Insulin and aging

A simplified longitudinal model for the development of Type 2 Diabetes Mellitus

Obesity and diabetes are a progressively more and more deleterious hallmark of modern, well fed societies. In order to study the potential impact of strategies designed to obviate the pathological consequences of detrimental lifestyles, a model for the development of Type 2 diabetes geared towards large population simulations would be useful. The present work introduces such a model, representing in simplified fashion the interplay between average glycemia, average insulinemia and functional beta-cell mass, and incorporating the effects of excess food intake or, conversely, of physical activity levels. Qualitative properties of the model are formally established and simulations are shown as examples of its use.

Maternal Obesity and Neonatal Metabolic Health: Insights Into Insulin Resistance

Background Maternal obesity is a global health concern that leads to metabolic alterations in the offspring, making them vulnerable to metabolic disorders in adulthood. Early identification of such neonates would provide opportunities to positively alter modifiable risk factors for non-communicable diseases (NCDs) to prevent their occurrence later in life. Objectives This study aimed to assess and contrast insulin resistance (IR) levels in neonates born to mothers with obesity and those born to healthy, non-obese mothers.  Methods This case-control study was conducted after approval from the institutional ethics committee. A total of 98 healthy, non-obese pregnant females were included in Group 1, and 68 obese pregnant females were included in Group 2. The participants were followed up until delivery and cord blood samples were collected after delivery. Neonatal glucose and insulin concentrations were estimated, and indices of IR such as homeostatic model assessment for insulin resistance (HOMA-IR), quantitative insulin-sensitivity check index (QUICKI), and glucose-to-insulin ratio were calculated. Neonatal IR indices and anthropometric measurements were compared between the groups using the Z test and correlated with the maternal pre-pregnancy body mass index (BMI) using Pearson's correlation. Additionally, Pearson's correlations were examined between neonatal IR indices and anthropometric measurements. Statistical significance was set at p <0.05. Results Neonates in Group 2 exhibited significantly higher anthropometric parameters and IR indices than those in Group 1. A statistically significant positive correlation was identified between maternal pre-pregnancy BMI, neonatal anthropometric parameters, and IR. Furthermore, a statistically significant positive correlation was observed between neonatal IR and the anthropometric parameters. Conclusion Neonates born to obese mothers exhibited higher anthropometric parameters and insulin resistance than those born to non-obese, healthy mothers. Assessment of IR at birth can help identify neonates who are at higher risk of developing NCD in later life. Timely promotion of a healthy lifestyle can reduce the occurrence of NCDs in later life.

Global trends in burden of type 2 diabetes attributable to physical inactivity across 204 countries and territories, 1990-2019

Background

To promote a comprehensive understanding of global trends and burden of type 2 diabetes attributable to physical inactivity.

Methods

We utilized data regarding mortality, disability-adjusted life years (DALYs), as well as age-standardized mortality rates (ASMR) and DALYs rates (ASDR) derived from the global burden of disease study 2019 to evaluate the impact of physical inactivity on the prevalence of type 2 diabetes in 204 countries and territories over the period from 1990 to 2019. This method facilitated the analysis of the diabetes burden across different ages, genders, and regions. To determine the long-term progression of type 2 diabetes prevalence, we computed the estimated annual percentage change (EAPC) in burden rates.

Results

Globally, the number of deaths and DALYs from type 2 diabetes due to physical inactivity more than doubled between 1990 and 2019. Concurrently, there was an increase in the ASMR and ASDR, with EAPC of 0.26 (95% CI: 0.13-0.39) and 0.84 (95% CI: 0.78-0.89), respectively. As of 2019, the global ASMR and ASDR for physical inactivity stood at 1.6 (95% UI: 0.8-2.7) per 100 000 and 55.9 (95% UI: 27.2-97.6) per 100 000, respectively. Notable disparities were observed in the type 2 diabetes burden associated with physical inactivity worldwide, with higher sociodemographic index (SDI) countries experiencing lower ASDR and ASMR compared to lower SDI countries. Initially, females exhibited higher ASMR and ASDR than males, but this gender disparity in ASMR and ASDR has lessened in recent years. The mortality and DALYs rates associated with physical inactivity exhibit an inverted V-shaped pattern across various age groups, predominantly affecting the elderly population.

