Biomarkers in diabetic nephropathy: Present and future

Diagnostic Performance of Cystatin C in the Early Detection of Diabetic Kidney Disease at the University of Nigeria Teaching Hospital, Ituku-Ozalla

INTRODUCTION

There is an increase in the prevalence of diabetes mellitus (DM) globally. Individuals with diabetes mellitus are at higher risk of impairment of kidney function. This study evaluated the diagnostic performance of Cystatin C in the early detection of diabetic kidney disease (DKD).

METHODS

Across a sectional analytical study of 300 participants (200 study group and 100 control group). A relevant clinical history was obtained, and a physical examination was carried out. Venous blood was collected to assay for serum creatinine, serum albumin, serum cystatin C, serum urea, fasting blood glucose, and urine for the quantification of urine albumin excretion rate.

RESULTS

The median age of the study group versus the control group was 62.50 for DM with proteinuria, 60.00 for DM without proteinuria, and 60.00 years for the control group (F = 3.524, p = 0.172). The laboratory parameters that were higher in the study group compared to the control group were FBG (141.0, 130, vs. 104 mg/dl, F = 68.456, p = <0.001), serum creatinine (109.0, 88.5, vs. 105.0 umol/l, F = 35.50, p = <0.001), serum cystatin C (1.24, 1.11, vs. 0.84 mg/L, F = 59.27, p = <0.001), and urine albumin excretion (230.0, 102.0, vs. 30.0 mg, F = 128.62, p = <0.001). The diagnostic performance of cystatin C using MDRD and cystatin C eGFR <60ml/min/1.73m2 was 13% and 23%, respectively, for the study group without proteinuria. Also, when the diagnostic efficiency of the variables was compared using ROC, the AUC of creatinine eGFR (MDRD) was less than that of cystatin C eGFR between the cut-off levels of 30 mg and 300 mg of urine albumin excretion. Cystatin C eGFR had a strong negative correlation with urine albumin excretion when compared to creatinine eGFR (MDRD).

CONCLUSION

This study showed the diagnostic performance of serum cystatin C in the early detection of DKD and that cystatin C-derived eGFR is more sensitive than serum creatinine-derived eGFR in detecting DKD early in people with DM.

One anastomosis gastric bypass ameliorates diabetic nephropathy via regulating the GLP-1-mediated Sirt1/AMPK/PGC1α pathway

BACKGROUND

Diabetic nephropathy (DN), a complication of diabetes, is the most leading cause of end-stage renal disease. Bariatric surgery functions on the remission of diabetes and diabetes-related complications. One anastomosis gastric bypass (OAGB), one of popular bariatric surgery, can improve diabetes and its complications by regulating the glucagon-like peptide-1 (GLP-1) level. Meanwhile, GLP-1 can alleviate renal damage in high-fat-diet-induced obese rats. However, the effect of OAGB on renal injury remains uncertain in DN.

METHODS

A diabetes model was elicited in rats via HFD feeding and STZ injection. The role and mechanism of OAGB were addressed in DN rats by the body and kidney weight and blood glucose supervision, oral glucose tolerance test (OGTT), enzyme-linked immunosorbent assay (ELISA), biochemistry detection, histopathological analysis, and western blot assays.

RESULTS

OAGB surgery reversed the increase in body weight and glucose tolerance indicators in diabetes rats. Also, OAGB operation neutralized the DN-induced average kidney weight, kidney weight/body weight, and renal injury indexes accompanied with reduced glomerular hypertrophy, alleviated mesangial dilation and decreased tubular and periglomerular collagen deposition. In addition, OAGB introduction reduced the DN-induced renal triglyceride and renal cholesterol with the regulation of fatty acids-related proteins expression. Mechanically, OAGB administration rescued the DN-induced expression of Sirt1/AMPK/PGC1α pathway mediated by GLP-1. Pharmacological block of GLP-1 receptor inverted the effect of OAGB operation on body weight, glucose tolerance, renal tissue damage, and fibrosis and lipids accumulation in DN rats.

CONCLUSION

OAGB improved renal damage and fibrosis and lipids accumulation in DN rats by GLP-1-mediated Sirt1/AMPK/PGC1α pathway.

Urinary biomarkers in diabetic nephropathy

Diabetic nephropathy (DN), a significant consequence of diabetes, is associated with adverse cardiovascular and renal disease as well as mortality. Although microalbuminuria is considered the best non-invasive marker for DN, better predictive markers are needed of sufficient sensitivity and specificity to detect disease in general and in early disease specifically. Even prior to appearance of microalbuminuria, urinary biomarkers increase in diabetics and can serve as accurate nephropathy biomarkers even in normoalbuminuria. In this review, a number of novel urine biomarkers including those reflecting kidney damage caused by glomerular/podocyte damage, tubular damage, oxidative stress, inflammation, and intrarenal renin-angiotensin system activation are discussed. Our review also includes emerging biomarkers such as urinary microRNAs. These short noncoding miRNAs regulate gene expression and could be utilized to identify potential novel biomarkers in DN development and progression. .

A digital twin model incorporating generalized metabolic fluxes to identify and predict chronic kidney disease in type 2 diabetes mellitus

We have developed a digital twin-based CKD identification and prediction model that leverages generalized metabolic fluxes (GMF) for patients with Type 2 Diabetes Mellitus (T2DM). GMF digital twins utilized basic clinical and physiological biomarkers as inputs for identification and prediction of CKD. We employed four diverse multi-ethnic cohorts (n = 7072): a Singaporean cohort (EVAS, n = 289) and a North American cohort (NHANES, n = 1044) for baseline CKD identification, and two multi-center Singaporean cohorts (CDMD, n = 2119 and SDR, n = 3627) for 3-year CKD prediction and risk stratification. We subsequently conducted a comprehensive study utilizing a single dataset to evaluate the clinical utility of GMF for CKD prediction. The GMF-based identification model performed strongly, achieving an AUC between 0.80 and 0.82. In prediction, the GMF generated with complete parameters attained high performance with an AUC of 0.86, while with incomplete parameters, it achieved an AUC of 0.75. The GMF-based prediction model utilizing complete inputs is the standard implementation of our algorithm: HealthVector Diabetes®. We have established the GMF digital twin-based model as a robust clinical tool capable of predicting and stratifying the risk of future CKD within a 3-year time horizon. We report the correlation of GMF with basic input parameters, their ability to differentiate between future health states and medication status at baseline, and their capability to quantify CKD progression rates. This holistic methodology provides insights into patients' health states and CKD progression rates based on GMF metabolic profile differences, enabling personalized care plans.

Diabetes and Renal Complications: An Overview on Pathophysiology, Biomarkers and Therapeutic Interventions

Diabetic kidney disease (DKD) is a major microvascular complication of both type 1 and type 2 diabetes. DKD is characterised by injury to both glomerular and tubular compartments, leading to kidney dysfunction over time. It is one of the most common causes of chronic kidney disease (CKD) and end-stage renal disease (ESRD). Persistent high blood glucose levels can damage the small blood vessels in the kidneys, impairing their ability to filter waste and fluids from the blood effectively. Other factors like high blood pressure (hypertension), genetics, and lifestyle habits can also contribute to the development and progression of DKD. The key features of renal complications of diabetes include morphological and functional alterations to renal glomeruli and tubules leading to mesangial expansion, glomerulosclerosis, homogenous thickening of the glomerular basement membrane (GBM), albuminuria, tubulointerstitial fibrosis and progressive decline in renal function. In advanced stages, DKD may require treatments such as dialysis or kidney transplant to sustain life. Therefore, early detection and proactive management of diabetes and its complications are crucial in preventing DKD and preserving kidney function.

