Psychological stress is known to exacerbate skin allergies, but the underlying molecular mechanisms remain poorly understood. Recent studies using a mouse model of immunoglobulin E (IgE)-mediated cutaneous allergic inflammation (IgE-CAI) suggest that stress may disrupt immune functions, thereby worsening allergic symptoms by interfering with the body’s inflammatory responses. IgE-CAI is characterized by swelling and infiltration of eosinophils, a type of immune cell involved in allergic inflammation, at the affected site.
In a recent study, a research group led by Associate Professor Soichiro Yoshikawa, Professor Kenji Takamori, and Professor Sachiko Miyake from the Juntendo University Graduate School of Medicine, along with Dr. Hitoshi Urakami and Professor Shin Morizane from the Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, explored the link between stress and allergic symptoms. Their study was published online on November 18, 2024, in The Journal of Allergy and Clinical Immunology.
The study revealed that psychological stress reduces the ability of specialized cells called anti-inflammatory programmed death ligand 2 (PD-L2)-positive macrophages, to clear dead cells at the allergy site, thereby exacerbating skin allergy symptoms. “This study is the first in the world to demonstrate that stress, through the sympathetic nervous system, disrupts macrophage function, which normally helps suppress allergic reactions, thereby intensifying allergic responses,” explains Dr. Yoshikawa.
To investigate the mechanism linking stress to skin allergies, the researchers used a mouse model, IgE-CAI, where injection of IgE caused persistent ear inflammation. The team first identified the neural tissue involved in IgE-CAI and then investigated the immune