RESUMO
Nicotinic acid adenine dinucleotide 2'-phosphate (NAADP) is a naturally occurring nucleotide that has been shown to be involved in the release of Ca2+ from intracellular stores in a wide variety of cell types, tissues and organisms. Current evidence suggests that NAADP may function as a trigger to initiate a Ca2+ signal that is then amplified by other Ca2+ release mechanisms. A fundamental question that remains unanswered is the identity of the NAADP receptor. Our recent studies have identified HN1L/JPT2 as a high affinity NAADP binding protein that is essential for the modulation of Ca2+ channels.
Assuntos
Canais de Cálcio/imunologia , Sinalização do Cálcio/imunologia , Cálcio/imunologia , Proteínas Associadas aos Microtúbulos/imunologia , NADP/análogos & derivados , Animais , Humanos , NADP/imunologiaRESUMO
Polyethyleneimine (PEI) induced immune responses were investigated in human bronchial epithelial (hBE) cells and mice. PEI rapidly induced ATP release from hBE cells and pretreatment with glutathione (GSH) blocked the response. PEI activated two conductive pathways, VDAC-1 and pannexin 1, which completely accounted for ATP efflux across the plasma membrane. Moreover, PEI increased intracellular Ca2+ concentration ([Ca2+]i), which was reduced by the pannexin 1 inhibitor, 10Panx (50 µM), the VDAC-1 inhibitor, DIDS (100 µM), and was nearly abolished by pretreatment with GSH (5 mM). The increase in [Ca2+]i involved Ca2+ uptake through two pathways, one blocked by oxidized ATP (oATP, 300 µM) and another that was blocked by the TRPV-1 antagonist A784168 (100 nM). PEI stimulation also increased IL-33 mRNA expression and protein secretion. In vivo experiments showed that acute (4.5 h) PEI exposure stimulated secretion of Th2 cytokines (IL-5 and IL-13) into bronchoalveolar lavage (BAL) fluid. Conjugation of PEI with ovalbumin also induced eosinophil recruitment and secretion of IL-5 and IL-13 into BAL fluid, which was inhibited in IL-33 receptor (ST2) deficient mice. In conclusion, PEI-induced oxidative stress stimulated type 2 immune responses by activating ATP-dependent Ca2+ uptake leading to IL-33 secretion, similar to allergens derived from Alternaria.
Assuntos
Trifosfato de Adenosina/imunologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/imunologia , Imunidade/efeitos dos fármacos , Nanopartículas/administração & dosagem , Estresse Oxidativo/efeitos dos fármacos , Polietilenoimina/farmacologia , Alérgenos/imunologia , Animais , Cálcio/imunologia , Células Cultivadas , Citocinas/imunologia , Feminino , Humanos , Imunidade/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Estresse Oxidativo/imunologia , RNA Mensageiro/imunologia , Mucosa Respiratória/efeitos dos fármacos , Mucosa Respiratória/imunologiaRESUMO
Transglutaminase 2 (TG2) is a ubiquitously expressed enzyme catalyzing the crosslinking between Gln and Lys residues and involved in various pathophysiological events. Besides this crosslinking activity, TG2 functions as a deamidase, GTPase, isopeptidase, adapter/scaffold, protein disulfide isomerase, and kinase. It also plays a role in the regulation of hypusination and serotonylation. Through these activities, TG2 is involved in cell growth, differentiation, cell death, inflammation, tissue repair, and fibrosis. Depending on the cell type and stimulus, TG2 changes its subcellular localization and biological activity, leading to cell death or survival. In normal unstressed cells, intracellular TG2 exhibits a GTP-bound closed conformation, exerting prosurvival functions. However, upon cell stimulation with Ca2+ or other factors, TG2 adopts a Ca2+-bound open conformation, demonstrating a transamidase activity involved in cell death or survival. These functional discrepancies of TG2 open form might be caused by its multifunctional nature, the existence of splicing variants, the cell type and stimulus, and the genetic backgrounds and variations of the mouse models used. TG2 is also involved in the phagocytosis of dead cells by macrophages and in fibrosis during tissue repair. Here, we summarize and discuss the multifunctional and controversial roles of TG2, focusing on cell death/survival and fibrosis.
