Title: The Association Between Serum Glutathione Peroxidase-3 Concentration and Risk of Acute Kidney Injury After Cardiac Surgery: A Nested Case-Control Study
Abstract: Oxidative stress has an integral role in the pathophysiology of cardiac surgery-associated acute kidney injury (CSA-AKI). Glutathione peroxidase 3 (GPx3) is an important antioxidant enzyme in circulation and is mainly secreted by the kidney. This study aimed to evaluate the relation between GPx3 protein and CSA-AKI. This study is a nested case-control study in Zhongshan Hospital affiliated with Fudan University. We examined serum samples from 80 CSA-AKI patients and 80 age- and gender-matched non-AKI patients who underwent cardiac surgery. AKI was defined according to Kidney Disease: Improving Global Outcomes (KDIGO) 2012 criteria. We measured serum GPx3 concentration using the enzyme-linked immunosorbent assay. GPx3 ratio is the ratio of preoperative and 6 hours postoperative of GPx3 protein concentration. We applied dose-response relation analyses to odds ratio in different GPx3 ratio levels and integrated it into the logistic model to predict the risk of AKI. The receiver operating characteristic curve and area under the curve (AUC) was used to assess the prediction models. Postoperative serum GPx3 concentrations were significantly lower in the AKI group compared with the non-AKI group (1.78 ± 0.33 vs 2.03 ± 0.27, p <0.001). Malondialdehyde was higher in the AKI than in the non-AKI group (17.74 ± 8.65 vs 7.48 ± 4.59, p <0.001). The AKI risk increased in a dose-dependent manner, which was flat in the first half of the GPx3 ratio and then tended to be faster. The peaking odds ratio of CSA-AKI was 2.615 at the GPx3 ratio of 1.21 to 1.40. The AUC value to predict CSA-AKI only included the GPx3 ratio was 72.3%. After gradually integrating other covariates (body mass index, aortic crossclamp time, and cardiopulmonary bypass), the model showed an AUC of 82.6%. The serum GPx3 concentration was significantly lower in the CSA-AKI group. GPx3 ratio has a good predictive value for CSA-AKI, which may be a potential early diagnostic marker for AKI. Oxidative stress has an integral role in the pathophysiology of cardiac surgery-associated acute kidney injury (CSA-AKI). Glutathione peroxidase 3 (GPx3) is an important antioxidant enzyme in circulation and is mainly secreted by the kidney. This study aimed to evaluate the relation between GPx3 protein and CSA-AKI. This study is a nested case-control study in Zhongshan Hospital affiliated with Fudan University. We examined serum samples from 80 CSA-AKI patients and 80 age- and gender-matched non-AKI patients who underwent cardiac surgery. AKI was defined according to Kidney Disease: Improving Global Outcomes (KDIGO) 2012 criteria. We measured serum GPx3 concentration using the enzyme-linked immunosorbent assay. GPx3 ratio is the ratio of preoperative and 6 hours postoperative of GPx3 protein concentration. We applied dose-response relation analyses to odds ratio in different GPx3 ratio levels and integrated it into the logistic model to predict the risk of AKI. The receiver operating characteristic curve and area under the curve (AUC) was used to assess the prediction models. Postoperative serum GPx3 concentrations were significantly lower in the AKI group compared with the non-AKI group (1.78 ± 0.33 vs 2.03 ± 0.27, p <0.001). Malondialdehyde was higher in the AKI than in the non-AKI group (17.74 ± 8.65 vs 7.48 ± 4.59, p <0.001). The AKI risk increased in a dose-dependent manner, which was flat in the first half of the GPx3 ratio and then tended to be faster. The peaking odds ratio of CSA-AKI was 2.615 at the GPx3 ratio of 1.21 to 1.40. The AUC value to predict CSA-AKI only included the GPx3 ratio was 72.3%. After gradually integrating other covariates (body mass index, aortic crossclamp time, and cardiopulmonary bypass), the model showed an AUC of 82.6%. The serum GPx3 concentration was significantly lower in the CSA-AKI group. GPx3 ratio has a good predictive value for CSA-AKI, which may be a potential early diagnostic marker for AKI. Cardiac surgery-associated acute kidney injury (CSA-AKI) is the most common perioperative complication after cardiac surgery,1Tseng PY Chen YT Wang CH Chiu KM Peng YS Hsu SP Chen KL Yang CY Lee OK Prediction of the development of acute kidney injury following cardiac surgery by machine learning.Crit Care. 2020; 24: 478Crossref PubMed Scopus (159) Google Scholar, 2Wang Y Bellomo R Cardiac surgery-associated acute kidney injury: risk factors, pathophysiology and treatment.Nat Rev Nephrol. 