PRDM1

调控B细胞产生抗体的Tfh细胞数量异常增加会导致自身免疫性疾病，因此同时存在一种抑制性细胞群：滤泡调节T(follicular regulatory T cell,Tfr)细胞来维持正常免疫耐受。滤泡调节T细胞：起源、功能、定位随着对Tfr细胞的进一步了解，小鼠模型和人体内Tfr亚群表征、活性和免疫调节功能的差异认识也逐渐细化。chapter1：亚群分类和表征人和小鼠Tfr细胞中，按照来源均可分为nTfr、iTfr和cTfr亚群。自然Treg细胞的称为nTfr细胞；来源于Th细胞形成的外周Treg(pTreg)也能在免疫后几天内形成一部分iTfr；cTfr细胞则指在体内长期存活的记忆样循环中的Tfr细胞。（1）根据CD25分类的nTfrnTfr小鼠人表达CD25- Tfr亚群下调FoxP3、Helios、CD103、GITR和Blimp1，上调Bcl6、CXCR5和PD-1。CD25- Tfr亚群表达Helios+ BCL6hi CXCR5hi PD-1hi，表达水平与小鼠相似。CD25high Foxp3high亚群则表达额外的Treg效应分子如Entpd1、CTLA4、Icos和GZMB，并上调IL-10和CCR5的表达。CD25high Foxp3high亚群表达高水平的FOXP3、Entpd1、TIGIT、OX40、GITR、HELIOS、BLIMP1、CTLA4和IL-17RACD25+ nTfr细胞一般表达中等水平的CXCR5和PD1。分布CD25− nTfr亚群更多地分布在GCs内。在CXCR5和PD1高表达的基础上，人CD25− TfR细胞可能与小鼠CD25− Tfr一样定位于GC内。CD25- Tfr细胞在人扁桃体中的出现频率明显低于小鼠。CD25+ nTfr亚群则主要分布在GCs周围的滤泡中。CD25+ nTfr亚群主要定位在卵泡中。细胞因子Prdm1和IL-10主要由CD25+ nTfr细胞产生CD25+ nTfr亚群也表达IL-10，但不是产生比例最高的亚群。转化在GC应答的早期阶段：IL-2可能是通过触发Blimp1转录因子，从而抵消Bcl6介导的nTfr细胞CXCR5和PD-1的上调传导，从而阻断CD25+ nTfr细胞转化和移动。目前还不清楚是什么因素促使Tfh细胞转变为CD25hi Tfh细胞和iTfr细胞，可能是IL-2通过低亲和力的IL-2受体IL-2Rβ被Tfh细胞感知。在GC应答的后期阶段：IL-2下降，使得部分CD25+ nTfr→CD25- nTfr细胞，↑Bcl6+ CXCR5high PD-1high，同时转移到GC内分布。部分Tfr细胞上调Foxp3表达，下调IL-21产生相关的基因，从而进一步分化为iTfr细胞。International Immunology（2）iTfr细胞iTfr小鼠人来源在GC应答晚期，还有一部分CD25- Foxp3+ CD4+ T细胞积累，即Tfh来源的FoxP3+GC驻留T细胞，又称诱导的iTfr细胞。类似小鼠表达均为FOXP3+ AIOLOS+ LAG3+ CD127−，表达KLRB1和CD3 8的水平高于其他滤泡T细胞亚群。分布在CXCR5和PD-1高表达的基础上，iTfr细胞在GCs中更丰富。大多数Tfr细胞是nTfr细胞。 iTfr亚群平均数量高于nTfr亚群。在儿童扁桃体中，iTfr克隆的数量大约是nTfr克隆的两倍。细胞因子下调IL-21表达高表达IL-21和IL-10这部分细胞因子表达功能主要由nTfr产生。iTfr细胞则同时表达PRDM1和IL-10，并且与人nTfr细胞相比，再次刺激后产生IL-10的细胞比例更高。International Immunology（3）cTfr细胞cTfr小鼠人表达CXCR5+ ICOSint FoxP3+CD45RA− CXCR5+ FOXP3+，大多数cTfr细胞是HELIOS+ CD25+ CD127low与非滤泡Treg细胞相比，CD38在cTfr细胞上的表达有所上调。由于人iTfr细胞也上调CD38，所以猜测cTfr细胞很可能包括记忆性iTfr细胞和nTfr细胞。分布cTfr细胞可在二次免疫激活时被招募到SLO卵泡和GC中。International Immunologychapter2：功能活性功能活性小鼠人①Th/Tfh细胞增殖和细胞因子产生的调控Tfr细胞抑制Th细胞的激活及其增殖。Tfr细胞促进了共培养的B细胞和Tfh细胞的长期表观遗传变化，改变了它们的代谢调节，并减少了Glut1的表达。加入IL-21可以逆转Tfr介导的Glut1表达减少。类似小鼠②抑制B细胞反应与PC的形成TFR细胞可以在GC反应的高峰期直接抑制GC B细胞。该作用依赖于GC B细胞产生CCL3和Tfr对CCL3分泌细胞的趋化作用。人cTfr细胞能够抑制Tfh细胞体外激活的B细胞和PC的形成，其效果与nTreg细胞相似。nTfr细胞可能有助于限制GC B细胞以直接接触依赖的方式产生抗体分泌细胞。Tfr细胞产生高度保守的神经素，可被GC B细胞直接摄取。人Tfr细胞也产生神经素，类似小鼠Treg细胞，从而直接作用于GC B细胞。但其具体产生神经蛋白的亚群尚不明确。③转铁蛋白受体细胞与自身免疫性疾病的关系多种缺陷小鼠模型中都显示，Tfr缺陷小鼠会导致形成抗dsDNA抗体和系统性红斑狼疮(SLE)等自身免疫性疾病症状加重。在TFR细胞消融后，小鼠体内多种自身抗体上调。不同疾病中，Tfr水平和疾病关系相反。一种假设是，Tfr细胞对GC表现出普遍的非特异性抑制，限制了从扩增和分化为效应细胞的B细胞克隆的选择，从而保留更多非外来抗原性B细胞。负相关：在RA和SLE中，cTfr的频率都有增加和减少的报道。MS患者和重症肌无力患者的TFR细胞频率降低，重症肌无力患者的Tfr细胞与疾病的严重程度呈负相关。正相关：干燥综合征和强直性脊柱炎中，cTfr细胞频率增加与抗SSA/Ro、抗SSA/Ro自身抗体和轻微SGS的淋巴细胞浸润呈正相关。④外源抗原特异性B细胞的正向调节对免疫和感染的最佳B细胞反应需要Tfr细胞。人CD38+ iTfr细胞与GC B细胞共培养时，比CD38- nTfr亚群在体外实验中产生的IgG和IgA显著增加。