Assuntos
Aminoaciltransferases/genética , Carbono-Nitrogênio Liases/genética , Fibrose/enzimologia , Proteínas de Ligação ao GTP/genética , Inflamação/enzimologia , Isomerases de Dissulfetos de Proteínas/genética , Transglutaminases/genética , Processamento Alternativo , Aminoaciltransferases/imunologia , Animais , Cálcio/imunologia , Cálcio/metabolismo , Carbono-Nitrogênio Liases/imunologia , Morte Celular , Sobrevivência Celular , Fibrose/genética , Fibrose/imunologia , Fibrose/patologia , Proteínas de Ligação ao GTP/imunologia , Expressão Gênica , Guanosina Trifosfato/imunologia , Guanosina Trifosfato/metabolismo , Humanos , Inflamação/genética , Inflamação/imunologia , Inflamação/patologia , Isoenzimas/genética , Isoenzimas/imunologia , Macrófagos/enzimologia , Macrófagos/imunologia , Fagocitose/genética , Isomerases de Dissulfetos de Proteínas/imunologia , Proteína 2 Glutamina gama-Glutamiltransferase , Transglutaminases/imunologiaRESUMO
Cytotoxic T lymphocytes (CTLs) are key effector cells in the immune response against viruses and cancers, killing targets with high precision. Target cell recognition by CTL triggers rapid polarization of intracellular organelles toward the synapse formed with the target cell, delivering cytolytic granules to the immune synapse. Single amino acid changes within peptides binding MHC class I (pMHCs) are sufficient to modulate the degree of killing, but exactly how this impacts the choreography of centrosome polarization and granule delivery to the target cell remains poorly characterized. Here we use 4D imaging and find that the pathways orchestrating killing within CTL are conserved irrespective of the signal strength. However, the rate of initiation along these pathways varies with signal strength. We find that increased strength of signal leads to an increased proportion of CTLs with prolonged dwell times, initial Ca2+ fluxes, centrosome docking, and granule polarization. Hence, TCR signal strength modulates the rate but not organization of effector CTL responses.
Assuntos
Linfócitos T Citotóxicos/imunologia , Animais , Cálcio/imunologia , Células Cultivadas , Centrossomo/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transdução de Sinais/imunologia , Sinapses/imunologiaRESUMO
Pseudomonas aeruginosa is a frequent cause of hospital-acquired wound infection and is difficult to treat because it forms biofilms and displays antibiotic resistance. Previous studies in mice demonstrated that mast cells (MCs) not only contribute to P. aeruginosa eradication but also promote wound healing via an unknown mechanism. We recently reported that host defense peptides (HDPs) induce human MC degranulation via Mas-related G protein-coupled receptor-X2 (MRGPRX2). Small molecule HDP mimetics have distinct advantages over HDPs because they are inexpensive to synthesize and display high stability, bioavailability, and low toxicity. Murepavadin is a lipidated HDP mimetic, (also known as POL7080), which displays antibacterial activity against a broad panel of multi-drug-resistant P. aeruginosa. We found that murepavadin induces Ca2+ mobilization, degranulation, chemokine IL-8 and CCL3 production in a human MC line (LAD2 cells) endogenously expressing MRGPRX2. Murepavadin also caused degranulation in RBL-2H3 cells expressing MRGPRX2 but this response was significantly reduced in cells expressing missense variants within the receptor's ligand binding (G165E) or G protein coupling (V282M) domains. Compound 48/80 induced ß-arrestin recruitment and promoted receptor internalization, which resulted in substantial decrease in the subsequent responsiveness to the MRGPRX2 agonist. By contrast, murepavadin did not cause ß-arrestin-mediated MRGPRX2 regulation. Murepavadin induced degranulation in mouse peritoneal MCs via MrgprB2 (ortholog of human MRGPRX2) and caused increased vascular permeability in wild-type mice but not in MrgprB2-/- mice. The data presented herein demonstrate that murepavadin activates human MCs via MRGPRX2 and murine MCs via MrgprB2 and that MRGPRX2 is resistant to ß-arrestin-mediated receptor regulation. Thus, besides its direct activity against P. aeruginosa, murepavadin may contribute to bacterial clearance and promote wound healing by harnessing MC's immunomodulatory property via the activation of MRGPRX2.
