Human basophils and eosinophils are the direct target leukocytes of the novel IL-1 family member IL-33

In mice, interleukin-18 (IL-18) regulates Th1- or Th2-type immune responses depending on the cytokine environment and effector cells involved, and the ST2-ligand, IL-33, primarily promotes an allergic phenotype. Human basophils, major players in allergic inflammation, constitutively express IL-18 receptors, while ST2 surface expression is inducible by IL-3. Unexpectedly, freshly isolated basophils are strongly activated by IL-33, but, in contrast to mouse basophils, do not respond to IL-18. IL-33 promotes IL-4, IL-13 and IL-8 secretion in synergy with IL-3 and/or FcepsilonRI-activation, and enhances FcepsilonRI-induced mediator release. These effects are similar to that of IL-3, but the signaling pathways engaged are distinct because IL-33 strongly activates NF-kappaB and shows a preference for p38 MAP-kinase, while IL-3 acts through Jak/Stat and preferentially activates ERK. Eosinophils are the only other leukocyte-type directly activated by IL-33, as evidenced by screening of p38-activation in peripheral blood cells. Only upon CD3/CD28-ligation, IL-33 weakly enhances Th2 cytokine expression by in vivo polarized Th2 cells. This study on primary human cells demonstrates that basophils and eosinophils are the only direct target leukocytes for IL-33, suggesting that IL-33 promotes allergic inflammation and Th2 polarization mainly by the selective activation of these specialized cells of the innate immune system.     

Le basophile humain et la réponse immunitaire

Allergic inflammation is the result of complex immune mechanisms that depends on cytokines produced by Th2 lymphocytes, which gives these cells a pivotal role in the allergic reaction. When activated by allergen, basophils produce IL-4 and IL-13, cytokines key in the allergic inflammatory response. Antigen activation induces expression of these two cytokines by basophils of only about 5–20% of allergic patients; basophils represent 80% of the IL-4 producing cells. Ionomycine can induce the production of these cytokines by basophils from most individuals, regardless of their clinical status. IL-4 production by basophils peaks at 2 h, whereas IL-13 expression is delayed, suggesting that basophils may be involved both in initiation and amplification of the allergic response. Furthermore, the rapid increase in CD40L expression on peripheral blood basophils suggests that they may be involved in IgE production. The CC chemokines increase the production of IL-4 by basophils, and stimulation with a 40-fold lower concentration of antigen then results in an equivalent level of IL-4 production. Diesel exhaust particles induce early IL-4 production by the majority of basophils, regardless of the individual’s allergic status; this effect is dependent on the generation of reactive oxygen species. Taken as a whole, these data add weight to the conclusion that basophils are involved in the pathophysiology of allergic diseases. In addition to their critical role in allergic inflammation, basophils may also be involved in anti-infectious immunity through the nonspecific mechanisms involved in innate immunity     

Increased expression of CD86 and reduced production of IL-12 and IL-10 by monocyte-derived dendritic cells from allergic asthmatics and their effects on Th1- and Th2-type cytokine balance

BACKGROUND: In allergic asthma, allergen-specific T cells have a Th2-biased phenotype, and it is thought that dendritic cells (DCs) contribute to the induction of allergic immune responses. Therefore, we hypothesized that DCs from allergic asthmatics and healthy donors differ with regard to their preference to induce Th1 or Th2 immune responses. OBJECTIVES: To investigate differences in DC-expressed costimulatory molecules and DC-secreted cytokines between allergic asthmatics and healthy donors, and their influence on the Th1- and Th2-type cytokine balance. METHODS: Circulating monocytes from patients with allergic asthma and healthy donors were cultured with GM-CSF and IL-4, respectively, for 5 days and subsequently with lipopolysaccharide for 2 days to create mature DCs (mDCs). CD1a, CD83, CD40 and CD86 expression on mDCs was examined using a fluorescence-activated cell sorter. IL-12 and IL-10 secreted by mDCs were measured by ELISA. Na?ve cord blood T cells were primed by mDCs from two groups, and IL-4 and IFN-gamma production by polarized T-helper cells (Th) was measured by ELISA. RESULTS: (1) CD86 expression on mDCs from allergic asthmatics was higher than that from healthy donors. (2) IL-12, IL-12p40 and IL-10 production by mDCs from allergic asthmatics was significantly lower than that from healthy donors, respectively. (3) IL-4 production by Th cells primed by mDCs from allergic asthmatics was increased compared with that from healthy donors. CONCLUSIONS: mDCs from allergic asthmatics preferentially priming na?ve T cells towards Th2-cell development might be due to increased expression of CD86 and reduced production of IL-12 and IL-10.     

