P-131 Overexpression of V-ATPase B2 prevent bleomycin induced lung injury/fibrosis by attenuate lysosomal membrane permeabilization(LMP) and enhancing collagen degradation

Background: Excessive oxidative stress cause lysosomal membrane permeabilization that lead to cell death.Vacuolar ATPase is the enzyme responsible for pumping H+ into cytosol,that maintain intracellular PH.We had reported that V-ATPaseB2 subunit expression is upregulated in TiO2 nanoparticle exposed alveolar epithelial cells. Aims:We investigated the role of lysosomal V-ATPaseB2 subunit in the H2O2 induced cell death in alveolar epithelial cells and following acute lung injury/fibrosis mouse model. Methods: Transgenic human V-ATPaseB2 mice were treated to bleomycin.Histological examinations, collagen assay, cytokine measurements were performed.Apoptosis, lysosomal functions and collagen uptake/degradation activates were evaluated in the V-ATPaseB2 overexpressing and knock down stable cells. Result: V-ATPaseB2 overexpression cells increased survival of H2O2 induced apoptosis and diminished LMP by oxidative stress. Overexpression of V-ATPaseB2 increased lysosomal activities, increased cellular PH, and lysosomal degradation activity against H2O2. In contrast, silencing of V-ATPaseB2 subunits increased H2O2 induced cell death by increasing LMP. V-atpaseB2 overexpressing macrophage enhanced uptake and degradation of collagen. V-atpaseB2 overexprssing transgenic mice showed significantly inhibit BLM induced increased lung inflammation and fibrosis. Conclusion: V-ATPaseB2 is critical for maintain lysosomal activities against excessive oxidative stress. Our finding revealed a previously unrealized role of V-ATPase subunit in lung injury/fibrosis model. Grant:2016R1E1A1A01943481