2017; 13: 697-711Crossref PubMed Scopus (382) Google Scholar, 3Cui H Shu S Li Y Yan X Chen X Chen Z Hu Y Chang Y Hu Z Wang X Song J Plasma metabolites-based prediction in cardiac surgery-associated acute kidney injury.J Am Heart Assoc. 2021; 10e021825Crossref Scopus (11) Google Scholar, 4Nadim MK Forni LG Bihorac A Hobson C Koyner JL Shaw A Arnaoutakis GJ Ding X Engelman DT Gasparovic H Gasparovic V Herzog CA Kashani K Katz N Liu KD Mehta RL Ostermann M Pannu N Pickkers P Price S Ricci Z Rich JB Sajja LR Weaver FA Zarbock A Ronco C Kellum JA Cardiac and vascular surgery-associated acute kidney injury: the 20th International Consensus Conference of the ADQI (Acute Disease Quality Initiative) Group.J Am Heart Assoc. 2018; 7e008834Crossref PubMed Scopus (173) Google Scholar with an incidence of 20% to 70%.5Bastin AJ Ostermann M Slack AJ Diller GP Finney SJ Evans TW Acute kidney injury after cardiac surgery according to Risk/Injury/Failure/Loss/End-Stage, Acute Kidney Injury Network, and Kidney Disease: improving Global Outcomes classifications.J Crit Care. 2013; 28: 389-396Crossref PubMed Scopus (148) Google Scholar CSA-AKI is independently associated with increased higher perioperative mortality, and short-term and long-term morbidity even for those patients with complete renal recovery.2Wang Y Bellomo R Cardiac surgery-associated acute kidney injury: risk factors, pathophysiology and treatment.Nat Rev Nephrol. 2017; 13: 697-711Crossref PubMed Scopus (382) Google Scholar,6Hobson CE Yavas S Segal MS Schold JD Tribble CG Layon AJ Bihorac A Acute kidney injury is associated with increased long-term mortality after cardiothoracic surgery.Circulation. 2009; 119: 2444-2453Crossref PubMed Scopus (755) Google Scholar, 7Wang Y Zou Z Jin J Teng J Xu J Shen B Jiang W Zhuang Y Liu L Luo Z Wang C Ding X Urinary TIMP-2 and IGFBP7 for the prediction of acute kidney injury following cardiac surgery.BMC Nephrol. 2017; 18: 177Crossref PubMed Scopus (39) Google Scholar, 8Xu JR Zhu JM Jiang J Ding XQ Fang Y Shen B Liu ZH Zou JZ Liu L Wang CS Ronco C Liu H Teng J Risk factors for long-term mortality and progressive chronic kidney disease associated with acute kidney injury after cardiac surgery.Med (Baltim). 2015; 94: e2025Crossref PubMed Scopus (81) Google Scholar Besides, CSA-AKI prolonged the length of stay in the intensive care unit and in the hospital, meanwhile, it also increased the cost of care.9Chertow GM Burdick E Honour M Bonventre JV Bates DW Acute kidney injury, mortality, length of stay, and costs in hospitalized patients.J Am Soc Nephrol. 2005; 16: 3365-3370Crossref PubMed Scopus (2655) Google Scholar,10Quan S Pannu N Wilson T Ball C Tan Z Tonelli M Hemmelgarn BR Dixon E James MT Prognostic implications of adding urine output to serum creatinine measurements for staging of acute kidney injury after major surgery: a cohort study.Nephrol Dial Transplant. 2016; 31: 2049-2056Crossref PubMed Scopus (35) Google Scholar Therefore, early identification of potential patients with CSA-AKI and early diagnosis of CSA-AKI remain a priority in the fields of nephrology and intensive care medicine. Glutathione peroxidase 3 (GPx3) is the only extracellular isoform secreted isozyme abundantly expressed in the kidneys and the thyroid.11Schomburg L Selenium, selenoproteins and the thyroid gland: interactions in health and disease.Nat Rev Endocrinol. 2011; 8: 160-171Crossref PubMed Scopus (254) Google Scholar,12Cardoso BR Hare DJ Bush AI Roberts BR Glutathione peroxidase 4: a new player in neurodegeneration?.Mol Psychiatry. 2017; 22: 328-335Crossref PubMed Scopus (182) Google Scholar GPx3 as a modulator of redox signaling accounts for the major anti-oxidative activity in the circulation.13Langhardt J Flehmig G Klöting N Lehmann S Ebert T Kern M Schön MR Gärtner D Lohmann T Dressler M Fasshauer M Kovacs P Stumvoll M Dietrich A Blüher M Effects of weight loss on glutathione peroxidase 3 serum concentrations and adipose tissue expression in human obesity.Obes Facts. 2018; 11: 475-490Crossref PubMed Scopus (34) Google Scholar Therefore, GPx3 protein concentration can be easily assayed in plasma, which makes it a useful prognostic and diagnostic biomarker. Oxidative stress is a crucial mechanism in the development of CSA-AKI.2Wang Y Bellomo R Cardiac surgery-associated acute kidney injury: risk factors, pathophysiology and treatment.Nat Rev Nephrol. 