RESUMO
Chronic viruses and cancers thwart immune responses in humans by inducing T cell dysfunction. Using a murine chronic virus that models human infections, we investigated the function of the adhesion molecule, P-selectin glycoprotein ligand-1 (PSGL-1), that is upregulated on responding T cells. PSGL-1-deficient mice cleared the virus due to increased intrinsic survival of multifunctional effector T cells that had downregulated PD-1 as well as other inhibitory receptors. Notably, this response resulted in CD4(+)-T-cell-dependent immunopathology. Mechanistically, PSGL-1 ligation on exhausted CD8(+) T cells inhibited T cell receptor (TCR) and interleukin-2 (IL-2) signaling and upregulated PD-1, leading to diminished survival with TCR stimulation. In models of melanoma cancer in which T cell dysfunction occurs, PSGL-1 deficiency led to PD-1 downregulation, improved T cell responses, and tumor control. Thus, PSGL-1 plays a fundamental role in balancing viral control and immunopathology and also functions to regulate T cell responses in the tumor microenvironment.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Coriomeningite Linfocítica/imunologia , Vírus da Coriomeningite Linfocítica/imunologia , Melanoma/imunologia , Glicoproteínas de Membrana/metabolismo , Animais , Modelos Animais de Doenças , Humanos , Evasão da Resposta Imune , Interleucina-2/metabolismo , Ativação Linfocitária , Glicoproteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptor de Morte Celular Programada 1/genética , Receptor de Morte Celular Programada 1/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Transdução de SinaisRESUMO
MicroRNAs (miRNAs/miRs) are small, endogenous noncoding RNAs that are important post-transcriptional regulators with clear roles in the development of the immune system and immune responses. Using miRNA microarray profiling, we characterized the expression profile of naive and in vivo generated murine effector antiviral CD8+ T cells. We observed that out of 362 measurable mature miRNAs, 120 were differentially expressed by at least 2-fold in influenza-specific effector CD8+ CTLs compared with naive CD8+ T cells. One miRNA found to be highly downregulated on both strands in effector CTLs was miR-139. Because previous studies have indicated a role for miR-139-mediated regulation of CTL effector responses, we hypothesized that deletion of miR-139 would enhance antiviral CTL responses during influenza virus infection. We generated miR-139-/- mice or overexpressed miR-139 in T cells to assess the functional contribution of miR-139 expression in CD8+ T cell responses. Our study demonstrates that the development of naive T cells and generation or differentiation of effector or memory CD8+ T cell responses to influenza virus infection are not impacted by miR-139 deficiency or overexpression; yet, miR-139-/- CD8+ T cells are outcompeted by wild-type CD8+ T cells in a competition setting and demonstrate reduced responses to Listeria monocytogenes Using an in vitro model of T cell exhaustion, we confirmed that miR-139 expression similarly does not impact the development of T cell exhaustion. We conclude that despite significant downregulation of miR-139 following in vivo and in vitro activation, miR-139 expression is dispensable for influenza-specific CTL responses.
Assuntos
Vírus da Influenza A/imunologia , Listeria monocytogenes/imunologia , MicroRNAs/genética , Infecções por Orthomyxoviridae/imunologia , Linfócitos T Citotóxicos/imunologia , Animais , Regulação para Baixo/genética , Feminino , Ativação Linfocitária/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transdução de Sinais/imunologiaRESUMO
P-selectin glycoprotein ligand-1 (PSGL-1) has long been studied as an adhesion molecule involved in immune cell trafficking and is recognized as a regulator of many facets of immune responses by myeloid cells. PSGL-1 also regulates T cell migration during homeostasis and inflammatory settings. However, recent findings indicate that PSGL-1 can also negatively regulate T cell function. Because T cell differentiation is finely tuned by multiple positive and negative regulatory signals that appropriately scale the magnitude of the immune response, PSGL-1 has emerged as an important checkpoint during this process. We summarize what is known regarding PSGL-1 structure and function and highlight how it may act as an immune checkpoint inhibitor in T cells.
