Urinary Neutrophil Gelatinase-Associated Lipocalin (NGAL) Predicts Renal Function Decline in Patients With Glomerular Diseases

Kidney urinary biomarkers in patients with branched-chain amino acid and cobalamin metabolism defects

There is a clinical need for early detection of chronic kidney disease (CKD) in patients with organic acidurias. We measured kidney markers in a longitudinal study over 5 years in 40 patients with methylmalonic aciduria (Mut0 ), propionic aciduria (PA), cobalamin A (CblA), and cobalamin C (CblC) deficiencies. Neutrophil gelatinase-associated lipocalin (NGAL), calprotectin (CLP), kidney injury molecule-1 (KIM-1), dickkopf-3 (DKK-3), albumin and beta-2-microglobulin (B2MG) in urine, as well as cystatin C (CysC) in serum were quantified. In Mut0 patients, mean concentrations of B2MG, KIM-1, and DKK-3 were elevated compared with healthy controls, all markers indicative of proximal tubule damage. In PA patients, mean B2MG, albumin, and CLP were elevated, indicating signs of proximal tubule and glomerulus damage and inflammation. In CblC patients, mean B2MG, NGAL, and CLP were increased, and considered as markers for proximal and distal tubule damage and inflammation. B2MG, was elevated in all three diseases, and correlated with DKK-3 in Mut0 /CblA and with eGFR(CysC) and KIM-1 in PA patients, respectively. None of the markers were elevated in CblA patients. Significant deterioration of kidney function, as determined by steady increase in CysC concentrations was noted in seven patients within the observation period. None of the investigated biomarker profiles showed a clear increase or added value for early detection. In conclusion, we identified disease-specific biomarker profiles for inflammation, tubular, and proximal damage in the urine of Mut0 , PA, and CblC patients. Whether these biomarkers can be used for early detection of CKD requires further investigation, as significant kidney function deterioration was observed in only a few patients.

Folate Deficiency Enhanced Inflammation and Exacerbated Renal Fibrosis in High-Fat High-Fructose Diet-Fed Mice

The prevalence of obesity and chronic kidney disease (CKD) is increasing simultaneously and rapidly worldwide. Our previous study showed that folate deficiency increased lipid accumulation and leptin production of adipocytes. Whether folate plays a role in CKD, particularly obesity-related nephropathy remains unclear. To investigate the effects of folate deficiency on CKD in diet-induced obese mice, four groups of male C57BL/6 mice were fed either a normal-fat diet (NF) with folate (NF+f); NF without folate (NF-f); high-fat high-fructose diet (HFF) with folate (HFF+f); or HFF without folate (HFF-f) for 12 months during the study. The results showed that HFF increased not only body weight, fasting blood glucose, total cholesterol (TC), low-density lipoprotein (LDL)-cholesterol, and blood pressure, but also cytokines levels, such as interleukin (IL)-2, interferon (IFN)-γ, IL-17A/F, IL-6, monocyte chemoattractant protein (MCP)-1, and transforming growth factor (TGF)-β1. The indicators of kidney failure including urinary protein, neutrophil gelatinase-associated lipocalin (NGAL), renal type I and IV collagen deposits and leptin content, and serum creatinine were also increased by HFF. Folate-deficient diets further elevated serum TC, LDL-cholesterol, IL-6, tumor necrosis factor (TNF)-α, MCP-1, TGF-β1, and leptin, but decreased IL-10 level, and thus exacerbated renal fibrosis. To investigate the possible mechanisms of folate deficiency on renal injury, phosphorylation of pro-fibrosis signaling molecules, including signal transducer and activator of transcription (STAT)3 and small mothers against decapentaplegic (Smad)2/3, were assayed. Both HFF and folate deficiency significantly increased the phosphorylation of STAT3 and Smad2/3, suggesting synergistic effects of HFF-f on chronic renal inflammation and fibrosis. In conclusion, the results demonstrated that folate deficiency might aggravate inflammatory status and enhance renal fibrosis.

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).

Fecal and Urinary Adipokines as Disease Biomarkers

The use of biomarkers is of great clinical value for the diagnosis and prognosis of disease and the assessment of treatment efficacy. In this context, adipokines secreted from adipose tissue are of interest, as their elevated circulating levels are associated with a range of metabolic dysfunctions, inflammation, renal and hepatic diseases and cancers. In addition to serum, adipokines can also be detected in the urine and feces, and current experimental evidence on the analysis of fecal and urinary adipokine levels points to their potential as disease biomarkers. This includes increased urinary adiponectin, lipocalin-2, leptin and interleukin-6 (IL-6) levels in renal diseases and an association of elevated urinary chemerin as well as urinary and fecal lipocalin-2 levels with active inflammatory bowel diseases. Urinary IL-6 levels are also upregulated in rheumatoid arthritis and may become an early marker for kidney transplant rejection, while fecal IL-6 levels are increased in decompensated liver cirrhosis and acute gastroenteritis. In addition, galectin-3 levels in urine and stool may emerge as a biomarker for several cancers. With the analysis of urine and feces from patients being cost-efficient and non-invasive, the identification and utilization of adipokine levels as urinary and fecal biomarkers could become a great advantage for disease diagnosis and predicting treatment outcomes. This review article highlights data on the abundance of selected adipokines in urine and feces, underscoring their potential to serve as diagnostic and prognostic biomarkers.

