滤泡辅助性T细胞与相关疾病研究进展

滤泡辅助性T细胞(Tfh)是近几年发现的一种新的T细胞亚群,与Th1细胞、Th2细胞、Th17细胞及调节性T细胞(Tr)相互促进或拮抗,维持免疫系统的正常生理功能,其主要功能是辅助B细胞分化、发育和促进体液免疫应答,当Tfh细胞数量或功能紊乱时可引起自身免疫病、免疫缺陷病、肿瘤或感染性疾病的发生或加重.     

滤泡辅助性T细胞在免疫相关性血液病中的研究进展

T细胞亚群异常是导致免疫相关性血液病发病的重要因素,其发病机制与Thl／Th2、Thl7细胞、调节性T细胞（Treg）等辅助性T细胞异常有关。滤泡辅助性T细胞（Tfh）作为新近发现的辅助性T细胞具有辅助B细胞产生抗体的作用,其产生、分化和功能均不同于以往的Thl、Th2和Thl7等CD4＋T细胞。Tfh细胞及其相关分子的数量和／或功能异常在免疫相关性血液病的发病中发挥重要作用,有望成为其新的治疗靶点。     

IL-21在滤泡辅助性T细胞分化发育及功能中的作用

抗原刺激B细胞产生抗体需要T细胞辅助,近年来人们逐渐认识到一个命名为滤泡辅助性T细胞(Tfh)的CD4+T细胞亚群在B细胞诱导的免疫应答中具有重要作用.Tfh细胞的主要特征包括表达趋化因子受体与(CXCR5),迁移定位于B细胞滤泡辅助B细胞产生抗体.Tfh细胞产生的细胞因子IL-21能够促进B细胞分化为抗体形成细胞,这种辅助性细胞因子在Tfh细胞的分化发育、效应发挥及Tfh细胞功能失调相关的疾病中具有重要意义.     

滤泡辅助性T细胞及其可塑性的研究进展

初始T细胞受到抗原刺激后,在不同细胞因子的调控下,分化成不同的CD4+T细胞亚群,主要包括Th1、Th2、Th17、Treg和Tfh细胞。滤泡辅助性T细胞(follicular helper T cell,Tfh)是一类新的CD4+T细胞亚群,参与生发中心(germinal center,GC)形成,促使B细胞分化成浆细胞和记忆B细胞,进而在产生抗体的过程中发挥着重要作用。研究发现,Tfh细胞与其他辅助性T细胞在表达转录因子和产生细胞因子上具有重叠性,并且具有向其他CD4+T细胞亚群分化的潜能。本文主要综述Tfh细胞分化的相关分子以及表现Tfh细胞可塑性的证据。     

IL-21在滤泡辅助性T细胞分化发育及功能中的作用

抗原刺激B细胞产生抗体需要T细胞辅助,近年来人们逐渐认识到一个命名为滤泡辅助性T细胞（Tfh）的CD4^＋T细胞亚群在B细胞诱导的免疫应答中具有重要作用。Tfh细胞的主要特征包括表达趋化因子受体与（CXCR5）,迁移定位于B细胞滤泡辅助B细胞产生抗体。Tfh细胞产生的细胞因子IL-21能够促进B细胞分化为抗体形成细胞,这种辅助性细胞因子在Tfh细胞的分化发育、效应发挥及Tfh细胞功能失调相关的疾病中具有重要意义。     

转录因子与Tfh细胞分化的研究进展

滤泡辅助性T细胞(T follicular helper cell,Tfh)是一类近年来发现的对B细胞活化有重要作用的Th细胞亚群。新近研究表明,多种转录因子参与了Tfh细胞的分化过程,且与这些转录因子的作用密切相关。本文就其相关研究进展做一综述。     

滤泡辅助性T细胞及其与自身免疫性疾病关系的研究进展

滤泡辅助性T(Tfh)细胞是一类新的CD4+T细胞亚群,主要功能是辅助B细胞参与体液免疫。与其他亚群的CD4+T细胞如Th1、Th2和Th17细胞相比,对于Tfh细胞的发育过程及其功能的了解还不是很清楚;此外,对于人体中Tfh细胞的发育以及与自身免疫性疾病的关系也不是很清楚。然而,近几年来通过对系统性红斑狼疮小鼠模型以及患有系统性自身免疫性疾病的患者的研究表明Tfh细胞对致病性自身抗体的产生发挥着重要调控作用。本文主要综述了Tfh细胞的发育、功能以及Tfh细胞异常与自身免疫性疾病的关系。     

滤泡辅助性T细胞分化及其在HIV感染中的变化

T细胞辅助B细胞是适应性免疫和免疫记忆生成的基础.滤泡辅助性T细胞(Tfh)是辅助B细胞的主要T细胞亚群,其主要转录因子为Bcl6.Tfh细胞的明显特征为表达CXCR5、程序性死亡因子-1(PD-1)、IL-21和ICOS,同时Blimp-1表达下调.在HIV-1慢性感染过程中Tfh细胞累积增多,从而导致B细胞调节异常,发生功能性改变,这可能是HIV-1逃避体液免疫应答的根源.     

滤泡辅助性T细胞的分化及其与免疫性疾病的关系

初始B细胞迁移至外周淋巴器官后发生一系列的变化,其参与体液免疫应答的过程需要滤泡辅助性T细胞（Tfh）的辅助.Tfh是一类以高水平表达CXCR5为特征的T细胞亚群,其分化除了由转录因子Bcl-6调控外尚有多种因素参与,如IL-21、ICOS、T-B细胞间接触、抗体亲和力等.Tfh细胞在体内正常的免疫应答中起着重要作用,一旦其相关因子表达发生异常,将导致机体免疫功能紊乱,引发多种免疫性疾病和肿瘤.     

