CD4+CD25+Foxp3+ Tregs resolve experimental lung injury in mice and are present in humans with acute lung injury
Franco R. D’Alessio, … , John F. McDyer, Landon S. King
Franco R. D’Alessio, … , John F. McDyer, Landon S. King
Published September 21, 2009
Citation Information: J Clin Invest. 2009;119(10):2898-2913. https://doi.org/10.1172/JCI36498.
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Research Article

CD4+CD25+Foxp3+ Tregs resolve experimental lung injury in mice and are present in humans with acute lung injury

Abstract

Acute lung injury (ALI) is characterized by rapid alveolar injury, inflammation, cytokine induction, and neutrophil accumulation. Although early events in the pathogenesis of ALI have been defined, the mechanisms underlying resolution are unknown. As a model of ALI, we administered intratracheal (i.t.) LPS to mice and observed peak lung injury 4 days after the challenge, with resolution by day 10. Numbers of alveolar lymphocytes increased as injury resolved. To examine the role of lymphocytes in this response, lymphocyte-deficient Rag-1–/– and C57BL/6 WT mice were exposed to i.t. LPS. The extent of injury was similar between the groups of mice through day 4, but recovery was markedly impaired in the Rag-1–/– mice. Adoptive transfer studies revealed that infusion of CD4+CD25+Foxp3+ Tregs as late as 24 hours after i.t. LPS normalized resolution in Rag-1–/– mice. Similarly, Treg depletion in WT mice delayed recovery. Treg transfer into i.t. LPS–exposed Rag-1–/– mice also corrected the elevated levels of alveolar proinflammatory cytokines and increased the diminished levels of alveolar TGF-β and neutrophil apoptosis. Mechanistically, Treg-mediated resolution of lung injury was abrogated by TGF-β inhibition. Moreover, BAL of patients with ALI revealed dynamic changes in CD3+CD4+CD25hiCD127loFoxp3+ cells. These results indicate that Tregs modify innate immune responses during resolution of lung injury and suggest potential targets for treating ALI, for which there are no specific therapies currently available.

Authors

Franco R. D’Alessio, Kenji Tsushima, Neil R. Aggarwal, Erin E. West, Matthew H. Willett, Martin F. Britos, Matthew R. Pipeling, Roy G. Brower, Rubin M. Tuder, John F. McDyer, Landon S. King

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Figure 4

Phenotype and function of alveolar Tregs during resolution of ALI.

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Phenotype and function of alveolar Tregs during resolution of ALI. (A) H...
(A) Histograms showing the percentage of Foxp3+ cells in the pool of donor CD4+CD25+ splenocytes (AT spleen) as well as in CD4+CD25+ cells recovered in the BAL from LPS-injured Rag-1–/– mice on days 4 and 10 after LPS. Labeling for isotype control Ab at day 10 is also shown. (B) Purified Tregs from naive WT spleens were cultured in the presence or absence of 100 ng/ml LPS and/or macrophages. Representative flow cytometry shows the relationship between Foxp3 and FR4 expression under different conditions. Numbers within plots denote the percentage of cells in the respective quadrants. (C) Relative expression of Foxp3 and FR4 in CD4+CD25+ cells from the experiments in B. †P < 0.05 versus Tregs without LPS or macrophages. (D) Proliferative responses of CD4+CD25– lymphocytes to 0.5 mg/ml anti-CD3 and irradiated APCs (Stimulated) in the presence or absence of CD4+CD25+ cells isolated from spleen or sorted from BAL of WT mice on day 4 after LPS and cultured at the indicated ratios. Unstimulated CD4+CD25– lymphocytes were not exposed to anti-CD3 and irradiated APCs. †P < 0.05 versus media-stimulated CD25– cells.