Atopic dermatitis, the most common form of eczema, could be treated with a protein known to protect the fetus against attack from the mother's immune system during pregnancy, a new study suggests.
Researchers from Japan found that the protein, called human leukocyte antigen-G1 (HLA-G1), significantly improved skin lesions in mice with atopic dermatitis.
What is more, HLA-G1 was found to reduce immune system activity among rodents in response to dust mites, a common allergen for atopic dermatitis.
Study co-author Prof. Katsumi Maenaka, of the Faculty of Pharmaceutical Sciences at Hokkaido University in Japan, and colleagues recently reported their findings in the journal International Immunopharmacology.
Atopic dermatitis is a chronic form of eczema, which is an inflammatory skin condition characterized by rashes - particularly on the face, hands, feet, and behind the elbows and knees - and dry, itchy skin.
The symptoms of atopic dermatitis can be triggered by exposure to a number of irritants and allergens, including dust mites, pet dander, mold, pollen, cigarette smoke, and certain foods.
According to the American Academy of Dermatology, atopic dermatitis is estimated to affect at least 28 million people in the United States. The condition is most common among infants and children; around 90 percent of people with atopic dermatitis develop it before the age of 5 years.
HLA-G1 reduced immune response in mice
There is currently no cure for atopic dermatitis, but there are treatments to help manage the condition. These include medications such as corticosteroids, good skincare routines, and drugs that curb the immune system response.
The new study from Prof. Maenaka and team may have identified another strategy to help treat allergic responses in atopic dermatitis: topical administration of HLA-G1.
HLA-G1 is a form of the HLA-G protein, which previous research has linked to fetal protection from maternal immune system attacks during pregnancy.
To test whether HLA-G1 might help to dampen the immune response in atopic dermatitis, the researchers tested the protein on mice with the condition.
To induce symptoms of atopic dermatitis in the mice, the researchers exposed them to dust mites for 15 days. This led to bleeding, dry skin, and scarring on the rodents' ears.
The researchers then treated some of the mice with HLA-G1 by applying the protein to their ears every other day for a total of 20 days.
The team found that mice treated with HLA-G1 not only showed a significant improvement in skin lesions, but blood samples from the rodents revealed that their immune responses had been reduced, compared with untreated mice.
Unlike some current treatments for atopic dermatitis, the researchers note that HLA-G1 did not trigger weight loss.
Possible treatment for inflammatory diseases
Overall, the results suggest that HLA-G1 may offer a safer, more effective treatment option for atopic dermatitis, and it may also lead to treatments for other inflammatory diseases.
"Our study provides novel insights on the function of HLA-G proteins, which can provide clues on efficient therapeutic strategies for patients with atopic dermatitis, rheumatoid arthritis, and other related diseases."
Prof. Katsumi Maenaka
"Further investigation is needed to better understand HLA-G's suppressive mechanism against excessive immune reactions," he adds.