Metabolomics reveals a link between homocysteine and lipid metabolism and leukocyte telomere length: the ENGAGE consortium

Investigating the association between blood metabolites and telomere length: A mendelian randomization study

BACKGROUND

Telomere length refers to the protective cap at the end of chromosomes, and it plays a crucial role in many diseases. The objective of this study is to explore the relationship between blood metabolites and telomere length, aiming to identify novel biological factors that influence telomere length.

METHODS

In this study, we extracted genome-wide association study (GWAS) data for blood metabolites from a sample of 7824 Europeans. Additionally, GWAS data for telomere length were obtained from the Open GWAS database (GWAS ID: ieu-b-4879). The primary analysis of this study utilized the random inverse variance weighted (IVW) method. Complementary analyses were also conducted using the MR-Egger and weighted median approaches. Sensitivity analyses were performed to assess the robustness of the findings. These included the Cochran Q test, MR-Egger intercept test, MR-PRESSO, and leave-one-out analysis. To investigate the possibility of reverse causation, reverse MR analysis was conducted. Additionally, multivariable MR was utilized to evaluate the direct effect of metabolites on telomere length.

RESULTS

The results suggested a potential association between 15-methylpalmitate, taurocholate, levulinate, and X-12712 and telomere length. MVMR analysis further showed that 15-methylpalmitate, taurocholate, and levulinate can directly influence telomere length, regardless of other metabolites.

CONCLUSIONS

This study suggests that 15-methylpalmitate, taurocholate, and levulinate are likely factors correlated with telomere length. These findings will contribute to the development of strategies for protecting telomeres, preventing related diseases, and establishing a new biological foundation for achieving healthy aging.

Persistent dyslipidemia increases the longitudinal changes in telomere length

BACKGROUND AND AIMS

Leukocyte telomere length (LTL) as a 'biological clock' of aging is closely related to human health, its association with an aging-related disease, dyslipidemia, has been less studied and mainly focused on cross-sectional investigations.

METHODS

Two rounds of information and blood collections were conducted on a cohort of 1624 individuals residing in rural Ningxia, located in northwest China, with an average time gap of 9.8 years. The relative telomere length (RTL) of peripheral blood leukocytes was assessed using real-time quantitative PCR. To investigate the association between dyslipidemia, blood lipid levels, and alterations in RTL, multiple linear regression and generalized linear models were employed.

RESULTS

After conducting the follow-up analysis, it was observed that 83.3% of the participants in the study exhibited a reduction in telomere length, while 16.7% experienced an increase in telomere length. The results suggested that dyslipidemia at baseline or follow-up may increase longitudinal changes in telomere length, but it was more significant in the healthy group, especially in those aged ≥ 60 years. Furthermore, HDL-C levels in baseline and follow-up were found to be associated with longitudinal changes in telomere length, and lower HDL-C levels may be associated with increased longitudinal changes in telomere length.

CONCLUSIONS

The change in telomere length is correlated with dyslipidemia and its lipid indicators especially HDL-C. Persistent dyslipidemia and a reduction in HDL-C levels may be associated with elevated longitudinal fluctuations in telomere length.

Lipids and the hallmarks of ageing: From pathology to interventions

Lipids are critical structural and functional architects of cellular homeostasis. Change in systemic lipid profile is a clinical indicator of underlying metabolic pathologies, and emerging evidence is now defining novel roles of lipids in modulating organismal ageing. Characteristic alterations in lipid metabolism correlate with age, and impaired systemic lipid profile can also accelerate the development of ageing phenotype. The present work provides a comprehensive review of the extent of lipids as regulators of the modern hallmarks of ageing viz., cellular senescence, chronic inflammation, gut dysbiosis, telomere attrition, genome instability, proteostasis and autophagy, epigenetic alterations, and stem cells dysfunctions. Current evidence on the modulation of each of these hallmarks has been discussed with emphasis on inherent age-dependent deficiencies in lipid metabolism as well as exogenous lipid changes. There appears to be sufficient evidence to consider impaired lipid metabolism as key driver of the ageing process although much of knowledge is yet fragmented. Considering dietary lipids, the type and quantity of lipids in the diet is a significant, but often overlooked determinant that governs the effects of lipids on ageing. Further research using integrative approaches amidst the known aging hallmarks is highly desirable for understanding the therapeutics of lipids associated with ageing.

