Advanced glycation end products as predictors of renal function in youth with type 1 diabetes

Development of simultaneous quantitation method for 20 free advanced glycation end products using UPLC-MS/MS and clinical application in kidney injury

Advanced glycation end products (AGEs), derived from the non-enzymatic glycation reaction, are defined as glycotoxins in various diseases including aging, diabetes and kidney injury. Exploring AGEs as potential biomarkers for these diseases holds paramount significance. Nevertheless, the high chemical structural similarity and great heterogeneity among AGEs present a formidable challenge when it comes to the comprehensive, simultaneous, and accurate detection of multiple AGEs in biological samples. In this study, an UPLC/MS/MS method for simultaneous quantification of 20 free AGEs in human serum was firstly established and applied to quantification of clinical samples from individuals with kidney injury. Simple sample preparation method through protein precipitation without derivatization was used. Method performances including imprecision, accuracy, sensitivity, linearity, and carryover were systematically validated. Intra- and inter- imprecision of 20 free AGEs were 1.93-5.94 % and 2.30-8.55 %, respectively. The method accuracy was confirmed with good recoveries ranging from 96.40 % to 103.25 %. The LOD and LOQ were 0.1-3.13 ng/mL and 0.5-6.25 ng/mL, respectively. Additionally, the 20 free AGEs displayed excellent linearity (R2 >0.9974) across a wide linear range (1.56-400 ng/mL). Finally, through simultaneous quantitation of 20 Free AGEs in 100 participants including kidney injury patient and healthy controls, we identified six free AGEs, including N6-carboxyethyl-L-arginine (CEA), N6-carboxymethyl-L-lysine (CML), methylglyoxal-derived hydroimidazolones (MG-H), N6-formyl-lysine, N6-carboxymethyl-L-arginine (CMA), and glyoxal-derived hydroimidazolone (G-H), could well distinguish kidney injury patients and healthy individuals. Among them, the levels of four free AGEs including CML, CEA, MG-H, and G-H strongly correlate with traditionally clinical markers of kidney disease. The high area under the curve (AUC) values (AUC=0.965) in receiver operating characteristic (ROC) curve indicated that these four free AGEs can be served as combined diagnostic biomarkers for the diagnosis of kidney disease.

Evaluation of Serum Advanced Glycation End Product Levels and Microvascular Complications in Children and Adolescents with Type 1 Diabetes Mellitus

OBJECTIVE

Advanced glycation end products (AGEs) are irreversible macromolecules formed by nonenzymatic reactions due to chronic hyperglycemia. The aim of this study was to assess the relationship between AGEs and the microvascular complications of children and adolescents with type 1 diabetes mellitus (T1DM).

MATERIALS AND METHODS

Twenty-six T1DM patients with microvascular complications and 58 complication-naive patients who were similar regarding age, sex, and pubertal status enrolled in the study. Anthropometric, biochemical, ophthalmologic, and neurologic variables were compared with serum AGEs levels by the fluorescence method.

RESULTS

There was no significant difference observed between the patients with complications and those without complications in terms of serum levels of AGEs and other biochemical parameters. However, the duration of T1DM and urine microalbumin-creatinine ratio (uACR) were significantly higher in the complication-positive group (P < .001). Serum levels of AGEs were found to be similar when retinopathy, peripheral, and optic neuropathy were separately compared with the complication-naive group (P > .05). However, patients with nephropathy had significantly higher serum levels of AGEs than patients without complications (P = .023). In addition, there was a significant positive correlation between serum AGEs levels and uACR (P = .042) but not other parameters (P > .05).

CONCLUSION

This study is the first to evaluate the association between serum AGEs levels and microvascular complications in children and adolescents with T1DM. Our study highlights that serum AGEs levels are significantly correlated with nephropathy but not with retinopathy and neuropathy. Further long-term studies with a larger sample size are required to establish a better relationship between diabetic complications and AGEs. Cite this article as: Kırkgöz T, Acar S, Küme T, et al. Evaluation of serum advanced glycation end product levels and microvascular complications in children and adolescents with type 1 diabetes mellitus. Turk Arch Pediatr. 2024;59(1):31-37.

Methylglyoxal and Its Adducts: Induction, Repair, and Association with Disease

Metabolism is an essential part of life that provides energy for cell growth. During metabolic flux, reactive electrophiles are produced that covalently modify macromolecules, leading to detrimental cellular effects. Methylglyoxal (MG) is an abundant electrophile formed from lipid, protein, and glucose metabolism at intracellular levels of 1-4 μM. MG covalently modifies DNA, RNA, and protein, forming advanced glycation end products (MG-AGEs). MG and MG-AGEs are associated with the onset and progression of many pathologies including diabetes, cancer, and liver and kidney disease. Regulating MG and MG-AGEs is a potential strategy to prevent disease, and they may also have utility as biomarkers to predict disease risk, onset, and progression. Here, we review recent advances and knowledge surrounding MG, including its production and elimination, mechanisms of MG-AGEs formation, the physiological impact of MG and MG-AGEs in disease onset and progression, and the latter in the context of its receptor RAGE. We also discuss methods for measuring MG and MG-AGEs and their clinical application as prognostic biomarkers to allow for early detection and intervention prior to disease onset. Finally, we consider relevant clinical applications and current therapeutic strategies aimed at targeting MG, MG-AGEs, and RAGE to ultimately improve patient outcomes.

Advanced Glycation End Products (AGEs) and Chronic Kidney Disease: Does the Modern Diet AGE the Kidney?

Since the 1980s, chronic kidney disease (CKD) affecting all ages has increased by almost 25%. This increase may be partially attributable to lifestyle changes and increased global consumption of a “western” diet, which is typically energy dense, low in fruits and vegetables, and high in animal protein and ultra-processed foods. These modern food trends have led to an increase in the consumption of advanced glycation end products (AGEs) in conjunction with increased metabolic dysfunction, obesity and diabetes, which facilitates production of endogenous AGEs within the body. When in excess, AGEs can be pathological via both receptor-mediated and non-receptor-mediated pathways. The kidney, as a major site for AGE clearance, is particularly vulnerable to AGE-mediated damage and increases in circulating AGEs align with risk of CKD and all-cause mortality. Furthermore, individuals with significant loss of renal function show increased AGE burden, particularly with uraemia, and there is some evidence that AGE lowering via diet or pharmacological inhibition may be beneficial for CKD. This review discusses the pathways that drive AGE formation and regulation within the body. This includes AGE receptor interactions and pathways of AGE-mediated pathology with a focus on the contribution of diet on endogenous AGE production and dietary AGE consumption to these processes. We then analyse the contribution of AGEs to kidney disease, the evidence for dietary AGEs and endogenously produced AGEs in driving pathogenesis in diabetic and non-diabetic kidney disease and the potential for AGE targeted therapies in kidney disease.