Regulation of human dendritic cell activation

为了诱导有效的免疫应答，微生物必须刺激TLR家族内外复杂的模式识别受体。这些不同受体的联合激活可产生互补、协同或拮抗作用，从而调节先天免疫和适应性免疫。我们过去的工作已经揭示了不同T细胞受体配体在树突状细胞活化中的重要协同作用，以及I型干扰素在树突状细胞、组织和肿瘤细胞中调节TLR下游信号传导的作用。细胞对TLR配体的反应不仅是产生促炎介质，而且还参与控制组织稳态，调节细胞分化、增殖和凋亡。MyD88和TRIF信号和I型IFN产生之间的平衡决定了组织和肿瘤细胞的增殖与凋亡以及树突状细胞的活化与存活。我们还发现，β -葡聚糖（酵母和真菌的一种成分）通过dectin 1受体刺激树突状细胞，促进了Th17反应的诱导，并与TLR受体刺激协同激活树突状细胞和促炎细胞因子的产生。dectin 1是一种细胞质部分具有itam样基元的受体，通过dectin 1发出信号，只能诱导少量早期应答的细胞因子，如il -1 β、IL-6和TNF，并且只能非常适度地激活NF-kappaB。然而，β -葡聚糖刺激诱导的il -1 β发挥了强有力的正反馈机制，这是NF-kappaB最佳激活和IL-12和IL-23等迟反应细胞因子产生所必需的。人类Th22细胞的分化机制：t辅助细胞是一组功能多样的调节细胞，通过控制多种免疫和非免疫细胞的激活或抑制来协调免疫反应。Th22细胞是辅助t细胞的一种相对较新的补充。通过对不同条件下极化的t辅助细胞的分析，我们发现Th22细胞具有可塑性，并且在th17极化细胞因子的刺激下能够成为产生IL-17的细胞。转录组分析表明，Th22细胞表达的基因大部分包含Th17和Th0细胞的特征，只有少量的自身贡献。这些结果现在被扩展到使用单细胞RNAseq的研究，以及使用ATAC-seq分析T细胞亚群基因组的转录调控。基于我们的研究结果，考虑到高度的可塑性和中间/过渡基因表达特征，我们认为Th22细胞不是一个完全独立的t辅助细胞亚群，而是一个与Th17细胞密切相关的准t辅助细胞亚群，它们共同组成一个单一的Th17/Th22调节轴，主要功能是控制屏障和结缔组织的免疫反应。因此，我们提出Th22细胞代表了一种新的t辅助细胞分化的转录模式，并推测其他t辅助细胞可能属于类似的准t辅助亚群类别。人类NK细胞启动炎性DC前体诱导Tc17分化：适应性免疫反应被认为是从先天免疫进化而来的。然而，关于先天细胞之间的相遇是否直接产生特化t细胞亚群的信息有限。我们的目标是了解自然杀伤（NK）细胞如何调节人类细胞介导的免疫。我们发现分化为炎性树突状细胞（dc）的人CD14+CD16-单核细胞在分化的早期阶段通过与NK细胞的细胞间相互作用形成。尽管一小部分单核细胞被nk细胞介导的细胞毒性消除，但在nkp30稳定突触上干扰素-g （IFN-g）的极化触发存活的单核细胞中稳定的IFN-g信号，并在分化为dc后持续存在。值得注意的是，nk细胞指示的dc驱动17型CD8+ T细胞（Tc17）的启动，具有产生IFN-g和白细胞介素- 17a的能力。与健康供者相比，由GATA2基因突变驱动的经典nk细胞缺乏症患者的这种细胞网络受损。我们的发现揭示了一种以前未被认识到的联系，tc17介导的免疫可能通过nk细胞介导的抗原提呈细胞调节来调节。稳态下先天T-bet（高）记忆表型CD4(+) T淋巴细胞分化的要求：在平行小鼠研究中，我们研究了CD4+ T淋巴细胞在稳态下由初始、常规抗原特异性记忆和记忆表型（MP）细胞区室组成。MP细胞在宿主防御由th1型免疫控制的病原体中发挥着重要的先天效应功能。然而，决定MP细胞在稳态条件下分化的机制仍有待明确。我们首先描述了MP淋巴细胞由T-bet（高）、T-bet（中）和T-bet（低）亚群组成，具有先天的th1样效应活性，仅与T-bet（高）细胞相关。我们进一步发现，T细胞区产生il -12的CD8+ dc可促进T-bet（高）MP细胞的稳态分化。补品IL-12的产生依赖于微生物无关的TLR-MyD88信号，并通过CD40-CD40L与MP CD4+ T淋巴细胞的相互作用进一步增强。后一种反应与这些细胞对自身的TCR亲和力呈正相关。综上所述，我们的研究结果表明，宿主保护性T-bet（高）MP淋巴细胞在稳态下的最佳分化需要CD8+ dc以MyD88和CD40信号依赖的方式强直产生IL-12。在一项相关的小鼠研究中，我们描述了IL-27作为肿瘤生长的免疫检查点的作用。虽然已经提出了驱动肝细胞癌（HCC）的炎症机制，但HCC中抗癌免疫的调节因子仍然知之甚少。我们发现IL-27受体（IL-27R）信号传导促进体内HCC的发展。IL-27EBI3细胞因子或IL-27RA高表达与HCC患者预后不良相关。在两种不同的肝癌发生模型中，IL-27R的缺失抑制了体内的HCC。在机制上，肿瘤微环境中的IL-27R信号抑制了先天细胞毒性淋巴细胞的细胞毒性。IL-27R消融增强了它们的积累和激活，而先天细胞毒性细胞的耗竭或功能损伤则消除了IL-27R破坏的作用。IL-27信号的药理中和增加了先天细胞毒性淋巴细胞的浸润，细胞毒性分子上调，减少了HCC的发展。我们的数据揭示了IL-27R信号作为免疫检查点调节先天细胞毒性淋巴细胞和促进不同病因的HCC的意想不到的作用，从而表明IL-27通路阻断在HCC中的治疗潜力。

To induce an effective immune response, microorganisms must stimulate complex sets of pattern-recognition receptors, both within and outside of the TLR family. The combined activation of these different receptors can result in complementary, synergistic or antagonistic effects that modulate innate and adaptive immunity. Our past work has uncovered the significant synergy in dendritic cell activation between ligands of different T cell receptors and the role of type I interferon in regulating TLR downstream signaling in both dendritic cells and tissue and tumor cells. The cellular response to TLR ligands is not only production of pro-inflammatory mediators, but they are also involved in control of tissue homeostasis and regulate cellular differentiation, proliferation, and apoptosis. The balance between MyD88 and TRIF signaling and the production of type I IFN