RESUMO
The functions of Nr4a1-dependent Ly6C(low) monocytes remain enigmatic. We show that they are enriched within capillaries and scavenge microparticles from their lumenal side in a steady state. In the kidney cortex, perturbation of homeostasis by a TLR7-dependent nucleic acid "danger" signal, which may signify viral infection or local cell death, triggers Gαi-dependent intravascular retention of Ly6C(low) monocytes by the endothelium. Then, monocytes recruit neutrophils in a TLR7-dependent manner to mediate focal necrosis of endothelial cells, whereas the monocytes remove cellular debris. Prevention of Ly6C(low) monocyte development, crawling, or retention in Nr4a1(-/-), Itgal(-/-), and Tlr7(host-/-BM+/+) and Cx3cr1(-/-) mice, respectively, abolished neutrophil recruitment and endothelial killing. Prevention of neutrophil recruitment in Tlr7(host+/+BM-/-) mice or by neutrophil depletion also abolished endothelial cell necrosis. Therefore, Ly6C(low) monocytes are intravascular housekeepers that orchestrate the necrosis by neutrophils of endothelial cells that signal a local threat sensed via TLR7 followed by the in situ phagocytosis of cellular debris.
Assuntos
Células Endoteliais/metabolismo , Monitorização Imunológica , Monócitos/imunologia , Animais , Moléculas de Adesão Celular/metabolismo , Micropartículas Derivadas de Células , Endotélio Vascular/citologia , Endotélio Vascular/imunologia , Humanos , Inflamação , Molécula 1 de Adesão Intercelular/metabolismo , Rim/irrigação sanguínea , Rim/metabolismo , Receptores de Lipopolissacarídeos/metabolismo , Antígeno-1 Associado à Função Linfocitária/metabolismo , Camundongos , Monócitos/metabolismo , Neutrófilos/imunologia , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/metabolismo , Receptores de Quimiocinas/metabolismoRESUMO
Upon its mucosal transmission, HIV type 1 (HIV-1) rapidly targets genital antigen-presenting Langerhans cells (LCs), which subsequently transfer infectious virus to CD4+ T cells. We previously described an inhibitory neuroimmune cross talk, whereby calcitonin gene-related peptide (CGRP), a neuropeptide secreted by peripheral pain-sensing nociceptor neurons innervating all mucosal epithelia and associating with LCs, strongly inhibits HIV-1 transfer. As nociceptors secret CGRP following the activation of their Ca2+ ion channel transient receptor potential vanilloid 1 (TRPV1), and as we reported that LCs secret low levels of CGRP, we investigated whether LCs express functional TRPV1. We found that human LCs expressed mRNA and protein of TRPV1, which was functional and induced Ca2+ influx following activation with TRPV1 agonists, including capsaicin (CP). The treatment of LCs with TRPV1 agonists also increased CGRP secretion, reaching its anti-HIV-1 inhibitory concentrations. Accordingly, CP pretreatment significantly inhibited LCs-mediated HIV-1 transfer to CD4+ T cells, which was abrogated by both TRPV1 and CGRP receptor antagonists. Like CGRP, CP-induced inhibition of HIV-1 transfer was mediated via increased CCL3 secretion and HIV-1 degradation. CP also inhibited direct CD4+ T cells HIV-1 infection, but in CGRP-independent manners. Finally, pretreatment of inner foreskin tissue explants with CP markedly increased CGRP and CCL3 secretion, and upon subsequent polarized exposure to HIV-1, inhibited an increase in LC-T cell conjugate formation and consequently T cell infection. Our results reveal that TRPV1 activation in human LCs and CD4+ T cells inhibits mucosal HIV-1 infection, via CGRP-dependent/independent mechanisms. Formulations containing TRPV1 agonists, already approved for pain relief, could hence be useful against HIV-1.