Roles of IL-18 in basophils and mast cells.

Basophils and mast cells are effecter cells in allergen/IgE-mediated immune responses. They induce type 1 immediate immune response in airway or other organ, resulting in bronchial asthma and other allergic diseases. However, they also play a critical role in host defense against infection with helminthes. Upon linkage of FcepsilonRI with a complex of allergen and IgE, basophils and mast cells release a large amount of Th2 cytokines and chemical mediators. Therefore these responses are "acquired allergic responses" and induce allergic diseases, such as bronchial asthma. However, basophils and mast cells derived from cultured bone marrow cells with IL-3 for 10 days express IL-18Ralpha chain and produce Th2 cytokines in response to the stimulation with IL-3 and IL-18 without FcepsilonRI cross-linkage. Furthermore, they produce Th2 cytokines upon stimulation with several TLR ligands, such as LPS. This finding may suggest the presence of allergen/IgE-independent allergic responses, which we would like to designate as "innate allergic response". However, in vivo treatment with IL-18 and IL-2 protects against gastrointestinal nematode infection by activating intestinal mucosal mast cells in STAT6-independent manner, suggesting the importance of innate allergic response against helminth infection. Here we discuss the functional role of IL-18-induced "innate allergic response" in disease and host defense.     

IgE-independent interleukin-4 expression and induction of a late phase of leukotriene C4 formation in human blood basophils

T-helper cells can differentiate into at least two subtypes secreting distinct profiles of cytokines, Th1 and Th2, regulating immunoprotection and different immunopathologies. Interleukin-4 (IL-4) is both the product and the inducer of Th2 cells, raising the question whether IL-4 can be produced in response to antigen-independent stimuli. Here we show that human basophils produce IL-4 on stimulation with IL-3 and C5a or C5adesarg in similar amounts as induced by IgE- receptor-cross-linking. C5a-induced IL-4 production requires the presence of IL-3, with little effect of the sequence of stimuli addition. No "Th1-cytokines" (interferon-gamma and IL-2) and even no "Th2-cytokines" (IL-3, IL-5, IL-10, and granulocyte-macrophage colony- stimulating factor) are produced by basophils in response to either IgE- dependent or IgE-independent activation. The generation of leukotriene C4 (LTC4) is regulated in a similar manner. However, C5a induces a rapid, transient burst of leukotriene formation only if added after IL- 3. Interestingly, upon prolonged culture, a late phase of continuous LTC4 production is observed, which also requires two signals (IL-3 and C5a), but rather depends on their continuous presence than on their sequence of action. These data describe an antigen-independent pathway of very restricted IL-4 expression. Thus, basophils must be considered as central immunoregulatory cells of the innate immune system. Furthermore, the results show that LTC4 can also be generated more continuously for many hours, a phenomenon that may be of particular importance in chornic allergic inflammation, such as asthma.     

The roles of IFN-γ versus IL-17 in pathogenic effects of human Th17 cells on synovial fibroblasts

Objectives

Th17 cells, while indispensable in host defense, may play pathogenic roles in many autoimmune diseases, including rheumatoid arthritis (RA). However, the mechanisms by which human Th17 cells drive autoimmunity have not been fully defined. We assessed the potential of the human Th17 CD4 T cell subset to induce expression of cell–cell interaction molecules and inflammatory mediators by fibroblast-like synoviocytes (FLS), and the roles of IFN-γ and IL-17 in these interactions.

Methods

Th1 or Th17 cells were induced from healthy adult donor CD4 T cells and were co-cultured with FLS for 48 h with/without neutralization of IFN-γ, IL-17A, or both. Alternatively, FLS were treated only with IFN-γ or IL-17 for 48 h. FLS expression of CD40, CD54, and MHC-II, as well as IL-6 and IL-8 secretion, were assessed by surface staining followed by flow cytometry and ELISA, respectively.

