RESUMO
Targeting immune receptors on T cells is a common strategy to treat cancer and autoimmunity. Frequently, this is accomplished through monoclonal antibodies targeting the ligand binding sites of stimulatory or inhibitory co-receptors. Blocking ligand binding prevents downstream signalling and modulates specific T cell functions. Since 1985, the FDA has approved over 100 monoclonal antibodies against immune receptors. This therapeutic approach significantly improved the care of patients with numerous immune-related conditions; however, many patients are unresponsive, and some develop immune-related adverse events. One reason for that is the lack of consideration for the localization of these receptors on the cell surface of the immune cells in the context of the immune synapse. In addition to blocking ligand binding, changing the location of these receptors on the cell surface within the different compartments of the immunological synapse could serve as an alternative, efficient, and safer approach to treating these patients. This review discusses the potential therapeutic advantages of altering proteins' localization within the immune synapse and summarizes published work in this field. It also discusses the novel use of bispecific antibodies to induce the clustering of receptors on the cell surface. It presents the rationale for developing novel antibodies, targeting the organization of signalling receptor complexes on the cell surface. This approach offers an innovative and emerging technology to treat cancer patients resistant to current immunotherapies.
RESUMO
Programmed cell death protein 1 (PD-1) is an inhibitory receptor on T lymphocytes that is critical for modulating adaptive immunity. As such, it has been successfully exploited for cancer immunotherapy. Programmed death ligand 1 (PD-L1) and PD-L2 are ligands for PD-1; the former is ubiquitously expressed in inflamed tissues, whereas the latter is restricted to antigen-presenting cells. PD-L2 binds to PD-1 with 3-fold stronger affinity compared with PD-L1. To date, this affinity discrepancy has been attributed to a tryptophan (W110PD-L2) that is unique to PD-L2 and has been assumed to fit snuggly into a pocket on the PD-1 surface. Contrary to this model, using surface plasmon resonance to monitor real-time binding of recombinantly-expressed and -purified proteins, we found that W110PD-L2 acts as an "elbow" that helps shorten PD-L2 engagement with PD-1 and therefore lower affinity. Furthermore, we identified a "latch" between the C and D ß-strands of the binding face as the source of the PD-L2 affinity advantage. We show that the 3-fold affinity advantage of PD-L2 is the consequence of these two opposing features, the W110PD-L2 "elbow" and a C-D region "latch." Interestingly, using phylogenetic analysis, we found that these features evolved simultaneously upon the emergence of placental mammals, suggesting that PD-L2-affinity tuning was part of the alterations to the adaptive immune system required for placental gestation.
Assuntos
Antígeno B7-H1/química , Placenta/metabolismo , Proteína 2 Ligante de Morte Celular Programada 1/química , Sequência de Aminoácidos , Animais , Antígeno B7-H1/genética , Antígeno B7-H1/metabolismo , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD4-Positivos/metabolismo , Proliferação de Células , Feminino , Humanos , Ligantes , Ativação Linfocitária , Camundongos , Mutagênese Sítio-Dirigida , Filogenia , Gravidez , Proteína 2 Ligante de Morte Celular Programada 1/classificação , Proteína 2 Ligante de Morte Celular Programada 1/genética , Proteína 2 Ligante de Morte Celular Programada 1/metabolismo , Ligação Proteica , Domínios Proteicos , Estrutura Terciária de Proteína , Alinhamento de Sequência , Eletricidade EstáticaRESUMO
Programmed cell death protein 1 (PD-1) is a critical inhibitory receptor that limits excessive T cell responses. Cancer cells have evolved to evade these immunoregulatory mechanisms by upregulating PD-1 ligands and preventing T cell-mediated anti-tumor responses. Consequently, therapeutic blockade of PD-1 enhances T cell-mediated anti-tumor immunity, but many patients do not respond and a significant proportion develop inflammatory toxicities. To improve anti-cancer therapy, it is critical to reveal the mechanisms by which PD-1 regulates T cell responses. We performed global quantitative phosphoproteomic interrogation of PD-1 signaling in T cells. By complementing our analysis with functional validation assays, we show that PD-1 targets tyrosine phosphosites that mediate proximal T cell receptor signaling, cytoskeletal organization, and immune synapse formation. PD-1 ligation also led to differential phosphorylation of serine and threonine sites within proteins regulating T cell activation, gene expression, and protein translation. In silico predictions revealed that kinase/substrate relationships engaged downstream of PD-1 ligation. These insights uncover the phosphoproteomic landscape of PD-1-triggered pathways and reveal novel PD-1 substrates that modulate diverse T cell functions and may serve as future therapeutic targets. These data are a useful resource in the design of future PD-1-targeting therapeutic approaches.
