The molecular basis for oxidative stress-induced insulin resistance

Reassessing type 2 diabetes in adolescents and its management strategies based on insulin resistance

With changes in lifestyle behaviors, including dietary structure and habits, the prevalence of Youth-onset Type 2 Diabetes Mellitus (YODM) has increased 2 to 3 times compared to 30 years ago. YODM patients experience complications earlier, progress faster, and exhibit more severe symptoms. However, limited and inconclusive direct evidence, coupled with poor patient compliance, poses challenges in the clinical management of YODM. Apart from the continuous decline in pancreatic β-cell function and quantity, tissue-specific insulin resistance (IR) is also a typical characteristic of YODM. The main mechanisms of IR in YODM involve different aspects such as obesity, dietary imbalance, abnormal substance metabolism, chronic inflammation, oxidative stress, and hormonal fluctuations during adolescence. For the comprehensive management of YODM, besides achieving good control of blood glucose levels, it may be necessary to apply the most appropriate methods considering the uniqueness of the patient population and the specifics of the disease. Early identification and detection of the disease are crucial. Precise screening of patients with well-functioning pancreatic insulin β-cells, primarily characterized by IR and obesity, represents the population most likely to achieve diabetes remission or reversal through lifestyle modifications, medications, or even surgical interventions. Additionally, considering potential emotional disorders or the impact of adolescent hormones in these patients, health education for patients and caregivers is essential to make them aware of the long-term benefits of well-controlled blood glucose. In conclusion, adopting comprehensive management measures to achieve diabetes remission or reversal is the ideal goal. Controlling high blood glucose, obesity, and other risk factors related to diabetes complications is the next priority to delay the occurrence and progression of complications. A comprehensive perspective on IR provides insights and references for identifying YODM and its management strategies.

Potential molecular mechanism of exercise reversing insulin resistance and improving neurodegenerative diseases

Neurodegenerative diseases are debilitating nervous system disorders attributed to various conditions such as body aging, gene mutations, genetic factors, and immune system disorders. Prominent neurodegenerative diseases include Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and multiple sclerosis. Insulin resistance refers to the inability of the peripheral and central tissues of the body to respond to insulin and effectively regulate blood sugar levels. Insulin resistance has been observed in various neurodegenerative diseases and has been suggested to induce the occurrence, development, and exacerbation of neurodegenerative diseases. Furthermore, an increasing number of studies have suggested that reversing insulin resistance may be a critical intervention for the treatment of neurodegenerative diseases. Among the numerous measures available to improve insulin sensitivity, exercise is a widely accepted strategy due to its convenience, affordability, and significant impact on increasing insulin sensitivity. This review examines the association between neurodegenerative diseases and insulin resistance and highlights the molecular mechanisms by which exercise can reverse insulin resistance under these conditions. The focus was on regulating insulin resistance through exercise and providing practical ideas and suggestions for future research focused on exercise-induced insulin sensitivity in the context of neurodegenerative diseases.

Correlation Between Serum Vitamin E and HOMA-IR in Patients with T2DM

Background

Peroxidation is one of the important causes of insulin resistance (IR), and vitamin E is a natural antioxidant, and there may be some correlation between serum vitamin E levels and insulin resistance.

Purpose

The correlation between serum vitamin E and insulin resistance in type 2 diabetes mellitus (T2DM) population.

Methods

Two hundred and forty-two people (119 with T2DM) were included. One hundred and nineteen patients with T2DM were selected as the case group, and 123 people with non-T2DM were selected as the control group. People insulin resistance was detected by the homeostasis model assessment method (HOMA-IR) greater than 2.69 were included in the diabetic insulin resistance group, and those with HOMA-IR less than 2.69 were included in the diabetic non-insulin resistance group. Record the general body indicators, biochemical indicators, hepatic function indicators, vitamin E, and other indicators. Correlation analysis, logistic regression, trend analysis, and restricted cubic spline (RCS) were performed using SPSS 25.0 and R 4.1.1 software. Correlation analysis, logistic regression, trend analysis, restricted cubic spline (RCS) analysis were conducted on general body indicators, biochemical indicators, hepatic function indicators, vitamin E, and other indicators.

Results

The logistic regression results showed that after adjusting for confounding factors, vitamin E was an independent influencing factor for insulin resistance in T2DM patients (P < 0.001). The trend analysis results show that with the decrease of serum vitamin E levels, the risk of insulin resistance in T2DM patients gradually increases. The RCS results showed that the risk of insulin resistance was significantly increased when the serum vitamin E level was lower than 10,575.23 ng/mL.

Conclusion

Serum vitamin E levels are lower in T2DM patients than in healthy populations; Vitamin E is an independent influencing factor for HOMA-IR in T2DM patients. The risk of insulin resistance gradually increases in T2DM patients as serum vitamin E levels decrease. Vitamin E is a risk factor for insulin resistance at serum vitamin E levels below 10,575.23 ng/mL. At higher serum vitamin E levels than 10,575.23 ng/mL, vitamin E is a protective factor for insulin resistance.

Exercise training improves diabetic renal injury by reducing fetuin-A, oxidative stress and inflammation in type 2 diabetic rats

Background

Diabetic kidney disease (DKD) stands as a primary contributor to end-stage renal disease, associated with heightened mortality in cardiovascular diseases. This study aimed to explore the impact of an eight-week high-intensity interval training (HIIT) on renal injury in diabetic rats.

Methods

Twenty-eight male Wistar rats were randomly allocated into four groups: healthy control (CTL), diabetic control (DC), exercise (EX), and diabetes-exercise (D + EX). Induction of diabetes in the DC and D + EX groups occurred through a two-month high-fat diet followed by a single dose of 35 mg/kg streptozotocin (STZ). Rats in the EX and D + EX groups underwent 4-10 intervals of HIIT (80-100% Vmax) over 8 weeks. Subsequently, pathological and biochemical parameters were assessed in the serum and kidney tissue of the experimental groups.

Results

In the DC group, diabetes led to elevated kidney damage, glomerulosclerosis, fasting blood glucose (FBG), Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) index, animal weight, kidney dysfunction, albuminuria, and glomerular filtration rate. Additionally, serum and kidney levels of fetuin-A increased, along with kidney levels of KIM-1. Mechanistically, diabetes induction resulted in kidney inflammation by elevating levels of tumor necrosis factor-alpha (TNF-α), transforming growth factor beta (TGF-β), and interleukin 6 (IL-6), while reducing IL-10 levels and increasing the IL-6/IL-10 ratio. Furthermore, diabetes triggered renal oxidative stress, evidenced by increased Malondialdehyde (MDA) levels and decreased levels of glutathione peroxidase (GPx), catalase, and superoxide dismutase (SOD). HIIT mitigated the adverse effects of diabetes in the D + EX group compared to the DC group.

Conclusion

Our findings suggest that HIIT ameliorates type 2 diabetes (T2D)-induced kidney damage by mitigating inflammation, lowering serum levels of fetuin-A, and bolstering antioxidant defenses. This study highlights the potential of HIIT as a time-efficient intervention for diabetic nephropathy.

Polystyrene nanoplastics induce glycolipid metabolism disorder via NF-κB and MAPK signaling pathway in mice

Nanoplastics-induced developmental and reproductive toxicity, neurotoxicity and immunotoxicity are a focus of widespread attention. However, the effects of nanoplastics (NPs) on glycolipid metabolism and the precise underlying mechanisms are unclear at present. Here, we showed that oral administration of polystyrene nanoparticles (PS-NPs) disrupts glycolipid metabolism, with reactive oxygen species (ROS) identified as a potential key signaling molecule. After PS-NPs treatment, excessive production of ROS induced the inflammatory response and activated the antioxidant pathway through nuclear factor-erythroid factor 2-related factor 2. The activation of nuclear factor-κB (NFκB) signaling pathway induced the phosphorylation of the mitogen-activated protein kinases (MAPK) signaling pathway, which induced the activation of extracellular regulated kinases (ERK) and p38. Constitutive activation of the MAPK signaling proteins induced high continued phosphorylation of insulin receptor substrate-1, in turn, leading to decreased protein kinase B (Akt) activity, which weakened the sensitivity of liver cells to insulin signals and induced insulin resistance. In parallel, phosphorylation of Akt led to loss of control of FoXO1, a key gene of gluconeogenesis, activating transcription of glucose-6-phosphatase (G6PC) and phosphoenolpyruvate carboxykinase (PEPCK) in a manner dependent on PGC1α. Moreover, the activated ERK promoted lipid accumulation through ERK-PPARγ cascades. Therefore, sterol regulatory element-binding protein-1 and levels of its downstream lipogenic enzymes, ACC-1, were up-regulated. Upon treatment with the antioxidant resveratrol, PS-NPs-induced glucose and lipid metabolic disorders were improved by inhibiting ROS-induced activation of NFκB and MAPK signaling pathway in mice. Based on above, PS-NPs exposure disrupts glycolipid metabolism in mice, with ROS identified as a potential key signaling molecule.

