The Role of Telomeres in Human Disease

Telomere length and telomerase activity in men and non-pregnant women with and without metabolic syndrome: a systematic review and bootstrapped meta-analysis

Purpose

We performed a systematic review and meta-analysis to examine the associations between telomere length and telomerase activity in subjects with and without metabolic syndrome (MetS).

Methods

The meta-analysis protocol was registered in the PROSPERO database. The PubMed, Embase, Cochrane Library, and LILACS databases were searched for studies reporting telomere length or telomerase activity in adult men and non-pregnant women with and without MetS. The risk of bias was assessed with the Newcastle-Ottawa Scale. Random effects and inverse variance methods were used to meta-analyze associations. We conducted a bootstrapped analysis to test the accuracy of clinical results.

Results

Five studies reported telomere length and two studies telomerase activity. There was no significant difference in telomere length (standardized mean difference [SMD]: 0.10, 95% confidence interval [CI]: -0.07, 0.28, I 2: 54%), between subjects of similar age (mean difference: 2.68, 95%CI: -0.04, 5.40 years) with and without the MetS. Subjects with MetS displayed significantly higher body mass index, triglycerides, and blood pressure, and lower HDL-cholesterol values than subjects without the syndrome. A bootstrapping mediation analysis of telomere length confirmed the clinical results. There was no significant difference in telomerase activity (SMD: 1.19, 95% CI -0.17, 2.55, I 2: 93%) between subjects with and without the MetS.

Conclusion

There were no significant differences of telomere length and telomerase activity in patients with MetS and subjects of similar age without the syndrome.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-024-01513-4.

Causal effect between telomere length and thirteen types of cancer in Asian population: a bidirectional Mendelian randomization study

BACKGROUND

The relationship between leukocyte telomere length (LTL) and the risk of developing various cancers has always been controversial and predominantly focused on European populations. Hence, Mendelian randomization (MR) was applied to the Asian population to explore the causal relationships between LTL and the risk of developing various cancers.

METHODS

We explored the causal connection between LTL and the risk of developing thirteen types of cancer in Asian populations using freely available genetic variation data. The primary analytical method employed was the inverse variance weighted (IVW) method, complemented by sensitivity and validation analyses. Following Bonferroni correction, P < 0.0038 was considered to indicate statistical significance, and P values ranging from 0.0038 to 0.05 were considered to indicate a nominally significant association.

RESULTS

The findings indicated significant positive associations between LTL and the risk of developing lung cancer [odds ratio (OR) = 1.6009, 95% confidence interval (CI) 1.3056-1.9629, P = 6.08 × 10-6] and prostate cancer (OR = 1.4200, 95% CI 1.1489-1.7550, P = 0.0012). Additionally, there was a nominally significant association between LTL and the risk of developing hematological malignancy (OR = 1.5119, 95% CI 1.0810-2.1146, P = 0.0157). No statistically significant relationships between LTL and the risk of developing the other ten kinds of cancer were detected. No causal link between the risk of developing various cancers and LTL was discovered.

CONCLUSIONS

Asians with longer telomeres are more prone to developing lung and prostate cancer. There is also a nominally significant association between longer telomeres and the risk of developing hematological malignancy.

Loss of Ten1 in mice induces telomere shortening and models human dyskeratosis congenita

Telomere length regulation is essential for genome stability as short telomeres can trigger cellular senescence and apoptosis constituting an integral aspect of biological aging. Telomere biology disorders (TBDs) such as dyskeratosis congenita (DC) are rare, inherited diseases with known mutations in at least 16 different genes encoding components of the telomere maintenance complexes. The precise role of TEN1, part of the CST complex (CTC1, STN1, and TEN1), and the consequences of its loss of function in vivo are not yet known. We investigated the first viable murine model of Ten1 deficiency created by CRISPR-Cas9-mediated exon 3 deletion. Ten1 homozygous knockout mice present with telomere attrition, short life span, skin hyperpigmentation, aplastic anemia, and cerebellar hypoplasia. Molecular analyses revealed a reduction of proliferating cells, increased apoptosis, and stem cell depletion with activation of the p53/p21 signaling pathway. Our data demonstrate that Ten1 deficiency causes telomere shortening and associates with accelerated aging.

Exploring the relationship between air pollution and telomere length: Baseline findings from a comprehensive ambispective cohort study

BACKGROUND

Telomere length is a biomarker of cellular aging, influenced by various environmental and lifestyle factors. Air pollution is a known environmental stressor that may impact telomere dynamics. This study aimed to investigate the effect of age, lifetime exposure to air pollution, inflammatory parameters and selected lifestyle factors on telomere length.

METHODS

The study included 356 participants aged 35-65 living in two regions with varying pollution. Telomere length was measured using qPCR. Individual lifetime exposures to PM10, PM2.5, NO2, benzo(a)pyrene and benzene were calculated based on historical air quality data. Statistical analysis of age, pollution exposure, inflammatory parameters, and lifestyle factors on telomere length was performed using logistic regression and generalized linear models, with odds ratios calculated.

RESULTS

Unexpectedly, higher air pollutants lifetime exposures were associated with longer telomeres, particularly for PM10 51-55 μg/m3 (OR = 5.67, p < 0.001), PM2.5 42-45 μg/m3 (OR = 6.56, p < 0.001), B(a)P 6.9-8.3 ng/m3 (OR = 5.25, p = 0.002), NO2 26-27 μg/m3 (OR = 5.22, p = 0.001) and benzene 2.45-2.75 μg/m3 (OR = 6.13, p < 0.001). Age significantly affected telomere length, with older individuals having shorter telomeres. Socioeconomic factors such as college education were positively associated with longer telomeres, while lifestyle factors did not show significant associations. IL-8 was identified as a significant inflammatory marker negatively associated with very long telomeres.

CONCLUSION

These baseline findings bring new perspective to the relationship between air pollution and telomere length. Contrary to traditional views, the results suggest potential adaptive responses, highlighting the need for further longitudinal research to explore telomere dynamics over time in conjunction with other factors.

Prognostic model of osteosarcoma based on telomere-related genes and analysis of immune characteristics

OBJECTIVE

Osteosarcoma is a malignant tumor with significant challenges in treatment and prognosis. Telomeres play a crucial role in genetic stability and tumor development, and telomere-related genes (TRGs) have shown considerable prognostic potential in various cancers. However, the prognostic significance of TRGs in osteosarcoma and their involvement in the tumor immune microenvironment (TIME) remain poorly understood.

METHOD

This study initially identified 2086 TRGs from the TelNet database as candidate genes. Using RNA sequencing and clinical data from osteosarcoma patients available in the TARGET and GEO public databases, we developed a TRG-based prognostic scoring model through univariate, LASSO regression, and multivariate Cox regression analyses, with its predictive performance subsequently validated. Unsupervised clustering was performed on TRGs associated with prognosis. To investigate the TIME, we utilized several algorithms including ESTIMATE, CIBERSORT, xCELL, and ssGSEA to analyze the immune landscape associated with TRG patterns. Additionally, functional enrichment analysis of different subtypes was conducted using KEGG, GO, and GSVA approaches. We also performed single-cell localization and drug sensitivity analysis on the prognostic model genes. Finally, the predictive results were preliminarily validated through a series of in vitro experiments.

RESULT

Differential expression analysis revealed 841 TRGs with significant changes in osteosarcoma, where P-value < 0.05 and |logFC| ≥ 1. Based on the prognostic relevance of these TRGs, we successfully identified two subtypes with distinct clinical and immune characteristics. Immune infiltration levels between Cluster 1 and Cluster 2 were significantly different, as assessed by multiple algorithms. Furthermore, we constructed a prognostic scoring model based on TRGs, which demonstrated excellent predictive performance, with AUC values for 1-year, 3-year, and 5-year ROC curves being 92.43 %, 87.08 %, and 84.34 % in the training cohort, respectively, and 74.49 %, 87.77 %, and 94.52 % in the validation cohort, indicating good stability of the model. Notably, functional enrichment analysis highlighted a strong association between immune dysfunction and poor prognosis, while drug sensitivity analysis offered personalized chemotherapy recommendations for osteosarcoma patients with different subtypes. We observed that Fludarabine had a higher IC50 value in the high-risk group compared to the low-risk group, and it showed a strong correlation with the prognostic model genes, with all P-values less than 0.05.