2017; 13: 697-711Crossref PubMed Scopus (382) Google Scholar,14Dhalla NS Elmoselhi AB Hata T Makino N Status of myocardial antioxidants in ischemia–reperfusion injury.Cardiovasc Res. 2000; 47: 446-456Crossref PubMed Scopus (681) Google Scholar,15Haase M Bellomo R Haase-Fielitz A Novel biomarkers, oxidative stress, and the role of labile iron toxicity in cardiopulmonary bypass-associated acute kidney injury.J Am Coll Cardiol. 2010; 55: 2024-2033Crossref PubMed Scopus (182) Google Scholar In an animal model, it has been reported that persistent oxidative stress in renal tissues resulted in decreased GPx3 after renal ischemia-reperfusion injury (IRI).16Basile DP Leonard EC Beal AG Schleuter D Friedrich J Persistent oxidative stress following renal ischemia-reperfusion injury increases ANG II hemodynamic and fibrotic activity.Am J Physiol Renal Physiol. 2012; 302: F1494-F1502Crossref PubMed Scopus (63) Google Scholar In this study, we sought to determine potential associations between circulating GPx3 protein concentration and the development of CSA-AKI. This is a nested case-control study of hospitalized patients who underwent cardiac surgery in a third-class hospital in mainland China during the period of July 2021 to July 2022. These patients were evaluated at a high risk of CSA-AKI according to CSA-AKI risk score.17Jiang W Teng J Xu J Shen B Wang Y Fang Y Zou Z Jin J Zhuang Y Liu L Luo Z Wang C Ding X Dynamic predictive scores for cardiac surgery-associated acute kidney injury.J Am Heart Assoc. 2016; 5e003754Crossref Scopus (60) Google Scholar The inclusion criteria of participants were as follows: aged over 18 years, underwent elective cardiopulmonary bypass (CPB) cardiac surgery, and CSA-AKI risk score ≥4 (Supplementary Table 1). Patients were excluded if they had situations as follows: pregnant, chronic kidney disease stage 5, underwent renal transplantation, liver failure or hepatorenal syndrome, acute myocardial infarction within 1 week, participated in another clinical trial, or investigators considering that it is inappropriate to participate in this study. Informed consent was obtained from all participants. The primary end points were AKI and moderate-to-severe AKI within 48 hours after cardiac surgery. AKI was defined according to the 2012 Kidney Disease: Improving Global Outcomes (KDIGO) guideline as follows: increase in serum creatinine by ≥0.3 mg/100 ml (≥26.5 μmol/L) within 48 hours. Severe AKI was defined as KDIGO stage 2 or 3. GPx3 ratio is the ratio of preoperative and 6 hours postoperative of GPx3 protein concentration. Demographic characteristics, including age, gender, height, weight, body mass index (BMI), co-morbidities (hypertension, diabetes mellitus, chronic kidney disease, and so on), intraoperative and postoperative data, were abstracted from history taking and the electronic medical record system. The biochemical data of the patients within 24 hours of admission were collected as baseline variables, including renal function, and other biochemical data. We also collected renal function 24 and 48 hours after surgery. The blood samples of GPx3 protein concentration and malondialdehyde (MDA) concentration were collected at 6 hours after surgery. For each suberect, the serum sample was separated from the blood sample by centrifuging at 3,000 rotations/min for 15 minutes at 4°C, separated into 1-ml aliquots, and immediately stored at −80°C until analysis. GPx3 was measured using the commercial enzyme-linked immunosorbent assay, brought from AdipoGen Life Sciences, for quantitative determination of GPx3 protein concentration in human serum samples. A polyclonal antibody specific for GPx3 protein has been precoated onto the 96-well microtiter plate. GPx3 protein was detected with biotinylated polyclonal antibody and horseradish peroxidase-labeled streptavidin using 3,3′,5,5′-tetra methyl benzidine as horseradish peroxidase substrate. The intensity of the color reaction measured using the SpectraMax (Molecular Devices, Silicon Valley, California) at 450 nm is directly proportional to the protein concentration of GPx3 in the serum sample. MDA concentration was determined using the MDA-TBA (thiobarbituric acid, TBA) method as described in the Lipid Peroxidation MDA assay kit brought from Beyotime Biotechnology. MDA levels were detected by microplate readers (BioTek Epoch 2,BioTek Instruments,Inc, Vermont) at 532 nm. The statistical analysis was run in R 4.0.3 software. The data of normal distribution are described as mean ± SD, and the data of skewed distribution are described by the median and interquartile range and were compared by Student's t test and Wilcoxon test. Categorical variables were described by frequency and compared using Pearson's test. For dose-response