Pathological role of Toll-like receptor signaling in cerebral malaria

Toll-like receptors (TLRs) recognize malaria parasites or their metabolites; however, their physiological roles in malaria infection in vivo are not fully understood. Here, we show that myeloid differentiation primary response gene 88 (MyD88)-dependent TLR signaling mediates brain pathogenesis of severe malaria infection, namely cerebral malaria (CM). A significant number of MyD88-, but not TIR domain containing adaptor-inducing IFN-beta (TRIF)-deficient or wild-type (WT) mice survived CM caused by Plasmodium berghei ANKA (PbA) infection. Although systemic parasitemia was comparable, sequestration of parasite and hemozoin load in the brain blood vessels was significantly lower in MyD88-deficient mice compared with those in TRIF-deficient or WT mice. Moreover, brain-specific pathological changes were associated with MyD88-dependent infiltration of CD8+, CCR5+ T cells and CD11c+ dendritic cells, including CD11c+, NK1.1+ and B220+ cells, and up-regulation of genes such as Granzyme B, Lipocalin 2, Ccl3 and Ccr5. Further studies using mice lacking various TLRs suggest that TLR2 and TLR9, but not TLR4, 5 and 7, were involved in CM. These results strongly suggest that TLR2- and/or TLR9-mediated, MyD88-dependent brain pathogenesis may play a critical role in CM, the lethal complication during PbA infection.     

General,but not myeloid or type II lung epithelial cell,myeloid differentiation factor 88 deficiency abrogates house dust mite induced allergic lung inflammation

Asthma is a highly prevalent chronic allergic inflammatory disease of the airways affecting people worldwide. House dust mite (HDM) is the most common allergen implicated in human allergic asthma. HDM‐induced allergic responses are thought to depend upon activation of pathways involving Toll‐like receptors and their adaptor protein myeloid differentiation factor 88 (MyD88). We sought here to determine the role of MyD88 in myeloid and type II lung epithelial cells in the development of asthma‐like allergic disease using a mouse model. Repeated exposure to HDM caused allergic responses in control mice characterized by influx of eosinophils into the bronchoalveolar space and lung tissue, lung pathology and mucus production and protein leak into bronchoalveolar lavage fluid. All these responses were abrogated in mice with a general deficiency of MyD88 but unaltered in mice with MyD88 deficiency, specifically in myeloid or type II lung epithelial cells. We conclude that cells other than myeloid or type II lung epithelial cells are responsible for MyD88‐dependent HDM‐induced allergic airway inflammation.     

Human placental mesenchymal stem cells of fetal origins-alleviated inflammation and fibrosis by attenuating MyD88 signaling in bleomycin-induced pulmonary fibrosis mice

Pulmonary fibrosis is a progressive lung disease that its pathogenic mechanism currently is incompletely understood. Toll-like receptor (TLR) signaling has recently been identified as a regulator of inflammation and pulmonary fibrosis. In addition, mesenchymal stem cells (MSCs) of different origins offer a great promise in treatment of idiopathic pulmonary fibrosis (IPF). However mechanisms of pathogenic roles of TLR signaling and therapeutic effects of MSCs in the IPF remain elusive. In present study, the involvement of TLR signaling and the therapeutic role of MSCs were interrogated in MyD88-deficient mice using human placental MSCs of fetal origins (hfPMSCs). The results showed an alleviated pulmonary inflammation and fibrosis in myeloid differentiation primary response gene 88 (MyD88)-deficient mice treated with bleomycin (BLM), accompanied with a reduced TGF-β signaling and production of pro-fibrotic cytokines, including TNF-α, IL-1β. An exposure of HLF1 lung fibroblasts, A549 epithelial cells and RAW264.7 macrophages to BLM led an increased expression of key components of MyD88 and TGF-β signaling cascades. Of interest, enforced expression and inhibition of MyD88 protein resulted in an enhanced and a reduced TGF-β signaling in above cells in the presence of BLM, respectively. However, the addition of TGF-β1 showed a marginally inhibitory effect on MyD88 signaling in these cells in the absence of BLM. Importantly, the administration of hfPMSCs could significantly attenuate BLM-induced pulmonary fibrosis in mice, along with a reduced hydroxyproline (HYP) deposition, MyD88 and TGF-β signaling activation, and production of pro-fibrotic cytokines. These results may suggest an importance of MyD88/TGF-β signaling axis in the tissue homeostasis and functional integrity of lung in response to injury, which may offer a novel target for treatment of pulmonary fibrosis.     