The therapeutic effect of mesenchymal stem cells in diabetic kidney disease

Diabetes mellitus (DM) often causes chronic kidney damage despite best medical practices. Diabetic kidney disease (DKD) arises from a complex interaction of factors within the kidney and the whole body. Targeting specific disease-causing agents using drugs has not been effective in treating DKD. However, stem cell therapies offer a promising alternative by addressing multiple disease pathways and promoting kidney regeneration. Mesenchymal stem cells (MSCs) offer great promise due to their superior accessibility ratio from adult tissues and remarkable modes of action, such as the production of paracrine anti-inflammatory and cytoprotective substances. This review critically evaluates the development of MSC treatment for DKD as it moves closer to clinical application. Results from animal models suggest that systemic MSC infusion may positively impact DKD progression. However, few registered and completed clinical trials exist, and whether the treatments are effective in humans is still being determined. Significant knowledge gaps and research opportunities exist, including establishing the ideal source, dose, and timing of MSC delivery, better understanding of in vivo mechanisms, and developing quantitative indicators to obtain a more significant therapeutic response. This paper reviews recent literature on using MSCs in preclinical and clinical trials in DKD. Potent biomarkers related to DKD are also highlighted, which may help better understand MSCs' action in this disease progression. KEY MESSAGES: Mesenchymal stem cells have anti-inflammatory and paracrine effects in diabetic kidney disease. Mesenchymal stem cells alleviate in animal models having diabetic kidney disease. Mesenchymal stem cells possess promise for the treatment of diabetic kidney disease.

The therapeutic effect of mesenchymal stem cells in diabetic kidney disease

Abstract

Diabetes mellitus (DM) often causes chronic kidney damage despite best medical practices. Diabetic kidney disease (DKD) arises from a complex interaction of factors within the kidney and the whole body. Targeting specific disease-causing agents using drugs has not been effective in treating DKD. However, stem cell therapies offer a promising alternative by addressing multiple disease pathways and promoting kidney regeneration. Mesenchymal stem cells (MSCs) offer great promise due to their superior accessibility ratio from adult tissues and remarkable modes of action, such as the production of paracrine anti-inflammatory and cytoprotective substances. This review critically evaluates the development of MSC treatment for DKD as it moves closer to clinical application. Results from animal models suggest that systemic MSC infusion may positively impact DKD progression. However, few registered and completed clinical trials exist, and whether the treatments are effective in humans is still being determined. Significant knowledge gaps and research opportunities exist, including establishing the ideal source, dose, and timing of MSC delivery, better understanding of in vivo mechanisms, and developing quantitative indicators to obtain a more significant therapeutic response. This paper reviews recent literature on using MSCs in preclinical and clinical trials in DKD. Potent biomarkers related to DKD are also highlighted, which may help better understand MSCs’ action in this disease progression.

Key messages

Urinary Marker Profiles in Heart Failure with Reduced Versus Preserved Ejection Fraction

BACKGROUND

Recent data suggest different causes of renal dysfunction between heart failure with reduced (HFrEF) versus preserved ejection fraction (HFpEF). We therefore studied a wide range of urinary markers reflecting different nephron segments in heart failure patients.

METHODS

In 2070, in chronic heart failure patients, we measured several established and upcoming urinary markers reflecting different nephron segments.

RESULTS

Mean age was 70 ± 12 years, 74% was male and 81% (n = 1677) had HFrEF. Mean estimated glomerular filtration rate (eGFR) was lower in patients with HFpEF (56 ± 23 versus 63 ± 23 ml/min/1.73 m2, P = 0.001). Patients with HFpEF had significantly higher values of NGAL (58.1 [24.0-124.8] versus 28.1 [14.6-66.9] μg/gCr, P < 0.001) and KIM-1 (2.28 [1.49-4.37] versus 1.79 [0.85-3.49] μg/gCr, P = 0.001). These differences were more pronounced in patients with an eGFR > 60 ml/min/1.73m2.

CONCLUSIONS

HFpEF patients showed more evidence of tubular damage and/or dysfunction compared with HFrEF patients, in particular when glomerular function was preserved.

Urinary Vitamin D Binding Protein: A Marker of Kidney Tubular Dysfunction in Patients at Risk for Type 2 Diabetes

Context

Recent studies have reported elevated urinary vitamin D binding protein (uVDBP) concentrations in patients with diabetic kidney disease, although the utility of uVDBP to predict deterioration of kidney function over time has not been examined.

Objective

Our objective was to assess the association of uVDBP with longitudinal changes in kidney function.

Methods

Adults at-risk for type 2 diabetes from the Prospective Metabolism and Islet Cell Evaluation (PROMISE) study had 3 assessments over 6 years (n = 727). Urinary albumin-to-creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR) were used as measures of kidney function. Measurements of uVDBP were performed with enzyme-linked immunosorbent assay and normalized to urine creatinine (uVDBP:cr). Generalized estimating equations (GEEs) evaluated longitudinal associations of uVDBP and uVDBP:cr with measures of kidney function, adjusting for covariates.

Results

Renal uVDBP loss increased with ACR severity at baseline. Individuals with normoalbuminuria, microalbuminuria, and macroalbuminuria had median log uVDBP:cr concentrations of 1.62 μg/mmol, 2.63 μg/mmol, and 2.48 μg/mmol, respectively, and ACR positively correlated with uVDBP concentrations (r = 0.37; P < .001). There was no significant association between uVDBP and eGFR at baseline. Adjusted longitudinal GEE models indicated that each SD increase both in baseline and longitudinal uVDBP:cr was significantly associated with higher ACR over 6 years (β = 30.67 and β = 32.91, respectively). Conversely, neither baseline nor longitudinal uVDBP:cr measures showed a significant association with changes in eGFR over time. These results suggest that loss of uVDBP:cr over time may be a useful marker for predicting renal tubular damage in individuals at risk for diabetes.

Interference of periostin attenuates pathological changes, proinflammatory markers and renal fibrosis in diabetic kidney injury

BACKGROUND

Diabetic nephropathy (DN) is a prevalent complication of diabetes, in which inflammation and fibrosis are the significant pathogenesis. Periostin is a matricellular protein that functions on stabilizing the extracellular matrix by binding to integrins during development. This study aimed to explored the role of periostin in DN.

METHODS

The animal and cell models of DN were constructed in streptozocin (STZ)-induced mice and high glucose-challenged human mesangial cells (HMCs). The role of periostin in pathological changes, inflammation and fibrosis in DN was investigated through biochemical detection, HE and Masson staining and scores, western blot, enzyme‑linked immunosorbent assay (ELISA) and real-time quantitative PCR (RT-qPCR) assays.

RESULTS

Knockdown of periostin counteracted the STZ-induced the ratio of kidney weight and body weight, and the concentrations of urine albumin excretion (UAE), serum creatinine (Scr), urine albumin/creatinine ratio (UACR) and blood urea nitrogen (BUN) in mice. Moreover, silencing of periostin alleviated the pathological manifestations and reduced the concentrations of IL-6, TNF-α and IL-1β in mice kidney tissues and sera. Also, downregulation of periostin decreased the relative protein expression of fibronectin, collagen IV and α-SMA in kidney tissues. Meanwhile, interference of periostin attenuated the levels of pro-inflammation factors and the expressions of fibrosis markers in HG-induced HMCs.

CONCLUSION

Interference of periostin resisted DN via attenuating the pro-inflammatory cytokines release and renal fibrosis in diabetic kidney injury. Our study establishes a basis for its further study and underlying application in clinical practice in diagnosing and treating diabetic kidney injury or other relevant diseases.

Evaluation of urinary haptoglobin level as a biomarker of diabetic nephropathy in children with type 1 diabetes

BACKGROUND

Type 1 diabetes mellitus (T1DM) is a common endocrine disease in children. Early recognition of complications of T1DM is important for preventing long-term morbidity and mortality. We aimed to investigate whether urinary haptoglobin level is a biomarker of diabetic nephropathy in children with T1DM.

METHODS

Ninety T1DM patients, aged between 2-18 years, and 60 healthy age-matched children were included in the study. Glycosylated hemoglobin (HbA1c), spot urine creatinine, microalbumin, protein and haptoglobin levels of all cases were measured and compared. Correlations between HbA1c level, duration of diabetes, spot urine microalbumin/creatinine (uACR), protein/creatinine (uPCR), and haptoglobin/creatinine (uHCR) ratios in the T1DM group were evaluated.

RESULTS

T1DM and control groups were homogeneous in terms of age, sex, and anthropometric measurements. uACR was higher in the T1DM group than in the control group (14 mg/g vs. 6 mg/g) while uHCR was not elevated in T1DM patients. Nevertheless, uHCR was higher in the microalbuminuria group when compared to the normoalbuminuria group. In the T1DM group, moderate positive correlations between uPCR with uACR and uHCR, and weak correlation between uACR and uHCR were found (r = 0.60, p < 0.001; r = 0.55, p < 0.001; r = 0.24, p = 0.03, respectively). No significant relationship was found between diabetes duration, HbA1c levels and uACR, uPCR, and uHCR.

