RESUMEN
Components of the intraflagellar transport (IFT) system that regulates the assembly of the primary cilium are co-opted by the non-ciliated T cell to orchestrate polarized endosome recycling and to sustain signaling during immune synapse formation. Here, we investigated the potential role of Bardet-Biedl syndrome 1 protein (BBS1), an essential core component of the BBS complex that cooperates with the IFT system in ciliary protein trafficking, in the assembly of the T cell synapse. We demonstrated that BBS1 allows for centrosome polarization towards the immune synapse. This function is achieved through the clearance of centrosomal F-actin and its positive regulator WASH1 (also known as WASHC1), a process that we demonstrated to be dependent on the proteasome. We show that BBS1 regulates this process by coupling the 19S proteasome regulatory subunit to the microtubule motor dynein for its transport to the centrosome. Our data identify the ciliopathy-related protein BBS1 as a new player in T cell synapse assembly that functions upstream of the IFT system to set the stage for polarized vesicular trafficking and sustained signaling. This article has an associated First Person interview with the first author of the paper.
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Síndrome de Bardet-Biedl , Cilios , Síndrome de Bardet-Biedl/genética , Polaridad Celular , Endosomas , Humanos , Proteínas Asociadas a Microtúbulos/genética , Sinapsis , Linfocitos TRESUMEN
The stromal microenvironment is central to chronic lymphocytic leukemia (CLL) pathogenesis. How leukemic cells condition the stroma to enhance its chemoattractant properties remains elusive. Here, we show that mouse and human CLL cells promote the contact-independent stromal expression of homing chemokines. This function was strongly enhanced in leukemic cells from Eµ-TCL1 mice lacking the pro-oxidant p66Shc adaptor, which develop an aggressive disease with organ infiltration. We identified interleukin-9 (IL-9) as the soluble factor, negatively modulated by p66Shc, that is responsible for the chemokine-elevating activity of leukemic cells on stromal cells. IL-9 blockade in Eµ-TCL1/p66Shc-/- mice resulted in a decrease in the nodal expression of homing chemokines, which correlated with decreased leukemic cell invasiveness. IL-9 levels were found to correlate inversely with residual p66Shc in p66Shc-deficient human CLL cells (n = 52 patients). p66Shc reconstitution in CLL cells normalized IL-9 expression and neutralized their chemokine-elevating activity. Notably, high IL-9 expression in CLL cells directly correlates with lymphadenopathy, liver infiltration, disease severity, and overall survival, emerging as an independent predictor of disease outcome. Our results demonstrate that IL-9 modulates the chemokine landscape in the stroma and that p66Shc, by regulating IL-9 expression, fine tunes the ability of leukemic cells to shape the microenvironment, thereby contributing to CLL pathogenesis.
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Similar to Janus, the two-faced god of Roman mythology, the tumor microenvironment operates two opposing and often conflicting activities, on the one hand fighting against tumor cells, while on the other hand, favoring their proliferation, survival and migration to other sites to establish metastases. In the tumor microenvironment, cytotoxic T cells-the specialized tumor-cell killers-also show this dual nature, operating their tumor-cell directed killing activities until they become exhausted and dysfunctional, a process promoted by cancer cells themselves. Here, we discuss the opposing activities of immune cells populating the tumor microenvironment in both cancer progression and anti-cancer responses, with a focus on cytotoxic T cells and on the molecular mechanisms responsible for the efficient suppression of their killing activities as a paradigm of the power of cancer cells to shape the microenvironment for their own survival and expansion.
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Inmunoterapia/métodos , Neoplasias/inmunología , Linfocitos T Citotóxicos/inmunología , Microambiente Tumoral/inmunología , Animales , Humanos , Neoplasias/patología , Neoplasias/terapiaRESUMEN
Helicobacter pylori (HP) is a Gram-negative bacterium that chronically infects the stomach of more than 50% of human population and represents a major cause of gastric cancer, gastric lymphoma, gastric autoimmunity, and peptic ulcer. It still remains to be elucidated, which HP virulence factors are important in the development of gastric disorders. Here, we analysed the role of the HP protein HP1454 in the host-pathogen interaction. We found that a significant proportion of T cells isolated from HP patients with chronic gastritis and gastric adenocarcinoma proliferated in response to HP1454. Moreover, we demonstrated in vivo that HP1454 protein drives Th1/Th17 inflammatory responses. We further analysed the in vitro response of human T cells exposed either to an HP wild-type strain or to a strain with a deletion of the hp1454 gene, and we revealed that HP1454 triggers the T-cell antigen receptor-dependent signalling and lymphocyte proliferation, as well as the CXCL12-dependent cell adhesion and migration. Our study findings prove that HP1454 is a crucial bacterial factor that exerts its proinflammatory activity by directly modulating the T-cell response. The relevance of these results can be appreciated by considering that compelling evidence suggest that chronic gastric inflammation, a condition that paves the way to HP-associated diseases, is dependent on T cells.