Integrative metabolomics science in Alzheimer's disease: Relevance and future perspectives

Alzheimer's disease (AD) is determined by various pathophysiological mechanisms starting 10-25 years before the onset of clinical symptoms. As multiple functionally interconnected molecular/cellular pathways appear disrupted in AD, the exploitation of high-throughput unbiased omics sciences is critical to elucidating the precise pathogenesis of AD. Among different omics, metabolomics is a fast-growing discipline allowing for the simultaneous detection and quantification of hundreds/thousands of perturbed metabolites in tissues or biofluids, reproducing the fluctuations of multiple networks affected by a disease. Here, we seek to critically depict the main metabolomics methodologies with the aim of identifying new potential AD biomarkers and further elucidating AD pathophysiological mechanisms. From a systems biology perspective, as metabolic alterations can occur before the development of clinical signs, metabolomics - coupled with existing accessible biomarkers used for AD screening and diagnosis - can support early disease diagnosis and help develop individualized treatment plans. Presently, the majority of metabolomic analyses emphasized that lipid metabolism is the most consistently altered pathway in AD pathogenesis. The possibility that metabolomics may reveal crucial steps in AD pathogenesis is undermined by the difficulty in discriminating between the causal or epiphenomenal or compensatory nature of metabolic findings.

Low Magnesium in Conjunction with High Homocysteine and Less Sleep Accelerates Telomere Attrition in Healthy Elderly Australian

The relationship between sleep and micronutrients, including magnesium, is implicated in its regulation. The effects of low magnesium and other micronutrients on sleep disruption and telomere loss are not well understood. The present study was carried out in 172 healthy elderly subjects from South Australia. Plasma micronutrients including magnesium were measured. Each participant provided information about their sleep hours (<7 h or ≥7 h). Lymphocyte telomere length (TL) was measured by real-time qPCR assay. Plasma magnesium level was significantly low in subjects who sleep less than 7 h (p = 0.0002). TL was significantly shorter in people who are low in magnesium and sleep less than 7 h (p = 0.01). Plasma homocysteine (Hcy) is negatively associated with magnesium (r = −0.299; p < 0.0001). There is a significant interaction effect of magnesium and Hcy on sleep duration (p = 0.04) and TL (p = 0.003). Our results suggest that inadequate magnesium levels have an adverse impact on sleep and telomere attrition rate in cognitively normal elderly people, and this may be exacerbated by low levels of vitamin B12 and folate that elevate Hcy concentration.

Lipidomics profiling of biological aging in American Indians: the Strong Heart Family Study

Telomeres shorten with age and shorter leukocyte telomere length (LTL) has been associated with various age-related diseases. Thus, LTL has been considered a biomarker of biological aging. Dyslipidemia is an established risk factor for most age-related metabolic disorders. However, little is known about the relationship between LTL and dyslipidemia. Lipidomics is a new biochemical technique that can simultaneously identify and quantify hundreds to thousands of small molecular lipid species. In a large population comprising 1843 well-characterized American Indians in the Strong Heart Family Study, we examined the lipidomic profile of biological aging assessed by LTL. Briefly, LTL was quantified by qPCR. Fasting plasma lipids were quantified by untargeted liquid chromatography-mass spectrometry. Lipids associated with LTL were identified by elastic net modeling. Of 1542 molecular lipids identified (518 known, 1024 unknown), 174 lipids (36 knowns) were significantly associated with LTL, independent of chronological age, sex, BMI, hypertension, diabetes status, smoking status, bulk HDL-C, and LDL-C. These findings suggest that altered lipid metabolism is associated with biological aging and provide novel insights that may enhance our understanding of the relationship between dyslipidemia, biological aging, and age-related diseases in American Indians.

1H NMR-Based Metabolomics Reveals the Intrinsic Interaction of Age, Plasma Signature Metabolites, and Nutrient Intake in the Longevity Population in Guangxi, China

Health and longevity populations have distinct metabolic and nutrient intake profiles. However, the relationship between biomarkers of longevity-related metabolites and dietary nutrient intake profiles, as well as metabolic markers associated with longevity features, have not been fully elucidated. Therefore, ¹H nuclear magnetic resonance (¹H NMR)-based plasma metabolomics profiling was conducted in the present study to identify potential metabolites which can be used as specific markers for the evaluation of healthy aging. Plasma samples were obtained from centenarians and nonagenarians from the longevous region, and elderly participants aged 60–89 from the longevous region, as well as a low centenarian ratio region. The results showed that participants from longevous regions exhibited higher plasma levels of citrate, tyrosine, choline, carnitine, and valine, as well as lower contents of VLDL, lactate, alanine, N-acetyl glycoprotein (NAG), trimethylamine oxide (TMAO), α-glucose, β-glucose, and unsaturated lipids. The differential plasma metabolites were associated with an alteration in glycolysis/gluconeogenesis; aminoacyl-tRNA biosynthesis; alanine, aspartate, and glutamate metabolism; and phenylalanine, tyrosine, and tryptophan biosynthesis in participants from longevous regions. The signature metabolites were associated with higher dietary fiber intake, as well as lower energy and fat intake. The results of the present study demonstrate key longevity signature metabolites in plasma, and the dietary patterns identified provide a basis for further health and longevity research.

