The gut microbiota promotes distal tissue regeneration via RORγ+ regulatory T cell emissaries [bulk RNA-seq]

Specific microbial signals induce the differentiation of a distinct pool of RORγ+ regulatory T cells (Tregs) crucial for intestinal homeostasis. We discovered highly analogous populations of microbiota-dependent Tregs that promote tissue regeneration at extra-gut sites, notably acutely injured skeletal muscle and fatty liver. Tissue damage elicited the emigration of RORγ+ Tregs from the gut to compromised tissues, wherein they regulated the dynamics and tenor of early inflammation and helped balance the proliferation versus differentiation of local stem cells. Reining in IL-17A-producing T cells was a major mechanism underlying these rheostatic functions. Our findings highlight the importance of gut-trained Treg emissaries in controlling the response to sterile injury of non-mucosal tissues. To analyze the transcriptional differences between RORγ+ Tregs from the colon and regenerating muscle, Foxp3-Thy1.1x RorcGFP/wt male mice were injected with cardiotoxin, and 3 days later RORγ+ Tregs (CD4+TCRβ+Foxp3Thy1.1+RORγGFP+) were sorted from both tissues, and their transcriptional profiles were determined using RNA-seq. To assess the impact of RORγ+ Tregs on muscle regeneration, we analyzed the transcriptomes of whole muscle samples from Foxp3-cre x Maffl/fl (MafΔTreg) mice versus Foxp3-cre x Mafwt/wt (Maf-wt) littermate controls 7 days after cardiotoxin-induced muscle injury. For sorted muscle satellite cells, samples were analyzed from rIL-17A-treated mice against PBS-treated controls at 0, 1 and 3 days after cardiotoxin-induced muscle injury. To study the impact of RORγ+ Tregs on non-alcoholic steatohepatitis (NASH) development, we analyzed the transcriptomes of whole liver samples from MafΔTreg mice versus Maf-wt littermate controls 7 days after feeding them a choline-deficient, amino-acid-defined, high-fat diet (CDAHFD).