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Severe acute respiratory syndrome coronavirus 2 (SARS-Cov2) infection has caused an increase in mortality and morbidity, but with vaccination, the disease severity has significantly reduced. With the emergence of various variants of concern (VOCs), the vaccine breakthrough infection has also increased. Here we studied circulating spike-specific T follicular response (cTfh) in infection-naïve vaccinees and convalescent vaccinees (individuals who got the Delta breakthrough infection after two doses of BBV152 vaccine) to understand their response as they are the most crucial cells that are involved in vaccine-mediated protection by helping in B-cell maturation. Our results indicated that cTfh cells in both the groups recognized the wild-type and Delta spike protein but memory response to the wild-type spike was superior in infection-naïve than in the convalescent group. The cytokine response, particularly interleukin-21 (IL-21) from cTfh, was also higher in infection-naïve than in convalescent vaccinees, indicating a dampened cTfh response in convalescent vaccinees after breakthrough infection. Also, there was a positive correlation between IL-21 from cTfh cells and neutralizing antibodies of infection-naïve vaccinees. Multiple cytokine analysis also revealed higher inflammation in convalescent vaccinees. Our data indicated that the necessity of a third booster dose may be individual-specific depending on the steady-state functional phenotype of immune cells.
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COVID-19 , Humanos , COVID-19/prevención & control , ARN Viral , SARS-CoV-2 , Células T Auxiliares Foliculares , Citocinas , Infección IrruptivaRESUMEN
Systemic lupus erythematous (SLE) is a chronic autoimmune disorder, broadly characterized by systemic inflammation along with heterogeneous clinical manifestations, severe morbidity, moribund organ failure and eventual mortality. In our study, SLE patients displayed a higher percentage of activated, inflamed and hyper-polarized CD8+ T cells, dysregulated CD8+ T cell differentiation, significantly elevated serum inflammatory cytokines and higher accumulation of cellular ROS when compared to healthy controls. Importantly, these hyper-inflammatory/hyper-polarized CD8+ T cells responded better to an antioxidant than to an oxidant. Terminally differentiated Tc1 cells also showed plasticity upon oxidant/antioxidant treatment, but that was in contrast to the SLE CD8+ T cell response. Our studies suggest that the differential phenotype and redox response of SLE CD8+ T cells and Tc1 cells could be attributed to their cytokine environs during their respective differentiation and eventual activation environs. The polarization of Tc1 cells with IL-21 drove hyper-cytotoxicity without hyper-polarisation suggesting that the SLE inflammatory cytokine environment could drive the extreme aberrancy in SLE CD8+ T cells.
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Introduction: CD4+ T cells are critically involved in the pathogenesis of Rheumatoid Arthritis; an autoimmune disorder characterized by joint inflammation and bone degeneration. In this study, we focused on the critical role of cytokines, IL-21 and IL-23 in facilitating the aberrant status of RA Th17-like cells and report their significant contribution(s) in modulating the expression of inflammatory cytokines and RANKL. Methods: Blood and synovial fluid collected from a total of 167 RA patients and 25 healthy volunteers were assessed for various inflammatory markers and RANKL expression in plasma and CD4+ T cells. Subsequent ex vivo studies examined the role of specific cytokines, IL-21 and IL-23 in mediating inflammation and RANKL upregulation by blocking their expression with neutralizing antibodies in RA CD4+ T cells and terminally differentiated human Th17 cells. Further, the role of p-Akt1 as a signalling target downstream of IL-21 and IL-23 was evinced with IL-21 and IL-23 inhibition and phospho Akt-1/2 kinase inhibitor. Results: Our observations highlighted the augmented inflammatory cytokine levels in plasma and an aberrant CD4+ T cell phenotype expressing exaggerated inflammatory cytokines and membrane RANKL expression in RA as opposed to healthy controls. Neutralization of either IL-21 or IL-23 (p19 and p40) or both, resulted in downregulation of the cytokines, TNF-α, IFN-γ and IL-17 and RANKL expression in these cells, signifying the critical role of IL-21/23 axis in modulating inflammation and RANKL. Subsequent dissection of the signaling pathway found p-Akt1 as the key phosphoprotein downstream of both IL-21 and IL-23, capable of increasing inflammatory cytokines and RANKL production. Discussion: Our findings unequivocally identify IL-21/23 axis in RA CD4+ T cells as a key regulator dictating two critical processes i.e. exaggerated inflammation and higher RANKL expression and provide critical targets in their downstream signalling for therapeutic approaches.