Assuntos
Antibacterianos/farmacologia , Mastócitos/efeitos dos fármacos , Proteínas do Tecido Nervoso/imunologia , Peptídeos Cíclicos/farmacologia , Receptores Acoplados a Proteínas G/imunologia , Receptores de Neuropeptídeos/imunologia , Animais , Cálcio/imunologia , Degranulação Celular/efeitos dos fármacos , Linhagem Celular , Citocinas/imunologia , Feminino , Humanos , Masculino , Mastócitos/imunologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , RatosRESUMO
Calmodulin (CaM) is a highly conserved second messenger protein transducing calcium signals by binding and modulating intracellular calcium ions (Ca2+), and involves in the Ca2+-dependent physical processes including host defense in vertebrates. In the present study, a CaM homologue (designated as CgCaM) was identified from Pacific oyster Crassostrea gigas. The open reading frame of CgCaM cDNA was of 471 bp encoding a polypeptide of 156 amino acid residues. There were four EFh domains predicted in CgCaM, which shared high homologies with those in CaMs from oyster C. virginica and other invertebrates. The mRNA transcripts of CgCaM were constitutively expressed in all the tested tissues including labellum, mantle, gonad, gills, adductor muscle, haemocytes and hepatopancreas, with the highest expression level in haemocytes. The mRNA expression level of CgCaM in haemocytes decreased significantly (0.31-fold of that in blank, p < 0.05) at 3 h after LPS stimulation, while the intracellular Ca2+ (1.57-fold of that in blank, p < 0.05) and the mRNA expression of cytokine CgIL17-1 (4.87-fold of that in blank, p < 0.05) both increased in haemocytes. Meanwhile, an oyster miRNA scaffold659_26519 was identified, and it was proved to target the 3'-untranslated regions (3'-UTR) of CgCaM mRNA by luciferase reporter assay. The expression of scaffold659_26519 increased significantly at 3 h (43.523-fold of that of blank, p < 0.05) and 6 h (55.91-fold of that of blank, p < 0.05) after LPS stimulation. When the expression of scaffold659_26519 was inhibited by transfection with its inhibitor in vitro, the expression of CgIL17-1 declined significantly to 0.58-fold of that in LPS stimulation group. These findings indicated that the miRNA scaffold659_26519 targeted CaM was involved in the early inflammatory response of oyster immunity, and provided a new evidence for CaM-mediated immune mechanism in molluscs.
Assuntos
Calmodulina/genética , Crassostrea/imunologia , Interleucina-17/genética , MicroRNAs/genética , Regiões 3' não Traduzidas , Sequência de Aminoácidos , Animais , Cálcio/imunologia , Calmodulina/imunologia , Crassostrea/genética , Expressão Gênica/imunologia , Hemócitos/efeitos dos fármacos , Hemócitos/imunologia , Interleucina-17/imunologia , Lipopolissacarídeos/imunologia , MicroRNAs/imunologia , Filogenia , RNA Mensageiro/genética , RNA Mensageiro/imunologia , Distribuição Tecidual/imunologiaRESUMO
Mitochondria, conserved intracellular organelles best known as the powerhouse of cells for generating ATP, play an important role in apoptosis. Oxidative stress can induce mitochondrial dysfunction and activate mitochondria-mediated apoptotic cell death. TRPM2 is a Ca2+-permeable cation channel that is activated by pathologically relevant concentrations of reactive oxygen species (ROS) and one of its well-recognized roles is to confer susceptibility to ROS-induced cell death. Increasing evidence from recent studies supports TRPM2 channel-mediated cell death as an important cellular mechanism linking miscellaneous oxidative stress-inducing pathological factors to associated diseased conditions. In this chapter, we will discuss the role of the TRPM2 channel in neurons in the brain and pancreatic ß-cells in mediating mitochondrial dysfunction and cell death, focusing mainly on apoptotic cell death, that are induced by pathological stimuli implicated in the pathogenesis of neurodegenerative diseases, ischemic stroke and diabetes.
