Effect of OTR4120 on pulmonary fibrosis in mice

BackgroundAcute respiratory distress syndrome (ARDS) can be related to airway remodeling caused by pulmonary fibrosis and systemic inflammation. Etiologies of ARDS are multifaceted such as idiopathic pulmonary fibrosis or as recently the SARS-CoV-2 infection. Antifibrotic drugs may be a better approach to slow the fibrotic process but they often have poor efficacy in patients, and the mortality rate remains high, up to 40% within 5 years of diagnosis. Here, we tested the antifibrotic effect of a ReGeneTaring Agents named OTR4120 in a bleomycin-induced mouse model of pulmonary fibrosis. MethodsSwiss mice were randomly divided into four experimental groups: saline-treated control group, an OTR4120 group, a bleomycin-induced fibrosis group without OTR4120, and a bleomycin-induced fibrosis groups with OTR4120 (intravenous injections every 3 days starting at day 11 post bleomycin I.P. injection). Lungs were compared using the lung/body weight index, and the extend of interstitial injury area was graded using histopathological assessment of haematoxylin & eosin-stained lung tissue sections. Lung tissue Collagen I and Collagen III levels, and blood cytokine levels were measured using a Collagen colorimetric kit and a Cytokine colorimetric kit, respectively. ResultsThe group treated by OTR4120 alone were used as a control. The clincal signs in all animals resoved gradually on day 17 after bleomycin injections and 6 days after OTR4120 treatment, and disappeared almost completetly at day 24 after bleomycin injections and day 13 after OTR4120 treatment. Lung/body weight index values were significantly lower in the bleomycin-OTR4120 treated group versus the bleomycin group (7.31, 9.97 and 7.63 mg/g, p-value< 0.01; respectively). Histopathological analyses suggest that OTR4120 treatment ameliorated the increased inflammatory cell infiltration, and attenuated the reduction in interstitial thickening, associated with bleomycin-induced fibrosis. Collagen III and cytokine levels were decreased in the OTR4120 group versus the fibrotic (bleomycin only) group. OTR4120-treated animals were less affected in their behavior, did not loose weight nor appetite, and recovered overall activities within 6 days of OTR4120 treatment, while none of the vehicle-treated animals recovered to normal. ConclusionOTR4120 is a potential candidate to reduce lung fibrosis.