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Citocinas , Interleucina-17 , Humanos , Citocinas/metabolismo , Interleucina-17/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Linfocitos T CD4-Positivos , Transducción de Señal , Interleucina-23/metabolismo , Inflamación/metabolismoRESUMEN
Infection with the human T-cell leukemia virus-1 (HTLV-1) results in a variety of diseases including adult T-cell leukemia/lymphoma (ATL). Although the pathogenesis of these disorders is poorly understood, it involves complex interactions with the host immune system. Activation of infected T cells may play an important role in disease pathogenesis through induction of the oncogenic HTLV-1 Tax transactivator protein. To test this hypothesis, we employed transgenic mice in which Tax is regulated by the HTLV-1 LTR. T-cell receptor stimulation of LTR-Tax CD4(+) T cells induced Tax expression, hyper-proliferation, and immortalization in culture. The transition to cellular immortalization was accompanied by markedly increased expression of the antiapoptotic gene, mcl-1, previously implicated as important in T-cell survival. Immortalized cells exhibited a CD4(+)CD25(+)CD3(-) phenotype commonly observed in ATL. Engraftment of activated LTR-Tax CD4(+) T cells into NOD/Shi-scid/IL-2Rγ null mice resulted in a leukemia-like phenotype with expansion and tissue infiltration of Tax(+), CD4(+) lymphocytes. We suggest that immune activation of infected CD4(+) T cells plays an important role in the induction of Tax expression, T-cell proliferation, and pathogenesis of ATL in HTLV-1-infected individuals.
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Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/patología , Productos del Gen tax/inmunología , Animales , Apoptosis , Linfocitos T CD4-Positivos/citología , Linfocitos T CD4-Positivos/metabolismo , Proliferación Celular , Citocinas/inmunología , Expresión Génica , Productos del Gen tax/genética , Ratones , Ratones Transgénicos , Linfocitos T Colaboradores-Inductores/inmunologíaRESUMEN
Background: SARS-CoV2 infection in patients with comorbidities, particularly T2DM, has been a major challenge globally and has been shown to be associated with high morbidity and mortality. Here, we did whole blood immunophenotyping along with plasma cytokine, chemokine, antibody isotyping, and viral load from oropharyngeal swab to understand the immune pathology in the T2DM patients infected with SARS-CoV2. Methods: Blood samples from 25 Covid-19 positive patients having T2DM, 10 Covid-19 positive patients not having T2DM, and 10 Covid-19 negative, non-diabetic healthy controls were assessed for various immune cells by analyzing for their signature surface proteins in mass cytometry. Circulating cytokines, chemokines, and antibody isotypes were determined from plasma while viral copy number was determined from oropharyngeal swabs. All our representative data corroborated with laboratory findings. Results: Our observations encompass T2DM patients having elevated levels of both type I and type II cytokines and higher levels of circulating IgA, IgM, IgG1, and IgG2 as compared to NDM and healthy volunteers. They also displayed higher percentages of granulocytes, mDCs, plasmablasts, Th2-like cells, CD4+ EM cells, and CD8+ TE cells as compared to healthy volunteers. T2DM patients also displayed lower percentages of pDCs, lymphocytes, CD8+ TE cells, CD4+, and CD8+ EM. Conclusion: Our study demonstrated that patients with T2DM displayed higher inflammatory markers and a dysregulated anti-viral and anti-inflammatory response when compared to NDM and healthy controls and the dysregulated immune response may be attributed to meta inflammation.
