microRNA-27a对树突状细胞表型及功能的影响

目的:研究microRNA-27a(miR-27a)对脂多糖(Lipopolysaccharide,LPS)刺激的小鼠树突状细胞(Dendritic cell,DC)的成熟和细胞因子分泌的影响。方法:小鼠骨髓来源的未成熟树突状细胞(immature dendritic cell,im DC)转染miR-27a的模拟物(miR-27a mimics)后,用LPS刺激24 h,采用流式细胞仪检测其表面共刺激分子CD80、CD86及MHCⅡ表达,ELISA方法检测其上清中的IL-12p70及IL-10蛋白水平,RT-PCR方法检测其细胞内IL-12p40及IL-10 mRNA水平,混合淋巴细胞反应(MLR)检测其刺激T细胞增殖能力。结果:与未处理的im DC比较,LPS刺激24 h后的DC表面的共刺激分子CD80、CD86及MHCⅡ表达均显著增高(均P0.001);LPS刺激24 h后,与对照组比较,转染miR-27a mimics细胞的共刺激分子CD80、CD86及MHCⅡ表达均显著降低(均P0.001),且显著抑制IL-12分泌(P0.01)、促进IL-10分泌(P0.05),并显著减弱LPS刺激的DC促CD4+T细胞增殖的能力(P0.01)。结论:miR-27a影响小鼠树突状细胞的成熟以及细胞因子的分泌。     

CD40配基化调节小鼠树突状细胞上B7-H3分子表达的研究

目的 探讨CD40配基化对小鼠骨髓来源树突状细胞上B7-H3分子表达的调节作用及其生物学意义。方法 采用GM-CSF和IL-4联合方案体外诱导小鼠髓系DC，并利用mCD40-CHO和TNF-α分别刺激凋亡肿瘤细胞负载的Dc制备成熟DC；采用间接免疫荧光标记法检测成熟Dc上B7-H3分子的表达；RT-PCR检测B7-H3 mRNA转录水平；混合淋巴细胞反应（MLR）和B7-H3单抗阻断实验分析CD40配基化的DC表面B7-H3分子在T细胞活化中的作用；^3H-TdR掺入试验检测DC对T淋巴细胞的促增殖效应；ELISA测定各组MLR反应和DC培养上清中IFN-γ分泌水平。结果 B7-H3分子在DC不同分化发育阶段均有表达，CD40配基化能显著上调凋亡肿瘤细胞负载的DC中B7-H3表达，TNF-α激发的DC弱表达（P〈0．05）；阻断CD40配基化的DC上B7-H3分子能抑制T细胞增殖和IFN-γ分泌；CD40配基化促进凋亡肿瘤细胞负载的DC分泌IFN-γ量也明显高于TNF-α组（P〈0．05）。结论 体外CD0配基化DC的B7-H3分子上调性表达有助于其刺激T细胞增殖和IFN-γ的产生。     

转化生长因子β1抑制树突状细胞的成熟及下调TLR4的表达

目的：研究转化生长因子β1（TGF-β1）对小鼠来源树突状细胞（DC）功能的影响。 方法: 在培养体系中同时应用GM-CSF和TGF-β1培养的TGF β-DC，用脂多糖（LPS）观察其对外源刺激的反应，流式细胞仪（FCM）检测细胞表型，应用BrdU ELISA法通过96 h混合淋巴细胞反应（MLR）检测其同种异基因刺激能力，ELISA法测IL-12 p70的分泌水平，分别用半定量RT-PCR法和FCM检测Toll-like受体4（TLR4）表达。 结果: TGF β-DC与常规培养的未成熟DC（imDC）相比，CD80、CD86、I-Ab、CD40表达更低。LPS对TGF β-DC的促成熟作用反应不明显，其表面共刺激分子升高的幅度不大，异基因的刺激能力提高不显著，且IL-12 p70的分泌下降。RT-PCR与FCM都显示TGF β-DC较imDC弱表达TLR4。 结论: TGF β1能抑制DC共刺激分子的表达，TGF β-DC能抵抗LPS的促成熟作用，并可能与其TLR4表达下降有关。     

