Methods of microbiota transfer affect severity of DSS-induced colitis

Differences in the gut microbiota (GM) of research mice can significantly impact model phenotypes. Previous studies in our lab demonstrated that methods of GM transfer also affect the severity of dextran sodium sulfate (DSS)-induced colitis in mice. Co-housing mice to transfer GM leads to greater disease severity compared to embryo transfer or cross-fostering methods. Additionally, transfer of low-richness GM into recipients with higher richness GM is associated with more severe colitis when compared to GM transfer in the opposite direction. However, it was unclear if disease was exacerbated by the stress of co-housing, or the later transfer of fecal material relative to other methods. To answer this question, we compared co-housing to fecal microbiota transfer (FMT) and bedding transfer. C57BL/6 mice from two suppliers with known differences in GM richness were used as recipients of two donor GMs differing in richness, via co-housing or a combination of FMT and bedding transfer. FMT groups were gavaged once per week for four weeks starting at weaning with twice weekly bedding transfer from donor cages. Each cohort contained 8 male and 8 female mice. At 7 weeks of age, all mice received 2.5% DSS in their drinking water for one week, followed by one week of regular water. Body weights (BW) were collected daily and mice losing 20% BW or greater were sacrificed. The remaining mice were sacrificed at 9 weeks of age and colon lengths measured.