B/T淋巴细胞弱化因子在免疫调控和免疫相关疾病中的作用

B/T淋巴细胞弱化因子(B and T lymphocyte attenuator,BTLA)是免疫调控中重要的检查点分子之一.BTLA属于CD28超家族,其蛋白质结构类似于程序性细胞死亡受体-1(programmed cell death-1,PD-1)和细胞毒性T淋巴细胞相关抗原-4(cytotoxic T lym...     

犬肿瘤免疫疗法的研究进展

目前,犬肿瘤疾病已成为临床常见病。手术疗法、放射疗法及化学疗法作为传统治疗手段虽然在一定程度上能够改善病犬的生存及预后,但仍不能彻底改变病犬的生存质量。因此,新的肿瘤治疗方式的引入迫在眉睫。肿瘤免疫疗法的诞生为犬类肿瘤的预防和治疗提供了契机。该文综述了犬肿瘤免疫疗法的研究进展,包括免疫检查点如程序性死亡受体1(programmed cell death 1,PD-1)/程序性死亡受体配体1(programmed cell death ligand 1,PD-L1)及细胞毒性T淋巴细胞抗原-4(cytotoxic T lymphocyte antigen-4,CTLA-4)。同时,该文评述了过继细胞疗法(adoptive cell therapy,ACT)在犬肿瘤治疗中的前景,为未来犬肿瘤治疗的研究方向提供了理论基础。     

PD-L1表达调控通路-治疗肿瘤潜在的新途径

癌细胞表面能表达多种免疫抑制蛋白,程序性死亡分子受体1配体(programmed death ligand-1,PD-L1)是关键蛋白之一,可与免疫细胞(如T细胞、B细胞、树突状细胞和自然杀伤性T细胞)表面的程序性死亡受体-1(programmed death ligand,PD-1)结合,激活PD-1的免疫抑制作用,通过RAS/Raf/MEK/ERK、磷脂酶C-γ(phospholipase C-γ,PLC-γ)、磷脂酰肌醇-3-激酶-蛋白激酶B(PI3K-AKT)等通路下调机体免疫细胞功能,协助癌细胞进行免疫逃逸。故近年来应用免疫检查点PD-1、PD-L1抑制剂成为治疗恶性肿瘤的新手段。研究表明,PD-L1的表达受多种信号通路、相关蛋白和转录因子的调控,故本文就PD-L1的表达调控进行综述,寻求PD-L1表达调控通路能否作为抗肿瘤治疗新的靶点。     

PDCD5在自身免疫性疾病中的调控作用及其机制

程序性细胞死亡分子5(programmed cell death 5,PDCD5)是PDCD家族的重要成员之一,具有多种生物学活性,如程序性细胞死亡、细胞周期、胚胎发育以及免疫调节等.PDCD5的表达受多种因素调控,能够通过PDCD5-TIP60-FOXP3途径促进调节性T细胞功能.临床研究证实PDCD5在多种自身免疫...     

程序性细胞死亡机制的研究进展

细胞是生物体最基本的结构单位和功能单位,细胞死亡对于多细胞生物的发育和稳态极为重要,也是生命的基本过程之一。目前认为细胞死亡形式主要分为两大类:非程序性细胞死亡(non-programmed cell death,NPCD)即坏死(necrosis);程序性细胞死亡(programmed cell death,PCD)。PCD与坏死不同,组织内无可见的炎症反应,无死亡细胞的溶解。程序性细胞死亡按其发生机制的不同可以分为凋亡(apoptosis)、自吞噬性程序性细胞死亡(autophagic cell death)、类凋亡/副凋亡(paraptosis)、细胞有丝分裂灾难(mitotic catastrophe)、胀亡(oncosis)、焦亡(pyroptosis)、胞质自切(autoschizis)、细胞程序性坏死(necroptosis)、细胞侵入性死亡(entosis)、铁死亡(ferroptosis)等。近年来,程序性细胞死亡在肿瘤发生发展中的作为成为研究热点,所以对程序性细胞死亡机制的研究至关重要,本文将对各类型程序性细胞死亡的机制做简要综述。     

