基于MyD88/ERK通路及NF-κB核移位探讨大黄素对局灶性脑缺血大鼠的作用及机制

目的基于髓样分化因子88(MyD88)/细胞外信号调节激酶(ERK)通路及核因子κB(NF-κB)核移位探讨大黄素对局灶性脑缺血大鼠的作用及机制。方法将SD大鼠按随机数字表法分为假手术组、模型组、大黄素组,每组6只,采用大脑中动脉栓塞法建立大脑中动脉短暂性闭塞模型(tMCAO)。大黄素组大鼠于造模前72、48、24 h,分别给予40 mg·kg-1大黄素灌胃给药,共3次。造模结束后24 h,对大鼠进行神经功能评分;采用TTC染色法检测脑组织梗死灶面积;HE染色法观察脑组织形态变化;RT-qPCR法检测脑组织中MyD88、肿瘤坏死因子α(TNF-α)mRNA表达水平;Western Blot法检测脑组织中MyD88、ERK、p-ERK、TNF-α蛋白表达水平;免疫荧光法检测脑组织中NF-κB蛋白表达。结果与假手术组比较,模型组大鼠神经功能评分显著升高(P<0.01),脑梗死面积显著增加(P<0.01);缺血半暗带皮质区中出现细胞坏死,细胞形态异常,胞核破碎萎缩,细胞数量明显降低;脑组织中MyD88、TNF-αmRNA表达水平显著升高(P<0.01,P<0.001),MyD88、p-ERK/ERK、TNF-α蛋白表达水平均明显升高(P<0.05,P<0.01,P<0.001),NF-κB入核细胞数占比显著升高(P<0.001)。与模型组比较,大黄素组大鼠的神经功能评分明显降低(P<0.05),脑梗死面积明显缩小(P<0.05);缺血半暗带皮质区的神经元数量及形态得到一定程度恢复;脑组织中MyD88、TNF-αmRNA表达水平均明显降低(P<0.05,P<0.01),MyD88、p-ERK/ERK、TNF-α蛋白表达水平均明显降低(P<0.05),NF-κB入核细胞数占比显著降低(P<0.001)。结论大黄素对局灶性脑缺血大鼠具有预防保护作用,可能与其抑制MyD88活化、ERK磷酸化及NF-κB核移位,进而下调炎症级联反应及TNF-α等促炎因子分泌,从而发挥抗炎作用有关。

Ramulus Cinnamomi extract attenuates neuroinflammatory responses via downregulating TLR4/MyD88 signaling pathway in BV2 cells

Ramulus Cinnamomi （RC）, a traditional Chinese herb, has been used to attenuate inflammatory responses. The purpose of this study was to investigate the effect of RC extract on lipopolysaccharide （LPS）-induced neuroinflammation in BV2 microglial cells and the underlying mechanisms involved. BV2 cells were incubated with normal medium （control group）, LPS, LPS plus 30 pg/mL RC extract, or LPS plus 100 pg/mL RC extract. The BV2 cell morphology was observed under an optical microscope and cell viability was detected by MTT assay. Nitric oxide level in BV2 cells was detected using Griess regents, and the levels of interleukin-6, interleukin-1 β, and tumor necrosis factor u in BV2 cells were determined by ELISA. The expression levels of cyclooxygenase-2, Toll-like receptor 4 and myeloid differentiation factor 88 proteins were detected by western blot assay. Compared with the LPS group, both 30 and 100 μg/mL RC extract had no significant effect on the viability of BV2 cells. The levels of nitric oxide, interleukin-6, interleukin-1β and tumor necrosis factor ct in BV2 cells were all significantly increased after LPS induction, and the levels were significantly reversed after treatment with 30 and 100 μg/mL RC extract. Furthermore, RC extract significantly inhibited the protein expression levels of cyclooxygenase-2, Toll-like receptor 4 and myeloid differentiation factor 88 in LPS-induced BV2 cells. Our findings suggest that RC extract alleviates neuroinflammation by downregulating the TLR4/MyD88 signaling pathway.

IL-1RⅠ/MyD88-TIR mimic AS-1 inhibits the activation of MyD88-dependent signaling pathway induced by IL-1β in vitro

Objective： To test whether IL-1 RI/My088-TIR mimic AS-1 can work as a new compound that targeted at blocking MyD88- dependent signaling pathway, we investigated the physical structure and biological function of AS-1. Methods：The crystallographic structure of AS-1 was examined by 1^H nuclear magnetic resonance. The toxicity of AS-1 was measured with Methyl thiazolyl tetrazolium （MTT） assay. The effect of AS-1 on phosphorylation state of p38 MAPK and IRAK-1 was observed with Western blot. Results：The crystallographic details of AS-1 demonstrated that it was a tri-peptide sequence[（F/Y）-（V/L/I）-（P/G）] of the IL-1R I -TIR domain BBloop. No toxicity of AS-1 was shown to HEK 293A cells. The phosphorylation of p38 MAPK, induced by IL-1β significantly increased from those in the control group. AS-1 significantly reduced the phosphorylation of p38 MAPK induced by IL-1β. IL-1β increased the phosphorylation of IRAK-1 significantly, which was prevented by AS-1. Conclusion：AS-1 is a competitive mimic between IL-1R I-TIR and MyD88-TIR domain, which most likely interferes with MyD88-dependent signaling pathway.

