Pleiotropic role of TLR2-mediated signaling in the protection of psoralidin against sepsis-induced acute lung injury

Abstract

Background: Sepsis, a life-threatening systemic inflammatory syndrome arising from dysregulated host response to pathogenic invasion, often leads to progressive multi-organ dysfunction, wherein acute lung injury typically precedes the onset of extrapulmonary organ failures. Psoralidin (PSO), extracted from Psoralea corylifolia L. seeds, possesses various pharmacological properties, including anti-inflammatory activity, antibacterial efficacy, and antioxidant capacity.

Purpose: This study aims to elucidate the therapeutic potential and underlying molecular mechanisms of PSO in attenuating sepsis-induced acute lung injury.

Methods: Effects of PSO pretreatment on sepsis-induced lung injury were assessed in cecal ligation and puncture (CLP) mice by evaluating sepsis scores, pulmonary cellular apoptosis, histopathological architecture, ROS generation, and TLR2/MyD88/NF-κB signaling. Transcriptomic profiling was performed to elucidate the molecular mechanisms underlying PSO-mediated protection against CLP-induced acute lung injury. To establish an optimal LPS-induced injury model, dose- and time-dependent effects of PSO on cellular morphology and vitality in LPS-challenged MLE-12 pulmonary epithelial cells were assessed. Effects of TLR2 siRNA and TLR2 overexpression on LPS-induced injury in MLE-12 pulmonary epithelial cells were also evaluated..

Results: Pharmacological pretreatment with PSO demonstrated significant efficacy in mitigating sepsis-induced acute lung injury in murine models, as evidenced by improved clinical parameters (reduced sepsis scores and restored anal temperature) and preserved pulmonary histoarchitecture. Transcriptomic profiling revealed that the pulmonary protective effects of PSO are mediated through modulation of the TLR2/MyD88/NF-κB signaling axis. In vitro investigations further demonstrated that PSO pretreatment effectively attenuated LPS-induced oxidative stress through reduction of intracellular ROS accumulation and suppression of TLR2-mediated inflammatory signaling, as indicated by downregulation of key pathway components (NF-κB p65, phosphorylated NF-κB p65, and Caspase1 p20). The critical role of TLR2 in PSO-mediated protection was substantiated through genetic overexpression studies, wherein TLR2 upregulation abrogated the cytoprotective effects of PSO against LPS-induced cellular injury.

Conclusion: PSO exerts significant protection against sepsis-induced acute lung injury by regulating the TLR2/MyD88/NF-κB signaling pathway, effectively attenuating the inflammatory response and oxidative stress. This study provides a theoretical basis for using PSO as a potential lung-protective agent and treatment for sepsis-induced acute lung injury.

Keywords: Antioxidant; Inflammation; MyD88; Psoralidin; Sepsis-induced acute lung injury; TLR2.