PD-1相关免疫调节应用的研究进展

程序性细胞死亡因子1(programmed cell death 1,PD-1)是一种共刺激分子,属于CD28家族,呈诱导性表达于活化的T细胞、B细胞和NK细胞表面,与其配体作用传递抑制性信号,发挥负向调控作用,这一信号通路在自身免疫性疾病、肿瘤发生、慢性病毒感染中具有重要的生物学意义。通过研究PD-1及其配体与临床疾病的相关性,阐明其作用机理后,利用信号调节可以达到维持自身耐受、抑制肿瘤、抗病毒和提高机体免疫应答等免疫治疗的目的。本文对PD-1及其配体的生物学功能,免疫治疗等方面的进展进行回顾。     

诺贝尔奖工作回顾细胞凋亡的分子机制及其在当前医学中的应用——2002年诺贝尔生理学或医学奖工作介绍及研究进展

细胞凋亡(apoptosis)或程序性细胞死亡(programmed cell death,PCD)是指在一定的条件下,细胞遵循固定的程序,自己结束生命的过程[1].从细胞功能上看,一个多细胞生物体中,在正常条件下,某些细胞的死亡是细胞个体发育的一个阶段(最后阶段).     

果蝇蜕皮激素诱导程序性细胞死亡的遗传调控因子

近年来关于果蝇程序性细胞死亡（programmed cell death, PCD）的研究结果表明,在果蝇的变态发育过程中,蜕皮激素与受体结合后诱导转录因子的表达。这些转录因子作为程序性细胞死亡调控网络中的初、次级应答信号,激活凋亡诱导因子Reaper、Hid和Grim的表达。Reaper、Hid和Grim进而阻止凋亡蛋白抑制因子的活性,从而启动半胱氨酸蛋白酶caspase途径,引起细胞凋亡（apoptosis）。该文综述了蜕皮激素诱导的果蝇程序性细胞死亡中各遗传调控因子之间的关系。     

PD-L1表达及其调控在肿瘤治疗中作用的研究进展

程序性死亡蛋白1(programmed cell death 1, PD-1)及其配体PD-L1(programmed death 1 ligand 1)是重要的免疫检查点，二者相互作用可负性调节效应T细胞活化与增殖，也是肿瘤细胞逃避免疫监视的重要途径。阻断PD-1与PD-L1的结合，可以解除肿瘤细胞或抗原提呈细胞对T细胞的抑制，恢复其对肿瘤细胞的识别和杀伤能力。然而，PD-L1的表达受到复杂的调控且在不同的肿瘤中呈现出差异，其主要发生在遗传、转录和转录后水平。本综述介绍PD-L1表达的调控过程及其在肿瘤免疫治疗中的作用，结合这些调控机制实现对不同特征肿瘤进行精准免疫治疗是下一步研究的重点，在肿瘤治疗中具有重要意义。     

程序性细胞死亡分子5(PDCD5)研究进展

程序性细胞死亡分子5(programmed cell death 5,PDCD5)在人体各种组织中广泛存在,可以通过多种凋亡通路促进细胞凋亡,其在大部分肿瘤中低表达,对肿瘤化疗具有增敏效应.近年发现,除了在细胞凋亡过程中发挥作用外,PDCD5在多种疾病的病理进程中发挥重要作用,如:肿瘤、自身免疫性疾病、炎症性疾病、脑缺...     

