Circulating Concentrations of advanced Glycation end Products, Carboxymethyl Lysine and Methylglyoxal are Associated With Renal Function in Individuals With Diabetes

An immunosensor for the detection of N-(carboxymethyl)lysine - a diabetic biomarker

Carboxymethyl-lysine (CML) is a well-known lysine product that strongly correlates with type 2 diabetes mellitus (T2DM), and its elevated levels are significantly associated with renal impairment and T2DM-related complications. Thus, it is imperative to quantify CML levels and recognize the onset of hyperglycemia and its consequences. In this context, the development of an electrochemical immunosensor for the rapid and ultralow-level detection of CML was attempted. The fabrication of the working electrode involves the covalent immobilization of anti-CML/EDC-NHS on the surface of a carbon quantum dot (CQD)-modified glassy carbon electrode (GCE). The immunosensor exhibited two discrete linear concentration ranges of 0.5-5.0 ng mL-1 and 5.5-10.0 ng mL-1, with limits of detection and quantification of 0.027 and 0.087 ng mL-1 and 0.16 and 0.51 ng mL-1, respectively. The observed specificity and other merits of the sensor make it suitable for testing human plasma samples.

Potential association between magnesium depletion score and hyperuricemia in American adults, a cross-sectional study based on NHANES 2003-2018

Objective

The pathophysiological mechanisms underlying hyperuricemia necessitate the identification of contributing factors to better understand disease progression and develop effective therapies. This study aimed to investigate the association between Magnesium Depletion Score (MDS) and hyperuricemia.

Methods

A cross-sectional study was sourced from the National Health and Nutrition Examination Survey 2003-2018. Hyperuricemia was defined by serum uric acid levels. MDS was calculated by incorporating factors affecting renal magnesium reabsorption.Weighted multivariable logistic regression was employed to assess the association between MDS and hyperuricemia, with sensitivity analyses to confirm robustness. Additionally, Restricted Cubic Spline (RCS) and Receiver Operating Characteristic (ROC) curve analyses were used to further elucidate the relationship.

Results

Compared to the low MDS group (0-1), the odds ratios (OR) and 95 % confidence intervals (CI) for the middle MDS group (2) and high MDS group (3-5) were 1.76 (1.52-2.04), and 3.14(2.54-3.88), respectively. The RCS analysis illustrated a linear dose-response relationship between MDS and hyperuricemia. The ROC analysis demonstrated that MDS had an area under the curve of 0.720 (95 % CI, 0.717-0.721).

Conclusions

This study highlights a strong association between MDS and hyperuricemia risk, emphasizing the importance of addressing magnesium deficiency in hyperuricemic patients.

The Potential Role of Advanced Glycation End Products in the Development of Kidney Disease

Advanced glycation end products (AGEs) represent a class of toxic and irreversible compounds formed through non-enzymatic reactions between proteins or lipids and carbonyl compounds. AGEs can arise endogenously under normal metabolic conditions and in pathological states such as diabetes, kidney disease, and inflammatory disorders. Additionally, they can be obtained exogenously through dietary intake, particularly from foods high in fat or sugar, as well as grilled and processed items. AGEs accumulate in various organs and have been increasingly recognized as significant contributors to the progression of numerous diseases, particularly kidney disease. As the kidney plays a crucial role in AGE metabolism and excretion, it is highly susceptible to AGE-induced damage. In this review, we provide a comprehensive discussion on the role of AGEs in the onset and progression of various kidney diseases, including diabetic nephropathy, chronic kidney disease, and acute kidney injury. We explore the potential biological mechanisms involved, such as AGE accumulation, the AGEs-RAGE axis, oxidative stress, inflammation, gut microbiota dysbiosis, and AGE-induced DNA damage. Furthermore, we discuss recent findings on the metabolic characteristics of AGEs in vivo and their pathogenic impact on renal function. Additionally, we examine the clinical significance of AGEs in the early diagnosis, treatment, and prognosis of kidney diseases, highlighting their potential as biomarkers and therapeutic targets. By integrating recent advancements in AGE research, this review aims to provide new insights and strategies for mitigating AGE-related renal damage and improving kidney disease management.

Transcriptome and single-cell profiling of the mechanism of diabetic kidney disease

BACKGROUND

The NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome may play an important role in diabetic kidney disease (DKD). However, the exact link remains unclear.

AIM

To investigate the role of the NLRP3 inflammasome in DKD.

METHODS

Using datasets from the Gene Expression Omnibus database, 30 NLRP3 inflammasome-related genes were identified. Differentially expressed genes were selected using differential expression analysis, whereas intersecting genes were selected based on overlapping differentially expressed genes and NLRP3 inflammasome-related genes. Subsequently, three machine learning algorithms were used to screen genes, and biomarkers were identified by overlapping the genes from the three algorithms. Potential biomarkers were validated by western blotting in a db/db mouse model of diabetes.

RESULTS

Two biomarkers, sirtuin 2 (SIRT2) and caspase 1 (CASP1), involved in the Leishmania infection pathway were identified. Both biomarkers were expressed in endothelial cells. Pseudo-temporal analysis based on endothelial cells showed that DKD mostly occurs during the mid-differentiation stage. Western blotting results showed that CASP1 expression was higher in the DKD group than in the control group (P < 0.05), and SIRT2 content decreased (P < 0.05).

CONCLUSION

SIRT2 and CASP1 provide a potential theoretical basis for DKD treatment.

