Aging is a multifactorial process that involves changes at the cellular, tissue, organ and the whole body levels resulting in decreased functioning, development of diseases, and ultimately death. O...

Oxidative stress and aging: is methylglyoxal the hidden enemy?

Methylglyoxal promotes oxidative stress and endothelial dysfunction

Metabolic abnormalities such as dyslipidemia, hyperinsulinemia, or insulin resistance and obesity play key roles in the induction and progression of type 2 diabetes mellitus (T2DM). The field of immunometabolism implies a bidirectional link between the immune system and metabolism, in which inflammation plays an essential role in the promotion of metabolic abnormalities (e.g., obesity and T2DM), and metabolic factors, in turn, regulate immune cell functions. Obesity as the main inducer of a systemic low-level inflammation is a main susceptibility factor for T2DM. Obesity-related immune cell infiltration, inflammation, and increased oxidative stress promote metabolic impairments in the insulin-sensitive tissues and finally, insulin resistance, organ failure, and premature aging occur. Hyperglycemia and the subsequent inflammation are the main causes of micro- and macroangiopathies in the circulatory system. They also promote the gut microbiota dysbiosis, increased intestinal permeability, and fatty liver disease. The impaired immune system together with metabolic imbalance also increases the susceptibility of patients to several pathogenic agents such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Thus, the need for a proper immunization protocol among such patients is granted. The focus of the current review is to explore metabolic and immunological abnormalities affecting several organs of T2DM patients and explain the mechanisms, whereby diabetic patients become more susceptible to infectious diseases.

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The Effects of Type 2 Diabetes Mellitus on Organ Metabolism and the Immune System.

Methylglyoxal (MGO), a dicarbonyl metabolite produced by all living cells, has been associated with a number of human diseases. However, studies of the role(s) MGO plays biologically have been handicapped by a lack of direct methods for its monitoring and detection. To address this limitation, we have developed a fluorescent sensor (methyl diaminobenzene-BODIPY, or "MBo") that can detect MGO under physiological conditions. We show that MBo is selective for MGO over other biologically relevant dicarbonyls and is suitable for detecting MGO in complex environments, including that of living cells. In addition, we demonstrate MBo's utility in estimating plasma concentrations of MGO. The results reported herein have the potential to advance both clinical and basic science research and practice.

A “Turn-On” Fluorescent Sensor for Methylglyoxal

OBJECTIVE The incidence of high dietary carbohydrate-induced type 2 diabetes is increasing worldwide. Methylglyoxal (MG) is a reactive glucose metabolite and a major precursor of advanced glycation end products (AGEs). MG levels are elevated in diabetic patients. We investigated the effects of chronic administration of MG on glucose tolerance and β-cell insulin secreting mechanism in 12-week-old male Sprague-Dawley rats. RESEARCH DESIGN AND METHODS MG (60 mg/kg/day) or 0.9% saline was administered by continuous infusion with a minipump for 28 days. We performed glucose and insulin tolerance tests and measured adipose tissue glucose uptake and insulin secretion from isolated pancreatic islets. We also used cultured INS-1E cells, a pancreatic β-cell line, for molecular studies. Western blotting, quantitative PCR, immunohistochemistry, and transferase-mediated dUTP nick-end labeling (TUNEL) assay were performed. RESULTS In rats treated with MG and MG + l-buthionine sulfoximine (BSO), MG levels were significantly elevated in plasma, pancreas, adipose tissue, and skeletal muscle; fasting plasma glucose was elevated, whereas insulin and glutathione were reduced. These two groups also had impaired glucose tolerance, reduced GLUT-4, phosphoinositide-3-kinase activity, and insulin-stimulated glucose uptake in adipose tissue. In the pancreatic β-cells, MG and MG + BSO reduced insulin secretion, pancreatic duodenal homeobox-1, MafA, GLUT-2, and glucokinase expression; increased C/EBPβ, nuclear factor-κB, MG-induced AGE, N e -carboxymeythyllysine, and receptor for AGEs expression; and caused apoptosis. Alagebrium, an MG scavenger and an AGE-breaking compound, attenuated the effects of MG. CONCLUSIONS Chronic MG induces biochemical and molecular abnormalities characteristic of type 2 diabetes and is a possible mediator of high carbohydrate-induced type 2 diabetes.

https://diabetes.diabetesjournals.org/content/diabetes/60/3/899.full.pdf

Qing H. Meng

Papers

Proinflammatory and proapoptotic effects of methylglyoxal on neutrophils from patients with type 2 diabetes mellitus.