Researchers might have finally scratched below the surface of this medical mystery.
Itchiness is a common symptom of various skin conditions, but why that is has long been unclear — until now.
A new study out of Harvard Medical School may offer some answers — and relief — for patients with eczema, an inflammatory skin condition affecting over 31 million Americans.
Their findings, published Wednesday in the journal Cell, fingered Staphylococcus aureus, a common bacterium found on the skin, as the culprit.
“We’ve identified an entirely novel mechanism behind itch — the bacterium Staph aureus, which is found in almost every patient with the chronic condition atopic dermatitis [eczema]. We show that itch can be caused by the microbe itself,” said author Isaac Chiu, an associate professor of immunology at the school’s Blavatnik Institute, in a statement. “We show that itch can be caused by the microbe itself.”
In laboratory mice, researchers found that the bacterium caused an intense itch by activating a protein called V8, which is responsible for sending touch sensations to the brain and triggering the feeling of pain, heat and, you guessed it, itch.
That same protein also plays a key role in blood clotting. Thus, researchers hypothesized, that perhaps anti-clotting medication could prevent this process from occurring — ergo, no itch.
And it worked.
Further testing on human cells showed parallel results. Skin samples from patients with atopic dermatitis yielded a higher prevalence of S. aureus and levels of V8 compared to healthy skin.
Now, researchers believe that anti-clotting medications, which satisfied the rodents’ itch, could become the norm for treating the uncomfortable symptom in people.
“Itch can be quite debilitating in patients who suffer from chronic skin conditions,” said the study’s co-author, Dr. Liwen Deng.
But scratching the insatiable itch, researchers found, resulted in skin damage — and even more itch — that spread to other areas. The mice also experienced alloknesis, hypersensitivity to external stimuli that wouldn’t normally be irritating — say, for example, wearing a wool sweater.
Experts previously believed the itching was a result of inflammation, but the new research suggests that inflammation isn’t necessary to be itchy, although it may certainly “exacerbate” it.
The team believes that the bacterium thrives when the equilibrium of a person’s skin is off-kilter, and they now want to investigate whether other microbes cause such an itch, and if it could have benefits.
“It’s speculation at this point, but the itch-scratch cycle could benefit the microbes and enable their spread to distant body sites and to uninfected hosts,” said Deng.
“Why do we itch and scratch? Does it help us, or does it help the microbe? That’s something that we could follow up on in the future.”