Protective Effect of Silibinin on Lipopolysaccharide-Induced Endotoxemia by Inhibiting Caspase-11-Dependent Cell Pyroptosis.

OBJECTIVE: To explore the protective effect and the underlying mechanism of silibinin (SIB), one of the active compounds from Silybum marianum (L.) Gaertn in endotoxemia. METHODS: Mouse peritoneal macrophage were isolated via intraperitoneally injection of BALB/c mice with thioglycolate medium. Cell viability was assessed using the cell counting kit-8, while cytotoxicity was determined through lactate dehydrogenase cytotoxicity assay. The protein expressions of interleukin (IL)-1 α, IL-1 ß, and IL-18 were determined by enzyme-linked immunosorbent assay. Intracellular lipopolysaccharide (LPS) levels were measured by employing both the limulus amoebocyte lysate assay and flow cytometry. Additionally, proximity ligation assay was employed for the LPS and caspase-11 interaction. Mice were divided into 4 groups: the control, LPS, high-dose-SIB (100 mg/kg), and low-dose-SIB (100 mg/kg) groups (n=8). Zebrafish were divided into 4 groups: the control, LPS, high-dose-SIB (200 εmol/L), and low-dose-SIB (100 εmol/L) groups (n=30 for survival experiment and n=10 for gene expression analysis). The expression of caspase-11, gasdermin D (GSDMD), and N-GSDMD was determined by Western blot and the expressions of caspy2, gsdmeb, and IL-1 ß were detected using quantitative real-time PCR. Histopathological observation was performed through hematoxylineosin staining, and protein levels in bronchoalveolar lavage fluid were quantified using the bicinchoninicacid protein assay. RESULTS: SIB noticeably decreased caspase-11 and GSDMD-mediated pyroptosis and suppressed the secretion of IL-1 α, IL-1 ß, and IL-18 induced by LPS (P<0.05). Moreover, SIB inhibited the translocation of LPS into the cytoplasm and the binding of caspase-11 and intracellular LPS (P<0.05). SIB also attenuated the expression of caspase-11 and N-terminal fragments of GSDMD, inhibited the relative cytokines, prolonged the survival time, and up-regulated the survival rate in the endotoxemia models (P<0.05). CONCLUSIONS: SIB can inhibit pyroptosis in the LPS-mediated endotoxemia model, at least in part, by inhibiting the caspase-11-mediated cleavage of GSDMD. Additionally, SIB inhibits the interaction of LPS and caspase-11 and inhibits the LPS-mediated up-regulation of caspase-11 expression, which relieves caspase-11-dependent cell pyroptosis and consequently attenuates LPS-mediated lethality.

Ethyl Lithospermate Reduces Lipopolysaccharide-Induced Inflammation through Inhibiting NF-κB and STAT3 Pathways in RAW 264.7 Cells and Zebrafish.

OBJECTIVE: To explore the anti-inflammatory effects of ethyl lithospermate in lipopolysaccharide (LPS)-stimulated RAW 264.7 murine-derived macrophages and zebrafish, and its underlying mechanisms. METHODS: 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazoliumbromide (MTT) assays were performed to investigate the toxicity of ethyl lithospermate at different concentrations (12.5-100 µ mol/L) in RAW 264.7 cells. The cells were stimulated with LPS (100 ng/mL) for 12 h to establish an inflammation model in vitro, the production of pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor α (TNF-α) were assessed by enzyme linked immunosorbent assay (ELISA). Western blot was used to ascertain the protein expressions of signal transducer and activator of transcription 3 (STAT3), nuclear factor kappa B (NF-κB) p65, phospho-STAT3 (p-STAT3, Tyr705), inhibitor of NF-κB (IκB) α, and phospho-I κB α (p-IκB α, Ser32), and confocal imaging was used to identify the nuclear translocation of NF-κB p65 and p-STAT3 (Tyr705). Additionally, the yolk sacs of zebrafish (3 days post fertilization) were injected with 2 nL LPS (0.5 mg/mL) to induce an inflammation model in vivo. Survival analysis, hematoxylin-eosin (HE) staining, observation of neutrophil migration, and quantitative real-time polymerase chain reaction (qRT-PCR) were used to further study the anti-inflammatory effects of ethyl lithospermate and its probable mechanisms in vivo. RESULTS: The non-toxic concentrations of ethyl lithospermate have been found to range from 12.5 to 100 µ mol/L. Ethyl lithospermate inhibited the release of IL-6 and TNF-α(P<0.05 or P<0.01), decreased IκBα degradation and phosphorylation (P<0.05) as well as the nuclear translocation of NF-κB p65 and p-STAT3 (Tyr705) in LPS-induced RAW 264.7 cells (P<0.01). Ethyl lithospermate also decreased inflammatory cells infiltration and neutrophil migration while increasing the survival rate of LPS-stimulated zebrafish (P<0.05 or P<0.01). In addition, ethyl lithospermate also inhibited the mRNA expression levels of of IL-6, TNF-α, IκBα, STAT3, and NF-κB in LPS-stimulated zebrafish (P<0.01). CONCLUSION: Ethyl lithospermate exerts anti-Inflammatory effected by inhibiting the NF-κB and STAT3 signal pathways in RAW 264.7 macrophages and zebrafish.