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COVID-19 , Diabetes Mellitus Tipo 2 , Quimiocinas , Citocinas , Humanos , ARN Viral , SARS-CoV-2RESUMEN
Purpose: The current global pandemic of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), led to the investigation with clinical, biochemical, immunological, and genomic characterization from patients to understand the pathophysiology of viral infection. Methods: Samples were collected from six asymptomatic and six symptomatic SARS-CoV-2-confirmed hospitalized patients in Bhubaneswar, Odisha, India. Clinical details, biochemical parameters, and treatment regimen were collected from a hospital; viral load was determined by RT-PCR; and the levels of cytokines and circulating antibodies in plasma were assessed by Bio-Plex and isotyping, respectively. In addition, whole-genome sequencing of viral strains and mutational analysis were carried out. Results: Analysis of the biochemical parameters highlighted the increased levels of C-reactive protein (CRP), lactate dehydrogenase (LDH), serum SGPT, serum SGOT, and ferritin in symptomatic patients. Symptomatic patients were mostly with one or more comorbidities, especially type 2 diabetes (66.6%). The virological estimation revealed that there was no significant difference in viral load of oropharyngeal (OP) samples between the two groups. On the other hand, viral load was higher in plasma and serum samples of symptomatic patients, and they develop sufficient amounts of antibodies (IgG, IgM, and IgA). The levels of seven cytokines (IL-6, IL-1α, IP-10, IL-8, IL-10, IFN-α2, IL-15) were found to be highly elevated in symptomatic patients, while three cytokines (soluble CD40L, GRO, and MDC) were remarkably higher in asymptomatic patients. The whole-genome sequence analysis revealed that the current isolates were clustered with 19B, 20A, and 20B clades; however, 11 additional changes in Orf1ab, spike, Orf3a, Orf8, and nucleocapsid proteins were acquired. The D614G mutation in spike protein is linked with higher virus replication efficiency and severe SARS-CoV-2 infection as three patients had higher viral load, and among them, two patients with this mutation passed away. Conclusions: This is the first comprehensive study of SARS-CoV-2 patients from India. This will contribute to a better understanding of the pathophysiology of SARS-CoV-2 infection and thereby advance the implementation of effective disease control strategies.
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COVID-19 , Diabetes Mellitus Tipo 2 , Genómica , Humanos , Pandemias , SARS-CoV-2RESUMEN
Receptor-stimulated generation of reactive oxygen species (ROS) has been shown to regulate signal transduction, and previous studies have suggested that T cell receptor (TCR) signals may involve or be sensitive to ROS. In this study, we have shown for the first time that TCR cross-linking induced rapid (within 15 min) generation of both hydrogen peroxide and superoxide anion, as defined with oxidation-sensitive dyes, selective pharmacologic antioxidants, and overexpression of specific antioxidant enzymes. Furthermore, the data suggest the novel observation that superoxide anion and hydrogen peroxide are produced separately by distinct TCR-stimulated pathways. Unexpectedly, TCR-stimulated activation of the Fas ligand (FasL) promoter and subsequent cell death was dependent upon superoxide anion, but independent of hydrogen peroxide, while nuclear factor of activated T cells (NFAT) activation or interleukin 2 transcription was independent of all ROS. Anti-CD3 induced phosphorylation of extracellular signal-regulated kinase (ERK)1/2 required hydrogen peroxide generation but was unaffected by superoxide anion. Thus, antigen receptor signaling induces generation of discrete species of oxidants that selectively regulate two distinct redox sensitive pathways, a proapoptotic (FasL) and a proliferative pathway (ERK).
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Glicoproteínas de Membrana/biosíntesis , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Peróxidos/metabolismo , Receptores de Antígenos de Linfocitos T/metabolismo , Linfocitos T/inmunología , Animales , Apoptosis , Complejo CD3/metabolismo , Proteína Ligando Fas , Depuradores de Radicales Libres/farmacología , Humanos , Hibridomas , Peróxido de Hidrógeno/metabolismo , Activación de Linfocitos , Ratones , Modelos Inmunológicos , Oxidación-Reducción , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal , Superóxidos/metabolismoRESUMEN
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.
