Nov. 27, 2023 – Scientists have a promising new theory of what causes the sensation of itching, and their latest laboratory experiments point toward potentially effective treatments for people who have itchy skin due to eczema or dermatitis.
In a study published this month by the journal Cell, researchers reported that directly exposing the skin of mice to the bacteria Staphylococcus aureus triggered the nervous system to send signals from the skin to the brain. Lab experiments were also conducted using human cells.
S. aureus is so common that about 30% of people carry the bacteria in their nose and usually it does not cause any harm, the CDC says. But in people who have skin conditions like eczema or dermatitis, the balance of microorganisms that keeps skin healthy is disrupted, potentially making people who have the skin conditions more susceptible to S. aureus, according to a summary of the research published by Harvard Medical School. The new findings point scientists and medical researchers away from the previously held theory that itchiness from eczema and dermatitis stemmed from inflammation caused by those conditions.
“We’ve identified an entirely novel mechanism behind itch — the bacterium Staph aureus, which is found on almost every patient with the chronic condition atopic dermatitis. We show that itch can be caused by the microbe itself,” said senior author Isaac Chiu, PhD, associate professor of immunobiology at Harvard, in a statement.
The mice that were exposed to S. aureus developed intensifying itchiness for several days, and they also developed an itch-scratch cycle that eventually resulted in damage to the skin beyond the site of the itch. The researchers were able to block the nervous system’s process that results in the itching sensation by using a medicine that’s usually used to help people who have problems with blood clots. The findings suggest that the medicine could be repurposed as an anti-itch treatment.
The researchers plan to explore whether other microbes beyond S. aureus can trigger itch.