Assuntos
Movimento Celular/imunologia , Glicoproteínas de Membrana/imunologia , Transdução de Sinais/imunologia , Linfócitos T/imunologia , Animais , Adesão Celular/imunologia , Humanos , Ativação Linfocitária/imunologia , Glicoproteínas de Membrana/metabolismo , Modelos Imunológicos , Receptores de Antígenos de Linfócitos T/imunologia , Linfócitos T/metabolismoRESUMO
BACKGROUND: Adolescence is a critical period for neural development, and alcohol exposure during adolescence can lead to an elevated risk for health consequences as well as alcohol use disorders. Clinical and experimental data suggest that chronic alcohol exposure may produce immunomodulatory effects that can lead to the activation of pro-inflammatory cytokine pathways as well as microglial markers. The present study evaluated, in brain and blood, the effects of adolescent alcohol exposure and withdrawal on microglia and on the most representative pro- and anti-inflammatory cytokines and major chemokines that can contribute to the establishing of a neuroinflammatory environment. METHODS: Wistar rats (males, n = 96) were exposed to ethanol (EtOH) vapors, or air control, for 5 weeks over adolescence (PD22-PD58). Brains and blood samples were collected at 3 time points: (i) after 35 days of vapor/air exposure (PD58); (ii) after 1 day of withdrawal (PD59), and (iii) 28 days after withdrawal (PD86). The ionized calcium-binding adapter molecule 1 (Iba-1) was used to index microglial activation, and cytokine/chemokine responses were analyzed using magnetic bead panels. RESULTS: After 35 days of adolescent vapor exposure, a significant increase in Iba-1 immunoreactivity was seen in amygdala, frontal cortex, hippocampus, and substantia nigra. However, Iba-1 density returned to control levels at both 1 day and 28 days of withdrawal except in the hippocampus where Iba-1 density was significantly lower than controls. In serum, adolescent EtOH exposure induced a reduction in IL-13 and an increase in fractalkine at day 35. After 1 day of withdrawal, IL-18 was reduced, and IP-10 was elevated, whereas both IP-10 and IL-10 were elevated at 28 days following withdrawal. In the frontal cortex, adolescent EtOH exposure induced an increase in IL-1ß at day 35, and 28 days of withdrawal, and IL-10 was increased after 28 days of withdrawal. CONCLUSION: These data demonstrate that EtOH exposure during adolescence produces significant microglial activation; however, inflammatory markers seen in the blood appear to differ from those observed in the brain.
Assuntos
Encéfalo/metabolismo , Citocinas/metabolismo , Etanol/efeitos adversos , Síndrome de Abstinência a Substâncias/metabolismo , Fatores Etários , Animais , Proteínas de Ligação ao Cálcio/metabolismo , Citocinas/sangue , Masculino , Proteínas dos Microfilamentos/metabolismo , Microglia/metabolismo , Ratos , Síndrome de Abstinência a Substâncias/sangue , Fatores de TempoRESUMO
Targeted deletion of BAFF causes severe deficiency of splenic B cells. BAFF-R is commonly thought to signal to nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB)-inducing kinase dependent noncanonical NF-κB RelB. However, RelB-deficient mice have normal B-cell numbers. Recent studies showed that BAFF also signals to the canonical NF-κB pathway, and we found that both RelB and cRel are persistently activated, suggesting BAFF signaling coordinates both pathways to ensure robust B-cell development. Indeed, we report now that combined loss of these 2 NF-κB family members leads to impaired BAFF-mediated survival and development in vitro. Although single deletion of RelB and cRel was dispensable for normal B-cell development, double knockout mice displayed an early B-cell developmental blockade and decreased mature B cells. Despite disorganized splenic architecture in Relb(-/-)cRel(-/-) mice, generation of mixed-mouse chimeras established the developmental phenotype to be B-cell intrinsic. Together, our results indicate that BAFF signals coordinate both RelB and cRel activities to ensure survival during peripheral B-cell maturation.
Assuntos
Linfócitos B/metabolismo , Proteínas Proto-Oncogênicas c-ret/metabolismo , Transdução de Sinais/fisiologia , Fator de Transcrição RelB/metabolismo , Animais , Fator Ativador de Células B/genética , Fator Ativador de Células B/metabolismo , Receptor do Fator Ativador de Células B/genética , Receptor do Fator Ativador de Células B/metabolismo , Linfócitos B/citologia , Sobrevivência Celular/genética , Camundongos , Camundongos Knockout , Proteínas Proto-Oncogênicas c-ret/genética , Fator de Transcrição RelB/genéticaRESUMO
IFN-ß is widely used in the treatment of multiple sclerosis, yet the mechanism facilitating its efficacy remains unclear. IL-2 production by activated T cells, including those mediating autoimmunity, and subsequent autocrine stimulation is vital for T cell expansion and function. In this study, we demonstrate that in mouse and human T cells, IFN-ß specifically inhibits the production of IL-2 upon TCR engagement without affecting other cytokines or activation markers. Rather than disrupting TCR signaling, IFN-ß alters histone modifications in the IL-2 promoter to retain the locus in an inaccessible configuration. This in turn is mediated through the upregulation of the transcriptional suppressor CREM by IFN-ß and consequent recruitment of histone deacetylases to the IL-2 promoter. In accordance, ablation of CREM expression or inhibition of histone deacetylases activity eliminates the suppressive effects of IFN-ß on IL-2 production. Collectively, these findings provide a molecular basis by which IFN-ß limits T cell responses.
