Advanced glycation end-products: modifiable environmental factors profoundly mediate insulin resistance

Natural polysaccharides: The potential biomacromolecules for treating diabetes and its complications via AGEs-RAGE-oxidative stress axis

Diabetes mellitus, a chronic metabolic disorder, poses a significantly public health challenge. Extensive research highlights that contemporary dietary patterns, characterized by excessive intake of sugar, fat, and protein, are major contributors to the onset and progression of diabetes. The central element to this process is the aberrant activation of the advanced glycation end products (AGEs) - receptor for AGEs (RAGE) - oxidative stress axis, which plays a pivotal role in disrupting normal carbohydrate metabolism. This pathway presents a critical target for developing interventions aimed at mitigating diabetes and its complications. In recent years, natural polysaccharides have emerged as promising agents in the prevention and treatment of diabetes, due to their ability to inhibit AGE formation, regulate RAGE expression, and modulate the AGEs-RAGE-oxidative stress axis. In this paper, we explore the pathogenic mechanism of this axis and review the therapeutic potential of natural polysaccharides in managing diabetes and its complications. Our goal is to provide new insights for the effective management of diabetes and its associated health challenges.

Effect of low vs high dietary-advanced glycation end products on insulin-sensitivity and inflammatory- markers among overweight/obese Asian-Indian adults-A randomised controlled trial

The present study investigated the effect of low vs high-dietary-Advanced Glycation End products-based diets on oral disposition index-(DIo)-a marker of islet β-cell function and cardiometabolic risks factors in 38-overweight and obese Asian Indian-adults (aged 25-45 years with body-mass-index (BMI) ≥23kg/m2) through 12-week isocaloric crossover feeding trial. Biochemical-measures included-glucose tolerance test (GTT), Insulin assay (0,30 and 120 min), lipid-profile, serum-adiponectin, serum-AGE and serum-Thiobarbituric acid reactive substances-(TBARS) assessed both at baseline and end of each intervention. Generalised linear models showed that low-dAGE diet significantly improved in oral disposition index [Least Square Mean (SE), +0.3 (0.1); p = 0.03] compared to high-dAGE diet. The low-dAGE diet also showed a significant reduction in 30-minutes plasmapost-glucose-challenge-value:(-8.1[3.8] (mg/dl) vs 3.8 [3.8] (mg/dl); p = 0.01), serum-AGEs-(-3.2 [0.2] (μg/ml) vs -0.8 [0.2] (μg/ml); p = <0.0001) compared to high-dAGE diet. In summary, low-dAGE diets exhibited improvement in the insulin-sensitivity and reduction in the inflammatory levels compared to high-dAGE diets. Hence, study first time in India revealed that low dAGE diets could be a potential strategy to reduce diabetes risk.

Efficient purification of soluble receptor for advanced glycation end-products from Sus scrofa lung tissue and synthesis of its binding ligand, glycated bovine serum albumin

A receptor for advanced glycation end products (RAGE) has emerged as a crucial player in various pathological conditions due to its involvement in inflammation and cellular dysfunction. Its soluble isoform, sRAGE, has garnered significant attention for its competitive inhibitory effects and potential therapeutic applications. However, obtaining sRAGE with appropriate glycosylation patterns for binding to glycated proteins has been challenging, often requiring costly expression systems. Here, we present a novel approach for producing and purifying sRAGE from Sus scrofa lungs, bypassing the need for expensive expression systems. Previous protocols for sRAGE extraction faced reproducibility issues due to high viscosity and haemoglobin content of the solution. To address this, we developed a method for selective haemoglobin precipitation using a zinc-containing buffer, enabling purification via various chromatographic methods. Through a combination of chromatographic techniques, we obtained sRAGE in suitable purity, identified using HPLC-MS/MS. Additionally, producing glycated proteins for RAGE receptor activation often involved lengthy protocols or inadequate separation from reactants. Thus, we devised a rapid method for producing and purifying pure BSA glycated with ribose, addressing a critical gap in the field. Functional studies, conducted using Native PAGE, demonstrated the capability of purified proteins to bind to each other.

Galectin-3 protects distal convoluted tubules in rhabdomyolysis-induced kidney injury

Advanced glycation endproducts (AGEs) contribute to cellular damage of various pathologies, including kidney diseases. Acute kidney injury (AKI) represents a syndrome seldom characterized by a single, distinct pathophysiological cause. Rhabdomyolysis-induced acute kidney injury (RIAKI) constitutes roughly 15% of AKI cases, yet its underlying pathophysiology remains poorly understood. Using a murine model of RIAKI induced by muscular glycerol injection, we observed elevated levels of AGEs and the AGE receptor galectin-3 (LGALS3) in the kidney. Immunofluorescence localized LGALS3 to distal nephron segments. According to transcriptomic profiling via next-generation sequencing, RIAKI led to profound changes in kidney metabolism, oxidative stress, and inflammation. Cellular stress was evident in both proximal and distal tubules, as shown by kidney injury markers KIM-1 and NGAL. However, only proximal tubules exhibited overt damage and apoptosis, as detected by routine morphology, active Caspase-3, and TUNEL assay, respectively. In vitro, distal convoluted tubule (DCT) cells challenged with AGEs underwent apoptosis, which was markedly enhanced by Lgals3 siRNA treatment. Thus, in RIAKI, the upregulation of LGALS3 may protect the distal nephron from AGE-mediated damage, while proximal tubules lacking LGALS3 stay at risk. Thus, stimulating LGALS3 in the proximal nephron, if achievable, may attenuate RIAKI.

Treatment of Acute and Long-COVID, Diabetes, Myocardial Infarction, and Alzheimer's Disease: The Potential Role of a Novel Nano-Compound-The Transdermal Glutathione-Cyclodextrin Complex

Oxidative stress (OS) occurs from excessive reactive oxygen species or a deficiency of antioxidants-primarily endogenous glutathione (GSH). There are many illnesses, from acute and post-COVID-19, diabetes, myocardial infarction to Alzheimer's disease, that are associated with OS. These dissimilar illnesses are, in order, viral infections, metabolic disorders, ischemic events, and neurodegenerative disorders. Evidence is presented that in many illnesses, (1) OS is an early initiator and significant promotor of their progressive pathophysiologic processes, (2) early reduction of OS may prevent later serious and irreversible complications, (3) GSH deficiency is associated with OS, (4) GSH can likely reduce OS and restore adaptive physiology, (5) effective administration of GSH can be accomplished with a novel nano-product, the GSH/cyclodextrin (GC) complex. OS is an overlooked pathological process of many illnesses. Significantly, with the GSH/cyclodextrin (GC) complex, therapeutic administration of GSH is now available to reduce OS. Finally, rigorous prospective studies are needed to confirm the efficacy of this therapeutic approach.

Advanced Glycation End-Products Acting as Immunomodulators for Chronic Inflammation, Inflammaging and Carcinogenesis in Patients with Diabetes and Immune-Related Diseases

Increased production of advanced glycation end products (AGEs) among reducing sugars (glucose, fructose, galactose, or ribose) and amino acids/proteins via non-enzymatic Maillard reaction can be found in lifestyle-related disease (LSRD), metabolic syndrome (MetS), and obesity and immune-related diseases. Increased serum levels of AGEs may induce aging, diabetic complications, cardiovascular diseases (CVD), neurodegenerative diseases (NDD), cancer, and inflamm-aging (inflammation with immunosenescence). The Maillard reaction can also occur among reducing sugars and lipoproteins or DNAs to alter their structure and induce immunogenicity/genotoxicity for carcinogenesis. AGEs, as danger-associated molecular pattern molecules (DAMPs), operate via binding to receptor for AGE (RAGE) or other scavenger receptors on cell surface to activate PI3K-Akt-, P38-MAPK-, ERK1/2-JNK-, and MyD88-induced NF-κB signaling pathways to mediate various pathological effects. Recently, the concept of "inflamm-aging" became more defined, and we have unveiled some interesting findings in relation to it. The purpose of the present review is to dissect the potential molecular basis of inflamm-aging in patients with diabetes and immune-mediated diseases caused by different AGEs.