Assuntos
Peptídeo Relacionado com Gene de Calcitonina , Infecções por HIV , Humanos , Peptídeo Relacionado com Gene de Calcitonina/farmacologia , Linfócitos T/metabolismo , Células de Langerhans/metabolismo , Mucosa/metabolismo , Capsaicina/farmacologia , Dor/metabolismo , Infecções por HIV/metabolismo , Canais de Cátion TRPV/genética , Canais de Cátion TRPV/metabolismoRESUMO
CD4+Foxp3+ regulatory T (Treg) cells are central modulators of autoimmune diseases. However, the timing and location of Treg cell-mediated suppression of tissue-specific autoimmunity remain undefined. Here, we addressed these questions by investigating the role of tumor necrosis factor (TNF) receptor 2 (TNFR2) signaling in Treg cells during experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis. We found that TNFR2-expressing Treg cells were critical to suppress EAE at peak disease in the central nervous system but had no impact on T cell priming in lymphoid tissues at disease onset. Mechanistically, TNFR2 signaling maintained functional Treg cells with sustained expression of CTLA-4 and Blimp-1, allowing active suppression of pathogenic T cells in the inflamed central nervous system. This late effect of Treg cells was further confirmed by treating mice with TNF and TNFR2 agonists and antagonists. Our findings show that endogenous Treg cells specifically suppress an autoimmune disease by acting in the target tissue during overt inflammation. Moreover, they bring a mechanistic insight to some of the adverse effects of anti-TNF therapy in patients.
Assuntos
Encefalomielite Autoimune Experimental/imunologia , Esclerose Múltipla/imunologia , Receptores Tipo II do Fator de Necrose Tumoral/metabolismo , Linfócitos T Reguladores/imunologia , Animais , Medula Óssea/patologia , Antígeno CTLA-4/metabolismo , Sistema Nervoso Central/imunologia , Sistema Nervoso Central/patologia , Encefalomielite Autoimune Experimental/tratamento farmacológico , Encefalomielite Autoimune Experimental/patologia , Humanos , Camundongos , Camundongos Knockout , Esclerose Múltipla/tratamento farmacológico , Esclerose Múltipla/patologia , Fator 1 de Ligação ao Domínio I Regulador Positivo/metabolismo , Receptores Tipo II do Fator de Necrose Tumoral/agonistas , Receptores Tipo II do Fator de Necrose Tumoral/antagonistas & inibidores , Receptores Tipo II do Fator de Necrose Tumoral/genética , Transdução de Sinais/imunologia , Linfócitos T Reguladores/metabolismoRESUMO
Clinical observations suggest that the source of primary infection accounts for a major determinant of further nosocomial pneumonia in critically ill patients with sepsis. Here we addressed the impact of primary nonpulmonary or pulmonary septic insults on lung immunity using relevant double-hit animal models. C57BL/6J mice were first subjected to polymicrobial peritonitis induced by cecal ligation and puncture (CLP) or bacterial pneumonia induced by intratracheal challenge with Escherichia coli. Seven days later, postseptic mice received ab intratracheal challenge with Pseudomonas aeruginosa. Compared with controls, post-CLP mice became highly susceptible to P. aeruginosa pneumonia, as demonstrated by defective lung bacterial clearance and increased mortality rate. In contrast, all postpneumonia mice survived the P. aeruginosa challenge and even exhibited improved bacterial clearance. Nonpulmonary and pulmonary sepsis differentially modulated the amounts and some important immune functions of alveolar macrophages. Additionally, we observed a Toll-like receptor 2 (TLR2)-dependent increase in regulatory T cells (Tregs) in lungs from post-CLP mice. Antibody-mediated Treg depletion restored the numbers and functions of alveolar macrophages in post-CLP mice. Furthermore, post-CLP TLR2-deficient mice were found resistant to secondary P. aeruginosa pneumonia. In conclusion, polymicrobial peritonitis and bacterial pneumonia conferred susceptibility or resistance to secondary gram-negative pulmonary infection, respectively. Immune patterns in post-CLP lungs argue for a TLR2-dependent cross-talk between Tregs and alveolar macrophages as an important regulatory mechanism in postseptic lung defense.
