4-1BB stimulation inhibits allergen-specific immunoglobulin E production and airway hyper-reactivity but partially suppresses bronchial eosinophilic inflammation in a mouse asthma model

BACKGROUND: 4-1 BB, a member of the tumour necrosis factor receptor superfamily, functions as a co-stimulatory molecule. Recently, stimulation of the 4-1 BB pathway was shown to suppress antigen-specific CD4(+) T cell and subsequent T cell-dependent humoral immune responses. OBJECTIVE: We examined the effect of agonistic anti-4-1 BB monoclonal antibody (mAb) treatment on allergic asthma, in which allergen-specific type 2 helper T cells (Th2) have been shown to play an important role. METHODS: BALB/c mice were systemically sensitized with intraperitoneal injections of ovalbumin (OVA) and alum on days 0 and 14, and then challenged with inhaled OVA on days 28, 29 and 30. In test groups, the agonistic anti-4-1 BB mAb was administered at the time of initial systemic sensitization with OVA. On day 31, mice were challenged with inhaled methacholine, and enhanced pause was measured as an index of airway hyper-responsiveness (AHR). Levels of OVA-specific IgE in serum, and levels of various cytokines in bronchoalveolar lavage (BAL) fluids were measured. The severity of airway inflammation was determined by differential cell counts in BAL fluids and histopathologic lung analysis. To evaluate local immunity, we cultured lymphocytes from draining perihilar lymph nodes and evaluated the proliferative response to OVA and the levels of IL-5 in the culture supernatant. In addition, the functional mechanism of 4-1 BB stimulation was evaluated in splenocytes obtained at day 7 after systemic OVA sensitization. RESULTS: We found that treatment with the anti-4-1 BB mAb significantly decreased AHR and the production of allergen-specific IgE. Bronchial inflammation, however, had only partially improved and the levels of IL-4 and IL-5 in BAL fluids showed only a small degree of reduction compared with the control Ig-treated mice. Thoracic lymphocytes from anti-4-1 BB-treated mice showed significant suppression of OVA-induced proliferation and IL-5 production. In anti-4-1 BB-treated mice, splenocytes exhibited poor proliferation and marked apoptosis 7 days after systemic OVA challenge. CONCLUSION: These results suggest that stimulation of the 4-1 BB pathway effectively suppresses some features of allergic asthma, including allergen-specific IgE production and AHR, through deletion of allergen-specific Th2 cells. However, we found that bronchial allergic inflammation was not strictly mediated by suppression of the Th2 immune response in this murine model of asthma. Despite these somewhat contradictory effects, intervention in the 4-1 BB pathway might provide a potential novel immunotherapeutic approach for treatment of allergic asthma.     

Haemorrhage-induced alterations in function and cytokine production of T cells and T cell subpopulations.

Haemorrhage produces alterations in macrophage, T and B cell function. In order to better define the mechanism for the effects of blood loss on immune response, we examined function of and cytokine production by purified T cells, CD4+ and CD8+ subpopulations after blood loss. Whereas T and CD4+ cells from control, unhaemorrhaged animals produced no alteration in proliferation when added to cultures of mitogen-stimulated splenocytes from normal mice, proliferation was decreased when T or CD4+ cells from haemorrhaged mice were included. The addition of CD8+ cells from haemorrhaged animals to mitogen-stimulated cultures reduced proliferation by approximately 50% more than that found when CD8+ cells from control, unhaemorrhaged animals were included. Supernatants of mitogen-stimulated splenocytes from haemorrhaged mice contained significantly less IL-2 and interferon-gamma (IFN-gamma) than did those from control, unhaemorrhaged mice. CD4+ populations from haemorrhaged mice produced significantly more IL-10, and significantly less IFN-gamma, than did CD4+ cells from control, unhaemorrhaged mice. There were no significant differences in IL-2, IL-4, IL-10 or IFN-gamma production by CD8+ cells from haemorrhaged or control mice. The present experiments demonstrate that haemorrhage affects both CD4+ and CD8+ T cell subsets. In particular, haemorrhage appeared to activate CD4+, Th2 cells, with concomitant suppression of the Th1 subpopulation. These results provide a mechanism which may contribute to the alterations in cytokine production previously described to occur following blood loss.     

