Assessment of the diagnostic value of different biomarkers in relation to various stages of diabetic nephropathy in type 2 diabetic patients

Serum angiopoietin-2: a promising biomarker for early diabetic kidney disease in children and adolescents with type 1 diabetes

Albuminuria has been considered the golden standard biomarker for diabetic kidney disease (DKD), but appears once significant kidney damage has already occurred. Angiopoietin-2 (Angpt-2) has been implicated in the development and progression of DKD in adults. We aimed to explore the association of serum Angpt-2 levels with DKD in children and adolescents with type 1 diabetes mellitus (T1DM) of short duration (3-5 years) and to evaluate the predictive power of serum Angpt-2 in the early detection of DKD prior to the microalbuminuric phase. The current cross-sectional study included 90 children divided into three age and sex-matched groups based on urinary albumin-to-creatinine ratio (UACR): microalbuminuric diabetic group (n = 30), non-albuminuric diabetic group (n = 30), and control group (n = 30). All participants were subjected to anthropometric measurements, serum Angpt-2 and fasting lipid profile (total cholesterol, triglycerides, LDL-C, HDL-C, and Non-HDL-C) assessment. Glomerular filtration rate was estimated based on serum creatinine (eGFR-Cr). Higher serum Angpt-2 levels were detected in both diabetic groups compared to controls and in microalbuminuric compared to non-albuminuric diabetic group. There was no detected significant difference in eGFR-Cr values across the study groups. Serum Angpt-2 was positively correlated with triglycerides, LDL, Non-HDL-C, HbA1c, and UACR, while UACR, HbA1c, and Non-HDL-C were independent predictors for serum Angpt-2. Serum Angpt-2 at level of 137.4 ng/L could discriminate between microalbuminuric and non-albuminuric diabetic groups with AUC = 0.960 and at level of 115.95 ng/L could discriminate between the non-albuminuric diabetic group and controls with AUC = 0.976.Conclusion: Serum Angpt-2 is a promising potent biomarker for the detection of early stage of DKD in childhood T1DM before albuminuria emerges. What is Known? • Urine albumin-to-creatinine ratio (UACR) and glomerular filtration rate (GFR) are the golden standard but late biomarkers for DKD. • Angiopoietin-2 has been implicated in the development and progression of DKD in adults with diabetes, but has not been explored in T1DM children with DKD. What is New? • Higher serum angiopoietin-2 was detected in diabetic groups compared to controls and in microalbuminuric compared to non-albuminuric group. • Angiopoietin-2 correlated positively with triglycerides, LDL, Non-HDL-C, HbA1c, and UACR. • Serum angiopoietin-2 is a promising early diagnostic biomarker for DKD in children with T1DM.

Pathomechanisms of Diabetic Kidney Disease

The worldwide occurrence of diabetic kidney disease (DKD) is swiftly rising, primarily attributed to the growing population of individuals affected by type 2 diabetes. This surge has been transformed into a substantial global concern, placing additional strain on healthcare systems already grappling with significant demands. The pathogenesis of DKD is intricate, originating with hyperglycemia, which triggers various mechanisms and pathways: metabolic, hemodynamic, inflammatory, and fibrotic which ultimately lead to renal damage. Within each pathway, several mediators contribute to the development of renal structural and functional changes. Some of these mediators, such as inflammatory cytokines, reactive oxygen species, and transforming growth factor β are shared among the different pathways, leading to significant overlap and interaction between them. While current treatment options for DKD have shown advancement over previous strategies, their effectiveness remains somewhat constrained as patients still experience residual risk of disease progression. Therefore, a comprehensive grasp of the molecular mechanisms underlying the onset and progression of DKD is imperative for the continued creation of novel and groundbreaking therapies for this condition. In this review, we discuss the current achievements in fundamental research, with a particular emphasis on individual factors and recent developments in DKD treatment.

Renoprotective Potency of Sitagliptin versus Pioglitazone in Type 2 Diabetic Patients: Impact on LncMIAT

Background: Diabetes mellitus (DM) represents one of the most important reasons for chronic kidney diseases due to the high level of blood glucose that destructs blood vessels. Objective: The present study focused on investigating the protective impact of sitagliptin on kidney complication in type 2 diabetes mellitus (T2DM) patients in comparison to pioglitazone to examine which has the superior effect against the nephritic complication of DM. Methods: Eighty adult subjects were classified into four groups: control group, pioglitazone-treated T2DM patients (P group), sitagliptin-treated T2DM patients for less than one year (SL group), and sitagliptin-treated T2DM patients for more than one year (SM group). Blood samples were withdrawn from all subjects for analysis of neutrophil gelatinase-associated lipocalin (NGAL), vanin-1, kidney injury molecule-1 (KIM-1), glyoxalase-1 (Glo-1), methylglyoxal (MG), cystatin-C, and interleukin-18 (IL-18) using competitive ELISA kits. Also, long noncoding myocardial infarction associated transcript (lncMIAT) was measured in whole blood using qRT-PCR. Results: The present study revealed that the lncMIAT expression level was significantly higher in the P group as compared to the SL group, SM group, or healthy control group. Additionally, serum NGAL, vanin-1, KIM-1, Glo-1, MG, and cystatin-C were significantly higher in the P group and SL group as compared to the SM group and healthy control group. Conclusion: Sitagliptin protected the kidney through downregulation of lncMIAT besides amelioration of kidney injury marker levels, which was more preferable than in pioglitazone therapy.

Identification of a novel immune landscape signature as effective diagnostic markers related to immune cell infiltration in diabetic nephropathy

Background

The study aimed to identify core biomarkers related to diagnosis and immune microenvironment regulation and explore the immune molecular mechanism of diabetic nephropathy (DN) through bioinformatics analysis.

Methods

GSE30529, GSE99325, and GSE104954 were merged with removing batch effects, and different expression genes (DEGs) were screened at a criterion |log2FC| >0.5 and adjusted P <0.05. KEGG, GO, and GSEA analyses were performed. Hub genes were screened by conducting PPI networks and calculating node genes using five algorithms with CytoHubba, followed by LASSO and ROC analysis to accurately identify diagnostic biomarkers. In addition, two different GEO datasets, GSE175759 and GSE47184, and an experiment cohort with 30 controls and 40 DN patients detected by IHC, were used to validate the biomarkers. Moreover, ssGSEA was performed to analyze the immune microenvironment in DN. Wilcoxon test and LASSO regression were used to determine the core immune signatures. The correlation between biomarkers and crucial immune signatures was calculated by Spearman analysis. Finally, cMap was used to explore potential drugs treating renal tubule injury in DN patients.

Results

A total of 509 DEGs, including 338 upregulated and 171 downregulated genes, were screened out. “chemokine signaling pathway” and “cell adhesion molecules” were enriched in both GSEA and KEGG analysis. CCR2, CX3CR1, and SELP, especially for the combination model of the three genes, were identified as core biomarkers with high diagnostic capabilities with striking AUC, sensitivity, and specificity in both merged and validated datasets and IHC validation. Immune infiltration analysis showed a notable infiltration advantage for APC co-stimulation, CD8+ T cells, checkpoint, cytolytic activity, macrophages, MHC class I, and parainflammation in the DN group. In addition, the correlation analysis showed that CCR2, CX3CR1, and SELP were strongly and positively correlated with checkpoint, cytolytic activity, macrophages, MHC class I, and parainflammation in the DN group. Finally, dilazep was screened out as an underlying compound for DN analyzed by CMap.

Conclusions

CCR2, CX3CR1, and SELP are underlying diagnostic biomarkers for DN, especially in their combination. APC co-stimulation, CD8+ T cells, checkpoint, cytolytic activity, macrophages, MHC class I, and parainflammation may participate in the occurrence and development of DN. At last, dilazep may be a promising drug for treating DN.

