Plasma Methylglyoxal Levels Are Associated With Amputations and Mortality in Severe Limb Ischemia Patients With and Without Diabetes

Molecular Assessment of Methylglyoxal-Induced Toxicity and Therapeutic Approaches in Various Diseases: Exploring the Interplay with the Glyoxalase System

This comprehensive exploration delves into the intricate interplay of methylglyoxal (MG) and glyoxalase 1 (GLO I) in various physiological and pathological contexts. The linchpin of the narrative revolves around the role of these small molecules in age-related issues, diabetes, obesity, cardiovascular diseases, and neurodegenerative disorders. Methylglyoxal, a reactive dicarbonyl metabolite, takes center stage, becoming a principal player in the development of AGEs and contributing to cell and tissue dysfunction. The dual facets of GLO I-activation and inhibition-unfold as potential therapeutic avenues. Activators, spanning synthetic drugs like candesartan to natural compounds like polyphenols and isothiocyanates, aim to restore GLO I function. These molecular enhancers showcase promising outcomes in conditions such as diabetic retinopathy, kidney disease, and beyond. On the contrary, GLO I inhibitors emerge as crucial players in cancer treatment, offering new possibilities in diseases associated with inflammation and multidrug resistance. The symphony of small molecules, from GLO I activators to inhibitors, presents a nuanced understanding of MG regulation. From natural compounds to synthetic drugs, each element contributes to a molecular orchestra, promising novel interventions and personalized approaches in the pursuit of health and wellbeing. The abstract concludes with an emphasis on the necessity of rigorous clinical trials to validate these findings and acknowledges the importance of individual variability in the complex landscape of health.

Communal interaction of glycation and gut microbes in diabetes mellitus, Alzheimer's disease, and Parkinson's disease pathogenesis

Diabetes and its complications, Alzheimer's disease (AD), and Parkinson's disease (PD) are increasing gradually, reflecting a global threat vis-à-vis expressing the essentiality of a substantial paradigm shift in research and remedial actions. Protein glycation is influenced by several factors, like time, temperature, pH, metal ions, and the half-life of the protein. Surprisingly, most proteins associated with metabolic and neurodegenerative disorders are generally long-lived and hence susceptible to glycation. Remarkably, proteins linked with diabetes, AD, and PD share this characteristic. This modulates protein's structure, aggregation tendency, and toxicity, highlighting renovated attention. Gut microbes and microbial metabolites marked their importance in human health and diseases. Though many scientific shreds of evidence are proposed for possible change and dysbiosis in gut flora in these diseases, very little is known about the mechanisms. Screening and unfolding their functionality in metabolic and neurodegenerative disorders is essential in hunting the gut treasure. Therefore, it is imperative to evaluate the role of glycation as a common link in diabetes and neurodegenerative diseases, which helps to clarify if modulation of nonenzymatic glycation may act as a beneficial therapeutic strategy and gut microbes/metabolites may answer some of the crucial questions. This review briefly emphasizes the common functional attributes of glycation and gut microbes, the possible linkages, and discusses current treatment options and therapeutic challenges.

Analysis of Methylglyoxal Concentration in a Group of Patients with Newly Diagnosed Prediabetes

BACKGROUND

The abnormal serum concentration of methylglyoxal (MGO) has been presented as an indicator of chronic complications in diabetes (DM). Because such complications are also found in pre-DM, we decided to assess the concentration of this compound in individuals with pre-DM, without cardio-vascular diseases.

METHODS

Frozen samples from individuals newly diagnosed with pre-DM (N = 31) and healthy subjects (N = 11) were prepared and MGO concentration was determined using UHPLC-ESI-QqTOF-MS.

RESULTS

Statistical significance was established when the groups were compared for body weight, BMI, fasting glucose level, fatty liver and use of statins but not for the other descriptive parameters. The positive linear correlation showed that the higher HbA1c, the higher MGO concentration (p = 0.01). The values of MGO were within the normal range in both groups (mean value for pre-DM: 135.44 nM (±SD = 32.67) and for the control group: 143.25 nM (±SD = 17.93); p = 0.46 (±95% CI)), with no statistical significance between the groups.

CONCLUSIONS

We did not confirm the elevated MGO levels in the group of patients with pre-DM. The available data suggests a possible effect of statin intake on MGO levels. This thesis requires confirmation on a larger number of patients with an assessment of MGO levels before and after the introduction of statins.

Utilization of Macroalgae for the Production of Bioactive Compounds and Bioprocesses Using Microbial Biotechnology

To achieve sustainable development, alternative resources should replace conventional resources such as fossil fuels. In marine ecosystems, many macroalgae grow faster than terrestrial plants. Macroalgae are roughly classified as green, red, or brown algae based on their photosynthetic pigments. Brown algae are considered to be a source of physiologically active substances such as polyphenols. Furthermore, some macroalgae can capture approximately 10 times more carbon dioxide from the atmosphere than terrestrial plants. Therefore, they have immense potential for use in the environment. Recently, macroalgae have emerged as a biomass feedstock for bioethanol production owing to their low lignin content and applicability to biorefinery processes. Herein, we provided an overview of the bioconversion of macroalgae into bioactive substances and biofuels using microbial biotechnology, including engineered yeast designed using molecular display technology.