Assuntos
Adesão Celular , Imunidade Celular/imunologia , Fosfoproteínas/metabolismo , Receptor de Morte Celular Programada 1/metabolismo , Proteoma/análise , Receptores de Antígenos de Linfócitos T/metabolismo , Linfócitos T/imunologia , Citocinas/metabolismo , Humanos , Ligantes , Ativação Linfocitária , Fosforilação , Transdução de Sinais , Linfócitos T/metabolismo , Ativação TranscricionalRESUMO
Ligation of the inhibitory receptor PD-1 on T cells results in the inhibition of numerous cellular functions. Despite the overtly inhibitory outcome of PD-1 signalling, there are additionally a collection of functions that are activated. We have observed that CD4+ T cells stimulated through the T-cell receptor and PD-1 primarily do not proliferate; however, there is a population of cells that proliferates more than T-cell receptor stimulation alone. These highly proliferating cells could potentially be associated with PD-1-blockade unresponsiveness in patients. In this study, we have performed RNA sequencing and found that following PD-1 ligation proliferating and non-proliferating T cells have distinct transcriptional signatures. Remarkably, the proliferating cells showed an enrichment of genes associated with an activated state despite PD-1 signalling. Additionally, circulating follicular helper T cells were significantly more prevalent in the non-proliferating population, demonstrated by enrichment of the associated genes CXCR5, CCR7, TCF7, BCL6 and PRDM1 and validated at the protein level. Translationally, we also show that there are more follicular helper T cells in patients that respond favourably to PD-1 blockade. Overall, the presence of transcriptionally and functionally distinct T cell populations responsive to PD-1 ligation may provide insights into the clinical differences observed following therapeutic PD-1 blockade.
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Linfócitos T CD4-Positivos/imunologia , Receptor de Morte Celular Programada 1/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Subpopulações de Linfócitos T/imunologia , Transcriptoma/imunologia , Linfócitos T CD4-Positivos/metabolismo , Proliferação de Células/genética , Células Cultivadas , Conjuntos de Dados como Assunto , Humanos , Imunofenotipagem , Ativação Linfocitária/genética , Cultura Primária de Células , RNA-Seq , Análise de Célula Única , Subpopulações de Linfócitos T/metabolismoRESUMO
Platelet-bound complement activation products (PC4d) are associated with thrombosis in Systemic Lupus Erythematosus (SLE). This study investigated the effect of PC4d on platelet function, as a mechanistic link to arterial thrombosis. In a cohort of 150 SLE patients, 13 events had occurred within five years of enrollment. Patients with arterial events had higher PC4d levels (13.6 [4.4-24.0] vs. 4.0 [2.5-8.3] net MFI), with PC4d 10 being the optimal cutoff for event detection. The association of arterial events with PC4d remained significant after adjusting for antiphospholipid status, smoking, and prednisone use (p = 0.045). PC4d levels correlated with lower platelet counts (r = -0.26, p = 0.002), larger platelet volumes (r = 0.22, p = 0.009) and increased platelet aggregation: the adenosine diphosphate (ADP) concentration to achieve 50% maximal aggregation (EC50) was lower in patients with PC4d 10 compared with PC4d < 10 (1.6 vs. 3.7, p = 0.038, respectively). These results suggest that PC4d may be a mechanistic marker for vascular disease in SLE.
