Jin-Kui Yang1, Ying-Ying Wang2, Chang Liu2, Ting-Ting Shi2, Jing Lu2, Xi Cao2, Fang-Yuan Yang2, Jian-Ping Feng2, Chen Chen3, Li-Nong Ji4, Aimin Xu5. 1. Beijing Key Laboratory of Diabetes Research and Care, Department of Endocrinology, Beijing Tongren Hospital, Capital Medical University, Beijing, China jkyang@ccmu.edu.cn. 2. Beijing Key Laboratory of Diabetes Research and Care, Department of Endocrinology, Beijing Tongren Hospital, Capital Medical University, Beijing, China. 3. School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia. 4. Endocrinology and Metabolism Department, Peking University People's Hospital, Beijing, China. 5. State Key Laboratory of Pharmaceutical Biotechnology, Department of Medicine, University of Hong Kong, Hong Kong.
Abstract
OBJECTIVE: The predictive value of microalbuminuria (MAU) for kidney damage is limited in type 2 diabetes (T2D). We studied whether a urine proteome specific for sight-threatening proliferative diabetic retinopathy (PDR) is an indicator to predict chronic renal insufficiency (CRI) in patients with T2D. RESEARCH DESIGN AND METHODS: A shotgun urine proteomic analysis was performed in patients with MAU and PDR (case subjects) and in patients with MAU and a duration of T2D for >10 years but without any degree of retinopathy (control subjects). In the cohort study, 210 patients with T2D with an estimated glomerular filtration rate (eGFR) ≥80 mL/min/1.73 m2 were followed for a median of 5.3 years. Urine proteins specific for PDR were used for predicting CRI (eGFR <60 mL/min/1.73 m2). RESULTS: The top two urine proteins with the highest difference in ratio of case subjects to control subjects were haptoglobin (8.7 times; P < 0.0001) and α-2-macroglobulin (5.7 times; P < 0.0001). In the cohort study, patients with baseline urinary haptoglobin ≥20 ng/min (haptoglobinuria) had a higher incidence of CRI than those without (hazard ratio [95% CI] 3.27 [1.41-7.58]; P = 0.006). The overall CRI rate was 3.2% for patients without haptoglobinuria or MAU, 9.5% for those with MAU, and 13.3% for those with haptoglobinuria. The highest rate for CRI (22.4%) was in patients with both MAU and haptoglobinuria (P < 0.001). CONCLUSIONS: Urine haptoglobin, which is specific for PDR, is a novel biomarker and complement to urine albumin for predicting kidney damage in patients with T2D.
OBJECTIVE: The predictive value of microalbuminuria (MAU) for kidney damage is limited in type 2 diabetes (T2D). We studied whether a urine proteome specific for sight-threatening proliferative diabetic retinopathy (PDR) is an indicator to predict chronic renal insufficiency (CRI) in patients with T2D. RESEARCH DESIGN AND METHODS: A shotgun urine proteomic analysis was performed in patients with MAU and PDR (case subjects) and in patients with MAU and a duration of T2D for >10 years but without any degree of retinopathy (control subjects). In the cohort study, 210 patients with T2D with an estimated glomerular filtration rate (eGFR) ≥80 mL/min/1.73 m2 were followed for a median of 5.3 years. Urine proteins specific for PDR were used for predicting CRI (eGFR <60 mL/min/1.73 m2). RESULTS: The top two urine proteins with the highest difference in ratio of case subjects to control subjects were haptoglobin (8.7 times; P < 0.0001) and α-2-macroglobulin (5.7 times; P < 0.0001). In the cohort study, patients with baseline urinary haptoglobin ≥20 ng/min (haptoglobinuria) had a higher incidence of CRI than those without (hazard ratio [95% CI] 3.27 [1.41-7.58]; P = 0.006). The overall CRI rate was 3.2% for patients without haptoglobinuria or MAU, 9.5% for those with MAU, and 13.3% for those with haptoglobinuria. The highest rate for CRI (22.4%) was in patients with both MAU and haptoglobinuria (P < 0.001). CONCLUSIONS: Urine haptoglobin, which is specific for PDR, is a novel biomarker and complement to urine albumin for predicting kidney damage in patients with T2D.