Getting an itch is one thing. Everybody has to scratch every now and then, and some of us have to watch out for dry skin during the winter, or allergic reactions to ingredients in certain makeup or lotions. Yet for most of us, those discomforts involve itches on parts of our skin that have hair, not on what is called ‘glabrous’ skin: the smoother, tougher skin that’s found on the palms of your hands and the soles of your feet.
And those glabrous skin conditions often cause chronic itching and pain. In the U.S., there are an estimated 200,000 cases of dyshidrosis, a skin condition causing itchy blisters to develop only on the palm and soles, each year. Another chronic skin condition, palmoplantar pustulosis (a type of psoriasis which causes inflamed, scaly skin and intense itch on the palms and soles) affects an estimated 330,0000 to 1,650,000 people in the U.S. each year.
“Those patients with chronic itch suffer a lot. They don’t have a significant treatment, and it affects their lives,” says Liang Han, an assistant professor in the School of Biological Sciences who also researches in the Parker H. Petit Institute for Bioengineering and Bioscience. Now, new research from Han and students in her Han Lab at Georgia Tech may offer a balm of hope for these patients.
"MrgprC11+ sensory neurons mediate glabrous skin itch,” published in the science journal PNAS (Proceedings of the National Academy of Sciences of the United States of America), is co-authored by Han alongside current and former graduate students Haley R. Steele (first author), Yanyan Xing, Yuyan Zhu, Henry B. Hilley, Katy Lawson, Yeseul Nho, and Taylor Niehoff.
Han and her students uncovered new information about which sensory neurons are responsible for glabrous skin itch. “We here present evidence demonstrating that distinct neuronal populations are responsible for mediating hairy and glabrous skin itch,” the authors write. “This study advanced our understanding of itch and will have significant impact on the clinical treatment of itch.”
Steele adds more: “Our research is showing, for the first time, the actual neurons that send itch are different populations. Neurons that are in hairy skin that do not sense itch in glabrous skins are one population, and another senses itch in glabrous skins.”