At the height of the first waves of SARS-Cov2, men were more often in ICU beds than women. The pandemic has shown that they fight off Covid-19 better than their male counterparts thanks to a more effective immune response to this infection. This is also the case with other viruses such as influenza or HIV.
According to a recent study by a joint team of Inserm, CNRS, Toulouse III – Paul-Sabatier University and Toulouse University Hospital, published in the journal eBioMedicineHormonal and genetic factors may explain this difference, and it continues to play a role even in older women.
We already knew that when an RNA virus attacks, cells called pDCs are able to detect their presence thanks to their TLR7 receptor. They also react to defend themselves and release cytokines into the blood, particularly those known as type I interferon, an army of powerful antiviral molecules, quickly to prevent the virus from reproducing.
When you activate this TRL7 receptor, women generally produce more interferon than men. Gene Charles Geary, director of Inserm Research, and co-author of the study, recalls that the TRL7 gene is on the X chromosome, in duplicate in women. If this mechanism of immunity is known, studies to date have relied on fairly young subjects, less than 60 years old. However, if age is an aggravating risk factor, older patients always resist better than men of their generation.
After closely examining a group of 310 apparently healthy women and men between the ages of 19 and 97, the researchers took a closer look at interferon production when the TRL7 receptor is affected by the presence of viruses. We observed that this immune response persisted with age. Even in people over 80 years old, there was more interferon in women than in men. At an advanced age, sexism persists, and women will better control the virus during the early stage, when they produce more interferon. This time it involves a mechanism that is no longer related to estrogen, the production of which decreases with age, but possibly due to genetic influences”, continues Jean-Charles Gerry.
Clinical study to test an antiviral booster
Now that we’ve decoded how the immune response is set up, scientists will try to use it to successfully activate it and thus give better weapons to infected people. Thus, a clinical trial could be conducted in Toulouse in the coming weeks on a molecule developed by an American company.
This should enhance the production of interferon in the elderly. We are trying to see if there is a response in people who take this molecule, and to bolster their immune defenses. It can be against Covid, but also against seasonal influenza,” concludes Jean Charles Giri.
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