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Adenocarcinoma/inmunología , Gastritis/inmunología , Infecciones por Helicobacter/inmunología , Helicobacter pylori/metabolismo , Lipoproteínas/inmunología , Neoplasias Gástricas/inmunología , Linfocitos T/inmunología , Adenocarcinoma/microbiología , Anciano , Adhesión Celular/inmunología , Diferenciación Celular/inmunología , Membrana Celular/metabolismo , Membrana Celular/ultraestructura , Movimiento Celular/inmunología , Femenino , Mucosa Gástrica/inmunología , Mucosa Gástrica/microbiología , Mucosa Gástrica/ultraestructura , Gastritis/microbiología , Regulación de la Expresión Génica/inmunología , Helicobacter pylori/genética , Helicobacter pylori/crecimiento & desarrollo , Interacciones Huésped-Patógeno/inmunología , Humanos , Masculino , Persona de Mediana Edad , Proteínas R-SNARE/genética , Proteínas R-SNARE/metabolismo , Receptores de Antígenos de Linfocitos T/inmunología , Transducción de Señal/inmunología , Neoplasias Gástricas/microbiología , Células TH1/inmunología , Células Th17/inmunologíaRESUMEN
In addition to their modulation through de novo expression and degradation, surface levels of chemokine receptors are tuned by their ligand-dependent recycling to the plasma membrane, which ensures that engaged receptors become rapidly available for further rounds of signaling. Dysregulation of this process contributes to the pathogenesis of chronic lymphocytic leukemia (CLL) by enhancing surface expression of chemokine receptors, thereby favoring leukemic cell accumulation in the protective niche of lymphoid organs. In this review, we summarize our current understanding of the process of chemokine receptor recycling, focusing on the impact of its dysregulation in CLL.
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Leucemia Linfocítica Crónica de Células B/patología , Receptores de Quimiocina/metabolismo , Arrestinas/metabolismo , Humanos , Leucemia Linfocítica Crónica de Células B/metabolismo , Ganglios Linfáticos/metabolismo , Fosforilación , Transducción de SeñalRESUMEN
The Shc family adaptor p66Shc acts as a negative regulator of proliferative and survival signals triggered by the B-cell receptor and, by enhancing the production of reactive oxygen species, promotes oxidative stress-dependent apoptosis. Additionally, p66Shc controls the expression and function of chemokine receptors that regulate lymphocyte traffic. Chronic lymphocytic leukemia cells have a p66Shc expression defect which contributes to their extended survival and correlates with poor prognosis. We analyzed the impact of p66Shc ablation on disease severity and progression in the Eµ-TCL1 mouse model of chronic lymphocytic leukemia. We showed that Eµ-TCL1/p66Shc-/- mice developed an aggressive disease that had an earlier onset, occurred at a higher incidence and led to earlier death compared to that in Eµ-TCL1 mice. Eµ-TCL1/p66Shc-/- mice displayed substantial leukemic cell accumulation in both nodal and extranodal sites. The target organ selectivity correlated with upregulation of chemokine receptors whose ligands are expressed therein. This also applied to chronic lymphocytic leukemia cells, where chemokine receptor expression and extent of organ infiltration were found to correlate inversely with these cells' level of p66Shc expression. p66Shc expression declined with disease progression in Eµ-TCL1 mice and could be restored by treatment with the Bruton tyrosine kinase inhibitor ibrutinib. Our results highlight p66Shc deficiency as an important factor in the progression and severity of chronic lymphocytic leukemia and underscore p66Shc expression as a relevant therapeutic target.