Insulin resistance as the molecular link between diabetes and Alzheimer's disease

Diabetes mellitus (DM) and Alzheimer's disease (AD) are two major health concerns that have seen a rising prevalence worldwide. Recent studies have indicated a possible link between DM and an increased risk of developing AD. Insulin, while primarily known for its role in regulating blood sugar, also plays a vital role in protecting brain functions. Insulin resistance (IR), especially prevalent in type 2 diabetes, is believed to play a significant role in AD's development. When insulin signalling becomes dysfunctional, it can negatively affect various brain functions, making individuals more susceptible to AD's defining features, such as the buildup of beta-amyloid plaques and tau protein tangles. Emerging research suggests that addressing insulin-related issues might help reduce or even reverse the brain changes linked to AD. This review aims to explore the rela-tionship between DM and AD, with a focus on the role of IR. It also explores the molecular mechanisms by which IR might lead to brain changes and assesses current treatments that target IR. Understanding IR's role in the connection between DM and AD offers new possibilities for treatments and highlights the importance of continued research in this interdisciplinary field.

Elucidation of inhibitory effects of bioactive anthraquinones towards formation of DNA advanced glycation end products (DNA-AGEs)

DNA is essential in biological processes as it directs transcription and translation assisting in RNA and protein synthesis. Extended periods of elevated blood glucose levels cause non-enzymatic DNA glycation, which results in the formation of DNA-AGEs and the production of free radicals, causing structural perturbation of DNA. In this work, we have investigated the glycation of calf thymus (ct-DNA) DNA and examined its inhibition by two anthraquinone derivatives, purpurin and aloin. Ribose sugar served as the glycating agent inducing non-enzymatic glycation of DNA and subsequent DNA-AGEs formation. UV-vis and fluorescence spectroscopic methods were utilized to characterize DNA-AGE formation in vitro. Circular dichroism (CD) spectroscopy was used to observe the structural disruption of DNA caused by glycation. The changes in AGEs fluorescence intensity and melting temperature (Tm) were measured to assess the inhibition of glycation process by aloin and purpurin. These derivatives demonstrated inhibitory effects via binding to glycating sites of ct-DNA or by scavenging free radicals generated during glycation. The current study elucidates the inhibitory actions of aloin and purpurin on DNA glycation, suggesting their possible applications in mitigating the adverse consequences linked to increased ribose concentrations.

N6-methyladenosine methylation regulator RBM15 promotes the progression of diabetic nephropathy by regulating cell proliferation, inflammation, oxidative stress, and pyroptosis through activating the AGE-RAGE pathway

BACKGROUND

Diabetic nephropathy (DN) is a major cause of end-stage renal disease throughout the world, and m6A modification plays a critical role in the progression of DN. We aimed to find m6A-related genes and their regulatory mechanisms in DN.

METHODS

The expression levels of four important m6A-related genes (METTL16, RBM15, IGF2BP1, and ALKBH5) were detected by quantitative real-time PCR (RT-qPCR). RBM15 was chosen and its function was explored. The downstream pathway of RBM15 was screened by transcriptome sequencing. The levels of AGE, inflammation, and oxidative stress were determined with enzyme-linked immunosorbent assay, and the expression of AGE-RAGE pathway-related proteins were detected by Western blot (WB). Cell proliferation was assessed by Cell counting Kit-8 (CCK-8). The levels of pyroptosis-related proteins were evaluated by RT-qPCR or WB.

RESULTS

METTL16 and RBM15 were up regulated in the mouse model of DN, in which RBM15 was more significant. Silencing RBM15 recovered cell proliferation, reduced the levels of inflammation factors, and inhibited cell pyroptosis in high glucose-induced HK-2 cells. Transcriptome sequencing suggested that the AGE-RAGE pathway might be downstream of RBM15. RBM15 knockdown reduced AGE level and the expression of AGE-RAGE pathway-related proteins. After silencing RBM15, we found that activating the AGE-RAGE pathway inhibited cell proliferation, increased the levels of inflammation factors, promoted oxidative stress, and induced cell pyroptosis in HK-2 cell model of DN.

CONCLUSION

The m6A-related gene RBM15 inhibited cell proliferation, promoted inflammation, oxidative stress, and cell pyroptosis, thereby facilitating the progression of DN through the activation of the AGE-RAGE pathway.

Dietary Advanced Glycation End Products: Their Role in the Insulin Resistance of Aging

Insulin resistance (IR) is commonly observed during aging and is at the root of many of the chronic nontransmissible diseases experienced as people grow older. Many factors may play a role in causing IR, but diet is undoubtedly an important one. Whether it is total caloric intake or specific components of the diet, the factors responsible remain to be confirmed. Of the many dietary influences that may play a role in aging-related decreased insulin sensitivity, advanced glycation end products (AGEs) appear particularly important. Herein, we have reviewed in detail in vitro, animal, and human evidence linking dietary AGEs contributing to the bodily burden of AGEs with the development of IR. We conclude that numerous small clinical trials assessing the effect of dietary AGE intake in combination with strong evidence in many animal studies strongly suggest that reducing dietary AGE intake is associated with improved IR in a variety of disease conditions. Reducing AGE content of common foods by simple changes in culinary techniques is a feasible, safe, and easily applicable intervention in both health and disease. Large-scale clinical trials are still needed to provide broader evidence for the deleterious role of dietary AGEs in chronic disease.

A Role for Advanced Glycation End Products in Molecular Ageing

Ageing is a composite process that involves numerous changes at the cellular, tissue, organ and whole-body levels. These changes result in decreased functioning of the organism and the development of certain conditions, which ultimately lead to an increased risk of death. Advanced glycation end products (AGEs) are a family of compounds with a diverse chemical nature. They are the products of non-enzymatic reactions between reducing sugars and proteins, lipids or nucleic acids and are synthesised in high amounts in both physiological and pathological conditions. Accumulation of these molecules increases the level of damage to tissue/organs structures (immune elements, connective tissue, brain, pancreatic beta cells, nephrons, and muscles), which consequently triggers the development of age-related diseases, such as diabetes mellitus, neurodegeneration, and cardiovascular and kidney disorders. Irrespective of the role of AGEs in the initiation or progression of chronic disorders, a reduction in their levels would certainly provide health benefits. In this review, we provide an overview of the role of AGEs in these areas. Moreover, we provide examples of lifestyle interventions, such as caloric restriction or physical activities, that may modulate AGE formation and accumulation and help to promote healthy ageing.

Social Isolation Activates Dormant Mammary Tumors, and Modifies Inflammatory and Mitochondrial Metabolic Pathways in the Rat Mammary Gland

Although multifactorial in origin, one of the most impactful consequences of social isolation is an increase in breast cancer mortality. How this happens is unknown, but many studies have shown that social isolation increases circulating inflammatory cytokines and impairs mitochondrial metabolism. Using a preclinical Sprague Dawley rat model of estrogen receptor-positive breast cancer, we investigated whether social isolation impairs the response to tamoxifen therapy and increases the risk of tumors emerging from dormancy, and thus their recurrence. We also studied which signaling pathways in the mammary glands may be affected by social isolation in tamoxifen treated rats, and whether an anti-inflammatory herbal mixture blocks the effects of social isolation. Social isolation increased the risk of dormant mammary tumor recurrence after tamoxifen therapy. The elevated recurrence risk was associated with changes in multiple signaling pathways including an upregulation of IL6/JAK/STAT3 signaling in the mammary glands and tumors and suppression of the mitochondrial oxidative phosphorylation (OXPHOS) pathway. In addition, social isolation increased the expression of receptor for advanced glycation end-products (RAGE), consistent with impaired insulin sensitivity and weight gain linked to social isolation. In socially isolated animals, the herbal product inhibited IL6/JAK/STAT3 signaling, upregulated OXPHOS signaling, suppressed the expression of RAGE ligands S100a8 and S100a9, and prevented the increase in recurrence of dormant mammary tumors. Increased breast cancer mortality among socially isolated survivors may be most effectively prevented by focusing on the period following the completion of hormone therapy using interventions that simultaneously target several different pathways including inflammatory and mitochondrial metabolism pathways.

Advanced Glycation End-Products and Their Effects on Gut Health

Dietary advanced glycation end-products (AGEs) are a heterogeneous group of compounds formed when reducing sugars are heated with proteins, amino acids, or lipids at high temperatures for a prolonged period. The presence and accumulation of AGEs in numerous cell types and tissues are known to be prevalent in the pathology of many diseases. Modern diets, which contain a high proportion of processed foods and therefore a high level of AGE, cause deleterious effects leading to a multitude of unregulated intracellular and extracellular signalling and inflammatory pathways. Currently, many studies focus on investigating the chemical and structural aspects of AGEs and how they affect the metabolism and the cardiovascular and renal systems. Studies have also shown that AGEs affect the digestive system. However, there is no complete picture of the implication of AGEs in this area. The gastrointestinal tract is not only the first and principal site for the digestion and absorption of dietary AGEs but also one of the most susceptible organs to AGEs, which may exert many local and systemic effects. In this review, we summarise the current evidence of the association between a high-AGE diet and poor health outcomes, with a special focus on the relationship between dietary AGEs and alterations in the gastrointestinal structure, modifications in enteric neurons, and microbiota reshaping.