Assuntos
Apoptose/imunologia , Diabetes Mellitus/imunologia , AVC Isquêmico/imunologia , Mitocôndrias/imunologia , Doenças Neurodegenerativas/imunologia , Estresse Oxidativo/imunologia , Canais de Cátion TRPM/imunologia , Animais , Cálcio/imunologia , Diabetes Mellitus/patologia , Humanos , Células Secretoras de Insulina/imunologia , Células Secretoras de Insulina/patologia , AVC Isquêmico/patologia , Mitocôndrias/patologia , Doenças Neurodegenerativas/patologia , Neurônios/imunologia , Neurônios/patologiaRESUMO
The population of regulatory T cells (Tregs) is critical for immunological self-tolerance and homeostasis. Proper ion regulation contributes to Treg lineage identity, regulation, and effector function. Identified ion channels include Ca2+ release-activated Ca2+, transient receptor potential, P2X, volume-regulated anion and K+ channels Kv1.3 and KCa3.1. Ion channel modulation represents a promising therapeutic approach for the treatment of autoimmune diseases such as rheumatoid arthritis and multiple sclerosis. This review summarizes studies with gene-targeted mice and pharmacological modulators affecting Treg number and function. Furthermore, participation of ion channels is illustrated and the power of future research possibilities is discussed.
Assuntos
Artrite Reumatoide/tratamento farmacológico , Cálcio/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Moduladores de Transporte de Membrana/farmacologia , Esclerose Múltipla/tratamento farmacológico , Linfócitos T Reguladores/efeitos dos fármacos , Animais , Artrite Reumatoide/genética , Artrite Reumatoide/imunologia , Artrite Reumatoide/metabolismo , Cálcio/imunologia , Canais de Cálcio Ativados pela Liberação de Cálcio/genética , Canais de Cálcio Ativados pela Liberação de Cálcio/imunologia , Sinalização do Cálcio , Modelos Animais de Doenças , Regulação da Expressão Gênica/imunologia , Humanos , Canais de Potássio Ativados por Cálcio de Condutância Intermediária/genética , Canais de Potássio Ativados por Cálcio de Condutância Intermediária/imunologia , Canal de Potássio Kv1.3/genética , Canal de Potássio Kv1.3/imunologia , Proteínas de Membrana/genética , Proteínas de Membrana/imunologia , Moduladores de Transporte de Membrana/química , Camundongos , Esclerose Múltipla/genética , Esclerose Múltipla/imunologia , Esclerose Múltipla/metabolismo , Receptores Purinérgicos P2X/genética , Receptores Purinérgicos P2X/imunologia , Receptores Purinérgicos P2X7/genética , Receptores Purinérgicos P2X7/imunologia , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/patologia , Canais de Potencial de Receptor Transitório/genética , Canais de Potencial de Receptor Transitório/imunologiaRESUMO
Accurate recognition of antigens by specific T cells is crucial for adaptive immunity to work properly. The activation of a T-cell antigen-specific response by an antigen-presenting cell (APC) has not been clearly measured at a single T-cell level. It is also unknown whether the cell-extrinsic environment alters antigen recognition by a T cell. To measure the activation probability of a single T cell by an APC, we performed a single-cell live imaging assay and found that the activation probability changes depending not only on the antigens but also on the interactions of other T cells with the APC. We found that the specific reactivity of single naïve T cells was poor. However, their antigen-specific reactivity increased drastically when attached to an APC interacting with activated T cells. Activation of T cells was suppressed when regulatory T cells interacted with the APC. These findings suggest that although the ability of APCs to activate an antigen-specific naïve T cell is low at a single-cell level, the surrounding environment of APCs improves the specificity of the bulk response.
Assuntos
Imunidade Adaptativa , Apresentação de Antígeno , Células Apresentadoras de Antígenos/imunologia , Cálcio/metabolismo , Linfócitos T Reguladores/imunologia , Animais , Células Apresentadoras de Antígenos/citologia , Bioensaio , Cálcio/imunologia , Técnicas de Cocultura , Humanos , Transporte de Íons , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , Probabilidade , Receptores de Antígenos de Linfócitos T/genética , Receptores de Antígenos de Linfócitos T/imunologia , Análise de Célula Única/métodos , Baço/citologia , Baço/imunologia , Linfócitos T Reguladores/citologiaRESUMO
Rheumatoid arthritis (RA) and psoriatic arthritis (PsA) are two distinct autoimmune diseases that manifest with chronic synovial inflammation. Here, we show that CD4+ T cells from patients with RA and PsA have increased expression of the pore-forming calcium channel component ORAI3, thereby increasing the activity of the arachidonic acid-regulated calcium-selective (ARC) channel and making T cells sensitive to arachidonic acid. A similar increase does not occur in T cells from patients with systemic lupus erythematosus. Increased ORAI3 transcription in RA and PsA T cells is caused by reduced IKAROS expression, a transcriptional repressor of the ORAI3 promoter. Stimulation of the ARC channel with arachidonic acid induces not only a calcium influx, but also the phosphorylation of components of the T cell receptor signaling cascade. In a human synovium chimeric mouse model, silencing ORAI3 expression in adoptively transferred T cells from patients with RA attenuates tissue inflammation, while adoptive transfer of T cells from healthy individuals with reduced expression of IKAROS induces synovitis. We propose that increased ARC activity due to reduced IKAROS expression makes T cells more responsive and contributes to chronic inflammation in RA and PsA.
