Increase in urinary markers during the acute phase reflects the degree of chronic tubulointerstitial injury after ischemia-reperfusion renal injury

Association of urinary liver-type fatty acid-binding protein with outcomes after adrenalectomy for unilateral primary aldosteronism

BACKGROUND AND AIMS

This study explored the association between urinary liver-type fatty acid-binding protein to creatinine (uL-FABP-cre) ratio and postoperative clinical failure in unilateral primary aldosteronism (PA) patients undergoing adrenalectomy.

MATERIALS AND METHODS

Data from the Taiwan Primary Aldosteronism Investigation Group database were analyzed, including patients with unilateral PA who had adrenalectomy between December 2015 and October 2018. Statistical methods included generalized additive modeling, logistic regression analysis, net reclassification improvement (NRI), and the C statistic.

RESULTS

In the study cohort of 131 patients (mean age 52.3 ± 10.8 years; 43.5% male), 117 achieved clinical success, while 14 experienced clinical failure. A uL-FABP-cre ratio ≥5 predicted clinical failure (odds ratio: 6.22, p = 0.005). Subgroup analysis revealed its efficacy in predicting clinical failure in patients with BMI ≥ 24 kg/m2, normokalemia, or <5 years of hypertension. Furthermore, incorporating uL-FABP-cre ratio into the Primary Aldosteronism Surgical Outcome (PASO) score significantly improved predictive ability. The addition increased the C statistic from 0.671 to 0.762 (p < 0.01) and improved category-free NRI by 0.675 (p = 0.014).

CONCLUSION

A uL-FABP-cre ratio ≥5 accurately predicted clinical failure post-adrenalectomy in unilateral PA, enhancing PASO score's identification of high-risk patients for postoperative clinical failure.

Combining robust urine biomarkers to assess chronic kidney disease progression

BACKGROUND

Urinary biomarkers may improve the prediction of chronic kidney disease (CKD) progression. Yet, data reporting the applicability of most commercial biomarker assays to the detection of their target analyte in urine together with an evaluation of their predictive performance are scarce.

METHODS

30 commercial assays (ELISA) were tested for their ability to quantify the target analyte in urine using strict (FDA-approved) validation criteria. In an exploratory analysis, LASSO (Least Absolute Shrinkage and Selection Operator) logistic regression analysis was used to identify potentially complementary biomarkers predicting fast CKD progression, determined as the ⁵¹CrEDTA clearance-based measured glomerular filtration rate (mGFR) decline (>10% per year) in a subsample of 229 CKD patients (mean age, 61 years; 66% men; baseline mGFR, 38 mL/min) from the NephroTest prospective cohort.

FINDINGS

Among the 30 assays, directed against 24 candidate biomarkers, encompassing different pathophysiological mechanisms of CKD progression, 16 assays fulfilled the FDA-approved criteria. LASSO logistic regressions identified a combination of five biomarkers including CCL2, EGF, KIM1, NGAL, and TGF-α that improved the prediction of fast mGFR decline compared to the kidney failure risk equation variables alone: age, gender, mGFR, and albuminuria. Mean area under the curves (AUC) estimated from 100 re-samples was higher in the model with than without these biomarkers, 0.722 (95% confidence interval 0.652-0.795) vs. 0.682 (0.614-0.748), respectively. Fully-adjusted odds-ratios (95% confidence interval) for fast progression were 1.87 (1.22, 2.98), 1.86 (1.23, 2.89), 0.43 (0.25, 0.70), 1.10 (0.71, 1.83), 0.55 (0.33, 0.89), and 2.99 (1.89, 5.01) for albumin, CCL2, EGF, KIM1, NGAL, and TGF-α, respectively.

INTERPRETATION

This study provides a rigorous validation of multiple assays for relevant urinary biomarkers of CKD progression which combination may improve the prediction of CKD progression.