Results

Both Th1 and Th17 cells secreted IL-17 as well as IFN-γ, although IFN-γ production was much greater from Th1 cells. FLS expression of CD40, CD54, and MHC-II significantly increased upon co-culture with Th1 cells, while Th17 cells increased only the percentage of FLS that were CD54+. Both T cell subsets induced IL-6 and IL-8 secretion by RA FLS. Neutralization of IL-17A did not reduce FLS expression of CD40, MHC-II, or CD54, but did inhibit IL-6 and IL-8 secretion. Although IFN-γ was a weak inducer of IL-6 secretion and significantly inhibited IL-8 secretion from FLS when used as a single stimulus, neutralization of IFN-γ inhibited the secretion of both cytokines in Th17/FLS co-cultures with RA but not OA FLS.

Conclusion

FLS cell–cell interaction molecules and soluble inflammatory mediators are differentially regulated by IFN-γ and IL-17. The effects of IFN-γ may depend in part on the particular milieu of other co-existing cytokines and its potential to induce cell–cell interactions. The potential benefit of therapeutic neutralization of either IL-17 or IFN-γ could depend on the relative proportions of these cytokines in the synovial compartment of an RA patient.     

IL-3 induces a Pim1-dependent antiapoptotic pathway in primary human basophils

The contribution of basophils in allergic disease and other Th2-type immune responses depends on their persistence at sites of inflammation, but the ligands and molecular pathways supporting basophil survival are largely unknown. The comparison of rates of apoptosis and of the expression of antiapoptotic proteins in different human granulocyte types revealed that basophils have a considerably longer spontaneous life span than neutrophils and eosinophils consistent with high levels of constitutive Bcl-2 expression. Interleukin-3 (IL-3) is the only ligand that efficiently protects basophils from apoptosis as evidenced by screening a large number of stimuli. IL-3 up-regulates the expression of the antiapoptotic proteins cIAP2, Mcl-1, and Bcl-X(L) and induces a rapid and sustained de novo expression of the serine/threonine kinase Pim1 that closely correlates with cytokine-enhanced survival. Inhibitor studies and protein transduction of primary basophils using wild-type and kinase-dead Pim1-Tat fusion-proteins demonstrate the functional importance of Pim1 induction in the IL-3-enhanced survival. Our data further indicate that the antiapoptotic Pim1-mediated pathway operates independently of PI3-kinase but involves the activation of p38 MAPK. The induction of Pim1 leading to PI3-kinase-independent survival as described here for basophils may also be a relevant antiapoptotic mechanism in other terminally differentiated leukocyte types.     

类风湿关节炎患者外周血Th17细胞的检测及意义

目的 探讨Th17细胞在类风湿关节炎(RA)患者外周血中的水平及意义.方法 分离RA患者和健康者外周血单个核细胞(PBMC),免疫磁珠阴选CD4~+T细胞,用或不用非特异性刺激剂(A-CD3、A-CD28),然后加佛波酯/离子霉素(PMA/Ion),经固定,透膜处理进行细胞内染色,流式细胞术(FCM)检测CD4~+T细胞内白细胞介素(IL)-17~+/干扰素(IFN)-γ~+、IL-17~+/IL-6~+水平.分组:①健康对照组;②RA病情稳定组;③RA病情活动组.结果 免疫磁珠阴选CD4~+T细胞纯度>90%.RA病情活动组IL-17表达水平(1.54±0.41)显著高于RA病情稳定组(0.70±0.21,P<0.01),二者又显著高于健康对照组(0.42±0.12,P<0.01).用A-CD3、A-CD28、IL-23刺激后,CD4~+T细胞IL-17胞内表达水平较无刺激组显著增加(P<0.05).CD4~+T细胞IFN-γ表达水平呈现与IL-17表达相似的特点,而RA患者与健康对照组IL-6表达水平差异无统计学意义.RA患者IL-17胞内表达水平与IFN-γ、IL-6无显著相关.结论 RA患者外周血CD4~+T细胞中存在异常增高的Th17细胞,且其水平与病情活动相关,有望作为判断RA患者病情活动的指标之一.     