The Impact of Exercise on Telomere Length, DNA Methylation and Metabolic Footprints

Aging as a major risk factor influences the probability of developing cancer, cardiovascular disease and diabetes, amongst others. The underlying mechanisms of disease are still not fully understood, but research suggests that delaying the aging process could ameliorate these pathologies. A key biological process in aging is cellular senescence which is associated with several stressors such as telomere shortening or enhanced DNA methylation. Telomere length as well as DNA methylation levels can be used as biological age predictors which are able to detect excessive acceleration or deceleration of aging. Analytical methods examining aging are often not suitable, expensive, time-consuming or require a high level of technical expertise. Therefore, research focusses on combining analytical methods which have the potential to simultaneously analyse epigenetic, genomic as well as metabolic changes.

Fat metabolism is associated with telomere length in six population-based studies

Telomeres are repetitive DNA sequences located at the end of chromosomes, which are associated to biological aging, cardiovascular disease, cancer, and mortality. Lipid and fatty acid metabolism have been associated with telomere shortening. We have conducted an in-depth study investigating the association of metabolic biomarkers with telomere length (LTL). We performed an association analysis of 226 metabolic biomarkers with LTL using data from 11 775 individuals from six independent population-based cohorts (BBMRI-NL consortium). Metabolic biomarkers include lipoprotein lipids and subclasses, fatty acids, amino acids, glycolysis measures and ketone bodies. LTL was measured by quantitative polymerase chain reaction or FlowFISH. Linear regression analysis was performed adjusting for age, sex, lipid-lowering medication and cohort-specific covariates (model 1) and additionally for body mass index (BMI) and smoking (model 2), followed by inverse variance-weighted meta-analyses (significance threshold pmeta = 6.5x10-4). We identified four metabolic biomarkers positively associated with LTL, including two cholesterol to lipid ratios in small VLDL (S-VLDL-C % and S-VLDL-ce %) and two omega-6 fatty acid ratios (FAw6/FA and LA/FA). After additionally adjusting for BMI and smoking, these metabolic biomarkers remained associated with LTL with similar effect estimates. In addition, cholesterol esters in very small VLDL (XS-VLDL-ce) became significantly associated with LTL (p = 3.6x10-4). We replicated the association of FAw6/FA with LTL in an independent dataset of 7845 individuals (p = 1.9x10-4). To conclude, we identified multiple metabolic biomarkers involved in lipid and fatty acid metabolism that may be involved in LTL biology. Longitudinal studies are needed to exclude reversed causation.

Telomere length and mtDNA copy number in human cystathionine β-synthase deficiency

Telomere shortening and mitochondrial DNA (mtDNA) copy number are associated with human disease and a reduced life span. Cystathionine β-synthase (CBS) is a housekeeping enzyme that catalyzes the first step in metabolic conversion of homocysteine (Hcy) to cysteine. Mutations in the CBS gene cause CBS deficiency, a rare recessive metabolic disease, manifested by severe hyperhomocysteinemia (HHcy) and thromboembolism, which ultimately reduces the life span. However, it was not known whether telomere shortening or mtDNA is involved in the pathology of human CBS deficiency. We quantified leukocyte telomere length (TL), mtDNA copy number, and plasma Hcy levels in CBS^-/- patients (n = 23) and in sex- and age-matched unaffected CBS^+/+ control individuals (n = 28) 0.08-57 years old. We found that TL was significantly increased in severely HHcy CBS^-/- female patients but unaffected in severely HHcy CBS^-/- male patients, relative to the corresponding CBS^+/+ controls who had normal plasma Hcy levels. In multiple regression analysis TL was associated with CBS genotype in women but not in men. MtDNA copy number was not significantly affected by the CBS^-/- genotype. Taken together, these findings identify the CBS gene as a new locus in human DNA that affects TL in women and illustrate a concept that a housekeeping metabolic gene can be involved in telomere biology. Our findings suggest that neither telomere shortening nor reduced mtDNA copy number contribute to the reduced life span in CBS^-/- patients.