MicroRNA regulation of T-cell development

MicroRNAs are short, 19–24 nucleotide long, RNA molecules capable of regulating the longevity and, to a lesser extent, translation of messenger RNA (mRNA) species. The function of the microRNA network, and indeed, even that of individual microRNA species, can have profoundly different roles in even a single cell type as the microRNA/mRNA composition evolves. As the role of microRNA within T cells has come under increasing scrutiny, several distinct checkpoints have been demonstrated to have a particular reliance on microRNA regulation. MicroRNAs are arguably most important in T cells during the earliest and last stages in T-cell biology. The first stages of early thymic differentiation have a crucial reliance on the microRNA network, while later stages and peripheral homeostasis are largely, although not completely, microRNA-independent. The most profound effects on T cells are in the activation of effector and regulatory functions of conventional and regulatory T cells, where microRNA deficiency results in a near-complete loss of function. In this review, we focus on integrating the research on individual microRNA into a more global understanding of the function of the microRNA regulatory network in T cells.     

Th17细胞与肝脏疾病的研究进展

机体免疫系统是抵抗外来病原体和各种损害的防御系统,根据CD4^＋T细胞的功能经典地分为辅助性T细胞（Th1、Th2）、细胞毒性T细胞以及调节性T细胞（Treg）3个亚群。Th1介导细胞免疫,Th2介导体液免疫,而Treg则在维护机体免疫平衡中发挥重要作用。然而随着对自身免疫性疾病的研究,发现一群不同于Th1、Th2、Treg的新型CD4^＋T细胞亚群——Th17细胞。已证实Th17细胞与清除胞外病原体、炎症、自身免疫性疾病和肿瘤的发生发展有密切联系。随着人们对肝炎、肝纤维化和肝癌等肝病认识不断加深,这种新型的Th17细胞在这些疾病中发生发展的作用机制也不断的被研究者所关注。     

树突状细胞诱导Th17细胞分化及其在气道炎症性反应中的作用

树突状细胞(DCs)是最具潜能的抗原提呈细胞,它能激活初始型T细胞并分泌相关细胞因子促进Th0的不同分化方向,在启动免疫应答中扮演着重要角色。Th17细胞是最新发现的与Th1、Th2不同的Th细胞亚群,能介导气道前炎症反应,并且与自身免疫病有关。本文综述了DCs诱导Th0向Th17细胞的分化研究及其在气道炎症性反应中的作用。     

类风湿性关节炎患者外周血Th17/Treg细胞比率失衡的研究

目的:观察类风湿性关节炎(RA)患者外周血Th17细胞与Foxp3+CD4+CD25+调节性T(Treg)细胞的平衡状态与疾病状态的关系,初步阐明Th17/Treg细胞比率失衡在RA发病机制中的作用和意义。方法:流式细胞术(FCM)检测RA患者和健康人外周血中Th17细胞和Foxp3+CD4+CD25+Treg细胞的比率。结果:活动期RA患者外周血CD3+CD4+T细胞和Th17细胞的比率均明显高于健康对照组(P均0.05);而Foxp3+CD4+CD25+Treg细胞的比率明显低于健康对照组(P0.05)。随疾病活动性的增加,Th17细胞表达增高(P0.05);而Foxp3+CD4+CD25+Treg细胞表达降低,但无统计学意义(P0.05)。结论:RA患者外周血T细胞紊乱以CD4+T细胞的增加为主,Th17细胞比率的增加和Foxp3+CD4+CD25+Treg细胞比率的降低所致的Th17/Treg细胞比率失衡,可能在RA的发生发展中起重要作用。     

CD4+ T-cell subsets in intestinal inflammation

Intestinal CD4⁺ T cells are essential mediators of immune homeostasis and inflammation. Multiple subsets of CD4⁺ T cells have been described in the intestine, which represents an important site for the generation and regulation of cells involved in immune responses both within and outside of the gastrointestinal tract. Recent advances have furthered our understanding of the biology of such cells in the intestine. Appreciation of the functional roles for effector and regulatory populations in health and disease has revealed potential translational targets for the treatment of intestinal diseases, including inflammatory bowel disease. Furthermore, the role of dietary and microbiota-derived factors in shaping the intestinal CD4⁺ T-cell compartment is becoming increasingly understood. Here, we review recent advances in understanding the multifaceted roles of CD4⁺ T cells in intestinal immunity.     