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Carcinogénesis/metabolismo , Leucemia Linfocítica Crónica de Células B/metabolismo , Proteínas de Neoplasias/metabolismo , Neoplasias Experimentales/metabolismo , Receptores de Quimiocina/metabolismo , Proteína Transformadora 1 que Contiene Dominios de Homología 2 de Src/deficiencia , Animales , Carcinogénesis/genética , Carcinogénesis/patología , Leucemia Linfocítica Crónica de Células B/genética , Leucemia Linfocítica Crónica de Células B/patología , Ratones , Ratones Noqueados , Proteínas de Neoplasias/genética , Neoplasias Experimentales/genética , Neoplasias Experimentales/patología , Receptores de Quimiocina/genética , Proteína Transformadora 1 que Contiene Dominios de Homología 2 de Src/metabolismoRESUMEN
Systemic lupus erythematosus is frequently associated with antiphospholipid syndrome. Patients with lupus-antiphospholipid syndrome are characterized by recurrent arterial/venous thrombosis, miscarriages, and persistent presence of autoantibodies against phospholipid-binding proteins, such as ß2-Glycoprotein I. We investigated the cytokine production induced by ß2-Glycoprotein I in activated T cells that infiltrate in vivo atherosclerotic lesions of lupus-antiphospholipid syndrome patients. We examined the helper function of ß2-Glycoprotein I-specific T cells for tissue factor production, as well as their cytolytic potential and their helper function for antibody production. Lupus-antiphospholipid syndrome patients harbor in vivo activated CD4+ T cells that recognize ß2-Glycoprotein I in atherosclerotic lesions. ß2-Glycoprotein I induces T-cell proliferation and expression of both Interleukin-17/Interleukin-21 and Interferon-γ in plaque-derived T-cell clones. ß2-Glycoprotein I-specific T cells display strong help for monocyte tissue factor production, and promote antibody production in autologous B cells. Moreover, plaque-derived ß2-Glycoprotein I-specific CD4+ T lymphocytes express both perforin-mediated and Fas/FasLigand-mediated-cytotoxicity. Altogether, our results indicate that ß2-Glycoprotein I is able to elicit a local Interleukin-17/Interleukin-21 and Interferon-γ inflammation in lupus-antiphospholipid syndrome patients that might lead, if unabated, to plaque instability and subsequent arterial thrombosis, suggesting that the T helper 17/T helper 1 pathway may represent a novel target for the prevention and treatment of the disease.
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Síndrome Antifosfolípido/fisiopatología , Aterosclerosis/etiología , Autoanticuerpos/inmunología , Inflamación/etiología , Lupus Eritematoso Sistémico/complicaciones , Linfocitos T/inmunología , beta 2 Glicoproteína I/inmunología , Adulto , Anticuerpos Antifosfolípidos/inmunología , Aterosclerosis/metabolismo , Aterosclerosis/patología , Autoanticuerpos/sangre , Femenino , Estudios de Seguimiento , Humanos , Inflamación/metabolismo , Inflamación/patología , Interferón gamma/inmunología , Interferón gamma/metabolismo , Interleucina-17/inmunología , Interleucina-17/metabolismo , Interleucinas/inmunología , Interleucinas/metabolismo , Lupus Eritematoso Sistémico/inmunología , Lupus Eritematoso Sistémico/metabolismo , Lupus Eritematoso Sistémico/patología , Activación de Linfocitos/inmunología , Masculino , Persona de Mediana Edad , Pronóstico , beta 2 Glicoproteína I/metabolismoRESUMEN
BACKGROUND: Low molecular weight protein tyrosine phosphatase (LMW-PTP) is overexpressed in different cancer types and its expression is related to more aggressive disease, reduced survival rate and drug resistance. Morin is a natural polyphenol which negatively modulates, among others, the activity of LMW-PTP, leading to the potentiation of the effects of different antitumoral drugs, representing a potential beneficial treatment against cancer. METHODS: LMW-PTP levels were measured by immunoblot analysis both in CLL cells from patients and in chronic lymphocytic leukemia (CLL)-derived Mec-1 cells. Cell viability was assessed in Mec-1 cells treated with morin alone or in combination with either fludarabine or ibrutinib or following siRNA-mediated LMW-PTP knockdown. Furthermore, the expression levels of VLA-4 and CXCR4 were assessed by both qRT-PCR and flow cytometry and both adhesion to fibronectin-coated plates and migration toward CXCL12 were analyzed in Mec-1 cells treated with morin alone or in combination with fludarabine or ibrutinib. RESULTS: We observed that LMW-PTP is highly expressed in Mec-1 cells as well as in leukemic B lymphocytes purified from CLL patients compared to normal B lymphocytes. Morin treatment strongly decreased LMW-PTP expression levels in Mec-1 cells and potentiated the anticancer properties of both fludarabine and ibrutinib by increasing their apoptotic effects on leukemic cells. Moreover, morin negatively regulates adhesion and CXCL12-dependent migration of Mec-1 cells by affecting VLA-4 integrin expression and CXCR4 receptor recycling. CONCLUSIONS: Morin treatment in CLL-derived Mec-1 cell line synergizes with conventional anticancer drugs currently used in CLL therapy by affecting leukemic cell viability and trafficking.