Changes in Cells Associated with Insulin Resistance

Insulin is a polypeptide hormone synthesized and secreted by pancreatic β-cells. It plays an important role as a metabolic hormone. Insulin influences the metabolism of glucose, regulating plasma glucose levels and stimulating glucose storage in organs such as the liver, muscles and adipose tissue. It is involved in fat metabolism, increasing the storage of triglycerides and decreasing lipolysis. Ketone body metabolism also depends on insulin action, as insulin reduces ketone body concentrations and influences protein metabolism. It increases nitrogen retention, facilitates the transport of amino acids into cells and increases the synthesis of proteins. Insulin also inhibits protein breakdown and is involved in cellular growth and proliferation. On the other hand, defects in the intracellular signaling pathways of insulin may cause several disturbances in human metabolism, resulting in several chronic diseases. Insulin resistance, also known as impaired insulin sensitivity, is due to the decreased reaction of insulin signaling for glucose levels, seen when glucose use in response to an adequate concentration of insulin is impaired. Insulin resistance may cause, for example, increased plasma insulin levels. That state, called hyperinsulinemia, impairs metabolic processes and is observed in patients with type 2 diabetes mellitus and obesity. Hyperinsulinemia may increase the risk of initiation, progression and metastasis of several cancers and may cause poor cancer outcomes. Insulin resistance is a health problem worldwide; therefore, mechanisms of insulin resistance, causes and types of insulin resistance and strategies against insulin resistance are described in this review. Attention is also paid to factors that are associated with the development of insulin resistance, the main and characteristic symptoms of particular syndromes, plus other aspects of severe insulin resistance. This review mainly focuses on the description and analysis of changes in cells due to insulin resistance.

NADPH Oxidase 3: Beyond the Inner Ear

Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.

Obstructive sleep apnea: Beyond the dogma of obesity!

Obstructive sleep apnea (OSA) has long been studied in patients with obesity and type 2 diabetes mellitus (T2DM), due to the fact that both disorders are commonly associated with an increased body mass index (BMI). However, a link between OSA and non-obese diabetic patients is still not very elaborated, nor heavily explored. In this review, we elucidate some proposed mechanisms for the link between OSA and diabetic patients both with and beyond obesity, shedding the light on the latter case. One such mechanism is oxidative stress, a phenomenon of reactive oxygen species (ROS) imbalance seen in both of the previously mentioned disorders. A plausible explanation for the OSA-induced ROS production is the repeating episodes of hypoxia and reperfusion and their effect on the mitochondrial electron transport chain. This paper explores the literature regarding ROS imbalance as the possible missing link between OSA and Diabetes Mellitus beyond obesity, while still mentioning other possible proposed mechanisms such as a dysregulated autonomic nervous system (ANS), as well as mechanical and craniofacial abnormalities. This paper also suggests a link between OSA and diabetic complications, while exploring the clinical progress made in treating the former disorder with anti-oxidant and hypo-glycemic drugs. If further investigated, these findings could help identify novel therapeutic interventions for the treatment of OSA and Diabetic patients.

White-brown adipose tissue interplay in polycystic ovary syndrome: Therapeutic avenues

This study highlights the therapeutic potential of activating brown adipose tissue (BAT) for managing polycystic ovary syndrome (PCOS), a prevalent endocrine disorder associated with metabolic and reproductive abnormalities. BAT plays a crucial role in regulating energy expenditure and systemic insulin sensitivity, making it an attractive target for the treatment of obesity and metabolic diseases. Recent research suggests that impaired BAT function and mass may contribute to the link between metabolic disturbances and reproductive issues in PCOS. Additionally, abnormal white adipose tissue (WAT) can exacerbate these conditions by releasing adipokines and nonesterified fatty acids. In this review, we explored the impact of WAT changes on BAT function in PCOS and discussed the potential of BAT activation as a therapeutic strategy to improve PCOS symptoms. We propose that BAT activation holds promise for managing PCOS; however, further research is needed to confirm its efficacy and to develop clinically feasible methods for BAT activation.

The role of sirtuins in the regulatin of oxidative stress during the progress and therapy of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by insulin resistance and impaired glucose homeostasis. Oxidative stress, arising from an imbalance between reactive oxygen species (ROS) production and antioxidant defense systems, plays a significant role in the development and progression of T2DM. The sirtuin family, particularly Sirt1, Sirt3, and Sirt6, have emerged as key regulators of oxidative stress in various cellular processes. This review aims to explore the role of the sirtuin family in oxidative stress during the progression of T2DM and their potential as therapeutic targets. We discussed the mechanisms through which sirtuins modulate oxidative stress, their impact on insulin sensitivity, and beta-cell function involved in T2DM. Furthermore, we highlight drugs targeting sirtuin activation and related complications in T2DM. This review summarizes the role as well as mechanism of sirtuins in the regulation of oxidative stress in T2DM and available drugs targeting sirtuins in clinic, which may provide novel insights into the mechanism and therapy of T2DM.

Mechanisms of action of natural products on type 2 diabetes

Over the past several decades, type 2 diabetes mellitus (T2DM) has been considered a global public health concern. Currently, various therapeutic modalities are available for T2DM management, including dietary modifications, moderate exercise, and use of hypoglycemic agents and lipid-lowering medications. Although the curative effect of most drugs on T2DM is significant, they also exert some adverse side effects. Biologically active substances found in natural medicines are important for T2DM treatment. Several recent studies have reported that active ingredients derived from traditional medicines or foods exert a therapeutic effect on T2DM. This review compiled important articles regarding the therapeutic effects of natural products and their active ingredients on islet β cell function, adipose tissue inflammation, and insulin resistance. Additionally, this review provided an in-depth understanding of the multiple regulatory effects on different targets and signaling pathways of natural medicines in the treatment of T2DM as well as a theoretical basis for clinical effective application.

Crosstalk between autophagy and insulin resistance: evidence from different tissues

Insulin is a critical hormone that promotes energy storage in various tissues, as well as anabolic functions. Insulin resistance significantly reduces these responses, resulting in pathological conditions, such as obesity and type 2 diabetes mellitus (T2DM). The management of insulin resistance requires better knowledge of its pathophysiological mechanisms to prevent secondary complications, such as cardiovascular diseases (CVDs). Recent evidence regarding the etiological mechanisms behind insulin resistance emphasizes the role of energy imbalance and neurohormonal dysregulation, both of which are closely regulated by autophagy. Autophagy is a conserved process that maintains homeostasis in cells. Accordingly, autophagy abnormalities have been linked to a variety of metabolic disorders, including insulin resistance, T2DM, obesity, and CVDs. Thus, there may be a link between autophagy and insulin resistance. Therefore, the interaction between autophagy and insulin function will be examined in this review, particularly in insulin-responsive tissues, such as adipose tissue, liver, and skeletal muscle.

Ascorbic acid enhances chondrocyte differentiation of ATDC5 by accelerating insulin receptor signaling

Chondrogenesis is strictly regulated by several factors, including cytokines, hormones, and extracellular matrix proteins. Mouse teratocarcinoma-derived lineage cells, differentiate into chondrocytes in the presence of insulin. Although ascorbic acid promotes chondrogenic differentiation, the detailed regulative mechanisms underlying its role in chondrogenesis remain unclear. Therefore, in this study, we evaluated the effects of ascorbic acid on insulin-induced chondrogenic differentiation of ATDC5 cells and the underlying intracellular signaling. The results revealed that insulin-stimulated collagen deposition, matrix formation, calcification, and expression of chondrogenic differentiation marker genes in ATDC5 cells. This enhancement by insulin was amplified with the addition of ascorbic acid. Molecular analysis revealed that the activation of insulin-induced phosphoinositide 3-kinase (PI3K)/Akt signaling was enhanced in the presence of ascorbic acid. In contrast, Wnt/β-catenin signaling was suppressed during chondrocyte differentiation via upregulation of the Wnt agonist, secreted Frizzled-related protein 1 (sFRP-1) and 3 (sFRP-3). Notably, ascorbic acid upregulated the expression of insulin receptors and their substrates (IRS-1 and IRS-2). Furthermore, ascorbic acid reversed the suppression of IRS-1 and IRS-2 protein by insulin. These results indicate that ascorbic acid positively regulates the chondrogenic differentiation of ATDC5 cells via enhancement of insulin signaling. Our findings provide a substantial basis for further elucidation of the regulatory mechanisms of chondrocyte differentiation and the pathophysiology of OA, thus aiding in development of effective treatment strategies.

