Th17细胞及其与感染性疾病关系的研究进展

Th17细胞是一种新近发现的不同于Th1、Th2细胞的CD4+效应性T细胞亚群,其分化受到局部微环境中不同细胞因子的调节,如TGF-β、IL-6促进初始CD4+T细胞分化为Th17细胞,而IL-27等则是抑制Th17分化的重要因子.Th17细胞以分泌IL-17、IL-21、IL-22等致炎细胞因子为主要特征,在对抗机体...     

IL-12对BALB/c小鼠Th17细胞的分化的影响

目的: 观察细胞因子IL-12对Th17细胞分化的影响.方法: 小鼠脾淋巴细胞经抗CD3单克隆抗体(mAb)和不同浓度的重组小鼠IL-12刺激, 3 d后使用ELISA方法观察培养物上清液中IL-17的产生情况.并使用细胞内细胞因子染色的方法, 通过流式细胞术观察CD3 mAb和重组小鼠IL-12刺激对Th1和Th17细胞分化的影响.结果: Th17细胞不分泌IFN-γ、 IL-5、 IL-10等细胞因子, 不表达Foxp3, 是一个独立的细胞亚群.不同浓度的重组小鼠IL-12可以诱导抗CD3 mAb 的T细胞分泌IFN-γ, 并向Th1细胞方向分化.同时, IL-12可以抑制活化的T细胞分泌IL-17, 抑制T细胞向Th17细胞分化.结论: IL-12可以抑制Th17细胞的分化.     

IL-21在Th17细胞炎症反应中的作用

Th17细胞是新近发现的T淋巴细胞亚群.作为不同于Th1、Th2的细胞亚群,已经被证实在自身免疫病、感染、炎症等疾病中发挥重要作用.IL-21作为Th17细胞的自分泌调节因子,在Th17细胞功能的维持、抑制Th1、调节性T细胞(Treg)分化等方面发挥关键作用.Th17细胞能够自分泌产生IL-21,从而促进自身分化过程...     

Th17细胞及其相关因子与自身免疫平衡的作用进展

Th17细胞是新近发现的不同于Th1细胞和Th2细胞的新型CD4+T细胞亚群。Th17细胞的分化受转录因子RORγt、IL-23、TGF-β和IL-6等细胞因子的调控。Th17细胞的特性与其分泌的IL-17的生物学效应密切相关。Th17细胞参与了多种自身免疫性疾病的发生发展。     

Th17与自身免疫性疾病

Th17细胞是新近发现的一类新型的能够分泌白细胞介素17(interleukin 17,IL-17)的CD4+T细胞。在IL-6和TGF-β作用下,初始CD4+T细胞分化为Th17细胞。分化成熟的Th17细胞可以分泌IL-17,IL-17F和IL-22等多种细胞因子,其中IL-17和IL-17F是其主要效应分子。临床前和临床数据均表明:Th17细胞与一些自身免疫性疾病(如系统性红斑狼疮、类风湿性关节炎、多发性硬化、银屑病、炎症性肠病、自身免疫性甲状腺疾病)有关。     

Th17细胞分化的调节

Th17细胞是一群分泌IL-17的CD4+T细胞,它在分化发育及功能上不同于Th1细胞和Th2细胞。目前认为Th17细胞与自身免疫性疾病的发生发展密切相关,Th17细胞在病灶部位高表达,并与疾病的严重程度相一致。研究发现:CD4+CD25+Treg和Th17细胞的分化均需要TGF-β,并通过IL-6决定两者的分化比例,CD4+CD25+Treg和Th17细胞的动态平衡在机体免疫防御、免疫自稳中起着重要作用;RORγt是Th17细胞分化的关键转录因子,RORγt的表达依赖于IL-6和TGF-β;IL-23及其受体能上调Th17细胞的表达,而IL-12、IFN-γ、IL-4、T-bet抑制其表达。对Th17细胞的深入研究将有助于我们对自身免疫性疾病发病机制的深入了解。     

环孢素A对小鼠Th17细胞分化的影响

目的：观察在抗CD3单克隆抗体（mAb）＋rIL-23刺激的条件下，环孢素A（CsA）对Th17细胞分化的影响。方法：小鼠脾淋巴细胞分别使用抗CD3mAb、抗CD3mAb＋rIL-23及抗CD3mAb＋rIL-23＋不同浓度的CsA刺激后，用ELISA检测IL-17和IFN-7的水平，并用流式细胞仪在单个细胞水平上检测产生IL-17的T细胞亚群。结果：单独抗CD3mAb能诱导少量的IL-17产生，加入IL-23后呈剂量依赖的方式明显增加IL-17的产生。CsA对抗CD3mAb＋rIL-23诱导的Th17细胞分化呈剂量依赖性的抑制作用。CsA不仅抑制早期Th17的分化，当细胞激活48小时后，CsA对Th17细胞的分化仍有抑制作用。CsA除了抑制Th17细胞分化外，对IFN-7和IL-2的产生也有抑制作用。此外，T细胞亚群分析的结果表明IL-17主要由CD4＋T细胞产生，而CD8＋T细胞几乎不产生IL-17。结论：CsA可以抑制Th17细胞的分化，进一步阐明了CsA免疫抑制及抗炎作用的机制，为临床上应用CsA提供科学理论和实验依据。     

