RESUMO
Activated Vγ9Vδ2 (γδ2) T lymphocytes that sense parasite-produced phosphoantigens are expanded in Plasmodium falciparum-infected patients. Although previous studies suggested that γδ2 T cells help control erythrocytic malaria, whether γδ2 T cells recognize infected red blood cells (iRBCs) was uncertain. Here we show that iRBCs stained for the phosphoantigen sensor butyrophilin 3A1 (BTN3A1). γδ2 T cells formed immune synapses and lysed iRBCs in a contact, phosphoantigen, BTN3A1 and degranulation-dependent manner, killing intracellular parasites. Granulysin released into the synapse lysed iRBCs and delivered death-inducing granzymes to the parasite. All intra-erythrocytic parasites were susceptible, but schizonts were most sensitive. A second protective γδ2 T cell mechanism was identified. In the presence of patient serum, γδ2 T cells phagocytosed and degraded opsonized iRBCs in a CD16-dependent manner, decreasing parasite multiplication. Thus, γδ2 T cells have two ways to control blood-stage malaria-γδ T cell antigen receptor (TCR)-mediated degranulation and phagocytosis of antibody-coated iRBCs.
Assuntos
Antígenos de Protozoários/imunologia , Citotoxicidade Imunológica , Eritrócitos/imunologia , Linfócitos Intraepiteliais/imunologia , Ativação Linfocitária , Malária Falciparum/imunologia , Fagocitose , Plasmodium falciparum/microbiologia , Antígenos CD/metabolismo , Antígenos de Diferenciação de Linfócitos T/metabolismo , Antígenos de Protozoários/sangue , Boston , Brasil , Butirofilinas/metabolismo , Células Cultivadas , Eritrócitos/metabolismo , Eritrócitos/parasitologia , Feminino , Granzimas/metabolismo , Interações Hospedeiro-Parasita , Humanos , Sinapses Imunológicas/metabolismo , Sinapses Imunológicas/parasitologia , Linfócitos Intraepiteliais/metabolismo , Linfócitos Intraepiteliais/parasitologia , Malária Falciparum/sangue , Malária Falciparum/parasitologia , Masculino , Plasmodium falciparum/crescimento & desenvolvimentoAssuntos
Proliferação de Células , Sinapses Imunológicas/imunologia , Ativação Linfocitária , Linfócitos do Interstício Tumoral/imunologia , Neoplasias/imunologia , Linfócitos T/imunologia , Animais , Humanos , Inibidores de Checkpoint Imunológico/uso terapêutico , Sinapses Imunológicas/efeitos dos fármacos , Sinapses Imunológicas/metabolismo , Sinapses Imunológicas/patologia , Linfócitos do Interstício Tumoral/efeitos dos fármacos , Linfócitos do Interstício Tumoral/metabolismo , Linfócitos do Interstício Tumoral/patologia , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Neoplasias/patologia , Transdução de Sinais , Linfócitos T/efeitos dos fármacos , Linfócitos T/metabolismo , Linfócitos T/patologia , Viroses/tratamento farmacológico , Viroses/imunologia , Viroses/metabolismo , Viroses/patologiaRESUMO
hScrib and hDlg belong to the PDZ family of proteins. Since the identification of these highly phylogenetically conserved scaffolds, an increasing amount of experiments has elucidated the roles of hScrib and hDlg in a variety of cell functions. Remarkably, their participation during the establishment of polarity in epithelial cells is well documented. Although the role of both proteins in the immune system is scantly known, it has become a growing field of investigation. Here, we summarize the interactions and functions of hScrib and hDlg1, which participate in diverse functions involving cell polarization in immune cells, and discuss their relevance in the immune cell biology. The fundamental role of hScrib and hDlg1 during the establishment of the immunological synapse, hence T cell activation, and the recently described role of hScrib in reactive oxygen species production in macrophages and of hDlg1 in cytokine production by dendritic cells highlight the importance of both proteins in immune cell biology. The expression of these proteins in other leukocytes can be anticipated and needs to be confirmed. Due to their multiple interaction domains, there is a wide range of possible interactions of hScrib and hDlg1 that remains to be explored in the immune system.