Studies on the synergistic action of methylglyoxal and peroxynitrite on structure and function of human serum albumin

Albumin, an important serum protein, is continuously exposed to various oxidizing/nitrating and glycating agents. Depending upon the nature/concentration of reactive species present, the protein may be glycated, oxidized/nitroxidized or glyco-nitro-oxidized. Peroxynitrite is a powerful nitroxidant and has been reported to damage a wide array of macromolecules. On the other hand, methylglyoxal is a very strong reactive dicarbonyl and a potent precursor for the formation of advanced glycation end products under pathological conditions. In certain pathological conditions albumin may be modified by peroxynitrite and methylglyoxal simultaneously. There is dearth of literature suggests that structural/conformational and functional alteration in albumin upon glycation and oxidation/nitroxidation, however the alterations produced by glyco-nitro-oxidation has not yet been explored. Therefore, in this study, simultaneous effect of glycation and nitroxidation on the structure and conformation, vis-a-vis function of albumin was explored. Glyco-nitro-oxidized albumin showed decreased free amino acid content together with decreased affinity of albumin towards cobalt. Molecular docking model and molecular dynamic simulations showed close interaction and formation of stable complexes between methylglyoxal, peroxynitrite and albumin. Formation of carboxymethyl lysine and 3-nitrotyrosine in glyco-nitro-oxidized albumin were confirmed by MALDI-TOF MS and UP-LC MS. Aggregate formation in glyco-nitro-oxidized albumin was visualized by transmission electron microscopy. On the basis of these results, it may be speculated that, albumin modified with endogenously generated methylglyoxal and peroxynitrite might be a driving factor in the progression of heightened inflammatory autoimmune responses. The work presents a ground to study the role of glyco-nitro-oxidized albumin in the pathogenesis and progression of various autoimmune diseases including rheumatoid arthritis. Communicated by Ramaswamy H. Sarma.

Metformin prevents methylglyoxal-induced apoptosis by suppressing oxidative stress in vitro and in vivo

Methylglyoxal (MGO) is an active metabolite of glucose and plays a prominent role in the pathogenesis of diabetic vascular complications, including endothelial cell apoptosis induced by oxidative stress. Metformin (MET), a widely prescribed antidiabetic agent, appears to reduce excessive reactive oxygen species (ROS) generation and limit cell apoptosis. However, the molecular mechanisms underlying this process are still not fully elucidated. We reported here that MET prevents MGO-induced apoptosis by suppressing oxidative stress in vitro and in vivo. Protein expression and protein phosphorylation were investigated using western blotting, ELISA, and immunohistochemical staining, respectively. Cell viability and apoptosis were assessed by the MTT assay, TUNEL staining, and Annexin V-FITC and propidium iodide double staining. ROS generation and mitochondrial membrane potential (MMP) were measured with fluorescent probes. Our results revealed that MET prevented MGO-induced HUVEC apoptosis, inhibited apoptosis-associated biochemical changes such as loss of MMP, the elevation of the Bax/Bcl-2 ratio, and activation of cleaved caspase-3, and attenuated MGO-induced mitochondrial morphological alterations in a dose-dependent manner. MET pretreatment also significantly suppressed MGO-stimulated ROS production, increased signaling through the ROS-mediated PI3K/Akt and Nrf2/HO-1 pathways, and markedly elevated the levels of its downstream antioxidants. Finally, similar results were obtained in vivo, and we demonstrated that MET prevented MGO-induced oxidative damage, apoptosis, and inflammation. As expected, MET reversed MGO-induced downregulation of Nrf2 and p-Akt. In addition, a PI3K inhibitor (LY-294002) and a Nrf2 inhibitor (ML385) observably attenuated the protective effects of MET on MGO-induced apoptosis and ROS generation by inhibiting the Nrf2/HO-1 pathways, while a ROS scavenger (NAC) and a permeability transition pores inhibitor (CsA) completely reversed these effects. Collectively, these findings broaden our understanding of the mechanism by which MET regulates apoptosis induced by MGO under oxidative stress conditions, with important implications regarding the potential application of MET for the treatment of diabetic vascular complications.

Plasma advanced glycation end products and the subsequent risk of microvascular complications in type 1 diabetes in the DCCT/EDIC

INTRODUCTION

To assess impact of glycemic control on plasma protein-bound advanced glycation end products (pAGEs) and their association with subsequent microvascular disease.

