RESUMO
T cell responses upon infection display a remarkably reproducible pattern of expansion, contraction, and memory formation. If the robustness of this pattern builds entirely on signals derived from other cell types or if activated T cells themselves contribute to the orchestration of these population dynamics-akin to bacterial quorum regulation-is unclear. Here, we examined this question using time-lapse microscopy, genetic perturbation, bioinformatic predictions, and mathematical modeling. We found that ICAM-1-mediated cell clustering enabled CD8+ T cells to collectively regulate the balance between proliferation and apoptosis. Mechanistically, T cell expressed CD80 and CD86 interacted with the receptors CD28 and CTLA-4 on neighboring T cells; these interactions fed two nested antagonistic feedback circuits that regulated interleukin 2 production in a manner dependent on T cell density as confirmed by in vivo modulation of this network. Thus, CD8+ T cell-population-intrinsic mechanisms regulate cellular behavior, thereby promoting robustness of population dynamics.
Assuntos
Antígenos CD28/metabolismo , Linfócitos T CD8-Positivos/citologia , Linfócitos T CD8-Positivos/imunologia , Antígeno CTLA-4/metabolismo , Animais , Antígeno B7-1/metabolismo , Antígeno B7-2/metabolismo , Linfócitos T CD8-Positivos/metabolismo , Comunicação Celular , Contagem de Células , Linhagem Celular , Sobrevivência Celular , Rastreamento de Células , Células Dendríticas/imunologia , Molécula 1 de Adesão Intercelular/metabolismo , Interleucina-2/metabolismo , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Modelos TeóricosRESUMO
Because of the growing numbers of immunocompromised patients, the incidence of life-threatening fungal infections caused by Candida albicans and Aspergillus fumigatus is increasing. We have recently identified enolase 1 (Eno1) from A. fumigatus as an immune evasion protein. Eno1 is a fungal moonlighting protein that mediates adhesion and invasion of human cells and also immune evasion through complement inactivation. We now show that soluble Eno1 has immunostimulatory activity. We observed that Eno1 from both C. albicans and A. fumigatus directly binds to the surface of lymphocytes, preferentially human and mouse B cells. Functionally, Eno1 upregulated CD86 expression on B cells and induced proliferation. Although the receptor for fungal Eno1 on B lymphocytes is still unknown, the comparison of B cells from wild-type and MyD88-deficient mice showed that B cell activation by Eno1 required MyD88 signaling. With respect to infection biology, we noted that mouse B cells stimulated by Eno1 secreted IgM and IgG2b. These Igs bound C. albicans hyphae in vitro, suggesting that Eno1-induced Ab secretion might contribute to protection from invasive fungal disease in vivo. Eno1 also triggered the release of proinflammatory cytokines from monocytes, particularly IL-6, which is a potent activator of B cells. Together, our data shed new light on the role of secreted Eno1 in infections with C. albicans and A. fumigatus. Eno1 secretion by these pathogenic microbes appears to be a double-edged sword by supporting fungal pathogenicity while triggering (antifungal) immunity.
Assuntos
Aspergillus fumigatus , Candida albicans , Fosfopiruvato Hidratase , Animais , Humanos , Camundongos , Aspergillus fumigatus/enzimologia , Aspergillus fumigatus/metabolismo , Candida albicans/enzimologia , Candida albicans/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Monócitos/metabolismo , Monócitos/microbiologia , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/metabolismo , Fosfopiruvato Hidratase/metabolismo , Linfócitos B/metabolismo , Linfócitos B/microbiologiaRESUMO
Due to ontogenetic changes in B-cell developmental lineages, the mature B-cell compartment constitutes by functionally different B-cell subsets that emerged from prenatal, early postnatal or adult precursors. While negative selection processes operate primarily within the framework of B-cell tolerance checkpoints during B-cell development, further differentiation into distinct B-cell subsets is additionally induced by positive selection. In addition to endogenous antigens, contact with microbial antigens is also involved in this selection process, with intestinal commensals having a significant influence on the development of a large layer within the B-cell compartment. The decisive threshold that triggers negative selection seems to be relaxed during fetal B-cell development, thereby allowing recruitment of polyreactive and also autoreactive B-cell clones into the mature naïve B-cell compartment. Almost all of the concepts on B-cell ontogeny are based on observations in laboratory mice that not only differ from humans in their developmental timeline but also in their composition of commensal microorganisms or rather a lack of exposure to these. In this review, we summarize conceptual findings on B-cell ontogeny and particularly describe key insights into the developing human B-cell compartment and immunoglobulin repertoire formation.