Health risks of neonicotinoids chronic exposure and its association with glucose metabolism: A case-control study in rural China

Since neonicotinoids (NNIs) are widely used around the world, they are extensively distributed in the environment and frequently occurred in humans. This study was conducted to assess the risk of NNIs residues in vegetables and fruits in Henan province, and evaluate the associations of NNIs single and mixed exposure with glucose metabolism, and further explore whether testosterone mediated these relationships in Henan rural population. The data of vegetables and fruits were collected from Henan Province in 2020-2021, and participants were drawn from the Henan Rural Cohort study. Hazard quotient (HQ) and hazard index (HI) were used to assess the risk of exposure to the individual and combined NNIs through vegetables or fruits intake. Relative potency factor (RPF) method was utilized to normalize each NNIs to imidacloprid (IMIRPF). Generalized linear models were used to explore the effects of each NNIs and IMIRPF on glucose metabolism. Weight quartile sum (WQS) regression and Bayesian kernel machine regression (BKMR) model were applied to estimate the effect of NNIs mixtures on glucose metabolism. Mediation analysis was employed to explore whether testosterone mediated these relationships. The HQs and HI in both vegetables and fruits were much lower than 1, which indicated that NNIs in vegetables and fruits were not expected to cause significant adverse effects. However, plasma natural logarithm nitenpyram (Ln_NIT), Ln_thiacloprid-amid (Ln_THD-A), and Ln_IMIeq were positively associated with type 2 diabetes mellitus (T2DM) (odds ratio (OR) (95% confidence interval (CI)): 1.12 (1.05, 1.19), 1.21 (1.10, 1.32), and 1.48 (1.22, 1.80)). Both WQS regression and BKMR models observed significantly positive associations between NNIs mixture exposure and T2DM. Testosterone partially mediated these associations among women (PE = 6.67%). These findings suggest that human NNIs exposure may impair glucose metabolism and could contribute to rising rates of T2DM, and it's necessary to regulate the use of pesticides in rural areas.

Polycystic Ovary Syndrome and Oxidative Stress-From Bench to Bedside

Oxidative stress (OS) is a condition that occurs as a result of an imbalance between the production of reactive oxygen species (ROS) and the body's ability to detoxify and neutralize them. It can play a role in a variety of reproductive system conditions, including polycystic ovary syndrome (PCOS), endometriosis, preeclampsia, and infertility. In this review, we briefly discuss the links between oxidative stress and PCOS. Mitochondrial mutations may lead to impaired oxidative phosphorylation (OXPHOS), decreased adenosine triphosphate (ATP) production, and an increased production of ROS. These functional consequences may contribute to the metabolic and hormonal dysregulation observed in PCOS. Studies have shown that OS negatively affects ovarian follicles and disrupts normal follicular development and maturation. Excessive ROS may damage oocytes and granulosa cells within the follicles, impairing their quality and compromising fertility. Impaired OXPHOS and mitochondrial dysfunction may contribute to insulin resistance (IR) by disrupting insulin signaling pathways and impairing glucose metabolism. Due to dysfunctional OXPHOS, reduced ATP production, may hinder insulin-stimulated glucose uptake, leading to IR. Hyperandrogenism promotes inflammation and IR, both of which can increase the production of ROS and lead to OS. A detrimental feedback loop ensues as IR escalates, causing elevated insulin levels that exacerbate OS. Exploring the relations between OS and PCOS is crucial to fully understand the role of OS in the pathophysiology of PCOS and to develop effective treatment strategies to improve the quality of life of women affected by this condition. The role of antioxidants as potential therapies is also discussed.

Role of Oxidative Stress on Insulin Resistance in Diet-Induced Obesity Mice

Insulin resistance is the link between obesity and type 2 diabetes mellitus. The molecular mechanism by which obese individuals develop insulin resistance has not yet been fully elucidated; however, inconclusive and contradictory studies have shown that oxidative stress may be involved in the process. Thus, this study aimed to evaluate the effect of reactive species on the mechanism of insulin resistance in diet-induced obese mice. Obese insulin-resistant mice were treated with N-acetylcysteine (NAC; 50 mg/kg per day, for 15 days) by means of oral gavage. Twenty-four hours after the last NAC administration, the animals were euthanized and their tissues were extracted for biochemical and molecular analyses. NAC supplementation induced improved insulin resistance and fasting glycemia, without modifications in food intake, body weight, and adiposity. Obese mice showed increased dichlorofluorescein (DCF) oxidation, reduced catalase (CAT) activity, and reduced glutathione levels (GSH). However, treatment with NAC increased GSH and CAT activity and reduced DCF oxidation. The gastrocnemius muscle of obese mice showed an increase in nuclear factor kappa B (NFκB) and protein tyrosine phosphatase (PTP1B) levels, as well as c-Jun N-terminal kinase (JNK) phosphorylation compared to the control group; however, NAC treatment reversed these changes. Considering the molecules involved in insulin signaling, there was a reduction in insulin receptor substrate (IRS) and protein kinase B (Akt) phosphorylation. However, NAC administration increased IRS and Akt phosphorylation and IRS/PI3k (phosphoinositide 3-kinase) association. The results demonstrated that oxidative stress-associated obesity could be a mechanism involved in insulin resistance, at least in this animal model.

Stevia (Stevia rebaudiana) extract ameliorates insulin resistance by regulating mitochondrial function and oxidative stress in the skeletal muscle of db/db mice

BACKGROUND

Type 2 diabetes mellitus (T2DM), a growing health problem worldwide, is a metabolic disorder characterized by hyperglycemia due to insulin resistance and defective insulin secretion by pancreatic β-cells. The skeletal muscle is a central organ that consumes most of the insulin-stimulated glucose in the body, and insulin resistance can damage muscles in T2DM. Based on a strong correlation between diabetes and muscles, we investigated the effects of stevia extract (SE) and stevioside (SV) on the skeletal muscle of diabetic db/db mice.

METHODS

The mice were administered saline, metformin  (200 mg/kg/day), SE (200 and 500 mg/kg/day), and SV (40 mg/kg/day) for 35 days. During administration, we checked the levels of fasting blood glucose twice a week and conducted the oral glucose tolerance test (OGTT) and insulin tolerance test (ITT). After administration, we analyzed serum biochemical parameters, triglyceride (TG), total cholesterol (TC), insulin and antioxidant enzymes, and the cross-sectional area of skeletal muscle fibers of db/db mice. Western blots were conducted using the skeletal muscle of mice to examine the effect of SE and SV on protein expression of insulin signaling, mitochondrial function, and oxidative stress.

RESULTS

SE and SV administration lowered the levels of fasting blood glucose, OGTT, and ITT in db/db mice. The administration also decreased serum levels of TG, TC, and insulin while increasing those of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Interestingly, muscle fiber size was significantly increased in db/db mice treated with SE500 and SV. In the skeletal muscle of db/db mice, SE and SV administration activated insulin signaling by increasing the protein expression of insulin receptor substrate, Akt, and glucose transporter type 4. Furthermore, SE500 administration markedly increased the protein expression of AMP-activated protein kinase-α, sirtuin-1, and peroxisome proliferator-activated receptor-γ coactivator-1α. SV administration significantly reduced oxidative stress by down-regulating the protein expression of 4-hydroxynonenal, heme oxygenase-1, SOD, and GPx. In addition, SE500 and SV administration suppressed the expression of apoptosis-related proteins in the skeletal muscle of db/db mice.

CONCLUSION

SE and SV administration attenuated hyperglycemia in diabetic mice. Moreover, the administration ameliorated insulin resistance by regulating mitochondrial function and oxidative stress, increasing muscle fiber size. Overall, this study suggests that SE and SV administration may serve as a potential strategy for the treatment of diabetic muscles.

Cross-sectional and longitudinal relationships between ozone exposure and glucose homeostasis: Exploring the role of systemic inflammation and oxidative stress in a general Chinese urban population

The adverse health effects of ozone pollution have been a globally concerned public health issue. Herein we aim to investigate the association between ozone exposure and glucose homeostasis, and to explore the potential role of systemic inflammation and oxidative stress in this association. A total of 6578 observations from the Wuhan-Zhuhai cohort (baseline and two follow-ups) were included in this study. Fasting plasma glucose (FPG) and insulin (FPI), plasma C-reactive protein (CRP, biomarker for systemic inflammation), urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG, biomarker for oxidative DNA damage), and urinary 8-isoprostane (biomarker for lipid peroxidation) were repeatedly measured. After adjusting for potential confounders, ozone exposure was positively associated with FPG, FPI, and homeostasis model assessment of insulin resistance (HOMA-IR), and negatively associated with HOMA of beta cell function (HOMA-β) in cross-sectional analyses. Each 10 ppb increase in cumulative 7-days moving average ozone was associated with a 13.19%, 8.31%, and 12.77% increase in FPG, FPI, and HOMA-IR, respectively, whereas a 6.63% decrease in HOMA-β (all P < 0.05). BMI modified the associations of 7-days ozone exposure with FPI and HOMA-IR, and the effects were stronger in subgroup whose BMI ≥24 kg/m². Consistently high exposure to annual average ozone was associated with increased FPG and FPI in longitudinal analyses. Furthermore, ozone exposure was positively related to CRP, 8-OHdG, and 8-isoprostane in dose-response manner. Increased CRP, 8-OHdG, and 8-isoprostane could dose-dependently aggravate glucose homeostasis indices elevations related to ozone exposure. Increased CRP and 8-isoprostane mediated 2.11-14.96% of ozone-associated glucose homeostasis indices increment. Our findings suggested that ozone exposure could cause glucose homeostasis damage and obese people were more susceptible. Systemic inflammation and oxidative stress might be potential pathways in glucose homeostasis damage induced by ozone exposure.

