Journal of Hainan Medical University 2017; 23(4): 69-73 69 Journal of Hainan Medical University http://www.hnykdxxb.com Evaluation of renal function and oxidative stress after adjuvant epalrestat of early diabetic nephropathy Ge Zhao 1, Min-Xiu Yao 2 1 Endocrinology Department, Qingdao University in Shandong Province, Qingdao City, Shandong Province, 266021 2 Endocrinology Department, Qingdao Central Hospital in Shandong Province, Qingdao City, Shandong Province, 266042 ARTICLE INFO Article history: Received 4 Nov 2016 Received in revised form 13 Nov 2016 Accepted 12 Nov 2016 Available online 24 Nov 2016 Keywords: Early diabetic nephropathy Epalrestat Renal function Oxidative stress ABSTRACT Objective: To explore the influence of adjuvant epalrestat of early diabetic nephropathy on renal function and oxidative stress. Methods: A total of 80 patients with early diabetic nephropathy who were treated in our hospital between January 2013 and February 2016 were collected and divided into observation group and control group according to singleblind parallel control. Control group of patients received routine therapy, and observation group of patients received adjuvant epalrestat on this basis. 8 weeks of, automatic biochemical analyzer was used to detect the renal function indexes of two groups of patients; RIA method was used to detect the serum renal fibrosis index levels; enzyme-linked immunosorbent assay (ELISA) was used to detect serum oxidative stress index levels. Results:, differences in serum renal function, renal fibrosis and oxidative stress index levels were not statistically significant between two groups of patients; after 8 weeks of, serum renal function indexes Scr, BUN, CysC and 毬 2-MG levels of observation group were lower than those of control group, renal fibrosis indexes CⅣ, CTGF and TGF- 毬 1 levels were lower than those of control group, oxidation indexes ROS, LHP and AOPPs levels were lower than those of control group, anti-oxidation indexes SOD, VitE, VitC and T-AOC levels were significantly higher than those of control group, and the differences were statistically significant. Conclusion: Adjuvant epalrestat therapy can optimize the renal function and reduce the systemic oxidative stress response in patients with early diabetic nephropathy. 1. Introduction Diabetic nephropathy (DN) is one of the most important complications in diabetic patients with poor control of blood glucose, there is complex metabolic disorder in such patients, and once it progresses to end-stage renal disease, the clinical will be very difficult[1]. Prevention or early of DN is the most reliable way to circumvent the end-stage renal diseases, and therefore, the of early diabetic nephropathy (EDN) has become the clinical research emphasis at present. EDN is the early stage of DN that is without severe renal dysfunction, the disease is reversible, and the reasonability of the choice of will directly decide outcome[2,3]. Epalrestat belongs to aldose reductase inhibitor, it reversibly inhibits the aldose reductase in the polyol metabolism process to reduce the production of sorbitol that affects nerve cell function, and it has been successfully applied in diabetic peripheral neuropathy[4]. At present, some scholars put forward that epalrestat can also optimize renal function and can be used as the adjuvant drug for EDN, but the relevant research reports are fewer. In the following study, the influence of adjuvant epalrestat of early diabetic nephropathy on renal function and oxidative stress was analyzed. Corresponding Author: Min-Xiu Yao, Endocrinology Department, Qingdao Central Hospital in Shandong Province, Qingdao City, Shandong Province, 266042. Tel: 13953232080 Fund Project: Medical Science and Technology Development Plan Project of Shandong Province No: 2014WS0137. 2. Information and methods 2.1 General information