约氏疟MIF对小鼠BM-DC细胞作用的探索

 摘要：目的 探索约氏疟原虫来源巨噬细胞迁移抑制因子（PyMIF）对小鼠髓系树突状细胞（BM-DC）表型和功能的影响。方法分离小鼠骨髓细胞并经GM-CSF和IL-4诱导培养得到BM-DC：经PyMIF刺激后,通过流式细胞术检测其TLR2、TLR4、CD80、CD86、CD40、MHCII分子表达,通过ELISA方法检测IL-12、IL-10分泌;经PyMIF刺激的BM-DC与CD4+T或CD8+T细胞共培养,同样方法检测T细胞CD69表达、IL-2分泌情况,并检测CD8+T细胞对靶细胞杀伤能力。结果PyMIF可以下调小鼠骨髓来源树突状细胞TLR-4的表达;但不能影响BM-DC细胞表面分子TLR2、CD80、CD86、CD40、MHCII的表达,也不改变BM-DC分泌IL-12、IL-10。PyMIF可通过BM-DC下调CD8+T的CD69表达,但不能通过BM-DC改变CD4+T细胞CD69表达、IL-2分泌,及CD8+T细胞IL-2分泌。结论PyMIF可能是通过下调BM-DC细胞TLR4表达来抑制免疫细胞对疟原虫的识别,使之逃逸机体的攻击而存活。     

4-1BB信号对小鼠树突状细胞表面TLR4表达的调节

目的 探讨4-1BB（CD137）激发型单克隆抗体2A对小鼠骨髓来源的树突状细胞（DC）表面TLR4表达的调节.方法 用不同剂量2A、LPS以及2A与LPS联合,或用LPS预刺激后再加入2A,以流式细胞术检测这些处理因素作用下DC表面TLR4表达情况.结果 LPS可下调DC TLR4的表达,下调作用可维持24 h,而2A可使DC TLR4的表达上调,上调作用可维持12 h,并可拮抗LPS对TLR4的下调作用.用LPS预处理DC后再加入2A,也可拮抗LPS的下调作用.结论 4-1BB信号可以上调DC表面TLR4的表达.     

血小板表达TLR4调节LPS刺激血小板释放细胞因子的作用

目的 证实人类血小板表面是否表达Toll样受体4(Toll like receptor 4,TLR4),探讨脂多糖(lipopolysaccharides,LPS)刺激血小板后TLR4表达变化及其对细胞因子白细胞介素-8(interlukine-8,IL-8)、β血小板球蛋白(β-thromboglobulin,β-TG)、可溶性CD40配体(soluble CD40 ligand,sCD40L)释放的凋节作用.方法 流式细胞技术测定不同浓度LPS刺激后血小板TLR4表达情况;ELISA法测定TLR4单克隆抗体封闭或不封闭LPS刺激的人血小板释放的细胞因子IL-8、β-TG、sCD40L的变化.结果 人血小板表达TLR4,LPS刺激后血小板对TLR4表达检出率降低(P<0.01),血小板对sCD40L、β-TG释放显著升高(P<0.001),但LPS在1～5μg/ml内不同浓度之间,sCD40L、β-TG浓度差异无统计学意义(P>0.05),LPS诱发血小板释放sCD40L、β-TG增加效应被TLR4单克隆抗体削弱.LPS刺激前后,反应体系中IL-8浓度无明显变化(P>0.05).结论 血小板TLR4与LPS相互作用诱发血小板大量释放sCD40L、β-TG,而血小板对IL-8的释放不依赖于TLR4-LPS途径.     