Assuntos
Plaquetas/metabolismo , Ativação do Complemento/imunologia , Complemento C4/imunologia , Lúpus Eritematoso Sistêmico/complicações , Lúpus Eritematoso Sistêmico/metabolismo , Ativação Plaquetária/genética , Doenças Vasculares/etiologia , Difosfato de Adenosina/metabolismo , Autoanticorpos/imunologia , Autoimunidade , Biomarcadores , Plaquetas/imunologia , Complemento C4/metabolismo , Suscetibilidade a Doenças , Humanos , Lúpus Eritematoso Sistêmico/imunologia , Ativação Plaquetária/imunologia , Agregação Plaquetária , Contagem de Plaquetas , Trombose/etiologia , Trombose/metabolismo , Doenças Vasculares/metabolismoRESUMO
Programmed cell death-1 (PD-1) is an essential inhibitory receptor in T cells. Antibodies targeting PD-1 elicit durable clinical responses in patients with multiple tumor indications. Nevertheless, a significant proportion of patients do not respond to anti-PD-1 treatment, and a better understanding of the signaling pathways downstream of PD-1 could provide biomarkers for those whose tumors respond and new therapeutic approaches for those whose tumors do not. We used affinity purification mass spectrometry to uncover multiple proteins associated with PD-1. Among these proteins, signaling lymphocytic activation molecule-associated protein (SAP) was functionally and mechanistically analyzed for its contribution to PD-1 inhibitory responses. Silencing of SAP augmented and overexpression blocked PD-1 function. T cells from patients with X-linked lymphoproliferative disease (XLP), who lack functional SAP, were hyperresponsive to PD-1 signaling, confirming its inhibitory role downstream of PD-1. Strikingly, signaling downstream of PD-1 in purified T cell subsets did not correlate with PD-1 surface expression but was inversely correlated with intracellular SAP levels. Mechanistically, SAP opposed PD-1 function by acting as a molecular shield of key tyrosine residues that are targets for the tyrosine phosphatase SHP2, which mediates PD-1 inhibitory properties. Our results identify SAP as an inhibitor of PD-1 function and SHP2 as a potential therapeutic target in patients with XLP.
Assuntos
Pontos de Checagem do Ciclo Celular/fisiologia , Espectrometria de Massas/métodos , Receptor de Morte Celular Programada 1/metabolismo , Família de Moléculas de Sinalização da Ativação Linfocitária/metabolismo , Linfócitos T/metabolismo , Animais , Biomarcadores Tumorais , Proliferação de Células/fisiologia , Citocinas/genética , Citocinas/metabolismo , Regulação Enzimológica da Expressão Gênica , Inativação Gênica , Células HEK293 , Humanos , Células Jurkat , Masculino , Camundongos , Camundongos Knockout , Receptor de Morte Celular Programada 1/genética , Proteína Tirosina Fosfatase não Receptora Tipo 11/genética , Proteína Tirosina Fosfatase não Receptora Tipo 11/metabolismo , Família de Moléculas de Sinalização da Ativação Linfocitária/genéticaRESUMO
T cell co-stimulation is important for the maintenance of immunologic tolerance. Co-inhibitory receptors including programmed cell death-1 (PD-1) confer peripheral tolerance to prevent autoimmunity. SAP (SH2D1A) is an adaptor molecule that is important in T cell signaling and has been shown to interact with signaling lymphocytic activation molecule (SLAM) family receptors also in the context of self-tolerance. We recently reported that SAP interferes with PD-1 function. In the current study, we investigated the levels of SAP and PD-1 in patients with rheumatoid arthritis (RA) to further understand what role they play in disease activity. We observed increased SAP levels in lymphocytes of RA patients and found that PD-1 levels correlated positively with RA disease activity. Additionally, we found that SAP interacts with CD28 to inhibit T cell signaling in vitro. This work demonstrates a putative molecular mechanism for SAP mediated PD-1 inhibition.