relation statistics, a correlation model between GPx3 protein concentration and the incidence of CSA-AKI, and the likelihood ratio test was used to compare nonlinear variables. To assess the predictive ability of the GPx3 ratio for the primary end point, receiver operating characteristic curves, area under the curve (AUC), sensitivity, and specificity were calculated. The 95% confidence intervals (CIs) for the AUC and receiver operating characteristic were determined using boot-strap and the Clopper-Pearson method respectively. All statistical tests were two-tailed, and the statistical significance was set at p <0.05. This study included 160 participants, the mean age was 65.33 ± 7.93 years, and 107 (66.9%) were male. In 80 patients with CSA-AKI, 73 (91.3%), 6 (7.5%), and 1 patients (1.3%) were in AKI stage 1, stage 2, and stage 3, respectively. Table 1 lists the major factors associated with CSA-AKI. Patients who had a higher BMI, prolonged CPB, and aortic crossclamp time (ACCT) were more likely to develop AKI. Although not statistically significant (p = 0.071), hypertension was more common in patients with CSA-AKI. Length of stay in the intensive care unit and the duration of mechanical ventilation in CSA-AKI patients was apparently longer than in non-AKI patients.Table 1Demographic characteristicsVariablesAKI(n = 80)non-AKI(n = 80)Total(n = 160)Demographic characteristics Age65.71±7.6964.96±8.1965.33±7.930.560 Male gender, n (%)55 (68.8)52 (65.0)107 (66.9)0.737 BMI (kg/m²)24.12±3.1222.43±2.9623.27±3.150.001 Cardiac function (NYHA) I-II (n, %)23 (28.8)19 (23.8)42 (26.3)0.557 III-IV (n, %)57(71.2)61 (76.2)118 (73.8)0.557Comorbidities Hypertension, n (%)31 (38.8)21 (26.3)52 (32.5)0.071 Diabetes mellitus, n (%)6 (7.5)5 (6.3)11 (6.88)0.755 Hyperlipidemia, n (%)3 (3.8)4 (5.0)7 (4.3)0.725 Hyperuricemia/gout, n (%)8 (10.0)5 (6.3)13 (8.13)0.399 CKD, n (%)3 (3.8)1 (1.3)4 (2.5)0.364 COPD, n (%)1 (1.3)01 (0.65)0.494 MI, n (%)4 (5.0)3 (3.8)7 (4.3)0.782 Encephalorrhagia, n (%)1 (1.3)01 (0.6)0.494 Cerebal infraction, n (%)4 (5.0)5 (6.3)9 (5.6)0.744Life style Current or former smoker21 (26.3)23 (28.7)44 (27.5)0.860 Current or former drinker13 (16.3)13 (16.3)26 (16.25)0.542Surgery style Valve, n (%)58 (72.5)62 (77.5)120 (75.0)0.200 Valve + CABG, n (%)10 (12.5)6 (7.5)16 (10.0) Others, n (%)12 (15.0)12 (15.0)24 (15.0) CPB117.56 ±34.8098.37 ± 33.12107.35 ± 35.140.001 ACCT (Aortic occlusion time)65.55±30.9854.81 ± 27.0459.84 ± 29.340.030 ECMO, n (%)0001.000 IABP, n (%)1 (1.3)1 (1.3)2 (2.6)1.000 Blood transfusion, n (%)17 (21.3)13 (16.3)30 (18.8)0.221 Duration of mechanical Ventilation, days1 [0.83,1]1 [0.5,1]1 [0.7,1]0.031 LOS in ICU2 [1,3]1 [1,2]1 [1,3]0.017 LOS after surgery6 [4,9]6 [5,9]6 [5,9]0.273ACCT = aortic crossclamp time; BMI = body mass index; CABG = coronary artery bypass grafting; CKD = chronic kidney disease; COPD = chronic obstructive pulmonary disease; CPB = cardiopulmonary bypass; ECMO = extracorporeal membrane oxygenation; IABP = intra-aortic balloon pump; ICU = intensive care unit; LOS = length of stay; MI = myocardial infraction; NYHA = New York Heart Association. Open table in a new tab ACCT = aortic crossclamp time; BMI = body mass index; CABG = coronary artery bypass grafting; CKD = chronic kidney disease; COPD = chronic obstructive pulmonary disease; CPB = cardiopulmonary bypass; ECMO = extracorporeal membrane oxygenation; IABP = intra-aortic balloon pump; ICU = intensive care unit; LOS = length of stay; MI = myocardial infraction; NYHA = New York Heart Association. All clinical laboratory biochemicals are listed in Table 2. There was no significant difference in GPx3 protein concentration before surgery between AKI and non-AKI groups. The GPx3 protein concentration at 6 hours after surgery was significantly lower in the AKI group compared with the non-AKI group (1.78 ± 0.33 vs 2.03 ± 0.27, p <0.001), and patients with AKI had higher postoperative serum creatinine levels (96.62 ± 34.74 vs 84.25 ± 19.36, p = 0.006). MDA was higher in the AKI than in the non-AKI group (17.74 ± 8.65 vs 7.48 ± 4.59, p <0.001).Table 2Clinical biochemical indexes and CSA-AKIVariablesAKI(n =80)non-AKI(n = 80)Total(n = 160)PGPx3 protein concentration (μg/ml) Before surgery1.99 ±0.361.98 ± 0.291.99± 0.320.865 6h after surgery1.78± 0.332.03± 0.271.90± 0.33<0.001MDA concentration (μmol/L) 6h after surgery17.74 ± 8.657.48 ± 4.5912.74 ± 8.62<0.001Blood routine examination Hb (g/L)128.01±15.29133.28±18.27130.63±17.000.055 RBC (1012/L)4.16±0.4884.32±0.564.24±0.530.070 WBC (109/L)6.57±1.145.63±1.5475.76±1.510.308 