β-arrestin 2 attenuates lipopolysaccharide-induced liver injury via inhibition of TLR4/NF-κB signaling pathwaymediated inflammation in mice

AIM To study the role and the possible mechanism of β-arrestin 2 in lipopolysaccharide(LPS)-induced liver injury in vivo and in vitro.METHODS Male β-arrestin 2^(+/+) and β-arrestin 2^(-/-)C57 BL/6 J mice were used for in vivo experiments, and the mouse macrophage cell line RAW264.7 was used for in vitro experiments. The animal model was established via intraperitoneal injection of LPS or physiological sodium chloride solution. Blood samples and liver tissues were collected to analyze liver injury and levels of pro-inflammatory cytokines. Cultured cell extracts were collected to analyze the production of pro-inflammatory cytokines and expression of key molecules involved in the TLR4/NF-κB signaling pathway.RESULTS Compared with wild-type mice, the β-arrestin 2 knockout mice displayed more severe LPS-induced liver injury and significantly higher levels of proinflammatory cytokines, including interleukin(IL)-1β, IL-6, tumor necrosis factor(TNF)-α, and IL-10. Compared with the control group, pro-inflammatory cytokines(including IL-1β, IL-6, TNF-α, and IL-10) produced by RAW264.7 cells in the β-arrestin 2 si RNA group were significantly increased at 6 h after treatment with LPS. Further, key molecules involved in the TLR4/NF-κB signaling pathway, including phosphoIκBα and phosho-p65, were upregulated.CONCLUSION β-arrestin 2 can protect liver tissue from LPS-induced injury via inhibition of TLR4/NF-κB signaling pathwaymediated inflammation.

Study on the Hepatoprotective Effect of Oxalis coriniculata L. and Related Mechanism by Regulating Oxidative Stress and TLR-2/NF-κB Signaling Pathway

[Objectives]This study aimed to explore the protective effect of Oxalis coriniculata L.on rats with acute liver injury induced by carbon tetrachloride(CCl4)and related mechanism by regulating oxidative stress and the TLR-2 TLR-2/NF-κB signaling pathway.[Methods]A total of 48 female rats were randomly and evenly divided into normal group,model group,silymarin group(0.12 g/kg),and high(16 g/kg),middle(8 g/kg)and low-dose(4 g/kg)O.coriniculata L.groups.The rats in the groups were intragastrically administered with 5 mL/kg of corresponding drugs(equal-volume distilled water for normal group and control group),respectively.The administration was conducted twice a day,for 10 consecutive days.After 2 h of the last administration,the rats in all the groups except the normal group were intraperitoneally injected with 12%carbon tetrachloride(CCl4)olive oil solution(5 mL/kg),respectively to establish liver injury rat models.After 16 h,the eyeball blood of the rats was collected,and their liver tissues were collected for preparation of HE sections.The biochemical indicators detected included aspartate aminotransferase(AST),alanine aminotransferase(ALT),total superoxide dismutase(T-SOD)and glutathione peroxidase(GSH-Px)activity and malondialdehyde(MDA)content in the serum.The contents of tumor necrosis factor-α(TNF-α),interleukin-1β(IL-1β)and interleukin-6(IL-6)in the serum were detected by ELISA.The expression of Toll-like receptor-2(TLR-2)and nuclear factor-κB(NF-κB)in liver tissue was detected using Western blotting.The pathological changes of liver were observed under light microscope.[Results]Compared with the normal group,the ALT,AST activity and MDA,IL-1β,IL-6,TNF-αlevels in rat serum significantly increased(P<0.01),the GSH-Px,T-SOD activity in rat serum significantly decreased(P<0.01),and the expression of TLR-2 and NF-κB in liver tissue was up-regulated(P<0.01)in the model group.Compared with the model group,the ALT,AST activity and MDA,IL-1β,IL-6 and TNF-αlevels in rat serum reduced(P<0.05,P<0.01),the GSH-Px and T-SOD activity in rat serum increased(P<0.05,P<0.01),and the expression of TLR-2 and NF-κB in liver tissue was down-regulated(P<0.05,P<0.01)in the O.coriniculata L.administration groups.Pathological sections show that O.coriniculata L.had an improving effect on rats with acute liver injury induced by CCl4.[Conclusions]O.coriniculata L.has a good protective effect on rats with acute liver injury induced by CCl4.Its mechanism may be related to inhibition of oxidative stress,inhibition of inflammatory response and regulation of the TLR-2/NF-κB signaling pathway.

