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Updated: Jun 20, 2026

Non-Invasive Endotracheal Administration of Lipopolysaccharide to Induce Acute Lung Injury in Rodents
Published on: December 5, 2025
Aryl hydrocarbon receptor in combination with Stat1 regulates LPS-induced inflammatory responses
Akihiro Kimura1, Tetsuji Naka, Taisuke Nakahama
1Laboratory of Immune Regulation, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka 565-0871, Japan.
Abstract:
Toll-like receptor (TLR) signals perform a crucial role in innate immune responses to pathogens. In this study, we found that the aryl hydrocarbon receptor (Ahr) negatively regulates inflammatory responses mediated by lipopolysaccharide (LPS) in macrophages. Ahr was induced in macrophages stimulated by LPS, but not by transforming growth factor (TGF)-beta plus interleukin (IL)-6, which can induce Ahr in naive T cells. The production of IL-6 and tumor necrosis factor (TNF)-alpha by LPS was significantly elevated in Ahr-deficient macrophages compared with that in wild-type (WT) cells. Ahr-deficient mice were more highly sensitive to LPS-induced lethal shock than WT mice. Signal transducer and activator of transcription 1 (Stat1) deficiency, as well as Ahr deficiency, augmented LPS-induced IL-6 production. We found that Ahr forms a complex with Stat1 and nuclear factor-kappa B (NF-kappaB) in macrophages stimulated by LPS, which leads to inhibition of the promoter activity of IL-6. Ahr thus plays an essential role in the negative regulation of the LPS signaling pathway through interaction with Stat1.
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