Serum advanced glycation end products as a putative biomarker in Type2 DKD patients' prognosis

Aim

Advanced glycation end products (AGEs) are pivotal mediators in diabetic kidney disease (DKD). However, their prognostic utility remains underexplored. This study introduced corrected lgAGEs [novel biomarker derived by adjusting logarithmically transformed AGEs (lgAGEs) levels based on serum albumin (ALB) levels] to enhance the prediction of adverse renal outcomes in patients with type 2 DKD (T2DKD).

Methods

In this prospective cohort study, 196 T2DKD patients were followed up longitudinally. Serum AGEs levels were log-transformed and adjusted for ALB to calculate corrected lgAGEs. Participants were stratified into the high- and low-level groups based on the median corrected lgAGEs. The association between corrected lgAGEs and renal outcomes was assessed using Cox proportional hazards models. Receiver operating characteristic (ROC) curve was utilized to evaluate the predictive performance of corrected lgAGEs alone and in combination with the urinary albumin-to-creatinine ratio (UACR).

Results

High level of corrected lgAGEs was independently associated with adverse renal outcomes [hazard ratio (HR), 3.252; 95% confidence interval (CI), 1.461-7.243; p = 0.003]. Kaplan-Meier analysis demonstrated that patients in the high-level group (12 months) exhibited significantly shorter median survival times compared with those in the low-level group (50 months). ROC analysis showed that UACR alone had an area under the curve (AUC) of 0.782 (95% CI, 0.705-0.858), with 82.8% sensitivity and 61.5% specificity. Corrected lgAGEs achieved an AUC of 0.725 (95% CI, 0.637-0.814), with 69.0% sensitivity and 76.9% specificity. Combining UACR and corrected lgAGEs improved the specificity to 75.6%, with an AUC of 0.764 (95% CI, 0.682-0.847), while maintaining a sensitivity of 70.7%.

Conclusion

Corrected lgAGEs are novel and independent biomarkers for predicting adverse renal outcomes in T2DKD. Combining UACR with corrected lgAGEs could enhance risk stratification by improving the specificity, highlighting its potential application in early identification of high-risk patients. These findings should be validated in broader populations in future research.

Phloroglucinol ameliorated methylglyoxal induced harmful effects in rats

Glycation is among the underlying mechanisms attributed to ageing and associated morbidities. There is no drug available to combat this deleterious phenomenon. The present study aimed to explore phloroglucinol (PHL) for its anti-glycation potential at preclinical level. The rats were treated with methylglyoxal (MGO, 17.25 mg/kg, i.p. for 14 days) to induce glvcative stress. The treatment groups received additional administration of test drug (PHL; 0.25mg/kg, 0.5mg/kg, and 1mg/kg) or standard aminoguanidine (AG, 50 mg/kg) or saline (control, 5ml/kg). During 14 days, the weight and food intake was noted. Afterwards, the cognitive function was evaluated using Morris Water Maze (MWM) while hepatic and renal functions were assessed through liver function test (bilirubin, alkaline phosphatase, SGPT, and SGOT) and creatinine respectively, using chemical analyzer. The carboxymethyllysine (CML) levels were quantified in the blood using ELISA technique. Histopathological study was performed on the brain, liver, and kidney using H&E staining. Additionally, the qPCR was used to quantify the expression of TNF-α, RAGE and BACE-1 (brain), RAGE, TNF-α, and glyoxalase-I (liver) and RAGE, TNF-α, and VEGF (kidney), while glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as a reference housekeeping gene. The data regarding weight and food intake did not reveal significant alterations. In MWM, the MGO treatment caused significant increase in the time to reach target quadrant, while decrease in the time spent in target quadrant and number of crossings through platform position. All these effects were inhibited by both AG and PHL. The navigation maps also exhibit that the retention of spatial memory. Additionally, the MGO-induced alteration in hepatic and renal function indicators was ameliorated by both AG and PHL treatments. The plasma CML levels were found to be elevated following MGO treatment, while the concomitant administration of AG and PHL has resisted this raise. Histopathological assessment revealed no specific pathology in liver kidney and brain tissues. The qPCR data revealed enhanced expression of all genes, especially TNF-α and BACE, which were found to be reduced following both AG and PHL treatments. PHL prevented the brain, hepatic, and renal impairments caused by MGO induced glycative stress. Hence, the PHL, a clinically used anti-spasmodic drug, presents itself as a potential candidate to be repurposed as anti-glycation drug.

Investigation of Advanced Glycation End Products in Liver, Adipose, and Renal Tissue of Mice on a High-Fat Diet

Obesity is a complex condition associated with disruptions in carbohydrate, protein, and fat metabolism, linked to increased insulin resistance and glucose intolerance. High levels of Advanced Glycation End-products (AGEs) are associated with a range of chronic diseases, including kidney diseases, diabetic complications, cardiovascular diseases, and neurodegenerative diseases. Our study aims to investigate the accumulation of AGEs in the liver, renal and adipose tissues of mice fed a high-fat diet, contributing to a deeper understanding of obesity and its related metabolic disorders. Our study consists of three different groups fed with diets containing 60% and 10% fat. The Experiment 1 group was maintained on their diet for 12 weeks, while the obese 2 and control groups continued their diets for 24 weeks. AGEs in the liver and kidney tissues obtained were measured using the High-performance liquid chromatography grade (HPLC) method. Higher accumulation of AGEs has been observed in kidney tissue compared to adipose and liver tissues (p < 0.05). Moreover, the GO levels were notably higher in liver tissue than in adipose tissue of the D1 and D2 groups (p < 0.0001). Our results suggest that particularly in kidney tissue, increased filtration burden, functional impairment, and receptor interaction due to obesity may be effective. The lower levels of AGEs detected, especially in the obese groups compared to the control, can be attributed to the inability to metabolize AGEs due to tissue damage caused by obesity.