Assuntos
Subpopulações de Linfócitos B , Linfócitos B , Camundongos , Animais , Adulto , Humanos , Antígenos , Tolerância Imunológica , Diferenciação CelularRESUMO
To obtain a better understanding of the biology behind life-threatening fungal infections caused by Candida albicans, we recently conducted an in silico screening for fungal and host protein interaction partners. We report here that the extracellular domain of human CD4 binds to the moonlighting protein enolase 1 (Eno1) of C. albicans as predicted bioinformatically. By using different anti-CD4 monoclonal antibodies, we determined that C. albicans Eno1 (CaEno1) primarily binds to the extracellular domain 3 of CD4. Functionally, we observed that CaEno1 binding to CD4 activated lymphocyte-specific protein tyrosine kinase (LCK), which was also the case for anti-CD4 monoclonal antibodies tested in parallel. CaEno1 binding to naïve human CD4+ T cells skewed cytokine secretion toward a Th2 profile indicative of poor fungal control. Moreover, CaEno1 inhibited human memory CD4+ T-cell recall responses. Therapeutically, CD4+ T cells transduced with a p41/Crf1-specific T-cell receptor developed for adoptive T-cell therapy were not inhibited by CaEno1 in vitro. Together, the interaction of human CD4+ T cells with CaEno1 modulated host CD4+ T-cell responses in favor of the fungus. Thus, CaEno1 mediates not only immune evasion through its interference with complement regulators but also through the direct modulation of CD4+ T-cell responses.
Assuntos
Candida albicans , Linfócitos T , Humanos , Linfócitos T/metabolismo , Linfócitos T CD4-Positivos , Fosfopiruvato Hidratase/metabolismo , Anticorpos Monoclonais/metabolismoRESUMO
Though myocardial infarction (MI) in pigs is a well-established translational large animal model, it has not yet been widely used for immunotherapy studies, and a comprehensive description of the immune response to MI in this species is lacking. We induced MI in Landrace pigs by balloon occlusion of the left anterior descending artery over 90 min. Within 14 days, the necrotic myocardium was progressively replaced by scar tissue with involvement of myofibroblasts. We characterized the immune response in the heart ex vivo by (immuno)histology, flow cytometry, and RNA sequencing of myocardial tissue on days 3, 7, and 14 after MI. Besides a clear predominance of myeloid cells among heart-infiltrating leukocytes, we detected activated T cells and an increasing proportion of CD4+ Foxp3+ regulatory T cells (Treg), especially in the infarct core-findings that closely mirror what has been observed in mice and humans after MI. Transcriptome data indicated inflammatory activity that was persistent but markedly changing in character over time and linked to extracellular matrix biology. Analysis of lymphocytes in heart-draining lymph nodes revealed significantly higher proliferation rates of T helper cell subsets, including Treg on day 7 after MI, compared to sham controls. Elevated frequencies of myeloid progenitors in the spleen suggest that it might be a site of emergency myelopoiesis after MI in pigs, as previously shown in mice. We thus provide a first description of the immune response to MI in pigs, and our results can aid future research using the species for preclinical immunotherapy studies.