Characterization of cellular immune response and innate immune signaling in human and nonhuman primate primary mononuclear cells exposed to Burkholderia mallei

Burkholderia pseudomallei infection causes melioidosis and is often characterized by severe sepsis. Although rare in humans, Burkholderia mallei has caused infections in laboratory workers, and the early innate cellular response to B. mallei in human and nonhuman primates has not been characterized. In this study, we examined the primary cellular immune response to B. mallei in PBMC cultures of non-human primates (NHPs), Chlorocebus aethiops (African Green Monkeys), Macaca fascicularis (Cynomolgus macaque), and Macaca mulatta (Rhesus macaque) and humans. Our results demonstrated that B. mallei elicited strong primary pro-inflammatory cytokines (IFN-γ, TNF-α, IL-1β, and IL-6) equivalent to the levels of B. pseudomallei in primary PBMC cultures of NHPs and humans. When we examined IL-1β and other cytokine responses by comparison to Escherichia coli LPS, African Green Monkeys appears to be most responsive to B. mallei than Cynomolgus or Rhesus. Characterization of the immune signaling mechanism for cellular response was conducted by using a ligand induced cell-based reporter assay, and our results demonstrated that MyD88 mediated signaling contributed to the B. mallei and B. pseudomallei induced pro-inflammatory responses. Notably, the induced reporter activity with B. mallei, B. pseudomallei, or purified LPS from these pathogens was inhibited and cytokine production was attenuated by a MyD88 inhibitor. Together, these results show that in the scenario of severe hyper-inflammatory responses to B. mallei infection, MyD88 targeted therapeutic intervention may be a successful strategy for therapy.     

PI-88抑制人食管癌TE-13细胞Matrigel裸鼠移植瘤血管新生及其机制

目的:探讨通过Matrigel与肿瘤细胞混合接种的方法构建裸鼠人食管癌Matrigel移植瘤模型的可能性,进一步研究抗肿瘤制剂PI-88对于人食管癌Matrigel移植瘤生长及血管新生的影响。方法:将食管鳞癌细胞株TE-13悬液与Matrigel胶混合,接种8只裸鼠,构建人食管癌TE-13细胞Matrigel裸鼠移植瘤模型,将其随机分为PI-88治疗组和对照组。治疗组按照20 mg/kg剂量皮下注射PI-88,1次/d(PI-88配成1 mg/ml溶液);对照组按照20 ml/kg注射生理盐水,1次/d,均连续给药2周。第2、6、10、14天记录裸鼠肿瘤体积,第15天进行增强CT扫描观察肿瘤区域显影情况。免疫组化染色观察肿瘤组织中乙酰肝素酶(heparanase,HPSE)和血管内皮生长因子(vascular endothelial growth factor,VEGF)的表达。结果:8只裸鼠均在接种当天形成移植瘤,成功构建TE-13细胞Matrigel裸鼠移植瘤模型。PI-88治疗第14天时,治疗组肿瘤体积明显小于对照组[(70.25±6.85)vs(143.13±17.18)mm3,P<0.05]。治疗第15天时,治疗组肿瘤区域CT值明显低于对照组(15.18±0.91vs 19.23±2.03,P<0.05)。治疗组肿瘤组织内HPSE与VEGF表达阳性细胞数显著低于对照组[HPSE:(28.70±6.39)vs(87.55±22.03)个,t=11.472,P<0.01;VEGF:(47.10±8.18)vs(94.40±14.47)个,t=12.727,P<0.01]。结论:Matrigel胶混合食管癌细胞接种裸鼠制备移植瘤方法可行,PI-88能够抑制人食管癌TE-13细胞Matrigel裸鼠移植瘤生长及血管新生,其作用机制可能与PI-88抑制移植瘤组织中HPSE和VEGF表达有关。     