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Linfocitos T CD8-positivos/inmunología , Calcio/metabolismo , Linfocitos T Citotóxicos/inmunología , Virosis/inmunología , Animales , Antioxidantes/farmacología , Calcio/inmunología , Bloqueadores de los Canales de Calcio/farmacología , Células Cultivadas , Citotoxicidad Inmunológica , Voluntarios Sanos , Hepatitis B/inmunología , Humanos , Interferón gamma/metabolismo , Interleucina-10/genética , Interleucina-10/inmunología , Interleucina-10/metabolismo , Activación de Linfocitos/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Factores de Transcripción NFATC/metabolismo , Especies Reactivas de Oxígeno/inmunología , Especies Reactivas de Oxígeno/metabolismoRESUMEN
The lethality of blood stage Plasmodium berghei ANKA (PbA) infection is associated with the expression of T-bet and production of cytokine IFN-γ. Expression of inducible costimulator (ICOS) and its downstream signaling has been shown to play a critical role in the T-bet expression and IFN-γ production. Although earlier studies have examined the role of ICOS in the control of acute blood-stage infection of Plasmodium chabaudi chabaudi AS (a non-lethal model of malaria infection), its significance in the lethal blood-stage of PbA infection remains unclear. Thus, to address the seminal role of ICOS in lethal blood-stage of PbA infection, we treated PbA-infected mice with anti-ICOS antibody and observed that these mice survived longer than their infected counterparts with significantly lower parasitemia. Anti-ICOS treatment notably depleted ICOS expressing CD4+ and CD8+ T cells with a concurrent reduction in plasma IFN-γ, which strongly indicated that ICOS expressing T cells are major IFN-γ producers. Interestingly, we observed that while ICOS expressing CD4+ and CD8+ T cells produced IFN-γ, ICOS-CD8+ T cells were also found to be producers of IFN-γ. However, we report that ICOS+CD8+ T cells were higher producers of IFN-γ than ICOS-CD8+ T cells. Moreover, correlation of ICOS expression with IFN-γ production in ICOS+IFN-γ+ T cell population (CD4+ and CD8+ T cells) suggested that ICOS and IFN-γ could positively regulate each other. Further, master transcription factor T-bet importantly involved in regulating IFN-γ production was also found to be expressed by ICOS expressing CD4+ and CD8+ T cells during PbA infection. As noted above with IFN-γ and ICOS, a positive correlation of expression of ICOS with the transcription factor T-bet suggested that both of them could regulate each other. Taken together, our results depicted the importance of ICOS expressing CD4+ and CD8+ T cells in malaria parasite growth and lethality through IFN-γ production and T-bet expression.
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Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD8-positivos/inmunología , Proteína Coestimuladora de Linfocitos T Inducibles/metabolismo , Malaria/inmunología , Plasmodium berghei/crecimiento & desarrollo , Animales , Interferón gamma/inmunología , Activación de Linfocitos , Masculino , Ratones , Ratones Endogámicos C57BL , Parasitemia/inmunología , Proteínas de Dominio T Box/genética , Proteínas de Dominio T Box/inmunologíaRESUMEN
Purpose: Intraocular inflammation in tuberculosis-associated uveitis (TBU) is usually widespread, and responds unpredictably to treatment. Herein, we analyze the intraocular T-cell response in TBU for its surface phenotype, antigenic specificity, and functional characteristics to explain the above observations. Methods: We isolated T cells from vitreous humor samples of patients with TBU and non-TB uveitis (controls). These were directly stained for surface markers CD4, CD8, CD45RO, CD45RA, CCR7, as well as intracellular cytokines IFN-γ, TNF-α, and IL-17 and analyzed on flow cytometry. Antigenic specificity was determined by activating with Mycobacterium tuberculosis-specific antigen Early Secreted Antigenic Target-6 (ESAT-6) or retinal crude extract (RCE). Activation-induced cell death (AICD) characteristics of each T-cell population were analyzed by staining for PI-Annexin V, Fas-FasL, phospho-Akt, and phospho-Erk1/2. Results: Immunophenotyping of vitreous humor samples demonstrated polyfunctional effector and central memory CD4+ T helper cells coexpressing IFN-γ, TNF-α, and IL-17. Both ESAT-6 and RCE (autoreactive) specificity was found in T cells extracted from TBU samples; however, the mycobacterial and autoreactive T-cell populations differed in their sensitivity to AICD. Autoreactive T cells appeared to resist AICD through decreased expression of apoptotic markers, FasL and caspase-3, sustained phosphorylation of Akt, and lowered Erk1/2 activity. Conclusions: Autoreactive T cells are present in TBU eyes and are relatively resistant to AICD. An understanding of this epiphenomenon could be crucial in planning treatment of TBU patients, and interpreting response to anti-TB therapy.