人cTfr细胞不支持B细胞在细胞培养中存活和产生抗体。目前仅确认IL-10对于GC B细胞循环和亲和力成熟是重要的。IL-10介导的小鼠TfR细胞对GC B细胞的调节可能是非常不同的，因为表达IL-10的IL-25+nTfr细胞主要是自身抗原特异性的。⑤调节IgE反应Tfr细胞在调节IgE反应中可能扮演着相反的角色。通过调节IL-10的产生；通过神经素的直接调控。负向调节：可能是通过转铁蛋白受体介导的抑制IL-13的表达，进而B细胞向IgE的转换；以及通过nTfr细胞表达的神经素肽直接作用于B细胞。例如，儿童血清中的IgE滴度与扁桃体CD25+ Tfh细胞呈负相关，与人类扁桃体中Tfr细胞的总体频率呈正相关。同时，变应性鼻炎患者的cTfr细胞数量减少，经变应原免疫治疗后cTfr/cTfh比值恢复。正向调节：当GCs参与IgE PB反应时，IL-10可能支持GC B细胞在亮区和暗区之间的循环；同时支持变应原特异性B细胞的亲和力成熟来增强对外来抗原的IgG1和IgE应答。所有研究都表明Tfr缺陷伴随着总IgE的显著增加。本周好文推荐如需转载请联系佰傲谷并在醒目位置注明出处·····

A new CRISPR interference (CRISPRi) model explores how the pioneer transcription factor FOXA controls human endoderm differentiation during liver development, and how the pioneer transcription factor OCT4 influences the behavior of pluripotent stem cells. The unexpected findings could influence future organoid and cell reprogramming studies. One of the important breakthroughs that made it possible to program or reprogram cell fate more efficiently and with higher fidelity in a dish was discovering how to make use of a small set of molecular cowboys called pioneer transcription factors (TFs). Every cell in our bodies has more than 200 transcription factors expressed inside, riding along the DNA helix instructing specific genes to activate and deactivate. During the early stages of fetal development, a small subset of "pioneer" TFs act inside our precursor cells driving them to make the mature cells that become parts of the spine, the heart, the liver, and so on. Identifying the key pluripotent pioneer TFs helped researchers learn how to make induced pluripotent stem cells from any type of adult cells, which could then be instructed to make other types of cells, thus forming organoids that can mimic functional organ tissue. Furthermore, tissue-specific pioneer TFs can directly reprogram one adult cell type into a targeted cell type without passing through a pluripotent state. Currently, there is considerable interest in producing therapeutic target cells from pioneer TF-mediated reprogramming of skin or other accessible somatic cells, as they hold great promise for personalized disease modeling and regenerative medicine. However, a major challenge is achieving sufficient gene repression of the original cell type, as inadequate repression often leads to the formation of "dead-end" cells or hybrid cells, thus limiting translational applications. Now a study published online Jan. 10, 2024, in Molecular Cell, reveals important new details about how pioneer TFs do their important jobs. "As we gain a more comprehensive understanding of the mechanisms