Quantification and characterization of lung fibrosis in ARDS patients using picrosirius red staining.

Introduction: Evolution toward diffuse lung fibrosis is common in patients with ARDS but remains poorly characterized. In particular, the quantification and characterization of collagen fibers in lung tissue from patients with ARDS has not been performed and remain technically challenging. This study aims to precisely quantify and characterize collagen deposition in lung tissue from patients with ARDS. Materials and methods: Lung samples from ARDS patients and controls were retrospectively analyzed to quantify lung tissue fibrosis using computer-assisted digital processing after picrosirius red (PSR) staining of whole tissue sections. Additional analyses were conducted using immunofluorescence (IF) in conjunction with PSR staining and using examination of PSR stained sections under polarized light (PL). Results: Compared to controls, patients with ARDS exhibited increased total collagen deposition ( Conclusion: Lung fibrosis during ARDS is predominantly driven by the deposition of weakly stained, loose segments of collagen fibers, which is associated with impaired lung mechanics and poorer clinical outcomes. Future studies should define candidates for early anti-fibrotic therapies.