Assuntos
Artrite Reumatoide/imunologia , Antígenos CD28/metabolismo , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Proteína Associada à Molécula de Sinalização da Ativação Linfocitária/metabolismo , Linfócitos T/imunologia , Adulto , Idoso , Artrite Reumatoide/genética , Artrite Reumatoide/patologia , Autoimunidade/genética , Autoimunidade/fisiologia , Linhagem Celular Tumoral , Feminino , Humanos , Células Jurkat , Masculino , Pessoa de Meia-Idade , Fosforilação , Receptor de Morte Celular Programada 1/metabolismo , Proteína Associada à Molécula de Sinalização da Ativação Linfocitária/genética , Adulto JovemRESUMO
Programmed cell death 1 (PD-1) is a major coinhibitory receptor and a member of the immunological synapse (IS). To uncover proteins that regulate PD-1 recruitment to the IS, we searched for cytoskeleton-related proteins that also interact with PD-1 using affinity purification mass spectrometry. Among these proteins, EF hand domain family member D2 (EFHD2), a calcium binding adaptor protein, was functionally and mechanistically analyzed for its contribution to PD-1 signaling. EFHD2 was required for PD-1 to inhibit cytokine secretion, proliferation, and adhesion of human T cells. Interestingly, EFHD2 was also required for human T cell-mediated cytotoxicity and for mounting an antitumor immune response in a syngeneic murine tumor model. Mechanistically, EFHD2 contributed to IS stability, lytic vesicles trafficking, and granzyme B secretion. Altogether, EFHD2 is an important regulator of T cell cytotoxicity and further studies should evaluate its role in T cell-mediated inflammation.
Assuntos
Proteínas de Ligação ao Cálcio/imunologia , Linfócitos T Citotóxicos/imunologia , Animais , Humanos , Sinapses Imunológicas/imunologia , CamundongosRESUMO
Regulation of integrins is critical for lymphocyte adhesion to endothelium and migration throughout the body. Inside-out signaling to integrins is mediated by the small GTPase Ras-proximate-1 (Rap1). Using an RNA-mediated interference screen, we identified phospholipase Cε 1 (PLCε1) as a crucial regulator of stromal cell-derived factor 1 alpha (SDF-1α)-induced Rap1 activation. We have shown that SDF-1α-induced activation of Rap1 is transient in comparison with the sustained level following cross-linking of the antigen receptor. We identified that PLCε1 was necessary for SDF-1α-induced adhesion using shear stress, cell morphology alterations, and crawling on intercellular adhesion molecule 1 (ICAM-1)-expressing cells. Structure-function experiments to separate the dual-enzymatic function of PLCε1 uncover necessary contributions of the CDC25, Pleckstrin homology, and Ras-associating domains, but not phospholipase activity, to this pathway. In the mouse model of delayed type hypersensitivity, we have shown an essential role for PLCε1 in T-cell migration to inflamed skin, but not for cytokine secretion and proliferation in regional lymph nodes. Our results reveal a signaling pathway where SDF-1α induces T-cell adhesion through activation of PLCε1, suggesting that PLCε1 is a specific potential target in treating conditions involving migration of T cells to inflamed organs.
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Quimiocina CXCL12/genética , Inflamação/genética , Fosfoinositídeo Fosfolipase C/genética , Proteínas de Ligação a Telômeros/genética , Animais , Adesão Celular/genética , Adesão Celular/imunologia , Movimento Celular/genética , Movimento Celular/imunologia , Quimiocina CXCL12/imunologia , Humanos , Inflamação/imunologia , Inflamação/patologia , Molécula 1 de Adesão Intercelular/imunologia , Linfócitos/imunologia , Linfócitos/patologia , Camundongos , Fosfoinositídeo Fosfolipase C/imunologia , Receptores de Antígenos/genética , Receptores de Antígenos/imunologia , Complexo Shelterina , Transdução de Sinais , Linfócitos T/imunologia , Linfócitos T/patologia , Proteínas de Ligação a Telômeros/imunologia , ras-GRF1/imunologiaRESUMO
Exosomes are cell-derived vesicles that have been implicated in the pathogenesis of many inflammatory diseases. More specifically, it has been shown that T cell-derived exosomes can induce immunological responses; however, little is known about the mechanism and the molecular content of these vesicles. Here, we used a proteomic approach to characterize human T cell-derived exosomes. We found that specific proteins of the RAS signaling pathway were enriched in exosomes derived from activated T cells, and that these vesicles induced ERK phosphorylation in recipient immune cells. Our findings support a mechanistic role of exosomes in cellular activation, and further studies should consider exosomes as a biomarker for inflammatory diseases.