Interleukin-11 induces Th2 polarization of human CD4(+) T cells

Exploration of the immunomodulatory activities of the multifunctional cytokine interleukin-11 (IL-11) has prompted several therapeutic applications. The immunomodulatory effects of IL-11 on human antigen-presenting cells and on T cells were investigated. IL-11 inhibited IL-12 production by activated CD14(+) monocytes, but not by mature dendritic cells (DCs) stimulated via CD40 ligation. Moreover, IL-11 did not affect either DC maturation, as demonstrated by phenotypic analysis and evaluation of cytokine production, or DC generation from progenitor cells in the presence of specific growth factors. Molecular analysis demonstrated the expression of IL-11 receptor messenger RNA in highly purified CD14(+) monocytes, CD19(+) B cells, CD8(+), and CD4(+) T cells, and CD4(+)CD45RA(+) naive T lymphocytes. In keeping with this finding, IL-11 directly prevented Th1 polarization of highly purified CD4(+)CD45RA(+) naive T cells stimulated with anti-CD3/CD28 antibodies, as demonstrated by significant increases of IL-4 and IL-5, by significantly decreased interferon-gamma production and by flow cytometry intracellular staining of cytokines. Coincubation of naive T cells with DCs, the most potent stimulators of Th1 differentiation, did not revert IL-11-mediated Th2 polarization. Furthermore, parallel experiments demonstrated that the activity of IL-11 was comparable with that induced by IL-4, the most effective Th2-polarizing cytokine. Taken together, these findings show that IL-11 inhibits Th1 polarization by exerting a direct effect on human T lymphocytes and by reducing IL-12 production by macrophages. Conversely, IL-11 does not exert any activity on DCs. This suggests that IL-11 could have therapeutic potential for diseases where Th1 responses play a dominant pathogenic role.     

Induction of Th2 type immunity in a mouse system reveals a novel immunoregulatory role of basophils

While production of cytokines such as IL-12 by activated dendritic cells supports development of Th1 type immunity, a source of early IL-4 that is responsible for Th2 immunity is not well understood. We now show that coculture of basophils could promote a robust Th2 differentiation upon stimulation of naive CD4 T cells primarily via IL-4. Th2 promotion by basophils was also observed even when naive CD4 T cells were stimulated in a Th1-promoting condition or when fully differentiated Th1 phenotype effector CD4 T cells were restimulated. IL-4-deficient basophils failed to induce Th2 differentiation but suppressed Th1 differentiation. It was subsequently revealed that the IL-4-deficient basophils must engage cell-to-cell contact to exert the inhibitory effect on Th1 differentiation. Stimulation of naive CD4 T cells within an in vivo environment of increased basophil generation supported development of Th2 type immunity. Taken together, our results suggest that basophils may provide an important link for the development of Th2 immunity.     

IL-33 Promotes the Induction and Maintenance of Th2 Immune Responses by Enhancing the Function of OX40 Ligand

Background: In Th2 immune responses, TSLP is a key player by induction of OX40-ligand (OX40L) on dendritic cells (DCs), which is the trigger to induce Th2 cell-mediated allergic cascade. Thus, TSLP-DC-OX40L axis might be the principal pathway in the inflammatory cascades in atopic dermatitis and asthma. IL-33, which is produced by epithelial cells, has been implicated in the Th2 immune responses and pathogenesis of the allergic disorders. However, the role of IL-33 in the Th2-polarizing TSLP-DC-OX40L axis still remains largely elusive. We focused on the ability of IL-33 to promote OX40L-mediated Th2 responses.Methods: Purified human naïve or memory CD4 + T cells were stimulated with recombinant OX40L or TSLP- treated DCs (TSLP-DCs) in the presence of IL-33, and the cytokine production by the primed T cells was examined. We also performed immunohistochemical analyses for the expression of IL-33 in specimens of lymph node and skin from the patients with atopic dermatitis.Results: IL-33 remarkably enhanced TSLP-DCs-driven or OX40L-driven Th2 responses from naïve T cells and the Th2 functional attributes of CRTH2 + CD4 + Th2 memory cells by the increased production of IL-5, IL-9, and IL-13. In addition, IL-33 was expressed in the nuclei of epithelial cells in not only skin lesion but also lymph nodes of the patient with atopic dermatitis, suggesting a specialized role in adaptive T cell-priming phase.Conclusions: IL-33 works as a positive regulator of TSLP-DC-OX40L axis that initiates and maintains the Th2 cell-mediated inflammatory responses, and therefore, it would be a new therapeutic target for the treatment of allergic disorders.     