Therapeutic treatments for diabetes mellitus-induced liver injury by regulating oxidative stress and inflammation

Diabetes mellitus (DM) is a metabolic disease that affects all systems in the body, including the liver. Numerous studies have reported that chronic DM etiology and pathogenesis complications implicate oxidative stress, generating reactive oxygen species, such as superoxide anions and free radicals. In addition, pro-inflammatory reactions are also underlying functions closely related to oxidative stress that further exacerbate pathological DM states. The liver is especially susceptible to hyperglycemia-induced oxidative stress and the related inflammation. Thus, anti-oxidation and anti-inflammation therapies are promising strategies for treating liver damage. This review summarizes therapeutic treatments attenuating the generation of oxidative stress and pro-inflammation, which also cause DM-induced liver injury. Although the treatments have several impediments to be solved, these remedies may have clinically important implications under the absence of effective drugs for the damaged liver in DM patients.

Vitamin E supplementation in the treatment on nonalcoholic fatty liver disease (NAFLD): Evidence from an umbrella review of meta-analysis on randomized controlled trials

OBJECTIVE

We conducted this umbrella review of meta-analysis on randomized controlled trials to clarify the effects of vitamin E administration on alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), degrees of steatosis and fibrosis in patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

PubMed, MEDLINE, SCOPUS, EMBASE, and Web of Science were searched to identify pertinent articles published up to June 2023. To calculate the overall effect size (ES) and confidence intervals (CI), random-effects model was used.

RESULTS

Six meta-analyses were included in the umbrella review. By pooling ES based on the random-effects model, we found that vitamin E supplementation significantly decreased ALT (ES -6.47, 95% CI -11.73 to -1.22, P = 0.01), AST (ES -5.35, 95% CI -9.78 to -0.93, P = 0.01), degrees of fibrosis (ES -0.24, 95% CI -0.36 to -0.12, P < 0.001) and steatosis (ES -0.67, 95% CI -0.88 to -0.45, P < 0.001) in NAFLD patients, but had no effect on GGT. In the subgroup analyses, we detected that fibrosis scores notably decreased when vitamin E dosage was >600 IU/day (ES -0.25, 95% CI -0.41 to -0.10, P = 0.002) and when the treatment duration was ≥12 months (ES -0.24, 95% CI -0.37 to -0.12, P < 0.001).

CONCLUSION

Vitamin E administration improves ALT, AST, fibrosis, and steatosis in NAFLD subjects. Fibrosis scores were significantly reduced when vitamin E dosage exceeded 600 IU/day or with a treatment duration of at least 12 months.

Underlying biochemical effects of intermittent fasting, exercise and honey on streptozotocin-induced liver damage in rats

Purpose

Derangements of liver transcriptional factors and enzymes have important implications in diabetes-induced related complications. Hence, this study which consists of two experimental phases was aimed at evaluating the possible underlying molecular mechanisms of intermittent fasting (IF), exercise starvation and honey in streptozotocin (STZ)-mediated liver damage in diabetic rats.

Methods

The diabetic rats were treated orally with distilled water (0.5 ml/kg), IF, starvation and honey at 1 g/kg body weight in the non-diabetic phase for four (4) weeks. After STZ injections, four (4) weeks of IF, exercise, starvation, and honey therapy were used as interventions prior to a biochemical evaluation of the liver.

Results

IF and exercise greatly decreased liver transcription factor (resistin, SREBP-1c), inflammatory cytokines/enzyme (TNF-α, IL-6, IL-1ß, MPO) as well as oxidative and nitrergic stress with correspondence increased liver PPAR-γ, IL-10, SOD, CAT and GSH in diabetic rats unlike starvation and honey regimen relative to diabetic controls. Furthermore, IF and exercise significantly improved hepatic glycogen synthase and decreased glycogen phosphorylase in diabetic rats compared to the diabetic control group, but starvation and honey therapy had no such influence. IF and exercise strategically reduces STZ-induced liver metabolic disorder via through modulation of liver transcriptional factors and inhibition of pro-inflammatory cytokines, oxido-nitrergic and adipokine signaling pathway.

A systematic review on anti-diabetic action of 7-O-galloyl-D-sedoheptulose, a polyphenol from Corni Fructus, in type 2 diabetic mice with hepatic and pancreatic damage

Traditional medicines are recently being focused on to treat diabetes and its complications because of their lack of toxic and/or side effects. This report describes the effects of 7-O-galloyl-D-sedoheptulose (GS), a polyphenolic compound isolated from Corni Fructus, on type 2 diabetic db/db mice with hepatic and pancreatic damage. We examined several biochemical factors and oxidative stress- and inflammation-related markers. In the serum, levels of glucose, leptin, insulin, C-peptide, resistin, tumor necrosis factor-α, and interleukin-6 were down-regulated, while adiponectin was augmented by GS treatment. In addition, GS suppressed the reactive oxygen species and lipid peroxidation in the serum, liver, and pancreas, but increased the pancreatic insulin and pancreatic C-peptide contents. These results were derived from attenuating the expression of nicotinamide adenine dinucleotide phosphate oxidase subunit proteins, Nox-4 and p22^phox. Augmented nuclear factor (NF)-E2-related factor 2 and heme oxygenase-1 were reduced with a decrease in oxidative stress during GS treatment. NF-κB-related pro-inflammatory factors were also alleviated in hepatic tissue. Moreover, GS modulated the protein expressions of pro-inflammatory NF-κB, cyclooxygenase-2, inducible nitric oxide synthase, c-Jun N-terminal kinase (JNK), phosphor-JNK, activator protein-1, transforming growth factor-β₁, and fibronectin. Based on these results, we demonstrated that the anti-diabetic action of GS may be due to its anti-oxidative stress property and anti-inflammatory action.

Salix babylonica L. mitigates pancreatic damage by regulating the Beclin-P62/SQSTM1 autophagy pathway in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Salix babylonica L. belongs to the genus Salix, family Salicaceae. It is traditionally used as an antipyretic, antirheumatic, antidiabetic and for the treatment of ulcers and parasite skin diseases. It also has a range of pharmacological effects, such as anti-inflammatory, anti-tumor, antioxidant, and antibacterial effects. However, there are no reports on the phytochemical profile and efficacy of its leaves extract to modulate dexamethasone induced pancreatic damage.

AIM OF THE STUDY

The present study was performed to annotate the phytoconstituents of Salix babylonica leaf extract and explore whether and how it could modulate dexamethasone-induced pancreatic damage and the role of oxidative stress and autophagy in mediating its protective effects.

MATERIALS AND METHODS

Wistar rats were used for this study. Salix babylonica in two dose levels (100 and 200 mg/kg) or metformin (50 mg/kg) was given by oral gavage concurrently with dexamethasone which was injected SC in a dose of 10 mg/kg for 4 consecutive days.

RESULTS

LC-MS analysis furnished 84 secondary metabolites belonging to phenolic acids, salicinoids, proanthocyanidins, flavonoids, cyclohexanediol glycosides, and hydroxy fatty acids. S. babylonica at both dose levels and metformin decreased the elevated pancreatic beclin while elevated the decreased pancreatic P62/SQSTM1 content compared to dexamethasone. These effects were associated with improved histopathological changes, glycemic and lipid parameters indicating that there might be a connection between autophagy and dexamethasone-induced pancreatic damage. Given that the level of GSH was negatively correlated with the levels of beclin and positively correlated with P62/SQSTM1, while both MDA and NO levels were positively correlated with beclin and negatively correlated with P62/SQSTM1, it seems that dexamethasone induced autophagy may be attributed to dexamethasone induced pancreatic oxidative stress.

CONCLUSION

Our results indicate that S. babylonica protects pancreatic tissues against dexamethasone-induced damage by decreasing oxidative stress and its associated autophagy. Our study reveals a new mechanism for dexamethasone effects on pancreas and shows the potential therapeutic role of S. babylonica in mitigating dexamethasone adverse effects on pancreas and establishes the groundwork for future clinical applications.