Assuntos
Polaridade Celular/imunologia , Células Dendríticas/imunologia , Proteína 1 Homóloga a Discs-Large/metabolismo , Macrófagos/imunologia , Proteínas de Membrana/metabolismo , Linfócitos T/imunologia , Proteínas Supressoras de Tumor/metabolismo , Citocinas/metabolismo , Células Dendríticas/metabolismo , Humanos , Imunidade Celular , Sinapses Imunológicas/imunologia , Sinapses Imunológicas/metabolismo , Ativação Linfocitária/imunologia , Macrófagos/metabolismo , Espécies Reativas de Oxigênio , Linfócitos T/metabolismoRESUMO
The immunological synapse (IS) is an intercellular communication platform, organized at the contact site of two adjacent cells, where at least one is an immune cell. Functional IS formation is fundamental for the modulation of the most relevant immune system activities, such as T cell activation by antigen presenting cells and T cell/natural killer (NK) cell-mediated target cell (infected or cancer) killing. Extensive evidence suggests that connexins, in particular connexin-43 (Cx43) hemichannels and/or gap junctions, regulate signaling events in different types of IS. Although the underlying mechanisms are not fully understood, the current evidence suggests that Cx43 channels could act as facilitators for calcium ions, cyclic adenosine monophosphate, and/or adenosine triphosphate uptake and/or release at the interface of interacting cells. These second messengers have relevant roles in the IS signaling during dendritic cell-mediated T and NK cell activation, regulatory T cell-mediated immune suppression, and cytotoxic T lymphocyte or NK cell-mediated target tumor cell killing. Additionally, as the cytoplasmic C-terminus domain of Cx43 interacts with a plethora of proteins, Cx43 may act as scaffolds for integration of various regulatory proteins at the IS, as suggested by the high number of Cx43-interacting proteins that translocate at these cell-cell interface domains. In this review, we provide an updated overview and analysis on the role and possible underlying mechanisms of Cx43 in IS signaling.
Assuntos
Conexina 43/metabolismo , Sinapses Imunológicas/metabolismo , Animais , Células Dendríticas/imunologia , Humanos , Mapas de Interação de Proteínas , Transdução de Sinais , Linfócitos T/imunologiaRESUMO
The capacity of B lymphocytes to produce specific antibodies, particularly broadly neutralizing antibodies that provide immunity to viral pathogens has positioned them as valuable therapeutic targets for immunomodulation. To become competent as antibody secreting cells, B cells undergo a series of activation steps, which are triggered by the recognition of antigens frequently displayed on the surface of other presenting cells. Such antigens elicit the formation of an immune synapse (IS), where local cytoskeleton rearrangements coupled to mechanical forces and membrane trafficking orchestrate the extraction and processing of antigens in B cells. In this review, we discuss the molecular mechanisms that regulate polarized membrane trafficking and mechanical properties of the immune synapse, as well as the potential extracellular cues from the environment, which may impact the ability of B cells to sense and acquire antigens at the immune synapse. An integrated view of the diverse cellular mechanisms that shape the immune synapse will provide a better understanding on how B cells are efficiently activated.
Assuntos
Antígenos/metabolismo , Linfócitos B/metabolismo , Membrana Celular/metabolismo , Polaridade Celular , Animais , Humanos , Sinapses Imunológicas/metabolismo , Transporte ProteicoRESUMO
The thymus supports differentiation of T cell precursors. This process requires relocation of developing thymocytes throughout multiple microenvironments of the organ, mainly with thymic epithelial cells (TEC), which control intrathymic T cell differentiation influencing the formation and maintenance of the immunological synapse. In addition to the proteins of the major histocompatibility complex (MHC), this structure is supported by several adhesion molecules. During the process of thymopoiesis, we previously showed that laminin-mediated interactions are involved in the entrance of T-cell precursors into the thymus, as well as migration of differentiating thymocytes within the organ. Using small interference RNA strategy, we knocked-down the ITGA6 gene (which encodes the CD49f integrin α-chain) in cultured human TEC, generating a decrease in the expression of the corresponding CD49f subunit, in addition to modulation in several other genes related to cell adhesion and migration. Thymocyte adhesion to TEC was significantly impaired, comprising both immature and mature thymocyte subsets. Moreover, we found a modulation of the MHC, with a decrease in membrane expression of HLA-ABC, in contrast with increase in the expression of HLA-DR. Interestingly, the knockdown of the B2M gene (encoding the ß-2 microglobulin of the HLA-ABC complex) increased CD49f expression levels, thus unraveling the existence of a cross-talk event in the reciprocal control of CD49f and HLA-ABC. Our data suggest that the expression levels of CD49f may be relevant in the general control of MHC expression by TEC and consequently the corresponding synapse with developing thymocytes mediated by the T-cell receptor.
