β-Catenin Stabilization Protects Against Pulmonary Hemorrhage Through Amphiregulin and BATF- Mediated Regulatory T Cells

Pulmonary hemorrhaging (PH) is a life-threatening condition with a high mortality rate, yet the role of immune cells in its pathogenesis remains poorly defined. Here, we investigated the protective function of {beta}-catenin stabilization in T cells and its impact on PH. Using a novel transgenic mouse model (CAT-Tg) with stabilized {beta}-catenin, we demonstrate that {beta}-catenin stabilization induces a distinct T-cell phenotype characterized by an expansion of central effector memory cells (CD44, CD122, Eomes, T-bet). Mechanistically, this effect was associated with suppression of key proinflammatory pathways, including reduced phosphorylation of STAT1, STAT3, and JAK1. PH was induced using pristane, and CAT-Tg mice were significantly protected from lung damage, showing reduced proteinuria and decreased pulmonary proinflammatory cytokine production compared with wild-type (WT) and T cell-specific {beta}-catenin knockout (cKO) mice. This protection correlated with a marked increase in FOXP3 regulatory T cells (Tregs) in CAT-Tg mice. We further identified a novel mechanism in which {beta}-catenin stabilization enhances lung expression of Amphiregulin and BATF, two molecules essential for Treg function and tissue repair. Adoptive transfer of CAT-Tg Tregs into WT mice with pristane-induced PH conferred superior protection, as evidenced by reduced lung inflammation and proteinuria. The systemic administration of a {beta}-catenin agonist to mice with PH significantly attenuated disease severity. Our bioinformatic analysis confirmed that {beta}-catenin stabilization upregulates pathways associated with tissue repair and immune homeostasis, including PI3K-Akt, angiogenesis, and STAT5 signaling. Collectively, these findings reveal that {beta}-catenin stabilization protects against pulmonary hemorrhage by inducing a specialized T-cell phenotype and establishing a protective Amphiregulin-BATF-Treg axis. This study identifies a novel immunomodulatory pathway with therapeutic potential for PH and other inflammatory lung diseases.