Pharmacological and mechanistic study of PS1, a Pdia4 inhibitor, in β-cell pathogenesis and diabetes in db/db mice

Pdia4 has been characterized as a key protein that positively regulates β-cell failure and diabetes via ROS regulation. Here, we investigated the function and mechanism of PS1, a Pdia4 inhibitor, in β-cells and diabetes. We found that PS1 had an IC₅₀ of 4 μM for Pdia4. Furthermore, PS1 alone and in combination with metformin significantly reversed diabetes in db/db mice, 6 to 7 mice per group, as evidenced by blood glucose, glycosylated hemoglobin A1c (Hb_A1c), glucose tolerance test, diabetic incidence, survival and longevity (P < 0.05 or less). Accordingly, PS1 reduced cell death and dysfunction in the pancreatic β-islets of db/db mice as exemplified by serum insulin, serum c-peptide, reactive oxygen species (ROS), islet atrophy, and homeostatic model assessment (HOMA) indices (P < 0.05 or less). Moreover, PS1 decreased cell death in the β-islets of db/db mice. Mechanistic studies showed that PS1 significantly increased cell survival and insulin secretion in Min6 cells in response to high glucose (P < 0.05 or less). This increase could be attributed to a reduction in ROS production and the activity of electron transport chain complex 1 (ETC C1) and Nox in Min6 cells by PS1. Further, we found that PS1 inhibited the enzymatic activity of Pdia4 and mitigated the interaction between Pdia4 and Ndufs3 or p22 in Min6 cells (P < 0.01 or less). Taken together, this work demonstrates that PS1 negatively regulated β-cell pathogenesis and diabetes via reduction of ROS production involving the Pdia4/Ndufs3 and Pdia4/p22 cascades.

Microalgae as a Nutraceutical Tool to Antagonize the Impairment of Redox Status Induced by SNPs: Implications on Insulin Resistance

Microalgae represent a growing innovative source of nutraceuticals such as carotenoids and phenolic compound which are naturally present within these single-celled organisms or can be induced in response to specific growth conditions. The presence of the unfavourable allelic variant in genes involved in the control of oxidative stress, due to one or more SNPs in gene encoding protein involved in the regulation of redox balance, can lead to pathological conditions such as insulin resistance, which, in turn, is directly involved in the pathogenesis of type 2 diabetes mellitus. In this review we provide an overview of the main SNPs in antioxidant genes involved in the promotion of insulin resistance with a focus on the potential role of microalgae-derived antioxidant molecules as novel nutritional tools to mitigate oxidative stress and improve insulin sensitivity.

Insulin: A connection between pancreatic β cells and the hypothalamus

Insulin is a hormone secreted by pancreatic β cells. The concentration of glucose in circulation is proportional to the secretion of insulin by these cells. In target cells, insulin binds to its receptors and activates phosphatidylinositol-3-kinase/protein kinase B, inducing different mechanisms depending on the cell type. In the liver it activates the synthesis of glycogen, in adipose tissue and muscle it allows the capture of glucose, and in the hypothalamus, it regulates thermogenesis and appetite. Defects in insulin function [insulin resistance (IR)] are related to the development of neurodegenerative diseases in obese people. Furthermore, in obesity and diabetes, its role as an anorexigenic hormone in the hypothalamus is diminished during IR. Therefore, hyperphagia prevails, which aggravates hyper-glycemia and IR further, becoming a vicious circle in which the patient cannot regulate their need to eat. Uncontrolled calorie intake induces an increase in reactive oxygen species, overcoming cellular antioxidant defenses (oxidative stress). Reactive oxygen species activate stress-sensitive kinases, such as c-Jun N-terminal kinase and p38 mitogen-activated protein kinase, that induce phos-phorylation in serine residues in the insulin receptor, which blocks the insulin signaling pathway, continuing the mechanism of IR. The brain and pancreas are organs mainly affected by oxidative stress. The use of drugs that regulate food intake and improve glucose metabolism is the conventional therapy to improve the quality of life of these patients. Currently, the use of antioxidants that regulate oxidative stress has given good results because they reduce oxidative stress and inflammatory processes, and they also have fewer side effects than synthetic drugs.

How Can Insulin Resistance Cause Alzheimer's Disease?

Alzheimer's disease (AD) is a neurodegenerative disorder associated with cognitive decline. Despite worldwide efforts to find a cure, no proper treatment has been developed yet, and the only effective countermeasure is to prevent the disease progression by early diagnosis. The reason why new drug candidates fail to show therapeutic effects in clinical studies may be due to misunderstanding the cause of AD. Regarding the cause of AD, the most widely known is the amyloid cascade hypothesis, in which the deposition of amyloid beta and hyperphosphorylated tau is the cause. However, many new hypotheses were suggested. Among them, based on preclinical and clinical evidence supporting a connection between AD and diabetes, insulin resistance has been pointed out as an important factor in the development of AD. Therefore, by reviewing the pathophysiological background of brain metabolic insufficiency and insulin insufficiency leading to AD pathology, we will discuss how can insulin resistance cause AD.

Insulin Metabolism in Polycystic Ovary Syndrome: Secretion, Signaling, and Clearance

Polycystic ovary syndrome (PCOS) is the most common endocrine and metabolic disorder in women of reproductive age. Its heterogeneous clinical presentation is characterized by hyperandrogenemia, reproductive changes, polycystic ovary morphology, and insulin resistance (IR). The primary pathophysiological process in its multifactorial etiology has not yet been identified. However, the two most proposed core etiologies are the disruption of insulin metabolism and hyperandrogenemia, both of which begin to intertwine and propagate each other in the later stages of the disease. Insulin metabolism can be viewed as the interconnectedness of beta cell function, IR or insulin sensitivity, and insulin clearance. Previous studies of insulin metabolism in PCOS patients have yielded conflicting results, and literature reviews have focused mainly on the molecular mechanisms and clinical implications of IR. In this narrative review, we comprehensively explored the role of insulin secretion, clearance, and decreased sensitivity in target cells as a potential primary insult in PCOS pathogenesis, along with the molecular mechanism behind IR in PCOS.

Potential Roles of mtDNA Mutations in PCOS-IR: A Review

Polycystic ovary syndrome (PCOS) is the most common heterogeneous endocrine disease that affecting females in reproductive age. Insulin resistance (IR), an important molecular basis for PCOS, accounts for at least 75% of women carrying this syndrome. Although there have been many studies on PCOS-IR, the detailed mechanisms are not fully understood. As essential hub for energy generation, mitochondria are critical to insulin secretion and normal function, whereas mutations in mitochondrial DNA (mtDNA) result in mitochondrial dysfunctions contributing to the pathophysiology of PCOS-IR via the regulation of balance of oxidative stress (OS), energy deficiency, or hormone metabolism. In the current review, we summarize the clinical and molecular features of PCOS-IR and discuss molecular mechanisms related to mtDNA mutations.

Ageing, Metabolic Dysfunction, and the Therapeutic Role of Antioxidants

The gradual ageing of the world population has been accompanied by a dramatic increase in the prevalence of obesity and metabolic diseases, especially type 2 diabetes. The adipose tissue dysfunction associated with ageing and obesity shares many common physiological features, including increased oxidative stress and inflammation. Understanding the mechanisms responsible for adipose tissue dysfunction in obesity may help elucidate the processes that contribute to the metabolic disturbances that occur with ageing. This, in turn, may help identify therapeutic targets for the treatment of obesity and age-related metabolic disorders. Because oxidative stress plays a critical role in these pathological processes, antioxidant dietary interventions could be of therapeutic value for the prevention and/or treatment of age-related diseases and obesity and their complications. In this chapter, we review the molecular and cellular mechanisms by which obesity predisposes individuals to accelerated ageing. Additionally, we critically review the potential of antioxidant dietary interventions to counteract obesity and ageing.

Parkin-mediated mitophagy is negatively regulated by FOXO3A, which inhibits Plk3-mediated mitochondrial ROS generation in STZ diabetic stress-treated pancreatic β cells

Diabetes mellitus (DM) is one of the most researched metabolic diseases worldwide. It leads to extensive complications such as cardiovascular disease, nephropathy, retinopathy, and peripheral and central nervous system through an inability to produce or respond to insulin. Although oxidative stress-mediated mitophagy has been reported to play an important role in the pathogenesis of DM, specific studies are still lacking as well as remain highly controversial. Here, we found that Parkin-mediated mitophagy in pancreatic β cells under streptozotocin (STZ)-diabetic stress was induced by Polo-like kinase 3 (Plk3) and inhibited by the transcription factor Forkhead Box O3A (FOXO3A). STZ stress induces mitochondrial recruitment of Parkin through Plk3-mediated mitochondrial reactive oxygen species (ROS) generation, which causes pancreatic cell damage. Conversely, FOXO3A acts as negative feedback to prevent diabetic stress by inhibiting Plk3. Meanwhile, antioxidants including N-acetylcysteine (NAC) and natural COA water scientifically block these mitochondrial ROS and mitochondrial recruitment of Parkin by inhibiting Plk3. Through a 3D organoid ex vivo model, we confirmed that not only ROS inhibitors but also mitophagy inhibitory factors such as 3-MA or Parkin deletion can compensate for pancreatic cell growth and insulin secretion under STZ diabetic stress. These findings suggest that the Plk3-mtROS-PINK1-Parkin axis is a novel mitophagy process that inhibits pancreatic β-cell growth and insulin secretion and FOXO3A and antioxidants may provide new alternatives for effective diabetes treatment strategies in the future.