Assuntos
Montagem e Desmontagem da Cromatina/efeitos dos fármacos , Modulador de Elemento de Resposta do AMP Cíclico/metabolismo , Interferon beta/farmacologia , Interleucina-2/antagonistas & inibidores , Linfócitos T Reguladores/imunologia , Animais , Infecções por Arenaviridae/imunologia , Células Cultivadas , Modulador de Elemento de Resposta do AMP Cíclico/genética , Inibidores de Histona Desacetilases , Histona Desacetilases/genética , Histonas/genética , Humanos , Interleucina-2/biossíntese , Ativação Linfocitária/imunologia , Vírus da Coriomeningite Linfocítica/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Esclerose Múltipla/imunologia , Regiões Promotoras Genéticas/genética , Interferência de RNA , RNA Interferente Pequeno , Receptor de Interferon alfa e beta , Receptores de Antígenos de Linfócitos T/imunologiaRESUMO
The contributions of IFN regulatory factor (IRF) 3/7 and the type I IFNs IFN-α/ß to the innate host defense have been extensively investigated; however, their role in thymic development is less clear. In this study, we show that mice lacking the type I IFN receptor IFN-α/ß receptor (IFNAR) or the downstream transcription factor STAT1 harbor a significant reduction in self-Ag-presenting, autoimmune regulator (AIRE)(+) medullary thymic epithelial cells (mTECs). Constitutive IFNAR signaling occurs in the thymic medulla in the absence of infection or inflammation. Receptor activator for NF-κB (RANK) ligand stimulation results in IFN-ß upregulation, which in turn inhibits RANK signaling and facilitates AIRE expression in mTECs. Finally, we find that IRF7 is required for thymic IFN-ß induction, maintenance of thymic architecture, and mTEC differentiation. We conclude that spatially and temporally coordinated cross talks between the RANK ligand/RANK and IRF7/IFN-ß/IFNAR/STAT1 pathways are essential for differentiation of AIRE(+) mTECs.
Assuntos
Células Epiteliais/metabolismo , Fator Regulador 7 de Interferon/genética , Interferon beta/biossíntese , Ligante RANK/farmacologia , Timo/metabolismo , Animais , Células Epiteliais/efeitos dos fármacos , Fator Regulador 7 de Interferon/metabolismo , Camundongos , Camundongos Knockout , Receptor Ativador de Fator Nuclear kappa-B/metabolismo , Receptor de Interferon alfa e beta/genética , Receptor de Interferon alfa e beta/metabolismo , Fator de Transcrição STAT1/genética , Fator de Transcrição STAT1/metabolismo , Transdução de Sinais , Células Estromais/efeitos dos fármacos , Células Estromais/metabolismo , Timo/efeitos dos fármacos , Fatores de Transcrição/metabolismo , Enzimas de Conjugação de Ubiquitina/metabolismo , Proteína AIRERESUMO
PSGL-1 (P-selectin glycoprotein-1) is a T cell-intrinsic checkpoint regulator of exhaustion with an unknown mechanism of action. Here, we show that PSGL-1 acts upstream of PD-1 and requires co-ligation with the T cell receptor (TCR) to attenuate activation of mouse and human CD8+ T cells and drive terminal T cell exhaustion. PSGL-1 directly restrains TCR signaling via Zap70 and maintains expression of the Zap70 inhibitor Sts-1. PSGL-1 deficiency empowers CD8+ T cells to respond to low-affinity TCR ligands and inhibit growth of PD-1-blockade-resistant melanoma by enabling tumor-infiltrating T cells to sustain an elevated metabolic gene signature supportive of increased glycolysis and glucose uptake to promote effector function. This outcome is coupled to an increased abundance of CD8+ T cell stem cell-like progenitors that maintain effector functions. Additionally, pharmacologic blockade of PSGL-1 curtails T cell exhaustion, indicating that PSGL-1 represents an immunotherapeutic target for PD-1-blockade-resistant tumors.