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Infecciones Bacterianas del Ojo/inmunología , Inmunidad Celular , Mycobacterium tuberculosis/inmunología , Linfocitos T/inmunología , Tuberculosis Ocular/inmunología , Uveítis/inmunología , Antígenos Bacterianos/inmunología , Antígenos Bacterianos/metabolismo , Proteínas Bacterianas/inmunología , Proteínas Bacterianas/metabolismo , Citocinas/metabolismo , Infecciones Bacterianas del Ojo/microbiología , Infecciones Bacterianas del Ojo/patología , Femenino , Citometría de Flujo , Humanos , Inmunofenotipificación , Masculino , Mycobacterium tuberculosis/aislamiento & purificación , Retina/microbiología , Retina/patología , Linfocitos T/patología , Tuberculosis Ocular/microbiología , Tuberculosis Ocular/patología , Uveítis/microbiología , Uveítis/patologíaRESUMEN
Granulocyte-macrophage colony-stimulating factor (GM-CSF) is an important hematopoietic growth factor and immune modulator. GM-CSF also has profound effects on the functional activities of various circulating leukocytes. It is produced by a variety of cell types including T cells, macrophages, endothelial cells and fibroblasts upon receiving immune stimuli. Although GM-CSF is produced locally, it can act in a paracrine fashion to recruit circulating neutrophils, monocytes and lymphocytes to enhance their functions in host defense. Recent intensive investigations are centered on the application of GM-CSF as an immune adjuvant for its ability to increase dendritic cell (DC) maturation and function as well as macrophage activity. It is used clinically to treat neutropenia in cancer patients undergoing chemotherapy, in AIDS patients during therapy, and in patients after bone marrow transplantation. Interestingly, the hematopoietic system of GM-CSF-deficient mice appears to be normal; the most significant changes are in some specific T cell responses. Although molecular cloning of GM-CSF was carried out using cDNA library of T cells and it is well known that the T cells produce GM-CSF after activation, there is a lack of systematic investigation of this cytokine in production by T cells and its effect on T cell function. In this article, we will focus mainly on the immunobiology of GM-CSF in T cells.
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Factor Estimulante de Colonias de Granulocitos y Macrófagos/metabolismo , Activación de Linfocitos , Linfocitos T/metabolismo , Animales , Vacunas contra el Cáncer , Factor Estimulante de Colonias de Granulocitos y Macrófagos/genética , Humanos , Inflamación/inmunología , FenotipoRESUMEN
The follicular helper T (Tfh) cells help is critical for activation of B cells, antibody class switching, and germinal center (GC) formation. The Tfh cells are characterized by the expression of CXC chemokine receptor 5 (CXCR5), ICOS, programed death 1 (PD-1), B cell lymphoma 6 (BCL-6), and IL-21. They are involved in clearing infections and are adversely linked with autoimmune diseases and also have a role in viral replication as well as clearance. On the one hand, Tfh cells are generated from naive CD4+ T cells with sequential steps involving cytokine signaling (IL-21, IL-6, IL-12, activin A), migration, and positioning in the GC by CXCR5, surface receptors (ICOS/ICOSL, signaling lymphocyte activation molecule-associated protein/signaling lymphocyte activation molecule) as well as transcription factor (BCL-6, c-Maf, and signal transducer and activator of transcription 3) signaling and repressor miR155. On the other hand, Tfh generation is negatively regulated at specific steps of Tfh generation by specific cytokine (IL-2, IL-7), surface receptor (PD-1, CTLA-4), transcription factors B lymphocyte maturation protein 1, signal transducer and activator of transcription 5, T-bet, KLF-2 signaling, and repressor miR 146a. Interestingly, miR-17-92 and FOXO1 act as a positive as well as a negative regulator of Tfh differentiation depending on the time of expression and disease specificity. Tfh cells are also generated from the conversion of other effector T cells as exemplified by Th1 cells converting into Tfh during viral infection. The mechanistic details of effector T cells conversion into Tfh are yet to be clear. To manipulate Tfh cells for therapeutic implication and or for effective vaccination strategies, it is important to know positive and negative regulators of Tfh generation. Hence, in this review, we have highlighted and interlinked molecular signaling from cytokines, surface receptors, transcription factors, ubiquitin ligase, and microRNA as positive and negative regulators for Tfh differentiation.
