Melatonin may Help Prevent COVID-19

The melatonin hormone acts as a barrier against the SARS-CoV-2 virus by blocking the expression of genes that encode proteins in cells serving as viral entry points.

Genes that are responsible for encoding the proteins in cells such as resident macrophages in the nose and pulmonary alveoli, and epithelial cells lining the alveoli, all of which serve as entry points for the virus.

The Melatonin synthesized in the lungs can act as a barrier against SARS-CoV-2 and prevent the infection of these cells by the virus and inhibit the immune response. This leaves the virus remain in the respiratory tract for a few days, eventually leaving to find another host, as per the study at the University of São Paulo (USP), in Brazil, published in the journal Melatonin Research.

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‘The melatonin hormone acts as a barrier against the SARS-CoV-2 virus by blocking the expression of genes that encode proteins in cells serving as viral entry points. Thus nasal administration of melatonin, in drops or as a spray, may help prevent the COVID-19 disease from developing in pre-symptomatic patients. However, more research is required to prove the efficacy in humans.’

This helps us understand the reason why some people are not infected or do not manifest symptoms of COVID-19 even when reliably diagnosed as carriers of the virus by RT-PCR.

"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. This action mechanism by pulmonary melatonin must also involve other respiratory viruses such as influenza," says Regina Pekelmann Markus, a professor at USP's Institute of Biosciences (IB) and principal investigator for the project.

Melatonin in COVID-19

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Melatonin is a hormone produced by the pineal gland in the brain at night, to mark the cessation of daylight. This helps the body prepare for sleep. The hormone can also be produced in other organs, such as the lungs.

Earlier the author had demonstrated that the melatonin produced in the lungs, alters the entry points for particulate matter from air pollution. The idea was incorporated to explore the same result in the case of the SARS-CoV-2 virus, which would hinder the virus to bind to the ACE-2 receptor on cells and epithelium, eventually stopping the COVID-19 infection.

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Out of 455 genes that are associated with COVID-19 in humans, 212 genes from 288 healthy human lung samples were selected by the team to quantify the COVID-19 signature genes level of expression. This was done using RNA sequencing data downloaded from a public database.

The Pulmonary Melatonin Metric

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Correlation of these gene expression levels was done using a gene index that estimated the capacity of the lungs to synthesize melatonin (MEL-Index). It was found that the lower gene index related to the higher the level of expression of genes that encode proteins for resident macrophages and epithelial cells.

A negative correlation between the genes that modify proteins in cell receptor CD147 – a viral entry point in macrophages and other immune cells, indicates that normal lung melatonin production may be a natural protector against the virus.

"We found that when MEL-Index was high the entry points for the virus in the lungs were closed, and when it was low these 'doors' were open. When the doors are shut, the virus wanders around for a time in the pulmonary airspace and then tries to escape in search of another host," says Markus.

The study thereby suggests that nasal administration of melatonin, in drops or as a spray, may help prevent the COVID-19 disease from developing in pre-symptomatic patients. Also the MEL-Index, the pulmonary melatonin metric, can be used as a prognostic biomarker to detect asymptomatic carriers of SARS-CoV-2. However, more research is required to prove the efficacy in humans.

Source-Medindia