UV inhibits allergic airways disease in mice by reducing effector CD4+ T cells

Background In human asthma, and experimental allergic airways disease in mice, antigen‐presenting cells and CD4⁺ effector cells at the airway mucosa orchestrate, and CD4⁺CD25⁺ regulatory T cells attenuate, allergen immunity. UV irradiation of skin before sensitization with ovalbumin (OVA) causes significantly reduced asthma‐like responses in respiratory tissues. Objective To determine whether UV‐induced changes in CD11c⁺ cells, CD4⁺CD25⁺ effector cells or CD4⁺CD25⁺ regulatory cells in the trachea and airway draining lymph nodes (ADLNs) were responsible for reduced allergic airways disease. Methods The phenotype and function of CD11c⁺ cells and CD4⁺CD25⁺ cells in the trachea and ADLNs of UV‐ and non‐irradiated, OVA‐sensitized mice was examined 24 h after a single exposure to aerosolized OVA. Results No changes in the function of CD11c⁺ cells from UV‐irradiated mice were observed. CD4⁺CD25⁺ cells from UV‐irradiated, OVA‐sensitized mice harvested 24 h after OVA aerosol proliferated less in response to OVA in vitro and were unable to suppress the proliferation of OVA‐sensitized responder cells. This result suggested reduced activation of effector T cells in the airway mucosa of UV‐irradiated, OVA‐sensitized mice. To exclude regulatory cells of any type, there was similar proliferation in vivo to aerosolized OVA by CFSE‐loaded, OVA‐TCR‐specific CD4⁺ cells adoptively transferred into UV‐ and non‐irradiated, OVA‐sensitized mice. In addition, there was no difference in the expression of regulatory T cell markers (Foxp3, IL‐10, TGF‐β mRNA). To examine effector T cells, ADLN cells from UV‐irradiated, OVA‐sensitized and ‐challenged mice were cultured with OVA. There was reduced expression of the early activation marker CD69 by CD4⁺CD25⁺ cells, and reduced proliferation in the absence of the regulatory cytokine, IL‐10. Conclusion Reduced allergic airways disease in UV‐irradiated mice is due to fewer effector CD4⁺CD25⁺ cells in the trachea and ADLNs, and not due to UV‐induced regulatory cells. Cite this as: J. P. McGlade, D. H. Strickland, M. J. M. Lambert, S. Gorman, J. A. Thomas, M. A. Judge, J. T. Burchell, G. R. Zosky and P. H. Hart, Clinical & Experimental Allergy, 2010 (40) 772–785.     

Complete inhibition of allergic airway inflammation and remodelling in quadruple IL-4/5/9/13−/− mice

BACKGROUND: T-helper type 2 (Th2)-derived cytokines such as IL-4, IL-5, IL-9 and IL-13 play an important role in the synthesis of IgE and in the promotion of allergic eosinophilic inflammation and airway wall remodelling. OBJECTIVE: We determined the importance of IL-13 alone, and of the four Th2 cytokines together, by studying mice in which either IL-13 alone or the Th2 cytokine cluster was genetically disrupted. METHODS: The knock-out mice and their BALB/c wild-type (wt) counterparts were sensitized and repeatedly exposed to ovalbumin (OVA) aerosol. RESULTS: Bronchial responsiveness measured as the concentration of acetylcholine aerosol needed to increase baseline lung resistance by 100% (PC100) was decreased in IL-13-/-, but increased in IL-4/5/9/13-/- mice. Chronic allergen exposure resulted in airway hyperresponsiveness (AHR) in wt mice but not in both genetically modified mice. After allergen exposure, eosinophil counts in bronchoalveolar lavage fluid and in airways mucosa, and goblet cell numbers were not increased in IL-4/5/9/13-/- mice, and were only attenuated in IL-13-/- mice. Airway smooth muscle (ASM) hyperplasia after allergen exposure was prevented in both IL-13-/- and IL-4/5/9/13-/- mice to an equal extent. Similarly, the rise in total or OVA-specific serum IgE levels was totally inhibited. CONCLUSION: IL-13 is mainly responsible for AHR, ASM hyperplasia and increases in IgE, while IL-4, -5 and -9 may contribute to goblet cell hyperplasia and eosinophilic inflammation induced by chronic allergen exposure in a murine model. Both redundancy or complementariness of Th2 cytokines can occur in vivo, according to specific aspects of the allergic response.     