重组质粒pcDNA3.1-IL-15转染对小鼠骨髓DC上表面分子的表达及功能的影响

目的: 探讨重组质粒pcDNA3. 1 IL- 15对小鼠骨髓树突状细胞(DC)表面共刺激分子的表达及免疫功能的影响。方法: 构建真核表达质粒pcDNA3. 1 IL- 15, 以其转染小鼠骨髓DC。用流式细胞仪检测转染的DC表面CD40、CD80及CD86的表达, 并分析转染的DC刺激脾淋巴细胞中CD4 、CD8 T细胞亚群的变化。用MTT比色法检测转染的DC刺激T细胞增殖的作用。用ELISA法检测T细胞产生IFN- γ的水平。结果: pcDNA3. 1- IL- 15转染的DC表面CD40、CD80及CD86的表达均有不同程度的升高。重组质粒转染的DC可诱导小鼠脾淋巴细胞中CD4 、CD8 T细胞增殖, 但CD4 /CD8 T细胞的比值降低。结论: 重组质粒pcDNA3. 1 -IL- 15转染可提高DC表面共刺激分子的表达并增强其免疫功能。     

TLR2激动剂Pam3CK逆转IL-10转染小鼠髓样树突状细胞免疫功能的研究

目的:观察TLR2激活剂Pam3CK对IL-10转染小鼠髓样树突状细胞免疫功能影响。方法:转染IL-10至小鼠髓样树突状细胞(mDC),TLR2配体Pam3CK刺激48小时,利用流式细胞仪检测DC表面标志MHCⅡ、CD80、CD86及FasL等分子的表达;ELISA检测细胞产生IL-6、TNF-α。结果:IL-10抑制mDC表达CD80、CD86、MHCⅡ类分子,降低其分泌IL-6、TNF-α,促进其表达FasL,而TLR2激动剂刺激增加了IL-10转染DC表达MHC-Ⅱ类分子及CD80、CD86,促进其产生IL-6及TNF-α,抑制了FasL表达。结论:TLR2激动剂可逆转IL-10诱发的DC免疫应答低下。     

HBeAg对小鼠骨髓源性树突状细胞成熟的影响

目的 探讨HBe Ag对LPS诱导小鼠骨髓源性树突状细胞(DC)成熟的影响。方法 体外诱导C57BL/6小鼠骨髓细胞分化成未成熟树突状细胞,经CD11c磁珠分选纯化后将DCs随机分为空白对照组、LPS刺激组、HBe Ag+LPS刺激组。流式检测DC表型变化,混合淋巴反应(MLR)检测DC促T淋巴细胞增殖能力,酶联免疫法(ELISA)检测细胞上清液中IL-12的分泌水平,Western blot检测p38磷酸化水平,并设置SB203580组为阳性对照探讨细胞IL-12分泌的可能调节机制。结果 LPS刺激未成熟DC引起细胞表面MHC-Ⅱ、CD86表达升高,刺激同种异体淋巴细胞增殖能力增强,IL-12分泌量增高。HBe Ag可抑制LPS促进DC表面MHC-Ⅱ、CD86表达升高和促淋巴细胞增殖能力增强的作用。LPS刺激DC可引起p38磷酸化水平升高,并呈时间依赖性;HBe Ag或SB203580预处理细胞再予LPS刺激,磷酸化p38表达和IL-12分泌较单纯LPS刺激组明显下降。结论 HBe Ag对LPS引起的树突状细胞的成熟有一定的抑制作用,且HBe Ag可能通过抑制p38MAPK信号通路下调LPS诱导的树突状细胞IL-12的产生。     

细菌脂多糖诱导小鼠DC2.4细胞TLR7蛋白的表达

目的:探讨细菌脂多糖(LPS)对小鼠树突状细胞(DC)系DC2.4 TLR7蛋白表达的诱导作用.方法:用RPMIl640完全培养液培养DC2.4细胞,光学显微镜观察LPS刺激前后的细胞形态特征,RT-PCR和Western blot分别测定TLR7 mRNA和蛋白表达.结果:LPS刺激前后,细胞中均有TLR7 mRNA转录.LPS刺激前,细胞较小而透亮,树突较少,无,TLR7蛋白表达;LPS刺激后,细胞体积增大,树突增粗增多,刺激后12 h、24 h、48 h,TLR7蛋白均有表达,且在3个时间点的表达量基本一致.结论:LPS可诱导DC2.4中TLR7蛋白的表达.     