determine proliferation versus apoptosis in tissue and tumor cells and activation versus survival in dendritic cells. We also have found that the stimulation of the dendritic cells by beta-glucan (a component of yeast and fungi) through the dectin 1 receptor facilitate the induction of a Th17 response in human and synergize with TLR receptor stimulation for activation of dendritic cells and pro-inflammatory cytokine production. Signaling through dectin 1, a receptor with an ITAM-like motif in its cytoplasmic portion, results in the induction of only a small number of early responding cytokine such as IL-1beta, IL-6, and TNF and in only a very modest activation of NF-kappaB. However, IL-1beta induced by beta-glucan stimulation exerts a potent positive feedback mechanism that it is necessary for optimal NF-kappaB activation and production of late responsive cytokines such as IL-12 and IL-23. Mechansisms of differentiation of human Th22 cells: T-helper cells represent a functionally diverse group of regulatory cells that orchestrate the immune response by controlling activation or inhibition of a wide range of immune and non-immune cells. Th22 cells are a relatively novel addition to the T-helper. Using analysis of T-helper cells polarized under different conditions we showed that Th22 cells are plastic and capable of becoming IL-17 producing cells upon stimulation with Th17-polarizing cytokines. Transcriptome analysis showed that majority of genes expressed by Th22 cells contained signatures of Th17 and Th0 cells, with only small contribution of their own. These results are now been extended to studies using single cell RNAseq as well as analysis of the transcriptional regulation of T cell subset genome by ATAC-seq. On the basis of our results, given the high degree of plasticity and the intermediate/transitional gene expression signature, we suggest that Th22 cells do not represent a completely independent T-helper subset, but a quasi-T-helper cell subset closely related to Th17 cells, which together rather comprise a single Th17/Th22 regulatory axis with a primary function to control immune responses of barrier and connective tissues. Therefore, we propose that Th22 cells represent a transcriptionally novel mode of T-helper cell differentiation and speculate of a possibility of other T-helper cells falling into a similar quasi-T-helper subset category. Human NK cells prime inflammatory DC precursors to induce Tc17 differentiation: Adaptive immune responses are acknowledged to evolve from innate immunity. However, limited information exists regarding whether encounters between innate cells direct the generation of specialized T-cell subsets. We aim to understand how natural killer (NK) cells modulate cell-mediated immunity in humans. We found that human CD14+CD16- monocytes that differentiate into inflammatory dendritic cells (DCs) are shaped at the early stages of differentiation by cell-to-cell interactions with NK cells. Although a fraction of monocytes is eliminated by NK-cell-mediated cytotoxicity, the polarization of interferon-g (IFN-g) at the NKp30-stabilized synapses triggers a