Neutrophil(109/L)56.98±7.3856.97±8.6656.98±7.970.993 Platelet (10⁹/L)167.13±51.59183.32±70.08175.2±61.800.106Renal function BUN (mmol/L) Before surgery8.69 ± 2.237.56 ±2.648.14 ± 2.210.186 24h after surgery10.31 ± 2.737.86 ± 2.789.09 ± 2.61<0.001 48h after surgery12.57 ±3.4810.29 ± 10.3911.43± 7.800.080 SCr (µmol/L) Before surgery96.62 ±34.7484.25 ± 19.3690.44 ± 28.710.006 24h after surgery132.94 ± 39.2188.23 ±20.85110.72± 38.55<0.001 48h after surgery138.96 ± 55.8785.04 ± 21.56112.00 ± 50.13<0.001 eGFR (ml/min/1.73m²) Before surgery70.97± 18.1876.49± 16.9473.66 ± 17.750.057 24h after surgery48.00± 12.6872.22 ± 16.7859.85 ± 19.13<0.001 48h after surgery49.42 ± 20.1075.10± 18.34262.08 ± 23.11<0.001 UA (µmol/L) Before surgery411.81± 117.19395.16±119.29403.71± 118.110.390 24h after surgery404.73± 97.26324.01 ±105.72364.37 ± 109.03<0.001 48h after surgery370.76 ± 101.69270.04 ± 101.01320.76 ± 112.93<0.001Liver function TB (µmol/L)13.12±6.813.05±5.1513.17±6.010.919 DB (µmol/L)4.47±2.054.01±2.064.24±2.230.383 AST (U/L)20.34±6.1520.96±6.71420.64±6.420.554 ALT (U/L)17.86±10.31417.88±11.86217.87±11.0630.991Cardiac biomarkers BNP (pg/ml)754[280,1754]718[121,2033]719[194,1819]0.490 CK-MB (U/L)11.86 ± 6.5812.68 ± 8.5112.26± 7.560.595Other laboratory indexes Total protein (g/L)63.44± 5.12164.11±7.4663.78± 6.370.514 Albumin (g/L)39.91 ± 3.5340.65 ± 3.20340.28± 3.380.175 Globulin (g/L)23.53 ± 4.00823.45 ± 7.1523.49 ± 5.750.933 FBG (mmol/L)4.95 ± 0.9375.05± 0.7755.00± 0.860.525 GA (%)12.30 ± 4.4611.75± 3.6812.02± 4.030.673 TC (mmol/L)4.12 ± 0.984.22 ± 0.8714.16 ± 0.9270.512 TG (mmol/L)1.43 ± 0.861.24 ± 0.7421.34± 0.8070.170 HDL (mmol/L)1.27 ±0.8421.28 ±0.581.27 ± 0.7240.907 LDL (mmol/L)2.29 ±0.7932.43± 0.7222.36 ± 0.7610.260ALT = alanine aminotransferase; AST = aspartate aminotransferase; BNP = brain natriuretic peptide; BUN = blood urea nitrogen; CK-MB = creatine kinase MB isoenzyme; CSA-AKI = cardiac surgery associated acute kidney injury; DB = direct bilirubin; eGFR = estimated glomerular filtration rate; FBG = fasting blood-glucose; GA = glycated albumin; GPx3 = glutathione peroxidase-3; Hb = hemoglobin; HDL = high density lipoprotein; LDL = low density lipoprotein; RBC = red blood cell; SCr = serum creatinine; TB = total bilirubin; TC = total cholesterol; TG = triglycerides; UA = uric acid; WBC = white blood cell. Open table in a new tab ALT = alanine aminotransferase; AST = aspartate aminotransferase; BNP = brain natriuretic peptide; BUN = blood urea nitrogen; CK-MB = creatine kinase MB isoenzyme; CSA-AKI = cardiac surgery associated acute kidney injury; DB = direct bilirubin; eGFR = estimated glomerular filtration rate; FBG = fasting blood-glucose; GA = glycated albumin; GPx3 = glutathione peroxidase-3; Hb = hemoglobin; HDL = high density lipoprotein; LDL = low density lipoprotein; RBC = red blood cell; SCr = serum creatinine; TB = total bilirubin; TC = total cholesterol; TG = triglycerides; UA = uric acid; WBC = white blood cell. The dose-response relation between the GPx3 ratio and CSA-AKI was shown in Figure 1. It was figured out that the GPx3 ratio was positively correlated with the risk of AKI. The upward trend in AKI at GPx3 ratio ≥1.2 was faster than at GPx3 ratio <1.2 (odds ratio [OR] 2.8, 95% CI 1.430 to 5.536, p <0.0001). Then we classified the GPx3 ratio into 6 levels, as listed in Table 3. Compared with the GPx3 ratio of 0.6 to 0.8, the risk continued to grow at a higher GPx3 ratio. The peaking OR of CSA-AKI was 2.615 (95% CI 1.003 to 6.822, p = 0.0350) at the GPx3 ratio of 1.21 to 1.40. The severe AKI showed a similar upward trend.Table 3Levels of GPx3 ratio and risk stratification for AKIn(160)AKISevere AKIn (%)aOR (95% CI)Pn (%)aOR (95% CI)PGPx 3 ratio0.6-0.80124 (33.3)Ref00.81-1.005416 (29.6)0.870(0.295,2.559)0.8012 (3.7)Ref1.01-1.206335 (55.5)2.167(0.713, 6.584)0.1581 (1.6)0.684 (0.300, 1.561)0.4701.21-1.401813 (72.7)2.615 (1.003, 6.822)0.0351 (5.6)1.130 (0.502, 2.545)0.7331.41-1.6087 (87.5)2.444 (1.082, 5.523)0.0171 (12.5)1.322 (0.591, 2.959)0.2791.61-1.8055 (100)2.25 (1.084, 4.671)0.0122 (40.0)1.891 (0.708, 5.049)0.002 Open table in a new tab We used a logistic model based on GPx3 ratio to predict CSA-AKI (Figure 2). In the model with GPx3 ratio alone, the AUC value was 72.3% (95% CI 64.4% to 80.2%). With the progressive enrollment of ACCT, CPB, the AUC value increased from 72.3% to 76.6% (95% CI 68.6% to 84.5%). With the progressive enrollment of BMI, the AUC value increased from 76.6% to 82.6% (95% CI 75.6% to 89.6%). Our data indicate that decreased GPx3 concentration predicts clinical CSA-AKI and the AUC of the GPx3 