Modifiable contributing factors to COVID-19: A comprehensive review

The devastating complications of coronavirus disease 2019 (COVID-19) result from an individual's dysfunctional immune response following the initial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Multiple toxic stressors and behaviors contribute to underlying immune system dysfunction. SARS-CoV-2 exploits the dysfunctional immune system to trigger a chain of events ultimately leading to COVID-19. The current study identifies eighty immune system dysfunction-enabling toxic stressors and behaviors (hereafter called modifiable contributing factors (CFs)) that also link directly to COVID-19. Each CF is assigned to one of the five categories in the CF taxonomy shown in Section 3.3.: Lifestyle (e.g., diet, substance abuse); Iatrogenic (e.g., drugs, surgery); Biotoxins (e.g., micro-organisms, mycotoxins); Occupational/Environmental (e.g., heavy metals, pesticides); Psychosocial/Socioeconomic (e.g., chronic stress, lower education). The current study shows how each modifiable factor contributes to decreased immune system capability, increased inflammation and coagulation, and increased neural damage and neurodegeneration. It is unclear how real progress can be made in combatting COVID-19 and other similar diseases caused by viral variants without addressing and eliminating these modifiable CFs.

The Bitter Side of Sugar Consumption: A Mitochondrial Perspective on Diabetes Development

Type 2 diabetes (T2D) has increased worldwide at an alarming rate. Metabolic syndrome (MetS) is a major risk factor for T2D development. One of the main reasons for the abrupt rise in MetS incidence, besides a sedentary lifestyle, is the westernized diet consumption, with high content of industrialized foods, rich in added dietary sugars (DS), mainly sucrose and fructose. It has been suggested that a higher intake of DS could impair metabolic function, inducing MetS, and predisposing to T2D. However, it remains poorly explored how excessive DS intake modulates mitochondrial function, a key player in metabolism. This review explores the relationship between increased consumption of DS and mitochondrial dysfunction associated with T2D development, pointing to a contribution of the diet-induced accumulation of advanced glycation end-products (AGEs), with brief insights on the impact of maternal high-sugar diet and AGEs consumption during gestation on offspring increased risk of developing T2D later in life, contributing to perpetuate T2D propagation.

Arginine Reduces Glycation in γ2 Subunit of AMPK and Pathologies in Alzheimer's Disease Model Mice

The metabolism disorders are a common convergence of Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM). The characteristics of AD are senile plaques and neurofibrillary tangles (NFTs) composed by deposits of amyloid-β (Aβ) and phosphorylated tau, respectively. Advanced glycation end-products (AGEs) are a stable modification of proteins by non-enzymatic reactions, which could result in the protein dysfunction. AGEs are associated with some disease developments, such as diabetes mellitus and AD, but the effects of the glycated γ2 subunit of AMPK on its activity and the roles in AD onset are unknown.

METHODS

We studied the effect of glycated γ2 subunit of AMPK on its activity in N2a cells. In 3 × Tg mice, we administrated L-arginine once every two days for 45 days and evaluated the glycation level of γ2 subunit and function of AMPK and alternation of pathologies.

RESULTS

The glycation level of γ2 subunit was significantly elevated in 3 × Tg mice as compared with control mice, meanwhile, the level of pT172-AMPK was obviously lower in 3 × Tg mice than that in control mice. Moreover, we found that arginine protects the γ2 subunit of AMPK from glycation, preserves AMPK function, and improves pathologies and cognitive deficits in 3 × Tg mice.

CONCLUSIONS

Arginine treatment decreases glycated γ2 subunit of AMPK and increases p-AMPK levels in 3 × Tg mice, suggesting that reduced glycation of the γ2 subunit could ameliorate AMPK function and become a new target for AD therapy in the future.

Accumulation of Advanced Glycation End-Products in the Body and Dietary Habits

The formation of advanced glycation end-products (AGE) in tissues is a physiological process; however, excessive production and storage are pathological and lead to inflammation. A sedentary lifestyle, hypercaloric and high-fructose diet and increased intake of processed food elements contribute to excessive production of compounds, which are created in the non-enzymatic multi-stage glycation process. The AGE’s sources can be endogenous and exogenous, mainly due to processing food at high temperatures and low moisture, including grilling, roasting, and frying. Accumulation of AGE increases oxidative stress and initiates various disorders, leading to the progression of atherosclerosis, cardiovascular disease, diabetes and their complications. Inborn defensive mechanisms, recovery systems, and exogenous antioxidants (including polyphenols) protect from excessive AGE accumulation. Additionally, numerous products have anti-glycation properties, occurring mainly in fruits, vegetables, herbs, and spices. It confirms the role of diet in the prevention of civilization diseases.

Oxidative Stress in Type 2 Diabetes: The Case for Future Pediatric Redoxomics Studies

Considerable evidence supports the role of oxidative stress in adult type 2 diabetes (T2D). Due to increasing rates of pediatric obesity, lack of physical activity, and consumption of excess food calories, it is projected that the number of children living with insulin resistance, prediabetes, and T2D will markedly increase with enormous worldwide economic costs. Understanding the factors contributing to oxidative stress and T2D risk may help develop optimal early intervention strategies. Evidence suggests that oxidative stress, triggered by excess dietary fat consumption, causes excess mitochondrial hydrogen peroxide emission in skeletal muscle, alters redox status, and promotes insulin resistance leading to T2D. The pathophysiological events arising from excess calorie-induced mitochondrial reactive oxygen species production are complex and not yet investigated in children. Systems medicine is an integrative approach leveraging conventional medical information and environmental factors with data obtained from “omics” technologies such as genomics, proteomics, and metabolomics. In adults with T2D, systems medicine shows promise in risk assessment and predicting drug response. Redoxomics is a branch of systems medicine focusing on “omics” data related to redox status. Systems medicine with a complementary emphasis on redoxomics can potentially optimize future healthcare strategies for adults and children with T2D.

Advanced Glycation End Products: key player of the pathogenesis of atherosclerosis

Atherosclerosis is the most common type of cardiovascular disease, and it causes intima thickening, plaque development, and ultimate blockage of the artery lumen. Advanced glycation end products (AGEs) are thought to have a role in the development and progression of atherosclerosis. there is developing an enthusiasm for AGEs as a potential remedial target. AGES mainly induce arterial damage and exacerbate the development of atherosclerotic plaques by triggering cell receptor-dependent signalling. The interplay of AGEs with RAGE, a transmembrane signalling receptor present across all cells important to atherosclerosis, changes cell activity, boosts expression of genes, and increases the outflow of inflammatory compounds, resulting in arterial wall injury and plaque formation. Here in this review, function of AGEs in the genesis, progression, and instability of atherosclerosis is discussed. In endothelial and smooth muscle cells, as well as platelets, the interaction of AGEs with their transmembrane cell receptor, RAGE, triggers intracellular signalling, resulting in endothelial damage, vascular smooth muscle cell function modification, and changed platelet activity.

Rosmarinic acid inhibits DNA glycation and modulates the expression of Akt1 and Akt3 partially in the hippocampus of diabetic rats

Non-enzymatic glycation of DNA and the associated effects are among pathogenic factors in diabetes mellitus. Natural polyphenols have anti-diabetic activity. Herein, the protective role of one of the phytochemicals, rosmarinic acid (RA), was evaluated in glycation (with fructose) of human DNA and expression of Akt genes in the hippocampus of diabetic rats. In-vitro studies using fluorescence, agarose gel electrophoresis, fluorescence microscopy, and thermal denaturation analyses revealed that glycation causes DNA damage and that RA inhibits it. In-vivo studies were performed by induction of diabetes in rats using streptozotocin. The diabetic rats were given RA daily through gavage feeding. The expression of Akt genes (inhibitors of apoptosis) in the hippocampus was evaluated using RT-qPCR. In diabetic rats, Akt1 and Akt3 were significantly down-regulated compared to the control group. Treating the diabetic rats with RA returned the expression of Akt1 and Akt3 relatively to the normal condition. Past studies have shown that diabetes induces apoptosis in the hippocampal neurons. Given that glycation changes the genes expression and causes cell death, apoptosis of the hippocampal neurons can be due to the glycation of DNA. The results also suggest that RA has reliable potency against the gross modification of DNA under hyperglycemic conditions.

