HMGB1通过TLR4促进心肌缺血损伤并调节脾脏CD4~+、CD8~+T细胞和Th17细胞比例

目的探讨高迁移率族蛋白B1(HMGB1)通过Toll样受体4 (TLR4)调控心肌缺血损伤及对脾脏组织CD4~+T细胞、CD8~+T细胞及Th17细胞亚群的影响。方法 C57BL/6野生型小鼠(WT)和TLR4基因敲除(TLR4-/-)小鼠各30只,随机分为对照组、异丙肾上腺素诱导心肌缺血(ISO)组和ISO联合重组HMGB1(r HMGB1)组。采用心脏超声检查小鼠心功能,应用HE染色和天狼星红染色观察心肌组织病理学变化;原位末端转移酶标记技术(TUNEL)检测心肌细胞凋亡指数,流式细胞术检测脾脏组织中CD4~+T细胞、CD8~+T细胞和Th17细胞亚群的比例。结果与对照组相比,ISO组小鼠诱发心脏功能损害、心肌组织坏死和纤维化、心肌细胞凋亡,脾脏组织中CD4~+T淋巴细胞比例、CD4~+/CD8~+T细胞比值和Th17细胞比例升高;与ISO组小鼠相比,ISO联合r HMGB1组心脏功能损害、心肌组织坏死和纤维化、心肌细胞凋亡状况均加重,脾脏组织中CD4~+T淋巴细胞比例、CD4~+/CD8~+T细胞比值和Th17细胞比例更高;与ISO联合r HMGB1组野生型小鼠相比,ISO联合r HMGB1组TLR4-/-小鼠心脏功能损害、心肌组织坏死和纤维化和心肌细胞凋亡减轻,脾脏组织CD4~+T淋巴细胞比例、CD4~+/CD8~+T细胞比值和Th17细胞比例显著降低。结论 HMGB1通过TLR4诱发心肌缺血时心肌组织损伤,并上调脾脏组织CD4~+T细胞比例、CD4~+/CD8~+T细胞比值和Th17细胞比例,从而可能促进心肌组织炎症损伤。     

Tmod1在动脉粥样硬化发生中的作用

<正>目的:研究单核巨噬细胞中的原肌球调节蛋白1(tropomodulin,Tmod1)在动脉粥样硬化发生中的作用。方法:检测Tmod1在高脂喂养Apo E-/-小鼠主动脉的表达及在斑块内的定位。分析野生型和Tmod1敲除小鼠(TOT/Tmod1-/-)中腹腔CD11b+F4/80+巨噬细胞、骨髓Gr1+CD11b+单核细胞和血液CD11b+单核细胞含量。将野生型和TOT/Tmod1-/-小鼠的骨髓移植到     

Bcl3基因敲除对小鼠脾脏免疫细胞组成及抗肿瘤能力的影响

目的观察Bcl3基因敲除对小鼠脾脏免疫细胞的组成及抗肿瘤能力的影响。方法使用CRISPR/Cas9基因编辑技术建立Bcl3基因敲除小鼠(Bcl3-/-), 血常规检验和流式细胞术检测Bcl3-/-小鼠的免疫细胞组成;建立B16F10黑色素瘤肺转移小鼠模型, 记录肺部肿瘤结节数和小鼠生存时间, 对比野生型(wild type, WT)小鼠和Bcl3-/-小鼠的抗肿瘤能力。结果 Bcl3-/-小鼠成功繁育成品系, 子代基因敲除纯合小鼠无胚胎致死现象, 且生长正常, 与WT小鼠相比外观、生长发育、繁育性能未见明显差异;主要脏器无明显异常, 但脾脏肿大且脾脏免疫细胞总数明显增加(P<0.05);血小板计数和中性粒细胞计数及百分比均显著低于WT小鼠;CD19+B细胞比例无明显改变, CD3+T细胞比例显著增加, 同时T细胞亚群(CD4+、CD8+、Treg)比例均呈明显上升趋势(P<0.05);固有免疫细胞中NK细胞(NK1.1+)和中性粒细胞(Gr1+)比例下降(P<0.05), DC(CD11b+)比例无明显变化;Bcl3-/-荷瘤小鼠的肺部可见大量由黑色素瘤细胞形成的肿瘤...     