Assuntos
Exossomos/metabolismo , Sistema de Sinalização das MAP Quinases/fisiologia , Transdução de Sinais/fisiologia , Linfócitos T/metabolismo , Proteínas ras/metabolismo , Biomarcadores/metabolismo , Humanos , Ativação Linfocitária/fisiologia , Fosforilação/fisiologia , Proteômica/métodosRESUMO
BACKGROUND: The mechanism by which mast cells (MCs) are activated in T cell-mediated inflammatory processes remains elusive. Recently, we have shown that microvesicles derived from activated T cells (mvT*s) can stimulate MCs to degranulate and release several cytokines. OBJECTIVE: The aim of this study was to characterize the contribution of microRNAs (miRs) delivered by microvesicles to MC activation. METHODS: miR profiling was performed with NanoString technology and validated by using real-time PCR. The biological role of mvT* miR was verified by overexpression of miRs in MCs using mimic or inhibitory molecules and analyzing the effect on their predicted targets. RESULTS: mvT*s were found to downregulate the expression of the tyrosine phosphatase protein tyrosine phosphatase receptor type J (PTPRJ), a known extracellular signal-regulated kinase inhibitor. Bioinformatics analysis predicted that miR-4443 regulates the PTPRJ gene expression. Indeed, miR-4443, which was present in mvT*s, was also found to be overexpressed in human MCs stimulated with these MVs. α-Amanitin insensitivity confirmed that overexpression of miR-4443 was not due to transcriptional activation. The luciferase reporter assay indicated that the 3' untranslated region of PTPRJ was targeted by this miR. Transfection of MCs with mimic or inhibitor of miR-4443 resulted in decreased or enhanced PTPRJ expression, respectively. Furthermore, miR-4443 regulated extracellular signal-regulated kinase phosphorylation and IL-8 release in MCs activated by mvT*s. CONCLUSION: These results support a scenario by which T cell-derived microvesicles act as intercellular carriers of functional miR-4443, which might exert heterotypic regulation of PTPRJ gene expression in MCs, leading to their activation in the context of T cell-mediated inflammatory processes.
Assuntos
Mastócitos/imunologia , MicroRNAs/imunologia , Linfócitos T/imunologia , Micropartículas Derivadas de Células/imunologia , Micropartículas Derivadas de Células/metabolismo , Células Cultivadas , Regulação da Expressão Gênica/imunologia , Humanos , Inflamação/imunologia , Inflamação/metabolismo , Mastócitos/metabolismo , Proteínas Tirosina Fosfatases Classe 3 Semelhantes a Receptores/biossínteseRESUMO
PURPOSE OF REVIEW: With the advent of cancer immunotherapy and immune checkpoint inhibitors, patients with malignancies can now achieve durable remissions for conditions previously described as terminal. However, immune-related adverse events (irAEs) associated with cancer immunotherapy have become an anticipated consequence of enhanced T cell activation. Through an extensive literature review, we assess the most recent clinical and basic research data concerning immune checkpoint blockade and describe the spectrum of associated irAEs as well as their management. RECENT FINDINGS: Anti-PD-1, anti-PD-L1, and anti-CTLA-4 antibodies are widely used in the management of an array of tumors with incredible clinical remissions. However, irAEs cause significant morbidity and mortality and in some cases, result in withdrawal of cancer therapy and initiation of immunosuppression. While this is an exciting time in oncology, irAEs are a barrier to adequate care and therefore deserve close attention and improved capacity to predict and prevent toxicity. Rheumatologists should be familiar with these topics in the eventuality of patient evaluation and management.