Assuntos
Linfócitos T CD8-Positivos , Receptor de Morte Celular Programada 1 , Humanos , Linfócitos T CD8-Positivos/metabolismo , Diferenciação Celular , Receptor de Morte Celular Programada 1/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Exaustão das Células TRESUMO
Understanding the mechanisms underlying anti-tumor immunity is pivotal for improving immune-based cancer therapies. Here, we report that growth of BRAF-mutant melanoma cells is inhibited, up to complete rejection, in Siah2-/- mice. Growth-inhibited tumors exhibit increased numbers of intra-tumoral activated T cells and decreased expression of Ccl17, Ccl22, and Foxp3. Marked reduction in Treg proliferation and tumor infiltration coincide with G1 arrest in tumor infiltrated Siah2-/- Tregs in vivo or following T cell stimulation in culture, attributed to elevated expression of the cyclin-dependent kinase inhibitor p27, a Siah2 substrate. Growth of anti-PD-1 therapy resistant melanoma is effectively inhibited in Siah2-/- mice subjected to PD-1 blockade, indicating synergy between PD-1 blockade and Siah2 loss. Low SIAH2 and FOXP3 expression is identified in immune responsive human melanoma tumors. Overall, Siah2 regulation of Treg recruitment and cell cycle progression effectively controls melanoma development and Siah2 loss in the host sensitizes melanoma to anti-PD-1 therapy.
Assuntos
Melanoma/imunologia , Proteínas Nucleares/imunologia , Linfócitos T Reguladores/imunologia , Ubiquitina-Proteína Ligases/imunologia , Animais , Quimiocina CCL17/genética , Quimiocina CCL17/imunologia , Quimiocina CCL22/genética , Quimiocina CCL22/imunologia , Proteína Forkhead Box O3/genética , Proteína Forkhead Box O3/imunologia , Humanos , Melanoma/genética , Camundongos , Camundongos Knockout , Proteínas Nucleares/genética , Ubiquitina-Proteína Ligases/genéticaRESUMO
Alcohol produces complex effects on the immune system. Moderate alcohol use (1-2 drinks per day) has been shown to produce anti-inflammatory responses in human blood monocytes, whereas, the post mortem brains of severe alcoholics show increased immune gene expression and activated microglial markers. The present study was conducted to evaluate the time course of alcohol effects during exposure and after withdrawal, and to determine the relationship between microglial and cytokine responses in brain and blood. Forty-eight adult, male Wistar rats were exposed to chronic ethanol vapors, or air control, for 5 weeks. Following ethanol/air exposure blood and brains were collected at three time points: 1) while intoxicated, following 35 days of air/vapor exposure; 2) following 24 h of withdrawal from exposure, and 3) 28 days after withdrawal. One hemisphere of the brain was flash-frozen for cytokine analysis, and the other was fixed for immunohistochemical analysis. The ionized calcium-binding adapter molecule 1 (Iba-1) was used to evaluate microglia activation at the three time points, and rat cytokine/chemokine Magnetic Bead Panels (Millipore) were used to analyze frontal cortex tissue lysate and serum. Ethanol induced a significant increase in Iba-1 that peaked at day 35, remained significant after 1 day of withdrawal, and was elevated at day 28 in frontal cortex, amygdala, and substantia nigra. Ethanol exposure was associated with a transient reduction of the serum level of the major pro- and anti-inflammatory cytokines and chemokines and a transient increase of effectors of sterile inflammation. Little or no changes in these molecules were seen in the frontal cortex except for HMG1 and fractalkine that were reduced and elevated, respectively, at day 28 following withdrawal. These data show that ethanol exposure produces robust microglial activation; however, measures of inflammation in the blood differ from those in the brain over a protracted time course.