Peritoneal dialysate-range hypertonic glucose promotes T-cell IL-17 production that induces mesothelial inflammation

Peritoneal dialysis (PD) employs hypertonic glucose to remove excess water and uremic waste. Peritoneal membrane failure limits its long-term use. T-cell cytokines promote this decline. T-cell differentiation is critically determined by the microenvironment. We here study how PD-range hypertonic glucose regulates T-cell polarization and IL-17 production. In the human peritoneal cavity, CD3⁺ cell numbers increased in PD. Single cell RNA sequencing detected expression of T helper (Th) 17 signature genes RORC and IL23R. In vitro, PD-range glucose stimulated spontaneous and amplified cytokine-induced Th17 polarization. Osmotic controls l -glucose and d -mannose demonstrate that induction of IL-17A is a substance-independent, tonicity dose-dependent process. PD-range glucose upregulated glycolysis and increased the proportion of dysfunctional mitochondria. Blockade of reactive-oxygen species (ROS) prevented IL-17A induction in response to PD-range glucose. Peritoneal mesothelium cultured with IL-17A or IL17F produced pro-inflammatory cytokines IL-6, CCL2, and CX3CL1. In PD patients, peritoneal IL-17A positively correlated with CX3CL1 concentrations. PD-range glucose-stimulated, but neither identically treated Il17a^−/−Il17f^−/− nor T cells cultured with the ROS scavenger N-acetylcysteine enhanced mesothelial CX3CL1 expression. Our data delineate PD-range hypertonic glucose as a novel inducer of Th17 polarization in a mitochondrial-ROS-dependent manner. Modulation of tonicity-mediated effects of PD solutions may improve membrane survival.     

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。     

p19-targeted ABD-derived protein variants inhibit IL-23 binding and exert suppressive control over IL-23-stimulated expansion of primary human IL-17+ T-cells

Interleukin-23 (IL-23), a heterodimeric cytokine of covalently bound p19 and p40 proteins, has recently been closely associated with development of several chronic autoimmune diseases such as psoriasis, psoriatic arthritis or inflammatory bowel disease. Released by activated dendritic cells, IL-23 interacts with IL-23 receptor (IL-23R) on Th17 cells, thus promoting intracellular signaling, a pivotal step in Th17-driven pro-inflammatory axis. Here, we aimed to block the binding of IL-23 cytokine to its cell-surface receptor by novel inhibitory protein binders targeted to the p19 subunit of human IL-23. To this goal, we used a combinatorial library derived from a scaffold of albumin-binding domain (ABD) of streptococcal protein G, and ribosome display selection, to yield a collection of ABD-derived p19-targeted variants, called ILP binders. From 214 clones analyzed by ELISA, Western blot and DNA sequencing, 53 provided 35 different sequence variants that were further characterized. Using in silico docking in combination with cell-surface competition binding assay, we identified a group of inhibitory candidates that substantially diminished binding of recombinant p19 to the IL-23R on human monocytic THP-1 cells. Of these best p19-blockers, ILP030, ILP317 and ILP323 inhibited IL-23-driven expansion of IL-17-producing primary human CD4^+?T-cells. Thus, these novel binders represent unique IL-23-targeted probes useful for IL-23/IL-23R epitope mapping studies and could be used for designing novel p19/IL-23-targeted anti-inflammatory biologics.     

IL-17: an important pathogenic factor in endometriosis

Interleukin-17 (IL-17) is known as a Th17-cell-derived proinflammatory cytokine, which plays a pivotal role in several inflammatory and autoimmune diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis, and psoriasis. Emerging evidence has shown that IL-17 is linked to endometriosis, although the etiology of endometriosis is still unknown. The IL-17 expression is up-regulated in serum, peritoneal fluid (PF) and endometriotic lesions from patients with endometriosis but the related regulation mechanisms are complex and obscure. Meanwhile, the specific roles of IL-17 in endometriosis are also worthy of further exploration. Through the integration and summary of literature, we conclude that the secretion of IL-17 increases under the regulation of ectopic microenvironment and other factors, and then IL-17 is deeply involved in endometriosis in the regulation of immune microenvironment, the invasion and growth of ectopic lesions, and so on, which implies its therapeutic value in this disorder.     