重组高迁移率族蛋白1(rHMGB1)体外诱导小鼠骨髓细胞向髓源性抑制性细胞(MDSC)分化北大核心CSCD

目的探讨重组高迁移率族蛋白1(r HMGB1)对髓源性抑制性细胞(MDSC)的体外分化作用。方法分离BALB/c小鼠的骨髓细胞,分别使用r HMGB1、粒细胞-巨噬细胞集落刺激因子联合白细胞介素6(GM-CSF-IL-6)、GM-CSF、IL-6和r HMGB1三者联合(GM-CSF-IL-6-r HMGB1)进行体外刺激48 h,流式细胞术检测CD11b+Gr1+MDSC、CD11c+和F4/80+巨噬细胞的比例。用免疫磁珠体外分选出粒细胞源性MDSC(G-MDSC)和巨噬细胞源性MDSC(M-MDSC)分别用r HMGB1刺激48 h,流式细胞术检测各组细胞中CD11b+Gr1+MDSC、CD11c+细胞和F4/80+巨噬细胞的比例。结果与对照组相比,r HMGB1、GM-CSF-IL-6、GM-CSF-IL-6-HMGB1刺激48 h后,CD11b+Gr1+MDSC比例增加,CD11c+细胞和F4/80+巨噬细胞的比例减少;免疫磁珠体外分选出G-MDSC和M-MDSC,用r HMGB1蛋白刺激48 h,与对照组相比,r HMGB1刺激后,CD11b+Gr1+MDSC、CD11c+细胞和F4/80+巨噬细胞的比例无显著性差异。结论 r HMGB1体外可以诱导分化MDSC比例增加,GM-CSF、IL-6与r HMGB1联用可以增强诱导效果。     

重组高迁移率族蛋白1(rHMGB1)体外诱导小鼠骨髓细胞向髓源性抑制性细胞(MDSC)分化

目的探讨重组高迁移率族蛋白1(r HMGB1)对髓源性抑制性细胞(MDSC)的体外分化作用。方法分离BALB/c小鼠的骨髓细胞,分别使用r HMGB1、粒细胞-巨噬细胞集落刺激因子联合白细胞介素6(GM-CSF-IL-6)、GM-CSF、IL-6和r HMGB1三者联合(GM-CSF-IL-6-r HMGB1)进行体外刺激48 h,流式细胞术检测CD11b+Gr1+MDSC、CD11c+和F4/80+巨噬细胞的比例。用免疫磁珠体外分选出粒细胞源性MDSC(G-MDSC)和巨噬细胞源性MDSC(M-MDSC)分别用r HMGB1刺激48 h,流式细胞术检测各组细胞中CD11b+Gr1+MDSC、CD11c+细胞和F4/80+巨噬细胞的比例。结果与对照组相比,r HMGB1、GM-CSF-IL-6、GM-CSF-IL-6-HMGB1刺激48 h后,CD11b+Gr1+MDSC比例增加,CD11c+细胞和F4/80+巨噬细胞的比例减少;免疫磁珠体外分选出G-MDSC和M-MDSC,用r HMGB1蛋白刺激48 h,与对照组相比,r HMGB1刺激后,CD11b+Gr1+MDSC、CD11c+细胞和F4/80+巨噬细胞的比例无显著性差异。结论 r HMGB1体外可以诱导分化MDSC比例增加,GM-CSF、IL-6与r HMGB1联用可以增强诱导效果。     