Assuntos
Modelos Animais de Doenças , Infarto do Miocárdio , Miocárdio , Linfócitos T Reguladores , Animais , Infarto do Miocárdio/imunologia , Infarto do Miocárdio/patologia , Linfócitos T Reguladores/imunologia , Miocárdio/patologia , Miocárdio/imunologia , Sus scrofa , Suínos , Ativação Linfocitária , Masculino , Transcriptoma , Feminino , Fatores de TempoRESUMO
Myocardial infarction (MI) induces the generation of proinflammatory Ly6Chigh monocytes in the spleen and the recruitment of these cells to the myocardium. CD4+ Foxp3+ CD25+ T-cells (Tregs) promote the healing process after myocardial infarction by engendering a pro-healing differentiation state in myocardial monocyte-derived macrophages. We aimed to study the effects of CD4+ T-cells on splenic myelopoiesis and monocyte differentiation. We instigated MI in mice and found that MI-induced splenic myelopoiesis is abrogated in CD4+ T-cell deficient animals. Conventional CD4+ T-cells promoted myelopoiesis in vitro by cell-cell-contact and paracrine mechanisms, including interferon-gamma (IFN-γ) signalling. Depletion of regulatory T-cells enhanced myelopoiesis in vivo, as evidenced by increases in progenitor cell numbers and proliferative activity in the spleen 5 days after MI. The frequency of CD4+ T-cells-producing factors that promote myelopoiesis increased within the spleen of Treg-depleted mice. Moreover, depletion of Tregs caused a proinflammatory bias in splenic Ly6Chigh monocytes, which showed predominantly upregulated expression of IFN-γ responsive genes after MI. Our results indicate that conventional CD4+ T-cells promote and Tregs attenuate splenic myelopoiesis and proinflammatory differentiation of monocytes.
Assuntos
Monócitos , Infarto do Miocárdio , Camundongos , Animais , Monócitos/metabolismo , Mielopoese , Baço/metabolismo , Infarto do Miocárdio/metabolismo , Linfócitos T Reguladores/metabolismo , Interferon gama/farmacologia , Camundongos Endogâmicos C57BLRESUMO
INTRODUCTION: Aspergillus fumigatus belongs to the saprophytic fungi, and its spores form a significant part of the daily load of fungal spores inhaled as particles in aerosols. A. fumigatus is a possible T-cell activator. Its contribution to the pathogenesis of chronic rhinosinusitis (CRS) is controversially discussed. The aim of this study was to detect and characterize A. fumigatus-specific CD4+ and CD8+ T cells in patients with CRS with (CRSwNP) and without (CRSsNP) nasal polyps. METHODS: Tissue and blood samples were collected from patients who underwent paranasal sinus surgery due to CRSwNP or CRSsNP. Afterward, purified CD4+ and CD8+ cells were cultured together with antigen-presenting cells. A peptide mix derived from A. fumigatus antigen was added to the cultures. After 6 days, multicolor flow cytometry was performed, and proliferation was measured using the marker Ki-67. Cytokine secretion was quantified from the supernatant of the cell culture. RESULTS: Significant differences in the proliferation of nasal CD4+ T cells to A. fumigatus antigen were observed for cells from patients with CRSwNP in comparison to CRSsNP, while no differences were found between nasal and peripheral blood T cells. The activation of tissue-derived CD4+ T cells was associated with significantly higher concentrations of IL-4, IL-5, and IL-17a in the cell culture from patients with CRSwNP in comparison to CRSsNP and/or healthy controls. CONCLUSION: Our findings indicate that patients with CRSwNP harbor a higher proportion of A. fumigatus-reactive CD4+ T cells in the nasal mucosa than patients with CRSsNP. A. fumigatus-reactive CD4+ T cells of CRSwNP patients secreted TH2 cytokines and IL-17. Our findings suggest a role for A. fumigatus in the pathogenesis of CRSwNP and provide a rationale for targeted therapies.
Assuntos
Pólipos Nasais , Rinite , Sinusite , Humanos , Aspergillus fumigatus , Mucosa Nasal , Linfócitos T CD4-Positivos , Doença CrônicaRESUMO
Because of its size, anatomical similarities, and now also accessibility to genetic manipulations, pigs are used as animal models for human diseases and immune system development. However, expression and function of CD28, the most important costimulatory receptor expressed by T cells, so far is poorly understood in this species. Using a newly generated mAb (mAb 3D11) with specificity for pig CD28, we detected CD28 on CD8+ and CD4+ αß T cells. Among γδ T cells, CD28 expression was restricted to a small CD2+ subpopulation of phenotypically naive cells. Functionally, CD28 ligation with mAb 3D11-costimulated porcine T cells, enhanced proliferation and cytokine secretion in vitro. We used a second, likewise newly generated but superagonistic, anti-CD28 mAb (CD28-SA; mAb 4D12) to test the function of CD28 on porcine T cells in a pilot study in vivo. Injection of the CD28-SA into pigs in vivo showed a very similar dose-response relationship as in humans (i.e., 100 µg/kg body weight [BW]) of CD28-SA induced a cytokine release syndrome that was avoided at a dose of 10 µg/kg BW and below. The data further suggest that low-dose (10 µg/kg BW) CD28-SA infusion was sufficient to increase the proportion of Foxp3+ regulatory T cells among CD4+ T cells in vivo. The pig is thus a suitable animal model for testing novel immunotherapeutics. Moreover, data from our pilot study in pigs further suggest that low-dose CD28-SA infusion might allow for selective expansion of CD4+ regulatory T cells in humans.