MicroRNAs Associated with Chronic Kidney Disease in the General Population and High-Risk Subgroups-A Systematic Review

The potential utility of microRNAs (miRNAs) as diagnostic or prognostic biomarkers, as well as therapeutic targets, for chronic kidney disease (CKD) has been advocated. However, studies evaluating the expression profile of the same miRNA signatures in CKD report contradictory findings. This review aimed to characterize miRNAs associated with CKD and/or measures of kidney function and kidney damage in the general population, and also in high-risk subgroups, including people with hypertension (HTN), diabetes mellitus (DM) and human immunodeficiency virus (HIV) infection. Medline via PubMed, Scopus, Web of Science, and EBSCOhost databases were searched to identify relevant studies published in English or French languages on or before 30 September 2022. A total of 75 studies fulfilled the eligibility criteria: CKD (n = 18), diabetic kidney disease (DKD) (n = 51) and HTN-associated CKD (n = 6), with no study reporting on miRNA profiles in people with HIV-associated nephropathy. In individuals with CKD, miR-126 and miR-223 were consistently downregulated, whilst in DKD, miR-21 and miR-29b were consistently upregulated and miR-30e and let-7a were consistently downregulated in at least three studies. These findings suggest that these miRNAs may be involved in the pathogenesis of CKD and therefore invites further research to explore their clinical utility for CKD prevention and control.

Molecular Pathways of Diabetic Kidney Disease Inferred from Proteomics

Diabetic kidney disease (DKD) affects an estimated 20-40% of type 2 diabetes patients and is among the most prevalent microvascular complications in this patient population, contributing to high morbidity and mortality rates. Currently, changes in albuminuria status are thought to be a primary indicator of the onset or progression of DKD, yet progressive nephropathy and renal impairment can occur in certain diabetic individuals who exhibit normal urinary albumin levels, emphasizing the lack of sensitivity and specificity associated with the use of albuminuria as a biomarker for detecting diabetic kidney disease and predicting DKD risk. According to the study, a non-invasive method for early detection or prediction of DKD may involve combining proteomic analytical techniques such second generation sequencing, mass spectrometry, two-dimensional gel electrophoresis, and other advanced system biology algorithms. Another category of proteins of relevance may now be provided by renal tissue biomarkers. The establishment of reliable proteomic biomarkers of DKD represents a novel approach to improving the diagnosis, prognostic evaluation, and treatment of affected patients. In the present review, a series of protein biomarkers that have been characterized to date are discussed, offering a theoretical foundation for future efforts to aid patients suffering from this debilitating microvascular complication.

Transcriptome Analysis Identifies Oxidative Stress Injury Biomarkers for Diabetic Nephropathy

BACKGROUND

The early diagnosis of diabetic nephropathy (DN) is essential for improving the prognosis and effectively manage patients affected with this disease. The standard biomarkers, including albuminuria and glomerular filtration rate, are not very precise. New molecular biomarkers are needed to more accurately identify DN and better predict disease progression. Characteristic DN biomarkers can be identified using transcriptomic analysis.

AIM OF THE STUDY

To evaluate the transcriptomic profile of controls (CTRLs, n = 15), patients with prediabetes (PREDM, n = 15), patients with type-2 diabetes mellitus (DM2, n = 15), and patients with DN (n = 15) by microarray analysis to find new biomarkers. RT-PCR was then used to confirm gene biomarkers specific for DN.

MATERIALS AND METHODS

Blood samples were used to isolate RNA for microarray expression analysis. 26,803 unique gene sequences and 30,606 LncRNA sequences were evaluated-Selected gene biomarkers for DN were validated using qPCR assays. Sensitivity, specificity, and area under the curve (AUC) were calculated as measures of diagnostic accuracy.

RESULTS

The DN transcriptome was composed of 300 induced genes, compared to CTRLs, PREDM, and DM-2 groups. RT-qPCR assays validated that METLL22, PFKL, CCNB1 and CASP2 genes were induced in the DN group compared to CTRLs, PREDM, and DM-2 groups. The ROC analysis for these four genes showed 0.9719, 0.8853, 0.8533 and 0.7748 AUC values, respectively.

CONCLUSION

Among induced genes in the DN group, we found that CASP2, PFKL and CCNB1 may potentially be used as biomarkers to diagnose DN. Of these, METLL22 had the highest AUC score, at 0.9719.

Assessment of Serum Free Light Chains as a Marker of Diabetic Nephropathy; A Cross-Sectional Study in the Kumasi Metropolis

Aims

Although traditional tests such as serum urea, creatinine, and microalbuminuria have been widely employed in the diagnosis of diabetic nephropathy, their sensitivity and accuracy are limited because kidney damage precedes the excretion of these biomarkers. This study investigated the role of serum free light chains in the disease manifestation of diabetic nephropathy.

Materials and Methods

Using a cross-sectional design we recruited 107 diabetes mellitus out-patients who visited the Diabetes and Renal Disease Clinics at the Komfo Anokye Teaching Hospital, Manhyia District Hospital, and Suntreso Government Hospital all in Ghana from November 2019 to February 2020. Five (5) mls of blood was collected from each participant and analyzed for fasting blood glucose (FBG) urea, creatinine, immunoglobulin free light chains. Urine samples were obtained and analyzed for albumin. Anthropometric characteristics were also measured. Data were analyzed using descriptive analysis, analysis of variance (ANOVA) test, Tukey HSD post hoc, and Kruskal Wallis test. Chi-squared test was used to examine if there are significant associations with the indicators of interest. In addition, Spearman’s correlation was used to test for associations between appropriate variables. Receiver operating characteristic analysis (ROC) was also performed to assess the diagnostic performance of free light chains.

Results

The mean age of studied participants was 58.2 years (SD: ± 11.1), 63.2% were females and most of the participants were married (63.0%). The mean FBG of the studied participants was 8.0mmol/L (SD: ± 5.86), and the average duration of diabetes mellitus (DM) was 11.88 years (SD: ± 7.96). The median serum Kappa, Lambda, and Kappa: Lambda ratios for the studied participants were 18.51 (15.63-24.18), 12.19(10.84-14.48), and 1.50(1.23-1.86) respectively. A positive correlation was observed between albuminuria and; Kappa (rs=0.132; p=0.209), and Lambda (rs=0.076; p=0.469). However, a negative correlation was observed between albuminuria and K: L ratio (rs=-0.006; p=0.956).

Conclusions

The current study observed an increasing trend in the levels of free light chains and degree of diabetic nephropathy, although not statistically significant. The exploration of serum free light chains as a better marker of diabetic nephropathy showed very promising results but further studies are required to elucidate its predictive value as a diagnostic tool for diabetic nephropathy.

The potential use of urinary transferrin, urinary adiponectin, urinary Retinol Binding Protein, and serum zinc alpha 2 glycoprotein levels as novel biomarkers for early diagnosis of diabetic nephropathy: A case-control study

BACKGROUND AND AIMS

The level of albuminuria is used to evaluate diabetic nephropathy (DN). However, to detect or predict the early stages of DN, better biomarkers are needed.

METHODS

This study is a case-control observational study. 80 Egyptians participated in the study: 60 patients with type 2 diabetes mellitus (T2DM) were divided into three groups (20 patients each), and 20 healthy subjects with matched age and gender were used as controls. Demographic and laboratory data were analyzed. An enzyme-linked immunosorbent assay was used to determine the levels of four biomarkers of DN; urinary adiponectin (ADP), urinary transferrin, serum Zinc Alpha 2 Glycoprotein (ZAG), and urinary Retinol Binding Protein (RBP).

RESULTS

The levels of DN biomarkers urinary ADP, transferrin, RBP, and serum, ZAG were significantly higher in patients with T2DM than in controls. The ROC curve of the validity of the simultaneous use of all four biomarkers in predicting albuminuria indicates a sensitivity of 90% and a specificity of 90%. The Area Under the Curve (AUC) was 0.948, the 95% confidence interval was 0.998-0.897, and the p-value was 0.001.

CONCLUSIONS

In patients with T2DM, urine adiponectin, transferrin, RBP, and serum ZAG concentration may be useful biomarkers in the early diagnosis of DN. A further longitudinal prospective study is required to explore the potential utility of these biomarkers.

Effects of Smoking on Diabetic Nephropathy

Diabetes is a systemic metabolic disease with serious complications that cause significant stress on the healthcare system. Diabetic kidney disease is the primary cause of end stage renal disease globally and its progression is accelerated by various factors. Another major healthcare hazard is tobacco consumption and smoking has deleterious effects on renal physiology. Prominent factors are defined as sympathetic activity, atherosclerosis, oxidative stress and dyslipidemia. This review aims to enlighten the mechanism underlying the cumulative negative effect of simultaneous exposure to hyperglycemia and nicotine.

