Researchers at Vanderbilt University Medical Center (VUMC) and their colleagues may have found a key as to why COVID-19 primarily infects adults and older people, but has a much lesser impact on children.
VUMC researchers found that children have lower levels of an enzyme/co-receptor that SARS-CoV-2 — the RNA virus that causes COVID-19 — needed to invade airway epithelial cells in the lung. Finding ways to block the enzyme could lead to potential treatments or even prevention of COVID-19 in older people, they reported.
“Our study provides a biologic rationale for why particularly infants and very young children seem to be less likely to either get infected or to have severe disease symptoms,” said Dr. Jennifer Sucre, assistant professor of pediatrics (neonatology), who led the research with Dr. Jonathan Kropski, assistant professor of medicine.
According to the study, “after a viral particle is inhaled into the lungs, protein ‘spikes’ that stick out like nail studs in a soccer ball attach to ACE2, a receptor on the surfaces of certain lung cells. Then, a cellular enzyme called TMPRSS2 chops up the spike protein, enabling the virus to fuse into the cell membrane and ‘break into’ the cell. Once inside, the virus hijacks the cell’s genetic machinery to make copies of its RNA.”
“What we found is that expression of (TMPRSS2) goes up significantly with aging, and we see that at the level of the gene and at the level of the protein,” Sucre said. “We see a lot more TMPRSS2 in older individuals, in both humans and mice … We do think TMPRSS2 could be an attractive target both in treatment and potentially as a prophylaxis for (preventing infection in) people at high risk of COVID exposure.”.
Source: Newswise November 12, 2020