Figure 2.

Biota alteration and its connection with chronic, inflammation-associated diseases

In this model, loss of complex eukaryotic symbionts leads to altered immune regulation, particularly impaired ability to achieve tolerance to self and environmental antigens. This condition, when combined with (1) other environmental mismatches, (2) “triggers” such as viral infections, and (3) genetic and epigenetic factors, leads to chronic inflammation-associated disease. In this case, “systems hygiene” is defined as factors such as sewage treatment facilities, clean water utilities, and food storage technology that effectively prevent water-borne disease.³ Although systems hygiene causes biota alteration and subsequent risks for immune dysregulation, personal hygiene can decrease exposure to some triggers for chronic disease, including insect-derived antigens and viral infections.^3,34,35,36