CONCLUSION

This study successfully constructed a prognostic risk prediction model for osteosarcoma by systematically analyzing the expression patterns of TRGs. Fludarabine may represent a promising therapeutic option for patients with osteosarcoma.

Premature aging and metabolic diseases: the impact of telomere attrition

Driven by genetic and environmental factors, aging is a physiological process responsible for age-related degenerative changes in the body, cognitive decline, and impaired overall wellbeing. Notably, premature aging as well as the emergence of progeroid syndromes have posed concerns regarding chronic health conditions and comorbidities in the aging population. Accelerated telomere attrition is also implicated in metabolic dysfunction and the development of metabolic disorders. Impaired metabolic homeostasis arises secondary to age-related increases in the synthesis of free radicals, decreased oxidative capacity, impaired antioxidant defense, and disrupted energy metabolism. In particular, several cellular and molecular mechanisms of aging have been identified to decipher the influence of premature aging on metabolic diseases. These include defective DNA repair, telomere attrition, epigenetic alterations, and dysregulation of nutrient-sensing pathways. The role of telomere attrition premature aging in the pathogenesis of metabolic diseases has been largely attributed to pro-inflammatory states that promote telomere shortening, genetic mutations in the telomerase reverse transcriptase, epigenetic alteration, oxidative stress, and mitochondrial dysfunctions. Nonetheless, the therapeutic interventions focus on restoring the length of telomeres and may include treatment approaches to restore telomerase enzyme activity, promote alternative lengthening of telomeres, counter oxidative stress, and decrease the concentration of pro-inflammatory cytokines. Given the significance and robust potential of delaying telomere attrition in age-related metabolic diseases, this review aimed to explore the molecular and cellular mechanisms of aging underlying premature telomere attrition and metabolic diseases, assimilating evidence from both human and animal studies.

Clinical Use of ZSCAN4 for Telomere Elongation in Hematopoietic Stem Cells

BACKGROUND

Extremely short telomeres in patients with dyskeratosis congenita and related telomere biology disorders (TBDs) lead to premature cellular senescence and bone marrow failure. Zinc finger and SCAN domain-containing 4 (ZSCAN4) elongates telomeres by recombination.

METHODS

We report a clinical study in which EXG34217, the term given for autologous CD34+ hematopoietic stem cells from patients with TBD exposed to a temperature-sensitive Sendai virus vector encoding human ZSCAN4 at 33°C for 24 hours, was infused into patients without preconditioning.

RESULTS

Four patients were enrolled; two experienced successful CD34+ mobilization during the second mobilization attempt and underwent apheresis and EXG34217 infusion, with follow-up of 5 and 24 months (both ongoing). We observed telomere elongation (1.06- to 1.34-fold) in CD34+ cells ex vivo. In one patient, the treatment was associated with a change in the mean absolute neutrophil count (ANC) from 1.78×103 to 3.18×103 cells/μl; the lymphocyte subpopulation telomere length changed from 3.6 to 6.7 kb (50th percentile for age). In the other patient, the treatment was associated with a change in the lowest ANC from 0.6×103/μl to 1.2×103/μl; this has occurred in 5 months without the patient receiving prior intermittent low-dose granulocyte-colony-stimulating factor injections. During mobilization, all patients experienced mild to moderate bone pain or pain after line replacement, and one patient had a blood infection associated with fever and hypoxemia. After EXG34217 infusion, no acute safety issues were noted; in one patient mild to moderate long-term cardiac and pulmonary adverse events were noted; these were similar to symptoms of the patient's underlying conditions.

CONCLUSIONS

Although definitive conclusions cannot be drawn from the two EXG34217-treated patients, these results warrant further investigation of CD34+ cells exposed to ZSCAN4 for treating TBDs. (Funded by Elixirgen Therapeutics; ClinicalTrials.gov number, NCT04211714.).

Premature ageing of lung alveoli and bone marrow cells from Terc deficient mice with different telomere lengths

Telomeres are terminal protective chromosome structures. Genetic variants in genes coding for proteins required for telomere maintenance cause rare, life-threatening Telomere Biology Disorders (TBDs) such as dyskeratosis congenita, aplastic anemia or pulmonary fibrosis. The more frequently used mice strains have telomeres much longer than the human ones which question their use as in vivo models for TBDs. One mice model with shorter telomeres based on the CAST/EiJ mouse strain carrying a mutation in the Terc gene, coding for the telomerase RNA component, has been studied in comparison with C57BL/6J mice, carrying the same mutation and long telomeres. The possible alterations produced in lungs and the haematopoietic system, frequently affected in TBD patients, were determined at different ages of the mice. Homozygous mutant mice presented a very shortened life span, more notorious in the short-telomeres CAST/EiJ strain. The lungs of mutant mice presented a transitory increase in fibrosis and a significant decrease in the relative amount of the alveolar epithelial type 2 cells from six months of age. This decrease was larger in mutant homozygous animals but was also observed in heterozygous animals. On the contrary the expression of the senescence-related protein P21 increased from six months of age in mutant mice of both strains. The analysis of the haematopoietic system indicated a decrease in the number of megakaryocyte-erythroid progenitors in homozygous mutants and an increase in the clonogenic potential of bone marrow and LSK cells. Bone marrow cells from homozygous mutant animals presented decreasing in vitro expansion capacity. The alterations observed are compatible with precocious ageing of lung alveolar cells and the bone marrow cells that correlate with the alterations observed in TBD patients. The alterations seem to be more related to the genotype of the animals that to the basal telomere length of the strains although they are more pronounced in the short-telomere CAST/EiJ-derived strain than in C57BL/6J animals. Therefore, both animal models, at ages over 6-8 months, could represent valuable and convenient models for the study of TBDs and for the assay of new therapeutic products.

Chemotherapeutic 6-thio-2'-deoxyguanosine selectively targets and inhibits telomerase by inducing a non-productive telomere-bound telomerase complex

Most cancers upregulate the telomere lengthening enzyme telomerase to achieve unlimited cell division. How chemotherapeutic nucleoside 6-thio-2'-deoxyguanosine (6-thio-dG) targets telomerase to inhibit telomere maintenance in cancer cells and tumors was unclear. Here, we demonstrate that telomerase insertion of 6-thio-dGTP prevents synthesis of additional telomeric repeats but does not disrupt telomerase binding to telomeres. Specifically, 6-thio-dG inhibits telomere extension after telomerase translocates along its product DNA to reposition the template, inducing a non-productive complex rather than enzyme dissociation. Furthermore, we provide direct evidence that 6-thio-dG treatment inhibits telomere synthesis by telomerase in cancer cells. In agreement, telomerase-expressing cancer cells harboring critically short telomeres are more sensitive to 6-thio-dG and show a greater induction of telomere losses compared to cancer cells with long telomere reserves. Our studies reveal that telomere length and telomerase status determine 6-thio-dG sensitivity and uncover the molecular mechanism by which 6-thio-dG selectively inhibits telomerase synthesis of telomeric DNA.

The canonical RPA complex interacts with Est3 to regulate yeast telomerase activity

In most eukaryotic organisms, cells that rely on continuous cell division employ the enzyme telomerase which replenishes chromosome termini through the addition of telomeric repeats. In budding yeast, the telomerase holoenzyme is composed of a catalytic core associated with two regulatory subunits, Est1 and Est3. The Est1 protein binds a telomere-specific RPA-like complex to recruit telomerase to chromosome ends. However, the regulatory function of the Est3 subunit has remained elusive. We report here that an interaction between Est3 and the canonical RPA complex is required for in vivo telomerase function, as revealed by mutations in RPA2 that confer an Est (Ever shorter telomeres) phenotype, characteristic of a defect in the telomerase pathway. Binding between RPA and telomerase, which is supported by compensatory charge-swap mutations in EST3 and RPA2, utilizes a surface on Est3 that is structurally analogous to an interface on the human TPP1 protein that is required for telomerase processivity. Mutations in a subset of conserved DNA contact residues in RPA also result in short telomeres and senescence, which we show is due to a requirement for DNA binding after RPA interacts with telomerase. We propose that once RPA forms a complex with telomerase, RPA utilizes a subset of DNA-binding domains to stabilize the interaction between the telomerase active site and telomeric substrates, thereby facilitating enzyme processivity. These results, combined with prior observations, show that yeast telomerase interacts with two different high-affinity ssDNA-binding complexes, indicating that management of single-stranded DNA is integral to effective telomerase function.