CD40-mediated up-regulation of Toll-like receptor 4-MD2 complex on the surface of murine dendritic cells

Toll-like receptors (TLRs) recognize pathogen-associated molecular patterns, which are non-self macromolecular components of pathogens that allow the innate-immune system to recognize infection. TLRs are expressed on macrophages and dendritic cells (DC). TLR stimulation or CD40 agonists can induce inflammatory cytokine secretion from macrophages and DC, and promote DC maturation. The regulation of TLR expression by inflammation has begun to be explored. Our studies have focused on the regulation of TLR4 surface expression on DC. TLR4, along with the adaptor molecule MD2, is involved in the recognition of lipopolysaccharide (LPS). CD40 stimulation via cross-linked anti-CD40 monoclonal antibody (mAb) up-regulates TLR4-MD2 surface expression on a DC cell line (DC2.4) and on ex vivo-cultured splenic DC. LPS treatment down-regulated surface TLR4-MD2 on DC2.4 cells, but if combined with anti-CD40 mAb, increased TLR4-MD2 expression was observed. The increased TLR4-MD2 surface expression by any treatment did not correlate with TLR4 mRNA levels. The functional consequence of increased TLR4-MD2 expression following LPS and anti-CD40 treatment was examined. Although CD40 prestimulation did slightly enhance interleukin-12p70 secretion after LPS restimulation, simultaneous anti-CD40 mAb and LPS treatment, which up-regulates TLR4-MD2 complex, does not restore DC responsiveness to subsequent LPS.     

Staphylococcal enterotoxins condition cells of the innate immune system for Toll-like receptor 4 stimulation

In this report we examined overlap between superantigen (SAg) and Toll-like receptor 4 (TLR4) stimulation of the innate immune system. Before in vivo stimulation we found that mouse splenic DCs expressed unexpectedly low levels of surface TLR4 compared to macrophages. In response to LPS, TLR4 gene expression in fractionated spleen cells was downregulated. By comparison, surface TLR4 staining with the Sa15-21 mAb showed little downregulation, and the anti-TLR4 MTS510 mAb showed decreased staining, suggesting that LPS was bound to TLR4 at the time points examined. Interestingly, SAg stimulation induced decreased TLR4 staining as measured by the MTS510 mAb, even though the TLR4 gene was not downregulated. Nevertheless, LPS potently induced DCs to produce TNF and IL-12, but SAg did not, even though they efficiently activated DCs. Notwithstanding, in vivo stimulation with staphylococcal enterotoxin SAg conditioned the innate immune system to hyper-respond to various pathogen-associated molecular patterns (PAMPs). Specifically, pre-priming with SAg enhanced LPS-mediated DC synthesis of TNF and IL-12. Thus, SAgs may exert their pathogenesis on the host by conditioning DCs, in a T cell activation dependent manner to potentiate responses to PAMPs.     

阻断CD40-CD40配体共刺激信号诱导的移植免疫耐受对树突状细胞的影响

目的:探讨阻断CD40-CD40配体共刺激信号诱导移植免疫耐受对树突状细胞功能的影响。方法:将抗CD40配体抗体(MR-1)应用于小鼠心脏移植受体以诱导移植免疫耐受,使用磁珠细胞提取装置从排斥及免疫耐受受体中提取树突状细胞。使用流式细胞仪测定树突状细胞表面分子CD40、CD80及CD86的表达。于体外以LPS再刺激树突状细胞,并使用ELISA法测定上清中的细胞因子IL-10和IL-12的水平。同时采用混合淋巴细胞反应(MLR)测定了树突状细胞的刺激性及免疫调节能力。结果:免疫耐受受体的树突状细胞表达低水平的共刺激分子CD40、CD80及CD86,同时分泌高水平的IL-10和低水平的IL-12。而且这些树突状细胞具有较弱的刺激性,并能抑制脾细胞的增殖。结论:阻断CD40-CD40配体共刺激信号可以产生免疫耐受状态,在这样的免疫耐受受体中诱导出未成熟表型的IL-10highIL-12low树突状细胞,这些细胞具有免疫调节活性。     