Plasmatic osteopontin and vascular access dysfunction in hemodialysis patients: a cross-sectional, case-control study (The OSMOSIS Study)

BACKGROUND AND AIMS

Despite close follow-up of patients with native arteriovenous fistulas (AVFs), up to 10% experience thrombosis each year. The OSMOSIS Study (Osteopontin as a Marker of Stenosis) tested the hypothesis that the systemic osteopontin level, a pro-inflammatory mediator related to vascular remodelling and intimal hyperplasia, increases in AVF stenosis, and may be used in clinical surveillance.

METHODS

Our cross-sectional study compared the level of plasmatic osteopontin (pOPN) between patients with a well-functioning AVF (control group) and patients who required revision of their AVF due to stenosis (stenosis group). Blood samples were collected before dialysis (control group) or before intervention (stenosis group) from the AVF arm, and from the opposite arm as a within-subject control. pOPN level was measured by enzyme-linked immunosorbent assay.

RESULTS

A total of 76 patients were included in the study. Baseline characteristics were similar between the groups (mean age, 70 years; men, 63%; AVF duration, 39 months), apart from prevalence of type 2 diabetes (T2D) (control group, 33%; stenosis group, 57%; p = 0.04). pOPN levels were similar between the AVF arm and the contralateral arm (551 ± 42 ng/mL vs. 521 ± 41 ng/mL, respectively, p = 0.11, paired t-test). Patients in the stenosis group displayed a higher pOPN level than patients in the control group (650.2 ± 59.8 ng/mL vs. 460.5 ± 61.2, respectively, p = 0.03; two-way ANOVA). T2D was not identified as an associated factor in a multivariate analysis (p = 0.50).

CONCLUSIONS

The level of pOPN in hemodialysis patients was associated with the presence of AVF stenosis requiring intervention. Thus, its potential as a diagnostic biomarker should be assessed in a vascular access surveillance program.

Diagnostic Accuracy of Serum Cystatin C for Early Recognition of Nephropathy in Type 2 Diabetes Mellitus

Objectives

Diabetic nephropathy is one of the major complications that develop over time in type 2 diabetes mellitus (T2DM). This prospective study was conducted to assess the diagnostic accuracy of serum cystatin C in detecting diabetic nephropathy at earlier stages.

Materials and Methods

This study was undertaken on 50 cases of T2DM and 50 healthy subjects as controls. Demographic and anthropometric data and blood and urine samples were collected. The concentration of serum cystatin C (index test) and traditional markers of diabetic nephropathy, serum creatinine, and urinary microalbumin (the reference standard) were estimated. Similarly, blood glucose, glycated haemoglobin (HbA1c), triglycerides, total cholesterol, high-density lipoprotein (HDL) cholesterol, and urinary creatine were measured.

Results

The mean ± SD serum cystatin C was significantly higher in T2DM as compared to control (1.07 ± 0.38 and 0.86 ± 0.12 mg/dl, respectively, p < 0.001). The mean ± SD bodyweight, BMI, W : H ratio, pulse, SBP, and DBP were 66.4 ± 12.6 kg, 26.2 ± 5.6 kg/m², 1.03 ± 0.09, 78 ± 7, 125 ± 16 mm of Hg, and 77 ± 9 mm of Hg, respectively, in cases. A significant difference in HDL cholesterol (p=0.018) and serum cystatin C (p < 0.001) was observed among different grades of nephropathy. Cystatin C had a significant positive correlation with age (r = 0.323, p=0.022), duration of T2DM (r = 0.326, p=0.021), and UACR (r = 0.528, p < 0.001) and a significant negative correlation with eGFR CKD-EPI cystatin C (r = −0.925, p < 0.001). The area under ROC curve for serum cystatin C (0.611, 95% CI: 0.450–0.772) was greater than for serum creatinine (0.429, 95% CI: 0.265–0.593) though nonsignificant.

Conclusion

Serum cystatin C concentration increases with the progression of nephropathy and duration of diabetes in Nepalese T2DM patients suggesting cystatin C as a potential marker of renal impairment in T2DM patients.

Effect of French maritime pine bark extract supplementation on metabolic status and serum vascular cell adhesion molecule-1 levels in patients with type 2 diabetes and microalbuminuria

OBJECTIVES

This study investigated the effect of French maritime pine bark extract (PBE) supplementation on metabolic parameters, vascular cell adhesion molecule 1 (VCAM-1), urinary albumin-to-creatinine ratio (UACR), and anthropometric indexes in patients with type 2 diabetes (T2DM) and microalbuminuria.

DESIGN

This randomized, double-blind, placebo-controlled clinical trial was conducted on 46 patients with T2DM and the evidence of microalbuminuria aged 30-65 years.

SETTING

Patients were recruited from the endocrinology clinic of Sina hospital (Tabriz, Iran) from March 2018 to April 2019.

INTERVENTIONS

The subjects were randomly assigned to receive two capsules/day each containing 50mg of PBE or placebo for eight weeks.

MAIN OUTCOME MEASURES

Glycemic parameters, serum VCAM-1 and lipid profile, UACR, and anthropometric indexes were measured for all patients at baseline and the end of the study.

RESULTS

PBE supplementation significantly reduced glycosylated hemoglobin, VCAM-1, total cholesterol, UACR, waist circumference, and waist-to-height ratio compared to the placebo group at the end of the study (all P < 0.05). Changes in fasting blood glucose, insulin, triglyceride, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were not significant between the two groups (all P > 0.05).

CONCLUSIONS

The study findings demonstrated some favorable effects of PBE supplementation on glycemic control, serum VCAM-1 and total cholesterol levels, and microalbuminuria, as well as abdominal obesity in patients with T2DM.

Differential Expressions of Ki-67, Bcl-2, and Apoptosis Index in Endometrial Cells of Women With and Without Type II Diabetes Mellitus and Their Correlation with Clinicopathological Variables

The objective of this study was to investigate proliferation, apoptosis, and antiapoptotic molecule expression in endometrial cells of reproductive-aged women with and without type II diabetes mellitus (T2D). In this case-control study, a total of 80 endometrial tissue specimens from reproductive-aged women (35 in the proliferative phase and 45 in the secretory phase) were examined. The age and body mass index (BMI) were matched between the groups. Formalin-fixed and paraffin-embedded endometrial tissue samples were used for immunohistochemistry analysis. The presence of proliferation was evaluated with Ki-67 expression, antiapoptotic function of cells was evaluated with Bcl-2 expression, and apoptosis was evaluated with terminal deoxynucleotidyl transferase (TUNEL) immunoreactivity in both the glandular epithelium and stroma of endometrial tissue samples from women with and without T2D. Ki-67 expression in the glandular epithelium and Bcl-2 expression in both the glandular epithelium and stroma were significantly higher in endometrial tissue samples of women in the T2D group than the control group (p = 0.0008, p = 0.0022, and p = 0.0261, respectively). TUNEL immunoreactivity was significantly lower in the glandular epithelium of women in the T2D group than the control group (p = 0.0001). Glandular Ki-67 expression correlated positively with BMI, use of insulin, and hemoglobin A1c level (p = 0.0034, p = 0.0154, and p = 0.0011, respectively). Glandular Bcl-2 expression correlated positively with BMI and duration of T2D (p = 0.0090 and p = 0.0109, respectively). Stromal Bcl-2 expression correlated positively with duration of T2D (p = 0.0069). TUNEL immunoreactivity in the glandular epithelium correlated negatively with duration of T2D (p = 0.0340) and positively with the use of oral antidiabetic agents (p = 0.0226). Compared to age and BMI-matched controls, women with T2D experienced increased cell proliferation and decreased apoptosis in the glandular epithelium and increased antiapoptotic function in both the glandular epithelium and stromal cells. High BMI values in women with diabetes seemed to contribute to increased cell proliferation and increased antiapoptotic function in the glandular epithelium but not the stromal cells.

