Hyperbaric oxygen ameliorates bleomycin-induced pulmonary fibrosis in mice

The prevalence of pulmonary fibrosis is increasing with an ageing population and its burden is likely 24 to increase following COVID-19, with large financial and medical implications. As approved therapies 25 in pulmonary fibrosis only slow disease progression there is a significant unmet medical need. 26 Hyperbaric oxygen (HBO) is the inhaling of pure oxygen, under the pressure of greater than one 27 atmosphere absolute and it has been reported to improve pulmonary function in patients with 28 pulmonary fibrosis. Our recent study suggested that repetitive HBO exposure may affect biological 29 processes in mice lungs such as response to wounding and extracellular matrix. To extend these 30 findings, a bleomycin-induced pulmonary fibrosis mouse model was used to evaluate the effect of 31 repetitive HBO exposure on pulmonary fibrosis. Building on our previous findings, we provide 32 evidence that HBO exposure attenuates bleomycin-induced pulmonary fibrosis in mice. In vitro, HBO 33 exposure could reverse, at least partially, transforming growth factor (TGF)-β-induced fibroblast 34 activation, and this effect may be mediated by down-regulating TGF-β-induced expression of hypoxia 35 inducible factor (HIF)-1α. These findings support HBO as a potentially life-changing therapy for 36 patients with pulmonary fibrosis, although further research is needed to fully evaluate this.