Studies conducted on mice have shown that scratching the skin triggers a series of immune responses, which ultimately leads to more mast cells (immune cells involved in allergic reactions) in the small intestine being activated. This newly discovered communication between the skin and the intestine helps to clarify the relationship between food allergies and atopic dermatitis (a type of eczema).
This research was supported by the National Institute of Allergy and Infectious Diseases (NIAID) under the National Institutes of Health, which is led by researchers from Boston Children's Hospital. Atopic dermatitis is an important risk factor for food allergy, but the exact relationship between the two conditions is still unknown. People with this disease, especially babies, often scratch their skin because itching is the main symptom of atopic dermatitis. Current research shows that scraping the skin can cause the intestinal mast cells to swell. Researchers found that certain cells in the skin smear and remove small pieces of mouse skin by producing a cell signaling protein called IL-33 in the blood, similar to scratching. I found it responsive. When IL-33 reaches the intestine, it works in concert with IL-25, a protein secreted by cells in the intestinal lining, to activate type 2 natural lymphocytes (ILC2).
"Activated ILC2 produces two other cell signaling proteins, IL-13 and IL-4, which have been shown to be involved in the proliferation of intestinal mast cells. Researchers also found that the expansion of mast cells promotes the penetration of the intestinal lining and makes it easier for allergens to enter the tissues. It is worth noting that the mice that received the tape stripping had more severe reactions to food allergens than the untouched mice. Finally, the researchers found that the intestinal biopsies of the four children with atopic dermatitis contained more mast cells than the four unaffected children.
More work is needed to determine the relevance of the research results to humans, but researchers believe that interventions to control itching can reduce the severity of food allergies in patients with atopic dermatitis.