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BAFF is a crucial cytokine that affects the activity of both innate and adaptive immune cells. It promotes the expansion of Th17 cells in autoimmune disorders. With this study, we investigated the BAFF/Th17 responses in Helicobacter pylori-induced gastritis in humans. Our results show that the mucosa from Helicobacter(+) patients with chronic gastritis is enriched in IL-17 and BAFF, whereas the two cytokines are weakly expressed in Helicobacter(-) patients with chronic gastritis; moreover, the expression of both BAFF and IL-17 decreases after bacteria eradication. We demonstrate that BAFF accumulates in macrophages in vivo and that it is produced by monocyte-derived macrophages in vitro, after Helicobacter stimulation. Application of BAFF on monocytes triggers the accumulation of reactive oxygen species that are crucial for the release of pro-Th17 cytokines, such as IL-23, IL-1ß, and TGF-ß. Moreover, BAFF directly promotes the differentiation of Th17 cells. In conclusion, our results support the notion that an axis BAFF/Th17 exists in chronic gastritis of Helicobacter(+) patients and that its presence strictly depends on the bacterium. Moreover, we demonstrated that BAFF is able to drive Th17 responses both indirectly, by creating a pro-Th17 cytokine milieu through the involvement of innate immune cells, and directly, via the differentiation of T cells toward the specific profile. The results obtained in this study are of great interest for Helicobacter-related diseases and the development of novel therapeutic strategies based on the inhibition of the BAFF/IL-17 response.
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Factor Activador de Células B/metabolismo , Gastritis/inmunología , Infecciones por Helicobacter/inmunología , Helicobacter pylori/inmunología , Macrófagos/inmunología , Membrana Mucosa/inmunología , Células Th17/inmunología , Inmunidad Adaptativa , Diferenciación Celular , Células Cultivadas , Enfermedad Crónica , Gastritis/etiología , Infecciones por Helicobacter/complicaciones , Humanos , Inmunidad Innata , Interleucina-17/metabolismo , Macrófagos/microbiología , Membrana Mucosa/microbiología , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Although intrinsic apoptosis defects are causal to the extended survival of chronic lymphocytic leukemia (CLL) B cells, several lines of evidence support a contribution of the peripheral lymphoid organs and BM microenvironment to the extended lifespan of leukemic B cells. Lymphocyte trafficking is controlled by homing signals provided by stromal cell-derived chemokines and egress signals provided by sphingosine-1-phosphate (S1P). In the present study, we show that expression of S1P1, the S1P receptor responsible for lymphocyte egress, is selectively reduced in CLL B cells with unmutated IGHV. Expression of S1P2, which controls B-cell homeostasis, is also impaired in CLL B cells but independently of the IGHV mutational status. We provide evidence herein that p66Shc, a Shc adaptor family member the deficiency of which is implicated in the apoptosis defects of CLL B cells, controls S1P1 expression through its pro-oxidant activity. p66Shc also controls the expression of the homing receptor CCR7, which opposes S1P1 by promoting lymphocyte retention in peripheral lymphoid organs. The results of the present study provide insights into the regulation of S1P1 expression in B cells and suggest that defective egress caused by impaired S1P1 expression contributes to the extended survival of CLL B cells by prolonging their residency in the prosurvival niche of peripheral lymphoid organs.