Urinary Neutrophil Gelatinase Associated Lipocalin: A Novel Biomarker Determining Steroid Responsiveness in Nephrotic Syndrome

BACKGROUND

Urinary Neutrophil Gelatinase Associated Lipocalin (uNGAL) has been demonstrated to be a powerful marker of progression in chronic kidney disease. The present study was done to find out the ability of uNGAL as a biomarker to differentiate steroid-sensitive nephrotic syndrome (SSNS), steroid-dependent nephrotic syndrome (SDNS), and steroid-resistant nephrotic syndrome (SRNS) from each other.

METHOD

The cross-sectional study included 45 patients with Idiopathic Nephrotic Syndrome (INS) (15 each of SSNS, SDNS, and SRNS). uNGAL was measured by ELISA. Demographic profile of patients with INS, lab parameters including Serum albumin, cholesterol, urinary albumin, creatinine, etc., were estimated using standard laboratory methods. Various statistical methods were used to assay the usefulness of NGAL as a diagnostic marker.

RESULTS

Among the three groups, the median value of uNGAL was 8.68 ng/ml in SSNS, higher in SDNS (32.8 ng/ml), and highest in the SRNS group (50 ng/ml). The receiver operating curve (ROC) was generated for uNGAL to differentiate between SDNS and SSNS. Cut-off 13.26 ng/ml had a sensitivity of 86.7% and specificity of 97.4%, PPV 92.9%, and NPV 87.5 % with an area under the curve (AUC) of 0.958. Another ROC was generated for uNGAL to differentiate between SRNS and SDNS, and cut-off 40.02 ng/ml had a sensitivity of 80% and specificity of 86.7% with an AUC of 0.907. A similar result was observed when ROC was generated to differentiate SRNS from SSNS and SDNS combined.

CONCLUSION

uNGAL can distinguish between SSNS, SDNS, and SRNS.

Plasma or Urine Neutrophil Gelatinase-Associated Lipocalin (NGAL): Which Is Better at Detecting Chronic Kidney Damage in Type 2 Diabetes?

Background and study aims—Albuminuria, defined as an enhanced urine albumin/creatinine ratio (ACR) on a spot sample, is a validated biomarker of glomerular damage. However, it cannot always detect early renal failures in patients with type 2 diabetes (T2D), thus prompting the search for more sensitive and specific parameters. Herein, we investigated the differential role of plasma and urine neutrophil-gelatinase-associated lipocalin (NGALp,—NGALu) for the detection of diabetic kidney disease (DKD). Methods—Traditional glomerular (serum creatinine, cystatin C, ACR) damage biomarkers were evaluated in 84 patients with T2D and in 21 metabolically healthy controls. Diabetic patients were stratified into four groups based on T2D duration (less or more than 5 years) and presence and severity of DKD (early- or advanced-stage), as defined by the ACR and estimated glomerular filtration rate (eGFR). NGALp and NGALu were determined by ELISA methodology and compared among groups. Results—There was no difference in NGALp and NGALu levels between the metabolically healthy individuals and the age-matched, newly diagnosed diabetic patients in the absence of DKD. However, in contrast to NGALu, NGALp was found to be substantially increased in patients with long-standing diabetes without biochemical evidence of DKD, closely mirroring the modest, but still accelerated, decline in the eGFR typical of this chronic dysmetabolic condition, and remained overexpressed throughout the stages of DKD progression. Increased NGALu levels were, instead, rather specific in patients with biochemical evidence of DKD (i.e., marked by increased albuminuria), regardless of T2D duration. Spearman’s correlation and regression analyses showed that patient age and T2D duration could exert a strong positive impact exclusively on NGALp concentrations (ρ = 0.419, p < 0.001 for age; ρ = 0.581, p < 0.001 for T2D), and none on NGALu. Furthermore, receiver operating characteristic (ROC) analysis showed the best performance of NGALp compared to NGALu for the detection of DKD (AUC = 0.817 for NGALp, AUC = 0.711 for NGALu). Conclusions—Our data suggest a different pathophysiological and predictive role for urine and plasma NGAL in the context of T2D and DKD.