PD-1/PD-L1 immune checkpoint: Potential target for cancer therapy

Recent studies show that cancer cells are sometimes able to evade the host immunity in the tumor microenvironment. Cancer cells can express high levels of immune inhibitory signaling proteins. One of the most critical checkpoint pathways in this system is a tumor-induced immune suppression (immune checkpoint) mediated by the programmed cell death protein 1 (PD-1) and its ligand, programmed death ligand 1 (PD-L1). PD-1 is highly expressed by activated T cells, B cells, dendritic cells, and natural killer cells, whereas PD-L1 is expressed on several types of tumor cells. Many studies have shown that blocking the interaction between PD-1 and PD-L1 enhances the T-cell response and mediates antitumor activity. In this review, we highlight a brief overview of the molecular and biochemical events that are regulated by the PD-1 and PD-L1 interaction in various cancers.     

Deubiquitinating enzyme OTUB1 promotes cancer cell immunosuppression via preventing ER-associated degradation of immune checkpoint protein PD-L1

Upregulation of programmed death ligand 1 (PD-L1) helps tumor cells escape from immune surveillance, and therapeutic antibodies targeting PD-1/PD-L1 have shown better patient outcomes only in several types of malignancies. Recent studies suggest that the clinical efficacy of anti-PD-1/PD-L1 treatments is associated with PD-L1 levels; however, the underlying mechanism of high PD-L1 protein levels in cancers is not well defined. Here, we report that the deubiquitinase OTUB1 positively regulates PD-L1 stability and mediates cancer immune responses through the PD-1/PD-L1 axis. Mechanistically, we demonstrate that OTUB1 interacts with and removes K48-linked ubiquitin chains from the PD-L1 intracellular domain in a manner dependent on its deubiquitinase activity to hinder the degradation of PD-L1 through the ERAD pathway. Functionally, depletion of OTUB1 markedly decreases PD-L1 abundance, reduces PD-1 protein binding to the tumor cell surface, and causes increased tumor cell sensitivity to human peripheral blood mononuclear cells (PBMCs)-mediated cytotoxicity. Meanwhile, OTUB1 ablation-induced PD-L1 destabilization facilitates more CD8⁺ T cells infiltration and increases the level of IFN-γ in serum to enhance antitumor immunity in mice, and the tumor growth suppression by OTUB1 silencing could be reversed by PD-L1 overexpression. Furthermore, we observe a significant correlation between PD-L1 abundance and OTUB1 expression in human breast carcinoma. Our study reveals OTUB1 as a deubiquitinating enzyme that influences cancer immunosuppression via regulation of PD-L1 stability and may be a potential therapeutic target for cancer immunotherapy.Subject terms: Proteins, Immune evasion     

Is it true that gut microbiota is considered as panacea in cancer therapy?

Recent studies demonstrated that a combination of the gut microbiome has the vital effect on the efficacy of anticancer immune therapies. Regulatory effects of microbiota have been shown in different types of cancer therapies such as chemotherapy and immunotherapy. Immune-checkpoint-blocked therapies are the recent efficient cancer immunotherapy strategies. The target of immune-checkpoint blocking is cytotoxic T lymphocyte protein-4 (CTLA-4) or blockade of programmed death-1 (PD-1) protein and its ligand programmed death ligand 1 (PD-L1) that they have been considered as cancer immunotherapy in recent years. In the latest studies, it have been demonstrated that several gut bacteria such as Akkermansia muciniphila, Bifidobacterium spp., Faecalibacterium spp., and Bacteroides fragilis have the regulatory effects on PD-1, PD-L1, and CTLA-4 blocked anticancer therapy outcome.     

Increased Level of Myeloid-Derived Suppressor Cells,Programmed Death Receptor Ligand 1/Programmed Death Receptor 1, and Soluble CD25 in Sokal High Risk Chronic Myeloid Leukemia

