Suppression of OGN in lung myofibroblasts attenuates pulmonary fibrosis by inhibiting integrin αv-mediated TGF-β/Smad pathway activation

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) represents a severe and progressive manifestation of idiopathic interstitial pneumonia marked by an uncertain etiology along with an unfavorable prognosis. Osteoglycin (OGN), belonging to the small leucine-rich proteoglycans family, assumes pivotal functions in both tissue formation and damage response. However, the roles and potential mechanisms of OGN in the context of lung fibrosis remain unexplored. METHODS: The assessment of OGN expression levels in fibrotic lungs was conducted across various experimental lung fibrosis mouse models. To elucidate the effects of OGN on the differentiation of lung myofibroblasts, both OGN knockdown and OGN overexpression were employed in vitro. The expression of integrin αv, along with its colocalization with lysosomes and latency-associated peptide (LAP), was monitored in OGN-knockdown lung myofibroblasts. Furthermore, the role of OGN in lung fibrosis was investigated through OGN knockdown utilizing adeno-related virus serotype 6 (AAV6)-mediated delivery. RESULTS: OGN exhibited upregulation in both lungs and myofibroblasts across diverse lung fibrosis mouse models. And laboratory experiments in vitro demonstrated that OGN knockdown inhibited the TGF-β/Smad signaling pathway in lung myofibroblasts. Conversely, OGN overexpression promoted TGF-β/Smad pathway in these cells. Mechanistic insights revealed that OGN knockdown facilitated lysosome-mediated degradation of integrin αv while inhibiting its binding to latency-associated peptide (LAP). Remarkably, AAV6-targeted OGN knockdown ameliorated the extent of lung fibrosis in experimental mouse models. CONCLUSION: Our results indicate that inhibiting OGN signaling could serve as a promising therapeutic way for lung fibrosis.