Assuntos
Citocinas/metabolismo , Etanol/farmacologia , Lobo Frontal/metabolismo , Microglia/efeitos dos fármacos , Síndrome de Abstinência a Substâncias/metabolismo , Animais , Proteínas de Ligação ao Cálcio/metabolismo , Citocinas/sangue , Masculino , Proteínas dos Microfilamentos/metabolismo , Ratos , Síndrome de Abstinência a Substâncias/sangue , Fatores de TempoRESUMO
Effective adaptive immune responses are characterized by stages of development and maturation of T and B cell populations that respond to disturbances in the host homeostasis in cases of both infections and cancer. For the T cell compartment, this begins with recognition of specific peptides by naïve, antigen-inexperienced T cells that results in their activation, proliferation, and differentiation, which generates an effector population that clears the antigen. Loss of stimulation eventually returns the host to a homeostatic state, with a heterogeneous memory T cell population that persists in the absence of antigen and is primed for rapid responses to a repeat antigen exposure. However, in chronic infections and cancers, continued antigen persistence impedes a successful adaptive immune response and the formation of a stereotypical memory population of T cells is compromised. With repeated antigen stimulation, responding T cells proceed down an altered path of differentiation that allows for antigen persistence, but much less is known regarding the heterogeneity of these cells and the extent to which they can become "memory-like," with a capacity for self-renewal and recall responses that are characteristic of bona fide memory cells. This review focuses on the differentiation of CD4+ and CD8+ T cells in the context of chronic antigen stimulation, highlighting the central observations in both human and mouse studies regarding the differentiation of memory or "memory-like" T cells. The importance of both the cellular and molecular drivers of memory T cell development are emphasized to better understand the consequences of persisting antigen on T cell fates. Integrating what is known and is common across model systems and patients can instruct future studies aimed at further understanding T cell differentiation and development, with the goal of developing novel methods to direct T cells toward the generation of effective memory populations.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Memória Imunológica/imunologia , Animais , Antígenos/imunologia , Diferenciação Celular/imunologia , HumanosRESUMO
Although the B-cell antigen receptor (BCR) factors most prominently in the maintenance and differentiation of mature B cells, it is now appreciated that co-receptor molecules can positively or negatively modulate signals through the BCR. Co-receptors are functionally defined as modifiers of BCR engagement and signal transduction, and are distinct from other accessory molecules that act independently to regulate B-cell growth. The co-receptor CD19 functions to augment signals by the pre-BCR/BCR and in doing so can modulate B-cell fate decisions at multiple stages of development. In mature B cells, CD19 also associates with complement receptor 2 (CR2/CD21) and is pivotal for transducing signals induced by co-recognition of complement C3d-fixed antigens by the BCR and CD21. In this article, we focus on recent progress in the understanding of CD19 function through the characterization of mouse models that relate in vivo function to biochemical properties of CD19.
Assuntos
Antígenos CD19/fisiologia , Subpopulações de Linfócitos B/citologia , Subpopulações de Linfócitos B/imunologia , Diferenciação Celular/fisiologia , Animais , Subpopulações de Linfócitos B/metabolismo , Diferenciação Celular/imunologia , Humanos , Receptores de Antígenos de Linfócitos B/fisiologia , Transdução de Sinais/fisiologiaRESUMO
BAFF, an activator of the noncanonical NFκB pathway, provides critical survival signals during B cell maturation and contributes to B cell proliferation. We found that the NFκB family member RelB is required ex vivo for B cell maturation, but cRel is required for proliferation. Combined molecular network modeling and experimentation revealed Nfkb2 p100 as a pathway switch; at moderate p100 synthesis rates in maturing B cells, BAFF fully utilizes p100 to generate the RelB:p52 dimer, whereas at high synthesis rates, p100 assembles into multimeric IκBsome complexes, which BAFF neutralizes in order to potentiate cRel activity and B cell expansion. Indeed, moderation of p100 expression or disruption of IκBsome assembly circumvented the BAFF requirement for full B cell expansion. Our studies emphasize the importance of p100 in determining distinct NFκB network states during B cell biology, which causes BAFF to have context-dependent functional consequences.
