Using circulating O-sulfotyrosine in the differential diagnosis of acute kidney injury and chronic kidney disease.

BACKGROUND: Sulfation of tyrosine, yielding O-sulfotyrosine, is a common but fixed post-translational modification in eukaryotes. Patients with increased circulating O-sulfotyrosine levels experience a faster decline in renal function with progression to end-stage renal disease (ESRD). In the present study, we measured serum O-sulfotyrosine levels in individuals with chronic kidney disease (CKD) and acute kidney injury (AKI) to explore its ability to differentiate AKI from CKD. METHODS: A total of 135 patients (20 with AKI and 115 with CKD) were recruited prospectively for liquid chromatography-mass spectrometry assessment of circulating O-sulfotyrosine. We also studied C57BL/6 mice with CKD after 5/6 nephrectomy (Nx). Blood samples were drawn from the tail vein on Day 1, 3, 5, 7, 14, 30, 60, and 90 after CKD. Serum separation and characterization of creatinine, blood urea nitrogen (BUN), and O-sulfotyrosine was performed. Thus, the time-concentration curves of the O-sulfotyrosine level demonstrate the variation of kidney dysfunction. RESULTS: The serum levels of O-sulfotyrosine were markedly increased in patients with CKD compared with AKI. Median O-sulfotyrosine levels in CKD patients versus AKI, respectively, were as follows:243.61 ng/mL(interquartile range [IQR] = 171.90-553.86) versus 126.55 ng/mL (IQR = 48.19-185.03, P = 0.004). In patients with CKD, O-sulfotyrosine levels were positively correlated with creatinine, BUN, and Cystatin C (r = 0.63, P < 0.001; r = 0.49, P < 0.001; r = 0.61, P < 0.001, respectively) by the multivariate linear regression analysis (ß = 0.71, P < 0.001; ß = 0.40, P = 0.002; ß = 0.73, P < 0.001, respectively). However, this association was not statistically significant in patients with AKI (r = - 0.17, P = 0.472; r = 0.11, P = 0.655; r = 0.09, P = 0.716, respectively). The receiver operating characteristic (ROC) analysis illustrated that the area under the curve was 0.80 (95% confidence interval [CI] 0.71-0.89; P < 0.001) and the optimal cut-off value of serum O-sulfotyrosine suggesting AKI was < 147.40 ng/mL with a sensitivity and specificity of 80.90 and 70.00% respectively. In animal experiments, serum levels of O-sulfotyrosine in mice were elevated on Day 7 after 5/6 nephrectomy (14.89 ± 1.05 vs. 8.88 ± 2.62 ng/mL, P < 0.001) until Day 90 (32.65 ± 5.59 vs. 8.88 ± 2.62 ng/mL, P < 0.001). CONCLUSION: Serum O-sulfotyrosine levels were observed correlated with degrading renal function and in CKD patients substantially higher than those in AKI patients. Thus serum O-sulfotyrosine facilitated the differential diagnosis of AKI from CKD.

Association of serum HMGB2 level with MACE at 1 mo of myocardial infarction: Aggravation of myocardial ischemic injury in rats by HMGB2 via ROS.

High-mobility group box (HMGB) family is related to inflammatory diseases. We investigated whether serum HMGB2 levels are related to myocardial infarction (MI) severity and major adverse cardiac events (MACE) during MI. We included 432 consecutive patients with ST-segment elevation myocardial infarction and 312 controls. Serum HMGB2 levels were significantly higher in MI patients than in controls. Increased HMGB2 levels were associated with MACE and negatively with ejection fraction in MI patients. HMGB2 was an independent determinant of MACE in logistic regression analysis. HMGB2 protein (10 µg) or saline was injected intramyocardially in MI rats, with or without coadministration of the NADPH oxidase inhibitor apocynin. After 72 h, pathological, echocardiographic, and hemodynamic examinations showed that HMGB2 increased infarct size and worsened cardiac function in MI rats. Moreover, HMGB2 administration enhanced reactive oxygen species (ROS) production, cell apoptosis, inflammation, and autophagosome clearance impairment, which were attenuated by coadministration of apocynin or knock down of receptor for advanced glycation end products (RAGE). In conclusion, increased serum HMGB2 levels are associated with MI severity and MACE at 1 mo. HMGB2 promotes myocardial ischemic injury in rats and hypoxic H9C2 cell damage via ROS provoked by RAGE.NEW & NOTEWORTHY We demonstrate that serum high-mobility group box 2 is associated with major adverse cardiac events at 1 mo in myocardial infarction patients. Mechanistically, high-mobility group box 2 promotes reactive oxygen species production via receptor for advanced glycation end products signaling in ischemic myocardium, thereby aggravating cell apoptosis, inflammation, and autophagosome clearance impairment. This study reveals that high-mobility group box 2 is a novel factor enhancing ischemic injury in myocardial infarction.

Clinical utility of the ratio between circulating fibrinogen and fibrin (ogen) degradation products for evaluating coronary artery disease in type 2 diabetic patients.

BACKGROUND: We investigated whether and to what extent the ratio between circulating fibrinogen (Fg) and its degradation products (FDP) reflects the severity of coronary artery disease (CAD) in type 2 diabetic patients. METHODS: Plasma levels of Fg and FDP were determined, and Fg/FDP ratio was calculated in 344 consecutive patients with type 2 diabetes and chest pain on exertion undergoing coronary angiography. The severity of CAD was evaluated by the number of significant CAD (>50% luminal diameter narrowing) and Gensini score. RESULTS: Plasma Fg was higher, but Fg/FDP ratio was lower in patients with significant CAD (n = 255) compared with those without (n = 89), due to a disproportionate increase in FDP. Fg and FDP correlated positively, while Fg/FDP ratio negatively, with the number of diseased coronary arteries and the tertile of Gensini score (all P values for trend < 0.01). After adjusting for age, sex, risk factors for CAD, lipid profiles, glycosylated hemoglobin A1c, creatinine, leukocyte count, and high-sensitivity C-reactive protein, Fg/FDP ratio remained an independent determinant for multivessel coronary disease (MVD) (odds ratio [OR], 0.869; 95% confidence interval [CI], 0.788-0.958, P = 0.005) and high tertile of Gensini score (OR, 0.797, 95% CI, 0.682-0.930, P = 0.004). The area under the curve of Fg/FDP ratio was larger than that of Fg for predicting the presence of MVD (0.647 vs. 0.563, P = 0.048) and Gensini score ≥ 30 (0.656 vs. 0.538, P = 0.026). CONCLUSIONS: Elevated plasma Fg and FDP level and reduced Fg/FDP ratio are associated with presence of CAD, and Fg/FDP ratio is superior to Fg in reflecting severe coronary atherosclerosis for patients with type 2 diabetes.