Assuntos
Peritonite , Pneumonia Bacteriana , Sepse , Animais , Camundongos , Macrófagos Alveolares , Receptor 2 Toll-Like , Modelos Animais de Doenças , Camundongos Endogâmicos C57BL , Pulmão , Sepse/complicações , Peritonite/complicaçõesRESUMO
Emerging data highlight the crucial role of enzymes involved in amino acid metabolism in immune cell biology. IL-4-induced gene-1 (IL4I1), a secreted l-phenylalanine oxidase expressed by APCs, has been detected in B cells, yet its immunoregulatory role has only been explored on T cells. In this study, we show that IL4I1 regulates multiple steps in B cell physiology. Indeed, IL4I1 knockout mice exhibit an accelerated B cell egress from the bone marrow, resulting in the accumulation of peripheral follicular B cells. They also present a higher serum level of natural Igs and self-reactive Abs. We also demonstrate that IL4I1 produced by B cells themselves controls the germinal center reaction, plasma cell differentiation, and specific Ab production in response to T dependent Ags, SRBC, and NP-KLH. In vitro, IL4I1-deficient B cells proliferate more efficiently than their wild-type counterparts in response to BCR cross-linking. Moreover, the absence of IL4I1 increases activation of the Syk-Akt-S6kinase signaling pathway and calcium mobilization, and inhibits SHP-1 activity upon BCR engagement, thus supporting that IL4I1 negatively controls BCR-dependent activation. Overall, our study reveals a new perspective on IL4I1 as a key regulator of B cell biology.
Assuntos
Aminoácido Oxirredutases/genética , Linfócitos B/citologia , Flavoproteínas/genética , Ativação Linfocitária/imunologia , Receptores de Antígenos de Linfócitos B/imunologia , Aminoácido Oxirredutases/metabolismo , Animais , Linfócitos B/imunologia , Diferenciação Celular/imunologia , Flavoproteínas/metabolismo , Imunoglobulinas/sangue , L-Aminoácido Oxidase , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Tirosina Fosfatase não Receptora Tipo 6/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas Quinases S6 Ribossômicas/metabolismo , Transdução de Sinais/fisiologia , Quinase Syk/metabolismoRESUMO
Failure of the immune system to eradicate viruses results in chronic viral infections, which are associated with increased susceptibility to secondary infections. Pathogenic HIV or lymphocytic choriomeningitis virus chronic infections display a persistent type I IFN signature. In chronic lymphocytic choriomeningitis virus infection, blockade of type I IFN signaling partially restores antiviral responses. In a mouse model, we tested whether chronic administration of type I IFN, at doses mimicking chronic viral infection, induced immunosuppression. Chronic exposure of mice to IFN-α alone was sufficient to strongly suppress specific CD8+ T cells responses to subsequent vaccinia virus infection. It resulted in the accumulation of Ly6Chi monocytes. These monocytes were similar, phenotypically and functionally, to the myeloid-derived suppressor cells found in cancer because they exerted a potent suppression on CD8+ T cell responses in vitro. They acted at least partly through the l-arginine pathway. In vivo, their elimination restored antiviral CD8+ T cell responses. Our work provides a specific mechanism accounting for the role of IFN-α in immunosuppression and predicts that type I IFN modulation will be pivotal to cure human chronic infections, cancer, or autoimmune diseases.
Assuntos
Tolerância Imunológica/efeitos dos fármacos , Interferon Tipo I/farmacologia , Células Supressoras Mieloides/efeitos dos fármacos , Animais , Linfócitos T CD8-Positivos/imunologia , Células Dendríticas/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Células Supressoras Mieloides/fisiologia , Viroses/imunologiaRESUMO
So far, peripheral T cells have mostly been described to circulate between blood, secondary lymphoid organs (SLOs), and lymph in the steady state. This nomadic existence would allow them to accomplish their surveying task for both foreign Ags and survival signals. Although it is now well established that γδ T cells can be rapidly recruited to inflammatory sites or in certain tumor microenvironments, the trafficking properties of peripheral γδ T cells have been poorly studied in the steady state. In the present study, we highlight the existence of resident γδ T cells in the SLOs of specific pathogen-free mice. Indeed, using several experimental approaches such as the injection of integrin-neutralizing Abs that inhibit the entry of circulating lymphocytes into lymph nodes and long-term parabiosis experiments, we have found that, contrary to Ly-6C-/+CD44lo and Ly-6C+CD44hi γδ T cells, a significant proportion of Ly-6C-CD44hi γδ T cells are trapped for long periods of time within lymph nodes and the spleen in the steady state. Specific in vivo cell depletion strategies have allowed us to demonstrate that macrophages are the main actors involved in this long-term retention of Ly-6C-CD44hi γδ T cells in SLOs.