70 A total of 80 patients with early diabetic nephropathy who were treated in our hospital between January 2013 and February 2016 were included and divided into observation group and control group (n=40) according to single-blind parallel control. Control group included 23 male cases and 17 female cases, they were 38-76 years old, the body weight was 49-87 kg and (59.73±7.55) kg in average, and the course of diabetes was 9-21 years and (13±2) years in average; observation group included 22 male cases and 18 female cases, they were 39-78 years old, the body weight was 48-85 kg and (57.69±7.81) kg in average, and the course of diabetes was 8-20 years and (12±2) years in average. The included patients signed the informed consent themselves, the research process was approved by the hospital ethics committee, and the differences in the distribution of gender, age and course of disease were not statistically significant (P>0.05). 2.2 Inclusion and exclusion criteria Inclusion criteria: (1) in accordance with the diagnostic criteria for EDN[5]; (2) 80 years old; (3) not receiving major surgery6 months prior to admission. Exclusion criteria: (1) with acute or chronic glomerulonephritis; (2) with severe heart, liver and kidney failure; (3) associated with systemic infectious diseases; (6) allergic to epalrestat; (7) pregnant or breastfeeding women. 2.3 Treatment methods Control group of patients received routine clinical EDN, including diet control, fitting exercise, insulin aspart (Novo Nordisk Pharmaceuticals Co., LTD., approved by S20133006) for glucose lowering, nifedipine (Shanghai Scond Pharmaceutical Co., LTD., approved by H20068147) for blood pressure lowering, and aspirin (Sichuan Pacific Pharmaceutical Co., LTD., approved by H51021475) for platelet lowering therapy. On the basis of conventional, the observation group received adjuvant epalrestat therapy as follows: oral administration of epalrestat tablets (Yangtze River Pharmaceutical Group Nanjing Hailing Pharmaceutical Co., LTD., approved by H20040012), 2.5 g/time, 3 times /d, for continuous 8 weeks. 2.4 Observation indexes 2.4.1 Renal function and renal fibrosis 2 ml of peripheral venous blood was extracted from two groups of patients at the same point in time immediately after admission and after 8 weeks of, the blood was centrifuged, the supernatant was obtained and cryopreserved in -40 refrigerator (Shanghai Siqi Scientific Instrument Co., LTD., the article number MDF-40V50) for testing, and the detection indexes were as follows: (1): renal function: automatic biochemical analyzer (Xuzhou Haoyu Science and Technology Development Co., LTD., model Senlo8008) was used to detect serum creatinine (Scr), blood urea nitrogen (BUN), cystatin C (CysC) and 毬 2 microglobulin ( 毬 2-MG) levels; (2) renal fibrosis: RIA kit (Sigma Company in the United States, the article number RA109) instructions were followed to detect serum renal fibrosis indexes collagen type Ⅳ (CⅣ), connective tissue growth factor (CTGF) and transforming growth factor 毬 1 (TGF- 毬 1) levels. 2.4.2 Oxidative stress The same method was used to obtain serum from two groups of patients immediately after admission and after8 weeks of, and then determine (1) oxidation indexes: reactive oxygen species (ROS), lipid hydrogen peroxide (LHP) and advanced oxidation protein products (AOPPs); (2) anti-oxidation indexes: superoxide dismutase (SOD), vitamin E (VitE), vitamin C (VitC) and total antioxidant capacity (T-AOC). 2.5 Statistical methods SPSS 15.0 software was used for statistical processing, measurement data was in terms of Mean ± SD, comparison within same group before and after was by paired t test, measurement data comparison between two groups was by t test, and P<0.05 indicated statistical significance in differences. 3. Results 3.1 Renal function Analysis of serum renal function indexes Scr (μmol/l), BUN (mmol/l), CysC (mg/l) and 毬 2-MG (μg/mmol) levels between two groups of patients was as follows: before, differences in Table 1. Comparison of serum renal function index levels. Scr BUN CysC β2-mg Groups n Observation 40 124.38±14.76 87.27±9.56 ab 15.48±1.92 6.54±0.71 ab 2.18±0.24 1.17±0.19 ab 3.92±0.42 2.24±0.28 ab Control 40 125.76±15.42 98.56±10.14 a 15.62±1.87 12.41±1.83 a 2.15±0.23 1.62±0.21 a 3.98±0.45 3.17±0.38 a t value 0.182 8.231 0.182 9.232 0.109 6.382 0.261 6.498 P value >0.05 <0.05 >0.05 >0.05 <0.05 <0.05 >0.05 <0.05 Note: compared with same group before, a P<0.05; compared with control group after, b P<0.05.
