TNFα Mediates the Interaction of Telomeres and Mitochondria Induced by Hyperglycemia: A Rural Community-Based Cross-Sectional Study

Joint Effects of Exercise and Ramadan Fasting on Telomere Length: Implications for Cellular Aging

Aging is a fundamental biological process that progressively impairs the functionality of the bodily systems, leading to an increased risk of diseases. Telomere length is one of the most often used biomarkers of aging. Recent research has focused on developing interventions to mitigate the effects of aging and improve the quality of life. The objective of this study was to investigate the combined effect of exercise and Ramadan fasting on telomere length. Twenty-nine young, non-obese, healthy females were randomized into two groups: the control group underwent a 4-week exercise training program, and the second group underwent a 4-week exercise training program while fasting during Ramadan. Blood samples were collected, and measurements of clinical traits, cytokines, oxidative stress, and telomere length were performed before and after intervention. Telomere length increased significantly from baseline in the exercise-while-fasting group, but showed no significant change in the exercise control group. This increase was accompanied by a reduction in TNF-α, among other cytokines. Additionally, a significant positive correlation was observed between the mean change in telomere length and HDL in the exercise-while-fasting group only. This study is the first to report an increase in telomere length after combining Ramadan fasting with training, suggesting that exercising while fasting may be an effective tool for slowing down the aging rate. Further studies using larger and more diverse cohorts are warranted.

Advanced glycation end products, leukocyte telomere length, and mitochondrial DNA copy number in patients with coronary artery disease and alterations of glucose homeostasis: From the GENOCOR study

BACKGROUND AND AIM

Alterations of glucose homeostasis can increase advanced glycation end products (AGEs) that exacerbate vascular inflammatory disease and may increase vascular senescence and aging. This study examined the relationships between carboxymethyl-lysine (CML) and soluble receptor for AGEs (sRAGE) with leukocyte telomere length (LTL) and mitochondrial DNA copy number (mtDNAcn), as cell aging biomarkers, in patients with established coronary artery disease (CAD).

METHODS AND RESULTS

We studied 459 patients with CAD further categorized as having normal glucose homeostasis (NG, n = 253), pre-diabetes (preT2D, n = 85), or diabetes (T2D, n = 121). All patients were followed up for the occurrence of major adverse cardiovascular events (MACEs). Plasma concentrations of sRAGE and CML were measured by ELISA. mtDNAcn and LTL were measured by qRT-PCR. CML levels were significantly higher in patients with preT2D (p < 0.007) or T2D (p < 0.003) compared with those with NG. mtDNAcn resulted lower in T2D vs preT2D (p = 0.04). At multivariate Cox proportional hazard analysis, short LTL (HR: 2.89; 95% CI: 1.11-10.1; p = 0.04) and high levels of sRAGE (HR: 2.20; 95% CI: 1.01-5.14; p = 0.04) were associated with an increased risk for MACEs in patients with preT2D and T2D, respectively. T2D patients with both short LTL and high sRAGE levels had the highest risk of MACEs (HR: 3.11; 95% CI: 1.11-9.92; p = 0.04).

CONCLUSIONS

High levels of sRAGE and short LTL were associated with an increased risk of MACEs, especially in patients with diabetes, supporting the usefulness of both biomarkers of glycemic impairment and aging in predicting cardiovascular outcomes in patients with CAD.

Telomeres and Mitochondrial Metabolism: Implications for Cellular Senescence and Age-related Diseases

Cellular senescence is an irreversible cell arrest process, which is determined by a variety of complicated mechanisms, including telomere attrition, mitochondrial dysfunction, metabolic disorders, loss of protein homeostasis, epigenetic changes, etc. Cellular senescence is causally related to the occurrence and development of age-related disease. The elderly is liable to suffer from disorders such as neurodegenerative diseases, cancer, and diabetes. Therefore, it is increasingly imperative to explore specific countermeasures for the treatment of age-related diseases. Numerous studies on humans and mice emphasize the significance of metabolic imbalance caused by short telomeres and mitochondrial damages in the onset of age-related diseases. Although the experimental data are relatively independent, more and more evidences have shown that there is mutual crosstalk between telomeres and mitochondrial metabolism in the process of cellular senescence. This review systematically discusses the relationship between telomere length, mitochondrial metabolic disorder, as well as their underlying mechanisms for cellular senescence and age-related diseases. Future studies on telomere and mitochondrial metabolism may shed light on potential therapeutic strategies for age-related diseases. Graphical Abstract The characteristics of cellular senescence mainly include mitochondrial dysfunction and telomere attrition. Mitochondrial dysfunction will cause mitochondrial metabolic disorders, including decreased ATP production, increased ROS production, as well as enhanced cellular apoptosis. While oxidative stress reaction to produce ROS, leads to DNA damage, and eventually influences telomere length. Under the stimulation of oxidative stress, telomerase catalytic subunit TERT mainly plays an inhibitory role on oxidative stress, reduces the production of ROS and protects telomere function. Concurrently, mitochondrial dysfunction and telomere attrition eventually induce a range of age-related diseases, such as T2DM, osteoporosis, AD, etc. :increase; :reduce;⟝:inhibition.

High Hemoglobin Glycation Index Is Associated With Telomere Attrition Independent of HbA1c, Mediated by TNFα

CONTEXT

The hemoglobin glycation index (HGI) is correlated with metabolic diseases and inflammation. Whether the HGI is associated with the aging process and how inflammation and oxidative stress affect the relationship remain unclear.

OBJECTIVE

We aimed to analyze links between the HGI and aging biomarkers, and to explore a potential role of inflammation and oxidative stress in the correlations.

METHODS

A cross-sectional study of 434 subjects with different glucose intolerances in a rural community was enrolled. The HGI was calculated as the difference between the measured and predicted hemoglobin A1c (HbA1c). The population was categorized into tertiles of the HGI. Telomere length (LTL) and mitochondrial DNA copy number (mtDNAcn) determined by polymerase chain reaction assay. Tumor necrosis factor (TNF) α and interleukin (IL) 6, 8-oxo-2'-deoxyguanosine (8-oxo-dG), superoxide dismutase (SOD) activities, and glutathione reductase (GR) were measured.

RESULTS

Participants in the high HGI group were older and reported a shorter LTL, higher levels of TNFα, SOD activities, and HbA1c. Correlation analyses demonstrated that HGI was correlated with LTL (r = -0.25, P < .001) and TNFα (r = 0.19, P < .001) regardless of HbA1c levels. No relationship was found between HGI and mtDNAcn. HGI (β = -0.238, 95% CI -0.430, -0.046, P = .015) and TNFα (β = -0.02, 95% CI -0.030, -0.014, P < .001) were proved to be correlated with LTL independently, using multiple linear regression analysis. Ordinal logistic regression models showed that compared with subjects the high HGI group, the possibilities of a higher-level LTL was 5.29-fold in the low HGI group (OR 5.29, 95% CI (2.45, 11.41), P < .001), 2.41-fold in the moderate HGI group (OR 2.41, 95% CI 1.35, 4.30, P = .003) after controlling for confounding variables. Mediation analyses indicated that TNFα accounted for 30.39% of the effects of the HGI on LTL.

CONCLUSION

HGI was negatively related to telomere attrition, independent of HbA1c. TNFα acted as a mediator of the relationship between HGI and LTL.