Follow Up of Value of the Intrarenal Resistivity Indices and Different Renal Biomarkers for Early Identification of Diabetic Nephropathy in Type 1 Diabetic Patients

O-Linked GlcNAcylation mediates the inhibition of proximal tubule (Na++K+)ATPase activity in the early stage of diabetes mellitus

BACKGROUND

Diabetic kidney disease (DKD) is a severe complication of diabetes mellitus (DM). It has been proposed that modifications in the function of proximal tubule epithelial cells (PTECs) precede glomerular damage during the onset of DKD. This study aimed to identify modifications in renal sodium handling in the early stage of DM and its molecular mechanism.

METHODS

Streptozotocin (STZ)-induced diabetic BALB/c mice (STZ group) and LLC-PK1 cells, a model of PTECs, were used. All parameters were assessed in the 4th week after an initial injection of STZ.

RESULTS

Early stage of DKD was characterized by hyperfiltration and PTEC dysfunction. STZ group exhibited increased urinary sodium excretion due to impairment of tubular sodium reabsorption. This was correlated to a decrease in cortical (Na++K+)ATPase (NKA) α1 subunit expression and enzyme activity and an increase in O-GlcNAcylation. RNAseq analysis of patients with DKD revealed an increase in expression of the glutamine-fructose aminotransferase (GFAT) gene, a rate-limiting step of hexosamine biosynthetic pathway, and a decrease in NKA expression. Incubation of LLC-PK1 cells with 10 μM thiamet G, an inhibitor of O-GlcNAcase, reduced the expression and activity of NKA and increased O-GlcNAcylation. Furthermore, 6-diazo-5-oxo-L-norleucine (DON), a GFAT inhibitor, or dapagliflozin, an SGLT2 inhibitor, avoided the inhibitory effect of HG on expression and activity of NKA associated with the decrease in O-GlcNAcylation.

CONCLUSION

Our results show that the impairment of tubular sodium reabsorption, in the early stage of DM, is due to SGLT2-mediated HG influx in PTECs, increase in O-GlcNAcylation and reduction in NKA expression and activity.

Significance of Neutrophil Gelatinase-Associated Lipocalin as a Biomarker for the Diagnosis of Diabetic Kidney Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising marker for the diagnosis of diabetic kidney disease (DKD), but its utility is currently debated. This meta-analysis aims to evaluate the diagnostic value of NGAL for DKD.

METHOD

MEDLINE, Embase, -Cochrane Library, CNKI, and CBM databases were searched up to April 13, 2019. In bivariate random-effect models, the diagnostic performance of NGAL for DKD was assessed using pooled estimates of sensitivity, specificity, likelihood ratio, diagnostic odds ratio, and hierarchical summary receiver-operating characteristic analysis.

RESULTS

Nineteen studies were eligible for the meta-analysis. Serum NGAL had a pooled sensitivity and specificity of 0.79 (95% confidence intervals [CI] 0.60-0.91) and 0.87 (0.75-0.93) (7 studies, 1,238 patients). The pooled positive likelihood ratio (LR+) and negative likelihood ratio (LR-) were 5.97 (3.03-11.76) and 0.24 (0.11-0.51). For urine NGAL, the pooled sensitivity, specificity, LR+, and LR- were 0.85 (0.74-0.91), 0.74 (0.57-0.86), 3.26 (1.87-5.67), and 0.21 (0.12-0.35), respectively (10 studies, 1,369 patients). The pooled sensitivity and specificity for kidney disease in normoalbuminuric patients with diabetes was 0.90 (0.82-0.95) and 0.97 (0.90-0.99) for both serum NGAL and 0.94 (0.87-0.98) and 0.90 (0.81-0.96) for urine NGAL (4 studies, 221 patients). NGAL appeared to perform similarly in subgroup analysis.

CONCLUSION

The meta-analysis has shown that NGAL may be useful for DKD classification and also has a potential diagnostic value for normoalbuminuric kidney disease. Large-scale prospective studies are required to clarify its role in the diagnosis and risk stratification of patients with DKD.

