Lipoxin A(4) promotes lung epithelial repair whilst inhibiting fibroblast proliferation

Therapy that promotes epithelial repair whilst protecting against fibroproliferation is critical for restoring lung function in acute and chronic respiratory diseases. Primary human alveolar type II cells were used to model the effects of lipoxin A(4) in vitro upon wound repair, proliferation, apoptosis and transdifferention. Effects of lipoxin A(4) upon primary human lung fibroblast proliferation, collagen production, and myofibroblast differentiation were also assessed. Lipoxin A(4) promoted type II cell wound repair and proliferation, blocked the negative effects of soluble Fas ligand/tumour necrosis factor α upon cell proliferation, viability and apoptosis, and augmented the epithelial cell proliferative response to bronchoaveolar lavage fluid (BALF) from acute respiratory distress syndrome (ARDS). In contrast, Lipoxin A(4) reduced fibroblast proliferation, collagen production and myofibroblast differentiation induced by transforming growth factor β and BALF from ARDS. The effects of Lipoxin A(4) were phosphatidylinositol 3′-kinase dependent and mediated via the lipoxin A(4) receptor. Lipoxin A(4) appears to promote alveolar epithelial repair by stimulating epitheial cell wound repair, proliferation, reducing apoptosis and promoting trans-differentiation of alveolar type II cells into type I cells. Lipoxin A(4) reduces fibroblast proliferation, collagen production and myofibroblast differentiation. These data suggest that targeting lipoxin actions may be a therapeutic strategy for treating the resolution phase of ARDS.