CONCLUSIONS

Although uHCR in the T1DM group was similar to the control group, uHCR was higher in the microalbuminuria group than in the normoalbuminuria group. These results show that the uHg level could be a biomarker of diabetic nephropathy, but not earlier than albuminuria in the disease course. A higher resolution version of the Graphical abstract is available as Supplementary information.

The relationship between serum γ-glutamyltransferase (GGT) and diabetic nephropathy in patients with type 2 diabetes mellitus: a cross-sectional study

The relationship between serum γ-glutamyltransferase (GGT) and renal dysfunction is controversial. In this study, we examined the relationship of serum GGT to diabetic nephropathy (DN) in patients with type 2 diabetes mellitus (T2DM). A total of 577 patients with T2DM were enrolled and their basic information and laboratory data were collected and analyzed. The prevalence of DN increased with the elevated serum GGT tertiles. The level of serum GGT in the DN group was higher than in the non-DN groups. Multivariate logistic analysis showed that high GGT was independent risks for DN (OR = 1.041, 95% CIs 1.023-1.059). And the OR of log-transformed serum GGT for DN was 6.190 (95% CIs 4.248-9.021). The OR of DN across increasing tertiles of serum GGT were 1.00, 3.288 (1.851-5.840), and 5.059 (2.620-9.769) (P for trend < 0.001). Stratified receiver operating characteristic (ROC) analysis by gender showed that the area under ROC curve (AUC) value for GGT was 0.781 (0.732-0.825, P < 0.05) in male and was 0.817 (0.761-0.864, P < 0.05) in female. Compared with female, GGT in male showed lower sensitivity (52.86% vs. 82.05%) and higher specificity (90.32% vs. 55.26%). And the AUC value for GGT was greater than creatinine (Cr) and estimated glomerular filtration rate (eGFR) in male and smaller than Cr and eGFR in female, respectively. In Conclusion, there was an independently positive relationship between serum GGT levels and DN, which suggested that elevated GGT was a potential indicator for risk of DN. There were gender differences in the predictive property of GGT for DN.

Diagnostic challenges of diabetic kidney disease

Diabetic kidney disease (DKD) is one of the most common microvascular complications of both type 1 and type 2 diabetes and the most common cause of the end-stage renal disease (ESRD). It has been evidenced that targeted interventions at an early stage of DKD can efficiently prevent or delay the progression of kidney failure and improve patient outcomes. Therefore, regular screening for DKD has become one of the fundamental principles of diabetes care. Long-established biomarkers such as serum-creatinine-based estimates of glomerular filtration rate and albuminuria are currently the cornerstone of diagnosis and risk stratification in routine clinical practice. However, their immanent biological limitations and analytical variations may influence the clinical interpretation of the results. Recently proposed new predictive equations without the variable of race, together with the evidence on better accuracy of combined serum creatinine and cystatin C equations, and both race- and sex-free cystatin C-based equation, have enabled an improvement in the detection of DKD, but also require the harmonization of the recommended laboratory tests, wider availability of cystatin C testing and specific approach in various populations. Considering the complex pathophysiology of DKD, particularly in type 2 diabetes, a panel of biomarkers is needed to classify patients in terms of the rate of disease progression and/or response to specific interventions. With a personalized approach to diagnosis and treatment, in the future, it will be possible to respond to DKD better and enable improved outcomes for numerous patients worldwide.

Predictive role of serum C-peptide in new-onset renal dysfunction in type 2 diabetes: a longitudinal observational study

Background

Our previous cross-sectional study has demonstrated the independently non-linear relationship between fasting C-peptide with renal dysfunction odds in patients with type 2 diabetes (T2D) in China. This longitudinal observational study aims to explore the role of serum C-peptide in risk prediction of new-onset renal dysfunction, then construct a predictive model based on serum C-peptide and other clinical parameters.

Methods

The patients with T2D and normal renal function at baseline were recruited in this study. The LASSO algorithm was performed to filter potential predictors from the baseline variables. Logistic regression (LR) was performed to construct the predictive model for new-onset renal dysfunction risk. Power analysis was performed to assess the statistical power of the model.

Results

During a 2-year follow-up period, 21.08% (35/166) of subjects with T2D and normal renal function at baseline progressed to renal dysfunction. Six predictors were determined using LASSO regression, including baseline albumin-to-creatinine ratio, glycated hemoglobin, hypertension, retinol-binding protein-to-creatinine ratio, quartiles of fasting C-peptide, and quartiles of fasting C-peptide to 2h postprandial C-peptide ratio. These 6 predictors were incorporated to develop model for renal dysfunction risk prediction using LR. Finally, the LR model achieved a high efficiency, with an AUC of 0.83 (0.76 - 0.91), an accuracy of 75.80%, a sensitivity of 88.60%, and a specificity of 70.80%. According to the power analysis, the statistical power of the LR model was found to be 0.81, which was at a relatively high level. Finally, a nomogram was developed to make the model more available for individualized prediction in clinical practice.

Conclusion

Our results indicated that the baseline level of serum C-peptide had the potential role in the risk prediction of new-onset renal dysfunction. The LR model demonstrated high efficiency and had the potential to guide individualized risk assessments for renal dysfunction in clinical practice.

Diabetic kidney disease in pediatric patients: A current review

In the last decades, a significant increase in the incidence of diabetic kidney disease (DKD) was observed concomitant with rising diabetes mellitus (DM) incidence. Kidney disease associated with DM in children and adolescents is represented by persistent albuminuria, arterial hypertension, progressive decline in estimated glomerular filtration rate to end-stage renal disease and increased cardiovascular and all-cause morbidity and mortality of these conditions. In medical practice, the common and still the "gold standard" marker for prediction and detection of diabetic kidney involvement in pediatric diabetes is represented by microalbuminuria screening even if it has low specificity to detect early stages of DKD. There are some known limitations in albuminuria value as a predictor biomarker for DKD, as not all diabetic children with microalbuminuria or macroalbuminuria will develop end-stage renal disease. As tubular damage occurs before the glomerular injury, tubular biomarkers are superior to the glomerular ones. Therefore, they may serve for early detection of DKD in both type 1 DM and type 2 DM. Conventional and new biomarkers to identify diabetic children and adolescents at risk of renal complications at an early stage as well as renoprotective strategies are necessary to delay the progression of kidney disease to end-stage kidney disease. New biomarkers and therapeutic strategies are discussed as timely diagnosis and therapy are critical in the pediatric diabetic population.

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.

Assessment of microvascular function using a novel technique Flow Mediated Skin Fluorescence (FMSF) in patients with diabetic kidney disease: A preliminary study

BACKGROUND

Diabetic kidney disease (DKD) plays an important role in morbidity and mortality in patients with diabetes mellitus. The pathogenesis of this microangiopathy is mainly due to impaired vascular endothelial function. The Flow Mediated Skin Fluorescence (FMSF) method is an innovative, non-invasive tool for assessing the microcirculation function (especially microcirculatory response to hypoxia), also in patients with complications of diabetes mellitus (DM).

MATERIAL AND METHODS

The study was conducted at the Medical University of Lodz, Poland. Total of 84 volunteers including 30 patients with DKD, 33 patients with DM without complications, and 21 healthy subjects underwent microvascular function assessments using FMSF. This technique measures changes in the intensity of nicotinamide adenine dinucleotide (NADH) fluorescence from the skin on the forearm as a function of time, in response to blocking and releasing blood flow in the forearm. In this study we asses two key parameters: Reactive Hyperemia Response (RHR) and Hypoxia Sensitivity [log(HS)] to characterize vascular circulation in patients with DKD and their response to transient ischemia.

