group(P＜0.05). In the severe group , urine protein excretion, renal tubulointerstitial injury score and urine ZAG were higher and eGFR was lower than those in the mild/moderate group(P＜0.05). There was no significant difference in HbA1c, BMI, cholesterol, SBP, DBP and albumin between the mild/moderate and severe groups(P＞0.05). ZAG was obviously expressed in tubular epithelial cells and interstitium of the control group. The expression of ZAG decreased in the mild/moderate group and remarkably decreased in the severe group. The expression of ZAG in renal tubulointerstitium was positively correlated with eGFR and negatively correlated with 24-hour urinary protein, TGF-β expression and tubulointerstitial injury score(P＜0.05). Urine ZAG level was negatively correlated with eGFR and positively correlated with tubulointerstitial injury score（P＜0.05）.
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗The expression of ZAG in renal tubulointerstitium decreased and the level of urine ZAG increased in patients with diabetic nephropathy, which are correlated with tubulointerstitial damage. ZAG may be used as an index to evaluate the degree of renal interstitial fibrosis.

Key words: diabetic nephropathies； zinc-α2-glycoprotein, tubulointerstitium