Prevalence and Risk Factors of Metabolic-Associated Fatty Liver Disease Among Hospital Staff

Background

The prevalence of metabolism-related fatty liver disease (MAFLD) has been rarely reported in hospital staffs. The aim of this study was to assess the prevalence and risk factors for MAFLD in hospital staffs aged ≥18 years.

Methods

Based on type B ultrasonic, hospital staffs who underwent medical examinations at the second Affiliated Hospital of Hainan Medical University from January 2022 to March 2022 were classified into health control group (661 subjects) and MAFLD group (223 subjects), demographic, biochemical and blood examination information were compared between 2 groups. Independent risk factors for MAFLD were determined by logistic regression. Predictive values of risk factors of MAFLD were evaluated by receiver operating characteristic (ROC) curves.

Results

The prevalence of MAFLD was 33.7%. Older age (OR=1.08, p<0.001), H. pylori infection (OR=0.234, p=0.02), triglyceride-glucose (TyG) (OR=7.001, p<0.001), low-density lipoprotein cholesterol (LDL-C) (OR=2.076, p=0.028), red blood cell (RBC) (OR=2.386, p=0.001), eating out (OR=0.048, p=0.001), regular exercise (OR=23.017, p<0.001), and overweight (OR=3.891, p=0.003) were independently associated factors for MAFLD. The AUC of model predicting MAFLD is 0.910 [95% CI (0.886, 0.934)], with 0.794 sensitivity, 0.908 specificity. The diagnostic value of model was higher in the female MAFLD group after stratified analysis according to gender. The model showed that TyG was the factor contributing more to MAFLD. The diagnostic value of TyG was higher in the female MAFLD group than male MAFLD group.

Conclusion

The prevalence of MAFLD among hospital staffs was 33.7%. TyG can be used to predict MAFLD especially for female hospital staffs for early intervention.

Metabolites of endophytic fungi isolated from leaves of Bauhinia variegata exhibit antioxidant activity and agonist activity on peroxisome proliferator-activated receptors α, β/δ and γ

Diabetes mellitus is a metabolic disorder that affects millions of people worldwide and is linked to oxidative stress and inflammation. Thiazolidinediones (TZD) improve insulin sensitization and glucose homeostasis mediated by the activation of peroxisome proliferator-activated receptors γ (PPARγ) in patients with type 2 diabetes. However, their use is associated with severe adverse effects such as loss of bone mass, retention of body fluids, liver and heart problems, and increased risk of bladder cancer. Partial PPARγ agonists can promote the beneficial effects of thiazolidinediones with fewer adverse effects. Endophytic fungi colonize plant tissues and have a particularly active metabolism caused by the interaction with them, which leads to the production of natural products with significant biological effects that may be like that of the colonized plant. Here, we identify seven endophytic fungi isolated from Bauhinia variegata leaves that have antioxidant activities. Also, one of the extracts presented pan-agonist activity on PPAR, and another showed activity in PPARα and PPARβ/δ. A better understanding of this relationship could help to comprehend the mechanism of action of antioxidants in treating diabetes and its complications. Moreover, compounds with these capabilities to reduce oxidative stress and activate the receptor that promotes glucose homeostasis are promising candidates in treatment of diabetes.

OXIDATIVE STRESS AND REPRODUCTIVE FUNCTION: Oxidative stress in polycystic ovary syndrome

In brief

A genetic, epigenetic, and environmental association exists between oxidative stress (OS) and polycystic ovary syndrome (PCOS), expressed in a multifaceted clinical profile. This review summarizes and discusses the role of OS in the pathogenesis of PCOS syndrome, focusing on metabolic, reproductive, and cancer complications.

Abstract

Oxidative stress (OS), an imbalance between oxidants and antioxidants in cells, is one of many factors playing essential roles in the pathogenesis of polycystic ovary syndrome (PCOS). PCOS is described mainly as a disproportion of reproductive hormones, leading to chronic anovulation and infertility in women. Interestingly, OS in PCOS may be associated with many disorders and diseases. This review focuses on characteristic markers of OS in PCOS and the relationship between OS and PCOS related to insulin resistance (IR), hyperandrogenemia, obesity, chronic inflammation, cardiovascular diseases, and cancer. Interestingly, in patients with PCOS, an increase in oxidative status and insufficient compensation of the increase in antioxidant status before any cardiovascular complications are observed. Moreover, free radicals promote carcinogenesis in PCOS patients. However, despite these data, it has not been established whether oxygen stress influences PCOS development or a secondary disorder resulting from hyperglycemia, IR, and cardiovascular and cancer complications in women.

Methionine restriction - Association with redox homeostasis and implications on aging and diseases

Methionine is an essential amino acid, involved in the promotion of growth, immunity, and regulation of energy metabolism. Over the decades, research has long focused on the beneficial effects of methionine supplementation, while data on positive effects of methionine restriction (MR) were first published in 1993. MR is a low-methionine dietary intervention that has been reported to ameliorate aging and aging-related health concomitants and diseases, such as obesity, type 2 diabetes, and cognitive disorders. In addition, MR seems to be an approach to prolong lifespan which has been validated extensively in various animal models, such as Caenorhabditis elegans, Drosophila, yeast, and murine models. MR appears to be associated with a reduction in oxidative stress via so far mainly undiscovered mechanisms, and these changes in redox status appear to be one of the underlying mechanisms for lifespan extension and beneficial health effects. In the present review, the association of methionine metabolism pathways with redox homeostasis is described. In addition, the effects of MR on lifespan, age-related implications, comorbidities, and diseases are discussed.

KCNH6 Enhanced Hepatic Glucose Metabolism through Mitochondrial Ca2+ Regulation and Oxidative Stress Inhibition

KCNH6 has been proven to affect glucose metabolism and insulin secretion both in humans and mice. Further study revealed that Kcnh6 knockout (KO) mice showed impaired glucose tolerance. However, the precise function of KCNH6 in the liver remains unknown. Mitochondria have been suggested to maintain intracellular Ca2+ homeostasis; ROS generation and defective mitochondria can cause glucose metabolism disorders, including type 2 diabetes (T2D). Here, we found that Kcnh6 attenuated glucose metabolism disorders by decreasing PEPCK and G6pase abundance and induced Glut2 and IRS2 expression. Overexpression of Kcnh6 increased hepatic glucose uptake and glycogen synthesis. Kcnh6 attenuated intracellular and mitochondrial calcium levels in primary hepatocytes and reduced intracellular ROS and mitochondrial superoxide production. Kcnh6 suppressed oxidative stress by inhibiting mitochondrial pathway activation and NADPH oxidase expression. Experiments demonstrated that Kcnh6 expression improved hepatic glucose metabolism disorder through the c-Jun N-terminal kinase and p38MAPK signaling pathways. These results were confirmed by experiments evaluating the extent to which forced Kcnh6 expression rescued metabolic disorder in KO mice. In conclusion, KCNH6 enhanced hepatic glucose metabolism by regulating mitochondrial Ca2+ levels and inhibiting oxidative stress. As liver glucose metabolism is key to T2D, understanding KCNH6 functions may provide new insights into the causes of diabetes.

Modulation of endoplasmic reticulum stress via sulforaphane-mediated AMPK upregulation against nonalcoholic fatty liver disease in rats

Nonalcoholic fatty liver disease (NAFLD) is a major health concern. Endoplasmic reticulum (ER) stress, inflammation, and metabolic dysfunctions may be targeted to prevent the progress of nonalcoholic fatty liver disease. Sulforaphane (SFN), a sulfur-containing compound that is abundant in broccoli florets, seeds, and sprouts, has been reported to have beneficial effects on attenuating metabolic diseases. In light of this, the present study was designed to elucidate the mechanisms by which SFN ameliorated ER stress, inflammation, lipid metabolism, and insulin resistance - induced by a high-fat diet and ionizing radiation (IR) in rats. In our study, the rats were randomly divided into five groups: control, HFD, HFD + SFN, HFD + IR, and HFD + IR + SFN groups. After the last administration of SFN, liver and blood samples were taken. As a result, the lipid profile, liver enzymes, glucose, insulin, IL-1β, adipokines (leptin and resistin), and PI3K/AKT protein levels, as well as the mRNA gene expression of ER stress markers (IRE-1, sXBP-1, PERK, ATF4, and CHOP), fatty acid synthase (FAS), peroxisome proliferator-activated receptor-α (PPAR-α). Interestingly, SFN treatment modulated the levels of proinflammatory cytokine including IL-1β, metabolic indices (lipid profile, glucose, insulin, and adipokines), and ER stress markers in HFD and HFD + IR groups. SFN also increases the expression of PPAR-α and AMPK genes in the livers of HFD and HFD + IR groups. Meanwhile, the gene expression of FAS and CHOP was significantly attenuated in the SFN-treated groups. Our results clearly show that SFN inhibits liver toxicity induced by HFD and IR by ameliorating the ER stress events in the liver tissue through the upregulation of AMPK and PPAR-α accompanied by downregulation of FAS and CHOP gene expression.