Maturation of murine bone marrow-derived dendritic cells with poly(I:C) produces altered TLR-9 expression and response to CpG DNA

Although poly(I:C) and LPS induced differential dendritic cell (DC) cytokine profiles and toll-like receptor (TLR) expression, all were capable of causing phenotypic and functional DC maturation. Both LPS and poly(I:C) downregulated TLR-4/MD-2 expression on DCs. Although poly(I:C) highly upregulated their cell surface TLR-9 expression, LPS upregulated the intracellular TLR-9 expression. LPS-treated DCs could not produce IL-12p70 in response to subsequent both LPS- and CpG DNA-stimulation. On the other hand, poly(I:C)-treated DCs retained to produce IL-12p70 by subsequent CpG DNA-stimulation, while subsequent LPS-stimulation did not induce IL-12p70 production. Chloroquine, inhibitor of endosomal maturation, completely inhibited cytokine production of LPS-treated DCs as well as unstimulated control in response to subsequent CpG DNA-stimulation, while it failed to delete the IL-12p40 and IL-10 production in poly(I:C)-treated DCs. These data suggest that poly(I:C) may induce a novel DC phenotype that preserves the capacity of cytokine production to subsequent CpG DNA-stimulation.     

TLR9 cooperates with TLR4 to increase IL-12 release by murine dendritic cells

Toll-like receptors (TLR) are expressed on the surface or intracellularly by dendritic cells (DC) and recognize specifically different pathogen-associated molecular patterns (PAMPs). Increasing evidence suggests that TLR expressed by DC can cooperate to synergize their functions. Here, we describe the cooperation of TLR9 and TLR4 triggering of murine bone marrow derived DC by CpG oligonucleotides and LPS, respectively. The simultaneous DC stimulation of LPS and CpG showed additive effects on the production of IL-12 but not on other cytokines, such as TNF, IL-6 or IL-10. CpG pretreatment before LPS induced five times more IL-12p40 and IL-12p70 production by DC, whereas LPS pretreatment before CpG showed no effect. The optimal time interval between CpG and LPS treatment was 4h and the synergistic effects were dependent on myeloid differentiation factor 88 (MyD88) but independent from the DNA backbone and did not mediate by nucleosome remodeling. The stimulatory effect could be further enhanced by addition of IFN-gamma but not anti-CD40 antibodies. These data show, that TLR4 and TLR9 can cooperate to increase selectively IL-12 production by DC.     

Differential role of mitogen-activated protein kinases in CD40-mediated IL-12 production by immature and mature dendritic cells

Using a murine spleen-derived dendritic cell (DC) line (BC1) CD40-mediated interleukin (IL)-12 production was analyzed and compared between immature and mature DC. BC1 cells, immature DC (iDC), were maturated by treatment with lipopolysaccharide (LPS) or tumor necrosis factor (TNF)-alpha. IL-12 production of LPS-treated DC (LPS/DC) was markedly enhanced by treatment with an anti-CD40 monoclonal antibody (mAb). Although the anti-CD40 mAb also enhanced IL-12 productions of iDC and TNF-alpha-treated DC (TNF/DC), these production levels were considerably low compared with that of LPS/DC. CD40-mediated IL-12-productions by iDC and TNF/DC were significantly enhanced by treatment with PD98059, a specific inhibitor of extracellular signal-related kinase (ERK) pathway. In contrast, PD98059 showed no significant effects on CD40-mediated IL-12-production by LPS/DC. These results demonstrated that ERK pathway was involved in negative regulation of the IL-12 productions by iDC and TNF/DC but not by LPS/DC. On the other hand, SB203580, a specific inhibitor of p38 mitogen activated protein kinase (MAPK) pathway, completely inhibited CD40-mediated IL-12-production by iDC, while not affecting those of TNF/DC and LPS/DC. Thus, p38 MAPK pathway appeared to positively regulate the IL-12 production in iDC but not in mature DC. It seems that roles of ERK and p38 MAPK for IL-12 production are developmentally changed in murine DC.     