Adult-Onset Presentations of Retinopathy Associated With Short Telomere Syndromes

Purpose: To describe the association between short telomere syndrome and exudative retinopathies in adults. Methods: This case series compared the presentation, course of treatment, and visual outcomes of 2 patients with adult-onset retinopathy associated with short telomere syndrome. Results: In Case 1, a 53-year-old man initially presented with bilateral retinal telangiectasias and preretinal hemorrhage in the left eye, which was followed by multiple vitreous hemorrhages. In the subsequent 15 years, the patient was diagnosed with pulmonary fibrosis, liver cirrhosis, and a RTEL1 gene mutation, consistent with short telomere syndrome. In Case 2, a previously asymptomatic 26-year-old man with paternally inherited short telomere syndrome (TERC gene mutation) presented with floaters, bilateral peripheral retinal capillary nonperfusion, and an aneurysmal lesion with surrounding exudation. Conclusions: Short telomere syndromes, with systemic features that can be life-threatening, can manifest initially in adulthood with retinal telangiectasia, aneurysmal lesions, exudation, or peripheral retinal capillary nonperfusion, preceding systemic manifestations. Because the systemic manifestations of retinal telangiectasia and peripheral retinal capillary nonperfusion are progressive and can be life-threatening, recognizing these findings in adults with retinal telangiectasia is crucial.

Leptin Modulates Ovarian Granulosa Cell Apoptosis by Regulating Telomerase Activity and Telomere Length in Polycystic Ovary Syndrome

Leptin (LEP) is implicated in the pathogenesis of polycystic ovary syndrome (PCOS). This study investigates the mechanism of LEP in PCOS. The baseline information of 80 PCOS patients and matched controls was analyzed, with serum and follicular fluid (FF) LEP and LEP receptor (LEPR) levels, telomerase activity, and relative telomere length (TL) measured. The correlation of FF LEP with telomerase activity and TL was analyzed. The viability and apoptosis of KGN cells (the ovarian granulosa cells) treated with gradient LEP were assessed. LEP-LEPR interaction was examined. LEPR, v-myc avian myelocytomatosis viral oncogene homolog (c-MYC), and telomerase reverse transcriptase (TERT) levels and c-MYC protein expression in the TERT promoter region were determined. Nuclear c-MYC translocation was detected. LEP was upregulated in sera and FF of PCOS patients. FF LEP positively correlated with telomerase activity and TL. Low-concentration LEP facilitated KGN cell proliferation, and high-concentration LEP dose-dependently suppressed cell proliferation, promoted apoptosis, upregulated LEPR, and increased telomerase activity and relative TL. LEP-LEPR interaction upregulated c-MYC and facilitated its nuclear accumulation. c-MYC enrichment in the TERT promoter region upregulated TERT, altering telomerase activity and TL and inducing cell apoptosis. Briefly, LEP/LEPR activates c-MYC, modulates TERT expression, and increases telomerase activity and TL, thus inducing ovarian granulosa cell apoptosis and participating in PCOS.

Exploration of the mechanism and therapy of ovarian aging by targeting cellular senescence

The ovary is a crucial gonadal organ that supports female reproductive and endocrine functions. Ovarian aging can result in decreased fertility and dysfunction across multiple organs. Research has demonstrated that cellular senescence in various cell types within the ovary can trigger a decline in ovarian function through distinct stress responses, resulting in ovarian aging. This review explores how cellular senescence may contribute to ovarian aging and reproductive failure. Additionally, we discuss the factors that cause ovarian cellular senescence, including the accumulation of advanced glycation end products, oxidative stress, mitochondrial dysfunction, DNA damage, telomere shortening, and exposure to chemotherapy. Furthermore, we discuss senescence in six distinct cell types, including oocytes, granulosa cells, ovarian theca cells, immune cells, ovarian surface epithelium, and ovarian endothelial cells, inside the ovary and explore their contribution to the accelerated ovarian aging. Lastly, we describe potential senotherapeutics for the treatment of ovarian aging and offer novel strategies for ovarian longevity.

A telomere-related signature for predicting prognosis and assessing immune microenvironment in osteosarcoma

Objective

Osteosarcoma is the most common primary bone cancer with a high propensity for local invasion and metastasis. An increasing number of research studies show that telomeres play an important role in the occurrence and development of cancer. Thus, we established a telomere-related signature in osteosarcoma to comprehensively evaluate the pathogenic roles of telomeres in this disease.

Methods

The data on osteosarcoma were collected from the TARGET and Gene Expression Omnibus databases. First, we constructed a telomere-related signature using univariate and LASSO Cox regression analyses. Subsequently, we analyzed the prognostic value, functional annotation, immune microenvironment, and cell communication patterns of the telomere-related signature in osteosarcoma via comprehensive bioinformatics analyses. Cell proliferation was analyzed using the CCK-8 assay, and cell migration and invasion capabilities were evaluated using the Transwell assay.

Results

Based on the SP110, HHAT, TUBB, MORC4, TERT, PPARG, MAP3K5, PAGE5, MAP7, and CAMK1G, a telomere-related signature was built in osteosarcoma patients. The telomere-related signature could effectively predict the prognosis of osteosarcoma patients. The osteosarcoma patients in the high TELscore group exhibited poor prognosis. In addition, the telomere-related signature demonstrated predictive value for the immune microenvironment and drug sensitivity in osteosarcoma. Finally, we discovered significant reduction in MAP7 expression in osteosarcoma cells, and patients with low MAP7 expression had poor prognosis. Moreover, the overexpression of MAP7 significantly reduced cell proliferation, the ability of cell migration, and invasion in osteosarcoma cells.

Conclusion

A telomere-related signature was constructed in osteosarcoma patients, offering predictive values into prognosis, the immune microenvironment, and drug sensitivity. Moreover, MAP7 might serve as a prognostic marker for osteosarcoma patients.

Effect of Physical Exercise on Telomere Length: Umbrella Review and Meta-Analysis

Background

Telomere length (TL) is a marker of cellular health and aging. Physical exercise has been associated with longer telomeres and, therefore, healthier aging. However, results supporting such effects vary across studies. Our aim was to synthesize existing evidence on the effect of different modalities and durations of physical exercise on TL.

Objective

The aim of this study was to explore the needs and expectations of individuals with physical disabilities and their interventionists for the use of a virtual reality physical activity platform in a community organization.

Methods

We performed an umbrella review and meta-analysis. Data sources included PubMed, Embase, Web of Science, Cochrane Library, and Scopus. We selected systematic reviews and meta-analyses of randomized and nonrandomized controlled clinical trials evaluating the effect of physical exercise on TL.

Results

Our literature search retrieved 12 eligible systematic reviews, 5 of which included meta-analyses. We identified 22 distinct primary studies to estimate the overall effect size of physical exercise on TL. The overall effect size was 0.28 (95% CI 0.118-0.439), with a heterogeneity test value Q of 43.08 (P=.003) and I² coefficient of 51%. The number of weeks of intervention explained part of this heterogeneity (Q_B=8.25; P=.004), with higher effect sizes found in studies with an intervention of less than 30 weeks. Exercise modality explained additional heterogeneity within this subgroup (Q_B=10.28, P=.02). The effect sizes were small for aerobic exercise and endurance training, and moderate for high-intensity interval training.

Conclusions

Our umbrella review and meta-analysis detected a small-moderate positive effect of physical exercise on TL, which seems to be influenced by the duration and type of physical exercise. High quality studies looking into the impact of standardized, evidence-based physical exercise programs on TL are still warranted.

Advances in Glioblastoma Diagnosis: Integrating Genetics, Noninvasive Sampling, and Advanced Imaging

Glioblastoma is the most common primary brain tumor in adult patients, and despite standard-of-care treatment, median survival has remained less than two years. Advances in our understanding of molecular mutations have led to changes in the diagnostic criteria of glioblastoma, with the WHO classification integrating important mutations into the grading system in 2021. We sought to review the basics of the important genetic mutations associated with glioblastoma, including known mechanisms and roles in disease pathogenesis/treatment. We also examined new advances in image processing as well as less invasive and noninvasive diagnostic tools that can aid in the diagnosis and surveillance of those undergoing treatment for glioblastoma. Our review is intended to serve as an overview of the current state-of-the-art in the diagnosis and management of glioblastoma.

