Common anti-inflammatory drugs may aid virus spread

New research shows an unintended and unfortunate side effect of common drugs. They can simply help viruses spread.

Drugs are supposed to help us get rid of disease, or at least alleviate the symptoms of them. It is therefore particularly unfortunate when, on the contrary, the drugs can contribute to making us sicker. Many medications can have side effects, but some are particularly serious.

We have found a surprising and potentially serious side effect of a class of anti-inflammatory drugs. They can help viruses spread more easily in the body."

Denis Kainov, Professor, Department of Clinical and Molecular Medicine.Norwegian University of Science and Technology (NTNU)

Influenza, COVID-19 and other viruses spread more easily

These drugs, which can make the body extra vulnerable to viral infections, are widely used. They are known as Janus kinase inhibitors, or JAKs.

"Among the viruses that more easily affect the body with the help of these drugs are Rift Valley fever virus, influenza A, adenovirus and SARS-CoV-2, the virus that causes COVID-19," Kainov says.

These are both serious and common viral infections that can be bad enough without the inadvertent help of medications.

Drugs used for autoimmune diseases and arthritis

In a new article in NAR Molecular Medicine, Kainov and colleagues describe how the drugs can promote viral infections.

"JAK inhibitors are often prescribed for autoimmune diseases and inflammatory conditions such as rheumatoid arthritis," says Erlend Ravlo, a PhD research fellow at NTNU and first author of the article.

But they also weaken the body's natural defences against viruses.

"In particular, the drugs suppress an important immune signalling pathway that helps protect healthy cells from viral attacks," Ravlo said.

Inhibits important gene response against viruses

The researchers found that drugs such as baricitinib slow down the genes that respond to viral infections.

"These genes play a crucial role in the body's response to viral infections," said Aleksandr Ianevski, an NTNU researcher and coauthor of the new paper.

By stopping or slowing down this signalling pathway, JAK inhibitors remove the body's antiviral shield. Then viruses can more easily gain a foothold and spread.

The researchers used advanced techniques in virology, organoid technology and gene expression analysis. They examined cells from the lungs, eyes and brain, as well as in laboratory-created mini-organs.

"Although JAK inhibitors are effective in the treatment of inflammation, this shows that they can pose a hidden risk for patients who have latent or active viral infections," says Ravlo.

Can be useful to know during the development of medications

The findings suggest that healthcare professionals should be cautious when prescribing JAK inhibitors, especially during viral outbreaks.

But the researchers point out that this immunosuppressive effect may also be useful in controlled environments, such as in the development of vaccines or screening of antiviral drugs.

The researchers hope to increase awareness among doctors and researchers about the effects of these drugs.

"We recommend further studies to better understand how the drugs can be used optimally, especially during virus outbreaks or pandemics," says Ianevski.

Professor Magnar Bjørås at the Department of Clinical and Molecular Medicine contributed important professional knowledge and most of the funding of the research. The study was also funded by the Central Norway Regional Health Authority, the South-Eastern Norway Regional Health Authority, the Research Council of Norway and the Swedish Research Council.