Cornus officinalis loganin attenuates acute lung injury in mice via regulating the PI3K/AKT/NLRP3 axis

Abstract

Ethnopharmacological relevance: Cornus officinalis (CO), a pharmaceutical and food product, can reduce inflammation, alleviate oxidative stress and lower blood sugar levels. In particular, CO has been used to treat severe COVID-19 patients during the pandemic, revealing its protective effects against pneumonia.

Aim: In this study, the mitigating effects of CO ethanol extract (COEE) on acute lung injury (ALI) and the molecular mechanism were investigated and the main active components of COEE were screened.

Methods: The anti-inflammatory effects of CO on model animals assessed by evaluating the levels of proinflammatory factors and inflammasome components by H&E staining technique, ELISA, RT‒qPCR and immunofluorescence assays. Moreover, CCK8, LDH, and RT‒qPCR assays were also performed to assess the effect of CO on cell viability and its anti-inflammatory efficacy in vitro. The mRNA expression of inflammatory factors (IL-1β and TNF-α), and the protein expression of NLRP3 inflammasome members was evaluated. In addition, the molecular mechanisms and core pharmacodynamic components of CO were inferred by network pharmacology, and the relevant pathway targets were analyzed and verified by immunohistochemistry, Western blotting and RT‒qPCR. In vivo and in vitro models were also established to verify the effects of the main active ingredient Loganin (LOG) on ALI and the related molecular mechanisms.

Results: COEE significantly suppressed inflammation, mitigated lung tissue damage, and inhibited NLRP3 inflammasome activation in an LPS-induced murine ALI model and an inflammatory cell model. Network pharmacology screening and experimental data revealed that the PI3K/AKT signalling pathway is the direct target of CO, as COEE administration potently inhibited the activation of the PI3K/AKT/NLRP3 signalling pathway in vitro and in vivo, whereas the PI3K/AKT pathway agonist YS-49 apparently impaired the effects of COEE. Further studies revealed that LOG, a core ingredient in CO, mediated the effects of COEE via direct targeting of AKT1, and different doses of LOG had consistent and strong protective effects on ALI model mice.

Conclusion: COEE exerts therapeutic effects on LPS-induced ALI model mice by inhibiting the activation of the PI3K/AKT pathway and preventing the overactivation of the NLRP3 inflammasome, and LOG is the core medicinal substance. These findings also provide supporting evidence for the development of new nutraceuticals for the prevention and treatment of ALI.

Keywords: Acute lung injury; Cornus officinalis; Loganin; NLRP3 inflammasome; Network pharmacology; PI3K/AKT signalling pathway.