Analysis of Th1 and Th2 cytokines expressing CD4+ and CD8+ T cells in rheumatoid arthritis by flow cytometry

OBJECTIVE: A Th1/Th2 cytokine imbalance with a predominance of Th1 cytokines has been suggested to be of pathogenetic importance in rheumatoid arthritis (RA). To evaluate the role of Th1/Th2 cytokines in RA, we used intracellular cytokine flow cytometry to determine cytokine profiles of CD4+ and CD8+ T cells in 34 peripheral blood (PB) and 10 synovial fluid (SF) samples from patients with RA. Results were compared with 10 PB samples from healthy controls (HC) and 5 SF samples from patients with non-RA synovitis. METHODS: After stimulating cells with PMA and ionomycin or alternatively with anti-CD3/CD28 in the presence of brefeldin A, intracellular levels of Th1 [interleukin 2 (IL-2), interferon-gamma (IFN-gamma)] and Th2 cytokines (IL-4, IL-5, IL-10, IL-13) were determined for CD3+CD8- (i.e., CD4+ Th1 and Th2 cells) and CD3+CD8+ (i.e., CD8+ Tc1 and Tc2 cells) T cells. RESULTS: The percentages of CD4+ and CD8+ Th1 and Th2 cytokines producing T cells (PB) were similar in patients with RA and healthy controls (HC), with a clear predominance of Th1 cytokines expressing, T cells. With regard to T cell subsets, IFN-gamma-producing T cells were significantly more frequently detected in the CD8+ subset [CD8+: median 45.1% (RA; p < 0.001), 38.2% (HC; p = 0.009) vs CD4+: 10.8%(RA), 17.0% (HC)]. Conversely, IL-2 was found in a higher percentage of CD4+ T cells [CD4+: median 33.4% (RA), 17.9% (HC) vs CD8+: 23.6% (RA), 12.3% (HC)]. Patients not in disease remission tended to have more IFN-gamma-producing CD8+ and IL-2-producing CD4+ T cells than patients in remission [CD8+: median 45.9% (IFN-gamma) vs 23.0% (IFN-gamma); CD4+: median 34.1% (IL-2) vs 18.2% (IL-2)1. In all PB samples, the proportion of T cells producing the Th2 cytokines IL-4, IL-5, IL-10, and IL-13 did not exceed 2%. Cytokine profiles did not differ between patients receiving immunosuppressive treatment and patients treated only with nonsteroidal antiinflammatory drugs. In comparison to PB, RA SF analysis revealed a significant increase in the percentage of IFN-gamma-producing CD4+ (p < 0.001) and CD8+ T cells (p < 0.001). In addition, the percentage of IL-10-producing CD4+ (p < 0.001) as well as CD8+ T cells (p = 0.001) was significantly elevated in SF. However, production of the other Th2 cytokines (IL-4, IL-5, IL-13) was similar in SF and PB. CONCLUSION: These data indicate similar cytokine profiles of T cells in PB of RA patients and healthy controls, with a strong predominance of Th1 cytokines producing T cells in the CD4+ and CD8+ T cell subset of both groups. PB cytokine profiles did not significantly differ in patients with active and non-active disease or between patients receiving and those not receiving immunosuppressive medication. In SF, the proportion of Th1 and Tcl cells was significantly elevated compared to PB, emphasizing the local importance of these cells for inflammation. CD8+ T cells (Tc1 cells) mainly contributed to the production of IFN-gamma, indicating an underestimated role of this cell subset for local cytokine production. The upregulation of IL-10-producing Th2 and Tc2 cells in SF may reflect an insufficient effort to down-regulate chronic inflammation in the joint. Modifying this cytokine imbalance in the joints may be a promising therapeutic approach in RA.     

La famille des IL-17 et la réponse allergique

Among the six members of the IL-17 family, three are clearly implicated in the regulation of the allergic response: IL-17A (also called IL-17), IL-17E (or IL-25) and IL-17F. IL-17A expresses strong homology with IL-17F and shares the same receptor. IL-17A is produced by various cells, mainly Th17 and iNKT17. IL-17A is a potent pro-inflammatory cytokine that induces the production of numerous other cytokines and chemokines and controls the recruitment and activation of neutrophils. However, in an experimental allergic asthma mouse model, IL-17A can induce either harmful or beneficial effect depending on the status of the allergic response. IL-17E, which is produced mainly by basophils and eosinophils in humans, acts mainly on Th2 cell differentiation either by polarizing naive CD4+ cells towards the Th2 pathway in an IL-4- dependent fashion, or by amplifying expansion and activation of memory Th2 cells in an IL-4-independent manner.     

