A collaborative research team led by Tohoku University (such as Shinshu University) has elucidated a part of the mechanism by which air pollutants cause various symptoms of atopic dermatitis.The development of new therapeutic agents to control itching is expected.This achievement was published in the online version of the British scientific journal "Nature Immunology" (November 11, Japan time).

　Atopic dermatitis is a chronic itchy dermatitis found in people with allergies, and the number of patients is increasing worldwide, and it is said that it is related to air pollution, but the reason is unknown.However, air pollutants contain a component called AhR that activates a transcription factor (a protein that binds to DNA and controls gene expression), and in fact, AhR is produced in the epidermis exposed to air pollutants. It was also known that constitutively activated mice (AhR activated mice) develop chronic dermatitis.Therefore, the research team investigated the relationship between AhR activation by air pollution and atopic dermatitis.

　As a result, air pollutants activate the transcription factor AhR to express a neurotrophic factor called artemin (a general term for proteins that promote nerve survival, growth, and differentiation), and nerves extend into the epidermis of the skin surface. It was found to create a condition in which itching is easily felt.The researchers believe that scratching the skin due to excessive itching destroys the skin barrier and allows many antigens to invade through the skin, causing allergic dermatitis.

　Currently, the main treatment for atopic dermatitis is symptomatic treatment with steroids, but itching may not be relieved during treatment rather than improving the cause.From this result, it is possible to develop a new therapeutic drug targeting itching of atopic dermatitis by a substance that suppresses the activity of AhR and the action of artemin.It is expected that symptom relief will be facilitated when used in combination with existing therapeutic agents.