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Activation Induced Cell Death of T helper cells is central to maintaining immune homeostasis and a perturbation often manifests in aberrant T helper cells that is associated with immunopathologies. Significant presence of T cells positive for IL-17A (Th17) and dual positive for IFN-γ/IL-17A (Th1/Th17) in both effector (CD45RA+RO+) and memory (CD45RA-RO+) compartments with differential FasL protein in RA peripheral blood suggested their differential TCR AICD sensitivity. Lowered active caspase-3 in Th17 and Th1/Th17 over Th1 cells confirmed their capability to resist AICD and pointed to early upstream events. Differential MAPK activities, FasL protein and downstream caspase-3 activities in murine Th1 and Th17 cells established distinct TCR mediated signaling pathways and suggested low Erk and p38 activity as pivotal for AICD sensitivity. We extrapolated our mouse and human data and report that Fas-FasL is the preferred death pathway for both Th1 and Th17 and that inherently low Erk2 activity protected Th17 cells from TCR AICD. The presence of significantly higher numbers of aberrant T helper cells in RA also suggest an inflammatory cytokine milieu and AICD insensitive T cell link to sustained inflammation. Re sensitization to apoptosis by targeting MAPK activity especially Erk2 in RA might be of therapeutic value.
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Apoptosis , Degranulación de la Célula , Proteína Ligando Fas/análisis , Activación de Linfocitos , Proteína Quinasa 1 Activada por Mitógenos/fisiología , Células Th17/fisiología , Proteínas Quinasas p38 Activadas por Mitógenos/fisiología , Animales , Artritis Reumatoide/inmunología , Activación Enzimática , Humanos , Memoria Inmunológica , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Células Th17/inmunologíaRESUMEN
Reactive oxygen species (ROS) signaling is critical in T helper (Th) cell differentiation; however its role in differentiated Th cell functions is unclear. In this study, we investigated the role of oxidative stress on the effector functions of in vitro differentiated mouse Th17 and Th1 cells or CD4+ T cells from patients with Rheumatoid Arthritis using pro-oxidants plumbagin (PB) and hydrogen peroxide. We found that in mouse Th cells, non-toxic concentration of pro-oxidants inhibited reactivation induced expression of IL-17A in Th17 and IFN-γ in Th1 cells by reducing the expression of their respective TFs, RORγt and T-bet. Interestingly, in both the subsets, PB increased the expression of IL-4 by enhancing reactivation induced ERK1/2 phosphorylation. We further investigated the cytokine modulatory effect of PB on CD4+ T cells isolated from PBMCs of patients with Rheumatoid Arthritis, a well-known Th17 and or Th1 mediated disease. In human CD4+ T cells from Rheumatoid Arthritis patients, PB reduced the frequencies of IL-17A+ (Th17), IFN-γ+ (Th1) and IL-17A+/IFN-γ+ (Th17/1) cells and also inhibited the production of pro-inflammatory cytokines TNF-α and IL-6. N-Acetyl Cysteine (NAC) an antioxidant completely reversed PB mediated cytokine modulatory effects in both mouse and human cells indicating a direct role for ROS. Together our data suggest that oxidative microenvironment can alter cytokine response of terminally differentiated cells and thus altering intracellular ROS could be a potential way to target Th17 and Th1 cells in autoimmune disorders.