Antibodies and IL-3 support helminth-induced basophil expansion

Basophils are powerful mediators of Th2 immunity and are present in increased numbers during allergic inflammation and helminth infection. Despite their ability to potentiate Th2 immunity the mechanisms regulating basophil development remain largely unknown. We have found a unique role for isotype-switched antibodies in promoting helminth-induced basophil production following infection of mice with Heligmosomoides polygyrus bakeri or Nippostrongylus brasiliensis. H. polygyrus bakeri-induced basophil expansion was found to occur within the bone marrow, and to a lesser extent the spleen, and was IL-3 dependent. IL-3 was largely produced by CD4(+)CD49b(+)NK1.1(-) effector T cells at these sites, and required the IL-4Rα chain. However, antibody-deficient mice exhibited defective basophil mobilization despite intact T-cell IL-3 production, and supplementation of mice with immune serum could promote basophilia independently of required IL-4Rα signaling. Helminth-induced eosinophilia was not affected by the deficiency in isotype-switched antibodies, suggesting a direct effect on basophils rather than through priming of Th2 responses. Although normal type 2 immunity occurred in the basopenic mice following primary infection with H. polygyrus bakeri, parasite rejection following challenge infection was impaired. These data reveal a role for isotype-switched antibodies in promoting basophil expansion and effector function following helminth infection.     

Reduced expression of the regulatory CD4+ T cell subset is related to Th1/Th2 balance and disease severity in rheumatoid arthritis

OBJECTIVE: To elucidate the involvement of the regulatory CD4+ T cells that produce high levels of interleukin-10 (IL-10) and low levels of IL-4 and IL-2 in the pathogenesis of rheumatoid arthritis (RA), we investigated whether the frequency of this type of CD4+ T cell subset in peripheral blood lymphocytes (PBL) or synovial lymphocyte infiltrates of patients with RA correlated with disease severity and histologic features in rheumatoid synovium. METHODS: PBL and synovial lymphocyte infiltrates were isolated from peripheral blood samples and synovial tissues obtained from 25 patients with RA. Control specimens were obtained from 18 patients with osteoarthritis (OA) and 10 patients with traumatic injuries of the knee joint. CD4+ T cell subsets were categorized as Th1 (production of interferon-gamma [IFNgamma], but not IL-4), Th2 (production of IL-4, but not IFNgamma), or CD4+ T cell subsets producing IL-10, IL-2, or IL-4. The percentages of these T helper subsets among PBL and among synovial infiltrating lymphocytes were determined by an intracellular staining assay with flow cytometric analysis. RESULTS: The level of expression of CD4+ T cells producing IL-10 but not IL-2 and IL-4 in the peripheral blood and synovial tissue was significantly lower in RA patients than in OA patients and trauma patients. In RA patients, the frequency of this type of CD4+ T cell subset among synovial infiltrating CD4+ T cells was inversely correlated with the frequency of Th1 cells and the Th1/Th2 balance in synovial lymphocytes, serum C-reactive protein value, disease activity score, and the degree of synovial lining hyperplasia and lymphocyte infiltration in rheumatoid synovium. There was a reciprocal relationship between the frequency of Thl cells and CD4+ T cells producing IL-10 but not IL-2 and IL-4 in the peripheral blood of RA patients. CONCLUSION: In RA, reduced expression of the CD4+ T cell subset producing IL-10 but not IL-2 and IL-4 may be responsible for the dominance of Th1 over Th2 cells at sites of inflamed synovium and in the peripheral blood. Decreases in this type of CD4+ T cell subset may induce the down-regulation of T cell tolerance and exacerbate the inflammatory process in RA.     