Impaired proliferative capacity and abnormal cytokine profile of naive and memory CD4 T cells from HIV-seropositive patients.

Purified naive and memory CD4 T cells from healthy donors, HIV+ asymptomatic carriers and AIDS patients were examined for their proliferative activity and their pattern of cytokine secretion (IL-4, IL-6, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha)) upon stimulation with phytohaemagglutinin (PHA), phorbol myristate acetate (PMA) and cross-linked anti-CD3 MoAb, in the presence of recombinant IL-2 (rIL-2). We found a decrease in the proliferative capacity of naive CD4 T cells following stimulation with PHA and PMA, and a sharp decline in this response upon cross-linked anti-CD3 stimulation in both subsets, although it predominated in the naive subpopulation. In AIDS patients, less pronounced impairment of thymidine uptake by the naive subset was found upon PHA and cross-linked anti-CD3 MoAb stimulation. In addition, an altered secretion pattern of the different cytokines was observed, consisting of abnormal secretion of IL-6 by both naive and memory cells, an abnormal pattern of IFN-gamma secretion and frequent loss of detectable IL-4 production by HIV patients. These abnormalities were even more pronounced in AIDS patients than in the asymptomatic carriers. Overall, our results extend previous reports indicating functional impairment of memory CD4 subsets in HIV+ subjects by showing that this impairment involves naive CD4 T cells.     

The bronchial epithelium as a key regulator of airway inflammation and remodelling in asthma

While asthma is an inflammatory disorder of the airways involving mediator release from mast cells and eosinophils and orchestrated by T cells, inflammation alone is insufficient to explain the chronic nature of the disease and its progression. Evidence is presented that the epithelium is fundamentally disordered in chronic asthma manifest by increased fragility, and an altered phenotype to one that secretes mucus, mediators, cytokines, chemokines and growth factors. Epithelial injury is mediated by exogenous factors such as air pollutants, viruses and allergens as well as by endogenous factors including the release of proteolytic enzymes from mast cells (tryptase, chymase) and eosinophils (MMP-9). Following injury, the normal epithelium should respond with increased proliferation driven by ligands acting on epidermal growth factor (EGF) receptors or through transactivation of the receptor. The epithelial response to these stimuli in asthma appears to be impaired despite upregulation of CD44 capable of enhancing presentation of EGF ligands to epidermal growth factor receptors (EGFR). Because the epithelium is 'held' in this repair phenotype, it becomes a continuous source of proinflammatory products as well as growth factors that drive airway wall remodelling.     

Survival of mature T cells in the periphery is intrinsically dependent on GIMAP1 in mice

An effective immune system depends upon the survival of mature T cells in the periphery. Members of the GIMAP family of GTPases have been proposed to regulate this homeostasis, supported by the paucity of peripheral T cells in rodents deficient for either GIMAP1 or GIMAP5. It is unclear whether this lack of T cells is a consequence of an ontological defect, causing the thymus to generate and export T cells incapable of surviving in the periphery, or whether (alternatively or additionally) mature T cells intrinsically require GIMAP1 for survival. Using the ER^T2Cre⁺ transgene, we conditionally deleted Gimap1 in C57BL/6 mice and demonstrate that GIMAP1 is intrinsically required for the survival of mature T cells in the periphery. We show that, in contrast to GIMAP5, this requirement is independent of the T‐cells' activation status. We investigated the nature of the survival defect in GIMAP1‐deficient CD4⁺ T cells and show that the death occurring after GIMAP1 ablation is accompanied by mitochondrial depolarization and activation of the extrinsic apoptotic pathway. This study shows that GIMAP1 is critical for maintaining the peripheral T‐cell pool in mice and offers a potent target for the treatment of T‐cell‐mediated diseases.     