71 serum renal function indexes Scr, BUN, CysC and 毬 2-MG levels were not statistically significant between two groups of patients (P>0.05); after 8 weeks of, serum Scr, BUN, CysC and 毬 2-MG levels of both groups were significantly lower than those before, and the differences were statistically significant (P<0.05). 8 weeks of, serum Scr, BUN, CysC and 毬 2-MG levels of observation group were significantly lower than those of control group, and the differences were statistically significant (P<0.05), shown in Table 1., differences in serum oxidation indexes ROS, LHP and AOPPs levels were not statistically significant between two groups of patients (P>0.05); after 8 weeks of, serum ROS, LHP and AOPPs levels of both groups were significantly lower than those before, and the differences were statistically significant (P<0.05). 8 weeks of, serum ROS, LHP and AOPPs levels of observation group were significantly lower than those of control group, and the differences were statistically significant (P<0.05), shown in Table 3. 3.2 Renal fibrosis, differences in serum renal fibrosis indexes CⅣ, CTGF and TGF- 毬 1 levels were not statistically significant between two groups of patients (P>0.05); after 8 weeks of, serum CⅣ, CTGF and TGF- 毬 1 levels of both groups were significantly lower than those before, and the differences were statistically significant (P<0.05). 8 weeks of, serum CⅣ, CTGF and TGF- 毬 1 levels of observation group were significantly lower than those of control group, and the differences were statistically significant (P<0.05), shown in Table 2. 3.3 Oxidation indexes 3.4 Anti-oxidation indexes Comparison of serum anti-oxidation indexes SOD (μg/ml), VitE (μg/ml), VitC (μg/ml) and T-AOC (U/mL) levels between two groups of patients before and after was as follows: before, differences in serum anti-oxidation indexes SOD, VitE, VitC and T-AOC levels were not statistically significant between two groups of patients (P>0.05); after 8 weeks of, serum SOD, VitE, VitC and T-AOC levels of both groups were significantly higher than those before, and the differences were statistically significant (P<0.05). 8 weeks of, serum SOD, VitE, VitC and T-AOC levels of observation group were significantly higher than those of control group, and the differences were statistically significant (P<0.05), shown in Table 4. Table 2. Comparison of serum renal fibrosis index levels (μg/l). Groups n CⅣ CTGF TGF-β1 Observation 40 130.27±15.94 43.09±5.65 ab 19.72±2.09 9.65±0.94 ab 175.38±20.94 70.43±8.62 ab Control 40 131.85±14.38 91.48±9.52 a 19.64±2.31 15.83±1.94 a 176.95±21.27 143.07±18.76 a t value 0.217 9.283 0.198 8.263 0.152 11.283 P value >0.05 <0.05 >0.05 <0.05 >0.05 <0.05 Note: compared with same group before, a P<0.05; compared with control group after, b P<0.05. Table 3. Comparison of serum oxidation index levels (μmol/l). Groups n ROS LHP AOPPs Observation 40 893.27±95.84 384.52±42.64 ab 672.19±78.23 342.43±45.75 ab 7.82±0.89 2.34±0.35 ab Control 40 891.76±92.43 669.19±70.85 a 681.24±75.92 543.27±56.86 a 7.91±0.87 5.27±0.67 a t value 0.183 9.273 0.162 8.384 0.158 8.921 P value >0.05 <0.05 >0.05 <0.05 >0.05 <0.05 Note: compared with same group before, a P<0.05; compared with control group after, b P<0.05. Table 4. Comparison of serum anti-oxidation index levels. SOD VitE VitC T-AOC Groups n Observation 40 53.27±5.92 95.35±9.11 ab 5.09±0.53 8.16±0.89 ab 15.37±1.82 28.25±3.09 ab 19.82±2.74 30.32±3.88 ab Control 40 52.19±6.02 64.09±7.58 a 5.11±0.58 6.48±0.76 a 15.48±1.96 20.64±2.78 a 19.63±2.69 24.63±3.42 a t value 0.182 8.593 0.174 7.293 0.163 8.192 0.159 7.293 P value >0.05 <0.05 >0.05 >0.05 <0.05 <0.05 >0.05 <0.05 Note: compared with same group before, a P<0.05; compared with control group after, b P<0.05.