艾灸对类风湿性关节炎大鼠关节滑膜组织Toll样受体4-骨髓样分化因子88-核转录因子-κB信号通路的影响

目的:观察艾灸对类风湿性关节炎(RA)大鼠关节滑膜组织Toll样受体4-骨髓样分化因子88-核转录因子-κB(TLR 4-MyD 88-NF-κB)信号通路的影响,进一步探讨艾灸治疗RA的作用机制。方法 :40只SD大鼠随机分为正常组、模型组、艾灸组和药物组,每组10只。采用风、寒、湿环境因素结合弗氏完全佐剂的方法复制RA模型。艾灸组以艾条悬灸大鼠"足三里""肾俞"穴,每天1次,连续治疗15d。药物组以雷公藤溶液灌胃(8.75mL/kg),每天1次,共15d。观察关节滑膜组织病理形态学变化,放射免疫法检测血清肿瘤坏死因子-α(TNF-α)、白细胞介素1(IL-1)含量,实时荧光定量PCR方法检测滑膜组织TLR 4、MyD 88、肿瘤坏死因子受体相关因子6(TRAF-6)mRNA的表达,免疫组化方法检测NF-κB p 65的表达。结果:与正常组比较,模型组滑膜组织有明显的病理改变,大量单核细胞及淋巴细胞等炎性细胞浸润,滑膜表面不整齐,滑膜增生变厚;与模型组比较,艾灸组和药物组均能明显缓解炎性细胞对滑膜的浸润,改善滑膜细胞增生反应。与正常组比较,模型组血清TNF-α、IL-1含量升高(P0.01),滑膜TLR 4mRNA、MyD 88mRNA、TRAF-6mRNA及NF-κB p 65表达均升高(P0.01);与模型组比较,艾灸组和药物组血清中TNF-α、IL-1含量降低(P0.01),滑膜TLR 4mRNA、MyD 88mRNA、TRAF-6mRNA及NF-κB p 65表达均降低(P0.01,P0.05)。结论:艾灸具有调节细胞因子的作用,其机制可能与艾灸抑制滑膜组织TLR 4-MyD 88-NF-κB信号通路的异常激活有关。     

MyD88高表达腺病毒对小鼠自发性免疫性心肌炎的影响

目的通过对自发性免疫性心肌炎的Balb／c小鼠尾静脉注射MyD88高表达腺病毒来观测髓样分化因子88（Myeloid Differentiation Factor88,MyD88）对心肌炎症的影响。方法将所购得的90只小鼠随机分为MyD88组、心肌炎组和对照组,各30只。MyD88组小鼠皮下注射心肌肌球蛋白混合液,3d后给予尾静脉注射MyD88高表达腺病毒混合液0．1ml;心肌炎组在相同部位注射等体积的心肌肌球蛋白混合液,3d后注射与实验组同剂量的PBS溶液;对照组仅皮下注射0．2ml的PBS。21d后处死动物并制作切片,观测炎症浸润程度,并取眼球血测心肌坏死标志物cTnI及IgG、IgM抗体。结果免疫后第21天,炎症评分心肌炎组显著高于对照组（2．39±1．23VS0．68±0．65,P〈0．05）,表明自发性免疫性心肌炎小鼠建模成功。MyD88组炎症评分显著升高（F=94．194,P〈0．01）,高于心肌炎组（3．56±1．34V82．39±1．23,P〈0．05）和对照组（3．56±1．34V80．68±0．65,P〈0．01）;MyD88组小鼠血清cTnI、IgG和IgM检测值也明显高于心肌炎组和对照组（P〈0．01,P〈0．05）。结论MyD88参与了自发性免疫性心肌炎的发生发展。     