FUNDING

This work was supported by Institut National de la Santé et de la Recherche Médicale, Université de Paris, Assistance Publique Hôpitaux de Paris, Agence Nationale de la Recherche, MSDAVENIR, Pharma Research and Early Development Roche Laboratories (Basel, Switzerland), and Institut Roche de Recherche et Médecine Translationnelle (Paris, France).

Serum and Urinary Neutrophil Gelatinase-Associated Lipocalin Are Not Associated With Serum Redox Parameters in Amateur Athletes After an Ultramarathon

Objective

To evaluate the relationship between oxidative stress and NGAL levels in blood and urine of amateur athletes after participating in a 100 km ultramarathon.

Methodology

The sample was composed of seven athletes, submitted to anthropometric assessment, cardiopulmonary exercise test, collection of urine and blood, measurement of body weight. The rate of perceived exertion (RPE), competition duration, heart rate (HR), energy expenditure and oxygen consumption (V'O2") were also measured during the event. The energy consumption during the race was verified at its end. The analyses were based on the means (M) and respective standard deviations (SD), with statistical significance set at 5% (p < 0.05). Paired t-test was used for comparison between the periods before and after the competition, and Pearson's correlation coefficient was used to measure the linear correlation between quantitative variables.

Results

Body mass index (BMI) of the sample was 25.75 kg/m2 ± 3.20, body fat percentage 18.54% ± 4.35% and V'O2"max 48.87% ± 4.78. Glucose, cortisol, and neutrophil gelatinase-associated lipocalin (NGAL) (p < 0.01) as well as glutathione peroxidase (GPx) active were higher after the race when compared to basal values. Moreover, lactate, creatinine, microalbuminuria, and glomerular filtration rate (GFR) (p < 0.001) were also higher after the race. After the competition, there was a significant correlation only between serum NGAL and creatinine, which was classified as strong and positive (r: 0.77; p < 0.05). There was a significant reduction (p < 0.05) of body weight after the event (72.40 kg ± 9.78) compared to before it (73.98 kg ± 10.25). In addition, we found an increase of RPE (p < 0.001) after the race. The competition lasted 820.60 min (±117.00), with a 127.85 bpm (±12.02) HR, a 2209.72 kcal ± 951.97 energy consumption, 7837.16 kcal ± 195.71 energy expenditure, and 28.78 ml/kg/min-1 (±4.66) relative V'O2"max.

Conclusion

The lack of correlation between oxidative stress biomarkers and serum and urine NGAL suggests that NGAL is more sensitive to inflammatory processes than to ROS levels.

Angiotensin II type 1a receptor loss ameliorates chronic tubulointerstitial damage after renal ischemia reperfusion

We investigate whether suppressing the activation of the angiotensin II type 1a receptor (AT1a) can ameliorate severe chronic tubulointerstitial damage (TID) after renal ischemia reperfusion (IR) using AT1a knockout homozygous (AT1a^−/−) male mice. To induce severe chronic TID after renal IR, unilateral renal ischemia was performed via clamping of the right renal pedicle in both AT1a^−/− and wild-type (AT1a^+/+) mice for 45 min. While marked renal atrophy and severe TID at 70 days postischemia was induced in the AT1a^+/+ mice, such a development was not provoked in the AT1a^−/− mice. Although the AT1a^+/+ mice were administered hydralazine to maintain the same systolic blood pressure (SBP) levels as the AT1a^−/− mice with lower SBP levels, hydralazine did not reproduce the renoprotective effects observed in the AT1a^−/− mice. Acute tubular injury at 3 days postischemia was similar between the AT1a^−/− mice and the AT1a^+/+ mice. From our investigations using IR kidneys at 3, 14, and 28 days postischemia, the multiple molecular mechanisms may be related to prevention of severe chronic TID postischemia in the AT1a^−/− mice. In conclusion, inactivation of the AT1 receptor may be useful in preventing the transition of acute kidney injury to chronic kidney disease.