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Antineoplásicos Imunológicos/efeitos adversos , Neoplasias/tratamento farmacológico , Antineoplásicos Imunológicos/uso terapêutico , HumanosRESUMO
Ras and Rap proteins are closely related small guanosine triphosphatase (GTPases) that share similar effector-binding domains but operate in a very different signaling networks; Ras has a dominant role in cell proliferation, while Rap mediates cell adhesion. Ras and Rap proteins are regulated by several shared processes such as post-translational modification, phosphorylation, activation by guanine exchange factors and inhibition by GTPase-activating proteins. Sub-cellular localization and trafficking of these proteins to and from the plasma membrane are additional important regulatory features that impact small GTPases function. Despite its importance, the trafficking mechanisms of Ras and Rap proteins are not completely understood. Chaperone proteins play a critical role in trafficking of GTPases and will be the focus of the discussion in this work. We will review several aspects of chaperone biology focusing on specificity toward particular members of the small GTPase family. Understanding this specificity should provide key insights into drug development targeting individual small GTPases.
Assuntos
Chaperonas Moleculares/metabolismo , Transdução de Sinais , Proteínas rap de Ligação ao GTP/metabolismo , Proteínas ras/metabolismo , Animais , Anti-Inflamatórios/farmacologia , Sistemas de Liberação de Medicamentos , Humanos , Chaperonas Moleculares/antagonistas & inibidores , Processamento de Proteína Pós-Traducional , Proteínas ras/químicaRESUMO
Regulation of integrins is critical for lymphocyte adhesion to endothelium and trafficking through secondary lymphoid organs. Inside-out signaling to integrins is mediated by the small GTPase Rap1. Two effectors of Rap1 regulate integrins, RapL and Rap1 interacting adaptor molecule (RIAM). Using mice conditionally deficient in both Rap1a and Rap1b and mice null for RIAM, we show that the Rap1/RIAM module is not required for T- or B-cell development but is essential for efficient adhesion to intercellular adhesion molecule (ICAM) 1 and vascular cell adhesion molecule (VCAM) 1 and for proper trafficking of lymphocytes to secondary lymphoid organs. Interestingly, in RIAM-deficient mice, whereas peripheral lymph nodes (pLNs) were depleted of both B and T cells and recirculating B cells were diminished in the bone barrow (BM), the spleen was hypercellular, albeit with a relative deficiency of marginal zone B cells. The abnormality in lymphocyte trafficking was accompanied by defective humoral immunity to T-cell-dependent antigens. Platelet function was intact in RIAM-deficient animals. These in vivo results confirm a role for RIAM in the regulation of some, but not all, leukocyte integrins and suggest that RIAM-regulated integrin activation is required for trafficking of lymphocytes from blood into pLNs and BM, where relatively high shear forces exist in high endothelial venules and sinusoids, respectively.
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Proteínas Adaptadoras de Transdução de Sinal/imunologia , Linfócitos B/imunologia , Quimiotaxia de Leucócito/imunologia , Proteínas de Membrana/imunologia , Linfócitos T/imunologia , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Linfócitos B/citologia , Linfócitos B/metabolismo , Adesão Celular/imunologia , Integrinas/metabolismo , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Linfócitos T/citologia , Linfócitos T/metabolismo , Proteínas rap1 de Ligação ao GTP/imunologia , Proteínas rap1 de Ligação ao GTP/metabolismoRESUMO
To limit excessive T cell-mediated inflammatory responses, the immune system has a milieu of inhibitory receptors, called immune checkpoints. Cancer cells have evolved to seize those inhibitory pathways and to prevent T cell-mediated killing of tumor cells. Therefore, immune checkpoint inhibitors (ICI) consisting of blocking antibodies against these receptors present an exciting avenue in the fight against cancer. The last decade has seen the implementation of ICI against a variety of cancer indications that have improved the overall anti-tumor responses and patient survival. However, inflammatory toxicities and autoimmunity are a significant adverse event of ICI therapies. In this review, we will discuss the biology of immune checkpoints, highlight research strategies that may help reduce the incidence of immune-related adverse events associated with ICI therapies, and also suggest investigational approaches to manipulate immune checkpoints to treat primary autoimmune disorders.