Multiparameter grouping delineates heterogeneous populations of human IL-17 and/or IL-22 T-cell producers that share antigen specificities with other T-cell subsets

The ontogenic relationship between pro-inflammatory populations of interleukin-17 (IL-17A)- and/or IL-22-producing T cells and other T-cell subsets is currently unclear in humans. To appreciate T helper cell-lineage commitment, we combined cytokine production profiles of in vitro expanded T-cell clones with T-cell receptor (TCR) clonotypic signatures. Moreover, ex vivo cytokine production profiles at the single-cell level were analyzed using an original approach based on the hierarchical cluster analysis of multiparametric flow cytometry data. These combined approaches enabled the delineation of distinct functional T-cell subsets, including Th1, Th2, Tr1, Th17 cells and a highly polyfunctional IL-22-producing T-cell population. Cluster analysis highlighted that the IL-22-producing T-cell population should be considered independently from the Th17 and Th1 subsets, although it was more closely related to the former. In parallel, we observed extensive TCRαβ sharing across all five subsets defined. The strategy described here allows the objective definition of cellular subsets and an unbiased insight into their similarities. Together, our results underscore the ontogenic plasticity of CD4(+) T-cell progenitors, which can adopt a differentiation profile irrespective of antigen specificity.     

DC subsets in positive and negative regulation of immunity

Summary: Since their discovery in 1973, dendritic cells (DCs) have gained strong interest from immunologists because of their unique capacity to sensitize naive T cells. There is now strong evidence that cells of the dendritic family not only control immunity but also regulate responses to self and non-self, thereby avoiding immunopathology. These two complementary functions are critical to ensure the integrity of the organism in an environment full of antigens. How DCs display these opposite functions is still intriguing. Here, we review the role of DC subsets in the regulation of T-helper responses in vivo.     

过敏性哮喘患者调节性T细胞对Th17细胞和Th9细胞的影响

目的:深入研究过敏性哮喘病人(轻到中度)急性发作期的调节性T细胞对Th17和Th9细胞功能影响的异常。方法:招募30例过敏性哮喘病人(轻到中度)急性发作期和30例健康者,采集外周静脉血30 ml,分离PBMC,然后应用磁珠法体外分离CD4+CD25+CD127-/low调节性T细胞(Tregs)和CD4+CD25-效应T细胞(选取分离纯度90%以上的标本继续下一步试验)。在PHA刺激下体外培养,检测效应T细胞增殖情况和Th17细胞、Th9细胞特异性基因(RORC和PU.1)表达及特异性细胞因子(IL-17和IL-9)分泌情况,检测哮喘病人Th17细胞和Th9细胞的异常情况;并给予Tregs干预,检测Tregs对Th17细胞和Th9细胞分化的影响。结果:哮喘组和健康对照组的Tregs均可以抑制CD4+CD25-效应细胞增殖反应,但哮喘组Tregs的抑制功能较健康对照组明显下降(P=0.03)。哮喘病人RORC表达和IL-17分泌均高于对照组(P0.05),Tregs对RORC表达的抑制能力在哮喘组有所下降(P0.05),但对IL-17分泌的抑制能力在哮喘组和对照组没有显著差别(P0.05);哮喘病人IL-9分泌无论是否加入Tregs干预均高于对照组(P0.05),但PU.1表达只有在加入Tregs干预后才高于对照组(P=0.04);Tregs对PU.1表达和IL-9分泌的抑制能力在哮喘组和对照组没有显著差别(P0.05)。结论:过敏性哮喘病人(轻到中度)急性发作期Tregs数量和功能下降,而Th17细胞和Th9细胞的特异性基因表达和特异性细胞因子生成增加,哮喘病人的Tregs在体外对Th17细胞的抑制功能有所下降,但尚未发现Tregs对Th9细胞的抑制功能明显降低。     

IL-23/IL-17轴在银屑病免疫发病机制中的作用

银屑病是一种以T淋巴细胞异常活化和浸润为主要特征的慢性炎性反应皮肤病。Th17细胞及IL-23/IL-17轴在银屑病的发病机制中可能处于关键地位,并成为新的治疗靶标。IL-23诱导Th17细胞分化增殖,分化成熟的Th17可以分泌IL-17、IL-21、IL-22等多种细胞因子,Th17类细胞因子在银屑病等多种自身免疫疾病和炎性疾病中起重要作用。     