滤泡辅助T细胞的分化和功能及其在疾病中的作用

CD4~+辅助T(Th)细胞在抗原的刺激下会分化为不同的效应T细胞亚群。体液免疫应答具有很好的持久性,持久性的维持依赖于一群特殊的CD4~+T细胞提供辅助,即滤泡辅助性T(Tfh)细胞。树突状细胞(DC)提呈抗原并促进活化的Tfh前体细胞迁移到B细胞滤泡区域分化为成熟的Tfh细胞,辅助生发中心(GC)形成以及浆细胞和记忆性B细胞的分化,从而形成完整的体液免疫应答。Tfh细胞分化和功能上的失调均会导致多种疾病的发生。本文主要从Tfh细胞分化、功能以及在疾病中的作用三个方面对Tfh细胞的研究进展进行阐述。     

Understanding the development and function of T follicular helper cells

A fundamental function of T helper (Th) cells is to regulate B-cell proliferation and immunoglobulin class switching, especially in the germinal centers. Th1 and Th2 lineages of CD4⁺ T cells have long been considered to play an essential role in helping B cells by promoting the production immunoglobulin G2a (IgG2a) and IgG1/IgE, respectively. Recently, it has become clear that a subset CD4⁺ T cells, named T follicular helper (Tfh) cells, is critical to B-cell response induction. In this review, we summarize the latest advances in our understanding of the regulation of Tfh cell differentiation, the relationship of Tfh cells to other CD4⁺ T-cell lineages, and the role of Tfh cells in health and disease.     

Notch signaling represents an important checkpoint between follicular T-helper and canonical T-helper 2 cell fate

Type-2 immunity is regulated by two distinct CD4+ T-cell subsets. T follicular helper (Tfh) cells are required for humoral hallmarks of type-2 inflammation. T-helper type-2 (Th2) cells orchestrate type-2 inflammation in peripheral tissues, such as the lung and intestine. Given the importance of Notch signaling in the establishment of other CD4+ T-helper cell subsets, we investigated whether canonical Notch activation could differentially impact Tfh and Th2 cell fate during the induction of type-2 immunity. These studies show that Tfh cell, but not Th2 cell, generation and function is reliant on Notch signaling. While early Tfh cell specification is influenced by functional Notch ligands on classical dendritic cells, functional Notch ligands on cells other than dendritic cells, T cells, B cells, and follicular dendritic cells are sufficient to achieve full Tfh cell commitment. These findings identify Notch signaling as an early lineage-determining factor between Tfh and Th2 cell fate.     

A fundamental role for interleukin-21 in the generation of T follicular helper cells

T cell help to B cells is a fundamental property of adaptive immunity, yet only recently have many of the cellular and molecular mechanisms of T cell help emerged. T follicular helper (Tfh) cells are the CD4(+) T helper cells that provide cognate help to B cells for high-affinity antibody production in germinal centers (GC). Tfh cells produce interleukin-21 (IL-21), and we show that IL-21 was necessary for GC formation. However, the central role of IL-21 in GC formation reflected its effects on Tfh cell generation rather than on B cells. Expression of the inducible costimulator (ICOS) was necessary for optimal production of IL-21, indicative of interplay between these two Tfh cell-expressed molecules. Finally, we demonstrate that IL-21's costimulatory capacity for T helper cell differentiation operated at the level of the T cell receptor signalosome through Vav1, a signaling molecule that controls T cell helper function. This study reveals a previously unappreciated role for Tfh cells in the formation of the GC and isotype switching through a CD4(+) T cell-intrinsic requirement for IL-21.     

Human blood CXCR5(+)CD4(+) T cells are counterparts of T follicular cells and contain specific subsets that differentially support antibody secretion

Although a fraction of human blood memory CD4(+) T cells expresses chemokine (C-X-C motif) receptor 5 (CXCR5), their relationship to T follicular helper (Tfh) cells is not well established. Here we show that human blood CXCR5(+)CD4(+) T cells share functional properties with Tfh cells and appear to represent their circulating memory compartment. Blood CXCR5(+)CD4(+) T cells comprised three subsets: T helper 1 (Th1), Th2, and Th17 cells. Th2 and Th17 cells within CXCR5(+), but not within CXCR5(-), compartment efficiently induced naive B cells to produce immunoglobulins via interleukin-21 (IL-21). In contrast, Th1 cells from both CXCR5(+) and CXCR5(-) compartments lacked the capacity to help B cells. Patients with juvenile dermatomyositis, a systemic autoimmune disease, displayed a profound skewing of blood CXCR5(+) Th cell subsets toward Th2 and Th17 cells. Importantly, the skewing of subsets correlated with disease activity and frequency of blood plasmablasts. Collectively, our study suggests that an altered balance of Tfh cell subsets contributes to human autoimmunity.     

Here,there and everywhere: T follicular helper cells on the move

T follicular helper (Tfh) cells have the important function of providing B‐cell help for the induction of antigen‐specific antibody production. As such, it is important to determine the factors that regulate the development, differentiation and function of Tfh cells. This review highlights some of the recent advances in our understanding of Tfh cell migration, Tfh cell memory and the origins and fate of circulating Tfh cells in the blood, that have been revealed from studies in humans and mice.