72 4. Discussion EDN is the early stage of DN, and positive intervention during this period can reverse the renal function damage and largely reduce and even avoid the disease progression to end-stage renal disease[6]. Diet control, glucose lowering, blood pressure control and so on are the common strategies for EDN, their effect on delaying disease progression is limited, and other targeted drugs are also required to expand the curative effect. Polyol metabolism plays an important role in both occurrence and development of DN, and epalrestat, as aldose reductase inhibitor, can block the polyol metabolism pathways and reduce the generation of advanced glycation end-products[7]. There are many studies about epalrestat of diabetic peripheral neuropathy, but there are fewer studies about its role in the EDN patients. In the study, epalrestat was used as auxiliary means and applied in the of patients with EDN in our hospital, and the effect of the drug on patients renal function and oxidative stress was expounded. Trace albuminuria is the main performance of the EDN, and along with the increase of the proteinuria levels, substantial renal damage will gradually appear in patients. glomerular filtration function damage, the metabolites accumulate in the body, Scr and BUN levels in the blood circulation increase, and the specific rising degree is consistent with renal damage[8,9]. It has been confirmed in many studies that CysC and 毬 2-MG are directly correlated with the renal impairment in patients, CysC is the metabolite of sulfur-containing amino acid, its content keeps dynamic balance under physiological state, and the CysC accumulation mostly means kidney damage; 毬 2-MG belongs to the macromolecular protein, and serum 毬 2-MG level may increase in the early glomerular filtration function injury[10,11]. In the study, serum levels of above renal functionrelated indexes were detected at first, and it was found that compared with the control group, observation group were with lower serum Scr, BUN, CysC and 毬 2-MG levels after, indicating that after adjuvant epalrestat therapy, the renal function in patients with END is significantly optimized, and confirming the positive effect of epalrestat on improving the renal function in patients with END. In addition to hypertension and urine proteinuria, renal fibrosis is also an important feature in patients with DN. In the condition of diabetes, the oxygen free radicals produced in kidney tissue can activate p38mapk signaling pathway, prompt the massive transcription and expression of fibrosis factors CⅣ and CTGF through TGF- 毬 1, and eventually make extracellular matrix excessively deposit and form renal fibrosis[12]. the formation of renal fibrosis, the TGF- 毬 1, CⅣ and CTGF in the tissue can be partially released into the circulating blood and be detected, so the high serum expression of TGF- 毬 1, CⅣ and CTGF is a reliable sign of renal fibrosis[13]. It was found in the study that compared with control group, observation group were with lower serum TGF- 毬 1, CⅣ and CTGF levels after, indicating that the adjuvant epalrestat therapy reduces the degree of renal fibrosis in patients with EDN. Under high glucose state, the polyol metabolism increases from 5% of the baseline value to about 30%, active polyols metabolism is a precipitating factor of renal fibrosis, and the above anti-fibrosis effect of epalrestat may be realized by inhibiting polyols. Many studies have confirmed that oxidative stress is an important factor of the occurrence and development of DN, and the mitochondrial respiratory chain induced by high glucose causes excessive ROS, which directly damage the kidney tissue and lead to renal inflammation and fibrosis[14,15]. Oxidation/anti-oxidation imbalance is the core factor that leads to sustained kidney damage progression and end-stage renal disease, ROS, LHP, AOPPs and other oxidation products are massively produced under high glucose condition, and they inhibit the protective effect of antioxidants SOD, VitE, VitC and T-AOC on the body, further attack the kidney tissue cells and cause the aggravation of kidney dysfunction[16]. Detecting oxidation/anti-oxidation index levels in patients with EDN can accurately assess the damage of kidney tissue, and it is also a reliable way to judge the effect of adjuvant epalrestat therapy[17]. It was found in the study that compared with control group, observation group were with lower serum oxidation indexes ROS, LHP and AOPPs levels, and higher anti-oxidation indexes SOD, VitE, VitC and T-AOC levels after, showing that adjuvant epalrestat therapy can effectively reduce the systemic oxidative stress in patients with EDN, and this is also one of the fundamental mechanisms for it to protect renal function. To sum up, it is concluded as follows: adjuvant epalrestat therapy can optimize the renal function and reduce the systemic oxidative stress response in patients with early diabetic nephropathy, and it s worth popularization and application in clinical practice in the future. References [1] XU Yu-mei, JIN Gui-lan, ZHENG Jun. Epalrestat Tablets combined with orka capsule of 60 cases of diabetic nephropathy. Herald Med 2014; 33(11): 1453-1456. [2] Halfon M, Rotman S, Egli M, Venetz JP, Pascual M. Continuous subcutaneous insulin pump associated with absence of recurrent kidney allograft diabetic nephropathy. Acta diabetologica 2015; 52(6): 1175-1177. [3] SU Xiu-hai, LV Shu-quan, ZHANG Shu-fang, LI Shu-lin, YU Wen-xia, GUO Rui-qing, et al. Clinical observation of Sanhuangyishen capsule combined with epalrestat of early diabetic nephropathy. J Basic Chin Med 2015; 21(9): 1169-1172. [4] Hu J, Yang S, Wang Y, Goswami R, Peng C, Gao R, et al. Serum bisphenol A and progression of type 2 diabetic nephropathy: a 6-year prospective study. Acta diabetologica 2015; 52(6): 1135-1141.