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Autoimunidade/imunologia , Pontos de Checagem do Ciclo Celular/imunologia , Neoplasias/imunologia , Linfócitos T/imunologia , Humanos , ImunoterapiaRESUMO
CD28 is a coreceptor expressed on T lymphocytes. Signaling downstream of CD28 promotes multiple T cell functions such as proliferation, survival, and cytokine secretion. Adhesion to APCs is another function of T cells; however, little is known with regard to the role of CD28 in this process. Our previous studies have shown that CD28 inhibits T cell adhesion, but the underlying mechanism that mediates this process remains unknown. In the present study we discovered that signaling downstream of CD28 resulted in inhibition of Rap1 activity and decreased LFA-1-mediated adhesion. We showed that this was regulated by the recruitment of calcium-promoted Ras inactivator (CAPRI), a GTPase-activating protein, to the plasma membrane downstream of CD28 signaling. CAPRI trafficking to the plasma membrane was secondary to calcium influx and was mediated by its C2A and C2B domains. We conclude that CD28 inhibits Rap1-mediated adhesion by recruiting the protein CAPRI to the plasma membrane.
Assuntos
Antígenos CD28/imunologia , Membrana Celular/imunologia , Linfócitos T/imunologia , Proteínas Ativadoras de ras GTPase/imunologia , Animais , Sítios de Ligação/genética , Antígenos CD28/metabolismo , Cálcio/imunologia , Cálcio/metabolismo , Adesão Celular/imunologia , Membrana Celular/metabolismo , Células Cultivadas , Feminino , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Confocal , Transporte Proteico/imunologia , Transdução de Sinais/imunologia , Linfócitos T/metabolismo , Proteínas rap1 de Ligação ao GTP/imunologia , Proteínas rap1 de Ligação ao GTP/metabolismo , Proteínas Ativadoras de ras GTPase/genética , Proteínas Ativadoras de ras GTPase/metabolismoRESUMO
Programmed death-1 (PD-1) is a co-receptor that is expressed predominantly by T cells. The binding of PD-1 to its ligands, PD-L1 or PD-L2, is vital for the physiologic regulation of the immune system. A major functional role of the PD-1 signaling pathway is the inhibition of self-reactive T cells, which serve to protect against autoimmune diseases. Elimination of the PD-1 pathway can therefore result in the breakdown of immune tolerance that can ultimately lead to the development of pathogenic autoimmunity. Conversely, tumor cells can at times co-opt the PD-1 pathway to escape from immunosurveillance mechanisms. Therefore, blockade of the PD-1 pathway has become an attractive target in cancer therapy. Recent clinical trials have shown that anti-PD-1 agents have profound effects on solid tumor regression. Current approaches include six agents that are either PD-1 and PD-L1 targeted neutralizing antibodies or fusion proteins. More than forty clinical trials are underway to better define the role of PD-1 blockade in variety of tumor types. In this review we will highlight the basic biology of the PD-1 system and discuss its potential roles in both autoimmunity and cancer. We propose that future research on PD-1 may lead to the translation of fundamental regulatory pathways into the development of practical new approaches for the treatment of autoimmune diseases and cancer.
Assuntos
Autoimunidade , Neoplasias/imunologia , Neoplasias/metabolismo , Receptor de Morte Celular Programada 1/metabolismo , Transdução de Sinais , Animais , Doenças Autoimunes/tratamento farmacológico , Doenças Autoimunes/genética , Doenças Autoimunes/imunologia , Doenças Autoimunes/metabolismo , Linfócitos B/imunologia , Linfócitos B/metabolismo , Doenças Transmissíveis/tratamento farmacológico , Doenças Transmissíveis/genética , Doenças Transmissíveis/imunologia , Doenças Transmissíveis/metabolismo , Humanos , Ligantes , Neoplasias/genética , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Receptor de Morte Celular Programada 1/genética , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismoRESUMO
BACKGROUND: Granulomatous mastitis is an uncommon chronic inflammatory breast condition that is characterized by granulomatous inflammation. Granulomatous mastitis presents a challenging clinical scenario, because it can mimic carcinoma. The etiology and optimal treatment remain unclear. We report our experience with granulomatous mastitis patients who presented to our clinic within the past 2 years and describe their response to our treatment modalities. METHODS: Our clinic records were reviewed for the diagnosis of granulomatous mastitis. Charts were used to collect clinical data, patients were reinter viewed, and physicians completed detailed reports on their management of these cases. All cases were diagnosed with granulomatous mastitis based on histological findings and by ruling out other etiologies. RESULTS: Twenty-four patients were identified. The mean age was 34 years. Fifty-three percent of our patients emigrated from Mexico. Most patients were treated with prednisone and/or methotrexate with overall response rate greater than 80 %. Cases that failed to improve were treated with other modalities, including antituberculosis drugs. CONCLUSIONS: Granulomatous mastitis remains a difficult entity to diagnose and to treat. The clinical course of patients often is prolonged. Exclusion of other causes of granulomatous conditions is essential before initiating anti-inflammatory treatment.