抗原特异性Th17细胞的分化与调节

目的: 探讨影响抗原特异性Th17细胞分化和调节的因素.方法: T细胞受体转基因小鼠(DO11.10)CD4 T细胞, 与同背景正常小鼠的脾细胞混合, 经OVA多肽刺激后, 在不同的Th17极化的培养条件下, 观察Th17细胞及细胞因子的产生. 结果: 单纯OVA抗原刺激主要诱导特异性Th1型反应, 在TGF-β和IL-6存在的条件下, 主要诱导Th17反应; 当加入IL-23之后, 促进了Th17细胞的分化.阻断了IFN-γ和IL-4之后, Th17细胞的百分率明显增加.LPS可以促进Th1型细胞因子的产生, 但对抗原特异性Th17细胞的分化没有明显的促进作用.结论: 抗原特异性Th17细胞是与Th1、 Th2相对独立的细胞亚群, TGF-β、 IL-6和 IL-23可诱导或促进Th17的分化, 而Th1和Th2细胞因子抑制其分化.     

Th17细胞及IL-17与系统性红斑狼疮

系统性红斑狼疮（SLE）是多种因素相互作用引起的自身免疫性疾病,其发病机制复杂。Th17细胞是最近发现的CD4^＋效应T细胞的新亚群。初始T细胞在TGF—B和IL-6的共同作用下分化发育成为Th17细胞,后者可以分泌IL-17、IL-21、IL-22等多种细胞因子。其中IL-17在多种自身免疫疾病（比如类风湿关节炎和Crohn’s病）中起关键作用,但在SLE中的作用尚不清晰。     

Th17细胞与自身免疫性疾病

Th17细胞是近年发现的不同于Th1细胞和Th2细胞的新型CD4^＋T细胞亚群。活化的Th17细胞可分泌IL—17、肿瘤坏死因子-α（TNF—α）、IL-6、粒-单核细胞集落刺激因子（GM—CSF）等多种促炎症因子,Th17细胞不适当的激活与多种自身免疫性疾病和过敏性疾病密切相关。在体内阻断Th17细胞的分化、扩增及其相关细胞因子可预防、延缓或阻止自身免疫性疾病的发生、发展。     

Phenotypic differences between Th1 and Th17 cells and negative regulation of Th1 cell differentiation by IL-17

Recent evidence from several groups indicates that IL-17-producing Th17 cells, rather than, as once was thought, IFN-gamma-producing Th1 cells, can represent the key effector cells in the induction/development of several autoimmune and allergic disorders. Although Th17 cells exhibit certain phenotypic and developmental differences from Th1 cells, the extent of the differences between these two T cell subsets is still not fully understood. We found that the expression profile of cell surface molecules on Th17 cells has more similarities to that of Th1 cells than Th2 cells. However, although certain Th1-lineage markers [i.e., IL-18 receptor alpha, CXCR3, and T cell Ig domain, mucin-like domain-3 (TIM-3)], but not Th2-lineage markers (i.e., T1/ST2, TIM-1, and TIM-2), were expressed on Th17 cells, the intensity of expression was different between Th17 and Th1 cells. Moreover, the expression of CTLA-1, ICOS, programmed death ligand 1, CD153, Fas, and TNF-related activation-induced cytokine was greater on Th17 cells than on Th1 cells. We found that IL-23 or IL-17 can suppress Th1 cell differentiation in the presence of exogenous IL-12 in vitro. We also confirmed that IL-12 or IFN-gamma can negatively regulate Th17 cell differentiation. However, these cytokines could not modulate such effects on T cell differentiation in the absence of APC.     