Different phenotypes with different endings-Telomere biology disorders and cancer predisposition with long telomeres

Rare germline pathogenic variants (GPVs) in genes essential in telomere length maintenance and function have been implicated in two broad classes of human disease. The telomere biology disorders (TBDs) are a spectrum of life-threatening conditions, including bone marrow failure, liver and lung disease, cancer and other complications caused by GPVs in telomere maintenance genes that result in short and/or dysfunctional telomeres and reduced cellular replicative capacity. In contrast, cancer predisposition with long telomeres (CPLT) is a disorder associated with elevated risk of a variety of cancers, primarily melanoma, thyroid cancer, sarcoma, glioma and lymphoproliferative neoplasms caused by GPVs in shelterin complex genes that lead to excessive telomere elongation and increased cellular replicative capacity. While telomeres are at the root of both disorders, the term TBD is used to convey the clinical phenotypes driven by critically short or otherwise dysfunctional telomeres and their biological consequences.

Telomere biology disorders: from dyskeratosis congenita and beyond

Defective telomerase function or telomere maintenance causes genomic instability. Alterations in telomere length and/or attrition are the primary features of rare diseases known as telomere biology disorders or telomeropathies. Recent advances in the molecular basis of these disorders and cutting-edge methods assessing telomere length have increased our understanding of this topic. Multiorgan manifestations and different phenotypes have been reported even in carriers within the same family. In this context, apart from dyskeratosis congenita, disorders formerly considered idiopathic (i.e. pulmonary fibrosis, liver cirrhosis) frequently correlate with underlying defective telomere maintenance mechanisms. Moreover, these patients are prone to developing specific cancer types and exhibit exceptional sensitivity and toxicity in standard chemotherapy regimens. The current review describes the diverse spectrum of clinical manifestations of telomere biology disorders in pediatric and adult patients, their correlation with pathogenic variants, and considerations during their management to increase awareness and improve a multidisciplinary approach.

Update on Recommendations for Cancer Screening and Surveillance in Children with Genomic Instability Disorders

Genomic instability disorders are characterized by DNA or chromosomal instability, resulting in various clinical manifestations, including developmental anomalies, immunodeficiency, and increased risk of developing cancers beginning in childhood. Many of these genomic instability disorders also present with exquisite sensitivity to anticancer treatments such as ionizing radiation and chemotherapy, which may further increase the risk of second cancers. In July 2023, the American Association for Cancer Research held the second Childhood Cancer Predisposition Workshop, where multidisciplinary international experts discussed, reviewed, and updated recommendations for children with cancer predisposition syndromes. This article discusses childhood cancer risks and surveillance recommendations for the group of genomic instability disorders with predominantly recessive inheritance, including the DNA repair disorders ataxia telangiectasia, Nijmegen breakage syndrome, Fanconi anemia, xeroderma pigmentosum, Bloom syndrome, and Rothmund-Thomson syndrome, as well as the telomere biology disorders and mosaic variegated aneuploidy. Recognition of children with genomic instability disorders is important in order to make the proper diagnosis, enable genetic counseling, and inform cancer screening, cancer risk reduction, and choice of anticancer therapy.

Exposing telomere length's impact on malnutrition risk among older adults residing in the community: Insights from cross-sectional data analysis

BACKGROUND

Successful aging is associated with an increase in life expectancy. For a better understanding of the aging process, recognize the relationship between telomere length and nutritional status is a novel approach in geriatric science. Telomers shortening coincides with a decrease in life expectancy, and an increased risk of malnutrition-related diseases.

GOALS

The goal of this study was to investigate whether a shorter telomere length is associated with a greater likelihood of malnutrition in community-dwelling older adults.

METHODS

A cross-sectional study with a probabilistic sample of 448 older people aged 60 years old or over, and living in the urban area of an inland Brazilian municipality was conducted. The information was gathered in two stages: a) a personal interview was conducted to obtain sociodemographic, cognitive, and functional autonomy data. The Mini Nutritional Assessment was used to assess the risk of malnutrition. b) a blood sample was taken to proceed with the relative quantitative study of telomere length using real-time qPCR method. The differences between the groups were estimated using Pearson's v2 and Fisher's exact tests. In the data analysis, descriptive statistics and multiple logistic regression were applied.

RESULTS

In 34.15% of the total sample, malnutrition was recognized as a risk factor. Older people with the shortest telomere length had more chances of getting malnutrition (OR = 1.63; IC:95% = 1.04-2.55) compared to those with longer telomeres, independent of age groups, family income, multimorbidity, cognitive decline, and depressive symptoms.

CONCLUSION

The creation of clinical trials and the implementation of therapies to reduce the risk of malnutrition will be aided using the telomere length as an aging innovative biomarker, connected with nutritional status.

Haematological features of telomere biology disorders diagnosed in adulthood: A French nationwide study of 127 patients

Data on haematological features of telomere biology disorders (TBD) remain scarce. We describe haematological, extra-haematological characteristics and prognosis of 127 genetically confirmed TBD patients diagnosed after the age of 15. Ninety-three index cases and 34 affected relatives were included. At diagnosis of TBD, 76.3% of index cases had haematological features, half pulmonary features and a third liver features. At diagnosis, bone marrow failure (BMF) was present in 59 (46.5%), myelodysplastic syndrome (MDS) in 22 (17.3%) and acute myeloid leukaemia (AML) in 2 (1.6%) while 13 (10.2%) developed or worsened bone marrow involvement during follow-up. At diagnosis, compared to MDS/AML patients, BMF patients were younger (median 23.1 years vs. 43.8, p = 0.007), and had a better outcome (4-year overall survival 76.3% vs. 31.8%, p < 0.001). While frequencies and burden of cytogenetical and somatic mutations increased significantly in myeloid malignancies, some abnormalities were also observed in patients with normal blood counts and BMF, notably somatic spliceosome variants. Solid cancers developed in 8.7% patients, mainly human papillomavirus-related cancers and hepatocellular carcinomas. TBD is a multiorgan progressive disease. While BMF is the main haematological disorder, high-risk myeloid malignancies are common, and are, together with age, the only factors associated with a worse outcome.

High-throughput single telomere analysis using DNA microarray and fluorescent in situ hybridization

The human telomere system is highly dynamic. Both short and long leucocyte average telomere lengths (aTL) are associated with an increased risk of cancer and early death, illustrating the complex relationship between TL and human health and the importance of assessing TL distributions with single TL analysis. A DNA microarray and telomere fluorescent in situ hybridization (DNA-array-FISH) approach was developed to measure the base-pair (bp) lengths of single telomeres. On average 32000 telomeres were measured per DNA sample with one microarray chip assaying 96 test DNA samples. Various telomere parameters, i.e. aTL and the frequency of short/long telomeres, were computed to delineate TL distribution. The intra-assay and inter-assay coefficient of variations of aTL ranged from 1.37% to 3.98%. The correlation coefficient (r) of aTL in repeated measurements ranged from 0.91 to 1.00, demonstrating high measurement precision. aTLs measured by DNA-array-FISH predicted aTLs measured by terminal restriction fragment (TRF) analysis with r ranging 0.87-0.99. A new accurate and high-throughput method has been developed to measure the bp lengths of single telomeres. The large number of single TL data provides an opportunity for an in-depth analysis of telomere dynamics and the complex relationship between telomere and age-related diseases.

Genetic architecture of telomere length in 462,666 UK Biobank whole-genome sequences

Telomeres protect chromosome ends from damage and their length is linked with human disease and aging. We developed a joint telomere length metric, combining quantitative PCR and whole-genome sequencing measurements from 462,666 UK Biobank participants. This metric increased SNP heritability, suggesting that it better captures genetic regulation of telomere length. Exome-wide rare-variant and gene-level collapsing association studies identified 64 variants and 30 genes significantly associated with telomere length, including allelic series in ACD and RTEL1. Notably, 16% of these genes are known drivers of clonal hematopoiesis-an age-related somatic mosaicism associated with myeloid cancers and several nonmalignant diseases. Somatic variant analyses revealed gene-specific associations with telomere length, including lengthened telomeres in individuals with large SRSF2-mutant clones, compared with shortened telomeres in individuals with clonal expansions driven by other genes. Collectively, our findings demonstrate the impact of rare variants on telomere length, with larger effects observed among genes also associated with clonal hematopoiesis.