Assuntos
Anti-Inflamatórios/uso terapêutico , Antituberculosos/uso terapêutico , Mastite Granulomatosa/diagnóstico , Mastite Granulomatosa/tratamento farmacológico , Metotrexato/uso terapêutico , Prednisona/uso terapêutico , Adulto , Diagnóstico Diferencial , Quimioterapia Combinada , Feminino , Seguimentos , Mastite Granulomatosa/terapia , Hospitais Públicos , Humanos , Mastectomia , Pessoa de Meia-Idade , New York , Estudos Retrospectivos , Sucção , Resultado do TratamentoRESUMO
Ras activation as a consequence of antigen receptor (T-cell receptor; TCR) engagement on T lymphocytes is required for T-cell development, selection and function. Lymphocyte function-associated antigen-1 (LFA-1) mediates lymphocyte adhesion, stabilization of the immune synapse and bidirectional signalling. Using a fluorescent biosensor we found that TCR activation with or without costimulation of CD28 led to activation of Ras only on the Golgi apparatus, whereas costimulation with LFA-1 induced Ras activation on both the Golgi and the plasma membrane. Ras activation on both compartments required RasGRP1, an exchange factor regulated by calcium and diacylglycerol (DAG), but phospholipase C (PLC) activity was required only for activation on the Golgi. Engagement of LFA-1 increased DAG levels at the plasma membrane by stimulating phospholipase D (PLD). PLD2 and phosphatidic acid phosphatase (PAP) were required for Ras activation on the plasma membrane. Thus, LFA-1 acts through PLD2 to reshape the pattern of Ras activation downstream of the TCR.
Assuntos
Membrana Celular/metabolismo , Antígeno-1 Associado à Função Linfocitária/metabolismo , Fosfolipase D/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Linfócitos T/metabolismo , Proteínas ras/metabolismo , Animais , Antígenos CD28/metabolismo , Comunicação Celular/fisiologia , Proteínas de Ligação a DNA/metabolismo , Diglicerídeos/metabolismo , Ativação Enzimática/fisiologia , Complexo de Golgi/metabolismo , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Humanos , Células Jurkat , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transdução de Sinais/fisiologia , Fosfolipases Tipo C/metabolismoRESUMO
Targeting immune checkpoint receptors on T cells is a common cancer treatment strategy. Frequently, this is accomplished through antibodies targeting the ligand of inhibitory co-receptors. Blocking the immune checkpoint PD-1 binding to its ligands PD-L1 and PD-L2 prevents downstream signaling and enhances anti-tumor T cell responses. This approach improves cancer patients' outcomes. However, only one-third of the patients respond to these treatments. To better understand the mechanism of anti-PD-1 antibodies, we explored the location of PD-1 within the immune synapse. Surprisingly, we discovered that anti-PD-1 antibodies, besides blocking the interaction between PD-1 and its ligands, also removed PD-1 from the synapse. We demonstrated a correlation between removing PD-1 from the synapse by anti-PD-1 antibodies and the extent of T cell activation. Interestingly, a short version of the anti-PD-1 antibody, F(ab')2, failed to remove PD-1 from the synapse and activate T cells. Using the syngeneic tumor model, we showed a superior anti-tumor effect of the anti-PD-1 antibody over the shorter version of the same antibody. Our data indicate that anti-PD-1 antibodies activate T cells by removing PD-1 from the synapse, and changing the location of PD-1 or other immune receptors within the immune synapse could serve as an alternative, efficient approach to treat cancer.