Assuntos
Ácido Araquidônico/imunologia , Artrite Reumatoide/imunologia , Linfócitos T CD4-Positivos/imunologia , Membrana Sinovial/imunologia , Idoso , Artrite Psoriásica/genética , Artrite Psoriásica/imunologia , Artrite Reumatoide/genética , Cálcio/imunologia , Canais de Cálcio/genética , Canais de Cálcio/imunologia , Sinalização do Cálcio , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The mechanisms underlying Mycobacterium fortuitum-induced mycobacteriosis remain unexplored. Using head kidney macrophages (HKM) from catfish (Clarias gariepinus), we report that Ca2+ surge across mitochondrial-Ca2+ uniporter (MICU), and consequent mitochondrial ROS (mtROS) production, is imperative for mycobactericidal activity. Inhibition of mtROS alleviated HKM apoptosis and enhanced bacterial survival. Based on RNA interference (RNAi) and inhibitor studies, we demonstrate that the Toll-like receptor (TLR)-2-endoplasmic reticulum (ER) stress-store-operated calcium entry (SOCE) axis is instrumental for activating the mt-Ca2+/mtROS cascade in M. fortuitum-infected HKM. Additionally, pharmacological inhibition of mtROS attenuated the expression of CHOP, STIM1, and Orai1, which suggests a positive feedback loop between ER-stress-induced SOCE and mtROS production. Elevated tumor necrosis factor alpha (TNF-α) levels and caspase-8 activity were observed in HKM consequent to M. fortuitum infection, and our results implicate that mtROS is crucial in activating the TNF-mediated caspase-8 activation. Our results for the first time demonstrate mitochondria as an innate immune signaling center regulating mycobacteriosis in fish. We conclude that M. fortuitum-induced persistent SOCE signaling leads to mtROS production, which in turn activates the TNF-α/caspase-8 axis culminating in HKM apoptosis and bacterial clearance.
Assuntos
Cálcio/imunologia , Mitocôndrias/imunologia , Infecções por Mycobacterium não Tuberculosas/imunologia , Mycobacterium fortuitum/imunologia , Espécies Reativas de Oxigênio/imunologia , Receptor 2 Toll-Like/imunologia , Animais , Peixes-Gato , Rim Cefálico/imunologia , Rim Cefálico/microbiologia , Macrófagos/imunologia , Macrófagos/microbiologia , Transdução de Sinais/imunologiaRESUMO
The immunological synapse is a transient junction that occurs when the plasma membrane of a T cell comes in close contact with an APC after recognizing a peptide from the antigen-MHC. The interaction starts when CRAC channels embedded in the T cell membrane open, flowing calcium ions into the cell. To counterbalance the ion influx and subsequent depolarization, Kv 1.3 and KCa3.1 channels are recruited to the immunological synapse, increasing the extracellular K+ concentration. These processes are crucial as they initiate gene expression that drives T cell activation and proliferation. The T cell-specific function of the K2P channel family member TASK2 channels and their role in autoimmune processes remains unclear. Using mass spectrometry analysis together with epifluorescence and super-resolution single-molecule localization microscopy, we identified TASK2 channels as novel players recruited to the immunological synapse upon stimulation. TASK2 localizes at the immunological synapse, upon stimulation with CD3 antibodies, likely interacting with these molecules. Our findings suggest that, together with Kv 1.3 and KCa3.1 channels, TASK2 channels contribute to the proper functioning of the immunological synapse, and represent an interesting treatment target for T cell-mediated autoimmune disorders.