Current Challenges and Future Perspectives of Renal Tubular Dysfunction in Diabetic Kidney Disease

Over decades, substantial progress has been achieved in understanding the pathogenesis of proteinuria in diabetic kidney disease (DKD), biomarkers for DKD screening, diagnosis, and prognosis, as well as novel hypoglycemia agents in clinical trials, thereby rendering more attention focused on the role of renal tubules in DKD. Previous studies have demonstrated that morphological and functional changes in renal tubules are highly involved in the occurrence and development of DKD. Novel tubular biomarkers have shown some clinical importance. However, there are many challenges to transition into personalized diagnosis and guidance for individual therapy in clinical practice. Large-scale clinical trials suggested the clinical relevance of increased proximal reabsorption and hyperfiltration by sodium-glucose cotransporter-2 (SGLT2) to improve renal outcomes in patients with diabetes, further promoting the emergence of renal tubulocentric research. Therefore, this review summarized the recent progress in the pathophysiology associated with involved mechanisms of renal tubules, potential tubular biomarkers with clinical application, and renal tubular factors in DKD management. The mechanism of kidney protection and impressive results from clinical trials of SGLT2 inhibitors were summarized and discussed, offering a comprehensive update on therapeutic strategies targeting renal tubules.

Role of urinary podocalyxin in early diagnosis of diabetic nephropathy

Introduction. Podocyte injury has been reported as an early feature of DN therefore, the assessment of podocyte injury can be accomplished by estimation of podocalyxin in urine. This study aimed to estimate the urinary podocalyxin levels and to determine the sensitivity and specificity of this biomarker for early detection of DN.Materials and methods. A total of 90 patients with type 2 diabetes mellitus (T2DM) were included in this cross-sectional study. Sixty of them were without diagnosed DN, and 30 with diagnosed DN. A control group consisted of 30 healthy subjects. All patients with T2DM were divided into three subgroups according to urinary microalbumin/creatinine ratio (UM/CR): normoalbuminuric, microalbuminuric and macroalbuminuric patients. Urine samples, were used for measurement of podocalyxin by ELISA, creatinine and microalbumin. Fasting venous blood samples was collected for biochemical analyses.Results. The levels of urinary podocalyxin (u-PDX) were higher in patients with T2DM compared to control subjects and a statistically significant difference among studied subgroups regarding u-PDX was found (p < 0.05). Levels of u-PDX are increasing gradually with the degree of DN (p < 0.029). u-PDX levels were positively correlated with UM/CR (r = 0.227, p = 0.002). A cut-off level of 43.8 ng/ml u-PDX showed 73.3% sensitivity and 93.3% specificity to detect DN in early stage. A cut-off level of 30 mg/g UM/CR showed 41.5% sensitivity and 90% specificity in predicting DN. u-PDX was elevated in 48,2% of normoalbuminuric patients.Conclusion. Urinary podocalyxin be useful and more sensitive and specific marker in early detection of DN than microalbuminuria.

Evaluation of early biomarkers of renal dysfunction in diabetic patients

Objectives:

To evaluate 2 renal tubular enzymes; urinary neutrophil gelatinase-associated lipocalin (uNGAL), and urinary N-acetyl-beta-D-glucosaminidase (uNAG), and serum Cystatin C as candidate biomarkers for early diagnosis of early stage of diabetic nephropathy (DB) in patients with type 2 diabetes mellitus (T2DM).

Methods:

This cross-sectional study was carried out at King Abdulaziz University Hospital (KAUH), Jeddah, Saudi Arabia during the period between May 2017 and May 2018 and was conducted on 86 patients with T2DM. Patients were classified according to their albumin/creatinine ratio (ACR) into 3 groups; a normal albuminuria group with ACR <30 mg/g creatinine, a moderately increased albuminuria group with ACR: 30-299 mg/g creatinine, and a severely increased albuminuria group with ACR ≥300 mg/g. Healthy adults were recruited as a control group. Urine uNGAL, uNAG, and serum Cystatin C were measured in all patients.

Results:

Compared with healthy control, diabetic patients with normal albuminuria excreted significantly higher levels of uNGAL (p<0.001). In addition, significantly elevated uNGAL, uNAG and cystatin C levels were observed in moderately increased albuminuria and severely increased albuminuria groups when compared to the control and normoalbuminuric groups (p<0.001). urinary neutrophil gelatinase-associated lipocalin, urinary N-acetyl-beta-D-glucosaminidase and Cystatin C showed a positive correlation with fasting blood glucose (FBG), HbA1c, duration of diabetes, urea, creatinine, and ACR.

Conclusion:

Our results indicated that uNGAL could be a sensitive biomarker for early renal dysfunction in diabetic patients while uNAG and serum Cystatin C might have prognostic value.

MicroRNAs in Chronic Kidney Disease: Four Candidates for Clinical Application

There are still major challenges regarding the early diagnosis and treatment of chronic kidney disease (CKD), which is in part due to the fact that its pathophysiology is very complex and not clarified in detail. The diagnosis of CKD commonly is made after kidney damage has occurred. This highlights the need for better mechanistic insight into CKD as well as improved clinical tools for both diagnosis and treatment. In the last decade, many studies have focused on microRNAs (miRs) as novel diagnostic tools or clinical targets. MiRs are small non-coding RNA molecules that are involved in post-transcriptional gene regulation and many have been studied in CKD. A wide array of pre-clinical and clinical studies have highlighted the potential role for miRs in the pathogenesis of hypertensive nephropathy, diabetic nephropathy, glomerulonephritis, kidney tubulointerstitial fibrosis, and some of the associated cardiovascular complications. In this review, we will provide an overview of the miRs studied in CKD, especially highlighting miR-103a-3p, miR-192-5p, the miR-29 family and miR-21-5p as these have the greatest potential to result in novel therapeutic and diagnostic strategies.

Relation of Copeptin with Diabetic and Renal Function Markers Among Patients with Diabetes Mellitus Progressing Towards Diabetic Nephropathy

BACKGROUND

Arginine vasopressin (AVP) plays an important role in the pathophysiology of Diabetes Mellitus (DM) and its related complications like diabetic nephropathy. Copeptin is considered as a reliable surrogate biomarker of AVP. If raised levels of copeptin in diabetic patients are detected earlier, prognosis of DM can be improved by timely modulating the treatment strategy.

AIMS OF THE STUDY

The study is therefore planned to assess copeptin levels in different groups of DM and in healthy controls to suggest a better and reliable biomarker for progressive stages of DM.

METHODS

Subjects were recruited as controls, pre diabetes, DM without nephropathy and diabetic nephropathy. Serum copeptin levels were measured by ELISA. While, Blood Urea Nitrogen (BUN), creatinine, Glycosylated Hemoglobin (HbA1c) and spot urinary albumin creatinine ratio (UACR) were done using spectrophotometry. Statistical analysis was done using ANOVA and Pearson's correlation tests on SPSS.

RESULTS

The average copeptin levels were 215.096 pg/mL. Copeptin levels were significantly elevated in subjects with positive family history of DM (p = 0.025), levels were also raised in pre diabetes kpatients (252.85 pg/mL) as compared to other groups. Copeptin levels were also correlated with HbA1c r = 0.171 (p = 0.101), BUN r = 0.244 (p = 0.007), creatinine r = 0.215 (p = 0.018), UACR r = 0.375 (p = <0.001) and GFR r = 0.215 (p = <0.019).

CONCLUSION

The significant correlation of copeptin with diabetic and renal biomarkers, along with its positive association with family history of DM support its' role as an early and reliable biomarker of DM and its associated nephropathy.

Salivary and serum interleukin-17A and interleukin-18 levels in patients with type 2 diabetes mellitus with and without periodontitis

OBJECTIVE

Interleukin (IL)-17A and IL-18 have been proposed to play important roles in periodontitis and type 2 diabetes mellitus (DM), but human data are conflicting. The present study aimed to investigate the roles of IL-17A and IL-18 in periodontitis and DM by measuring salivary and serum levels, respectively.

MATERIALS AND METHODS

A total of 49 participants with type 2 DM and 25 control subjects without type 2 DM were recruited. A periodontal screening and recording (PSR) index (0, 1-2, 3, and 4) was used to classify whether these subjects had periodontitis. Salivary and serum IL-17A and IL-18 levels were measured by enzyme-linked immunosorbent assay. Multiple linear regression analyses were used to evaluate the associations between these cytokines and clinical parameters.