Neuroprotective effect of Angiopep-2 peptide modified scutellarin-loaded PEGylated PAMAM dendrimer nanoparticles on ischemic stroke by modulating the Toll-like receptors-dependent MyD88/IKK/NF-κB signaling pathway

OBJECTIVE The greatest challenge in chemotherapy of ischemic stroke is the construction a suitable delivery system to overcome the poor physicochemical properties of drug and its low permeability across the blood brain barrier(BBB).METHODS In the present study,dendrimer,polyamidoamine(PAMAM),was synthesized as the nano-drug carriers.Angiopep-2,which has been proved excellent ability to cross the BBB,was exploited as the targeting ligand to conjugate PAMAM via bifunctional polyethylene glycol(PEG).Then scutellarin(STA)was encapsulated into the functionalized nanoparticles(NPs)to formulate Angiopep-2 modified STA-loaded PEG-PAMAM NPs.Ischemic stroke model was established to evaluate the treatment efficacy and protective mechanism of Angiopep-2-STA-PEG-PAMAM NPs.RESULTS The pharmacokinetics and biodistribu-tion demonstrated that Angiopep-2-STA-PEG-PAMAM NPs exhibited significantly higher plasma concentration from 1 h to 10 h after intravenous administration and improve accumulation in brain(4.7-fold)compared with STA solution.Moreover,prolonged elimination half-life(4.8-fold)and lower clearance(3.4-fold)were observed.The brain uptake study of 6-coumarin confirmed that Angiopep-2-PEG-PAMAM NPs possessed better brain targeting efficacy(3.2-fold)than PEG-PAMAM NPs.Angiopep-2-STA-PEG-PAMAM NPs obviously ameliorated infarct volume,neurological deficit,histopathological severity and neuronal apoptosis.In addition,Angiopep-2-STA-PEG-PAMAM NPs markedly inhibited the calcium content and the levels of IL-12p40,IL-13,IL-17 and IL-23.Furthermore,Angiopep-2-STA-PEG-PAMAM NPs significantly decreased the m RNA and protein expressions of HMGB1,TLR2,TLR4,TLR5,My D88,TRIF,TRAM,IRAK-4,TRAF6,IкBα,IKKβand NF-кBp65.CONCLUSION The results suggested that Angiopep-2modified scutellarin-loaded PEG-PAMAM nanocarriers possessed remarkable neuroprotective effects on ischemic stroke through modulation of inflammatory cascades and HMGB1/TLRs/MyD 88-induced NF-κB activation pathways.

Correlation of MyD88 expression in the peripheral blood and placenta with the inflammatory response and insulin signal transduction in the placenta of patients with GDM

Objective: To study the correlation of MyD88 expression in peripheral blood and placenta with the inflammatory response and insulin signal transduction in the placenta of patients with gestational diabetes mellitus (GDM). Methods: The patients with GDM and healthy pregnant women who accepted antenatal care and gave birth in Guangyuan First People's Hospital between March 2015 and June 2017 were selected as the research subjects and enrolled in the GDM group and control group for the study respectively;the peripheral blood was collected before delivery to determine the MyD88 mRNA expression, and the placental tissue was collected after delivery to determine the mRNA expression of MyD88, inflammatory response molecules and insulin signal transduction molecules. Results: MyD88 mRNA expression levels in the peripheral blood and placenta of GDM group were significantly higher than those of control group, and the MyD88 mRNA expression in the peripheral blood was positively correlated with the MyD88 mRNA expression in the placenta;IL-1β, IL-6, RBP4, Chemerin, Resistin and PTP1B mRNA expression levels in the placenta of GDM group were significantly higher than those of control group whereas IRS1, ISR2, p-PI3K and GLUT4 protein expression levels were significantly lower than those of control group;IL-1β, IL-6, RBP4, Chemerin, Resistin and PTP1B mRNA expression levels in the placenta of GDM group of patients with high MyD88 expression were significantly higher than those of patients with low MyD88 expression whereas IRS1, ISR2, p-PI3K and GLUT4 protein expression levels were significantly lower than those of patients with low MyD88 expression. Conclusion:The expression of MyD88 in peripheral blood and placenta increase in patients with GDM and the change of MyD88 expression in peripheral blood could reflect the abnormality of inflammatory response and insulin signal transduction in the placenta.