过敏性哮喘患者树突细胞表型及分泌细胞因子的研究

目的观察过敏性哮喘患者树突细胞(DC)表达表面分子(CD1a、CD83、CD40、CD86)和分泌细胞因子(IL12和IL10)的情况,及对原始T细胞分化的影响。方法分别取过敏性哮喘患者(9例)和健康对照者(14例)外周血培养成熟DC。另取无哮喘家族史的新生儿脐血分离得到原始T细胞。将2组DC和原始T细胞共同培养。流式细胞仪测DC表面协同刺激分子CD1a、CD83、CD40、CD86的表达。ELISA测DC分泌的IL12、IL10及T细胞分泌的IFNγ、IL4的含量。结果哮喘组DC表达CD86分子比对照组显著升高(P<001)。哮喘组DC分泌IL12、IL12p40和IL10较对照组显著减少(P<001,P<005)。哮喘组T细胞释放IFNγ较对照组减少(P<005),释放IL4较对照组显著增多(P<001)。哮喘组IL12与IFNγ呈正相关(r=0758,P<005),与IL4呈负相关(r=-0756,P<005);IL10与IL4呈负相关(r=-0685,P<005);IL12与IL10呈正相关(r=0926,P<001)。结论过敏性哮喘患者DC存在缺陷,使原始T细胞向Th2优势分化,IL4等的释放增加,且不能有效地形成T细胞耐受,共同导致过敏性哮喘的发生。     

Polynuclear basophils, the key to allergic reactions. Modulations by chemokines

Both IgE synthesis and inflammatory cell recruitment are recognized to be major components of the allergic response, leading to bronchial inflammation. Typically, T cells are considered to be the key stone of the allergic reaction after acquisition of their TH2 phenotype, responsible for IL-4, -5, -10 -13 production. Basophil is also capable to produce IL-4 and IL-13 following non-specific or antigen activations, and chemokines induce basophil chemotaxis and inflammatory mediator release. However, in context of allergy, the contribution of basophil to cytokine production remains unclear, and the role of chemokine on it is not known. To address this issue, leucocytes from healthy and allergic asthmatic patients were incubated in presence of ionomycine or Ag extracts, with or without chemokine, then fixed, permeabilized, stained using antibodies anti-IgE, anti-CD3, anti-cytokine, and analyzed by flow cytometry. After ionomycin activation, a large majority of basophils from both control and allergic asthmatic subjects express IL-4 and IL-13. Specific antigen induce cytokine expression by 5-20% of basophils from the asthmatic group only, and basophils represent 80% of IL-4 producing cells (p < 0.01). Basophil IL-4 expression peaks at 2 h (p < 0.01), whereas IL-13 expression is more delayed, suggesting that basophil may be involved in initiation, amplification and maintenance of allergic response. Since CD40 ligand is early up-regulated on peripheral blood basophils (p < 0.05), it may be critical in the initial IgE production. CC chemokines (eotaxin, eotaxin-2, RANTES, and MCP-2, 3, 4) enhance the frequency of IL-4 producing basophils (p < 0.01), following Ag activation, and eotaxin lowers the Ag concentration responsible for IL-4 production by 40 fold (p < 0.01). These data demonstrate that after antigen activation, basophils are the predominant peripheral blood cells expressing IL-4 and IL-13, and add weight to the conclusions that basophils are envolved in the regulation of allergic diseases. Finally, our results describe a novel role for CC chemokine: the potentialisation of IL-4 expression, suggesting potential inovative approaches to treat allergic asthma.     

Human Th2 cells selectively express the orexigenic peptide, pro-melanin-concentrating hormone

Th1 and Th2 cells represent the two main functional subsets of CD4(+) T helper cell, and are defined by their cytokine expression. Human Th1 cells express IFNgamma, whilst Th2 cells express IL-4, IL-5, and IL-13. Th1 and Th2 cells have distinct immunological functions, and can drive different immunopathologies. Here, we show that in vitro-differentiated human Th2 cells highly selectively express the gene for pro-melanin-concentrating hormone (PMCH), using real-time RT-PCR, enzyme immunoassay, and Western blot analysis. PMCH encodes the prohormone, promelanin-concentrating hormone (PMCH), which is proteolytically processed to produce several peptides, including the orexigenic hormone melanin-concentrating hormone (MCH). PMCH expression by Th2 cells was activation responsive and increased throughout the 28-day differentiation in parallel with the expression of the Th2 cytokine genes. MCH immunoreactivity was detected in the differentiated Th2 but not Th1 cell culture supernatants after activation, and contained the entire PMCH protein, in addition to several smaller peptides. Human Th1 and Th2 cells were isolated by their expression of IFNgamma and CRTH2, respectively, and the ex vivo Th2 cells expressed PMCH upon activation, in contrast to the Th1 cells. Because Th2 cells are central to the pathogenesis of allergic diseases including asthma, expression of PMCH by activated Th2 cells in vivo may directly link allergic inflammation to energy homeostasis and may contribute to the association between asthma and obesity.