RESULTS

Salivary IL-17A levels were not significantly different between patients with DM and controls, however, the levels were significantly higher in controls with periodontitis than those without periodontitis (p = 0.031). Salivary IL-17A levels were significantly associated with the PSR index (β = 0.369, p = 0.011). Multiple linear regression analyses revealed the association of salivary IL-18 levels and fasting plasma glucose (β = 0.270, p = 0.022) whereas serum IL-18 levels were associated with HbA1C (β = 0.293, p = 0.017). No correlation between salivary and serum levels of IL-17A and IL-18 was found.

CONCLUSION

Salivary IL-17A was strongly associated with periodontitis, whereas salivary IL-18 was associated with FPG and serum IL-18 was associated with HbA1C. These results suggest the role of these cytokines in periodontal inflammation and DM.

The role of activation of KАTP channels on hydrogen sulfide induced renoprotective effect on diabetic nephropathy

This work aims to investigate the renal effect of hydrogen sulfide (H₂ S), in the experimentally induced diabetic nephropathy, besides the role of activation of АТP-sensitive potassium (K_АTP ) channel in that effect. Thirty-two adult male albino rats randomly divided into four groups: Control, streptozotocin-induced diabetic (diabetic nephropathy [DN]), DN+NaHS (the H₂ S inducer), and DN+NaHS+Glibenclamide (a selective K_АTP channel blocker) groups. Results showed that kidney functions in the diabetic group improved by NaHS proved by the significant decrease in the measured renal injury markers when compared with the diabetic group with an obvious role of inflammation and oxidative stress. However, the improved kidney functions produced by NaHS was reduced by the combination with Glibenclamide. Glibenclamide combination led also to a significant increase in renal total antioxidant capacity, in addition to a significant decrease in renal total nitric oxide (NO) level. Аccordingly, the results from the present work revealed that the renoprotective effects of H₂ S in the case of DN through its effects on renal tissue antioxidants and NO can be partially dependent on activation of K_АTP channels, while its effect on renal tissue proinflammatory cytokines is independent of it.

Variation in the Level of Thyroid Markers in Association with Inflammation in Patients with Type 2 Diabetes

BACKGROUND

A possible relationship between thyroid hormones and glucose metabolism in diabetes has already been established.

OBJECTIVES

We aimed to evaluate the thyroid function markers and their relationship with inflammation, which is considered as a pathogenic condition of diabetes.

METHODS

This cross-sectional study included 276 patients with type 2 diabetes. Serum levels of thyroid (TSH, FT4, and FT3) and inflammatory markers (CRP, IL-6, and TNF-α) were measured.

RESULTS

The mean age of the subjects was 55.2 years and mean diabetes duration of 16.8 years. The inflammatory markers showed significant differences with the tertiles of TSH and thyroid hormones. TSH was significantly correlated with inflammatory markers, IL-6 (r = 0.13, P = 0.020) and TNF-α (r = 0.17, P = 0.003), while FT4 had a correlation only with TNF-α (r = 0.25, P = <0.001). FT3 was negatively correlated with inflammatory marker IL-6 (r = -0.14, P = 0.020), HbA1c (r = -0.12, P = 0 .040), and HOMA-IR (r = -0.17, P = 0.010).

CONCLUSION

Abnormalities in the thyroid hormone metabolism are related to the increased inflammatory activity as well as insulin resistance, and are associated with the disorders of glucose metabolism.

Urinary NGAL and RBP Are Biomarkers of Normoalbuminuric Renal Insufficiency in Type 2 Diabetes Mellitus

Objectives

As a screening index of diabetic kidney disease (DKD), urinary albumin/creatine ratio (UACR) is commonly used. However, approximately 23.3%-56.6% of DKD patients with estimated glomerular filtration rate (eGFR) < 60 ml/min per 1.73 m² are normoalbuminuric. Thus, urinary biomarkers of nonalbuminuric renal insufficiency in type 2 diabetes mellitus (T2DM) patients are urgently needed.

Methods

This cross-sectional study enrolled 209 T2DM patients with normoalbuminuria whose diabetes duration was more than 5 years. The patients were classified into two groups, NO-CKD (eGFR ≥ 60 ml/min per 1.73 m², n = 165) and NA-DKD (eGFR < 60 ml/min per 1.73 m², n = 44). Levels of urinary neutrophil gelatinase-associated lipocalin (NGAL), retinol-binding protein (RBP), plasminogen activator inhibitor-1 (PAI-1), vascular cell adhesion molecule-1 (VCAM-1), and E-cadherin were detected, and their correlations with eGFR, plasma TNF-α, IL-6, endothelin-1 (ET-1), and 8-hydroxydeoxyguanosine (8-OHdG) were assessed.

Results

Among patients with renal insufficiency, 26.0% was normoalbuminuric. Compared to the NO-CKD group, the NA-DKD group was older with lower hemoglobin (HB) levels and higher systolic blood pressure (SBP), plasma TNF-α, IL-6, and 8-OHdG levels. Logistic regression analysis suggested that age, TNF-α, and 8-OHdG were independent risk factors for nonalbuminuric renal insufficiency. Compared to the NO-CKD group, the NA-DKD group exhibited significant increases in urinary NGAL and RBP levels but not PAI-1, VCAM-1, and E-cadherin. Urinary NGAL and RBP both correlated negatively with eGFR and positively with plasma IL-6 and 8-OHdG. Multiple linear regression indicated NGAL (β = -0.287, p = 0.008) and RBP (β = -44.545, p < 0.001) were independently correlated with eGFR.

Conclusion

Age, plasma TNF-α, and 8-OHdG are independent risk factors for renal insufficiency in T2DM patients with normoalbuminuria. Urinary NGAL and RBP can serve as noninvasive biomarkers of normoalbuminuric renal insufficiency in T2DM.

The association between thyroid dysfunction (TD) and diabetic kidney disease (DKD) in type 2 diabetes mellitus (T2DM)

BACKGROUND

Epidemiological studies have identified an association between thyroid dysfunction (TD) and various kidney diseases. In this study, the prevalence of TD in type 2 diabetic mellitus (T2DM) patients with diabetic kidney disease (DKD) was evaluated to analyse the potential association between TD and DKD in T2DM patients.

METHODOLOGY

A total of 2108 T2DM patients from Anhui Provincial Hospital were recruited in this study. Demographic and clinical characteristics were collected from 834 T2DM patients with DKD and 1274 T2DM patients without DKD (non-DKD). All patients were stratified into a number of groups based on UACR (urine albumin-to-creatinine ratio) or eGFR (estimated glomerular filtration rate): (a) A1: normoalbuminuria (<30), A2: microalbuminuria (30-300) and A3: macroalbuminuria (>300); (b) F1: normal filtration (60-139), F2: hyper filtration (≥140) and F3: low filtration (<60).

RESULTS

Significant differences were observed between the non-DKD and DKD groups (P < .05) in age, sex ratio, duration, systolic blood pressure, total cholesterol, low density lipoprotein cholesterol, serum creatinine, blood urea nitrogen, free triiodothyronine (FT3), free thyroxine (FT4) and sensitive thyrotropin hormone (sTSH). The macroalbuminuira and low filtration groups had the lowest levels of FT3 and FT4 and the highest level of sTSH, compared with all other groups (P < .0167). The prevalence of subclinical hypothyroidism in the DKD group was significantly higher than that in the non-DKD group (χ2  = 13.92, P < .01). Logistic regression analysis showed that hypothyroidism was associated with increased UACR or reduced eGFR in T2DM patients. Compared with controls, T2DM patients with hypothyroidism exhibited a higher UACR and urinary excretion of transferrin, as well as a lower excretion of urinary Tamm-Horsfall protein (THP) (P < .0167).

CONCLUSION

Subclinical hypothyroidism is more prevalent in T2DM patients with DKD than in T2DM patients without DKD. Hypothyroidism is associated with albuminuria and decreased eGFR in T2DM patients.

Kruppel-Like Transcription Factor-4 Gene Expression and DNA Methylation Status in Type 2 Diabetes and Diabetic Nephropathy Patients

BACKGROUND/AIM

Diabetic nephropathy (DN) is one of the most serious microvascular complications in diabetic patients. The kruppel-like transcription factor-4 (KLF-4) affects the expression of genes involved in the pathogenesis of DN. The present study aims to identify the KLF-4 expression and DNA methylation (DNAMe) status in patients with type-2 diabetes (T2D) and DN and to reveal the contribution of the KLF-4 to the development of DN.