RESULTS

The patients with low reactive hyperemic response (the RHR parameter) had a significantly higher sCr than patients with moderate and high RHR value (p < 0.001, p < 0.05, respectively) and a significantly lower eGFR than the patients with moderate and high RHR parameter (p < 0.001, p < 0.01, respectively). The patients with very low and low log(HS) values had a significantly higher sCr than the patients with high log(HS) (p < 0.001, p < 0.01, respectively), and a significantly lower eGFR than the patients with high log(HS) parameter (p < 0.001, p < 0.01, respectively). The patients with very low log(HS) had a significantly higher sCr and a significantly lower eGFR than the patients with moderate (p < 0.05, p < 0.01, respectively). The mean value of the RHR parameter was significantly lower in DKD patients (18.31 ± 5.06 %) compared to both healthy subjects (34.37 ± 8.18 %, p < 0.001) and DM without complications subgroup (28.75 ± 7.12 %, p < 0.001). Similar trends were noted with the mean value of log(HS) parameter in DKD subgroup (1.03 ± 0.5) vs. healthy subjects (1.59 ± 0.53, p < 0.001), and vs. DM without complications subgroup (1.73 ± 0.52, p < 0.001). We observed a significant inverse correlation between the RHR parameter and serum creatinine (sCr) and a significant positive correlations with eGFR (R =  -0.3; p < 0.05, R = 0.61; p < 0.001, respectively). We found also a significant negative correlations of the log(HS) measure with sCr and a significant positive correlations with eGFR (R = -0.33; p < 0.01, R = 0.55; p < 0.001, respectively). We observed also a significant inverse correlation between the RHR and log(HS) parameters and advanced glycation end products (AGEs) (R = -0.6; p < 0.001, R = -0.32; p < 0.01, respectively). The AGEs parameter was also a significantly higher in patients with low RHR parameter than in patients with moderate (p < 0.01) and high (p < 0.001).

CONCLUSIONS

The FMSF technique makes it possible to identify impairments of the microvascular function in patients with DKD. This study confirms that the simple two-parametric approach diagnostic tool perfectly characterizes the state of the microvascular system in diabetic patients with impaired renal function. These preliminary results require further validation in a larger patients cohort.

Role of Periostin and Nuclear Factor-κB Interplay in the Development of Diabetic Nephropathy

Diabetic nephropathy (DN) remains the most common reason for end-stage renal disease and a leading cause of kidney replacement therapy. Multifactorial pathophysiological mechanisms underlie the development of DN. Among the signalling pathways involved, nuclear factor-κB (NF-κB) plays a key role in pathogenesis triggering inflammation, oxidative stress and fibrosis. Recent evidence shows that periostin, a matricellular protein, is involved in the development of renal glomerular diseases through interaction with NF-κB signalling. The aim of the present study is to investigate the contribution of periostin and its interaction with NF-κB in DN development. To this end, we used the BTBR ob/ob mice model of diabetes type 2, and we applied transcriptomic analysis, immunostaining and methods quantifying protein and mRNA expressions. We found that increased periostin expression was correlated with decreased renal function, advanced stage renal damage and fibrosis, and NF-κB activation. Subsequently, we identified novel pathways and genes regulated by the NF-κB-periostin interaction which are involved in the mechanisms of progression of DN. Some of these genes, such as FGF1 and GDF15, have the potential to be new biomarkers and/or targets for the therapy of DN.

Blocking REDD1/TXNIP Complex Ameliorates HG-Induced Renal Tubular Epithelial Cell Apoptosis and EMT through Repressing Oxidative Stress

Diabetic nephropathy (DN) has become the most common secondary kidney disease causing end-stage renal disease (ESRD). Nevertheless, the underlying mechanisms responsible for DN remain largely unknown. Regulated in development and DNA damage response 1 (REDD1) is a prooxidative molecule known to contribute to diabetes mellitus and its complications. However, it has not been previously examined whether and how REDD1 can further drive renal tubular epithelial cell (RTEC) apoptosis and epithelial-to-mesenchymal transition in DN. The expression of REDD1 was elevated in the kidneys of DN patients and diabetic mice in this study. By generating the DN model in REDD1 knockout mice, we demonstrated that REDD1 deficiency significantly improved apoptosis and EMT in diabetic mice. In vitro experiments showed that REDD1 generation was induced by high glucose (HG) in HK-2 cells. Similarly, the transfection of REDD1 siRNA plasmid also suppressed HG-induced apoptosis and EMT. Furthermore, we discovered that the inhibition of REDD1 suppressed the expression of Nox4-induced HG and reactive oxygen species (ROS) synthesis in HK-2 cells. In addition, HG could induce endogenous REDD1 and TXNIP to form a powerful complex. In summary, our findings demonstrate that blocking the REDD1/TXNIP complex can prevent HG-induced apoptosis and EMT by inhibiting ROS production, highlighting REDD1 as a valuable therapeutic priority site for DN.

COULD PROTEINURIA PREDICT THE RENAL PROGNOSES OF PATIENTS WITH TYPE 2 DIABETES MELLITUS AND DIABETIC NEPHROPATHY?

AIMS

This study investigated the relationship between proteinuria levels, clinicopathological features, and renal prognoses in Chinese patients with type 2 diabetes mellitus (T2DM) and diabetic nephropathy (DN).

METHODS

Three hundred patients with T2DM and biopsy-proven DN were enrolled. Patients were stratified by 24-h proteinuria levels: Group 1:≤1g/24h); Group 2:1-3g/24h; and Group 3:≥3g/24h. Renal outcomes were defined as having reached end-stage renal disease (ESRD). The proteinuria level's influence on the renal outcomes was evaluated using Cox regression analysis.

RESULTS

Among subgroups stratified by proteinuria levels, systolic blood pressure, serum creatinine, BUN, cholesterol, DR and hypertension incidence, the incidences of patients who progressed to ESRD were the lowest in group 1 (P<0.05). However, eGFR, serum albumin and hemoglobin were highest in group 1. Patients with higher proteinuria levels had much lower five-year renal survival rates. Univariate analyses revealed that higher proteinuria levels were significant clinical predictors of renal prognosis (P<0.05), although they were not independent risk factors for progression to ESRD in the multivariate Cox proportional hazard analysis (P>0.05).

CONCLUSIONS

The higher the level of proteinuria, the lower the 5-year renal survival rate of DN patients, but there was no significant correlation between proteinuria level and 5-year renal survival rate. Other factors in the proteinuria group may have more significant effects on the 5-year renal survival rate, such as lower baseline eGFR, serum albumin, hemoglobin and higher cholesterol, higher incidences of DR and more severe lesions.

Relationship between amino acid ratios and decline in estimated glomerular filtration rate in diabetic and non-diabetic patients in South Africa

Background

Diabetic kidney disease is a major complication resulting from type 1 and type 2 diabetes. Currently, the microalbuminuria test is used to monitor renal function; however, it does not detect albumin until progressive loss of renal function has occurred.

Objective

This study analysed the relationship between changes in amino acid ratios and estimated glomerular filtration rate (eGFR) decline in diabetic and non-diabetic patients.

Methods

Urine samples were collected from participants between February 2019 to April 2019 and analysed from November 2020 to January 2021. Diabetic (glycated haemoglobin > 6.4%) and non-diabetic patients (glycated haemoglobin ≤ 6.4%) from Chris Hani Baragwanath Hospital, South Africa, were further categorised based on the degree of renal function predicted by the eGFRs. Amino acids were quantified using tandem mass spectrometry to determine the concentrations and ratios of tyrosine/phenylalanine, ornithine/arginine, arginine/citrulline and citrulline/ornithine at different stages of the chronic kidney disease.

Results

Among diabetic patients, the tyrosine/phenylalanine ratio showed a statistically significant increase (p = 0.04) as the eGFR declined from stage 1 to stage 4; the ornithine/arginine ratio showed a strong negative correlation with eGFR. The citrulline/ornithine ratio differed between the diabetic and non-diabetic patients in stage 1 of chronic kidney disease.

Conclusion

Amino acid ratios (ornithine/arginine and tyrosine/phenylalanine) are affected by the progression of diabetes and can be correlated to renal function. The citrulline/ornithine ratios differ between the studied groups in stage 1 of the disease and may be utilised to predict the onset of chronic kidney disease.