Bioinformatic Analysis and Experimental Verification of QJHGD on Caerulein-induced Inflammatory Response in SAP Model Rats Based on TLR4/NF-κB/My D88 Pathway

[Objectives]To conduct bioinformatic analysis and experimental verification of Qingjie Huagong Decoction(QJHGD)on caerulein-induced inflammatory response in severe acute pancreatitis(SAP)model rats based on TLR4/NF-κB/MyD88 pathway.[Methods]The effective component groups and potential targets of QJHGD were collected by the network pharmacology method.A drug-component-target network was constructed.The GO and KEGG of targets were enriched and analyzed with the aid of Metascape database,and the target pathway related to SAP inflammation was screened.The SAP rat model was established by caerulein combined with lipopolysaccharide,and QJHGD was intragastrically administered.Pancreatic tissue was observed by HE staining.In addition,enzyme-linked immunosorbent assay and immunohistochemistry were used to verify the anti-inflammatory effect of QJHGD on SAP rats and its regulatory effect on TLR4/NF-κB/MyD88 target pathway.[Results]A total of 105 active components of QJHGD and 148 key targets of SAP were predicted and screened;KEGG was enriched in 320 different pathways including toll-like receptor and NF-κB classical pathways.Animal experiment verified that QJHGD reduced serum amylase,serum lipase activity,IL-6,TNF-αlevels in SAP rats;HE staining showed the effect of QJHGD on the pathological changes of pancreas,and QJHGD inhibited the positive expression of key proteins of TLR4,NF-κB and MyD88 in the inflammatory transduction pathway.[Conclusions]The mechanism of QJHGD improving pancreatic injury in SAP rats may be related to down-regulating the expression of key proteins in the TLR4/NF-κB/MyD88 pathway.

Novel compound FLZ alleviates rotenoneinduced PD mouse model by suppressing TLR4/MyD88/NF-kB pathway through microbiotaegutebrain axis

Parkinson’s disease(PD)is the second most common neurodegenerative disease,but none of the current treatments for PD can halt the progress of the disease due to the limited understanding of the pathogenesis.In PD development,the communication between the brain and the gastrointestinal system influenced by gut microbiota is known as microbiota-gut-brain axis.However,the explicit mechanisms of microbiota dysbiosis in PD development have not been well elucidated yet.FLZ,a novel squamosamide derivative,has been proved to be effective in many PD models and is undergoing the phase I clinical trial to treat PD in China.Moreover,our previous pharmacokinetic study revealed that gut microbiota could regulate the absorption of FLZ in vivo.The aims of our study were to assess the protective effects of FLZ treatment on PD and to further explore the underlying microbiota-related mechanisms of PD by using FLZ as a tool.In the current study,chronic oral administration of rotenone was utilized to induce a mouse model to mimic the pathological process of PD.Here we revealed that FLZ treatment alleviated gastrointestinal dysfunctions,motor symptoms,and dopaminergic neuron death in rotenone-challenged mice.16 S rRNA sequencing found that PD-related microbiota alterations induced by rotenone were reversed by FLZ treatment.Remarkably,FLZ administration attenuated intestinal inflammation and gut barrier destruction,which subsequently inhibited systemic inflammation.Eventually,FLZ treatment restored blood-brain barrier structure and suppressed neuroinflammation by inhibiting the activation of astrocytes and microglia in the substantia nigra(SN).Further mechanistic research demonstrated that FLZ treatment suppressed the TLR4/MyD88/NF-κB pathway both in the SN and colon.Collectively,FLZ treatment ameliorates microbiota dysbiosis to protect the PD model via inhibiting TLR4 pathway,which contributes to one of the underlying mechanisms beneath its neuroprotective effects.Our research also supports the importance of microbiota-gut-brain axis in PD pathogenesis,suggesting its potential role as a novel therapeutic target for PD treatment.

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.

ATF4 is directly recruited by TLR4 signaling and positively regulates TLR4-trigged cytokine production in human monocytes

Toll-like receptors （TLRs） are sentinels of the host defense system, which recognize a large number of microbial pathogens. The host defense system may be inefficient or inflammatory diseases may develop if microbial recognition by TLRs and subsequent TLR-triggered cytokine production are deregulated. Activating transcription factor 4 （ATF4）, a member of the ATF/CREB transcription factor family, is an important factor that participates in several pathophysiological processes. In this report, we found that ATF4 is also involved in the TLR-mediated innate immune response, which participates in TLR4 signal transduction and mediates the secretion of a variety of cytokines. We observed that ATF4 is activated and translocates to the nucleus following l ipopolysaccharide （LPS） stimulation via the TLR4-MyD88-dependent pathway. Additionally, a cytokine array assay showed that some key inflammatory cytokines, such as I L-6, I L-8 and RANTES, are positively regulated by ATF4. We also demonstrate that c-Jun directly binds to ATF4, thereby promoting the secretion of inflammatory cytokines. Taken together, these results indicate that ATF4 acts as a positive regulator in TLR4-triggered cytokine production.