Assuntos
Sinapses Imunológicas/imunologia , Canais de Potássio de Domínios Poros em Tandem/imunologia , Animais , Doenças Autoimunes/imunologia , Complexo CD3/imunologia , Cálcio/imunologia , Linhagem Celular Tumoral , Membrana Celular/imunologia , Células Cultivadas , Feminino , Expressão Gênica/imunologia , Humanos , Canais de Potássio Ativados por Cálcio de Condutância Intermediária/imunologia , Células Jurkat , Canal de Potássio Kv1.3/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Linfócitos T/imunologiaRESUMO
Aging is an unstoppable process and begins shortly after birth. Each cell of the organism is affected by the irreversible process, not only with equal density but also at varying ages and with different speed. Therefore, aging can also be understood as an adaptation to a continually changing cellular environment. One of these very prominent changes in age affects Ca2+ signaling. Especially immune cells highly rely on Ca2+-dependent processes and a strictly regulated Ca2+ homeostasis. The intricate patterns of impaired immune cell function may represent a deficit or compensatory mechanisms. Besides, altered immune function through Ca2+ signaling can profoundly affect the development of age-related disease. This review attempts to summarize changes in Ca2+ signaling due to channels and receptors in T cells and beyond in the context of aging.
Assuntos
Envelhecimento/imunologia , Canais de Cálcio/imunologia , Sinalização do Cálcio/imunologia , Cálcio/imunologia , Homeostase/imunologia , Linfócitos T/imunologia , Animais , HumanosRESUMO
Calcium signals are initiated in immune cells by the process of store-operated calcium entry (SOCE), where receptor activation triggers transient calcium release from the endoplasmic reticulum, followed by opening of plasma-membrane calcium-release activated calcium (CRAC) channels. ORAI1, ORAI2, and ORAI3 are known to comprise the CRAC channel; however, the contributions of individual isoforms to neutrophil function are not well understood. Here, we show that loss of ORAI1 partially decreases calcium influx, while loss of both ORAI1 and ORAI2 completely abolishes SOCE. In other immune-cell types, loss of ORAI2 enhances SOCE. In contrast, we find that ORAI2-deficient neutrophils display decreased calcium influx, which is correlated with measurable differences in the regulation of neutrophil membrane potential via KCa3.1. Decreased SOCE in ORAI1-, ORAI2-, and ORAI1/2-deficient neutrophils impairs multiple neutrophil functions, including phagocytosis, degranulation, leukotriene, and reactive oxygen species (ROS) production, rendering ORAI1/2-deficient mice highly susceptible to staphylococcal infection. This study demonstrates that ORAI1 and ORAI2 are the primary components of the neutrophil CRAC channel and identifies subpopulations of neutrophils where cell-membrane potential functions as a rheostat to modulate the SOCE response. These findings have implications for mechanisms that modulate neutrophil function during infection, acute and chronic inflammatory conditions, and cancer.
Assuntos
Sinalização do Cálcio , Cálcio/imunologia , Neutrófilos/imunologia , Proteína ORAI1/imunologia , Proteína ORAI2/imunologia , Animais , Feminino , Canais de Potássio Ativados por Cálcio de Condutância Intermediária/genética , Canais de Potássio Ativados por Cálcio de Condutância Intermediária/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteína ORAI1/genética , Proteína ORAI2/genéticaRESUMO
Calcium plays an important role in regulating cell physiology and immune responses to various pathogens. Our recent work has highlighted the crucial role for calcium homeostasis in dendritic cells and macrophages during various infections. Here we investigated the effect of calcium homeostasis in regulating T cell activation and function during mycobacterial infection. Results show that calcium homeostasis had varied effects in regulating T cell activation and function during mycobacterial infection. This included regulation of the expression of co-stimulatory molecules, cytokine profiles and effector function. A net negative role for Voltage Gated Calcium Channel (VGCC) was observed. Inhibiting VGCC in mycobacteria primed T cells induced increased production of pro-inflammatory cytokines and an increased effector phenotype. Infected macrophages when incubated with VGCC inhibited T cells, induced increased expression of co-stimulatory molecule expression on macrophages, increased the production of pro-inflammatory cytokines and increased autophagy and apoptosis. This collectively led to reduced survival of mycobacteria inside macrophages. The data point towards a fine regulation of protective responses by routes of calcium influx and release that mediate pathogen survival or clearance.