MATERIAL AND METHODS

The cohort study was performed with blood samples from 120 individuals; T2D group (n = 40), DN group (n = 40) and control group (n = 40). The expression level of the KLF-4 gene was analyzed using the real-time polymerase chain reaction (qRT-PCR) and the methylation profile detected using the methylation-specific PCR (MS-PCR) technique.

RESULTS

According to our findings, KLF-4 mRNA expression in the T2D group was 1.60 fold lower than in the control group (p = 0.001). In the DN group, the expression of KLF-4 mRNA was 2.92-fold less than that of the T2D group (p = 0.001). There was no significant alteration in the DNAMe status among the groups.

CONCLUSION

Our findings showed that regardless of the DNAMe status, KLF-4 gene expression may play a role in the development of T2D and DN. This suggests that the KLF-4 gene may be the target gene in understanding the mechanism of nephropathy, which is the most important complication of diabetes, and planning nephropathy-related treatments, but the data should be supported with more studies.

The Association of Serum hsCRP and Urinary Alpha1-Microglobulin in Patients with Type 2 Diabetes Mellitus

This study aimed to investigate the association of serum hsCRP and urinary A1MG in patients with T2DM. Numerous investigations have proven that serum hypersensitive C-reactive protein (hsCRP) concentration in patients with type 2 diabetes mellitus (T2DM) is increased. Also, increased urinary alpha-1 microglobulin (A1MG) can be an early sign of renal damage, primarily on the proximal tubules in T2DM. Little information is available with respect to the associations of serum hsCRP levels and urinary A1MG in T2DM. A total of 520 patients with T2DM were recruited to participate in this study. Serum hsCRP and UA1MG (urinary alpha1-microglobulin to creatinine ratio), UACR (urinary microalbumin to creatinine ratio), UIGG (urinary immunoglobulin G to creatinine ratio), and UTRF (urinary transferrin to creatinine ratio) were obtained. The association of serum hsCRP level and each urinary protein parameter was analyzed by using the regression analysis, respectively. LnhsCRP was positively associated with the lnUA1MG in all three linear regression models (adjusted β in model 3=0.122, SE=0.027, P<0.001). Furthermore, the high hsCRP group (hsCRP > 3mg/L) was associated with increasing risk of high UA1MG (adjusted OR in model 3=1.610, 95% CI 1.037-2.499, P=0.034) by logistic regression. This study suggests that serum hsCRP levels independently associate with UA1MG in patients with T2DM. Further research is warranted to elucidate these interactions.

IL-18, VCAM-1 and P-selectin as early biomarkers in normoalbuminuric Type 2 diabetes patients

Aim: To investigate the pathophysiological role of different biomarkers in diabetic kidney disease (DKD) among normoalbuminuric patients with a low-estimated glomerular filtration rate (eGFR). Methods: In this cross-sectional study of 200 normoalbuminuric Type 2 diabetes patients, 28 patients (14%) had a low eGFR. Results: The IL-18, VCAM-1 and P-selectin levels were significantly higher at a low eGFR. On analyzing the area under the receiver operating characteristic curve, these biomarkers had significant diagnostic value and have important pathophysiological role in the progression of DKD. Conclusion: Among normoalbuminuric Type 2 diabetes patients, IL-18, VCAM-1 and P-selectin may play a significant role in the prediction of early DKD. Further prospective studies need to be conducted to confirm this observation.

Urinary nephrin is earlier, more sensitive and specific marker of diabetic nephropathy than microalbuminuria

Background

Diabetic nephropathy (DN) is a leading cause of end-stage renal disease. Progressive damage and decline in the number of podocytes often occur in the early stages of DN. Thus, nephrin as a podocyte-specific protein may be regarded as a potential biomarker of early detection of DN. The aim of this study is to determine whether urinary nephrin is an earlier marker in DN than microalbuminuria and to test the significance of urinary nephrin as a marker for early detection of DN.

Methods

Our cross-sectional study included 90 patients with type 2 diabetes mellitus (T2DM), 30 patients with diagnosed DN and 60 patients without diagnosed DN. As a control group, we used 30 healthy subjects. All patients with T2DM were classified into three subgroups according to urinary microalbumin/creatinine ratio (UMCR): normoalbuminuric, microalbuminuric and macroalbuminuric patients. Nephrin in urine was measured by immunoenzyme assay, microalbumin with turbidimetric and creatinine with the photometric method. In blood sera, we measured a few standard biochemical parameters.

Results

Nephrinuria was found to be present in 100% of patients with T2DM and macroalbuminuria, in 88% with microalbuminuria, as well as 82% of patients with T2DM and normoalbuminuria. A concentration of urinary nephrin was significantly increased in all groups of subjects with T2DM compared to the control group (p<0.05). Nephrinuria correlated statistically negative with eGFR (r=-0.54). ROC analysis showed that nephrin has a total predicted probability of 96% in patients with DN.

Conclusions

Urinary nephrin is earlier, more specific and sensitive marker than microalbumin in early detection of DN.

Quantitative contrast-enhanced ultrasound of renal perfusion: a technology for the assessment of early diabetic nephropathy in cynomolgus macaques with type 2 diabetes mellitus

PURPOSE

The aim of this study was to investigate the effectiveness of contrast-enhanced ultrasound (CEUS) in predicting early nephropathy in cynomolgus macaques with spontaneous type 2 diabetes mellitus (T2DM).

METHODS

Six cynomolgus macaques with spontaneous T2DM and six normal cynomolgus macaques (Group 1) were included in this study. The time-intensity curve was used to obtain parameters such as peak values, red blood volume (RBV), red blood flow (RBF), time to peak (TTP), and mean transit time (MTT). Biopsy renal tissue samples were assessed histopathologically. Six cynomolgus macaques with spontaneous T2DM were subgrouped into T2DM without nephropathy group (Group 2) and T2DM with nephropathy group (Group 3) based on histopathological findings.

RESULTS

Peak value had the largest area under the curve comparing with RBF, RBV, TTP, MTT. The sensitivity and specificity of peak value with cut-off value of 38.65 dB for the diagnosis of DN were 98.3% and 83%, respectively. Peak value, RBV, and RBF in Group 3 was significantly decreased compared with Group 1 and Group 2 (P = 0.000, x² = 23.99; P = 0.003, x² = 9.14; P = 0.02, x² = 5.14).

CONCLUSIONS

The perfusion parameter of peak value in CEUS might be useful in predicting early diabetic nephropathy in spontaneous T2DM cynomolgus macaques.

Diagnostic Accuracy of Neutrophil Gelatinase-Associated Lipocalin for Predicting Early Diabetic Nephropathy in Patients with Type 1 and Type 2 Diabetes Mellitus: A Systematic Review and Meta-analysis

BACKGROUND

Currently, there is a lack of prediction markers for diabetic nephropathy (DN) in patients with type 1 and type 2 diabetes mellitus (T1DM/T2DM). The aim of this systematic review and meta-analysis was to evaluate the value of a promising biomarker, neutrophil gelatinase-associated lipocalin (NGAL), in both serum and urine for the diagnosis of early DN in T1DM and T2DM patients with different stages of albuminuria.

METHODS

A comprehensive search was performed on PubMed by 2 reviewers until September 2018. Studies in which (a) the degree of DN was determined according to the urinary albumin/creatinine ratio and (b) NGAL was measured in healthy individuals and in diabetes patients with DN were included in the meta-analysis. For each study, a 2 × 2 contingency table was formulated. Sensitivity, specificity, and other estimates of accuracy were calculated using a bivariate random effects model. The hierarchical summary ROC method was used to pool data and to evaluate the area under the curve (AUC). The sources of heterogeneity were explored by subgroup analysis. Publication bias was assessed using the Deeks test.