FAT/CD36在高脂喂养小鼠脂肪组织炎症中的作用

目的:探讨脂肪酸转运酶/白细胞分化抗原36(fatty acid translocase/CD36,FAT/CD36)在高脂饮食诱导的小鼠脂肪组织炎症中的作用。方法:将6周龄雄性C57BL/6J小鼠分别随机分为普通饮食组和高脂饮食组,喂养14周后,ELISA测定血清游离脂肪酸(FFA)含量,应用荧光实时定量PCR和Western blotting检测脂肪组织中FAT/CD36及炎症/趋化因子(IL-1β、IL-6、TNF-α、MCP-1、MIP-1)mRNA和蛋白的表达,免疫组织化学染色检测脂肪组织巨噬细胞浸润,比较高脂喂养14周的野生型小鼠和CD36基因敲除小鼠的脂肪组织炎症反应情况。结果:与普通饮食组相比,高脂饮食能增强C57BL/6J小鼠脂肪组织的FAT/CD36及炎症/趋化因子的表达,促进巨噬细胞在脂肪组织的浸润。与高脂饮食喂养的野生型小鼠相比,CD36基因敲除小鼠的脂肪组织炎症因子、趋化因子表达明显降低,脂肪组织巨噬细胞浸润减少。结论:高脂饮食通过上调脂肪组织FAT/CD36的表达激活了脂肪组织炎症。     

通过TLR9途径活化巨噬细胞导致小鼠流产的机制研究

为研究低甲基化型CpG与TLR9相互作用激活巨噬细胞并诱发小鼠妊娠失败的机制,本研究模拟特异性配体CpG活化TLR9的过程,并比较CpG对NK1.1+CD3-细胞和CD11b+F4/80+细胞数量、TNF-α表达水平以及妊娠结局的影响。研究发现,在孕6.5d腹腔注射CpG可显著提高非肥胖型糖尿病(non-obese diabetic,NOD)小鼠胚胎吸收率。相反,相同剂量对野生型BALB/c小鼠则无此影响。胚胎吸收率的增高伴有CD11b+F4/80+巨噬细胞相对数量增多和血清TNF-α水平增高,但是NK细胞构成比无显著改变。采用F4/80中和抗体抑制CD11b+F4/80+巨噬细胞可显著降低血清TNF-α水平,并降低胚胎吸收率。这些证据表明,CpG通过激活TLR9,并提高蜕膜CD11b+F4/80+巨噬细胞相对数量、增强TNF-α表达,进而导致胚胎吸收率增高。     

敲除CD226通过调节小鼠脾脏和肠道免疫细胞比例缓解小鼠的慢性束缚应激引起的抑郁样行为

目的 探讨CD226在小鼠慢性束缚应激(CRS)诱导的抑郁样行为中发挥的免疫调控作用及其可能机制。方法 选取4～6周龄野生型(WT)雄性C57/BL6J和同品系CD226基因敲除(CD226KO)小鼠建立CRS模型，通过强迫游泳测试、蔗糖偏好测试等行为学检测方法对小鼠进行应激抑郁评分，利用流式细胞术分析脾脏、Peyer淋巴结及肠上皮内淋巴细胞亚群的差异。结果 与WT CRS组相比，CD226KO CRS组强迫游泳测试静止时间显著降低，蔗糖偏好率显著上升；脾脏CD4⁺T细胞和CD8⁺ T细胞之比显著降低；小肠上皮内淋巴细胞中T细胞受体αβ(TCRαβ)和TCRαβ CD8αβ细胞亚群比例显著升高。结论敲除CD226能够缓解小鼠CRS模型诱导的抑郁样行为，影响CRS状态下小鼠脾脏及肠道免疫细胞比例，改善小鼠应激状态下的整体免疫状态。     

miRNA-126 基因敲减小鼠脾脏中免疫细胞的组成变化

目的:观察miRNA-126基因敲减(Knock down,KD)小鼠脾脏中免疫细胞组成比例变化并探讨其意义。方法:Realtime PCR探针法检测miR-126KD小鼠脾脏中miR-126表达水平,计算脾脏总细胞数;HE染色观察脾脏组织的病理学变化;流式细胞术(FACS)分别检测脾脏中DCs细胞、巨噬细胞、γδT细胞、NKT细胞,CD3~+T细胞和其亚群以及CD19~+B细胞的比例并计算细胞绝对数;免疫印迹法(Western blot,WB)检测脾脏组织中磷酸化NF-κB和磷酸化Akt的表达水平。结果:与野生型(WT)小鼠相比,miR-126KD脾组织中miR-126表达水平明显降低(P0.05),细胞总数明显增加(P0.05),且发生明显病理学改变;固有免疫细胞中NK细胞的比例和细胞绝对数显著增加(P0.05),但巨噬细胞的比例显著降低(P0.05);适应性免疫细胞中CD3~+T细胞和CD4~+T细胞的比例和绝对细胞数都显著增加(P0.05),而CD19~+B细胞仅绝对数显著增加(P0.05);最后miRNA-126KD小鼠脾脏组织的磷酸化NF-κB和磷酸化Akt水平明显增加(P0.05)。结论:miRNA-126敲减小鼠脾脏中各免疫细胞亚群的组成发生明显改变,可能与NF-κB和Akt信号通路传递变化有关,为后续探讨miR-126在机体免疫应答中的作用提供了前期实验基础。     