Telomere stabilization by metformin mitigates the progression of atherosclerosis via the AMPK-dependent p-PGC-1α pathway

Telomere dysfunction is a well-known molecular trigger of senescence and has been associated with various age-related diseases, including atherosclerosis. However, the mechanisms involved have not yet been elucidated, and the extent to which telomeres contribute to atherosclerosis is unknown. Therefore, we investigated the mechanism of metformin-induced telomere stabilization and the ability of metformin to inhibit vascular smooth muscle cell (VSMC) senescence caused by advanced atherosclerosis. The present study revealed that metformin inhibited the phenotypes of atherosclerosis and senescence in VSMCs. Metformin increased the phosphorylation of AMPK-dependent PGC-1α and thus increased telomerase activity and the protein level of TERT in OA-treated VSMCs. Mechanistically, the phosphorylation of AMPK and PGC-1α by metformin not only enhanced telomere function but also increased the protein level of TERT, whereas TERT knockdown accelerated the development of atherosclerosis and senescent phenotypes in OA-treated VSMCs regardless of metformin treatment. Furthermore, the in vivo results showed that metformin attenuated the formation of atherosclerotic plaque markers in the aortas of HFD-fed ApoE KO mice. Although metformin did not reduce plaque size, it inhibited the phosphorylation of the AMPK/PGC-1α/TERT signaling cascade, which is associated with the maintenance and progression of plaque formation, in HFD-fed ApoE KO mice. Accordingly, metformin inhibited atherosclerosis-associated phenotypes in vitro and in vivo. These observations show that the enhancement of telomere function by metformin is involved in specific signaling pathways during the progression of atherosclerosis. These findings suggest that telomere stabilization by metformin via the AMPK/p-PGC-1α pathway might provide a strategy for developing therapeutics against vascular diseases such as atherosclerosis.

Integrating Machine Learning with Multi-Omics Technologies in Geroscience: Towards Personalized Medicine

Aging is a fundamental biological process characterized by a progressive decline in physiological functions and an increased susceptibility to diseases. Understanding aging at the molecular level is crucial for developing interventions that could delay or reverse its effects. This review explores the integration of machine learning (ML) with multi-omics technologies-including genomics, transcriptomics, epigenomics, proteomics, and metabolomics-in studying the molecular hallmarks of aging to develop personalized medicine interventions. These hallmarks include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, disabled macroautophagy, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, chronic inflammation, and dysbiosis. Using ML to analyze big and complex datasets helps uncover detailed molecular interactions and pathways that play a role in aging. The advances of ML can facilitate the discovery of biomarkers and therapeutic targets, offering insights into personalized anti-aging strategies. With these developments, the future points toward a better understanding of the aging process, aiming ultimately to promote healthy aging and extend life expectancy.

Telomeric DNA breaks in human induced pluripotent stem cells trigger ATR-mediated arrest and telomerase-independent telomere damage repair

Although mechanisms of telomere protection are well-defined in differentiated cells, how stem cells sense and respond to telomere dysfunction, in particular telomeric double-strand breaks (DSBs), is poorly characterized. Here, we report the DNA damage signaling, cell cycle, and transcriptome changes in human induced pluripotent stem cells (iPSCs) in response to telomere-internal DSBs. We engineer human iPSCs with an inducible TRF1-FokI fusion protein to acutely induce DSBs at telomeres. Using this model, we demonstrate that TRF1-FokI DSBs activate an ATR-dependent DNA damage response, which leads to p53-independent cell cycle arrest in G2. Using CRISPR-Cas9 to cripple the catalytic domain of telomerase reverse transcriptase, we show that telomerase is largely dispensable for survival and lengthening of TRF1-FokI-cleaved telomeres, which instead are effectively repaired by robust homologous recombination (HR). In contrast to HR-based telomere maintenance in mouse embryonic stem cells, where HR causes ZSCAN4-dependent extension of telomeres beyond their initial lengths, HR-based repair of telomeric breaks is sufficient to maintain iPSC telomeres at a normal length, which is compatible with sustained survival of the cells over several days of TRF1-FokI induction. Our findings suggest a previously unappreciated role for HR in telomere maintenance in telomerase-positive iPSCs and reveal distinct iPSC-specific responses to targeted telomeric DNA damage.

Telomeres and telomerase in Sarcoma disease and therapy

Sarcoma is a rare tumor derived from the mesenchymal tissue and mainly found in children and adolescents. The outcome for patients with sarcoma is relatively poor compared with that for many other solid malignant tumors. Sarcomas have a highly heterogeneous pathogenesis, histopathology and biological behavior. Dysregulated signaling pathways and various gene mutations are frequently observed in sarcomas. The telomere maintenance mechanism (TMM) has recently been considered as a prognostic factor for patients with sarcomas, and alternative lengthening of telomeres (ALT) positivity has been correlated with poor outcomes in patients with several types of sarcomas. Therefore, telomeres and telomerases may be useful targets for treating sarcomas. This review aims to provide an overview of telomere and telomerase biology in sarcomas.

High prevalence of short telomeres in idiopathic porto-sinusoidal vascular disorder

BACKGROUND

Telomeres prevent damage to coding DNA as end-nucleotides are lost during mitosis. Mutations in telomere maintenance genes cause excessive telomere shortening, a condition known as short telomere syndrome (STS). One hepatic manifestation documented in STS is porto-sinusoidal vascular disorder (PSVD).

METHODS

As the etiology of many cases of PSVD remains unknown, this study explored the extent to which short telomeres are present in patients with idiopathic PSVD.

RESULTS

This monocentric cross-sectional study included patients with histologically defined idiopathic PSVD. Telomere length in 6 peripheral blood leukocyte subpopulations was assessed using fluorescent in situ hybridization and flow cytometry. Variants of telomere-related genes were identified using high-throughput exome sequencing. In total, 22 patients were included, of whom 16 (73%) had short (9/22) or very short (7/22) telomeres according to age-adjusted reference ranges. Fourteen patients (64%) had clinically significant portal hypertension. Shorter telomeres were more frequent in males (p = 0.005) and patients with concomitant interstitial lung disease (p < 0.001), chronic kidney disease (p < 0.001), and erythrocyte macrocytosis (p = 0.007). Portal hypertension (p = 0.021), low serum albumin level (p < 0.001), low platelet count (p = 0.007), and hyperbilirubinemia (p = 0.053) were also associated with shorter telomeres. Variants in known STS-related genes were identified in 4 patients with VSTel and 1 with STel.

CONCLUSIONS

Short and very short telomeres were highly prevalent in patients with idiopathic PSVD, with 31% presenting with variants in telomere-related genes. Telomere biology may play an important role in vascular liver disease development. Clinicians should consider measuring telomeres in any patient presenting with PSVD.

Telomere-lengthening germline variants predispose to a syndromic papillary thyroid cancer subtype

Papillary thyroid cancer (PTC) is the most common endocrine malignancy. 10% to 15% of individuals show familial clustering with three or more affected members, but the factors underlying this risk are unknown. In a group of recently studied individuals with POT1 pathogenic variants and ultra-long telomere length, PTC was the second most common solid tumor. We tested whether variants in POT1 and four other telomere-maintenance genes associated with familial cancer underlie PTC susceptibility. Among 470 individuals, we identified pathogenic or likely pathogenic variants in three genes encoding telomere-binding proteins: POT1, TINF2, and ACD. They were found in 4.5% and 1.5% of familial and unselected cases, respectively. Individuals harboring these variants had ultra-long telomere length, and 15 of 18 (83%) developed other cancers, of which melanoma, lymphoma, and sarcoma were most common. Among individuals with PTC and melanoma, 22% carried a deleterious germline variant, suggesting that a long telomere syndrome might be clinically recognizable. Successive generations had longer telomere length than their parents and, at times, developed more cancers at younger ages. Tumor sequencing identified a single oncogenic driver, BRAF p.Val600Glu, in 10 of 10 tumors studied, but no telomere-maintenance mechanism, including at the TERT promoter. These data identify a syndromic subset of PTCs with locus heterogeneity and telomere lengthening as a convergent mechanism. They suggest these germline variants lower the threshold to cancer by obviating the need for an acquired telomere-maintenance mechanism in addition to sustaining the longevity of oncogenic mutations.

Longer prostate stromal cell telomere length is associated with increased risk of death from other cancers

Background

Telomeres are located at chromosomal termini and function to maintain genomic integrity. Telomere dysfunction is a well-recognized contributor to aging and age-related diseases, such as prostate cancer. Since telomere length is highly heritable, we postulate that stromal cell telomere length in the tissue of a particular solid organ may generally reflect constitutive stromal cell telomere length in other solid organs throughout the body. Even with telomere loss occurring with each round of cell replication, in general, telomere length in prostate stromal cells in mid-life would still be correlated with the telomere length in stromal cells in other organs. Thus, we hypothesize that prostate stromal cell telomere length and/or telomere length variability is a potential indicator of the likelihood of developing future solid cancers, beyond prostate cancer, and especially lethal cancer.