Immunotherapy (eg interferon α) in combination with tyrosine kinase inhibitors is currently in clinical trials for treatment of chronic myeloid leukemia (CML). Cancer patients commonly have problems with so called immune escape mechanisms that may hamper immunotherapy. Hence, to study the function of the immune system in CML is of interest. In the present paper we have identified immune escape mechanisms in CML with focus on those that directly hamper T cells since these cells are important to control tumor progression. CML patient samples were investigated for the presence of myeloid-derived suppressor cells (MDSCs), expression of programmed death receptor ligand 1/programmed death receptor 1 (PD-L1/PD-1), arginase 1 and soluble CD25. MDSC levels were increased in samples from Sokal high risk patients (p<0,05) and the cells were present on both CD34 negative and CD34 positive cell populations. Furthermore, expression of the MDSC-associated molecule arginase 1, known to inhibit T cells, was increased in the patients (p = 0,0079). Myeloid cells upregulated PD-L1 (p<0,05) and the receptor PD-1 was present on T cells. However, PD-L1 blockade did not increase T cell proliferation but upregulated IL-2 secretion. Finally, soluble CD25 was increased in high risk patients (p<0,0001). In conclusion T cells in CML patients may be under the control of different immune escape mechanisms that could hamper the use of immunotherapy in these patients. These escape mechanisms should be monitored in trials to understand their importance and how to overcome the immune suppression.     

Implication of the hepatokine,fibrinogen-like protein 1 in liver diseases,metabolic disorders and cancer: The need to harness its full potential

Fibrinogen-like protein 1 (FGL1) is a novel hepatokine that forms part of the fibrinogen superfamily. It is predominantly expressed in the liver under normal physiological conditions. When the liver is injured by external factors, such as chemical drugs and radiation, FGL1 acts as a protective factor to promote the growth of regenerated cells. However, elevated hepatic FGL1 under high fat conditions can cause lipid accumulation and inflammation, which in turn trigger the development of non-alcoholic fatty liver disease, diabetes, and obesity. FGL1 is also involved in the regulation of insulin resistance in adipose tissues and skeletal muscles as a means of communication between the liver and other tissues. In addition, the abnormally changed FGL1 levels in the plasma of cancer patients make it a potential predictor of cancer incidence in clinical practice. FGL1 was recently identified as a major functional ligand of the immune inhibitory receptor, lymphocyte-activation gene 3 (LAG3), thus making it a promising target for cancer immunotherapy except for the classical programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) axis. Despite the potential of FGL1 as a new cancer biomarker and therapeutic target, there are few related studies and much of what has been reported are superficial and lack depth and particularity. Therefore, elucidating the role and underlying mechanisms of FGL1 could be crucial for the development of promising diagnostic and therapeutic strategies for related diseases. Here, we provide a comprehensive review of the cellular mechanisms and clinical prospects of FGL1 in the prevention and treatment of liver diseases, metabolic disorders and cancer, and proffer suggestions for future studies.     

New insights into checkpoint inhibitor immunotherapy and its combined therapies in hepatocellular carcinoma: from mechanisms to clinical trials

Hepatocellular carcinoma (HCC) is one of the most lethal tumors in China and worldwide, although first-line therapies for HCC, such as atezolizumab and bevacizumab, have been effective with good results, the researches on new therapies have attracted much attention. With the deepening research on tumor immunology, the role and operation mechanism of immune cells in the tumor microenvironment (TME) of HCC have been explained, such as programmed cell death protein 1 (PD-1) binding to ligand could cause T cell exhaustion and reduce IFN-γ T cell secretion, cytotoxic T lymphocyte 4 (CTLA-4) and CD28 mediate immunosuppression by competing for B7 protein and disrupting CD28 signal transduction pathway, which also lays the foundation for the development and application of more new immune checkpoint inhibitors (ICIs). The biological behavior of various immune checkpoints has been proved in HCC, such as PD-1, programmed cell death ligand 1 (PD-L1), CTLA-4 and so on, leading to a series of clinical trials. Currently, FDA approved nivolumab, pembrolizumab and nivolumab plus ipilimumab for the treatment of HCC. However, the treatment of ICI has the disadvantages of low response rate and many side effects, so the combination of ICIs and various other therapies (such as VEGF or VEGFR inhibition, neoadjuvant and adjuvant therapy, locoregional therapies) has been derived. Further studies on immune checkpoint mechanisms may reveal new therapeutic targets and new combination therapies in the future.     

