Microbial triggers in autoimmunity, severe allergy, and autoallergy

The prevalence of immune-mediated diseases (allergies, autoimmune diseases, and autoinflammatory diseases) is rising world-wide and their management is difficult, since treatments usually are mainly symptomatic. Insight in the exact pathomechanisms is crucial for focused prevention or improvement of therapies. Microbial factors including bacteria (mainly Staphylococcus aureus), viruses and fungi are important factors in atopic dermatitis. Allergic asthma is also heavily impacted by Staphylococcus aureus, but also by multiple viruses. Viral complications in severe allergies can lead to life-threatening disease states. In autoimmunity, many viruses and bacteria play a role in disease development due to molecular mimicry or bystander activation. Furthermore, it is hypothesized that autoallergy can link allergy, chronification of disease, and autoimmunity. Here, fungal triggers are suspected to elicit autoreactive IgE and T helper 1 responses in atopic dermatitis, which can maintain a vicious inflammatory cycle due to constant autoallergen release by scratching. Taken together, multiple microbial factors elicit or aggravate immune mediated diseases, such as allergies and autoimmunity.