Assuntos
Fator Ativador de Células B/metabolismo , Linfócitos B/metabolismo , Proliferação de Células , NF-kappa B/metabolismo , Transdução de Sinais , Animais , Fator Ativador de Células B/genética , Linfócitos B/citologia , Linfócitos B/fisiologia , Diferenciação Celular , Proteínas I-kappa B/genética , Proteínas I-kappa B/metabolismo , Camundongos , Modelos Biológicos , NF-kappa B/genética , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismoRESUMO
Mice lacking the Jak tyrosine kinase member Tyk2 become progressively obese due to aberrant development of Myf5+ brown adipose tissue (BAT). Tyk2 RNA levels in BAT and skeletal muscle, which shares a common progenitor with BAT, are dramatically decreased in mice placed on a high-fat diet and in obese humans. Expression of Tyk2 or the constitutively active form of the transcription factor Stat3 (CAStat3) restores differentiation in Tyk2(-/-) brown preadipocytes. Furthermore, Tyk2(-/-) mice expressing CAStat3 transgene in BAT also show improved BAT development, normal levels of insulin, and significantly lower body weights. Stat3 binds to PRDM16, a master regulator of BAT differentiation, and enhances the stability of PRDM16 protein. These results define Tyk2 and Stat3 as critical determinants of brown fat lineage and suggest that altered levels of Tyk2 are associated with obesity in both rodents and humans.
Assuntos
Tecido Adiposo Marrom/metabolismo , Obesidade/metabolismo , Fator de Transcrição STAT3/metabolismo , TYK2 Quinase/metabolismo , Tecido Adiposo Marrom/citologia , Tecido Adiposo Marrom/crescimento & desenvolvimento , Animais , Diferenciação Celular , Células Cultivadas , Proteínas de Ligação a DNA/metabolismo , Humanos , Insulina , Camundongos , Camundongos Knockout , Obesidade/patologia , Ligação Proteica , Fator de Transcrição STAT3/genética , TYK2 Quinase/deficiência , TYK2 Quinase/genética , Fatores de Transcrição/metabolismo , Redução de PesoRESUMO
STAT1 is an essential part of interferon signaling, and STAT1-deficiency results in heightened susceptibility to infections or autoimmunity in both mice and humans. Here we report that mice lacking the IFNα/ß-receptor (IFNAR1) or STAT1 display impaired deletion of autoreactive CD4(+)CD8(+)-T-cells. Strikingly, co-existence of WT T cells restored thymic elimination of self-reactive STAT1-deficient CD4(+)CD8(+)-T cells. Analysis of STAT1-deficient thymocytes further revealed reduced Bim expression, which was restored in the presence of WT T cells. These results indicate that type I interferons and STAT1 play an important role in the survival of MHC class I-restricted T cells in a T cell intrinsic and non-cell intrinsic manner that involves regulation of Bim expression through feedback provided by mature STAT1-competent T cells.
Assuntos
Apoptose/imunologia , Receptor de Interferon alfa e beta/fisiologia , Fator de Transcrição STAT1/fisiologia , Linfócitos T/imunologia , Timócitos/citologia , Timócitos/metabolismo , Transferência Adotiva , Animais , Proteínas Reguladoras de Apoptose/metabolismo , Proteína 11 Semelhante a Bcl-2 , Ciclo Celular , Diferenciação Celular , Citometria de Fluxo , Complexo Principal de Histocompatibilidade , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Proteínas Proto-Oncogênicas/metabolismo , Transdução de Sinais , Linfócitos T/metabolismo , Timócitos/imunologiaRESUMO
Non-coding microRNAs (miRs) are a vital component of post-transcriptional modulation of protein expression and, like coding mRNAs harbour oncogenic properties. However, the mechanisms governing miR expression and the identity of the affected transcripts remain poorly understood. Here we identify the inositol phosphatase SHIP1 as a bonafide target of the oncogenic miR-155. We demonstrate that in diffuse large B cell lymphoma (DLBCL) elevated levels of miR-155, and consequent diminished SHIP1 expression are the result of autocrine stimulation by the pro-inflammatory cytokine tumour necrosis factor a (TNFalpha). Anti-TNFalpha regimen such as eternacept or infliximab were sufficient to reduce miR-155 levels and restored SHIP1 expression in DLBCL cells with an accompanying reduction in cell proliferation. Furthermore, we observed a substantial decrease in tumour burden in DLBCL xenografts in response to eternacept. These findings strongly support the concept that cytokine-regulated miRs can function as a crucial link between inflammation and cancer, and illustrate the feasibility of anti-TNFalpha therapy as a novel and immediately accessible (co)treatment for DLBCL.