Fucoxanthin suppresses OxLDL-induced inflammation via activation of Nrf2 and inhibition of NF-κB signaling

Objective:To explore the impact of fucoxanthin on oxidized low-density lipoprotein(OxLDL)-induced stress and inflammation in human endothelial cells and its underlying mechanisms.Methods:HUVECs were treated with OxLDL and/or fucoxanthin for a range of time points and concentrations.We evaluated the effects of fucoxanthin on OxLDL-induced HUVECs using the MTT assay,reactive oxygen species accumulation assay,ELISA,RT-PCR,immunofluorescence,and Western blotting.Results:Fucoxanthin enhanced the cell viability in a dose dependent manner after OxLDL exposure.Furthermore,fucoxanthin pretreatment significantly decreased OxLDL-induced reactive oxygen species production and prevented the activation of the nuclear factor kappa-B pathway,which led to substantial suppression of pro-inflammatory gene expressions.OxLDL-induced upregulation of interleukin-6,intercellular adhesion molecule-1,vascular cell adhesion molecule-1,interleukin-1β,monocyte chemotactic protein-1,cyclooxygenase-1,and tumor necrosis factor-αwas significantly reduced by fucoxanthin.Conclusions:Fucoxanthin can inhibit OxLDL-induced vascular inflammation and oxidative stress in HUVECs by targeting Nrf2 signaling pathways.

甘草甜素调节Drd2/Cryab/NF-κB信号通路对新生大鼠缺氧缺血性脑损伤的治疗作用

目的:探究甘草甜素(GL)调节多巴胺D2受体(Drd2)/α-B晶状体蛋白(Cryab)/核转录因子-κB(NF-κB)信号通路对新生大鼠缺氧缺血性脑损伤(HIBD)的治疗作用。方法:从60只产后第7 d的新生大鼠中选取12只为假手术组,其余新生大鼠均采用Rice-Vannucci法建立HIBD新生大鼠模型。将造模成功的36只新生大鼠采用随机数字表法分为HIBD组、GL组、氟哌啶醇组(Drd2抑制剂),每组12只。对各组新生大鼠进行神经功能缺损评分及脑含水量测定;苏木素-伊红染色法(HE)及尼氏(Nissl)染色观察海马组织病理改变;脱氧核糖核苷酸末端转移酶介导的缺口末端标记法(TUNEL)染色检测神经细胞凋亡;酶联免疫吸附法(ELISA)法检测血清中肿瘤坏死因子(TNF-α)、白细胞介素-6(IL-6)水平;免疫印记法(Western blot)检测海马组织中Drd2/Cryab/NF-κB通路蛋白表达。结果:与假手术组比较,HIBD组海马CA1结构模糊不清,神经元排列无序,尼氏小体数量减少,神经功能缺损评分、脑含水量、神经元凋亡率、TNF-α、IL-6、p-NF-κB/NF-κB蛋白表达升高,Drd2、Cryab蛋白表达降低(P<0.05);与HIBD组比较,GL组神经元排列相对整齐,尼氏小体数量增多,神经功能缺损评分及脑含水量、神经元凋亡率、TNF-α、IL-6、p-NF-κB/NF-κB蛋白表达降低,Drd2、Cryab蛋白表达升高(P<0.05);与GL组比较,氟哌啶醇组上述指标均显著逆转(P<0.05)。结论:GL可抑制HIBD新生大鼠炎症反应和神经细胞凋亡,减轻HIBD新生大鼠神经损伤,其作用机制可能与激活Drd2/Cryab/NF-κB信号通路有关。

Photothermal therapy with regulated Nrf2/NF-κB signaling pathway for treating bacteria-induced periodontitis

