Inflammation-induced Generation of Splenic Erythroblast-like Ter- Cells Inhibits the Progression of Acute Lung Injury via Artemin

Identifying inflammation-induced leukocyte subsets and their derived circulating factors has been instrumental in understanding the progession of ALI/ARDS. Nevertheless, how primary inflammation-induced non-leukocyte populations in distal organs contribute to ALI/ARDS remains poorly defined. Here, we report one population of erythroblast-like cells (Ter-cells) deriving from megakaryocyte- erythroid progenitor cells with a unique Ter-119+CD45-CD71+ phenotype in ALI/ARDS. Ter-cells induced by spleen are chemoattracted into lung to inhibit the progression of ALI by secreting neurotrophic factor artemin into the blood and BALF. In vivo blockade of Ter-cell-derived artemin aggravates lung injury, and artemin deficiency abolishes Ter-cells' anti-inflammatory ability. We confirm the presence of circulating artemin in ARDS patients and show that significantly elevated artemin correlates with good prognosis. We propose that Ter-cells and the secreted artemin play important roles in ALI/ARDS with prognostic and therapeutic implications.