高脂饲养C57BL/6J小鼠肾周脂肪组织炎性反应的评估

目的评估高脂饲养C57BL/6J小鼠肾周脂肪组织炎性反应。方法将小鼠随机分为对照组(control组,n=6)和高脂饲养组(HFD组,n=6)。用RT-qPCR检测肾周脂肪组织中TNF-α、CD11c、IL-1β、IL-10、TGF-β1、CD206等mRNA的表达;免疫组织化学法检测肾周脂肪组织及肾实质F4/80、CD68、LCA的水平。结果与对照组比较,HFD组小鼠肾周脂肪组织TNF-α、IL-1β等mRNA相对含量升高(P0.05);HFD组的肾周脂肪巨噬细胞标志物F4/80,CD68及炎细胞广谱标志物LCA的表达均呈高表达(P0.05)。结论高脂饲养的C57BL/6J小鼠肾周脂肪组织确实存在明显的炎性反应。     

Peritoneal macrophage from male and female SJL mice differ in IL-10 expression and macrophage maturation

Injection of proteins and particulate antigens into the peritoneal cavity of male SJL mice preferentially activates T cells secreting Th2 cytokines. Identical immunizations of females activate T cells secreting Th1 cytokines. CD11b(+)F4/80(hi) LPM and CD11b(+)F4/80(lo) SPM populations were compared between naive males and females to define their role in supporting differential Th1 versus Th2 T cell activation. No sex-dependent differences in the expression of MHC class II, costimulatory molecules, and MR were detected. Immunization induced influx of CD11b(lo)F4/80(lo) cells in both sexes. CD11b(lo)F4/80(lo) cells consist predominantly of Ly6C(hi) monocytes, which mature into a Ly6C(-) SPM subset. Following immunization, equivalent frequencies of LPM had taken up antigen. However, the CD11b(lo)F4/80(lo) population, which had taken up antigen, was decreased significantly in males compared with females. Similar to na?ve macrophages, antigen-positive cells in immunized males and females exhibited no phenotypic differences. However, fewer Ly6C(-)F4/80(+) cells were present in males compared with females, consistent with the reduced number of antigen-positive cells. Furthermore, CD11b(lo)F4/80(lo) cells, which had taken up antigen in males, expressed increased IL-10 and limited IL-12 mRNA compared with the predominant IL-12 mRNA expression in female-derived, antigen-positive CD11b(lo)F4/80(lo) cells. IL-10 blockade increased the frequency of Ly6C(-)F4/80(+) cells in males to the frequency in females, suggesting that preferential activation of Th2 T cells in male SJL mice is associated with increased IL-10 expression and limited antigen presentation as a result of decreased macrophage maturation under the influence of IL-10.     

High mobility group box 1 promotes small intestinal damage induced by nonsteroidal anti-inflammatory drugs through Toll-like receptor 4