underlying pioneer TF-mediated gene repression, it will greatly enhance the precise manipulation of cell fate in cellular programming and reprogramming," says Makiko Iwafuchi, PhD, a member of the Division of Developmental Biology and the Center for Stem Cell & Organoid Medicine at Cincinnati Children's. The first author, Satoshi Matsui, PhD, and Iwafuchi collaborated with Hee-Woong Lim, PhD, a co-senior author and a member of the Division of Biomedical Informatics, on the study. Until this study, most experts believed that pioneer TFs functioned primarily by activating genes to send cells toward their ultimate fates. However, scientists have learned that our genetic programming is packed with alternative pathways, which must be actively shut down. So how does the body ensure that precursor cells consistently follow the correct path? It turns out that pioneer TFs do more than push cells in the desired direction. When functioning correctly, these cowboys ride ahead and cut off alternative paths so that developing cells keep developing as intended. Who are these pioneers? The Cincinnati Children's team established a new CRISPR interference (CRISPRi) model to explore how the pioneer transcription factor FOXA controls human endoderm differentiation during liver development, and how the pioneer transcription factor OCT4 influences the behavior of pluripotent stem cells. They found that when FOXA function was disrupted, cells followed multiple development pathways. But when FOXA functioned normally, the cells stayed on track. This allowed the team to conclude that FOXA prevents alternative lineage and precocious gene expression. The team went on to show that FOXA gets help with repressing access to alternative pathways from another transcription factor called PRDM1 and other epigenetic repressors. Meanwhile in pluripotent cells, the pioneer transcription factor OCT4 performs a similar repression function by teaming up with a related transcription factor called PRDM14. The central role of FOXA and its ability to repress development pathways were unexpected and critical findings that could influence future organoid and cell reprogramming studies, Iwafuchi says. Finding a similar relationship occurring with OCT4 was an important further proof of concept because that transcription factor was already known to be among the pioneer TFs that enable reprogramming of somatic cells into pluripotent stem cells. Next steps Now that researchers have shown that two pioneer TFs coordinate with PRDM TFs to safeguard cell fate, it appears likely that other TFs have similar relationships. As these TF teams are identified, it may become possible to produce organoids and other engineered tissues in larger volumes with higher degrees of consistency and fidelity -- steps that will be important for scaling up the technology.