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Leucemia Linfocítica Crónica de Células B/diagnóstico , Leucemia Linfocítica Crónica de Células B/genética , Receptores de Lisoesfingolípidos/genética , Proteínas Adaptadoras de la Señalización Shc/fisiología , Adulto , Animales , Femenino , Regulación de la Expresión Génica/genética , Regulación Leucémica de la Expresión Génica , Humanos , Leucemia Linfocítica Crónica de Células B/metabolismo , Leucemia Linfocítica Crónica de Células B/mortalidad , Masculino , Ratones , Ratones Noqueados , Oxidantes/metabolismo , Pronóstico , Receptores de Lisoesfingolípidos/fisiología , Proteínas Adaptadoras de la Señalización Shc/genética , Proteínas Adaptadoras de la Señalización Shc/metabolismo , Proteína Transformadora 1 que Contiene Dominios de Homología 2 de Src , Células Tumorales CultivadasRESUMEN
Introduction: Escape from immunosurveillance is a hallmark of chronic lymphocytic leukemia (CLL) cells. In the protective niche of lymphoid organs, leukemic cells suppress the ability of T lymphocytes to form the immune synapse (IS), thereby hampering T-cell mediated anti-tumoral activities. By binding its cognate receptor PD-1 at the surface of T lymphocytes, the inhibitory ligand PD-L1, which is overexpressed in CLL cells, mediates the T-cell suppressive activities of CLL cells. However, the molecular mechanism underlying PD-L1 overexpression in CLL cells remains unknown. We have previously reported a defective expression of the pro-apoptotic and pro-oxidant adaptor p66Shc in CLL cells, which is causally related to an impairment in intracellular reactive oxygen species (ROS) production and to the activation of the ROS-sensitive transcription factor NF-κB. The fact that PD-L1 expression is regulated by NF-κB suggests a mechanistic relationship between p66Shc deficiency and PD-L1 overexpression in CLL cells. Methods: 62 treatment-naive CLL patients and 43 healthy donors were included in this study. PD-L1 and p66Shc expression was quantified in B cells by flow cytometry and qRT-PCR. IS architecture and local signaling was assessed by flow cytometry and confocal microscopy. CD8+ cell killing activity was assessed by flow cytometry. Results: Here we show that residual p66Shc expression in leukemic cells isolated both from CLL patients and from the CLL mouse model Eµ-TCL1 inversely correlated with PD-L1 expression. We also show that the PD-L1 increase prevented leukemic cells from forming ISs with T lymphocytes. Reconstitution of p66Shc, but not of a ROS-defective mutant, in both CLL cells and the CLL-derived cell line MEC-1, enhanced intracellular ROS and decreased PD-L1 expression. Similar results were obtained following treatment of CLL cells with H2O2 as exogenous source of ROS, that normalized PD-L1 expression and recovered IS formation. Discussion: Our data provide direct evidence that the p66Shc-deficiency-related ROS depletion in CLL cells concurs to enhance PD-L1 expression and provides a mechanistic basis for the suppression of T cell-mediated anti-tumoral functions in the immunosuppressive lymphoid niche.
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The tumor microenvironment (TME) plays a central role in the pathogenesis of chronic lymphocytic leukemia (CLL), contributing to disease progression and chemoresistance. Leukemic cells shape the TME into a pro-survival and immunosuppressive niche through contact-dependent and contact-independent interactions with the cellular components of the TME. Immune synapse (IS) formation is defective in CLL. Here we asked whether soluble factors released by CLL cells contribute to their protection from cytotoxic T cell (CTL)-mediated killing by interfering with this process. We found that healthy CTLs cultured in media conditioned by leukemic cells from CLL patients or Eµ-TCL1 mice upregulate the exhaustion marker PD-1 and become unable to form functional ISs and kill target cells. These defects were more pronounced when media were conditioned by leukemic cells lacking p66Shc, a proapoptotic adapter whose deficiency has been implicated in disease aggressiveness both in CLL and in the Eµ-TCL1 mouse model. Multiplex ELISA assays showed that leukemic cells from Eµ-TCL1 mice secrete abnormally elevated amounts of CCL22, CCL24, IL-9 and IL-10, which are further upregulated in the absence of p66Shc. Among these, IL-9 and IL-10 were also overexpressed in leukemic cells from CLL patients, where they inversely correlated with residual p66Shc. Using neutralizing antibodies or the recombinant cytokines we show that IL-9, but not IL-10, mediates both the enhancement in PD-1 expression and the suppression of effector functions in healthy CTLs. Our results demonstrate that IL-9 secreted by leukemic cells negatively modulates the anti-tumor immune abilities of CTLs, highlighting a new suppressive mechanism and a novel potential therapeutical target in CLL.
