MicroRNAs attacking SARS-CoV-2 diminish with age and chronic health problems


Those aged 65 and older and anyone with an underlying medical condition, including heart conditions, asthma and diabetes, have been classified by the Centres for Disease Control and Prevention (GA, USA) as being more at risk of developing severe illness from COVID-19 infections. Researchers from Augusta University (GA, USA) and the University of Florida (USA) have discovered that a potential explanation for this increased risk could be that microRNAs that should attack SARS-CoV-2 when it invades the body are diminished in the elderly and those with chronic health conditions.

MicroRNAs are at the frontline of the body’s immune defense against viruses, latching onto and cutting the viral RNA to induce an antiviral effect. When they are in short supply, the virus is able to replicate more freely and cause more severe illness.

In a recent study, published in Aging and Disease, the researchers performed an in silico analysis of human microRNAs that target the genomes of SARS and SARS-CoV-2. Their analysis included four samples of SARS and 29 samples of SARS-CoV-2, taken between January and April 2020 from five different continents.

The researchers identified 848 microRNAs that target the SARS genome and 873 microRNAs that target the SARS-CoV-2 genome. Of these, 588 targeted both viruses, while 315 and 290 were unique to SAR-CoV-2 and SARS, respectively. Upon correlating their results with age and underlying health conditions, they observed a reduction in the number of key microRNAs in those most vulnerable.

The microRNAs identified as targeting the SARS-CoV-2 genome are associated with over 72 biological processes, many of which are already known to become dysregulated in line with age and the presence of chronic disease. The researchers believe this is likely to contribute towards the susceptibility of these groups to COVID-19.

The results from this study have also provided a potential new avenue for treatment of COVID-19. Synthetic microRNAs could potentially help to restore levels of key microRNAs in the most vulnerable, helping them to ‘naturally’ fight off the disease.

More studies are in the pipeline to validate some of these targets and identify which microRNA would be most successful as a therapeutic option. The researchers also hope to investigate whether younger people infected with COVID-19 also have diminished levels of these microRNAs.

Sources: Sadanand F, Bikash S, Ibrahim Y et al. COVID-19 virulence in aged patients might be impacted by the host cellular microRNAs abundance/profile. Aging Dis. 11(3), 509-522 (2020); https://jagwire.augusta.edu/tiny-rna-that-should-attack-coronavirus-diminish-with-age-disease/

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