73 [5] Zhao Ling-jun, Liu Yu-feng, Wu Lin-lin, Liu Shu-jun. Clinical application research of the latest international pathological diagnostic criteria for diabetic nephropathy. Chin J Lab Diagn 2014; 18(5): 847-850. [6] Patel L, Thaker A. The effects of adenosine A2B receptor inhibition on VEGF and nitric oxide axis-mediated renal function in diabetic nephropathy. Renal Failure 2014; 36(6): 916-924. [7] Zhiqing W, Jing W, Haili X, Shaozhuang L, Chunxiao H, Haifeng H, et al. Renal function is ameliorated in a diabetic nephropathy rat model through a duodenal-jejunal bypass. Diabetes Res Clin Pract 2014; 103(1): 26-34. [8] Lu Q, Zuo WZ, Ji XJ, Zhou YX, Liu YQ, Yao XQ, et al. Ethanolic Ginkgo biloba leaf extract prevents renal fibrosis through Akt/mTOR signaling in diabetic nephropathy. Phytomedicine 2015; 22(12): 1071-1078. [9] Ding Ling, Hu Yi, Yuan Ye. The influence of Atorvastatin on blood lipid, inflammatory factors and renal function in patients with early diabetic nephropathy. China Pharm 2015; 26(15): 2035-2038. [10] Peng De-zhi, Kong Li, Li Han-yu. Effects of alprostadil on renal function and serum inflammatory factors of patients with early diabetic nephropathy. J Hainan Med Univ 2015; 21(2): 209-212. [11] He Fang, Zhang Xiao, Chen He-jun, Li Jie, He Shi-xue. Systemic evaluation on effect of ginkgo biloba extract on microalbuminuria and renal function in patients with diabetic nephropathy. Chin J Exp Tradit Med Formulae 2016; 22(3): 206-209. [12] He F, Peng F, Xia X, Zhao C, Luo Q, Guan W, et al. MiR-135a promotes renal fibrosis in diabetic nephropathy by regulating TRPC1. Diabetologia 2014; 57(8): 1726-1736. [13] Jia Hui-yu, Li Zhong-nan, Chen Guang-liang. Effect of transforming growth factor beta 1/Sma-and Mad-related protein signal pathway in diabetic nephropathy and related drugs:a review. Chin J Pharmacol Toxicol 2016; 30(3): 266-269. [14] Dabhi B, Mistry KN. Oxidative stress and its association with TNFα-308 G/C and IL-1α-889 C/T gene polymorphisms in patients with diabetes and diabetic nephropathy. Gene 2015; 562(2): 197-202. [15] Man-hua ZUO, Jun TANG. Evaluation of elderly diabetic nephropathy patients' serum oxidative stress, angiogenesis targets and peripheral blood T cells contents during different stages. China J Modern Med 2015; 25(31): 74-78. [16] Guo Fu-tuan, Xu Xiong-wei, Pan Jian-feng, Lin Pei-li, Zheng Ni. The anti-oxidative effect of Ramulus mori polysaccharides on diabetic nephropathy mice. Chin Pharmacol Bull 2016; 32(8): 1148-1152. [17] Hsu YC, Lee PH, Lei CC, Ho C, Shih YH, Lin CL. Nitric oxide donors rescue diabetic nephropathy through oxidative-stress-and nitrosativestress-mediated Wnt signaling pathways. J Diabetes Invest 2015; 6(1): 24-34.