Liang-Ge-San inhibits dengue virus serotype 2 infection by reducing caveolin1-induced cytoplasmic heat shock protein 70 translocation into the plasma membrane.

BACKGROUND: Dengue virus (DENV) is a major public health threat. However, there are no specific therapeutic drugs for DENV. Many Chinese heat-cleaning formulas, such as Liang-Ge-San (LGS), have been frequently used in the virus-induced diseases. The antiviral effect of LGS has not been reported yet. PURPOSE: In this study, the effect of LGS on the inhibition of dengue virus serotype 2 (DENV-2) was investigated and the relevant mechanism was explored. METHODS: High-performance liquid chromatography was applied to analyze the chemical characterization of LGS. The in vitro antiviral activities of LGS against DENV-2 were evaluated by time-of-drug-addition assay. The binding of heat shock protein 70 (Hsp70) and envelope (E) protein or caveolin1 (Cav1) were analyzed by immunofluorescence and immunoprecipitation assays. Then the role of Cav1 in the anti-DENV-2 effects of LGS was further examined. DENV-2 infected Institute of Cancer Research suckling mice (n = 10) and AG129 mice (n = 8) were used to examine the protective effects of LGS. RESULTS: It was found that geniposide, liquiritin, forsythenside A, forsythin, baicalin, baicalein, rhein, and emodin maybe the characteristic components of LGS. LGS inhibited the early stage of DENV-2 infection, decreased the expression levels of viral E and non-structural protein 1 (NS1) proteins. LGS also reduced E protein and Hsp70 binding and attenuated the translocation of Hsp70 from cytoplasm to the cell membrane. Moreover, LGS decreased the binding of Hsp70 to Cav1. Further study showed that the overexpression of Cav1 reversed LGS-mediated E protein and Hsp70 inhibition in the plasma membrane. In the in vivo study, LGS was highly effective in prolonging the survival time, reducing viral loads. CONCLUSION: This work demonstrates for the first time that LGS exerts anti-DENV-2 activity in vitro and in vivo. LGS decreases DENV-2-stimulated cytoplasmic Hsp70 translocation into the plasma membrane by Cav1 inhibition, thereby inhibiting the early stage of virus infection. These findings indicate that LGS may be a candidate for the treatment of DENV.

Salvianolic acids from Salvia miltiorrhiza Bunge and their anti-inflammatory effects through the activation of α7nAchR signaling.