Assuntos
Linfonodos/imunologia , Macrófagos/imunologia , Baço/imunologia , Subpopulações de Linfócitos T/imunologia , Linfócitos T/imunologia , Animais , Antígenos Ly/metabolismo , Comunicação Celular , Movimento Celular , Células Cultivadas , Receptores de Hialuronatos/metabolismo , Imunidade Inata , Vigilância Imunológica , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Receptores de Antígenos de Linfócitos T gama-delta/metabolismoRESUMO
Severe sepsis remains a frequent and dreaded complication in cancer patients. Beyond the often fatal short-term outcome, the long-term sequelae of severe sepsis may also impact directly on the prognosis of the underlying malignancy in survivors. The immune system is involved in all stages of tumour development, in the detection of transforming and dying cells and in the prevention of tumour growth and dissemination. In fact, the profound and sustained immune defects induced by sepsis may constitute a privileged environment likely to favour tumour growth. We investigated the impact of sepsis on malignant tumour growth in a double-hit animal model of polymicrobial peritonitis, followed by subcutaneous inoculation of MCA205 fibrosarcoma cells. As compared to their sham-operated counterparts, post-septic mice exhibited accelerated tumour growth. This was associated with intratumoural accumulation of CD11b(+) Ly6G(high) polymorphonuclear cells (PMNs) that could be characterized as granulocytic myeloid-derived suppressor cells (G-MDSCs). Depletion of granulocytic cells in post-septic mice inhibited the sepsis-enhanced tumour growth. Toll-like receptor (TLR)-4 (Tlr4) and Myd88 deficiencies prevented sepsis-induced expansion of G-MDSCs and tumour growth. Our results demonstrate that the myelosuppressive environment induced by severe bacterial infections promotes malignant tumour growth, and highlight a critical role of CD11b(+) Ly6G(high) G-MDSCs under the control of TLR-dependent signalling. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Assuntos
Fibrossarcoma/patologia , Granulócitos/patologia , Células Supressoras Mieloides/patologia , Peritonite/patologia , Receptor 4 Toll-Like/metabolismo , Animais , Linhagem Celular Tumoral , Modelos Animais de Doenças , Progressão da Doença , Fibrossarcoma/complicações , Fibrossarcoma/metabolismo , Granulócitos/metabolismo , Camundongos , Camundongos Knockout , Células Supressoras Mieloides/metabolismo , Peritonite/complicações , Peritonite/metabolismoRESUMO
To better apprehend γ/δ T cell biological functions in the periphery, it appears crucial to identify markers highlighting the existence of distinct phenotypic and functional γ/δ T cell subsets. Interestingly, the expression of CD44 and Ly-6C subdivides murine peripheral γ/δ T cells into several subsets, with Ly-6C(-) CD44(hi) γ/δ T cells corresponding to the IL-17-producing CD27(-) γ/δ T cell subset exhibiting innate-like features. By comparing the other subsets to naive and memory CD8(+) α/ß T cells, in this study, we show that Ly-6C(- or +) CD44(lo) and Ly-6C(+)CD44(hi) γ/δ T cells greatly resemble, and behave like, their CD8(+) α/ß T cell counterparts. First, like memory CD8(+) α/ß T cells, Ly-6C(+)CD44(hi) γ/δ T cells are sparse in the thymus but largely increased in proportion in tissues. Second, similarly to naive CD8 α/ß T cells, CD44(lo) γ/δ T cells are poorly cycling in vivo in the steady state, and their proportion declines with age in secondary lymphoid organs. Third, CD44(lo) γ/δ T cells undergo spontaneous proliferation and convert to a memory-like Ly-6C(+)CD44(hi) phenotype in response to lymphopenia. Finally, CD44(lo) γ/δ T cells have an intrinsic high plasticity as, upon appropriate stimulation, they are capable of differentiating nonetheless into Th17-like and Th1-like cells but also into fully functional Foxp3(+) induced regulatory T cell-like γ/δ T cells. Thus, peripheral CD27(+) γ/δ T cells, commonly considered as a functionally related T cell compartment, actually share many common features with adaptive α/ß T cells, as both lineages include naive-like and memory-like lymphocytes with distinct phenotypic, functional, and homeostatic characteristics.
