TGFB1 and idiopathic pulmonary fibrosis: In addition to a previous report on Tregs impairment in IPF [46], there is a report that the immunosuppressive function of Tregs is important in suppressing lung fibrosis, as the administration of dysfunctional Tregs worsened fibrosis in a TGF-β1-induced mouse model of lung fibrosis compared to the administration of normal Tregs [48].