Lactose Glycation of the Maillard-Type Impairs the Benefits of Caseinate Digest to the Weaned Rats for Intestinal Morphology and Serum Biochemistry

The Maillard reaction between the lactose and milk proteins unavoidably occurs during the thermal treatment of milk. Although the impact of this reaction on protein nutrition and safety has been well-studied, whether a lactose glycation of milk proteins of the Maillard-type might affect the rats in their growth and intestinal morphology needs an investigation. In this study, caseinate and lactose-glycated caseinate were digested using pepsin and trypsin. Afterward, the resultant caseinate digest and glycated caseinate digest (lactose content of 13.5 g/kg of protein) at 100, 200, and 400 mg/kg body weight (BW)/d were assessed for their effects on the female weaned Wistar rats in terms of daily body weight gain, intestinal morphology, digestive and brush-border enzyme activities, as well as serum chemical indices. The results showed that glycated caseinate digest always showed a weaker effect on rat than caseinate digest either at the 0-7 or 0-28 d feeding stage, and more importantly, at the highest dose of 400 mg/kg BW/d, it caused obvious adverse effect on the rats, reflected by lower values of these indices. Compared with caseinate digest, glycated caseinate digest in the rats caused 0.9-15.4% and 10.6-49.7% decreases in average daily gain of BW and small intestinal length, 1.1-21.5% and 2.3-33.3% decreases in villus height and the ratio of villus height to crypt depth of the small intestine, or 0.3-57.6% and 0.2-55.7% decreases in digestive and critical brush-border enzyme activities, respectively. In addition, when the rats were fed with glycated caseinate digest, some serum indices related to oxidative stress status were enhanced dose-dependently. Lactose glycation of the Maillard-type is thus considered as a negative event of the Maillard reaction on milk proteins because this reaction might impair protein benefits to the body.

The effect of acrylamide on sperm oxidative stress, total antioxidant levels, tyrosine phosphorylation, and carboxymethyl-lysine expression: A laboratory study

Background

Acrylamide (AA) is a reactive molecule produced during food processing at temperatures above 120∘C.

Objective

To evaluate the impact of different concentrations of AA on human sperm parameters, oxidative stress and total antioxidant capacity (TAC).

Materials and Methods

In this laboratory study, semen samples were obtained from healthy donors referred to the Taleghani Hospital, Tehran, Iran between June and July 2019. Samples were divided into four groups (n = 10/each): one control and three treatment groups (0.5, 1, and 2 mM of AA). After 2 hr of exposure to AA, the superoxide dismutase and malondialdehyde levels were measured based on colorimetric methods. The TAC was determined by the ferric-reducing antioxidant power assay. Flow cytometry was performed to measure the intracellular reactive oxygen species generation. Also, immunohistochemistry was done to determine the effect of AA on tyrosine phosphorylation and carboxymethyl-lysine expression.

Results

Results of the study demonstrated that the motility and viability of spermatozoa were significantly decreased after AA exposure (p < 0.001). This decrease was also seen in the TAC and superoxide dismutase activity as well as in the phosphotyrosine percentage compared with the control (p < 0.01). However, the carboxymethyl-lysine and prooxidant activity including reactive oxygen species generation and lipid peroxidation level increased (p < 0.001).

Conclusion

Overall, the results confirmed the detrimental effect of AA on human spermatozoa which may be due to oxidative stress and decreased total antioxidant levels. AA may reduce fertility by reducing sperm capacitation and motility.

Hemoglobin A1c-levels and subsequent risk of depression in individuals with and without diabetes

BACKGROUND

It has been suggested that long-term glycemic load as reflected in plasma levels of Glycosylated Hemoglobin, Type A1C (HbA1c) is associated with higher risk of depression, however results have been conflicting. We examined the potential association between HbA1c and risk of depression in a large population-based cohort without baseline diabetes (the Glostrup cohort) defined by either self-reported diabetes, registry diagnosis of diabetes or use of antidiabetic medication at baseline and in a national diabetes cohort (the Danish Adult Diabetes Database).

METHODS

A total of 16,124 middle-aged individuals from the Glostrup cohort and 93,544 patients registered in the Danish Adult Diabetes Database were followed from the first registered HbA1c measurement (1999-2014) for subsequent diagnosis of depression or use of antidepressant medication in nation-wide Danish registers. The association was analyzed using a Cox proportional hazards regression model with HbA1c on both a continuous scale using restricted cubic splines and categorized based on the groups found in the spline model. We adjusted for relevant sociodemographic and clinical variables including previous depression and tested for interaction of both gender, insulin use and diabetes type.

RESULTS

During follow-up, 2694 (17%) in the Glostrup cohort and 29,234 (31%) in the diabetes cohort developed depression. In the Glostrup cohort, we found an indication of a positive linear association between HbA1c and depression in women, while no clear association was found in men. In patients with diabetes, we found a U-shaped association between HbA1c and depression in both men and women with the lowest risk estimates for HbA1c levels of 58 mmol/mol (7.5%) in men and of 60 mmol/mol (7.6%) in women. When HbA1c was categorized, men with the highest HbA1c-levels had significantly elevated risk of depression (HR_HbA1c>9.4 1.16 (95%CI 1.10-1.23)) after multifactorial adjustment compared to the reference group with HbA1c of 42.1-56.2 mmol/mol (6.0-7.3%). Women in the lowest and highest category of HbA1c had significantly higher risk of depression HR_HbA1c<6.0 1.15 (95% CI 1.09-1.22) and HR_HbA1c>9.3 1.10 (95% CI 1.04-1.16), respectively, compared to the reference group with HbA1c 42.1-55.0 mmol/mol (7.2-9.3%). There was a significant interaction with gender, but no interaction for insulin use or diabetes type.

CONCLUSIONS

In a population without baseline diabetes, higher HbA1c levels seemed associated with higher depression risk in women, whereas a U-shaped association was found in patients with known diabetes.

Phloroglucinol prevents albumin glycation as well as diminishes ROS production, glycooxidative damage, nitrosative stress and inflammation in hepatocytes treated with high glucose

The treatment of diabetes mellitus aftermaths became one of medicine's most significant therapeutical and financial issues in the XXI century. Most of which are related to protein glycation and oxidative stress caused by long lasting periods of hyperglycemia. Thus, even within a venerable one, searching for new drugs, displaying anti-glycation and anti-oxidative properties seem useful as an additive therapy of diabetes. In this paper, we assessed the anti-glycating properties of phloroglucinol, a drug discovered in the XIX century and still used in many countries for its antispasmodic action. Herewith, we present its effect on protein glycation, glycoxidation, and oxidative damage in an albumin glycation/oxidation model and HepG2 cells treated with high glucose concentrations. The phloroglucinol showed the strongest and the widest protective effect within all analyzed antiglycating (aminoguanidine, pioglitazone) and anti-oxidative (vitamin C, GSH) agents. To the very best of our knowledge, this is the first study showing the properties of phloroglucinol in vitro what once is proven in other models might deepen its clinical applications.

Role of Long Non-Coding RNAs and the Molecular Mechanisms Involved in Insulin Resistance

Long non-coding RNAs (lncRNAs) are single-stranded RNA biomolecules with a length of >200 nt, and they are currently considered to be master regulators of many pathological processes. Recent publications have shown that lncRNAs play important roles in the pathogenesis and progression of insulin resistance (IR) and glucose homeostasis by regulating inflammatory and lipogenic processes. lncRNAs regulate gene expression by binding to other non-coding RNAs, mRNAs, proteins, and DNA. In recent years, several mechanisms have been reported to explain the key roles of lncRNAs in the development of IR, including metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), imprinted maternal-ly expressed transcript (H19), maternally expressed gene 3 (MEG3), myocardial infarction-associated transcript (MIAT), and steroid receptor RNA activator (SRA), HOX transcript antisense RNA (HOTAIR), and downregulated Expression-Related Hexose/Glucose Transport Enhancer (DREH). LncRNAs participate in the regulation of lipid and carbohydrate metabolism, the inflammatory process, and oxidative stress through different pathways, such as cyclic adenosine monophosphate/protein kinase A (cAMP/PKA), phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT), polypyrimidine tract-binding protein 1/element-binding transcription factor 1c (PTBP1/SREBP-1c), AKT/nitric oxide synthase (eNOS), AKT/forkhead box O1 (FoxO1), and tumor necrosis factor-alpha (TNF-α)/c-Jun-N-terminal kinases (JNK). On the other hand, the mechanisms linked to the molecular, cellular, and biochemical actions of lncRNAs vary according to the tissue, biological species, and the severity of IR. Therefore, it is essential to elucidate the role of lncRNAs in the insulin signaling pathway and glucose and lipid metabolism. This review analyzes the function and molecular mechanisms of lncRNAs involved in the development of IR.