Assuntos
Anticorpos Monoclonais/imunologia , Antígenos CD28/imunologia , Modelos Animais , Suínos/imunologia , Linfócitos T/imunologia , Animais , Anticorpos Monoclonais/farmacologia , Humanos , Ativação Linfocitária/imunologiaRESUMO
Like human Th1 cells, mouse Th1 cells also secrete IFN-γ upon stimulation with a superagonistic anti-CD28 monoclonal antibody (CD28-SA). Crosslinking of the CD28-SA via FcR and CD40-CD40L interactions greatly increased IFN-γ release. Our data stress the utility of the mouse as a model organism for immune responses in humans.
Assuntos
Antígenos CD28/imunologia , Interferon gama/imunologia , Células Th1/imunologia , Animais , Anticorpos Monoclonais/imunologia , Antígenos CD40/imunologia , Ligante de CD40/imunologia , Humanos , Ativação Linfocitária/imunologia , Camundongos , Transdução de Sinais/imunologiaRESUMO
For the control of immunity in COVID-19 survivors and vaccinated subjects, there is an urgent need for reliable and rapid serological assays. Based on samples from 63 COVID-19 survivors up to 7 months after symptom onset, and on 50 serum samples taken before the beginning of the pandemic, we compared the performances of three commercial immunoassays for the detection of SARS-CoV-2 IgA and IgG antibodies (Euroimmun SARS-COV-2 IgA/IgG, Mikrogen recomWell SARS-CoV-2 IgA/IgG, and Serion ELISA agile SARS-CoV-2 IgA/IgG) and three rapid lateral flow (immunochromatographic) tests (Abbott PanBio COVID-19 IgG/IgM, Nadal COVID-19 IgG/IgM, and Cleartest Corona 2019-nCOV IgG/IgM) with a 50% plaque-reduction neutralization test (PRNT50) representing the gold standard. Fifty-seven out of 63 PCR-confirmed COVID-19 patients (90%) showed neutralizing antibodies. The sensitivity of the seven assays ranged from 7.0% to 98.3%, and the specificity ranged from 86.0% to 100.0%. Only one commercial immunoassay showed a sensitivity and specificity of greater than 98%.
Assuntos
COVID-19 , SARS-CoV-2 , Anticorpos Antivirais , Humanos , Imunoensaio , Imunoglobulina M , Pandemias , Sensibilidade e EspecificidadeRESUMO
Once biological systems are modeled by regulatory networks, the next step is to include external stimuli, which model the experimental possibilities to affect the activity level of certain network's nodes, in a mathematical framework. Then, this framework can be interpreted as a mathematical optimal control framework such that optimization algorithms can be used to determine external stimuli which cause a desired switch from an initial state of the network to another final state. These external stimuli are the intervention points for the corresponding biological experiment to obtain the desired outcome of the considered experiment. In this work, the model of regulatory networks is extended to controlled regulatory networks. For this purpose, external stimuli are considered which can affect the activity of the network's nodes by activation or inhibition. A method is presented how to calculate a selection of external stimuli which causes a switch between two different steady states of a regulatory network. A software solution based on Jimena and Mathworks Matlab is provided. Furthermore, numerical examples are presented to demonstrate application and scope of the software on networks of 4 nodes, 11 nodes and 36 nodes. Moreover, we analyze the aggregation of platelets and the behavior of a basic T-helper cell protein-protein interaction network and its maturation towards Th0, Th1, Th2, Th17 and Treg cells in accordance with experimental data.