Assuntos
Imunidade Adaptativa , Receptores de Antígenos de Linfócitos T alfa-beta/metabolismo , Receptores de Antígenos de Linfócitos T gama-delta/metabolismo , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Animais , Antígenos Ly/genética , Antígenos Ly/metabolismo , Expressão Gênica , Homeostase , Receptores de Hialuronatos/genética , Receptores de Hialuronatos/metabolismo , Imunofenotipagem , Interleucina-17/biossíntese , Linfopenia/imunologia , Linfopenia/metabolismo , Camundongos , Camundongos Knockout , Fenótipo , Transdução de Sinais , Membro 7 da Superfamília de Receptores de Fatores de Necrose TumoralRESUMO
An uncontrolled exaggerated Th17 response can drive the onset of autoimmune and inflammatory diseases. In this study, we show that, in T cells, Foxo1 is a negative regulator of the Th17 program. Using mixed bone marrow chimeras and Foxo1-deficient mice, we demonstrate that this control is effective in vivo, as well as in vitro during differentiation assays of naive T cells with specific inhibitor of Foxo1 or inhibitors of the PI3K/Akt pathway acting upstream of Foxo1. Consistently, expressing this transcription factor in T cells strongly decreases Th17 generation in vitro as well as transcription of both IL-17A and IL-23R RORγt-target genes. Finally, at the molecular level, we demonstrate that Foxo1 forms a complex with RORγt via its DNA binding domain to inhibit RORγt activity. We conclude that Foxo1 is a direct antagonist of the RORγt-Th17 program acting in a T cell-intrinsic manner.
Assuntos
Fatores de Transcrição Forkhead/metabolismo , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/metabolismo , Subpopulações de Linfócitos T/metabolismo , Células Th17/metabolismo , Animais , Diferenciação Celular/genética , Linhagem Celular , Proteína Forkhead Box O1 , Fatores de Transcrição Forkhead/deficiência , Fatores de Transcrição Forkhead/genética , Humanos , Imunofenotipagem , Interleucina-17/genética , Interleucina-17/metabolismo , Contagem de Linfócitos , Camundongos , Camundongos Knockout , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/antagonistas & inibidores , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/química , Fenótipo , Fosfatidilinositol 3-Quinases/metabolismo , Regiões Promotoras Genéticas , Domínios e Motivos de Interação entre Proteínas , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/imunologia , Células Th17/citologia , Células Th17/imunologia , Transcrição GênicaRESUMO
CD4 regulatory T cells (Tregs) can be subdivided into two subsets according to Ly-6C expression in the periphery. Phenotypic analysis, imaging, and adoptive-transfer experiments of peripheral Ly-6C(-) and Ly-6C(+) Tregs reveal that the nonexpression of Ly-6C by â¼70% of peripheral Tregs depends on TCR signaling events. Interestingly, Ly-6C(-) Tregs express higher surface amounts of key immunosuppressive molecules than do Ly-6C(+) Tregs and produce constitutively anti-inflammatory cytokines. In line with their phenotype, Ly-6C(+) Tregs exhibit poor suppressive capacities in vitro and in vivo. Finally, although Ly-6C(-) Tregs maintain their numbers with age, Ly-6C(+) Tregs gradually disappear. Altogether, our data strongly suggest that both the survival and suppressive functions of peripheral CD4 Tregs rely on their ability to receive strong TCR signals.
Assuntos
Imunomodulação , Receptores de Antígenos de Linfócitos T/metabolismo , Transdução de Sinais , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Fatores Etários , Envelhecimento/imunologia , Animais , Antígenos Ly/genética , Antígenos Ly/metabolismo , Antígenos de Superfície/genética , Antígenos de Superfície/metabolismo , Expressão Gênica , Imunofenotipagem , Linfonodos/imunologia , Linfonodos/metabolismo , Ativação Linfocitária/genética , Ativação Linfocitária/imunologia , Camundongos , Camundongos Transgênicos , FenótipoRESUMO
The present study evaluates the impact of immune cell populations on metastatic development in a model of spontaneous melanoma [mice expressing the human RET oncogene under the control of the metallothionein promoter (MT/ret mice)]. In this model, cancer cells disseminate early but remain dormant for several weeks. Then, MT/ret mice develop cutaneous metastases and, finally, distant metastases. A total of 35% of MT/ret mice develop a vitiligo, a skin depigmentation attributable to the lysis of normal melanocytes, associated with a delay in tumor progression. Here, we find that regulatory CD4(+) T cells accumulate in the skin, the spleen, and tumor-draining lymph nodes of MT/ret mice not developing vitiligo. Regulatory T-cell depletion and IL-10 neutralization led to increased occurrence of vitiligo that correlated with a decreased incidence of melanoma metastases. In contrast, inflammatory monocytes/dendritic cells accumulate in the skin of MT/ret mice with active vitiligo. Moreover, they inhibit tumor cell proliferation in vitro through a reactive oxygen species-dependent mechanism, and both their depletion and reactive oxygen species neutralization in vivo increased tumor cell dissemination. Altogether, our data suggest that regulatory CD4(+) T cells favor tumor progression, in part, by inhibiting recruitment and/or differentiation of inflammatory monocytes in the skin.