关注并星标CPHI制药在线   日前，苏州信诺维医药科技股份有限公司1类新药「XNW21015片」在国内获得临床试验默示许可，拟用于治疗标准治疗失败的或对标准治疗不耐受或缺乏有效标准治疗的晚期和/或转移性恶性实体瘤。       XNW21015是一种高效、选择性造血祖细胞激酶1（HPK1）抑制剂。研究显示，XNW21015能有效抑制HPK1驱动的SLP76磷酸化，促进T细胞活化，并增加T细胞IL-2的分泌，单用或者与PD-1抗体联用产生协同抗肿瘤作用，且安全性特征良好，整体安全性可控。       此外，在小鼠同源肿瘤模型中，口服XNW21015显示出良好的PK谱和强大的抗肿瘤活性，无论是单药还是与免疫检查点抑制剂联合使用。在人源化PDX(患者来源的异种移植物)模型中，XNW21015增强肿瘤浸润淋巴细胞(TIL)。       关于HPK1及其抑制剂       HPK1，即造血祖细胞激酶1 ，是有丝分裂原激活蛋白激酶（MAP4K）家族成员之一。MAP4K家族包括HPK1、GCK、GLK、HGK、KHS 和mink 等，与哺乳动物ste20丝氨酸/苏氨酸蛋白激酶家族同源，在调节细胞存活、细胞迁移、细胞凋亡和自噬中发挥重要作用。       HPK1是一种以ATP或其它核苷酸作为磷酸供体的丝氨酸/苏氨酸蛋白激酶，主要在造血细胞，如T细胞，B细胞，中性粒细胞，树突状细胞（DC）和巨噬细胞中表达。HPK1由N端的激酶结构域（HPK1-KD）、4个富含脯氨酸基序（PR1、PR2、PR3和PR4）和C端的柠檬酸同源结构域组成，参与多种细胞信号级联反应，包括抗原受体信号、细胞凋亡、生长因子信号和细胞因子信号调控。       HPK1是T细胞受体（TCR）和B细胞信号通路的负反馈免疫调节因子，能负调控树突细胞活化和T细胞与B细胞反馈。研究发现，HPK1可与许多接头蛋白结合，如SLP76家族，Gads、HIP-55、GRB2家族，LAT、CRK家族等相互作用，活化造血干细胞的SAPK/JNK信号途径，从而对TCR通路进行负向调节。抑制HPK1可增强T细胞活性，从而提高抗肿瘤免疫。       2020年8月，清华大学药学院廖学斌课题组与中山大学魏来课题组合作在《Cancer Cell》杂志上发表了题为《Hematopoietic Progenitor Kinase1 (HPK1) Mediates T Cell Dysfunction and Is a Druggable Target for T Cell-Based Immunotherapies》研究论文。该研究发现HPK1-NFκB-Blimp1信号轴介导T细胞功能障碍。MAP4K1的高表达（编码HPK1）与T细胞衰竭的增加和某些癌症类型患者的较差生存有关。在MAP4K1敲除小鼠中，肿瘤的生长比野生型小鼠慢，并且浸润性T细胞的衰竭程度降低，活性和增殖性更高。       进一步研究发现，针对嵌合体（PROTAC）介导的HPK1的遗传耗竭，药理学抑制或蛋白水解，可在血液和实体瘤的各种临床前小鼠模型中提高基于CAR-T细胞的免疫疗法的功效。这证实HPK1有潜力成为T细胞免疫疗法药物研发的靶点。       据药渡数据库，目前全球已有多款HPK1抑制剂进入临床试验阶段，最快已进入2期临床。整体来看，在研HPK1抑制剂主要是小分子化药，多被开发用于治疗实体瘤。       具体品种来看，CFI-402411是一种口服HPK1激酶抑制剂，已公布的CFI-402411单药或与PD-1抑制剂pembrolizumab联合治疗晚期实体肿瘤的早期临床数据显示：CFI-40241的安全性可控，暴露量随剂量成比例增加。在31例疗效可评估的患者中，2例达到PR（目标病灶分别缩小了36%和81%），9例达到SD。       NDI-101150是Nimbus Therapeutics开发的一款口服小分子HPK1抑制剂，用于治疗实体瘤。2019年7月，Nimbus Therapeutics与BMS达成合作协议，共同开发NDI-101150。       研究显示，NDI-101150在体外和体内模型中均显示出对T细胞特异性激酶和MAP4K家族激酶有很高的选择性抑制作用。NDI-101150可增强激活T细胞产生IL-2，降低PGE2介导的T细胞活化的免疫抑制。在小鼠肿瘤模型中，无论是单一治疗还是联合抗CTLA4，口服NDI-101150均能显著抑制肿瘤生长。       我国药企如宇繁生物、百济神州、信诺维、阿诺生物等也积极布局HPK1靶点，其中百济神州研发BGB-15025是一款小分子HPK1抑制剂，临床前研究显示其与替雷利珠单抗具有联合活性，并且具有广阔的治疗窗口。       总结       作为肿瘤免疫治疗新靶点，HPK1整体进展较慢。目前，HPK1抑制剂已在多项研究中证实具有抗肿瘤潜力，而且HPK1抑制剂通过免疫激活作用，具备将"冷肿瘤"转化为"热肿瘤"的能力，有望与其他免疫疗法如PD-1单抗联用提高免疫治疗的应答率和有效率。而且，除了小分子HPK1抑制剂，已有企业/机构基于PROTAC技术开发出HPK1降解剂。期待随着研究人员的不懈努力，HPK1靶点可以早日迎来重磅进展。       智药研习社近期直播报名来源：CPHI制药在线声明：本文仅代表作者观点，并不代表制药在线立场。本网站内容仅出于传递更多信息之目的。如需转载，请务必注明文章来源和作者。投稿邮箱：Kelly.Xiao@imsinoexpo.com▼更多制药资讯，请关注CPHI制药在线▼点击阅读原文，进入智药研习社~