Assuntos
Simulação por Computador , Modelos Biológicos , Mapas de Interação de Proteínas , Linfócitos T Auxiliares-Indutores/metabolismoRESUMO
Cation homeostasis, in relation to various immune-suppressive diseases, is a novel field of investigation. Recently, patients with a loss-of-function mutation in magnesium transporter 1 (MAGT1) were reported to present a dysregulated Mg2+ homeostasis in T lymphocytes. Using Magt1-knockout mice (Magt1-/y ), we show that Mg2+ homeostasis was impaired in Magt1-/y B cells and Ca2+ influx was increased after BCR stimulation, whereas T and NK cell function was unaffected. Consequently, mutant B cells displayed an increased phosphorylation of BCR-related proteins differentially affecting protein kinase C activation. These in vitro findings translated into increased frequencies of CD19+ B cells and marginal zone B cells and decreased frequencies of plasma cells among CD45+ splenocytes in vivo. Altogether, our study demonstrates for the first time, to our knowledge, that abolished MAGT1 function causes imbalanced cation homeostasis and developmental responses in B cells. Therefore, this study might contribute to a further understanding of B cell-related pathologies.
Assuntos
Linfócitos B/metabolismo , Linfócitos B/fisiologia , Proteínas de Transporte de Cátions/metabolismo , Cátions/metabolismo , Hematopoese/fisiologia , Homeostase/fisiologia , Animais , Antígenos CD19/metabolismo , Cálcio/metabolismo , Células Matadoras Naturais/metabolismo , Células Matadoras Naturais/fisiologia , Antígenos Comuns de Leucócito/metabolismo , Ativação Linfocitária/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Quinase C/metabolismo , Transdução de Sinais/fisiologia , Linfócitos T/metabolismo , Linfócitos T/fisiologiaRESUMO
In recent years, the myocardium has been rediscovered under the lenses of immunology, and lymphocytes have been implicated in the pathogenesis of cardiomyopathies with different etiologies. Aging is an important risk factor for heart diseases, and it also has impact on the immune system. Thus, we sought to determine whether immunological activity would influence myocardial structure and function in elderly mice. Morphological, functional, and molecular analyses revealed that the age-related myocardial impairment occurs in parallel with shifts in the composition of tissue-resident leukocytes and with an accumulation of activated CD4+ Foxp3- (forkhead box P3) IFN-γ+ T cells in the heart-draining lymph nodes. A comprehensive characterization of different aged immune-deficient mouse strains revealed that T cells significantly contribute to age-related myocardial inflammation and functional decline. Upon adoptive cell transfer, the T cells isolated from the mediastinal lymph node (med-LN) of aged animals exhibited increased cardiotropism, compared with cells purified from young donors or from other irrelevant sites. Nevertheless, these cells caused rather mild effects on cardiac functionality, indicating that myocardial aging might stem from a combination of intrinsic and extrinsic (immunological) factors. Taken together, the data herein presented indicate that heart-directed immune responses may spontaneously arise in the elderly, even in the absence of a clear tissue damage or concomitant infection. These observations might shed new light on the emerging role of T cells in myocardial diseases, which primarily affect the elderly population.
Assuntos
Envelhecimento/imunologia , Linfócitos T CD4-Positivos/imunologia , Miocárdio/imunologia , Transferência Adotiva , Animais , Coração/crescimento & desenvolvimento , Humanos , Linfonodos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Donor lymphocyte infusions together with allogeneic hematopoietic stem cell transplantation are routinely used as second-line treatment for hematological malignancies. Mature T cells in the graft crucially mediate a graft versus leukemia (GvL) response, but also attack healthy tissues in the recipient leading to potentially life-threatening acute graft versus host disease. Using inducible CD28 knockout C57BL/6 mice as T-cell donors, we have now assessed whether CD28 costimulation of donor CD4+ and/ or CD8+ T cells is required for an efficient GvL effect after allogeneic T-cell transplantation into BALB/c recipients. Our results show that CD28 costimulation of donor CD8+ cytotoxic, but not CD4+ helper, T cells was dispensable for curing mice from the BCL-1 lymphoma. Therefore, donor lymphocyte infusion treated lymphoma-bearing BALB/c recipient mice showed enhanced long-term survival when receiving CD28-deficient as compared to wild-type donor CD8+ T cells together with wild-type conventional and regulatory CD4+ T cells. The same was observed when donor CD8+ and conventional and regulatory CD4+ T cells were CD28 deficient. Our data, thus, suggest that systemic CD28 blockade, for example, with the drug FR104 might also reduce acute graft versus host disease in patients after allogeneic hematopoietic stem cell transplantation, while maintaining the protective GvL response.
