Generation of a novel lung fibrosis model using precision-cut lung slices from transgenic TGFβ1 mice.

Lung fibrosis is a progressive, lethal disease with a life expectancy of 3-5 yr after diagnosis. A dysregulated repair response to injury, resulting in an accumulation of extracellular matrix (ECM) in the alveolar spaces, is suggested to be causal. Despite increased understanding of the mechanisms driving the development and progression of lung fibrosis, there is no cure. This study aimed to establish an ex vivo model of early lung fibrosis in mouse precision-cut lung slices (PCLS) derived from transgenic mice with doxycycline (DOX)-induced overexpression of active transforming growth factor β1 (TGFβ1). PCLS were untreated (control) or treated with either DOX (25 μg/mL) to induce endogenous TGFβ1 secretion ex vivo or DOX with an additional fibrotic cocktail (FC). Treatment with exogenous TGFβ1 acted as a control for the model. None of the treatments affected PCLS viability. DOX-treated PCLS secreted more TGFβ1 and pro-COL1α1 compared with control after 5 days of culture. The combination of DOX + FC induced enhanced collagen deposition with disorganized immature collagen I fibers, particularly around airways. More fibulin-1 was deposited in PCLS treated with DOX + FC compared with DOX alone, indicating that fibulin-1 may play a role in collagen deposition. In summary, ex vivo treatment with DOX induces secretion of endogenous TGFβ1 from transgenic mice PCLS, eliciting a range of profibrotic responses. The addition of FC components enhanced in situ fibrosis, especially around the airways. This novel ex vivo model may provide a platform to explore the mechanisms underlying fibrogenesis in lung fibrosis.NEW & NOTEWORTHY Induction of endogenous transforming growth factor β1, combined with factors increased in lungs of patients with lung fibrosis, in murine precision-cut lung slices provided an innovative ex vivo model for studying lung fibrosis. Leveraging this model revealed the involvement of extracellular matrix modulating components that may be important for orchestrating collagen fiber organization in fibrosis. This ex vivo model provides a platform to explore mechanisms underlying lung fibrosis and identify novel potential therapeutic targets.