Pogostone attenuates TNF-α-induced injury in A549 cells via inhibiting NF-κB and activating Nrf2 pathways

Pogostone (PO), a major component of Pogostemon cablin, displays potent protective effects against lipopolysaccharide-induced acute lung injury (ALI) in mice. This study aimed to investigate the protective effect of PO on TNF-alpha-induced cell injury in human alveolar epithelial cells in vitro and its underlying mechanism. The cell viability was measured using the MTS method. The cell apoptosis was determined using flow cytometry. The activities of reactive oxygen species (ROS) were detected using a fluorescence microscope. The pro-inflammatory cytokines and antioxidant genes were assessed using reverse transcription-polymerase chain reaction. The protein expression of Kelch-like ECH-associated protein 1 (Keap1), nuclear factor erythroid 2-related factor 2 (Nrf2), nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor-alpha (I kappa B alpha), and nuclear factor-kappa B (NF-kappa B) p65 was analyzed using the Western blot analysis. PO alleviated cell apoptosis and inhibited ROS production. It alleviated TNF-alpha-induced cell injury, suppressed the levels of inflammatory cytokines [interleukin (IL)-6, IL-1 beta, and IL-8], and enhanced the expression of antioxidant genes (quinine oxido-reductase 1, glutamate cysteine ligase catalytic subunit, heme oxygenase-1). It increased the expression of Keap1 and promoted the activation of Nrf2. However, the phosphorylation of I kappa B alpha and the nuclear expression of NF-kappa B p65 decreased. The anti-inflammatory and antioxidant effects of PO were abrogated following Nrf2 and NF-kappa B p65 knockdown. The results indicated a protective effect of PO against TNF-alpha-induced cell injury in A549 cells by modulating the balance between Nrf2 and NF-kappa B p65 signaling pathways. They verified PO as a promising anti-inflammatory adjuvant drug for treating ALI.