Liver X receptor agonist T0901317 alleviates sepsis-induced acute lung injury by enhancing macrophage autophagy

Ben Wang¹Xueling Wu²Yu Zhong¹Chaowang Huang¹Zhi Xu¹Liang Guo^1*

• ¹Army Medical University, Chongqing, China
• ²Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China

Objective design This study sought to identify the effects of Liver X receptor-α (LXRα) on sepsis-induced acute lung injury (ALI) and to clarify its novel regulatory mechanisms using bioinformatics and experimental methods. Materials or subjects Bioinformatics analysis of differentially expressed genes and functional annotations was performed. LPS was administered intraperitoneally to constitute an sepsis-induced ALI model in mice, and the LXR agonist T0901317 (T0) was administered to mice and RAW264.7 macrophages for LXRα activation. Hematoxylin‒eosin (H&E) staining, total protein in BALF and the TNFα and IL6 expression detected by RT‒PCR were performed to evaluate inflammatory injury in lung tissues. Autophagy was detected via immunohistochemistry, transmission electron microscopy (TEM) and western blotting. RNA sequencing was used to analyze autophagy-related genes regulated by LXRα, and cells were transfected with S100A8-siRNA to determine whether LXRα regulates inflammatory damage by regulating the autophagy-related gene S100A8. The clinical correlation between LXRα and S100A8 was determined by analysis of human transcriptome data. Results Bioinformatics analyses revealed that LXRα (NR1H3) was downregulated in sepsis-induced ALI models and LXRα may regulate autophagy. Animal and cell-based experiments further verified this phenomenon. LXR agonist T0901317 (T0) alleviated lung damage and reduced inflammatory factor expression in lung tissues and cells. After inhibiting autophagy with 3-MA, which was a autophagy inhibitor, the protective effect of T0 on inflammatory damage was inhibited. Subsequent RNA sequencing of macrophages was performed and four genes, including ABCG1, FASN, S100A8 and SNORD118 were obtained through intersecting the up- and down-regulated differential genes with an autophagy gene set. However, among them, only S100A8, which was increased in ALI and was markedly decreased after T0 treatment, exhibited a negative correlation with T0. After S100A8 knockdown in macrophages with siRNA-S100A8, TNFα expression was increased in the T0+LPS+S100A8-siRNA treated cells compared with the LPS+T0-treated cells. Analysis of human transcriptome data revealed a significant negative correlation between LXRα and S100A8 (R =( -0.98), P < 0.001). Conclusions This study suggests that T0 attenuates sepsis-induced pulmonary injury by promoting macrophage autophagy via suppressing S100A8 expression.