RESULTS

The meta-analysis enrolled 22 studies involving 683 healthy individuals and 3249 patients with diabetes, of which 488 were T1DM and 2761 were T2DM patients. Overall, pooled sensitivity and specificity among the different settings analyzed ranged from 0.42 (95% CI, 0.22-0.66) to 1.00 (95% CI, 0.99-1.00) and 0.72 (95% CI, 0.62-0.80) to 0.98 (95% CI, 0.50-1.00) in T2DM patients, respectively. For T1DM patients, the corresponding estimates were 0.71 (95% CI, 0.59-0.81) to 0.89 (95% CI, 0.64-0.97) and 0.72 (95% CI, 0.62-0.80) to 0.79 (95% CI, 0.67-0.87). The AUC of NGAL for T2DM patients ranged from 0.69 (95% CI, 0.65-0.73) to 1.00 (95% CI, 0.99-1.00) in the different settings.

CONCLUSION

The results of this meta-analysis suggest that NGAL in both serum and urine can be considered a valuable biomarker for early detection of DN in diabetes patients.

Urinary N-acetyl-beta-d-glucosaminidase (NAG) with neutrophil gelatinase-associated lipocalin (NGAL) improves the diagnostic value for proximal tubule damage in diabetic kidney disease

Screening for diabetic kidney disease (DKD) remains a challenge; however, there has been an ongoing research to investigate the diagnostic value of different biomarkers to identify DKD. The aim of this study was to assess the diagnostic value of both N-acetyl-beta-d-glucosaminidase (NAG) and neutrophil gelatinase-associated lipocalin (NGAL) in the progression of DKD. This cross-sectional case-control study included 92 type 2 diabetic patients with or without DKD. Urinary NAG and NGAL were measured to evaluate their diagnostic values as biochemical markers related to DKD. Both urinary NAG and NGAL levels were significantly higher among patients with DKD. In multiple linear regression analysis, NAG showed a positive significant association with NGAL in the three different adjusted models, while no significant correlation with fasting blood glucose, glycated hemoglobin, serum creatinine, estimated glomerular filtration rate, and albumin creatinine ratio were observed. The area under the curve for NGAL was 0.659 (p = 0.01) and 0.564 (p = 0.297) for NAG in DKD patients. This study demonstrates the association between urinary NAG and NGAL as a tubular damage marker for DKD although longitudinal studies are needed to evaluate its diagnostic value.

Diabetic nephropathy: An update on pathogenesis and drug development

Diabetic nephropathy (DN) is a major cause of end-stage renal disease and affects a large number of individuals with diabetes. However, the development of specific treatments for DN has not yet been identified. Hence, this review is concisely designed to understand the molecular pathways leading to DN in order to develop suitable therapeutic strategies. Extensive literature search have been carried in regard with the pathogenesis and pathophysiology of DN, drug targets and updates on clinical trials, the consequences associated with DN and the potential biomarkers for diagnosis and prediction of DN are discussed in this review. DN is characterised by microalbuminuria and macroalbuminuria, and morphological changes such as glomerular thickening, interstitial fibrosis, formation of nodular glomerulosclerosis and decreased endothelial cell fenestration. Besides, the involvement of renin-angiotensin-aldosterone system, inflammation and genetic factors are the key pathways in the progression of DN. In regard with drug development drugs targeted to epidermal growth factor, inflammatory cytokines, ACTH receptor and TGFβ1 receptors are in pipeline for clinical trials whereas, several drugs have also failed in phase III and phase IV of clinical trials due to lack of efficacy and severe adverse effect. The research on DN is limited with respect to its pathogenesis and drug development. Thus, a more detailed understanding of the pathogenesis of DN is very essential to progress in the drug development process.

Evaluation of urinary biomarkers for prediction of diabetic kidney disease: a propensity score matching analysis

BACKGROUND

The aim of this study was to evaluate the diagnostic value of six urinary biomarkers for prediction of diabetic kidney disease (DKD).

METHODS

The cross-sectional study recruited 1053 hospitalized patients with type 2 diabetes mellitus (T2DM), who were categorized into the diabetes mellitus (DM) with normoalbuminuria (NA) group (n = 753) and DKD group (n = 300) according to 24-h urinary albumin excretion rate (24-h UAE). Data on the levels of six studied urinary biomarkers [transferrin (TF), immunoglobulin G (IgG), retinol-binding protein (RBP), β-galactosidase (GAL), N-acetyl-beta-glucosaminidase (NAG), and β2-microglobulin (β2MG)] were obtained. The propensity score matching (PSM) method was applied to eliminate the influences of confounding variables.

RESULTS

Patients with DKD had higher levels of all six urinary biomarkers. All indicators demonstrated significantly increased risk of DKD, except for GAL and β2MG. Single RBP yielded the greatest area under the curve (AUC) value of 0.920 compared with the other five markers, followed by TF (0.867) and IgG (0.867). However, GAL, NAG, and β2MG were shown to have a weak prognostic ability. The diagnostic values of the different combinations were not superior to the single RBP.

CONCLUSIONS

RBP, TF, and IgG could be used as reliable or good predictors of DKD. The combined use of these biomarkers did not improve DKD detection.

A review of urinary angiotensin converting enzyme 2 in diabetes and diabetic nephropathy

Urinary angiotensin converting enzyme 2 (ACE2) is significantly increased in diabetes and diabetic nephropathy. While studies on its clinical significance are still underway, its urinary expression, association with metabolic and renal parameters has been in the recent past considerably studied. The recent studies have demystified urine ACE2 in many ways and suggested the roles it could play in the management of diabetic nephropathy. In all studies the expression of urinary ACE2 was determined by enzyme activity assay and/with the quantification of ACE2 protein and mRNA by methods whose reliability are yet to be evaluated. This review summarizes recent findings on expression of urinary ACE2, examines its relationship with clinical parameters and highlights possible applications in management of diabetic nephropathy.

Urinary Proteomics for the Early Diagnosis of Diabetic Nephropathy in Taiwanese Patients

Diabetic nephropathy (DN) is a major complication in diabetic patients. Microalbuminuria testing is used to identify renal disease; however, its predictive value is questionable. We aimed to identify urinary biomarkers to early diagnosis nephropathy before identifiable alternations in kidney function or urine albumin excretion occurs. Proteomic approaches were used to identify potential urinary biomarkers and enzyme-linked immunosorbent assay was performed to verify the results. The data identified haptoglobin (HPT) and α-1-microglobulin/bikunin precursor (AMBP) as two biomarkers with the highest ability to distinguish between healthy individuals and patients with nephropathy, and between diabetic patients with and without DN. Further, the HPT-to-creatinine ratio (HCR) was evaluated as an independent predictor of early renal functional decline (ERFD) in a cohort with an average follow-up of 4.2 years. The area under the curve (AUC) value for ERFD prediction was significantly improved when the HCR biomarker was included in the model with albumin to creatinine ratio (ACR) and baseline characteristics (AUC values were 0.803 and 0.759 for HCR and ACR, respectively; p value was 0.0423 for difference between models). In conclusion, our results suggest that HCR represents an early indicator of nephropathy, and a marker related to ERFD among diabetic patients in Taiwan.

Markers of Glomerular and Tubular Damage in the Early Stage of Kidney Disease in Type 2 Diabetic Patients

Diabetic kidney disease develops in half of genetically predisposed patients with type 2 diabetes (T2DM). Early diagnosis of kidney damage and nephroprotective treatment are the ways of preventing the disease progression. Our aim was to evaluate selected laboratory markers of glomerular and tubular damage in T2DM patients with early stages of chronic kidney disease (G1/G2, A1/A2) for their associations with A2 albuminuria and early decline in the estimated glomerular filtration rate (eGFR). Among 80 T2DM patients with median eGFR of 92.4 ml/min/1.73 m² and median urinary albumin to creatinine ratio (uACR) of 4.69 mg/g, 19 had uACR > 30 mg/g (A2). Higher serum cystatin C, serum and urine neutrophil gelatinase associated lipocalin (NGAL), urine kidney injury molecule 1 (KIM-1), detectable urine transferrin and IgG, and lower serum uromodulin significantly predicted A2 albuminuria, urine KIM-1/creatinine ratio, and IgG being the best predictors. Albuminuria, urine NGAL/creatinine, and IgG correlated with diabetes duration. Albuminuria, urine NGAL, transferrin, IgG, and uromodulin correlated with diabetes control. In a subgroup of 29 patients, retrospective data were available on changes in eGFR and uACR over one year. Decline in eGFR was observed in 17 patients and increase in uACR in 10 patients. Serum and urine NGAL correlated with eGFR changes. Higher urine NGAL, KIM-1/creatinine ratio, and detectable IgG were significantly associated with the increase in uACR. Widely available markers, serum cystatin C, urine IgG, transferrin, and NGAL, may help in early assessment of kidney disease in T2DM patients; however, large prospective studies are needed to confirm the conclusion.

