In a new study, researchers found that a group of tiny RNA that should attack the virus causing COVID-19 when it tries to infect the body are diminished with age and chronic health problems.
The decrease may help explain why older individuals and those with pre-existing medical conditions are vulnerable populations.
The research was conducted by a team at Augusta University.
MicroRNAs play a big role in our body in controlling gene expression, and also are a front line when viruses invade, latching onto and cutting the RNA, the genetic material of the virus.
But with age and some chronic medical conditions, the attacking microRNA numbers dwindle, reducing our ability to respond to viruses.
Much like not having enough troops on the ground in an actual war, the coronavirus is then better able to do what it does naturally, which is hijacking our cell machinery so it can replicate.
In the study, the team looked at the RNA sequence of actually two coronaviruses, SARS, which surfaced in 2002, and SARS-CoV-2, which causes COVID-19, and the sequence of the microRNAs that appeared to be attacking the virus.
Their data included four samples of SARS and 29 samples of SARS-CoV-2, taken between January and April 2020 from five continents covering 17 countries from the United States to Germany to Thailand.
They found 848 microRNAs that target the SARS genome and 873 microRNAs that target SARS-CoV-2 genome.
In addition, 558 of the microRNAs fighting SARS also present in SARS-CoV-2, while 315 microRNAs were unique to SARS-CoV-2, and 290 were unique to SARS.
MicroRNAs most proficient at attacking SARS-CoV-2 showed more than 10 target sites and might ultimately be found to be the most proficient at fighting the virus, which, in a few months, has changed much of the way the world functions.
The team also found the microRNAs targeting SARS-CoV-2 were linked to more than 72 biological processes—from the production of molecules to the immune response—and that many are known to become dysregulated and/or diminish in number with age and with underlying medical conditions like diabetes and cardiovascular disease, a likely factor in the increased disease presentation and death rates seen in these individuals, the investigators say.
In the 29 worldwide samples of SARS-CoV-2, 19 had identical microRNAs, which indicates the virus has a fairly uniform presence internationally and that any effective treatments or vaccines should have a broad impact.
The team says there is a key set of microRNAs that are important in triggering this abnormal response, in making older patients more susceptible.
Cocktails of multiple key microRNA, potentially given through the nose, might help restore sufficient levels of the key virus fighters, the researchers say.
People age 65 and older and people of any age with underlying medical conditions are considered at higher risk for severe illness from COVID-19, according to the Centers for Disease Control and Prevention.
Underlying medical conditions include problems like serious heart conditions, chronic lung disease and moderate to severe asthma, and people with a compromised immune system such as individuals with cancer or who have had an organ transplant, the CDC says.
Obesity, diabetes, chronic kidney disease requiring dialysis, and liver disease are among the other conditions.
One author of the study is Dr. Sadanand Fulzele, an aging researcher in the Department of Medicine and Center for Healthy Aging at the Medical College of Georgia.
The study is published in Aging and Disease.
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