Assuntos
Cálcio/metabolismo , Infecções por Mycobacterium/imunologia , Linfócitos T/metabolismo , Animais , Apoptose/imunologia , Autofagia/imunologia , Cálcio/imunologia , Canais de Cálcio/metabolismo , Citocinas/imunologia , Feminino , Homeostase , Interleucina-2/metabolismo , Ativação Linfocitária/imunologia , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Mycobacterium/patogenicidade , Mycobacterium tuberculosis/imunologia , Linfócitos T/fisiologia , Tuberculose/imunologiaRESUMO
HIV-associated neurocognitive disorder (HAND) is a collective term describing the spectrum of neurocognitive deficits that arise from HIV infection. Although the introduction to highly active antiretroviral therapy (HAART) has prolonged the lifespan of HIV patients, neurocognitive impairments remain prevalent, as patients are left perpetually with HIV. Currently, physicians face a challenge in treating HAND patients, so a greater understanding of the mechanisms underlying HAND pathology has been a growing focus in HIV research. Recent research has revealed the role disrupted calcium homeostasis in HIV-mediated neurotoxicity. Calcium plays a well-established role in the crosstalk between the mitochondrion and ER as well as in regulating autophagy, and ER stress, mitochondrial dysfunction, and impaired autophagic activity are considered hallmarks in several neurodegenerative and neurocognitive disorders. Therefore, it is paramount that the intricate inter-organelle signaling in relation to calcium homeostasis during HIV infection and the development of HAND is elucidated. This review consolidates current knowledge regarding the neuropathology of neurocognitive disorders and HIV infection with a focus on the underlying role of calcium during ER stress, mitochondrial dysfunction, and autophagy associated with the progression of HAND. The details of this intricate crosstalk during HAND remain relatively unknown; further research in this field can potentially aid in the development of improved therapy for patients suffering from HAND.
Assuntos
Autofagia/genética , Cálcio/metabolismo , Disfunção Cognitiva/metabolismo , Retículo Endoplasmático/metabolismo , Infecções por HIV/metabolismo , Homeostase/genética , Mitocôndrias/metabolismo , Fármacos Anti-HIV/uso terapêutico , Terapia Antirretroviral de Alta Atividade , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Astrócitos/virologia , Autofagia/imunologia , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/virologia , Cálcio/imunologia , Canais de Cálcio Tipo L/genética , Canais de Cálcio Tipo L/metabolismo , Disfunção Cognitiva/tratamento farmacológico , Disfunção Cognitiva/virologia , Retículo Endoplasmático/genética , Estresse do Retículo Endoplasmático/genética , Estresse do Retículo Endoplasmático/imunologia , Regulação da Expressão Gênica , Infecções por HIV/tratamento farmacológico , Infecções por HIV/virologia , Homeostase/imunologia , Humanos , Mitocôndrias/genética , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/virologia , Receptores de N-Metil-D-Aspartato/genética , Receptores de N-Metil-D-Aspartato/metabolismo , Transdução de SinaisRESUMO
Interleukin-33 (IL-33) is a member of the IL-1 cytokine family and plays critical roles in facilitating type-2 immune responses. IL-33 is localized in the nucleus and released to the extracellular milieu during cell death, although the precise mechanisms underlying IL-33 mobilization remain unclear. Here, we found that nigericin, a toxin derived from Streptomyces hygroscopicus, promoted IL-33 translocation from the nucleus to the cytosol before extracellular release. This translocation was inhibited by chelating Ca2+ with EGTA or membrane protection by glycine treatment. Ca2+ ionophore A23187 stimulation caused IL-33 translocation to the cytoplasm but was not sufficient for extracellular release. However, IL-33 release was induced by detergent treatment, which indicates that membrane rupture is required for IL-33 release. The pore-forming pyroptosis executor gasdermin D was cleaved following nigericin stimulation, and overexpression of the cleaved gasdermin D-N-terminal fragment that forms the membrane pore sufficiently induced IL-33 release, which was blocked by EGTA and glycine. Together, these findings suggest that Ca2+-dependent signals and gasdermin D pore formation are required for robust IL-33 production.