Diabetic Nephropathy - possibilities of early laboratory diagnostics and course prediction (review of literature)

The medical and social significance of diabetes mellitus is determined by a progressive increase in the incidence of the disease, as well as the development of disabling and reducing the quality of life of macro- and microvascular complications in patients of working age, in particular, with the development of diabetic nephropathy (DN), which develops in one third of patients with type 1 and 2 diabetes. DN is the third leading cause of death after diseases of the cardiovascular system and oncological pathologies. In this regard, the identification of DN at the early stages is an important task both from the standpoint of prevention and a more favorable prognosis of the course of diabetes. This review presents data on the possibilities of early diagnosis of DN using blood and urine biomarkers, as well as information on their diagnostic and prognostic value. The analysis of the interpretation of the indicator of microalbuminuria in type 1 and 2 diabetes was carried out. In addition, the literature data of recent years on the informative value of determining markers of podocyte damage, on the role of oxidative stress products, immune-inflammatory factors, and vascular endothelial growth factor in the process of the onset and development of DN are presented. The possibility of their practical use for the diagnosis of DN in clinical practice is discussed. The literature search for this review was carried out using the databases of the RSCI, CyberLeninka, Scopus, Web of Science, MedLine, PubMed for the period from 2011 to 2021. using the following keywords: diabetes mellitus, diabetic nephropathy, markers of diabetic nephropathy; kidney damage, early diagnosis of diabetic nephropathy.

Circulating Biomarkers of Inflammation and Endothelial Activation in Diabetic Retinopathy

Inflammation and endothelial activation play a pivotal role in development and progression of diabetic retinopathy (DR), a vision-threatening complication of diabetes mellitus (DM) and the leading cause of blindness in the working age population. Easily accessible and validated biomarkers for DR early diagnosis and progression are required for use in clinical trials: here, we reviewed the available literature to understand the association of circulating levels of selected markers of inflammation and endothelial activation with the presence of nonproliferative and proliferative DR (NPDR and PDR) and investigate the relationship between their systemic and ocular levels. We additionally provide data synthesis and perform statistical analysis for interpretation of the collected evidence. CRP, IL-1β, IL-6, TNFα, sICAM1, and sVCAM1 circulating levels were increased in subjects with DM compared to healthy individuals. Moreover, TNFα and sVCAM1 showed increasing systemic levels with DR presence and severity; circulating CRP increased with the transition from no DR to NPDR, whereas IL-6 was increased in PDR compared to NDPR stages. The relationship between ocular and systemic concentrations of these proteins remained unclear due to the low number of studies with matched sampling. In conclusion, the available data supports the use of systemic biomarkers of inflammation and endothelial activation to identify DM status and DR severity. These systemic biomarkers are likely reflecting an overall state of inflammation and vascular activation in different tissues of the body, including the eyes. Prospective, longitudinal datasets are required to validate these biomarkers as predictors of early DR presence, of DR progression, or for disease monitoring.

Genetics Variants in the Epoxygenase Pathway of Arachidonic Metabolism Are Associated with Eicosanoids Levels and the Risk of Diabetic Nephropathy

Genes in the epoxygenase pathway of arachidonic acid metabolism leading to vasoactive eicosanoids, mainly 20-hydroxyeicosatetraenoic (20-HETE) and epoxyeicosatrienoic (EETs) acids, have been related to glucose-induced renal damage in preclinical reports. We genotyped 1088 diabetic kidney disease (DKD) patients and controls for seven polymorphisms in five genes (CYP2C8, CYP2J2, CYP4F2, CYP4A11, and EPHX2) along this metabolic route and evaluated their effect on DKD risk, clinical outcomes, and the plasma/urine levels of eicosanoids measured by LC/MS/MS and immunoenzymatic assays. The CYP4F2 433M variant allele was associated with lower incidence of DKD (OR = 0.65 (0.48-0.90), p = 0.008), whilst the CYP2C8*3/*3 genotype was related to increased risk (OR = 3.21 (1.05-9.87), p = 0.036). Patients carrying the 433M allele also showed lower eGFR [median and interquartile range vs. wildtype carriers: 30.8 (19.8) and 33.0 (23.2) mL/min/1.73 m², p = 0.037). Finally, the 433VM/MM variant genotypes were associated with lower urinary levels of 20-HETE compared with 433VV (3.14 (0.86) vs. 8.45 (3.69) ng/mg Creatinine, p = 0.024). Our results indicate that the CYP4F2 V433M polymorphism, by decreasing 20-HETE levels, may play an important role in DKD.

LncRNA LINC01857 promotes cell growth and diminishes apoptosis via PI3K/mTOR pathway and EMT process by regulating miR-141-3p/MAP4K4 axis in diffuse large B-cell lymphoma

LINC01857 has been proven to be involved in glioma and breast cancer. However, the biological function of LINC01857 in diffuse large B-cell lymphoma (DLBCL) is poorly investigated. By accessing to the Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTE_X), LINC01857 expression was found upregulated in both DLBCL tissues and cells. Cell proliferation and flow cytometry assays showed that LINC01857 promoted proliferation and cell cycle, but suppressed apoptosis in DLBCL cells. Bioinformatics analysis and luciferase reporter assay confirmed that LINC01857 may serve as a sponge for miR-141-3p and miR-141-3p may target MAP4K4. Mechanically, the regulatory action of miR-141-3p/MAP4K4 on DLBCL cellular behaviors was regulated by LINC01857. In addition, LINC01857 could increase the activity of PI3K/mTOR pathway and facilitate the EMT process in a miR-141-3p-mediated manner in DLBCL. Our data illustrated that the LINC01857/miR-141-3p/MAP4K4 might function as a promising therapeutic avenue for DLBCL treatment.

Urinary cystatin C as a biomarker of early renal dysfunction in type 2 diabetic patients

AIMS

We aimed to evaluate urinary CysC (cystanin c) as an early marker of diabetic nephropathy in patients with type 2 diabetes and investigate the correlation of urinary CysC with albuminuria and GFR.

METHODOLOGY

This case-controlled study was conducted on 66 type 2 diabetic patients who were classified according to albuminuria into 3 groups and consisting of 20 healthy subjects as the control group. We assessed urinary CysC, urinary albumin excretion rate (UACR).

RESULTS

Urinary CysC levels were significantly higher in normoalbuminuric diabetic compared with healthy control and there was a progressive linear increase in urinary CysC levels with increasing albuminuria in the diabetic patients. Despite insignificant deference in creatinine between participants groups, we observed significant differences between these groups as regard eGFR, urinary CysC, and UACR. Urinary CysC did not have significant correlations with any clinical or biochemical parameters. Moreover, urinary CysC had a statistically significant association with albuminuria and eGFR.

CONCLUSION

Urinary CysC levels correlated with UACR and GFR. It is linked to subclinical tubular injury and can be an earlier marker of kidney involvement, even before albuminuria and it is less influenced by non-renal factors. Therefore, Urinary CysC is useful biomarker for early diagnosis of diabetic nephropathy.

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.

Effects of Angiotensin II Type 1A Receptor on ACE2, Neprilysin and KIM-1 in Two Kidney One Clip (2K1C) Model of Renovascular Hypertension

Activation of the renin angiotensin system plays a pivotal role in the regulation of blood pressure, which is mainly attributed to the formation of angiotensin-II (Ang II). The actions of Ang II are mediated through binding to the Ang-II type 1 receptor (AT1R) which leads to increased blood pressure, fluid retention, and aldosterone secretion. In addition, Ang II is also involved in cell injury, vascular remodeling, and inflammation. The actions of Ang II could be antagonized by its conversion to the vasodilator peptide Ang (1-7), partly generated by the action of angiotensin converting enzyme 2 (ACE2) and/or neprilysin (NEP). Previous studies demonstrated increased urinary ACE2 shedding in the db/db mouse model of diabetic kidney disease. The aim of the study was to investigate whether renal and urinary ACE2 and NEP are altered in the 2K1C Goldblatt hypertensive mice. Since AT1R is highly expressed in the kidney, we also researched the effect of global deletion of AT1R on renal and urinary ACE2, NEP, and kidney injury marker (KIM-1). Hypertension and albuminuria were induced in AT1R knock out (AT1RKO) and WT mice by unilateral constriction of the renal artery of one kidney. The 24 h mean arterial blood pressure (MAP) was measured using radio-telemetry. Two weeks after 2K1C surgery, MAP and albuminuria were significantly increased in WT mice compared to AT1RKO mice. Results demonstrated a correlation between MAP and albuminuria. Unlike db/db diabetic mice, ACE2 and NEP expression and activities were significantly decreased in the clipped kidney of WT and AT1RKO compared with the contralateral kidney and sham control (p < 0.05). There was no detectable urinary ACE2 and NEP expression and activity in 2K1C mice. KIM-1 was significantly increased in the clipped kidney of WT and AT1KO (p < 0.05). Deletion of AT1R has no effect on the increased urinary KIM-1 excretion detected in 2K1C mice. In conclusion, renal injury in 2K1C Goldblatt mouse model is associated with loss of renal ACE2 and NEP expression and activity. Urinary KIM-1 could serve as an early indicator of acute kidney injury. Deletion of AT1R attenuates albuminuria and hypertension without affecting renal ACE2, NEP, and KIM-1 expression.

