TSP-1 upregulation promotes alveolar regeneration via the CD47/β1-integrin/FAK pathway during sepsis

Thrombospondin-1 (TSP-1) counteracts inflammation and contributes to tissue remodeling. This study aimed to investigate the role of TSP-1 in alveolar epithelial regeneration and repair during sepsis-associated acute lung injury (ALI). Bulk and single-cell RNA sequencing datasets were analyzed to assess TSP-1 expression in murine sepsis models, with validation performed in cecal ligation and puncture (CLP)-induced septic mice. Intrapulmonary TSP-1 overexpression was achieved by intratracheal injection of a lentiviral vector encoding TSP-1. Lipopolysaccharide (LPS)-treated alveolar type II (AT2) cell-derived organoids, combined with CLP-induced murine sepsis models, were used to elucidate the mechanisms by which TSP-1 promotes AT2 cell proliferation and differentiation. Analysis of bulk and single-cell RNA sequencing data revealed TSP-1 upregulation in the lungs of endotoxemic and septic mice, a finding validated in CLP-induced septic mice. Intrapulmonary TSP-1 overexpression alleviated, whereas TSP-1 inhibition exacerbated, pulmonary inflammation, ALI, and mortality in septic mice. Furthermore, TSP-1 overexpression enhanced alveolar epithelial regeneration, while its inhibition impaired this process. Using LPS-treated alveolar organoids, we demonstrated that a TSP-1 mimic peptide promoted AT2 cell proliferation and differentiation. Mechanistically, CD47 mediated TSP-1-induced AT2 cell regeneration through activation of the β1 integrin/focal adhesion kinase (FAK) signaling pathway. Moreover, intrapulmonary TSP-1 overexpression activated the β1 integrin/FAK pathway, thereby promoting alveolar epithelial repair, alleviating acute lung injury, and reducing mortality in CLP-induced septic mice in a CD47-dependent manner. Upregulation of TSP-1 may represent an endogenous protective response during sepsis by promoting alveolar regeneration via the CD47/β1-integrin/FAK signaling axis, highlighting its potential as a therapeutic target for sepsis-associated ALI.