Advanced glycation end products and their receptors in serum of patients with type 2 diabetes

Glycation is a non-enzymatic process involving the reaction of reducing sugars or reactive oxoaldehyde with proteins, lipids or nucleic acids, which results in the formation of advanced glycation end products (AGEs). The presented work discusses the glycation process in people with advanced stage of type 1 or type 2 diabetes. The concentration of different AGEs and their receptors for 58 serum samples was determined by ELISA and by spectrofluorimetric methods. In addition to fluorescent low molecular weight and protein-bound AGEs, we have also marked a new class of AGEs: melibiose-derived glycation product (MAGE). Our attention was also focused on the two groups of AGEs receptors: scavenger receptors (SR-A and SR-B) and RAGE. The correlation between the SR-AI scavenging receptors concentration and the fluorescence of AGEs as well as diabetes biological markers: GFR, creatinine contentration and HbA1c was demonstrated. A relationship between the concentration of AGEs and their receptors was also found in serum sample of patients treated with the metformin and aspirin. Furthermore, the concentration of SR-AI scavenger and the fluorescence of total AGEs was significantly lower in treated patients than in non treated patients. AGEs have also been found to contribute to the development of cardiovascular disease, atherosclerosis and diabetic complications, what could be deduced from the correlation of AGEs level and HDL cholesterol or uric acid level. Thus, it was confirmed that AGEs are involved in the pathomechanism of diabetes and other degenerative diseases. Nowadays, it is believed that AGEs due to the long time remaining in the body may be an important diagnostic marker. Their determination may allow monitoring the progression of the disease and the effectiveness of the therapy.

The Impact of Low Advanced Glycation End Products Diet on Metabolic Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Several randomized clinical trials have investigated the effect of dietary advanced glycation end products (AGEs) on metabolic syndrome risk factors in adults. However, the results of these studies were conflicting. Therefore, our aim was to assess the effect of dietary AGEs on metabolic syndrome risk factors. We searched the PubMed-MEDLINE, Scopus, Cochrane Databases, Google Scholar, Web of Science, and Embase databases for papers published up to October 2019 that investigated the effect of dietary AGEs on metabolic syndrome risk factors. From the eligible trials, 13 articles were selected for inclusion in this systematic review and meta-analysis. The meta-analysis was performed using a random-effects model. Heterogeneity was determined by I2 statistics and Cochrane Q test. Pooled results from the random-effects model showed a significant reduction for insulin resistance [weighted mean difference (WMD): -1.204; 95% CI: -2.057, -0.358; P = 0.006], fasting insulin (WMD: -5.472 μU/mL; 95% CI: -9.718, -1.234 μU/mL; P = 0.011), total cholesterol (WMD: -5.486 mg/dL; 95% CI: -10.222, -0.747 mg/dL; P = 0.023), and LDL (WMD: -6.263 mg/dL; 95% CI: -11.659, -0.866 mg/dL; P = 0.023) in the low-AGEs groups compared with the high-AGEs groups. There were no changes in the other components of the metabolic syndrome. The results of this review suggest that a diet with a low AGEs content has beneficial effects on insulin resistance, fasting insulin, total cholesterol, and LDL. Moreover, following a diet low in AGEs may be a helpful strategy to decrease the burden of metabolic syndrome risk factors in adults and particularly in patients with diabetes.

Pathology, Risk Factors, and Oxidative Damage Related to Type 2 Diabetes-Mediated Alzheimer's Disease and the Rescuing Effects of the Potent Antioxidant Anthocyanin

The pathology and neurodegeneration in type 2 diabetes- (T2D-) mediated Alzheimer's disease (AD) have been reported in several studies. Despite the lack of information regarding the basic underlying mechanisms involved in the development of T2D-mediated AD, some common features of the two conditions have been reported, such as brain atrophy, reduced cerebral glucose metabolism, and insulin resistance. T2D phenotypes such as glucose dyshomeostasis, insulin resistance, impaired insulin signaling, and systemic inflammatory cytokines have been shown to be involved in the progression of AD pathology by increasing amyloid-beta accumulation, tau hyperphosphorylation, and overall neuroinflammation. Similarly, oxidative stress, mitochondrial dysfunction, and the generation of advanced glycation end products (AGEs) and their receptor (RAGE) as a result of chronic hyperglycemia may serve as critical links between diabetes and AD. The natural dietary polyflavonoid anthocyanin enhances insulin sensitivity, attenuates insulin resistance at the level of the target tissues, inhibits free fatty acid oxidation, and abrogates the release of peripheral inflammatory cytokines in obese (prediabetic) individuals, which are responsible for insulin resistance, systemic hyperglycemia, systemic inflammation, brain metabolism dyshomeostasis, amyloid-beta accumulation, and neuroinflammatory responses. In this review, we have shown that obesity may induce T2D-mediated AD and assessed the recent therapeutic advances, especially the use of anthocyanin, against T2D-mediated AD pathology. Taken together, the findings of current studies may help elucidate a new approach for the prevention and treatment of T2D-mediated AD by using the polyflavonoid anthocyanin.

The Development of Maillard Reaction, and Advanced Glycation End Product (AGE)-Receptor for AGE (RAGE) Signaling Inhibitors as Novel Therapeutic Strategies for Patients with AGE-Related Diseases

Advanced glycation end products (AGEs) are generated by nonenzymatic modifications of macromolecules (proteins, lipids, and nucleic acids) by saccharides (glucose, fructose, and pentose) via Maillard reaction. The formed AGE molecules can be catabolized and cleared by glyoxalase I and II in renal proximal tubular cells. AGE-related diseases include physiological aging, neurodegenerative/neuroinflammatory diseases, diabetes mellitus (DM) and its complications, autoimmune/rheumatic inflammatory diseases, bone-degenerative diseases, and chronic renal diseases. AGEs, by binding to receptors for AGE (RAGEs), alter innate and adaptive immune responses to induce inflammation and immunosuppression via the generation of proinflammatory cytokines, reactive oxygen species (ROS), and reactive nitrogen intermediates (RNI). These pathological molecules cause vascular endothelial/smooth muscular/connective tissue-cell and renal mesangial/endothelial/podocytic-cell damage in AGE-related diseases. In the present review, we first focus on the cellular and molecular bases of AGE–RAGE axis signaling pathways in AGE-related diseases. Then, we discuss in detail the modes of action of newly discovered novel biomolecules and phytochemical compounds, such as Maillard reaction and AGE–RAGE signaling inhibitors. These molecules are expected to become the new therapeutic strategies for patients with AGE-related diseases in addition to the traditional hypoglycemic and anti-hypertensive agents. We particularly emphasize the importance of “metabolic memory”, the “French paradox”, and the pharmacokinetics and therapeutic dosing of the effective natural compounds associated with pharmacogenetics in the treatment of AGE-related diseases. Lastly, we propose prospective investigations for solving the enigmas in AGE-mediated pathological effects.