Attenuated Salmonella typhimurium reduces ovalbumin-induced airway inflammation and T-helper type 2 responses in mice

Cytokines produced by Th2 cells are responsible for the pathogenesis of asthma. Th1-biased immune responses caused by attenuated salmonella have the potential to relieve asthmatic symptoms. We evaluated whether oral administration of attenuated salmonella could modulate allergic responses in a chicken ovalbumin (OVA)-induced asthmatic murine model. Mice were fed with attenuated salmonella SL7207 one dose before and three doses during the induction of an allergic response. Lung histology, percentages of eosinophil in bronchoalveolar lavage fluid, serum levels of OVA-specific antibodies and cytokine production by OVA-activated splenocytes were evaluated in mice with or without the administration of SL7207. A significant reduction in pulmonary eosinophilic infiltration was observed in mice receiving attenuated salmonella. Lower levels of OVA-specific IgG1 but higher titres of OVA-IgG2a in serum were also detected in this group. Splenocytes from salmonella-fed mice produced lower levels of Th2 cytokines upon OVA stimulation. The administration of attenuated salmonella significantly suppressed immunopathological symptoms in OVA-sensitized mice. Inhibition of Th2 responses might explain the potential mechanisms. This study provides some evidence for the feasibility of attenuated salmonella as an effective vaccine for allergic diseases.     

CD4+ T cells from mice with intestinal immediate-type hypersensitivity induce airway hyperreactivity

BACKGROUND: A subset of food-allergic patients does not only respond clinically with symptoms in the gastro-intestinal tract but also with asthmatic reactions. OBJECTIVE: The aim of this study was to analyse whether CD4+ T cells from mice with intestinal immediate-hypersensitivity reactions to food allergen are involved in the development of experimental asthma. METHODS: BALB/c mice were intraperitoneally sensitized to ovalbumin (OVA), followed by repeated intra-gastric (i.g.) OVA challenges. Control animals were either sham-sensitized or sham-challenged with phosphate-buffered saline (PBS). Duodenum, jejunum, ileum and colon were histologically examined. CD4+ T cells from mesenteric lymph nodes were transferred from various donor groups into recipient mice that received either OVA or PBS aerosol challenges. Recipients were analysed by measurements of lung function using head-out body-plethysmography and examination of broncho-alveolar lavage and lung histology. RESULTS: The highest levels of OVA-specific IgE antibody levels were detected in OVA-sensitized and OVA-challenged mice. Throughout the lower intestinal tract, a marked infiltration with eosinophils was observed, and goblet cell numbers as well as goblet cell area were significantly increased. The villus/crypt ratio was decreased compared with controls. The transfer of CD4+ T cells from mesenteric lymph nodes of OVA-sensitized and OVA-challenged mice triggered airway hyperreactivity and eosinophilic airway inflammation in recipients aerosol challenged with OVA, but not with PBS. CONCLUSION: We conclude that CD4+ T cells from mesenteric lymph nodes of mice with allergen-induced immediate-type hypersensitivity reactions in the gut are able to transfer the phenotype of experimental asthma.     

IL-17 neutralization significantly ameliorates hepatic granulomatous inflammation and liver damage in Schistosoma japonicum infected mice