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Interleucina-9 , Leucemia Linfocítica Crónica de Células B , Animales , Humanos , Ratones , Factores Inmunológicos , Interleucina-10/metabolismo , Interleucina-9/metabolismo , Leucemia Linfocítica Crónica de Células B/inmunología , Leucemia Linfocítica Crónica de Células B/patología , Receptor de Muerte Celular Programada 1/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Proteína Transformadora 1 que Contiene Dominios de Homología 2 de Src/metabolismo , Linfocitos T Citotóxicos/metabolismo , Microambiente TumoralRESUMEN
The Retention Using Selective Hooks (RUSH) system allows for the synchronized release of one or more proteins of interest from a donor endomembrane compartment, usually the endoplasmic reticulum, and the subsequent monitoring of their traffic toward acceptor compartments. Here we describe the RUSH system applied to cytotoxic T cells to characterize the biogenesis of lytic granules, using as a proof-of-concept granzyme B trafficking to this specialized compartment.
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Proteínas , Linfocitos T Citotóxicos , Linfocitos T Citotóxicos/metabolismo , Proteínas/metabolismo , Gránulos Citoplasmáticos/metabolismoRESUMEN
Intrinsic apoptosis defects underlie to a large extent the extended survival of malignant B cells in chronic lymphocytic leukemia (CLL). Here, we show that the Shc family adapter p66Shc uncouples the B-cell receptor (BCR) from the Erk- and Akt-dependent survival pathways, thereby enhancing B-cell apoptosis. p66Shc expression was found to be profoundly impaired in CLL B cells compared with normal peripheral B cells. Moreover, significant differences in p66Shc expression were observed in patients with favorable or unfavorable prognosis, based on the mutational status of IGHV genes, with the lowest expression in the unfavorable prognosis group. Analysis of the expression of genes implicated in apoptosis defects of CLL showed an alteration in the balance of proapoptotic and antiapoptotic members of the Bcl-2 family in patients with CLL. Reconstitution experiments in CLL B cells, together with data obtained on B cells from p66Shc(-/-) mice, showed that p66Shc expression correlates with a bias in the Bcl-2 family toward proapoptotic members. The data identify p66Shc as a novel regulator of B-cell apoptosis which attenuates BCR-dependent survival signals and modulates Bcl-2 family expression. They moreover provide evidence that the p66Shc expression defect in CLL B cells may be causal to the imbalance toward the antiapoptotic Bcl-2 family members in these cells.
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Apoptosis , Linfocitos B/metabolismo , Leucemia Linfocítica Crónica de Células B/metabolismo , Proteínas Adaptadoras de la Señalización Shc/metabolismo , Animales , Western Blotting , Estudios de Casos y Controles , Supervivencia Celular , Metilación de ADN , Quinasas MAP Reguladas por Señal Extracelular/genética , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Humanos , Leucemia Linfocítica Crónica de Células B/genética , Leucemia Linfocítica Crónica de Células B/patología , Ratones , Ratones Noqueados , Regiones Promotoras Genéticas/genética , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Proteínas Proto-Oncogénicas c-bcr/genética , Proteínas Proto-Oncogénicas c-bcr/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de Señal , Proteína Transformadora 1 que Contiene Dominios de Homología 2 de SrcRESUMEN
Similar to other pathogens, bacteria have developed during their evolution a variety of mechanisms to overcome both innate and acquired immunity, accounting for their ability to cause disease or chronic infections. The mechanisms exploited for this critical function act by targeting conserved structures or pathways that regulate the host immune response. A strategic potential target is the immunological synapse (IS), a highly specialized structure that forms at the interface between antigen presenting cells (APC) and T lymphocytes and is required for the establishment of an effective T cell response to the infectious agent and for the development of long-lasting T cell memory. While a variety of bacterial pathogens are known to impair or subvert cellular processes essential for antigen processing and presentation, on which IS assembly depends, it is only recently that the possibility that IS may be a direct target of bacterial virulence factors has been considered. Emerging evidence strongly supports this notion, highlighting IS targeting as a powerful, novel means of immune evasion by bacterial pathogens. In this review we will present a brief overview of the mechanisms used by bacteria to affect IS assembly by targeting APCs. We will then summarize what has emerged from the current handful of studies that have addressed the direct impact of bacterial virulence factors on IS assembly in T cells and, based on the strategic cellular processes targeted by these factors in other cell types, highlight potential IS-related vulnerabilities that could be exploited by these pathogens to evade T cell mediated immunity.
