No abstract

Gas6/TAM receptor activity contributes to the activation of pulmonary fibroblasts in IPF, suggesting that targeting this RTK pathway might be an effective antifibrotic strategy in this disease.

Idiopathic pulmonary fibrosis (IPF) is a fibrotic lung disease, with unknown etiopathogenesis and suboptimal therapeutic options. Previous reports have shown that increased T cell numbers and CD28 null phenotype is predictive of prognosis in IPF, suggesting that these cells might have a role in this disease. Flow cytometric analysis of explanted lung cellular suspensions showed a significant increase in CD8 + CD28 null T cells in IPF relative to normal lung explants. Transcriptomic analysis of CD3 + T cells isolated from IPF lungs explants revealed a loss of CD28 transcript expression and elevation of proinflammatory cytokine expression in IPF relative to normal T cells. IPF lung explant derived T cells (enriched with CD28 null T cells), but not normal donor lung CD28 + T cells induced dexamethasone resistant lung remodeling in humanized NSG mice. Finally, CD28 null T cells expressed similar CTLA4 and significantly higher levels of PD-1 proteins relative to CD28 + T cells and blockade of either proteins in humanized NSG mice, using anti-CTLA4, or anti-PD1, mAb treatment accelerated lung fibrosis. Together, these results demonstrate that IPF CD28 null T cells may promote lung fibrosis but the immune checkpoint proteins, CTLA-4 and PD-1, appears to limit this effect.

Idiopathic pulmonary fibrosis (IPF) is a fibrotic lung disease of unknown etiopathogenesis with limited therapeutic options. IPF is characterized by an abundance of fibroblasts and loss of epithelial progenitors, which cumulates in unrelenting fibrotic lung remodeling and loss of normal oxygenation. IPF has been challenging to model in rodents; nonetheless, mouse models of lung fibrosis provide clues as to the natural progression of lung injury and remodeling, but many have not been useful in predicting efficacy of therapeutics in clinical IPF. We provide a detailed methodologic description of various iterations of humanized mouse models, initiated by the i.v. injection of cells from IPF lung biopsy or explants specimens into severe combined immunodeficiency (SCID)/beige or nonobese diabetic SCID g mice. Unlike cells from normal lung samples, IPF cells promote persistent, nonresolving lung remodeling in SCID mice. Finally, we provide examples and discuss potential advantages and pitfalls of humanspecific targeting approaches in a humanized SCID model of pulmonary fibrosis.