YKL-40: A biomarker for early nephropathy in type 2 diabetic patients and its association with inflammatory cytokines

Diabetic Nephropathy (DN) is an important cause of morbidity and death amongst diabetes. Persistent micro and macroalbuminuria are well known predictors of DN leading to progressive end-stage renal disease. However, albuminuria has several limitations. Increasing evidences show that YKL-40 is highly expressed in variety of inflammatory diseases and also recognized as a non-invasive prognostic biomarker for inflammation. In the present study, we measured plasma YKL-40 levels in different stages of albuminuria and assessed its diagnostic accuracy as a biomarker for DN and correlated with different families of circulatory cytokines. A total of 306 subjects were recruited and divided into three groups [Group-I, control (n = 83), Group-II, Normoalbuminuria (n = 81), Group-III, DN (n = 142)]. Group-III is further subdivided into: Group-IIIa, microalbuminuria (n = 73), Group-IIIb, macroalbuminuria (n = 69). The median levels of YKL-40 (p = 0.001) showed a marked stepwise increase from normo to macroalbuminuria and positively correlated with eGFR. The AUC_ROC for YKL-40 was found to be high [0.95; (95% CI: 0.88-1.0)], when compared to other acute phase markers. Plasma YKL-40 showed a positive correlation with LIGHT/TNFSF14, sIL-6Ra, gp130/sIL-6Rβ, IFN-β, IL-8, TNFSF14, sCD-30 and eGFR meanwhile a negative correlation with TWEAK/TNFSF12, IL-7 like cytokine and IFN-λ2. Plasma YKL-40 could be a potential biomarker for early diagnosis of incipient DN among South Indian population.

The relationship between the thickness of glomerular basement membrane and renal outcomes in patients with diabetic nephropathy

AIMS

Glomerular basement membrane (GBM) thickening is considered as one of the earliest detectable pathological features of diabetic nephropathy (DN). However, whether the thickness of GBM will impact the prognosis of DN remains largely unknown. Our aim was to explore the relationship between thickness of GBM and DN progression in patients with type 2 diabetes mellitus (T2DM).

METHODS

A total of 118 patients with T2DM and biopsy-proven DN who received follow-up for at least 1 year were recruited. The patients were divided into two groups according to the median (787 nm) of the GBM thickness: Group 1: GBM thickness < 787 nm (n = 59), and Group 2: GBM thickness ≥ 787 nm (n = 59). The GBM width was estimated by the direct GBM measurements as recently modified by Haas. Renal outcomes were defined by progression to ESRD and/or doubling of serum creatinine (D-Cr). The influence of GBM thickness on renal outcomes was assessed using Cox regression.

RESULTS

Compared with the Group 1, patients in Group 2 had more serious renal insufficiency and glomerular lesions. During the follow-up, ESRD occurred in 39.8% of patients, and 8.5% of patients progressed to D-Cr. The univariate analysis indicated the greater width of GBM the higher risk of renal outcomes in T2DM patients with DN (HR [95% CI] = 2.180 [1.246-3.814], p = 0.006). However, the multivariate COX analysis demonstrated that the GBM thickness was not an independent risk factor for progression to ESRD or D-Cr (HR [95% CI] = 0.825 [0.404-1.685], p = 0.597) when adjusting for important clinical variables and pathological findings.

CONCLUSIONS

In conclusion, the DN patients with greater width of GBM had relatively poorer renal prognosis, although it did not emerge as an independent indicator of disease progression.

Retinol-binding protein 4 versus albuminuria as predictors of estimated glomerular filtration rate decline in patients with type 2 diabetes

Background

Since the increase in some tubular damage biomarkers can be observed at the early stage of diabetic nephropathy, even in the absence of albuminuria, we aimed to investigate if urinary albumin is superior than tubular damage marker, such as serum retinol-binding protein 4 (RBP4), in predicting renal function decline (defined as estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m²) in the cohort of patients with type 2 diabetes mellitus (T2D).

Materials and Methods

A total of 106 sedentary T2D patients (mean [± standard deviation] age 64.9 [±6.6] years) were included in this cross-sectional study. Anthropometric and biochemical parameters (fasting glucose, glycated hemoglobin [HbA1c], lipid parameters, creatinine, RBP4, high sensitivity C-reactive protein [hsCRP], urinary albumin excretion [UAE]), as well as blood pressure were obtained.

Results

HsCRP (odds ratio [OR] =0.754, 95% confidence interval [CI] (0.603-0.942), P = 0.013) and RBP4 (OR = 0.873, 95% CI [0.824-0.926], P < 0.001) were independent predictors of eGFR decline. Moreover, although RBP4 and UAE as single diagnostic parameters of renal impairment showed excellent clinical accuracy (area under the curve [AUC] = 0.900 and AUC = 0.940, respectively), the Model which included body mass index, HbA1c, triglycerides, hsCRP, and RBP4 showed statistically same accuracy as UAE, when UAE was used as a single parameter (AUC = 0.932 vs. AUC = 0.940, respectively; P for AUC difference = 0.759). As well, the Model had higher sensitivity and specificity (92% and 90%, respectively) than single predictors, RBP4, and UAE.

Conclusion

Although serum RBP4 showed excellent clinical accuracy, just like UAE, a combination of markers of tubular damage, inflammation, and traditional markers has the higher sensitivity and specificity than UAE alone for prediction renal impairment in patients with T2D.

MicroRNAs as biomarkers in chronic kidney disease

PURPOSE OF REVIEW

This review summarizes recent data supporting the concept that urinary microRNAs are a useful new class of biomarker. They may improve capacity to stratify patients with chronic kidney disease according to risk of progression, and may also inform about response to therapy.

RECENT FINDINGS

MicroRNAs are present, stable and readily quantifiable in tissues and body fluids, including urine, and have widespread importance as regulators in the kidney. Urinary microRNAs are typically released from the nephron or downstream structures, and their abundance may reflect altered microRNA expression in the kidney, or release into the lumen by the cells comprising the different regions of the nephron. As a consequence, abundance of specific microRNAs in the urine may change in various pathological states. Large-scale studies are now needed, to test the capacity of specific microRNAs to inform about risk and response to therapy.

SUMMARY

Urinary microRNAs appear useful sentinels for pathological processes occurring in the kidney and may enable a 'personalized medicine' approach to the management and stratification of renal disease.

SIRT1 rs10823108 and FOXO1 rs17446614 responsible for genetic susceptibility to diabetic nephropathy

SIRT1 and FOXO1 play an important role in the pathogenesis of diabetic nephropathy (DN). However, the association between genetic polymorphisms and susceptibility to type 2 DN (T2DN) has not been explored. In this study, a total of 1066 patients with type 2 diabetes mellitus (T2DM) (413 without and 653 with DN) were enrolled. The genotypes of three htSNPs (rs3818292, rs4746720, rs10823108) within SIRT1 and two htSNPs (rs2721068, rs17446614) in FOXO1 were determined by PCR-RFLP. HbA1C, LDL, HDL, TC, and TG levels were also examined. SIRT1 rs10823108 AA genotype was significantly associated with a decreased risk of DN (OR = 0.60, 95%CI: 0.38–0.97), while GA genotype (OR = 1.77, 95%CI: 1.33–2.35) and AA genotype (OR = 2.32, 95%CI: 1.25–4.34) of FOXO1 rs17446614 was associated with an increased T2DN risk. The interactions among rs1744 6614, BMI and duration of diabetes (OR: 2.63, 95%CI: 1.23–4.31) were also observed. Subsequent haplotype analysis revealed that two haplotype defined by AC (OR: 1.50, 95%CI: 1.15–1.94) and AT (OR: 1.79, 95%CI: 1.06–2.80) within FOXO1 gene may increase the risk of T2DN. In conclusion, genetic variant rs10823108 in SIRT1 and variant rs17446614 in FoxO1 may contribute to the risk of DN in T2DM patients.