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Artritis Reumatoide/inmunología , Citocinas/inmunología , Regulación de la Expresión Génica/inmunología , Estrés Oxidativo/inmunología , Células TH1/efectos de los fármacos , Células Th17/efectos de los fármacos , Acetilcisteína/farmacología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Animales , Artritis Reumatoide/genética , Artritis Reumatoide/patología , Estudios de Casos y Controles , Diferenciación Celular , Citocinas/genética , Femenino , Humanos , Peróxido de Hidrógeno/antagonistas & inhibidores , Peróxido de Hidrógeno/farmacología , Masculino , Ratones , Ratones Endogámicos BALB C , Persona de Mediana Edad , Proteína Quinasa 1 Activada por Mitógenos/genética , Proteína Quinasa 1 Activada por Mitógenos/inmunología , Proteína Quinasa 3 Activada por Mitógenos/genética , Proteína Quinasa 3 Activada por Mitógenos/inmunología , Naftoquinonas/antagonistas & inhibidores , Naftoquinonas/farmacología , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/genética , Miembro 3 del Grupo F de la Subfamilia 1 de Receptores Nucleares/inmunología , Oxidantes/antagonistas & inhibidores , Oxidantes/farmacología , Fosforilación/efectos de los fármacos , Cultivo Primario de Células , Proteínas de Dominio T Box/genética , Proteínas de Dominio T Box/inmunología , Células TH1/inmunología , Células TH1/patología , Células Th17/inmunología , Células Th17/patologíaRESUMEN
Inhibition of Fas-mediated apoptosis in B cell lymphomas by thiol antioxidants (glutathione and N-acetylcysteine) supported previous studies, suggesting that Fas-stimulated ROS generation may play a role in Fas-mediated apoptosis. Thus, the goal of the current study was to determine if Fas stimulation could induce ROS generation and what role, if any, it played in apoptosis. Fas crosslinking induced rapid generation of ROS (within 15 min) well before the appearance of characteristic apoptotic changes. Overexpression of catalase or superoxide dismutase suggested that Fas induced production of both superoxide anion and hydrogen peroxide. ROS generation was only observed, however, in cells that were sensitive to apoptosis and not in B cells inherently resistant to anti-Fas or in those in which resistance was induced by B cell receptor crosslinking. The exogenous addition of 250 microM hydrogen peroxide could reverse the resistant phenotype and sensitize cells to Fas-induced apoptosis. In Fas-sensitive cells, depletion of endogenous antioxidant defenses with buthionine sulfoximine increased the sensitivity to Fas-induced apoptosis, while overexpression of antioxidant enzymes and antiapoptotic proteins suggested a role for Fas-induced production of hydrogen peroxide in apoptosis. Further analysis suggested a redox-sensitive step early in Fas signaling at the level of initiator caspase (caspase-8) activation. Thus, the data suggest that the level of oxidative stress, either from exogenous sources or generated endogenously upon receptor stimulation, regulates the sensitivity to Fas-mediated apoptosis.
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Apoptosis , Estrés Oxidativo , Especies Reactivas de Oxígeno/metabolismo , Receptor fas/metabolismo , Antioxidantes/metabolismo , Apoptosis/efectos de los fármacos , Caspasa 8 , Caspasas/metabolismo , Línea Celular Tumoral , Citometría de Flujo , Vectores Genéticos , Glutatión/farmacología , Humanos , Linfoma de Células B/metabolismo , Linfoma de Células B/patología , Oxidación-Reducción/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacosRESUMEN
Activation-induced cell death (AICD) has been demonstrated in T-cell hybridomas, immature thymocytes, and activated mature T cells. However, the molecular mechanisms of AICD and its physiological role in T-helper-cell differentiation remain uncertain. Recently, we have shown that Th1 and Th2 cells have distinct mechanisms of AICD. Our findings suggest that signaling from cytokines initiates the differentiation program, but that the selective action of death effectors determines the fate of differentiating T-helper cells, and thus, the ultimate balance between T-helper subpopulations. Among T cells, activation- induced expression of the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is observed exclusively in Th2 clones and primary T-helper cells differentiated under Th2 conditions, while the expression of CD95L (Fas ligand) occurs mainly in Th1 cells. Furthermore, Th1 cells are more susceptible than Th2 cells to apoptosis induced through either TRAIL or CD95L, and radiolabeled Th1 cells can be induced into apoptosis via fratricide by both Th1 and Th2 cells, while Th2 cells are spared. The pan-caspase inhibitor, z-VAD, prevents AICD in Th1 cells, but not Th2 cells, indicating different mechanisms of AICD in each T-helper subtype. Antibody blockade of TRAIL and CD95L significantly boosts interferon-gamma (IFN-gamma) production in vitro. Also, young mice with mutant CD95 (MRL/MpJ-lpr/lpr) have a stronger Th1 response to ovalbumin immunization than do controls. We conclude that apoptosis mediated by CD95L and TRAIL is critical in the selective removal of differentiating T helper cells.
