No abstract

Acute lung injury (ALI) is featured by pulmonary edema, alveolar barrier injury, inflammatory response, and oxidative stress. The activation of Sirt1 could relieve lipopolysaccharide- (LPS-) induced murine ALI by maintaining pulmonary epithelial barrier function. Oxypaeoniflorin (Oxy) serves as a major component of Paeonia lactiflora Pall., exerting cardioprotection by activating Sirt1. However, the role of Oxy in ALI induced by LPS remains unclear. The aim of the present study is to illustrate the modulatory effects and molecular mechanisms by which Oxy operates in ALI induced by LPS. The intraperitoneal injection of LPS was performed to establish the murine ALI model while LPS-treated alveolar epithelial cells were used to mimic the in vitro ALI model. Levels of lung injury, oxidative stress, and inflammatory response were detected to observe the potential effects of Oxy on ALI. Oxy treatment mitigated lung edema, inflammatory response, and oxidative stress in mouse response to LPS, apart from improving 7-day survival. Meanwhile, Oxy also increased the expression and activity of Sirt1. Intriguingly, Sirt1 deficiency or inhibition counteracted the protective effects of Oxy treatment in LPS-treated mice or LPS-treated alveolar epithelial cells by regulating the PTEN/AKT signaling pathway. These results demonstrated that Oxy could combat ALI in vivo and in vitro through inhibiting inflammatory response and oxidative stress in a Sirt1-dependent manner. Oxy owns the potential to be a promising candidate against ALI.

Oxidative damage and epithelial-mesenchymal transition (EMT) are main pathological processes leading to the development of PM2.5-induced lung fibrosis. Epigallocatechin gallate (EG), a natural polyphenol extracted from green tea, possesses the ability to combat oxidative stress and inflammation. However, the potential roles of EG in PM2.5-induced lung fibrosis have not been reported yet. In the present study, we investigated whether EG could relieve PM2.5-induced lung injury and fibrosis in vivo and in vitro. To mimic PM2.5-induced lung fibrosis, C57/BL6 mice were intranasally instilled with PM2.5 suspension, and MLE-12 lung epithelial cells were stimulated with PM2.5 (100 μg/mL) in vitro. The results showed that intragastric administration of EG (20 mg/kg/d or 80 mg/kg/d for 8 weeks) significantly prevented lung injury, inflammation, and oxidative stress in PM2.5-induced mice, apart from inhibiting collagen deposition. Additionally, EG treatment also suppressed the activation of AKT/mTOR signaling pathway in lung tissues challenged with PM2.5. In vitro experiments further demonstrated that EG treatment could enhance cell viability in a concentration-dependent manner in PM2.5-treated MLE-12 lung epithelial cells. Also, the overexpression of constitutively active AKT could offset the inhibitory effects of EG on EMT and oxidative stress in PM2.5-treated MLE-12 lung epithelial cells. Finally, AKT overexpression also blocked the inhibitory effect of EG on the phosphorylation of mTOR in PM2.5-treated MLE-12 lung epithelial cells. In conclusion, EG could improve PM2.5-induced lung fibrosis by decreasing oxidative damage and EMT through AKT/mTOR pathway, which might be a potential candidate for the treatment of PM2.5-induced lung fibrosis.

Background and objective: Hydroxychloroquine (HCQ) is a molecule derived from quinacrine; it displays a wide range of pharmacological properties, including anti-inflammatory, immunomodulatory, and antineoplastic. However, little is known about this molecule’s role in lung injury. This study aimed to identify HCQ’s regulatory role of HCQ in sepsis - induced lung injury and its molecular mechanism. Methods: To test the protective properties of HCQ, we established an in vivo model of lipopolysaccharide (LPS)-induced lung injury in mice. The extent of the injury was determined by evaluating histopathology, inflammatory response, oxidative stress, and apoptosis. Mechanistically, conventional nucleotide-binding oligomerization domain leucine-rich repeat and pyrin domain-containing 3 (NLRP3) knockout mice were employed to investigate whether HCQ exerted pulmonary protection by inhibiting NLRP3-mediated pyroptosis. Results: Our findings revealed that HCQ pretreatment significantly mitigated LPS-induced lung injury in mice in terms of histopathology, inflammatory response, oxidative stress, and apoptosis, while inhibiting LPS-induced NLRP3 inflammasome activation and pyroptosis. Additionally, the indicators of lung injury, including histopathology, inflammatory response, oxidative stress, and apoptosis, were still reduced drastically in LPS-treated NLRP3(-/-) mice after HCQ pretreatment. Notably, HCQ pretreatment further decreased the levels of pyroptosis indicators, including IL-1β, IL-18 and Cle-GSDMD in LPS-treated NLRP3(-/-) mice. Conclusion: Taken together, HCQ protects against lung injury by inhibiting pyroptosis maybe not only through NLRP3 pathway, but also through non NLRP3 pathway; therefore, it may be a new therapeutic strategy in the treatment of lung injury.