Release of high mobility group box 1 (HMGB1) from damaged cells, which is involved in many types of tissue injuries, activates inflammatory pathways by stimulating multiple receptors, including Toll-like receptor 2 (TLR2), TLR4, and receptor for advanced glycation end-products (RAGE). Our objective was to determine the role of HMGB1 in nonsteroidal anti-inflammatory drug (NSAID)-induced damage of the small intestine. Oral indomethacin (10 mg/kg) induced damage to the small intestine and was associated with increases in intestinal HMGB1 expression and serum HMGB1 levels. In wild-type mice, recombinant human HMGB1 aggravated indomethacin-induced small intestinal damage; enhanced the mRNA expression levels of tumor necrosis factor α (TNF-α), monocyte chemotactic protein 1, and KC; activated nuclear factor kappa B; and stimulated phosphorylation of the mitogen-activated protein kinases p38, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK). In contrast, blocking HMGB1 action with neutralizing antibodies prevented damage and inhibited both inflammatory cytokine overexpression and activation of these intracellular signaling pathways. TLR2-knockout (KO) and RAGE-KO mice exhibited high sensitivities to indomethacin-induced damage, similar to wild-type mice, whereas TLR4-KO mice exhibited less severe intestinal damage and lower levels of TNF-α mRNA expression. Exogenous HMGB1 aggravated the damage in TLR2- and RAGE-KO mice but did not affect the damage in TLR4-KO mice. Thus, our results suggest that HMGB1 promotes NSAID-induced small intestinal damage through TLR4-dependent signaling pathways.     

Myeloid marker expression on antiviral CD8+ T cells following an acute virus infection

CD11b, CD11c, and F4/80 are normally used to define dendritic cell and/or macrophage populations. In this study, the expression of all three markers was observed on CD8(+) T cells following infection of mice with several distinct viruses. Using lymphocytic choriomeningitis virus as a model virus, it was found that relatively more CD11b(+)CD8(+) and CD11c(+)CD8(+) T cells were present in the periphery than in primary lymphoid organs; in contrast, the F4/80(+)CD8(+) T cell population was more prevalent in the spleen. All three myeloid markers were detected on virus-specific CTL. The expression of CD11b and CD11c on CD8(+) T cells correlated with their level of CTL activity, whereas the F4/80(+)CD8(+) T cell population increased after the peak of the CTL response but did not have higher CTL activity. These data suggest that there is a differential induction of CD11b, CD11c, and F4/80 on virus-specific CD8(+) T cells following an acute virus infection.     

Dendritic cells recruited to the lung shortly after intranasal delivery of Mycobacterium bovis BCG drive the primary immune response towards a type 1 cytokine production

We showed in a previous study that the intranasal (i.n) delivery of bacille Calmette-Guérin (BCG) to BP2 mice (H-2q) inhibits eosinophilia and bronchial hyperreactivity in a mouse model of asthma. The present work has been performed to characterize the leucocyte lineages recruited to the lungs of mice after i.n. delivery of BCG and potentially involved in the polarization of T lymphocytes. The different antigen-presenting cells (APC) recruited to bronchoalveolar lavage (BAL) and to lung tissue of mice shortly after the delivery of BCG were analysed in parallel as well as their capacity to drive the immune response towards a T helper type 1 cytokine production. Alveolar macrophages (AM) from the BAL were CD11c+, F4/80+ and CD11b-, and in the lung tissue two major populations of potential APC were detected: one CD11c-, F4/80+, CD11b+ and I-Aq- was identified as interstitial macrophages (IM) and a second expressing CD11c+ and I-Aq+ antigens, negative for CD11b and F4/80 markers as leucocytic dendritic cells (DC). Freshly isolated DC up-regulated CD11b and CD40 antigens after overnight culture, but remained negative for CD8alpha antigen, suggesting a myeloid origin. Lung DC which produced high amount of interleukin (IL)-12 were potent inducers of naive CD4+ T lymphocyte priming, as assessed by interferon-gamma (IFN-gamma) production by these naive CD4+ T cells. Lung explants recovered long term after BCG delivery produced sustained levels of IFN-gamma. Our results suggest that AM and particularly DC by secreting IL-12 shortly after BCG delivery induce the long-term persistence of IFN-gamma-secreting T cells percolating in BCG-loaded lung tissue.     