IL-17 is a signature cytokine of Th17 cells implicated in the induction and progression of chronic inflammatory diseases. Several studies in C57BL/6 mice, immunized with soluble schistosome egg Ags (SEA) in complete Freund's adjuvant (CFA), and subsequently infected with Schistosoma mansoni (S. mansoni) have shown that severe hepatic granulomatous inflammation is correlated with high levels of IL-17. Here, using a Schistosoma japonicum (S. japonicum) larvae infection model in C57BL/6 mice, we analyzed the dynamic expression of IL-17 in infected livers by RT-qPCR and ELISA. Our results showed that IL-17 expression was elevated during the course of infection. The temporal expression of IL-17 and cytokines/chemokines involved in the induction and effector function of Th17 cells was paralleled with hepatic granulomatous inflammation. Treatment of S. japonicum infected mice with IL-17-neutralizing mAb resulted in significant downmodulation of granulomatous inflammation and hepatocyte necrosis. The protection was associated with lower expression of proinflammatory cytokines/chemokines, such as IL-6, IL-1β, CXCL1, and CXCL2 and a reduced number of infiltrating neutrophils. Anti-IL-17 mAb significantly ameliorated hepatic granulomatous inflammation, partly through the downregulation of proinflammatory cytokines/chemokines and recruitment of neutrophils. Our data indicate a pathogenic role of Th17/IL-17 in hepatic immunopathology in S. japonicum infected mice.     

小鼠CD4＋ CD25＋免疫调节性T细胞体外扩增及功能检测的研究

目的 探讨小鼠CD4＋ CD25＋调节性T细胞（Tregs）的体外扩增方法及扩增后Tregs的免疫功能.方法 利用免疫磁珠法分离小鼠Tregs;采用anti-CD3mAb＋rIL-2和Allo-APC＋rIL-2两种方法进行体外扩增,通过TRANSWELL培养系统、细胞因子表达及CFSE染色标记等方法检测Tregs免疫抑制作用的机制.结果 体外分离的Tregs纯度为89.5％;活细胞率约为98％.Tregs扩增的倍数在两组各时间点差异无统计学意义.扩增后CD4＋ CD25＋T细胞、CD4＋T细胞和CD4＋ CD25-T细胞的每分钟计数（CPM）分别为1 470、12 700和14 300.混合淋巴细胞反应（MLR）中当CD4＋：CD25＋T细胞的比例为1∶1时,抑制率为79％,比例为8∶1时,抑制率为33％.CFSE标记后,进入分裂周期的CD4＋T细胞的百分比在未加入CD4＋ CD25＋T细胞组为83.7％,加入CD4＋ CD25＋T细胞组为31.7％,差异具有统计学意义（P=0.0006）.CD4＋ CD25＋T细胞对CD4＋T细胞的增殖抑制率在Transwell和Non-Transwell的培养系统中分别为＜5％和95％.Transwell培养组中IL-2含量高于Non-Transwell组,差异具有统计学意义[Transwell培养组为（158.33±2.08）pg/mL,Non-Transwell组为（23.00±2.00） pg/mL,P ＜0.0001].结论 采用免疫磁珠法分离小鼠Tregs可行,Tregs可有效扩增;Tregs的作用机制为抑制CD4＋T细胞的增殖及抑制CD4＋T细胞分泌IL-2;其抑制作用需要细胞-细胞间接触;体外扩增后的Tregs仍具有免疫特性,其体外免疫抑制作用增强.     

In vitro cytokine production and growth inhibition of lymphoblastoid cell lines by CD4+ T cells from Epstein-Barr virus (EBV) seropositive donors.

In vitro stimulation of peripheral blood lymphocytes (PBL) from healthy Epstein-Barr Virus (EBV) seropositive individuals with autologous lymphoblastoid cell lines (LCL) gives rise to CD4+ and CD8+ T cells both of which are cytotoxic for autologous lymphoblastoid cells. Activated EBV-specific CD4+ T cells are cytotoxic towards autologous LCL but, paradoxically, CD4+ T cells have also been shown to enhance tumour formation in SCID/Hu mice. Here, we show that despite being cytotoxic, CD4+ T-cell lines from different donors show considerable variation in their ability to inhibit the long-term growth of autologous LCLs in vitro. Following re-stimulation in vitro with PMA and ionomycin, CD4+ T cells produced IFNgamma, TNFalpha, TNFbeta, IL-2, IL-4, IL-10 and IL-13. TNFalpha, TNFbeta and IL-10 production were also detected in LCL. IL-6 was only detected in trace amounts in either cell type. The ratio of IFNgamma to IL-4 production varied between the CD4+ T-cell lines, indicating differences in the Th1/Th2 balance of the response. When CD4+ T cells were re-stimulated using autologous LCL as antigen-presenting cells, they produced more IL-4 and less IFNgamma or IL-13 when compared with cells re-stimulated by phorbol myristate acetate (PMA) and ionomycin. Using two colour cytokine staining, we showed that many individual CD4+ T cells produced IFNgamma along with either IL-4 or IL-13. Purified CD4+ T cells completely inhibited the outgrowth of autologous LCL in five out of nine cases, and partially inhibited outgrowth in the remaining four. There was no correlation between the pattern of CD4+ T-cell cytokine production and the capacity to inhibit outgrowth of autologous LCL. The killing of LCLs was contact-dependant and not mediated by soluble factors. We conclude that the ability of CD4+ T cells to inhibit autologous LCL growth is not directly related to T-helper cell cytokine production, but may depend on cytoxicity through surface ligands such as CD95L (FasL) and TNFalpha-related apoptosis-inducing ligand (TRAIL).     