Assuntos
Moléculas de Adesão Celular/metabolismo , Células Epiteliais/metabolismo , Epitélio/metabolismo , Sinapses Imunológicas/metabolismo , Integrina alfa6/genética , Adesão Celular/fisiologia , Diferenciação Celular/fisiologia , Movimento Celular/fisiologia , Matriz Extracelular/metabolismo , Marcação de Genes/métodos , Humanos , Integrinas/metabolismoRESUMO
Gap junction (GJ) mediates intercellular communication through linked hemichannels from each of two adjacent cells. Using human and mouse models, we show that connexin 43 (Cx43), the main GJ protein in the immune system, was recruited to the immunological synapse during T cell priming as both GJs and stand-alone hemichannels. Cx43 accumulation at the synapse was Ag specific and time dependent, and required an intact actin cytoskeleton. Fluorescence recovery after photobleaching and Cx43-specific inhibitors were used to prove that intercellular communication between T cells and dendritic cells is bidirectional and specifically mediated by Cx43. Moreover, this intercellular cross talk contributed to T cell activation as silencing of Cx43 with an antisense or inhibition of GJ docking impaired intracellular Ca(2+) responses and cytokine release by T cells. These findings identify Cx43 as an important functional component of the immunological synapse and reveal a crucial role for GJs and hemichannels as coordinators of the dendritic cell-T cell signaling machinery that regulates T cell activation.
Assuntos
Conexina 43/imunologia , Junções Comunicantes/imunologia , Sinapses Imunológicas/imunologia , Ativação Linfocitária/imunologia , Linfócitos T/imunologia , Animais , Comunicação Celular/imunologia , Separação Celular , Conexina 43/metabolismo , Citometria de Fluxo , Imunofluorescência , Junções Comunicantes/metabolismo , Humanos , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional , Sinapses Imunológicas/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microscopia Confocal , Receptor Cross-Talk/imunologia , Transdução de Sinais/imunologia , Linfócitos T/metabolismoRESUMO
As part of the innate immune response NK cells destroy infected, transformed, or otherwise stressed cells within hours of activation. In contrast, CD4(+) T lymphocytes require a sustained increase in their metabolism in order to cope with the biogenesis of cell components, in a process of proliferation and differentiation into effector cells. Recently, mitochondria have been implied in T lymphocyte immune synapse function but little is known on the role of mitochondria in the NK cell interaction with tumour cells. Here we analysed NK cells mitochondrial membrane potential (Deltapsi(m)) as an indicator of mitochondrial energy status and cellular homeostasis. Upon contact with K562 tumour cells, NK cells undergo Deltapsi(m) depolarization, indicating a rapid consumption of their metabolic energy. Furthermore, pharmacological inhibition of ATP synthesis down-regulates NK cell cytotoxic activity. Confocal- and electron-microscopy analyses showed re-organization of NK cells mitochondria towards the site of interaction with K562 tumour cell (NK cell immune synapse), perhaps as a way to compensate for local energy consumption. Interestingly, mitochondrial re-organization also takes place following NK stimulation with anti-NKGD2 antibodies but not with anti-KIR2DL1 antibodies, suggesting that activating rather than inhibiting cell signalling, triggered by NK cell receptors, is involved in NK cell mitochondria dynamics.