Assuntos
Inflamação/imunologia , Melanoma/imunologia , Monócitos/imunologia , Linfócitos T Reguladores/imunologia , Animais , Proliferação de Células , Feminino , Citometria de Fluxo , Humanos , Inflamação/genética , Inflamação/patologia , Linfonodos/imunologia , Linfonodos/metabolismo , Linfonodos/patologia , Masculino , Melanoma/genética , Melanoma/patologia , Metalotioneína/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Monócitos/metabolismo , Metástase Neoplásica , Regiões Promotoras Genéticas/genética , Proteínas Proto-Oncogênicas c-ret/genética , Proteínas Proto-Oncogênicas c-ret/imunologia , Espécies Reativas de Oxigênio/imunologia , Espécies Reativas de Oxigênio/metabolismo , Pele/imunologia , Pele/metabolismo , Pele/patologia , Baço/imunologia , Baço/metabolismo , Linfócitos T Reguladores/metabolismo , Fatores de Tempo , Vitiligo/genética , Vitiligo/imunologiaAssuntos
Linfócitos T CD4-Positivos/metabolismo , Células Dendríticas/fisiologia , Homeostase/fisiologia , Tecido Linfoide/citologia , Animais , Linfócitos T CD4-Positivos/imunologia , Humanos , Linfonodos/fisiologia , Sistema Linfático/fisiologia , Linfócitos/fisiologia , Tecido Linfoide/fisiologiaRESUMO
VE-cadherin-mediated cell-cell junction weakening increases paracellular permeability in response to both angiogenic and inflammatory stimuli. Although Semaphorin 3A has emerged as one of the few known anti-angiogenic factors to exhibit pro-permeability activity, little is known about how it triggers vascular leakage. Here we report that Semaphorin 3A induced VE-cadherin serine phosphorylation and internalisation, cell-cell junction destabilisation, and loss of barrier integrity in brain endothelial cells. In addition, high-grade glioma-isolated tumour-initiating cells were found to secrete Semaphorin 3A, which promoted brain endothelial monolayer permeability. From a mechanistic standpoint, Semaphorin 3A impinged upon the basal activity of the serine phosphatase PP2A and disrupted PP2A interaction with VE-cadherin, leading to cell-cell junction disorganization and increased permeability. Accordingly, both pharmacological inhibition and siRNA-based knockdown of PP2A mimicked Semaphorin 3A effects on VE-cadherin. Hence, local Semaphorin 3A production impacts on the PP2A/VE-cadherin equilibrium and contributes to elevated vascular permeability.