Dietary Advanced Glycation End Products (AGEs) could alter ovarian function in mice

Nutrition is an important source of exogenous AGEs and thermally processed foods present in western-style diets contain a large amount of these pro-inflammatory AGEs. Additionally, the intake of dietary AGEs could upregulate ovarian gene expression of inflammatory macrophage markers. The objective of this study was to investigate the effect of diet rich in AGEs on estrous cyclicity and ovarian function in a mouse model. Six-week old C57BL/6 J female mice were randomly subjected to either a diet low in AGEs (L-AGE) or a diet high in AGEs (H-AGE) for a total of 13 weeks. Experiments performed included daily vaginal smears to assess estrous cyclicity, ovarian superovulation with gonadotropins to assess the number of oocytes released, whole ovarian tissue mRNA quantification by RT-PCR to quantify genes involved in folliculogenesis, steroidogenesis, and macrophage markers, and ovarian morphology for follicle count. Outcome measures included estrous cyclicity, number of oocytes following superovulation, expression of genes involved in folliculogenesis, steroidogenesis, and macrophage infiltration as well as the number of primordial, primary, secondary, antral follicles and corpora lutea. Compared to mice on L-AGE diet, mice on H-AGE spent significantly longer time in the diestrus phase, had similar number of oocytes released following ovarian superovulation, and showed significant alterations in genes involved in steroidogenesis (increase in Star mRNA expression levels) and folliculogenesis (increase in Gdf-9 and Fshr mRNA expression levels). Mouse macrophage marker F4/80 mRNA expression was upregulated in mice on H-AGE diet compared to mice on L-AGE diet. Finally, mice on H-AGE diet had significantly fewer corpora lutea in their ovaries. These results indicate that the ingestion of high amounts of dietary AGEs could disrupt folliculogenesis and steroidogenesis that might lead to abnormal estrous cyclicity. Intake of dietary AGEs could also upregulate ovarian gene expression of inflammatory macrophage markers.

Advanced Glycation End Products (AGEs): Biochemistry, Signaling, Analytical Methods, and Epigenetic Effects

The advanced glycation end products (AGEs) are organic molecules formed in any living organisms with a great variety of structural and functional properties. They are considered organic markers of the glycation process. Due to their great heterogeneity, there is no specific test for their operational measurement. In this review, we have updated the most common chromatographic, colorimetric, spectroscopic, mass spectrometric, and serological methods, typically used for the determination of AGEs in biological samples. We have described their signaling and signal transduction mechanisms and cell epigenetic effects. Although mass spectrometric analysis is not widespread in the detection of AGEs at the clinical level, this technique is highly promising for the early diagnosis and therapeutics of diseases caused by AGEs. Protocols are available for high-resolution mass spectrometry of glycated proteins although they are characterized by complex machine management. Simpler procedures are available although much less precise than mass spectrometry. Among them, immunochemical tests are very common since they are able to detect AGEs in a simple and immediate way. In these years, new methodologies have been developed using an in vivo novel and noninvasive spectroscopic methods. These methods are based on the measurement of autofluorescence of AGEs. Another method consists of detecting AGEs in the human skin to detect chronic exposure, without the inconvenience of invasive methods. The aim of this review is to compare the different approaches of measuring AGEs at a clinical perspective due to their strict association with oxidative stress and inflammation.

Cancer prevention programmes in Mexico: are we doing enough?

Cancer has increased in all the countries of the world and Mexico is no exception. The recognised risk factors for the main types of cancer are reviewed and searched through the Mexican government web pages and cancer prevention programmes to tackle the risk factors in the population. The Mexican government, a member of the World Health Organization, shows that the main approach is an early diagnosis rather than prevention, forgetting that an ounce of prevention is better than a pound of cure. Effective public programmes should be promoted to reduce preventable risk factors in the population (smoking, nutrition, obesity, diet, environmental toxicity, sedentary lifestyle) and control the non-preventable factors (genetics) if we really want to control the incidence of different types of cancer.

An in Silico Approach Reveals the Potential Function of Cyanidin-3-o-glucoside of Red Rice in Inhibiting the Advanced Glycation End Products (AGES)-Receptor (RAGE) Signaling Pathway

Introduction:

Advanced glycation end products (AGEs) contribute to the pathogenesis of chronic inflammation, diabetes, micro and macrovascular complications, and neurodegenerative diseases through the binding with RAGE. Natural compounds can act as an alternative in disease therapy related to the AGEs-RAGE interactions. Cyanidin-3-O-glucoside is one of the potential anthocyanins found in red rice. Cyanidin-3-O-glucoside in red rice may interfere with the AGEs-RAGE signaling so that the potential mechanism of their interaction needs to be elucidated.

Aim:

This study aimed to investigate the potency of cyanidin-3-O-glucoside in red rice as an inhibitor of AGE-RAGE signaling pathway through in silico analysis.

Methods:

Our study used the 3D structures of AGEs and Cyanidin-3-O-glucoside compounds from PubChem and Receptor for AGEs (RAGE) from the RCSB Protein Data Bank (PDB) database. The molecular interactions of those compounds and RAGE were established using Hex 8.0 software, then visualized using Discovery Studio 2016 software.

Results:

Argypirimidine, pentosidine, pyrralline, and imidazole bound to the ligand-binding domain of RAGE with the binding energy of -247 kcal/mol, -350.4 kcal/mol, -591.1 kcal/mol, and -100.4 kcal/mol, respectively. The presence of cyanidin-3-O-glucoside in the imidazole-RAGE-cyanidin-3-O-glucoside complex could inhibit the interaction of imidazole-RAGE with a binding energy of -299 kcal/mol, which was lower than of imidazole-RAGE complex. The establishment of AGEs-Cyanidin-3-O-glucoside-RAGE complex showed that cyanidin-3-O-glucoside, which bound first to Argypirimidine and Pyrralline, could bound to RAGE at the same residue as those two AGEs did with the binding energy of -411.8 kcal/mol and -1305 kcal/mol, respectively. Based on the binding site location and energy, cyanidin-3-O-glucoside might have a biological function as an inhibitor of AGEs-RAGE interactions, which was more likely through the establishment of AGEs-cyanidin-3-O-glucoside-RAGE.

Conclusion:

This study suggests that cyanidin-3-O-glucoside in red rice can be a potential AGEs-RAGE inhibitor, leading to the regulation of the pro-inflammatory and oxidative damage in the cellular pathway.

Dietary and Plasma Carboxymethyl Lysine and Tumor Necrosis Factor-α as Mediators of Body Mass Index and Waist Circumference among Women in Indonesia

Dietary and plasma carboxymethyl lysine (dCML, pCML) and plasma tumor necrosis factor-α (pTNF-α) may be associated with obesity in affluent society. However, evidence in women from low-middle income countries with predominantly traditional diets is lacking. We investigated the mediator effects of dCML, pCML and pTNF-α on body mass index (BMI) and waist circumference (WC) among Indonesian women. A cross-sectional study was conducted among 235 non-diabetic, non-anemic and non-smoking women aged 19–50 years from selected mountainous and coastal areas of West Sumatra and West Java. Dietary CML, pCML, pTNF-α were obtained from 2 × 24-h recalls, ultra-performance liquid chromatography-tandem mass spectrometry and enzyme-linked immunosorbent assay, respectively. Between-group differences were analyzed by the Chi-square or Mann-Whitney test and mediator effects by Structural Equation Modeling. The medians and interquartile-ranges of dCML, pCML and pTNF-α were 2.2 (1.7–3.0) mg/day, 22.2 (17.2–28.2) ng/mL and 0.68 (0.52–1.00) IU/mL, respectively, and significantly higher in the WC ≥ 80 cm than in the WC < 80 cm group, but not in BMI ≥ 25 kg/m² compared to BMI < 25 kg/m² group. Plasma CML and pTNF-α were positively and directly related to WC (β = 0.21 [95% CI: 0.09, 0.33] and β = 0.23 [95% CI: 0.11, 0.35], respectively). Dietary CML that correlated with dry-heat processing and cereals as the highest contributions was positively related to WC (β = 0.33 [95% CI: 0.12, 0.83]). Ethnicity, level of education, intake of fat, and intake of energy contributed to dCML, pCML and pTNF-α, and subsequently affected WC, while only ethnicity contributed to BMI through dCML, pCML and pTNF-α (β = 0.07 [95% CI: 0.01, 0.14]). A positive direct effect of dCML on pCML and of pCML and pTNF-α on WC was seen among Indonesian women. Dietary CML seems to have several paths that indirectly influence the increases in WC if compared to BMI. Thus, intake of CML-rich foods should be reduced, or the foods consumed in moderate amounts to avoid the risk of central obesity in this population.