Selective synergy in anti-inflammatory cytokine production upon cooperated signaling via TLR4 and TLR2 in murine conventional dendritic cells

Toll-like receptor (TLR) ligands, i.e. lipopolysaccharide (LPS), induce dendritic cell (DC) production of both inflammatory and anti-inflammatory cytokines including interleukin (IL)-12, tumor necrosis factor (TNF)-, and IL-10. The balance of inflammatory versus anti-inflammatory cytokines appears to be crucial to control immune homeostasis. In the present study, we investigated TLR-mediated regulation of inflammatory versus anti-inflammatory cytokine production using murine bone marrow derived conventional DCs. Standard LPS (sLPS) that contains lipoprotein, a TLR2 ligand, induced vigorous production of both IL-10 and IL-12 p40 by DCs. Highly purified LPS (ultra-pure LPS, upLPS) also induced vigorous production of IL-12 p40, but markedly low IL-10 production. Thus, signal deficiency through TLR2 appeared to result in marked reduction in DC production of IL-10 but not IL-12 p40 upon stimulation with upLPS. To examine this possibility, DCs were stimulated with Pam3CSK4, a synthetic ligand of TLR2, in addition to stimulation with upLPS. It was shown that Pam3CSK4 alone failed to induce IL-10 production. However, Pam3CSK4 synergistically enhanced upLPS-induced DC production of IL-10 but neither IL-12 p40 nor TNF-. Extracellular signal-regulated kinase (ERK)1/2, p38 mitogen-activated protein kinase (MAPK), and c-jun N-terminal kinase (JNK)1/2 in DCs were significantly activated by upLPS stimulation. The upLPS-induced activities of these MAPKs were considerably enhanced by additional stimulation with Pam3CSK4. Blocking either p38 MAPK or JNK1/2 pathway completely inhibited the synergistic enhancement of the IL-10 production by DCs upon upLPS and Pam3CSK4 stimulation. Thus, cooperated stimulation of these MAPKs via TLR4 and TLR2 appeared to induce selective synergy in anti-inflammatory cytokine production by murine conventional DCs.     

Plasmodium falciparum-free merozoites and infected RBCs distinctly affect soluble CD40 ligand-mediated maturation of immature monocyte-derived dendritic cells

Free plasmodium merozoites released from the parasitized hepatocytes and erythrocytes represent a transitory, extracellular stage in its mammalian host. In this study, we compared the effect of Plasmodium falciparum-free merozoites with infected RBCs (iRBCs) on the maturation of human monocyte-derived dendritic cells (DCs) in vitro. Phagocytosed-free merozoites prevented soluble CD40 ligand (sCD40L)-induced, phenotypic maturation of DCs and secretion of IL-12p70 but enhanced IL-10 production and primed, naive CD4+ cells to produce a high level of IL-10 compared with IFN-gamma. Free merozoites augmented sCD40L-induced ERK1/2 activation, and inhibition of ERK1/2 with its inhibitor PD98059 markedly abrogated IL-10 production and rescued IL-12 production. Therefore, the molecular mechanisms by which free merozoites antagonized sCD40L-induced DC maturation appeared to involve the activation of the ERK pathway. In contrast, phagocytosed iRBCs by itself induced DCs to semi-maturation, responded to CD40 signaling by maturing and secreting increased levels of TNF-alpha, IL-6, and also IL-12p70, and led to a pronounced, proinflammatory response by the allogenic CD4+ T cells. iRBCs regulate CD40-induced p38MAPK. Studies using inhibitors selective for p38MAPK (SB203580) showed that p38MAPK played an essential role in the maturation and function of DCs. Our results reveal the ability of free merozoites and iRBCs to distinctly alter the sCD40L-induced DC functioning by regulating the activation of the MAPK pathway that can inactivate or exacerbate immune responses to promote their survival and the development of parasite-specific pathologies.