Conclusion

Between 1990 and 2019, there was a marked rise in the worldwide burden of type 2 diabetes associated with physical inactivity, underscoring the role of physical inactivity as a key changeable risk factor in the global landscape of this disease. This necessitates additional research to explore the variables contributing to the varying levels of disease burden across different countries and between sexes. Furthermore, it calls for the formulation of public health policies aimed at guiding prevention tactics, promoting early detection, and enhancing the management of type 2 diabetes.

Western diet consumption by host vertebrate promotes altered gene expression on Aedes aegypti reducing its lifespan and increasing fertility following blood feeding

BACKGROUND

The high prevalence of metabolic syndrome in low- and middle-income countries is linked to an increase in Western diet consumption, characterized by a high intake of processed foods, which impacts the levels of blood sugar and lipids, hormones, and cytokines. Hematophagous insect vectors, such as the yellow fever mosquito Aedes aegypti, rely on blood meals for reproduction and development and are therefore exposed to the components of blood plasma. However, the impact of the alteration of blood composition due to malnutrition and metabolic conditions on mosquito biology remains understudied.

METHODS

In this study, we investigated the impact of whole-blood alterations resulting from a Western-type diet on the biology of Ae. aegypti. We kept C57Bl6/J mice on a high-fat, high-sucrose (HFHS) diet for 20 weeks and followed biological parameters, including plasma insulin and lipid levels, insulin tolerance, and weight gain, to validate the development of metabolic syndrome. We further allowed Ae. aegypti mosquitoes to feed on mice and tracked how altered host blood composition modulated parameters of vector capacity.

RESULTS

Our findings identified that HFHS-fed mice resulted in reduced mosquito longevity and increased fecundity upon mosquito feeding, which correlated with alteration in the gene expression profile of nutrient sensing and physiological and metabolic markers as studied up to several days after blood ingestion.

CONCLUSIONS

Our study provides new insights into the overall effect of alterations of blood components on mosquito biology and its implications for the transmission of infectious diseases in conditions where the frequency of Western diet-induced metabolic syndromes is becoming more frequent. These findings highlight the importance of addressing metabolic health to further understand the spread of mosquito-borne illnesses in endemic areas.

The Role of Cdc42 in the Insulin and Leptin Pathways Contributing to the Development of Age-Related Obesity

Age-related obesity significantly increases the risk of chronic diseases such as type 2 diabetes, cardiovascular diseases, hypertension, and certain cancers. The insulin-leptin axis is crucial in understanding metabolic disturbances associated with age-related obesity. Rho GTPase Cdc42 is a member of the Rho family of GTPases that participates in many cellular processes including, but not limited to, regulation of actin cytoskeleton, vesicle trafficking, cell polarity, morphology, proliferation, motility, and migration. Cdc42 functions as an integral part of regulating insulin secretion and aging. Some novel roles for Cdc42 have also been recently identified in maintaining glucose metabolism, where Cdc42 is involved in controlling blood glucose levels in metabolically active tissues, including skeletal muscle, adipose tissue, pancreas, etc., which puts this protein in line with other critical regulators of glucose metabolism. Importantly, Cdc42 plays a vital role in cellular processes associated with the insulin and leptin signaling pathways, which are integral elements involved in obesity development if misregulated. Additionally, a change in Cdc42 activity may affect senescence, thus contributing to disorders associated with aging. This review explores the complex relationships among age-associated obesity, the insulin-leptin axis, and the Cdc42 signaling pathway. This article sheds light on the vast molecular web that supports metabolic dysregulation in aging people. In addition, it also discusses the potential therapeutic implications of the Cdc42 pathway to mitigate obesity since some new data suggest that inhibition of Cdc42 using antidiabetic drugs or antioxidants may promote weight loss in overweight or obese patients.