Mitochondrial carnitine palmitoyltransferase 2 is involved in Nε-(carboxymethyl)-lysine-mediated diabetic nephropathy

Diabetic nephropathy (DN) is the most common cause of end-stage renal disease in the world. Advanced glycation end products (AGEs) are thought to be involved in the pathogenesis of DN via multifactorial mechanisms including the generation of oxidative stress and overproduction of various growth factors and cytokines. AGEs are heterogeneous cross-linked sugar-derived proteins, and N^ε-(carboxymethyl)-lysine (CML)-conjugated BSA is a major component of AGEs. However, the proteins involved in DN induction by CML have never been reported. Herein, we investigated specific protein regulators of AGE-mediated DN via proteomic analysis of streptozotocin (STZ)-induced diabetic mice kidneys. We identified 937, 976, and 870 proteins in control, STZ, and STZ + CML-BSA samples, respectively. Bioinformatics analysis identified several CML-mediated proteins potentially involved in kidney damage, activation of fatty acid oxidation (FAO), and mitochondrial dysfunction. Furthermore, we identified the CML-specific differential protein carnitine palmitoyltransferase 2 (CPT2), related to FAO. To confirm the effect of CPT2 and the CML-mediated mechanism, human renal tubular HK-2 cells were treated with CML-BSA and cpt2 siRNA, and examined for FAO-mediated fibrosis and mitochondrial dysfunction. CML-BSA and CPT2 knockdown induced fibrosis-related gene expression and damage to mitochondrial membrane potential. Moreover, CPT2 overexpression recovered CML-induced fibrosis-related gene expression. Based on these results, a decrease in CML-induced CPT2 expression causes mitochondrial FAO damage, leading to renal fibrosis and DN.

Formation of advanced glycation endproducts in foods during cooking process and underlying mechanisms: a comprehensive review of experimental studies

Advanced glycation endproducts (AGE) are a group of complex and heterogeneous molecules, sharing some common characteristics such as covalent cross-link formation among proteins, the effect of transforming the colour of food products into yellow-brown colours and fluorescence formation. AGE are linked to many diseases including diabetes, renal diseases, CVD, liver diseases, neuro-degenerative and eye disorders, female reproductive dysfunction, and even cancer. AGE are formed endogenously but are also provided from exogenous sources including diet and tobacco. Western diet, rich in processed and/or heat-treated foods, fat and sugar, increases the exposure to AGE. The foods that contain high levels of fat and protein are generally rich in terms of AGE, and are also prone to AGE formation during cooking compared with carbohydrate-rich foods such as vegetables, fruits, legumes and whole grains. The present article aimed to review the literature about the effects of different cooking methods and conditions on the AGE content of food and AGE formation mechanisms using a comprehensive approach.

Quality Criteria for Studies on Dietary Glycation Compounds and Human Health

Current reports increasingly associate dietary "advanced glycation end products" ("AGEs") resulting from the Maillard reaction (glycation) between reducing sugars and amino compounds in foods with pathophysiological consequences, such as chronic inflammation, atherosclerosis, and metabolic syndrome. Heated foods are therefore suggested to pose a potential risk for human health. However, studies in this field are very often based on questionable quantitative data and inadequate structural characterization. To improve the situation, the present perspective suggests quality criteria for future studies and the assessment of the currently available literature.

The role of chronic kidney disease-associated dysbiosis in cardiovascular disease

IMPACT STATEMENT

Negative alterations, or dysbiosis, in the intestinal microbial community balance in response to chronic kidney disease is emerging as a substantial and important factor in inducing and exacerbating multiple comorbid conditions. Patients with renal insufficiency experience a substantial increase in cardiovascular risk, and recent evidence is shedding light on the close interaction between microbiome dysbiosis and increased cardiovascular events in this population. Previous association and recent causality studies utilizing experimental animal models have enriched our understanding and confirmed the impact of microbial community imbalance on cardiac health in both the general population and in patients with renal impairment.

Skim milk powder with high content of Maillard reaction products affect weight gain, organ development and intestinal inflammation in early life in rats

BACKGROUND

The intestinal tract is important for development of immune tolerance and disturbances are suggested to trigger autoimmune disorders. The aim of this study was to explore the effect of Maillard products in skim milk powder obtained after long storage, compared to fresh skim milk powder.

METHODS

Young rats were weaned onto a diet based on skim milk powder with high concentration of Maillard products (HM-SM, n = 18) or low (C-SM, n = 18) for one week or four weeks. Weekly body weight and feed consumption were noted. At the end, organ weights, intestinal histology, permeability and inflammatory cytokines were evaluated.

RESULTS

Rats fed with HM-SM had after one week, 15% less weight gain than controls, despite equal feed intake. After one week thymus and spleen were smaller, intestinal mucosa thickness was increased and acute inflammatory cytokines (IL-17, IL-1β, MCP-1) were elevated. After four weeks, cytokines associated with chronic intestinal inflammation (fractalkine, IP-10, leptin, LIX, MIP-2, RANTES and VEGF) were increased in rats fed with HM-SM compared to C-SM.

CONCLUSION

High content of Maillard products in stored milk powder caused an intestinal inflammation. Whether this is relevant for tolerance development and future autoimmune diseases remains to be explored.

Role of advanced glycation end products in mobility and considerations in possible dietary and nutritional intervention strategies

Advanced glycation end products (AGEs), a group of compounds that are formed by non-enzymatic reactions between carbonyl groups of reducing sugars and free amino groups of proteins, lipids or nucleic acids, can be obtained exogenously from diet or formed endogenously within the body. AGEs accumulate intracellularly and extracellularly in all tissues and body fluids and can cross-link with other proteins and thus affect their normal functions. Furthermore, AGEs can interact with specific cell surface receptors and hence alter cell intracellular signaling, gene expression, the production of reactive oxygen species and the activation of several inflammatory pathways. High levels of AGEs in diet as well as in tissues and the circulation are pathogenic to a wide range of diseases. With respect to mobility, AGEs accumulate in bones, joints and skeletal muscles, playing important roles in the development of osteoporosis, osteoarthritis, and sarcopenia with aging. This report covered the related pathological mechanisms and the potential pharmaceutical and dietary intervention strategies in reducing systemic AGEs. More prospective studies are needed to determine whether elevated serum AGEs and/or skin autofluorescence predict a decline in measures of mobility. In addition, human intervention studies are required to investigate the beneficial effects of exogenous AGEs inhibitors on mobility outcomes.

Low total and free triiodothyronine levels are associated with insulin resistance in non-diabetic individuals

This study examined associations of thyroid hormone levels and insulin resistance (IR) in non-diabetic individuals. Using a cross-sectional design, 2007-2008 data from the National Health and Nutrition Examination Survey (NHANES) were analyzed. NHANES participants ≥20 years of age with complete data of interest were included. The homeostatic model assessment (HOMA) was used to quantify IR, and treated as a continuous variable. Self-reported diabetes or a fasting glucose ≥7 mmol/L were used as criteria to exclude diabetic subjects. Race, liver function, obesity, hypertension, dyslipidemia, smoking, physical activity, vigorous recreational activity, 2-hour glucose, hemoglobin A1C (HbA1C), high-density lipoprotein, triglyceride, vitamin D and C-reactive protein were covariates significantly associated with HOMA-IR. A total of 1,560 non-diabetic subjects were included in the analysis. When adjusted for all factors significant in the univariate analysis (race, liver function, obesity, hypertension, dyslipidemia, smoking, physical activity, vigorous recreational activity, 2-hour glucose, HbA1C, high-density lipoprotein, triglyceride, vitamin D, and CRP) low total triiodothyronine (TT3) and low free T3 (FT3) were significantly associated with decreased HOMA-IR (adjusted coefficient = -0.486, 95% confidence interval [CI]: -0.936, -0.036; adjusted coefficient = -1.151, 95% CI: -1.952, -0.350, respectively). Insulin resistance is associated with low thyroid hormone levels in non-diabetic individuals.