Personizing the prediction of future susceptibility to a specific disease

A traceable biomarker is a member of a disease's molecular pathway. A disease may be associated with several molecular pathways. Each different combination of these molecular pathways, to which detected traceable biomarkers belong, may serve as an indicative of the elicitation of the disease at a different time frame in the future. Based on this notion, we introduce a novel methodology for personalizing an individual's degree of future susceptibility to a specific disease. We implemented the methodology in a working system called Susceptibility Degree to a Disease Predictor (SDDP). For a specific disease d, let S be the set of molecular pathways, to which traceable biomarkers detected from most patients of d belong. For the same disease d, let S' be the set of molecular pathways, to which traceable biomarkers detected from a certain individual belong. SDDP is able to infer the subset S'' ⊆{S-S'} of undetected molecular pathways for the individual. Thus, SDDP can infer undetected molecular pathways of a disease for an individual based on few molecular pathways detected from the individual. SDDP can also help in inferring the combination of molecular pathways in the set {S'+S''}, whose traceable biomarkers collectively is an indicative of the disease. SDDP is composed of the following four components: information extractor, interrelationship between molecular pathways modeler, logic inferencer, and risk indicator. The information extractor takes advantage of the exponential increase of biomedical literature to automatically extract the common traceable biomarkers for a specific disease. The interrelationship between molecular pathways modeler models the hierarchical interrelationships between the molecular pathways of the traceable biomarkers. The logic inferencer transforms the hierarchical interrelationships between the molecular pathways into rule-based specifications. It employs the specification rules and the inference rules for predicate logic to infer as many as possible undetected molecular pathways of a disease for an individual. The risk indicator outputs a risk indicator value that reflects the individual's degree of future susceptibility to the disease. We evaluated SDDP by comparing it experimentally with other methods. Results revealed marked improvement.

Evidence of Early Diabetic Nephropathy in Pediatric Type 1 Diabetes

BACKGROUND

Diabetic nephropathy (DN) is one of the most common microvascular complications in type 1 diabetes Mellitus (T1D). Urinary markers of renal damage or oxidative stress may signal early stages of DN. The association of these markers with blood pressure (BP) patterns and glycemic variability (GV) in children is yet to be explored.

METHODS

Subjects between the ages of 10 and 21 years with T1D were enrolled. Continuous glucose monitoring (CGM) and ambulatory blood pressure monitoring (ABPM) were performed on each subject. Urine samples were collected and analyzed for albumin, creatinine, neutrophil gelatinase-associated lipocalin (NGAL) and pentosidine.

RESULTS

The study included 21 subjects (62% female) with median age of 16.8 (IQR: 14.5, 18.9). Median HbA1C was 8.4 (IQR: 7.5, 9.3). While microalbuminuria was negative in all but one case (4.8%), urinary NGAL/Cr and pentosidine/Cr ratios were significantly elevated (P<0.001) in diabetic patients despite having normal microalbuminuria, and they correlated significantly with level of microalbumin/Cr (r=0.56 [CI: 0.17, 0.8] and r=0.79 [CI: 0.54, 0.91], respectively). Using ABPM, none had hypertension, however, poor nocturnal systolic BP dipping was found in 48% of cases (95% CI: 28-68%). Urinary NGAL/Cr negatively correlated with nocturnal SBP dipping (r=-0.47, CI: -0.76, -0.03). Urine NGAL/Cr also showed a significant negative correlation with HbA1c measurements, mean blood glucose, and high blood glucose index (r=-0.51 [CI: -0.78, -0.09], r=-0.45 [CI: -0.74, -0.03], and r=-0.51 [CI: -0.77, -0.1], respectively). Median urinary NGAL/Cr and pentosidine/Cr ratios were higher in the high GV group but were not significantly different.

DISCUSSION

This pilot study explores the role of ABPM and urinary markers of tubular health and oxidative stress in early detection of diabetic nephropathy. GV may play a role in the process of this diabetic complication.

Type 2 diabetes mellitus management in patients with chronic kidney disease: an update

Diabetes mellitus (DM) is a chronic multisystem disease. Diabetic nephropathy (DN) is one of its significant microvascular complications, associated with increased morbidity and mortality. The aim of this article is to review the literature regarding the latest advances in the management of type 2 DM (T2DM) in patients with chronic kidney disease (CKD). We initially refer to the screening guidelines, the diagnostic tests used, the need for novel biomarkers in DN, the recent advances in high-risk patient identification, the recommended glycemic targets, and concerns regarding the accuracy of HbA1c in these patients. Then, a detailed explanation of the appropriate medical management based on evidence from recent trials is presented, analyzed, and discussed. All patients with T2DM should be screened for albuminuria at initial diagnosis and annually thereafter. Proteomics and metabolomics today represent promising diagnostic tools. Optimal glycemic control, with individualized HbA1c targets, is fundamental for reduced onset or delayed progression of DN and microvascular complications, in general. This can be enhanced by lifestyle modifications and pharmacological interventions when needed. Metformin represents the first pharmacological step, with, recently, a broadened indication for patients with impaired renal function. If HbA1c remains above the target in patients with established CKD, SGLT2i or GLP-1 RA are the preferred second-line agents, as introduced in all new guidelines. This change was the result of recent landmark trials that highlighted the superiority of the two aforementioned medication categories in terms of both renal and cardiovascular outcomes.

Urinary proteins detected using modern proteomics intervene in early type 2 diabetic kidney disease – a pilot study

Aim: An advanced proteomics platform for protein biomarker discovery in diabetic chronic kidney disease (DKD) was developed, validated and implemented. Materials & methods: Three Type 2 diabetes mellitus patients and three control subjects were enrolled. Urinary peptides were extracted, samples were analyzed on a hybrid LTQ-Orbitrap Velos Pro instrument. Raw data were searched using the SEQUEST algorithm and integrated into Proteome Discoverer platform. Results & discussion: Unique peptide sequences, resulted sequence coverage, scoring of peptide spectrum matches were reported to albuminuria and databases. Five proteins that can be associated with early DKD were found: apolipoprotein AI, neutrophil gelatinase-associated lipocalin, cytidine deaminase, S100-A8 and hemoglobin subunit delta. Conclusion: Urinary proteome analysis could be used to evaluate mechanisms of pathogenesis of DKD.

Association of urinary non-albumin protein with the different urinary marker for glomerular and tubular damage in patients with type 2 diabetes

BACKGROUND/AIM

In recent years, the diagnostic utility of urinary protein levels has been demonstrated for the early detection and progression of kidney disease. This study aimed to evaluate the associations of the non-albumin protein (NAP) with different urinary marker for tubular and glomerular damage in patients with type 2 diabetes (T2D).

METHODS

In this observational cross-sectional study, 424 patients with T2D duration > 10 years were classified into two groups according to estimated glomerular filtration rate (eGFR). The ratios of different urinary markers (albumin, NAP, total protein, transferrin, retinol-binding protein (RBP), and neutrophil gelatinase-associated lipocalin (NGAL) to creatinine were analyzed.

RESULTS

The levels of urinary biomarkers increased significantly with decrease in eGFR levels. In the group with moderately decreased eGFR, the albumin to-creatinine ratio (ACR), non-albumin protein-to-creatinine ratio (NAPCR), and total protein-to-creatinine ratio (PCR) were independently associated with all urinary markers after being adjusted for risk factors. The area under the receiver operating characteristics (ROC) curve for ACR and PCR had a better diagnostic value than other urinary biomarkers. Comparing ROC curve of NAPCR with other urinary biomarkers, it was significantly better than NGAL/Cr (p = 0.033).

CONCLUSIONS

The findings of the present study confirm that ACR and PCR are diagnostic biomarkers in T2D patients with decreased eGFR. NAPCR in these patients diagnostically only outperformed NGAL/Cr.