Assuntos
Antígenos CD28/metabolismo , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Doença Enxerto-Hospedeiro/imunologia , Efeito Enxerto vs Leucemia/imunologia , Transplante de Células-Tronco Hematopoéticas , Linfoma/imunologia , Doença Aguda , Animais , Antígenos CD28/genética , Linfócitos T CD4-Positivos/transplante , Linfócitos T CD8-Positivos/transplante , Células Cultivadas , Ciclina D1/genética , Modelos Animais de Doenças , Humanos , Transfusão de Linfócitos , Linfoma/terapia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Doadores de Tecidos , Transplante HomólogoRESUMO
Acid sphingomyelinase (ASM) is the rate-limiting enzyme cleaving sphingomyelin into ceramide and phosphorylcholin. CD4+ Foxp3+ regulatory T (Treg) cells depend on CD28 signaling for their survival and function, a receptor that activates the ASM. Both, basal and CD28-induced ASM activities are higher in Treg cells than in conventional CD4+ T (Tconv) cells. In ASM-deficient (Smpd1-/-) as compared to wt mice, membranes of T cells contain 7-10-fold more sphingomyelin and two- to three-fold more ceramide, and are in a state of higher order than membranes of T cells from wt mice, which may facilitate their activation. Indeed, the frequency of Treg cells among CD4+ T cells in ASM-deficient mice and their suppressive activity in vitro are increased. Moreover, in vitro stimulation of ASM-deficient T cells in the presence of TGF-ß and IL-2 leads to higher numbers of induced Treg cells. Pharmacological inhibition of the ASM with a clinically used tricyclic antidepressant such as amitriptyline in mice or in tissue culture of murine or human T cells induces higher frequencies of Treg cells among CD4+ T cells within a few days. This fast alteration of the balance between T cell populations in vitro is due to the elevated cell death of Tconv cells and protection of the CD25high Treg cells by IL-2. Together, these findings suggest that ASM-inhibiting antidepressants, including a fraction of the serotonin re-uptake inhibitors (SSRIs), are moderately immunosuppressive and should be considered for the therapy of inflammatory and autoimmune disorders.
Assuntos
Amitriptilina/farmacologia , Antidepressivos/farmacologia , Fatores de Transcrição Forkhead/metabolismo , Imunomodulação/efeitos dos fármacos , Esfingomielina Fosfodiesterase/antagonistas & inibidores , Linfócitos T Reguladores/imunologia , Animais , Doenças Autoimunes/terapia , Humanos , Inflamação/terapia , Camundongos , Esfingomielina Fosfodiesterase/deficiência , Esfingomielina Fosfodiesterase/metabolismo , Linfócitos T Reguladores/metabolismoRESUMO
Nonalcoholic fatty liver disease is increasing in prevalence. It can be subdivided into nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). Five to twenty percent of cases progress from NAFL to NASH. Increased hepatic Th17 cells and IL-17 expression were observed in NASH mice and patients, respectively. We analyzed CD4(+) effector T cells and regulatory T cells (Tregs) from peripheral blood and livers of NAFL and NASH patients. A total of 51 NAFL patients, 30 NASH patients, 31 nonalcoholic fatty liver disease patients (without histology), and 43 healthy controls were included. FACS analysis was performed on PBMCs and intrahepatic lymphocytes. Compared with healthy controls, a lower frequency of resting Tregs (rTregs; CD4(+)CD45RA(+)CD25(++)) and higher frequencies of IFN-γ(+) and/or IL-4(+) cells were detected among CD4(+) T cells of peripheral blood in NASH, and to a lesser degree in NAFL. In hepatic tissue, NAFL to NASH progression was marked by an increase in IL-17(+) cells among intrahepatic CD4(+) T cells. To define immunological parameters in peripheral blood to distinguish NAFL from NASH, we calculated different ratios. Th17/rTreg and Th2/rTreg ratios were significantly increased in NASH versus NAFL. The relevance of our findings for NASH pathogenesis was highlighted by the normalization of all of the changes 1 y after bariatric surgery. In conclusion, our data indicate that NAFL patients show changes in their immune cell profile compared with healthy controls. NAFL to NASH progression is marked by an increased frequency of IL-17(+) cells among intrahepatic CD4(+) T cells and higher Th17/rTreg and Th2/rTreg ratios in peripheral blood.