The role of exosomal PD-L1 in tumor immunotherapy

Exosomes are bioactive lipid bilayer vesicles released by most cells to mediate intercellular signal communication. Tumor cells release exosomes transmitting signals cell-to-cell and between cells and organs, which will promote tumor angiogenesis, regulate tumor stromal response, immune response, and enhance tumor cells resistance, while exosomes-derived from immune cells in tumor microenvironment play a key role in inhibiting tumor growth and killing tumor cells. Programmed cell death protein 1 (PD-1) combined with Programmed cell death protein ligand 1(PD-L1) can inhibit the activation of T cells, for tumor cells achieve immune escape by overexpressing PD-L1 and binding PD-1 on T cells. The use of anti-PD-1 / PD-L1 antibodies prevents their binding to a certain extent and partially restores T cell's activity. This article mainly discusses the role of exosomal PD-L1 in tumor progression and therapeutic efficacy after application of clinical antibodies, as well as the relation between different reactivity and immunity set points in cancer patients of different races, with different types and at different stages. Besides, we propose that exosomal PD-L1 may become targets for anti-PD-1 / PD-L1 antibody therapy, biomarkers for liquid biopsy, and drug carriers.     

Programmed death ligand-1 over-expression correlates with malignancy and contributes to immune regulation in ovarian cancer

The programmed death-1 (PD-1) pathway is important in the maintenance of peripheral tolerance and homeostasis through suppression of T cell receptor signaling. As such, it is employed by many tumors as a means of immune escape. We have investigated the role of this pathway in human ovarian cancer (OC) to assess its potential role as a diagnostic and/or prognostic marker and therapeutic target, following recent clinical trial success of antibody therapy directed at this pathway. We show programmed death ligand-1 (PD-L1) expression on monocytes in the ascites and blood of patients with malignant OC is strikingly higher than those with benign/borderline disease, with no overlap in the values between these groups. We characterize the regulation of this molecule and show a role of IL-10 present in ascitic fluid. Flow cytometric analysis of T cells present in the ascites and blood showed a correlation of PD-1 expression with malignant tumors versus benign/borderline, in a similar manner to PD-L1 expression on monocytes. Finally, we demonstrate functional links between PD-L1 expression on monocytes and OC tumor cells with suppression of T cell responses. Overall, we present data based on samples obtained from women with ovarian cancer, suggesting the PD-1 pathway may be used as a reliable diagnostic marker in OC, as well as a viable target for use with PD-1/PD-L1-directed antibody immunotherapy.     

New insights into the important roles of tumor cell-intrinsic PD-1

PD-1 (Programmed cell death protein-1) is mainly expressed in various immune cells, while its ligands PD-L1/PD-L2 (Programmed death ligand-1/Programmed death ligand-2) are mostly expressed in tumor cells. Generally, the binding of PD-L1/PD-L2 and PD-1 could lead to the tumor immune evasion. However, some recent studies showed that PD-1 could also be expressed in tumor cells and could activate mTOR (Mammalian Target of Rapamycin) or Hippo signaling pathway, therefore facilitating tumor proliferation independent of the immune system. While there was evidence that tumor cell-intrinsic PD-1 inhibited the activation of AKT and ERK1/2 pathways, thereby inhibiting tumor cell growth. Based on TCGA and CCLE database, we found that PD-1 was expressed in a variety of tumors and was associated with patient''s prognosis. Besides, we found that PD-1 may be involved in many carcinogenic signaling pathway on the basis of PD-1 gene enrichment analysis of cancer tissues and cancer cells. Our understanding of the tumor cell-intrinsic PD-1 function is still limited. This review is aimed at elaborating the potential effects of tumor cell-intrinsic PD-1 on carcinogenesis, providing a novel insight into the effects of anti-PD-1/PD-L1 immunotherapy, and helping to open a major epoch of combination therapy.