Assuntos
Permeabilidade da Membrana Celular , Células Endoteliais/enzimologia , Células Endoteliais/patologia , Proteína Fosfatase 2/metabolismo , Semaforina-3A/metabolismo , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Neoplasias Encefálicas/enzimologia , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Ativação Enzimática , Glioma/enzimologia , Glioma/metabolismo , Glioma/patologia , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Células-Tronco Neoplásicas/metabolismo , Proteína Fosfatase 2/antagonistas & inibidores , Quinases da Família src/metabolismoRESUMO
Work over the last decades has led to the identification of the factors that influence the survival and homeostasis of conventional T cells. IL-7 and TCR signaling promote the survival of naive CD4(+) and CD8(+) T cells in lymphoreplete mice and their proliferation in a lymphopenic environment, whereas survival and homeostatic proliferation of memory CD4(+) and CD8(+) T cells crucially depend on a combination of IL-7 and IL-15. In contrast, there is little information regarding the factors driving the proliferation of regulatory CD4(+) T cells in response to lymphopenia. In this study, we investigated whether regulatory CD4(+) T cell proliferation in response to lymphopenia was guided by classical homeostatic resources, such as IL-2, IL-7, or TCR-MHC interactions. Altogether, our data suggest that, although homeostatic proliferation of conventional naive CD4(+) T cells is closely related to IL-7 levels, the proliferation of regulatory CD4(+) T cells in response to lymphopenia appears to be primarily controlled by IL-2. The capacity of IL-7 to augment conventional T cell proliferation with minimal concomitant regulatory T cell expansion may be clinically exploitable in the treatment of patients with lymphopenia, especially in the case of chronic viral diseases or cancer immunotherapy.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Compartimento Celular/imunologia , Homeostase/imunologia , Interleucina-2/fisiologia , Interleucina-7/fisiologia , Animais , Linfócitos T CD4-Positivos/patologia , Linfócitos T CD4-Positivos/transplante , Compartimento Celular/genética , Ciclo Celular/genética , Ciclo Celular/imunologia , Proliferação de Células , Células Cultivadas , Genes Reporter , Homeostase/genética , Linfopenia/genética , Linfopenia/imunologia , Linfopenia/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Linfócitos T Reguladores/citologia , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismoRESUMO
Foxo family transcription factors are critically involved in multiple processes, such as metabolism, quiescence, cell survival and cell differentiation. Although continuous, high activity of Foxo transcription factors extends the life span of some species, the involvement of Foxo proteins in mammalian aging remains to be determined. Here, we show that Foxo1 is down-regulated with age in mouse T cells. This down-regulation of Foxo1 in T cells may contribute to the disruption of naive T-cell homeostasis with age, leading to an increase in the number of memory T cells. Foxo1 down-regulation is also associated with the up-regulation of co-inhibitory receptors by memory T cells and exhaustion in aged mice. Using adoptive transfer experiments, we show that the age-dependent down-regulation of Foxo1 in T cells is mediated by T-cell-extrinsic cues, including type 1 interferons. Taken together, our data suggest that type 1 interferon-induced Foxo1 down-regulation is likely to contribute significantly to T-cell dysfunction in aged mice.
Assuntos
Fatores de Transcrição Forkhead , Exaustão das Células T , Camundongos , Animais , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Regulação para Baixo , Proteína Forkhead Box O1/genética , Proteína Forkhead Box O1/metabolismo , Diferenciação Celular , Proteínas/metabolismo , Interferons/metabolismo , Mamíferos/metabolismoRESUMO
Cancers only develop if they escape immunosurveillance, and the success of cancer immunotherapies relies in most cases on their ability to restore effector T-cell functions, particularly IFNγ production. Revolutionizing the treatment of many cancers, immunotherapies targeting immune checkpoints such as PD1 can increase survival and cure patients. Unfortunately, although immunotherapy has greatly improved the prognosis of patients, not all respond to anti-PD1 immunotherapy, making it crucial to identify alternative treatments that could be combined with current immunotherapies to improve their effectiveness. Here, we show that iron supplementation significantly boosts T-cell responses in vivo and in vitro. The boost was associated with a metabolic reprogramming of T cells in favor of lipid oxidation. We also found that the "adjuvant" effect of iron led to a marked slowdown of tumor cell growth after tumor cell line transplantation in mice. Specifically, our results suggest that iron supplementation promotes antitumor responses by increasing IFNγ production by T cells. In addition, iron supplementation improved the efficacy of anti-PD1 cancer immunotherapy in mice. Finally, our study suggests that, in patients with cancer, the quality and efficacy of the antitumor response following anti-PD1 immunotherapy may be modulated by plasma ferritin levels. In summary, our results suggest the benefits of iron supplementation on the reactivation of antitumor responses and support the relevance of a fruitful association between immunotherapy and iron supplementation.