Assuntos
Fígado/citologia , Hepatopatia Gordurosa não Alcoólica/patologia , Linfócitos T Reguladores/imunologia , Células Th17/imunologia , Células Th2/imunologia , Adulto , Animais , Cirurgia Bariátrica , Células Cultivadas , Progressão da Doença , Feminino , Humanos , Interferon gama/imunologia , Interleucina-17/biossíntese , Interleucina-4/imunologia , Fígado/patologia , Contagem de Linfócitos , Masculino , Camundongos , Pessoa de Meia-Idade , Estudos ProspectivosRESUMO
CD4+ Foxp3+ regulatory T cells (Tregs) depend on CD28 signaling for their survival and function, a receptor that has been previously shown to activate the acid sphingomyelinase (Asm)/ceramide system. In this article, we show that the basal and CD28-induced Asm activity is higher in Tregs than in conventional CD4+ T cells (Tconvs) of wild-type (wt) mice. In Asm-deficient (Smpd1-/-; Asm-/-) mice, as compared with wt mice, the frequency of Tregs among CD4+ T cells, turnover of the effector molecule CTLA-4, and their suppressive activity in vitro were increased. The biological significance of these findings was confirmed in our Treg-sensitive mouse model of measles virus (MV) CNS infection, in which we observed more infected neurons and less MV-specific CD8+ T cells in brains of Asm-/- mice compared with wt mice. In addition to genetic deficiency, treatment of wt mice with the Asm inhibitor amitriptyline recapitulated the phenotype of Asm-deficient mice because it also increased the frequency of Tregs among CD4+ T cells. Reduced absolute cell numbers of Tconvs after inhibitor treatment in vivo and extensive in vitro experiments revealed that Tregs are more resistant toward Asm inhibitor-induced cell death than Tconvs. Mechanistically, IL-2 was capable of providing crucial survival signals to the Tregs upon inhibitor treatment in vitro, shifting the Treg/Tconv ratio to the Treg side. Thus, our data indicate that Asm-inhibiting drugs should be further evaluated for the therapy of inflammatory and autoimmune disorders.
Assuntos
Encéfalo/imunologia , Sarampo/imunologia , Morbillivirus/imunologia , Esfingomielina Fosfodiesterase/metabolismo , Subpopulações de Linfócitos T/imunologia , Linfócitos T Reguladores/imunologia , Animais , Encéfalo/virologia , Antígenos CD28/metabolismo , Antígenos CD4/metabolismo , Diferenciação Celular , Sobrevivência Celular , Células Cultivadas , Ceramidas/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Interleucina-2/metabolismo , Ativação Linfocitária , Sarampo/enzimologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Esfingomielina Fosfodiesterase/genética , Subpopulações de Linfócitos T/virologia , Linfócitos T Reguladores/virologiaRESUMO
OBJECTIVE: The present study analyzed the effect of CD4+ Forkhead box protein 3 negative (Foxp3-) T-cells and Foxp3+ CD4+ T-cells on infarct size in a mouse myocardial ischemia-reperfusion model. APPROACH AND RESULTS: We examined the infarct size as a fraction of the area-at-risk as primary study endpoint in mice after 30minutes of coronary ligation followed by 24hours of reperfusion. CD4+ T-cell deficient MHC-II KO mice showed smaller histologically determined infarct size (34.5±4.7% in MHCII KO versus 59.4±4.9% in wildtype (WT)) and better preserved ejection fraction determined by magnetic resonance tomography (56.9±2.8% in MHC II KO versus 39.0±4.2% in WT). MHC-II KO mice also displayed better microvascular perfusion than WT mice after 24hours of reperfusion. Also CD4+ T-cell sufficient OT-II mice, which express an in this context irrelevant T-cell receptor, revealed smaller infarct sizes compared to WT mice. However, MHC-II blocking anti-I-A/I-E antibody treatment was not able to reduce infarct size indicating that autoantigen recognition is not required for the activation of CD4+ T-cells during reperfusion. Flow-cytometric analysis also did not detect CD4+ T-cell activation in heart draining lymph nodes in response to 24hours of ischemia-reperfusion. Adoptive transfer of CD4+ T-cells in CD4 KO mice increased the infarct size only when including the Foxp3+ CD25+ subset. Depletion of CD4+ Foxp3+ T-cells in DEREG mice enabling specific conditional ablation of this subset by treatment with diphtheria toxin attenuated infarct size as compared to diphtheria toxin treated WT mice. CONCLUSIONS: CD4+ Foxp3+ T-cells enhance myocardial ischemia-reperfusion injury. CD4+ T-cells exert injurious effects without the need for prior activation by MHC-II restricted autoantigen recognition.