Asynchronous Shortening of Telomere Length and Cardiovascular Outcomes

Telomeres and telomerase in risk assessment of cardiovascular diseases

Telomeres are repetitive nucleoprotein structures located at the ends of chromosomes. Reduction in the number of repetitions causes cell senescence. Cells with high proliferative potential age with each replication cycle. Post-mitotic cells (e.g. cardiovascular cells) have a different aging mechanism. During the aging of cardiovascular system cells, permanent DNA damage occurs in the telomeric regions caused by mitochondrial dysfunction, which is a phenomenon independent of cell proliferation and telomere length. Mitochondrial dysfunction is accompanied by increased production of reactive oxygen species and development of inflammation. This phenomenon in the cells of blood vessels can lead to atherosclerosis development. Telomere damage in cardiomyocytes leads to the activation of the DNA damage response system, histone H2A.X phosphorylation, p53 activation and p21 and p16 protein synthesis, resulting in the SASP phenotype (senescence-associated secretory phenotype), increased inflammation and cardiac dysfunction. Cardiovascular cells show the activity of the TERT subunit of telomerase, an enzyme that prevents telomere shortening. It turns out that disrupting the activity of this enzyme can also contribute to the formation of cardiovascular diseases. Measurements of telomere length according to the "blood-muscle" model may help in the future to assess the risk of cardiovascular complications in people undergoing cardiological procedures, as well as to assess the effectiveness of some drugs.

Telomeres as Therapeutic Targets in Heart Disease

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Age-associated CVDs impose a great burden on current health systems. Despite the fact that current strong evidence supports the links among aging, telomere attrition, and CVDs, there is no clear direction for the development of telomere therapeutics against CVDs.

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This review focuses on immune modulation, CHIP, pharmaceutical interventions, and gene therapy for their therapeutic roles in age-associated CVDs.

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The future goal of telomere cardiovascular therapy in young subjects is to prevent senescence and diseases, whereas in older adult subjects, the goal is restoration of cardiovascular functions. Further studies on the telomere-CHIP-atherosclerosis axis may shed insights on how to achieve these 2 different therapeutic targets.

Telomeres are double-stranded repeats of G-rich tandem DNA sequences that gradually shorten with each cell division. Aging, inflammation, and oxidative stress accelerate the process of telomere shortening. Telomerase counteracts this process by maintaining and elongating the telomere length. Patients with atherosclerotic diseases and cardiovascular risk factors (e.g., smoking, obesity, sedentary lifestyle, and hypertension) have shorter leukocyte telomere length. Following myocardial infarction, telomerase expression and activity in cardiomyocytes and endothelial cells increase significantly, implying that telomerase plays a role in regulating tissue repairs in heart diseases. Although previous studies have focused on the changes of telomeres in heart diseases and the telomere length as a marker for aging cardiovascular systems, recent studies have explored the potential of telomeres and telomerase in the treatment of cardiovascular diseases. This review discusses the significant advancements of telomere therapeutics in gene therapy, atherosclerosis, anti-inflammation, and immune modulation in patients with cardiovascular diseases.