Methods

To explore this hypothesis, we conducted a cohort study analysis of 1,175 men who were surgically treated for prostate cancer and were followed for death, including from causes other than their prostate cancer.

Results

In this cohort study with a median follow-up of 19 years, we observed that longer prostate stromal cell telomere length measured in tissue microarray spots containing prostate cancer was associated with an increased risk of death from other solid cancers. Variability in telomere length among these prostate stromal cells was possibly positively associated with risk of death from other solid cancers.

Conclusion

Studying the link between stromal cell telomere length and cancer mortality may be important for guiding the development of cancer interception and prevention strategies.

Leukocytospermia and/or Bacteriospermia: Impact on Male Infertility

Infertility is a globally underestimated public health concern affecting almost 190 million people, i.e., about 17.5% of people during their lifetime, while the prevalence of male factor infertility is about 7%. Among numerous other causes, the prevalence of male genital tract infections reportedly ranges between 10% and 35%. Leukocytospermia is found in 30% of infertile men and up to 20% in fertile men. Bacterial infections cause an inflammatory response attracting leukocytes, which produce reactive oxygen species (ROS) and release cytokines, both of which can cause damage to sperm, rendering them dysfunctional. Although leukocytospermia and bacteriospermia are both clinical conditions that can negatively affect male fertility, there is still debate about their impact on assisted reproduction outcomes and management. According to World Health Organization (WHO) guidelines, leukocytes should be determined by means of the Endtz test or with monoclonal antibodies against CD15, CD68 or CD22. The cut-off value proposed by the WHO is 1 × 106 peroxidase-positive cells/mL. For bacteria, Gram staining and semen culture are regarded as the "gold standard", while modern techniques such as PCR and next-generation sequencing (NGS) are allowing clinicians to detect a wider range of pathogens. Whereas the WHO manual does not specify a specific value as a cut-off for bacterial contamination, several studies consider semen samples with more than 103 colony-forming units (cfu)/mL as bacteriospermic. The pathogenic mechanisms leading to sperm dysfunction include direct interaction of bacteria with the male germ cells, bacterial release of spermatotoxic substances, induction of pro-inflammatory cytokines and ROS, all of which lead to oxidative stress. Clinically, bacterial infections, including "silent" infections, are treatable, with antibiotics being the treatment of choice. Yet, non-steroidal antiphlogistics or antioxidants should also be considered to alleviate inflammatory lesions and improve semen quality. In an assisted reproduction set up, sperm separation techniques significantly reduce the bacterial load in the semen. Nonetheless, contamination of the semen sample with skin commensals should be prevented by applying relevant hygiene techniques. In patients where leukocytospermia is detected, the causes (e.g. infection, inflammation, varicocele, smoking, etc.) of the leukocyte infiltration have to be identified and addressed with antibiotics, anti-inflammatories or antioxidants in cases where high oxidative stress levels are detected. However, no specific strategy is available for the management of leukocytospermia. Therefore, the relationship between bacteriospermia and leukocytospermia as well as their specific impact on functional sperm parameters and reproductive outcome variables such as fertilization or clinical pregnancy must be further investigated. The aim of this narrative review is to provide an update on the current knowledge on leukocytospermia and bacteriospermia and their impact on male fertility.

Human telomere length is chromosome end-specific and conserved across individuals

Short telomeres cause age-related disease, and long telomeres contribute to cancer; however, the mechanisms regulating telomere length are unclear. We developed a nanopore-based method, which we call Telomere Profiling, to determine telomere length at nearly single-nucleotide resolution. Mapping telomere reads to chromosome ends showed chromosome end-specific length distributions that could differ by more than six kilobases. Examination of telomere lengths in 147 individuals revealed that certain chromosome ends were consistently longer or shorter. The same rank order was found in newborn cord blood, suggesting that telomere length is determined at birth and that chromosome end-specific telomere length differences are maintained as telomeres shorten with age. Telomere Profiling makes precision investigation of telomere length widely accessible for laboratory, clinical, and drug discovery efforts and will allow deeper insights into telomere biology.

Clinical mutations in the TERT and TERC genes coding for telomerase components induced oxidative stress, DNA damage at telomeres and cell apoptosis besides decreased telomerase activity

Telomeres are nucleoprotein structures at the end of chromosomes that maintain their integrity. Mutations in genes coding for proteins involved in telomere protection and elongation produce diseases such as dyskeratosis congenita or idiopathic pulmonary fibrosis known as telomeropathies. These diseases are characterized by premature telomere shortening, increased DNA damage and oxidative stress. Genetic diagnosis of telomeropathy patients has identified mutations in the genes TERT and TERC coding for telomerase components but the functional consequences of many of these mutations still have to be experimentally demonstrated. The activity of twelve TERT and five TERC mutants, five of them identified in Spanish patients, has been analyzed. TERT and TERC mutants were expressed in VA-13 human cells that express low telomerase levels and the activity induced was analyzed. The production of reactive oxygen species, DNA oxidation and TRF2 association at telomeres, DNA damage response and cell apoptosis were determined. Most mutations presented decreased telomerase activity, as compared to wild-type TERT and TERC. In addition, the expression of several TERT and TERC mutants induced oxidative stress, DNA oxidation, DNA damage, decreased recruitment of the shelterin component TRF2 to telomeres and increased apoptosis. These observations might indicate that the increase in DNA damage and oxidative stress observed in cells from telomeropathy patients is dependent on their TERT or TERC mutations. Therefore, analysis of the effect of TERT and TERC mutations of unknown function on DNA damage and oxidative stress could be of great utility to determine the possible pathogenicity of these variants.

Influence of breed and environment on leukocyte telomere length in cattle

High milk yield is associated with reduced longevity in high-producing dairy cattle breeds. Pre-term culling leads to high replacement heifer demand and economic losses for the dairy industry. Selection for this trait is limited because of low heritability and difficulties in phenotype measurement. Telomeres are elements found at the ends of chromosomes, consisting of repetitive DNA sequences, several thousand base pairs in length, coupled with nucleoprotein complexes. Eventually, in humans and most other animals, telomere length reduces with age. When telomeric DNA is truncated to a critical length, cell ageing, cell cycle arrest, and apoptosis are induced. As a result, telomere length can be considered as a predictor of health risks and an individual's lifespan. The leukocyte telomere length may be used as a proxy phenotype of productive lifespan to improve cattle selection. Our objectives were to assess the effects of breed and breed group (dairy vs. beef) on the leukocyte telomere length and to estimate the effect of cold climate on this trait in Kalmyk cattle populations from the South (Rostov Oblast) and Far North (Republic of Sakha) regions of Russia. The leukocyte telomere lengths were estimated computationally from whole-genome resequencing data. We leveraged data on leukocyte telomere length, sex, and age of 239 animals from 17 cattle breeds. The breed factor had a significant effect on leukocyte telomere length across our sample. There was no difference in leukocyte telomere length between dairy and beef groups. The population factor had a significant effect on leukocyte telomere length in Kalmyk animals. In conclusion, we found that breed, but not breed group (dairy vs. beef), was significantly associated with leukocyte telomere length in cattle. Residence in colder climates was associated with longer leukocyte telomere length in Kalmyk breed cattle.

Telomere length and risk of cirrhosis, hepatocellular carcinoma, and cholangiocarcinoma in 63,272 individuals from the general population

BACKGROUND AND AIMS

Inherited short telomeres are associated with a risk of liver disease, whereas longer telomeres predispose to cancer. The association between telomere length and risk of HCC and cholangiocarcinoma remains unknown.