Ozone inhalation induces exacerbation of eosinophilic airway inflammation and hyperresponsiveness in allergen-sensitized mice

Background:  Ozone (O₃) exposure evokes asthma exacerbations by mechanisms that are poorly understood. We used a murine model to characterize the effects of O₃ on allergic airway inflammation and hyperresponsiveness and to identify factors that might contribute to the O₃-induced exacerbation of asthma.
Methods:  BALB/c mice were sensitized and challenged with Aspergillus fumigatus ( Af ). A group of sensitized and challenged mice was exposed to 3.0 ppm of O₃ for 2 h and studied 12 h later (96 h after Af challenge). Naive mice and mice exposed to O₃ alone were used as controls. Bronchoalveolar lavage (BAL) cellular and cytokine content, lung function [enhanced pause (P_enh)], isometric force generation by tracheal rings and gene and protein expression of Fas and FasL were assessed. Apoptosis of eosinophils was quantified by FACS.
Results:  In sensitized mice allergen challenge induced a significant increase of P_enh and contractile force in tracheal rings that peaked 24 h after challenge and resolved by 96 h. O₃ inhalation induced an exacerbation of airway hyperresponsiveness accompanied by recurrence of neutrophils and enhancement of eosinophils 96 h after allergen challenge. The combination of allergen and O₃ exposure inhibited Fas and FasL gene and protein expression and eosinophil apoptosis and increased interleukin-5 (IL-5), granulocyte-macrophage-colony stimulating factor (GM-CSF) and G-CSF protein levels.
Conclusions:  O₃ affects airway responsiveness of allergen-primed airways indirectly by increasing viability of eosinophils and eosinophil-mediated pathological changes.     

Immunoregulatory CD4+ CD45R+ suppressor/inducer T lymphocyte subsets and impaired cell-mediated immunity in patients with Down''s syndrome.

The monoclonal antibodies 2H4 and 4B4 allow CD4+ and CD8+ T lymphocytes to be subdivided into CD45R+ and CDW29+ functional subpopulations. The CD4+ CD45R+ lymphocytes are designated as suppressor/inducer and CD4+ CDW29+ as helper/inducer subsets. Peripheral blood lymphocytes from 19 patients with Down's syndrome and 19 age- and sex-matched normal controls were analysed for the CD45R+ and CDW29+ subsets from the CD4+ and CD8+ T lymphocytes. The percentage of CD4+ CD45R+ cells (suppressor inducer) was markedly increased and of CD4+ CDW29+ cells (helper/inducer) decreased in all patients with Down's syndrome. In contract, the percentage of CD8+ CD45R+ and CD8+ CDW29+ subsets showed no major differences between patients with Down's syndrome and normal controls. Moreover, an alteration in the CD4+ and CD45R+ and CD4+ CDW29+ T cell subsets was accompanied by a markedly reduced proliferative response to phytohaemagglutinin and concanavalin A stimulation of the CD4+ T lymphocytes. Thus, a deficiency exists in patients with Down's syndrome in the CD4+ CDW29+ helper/inducer T cell subset which may contribute to their impaired cell-mediated immunity.