Transcription factors that regulate helper T cell differentiation]

Antigen-specific CD4(+) helper T cell (Th cell) is a major player for acquired-immunity. Th cell distribute in the peripheral tissues after educations and selections in the thymus. By stimulation from antigen presenting cell (APC), Th cell differentiate into at least three types of effector Th cells by the cytokine environments and the kinds of co-stimulatory molecules on APC. One is Th1 cell which produces IFN-gamma mainly, and another is Th2 cell which produces IL-4, 5 and 13 mainly, and finally recently defined Th17 cell which produces IL-17 mainly, and these cells are charged with the a role for "cellular", "hormoral" and "inflammatory" immunity respectively. IL-12, STAT4 and T-bet signals are important for Th1 differentiation, and IL-4, STAT6 andGATA3 signals are important for Th2 differentiation, and IL-1beta, TGF-beta, IL-6, IL-23, STAT3, RORgammat signals are important for Th17 differentiation. This newly defined Th17 cell clearly makes a big progress for understanding the pathophysiology of many inflammatory conditions. In the near future, many biologics or compounds that regulate the production or function of IL-17 will be produced aggressively.     

Transcriptional regulation of Th17 cell differentiation

The paradigm of effector T helper cell differentiation into either Th1 or Th2 lineages has been profoundly shaken by the discovery of T cells that secrete IL-17 and other inflammatory cytokines. This subset, referred to as Th17, is centrally involved in autoimmune disease and is important in host defense at mucosal surfaces. In mouse, a series of cytokines, including IL-6, IL-21, IL-23, and TGF-beta, function sequentially or synergistically to induce the Th17 lineage. Other cytokines, including IL-2, IL-4, IFNgamma, and IL-27, inhibit differentiation of this lineage. Here we review how the nuclear orphan receptor RORgammat functions to coordinate the diverse cytokine-induced signals and thus controls Th17 cell differentiation.     

IL-27, targeting antigen-presenting cells,promotes Th17 differentiation and colitis in mice

T helper type 17 (Th17) cells have been implicated in autoimmunity and inflammatory bowel disease (IBD). Antigen-presenting cell (APC) -derived cytokines such as interleukin (IL)-1β and IL-6 are key mediators supporting Th17 differentiation, yet how these factors are induced in vivo remains unclear. Here, we show that IL-27 acting on APCs enhances IL-6 and IL-1β production and Th17 differentiation. IL-27Rα−/− T-cell receptor (TCR)β−/− recipients fail to develop gut inflammation following naive CD4 T-cell transfer, whereas IL-27Rα+/+ TCRβ−/− recipients develop severe colitis. Investigation of T-cell responses exhibits that IL-27Rα−/− TCRβ−/− mice do not support Th17 differentiation with significantly decreased levels of IL-6 and IL-1β by APCs. Our study has identified a novel proinflammatory role for IL-27 in vivo that promotes Th17 differentiation by inducing Th17-supporting cytokines in APCs.     

Helicobacter pylori-infected macrophages induce Th17 cell differentiation

Th17 cells represent a novel subset of CD4(+) T cells, which is associated with chronic inflammation. The present study evaluated Th17 cell responses to Helicobacter pylori infection in mouse model and CD4(+) T cell differentiation in response to H. pylori-infected macrophages. Th17 cells were observed in the H. pylori-infected gastric tissue. Co-culture of CD4(+) T cells with H. pylori-infected macrophages elevated IL-17 and IFN-γ secretion, up-regulated retinoid-related orphan receptor gamma t (RORγt) and T box expressed in T cells (T-bet) expression and increased the numbers of Th17 and Th1 cells. The expression of CD40, CD80, and CD86 and the secretion of IL-6, TGF-β1, IL-23, and CCL20 were significantly increased in H. pylori-stimulated macrophages. NF-κB pathway participated in the production of IL-6, IL-23, and CCL20 from macrophages in response to H. pylori, and inhibition of NF-κB pathway of macrophages resulted in less Th17 cell differentiation. Taken together, these results suggest that H. pylori induces Th17 cell differentiation via infected macrophages.     

Priming microenvironments dictate cytokine requirements for T helper 17 cell lineage commitment

Activation of pattern recognition receptors on dendritic cells (DCs) and macrophages leads to secretion of cytokines that control differentiation of CD4(+) T cells. The current understanding is that interleukin-6 (IL-6) in combination with transforming growth factor-β (TGF-β) leads to generation of T helper 17 (Th17) lineage cells. Here, we have discovered that the cytokine requirements for Th17 cell polarization depend on the site of priming. Although IL-6 played a critical role in Th17 cell lineage priming in the skin and mucosal tissues, it was not required for Th17 cell priming in the spleen. In contrast, IL-1 played an irreplaceable role for priming of Th17 lineage cells in all tissues. Importantly, we have demonstrated that IL-6-independent and -dependent pathways of Th17 cell differentiation are guided by DCs residing in various tissues. These results reveal fundamental differences by which the systemic, mucosal, and cutaneous immune systems guide Th17 cell lineage commitment.