APPROACH AND RESULTS

We measured leukocyte telomere length using multiplex PCR in 63,272 individuals from the Danish general population. Telomere length and plasma ALT concentration were not associated (β = 4 ×10 -6 , p -value = 0.06) in a linear regression model, without any signs of a nonlinear relationship. We tested the association between telomere length and risk of cirrhosis, HCC, and cholangiocarcinoma using Cox regression. During a median follow-up of 11 years, 241, 76, and 112 individuals developed cirrhosis, HCC, and cholangiocarcinoma, respectively. Telomere length and risk of cirrhosis were inversely and linearly associated ( p -value = 0.004, p for nonlinearity = 0.27). Individuals with telomeres in the shortest vs. longest quartile had a 2.25-fold higher risk of cirrhosis. Telomere length and risk of HCC were nonlinearly associated ( p -value = 0.009, p -value for nonlinearity = 0.01). This relationship resembled an inverted J-shape, with the highest risk observed in individuals with short telomeres. Individuals with telomeres in the shortest versus longest quartile had a 2.29-fold higher risk of HCC. Telomere length was inversely and linearly associated with the risk of cholangiocarcinoma. Individuals with telomeres in the shortest versus longest quartile had a 1.86-fold higher risk of cholangiocarcinoma.

CONCLUSIONS

Shorter telomere length is associated with a higher risk of cirrhosis, HCC, and cholangiocarcinoma.

Epigenetic dynamics of aging and cancer development: current concepts from studies mapping aging and cancer epigenomes

PURPOSE OF REVIEW

This review emphasizes the role of epigenetic processes as incidental changes occurring during aging, which, in turn, promote the development of cancer.

RECENT FINDINGS

Aging is a complex biological process associated with the progressive deterioration of normal physiological functions, making age a significant risk factor for various disorders, including cancer. The increasing longevity of the population has made cancer a global burden, as the risk of developing most cancers increases with age due to the cumulative effect of exposure to environmental carcinogens and DNA replication errors. The classical 'somatic mutation theory' of cancer cause is being challenged by the observation that multiple normal cells harbor cancer driver mutations without resulting in cancer. In this review, we discuss the role of age-associated epigenetic alterations, including DNA methylation, which occur across all cell types and tissues with advancing age. There is an increasing body of evidence linking these changes with cancer risk and prognosis.

SUMMARY

A better understanding about the epigenetic changes acquired during aging is critical for comprehending the mechanisms leading to the age-associated increase in cancer and for developing novel therapeutic strategies for cancer treatment and prevention.

Targeting chromosomal instability and aneuploidy in cancer

Cancer development and therapy resistance are driven by chromosomal instability (CIN), which causes chromosome gains and losses (i.e., aneuploidy) and structural chromosomal alterations. Technical limitations and knowledge gaps have delayed therapeutic targeting of CIN and aneuploidy in cancers. However, our toolbox for creating and studying aneuploidy in cell models has greatly expanded recently. Moreover, accumulating evidence suggests that seven conventional antimitotic chemotherapeutic drugs achieve clinical response by inducing CIN instead of mitotic arrest, although additional anticancer activities may also contribute in vivo. In this review, we discuss these recent developments. We also highlight new discoveries, which together show that 25 chromosome arm aneuploidies (CAAs) may be targetable by 36 drugs across 14 types of cancer. Collectively, these advances offer many new opportunities to improve cancer treatment.

Genetically predicted telomere length and the risk of 11 hematological diseases: a Mendelian randomization study

OBJECTIVE

Previous studies have demonstrated that various hematologic diseases (HDs) induce alterations in telomere length (TL). The aim of this study is to investigate whether genetically predicted changes in TL have an impact on the risk of developing HDs.

METHODS

GWAS data for TL and 11 HDs were extracted from the database. The R software package "TwoSampleMR" was employed to conduct a two-sample Mendelian randomization (MR) analysis, in order to estimate the influence of TL changes on the risk of developing the 11 HDs.

RESULTS

We examined the effect of TL changes on the risk of developing the 11 HDs. The IVW results revealed a significant causal association between genetically predicted longer TL and the risk of developing acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MANTLE), and hodgkin lymphoma (HODGKIN). However, there was no significant causal relationship observed between TL changes and the risk of developing chronic myeloid leukemia (CML), diffuse large b-cell lymphoma (DLBCL), marginal zone b-cell lymphoma (MARGINAL), follicular lymphoma (FOLLICULAR), monocytic leukemia (MONOCYTIC), and mature T/NK-cell lymphomas (TNK).

CONCLUSIONS

The MR analysis revealed a positive association between genetically predicted longer TL and an increased risk of developing ALL, AML, CLL, MANTLE, and HODGKIN. This study further supports the notion that cells with longer TL have greater proliferative and mutational potential, leading to an increased risk of certain HDs.

Adaptive and Maladaptive Clonal Hematopoiesis in Telomere Biology Disorders

PURPOSE OF REVIEW

Telomere biology disorders (TBDs) are germline-inherited conditions characterized by reduction in telomerase function, accelerated shortening of telomeres, predisposition to organ-failure syndromes, and increased risk of neoplasms, especially myeloid malignancies. In normal cells, critically short telomeres trigger apoptosis and/or cellular senescence. However, the evolutionary mechanism by which TBD-related telomerase-deficient cells can overcome this fitness constraint remains elusive.

RECENT FINDINGS

Preliminary data suggests the existence of adaptive somatic mosaic states characterized by variants in TBD-related genes and maladaptive somatic mosaic states that attempt to overcome hematopoietic fitness constraints by alternative methods leading to clonal hematopoiesis. TBDs are both rare and highly heterogeneous in presentation, and the association of TBD with malignant transformation is unclear. Understanding the clonal complexity and mechanisms behind TBD-associated molecular signatures that lead to somatic adaptation in the setting of defective hematopoiesis will help inform therapy and treatment for this set of diseases.

Human telomere length is chromosome specific and conserved across individuals

Short telomeres cause age-related disease and long telomeres predispose to cancer; however, the mechanisms regulating telomere length are unclear. To probe these mechanisms, we developed a nanopore sequencing method, Telomere Profiling, that is easy to implement, precise, and cost effective with broad applications in research and the clinic. We sequenced telomeres from individuals with short telomere syndromes and found similar telomere lengths to the clinical FlowFISH assay. We mapped telomere reads to specific chromosome end and identified both chromosome end-specific and haplotype-specific telomere length distributions. In the T2T HG002 genome, where the average telomere length is 5kb, we found a remarkable 6kb difference in lengths between some telomeres. Further, we found that specific chromosome ends were consistently shorter or longer than the average length across 147 individuals. The presence of conserved chromosome end-specific telomere lengths suggests there are new paradigms in telomere biology that are yet to be explored. Understanding the mechanisms regulating length will allow deeper insights into telomere biology that can lead to new approaches to disease.

Effects of Physical Exercise on Telomere Length in Healthy Adults: Systematic Review, Meta-Analysis, and Meta-Regression

BACKGROUND

Physical exercise is one of the main nonpharmacological treatments for most pathologies. In addition, physical exercise is beneficial in the prevention of various diseases. The impact of physical exercise has been widely studied; however, existing meta-analyses have included diverse and heterogeneous samples. Therefore, to our knowledge, this is the first meta-analysis to evaluate the impact of different physical exercise modalities on telomere length in healthy populations.

OBJECTIVE

In this review, we aimed to determine the effect of physical exercise on telomere length in a healthy population through a meta-analysis of randomized controlled trials.

METHODS

A systematic review with meta-analysis and meta-regression of the published literature on the impact of physical exercise on telomere length in a healthy population was performed. PubMed, Cochrane Library, SCOPUS, Web of Science, and Embase databases were searched for eligible studies. Methodological quality was evaluated using the Risk Of Bias In Nonrandomized Studies of Interventions and the risk-of-bias tool for randomized trials. Finally, the certainty of our findings (closeness of the estimated effect to the true effect) was evaluated using Grading of Recommendations, Assessment, Development, and Evaluations (GRADE).

RESULTS

We included 9 trials that met the inclusion criteria with fair methodological quality. Random-effects model analysis was used to quantify the difference in telomere length between the exercise and sham groups. Meta-analysis showed that exercise did not significantly increase telomere length compared with the control intervention (mean difference=0.0058, 95% CI -0.05 to 0.06; P=.83). Subgroup analysis suggested that high-intensity interventional exercise significantly increased telomere length compared with the control intervention in healthy individuals (mean difference=0.15, 95% CI 0.03-0.26; P=.01). Furthermore, 56% of the studies had a high risk of bias. Certainty was graded from low to very low for most of the outcomes.

CONCLUSIONS

The findings of this systematic review and meta-analysis suggest that high-intensity interval training seems to have a positive effect on telomere length compared with other types of exercise such as resistance training or aerobic exercise in a healthy population.

TRIAL REGISTRATION

PROSPERO CRD42022364518; http://tinyurl.com/4fwb85ff.

