Ifnar1fl fl

All mouse experiments were approved by the Institutional Animal Care and Use Committee (IACUC) of The University of Pennsylvania. Mice were maintained in a specific pathogen-free facility in accordance with the American Association for Laboratory Animal Science guidelines. All mice were of C57BL/6NJ background, and unless otherwise described are 6-8 weeks of age. Mice of both sexes were utilized for these studies. Rag1^−/−, Ifnar1^fl/fl, and Col1a2-Cre^ERT2/+ mice were obtained from Jackson Laboratory (Bar Harbor, ME, USA). Ifnar1^S526A mice (“SA”) and bone marrow chimeras were generated as previously described [23 (link)]. Fibroblast-specific IFNAR1 knockout mice (Ifnar1^Δfib) were established by crossing Ifnar1^fl/fl mice with Col1a2-Cre^ERT2/+ mice. The resultant Col1a2-Cre^ERT2/+; Ifnar1^fl/fl mice were genotyped by PCR (Figure 3I). The Col1a2-Cre^ERT2/+ was induced by administering tamoxifen (Sigma #T5648, St. Louis, MO, USA) 0.2 mg/g, daily for 5 days. Deletion of IFNAR1 was confirmed by PCR with primers for mouse wildtype IFNAR1 (Forward: 5’-CTGGGAGCCAGGGCATAAC-3’, Reverse 5’-CCAGCCTTTCGGAGTGTGC-3’) (Figure 3I). Littermates were randomly assigned into experimental groups, which were either co-housed or exposed to other groups’ bedding to ensure exposure to all groups’ microbiota.