An amphiregulin reporter mouse enables transcriptional and clonal expansion analysis of reparative lung Treg cells

Regulatory T (Treg) cells are known to play critical roles in tissue repair via provision of growth factors such as amphiregulin (Areg). Areg-producing Treg cells have previously been difficult to study because of an inability to isolate live Areg-producing cells. In this report, we created a novel reporter mouse to detect Areg expression in live cells ( Areg ^Thy1.1 ). We employed influenza A and bleomycin models of lung damage to sort Areg-producing and –non-producing Treg cells for transcriptomic analyses. Single cell RNA-seq revealed distinct subpopulations of Treg cells and allowed transcriptomic comparisons of damage-induced populations. Single cell TCR sequencing showed that Treg cell clonal expansion is biased towards Areg-producing Treg cells, and largely occurs within damage-induced subgroups. Gene module analysis revealed functional divergence of Treg cells into immunosuppression-oriented and tissue repair–oriented groups, leading to identification of candidate receptors for induction of repair activity in Treg cells. We tested these using an ex vivo assay for Treg cell–mediated tissue repair, identifying 4-1BB agonism as a novel mechanism for reparative activity induction. Overall, we demonstrate that the Areg ^Thy1.1 mouse is a promising tool for investigating tissue repair activity in leukocytes.