Elevated temperature decreases cardiovascular toxicity of nanoplastics but adds to their lethality: A case study during zebrafish (Danio rerio) development

To highlight the key role of global warming on the toxicity of contaminants, the cardiovascular toxicity of nanoparticles (NPs) was estimated in developing zebrafish (Danio rerio) at different exposure temperatures, and the toxicity mechanisms were explored via multi-omic analyses. Polystyrene NPs (50 nm) at 0.1 mg·L^-1 entered zebrafish embryos at 24 h post-fertilization and caused cardiovascular toxicity in the developing zebrafish at 27 ℃. This was explained by the down-regulation of the branched-chain amino acid and insulin signaling pathways owing to induced oxidative stress. Elevated exposure temperatures promoted the accumulation of NPs in developing zebrafish, increased the levels of oxidative stress and enhanced the oxidative phosphorylation rate in mitochondria, thus resulting in an additive effect on the mortality of zebrafish larvae. Notably, elevated exposure temperatures reduced the cardiovascular toxicity of NPs, as the effective concentration of NPs for inhibiting embryonic heartbeat rate increased from 0.1 mg·L^-1 at 27 ℃ to 1.0 mg·L^-1 at 30 ℃. Experiments of transgenic zebrafish Tg(myl7:GFP) and multi-omic analyses revealed that elevated temperatures enhanced the myocardial contractility of larvae, thus reducing the cardiovascular toxicity of NPs. However, the health risks of enhanced myocardial contraction caused by NP exposure at elevated temperatures requires further consideration.

Deficiency of S100 calcium binding protein A9 attenuates vascular dysfunction in aged mice

BACKGROUND

S100 calcium-binding protein A9 (S100A9) is a danger-associated molecular pattern molecule that mediates the inflammatory response. Inflammation is essential in aging-related cardiovascular diseases. However, less is known regarding the role of S100A9 in vascular aging.

METHODS

S100A9 null mice were used to investigate the role of S100A9 in aging-related pathologies. Artery rings were used to measure the functional characteristics of vascular with a pressurized myograph. Telomere length, Sirtuin activity, oxidative stress, and endothelial nitric oxide synthetase (eNOS) activity were used to elevate vascular senescence. Intraperitoneal glucose tolerance (IPGTT) and insulin sensitivity test (IST) were employed to investigate the effects of S100A9 on insulin resistance. Inflammation response was reflected by the concentration of inflammatory cytokines. The Toll-like receptor 4 (TLR4) and receptor for advanced glycation end products (RAGE) inhibitors were used to identify the downstream molecular mechanisms of S100A9 in aging-induced senescence in endothelial cells.

RESULTS

S100A9 expression in vascular increased with aging in mice and humans. Deficiency of S100A9 alleviated vascular senescence in aged mice, as evidenced by increased telomere length, Sirtuin activity, and eNOS activity. Meanwhile, S100A9 knockout improved endothelium-dependent vasodilatation and endothelial continuity in aged mice. Moreover, the increased insulin resistance, oxidative stress, and inflammation were mitigated by S100A9 deletion in aged mice. In vitro, S100A9 induced senescence in endothelial cells, and that effect was blunted by TLR4 but not RAGE inhibitors.

CONCLUSION

The present study suggested that S100A9 may contribute to aging-related pathologies and endothelial dysfunction via the TLR4 pathway. Therefore, targeting S100A9/TLR4 signaling pathway may represent a crucial therapeutic strategy to prevent age-related cardiovascular diseases.

Endocannabinoid System Components of the Female Mouse Reproductive Tract Are Modulated during Reproductive Aging

The endocannabinoid (eCB) system has gained ground as a key modulator of several female fertility-related processes, under physiological/pathological conditions. Nevertheless, its modulation during reproductive aging remains unclear. This study aimed to investigate the expression levels of the main receptors (cannabinoid receptor 1,CB₁; cannabinoid receptor 2, CB₂; G-protein coupled receptor, GPR55; and transient receptor potential vanilloid type 1 channel, TRPV1) and metabolic enzymes (N-acylphosphatidylethanolamine phospholipase D, NAPE-PLD; fatty acid amide hydrolase, FAAH; monoacylglycerol lipase, MAGL; and diacylglycerol lipase, DAGL-α and -β) of this system in the ovaries, oviducts, and uteri of mice at prepubertal, adult, late reproductive, and post-reproductive stages through quantitative ELISA and immunohistochemistry. The ELISA showed that among the receptors, TRPV1 had the highest expression and significantly increased during aging. Among the enzymes, NAPE-PLD, FAAH, and DAGL-β were the most expressed in these organs at all ages, and increased age-dependently. Immunohistochemistry revealed that, regardless of age, NAPE-PLD and FAAH were mainly found in the epithelial cells facing the lumen of the oviduct and uteri. Moreover, in ovaries, NAPE-PLD was predominant in the granulosa cells, while FAAH was sparse in the stromal compartment. Of note, the age-dependent increase in TRPV1 and DAGL-β could be indicative of increased inflammation, while that of NAPE-PLD and FAAH could suggest the need to tightly control the levels of the eCB anandamide at late reproductive age. These findings offer new insights into the role of the eCB system in female reproduction, with potential for therapeutic exploitation.