IL-23/IL-17炎症轴在咪喹莫特诱导的小鼠银屑病样皮肤损害中的作用

 目的：观察IL-23/IL-17炎症轴在咪喹莫特诱导的小鼠银屑病样皮损形成过程中的作用及变化规律。方法：雌性BALB/c小鼠随机分为正常对照组和咪喹莫特组,采用PASI评分观察银屑病样小鼠模型皮损动态变化;光镜观察皮损组织形态学变化;细胞因子抗体芯片技术对比检测两组小鼠血清及皮损组织中细胞因子谱的变化;采用流式细胞小球微阵列术、实时荧光定量PCR和蛋白免疫印迹分析技术对小鼠血清及皮肤组织中细胞因子含量、mRNA和蛋白表达水平进行检测;流式细胞术分析外周血及脾细胞成分。结果：咪喹莫特诱导小鼠产生红斑、鳞屑、增厚等典型的银屑病样皮损,并随着给药时间的延长呈现一个抛物线型的动态变化;经咪喹莫特外用刺激后,小鼠皮肤及血清中IL-23/IL-17轴相关细胞因子、Th1、Th2和Treg类细胞因子含量及表达水平均显著升高。IL-23/IL-17轴细胞因子表达也呈现一个先升高后降低的动态变化过程。咪喹莫特组小鼠外周血及脾细胞中树突状细胞比例显著升高,脾细胞中Th17细胞比例升高,约为正常对照组的3～4倍,Treg细胞比例约为正常对照组的2倍。结论：咪喹莫特诱导小鼠产生的皮损症状、病理学特征及细胞因子改变都与银屑病相似,是进行银屑病研究可行的动物模型,该模型制备后第1～8天可模拟疾病的发展阶段。Th17细胞活化及IL-23/IL-17轴参与了该模型皮损的形成,并呈现一个先升高后降低的动态变化过程。Th1细胞介导的炎症反应也参与了该模型皮损的形成,并且伴随Treg 和Th2类细胞因子的反馈性升高。     

MCAM-expressing CD4(+) T cells in peripheral blood secrete IL-17A and are significantly elevated in inflammatory autoimmune diseases

Th17 cells are a subset of CD4⁺ T cells characterized by production of IL-17 and are known to be key participants in inflammatory reactions and various autoimmune diseases. In this study we found that a subset of human CD4⁺ T cells expressing MCAM (CD146) have higher mRNA levels of RORC2, IL-23R, IL-26, IL-22, IL-17A, but not IFN-γ, compared to CD4⁺ T cell not expressing CD146. Upon TCR stimulation with CD3/CD28, CD4⁺CD146⁺ T cells secrete significantly more IL-17A, IL-6, and IL-8 than do CD4⁺CD146⁻ T cells. Low frequencies of CD4⁺CD146⁺ T cells are found in the circulation of healthy adults, but the frequency of these cells is significantly increased in the circulation of patients with inflammatory autoimmune diseases including Behcet’s, sarcoidosis and Crohn’s disease. Patterns of gene expression and cytokine secretion in these cells are similar in healthy and disease groups. In Crohn’s disease, the increase in CD4⁺CD146⁺ cells in the circulation correlates with disease severity scores. These data indicate that expression of CD146 on CD4⁺ T cells identifies a population of committed human Th17 cells. It is likely the expression of CD146, an endothelial adhesion molecule, facilitates adherence and migration of Th17 cells through the endothelium to sites of inflammation.     

IL-17-producing T cells contribute to acute graft-versus-host disease in patients undergoing unmanipulated blood and marrow transplantation

The aim of this study was to investigate the effects of IL-17-producing T cells, including Th17 and Tc17 cells, on acute graft-versus-host disease (aGVHD) in patients who had undergone granulocyte colony-stimulating factor (G-CSF)-mobilised peripheral blood progenitor cell (PBPC) and G-CSF-primed bone marrow (G-BM) transplantation. Allografts from forty-one patients were analysed for IL-17-producing T cells with respect to aGVHD. Furthermore, ten patients with aGVHD onset were monitored for the presence of Th17 cells in the peripheral blood by flow cytometry. Patients who received a higher dose of Th17 cells in the G-BM (>8.5 × 10(4) /kg, p=0.005) or a higher dose of Tc17 cells in PBPC (>16.8 × 10(4) /kg, p=0.001) exhibited a higher incidence of aGVHD. An increased Th17 population (up to 4.99% CD4(+) T lymphocytes) was observed in patients with aGVHD onset. In contrast, the percentage of Th17 population decreased drastically in aGVHD patients following treatment to achieve partial and complete remission (p=0.013 and p=0.008, respectively). All percentages of Th17 and Tc17 cells were significantly reduced after in vivo G-CSF application. Our results suggested that IL-17-producing T cells contributed to aGVHD. The application of G-CSF in vivo aided in reducing the occurrence of aGVHD through a decrease in IL-17 secretion by T cells.