Phenotypic and immunoregulatory characteristics of monocytic iris cells

The introduction of antigen into the anterior chamber of an eye induces the antigen-specific suppression of cell-mediated immunity and the antigen-induced production of immunoglobulin G2 antibodies. To define further the role of iris monocytic cells in the systemic suppression of cell-mediated immunity that follows the entry of foreign antigen into the anterior chamber, murine iris wholemounts or cell suspensions of iris cells were stained with fluorescent anti-F4/80 and/or anti-CD11c, anti-CD11b antibodies and examined by confocal microscopy or flow cytometry, respectively. Monocytic cells in iris cell suspensions were recovered from mice receiving an injection of trinitrophenylated bovine serum albumin (TNP-BSA) into an anterior chamber and Percoll-enriched iris cells separated into cells expressing F4/80 or CD11c were injected intravenously into TNP-BSA-immunized or naive recipients. The recipients were challenged to induce delayed-type hypersensitivity (DTH) or were provided with splenocytes or thymocytes that transfer the suppression of DTH. The homing of monocytic bone marrow cells to the iris was determined by the intravenous injection of bone marrow cells from green fluorescent protein (GFP)-transgenic donors into C57 mice, and the staining of recipient iris wholemounts with anti-F4/80 antibodies. Iris cells with a dendritic morphology expressing both F4/80 and/or CD11c and CD11b, some cells expressing only F4/80 or CD11c, were detected. The irides of irradiated GFP- mice that received intravenous GFP+ bone marrow cells contained GFP+ F4/80+ cells. F4/80+ and CD11c+ cells from the irides of donors that received intracameral TNP-BSA transferred the suppression of DTH when injected intravenously into TNP-BSA-immunized recipients, activated immunoregulatory thymocytes and activated antigen-specific splenic regulatory effector cells. These results support the hypothesis that iris monocytic cells may participate in the systemic induction of regulatory T cells.     

Toll-like receptor 4 is a regulator of monocyte and electroencephalographic responses to sleep loss

STUDY OBJECTIVES: Sleep loss triggers changes in inflammatory signaling pathways in the brain and periphery. The mechanisms that underlie these changes are ill-defined. The Toll-like receptor 4 (TLR4) activates inflammatory signaling cascades in response to endogenous and pathogen-associated ligands known to be elevated in association with sleep loss. TLR4 is therefore a possible mediator of some of the inflammation-related effects of sleep loss. Here we describe the baseline electroencephalographic sleep phenotype and the biochemical and electroencephalographic responses to sleep loss in TLR4-deficient mice. DESIGN, MEASUREMENTS AND RESULTS: TLR4-deficient mice and wild type controls were subjected to electroencephalographic and electromyographic recordings during spontaneous sleep/wake cycles and during and after sleep restriction sessions of 3, 6, and 24-h duration, during which sleep was disrupted by an automated sleep restriction system. Relative to wild type control mice, TLR4-deficient mice exhibited an increase in the duration of the primary daily waking bout occurring at dark onset in a light/dark cycle. The amount of time spent in non-rapid eye movement sleep by TLR4-deficient mice was reduced in proportion to increased wakefulness in the hours immediately after dark onset. Subsequent to sleep restriction, EEG measures of increased sleep drive were attenuated in TLR4-deficient mice relative to wild-type mice. TLR4 was enriched 10-fold in brain cells positive for the cell surface marker CD11b (cells of the monocyte lineage) relative to CD11b-negative cells in wild type mouse brains. To assess whether this population was affected selectively by TLR4 knockout, flow cytometry was used to count F4/80- and CD45-positive cells in the brains of sleep deprived and time of day control mice. While wild-type mice exhibited a significant reduction in the number of CD11b-positive cells in the brain after 24-h sleep restriction, TLR4-deficient mice did not. CONCLUSION: These data demonstrate that innate immune signaling pathways active in the monocyte lineage, including presumably microglia, detect and mediate in part the cerebral reaction to sleep loss.     

Autoimmune syndrome after neonatal induction of tolerance to alloantigens: analysis of the specificity and of the cellular and genetic origin of autoantibodies.