内毒素诱导的葡萄膜炎中虹膜固有组织细胞上MyD88与TLR-4的共表达

目的观察小鼠内毒素诱导的葡萄膜炎(endotoxin-induced uveitis,EIU)模型中Toll样受体-4(Toll-like receptor-4,TLR-4)、髓样分化因子88(myeloid differentiation factor 88,MyD88)、CD163的共表达。方法 6～8周龄雄性C3H/HeN(野生型)小鼠25只,C3H/HeJ(TLR-4基因缺陷型)小鼠5只,分别腹腔注射霍乱弧菌内毒素细胞壁脂多糖(lipopolysaccharide,LPS)诱导急性前葡萄膜炎动物模型,处死小鼠后虹膜、睫状体铺片,用免疫荧光三标记的方法检测虹膜、睫状体组织内不同时间CD163、TLR-4、MyD88的表达,并对虹膜内CD163、TLR-4和MyD88阳性细胞进行计数分析。结果 C3H/HeN小鼠LPS注射后12h结膜囊内出现炎症反应,24～48h达到高峰,72h炎症逐渐消退,而C3H/HeJ小鼠LPS注射后没有发现炎症反应。在内毒素诱导的C3H/HeJ小鼠虹膜中未检测到CD163、TLR-4和MyD88阳性细胞。C3H/HeN小鼠腹腔注射LPS后在虹膜铺片内0h未见CD163、TLR-4与MyD88阳性表达,12h后可见阳性细胞(40.3±8.9、45.2±6.3、42.5±4.1),24h阳性细胞数(121.0±39.5、138.6±28.3、125.5±36.1)较12h明显增多,差异均有统计学意义(均为P<0.05);48h阳性细胞数(132.3±54.5、129.9±36.2、122.1±29.3)与24h相比,差异均无统计学意义(均为P>0.05);72h阳性细胞数(12.8±3.2、10.4±5.6、9.3±5.2)较48h减少,差异均有显著统计学意义(均为P<0.01)。结论小鼠EIU模型中,LPS激活了CD163标记的巨噬细胞膜表面的TLR-4,TLR-4与MyD88途径可能是EIU主要的信号传导途径。     

Toll-Like Receptor 4 Signaling Contributes to Paclitaxel-Induced Peripheral Neuropathy

This paper tests the contribution of the toll-like receptors, TLR4 in particular, in the initiation and maintenance of paclitaxel-related chemotherapy-induced peripheral neuropathy. TLR4 and its immediate downstream signaling molecules—myeloid differentiation primary response gene 88 (MyD88) and toll/interleukin 1 receptor domain–containing adapter-inducing interferon-β (TRIF)—were found to be increased in the dorsal root ganglion (DRG) using Western blot by day 7 of paclitaxel treatment. The behavioral phenotype, the increase of both TLR4 and MyD88, was blocked by cotreatment with the TLR4 antagonist lipopolysaccharide–Rhodobacter sphaeroides during chemotherapy. A similar, but less robust, behavioral effect was observed using intrathecal treatment of MyD88 homodimerization inhibitory peptide. DRG levels of TLR4 and MyD88 reduced over the next 2 weeks, whereas these levels remained increased in spinal cord through day 21 following chemotherapy. Immunohistochemical analysis revealed TLR4 expression in both calcitonin gene-related peptide–positive and isolectin B4–positive small DRG neurons. MyD88 was only found in calcitonin gene-related peptide–positive neurons, and TRIF was found in both calcitonin gene-related peptide–positive and isolectin B4–positive small DRG neurons as well as in medium- and large-size DRG neurons. In the spinal cord, TLR4 was only found colocalized to astrocytes but not with either microglia or neurons. Intrathecal treatment with the TLR4 antagonist lipopolysaccharide–R. sphaeroides transiently reversed preestablished chemotherapy-induced peripheral neuropathy mechanical hypersensitivity. These results strongly implicate TLR4 signaling in the DRG and the spinal cord in the induction and maintenance of paclitaxel-related chemotherapy-induced peripheral neuropathy.PerspectiveThe toll-like receptor TLR4 and MyD88 signaling pathway could be a new potential therapeutic target in paclitaxel-induced painful neuropathy.