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Apoptosis/inmunología , Células TH1/citología , Células TH1/inmunología , Células Th2/citología , Células Th2/inmunología , Animales , Proteínas Reguladoras de la Apoptosis , Diferenciación Celular , Humanos , Activación de Linfocitos , Glicoproteínas de Membrana/inmunología , Ligando Inductor de Apoptosis Relacionado con TNF , Factor de Necrosis Tumoral alfa/inmunologíaRESUMEN
Although CD95L is required for T cell receptor (TCR)-induced cell death (TCR-ICD) in T helper 1 cells, the molecular mechanisms mediating TCR-ICD in Th2 cells are unknown. We found that death receptors were not involved in TCR-ICD of Th2 cells because blocking their cognate ligands had no effect on apoptosis of activated Th2 cells. Furthermore, we showed that caspases were not actively involved in TCR-ICD of Th2 cells. However, inhibition of granzyme B (GrB) activity abolished TCR-ICD in Th2 cells but not Th1 cells. Likewise, Th2 cells derived from GrB-deficient mice were resistant to TCR-ICD, and GrB deficiency or inhibition of GrB activity consequently enhanced the production of Th2 cytokines. GrB-deficient mice exhibited increased susceptibility to allergen-induced asthma. Thus, GrB plays a critical role in the TCR-ICD of Th2 cells.
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Apoptosis/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Serina Endopeptidasas/metabolismo , Células Th2/citología , Células Th2/metabolismo , Alérgenos/inmunología , Animales , Asma/inmunología , Asma/patología , Caspasas/metabolismo , Células Cultivadas , Activación Enzimática , Femenino , Granzimas , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Serina Endopeptidasas/deficiencia , Serina Endopeptidasas/genética , Células TH1/citología , Células TH1/inmunología , Células TH1/metabolismo , Células Th2/inmunología , Factores de Tiempo , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
T cell receptor (TCR) stimulation induces rapid generation of reactive oxygen species, although the mechanisms for this are unclear. Here we found that T cells expressed a functional phagocyte-type nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. TCR crosslinking induced oxidase activation through the recruitment of preformed Fas ligand and Fas. TCR stimulation induced three separable events generating reactive oxygen species: rapid hydrogen peroxide production independent of Fas or NADPH oxidase; sustained hydrogen peroxide production dependent on both Fas and NADPH oxidase; and delayed superoxide production that was dependent on Fas ligand and Fas yet independent of NADPH oxidase. NADPH oxidase-deficient T cells showed enhanced activation of the kinase Erk and a relative increase in T helper type 1 cytokine secretion. Thus, mature T cells express a phagocyte-type NADPH oxidase that regulates elements of TCR signaling.
Asunto(s)
Activación de Linfocitos/inmunología , NADPH Oxidasas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Receptores de Antígenos de Linfocitos T/metabolismo , Linfocitos T/enzimología , Animales , Células Cultivadas , Proteína Ligando Fas , Humanos , Immunoblotting , Glicoproteínas de Membrana , Especies Reactivas de Oxígeno/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de Señal/inmunología , Receptor fasRESUMEN
Psychological and physical stressors best exemplify the intercommunication of the immune and the nervous systems. It has been shown that stress significantly impacts leukocyte cellularity and immune responses and alters susceptibility to various diseases. While acute stress has been shown to enhance immune responses, chronic stress often leads to immunosuppression. Among many criteria examined upon exposure to chronic stress, the reduction in lymphocyte mitogenic response and lymphocyte cellularity are commonly assessed. We have reported that chronic restraint stress could induce lymphocyte reduction, an effect dependent on endogenous opioids. Interestingly, the effect of endogenous opioids was found to be exerted through increasing the expression of a cell death receptor, Fas, and an increased sensitivity of lymphocytes to apoptosis. Stress-induced lymphocyte reduction was not affected by adrenalectomy. In this review, based on available literature and our recent data, we will discuss the role of the hypothalamic-pituitary-adrenal axis and endogenous opioids and examine the mechanisms by which chronic stress modulates lymphocyte apoptosis.