BALB/c mice neonatally injected with 10(8) semiallogeneic (C57BL/6 x BALB/c)F1 spleen cells become tolerant to the H-2b alloantigens, but also develop a wide range of autoimmune manifestations characteristic of systemic lupus erythematosus (SLE). Indeed, in these mice, the presence of a hypergammaglobulinaemia, autoantibodies--including anti-ssDNA, anti-platelet, thymocytotoxic and rheumatoid factor antibodies--circulating immune complexes, cryoglobulins as well as renal glomerular deposition of immunoglobulins have been observed. In this study, we have shown that the allogenic effect and B cell chimaerism which characterize these F1 cell-injected mice is associated with the expression of a large spectrum of autoantibodies, including anti-ssDNA and anti-cytoskeleton antibodies, and that these autoantibodies are not multispecific. We took advantage of the fact that, in this model, autoantibodies are exclusively produced by F1 donor B cells to inject newborn BALB/c mice with F1 Xid spleen cells lacking the CD5+ B cell subset. Injection of 2 x 10(8) F1 Xid spleen cells triggers the production of anti-ssDNA as well as anti-BrMRBC antibodies, and these mice developed tissue lesions. Finally, analysis of the VH gene family expressed by monoclonal autoantibodies derived from F1 cell-injected mice showed that they used the 2 largest families J558 and 7183. These results suggest that the allogenic effect and B cell chimerism which characterize the neonatal induction of tolerance to MHC alloantigens is associated with the selective triggering of autoreactive B cells producing monospecific IgG autoantibodies. They also imply that upon stimulation by persisting alloreactive CD4+ T cells, either CD5- B cells are able to produce autoantibodies or autoantibody-producing CD5+ B cells can differentiate from Xid spleen cells.     

Toll-like receptor 2 is required for inflammatory responses to Francisella tularensis LVS

Francisella tularensis, a gram-negative bacterium, is the etiologic agent of tularemia and has recently been classified as a category A bioterrorism agent. Infections with F. tularensis result in an inflammatory response that plays an important role in the pathogenesis of the disease; however, the cellular mechanisms mediating this response have not been completely elucidated. In the present study, we determined the role of Toll-like receptors (TLRs) in mediating inflammatory responses to F. tularensis LVS, and the role of NF-kappaB in regulating these responses. Stimulation of bone marrow-derived dendritic cells from C57BL/6 wild-type (wt) and TLR4-/- but not TLR2-/- mice, with live F. tularensis LVS elicited a dose-dependent increase in the production of tumor necrosis factor alpha. F. tularensis LVS also induced in a dose-dependent manner an up-regulation in the expression of the costimulatory molecules CD80 and CD86 and of CD40 and the major histocompatibility complex class II molecules on dendritic cells from wt and TLR4-/- but not TLR2-/- mice. TLR6, not TLR1, was shown to be involved in mediating the inflammatory response to F. tularensis LVS, indicating that the functional heterodimer is TLR2/TLR6. Stimulation of dendritic cells with F. tularensis resulted in the activation of NF-kappaB, which resulted in a differential effect on the production of pro- and anti-inflammatory cytokines. Taken together, our results demonstrate the role of TLR2/TLR6 in the host's inflammatory response to F. tularensis LVS in vitro and the regulatory function of NF-kappaB in modulating the inflammatory response.     

Three-colour fluorescence immunohistochemistry reveals the diversity of cells staining for macrophage markers in murine spleen and liver

Macrophages have traditionally been identified in murine tissues using a small range of markers, typically F4/80, CD68 and CD11b. However many studies have suggested that substantial heterogeneity exists in macrophage populations, and no single marker, nor even pair of markers, can necessarily identify all the populations. Further, many of the key monoclonal antibodies have been raised in the same species, making it difficult to combine them in histochemical studies. Here we have optimised a triple colour immunofluorescent staining protocol, utilising an anti-FITC technique, to allow antibodies to macrophage markers to be used simultaneously. We highlight the substantial heterogeneity of cells in both normal liver and spleen that stain for F4/80, CD68, CD11b, and CD11c. Using diet-induced steatohepatitis as a model of liver inflammation, we show that CD11b is expressed by newly migrating macrophage precursors, but is an unreliable marker for macrophage precursors when used alone because it is also expressed by migrating neutrophils. In healthy livers CD11c expression is a unique feature of a population of cells immediately surrounding the sinusoids. However, during hepatic inflammation CD11c can also be co-expressed by other cells, including both infiltrating cells and F4/80⁺ cells within the liver parenchyma. While no one marker alone is sufficient to account for all macrophage populations, we confirm that F4/80 marks the majority of the tissue-resident macrophages in both the liver and the spleen, although F4/80⁻ populations that are positive for CD68, CD11b, or CD11c also exist. Distinguishing between tissue macrophages and dendritic cells with these markers remains problematic.