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Sinapsis Inmunológicas , Receptores de Antígenos de Linfocitos T , Presentación de Antígeno , Bacterias/metabolismo , Evasión Inmune , Factores de Virulencia/metabolismoRESUMEN
An imbalance in the expression of pro- and anti-apoptotic members of the Bcl-2 family of apoptosis-regulating proteins is one of the main biological features of CLL, highlighting these proteins as therapeutic targets for treatment of this malignancy. Indeed, the Bcl-2 inhibitor Venetoclax is currently used for both first-line treatment and treatment of relapsed or refractory CLL. An alternative avenue is the transcriptional modulation of Bcl-2 family members to tilt their balance towards apoptosis. Glycerophosphoinositol (GroPIns) is a biomolecule generated from membrane phosphoinositides by the enzymes phospholipase A2 and lysolipase that pleiotropically affects key cellular functions. Mass-spectrometry analysis of GroPIns interactors recently highlighted the ability of GroPIns to bind to the non-receptor tyrosine phosphatase SHP-1, a known promoter of Bax expression, suggesting that GroPIns might correct the Bax expression defect in CLL cells, thereby promoting their apoptotic demise. To test this hypothesis, we cultured CLL cells in the presence of GroPIns, alone or in combination with drugs commonly used for treatment of CLL. We found that GroPIns alone increases Bax expression and apoptosis in CLL cells and enhances the pro-apoptotic activity of drugs used for CLL treatment in a SHP-1 dependent manner. Interestingly, among GroPIns interactors we found Bax itself. Short-term treatments of CLL cells with GroPIns induce Bax activation and translocation to the mitochondria. Moreover, GroPIns enhances the pro-apoptotic activity of Venetoclax and Fludarabine in CLL cells. These data provide evidence that GroPIns exploits two different pathways converging on Bax to promote apoptosis of leukemic cells and pave the way to new studies aimed at testing GroPIns in combination therapies for the treatment of CLL.
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The microenvironment of lymphoid organs is central to the pathogenesis of chronic lymphocytic leukemia (CLL). Within it, tumor cells find a favourable niche to escape immunosurveillance and acquire pro-survival signals. We have previously reported that a CLL-associated defect in the expression of the pro-apoptotic and pro-oxidant adaptor p66Shc leads to enhanced homing to and accumulation of leukemic cells in the lymphoid microenvironment. The p66Shc deficiency-related impairment in intracellular reactive oxygen species (ROS) production in CLL cells is causally associated to the enhanced expression of the chemokine receptors CCR2, CXCR3 and CCR7, that promote leukemic cell homing to both lymphoid and non-lymphoid organs, suggesting the implication of a ROS-modulated transcription factor(s). Here we show that the activity of the ROS-responsive p65 subunit of the transcription factor NF-κB was hampered in the CLL-derived cell line MEC-1 expressing a NF-κB-luciferase reporter following treatment with H2O2. Similar results were obtained when intracellular ROS were generated by expression of p66Shc, but not of a ROS-defective mutant, in MEC-1 cells. NF-κB activation was associated with increased expression of the chemokine receptors CCR2, CXCR3 and CCR7. Reconstitution of p66Shc in CLL cells normalized intracellular ROS and hampered NF-κB activation, which led to a decrease in the expression of these homing receptors. Our data provide direct evidence that the p66Shc-deficiency-related ROS depletion in CLL cells concurs to NF-κB hyperactivation and homing receptor overexpression, providing a mechanistic basis for the enhanced ability of these cells to accumulate in the pro-survival lymphoid niche.
