Aging linked to decline in cells that control itch response
From the WashU Newsroom…
For some people, particularly those who are elderly, even a light touch of the skin or contact with clothing can lead to unbearable itching. What’s worse, anti-itch treatments, including hydrocortisone, don’t provide much relief for this type of itching.
Now, researchers at Washington University School of Medicine in St Louis have discovered, in mice, why a touch can cause such severe itching and, in the process, identified some possible therapeutic targets.
Their research, published May 4 in the journal Science, indicates that itching caused by touch is directly related to the number of touch receptors embedded in the skin. The fewer the receptors, the more likely it is that touching will induce itching.
“Itching caused by touch becomes more common as we age and is especially problematic for people with dry skin or who already suffer from chronic itching,” said senior investigator Hongzhen Hu, PhD, an associate professor of anesthesiology who conducts research as part of the university’s Center for the Study of Itch. “It can be more than a nuisance, and there are no drugs available to treat this type of itching, so we wanted to identify the underlying causes in hopes of finding better ways to treat it.”
Studying mice, the scientists discovered that the number of touch receptors called Merkel cells in the skin declined as the animals aged. They also found fewer of these touch receptors in animals with dry skin. Not having as many Merkel cells made itch problems more likely when the animals were poked with a hairlike nylon device that scientists use to study itch responses.
“As the number of Merkel cells went down, problems with touch-related itch went up,” Hu said. “What exactly Merkel cells do has not been clear, but our findings suggest they help control the itch response. When you lose these cells, their ability to inhibit itch also is lost.”