Therapeutic and prophylactic roles of oleuropein in experimental acute lung injury: Modulation of tumor necrosis factor‑α and nuclear factor erythroid 2‑related factor 2 pathways

In total, 10.4% of patients with acute hypoxemic respiratory failure that are treated in intensive care units develop acute respiratory distress syndrome (ARDS); this condition currently represents an incontrovertible health problem due to its high mortality rates, which have been reach ~40%. Following the rise in ARDS cases during the coronavirus disease 2019 pandemic, awareness of this disease has notably increased, emphasizing the importance of its prevention, early diagnosis and treatment. Despite numerous studies on this disease, to the best of our knowledge, no effective treatment options for ARDS have been identified outside of supportive therapies. A total of 30 female Wistar Albino rats were used to establish an ARDS model in the present study. Acute lung injury was induced in rats by administering intravenous oleic acid (OA). Intraperitoneal oleuropein (OLE) prophylaxis and therapeutic administration were then performed in model rats to investigate the prophylactic and therapeutic benefits of OLE on lung injury. The extent of lung damage after different OLE treatments was evaluated biochemically, histopathologically and immunohistochemically. Histopathological and immunohistochemical analyses revealed that OA‑induced lung damage was significantly reduced in the groups treated with OLE compared with the ARDS model group. In the prophylactic OLE group, the total damage score of rat lung tissue was significantly reduced compared with that in the OA group. This was also the case for rats in the therapeutic OLE group, but the total damage score of lung tissues in this group was slightly higher compared with that in the prophylactic group. Therefore, the present study demonstrated that OLE significantly alleviated lung damage in rats. Based on these findings, OLE may be considered a potential therapeutic agent for ARDS and therefore the findings of the present study may guide future research in this field.