4-Octyl itaconate (4-OI) attenuates lipopolysaccharide-induced acute lung injury by suppressing PI3K/Akt/NF-κB signaling pathways in mice

The progression of acute lung injury (ALI) is attributable to inflammation and oxidative stress. The cell-permeable itaconate analog 4-octyl itaconate (4-OI) provides protection against inflammatory responses and oxidative stress. However, whether 4-OI can protect against ALI remains poorly understood. The aim of this study was to explore the protective effects of 4-OI against LPS-induced ALI and the underlying mechanisms using hematoxylin and eosin (H&E) to observe lung morphology, ELISA and reverse transcription-quantitative PCR to measure the levels of IL-1β, TNF-α and IL-6 and western blotting to examine the levels of PI3K, Akt and NF-κB. The present study demonstrates that intraperitoneal administration of 4-OI (25 mg/kg) 2 h before lipopolysaccharide (LPS; 5 mg/kg) intratracheal injection significantly alleviated the lung tissue injury induced by LPS, reducing the production of proinflammatory cytokines and reactive oxygen species (ROS) in vivo. Furthermore, 4-OI and the antioxidant N-acetyl-L-cysteine markedly suppressed PI3K and Akt phosphorylation in LPS-treated RAW264.7 macrophage cells in vitro. Further study demonstrated that a pharmacological inhibitor of the phosphoinositide 3-kinase (PI3K)-Akt pathway, LY294002, inhibited the expression of NF-κB p65 in the nuclear fraction and decreased the production of inflammatory cytokines. Collectively, the experimental results of the present study provide evidence that 4-OI significantly decreased LPS-induced lung inflammation by suppressing ROS-mediated PI3K/Akt/NF-κB signaling pathways. These results suggest that 4-OI could be a valuable therapeutic drug in the treatment of ALI.