Identification and function of Tbx4 resident fibroblasts as a major source of fibrotic fibroblasts

Progressive tissue fibrosis is a major cause of morbidity, and idiopathic pulmonary fibrosis (IPF) is a terminal illness characterized by unremitting matrix deposition in the lung with very limited choice of therapies. The imcomplete understanding of the mechanisms of progressive fibrosis curbs the progress in therapeutics development. Of which, the origin of fibrotic fibroblasts has been poorly defined during the pathogenesis of tissue fibrosis. Here, we fate-mapped a early embryonic transcription factor T-box gene 4 (Tbx4)-derived mesenchymal progenitors in injured adult lung and found that Tbx4+ lineage cells are the major source of myofibroblasts. The ablation of Tbx4+ cells or disruption of Tbx4 signaling attenuated lung fibrosis in bleomycin injury model in mice in vivo. Furthermore, Tbx4+ fibroblasts are more invasive and the regulation of fibroblast invasiveness by Tbx4 is through mediating hyaluronan synthase 2 (HAS2). This study identified a major mesenchymal transcription factor driving the development of fibrotic fibroblasts during lung fibrosis. Understanding the origin, signaling, and functions of these fibroblasts would prove pivotal in the development of therapeutics for patients with progressive fibrotic diseases.

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Xie T, Liang J, Liu N, Huan C, Zhang Y, Liu W, Kumar M, Xiao R, D'Armiento J, Metzger D, Chambon P, Papaioannou VE, Stripp BR, Jiang D, Noble PW