ratio after adjusting BMI, ACCT, and CPB reaches a better prediction ability than that of the GPx3 ratio alone. Both in human studies and in animal models, GPx3 protein concentration and its bioactivity have already been investigated in various diseases. The bioactivity of GPx3 was found to be inversely associated with critical illness.18Manzanares W Biestro A Galusso F Torre MH Mañay N Pittini G Facchin G Hardy G Serum selenium and glutathione peroxidase-3 activity: biomarkers of systemic inflammation in the critically ill?.Intensive Care Med. 2009; 35: 882-889Crossref PubMed Scopus (114) Google Scholar,19Lee WJ Chen YL Chu YW Chien DS Comparison of glutathione peroxidase-3 protein expression and enzyme bioactivity in normal subjects and patients with sepsis.Clin Chim Acta. 2019; 489: 177-182Crossref PubMed Scopus (10) Google Scholar There is a positive correlation between GPx3 bioactivity and its protein concentration in septic patients.19Lee WJ Chen YL Chu YW Chien DS Comparison of glutathione peroxidase-3 protein expression and enzyme bioactivity in normal subjects and patients with sepsis.Clin Chim Acta. 2019; 489: 177-182Crossref PubMed Scopus (10) Google Scholar Lower plasma GPx3 levels were observed in patients and rat liver transplantation models with hepatocellular carcinoma recurrence.20Qi X Ng KT Lian Q Li CX Geng W Ling CC Yeung WH Ma YY Liu XB Liu H Liu J Yang XX Lo CM Man K Glutathione peroxidase 3 delivered by hiPSC-MSCs ameliorated hepatic IR injury via inhibition of hepatic senescence.Theranostics. 2018; 8: 212-222Crossref PubMed Scopus (26) Google Scholar GPx deficiency has previously been demonstrated in hemodialysis patients and those with CKD.21Heather E Roxborougha Caroline Mercerb Dorothy McMaster ea [plasma GPx zctiviyt is reduced in haemodialysis patients].Nephron. 1998; 81: 278-283Google Scholar,22Pang P Abbott M Abdi M Fucci QA Chauhan N Mistri M Proctor B Chin M Wang B Yin W Lu TS Halim A Lim K Handy DE Loscalzo J Siedlecki AM Pre-clinical model of severe glutathione peroxidase-3 deficiency and chronic kidney disease results in coronary artery thrombosis and depressed left ventricular function.Nephrol Dial Transplant. 2018; 33: 923-934Crossref PubMed Scopus (22) Google Scholar Jin et al23Jin RC Mahoney CE Coleman Anderson L Ottaviano F Croce K Leopold JA Zhang YY Tang SS Handy DE Loscalzo J Glutathione peroxidase-3 deficiency promotes platelet-dependent thrombosis in vivo.Circulation. 2011; 123: 1963-1973Crossref PubMed Scopus (127) Google Scholar found that GPx3 deficiency promoted platelet-dependent thrombosis in vivo. Previous studies have not demonstrated a consistent association between GPx3 and AKI after cardiac surgery. In this context, we are the first to deem that decreased plasma GPx3 is discovered in CSA-AKI patients, suggesting that GPx3 is a potential diagnostic marker for AKI and predicts CSA-AKI after cardiac surgery. GPx3 is primarily synthesized by the basolateral membrane of epithelial cells in the proximal renal tubule cells.24Nirgude S Choudhary B Insights into the role of GPX3, a highly efficient plasma antioxidant, in cancer.Biochem Pharmacol. 2021; 184114365Crossref PubMed Scopus (31) Google Scholar, 25Olson GE Whitin JC Hill KE Winfrey VP Motley AK Austin LM Deal J Cohen HJ Burk RF Extracellular glutathione peroxidase (Gpx3) binds specifically to basement membranes of mouse renal cortex tubule cells.Am J Physiol Renal Physiol. 2010; 298: F1244-F1253Crossref PubMed Scopus (120) Google Scholar, 26Whitin JC Bhamre S Tham DM Cohen HJ Extracelluar glutathione peroxidase is secerted basolaterally by human renal proximao tubule cells.Am J Physiol Ren Physiol. 2002; 283: F20-F28Crossref PubMed Scopus (86) Google Scholar GPx3 is a member of the GPx family and plays a vital role in eliminating all forms of hydrogen peroxide and organic peroxides generated in the body23Jin RC Mahoney CE Coleman Anderson L Ottaviano F Croce K Leopold JA Zhang YY Tang SS Handy DE Loscalzo J Glutathione peroxidase-3 deficiency promotes platelet-dependent thrombosis in vivo.Circulation. 2011; 123: 1963-1973Crossref PubMed Scopus (127) Google Scholar and catalyzing the conversion of glutathione to oxidized glutathione.24Nirgude S Choudhary B Insights into the role of GPX3, a highly efficient plasma antioxidant, in cancer.Biochem Pharmacol. 2021; 184114365Crossref PubMed Scopus (31) Google Scholar,27Chełchowska M Gajewska J Ambroszkiewicz J Mazur J Ołtarzewski M Maciejewski TM Influence of oxidative stress generated by smoking during pregnancy on glutathione status in mother-newborn pairs.Antioxidants (Basel). 