The Additive Values of the Classification of Higher Serum Uric Acid Levels as a Diagnostic Criteria for Metabolic-Associated Fatty Liver Disease

Serum uric acid (SUA) is regarded as an independent risk factor for nonalcoholic fatty liver disease (NAFLD). However, the role of SUA in the new diagnosis flowchart of metabolic-associated fatty liver disease (MAFLD) remains unclear. A cross-sectional study enrolled consecutive individuals with ultrasonography and magnetic resonance imaging−based proton density fat fraction (MRI-PDFF) measurements in the First Affiliated Hospital of Sun Yat-sen University from January 2015 to December 2021. All patients were divided into four groups according to their baseline SUA levels and sex. Of the 3537 ultrasound-diagnosed and 1017 MRI-PDFF-diagnosed MAFLD patients included, the prevalence of severe steatosis determined with ultrasound or MRI-PDFF increased across the serum SUA quartiles. The SUA cutoffs were identified as ≥478 µmol/L and ≥423.5 µmol/L for severe steatosis in male and female MAFLD, respectively. Furthermore, using these cutoff values, patients with higher SUA levels in the NAFLD−non-MAFLD group had higher liver fat contents than those without (16.0% vs. 9.7%, p < 0.001). The lean/normal-weight NAFLD−non-MAFLD patients with higher SUA levels are still at high risk of severe steatosis. This study supports the rationale for SUA being established as another risk factor for metabolic dysfunctions in lean/normal-weight MAFLD.

Effects of daily functional acorn cake consumption on insulin resistance in individuals with obesity or overweight and the metabolic syndrome: a placebo-controlled randomised clinical trial

The metabolic syndrome is a multi-factorial condition and functional foods need more investigation as novel adjunct treatments for this group. This study aimed to determine the effects of daily consumption of a functional acorn cake in conjunction with energy restriction (119.50 kJ) on individuals with overweight or obesity and the metabolic syndrome. In this randomised double-blinded study, eighty-four participants were randomly allocated to either an energy-restricted diet plus two servings (2 × 30 g)/d of functional acorn cake (a cake made of acorn for the intervention group) (FC) (n 42) or an energy-restricted diet plus placebo cake (PC) (n 42). Body composition and biochemical parameters were measured before and after 10 weeks of intervention. Seventy-three participants completed this trial. No differences in loss of body weight, waist circumference, fat mass, fasting blood glucose and blood pressure were shown between two groups. Body weight decreased by 4·2 (sd 1·9) kg and 5·1 (sd 2·8) kg in PC and FC groups, respectively. Compared with PC, the consumption of FC resulted in a significant reduction in serum insulin (P = 0·02), homoeostasis model assessment for insulin resistance (P = 0·02), high-sensitivity C-reactive protein (P = 0·04) and a significant increase in adiponectin concentration (P = 0·04). Although lipid metabolism did not differ among groups, total cholesterol and HDL-cholesterol improved non-significantly in the FC group. Functional acorn cake as an adjunct to energy restriction could possibly improve insulin resistance in individuals with obesity. Further research is needed to elucidate whether functional acorn cake can be used as a preventive strategy for the metabolic syndrome in individuals with obesity.

Relationships among phthalate exposure, oxidative stress, and insulin resistance in young military soldiers: A cumulative risk assessment and mediation approach

BACKGROUND

Epidemiological studies concerning whether oxidative stress mediates phthalate exposure-insulin resistance (IR) associations in young adults are limited. Therefore, we investigated this potential mediation by using a cumulative risk approach involving daily intake (DI) and a hazard index (HI_RfD).

METHODS

The participants were 391 Taiwanese military personnel. This study measured their IR (as homeostatic model assessment of estimated IR [HOMA-IR]), levels of oxidative stress biomarkers (8-hydroxy-2-deoxyguanosine, 8-nitroguanine, 8-iso-prostaglandin F2α, and N-acetyl-S-[tetrahydro-5-hydroxy-2-pentyl-3-furanyl]-L-cysteine [HNE-MA]), the sum of these four biomarkers (ΣOS), and urinary phthalate metabolite concentrations. The HI_RfD was estimated on the basis of urinary levels of phthalate metabolite, and the DI of five phthalates was determined: dimethyl phthalate, benzyl butyl phthalate (BBzP), diethyl phthalate, dibutyl phthalate (DBP), and di (2-ethylhexyl) phthalate (DEHP). Logistic regression models were employed to explore associations among DI, HI_RfD, oxidative stress biomarkers, and HOMA-IR values. The role played by oxidative stress in the phthalate exposure-HOMA-IR association was determined using mediation analysis.

RESULTS

We discovered positive associations between high DI of DBP, BBzP, and DEHP; high HI_RfD; and high ΣOS. High ΣOS and HNE-MA were associated with a higher likelihood of a high HOMA-IR value. Mediation analysis indicated that high ΣOS and HNE-MA were significant mediators of the associations between phthalates and IR.

CONCLUSION

Oxidative stress may partially mediate the phthalate-IR relationship in young adults.

Hepatic Insulin Resistance in Hyperthyroid Rat Liver: Vitamin E Supplementation Highlights a Possible Role of ROS

Thyroid hormones are normally involved in glycaemic control, but their excess can lead to altered glucose metabolism and insulin resistance (IR). Since hyperthyroidism-linked increase in ROS results in tissue oxidative stress that is considered a hallmark of conditions leading to IR, it is conceivable a role of ROS in the onset of IR in hyperthyroidism. To verify this hypothesis, we evaluated the effects of vitamin E on thyroid hormone-induced oxidative damage, insulin resistance, and on gene expression of key molecules involved in IR in the rat liver. The factors involved in oxidative damage, namely the total content of ROS, the mitochondrial production of ROS, the activity of antioxidant enzymes, the in vitro susceptibility to oxidative stress, have been correlated to insulin resistance indices, such as insulin activation of hepatic Akt and plasma level of glucose, insulin and HOMA index. Our results indicate that increased levels of oxidative damage ROS content and production and susceptibility to oxidative damage, parallel increased fasting plasma level of glucose and insulin, reduced activation of Akt and increased activation of JNK. This last result suggests a role for JNK in the insulin resistance induced by hyperthyroidism. Furthermore, the variation of the genes Pparg, Ppara, Cd36 and Slc2a2 could explain, at least in part, the observed metabolic phenotypes.

Selenium and Selenoproteins at the Intersection of Type 2 Diabetes and Thyroid Pathophysiology

Type 2 diabetes (T2D) is considered one of the largest global public-health concerns, affecting approximately more than 400 million individuals worldwide. The pathogenesis of T2D is very complex and, among the modifiable risk factors, selenium (Se) has recently emerged as a determinant of T2D pathogenesis and progression. Selenium is considered an essential element with antioxidant properties, and is incorporated into the selenoproteins involved in the antioxidant response. Furthermore, deiodinases, the enzymes responsible for homeostasis and for controlling the activity of thyroid hormones (THs), contain Se. Given the crucial action of oxidative stress in the onset of insulin resistance (IR) and T2D, and the close connection between THs and glucose metabolism, Se may be involved in these fundamental relationships; it may cover a dual role, both as a protective factor and as a risk factor of T2D, depending on its basal plasma concentration and the individual’s diet intake. In this review we discuss the current evidence (from experimental, observational and randomized clinical studies) on how Se is associated with the occurrence of T2D and its influence on the relationship between thyroid pathophysiology, IR and T2D.

The effect of Madhumeha Kusumakar Rasa - an Ayurved medicine - in insulin resistance

OBJECTIVES

Madhumeha Kusumakar Rasa (MKR) is an Ayurved formulation having a strong pharmacological base for diabetes management. This study aimed to validate MKR's efficacy in dexamethasone-induced insulin resistance (IR).

METHODS

Albino Wistar rats were divided into four groups. Group 1 served as the normal control, Group 2 received dexamethasone 1.5 mg/kg (i.p.), Group 3 received dexamethasone and metformin 200 mg/kg (p.o.), and Group 4 received dexamethasone and MKR 236 mg/kg (p.o.). Animals were evaluated for serum glucose levels and glucose tolerance, serum insulin, Homeostatic model assessment of insulin resistance (HOMA-IR), Homeostatic model assessment of insulin sensitivity (HOMA-IS), fasting glucose to insulin ratio (FGIR), and lipid parameters. Pancreas, liver, and kidneys were evaluated for reduced Glutathione (GSH) and Malondialdehyde (MDA) levels. These tissues were also evaluated for histopathological changes.

RESULTS

MKR showed significant improvement in serum glucose and glucose tolerance, serum insulin and HOMA-IR, HOMA-IS, and FGIR. It also showed a significant improvement in lipid parameters as compared to the dexamethasone-treated group. It prevented depletion of GSH levels and elevation in MDA levels. These effects were supported by histopathological analysis.