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Antiphospholipid syndrome (APS) is a systemic autoimmune disorder characterized by recurrent vascular thrombosis and miscarriages in the absence of known causes. Antibodies against phospholipid-binding proteins (aPL) are pathogenic players in both clotting and pregnancy APS manifestations. There is sound evidence that antibodies specific for beta2 glycoprotein I (ß2GPI) trigger thrombotic and pregnancy complications by interacting with the molecule on the membranes of different cell types of the coagulation cascade, and in placenta tissues. In addition to the humoral response against ß2GPI, both peripheral and tissue CD4+ ß2GPI-specific T cells have been reported in primary APS as well as in systemic lupus erythematosus (SLE)-associated APS. While adaptive immunity plays a clear role in APS, it is still debated whether innate immunity is involved as well. Acute systemic inflammation does not seem to be present in the syndrome, however, there is sound evidence that complement activation is crucial in animal models and can be found also in patients. Furthermore, neutrophil extracellular traps (NETs) have been documented in arterial and venous thrombi with different etiology, including clots in APS models. Keeping in mind that ß2GPI is a pleiotropic glycoprotein, acting as scavenger molecule for infectious agents and apoptotic/damaged body constituents and that self-molecules externalized through NETs formation may become immunogenic autoantigens, we demonstrated ß2GPI on NETs, and its ability to stimulate CD4+ß2GPI-specific T cells. The aim of this review is to elucidate the role of ß2GPI in the cross-talk between the innate and adaptive immunity in APS.
Asunto(s)
Síndrome Antifosfolípido , Trampas Extracelulares , Trombosis , beta 2 Glicoproteína I , Animales , Femenino , Embarazo , Inmunidad Adaptativa , Anticuerpos Antifosfolípidos , beta 2 Glicoproteína I/metabolismo , Trampas Extracelulares/metabolismo , Trombosis/complicaciones , Inmunidad InnataRESUMEN
Ciliogenesis proteins orchestrate vesicular trafficking pathways that regulate immune synapse (IS) assembly in the non-ciliated T-cells. We hypothesized that ciliogenesis-related genes might be disease candidates for common variable immunodeficiency with impaired T-cell function (T-CVID). We identified a heterozygous, predicted pathogenic variant in the ciliogenesis protein CCDC28B present with increased frequency in a large CVID cohort. We show that CCDC28B participates in IS assembly by regulating polarized T-cell antigen receptor (TCR) recycling. This involves the CCDC28B-dependent, FAM21-mediated recruitment of the actin regulator WASH to retromer at early endosomes to promote actin polymerization. The CVID-associated CCDC28BR25W variant failed to interact with FAM21, leading to impaired synaptic TCR recycling. CVID T cells carrying the ccdc28b 211 C > T allele displayed IS defects mapping to this pathway that were corrected by overexpression of the wild-type allele. These results identify a new disease gene in T-CVID and pinpoint CCDC28B as a new player in IS assembly.
Asunto(s)
Inmunodeficiencia Variable Común , Actinas/genética , Inmunodeficiencia Variable Común/genética , Proteínas del Citoesqueleto , Humanos , Receptores de Antígenos de Linfocitos T/metabolismo , Sinapsis/metabolismo , Linfocitos TRESUMEN
Pernicious anemia (PA) is a megaloblastic anemia consisting of hematological, gastric and immunological alterations. The immunopathogenesis of PA is sustained by both autoantibodies (e.g. intrinsic factor (IFA) antibodies and anti parietal cell (PCA) antibodies and autoreactive T cells specific for IFA and the parietal cell proton pump ATPase. Iron deficient anemia (IDA) is a microcytic anemia and represents the most common cause of anemia worldwide. Our work aimed to investigate serum levels of several interleukins (IL) of the IL-20 cytokine subfamily in patients with PA, with IDA and in healthy subjects (HC). We compared serum levels of IL-19, IL-20, IL-26, IL-28A and IL-29 in 43 patients with PA and autoimmune gastritis, in 20 patients with IDA and no autoimmune gastritis, and in 47 HC. Furthermore, we analyzed the IL-19 cytokine production by gastric lamina propria mononuclear cells (LPMC) in eight patients with PA and four HC. We found that patients with PA have significantly higher serum levels of IL-19 (163.68 ± 75.96 pg/ml) than patients with IDA (35.49 ± 40.97 pg/ml; p<0.001) and healthy subjects (55.68 ± 36.75 pg/ml; p<0.001). Gastric LPMC from all PA patients were able to produce significantly higher levels of IL-19 (420.67 ± 68.14 pg/ml) than HC (53.69 ± 10.92 pg/ml) (p<0.01). Altogether, our results indicate that IL-19 serum levels are significantly increased in patients with PA but not with IDA and that IL-19 is produced in vivo in the stomach of PA patients. These data open a new perspective on PA pathogenesis and suggest that IL-19 may represent a novel important tool for the management of patients with PA.