2021; 10: 1866Crossref PubMed Scopus (6) Google Scholar In our report, we showed that in patients with CSA-AKI, GPx3 protein concentration at 6 hours after surgery was significantly lower than that in non-AKI patients. MDA was higher in patients with CSA-AKI. The potential regulatory mechanisms of GPx3 and its physiological and pathophysiological roles in CSA-AKI remain elusive. Mechanisms of CSA-AKI include perioperative renal ischemia-reperfusion injury, oxidative stress,28Billings 4th, FT Pretorius M Schildcrout JS Mercaldo ND Byrne JG Ikizler TA Brown NJ Obesity and oxidative stress predict AKI after cardiac surgery.J Am Soc Nephrol. 2012; 23: 1221-1228Crossref PubMed Scopus (122) Google Scholar inflammation, CPB-induced hemolysis, and pigment nephropathy.29O'Neal JB Shaw AD Billings 4th, FT Acute kidney injury following cardiac surgery: current understanding and future directions.Crit Care. 2016; 20: 187Crossref PubMed Scopus (348) Google Scholar,30Huen SC Parikh CR Predicting acute kidney injury after cardiac surgery: a systematic review.Ann Thorac Surg. 2012; 93: 337-347Abstract Full Text Full Text PDF PubMed Scopus (172) Google Scholar They are interdependent and interrelated between IRI, oxidative stress, and inflammation.29O'Neal JB Shaw AD Billings 4th, FT Acute kidney injury following cardiac surgery: current understanding and future directions.Crit Care. 2016; 20: 187Crossref PubMed Scopus (348) Google Scholar Cardiac surgery also induces renal and systemic inflammation.31Zhang WR Garg AX Coca SG Devereaux PJ Eikelboom J Kavsak P McArthur E Thiessen-Philbrook H Shortt C Shlipak M Whitlock R Parikh CR TRIBE-AKI ConsortiumPlasma IL-6 and IL-10 concentrations predict AKI and long-term mortality in adults after cardiac surgery.J Am Soc Nephrol. 2015; 26: 3123-3132Crossref PubMed Scopus (129) Google Scholar The exposure of blood to the CPB circuit, IRI, and oxidative damage all contribute to inflammation.31Zhang WR Garg AX Coca SG Devereaux PJ Eikelboom J Kavsak P McArthur E Thiessen-Philbrook H Shortt C Shlipak M Whitlock R Parikh CR TRIBE-AKI ConsortiumPlasma IL-6 and IL-10 concentrations predict AKI and long-term mortality in adults after cardiac surgery.J Am Soc Nephrol. 2015; 26: 3123-3132Crossref PubMed Scopus (129) Google Scholar IRI disrupts the cellular redox balance and promotes the generation of reactive oxygen species (ROS) and superoxide in kidney.16Basile DP Leonard EC Beal AG Schleuter D Friedrich J Persistent oxidative stress following renal ischemia-reperfusion injury increases ANG II hemodynamic and fibrotic activity.Am J Physiol Renal Physiol. 2012; 302: F1494-F1502Crossref PubMed Scopus (63) Google Scholar ROS are derived from molecular oxygen and non-radicals like hydrogen peroxide. ROS induces inflammation by activating proinflammatory transcription factors32Hussain T Tan B Yin Y Blachier F Tossou MC Rahu N Oxidative stress and inflammation: what polyphenols can do for us?.Oxid Med Cell Longev. 2016; 20167432797Crossref PubMed Scopus (1184) Google Scholar and proinflammatory signals such as Toll-like receptors and the nucleotide oligomerization domain (NOD)-like receptor thermal protein domain associated Protein 3 inflammasome.33Collins LV Hajizadeh S Holme E Jonsson IM Tarkowski A Endogenously oxidized mitochondrial DNA induces in vivo and in vitro inflammatory responses.J Leukoc Biol. 2004; 75: 995-1000Crossref PubMed Scopus (374) Google Scholar,34Shimada K Crother TR Karlin J Dagvadorj J Chiba N Chen S Ramanujan VK Wolf AJ Vergnes L Ojcius DM Rentsendorj A Vargas M Guerrero C Wang Y Fitzgerald KA Underhill DM Town T Arditi M Oxidized mitochondrial DNA activates the NLRP3 inflammasome during apoptosis.Immunity. 2012; 36: 401-414Abstract Full Text Full Text PDF PubMed Scopus (1484) Google Scholar Inflammation also promotes ROS production.35Radhakrishna Baliga NU Walker PD Shah SV Oxidant mechanisms in toxic acute renal failure.Physiol Cell Biol Update. 1997; 29: 465-477Google Scholar As a major ROS scavenger in plasm, Gpx3 is heavily consumed during oxidative stress and inflammation. Previous studies indicated that the GPx3 protein or GPx3 activity was decreased in oxidative stress and inflammation. As previously mentioned, GPx3 is secreted by the proximal renal tubule cells (PTC).26Whitin JC Bhamre S Tham DM Cohen HJ Extracelluar glutathione peroxidase is secerted basolaterally by human renal proximao tubule cells.Am J Physiol Ren Physiol. 