Crescent-Like Lesions as an Early Signature of Nephropathy in a Rat Model of Prediabetes Induced by a Hypercaloric Diet

Diabetic nephropathy (DN) is a major microvascular complication of diabetes. Obesity and hyperlipidemia, fueled by unhealthy food habits, are risk factors to glomerular filtration rate (GFR) decline and DN progression. Several studies recommend that diabetic patients should be screened early (in prediabetes) for kidney disease, in order to prevent advanced stages, for whom the current interventions are clearly inefficient. This ambition greatly depends on the existence of accurate early biomarkers and novel molecular targets, which only may arise with a more thorough knowledge of disease pathophysiology. We used a rat model of prediabetes induced by 23 weeks of high-sugar/high-fat (HSuHF) diet to characterize the phenotype of early renal dysfunction and injury. When compared with the control animals, HSuHF-treated rats displayed a metabolic phenotype compatible with obese prediabetes, displaying impaired glucose tolerance and insulin sensitivity, along with hypertriglyceridemia, and lipid peroxidation. Despite unchanged creatinine levels, the prediabetic animals presented glomerular crescent-like lesions, accompanied by increased kidney Oil-Red-O staining, triglycerides content and mRNA expression of IL-6 and iNOS. This model of HSuHF-induced prediabetes can be a useful tool to study early features of DN, namely crescent-like lesions, an early signature that deserves in-depth elucidation.

Alpha1-Antitrypsin in Urinary Extracellular Vesicles: A Potential Biomarker of Diabetic Kidney Disease Prior to Microalbuminuria

PURPOSE

Diabetic kidney disease (DKD), which is related to inflammation and immune response, is the primary vascular complication of diabetes mellitus and also the leading etiology of end-stage renal disease. Urinary extracellular vesicles (UEVs) are an attractive source for biomarker detection as they involve molecular constituents derived from their parental sections of the nephron. In this study, we aimed to search for a potential biomarker in UEVs for the early diagnosis and prediction of DKD, especially before the emergence of microalbuminuria.

PATIENTS AND METHODS

UEVs were isolated from the urine of healthy subjects, pre-diabetic, and diabetic patients with varying degrees of kidney damage by ultracentrifugation, and the extracted UEVs were used to measure alpha1-antitrypsin (α1-AT) by Western blot. To explore the function of α1-AT in the inflammatory process leading to DKD, we silenced the expression of α1-AT in renal tubular epithelial cells using cell transfection techniques to assess the differential expression of the inflammatory factors such as MCP-1 and TNF-α using qRT-PCR.

RESULTS

There was no expression of α1-AT in the UEVs of either healthy or pre-diabetic subjects. Its expression was significantly increased in the UEVs of diabetic patients with normoalbuminuria (prior to microalbuminuria), which was more sensitive and more stable than other renal indexes to predict DKD. Additionally, the expression of α1-AT in UEVs was gradually upregulated with the aggravation of DKD and the decline of renal function. In vitro, the mRNA expression of MCP-1 and TNF-α was significantly decreased when the generation of α1-AT in tubular epithelial cells was inhibited under high glucose stimulation.

CONCLUSION

Our results suggest that α1-AT derived from UEVs, especially in diabetic patients with normoalbuminuria, might serve as a potential noninvasive biomarker for diagnosis of DKD early in the development of the disease and may predict the future decline of renal function.

A Proteomics-Based Approach Reveals Differential Regulation of Urine Proteins between Metabolically Healthy and Unhealthy Obese Patients

Metabolic dysfunction associated with obesity threatens to inundate health care resources by increasing the incidences of obesity-related diseases. The aim of the present study was to investigate the changes in the urinary proteome of 18 individuals classified into metabolically healthy obese (MHO) and metabolically unhealthy obese (MUHO) patients. Proteome analysis was performed using the two-dimensional difference in gel electrophoresis (2D-DIGE) coupled with mass spectrometry (MS). Upon analysis, a total of 54 proteins were found to be affected with ≥1.5-fold change (ANOVA, p ≤ 0.05), of which 44 proteins were upregulated and 10 proteins were downregulated. These differentially abundant proteins were related to nuclear factor κB (NF-κB) and p38 mitogen-activated protein (MAP) kinase pathways and were involved in cellular compromise, inflammatory response, and cancer. Proteins involved in inflammation (fibrinogen alpha (FIBA), serotransferrin (TRFE, and kininogen-1 (KNG1)) and insulin resistance (ADP-ribosylation factor (ARF)-like protein 15 (ARL15) and retinol-binding protein 4 (RET4)) were found to be significantly increased in the urine samples of MUHO compared to MHO patients. Investigating the effects of obesity on urinary proteins can help in developing efficient diagnostic procedures for early detection and prevention of obesity-related complications.

Molecular Imaging of the Glomerulus via Mesangial Cell Uptake of Radiolabeled Tilmanocept

An unmet need for the clinical management of chronic kidney disease is a predictive tool of kidney function during the first decade of the disease, when there is silent loss of glomerular function. The objective of this study was to demonstrate receptor-mediated binding of tilmanocept to CD206 within the kidney and provide evidence of kinetic sensitivity of this binding to renal function. Methods: Rats were positioned in a PET scanner with the liver and kidneys within the field of view. After an intravenous injection of 68Ga-IRDye800-tilmanocept, using 1 of 2 scaled molar doses (0.02 nmol/g, n = 5; or 0.10 nmol/g, n = 5), or coinjection (n = 3) of 68Ga-IRDye800-tilmanocept (0.10 nmol/g) and unlabeled tilmanocept (5.0 nmol/g), or a negative control, 68Ga-IRDye800-DTPA-galactosyl-dextran (0.02 nmol/g, n = 5), each animal was imaged for 20 min followed by a whole-body scan. Frozen kidney sections were stained for podocytes and CD206 using immunofluorescence. Molecular imaging of diabetic db/db mice (4.9 wk, n = 6; 7.3 wk, n = 4; 13.3 wk, n = 6) and nondiabetic db/m mice (n = 6) was performed with fluorescence-labeled 99mTc-tilmanocept (18.5 MBq, 2.6 nmol). Thirty minutes after injection, blood, liver, kidneys, and urine were assayed for radioactivity. Renal time-activity curves were generated. Results: Rat PET whole-body images and time-activity curves of 68Ga-IRDye800-tilmanocept demonstrated receptor-mediated renal accumulation with evidence of glomerular uptake. Activity within the renal cortex persisted during the 40-min study. Histologic examination demonstrated colocalization of CD206 and IRDye800-tilmanocept within the glomerulus. The glomerular accumulation of the coinjection and the negative control studies were significantly less than the CD206-targeted agent. The db/db mice displayed a multiphasic renal time-activity curve with high urinary bladder accumulation; the nondiabetic mice exhibited renal uptake curves dominated by a single phase with low bladder accumulation. Conclusion: This study demonstrated receptor-mediated binding to the glomerular mesangial cells and kinetic sensitivity of tilmanocept to chronic renal disease. Given the role of mesangial cells during the progression of diabetic nephropathy, PET or SPECT renal imaging with radiolabeled tilmanocept may provide a noninvasive quantitative assessment of glomerular function.

Detection and Characterization of a Biochemical Signature Associated with Diabetic Nephropathy Using Near-infrared Spectroscopy on Tissue Sections

Histological evaluation of renal biopsies is currently the gold standard for acquiring important diagnostic and prognostic information in diabetic nephropathy (DN) patients. Nevertheless, there is an unmet clinical need for new biomarkers that allow earlier diagnosis and risk stratification. As biochemical changes in tissues must precede any symptomatic or morphological expression of a disease, we explored the potential of near-infrared (NIR) spectroscopy in the detection of a biochemical signature associated with DN. Kidney tissue sections were investigated using NIR spectroscopy, followed by principal component analysis and soft independent modelling of class analogy. A biochemical signature indicative of DN was detected, which enabled perfect discrimination between tissue sections with normal histological findings (n = 27) and sections obtained from DN patients (n = 26). Some spectral changes related to carbamoylation and glycation reactions appeared to be similar to the ones obtained in patients with DN. In addition, treatment with the deglycating enzyme fructosamine-3-kinase resulted in partial to pronounced restorations of the spectral pattern. Significant relationships were found between spectral features and laboratory parameters indicative of glycemic and uremic load, such as hemoglobin A1c, urea, creatinine, estimated glomerular filtration rate, and proteinuria. The presented method could be a useful tool to complement histopathological analysis in order to prevent or delay further disease progression, especially in the setting of post-transplant surveillance kidney biopsies.