ETHNOPHARMACOLOGICAL RELEVANCE: Cardiovascular disease (CVD) is a serious disease with a high incidence rate and mortality. Inflammation is closely related to the occurrence of CVDs. As an essential medicine of promoting blood circulation and removing blood stasis in China, Salvia miltiorrhiza Bunge (Danshen) is widely used to treat CVDs due to its anti-inflammatory and cardiovascular protective effects. Salvianolic acids are the most abundant component in the water extract of S. miltiorrhiza, which has a significant effect on the treatment of CVDs. However, due to the complex composition of salvianolic acids, the active molecules and their underlying mechanisms have not been fully explored. AIM OF THIS STUDY: The present study aims to isolate and identify salvianolic acids from Danshen with anti-inflammatory activity and explore the potential mechanisms of isolates. METHODS: The structures of isolated salvianolic acids were elucidated by UV, IR, NMR, MS and electronic circular dichroism (ECD) calculations. Then anti-inflammatory activities of isolates were screened out by the zebrafish inflammation models. The most active compound was further used to explore the anti-inflammatory mechanisms on LPS-stimulated RAW 264.7 cells. The key inflammatory cytokines IL-6 and TNF-α were measured by enzyme-linked immunosorbent assay (ELISA). The protein expression levels of STAT3, p-STAT3 (Tyr705), NF-κB p65, IκBα, p-IκBα (Ser32) and α7nAchR were determined by Western blotting. The nuclear translocation of p-STAT3 (Tyr705) and NF-κB p65 was evaluated by immunofluorescence assays. Finally, the in vivo anti-inflammatory mechanisms were investigated by observation of neutrophil migration, H&E staining, survival analysis and quantitative PCR (Q-PCR) in LPS-microinjected zebrafish. RESULTS: Two new and four known compounds were isolated from Danshen. Among them, isosalvianolic acid A-1 (C1) and ethyl lithospermate (C5) inhibited neutrophil migrations in three zebrafish inflammation models and C1 with the best activities decreased the secretion of IL-6 and TNF-α and inhibited the expression level of p-IκBα (Ser32) in LPS stimulated RAW 264.7 cells. In addition, C1 also reduced the nuclear translocation of NF-κB p65 and p-STAT3 (Tyr705). Moreover, C1 significantly upregulated the protein expression of α7nAchR, and the knockdown of α7nAchR counteracted the effects of C1 on the production of IL-6 and TNF-α and the expression levels of p-STAT3 (Tyr705), NF-κB p65 and p-IκBα (Ser32). In vivo experiments, C1 decreased the migration and infiltration of inflammatory cells, increased the survival ratio and inhibited the mRNA level of IL-6, TNF-α, STAT3, NF-κB and IκBα in LPS-microinjected zebrafish. CONCLUSION: Two new and four known compounds were isolated from Danshen. Among them, C1 exerted anti-inflammatory activities by activating α7nAchR signaling and subsequently inhibiting STAT3 and NF-κB pathways. This study provided evidence for the clinical application of Danshen and contributed to the development of C1 as a novel in the treatment of cardiovascular disease.

N-Butanol Extract of Glycyrrhizae Radix et Rhizoma Inhibits Dengue Virus through Targeting Envelope Protein.

BACKGROUND: At present, about half of the world's population is at risk of being infected with dengue virus (DENV). However, there are no specific drugs to prevent or treat DENV infection. Glycyrrhizae Radix et Rhizome, a well-known traditional Chinese medicine, performs multiple pharmacological activities, including exerting antiviral effects. The aim of this study was to investigate the anti-DENV effects of n-butanol extract from Glycyrrhizae Radix et Rhizome (GRE). METHODS: Compounds analysis of GRE was conducted via ultra-performance liquid chromatography/tandem mass spectrometry (UHPLC-MS/MS). The antiviral activities of GRE were determined by the CCK-8 assay, plaque assay, qRT-PCR, Western blotting, and the immunofluorescence assay. The DENV-infected suckling mice model was constructed to explore the antiviral effects of GRE in vivo. RESULTS: Four components in GRE were analyzed by UHPLC-MS/MS, including glycyrrhizic acid, glycyrrhetnic acid, liquiritigenin, and isoliquiritigenin. GRE inhibited the attachment process of the virus replication cycle and reduced the expression of the E protein in cell models. In the in vivo study, GRE significantly relieved clinical symptoms and prolong survival duration. GRE also significantly decreased viremia, reduced the viral load in multiple organs, and inhibited the release of pro-inflammatory cytokines in DENV-infected suckling mice. CONCLUSIONS: GRE exhibited significant inhibitory activities in the adsorption stage of the DENV-2 replication cycle by targeting the envelope protein. Thus, GRE might be a promising candidate for the treatment of DENV infection.