Research ArticleFibrosis

PD-1 up-regulation on CD4+ T cells promotes pulmonary fibrosis through STAT3-mediated IL-17A and TGF-β1 production

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Science Translational Medicine  26 Sep 2018:
Vol. 10, Issue 460, eaar8356
DOI: 10.1126/scitranslmed.aar8356

PD-1–expressing T cells prompt pulmonary fibrosis

Although T cells expressing programmed cell death-1 (PD-1) are sometimes described as exhausted, they are not too tuckered out to wreak havoc in a variety of settings. Celada et al. examined cells from patients with sarcoidosis or idiopathic pulmonary fibrosis and saw an increase in PD-1+CD4+ T cells relative to healthy controls. These cells were mostly TH17 cells and were able to induce fibroblasts to produce collagen in vitro. Blocking PD-1 in the coculture system prevented this induction and associated cytokine production from the T cells. The authors then demonstrated that blocking PD-1 in a mouse bleomycin model reduced fibrosis symptoms. Putting these cells to sleep may be a way to help patients with pulmonary fibrosis.

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