Advancing athletic assessment by integrating conventional methods with cutting-edge biomedical technologies for comprehensive performance, wellness, and longevity insights

In modern athlete assessment, the integration of conventional biochemical and ergophysiologic monitoring with innovative methods like telomere analysis, genotyping/phenotypic profiling, and metabolomics has the potential to offer a comprehensive understanding of athletes' performance and potential longevity. Telomeres provide insights into cellular functioning, aging, and adaptation and elucidate the effects of training on cellular health. Genotype/phenotype analysis explores genetic variations associated with athletic performance, injury predisposition, and recovery needs, enabling personalization of training plans and interventions. Metabolomics especially focusing on low-molecular weight metabolites, reveal metabolic pathways and responses to exercise. Biochemical tests assess key biomarkers related to energy metabolism, inflammation, and recovery. Essential elements depict the micronutrient status of the individual, which is critical for optimal performance. Echocardiography provides detailed monitoring of cardiac structure and function, while burnout testing evaluates psychological stress, fatigue, and readiness for optimal performance. By integrating this scientific testing battery, a multidimensional understanding of athlete health status can be achieved, leading to personalized interventions in training, nutrition, supplementation, injury prevention, and mental wellness support. This scientifically rigorous approach hereby presented holds significant potential for improving athletic performance and longevity through evidence-based, individualized interventions, contributing to advances in the field of sports performance optimization.

Reduced SIRT1 and SIRT3 and Lower Antioxidant Capacity of Seminal Plasma Is Associated with Shorter Sperm Telomere Length in Oligospermic Men

Infertility affects millions of couples worldwide and has a profound impact not only on their families, but also on communities. Telomere attrition has been associated with infertility, DNA damage and fragmentation. Oxidative stress has been shown to affect sperm DNA integrity and telomere length. Sirtuins such as SIRT1 and SIRT3 are involved in aging and oxidative stress response. The aim of the present study is to determine the role of SIRT1 and SIRT3 in regulating oxidative stress, telomere shortening, and their association with oligospermia. Therefore, we assessed the protein levels of SIRT1 and SIRT3, total antioxidant capacity (TAC), superoxide dismutase (SOD), malondialdehyde (MDA) and catalase activity (CAT) in the seminal plasma of 272 patients with oligospermia and 251 fertile men. We also measured sperm telomere length (STL) and leukocyte telomere length (LTL) using a standard real-time quantitative PCR assay. Sperm chromatin and protamine deficiency were also measured as per standard methods. Our results for oligospermic patients demonstrate significant reductions in semen parameters, shorter STL and LTL, lower levels of SOD, TAC, CAT, SIRT1 and SIRT3 levels, and also significant protamine deficiency and higher levels of MDA and DNA fragmentation. We conclude that a shorter TL in sperms and leukocytes is associated with increased oxidative stress that also accounts for high levels of DNA fragmentation in sperms. Our results support the hypothesis that various sperm parameters in the state of oligospermia are associated with or caused by reduced levels of SIRT1 and SIRT3 proteins.

Telomeres as hotspots for innate immunity and inflammation

Aging is marked by the gradual accumulation of deleterious changes that disrupt organ function, creating an altered physiological state that is permissive for the onset of prevalent human diseases. While the exact mechanisms governing aging remain a subject of ongoing research, there are several cellular and molecular hallmarks that contribute to this biological process. This review focuses on two factors, namely telomere dysfunction and inflammation, which have emerged as crucial contributors to the aging process. We aim to discuss the mechanistic connections between these two distinct hallmarks and provide compelling evidence highlighting the loss of telomere protection as a driver of pro-inflammatory states associated with aging. By reevaluating the interplay between telomeres, innate immunity, and inflammation, we present novel perspectives on the etiology of aging and its associated diseases.

Clonal evolution in inherited marrow failure syndromes predicts disease progression

Progression to myelodysplastic syndromes (MDS) and acute myeloid leukemia is one of the most serious complications of the inherited bone marrow failure and MDS-predisposition syndromes. Given the lack of predictive markers, this risk can also be a source of great uncertainty and anxiety to patients and their providers alike. Recent data show that some acquired mutations may provide a window into this risk. While maladaptive mechanisms, such as monosomy 7, are associated with a high risk of leukemogenesis, mutations that offset the inherited defect (known as somatic genetic rescue) may attenuate this risk. Somatic mutations that are shared with age-acquired clonal hematopoiesis mutations also show syndrome-specific patterns that may provide additional data as to disease risk. This review focuses on recent progress in this area with an emphasis on the biological underpinnings and interpretation of these patterns for patient care decisions.

Experimental and Computational Approaches to Measure Telomere Length: Recent Advances and Future Directions

PURPOSE OF REVIEW

The length of telomeres, protective structures at the chromosome ends, is a well-established biomarker for pathological conditions including multisystemic syndromes called telomere biology disorders. Approaches to measure telomere length (TL) differ on whether they estimate average, distribution, or chromosome-specific TL, and each presents their own advantages and limitations.

RECENT FINDINGS

The development of long-read sequencing and publication of the telomere-to-telomere human genome reference has allowed for scalable and high-resolution TL estimation in pre-existing sequencing datasets but is still impractical as a dedicated TL test. As sequencing costs continue to fall and strategies for selectively enriching telomere regions prior to sequencing improve, these approaches may become a promising alternative to classic methods. Measurement methods rely on probe hybridization, qPCR or more recently, computational methods using sequencing data. Refinements of existing techniques and new approaches have been recently developed but a test that is accurate, simple, and scalable is still lacking.

A comprehensive prognostic and immunological analysis of telomere-related lncRNAs in kidney renal clear cell carcinoma

Kidney renal clear cell carcinoma (KIRC) is one of the most prevalent malignant tumors of the urinary system, with a high recurrence and metastasis rate. Telomeres and long non-coding RNAs (lncRNAs) have been documented playing critical roles in cancer progression. However, the prognostic significance of telomere-related lncRNA (TRLs) in KIRC is less well-defined. The Cancer Genome Atlas database was applied to retrieve the expression profiles and corresponding clinical information of KIRC patients. To create the TRLs prognostic signature, univariate Cox regression, least absolute shrinkage and selection operator analyses were performed. The prognostic signature, comprised of nine prognostic TRLs, was developed and demonstrated superior prognostic ability for KIRC patients. Additionally, the risk score acted as an independent prognostic indicator. A nomogram incorporating age, grade, stage, and signature-based risk scores was also developed and exhibited excellent predictive accuracy. Several immune activities were associated with the signature, as determined by gene function analysis. Further analysis revealed differences in the status of immunity and the tumor microenvironment between low- and high-risk groups. Notably, KIRC patients with high-risk scores were more responsive to immunotherapy and chemotherapy. To summarize, our study developed a new prognostic signature consisting of nine telomere-related lncRNA that can precisely predict the prognosis of KIRC patients. The signature was shown to be of substantial value for the tumor microenvironment and tumor mutation burden, thereby contributing to a framework for the individualized treatment of patients.

p53 in the Molecular Circuitry of Bone Marrow Failure Syndromes

Mice with a constitutive increase in p53 activity exhibited features of dyskeratosis congenita (DC), a bone marrow failure syndrome (BMFS) caused by defective telomere maintenance. Further studies confirmed, in humans and mice, that germline mutations affecting TP53 or its regulator MDM4 may cause short telomeres and alter hematopoiesis, but also revealed features of Diamond-Blackfan anemia (DBA) or Fanconi anemia (FA), two BMFSs, respectively, caused by defects in ribosomal function or DNA repair. p53 downregulates several genes mutated in DC, either by binding to promoter sequences (DKC1) or indirectly via the DREAM repressor complex (RTEL1, DCLRE1B), and the p53-DREAM pathway represses 22 additional telomere-related genes. Interestingly, mutations in any DC-causal gene will cause telomere dysfunction and subsequent p53 activation to further promote the repression of p53-DREAM targets. Similarly, ribosomal dysfunction and DNA lesions cause p53 activation, and p53-DREAM targets include the DBA-causal gene TSR2, at least 9 FA-causal genes, and 38 other genes affecting ribosomes or the FA pathway. Furthermore, patients with BMFSs may exhibit brain abnormalities, and p53-DREAM represses 16 genes mutated in microcephaly or cerebellar hypoplasia. In sum, positive feedback loops and the repertoire of p53-DREAM targets likely contribute to partial phenotypic overlaps between BMFSs of distinct molecular origins.