Reactivation of CTLA4-expressing T cells accelerates resolution of lung fibrosis in a humanized mouse model
Santosh Yadav, … , Jay Kolls, Victor J. Thannickal
Santosh Yadav, … , Jay Kolls, Victor J. Thannickal
Published March 18, 2025
Citation Information: J Clin Invest. 2025;135(10):e181775. https://doi.org/10.1172/JCI181775.
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Research Article Immunology Pulmonology

Reactivation of CTLA4-expressing T cells accelerates resolution of lung fibrosis in a humanized mouse model

Abstract

Tissue regenerative responses involve complex interactions between resident structural and immune cells. Recent reports indicate that accumulation of senescent cells during injury repair contributes to pathological tissue fibrosis. Using tissue-based spatial transcriptomics and proteomics, we identified upregulation of the immune checkpoint protein, cytotoxic T lymphocyte–associated protein 4 (CTLA4), on CD8+ T cells adjacent to regions of active fibrogenesis in human idiopathic pulmonary fibrosis and in a repetitive bleomycin lung injury murine model of persistent fibrosis. In humanized CTLA4-knockin mice, treatment with ipilimumab, an FDA-approved drug that targets CTLA4, resulted in accelerated lung epithelial regeneration and diminished fibrosis from repetitive bleomycin injury. Ipilimumab treatment resulted in the expansion of Cd3e+ T cells, diminished accumulation of senescent cells, and robust expansion of type 2 alveolar epithelial cells, facultative progenitor cells of the alveolar epithelium. Ex vivo activation of isolated CTLA4-expressing CD8+ cells from mice with established fibrosis resulted in enhanced cytolysis of senescent cells, suggesting that impaired immune-mediated clearance of these cells contributes to persistence of lung fibrosis in this murine model. Our studies support the concept that endogenous immune surveillance of senescent cells may be essential in promoting tissue regenerative responses that facilitate the resolution of fibrosis.

Authors

Santosh Yadav, Muralidharan Anbalagan, Shamima Khatun, Devadharshini Prabhakaran, Yasuka Matsunaga, Justin Manges, James B. McLachlan, Joseph A. Lasky, Jay Kolls, Victor J. Thannickal

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Figure 4

CTLA4 blockade in a mouse model of persistent lung fibrosis ameliorates fibrosis.

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CTLA4 blockade in a mouse model of persistent lung fibrosis ameliorates ...
(A) Schematic representation of the humanized CTLA4-knockin mouse carrying the extracellular domain of CTLA4 gene. (B) Experimental outline of humanized CTLA4 mice subjected to repetitive bleomycin injury–induced pulmonary fibrosis via oropharyngeal administration of bleomycin (1.25 U per kg body weight) in 2 doses, 14 days apart. On day 21 after the second dose, mice were treated intraperitoneally with either control IgG1 isotype or the anti-CTLA4 monoclonal antibody ipilimumab at doses of 5 mg per kg body weight twice per week for 4.5 weeks (total of 9 doses). (C and D) Representative images of H&E- (C) and Masson’s trichrome–stained (D) whole lung sections from bleomycin-induced mice treated with either IgG1 isotype control or ipilimumab. Scale bar: 800 μm. (E) Quantitation of H&E staining in the IgG1 isotype control and ipilimumab groups. Images of H&E staining were quantified using QuPath software. Data represent IgG1 isotype control and ipilimumab (n = 6 in each group). (F) Quantitation of Masson’s trichrome staining in the IgG1 isotype control or ipilimumab groups. Collagen containing areas were identified with machine-learning algorithms using inForm automated image analysis software built into the PhenoImager Fusion (Akoya Biosciences). Data represent IgG1 isotype control and ipilimumab groups (n = 6 per group). (G) Whole-lung hydroxyproline content (μg/lung) in IgG1 isotype control and ipilimumab treated groups (n = 4 per group). Data are shown as mean ± SEM. Statistical differences in E–G were tested using a paired 2-tailed Student’s t test.