The Mechanism of Aureusidin in Suppressing Inflammatory Response in Acute Liver Injury by Regulating MD2

Abstract

ObjectiveIn this study, we mainly explored the mechanism and target of the anti-inflammatory effects of Aureusidin (Aur) in acute liver injury.MethodsLipopolysaccharide (LPS) was used to induce inflammatory injury in Kupffer cells (KCs) in vitro. After Aur treatment with gradient concentration, flow cytometry, propidium iodide (PI) staining, and Hoechst 33342 staining were used to detect the apoptotic level of KCs, and an enzyme-linked immunosorbent assay (ELISA) was used to detect the expression levels of inflammatory factors, including Interleukin-1β (IL-1β), Interleukin-18 (IL-18), and tumor necrosis factor alpha (TNF-α). Western blot was used to detect the expression of toll-like receptor 4 (TLR4), myeloid differentiation protein-2 (MD2), MyD88, and p-P65. Aur was labeled with biotin, followed by a pull-down assay to detect its binding with MD2. Moreover, D-GalN/LPS was used to induce acute liver injury in mice in vitro, followed by Aur treatment by gavage. H&E staining was used to detect the pathological changes of liver tissue, an IF assay was used to detect the expression of MD2, Western blot was used to detect the expression of relevant proteins.ResultsAur pretreatment could significantly inhibit LPS-induced KC injury, downregulate the apoptotic level, inhibit the expression of inflammatory factors, decrease the level of MDA, and downregulate the expression of MD2 in cells. Aur could inhibit the activation level of TLR4/MD2-NF-κB in a dose-dependent pattern, a high dose of Aur had a superior effect compared to low-dose Aur. In the case of MD2 deletion, the effects of Aur were suppressed. Additionally, pull-down and co-immunoprecipitation assays show that Aur can bind with the MD2 protein to inhibit the activation of TLR4/MD2-NF-κB. Results of mice experiments also showed that Aur could relieve liver injury, decrease the levels of ALT and AST, and simultaneously downregulate the levels of inflammatory factors in tissues and peripheral blood.ConclusionWe found that Aur exerted an anti-inflammatory effect by directly targeting the MD2 protein, further inhibiting the expression of TLR4/MD2-NF-κB, thereby relieving acute liver injury. Therefore, Aur might be a potential inhibitor for MD2.

Protective Role of 4‐Octyl Itaconate in Murine LPS/D‐GalN‐Induced Acute Liver Failure via Inhibiting Inflammation, Oxidative Stress, and Apoptosis

“…The animals were raised according to the National Health Guidelines for the Care and Use of Laboratory Animals. ALF model was performed as described previously with minor alteration [ 8 ]. To determine a suitable dose for the next experiment, mice were divided into 5 groups ( n = 6 to 12/per group).…”

“…D-Galactosamine (D-GalN) is a hexosamine derived from galactose which can cause hepatic damage [ 7 ]. LPS and D-GalN can lead to hepatic injury in the mouse, which is similar to fulminant hepatic failure in clinic [ 8 ]. Therefore, a LPS/D-GalN-induced hepatic injury model has been widely used to explore potential hepatoprotective medicines.…”

Aureusidin derivative CNQX inhibits chronic colitis inflammation and mucosal barrier damage by targeting myeloid differentiation 2 protein

“…Suppression of MD2 level can inhibit the activation of TLR4 signalling and inhibit mucosal barrier damage caused by inflammation. Additionally, our previous study has also demonstrated that aureusidin is an effective inhibitor of MD2 to suppress inflammation 14 . In this study, we modified the structure of aureusidin and found that CNQX had anti‐inflammatory effects.…”

“…The preliminary study of our group has found that aureusidin is a small molecule targeting MD2 through screening and research. Through liver injury models, pull‐down and immunoprecipitation assays have shown that aureusidin can inhibit the activation of TLR4/MD2‐NF‐κB by binding to the MD2 protein 14 . Further structural modification identified that an open‐loop derivative CNQX exerted a significant anti‐inflammatory effect.…”

Mammalian Arginase Inhibitory Activity of Methanolic Extracts and Isolated Compounds from Cyperus Species

“…This molecule, which rarely occurs in nature, was previously isolated from mosses marine brown algae and flowering plants [ 24 , 25 ]. Aureusidin possesses a pharmacological profile showing high antioxidant and lipoxygenase inhibitory activity [ 26 ], as well as anti-inflammatory effects [ 27 , 28 ]. Luteolin ( 7 ), a flavone, which is abundant in edible plants, displays a wide range of biological activities including antioxidant, anti-carcinogenic [ 29 ], cardioprotective [ 30 ], anti-inflammatory, and antipruritic [ 31 ] activities.…”