Assuntos
Cálcio/imunologia , Interleucina-33/imunologia , Nigericina/imunologia , Streptomyces/imunologia , Animais , Células Cultivadas , Células HEK293 , Humanos , Interleucina-33/análise , Peptídeos e Proteínas de Sinalização Intracelular/imunologia , Camundongos Endogâmicos C57BL , Proteínas de Ligação a Fosfato/imunologiaRESUMO
Antigen recognition by B-cell antigen receptors (BCRs) activates distinct intracellular signaling pathways that control the differentiation fate of activated B lymphocytes. BCR-proximal signaling enzymes comprise protein tyrosine kinases, phosphatases, and plasma membrane lipid-modifying enzymes, whose function is furthermore coordinated by catalytically inert adaptor proteins. Here, we show that an additional class of enzymatic activity provided by guanine-nucleotide exchange factors (GEFs) of the Vav family controls BCR-proximal Ca2+ mobilization, cytoskeletal actin reorganization, and activation of the PI3 kinase/Akt pathway. Whereas Vav1 and Vav3 supported all of those signaling processes to different extents in a human B-cell model system, Vav2 facilitated Actin remodeling, and activation of Akt but did not promote Ca2+ signaling. On BCR activation, Vav1 was directly recruited to the phosphorylated BCR and to the central adaptor protein SLP65 via its Src homology 2 domain. Pharmacological inhibition or genetic inactivation of the substrates of Vav GEFs, small G proteins of the Rho/Rac family, impaired BCR-induced Ca2+ mobilization, probably because phospholipase Cγ2 requires activated Rac proteins for optimal activity. Our findings show that Vav family members are key relays of the BCR signalosome that differentially control distinct signaling pathways both in a catalysis-dependent and -independent manner.
Assuntos
Proteínas Proto-Oncogênicas c-vav/metabolismo , Receptores de Antígenos de Linfócitos B/imunologia , Transdução de Sinais/imunologia , Linfócitos B/imunologia , Cálcio/imunologia , Diferenciação Celular/imunologia , Linhagem Celular Tumoral , Humanos , Fosforilação/imunologia , Domínios de Homologia de src/imunologiaRESUMO
The worldwide socioeconomical burden associated with chronic respiratory diseases is substantial. Enzymes involved in the metabolism of nicotinamide adenine dinucleotide (NAD) are increasingly being implicated in chronic airway diseases. One such enzyme, CD38, utilizes NAD to produce several metabolites, including cyclic ADP ribose (cADPR), which is involved in calcium signaling in airway smooth muscle (ASM). Upregulation of CD38 in ASM caused by exposure to cytokines or allergens leads to enhanced calcium mobilization by agonists and the development of airway hyperresponsiveness (AHR) to contractile agonists. Glucocorticoids and microRNAs can suppress CD38 expression in ASM, whereas cADPR antagonists such as 8Br-cADPR can directly antagonize intracellular calcium mobilization. Bronchodilators act via CD38-independent mechanisms. CD38-dependent mechanisms could be developed for chronic airway diseases therapy.
Assuntos
ADP-Ribosil Ciclase 1/metabolismo , ADP-Ribose Cíclica/metabolismo , Pneumopatias Obstrutivas/metabolismo , Glicoproteínas de Membrana/metabolismo , Transdução de Sinais/fisiologia , ADP-Ribosil Ciclase 1/imunologia , Animais , Cálcio/imunologia , Cálcio/metabolismo , ADP-Ribose Cíclica/imunologia , Humanos , Pneumopatias Obstrutivas/imunologia , Glicoproteínas de Membrana/imunologiaRESUMO
Exhaustion of CD8+ T cells and increased IL-10 production is well-known in chronic viral infections but mechanisms leading to loss of their cytotoxic capabilities and consequent exhaustion remain unclear. Exhausted CD8+T cells also called T suppressors are highly immune suppressive with altered T cell receptor signaling characteristics that mark it exclusively from their cytotoxic counterparts. Our study found that iCa2+ flux is reduced following T cell receptor activation in T suppressor cells when compared to their effector counterpart. Importantly chronic activation of murine cytotoxic CD8+ T cells lead to reduced iCa2+ influx, decreased IFN-γ and enhanced IL-10 production and this profile is mimicked in Tc1 cells upon reduction of iCa2+ flux by extracellular calcium channel inhibitors. Further reduced iCa2+ flux induced ROS which lead to IFN-γ reduction and increased IL-10 producing T suppressors through the STAT3-STAT5 axis. The above findings were substantiated by our human data where reduced iCa2+ flux in chronic Hepatitis infections displayed CD8+ T cells with low IFN-γ and increased IL-10 production. Importantly treatment with an antioxidant led to increased IFN-γ and reduced IL-10 production in human chronic Hep-B/C samples suggesting overall a proximal regulatory role for iCa2+ influx, ROS, and IL-10 in determining the effector/ suppressive axis of CD8+ T cells.