Tff1-expressing Tregs in lung prevents exacerbation of Bleomycin-induced pulmonary fibrosis (scRNA-Seq)

Bleomycin (BLM) induces lung injury, leading to inflammation and pulmonary fibrosis. Regulatory T cells (Tregs) maintain self-tolerance and control host immune responses. However, little is known about their involvement in the pathology of pulmonary fibrosis. Here we show that a unique Treg subset that expresses trefoil factor family 1(Tff1) emerges in the BLM-injured lung. These Tff1-expressing Tregs (Tff1-Tregs) were induced by IL-33. Moreover, although Tff1 ablation in Tregs had no impact, selective ablation of Tff1-Tregs using an intersectional genetic method promoted pro-inflammatory features of macrophages in the injured lung and exacerbated the fibrosis. Taken together, our study revealed the presence of a unique Treg subset expressing Tff1 in BLM-injured lungs and their critical role in the injured lung to ameliorate fibrosis. Overall design: Living CD45+ cells were sorted from naïve lung or BLM-injured lung (day 15) of WT mice. The sorted samples from three individual mice under identical conditions were pooled together, ensuring an equal cell count across the combined sample.