CONCLUSIONS

MKR treatment significantly attenuated dexamethasone-induced IR. This study validates the mechanism of the anti-diabetic potential of MKR.

Metabolic Syndrome and Male Fertility: Beyond Heart Consequences of a Complex Cardiometabolic Endocrinopathy

Metabolic syndrome (MetS) is a highly prevalent condition among adult males, affecting up to 41% of men in Europe. It is characterized by the association of obesity, hypertension, and atherogenic dyslipidemia, which lead to premature morbidity and mortality due to cardiovascular disease (CVD). Male infertility is another common condition which accounts for about 50% of cases of couple infertility worldwide. Interestingly, male infertility and MetS shares several risk factors (e.g., smoking, ageing, physical inactivity, and excessive alcohol consumption), leading to reactive oxygen species (ROS) production and increased oxidative stress (OS), and resulting in endothelial dysfunction and altered semen quality. Thus, the present narrative review aims to discuss the pathophysiological mechanisms which link male infertility and MetS and to investigate the latest available evidence on the reproductive consequences of MetS.

Are Inflamed Periodontal Tissues Endogenous Source of Advanced Glycation End-Products (AGEs) in Individuals with and without Diabetes Mellitus? A Systematic Review

Advanced glycation end-products (AGEs) are heterogeneous compounds formed when excess sugars condense with the amino groups of nucleic acids and proteins. Increased AGEs are associated with insulin resistance and poor glycemic control. Recently, inflamed periodontal tissues and certain oral bacteria were observed to increase the local and systemic AGE levels in both normoglycemic and hyperglycemic individuals. Although hyperglycemia induced AGE and its effect on the periodontal tissues is known, periodontitis as an endogenous source of AGE formation is not well explored. Hence, this systematic review is aimed to explore, for the first time, whether inflamed periodontal tissues and periodontal pathogens have the capacity to modulate AGE levels in individuals with or without T2DM and how this affects the glycemic load. Six electronic databases were searched using the following keywords: (Periodontitis OR Periodontal disease OR Periodontal Inflammation) AND (Diabetes mellitus OR Hyperglycemia OR Insulin resistance) AND Advanced glycation end products. The results yielded 1140 articles, of which 13 articles were included for the review. The results showed that the mean AGE levels in gingival crevicular fluid was higher in individuals with diabetes mellitus and periodontitis (521.9 pg/mL) compared to healthy individuals with periodontitis (234.84 pg/mL). The serum AGE levels in normoglycemic subjects having periodontitis was higher compared to those without periodontitis (15.91 ng/mL vs. 6.60 ng/mL). Tannerella forsythia, a common gram-negative anaerobe periodontal pathogen in the oral biofilm, was observed to produce methylglyoxal (precursor of AGE) in the gingival tissues. Increased AGE deposition and activate of AGE receptors was noted in the presence of periodontitis in both normoglycemic and hyperglycemic individuals. Hence, it can be concluded that periodontitis can modulate the local and systemic levels of AGE levels even in absence of hyperglycemia. This explains the bidirectional relationship between periodontitis and development of prediabetes, incident diabetes, poor glycemic control, and insulin resistance.

A case report of CAT gene and HNF1β gene variations in a patient with early-onset diabetes

Complex forms of diabetes are the ultimate common pathway involving multiple genetic variations and multiple environmental factors. Type 2 diabetes (T2DM) is classified as complex diabetes. Varying degrees of insulin deficiency and tissue insulin resistance are two key links to T2DM. The islet β cell dysfunction plays a crucial role in the pathogenesis of T2DM. The decompensation of the islet β cell to insulin resistance is a common mechanism leading to the pathogenesis of T2DM. Available data show that genetic factors mainly affect cell function. At present, a number of susceptibility genes related to T2DM have been reported at home and abroad. In this study, the diabetes-related genes in the case of early-onset diabetes with a significant family history were examined, and our results showed the presence of the intron mutations of catalase (CAT) gene and hepatocyte nuclear factor 1β (HNF1β) gene. The patient enrolled in this study was observed and analyzed, thus, increasing further understanding of the genes associated with diabetes and exploring the pathogenesis of diabetes from the molecular level. This is significant for guiding the prevention, treatment, and prognosis evaluation of diabetes.

Food Insecurity and Cardiometabolic Markers: Results From the Study of Latino Youth

OBJECTIVES

Hispanic/Latino youth bear a disproportionate burden of food insecurity and poor metabolic outcomes, but research linking the two in this diverse population is lacking. We evaluated whether lower household and child food security (FS) were adversely associated with a metabolic syndrome (MetS) composite variable and clinically measured cardiometabolic markers: waist circumference, fasting plasma glucose, triglycerides, high-density lipoprotein cholesterol, and systolic and diastolic blood pressure.

METHODS

This cross-sectional study included 1325 Hispanic/Latino youth aged 8 to 16 years from the Hispanic Community Children's Health Study/Study of Latino Youth, a study of offspring of adults enrolled in the Hispanic Community Health Survey/Study of Latinos. Multivariable regression analyses were used to assess relationships between household FS (high, marginal, low, very low) and child FS (high, marginal, low/very low) status, separately, and our dependent variables, adjusting for participant age, sex, site, parental education, and poverty-income ratio.

RESULTS

For both FS measures, youth in the lowest FS category had significantly lower high-density lipoprotein cholesterol than those with high FS (household FS: -3.17, 95% confidence interval [CI]: -5.65 to -0.70, child FS: -1.81, 95% CI: -3.54 to -0.09). Low/very low versus high child FS was associated with greater fasting plasma glucose (β = 1.37, 95% CI: 0.08 to 2.65), triglycerides (β = 8.68, 95% CI: 1.75 to 15.61), and MetS expected log counts (β = 2.12, 95% CI: 0.02 to 0.45).

CONCLUSIONS

Lower FS is associated with unfavorable MetS-relevant cardiometabolic markers in Hispanic/Latino youth. These findings also support the use of a child-level versus a household-level measure to capture the health implications of food insecurity in this population.

Oxidative RNA Damage in the Pathogenesis and Treatment of Type 2 Diabetes

Excessive production of free radicals can induce cellular damage, which is associated with many diseases. RNA is more susceptible to oxidative damage than DNA due to its single-stranded structure, and lack of protective proteins. Yet, oxidative damage to RNAs received little attention. Accumulating evidence reveals that oxidized RNAs may be dysfunctional and play fundamental role in the occurrence and development of type 2 diabetes (T2D) and its complications. Oxidized guanine nucleoside, 8-oxo-7, 8-dihydroguanine (8-oxoGuo) is a biomarker of RNA oxidation that could be associated with prognosis in patients with T2D. Nowadays, some clinical trials used antioxidants for the treatment of T2D, though the pharmacological effects remained unclear. In this review, we overview the cellular handling mechanisms and the consequences of the oxidative RNA damage for the better understanding of pathogenesis of T2D and may provide new insights to better therapeutic strategy.

Perspectives in liver redox imbalance: Toxicological and pharmacological aspects underlying iron overloading, nonalcoholic fatty liver disease, and thyroid hormone action

Oxidative stress is an imbalance between oxidants and antioxidants in favor of the oxidants, leading to a disruption of redox signaling and control, and/or molecular damage altering cellular functions. This redox imbalance may trigger different responses depending on the antioxidant potential of a given cell, the level of reactive oxygen/nitrogen species (ROS/RNS) attained and the time of exposure, with protective effects being induced at low ROS/RNS levels in acute or short-term conditions, and harmful effects after high ROS/RNS exposure in prolonged situations. Relevant conditions underlying liver redox imbalance include iron overload associated with ROS production via Fenton chemistry and the magnitude of the iron labile pool achieved, with low iron exposure inducing protective effects related to nuclear factor-κB, signal transducer and activation of transcription 3, and nuclear factor erythroid-related factor 2 (Nrf2) activation and upregulation of ferritin, hepcidin, acute-phase response and antioxidant components, whereas high iron exposure causes drastic oxidation of biomolecules, mitochondrial dysfunction, and cell death due to necrosis, apoptosis and/or ferroptosis. Redox imbalance in nonalcoholic fatty liver disease (NAFLD) is related to polyunsaturated fatty acid depletion, lipogenic factor sterol regulatory element-binding protein-1c upregulation, fatty acid oxidation-dependent peroxisome proliferator-activated receptor-α downregulation, low antioxidant factor Nrf2 and insulin resistance, a phenomenon that is exacerbated in nonalcoholic steatohepatitis triggering an inflammatory response. Thyroid hormone (T₃ ) administration determines liver preconditioning against ischemia-reperfusion injury due to the redox activation of several transcription factors, AMP-activated protein kinase, unfolded protein response and autophagy. High grade liver redox imbalance occurring in severe iron overload is adequately handled by iron chelation, however, that underlying NAFLD/NASH is currently under study in several Phase II and Phase III trials.