CD4+CD25+Foxp3+ Tregs resolve experimental lung injury in mice and are present in humans with acute lung injury
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
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
View: Text | PDF
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

×

Figure 6

Tregs alter alveolar cytokine profiles after LPS-induced lung injury.

Options: View larger image (or click on image) Download as PowerPoint
Tregs alter alveolar cytokine profiles after LPS-induced lung injury. WT...
WT and Rag-1–/– mice received LPS or sterile water as control i.t. (A) Rag-1–/– mice received CD4+CD25– or CD4+CD25+ cells by tail vein injection 1 hour after LPS. BAL was harvested at the indicated times and assayed for the indicated cytokines. †P < 0.05 versus respective Rag-1–/– value. (B) BAL cytokines were assessed on day 4 after i.t. LPS in mice receiving isotype Ab or PC61. *P < 0.05 versus respective isotype value. (C) Primary alveolar macrophages were isolated from unstimulated WT mice and exposed to 10 ng/ml LPS. (D) Cocultures of alveolar macrophages and the indicated T cells (1:2 lymphocyte/macrophage ratio) was performed both directly (in the bottom chamber of a Transwell plate) and indirectly (macrophages and T cells in the bottom and top chambers, respectively), and TNF-α was measured 24 hours after LPS stimulation. (E) Thioglycollate-induced peritoneal macrophages were harvested, plated on 24-well plates (1 × 106 cells/well), and cocultured with CD4+CD25+ or CD4+CD25– cells or with media alone at a 1:2 lymphocyte/macrophage ratio in the presence or absence of 10 ng/ml LPS. Active TGF-β was measured in supernatants by ELISA. (C–E) †P < 0.05; *P < 0.05. (F) Cell surface expression of LAP in CD4+CD25+ splenocytes incubated with medium (unstimulated) or cultured with 10 μg/ml anti-CD3 and 50 U/ml IL-2 (stimulated), ex vivo BAL CD4+CD25+ cells on day 4 after i.t. LPS, and isotype Ab control.