Melatonin could act as barrier against COVID-19 infection

According to a new study, published in Melatonin Research, melatonin synthesised in the lungs could act as a barrier against SARS-CoV-2, preventing expression of genes that encode proteins in cells such as resident macrophages in the nose and pulmonary alveoli and epithelial cells lining the alveoli, all of which are entry points for the virus.

The hormone, therefore, would prevent infection of these cells by the virus and inhibit the immune response so that SARS-CoV-2 remains in the respiratory tract for a few days, eventually leaving to find another host.

The discovery by researchers at the University of São Paulo (USP), Brazil, offers the prospect of nasal administration of melatonin, in drops or as a spray, to prevent the disease from developing in pre-symptomatic patients. 

"We showed that melatonin produced in the lung acts as a barrier against SARS-CoV-2, preventing the virus from entering the epithelium, activating the immune system and triggering the production of antibodies," said Professor Regina Pekelmann Markus, principal investigator for the project. "This action mechanism by pulmonary melatonin must also involve other respiratory viruses such as influenza."

Previous research from the team showed that in rodents, the hormone, produced at night by the pineal gland in the brain, can be produced in other organs, such as the lungs.