2002; 283: F20-F28Crossref PubMed Scopus (86) Google Scholar When the proximal renal tubule was injured after cardiac surgery, the GPx3 protein concentration would be reduced. It has been reported that post-AKI rats had decreased renal GPx3 mRNA expression.16Basile DP Leonard EC Beal AG Schleuter D Friedrich J Persistent oxidative stress following renal ischemia-reperfusion injury increases ANG II hemodynamic and fibrotic activity.Am J Physiol Renal Physiol. 2012; 302: F1494-F1502Crossref PubMed Scopus (63) Google Scholar And CKD was related to lower GPx activity.21Heather E Roxborougha Caroline Mercerb Dorothy McMaster ea [plasma GPx zctiviyt is reduced in haemodialysis patients].Nephron. 1998; 81: 278-283Google Scholar,36Zachara BA Trafikowska U Adamowicz A Nartowicz E Manitius J Selenium, glutathione peroxidases, and some other antioxidant parameters in blood of patients with chronic renal failure.J Trace Elem Med Biol. 2001; 15: 161-166Crossref PubMed Scopus (37) Google Scholar Because of increase the excessive consumption and decrease the production of GPx3 in C patients with CSA-AKI during cardiac surgery, the GPx3 protein concentrations of CSA-AKI were lower than those without. We wonder what would happen, if we exogenously supplement Gpx3 and its related substances to patients with CSA-AKI. Ebselen is seleno-organic compound of GPx, which is able to ameliorate IRI of the kidney by decreasing oxidative and nitrosative stresses in rat renal IRI model.37Kizilgun M Poyrazoglu Y Oztas Y Yaman H Cakir E Cayci T Akgul OE Kurt YG Yaren H Kunak ZI Macit E Ozkan E Taslipinar MY Turker T Ozcan A Beneficial effects of N-acetylcysteine and ebselen on renal ischemia/reperfusion injury.Ren Fail. 2011; 33: 512-517Crossref PubMed Scopus (30) Google Scholar Ebselen also has a renoprotective effect in a model of diabetic complications in the setting of enhanced oxidative stress.38Chew P Yuen DY Stefanovic N Pete J Coughlan MT Jandeleit-Dahm KA Thomas MC Rosenfeldt F Cooper ME de Haan JB Antiatherosclerotic and renoprotective effects of ebselen in the diabetic apolipoprotein E/GPx1-double knockout mouse.Diabetes. 2010; 59: 3198-3207Crossref PubMed Scopus (103) Google Scholar It is a promising candidate for IRI induced AKI through selenium-containing nanomaterials to remedy Se imbalance and impede inflammatory responses in the kidney.39Wang S Chen Y Han S Liu Y Gao J Huang Y Sun W Wang J Wang C Zhao J Selenium nanoparticles alleviate ischemia reperfusion injury-induced acute kidney injury by modulating GPx-1/NLRP3/Caspase-1 pathway.Theranostics. 2022; 12: 3882-3895Crossref PubMed Google Scholar A potential use of Se supplementation has been proposed benefit patients with sepsis. Therapeutic role of recombinant GPx3 has not been used in renal diseases, whereas it has been explored in the hepatocellular carcinoma. GPx3 treatment at early phase was suggested as a new therapeutic strategy for patients with hepatocellular carcinoma after liver transplantation.20Qi X Ng KT Lian Q Li CX Geng W Ling CC Yeung WH Ma YY Liu XB Liu H Liu J Yang XX Lo CM Man K Glutathione peroxidase 3 delivered by hiPSC-MSCs ameliorated hepatic IR injury via inhibition of hepatic senescence.Theranostics. 2018; 8: 212-222Crossref PubMed Scopus (26) Google Scholar However, our study possesses some limitations. This research is a single-center observational study design, and there may be some unmeasured confounding factors. Given the small sample size, we were unable to give a validation cohort. Additionally, we did not measure GPx3 bioactivity and thus could not know the relation between GPx3 bioactivity and CSA-AKI. The information on long-term kidney function and related prognosis was also not available. In conclusion, the lower GPx3 protein concentration and higher GPx3 ratio are strongly associated with high risk of CSA-AKI. Gpx3 may serve as an early diagnostic marker for CSA-AKI. More further studies are needed to confirm the role of GPx3 in diagnoses and treatment for AKI. Zhouping Zou performed the analysis and drafted the manuscript, Teng Ren, Qi Zeng and Xiaoyan Wang helped to collect the data, Yang Li helped to guide the analysis, Xiaoqiang Ding conceived the idea, participated in manuscript writing and revision. Jiarui Xu and Ping Jia helped to revise the manuscript. All authors have read and approved the final manuscript. The authors have no competing interests to declare. Some or all data, models, or code generated or used during the study are available in a repository or online in accordance with funder data retention policies. This study was approved by the Chinese Clinical Trial Registry (ChiCTR2000035568). Download .docx (.02 MB) Help with docx files