Periodontitis is an inflammatory disease initiated by bacterial infection,developed by excessive immune response,and aggravated by high level of reactive oxygen species(ROS).Hence,herein,a versatile metal-organic framework(MOF)-based nanoplatform is prepared using mesoporous Prussian blue(MPB)nanoparticles to load BA,denoted as MPB-BA.The established MPB-BA nanoplatform serves as a shelter and reservoir for vulnerable immunomodulatory drug BA,which possesses antioxidant,anti-inflammatory and anti-bacterial effects.Thus,MPB-BA can exert its antioxidant,anti-inflammatory functions through scavenging intracellular ROS to switch macrophages from M1 to M2 phenotype so as to relieve inflammation.The underlying molecular mechanism lies in the upregulation of phosphorylated nuclear factor erythroid 2-related factor 2(Nrf2)to scavenge ROS and subsequently inhibit the nuclear factor kappa-B(NF-κB)signal pathway.Moreover,MPB-BA also exhibited efficient photothermal antibacterial activity against periodontal pathogens under near-infrared(NIR)light irradiation.In vivo RNA sequencing results revealed the high involvement of both antioxidant and anti-inflammatory pathways after MPB-BA application.Meanwhile,micro-CT and immunohistochemical staining of p-Nrf2 and p-P65 further confirmed the superior therapeutic effects of MPB-BA than minocycline hydrochloride.This work may provide an insight into the treatment of periodontitis by regulating Nrf2/NF-κB signaling pathway through photothermal bioplatform-assisted immunotherapy.

Attenuation of lipopolysaccharide-induced neuroinflammatory events in BV-2 microglial cells by Moringa oleifera leaf extract

Objective: To determine the anti-neuroinflammatory activity of Moringa oleifera leaf extract(MLE) under lipopolysaccharide stimulation of mouse murine microglia BV2 cells in vitro. Methods: The cytotoxicity effect of MLE was investigated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide assay. The inflammatory response of BV-2 cells were induced with lipopolysaccharide. The generation of nitric oxide levels was determined by using Griess assay and the level of pro-inflammatory cytokines(IL-1β, IL-6 and TNF-α) was evaluated by ELISA kit. The expression of iNOS, COX-2 as well as IκB-ααwas carried out by immunoblot analysis. Results: MLE reduced the nitric oxide production in concentration-dependent manner, and maintained the viability of BV-2 microglial cells which indicated absence of toxicity. In addition, MLE repressed the activation of nuclear factor kappa B by arresting the deterioration of IκB-α, consequently resulted in suppression of cytokines expression such as COX-2 and iNOS. Conclusions: MLE inhibitory activities are associated with the inhibition of nuclear factor kappa B transcriptional activity in BV2 microglial cells. Thus MLE may offer a substantial treatment for neuroinflammatory diseases.

Discovery of novel aporphine alkaloid derivative as potent TLR2 antagonist reversing macrophage polarization and neutrophil infiltration against acute inflammation

Toll-like receptor 2(TLR2)mediated macrophages regulate the protective immune response to infectious microorganisms,but the aberrant activation of macrophages often leads to pathological inflammation,including tissue damage.In this study,we identified antagonists of TLR2 by screening2100 natural products and subsequently identified Taspine,an aporphine alkaloid,as an excellent candidate.Furthermore,analysis of the 10 steps chemical synthesis route and structural optimization yielded the Taspine derivative SMU-Y6,which has higher activity,better solubility,and improved drug-feasible property.Mechanistic studies and seq-RNA analysis revealed that SMU-Y6 inhibited TLR2 over other TLRs,hindered the formation of TLR2/MyD88 complex,and blocked the downstream NF-κB and MAPK signaling pathway,thus suppressing the release of inflammatory cytokines.SMU-Y6 could stabilize TLR2 and bind to TLR2 protein with a Kdof 0.18μmol/L.Additionally,SMU-Y6 could efficiently reverse the M1 phenotype macrophage polarization,reduce the production of cytokines as well as infiltration of neutrophiles and alleviate the local inflammation in mice with acute paw edema and colitis.Collectively,we reported the first aporphine alkaloid derivative that selectively inhibits TLR2 with high binding affinity and superior drug-feasible property,thus providing an urgently-needed molecular probe and potential drug candidate for inflammatory and autoimmune disease therapy.