Metabolic landscape in cardiac aging: insights into molecular biology and therapeutic implications

Cardiac aging is evident by a reduction in function which subsequently contributes to heart failure. The metabolic microenvironment has been identified as a hallmark of malignancy, but recent studies have shed light on its role in cardiovascular diseases (CVDs). Various metabolic pathways in cardiomyocytes and noncardiomyocytes determine cellular senescence in the aging heart. Metabolic alteration is a common process throughout cardiac degeneration. Importantly, the involvement of cellular senescence in cardiac injuries, including heart failure and myocardial ischemia and infarction, has been reported. However, metabolic complexity among human aging hearts hinders the development of strategies that targets metabolic susceptibility. Advances over the past decade have linked cellular senescence and function with their metabolic reprogramming pathway in cardiac aging, including autophagy, oxidative stress, epigenetic modifications, chronic inflammation, and myocyte systolic phenotype regulation. In addition, metabolic status is involved in crucial aspects of myocardial biology, from fibrosis to hypertrophy and chronic inflammation. However, further elucidation of the metabolism involvement in cardiac degeneration is still needed. Thus, deciphering the mechanisms underlying how metabolic reprogramming impacts cardiac aging is thought to contribute to the novel interventions to protect or even restore cardiac function in aging hearts. Here, we summarize emerging concepts about metabolic landscapes of cardiac aging, with specific focuses on why metabolic profile alters during cardiac degeneration and how we could utilize the current knowledge to improve the management of cardiac aging.

Changes in Pancreatic Senescence Mediate Pancreatic Diseases

In recent years, there has been a significant increase in age-related diseases due to the improvement in life expectancy worldwide. The pancreas undergoes various morphological and pathological changes with aging, such as pancreatic atrophy, fatty degeneration, fibrosis, inflammatory cell infiltration, and exocrine pancreatic metaplasia. Meanwhile, these may predispose the individuals to aging-related diseases, such as diabetes, dyspepsia, pancreatic ductal adenocarcinoma, and pancreatitis, as the endocrine and exocrine functions of the pancreas are significantly affected by aging. Pancreatic senescence is associated with various underlying factors including genetic damage, DNA methylation, endoplasmic reticulum (ER) stress, mitochondrial dysfunction, and inflammation. This paper reviews the alternations of morphologies and functions in the aging pancreas, especially β-cells, closely related to insulin secretion. Finally, we summarize the mechanisms of pancreatic senescence to provide potential targets for treating pancreatic aging-related diseases.

The impact of aging and physical training on angiogenesis in the musculoskeletal system

Angiogenesis is the physiological process of capillary growth. It is strictly regulated by the balanced activity of agents that promote the formation of capillaries (pro-angiogenic factors) on the one hand and inhibit their growth on the other hand (anti-angiogenic factors). Capillary rarefaction and insufficient angiogenesis are some of the main causes that limit blood flow during aging, whereas physical training is a potent non-pharmacological method to intensify capillary growth in the musculoskeletal system. The main purpose of this study is to present the current state of knowledge concerning the key signalling molecules implicated in the regulation of skeletal muscle and bone angiogenesis during aging and physical training.

Remnant cholesterol for the detection of glucose metabolic states in patients with coronary heart disease angina pectoris

BACKGROUND

This study aimed to evaluate the relationship between remnant cholesterol (RC) and glucose metabolic states in coronary heart disease (CHD) patients with angina pectoris.

METHODS

This study collected data from 11,557 CHD patients with angina pectoris aged 35-75 years in Tianjin, China. Participants were divided into normal glucose regulation (NGR), prediabetes (Pre-DM) and diabetes mellitus (DM) groups according to glucose metabolic states. Linear regression analysis was used to explore the relationship between glucose metabolism [fasting blood glucose (FBG) and glycated hemoglobin (HbA1c)] and RC levels. Logistic regression was performed to analyze the relationship between RC levels and glucose metabolic states.