Assuntos
Proliferação de Células , Linfoma de Células B/fisiopatologia , MicroRNAs/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Linhagem Celular Tumoral , Expressão Gênica , Humanos , Inositol Polifosfato 5-Fosfatases , Linfoma de Células B/genética , Linfoma de Células B/metabolismo , Camundongos , Camundongos SCID , MicroRNAs/genética , Transplante de Neoplasias , Fosfatidilinositol-3,4,5-Trifosfato 5-Fosfatases , Monoéster Fosfórico Hidrolases/genética , Transporte Proteico , Fator de Necrose Tumoral alfa/genéticaRESUMO
Mice lacking activity of the kinase MEKK1 ('Map3k1(deltaKD)' mice) have defective activation of the kinase Jnk and increased production of T helper type 2 cytokines after T cell receptor ligation. Here we show that Map3k1(deltaKD) mice had defective germinal center formation and diminished production of antibodies recognizing thymus-dependent antigens. Those defects were B cell intrinsic, as MEKK1 was necessary for CD40-mediated activation of the kinases Jnk and p38 and transcription factor c-Jun, as well as for expression of cyclin D2 and activation-induced deaminase. MEKK1 was recruited to CD40 and adaptor molecule TRAF2 after CD40 ligation, and Map3k1(deltaKD) B cells were hypoproliferative after CD40 stimulation. Our data emphasize that MEKK1 is an essential component of signaling cascades needed for thymus-dependent antigen-induced B cell proliferation and antibody production.
Assuntos
Formação de Anticorpos/imunologia , Linfócitos B/imunologia , Antígenos CD40/metabolismo , Centro Germinativo/imunologia , Ativação Linfocitária/imunologia , MAP Quinase Quinase 4/metabolismo , MAP Quinase Quinase Quinase 1/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Animais , Linfócitos B/citologia , MAP Quinase Quinase Quinase 1/genética , Camundongos , Transdução de Sinais/imunologiaRESUMO
Radiation-induced apoptosis (RiA) is used therapeutically for tumor cell ablation as well as a tool to characterize hemopoietic cell lineages. We report that the peritoneal B-1 B cell subset is selectively resistant to RiA. Inherent radioresistance is not shared by splenic B-2 or B-1 cells. However, it is conferred upon B-2 cells by BCR crosslinking in the presence of IL-6 or IL-10. In vivo experiments with gene-targeted mice confirm that IL-6 and, to a lesser extent, IL-10 are the relevant stimuli that combine with BCR ligands to promote B-1 cell radioresistance. STAT3 promotes cell survival in response to selected growth factors, and is activated by combined BCR crosslinking and IL-6 (IL-10). Importantly, STAT3(-/-) B-1 cells become susceptible to irradiation, indicating that STAT3 activation by the BCR in the presence of IL costimuli account for the inherent radioresistance of peritoneal B-1 B cells.
Assuntos
Apoptose/efeitos da radiação , Subpopulações de Linfócitos B/imunologia , Subpopulações de Linfócitos B/efeitos da radiação , Raios gama , Fator de Transcrição STAT3/fisiologia , Animais , Apoptose/genética , Subpopulações de Linfócitos B/metabolismo , Células Cultivadas , Imunidade Inata/genética , Imunidade Inata/efeitos da radiação , Interleucina-10/fisiologia , Interleucina-6/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Cavidade Peritoneal/citologia , Cavidade Peritoneal/efeitos da radiação , Fosforilação , Receptores de Antígenos de Linfócitos B/metabolismo , Receptores de Antígenos de Linfócitos B/fisiologia , Fator de Transcrição STAT3/biossíntese , Fator de Transcrição STAT3/deficiência , Fator de Transcrição STAT3/genética , Serina/metabolismo , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Transdução de Sinais/efeitos da radiaçãoRESUMO
Expression of B cell-activating factor (BAFF), a critical B cell survival factor, is elevated in autoimmune and lymphoproliferative disorders. Mice overproducing BAFF develop systemic lupus erythematosus (SLE)-like disease and exhibit B cell activation of classical and alternative NF-kappaB-signaling pathways. We used a genetic approach and found that both NF-kappaB-signaling pathways contributed to disease development but act through distinct mechanisms. Whereas BAFF enhanced long-term B cell survival primarily through the alternative, but not the classical, NF-kappaB pathway, it promoted immunoglobulin class switching and generation of pathogenic antibodies through the classical pathway. Activation of the alternative NF-kappaB pathway resulted in integrin upregulation, thereby retaining autoreactive B cells in the splenic marginal zone, a compartment that contributes to their survival. Thus, both classical and alternative NF-kappaB signaling are important for development of lupus-like disease associated with BAFF overproduction. The same mechanisms may be involved in the pathogenesis of human SLE.