Sepsis-Associated Acute Kidney Disease

Introduction

About one-third of critically ill patients with acute kidney injury (AKI) develop persistently decreased kidney function, known as acute kidney disease (AKD), which may progress to chronic kidney disease (CKD). Although sepsis is the most common cause of AKI, little is known about sepsis-associated AKD.

Methods

Using data from a large randomized trial including 1341 patients with septic shock, we studied patients with stage 2 or 3 AKI on day 1 of hospitalization. We defined AKD as a persistently reduced glomerular filtration rate for >7 days. In addition to clinical data, we measured several urinary biomarkers (tissue inhibitor of metalloproteinases-2 and insulin-like growth factor-binding protein 7 [TIMP-2∗IGFBP7], neutrophil gelatinase-associated lipocalin [NGAL], kidney injury molecule-1 [KIM-1], liver-type fatty acid binding protein, and type 4 collagen) at 0, 6, and 24 hours, to predict AKD.

Results

Of 598 patients, 119 (19.9%) died within 7 days, 318 (53.2%) had early reversal of AKI within the first 7 days, whereas 161 (26.9%) developed AKD. In patients with early reversal, 45 (14.2%) had relapsed AKI after early reversal, and only about one-third of these recovered. Among patients developing AKD, only 15 (9.3%) recovered renal function prior to discharge. Male sex, African American race, and underlying CKD were more predominant in patients developing AKD. None of the biomarkers tested performed well for prediction of AKD, although NGAL modestly increased the performance of a clinical model.

Conclusions

AKD is common in patients with septic shock, especially among African American males and those with underlying CKD. Existing AKI biomarkers have limited utility for predicting AKD but might be useful together with clinical variables. Novel predictive biomarkers for renal recovery are needed.

The Possibility of Urinary Liver-Type Fatty Acid-Binding Protein as a Biomarker of Renal Hypoxia in Spontaneously Diabetic Torii Fatty Rats

BACKGROUND

Renal hypoxia is an aggravating factor for tubulointerstitial damage, which is strongly associated with renal prognosis in diabetic kidney disease (DKD). Therefore, urinary markers that can detect renal hypoxia are useful for monitoring DKD.

OBJECTIVE

To determine the correlation between urinary liver-type fatty acid-binding protein (L-FABP) and renal hypoxia using a novel animal model of type 2 diabetes.

METHODS

Male spontaneously diabetic Torii (SDT) fatty rats (n = 6) were used as an animal model of type 2 diabetes. Age- and sex-matched Sprague-Dawley (SD) rats (n = 8) were used as controls. Body weight, systolic blood pressure, and blood glucose levels were measured at 8, 12, 16, and 24 weeks of age. Urine samples and serum and kidney tissues were collected at 24 weeks of age. Microvascular blood flow index (BFI) was measured using diffuse correlation spectroscopy before sampling both the serum and kidneys for the evaluation of renal microcirculation at the corticomedullary junction.

RESULTS

Obesity, hyperglycemia, and hypertension were observed in the SDT fatty rats. Focal glomerular sclerosis, moderate interstitial inflammation, and fibrosis were significantly more frequent in SDT fatty rats than in SD rats. While the frequency of peritubular endothelial cells and phosphoendothelial nitric oxide synthase levels were similar in both types of rats, the degree of renal hypoxia-inducible factor-1α (HIF-1α) expression was significantly higher (and with no change in renal vascular endothelial growth factor expression levels) in the SDT fatty rats. Urinary L-FABP levels were significantly higher and renal microvascular BFI was significantly lower in the SDT fatty rats than in the SD rats. Urinary L-FABP levels exhibited a significant positive correlation with renal HIF-1α expression and a significant negative correlation with renal microvascular BFI.

CONCLUSIONS

Urinary L-FABP levels reflect the degree of renal hypoxia in DKD in a type 2 diabetic animal model. Urinary L-FABP may thus prove useful as a renal hypoxia marker for monitoring DKD in patients with type 2 diabetes in clinical practice.