Harvard Researchers Discover Cause of Itching

The mystery about why some people are itchier than others may have been solved by Harvard Medical School researchers. They discovered that a common skin bacterium, Staphylococcus aureus, triggers itching by acting on nerve cells.

According to Study Finds, this discovery may explain why constant, intense itching often accompanies skin conditions like eczema. On experiments on mice, the researchers found that the bacterium intensified their itch. The scientists isolated a specific bacterial enzyme that activates a protein involved in blood clotting which causes itching. When they administered an existing anticlotting drug to the mice, it stopped their itch.

Published in the journal Cell, the study findings suggest that this anticlotting drug could be a key ingredient in the development of anti-itch creams. Previously, experts thought that the itching that accompanies certain skin conditions was due to inflammation. The new findings indicate that S. aureus alone can trigger the itch through a molecular chain reaction that leads to the urge to itch. The research adds an important piece of the puzzle to the uncomfortable dilemma of itching, and helps explain why skin conditions like eczema and atopic dermatitis are accompanied by persistent itch.

It appears that in these conditions the equilibrium of microorganisms that keep our skin healthy is often thrown off balance, allowing S. aureus to flourish, the researchers said.

“We’ve identified an entirely novel mechanism behind itch — the bacterium Staph aureus, which is found on almost every patient with the chronic skin condition atopic dermatitis. We show that itch can be caused by the microbe itself,” said senior author Isaac Chiu, an associated professor of immunology in the Blavatnik Institute at Harvard Medical School, according to a news release.

The scientists found that PAR1, the protein activated by S. aureus, is involved in blood clotting. So, they treated the mice with an approved anti-clotting drug that blocks PAR1. It stopped the mice from itching. Their desire to scratch diminished dramatically, as did the skin damage caused by itching.

The PAR1 blocker is already used in humans to prevent blood clots and could be repurposed as an anti-itch medicine, according to the university press release. For example, the researchers noted, the active ingredient in the medicine could become the basis for an anti-itch cream.