RESEARCH DESIGN AND METHODS

Eleven pAGEs were measured by liquid chromatography-mass spectrometry in banked plasma from 466 participants in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study at three time points (TPs): DCCT year 4 (TP1) and year 8 (TP2) and EDIC year 5/6 (TP3). Correlation coefficients assessed cross-sectional associations, and Cox proportional hazards models assessed associations with subsequent risk of microvascular complications through EDIC year 24.

RESULTS

Glucose-derived glycation products fructose-lysine (FL), glucosepane (GSPN) and carboxymethyl-lysine (CML) decreased with intensive glycemic control at both TP1 and TP2 (p<0.0001) but were similar at TP3, and correlated with hemoglobin A1c (HbA1c). At TP1, the markers were associated with the subsequent risk of several microvascular outcomes. These associations did not remain significant after adjustment for HbA1c, except methionine sulfoxide (MetSOX), which remained associated with diabetic kidney disease. In unadjusted models using all 3 TPs, glucose-derived pAGEs were associated with subsequent risk of proliferative diabetic retinopathy (PDR, p<0.003), clinically significant macular edema (CSME, p<0.015) and confirmed clinical neuropathy (CCN, p<0.018, except CML, not significant (NS)). Adjusted for age, sex, body mass index, diabetes duration and mean updated HbA1c, the associations remained significant for PDR (FL: p<0.002, GSPN: p≤0.02, CML: p<0.003, pentosidine: p<0.02), CMSE (CML: p<0.03), albuminuria (FL: p<0.02, CML: p<0.03) and CCN (FL: p<0.005, GSPN : p<0.003).

CONCLUSIONS

pAGEs at TP1 are not superior to HbA1c for risk prediction, but glucose-derived pAGEs at three TPs and MetSOX remain robustly associated with progression of microvascular complications in type 1 diabetes even after adjustment for HbA1c and other factors.

Principal predictors of major adverse limb events in diabetic peripheral artery disease: A narrative review

Background and aims

The increasing prevalence of diabetes mellitus is causing a massive growth of peripheral artery disease incidences, a disabling complication of diabetic atherosclerosis, which leads often to the amputation of the affected limb. Critical limb ischemia is the terminal disease stage, which requires a prompt intervention to relieve pain and save limbs. However, patients undergoing revascularization often suffer from cardiovascular, cerebrovascular and major adverse limb events with poor outcomes. Furthermore, the same procedure performed in apparently similar patients has various outcomes and lack of an outcome predictive support causes a high lower limb arterial revascularization rate with disastrous effects for patients. We collected the main risk factors of major adverse limb events in a more readable and immediate format of the topic, to propose an overview of parameters to manage effectively peripheral artery disease patients and to propose basics of a new predictive tool to prevent from disabling vascular complications of the disease.

Methods

Most recent and updated literature about the prevalence of major adverse limb events in peripheral artery disease was reviewed to identify possible main predictors.

Results

In this article, we summarized major risk factors of limb revascularization failure and disabling vascular complications collecting those parameters principally responsible for major adverse limb events, which provides physio-pathological explanation of their role in peripheral artery disease.

Conclusion

We evaluated and listed a panel of possible predictors of MALE (Major Adverse Limb Event) in order to contribute to the development of a predictive score, based on a summary of the main risk factors reported in scientific articles, which could improve the management of peripheral artery disease by preventing vascular accidents.

The Putative Role of Methylglyoxal in Arterial Stiffening: A Review

BACKGROUND

Arterial stiffening is a hallmark of vascular ageing and a consequence of many diseases including diabetes mellitus. Methylglyoxal (MGO), a highly reactive α-dicarbonyl mainly formed during glycolysis, has emerged as a potential contributor to the development of arterial stiffness. MGO reacts with arginine and lysine residues in proteins to form stable advanced glycation endproducts (AGEs). AGEs may contribute to arterial stiffening by increased cross-linking of collagen within the extracellular matrix (ECM), by altering the vascular structure, and by triggering inflammatory and oxidative pathways. Although arterial stiffness is mainly determined by ECM and vascular smooth muscle cell function, the effects of MGO and MGO-derived AGEs on these structures have not been thoroughly reviewed to date.

METHODS AND RESULTS

We conducted a PubMed search without filtering for publication date which resulted in 16 experimental and 22 clinical studies eligible for inclusion. Remarkably, none of the experimental and only three of the clinical studies specifically mentioned MGO-derived AGEs. Almost all studies reported an association between arterial stiffness and AGE accumulation in the arterial wall or increased plasma AGEs. Other studies report reduced arterial stiffness in experimental models upon administration of AGE-breakers.

CONCLUSIONS

No papers published to date directly show an association between MGO or MGO-derived AGEs and arterial stiffening. The relevance of the various underlying mechanisms is not yet clear, which is particularly due to methodological challenges in the detection of MGO and MGO-derived AGEs at the molecular, intra- and pericellular, and structural levels, as well as in challenges in the assessment of intrinsic arterial wall properties at ECM- and tissue levels.