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Traumatismo por Reperfusão Miocárdica/etiologia , Traumatismo por Reperfusão Miocárdica/metabolismo , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Transferência Adotiva , Animais , Biomarcadores , Modelos Animais de Doenças , Epitopos de Linfócito T/imunologia , Fatores de Transcrição Forkhead/metabolismo , Masculino , Camundongos , Camundongos Knockout , Infarto do Miocárdio/diagnóstico , Infarto do Miocárdio/etiologia , Infarto do Miocárdio/metabolismo , Traumatismo por Reperfusão Miocárdica/diagnóstico , Traumatismo por Reperfusão Miocárdica/terapiaRESUMO
Upon transplantation of T cells from a CD28 superagonist (CD28-SA) treated donor into an irradiated allogeneic host, the CD28-SA-induced activation and expansion of Treg cells inhibits acute graft versus host disease (aGvHD), while not abrogating the desired graft versus tumor effect. Human peripheral blood CD4(+) T cells, however, harbor only very few Treg cells. Therefore, we studied whether polyclonal in vitro prestimulation of conventional, that is Treg -cell-depleted, CD4(+) T cells of C57BL/6 mice with CD28-SA-coated paramagnetic beads is sufficient to protect recipient BALB/c mice from aGvHD. CD28-SA prestimulation of conventional CD4(+) T cells efficiently protected BALB/c recipient mice from aGvHD and CD28-SA-stimulated CD4(+) and CD8(+) T cells were capable of mediating long-term protection from the BCL1 lymphoma. The recently completed successful phase I testing of the human CD28-SA TGN1412/TAB08 should greatly facilitate further development of this straightforward method into a novel immunotherapy for patients.
Assuntos
Transplante de Medula Óssea/métodos , Antígenos CD28/agonistas , Linfócitos T CD4-Positivos/imunologia , Doença Enxerto-Hospedeiro/prevenção & controle , Ativação Linfocitária/imunologia , Aloenxertos , Animais , Transplante de Medula Óssea/efeitos adversos , Linfócitos T CD8-Positivos/imunologia , Técnicas de Cultura de Células/métodos , Separação Celular , Modelos Animais de Doenças , Citometria de Fluxo , Doença Enxerto-Hospedeiro/imunologia , Técnicas In Vitro , Linfoma/terapia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BLRESUMO
Anergic T cells can survive for long time periods passively in a hyporesponsive state without obvious active functions. Thus, the immunological reason for their maintenance is unclear. Here, we induced peptide-specific anergy in T cells from mice by coculturing these cells with immature murine dendritic cells (DCs). We found that these anergic, nonsuppressive IL-10(-) Foxp3(-) CTLA-4(+) CD25(low) Egr2(+) T cells could be converted into suppressive IL-10(+) Foxp3(-) CTLA-4(+) CD25(high) Egr2(+) cells resembling type-1 Treg cells (Tr1) when stimulated a second time by immature DCs in vitro. Addition of TGF-ß during anergy induction favored Foxp3(+) Treg-cell induction, while TGF-ß had little effect when added to the second stimulation. Expression of both CD28 and CTLA-4 molecules on anergic T cells was required to allow their conversion into Tr1-like cells. Suppressor activity was enabled via CD28-mediated CD25 upregulation, acting as an IL-2 sink, together with a CTLA-4-mediated inhibition of NFATc1/α activation to shut down IL-2-mediated proliferation. Together, these data provide evidence and mechanistical insights into how persistent anergic T cells may serve as a resting memory pool for Tr1-like cells.