Usefulness of Doppler ultrasound for the early diagnosis of diabetic nephropathy in type 1 diabetes mellitus

PURPOSE

Early diagnosis and management of diabetic nephropathy (DN) might prevent or delay its progression to end-stage renal disease. The purpose of this study was to investigate whether changes in the duplex Doppler resistivity index (RI) are useful for the early identification of renal involvement in children and adolescents with insulin-dependent diabetes mellitus and associated conditions.

MATERIALS AND METHODS

A total of 49 diabetic patients (two groups: 21 with DN and 28 without DN) were included in this study. DN was defined as 30-300 mg/l of albumin excretion in a random urine sample. The RI of the main renal arteries and their intrarenal branches (arcuate, interlobar) were evaluated with duplex Doppler ultrasound and correlated with age, renal length, duration of diabetes, and laboratory examinations.

RESULTS

The mean age did not significantly differ between the two groups. The patients with DN had a significantly longer duration of type 1 diabetes (p = 0.02). The majority of patients (90.5%) had mild renal involvement with microalbuminuria and normal renal function. The mean RI was normal in both groups of patients, with no significant difference between the two groups.

CONCLUSION

The RI did not increase in the early clinical stage of DN and was not a reliable marker for the screening of DN in patients with type 1 diabetes mellitus.

Evaluation of renal markers of T1D in Sprague-Dawley exposed to 2-aminoanthracene

The incidence of type 1 diabetes (T1D) and its associated risks of chronic kidney disease or end-stage renal disease development are on the rise. T1D is an autoimmune disease in which insulin-producing beta cells are destroyed. Increased incidence of T1D has been suggested to be a result of environmental factors such as exposure to polycyclic aromatic hydrocarbons (PAHs). 2-aminoanthracene (2AA) is a PAH that has been associated with the onset of early diabetic symptoms. This study was conducted to assess if 2AA dietary ingestion would induce T1D renal injuries. To accomplish study goals, Sprague-Dawley rats were assigned into three 2AA dietary (0, 50, and 100 mg/kg-2AA) ingestion groups for 12 weeks. Animals were evaluated for various morphometric indices, clinical markers, and gene expression. The rats in the 100 mg/kg group lost 5% less weight than the other treatment groups and converted roughly 3% more of their food intake into body mass. Renal histopathology indicated no significant difference between groups. The kidney weight per bodyweight of the 100 mg/kg treatment group was 30.1% greater than the control group. Creatinine concentration of the 100 mg/kg group was 46.2% greater than the control group. Serum glucose levels were significantly elevated in rats exposed to 2AA. On the contrary, serum albumin concentration was significantly reduced in 2AA-treated rats. T1D and genetic markers of renal injury such as FABP1, SPP1, IL-1B, and IL-7 were elevated in treated groups. These results suggest that 2AA may induce the early diabetic renal injuries.

Urine NGAL as an early biomarker for diabetic kidney disease: accumulated evidence from observational studies

Objectives: Urine neutrophil gelatinase-associated lipocalin (NGAL) was found to increase in diabetic kidney disease (DKD). However, the clinical value of urine NGAL as diagnostic indicators in DKD remains to be clarified. Methods: Relevant studies were systematically retrieved from PubMed, Embase, Web of Science, and the Cochrane Library. Stratified analyses and regression analyses were performed. Results: Fourteen studies with 1561 individuals were included in our analysis, including 1204 cross-sectional participants and 357 cohort participants. For the cross-sectional studies, the pooled sensitivity and specificity of NGAL in the diagnosis of DKD were 0.82 (95% confidence interval (CI): 0.75-0.87) and 0.81 (95% CI: 0.68-0.90), respectively. The pooled diagnostic odds ratio was 19 (95% CI: 11-33), and the overall area under the curve was 0.88 (95% CI: 0.84-0.90). For the cohort studies, the pooled sensitivity and specificity of NGAL in the diagnosis of DKD were 0.96 (95% CI: 0.91-0.98) and 0.89 (95% CI: 0.84-0.92), respectively. The overall area under the curve was 0.98, indicating good discriminative ability of NGAL as biomarkers for DKD. Conclusions: Urine NGAL, as the early diagnostic marker of DKD, might have the high diagnostic value, especially in cohort studies.