RESULTS

Among all participants, 5883 (50.9%) had a DM state and 4034 (34.9%) had a Pre-DM state. FBG levels and HbA1c levels were positively related with RC in all patients (P < 0.001). NGR was used as a reference, multi-adjusted model showing that RC level was significantly associated with Pre-DM [Odds ratio (OR): 1.37; 95% confidence interval (CI) 1.19-1.56; P < 0.001] and DM state (OR:1.47; 95% CI 1.29-1.67; P < 0.001). When considering RC as categorical variables (tertiles), using T1 as a reference, T3 had the strongest relationship between RC levels and Pre-DM and DM state in univariate model and multivariate model. In the stratified analyses, the association between RC levels and pre-DM and DM in women was higher than that in men, and the elderly patients was higher than in the middle-aged patients.

CONCLUSION

The study demonstrated a significant association between RC levels and pre-DM and DM state among CHD patients with angina pectoris, and the relationship was stronger in women and elderly patients.

Resistance Training Improves Beta Cell Glucose Sensing and Survival in Diabetic Models

Resistance training increases insulin secretion and beta cell function in healthy mice. Here, we explored the effects of resistance training on beta cell glucose sensing and survival by using in vitro and in vivo diabetic models. A pancreatic beta cell line (INS-1E), incubated with serum from trained mice, displayed increased insulin secretion, which could be linked with increased expression of glucose transporter 2 (GLUT2) and glucokinase (GCK). When cells were exposed to pro-inflammatory cytokines (in vitro type 1 diabetes), trained serum preserved both insulin secretion and GCK expression, reduced expression of proteins related to apoptotic pathways, and also protected cells from cytokine-induced apoptosis. Using 8-week-old C57BL/6 mice, turned diabetic by multiple low doses of streptozotocin, we observed that resistance training increased muscle mass and fat deposition, reduced fasting and fed glycemia, and improved glucose tolerance. These findings may be explained by the increased fasting and fed insulinemia, along with increased beta cell mass and beta cell number per islet, observed in diabetic-trained mice compared to diabetic sedentary mice. In conclusion, we believe that resistance training stimulates the release of humoral factors which can turn beta cells more resistant to harmful conditions and improve their response to a glucose stimulus.

Factors correlated with targeted prevention for prediabetes classified by impaired fasting glucose, impaired glucose tolerance, and elevated HbA1c: A population-based longitudinal study

BACKGROUND

There is still controversy surrounding the precise characterization of prediabetic population. We aim to identify and examine factors of demographic, behavioral, clinical, and biochemical characteristics, and obesity indicators (anthropometric characteristics and anthropometric prediction equation) for prediabetes according to different definition criteria of the American Diabetes Association (ADA) in the Chinese population.

METHODS

A longitudinal study consisted of baseline survey and two follow-ups was conducted, and a pooled data were analyzed. Prediabetes was defined as either impaired fasting glucose (IFG), impaired glucose tolerance (IGT), or elevated glycosylated hemoglobin (HbA1c) according to the ADA criteria. Robust generalized estimating equation models were used.

RESULTS

A total of 5,713 (58.42%) observations were prediabetes (IGT, 38.07%; IGT, 26.51%; elevated HbA1c, 23.45%); 9.66% prediabetes fulfilled all the three ADA criteria. Among demographic characteristics, higher age was more evident in elevated HbA1c [adjusted OR (aOR)=2.85]. Female individuals were less likely to have IFG (aOR=0.70) and more likely to suffer from IGT than male individuals (aOR=1.41). Several inconsistency correlations of biochemical characteristics and obesity indicators were detected by prediabetes criteria. Body adiposity estimator exhibited strong association with prediabetes (D10: aOR=4.05). For IFG and elevated HbA1c, the odds of predicted lean body mass exceed other indicators (D10: aOR=3.34; aOR=3.64). For IGT, predicted percent fat presented the highest odds (D10: aOR=6.58).

CONCLUSION

Some correlated factors of prediabetes under different criteria differed, and obesity indicators were easily measured for target identification. Our findings could be used for targeted intervention to optimize preventions to mitigate the obviously increased prevalence of diabetes.