Assuntos
Imunoterapia , Ferro , Receptor de Morte Celular Programada 1 , Animais , Camundongos , Ferro/metabolismo , Imunoterapia/métodos , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Humanos , Linhagem Celular Tumoral , Camundongos Endogâmicos C57BL , Inibidores de Checkpoint Imunológico/farmacologia , Inibidores de Checkpoint Imunológico/uso terapêutico , Interferon gama/metabolismo , Feminino , Células Th1/imunologia , Neoplasias/imunologia , Neoplasias/terapia , Neoplasias/tratamento farmacológicoRESUMO
In the periphery, Foxp3 expression is considered sufficient to maintain natural regulatory CD4(+) T-cell suppressive function. In this study, we challenge this model. Indeed, in mouse chimeras in which major histocompatibility complex (MHC) class II expression is restricted to the thymus, peripheral regulatory CD4(+) T cells lack suppressive activity. In addition, regulatory CD4(+) T cells recovered 5 days after transfer into recipient mice lacking expression of MHC class II molecules (self-deprived) are unable to inhibit the proliferative response of conventional CD4(+) T cells both in vitro and in vivo. Disruption of TCR/MHC class II interactions rapidly leads to alterations in the regulatory CD4(+) T-cell phenotype, the ability to respond to stimulation and to produce interleukin-10, and the transcriptional signature. Interestingly, self-deprivation does not affect Foxp3 expression indicating that in regulatory CD4(+) T cells, self-recognition induces unique transcriptional and functional features that do not rely on Foxp3 expression.
Assuntos
Fatores de Transcrição Forkhead/fisiologia , Tolerância Imunológica , Linfócitos T Reguladores/imunologia , Animais , Células Cultivadas , Quimera/imunologia , Técnicas de Cocultura , Antígenos de Histocompatibilidade Classe II/fisiologia , Interleucina-10/biossíntese , Interleucina-10/fisiologia , Ativação Linfocitária/imunologia , Camundongos , Receptores de Antígenos de Linfócitos T/fisiologia , Transcriptoma/imunologiaRESUMO
OBJECTIVE: Systemic sclerosis (SSc) is a debilitating autoimmune disease characterized by severe lung outcomes resulting in reduced life expectancy. Fra-2-transgenic mice offer the opportunity to decipher the relationships between the immune system and lung fibrosis. This study was undertaken to investigate whether the Fra-2-transgenic mouse lung phenotype may result from an imbalance between the effector and regulatory arms in the CD4+ T cell compartment. METHODS: We first used multicolor flow cytometry to extensively characterize homeostasis and the phenotype of peripheral CD4+ T cells from Fra-2-transgenic mice and control mice. We then tested different treatments for their effectiveness in restoring CD4+ Treg cell homeostasis, including adoptive transfer of Treg cells and treatment with low-dose interleukin-2 (IL-2). RESULTS: Fra-2-transgenic mice demonstrated a marked decrease in the proportion and absolute number of peripheral Treg cells that preceded accumulation of activated, T helper cell type 2-polarized, CD4+ T cells. This defect in Treg cell homeostasis was derived from a combination of mechanisms including impaired generation of these cells in both the thymus and the periphery. The impaired ability of peripheral conventional CD4+ T cells to produce IL-2 may greatly contribute to Treg cell deficiency in Fra-2-transgenic mice. Notably, adoptive transfer of Treg cells, low-dose IL-2 therapy, or combination therapy changed the phenotype of Fra-2-transgenic mice, resulting in a significant reduction in pulmonary parenchymal fibrosis and vascular remodeling in the lungs. CONCLUSION: Immunotherapies for restoring Treg cell homeostasis could be relevant in SSc. An intervention based on low-dose IL-2 injections, as is already proposed in other autoimmune diseases, could be the most suitable treatment modality for restoring Treg cell homeostasis for future research.
Assuntos
Fibrose Pulmonar , Escleroderma Sistêmico , Animais , Linfócitos T CD4-Positivos , Modelos Animais de Doenças , Interleucina-2 , Camundongos , Camundongos Transgênicos , Fibrose Pulmonar/metabolismo , Linfócitos T Reguladores , Remodelação VascularRESUMO
Lymphopenia is thought to be a major cause of tolerance breakdown. In a lymphopenic environment, self-recognition events induce some T cells to expand strongly (a mechanism known as spontaneous proliferation). In this study, we show that in C57BL/6 mice, the repertoire resulting from lymphopenia-induced spontaneous CD4(+) T-cell proliferation included a proportion of regulatory T cells as large as that observed in a normal mouse, and no autoimmune disorder was observed. By contrast, in nonobese diabetic mice, differences in the ability of conventional and regulatory T cells to expand in response to lymphopenia led to an unbalance between these 2 T-cell compartments at the expense of regulatory T cells, resulting in the onset of autoimmune diseases. Notably, this accounted for the rapid transfer of diabetes with small numbers of BDC2.5 CD4(+) T cells. Thus, lymphopenia does not itself induce autoimmunity, but it should be considered as a cofactor for the development of autoimmune disorders.