Changes in circulating levels of carboxymethyllysine, soluble receptor for advanced glycation end products (sRAGE), and inflammation markers in women during normal pregnancy

Objective: To determine the circulating levels of insulin, Nε-carboxymethyllysine (CML), soluble receptor for advanced glycation end products (sRAGE), and markers of inflammation and oxidative stress (OS) in maternal and umbilical cord blood in a cohort of healthy women with normal pregnancy.Methods: We conducted an observational longitudinal study in a group of women (n = 31; age range 18-39 years) with healthy pregnancy starting at 30 weeks of gestation and finishing at the time of delivery. We collected weight and height in the participants and their neonates and calculated body mass index (BMI). Blood from each patient was collected at 30th week of pregnancy and at delivery when a sample of cord blood was also obtained. Glucose, lipid profile, CML, sRAGE, malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), highly sensitivity C-reactive protein (hsPCR), and insulin were determined. The study was approved by the University of Guanajuato Institutional Ethics Committee.Results: All pregnancies reached term (mean gestational time 38.9 ± 0.83 weeks) and there were no maternal complications. Mean age was 27.6 years. Lipid profile values were higher in the group compared with our values in nonpregnant women. During pregnancy, levels of insulin increased (p < .0006), CML (p < .0001) and sRAGE (p < .01) decreased, levels of MDA did not change, while those of TNF-α and hsPCR tended to increase. In the neonates, we found lower levels of CML (p < .003), hsPCR (p < .004), and insulin (p < .004) and higher levels of sRAGE (p < .013) and TNF-α (p < .022) compared to their mothers at delivery. In the total group, we found association of CML of the mother at baseline with the CML (p < .0006) and MDA (p < .002) in neonates, while maternal sRAGE at the end of pregnancy was associated with CML (p < .004) of their neonates.Conclusions: Our study confirms that normal pregnancy is accompanied by insulin resistance (IR) and significant increase in lipid profile, and demonstrates that circulating levels of CML and sRAGE decreased significantly at the end of pregnancy. The lack of association between the course of insulin levels and those of CML probably results from the predominant role of placental factors in the pathogenesis of IR in pregnancy. sRAGE levels in the neonates are markedly increased compared to their mothers suggesting a placental origin of this compound which may have a protective effect on the fetus since sRAGE restricts Advanced glycation end product (AGE) effects and may exert anti-inflammatory effects.

Interaction of diabetes and smoking on stroke: a population-based cross-sectional survey in China

OBJECTIVES

Diabetes and smoking are known independent risk factors for stroke; however, their interaction concerning stroke is less clear. We aimed to explore such interaction and its influence on stroke in Chinese adults.

DESIGN

Cross-sectional study.

SETTING

Community-based investigation in Xuzhou, China.

PARTICIPANTS

A total of 39 887 Chinese adults who fulfilled the inclusion criteria were included.

METHODS

Participants were selected using a multistage stratified cluster method, and completed self-reported questionnaires on stroke and smoking. Type 2 diabetes mellitus (DM2) was assessed by fasting blood glucose or use of antidiabetic medication. Interaction, relative excess risk owing to interaction (RERI), attributable proportion (AP) and synergy index (S) were evaluated using a logistic regression model.

RESULTS

After adjustment for age, sex, marital status, educational level, occupation, physical activity, body mass index, hypertension, family history of stroke, alcohol use and blood lipids, the relationships between DM2 and stroke, and between smoking and stroke, were still significant: ORs were 2.75 (95% CI 2.03 to 3.73) and 1.70 (95% CI 1.38 to 2.10), respectively. In subjects with DM2 who smoked, the RERI, AP and S values (and 95% CIs) were 1.80 (1.24 to 3.83), 0.52 (0.37 to 0.73) and 1.50 (1.18 to 1.84), respectively.

CONCLUSIONS

The results suggest there are additive interactions between DM2 and smoking and that these affect stroke in Chinese adults.

Maillard Proteomics: Opening New Pages

Protein glycation is a ubiquitous non-enzymatic post-translational modification, formed by reaction of protein amino and guanidino groups with carbonyl compounds, presumably reducing sugars and α-dicarbonyls. Resulting advanced glycation end products (AGEs) represent a highly heterogeneous group of compounds, deleterious in mammals due to their pro-inflammatory effect, and impact in pathogenesis of diabetes mellitus, Alzheimer's disease and ageing. The body of information on the mechanisms and pathways of AGE formation, acquired during the last decades, clearly indicates a certain site-specificity of glycation. It makes characterization of individual glycation sites a critical pre-requisite for understanding in vivo mechanisms of AGE formation and developing adequate nutritional and therapeutic approaches to reduce it in humans. In this context, proteomics is the methodology of choice to address site-specific molecular changes related to protein glycation. Therefore, here we summarize the methods of Maillard proteomics, specifically focusing on the techniques providing comprehensive structural and quantitative characterization of glycated proteome. Further, we address the novel break-through areas, recently established in the field of Maillard research, i.e., in vitro models based on synthetic peptides, site-based diagnostics of metabolism-related diseases (e.g., diabetes mellitus), proteomics of anti-glycative defense, and dynamics of plant glycated proteome during ageing and response to environmental stress.

Dietary iron intake, iron status, and gestational diabetes

Pregnant women are particularly vulnerable to iron deficiency and related adverse pregnancy outcomes and, as such, are routinely recommended for iron supplementation. Emerging evidence from both animal and population-based studies, however, has raised potential concerns because significant associations have been observed between greater iron stores and disturbances in glucose metabolism, including increased risk of type 2 diabetes among nonpregnant individuals. Yet, the evidence is uncertain regarding the role of iron in the development of gestational diabetes mellitus (GDM), a common pregnancy complication which has short-term and long-term adverse health ramifications for both women and their children. In this review, we critically and systematically evaluate available data examining the risk of GDM associated with dietary iron, iron supplementation, and iron status as measured by blood concentrations of several indicators. We also discuss major methodologic concerns regarding the available epidemiologic studies on iron and GDM.

Advanced glycation end products dietary restriction effects on bacterial gut microbiota in peritoneal dialysis patients; a randomized open label controlled trial

The modern Western diet is rich in advanced glycation end products (AGEs). We have previously shown an association between dietary AGEs and markers of inflammation and oxidative stress in a population of end stage renal disease (ESRD) patients undergoing peritoneal dialysis (PD). In the current pilot study we explored the effects of dietary AGEs on the gut bacterial microbiota composition in similar patients. AGEs play an important role in the development and progression of cardiovascular (CVD) disease. Plasma concentrations of different bacterial products have been shown to predict the risk of incident major adverse CVD events independently of traditional CVD risk factors, and experimental animal models indicates a possible role AGEs might have on the gut microbiota population. In this pilot randomized open label controlled trial, twenty PD patients habitually consuming a high AGE diet were recruited and randomized into either continuing the same diet (HAGE, n = 10) or a one-month dietary AGE restriction (LAGE, n = 10). Blood and stool samples were collected at baseline and after intervention. Variable regions V3-V4 of 16s rDNA were sequenced and taxa was identified on the phyla, genus, and species levels. Dietary AGE restriction resulted in a significant decrease in serum N^ε-(carboxymethyl) lysine (CML) and methylglyoxal-derivatives (MG). At baseline, our total cohort exhibited a lower relative abundance of Bacteroides and Alistipes genus and a higher abundance of Prevotella genus when compared to the published data of healthy population. Dietary AGE restriction altered the bacterial gut microbiota with a significant reduction in Prevotella copri and Bifidobacterium animalis relative abundance and increased Alistipes indistinctus, Clostridium citroniae, Clostridium hathewayi, and Ruminococcus gauvreauii relative abundance. We show in this pilot study significant microbiota differences in peritoneal dialysis patients’ population, as well as the effects of dietary AGEs on gut microbiota, which might play a role in the increased cardiovascular events in this population and warrants further studies.

Dietary Advanced Glycation End Products and Cardiometabolic Risk

PURPOSE OF REVIEW

This report analyzes emerging evidence about the role of dietary advanced glycation end products (AGEs) as a cardiometabolic risk factor. Two important aspects are discussed: First, the modulation of AGE load by dietary AGEs; second, if the evidence of clinical and observational studies is enough to make dietary recommendations towards lowering AGE intake.

RECENT FINDINGS

Clinical studies in subjects with diabetes mellitus have shown that high intake of dietary AGEs increases inflammation markers, oxidative stress, and could impair endothelial function. In subjects at risk for cardiometabolic diseases (with overweight, obesity, or prediabetes), dietary AGE restriction decreases some inflammatory molecules and improves insulin sensitivity. However, studies in healthy subjects are limited, and not all of the studies have shown a decrease in circulating AGEs. Therefore, it is still unclear if dietary AGEs represent a health concern for people potentially at risk for cardiometabolic diseases. The evidence shows that dietary AGEs are bioavailable and absorbed, and the rate of excretion depends on dietary intake. The metabolic fate of most dietary AGEs remains unknown. Regardless, most studies have shown that by diminishing AGE intake, circulating levels will also decrease. Thus, dietary AGEs can modulate the AGE load at least in patients with DM, overweight, or obesity. Studies with specific clinical outcomes and large-scale observational studies are needed for a better risk assessment of dietary AGEs and to establish dietary recommendations accordingly.