Experimental evidence that preexisting chronic kidney disease is a risk factor for acute kidney injury

Elevation of serum human epididymis protein 4 (HE4) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) as predicting factors for the occurrence of acute kidney injury on chronic kidney disease: a single-center retrospective self-control study

Objectives: To evaluate whether novel biomarkers of renal injury, serum HE4 and NT-proBNP could predict acute kidney injury (AKI) on chronic kidney disease (CKD) (A on C) and assess the specificity and efficiency of serum creatinine (SCr), HE4 and NT-proBNP in identifying potential AKI. Meanwhile, the potential early-warning value of HE4 and NT-proBNP in CKD patients was explored. Methods: We performed a single-center, retrospective cohort study of 187 adult CKD patients. 32 AKI (grades 1-2) patients with pre-existing CKD (stages 3-5) were Group 1, 59 patients of CKD (stages 4-5) were Group 2. Another 96 patients of CKD (stages 1-3) were Group 3. All patients received general treatments, Group 1 patients received Chinese herb formulation (Chuan Huang Fang-Ⅱ, CHF-Ⅱ) simultaneously. These 155 CKD (stages 1-5) without AKI patients were observed for descriptive analysis. Results: HE4 in Group 1 (860.63 ± 385.40) was higher than that in Group 2 (673.86 ± 283.58) before treatments. BUN, SCr, UA, NGAL, IL18, HE4 and NT-proBNP in Group 1 were lower, while eGFR was higher (p < 0.01, after vs. before treatments). In Group 1, both HE4 and NT-proBNP were positively correlated with SCr (respectively r = 0.549, 0.464) before treatments. The diagnostic performance of serum HE4 and NT-proBNP for A on C was 351.5 pmol/L, 274.5 pg/mL as the optimal cutoff value Area Under Curve (AUC) 0.860 (95% CI: 0.808 - 0.913, p < 0.001), [AUC 0.775 (95% CI: 0.697 - 0.853, p < 0.001), with a sensitivity and specificity of 100% and 66.5%, 87.5% and 48.8%, respectively]. In Group 2, serum HE4 was correlated with SCr (r = 0.682, p < 0.01) before treatments. Serum HE4 and NT-proBNP were elevated in advanced CKD stages, and were increased as CKD stages progressed with statistical significance. Conclusion: This work indicated serum HE4 and NT-proBNP should elevate in A on C and CKD patients, HE4 is positively correlated with the disease severity, and patients with higher HE4 and NT-proBNP usually have poorer prognosis. Thus, serum HE4 and NT-proBNP are impactful predictors of A on C. Additionally, serum HE4 and NT-proBNP have the potential to evaluate clinical efficacy of A on C.

Novel predictive biomarkers for acute injury superimposed on chronic kidney disease

INTRODUCTION AND OBJECTIVES

Chronic kidney disease (CKD) is a risk factor for the development of acute kidney injury (AKI). Recent studies have revealed numerous biomarkers eligible for AKI prediction. However, the expression and performance of AKI biomarkers in acute injury superimposed on preexisting CKD (AonC) remain elusive. The aim of this study was to evaluate whether biomarkers which robustly expressed in acute kidney injury could predict acute injury based on CKD.

MATERIALS AND METHODS

Mice were classified into cohorts: AKI, CKD, AonC and sham. The AonC model mice were subjected to renal bilateral ischemia/reperfusion (I/R) injury fourteen days after intraperitoneally administrated with 20mg/kg aristolochic acid. Severity of acute ischemic injury was stratified by clamping the dissected bilateral renal arteries with non-traumatic microvascular clips for 20 or 35min. The AKI mice were induced with renal bilateral I/R injury and CKD mice were crafted with 20mg/kg aristolochic acid administrated intraperitoneally. Histology, genetic and protein expression of biomarkers were measured in three cohorts.

RESULTS

We found that serum creatinine dramatically increased in severe (sAonC) but not in moderate (mAonC) injury mice. Upregulation of Kidney injury molecule-1 (KIM-1) mRNA, tissue inhibitor of metalloproteinase-2 (TIMP-2), Syndecan-1 (SDC-1) mRNA and insulin-like growth factor binding protein-7 (IGFBP7) protein indicated the onset of mAonC. An increase in neutrophil gelatinase-associated lipocalin (NGAL), rhomboid-like protein 2 (RHBDL2), Syndecan-1 (SDC-1) mRNA and protein, and a decrease in IGFBP7 protein were associated with sAonC.

CONCLUSIONS

Our study revealed the variational expression of AKI biomarkers in AonC kidneys, and uncovered IGFBP7 protein can be used as a sensitive biomarker to predict and differentiate AonC severity. The performance of RHBDL2 and SDC-1 in predicting severe AonC was promising, providing new biomarkers for predicting AonC.

Acetaminophen administration and the risk of acute kidney injury: a self-controlled case series study

Background

Acetaminophen (APAP) is frequently used for analgesia and is considered safer than nonsteroidal anti-inflammatory drugs (NSAIDs) for the kidneys. However, there is little epidemiological evidence of the association between APAP and acute kidney injury (AKI).

Objectives

To examine the association between APAP and AKI using the self-controlled case series (SCCS) method, which is a novel strategy to control between-person confounders by comparing the risk and reference periods in each patient.

Methods

We performed SCCS in 1,871 patients (39.9% female) who were administered APAP and subsequently developed AKI, by reviewing electronically stored hospital information system data from May 2011 to July 2016. We used conditional Poisson regression to compare each patient’s risk and reference period. As a time-varying confounder, we adjusted the status of liver and kidney functions, systemic inflammation, and exposure to NSAIDs.

Results

We identified 5,650 AKI events during the 260,549 person-day observation period. The unadjusted incidences during the reference and exposure periods were 2.01/100 and 3.12/100 person-days, respectively. The incidence rate ratio adjusted with SCCS was 1.03 (95% confidence interval [CI]: 0.95–1.12). When we restricted endpoints as stage 2 AKI- and stage 3 AKI-level creatinine elevations, the incidence rate ratios were 1.20 (95% CI 0.91–1.58) and 1.20 (95% CI 0.62–2.31), respectively, neither of which was statistically significant.

Conclusion

Our findings added epidemiological information for the relationship between APAP administration and AKI development. The results indicated scarce association between APAP and AKI, presumably supporting the general physicians’ impression that APAP is safer for kidney.