stable IFN-g signature in surviving monocytes that persists after their differentiation into DCs. Notably, NK-cell-instructed DCs drive the priming of type 17 CD8+ T cells (Tc17) with the capacity to produce IFN-g and interleukin-17A. Compared with healthy donors, this cellular network is impaired in patients with classical NK-cell deficiency driven by mutations in the GATA2 gene. Our findings reveal a previously unrecognized connection by which Tc17-mediated immunity might be regulated by NK-cell-mediated tuning of antigen-presenting cells. Requirements for the differentiation of innate T-bet(high) memory-phenotype CD4(+) T lymphocytes under steady state: In parallel mouse studies, we studied CD4+ T lymphocytes that consist of naive, conventional antigen-specific memory, and memory-phenotype (MP) cell compartments in steady state. MP cells exert significant, innate-like effector function in host defense against pathogens controlled by Th1-type immunity. However, the mechanisms determining the differentiation of MP cells under homeostatic conditions remain to be defined. We first characterized MP lymphocytes as consisting of T-bet(high), T-bet(int), and T-bet(low) subsets, with innate Th1-like effector activity exclusively associated with T-bet(high) cells. We further showed that steady-state differentiation of T-bet(high) MP cells is promoted by IL-12-producing CD8+ DCs localized in the T cell zone. Tonic IL-12 production depended on microbial-independent TLR-MyD88 signaling and was further enhanced by CD40-CD40L interactions with MP CD4+ T lymphocytes. The latter response was positively associated with the TCR affinity of these cells to self. Taken together, our findings reveal that the optimal differentiation of host-protective T-bet(high) MP lymphocytes in steady state requires IL-12 tonically produced by CD8+ DCs in a MyD88 and CD40 signaling-dependent fashion. In a related mouse study, we characterize the role of IL-27 as an immunological checkpoint for tumor growth. While inflammatory mechanisms driving hepatocellular carcinoma (HCC) had been proposed, the regulators of anti-cancer immunity in HCC remain poorly understood. We found that IL-27 receptor (IL-27R) signaling promotes HCC development in vivo. High IL-27EBI3 cytokine or IL-27RA expression correlated with poor prognosis for patients with HCC. Loss of IL-27R suppressed HCC in vivo in two different models of hepatocarcinogenesis. Mechanistically, IL-27R signaling within the tumor microenvironment restrains the cytotoxicity of innate cytotoxic lymphocytes. IL-27R ablation enhanced their accumulation and activation, while depletion or functional impairment of innate cytotoxic cells abrogated the effect of IL-27R disruption. Pharmacological neutralization of IL-27 signaling increased infiltration of innate cytotoxic lymphocytes with upregulated cytotoxic molecules and reduced HCC development. Our data reveal an unexpected role of IL-27R signaling as an immunological checkpoint regulating innate cytotoxic lymphocytes and promoting HCC of different etiologies, thus indicating a therapeutic potential for IL-27 pathway blockade in HCC.