Farnesoid X Receptor Protects Murine Lung against IL-6-promoted Ferroptosis Induced by Polyriboinosinic-Polyribocytidylic Acid.

Various infections trigger a storm of proinflammatory cytokines in which IL-6 acts as a major contributor and leads to diffuse alveolar damage in patients. However, the metabolic regulatory mechanisms of IL-6 in lung injury remain unclear. Polyriboinosinic-polyribocytidylic acid [poly(I:C)] activates pattern recognition receptors involved in viral sensing and is widely used in alternative animal models of RNA virus-infected lung injury. In this study, intratracheal instillation of poly(I:C) with or without an IL-6-neutralizing antibody model was combined with metabonomics, transcriptomics, and so forth to explore the underlying molecular mechanisms of IL-6-exacerbated lung injury. We found that poly(I:C) increased the IL-6 concentration, and the upregulated IL-6 further induced lung ferroptosis, especially in alveolar epithelial type II cells. Meanwhile, lung regeneration was impaired. Mechanistically, metabolomic analysis showed that poly(I:C) significantly decreased glycolytic metabolites and increased bile acid intermediate metabolites that inhibited the bile acid nuclear receptor farnesoid X receptor (FXR), which could be reversed by IL-6-neutralizing antibody. In the ferroptosis microenvironment, IL-6 receptor monoclonal antibody tocilizumab increased FXR expression and subsequently increased the Yes-associated protein (YAP) concentration by enhancing PKM2 in A549 cells. FXR agonist GW4064 and liquiritin, a potential natural herbal ingredient as an FXR regulator, significantly attenuated lung tissue inflammation and ferroptosis while promoting pulmonary regeneration. Together, the findings of the present study provide the evidence that IL-6 promotes ferroptosis and impairs regeneration of alveolar epithelial type II cells during poly(I:C)-induced murine lung injury by regulating the FXR-PKM2-YAP axis. Targeting FXR represents a promising therapeutic strategy for IL-6-associated inflammatory lung injury.

Angong Niuhuang Wan ameliorates LPS-induced cerebrovascular edema by inhibiting blood‒brain barrier leakage and promoting the membrane expression of AQP4.

Introduction: Angong Niuhuang Wan (AGNHW), developed during the Qing dynasty (18th century) for the treatment of consciousness disturbances caused by severe infections, has been used to treat brain edema caused by ischemia‒reperfusion. However, it remains unclear whether AGNHW can ameliorate vascular-origin brain edema caused by lipopolysaccharides (LPS). This study explored the ameliorative effects of AGNHW on LPS-induced cerebrovascular edema in mice, as well as the potential underlying mechanisms. Methods: A cerebrovascular edema model was established in male C57BL/6N mice by two intraperitoneal injections of LPS (15 mg/kg), at 0 and 24 h. AGNHW was administered by gavage at doses of 0.2275 g/kg, 0.455 g/kg, and 0.91 g/kg, 2 h after LPS administration. In control mice, normal saline (NS) or AGNHW (0.455 g/kg) was administered by gavage 2 h after intraperitoneal injection of NS. The survival rate, cerebral water content, cerebral venous FITC-dextran leakage, Evans blue extravasation, and expression of vascular endothelial cadherin (VE-cadherin), zonula occludens-1 (ZO-1), claudin-5, phosphorylated caveolin-1 (CAV-1), and cytomembrane and cytoplasmic aquaporin 1 (AQP1) and aquaporin 4 (AQP4) were evaluated. The cerebral tissue phosphoproteome, blood levels of AGNHW metabolites, and the relationships between these blood metabolites and differentially phosphorylated proteins were analyzed. Results: AGNHW inhibited the LPS-induced decrease in survival rate, increase in cerebral water content, decrease in VE-Cadherin expression and increase in phosphorylated CAV-1 (P-CAV-1). AGNHW treatment increased the expression of AQP4 on astrocyte membrane after LPS injection. AGNHW also inhibited the LPS-induced increases in the phosphorylation of 21 proteins, including protein kinase C-α (PKC-α) and mitogen-activated protein kinase 1 (MAPK1), in the cerebral tissue. Eleven AGNHW metabolites were detected in the blood. These metabolites might exert therapeutic effects by regulating PKC-α and MAPK1. Conclusion: AGNHW can ameliorate cerebrovascular edema caused by LPS. This effect is associated with the inhibition of VE-Cadherin reduction and CAV-1 phosphorylation, as well as the upregulation of AQP4 expression on the astrocyte membrane, following LPS injection.