Comparison of the effect of autoclaved and non-autoclaved soil exposure on mouse immune system

Abstract

Abstract The biodiversity hypothesis suggests that decreased interaction with microbes can lead to an imbalance in the human microbiota (referred to as dysbiosis), which in turn will contribute to the development of immune-mediated diseases including asthma, allergies, and autoimmune diseases such as type 1 diabetes. We have previously utilised a novel approach of bringing humans and mice into contact with microbially rich plant- and soil-based material. In humans, exposure to this material increased commensal microbial diversity in daycare children which also linked to higher levels of anti-inflammatory cytokines TGF-b and IL-10 in plasma. Here, we compared the effects of autoclaved and non-autoclaved, fresh soil powder on the mouse immune system, to understand if soil-derived material contains molecular structures that convey the immunoregulatory signals. These effects were evaluated phenotyping immune populations by flow cytometry, assessing cytokine profiles in serums and microbiome diversity by genetic sequencing. Our results indicate that exposure to non-autoclaved soil did not influence the health of mice but was associated with elevated serum IFN-g expression, and reduction of GATA-3 and Foxp3 expression in mLNs. The observed immunological effects warrant further studies with autoclaved and non-autoclaved soil exposure in immune-related diseases, such as allergy and inflammatory bowel disease models in mice. Academy of Finland, Tampere Tuberculosis Foundation, State Research Funding (for Fimlab Laboratories), Finnish Medical foundation and Northern Finland Laboratory Centre (NordLab).