Renal effects of glucagon-like peptide receptor agonists in patients with type 1 diabetes mellitus

AIM

The purpose of our study is to assess the effects of glucagon-like peptide-1 receptor agonists (GLP-1R agonists) on early markers of kidney damage in patients with type 1 diabetes mellitus (DM).

MATERIALS AND METHODS

The study included 27 patients with type 1 diabetes with normo- (n=16) and microalbuminuria (n=11) on intensive insulin injection regimen with insulin analogs. Patients were divided into two groups: 15 patients continued insulin therapy throughout the follow-up period, 12 patients were given 1.2 mg GLP-1R agonist (Liraglutide) once a day in addition to the insulin therapy for 6 months. HbA1c, lipid profile, classic markers of kidney damage (albuminuria, creatinine, glomerular filtration rate); plazma (neutrophilic gelatinase-associated lipoxalin - NGAL, molecule renal damage of type 1 - KIM-1, cystatin C, osteopontin) and urinary kidney biomarkers (nephrin, podocyne, uromodulin, NGAL, KIM-1, collagen type IV, cystatin C) were evaluated prior and in dynamics at 6 months. Kidney biomarkers levels were assessed by the enzyme-linked immunosorbent assay (ELISA).

RESULTS

We observed a significant decrease in the urinary excretion of type IV collagen, cystatin C, increased uromodulin excretion and decrease in the plasma levels of osteopontin, NGAL and cystatin C in the group of combined insulin and GLP-1R agonist therapy.

CONCLUSION

Changes in the level of sensitive kidney biomarkers indicate a possible renoprotective effect of GLP-1R agonist therapy in patients with type 1 diabetes at an early stages of kidney damage.

The role of serum and urinary biomarkers in the diagnosis of early diabetic nephropathy in patients with type 2 diabetes

Background

Previous studies have shown that a variety of biomarkers are closely related to the occurrence and development of early-stage diabetic nephropathy (DN) in patients. The aim of this study was to evaluate the role of multiple sera and urinary biomarkers in the diagnosis of early-stage DN in patients with type 2 diabetes.

Methods

We enrolled 287 patients with type 2 diabetes, who were classified into normoalbuminuria (n = 144), microalbuminuria (n = 94), or macroalbuminuria (n = 49) groups based on their urine albumin to creatinine ratios (UACR), along with 42 healthy controls. We assessed 13 biomarkers, including transferrin (Tf), immunoglobulin G (IgG), podocalyxin, neutrophil gelatinase-associated lipocalin (NGAL), N-acetyl-beta-glucosaminidase, α-1-microglobulin, 8-hydroxy-deoxyguanosine, tumor necrosis factor-alpha (TNF-α), and interleukin-18 in urine samples, along with cystatin C, total bilirubin, and uric acid in sera samples, to evaluate their diagnostic roles. From the measurements, the blood neutrophil to lymphocyte ratio was also calculated.

Results

Urinary Tf, IgG, NGAL, and TNF-α were significantly related to the UACR. We calculated the area under the receiver operating characteristic curves (area under the curve) and found that urinary IgG (0.894), NGAL (0.875), Tf (0.861), TNF-α (0.763), and the combination of urinary Tf + IgG + TNF-α + NGAL (0.922) showed good diagnostic value for early-stage DN.

Conclusions

Urinary Tf, IgG, NGAL, TNF-α, and the combination of all four biomarkers demonstrated excellent diagnostic value for early-stage DN in patients with type 2 diabetes.

Involvement of Elf3 on Smad3 activation-dependent injuries in podocytes and excretion of urinary exosome in diabetic nephropathy

Diabetic nephropathy (DN) is among the most serious complications of diabetes mellitus, and often leads to end-stage renal disease ultimately requiring dialysis or renal transplantation. The loss of podocytes has been reported to have a role in the onset and progression of DN. Here, we addressed the activation mechanism of Smad3 signaling in podocytes. Expression of RII and activation of Smad3 were induced by AGE exposure (P<0.05). Reduction of the activation of RII-Smad3 signaling ameliorated podocyte injuries in Smad3-knockout diabetic mice. The bone morphogenetic protein 4 (BMP4) significantly regulated activation of RII-Smad3 signalings (P<0.05). Moreover, the epithelium-specific transcription factor, Elf3was induced by AGE stimulation and, subsequently, upregulated RII expression in cultured podocytes. Induction of Elf3 and activation of RII-Smad3 signaling, leading to a decrease in WT1 expression, were observed in podocytes in diabetic human kidneys. Moreover, AGE treatment induced the secretion of Elf3-containing exosomes from cultured podocytes, which was dependent on the activation of the TGF-β-Smad3 signaling pathway. In addition, exosomal Elf3 protein in urine could be measured only in urinary exosomes from patients with DN. The appearance of urinary exosomal Elf3 protein in patients with DN suggested the existence of irreversible injuries in podocytes. The rate of decline in the estimated Glomerular Filtration Rate (eGFR) after measurement of urinary exosomal Elf3 protein levels in patients with DN (R² = 0.7259) might be useful as an early non-invasive marker for podocyte injuries in DN.

Relationship between Salivary Alpha-2 Macroglobulin and HbA1c among Patients with Type-2 Diabetes Mellitus: A Cross-sectional Study

CONTEXT

Type-2 diabetes mellitus (DM2) requires an adequate glycemic control to avoid diabetic complications. The best parameter available is glycosylated hemoglobin (HbA1c), as it gives us an overview of an individuals' glycemic control of the previous 4 months. Salivary biomarkers used as a diagnostic tool can indicate the control or degree of progression of diseases. Studies indicate that salivary alpha-2-macroglobulin (A2MG) levels are elevated in diabetes patients.

AIMS

To study the relationship of salivary A2MG with glycosylated Hba1c among patients with DM2.

SETTINGS AND DESIGN

A total of 87 patients of DM2, age 35-65 years were recruited.

MATERIALS AND METHODS

The routine oral cavity examination and dental check-up was done to rule out any dental disease. The patients with hepatic diseases and inflammatory diseases of oral cavity and body were excluded. The values of HbA1c were collected from the records of patients. Salivary A2MG levels were estimated by enzyme-linked immunosorbent assay. Levels of fasting and postprandial blood sugar, serum creatinine, and A2MG were compared with the HbA1c groups (<7 and ≥ 7).

STATISTICAL ANALYSIS USED

Descriptive statistics (Software SPSS version 20.0). Nonparametric Pearson correlation test was used to assess the correlation between HbA1c and A2MG.

RESULTS

A positive correlation between salivary levels of A2MG and blood levels of HbA1c in blood was observed in this study. Results showed that there was also a significant correlation in mean values of fasting and postprandial blood sugar, serum creatinine, and salivary A2MG in diabetic subjects.

CONCLUSION

Measurement of A2MG in saliva represents a promising noninvasive alternative method to evaluate glycemic index and consequently avoiding comorbidities.

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.

Hedgehog Interacting Protein Promotes Fibrosis and Apoptosis in Glomerular Endothelial Cells in Murine Diabetes

We investigated whether renal hedgehog interacting protein (Hhip) expression contributes to the progression of diabetic nephropathy (DN) and studied its related mechanism(s) in vivo and in vitro. Here, we show that Hhip expression is highly elevated in glomerular endothelial cells of adult type 1 diabetic (T1D) Akita and T2D db/db mouse kidneys as compared to non-diabetic control littermates. Hyperglycemia enhances reactive oxygen species (ROS) generation via NADPH oxidase 4 (Nox4) activation and stimulates renal Hhip gene expression, and that elevated renal Hhip gene expression subsequently activates the TGFβ1- Smad2/3 cascade and promotes endothelial to mesenchymal transition associated with endothelial cell fibrosis/apoptosis in vivo and in vitro. Furthermore, kidneys of low-dose streptozotocin-induced diabetic heterozygous Hhip deficient (Hhip^+/−) mice displayed a normal albumin/creatinine ratio with fewer features of DN (glomerulosclerosis/fibrosis and podocyte apoptosis/loss) and less evidence of renal compensation (glomerular hypertrophy and hyperfiltration) as compared to diabetic wild type controls (Hhip^+/+). Thus, our studies demonstrated that renal Hhip expression is associated with nephropathy development in diabetes and that hyperglycemia-induced renal Hhip expression may mediate glomerular endothelial fibrosis and apoptosis in diabetes, a novel finding.