Nov 23, 2023 - Health

Scientists make breakthrough discovery in research into what causes an itch

At The Department Of Dermatology At The Bocage Hospital, University Hopital Of Dijon, a consultation In Pediatrics For Eczema On A 7 Month Old Child.

A doctor in Dijon, France, examines a baby during a consultation for eczema. Photo: BSIP/UIG Via Getty Images

Scientists researching what causes an itch in skin conditions such as eczema and dermatitis have made a major breakthrough.

Why it matters: The research that has for the first time shown that bacteria can cause itch by activating nerve cells in the skin could help with treating itches that occur in inflammatory skin conditions, per Harvard Medical School scientists whose study was published in the journal Cell on Wednesday.

  • "Up until now, the itch that occurs with eczema and atopic dermatitis was believed to arise from the accompanying inflammation of the skin," per a statement accompanying the study. But the new findings show that S. aureus, a common bacterium, "single-handedly causes itch" by releasing an enzyme that "culminates in the urge to scratch."

By the numbers: About 31.6 million people in the U.S., or 10.1% of the population, have some form of eczema, with the prevalence peaking during early childhood, according to the National Eczema Association.

The big picture: The scientists based their research in mice and in human cells.

  • A key finding occurred when the scientists discovered that using an already approved anticlotting drug that blocks a protein called PAR1 stopped itching in mice.
  • "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," said study co-author Isaac Chiu, an associate professor of immunology at Harvard Medical School.
  • "We show that itch can be caused by the microbe itself."

Between the lines: Brian Kim, a physician-scientist at Icahn School of Medicine at Mount Sinai, who was not involved in the study, told Stat News this was among the first research to show a "clear mechanism" between itching and bacteria.

  • "It kind of makes you wonder ... what else did we miss?'"
  • While some experts said more studies in humans were needed, Emma Wedgeworth, a consultant dermatologist, hoped the breakthrough "will translate into new treatment options helping to tackle the misery of itch and eczema," per The Guardian.

What's next: The researchers plan to examine whether microbes other than S. aureus can trigger itch, per the Harvard statement.

  • "We know that many microbes, including fungi, viruses, and bacteria, are accompanied by itch but how they cause itch is not clear," Chiu said.
  • And the researches said they could in the future follow up on the broader question: Why would a microbe cause itch? Evolutionarily speaking, what's in it for the bacterium?
Go deeper