COVID-19 and Telomeres

2020 and 2021 will be marked in history by the COVID-19 pandemic. As of late March, close to 3,000,000 people had died due to SARS-CoV-2. To put this number in perspective, the fatality of this virus mimics the death toll of the Thirty Years War back in 1618 and is already higher than the Vietnam War in 1955.

SARS-CoV-2 is a novel coronavirus of the genus Betacoronavirus, initially discovered in Wuhan in late December of 2019, that causes an infection with fibrosis-like phenotypes in the lungs and kidneys. COVID-19 causes mild flu-like symptoms in 75% of cases, but it can be deadly by leading to severe multi-organ failure. Of special importance is the dramatic effect of this virus on the elderly, with a 15% death rate in people over 85 years old. Furthermore, males seem to be more vulnerable to suffering a more severe COVID-19 response than females of similar ages. The question that arises is, what do males and elderly people have in common that make them sicker after having contracted SARS-CoV-2? The answer could be telomere length.

Telomeres are DNA repeats at the end of the chromosomes that protect the genome from a wide array of aberrations. Most cells have a lifespan of 45-50 divisions, after which they undergo apoptosis (the cells kill themselves) to counteract the progressive shortening of telomeres that naturally occurs and leads to senescence. Therefore, as we age, our telomere length decreases. Interestingly, females have longer telomere length in general with respect to same-age males, an effect not clearly understood yet.

In a recent study published in the journal Aging, 89 people representing a wide array of ages were hospitalized in Madrid due to COVID-19 symptoms. As expected, older people experienced a more severe response to COVID-19. People with shorter telomeres were sicker than the patients with longer chromosome ends (that is, for similar age individuals). Furthermore, females, with longer telomeres on average with respect to males, displayed milder symptoms. 

This clinical study undertaken by Maria Blasco’s lab in Spain highlights the correlation between the severity of COVID-19 pathologies and telomere length. It is important to know that previous findings already highlight that short telomeres are at the origin of pulmonary fibrosis, and telomerase gene therapy in mice has been shown to stop the progression of this disease. Whether gene therapy could be used to diminish the severity of COVID-19 is unclear. However, I believe this information is really valuable to further understand the ins and outs of this devastating disease.

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