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BACKGROUND: Allergic diseases begin early in life and are often chronic, thus creating an inflammatory environment that may precede or exacerbate other pathologies. In this regard, allergy has been associated to metabolic disorders and with a higher risk of cardiovascular disease, but the underlying mechanisms remain incompletely understood. METHODS: We used a murine model of allergy and atherosclerosis, different diets and sensitization methods, and cell-depleting strategies to ascertain the contribution of acute and late phase inflammation to dyslipidemia. Untargeted lipidomic analyses were applied to define the lipid fingerprint of allergic inflammation at different phases of allergic pathology. Expression of genes related to lipid metabolism was assessed in liver and adipose tissue at different times post-allergen challenge. Also, changes in serum triglycerides (TGs) were evaluated in a group of 59 patients ≥14 days after the onset of an allergic reaction. RESULTS: We found that allergic inflammation induces a unique lipid signature that is characterized by increased serum TGs and changes in the expression of genes related to lipid metabolism in liver and adipose tissue. Alterations in blood TGs following an allergic reaction are independent of T-cell-driven late phase inflammation. On the contrary, the IgG-mediated alternative pathway of anaphylaxis is sufficient to induce a TG increase and a unique lipid profile. Lastly, we demonstrated an increase in serum TGs in 59 patients after undergoing an allergic reaction. CONCLUSION: Overall, this study reveals that IgG-mediated allergic inflammation regulates lipid metabolism.
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B cell receptor (BCR)-mediated antigen-specific recognition activates B lymphocytes and drives the humoral immune response. This enables the generation of antibody-producing plasma cells, the effector arm of the B cell immune response, and of memory B cells, which confer protection against additional encounters with antigen. B cells search for cognate antigen in the complex cellular microarchitecture of secondary lymphoid organs, where antigens are captured and exposed on the surface of different immune cells. While scanning the cell network, the BCR can be stimulated by a specific antigen and elicit the establishment of the immune synapse with the antigen-presenting cell. At the immune synapse, an integrin-enriched supramolecular domain is assembled at the periphery of the B cell contact with the antigen-presenting cell, ensuring a stable and long-lasting interaction. The coordinated action of the actomyosin cytoskeleton and the microtubule network in the inner B cell space provides a structural framework that integrates signaling events and antigen uptake through the generation of traction forces and organelle polarization. Accordingly, the B cell immune synapse can be envisioned as a temporal engine that drives the molecular mechanisms needed for successful B cell activation. Here, I review different aspects of the B cell synapse engine and provide insights into other aspects poorly known or virtually unexplored.
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Linfocitos B , Sinapsis Inmunológicas , Sinapsis Inmunológicas/metabolismo , Receptores de Antígenos de Linfocitos B/metabolismo , Citoesqueleto/metabolismo , Antígenos/metabolismo , Activación de Linfocitos , Sinapsis/metabolismoRESUMEN
In addition to triggering humoral responses, conventional B cells have been described in vitro to cross-present exogenous antigens activating naïve CD8+ T cells. Nevertheless, the way B cells capture these exogenous antigens and the physiological roles of B cell-mediated cross-presentation remain poorly explored. Here, we show that B cells capture bacteria by trans-phagocytosis from previously infected dendritic cells (DC) when they are in close contact. Bacterial encounter "instructs" the B cells to acquire antigen cross-presentation abilities, in a process that involves autophagy. Bacteria-instructed B cells, henceforth referred to as BacB cells, rapidly degrade phagocytosed bacteria, process bacterial antigens and cross-prime naïve CD8+ T cells which differentiate into specific cytotoxic cells that efficiently control bacterial infections. Moreover, a proof-of-concept experiment shows that BacB cells that have captured bacteria expressing tumor antigens could be useful as novel cellular immunotherapies against cancer.
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Linfocitos T CD8-positivos , Células Dendríticas , Presentación de Antígeno , Reactividad Cruzada , Antígenos BacterianosRESUMEN
ICAP-1 regulates ß1-integrin activation and cell adhesion. Here, we used ICAP-1-null mice to study ICAP-1 potential involvement during immune cell development and function. Integrin α4ß1-dependent adhesion was comparable between ICAP-1-null and control thymocytes, but lack of ICAP-1 caused a defective single-positive (SP) CD8+ cell generation, thus, unveiling an ICAP-1 involvement in SP thymocyte development. ICAP-1 bears a nuclear localization signal and we found it displayed a strong nuclear distribution in thymocytes. Interestingly, there was a direct correlation between the lack of ICAP-1 and reduced levels in SP CD8+ thymocytes of Runx3, a transcription factor required for CD8+ thymocyte generation. In the spleen, ICAP-1 was found evenly distributed between cytoplasm and nuclear fractions, and ICAP-1-/- spleen T and B cells displayed upregulation of α4ß1-mediated adhesion, indicating that ICAP-1 negatively controls their attachment. Furthermore, CD3+ - and CD19+ -selected spleen cells from ICAP-1-null mice showed reduced proliferation in response to T- and B-cell stimuli, respectively. Finally, loss of ICAP-1 caused a remarkable decrease in marginal zone B- cell frequencies and a moderate increase in follicular B cells. Together, these data unravel an ICAP-1 involvement in the generation of SP CD8+ thymocytes and in the control of marginal zone B-cell numbers.
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Proteínas Adaptadoras Transductoras de Señales , Linfocitos B , Linfocitos T CD8-positivos , Activación de Linfocitos , Timocitos , Proteínas Adaptadoras Transductoras de Señales/genética , Animales , Linfocitos B/citología , Linfocitos T CD8-positivos/citología , Diferenciación Celular , Integrina beta1/metabolismo , Ratones , Ratones Noqueados , Bazo/citología , Timocitos/citología , Timo/citologíaRESUMEN
Normal cell counterparts of solid and myeloid tumors accumulate mutations years before disease onset; whether this occurs in B lymphocytes before lymphoma remains uncertain. We sequenced multiple stages of the B lineage in elderly individuals and patients with lymphoplasmacytic lymphoma, a singular disease for studying lymphomagenesis because of the high prevalence of mutated MYD88. We observed similar accumulation of random mutations in B lineages from both cohorts and unexpectedly found MYD88L265P in normal precursor and mature B lymphocytes from patients with lymphoma. We uncovered genetic and transcriptional pathways driving malignant transformation and leveraged these to model lymphoplasmacytic lymphoma in mice, based on mutated MYD88 in B cell precursors and BCL2 overexpression. Thus, MYD88L265P is a preneoplastic event, which challenges the current understanding of lymphomagenesis and may have implications for early detection of B cell lymphomas.
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Linfoma de Células B , Linfoma , Macroglobulinemia de Waldenström , Anciano , Animales , Humanos , Linfoma de Células B/metabolismo , Ratones , Mutación , Factor 88 de Diferenciación Mieloide/genética , Factor 88 de Diferenciación Mieloide/metabolismo , Macroglobulinemia de Waldenström/diagnóstico , Macroglobulinemia de Waldenström/genética , Macroglobulinemia de Waldenström/patologíaRESUMEN
To accomplish their critical task of removing infected cells and fighting pathogens, leukocytes activate by forming specialized interfaces with other cells. The physics of this key immunological process are poorly understood, but it is important to understand them because leukocytes have been shown to react to their mechanical environment. Using an innovative micropipette rheometer, we show in three different types of leukocytes that, when stimulated by microbeads mimicking target cells, leukocytes become up to 10 times stiffer and more viscous. These mechanical changes start within seconds after contact and evolve rapidly over minutes. Remarkably, leukocyte elastic and viscous properties evolve in parallel, preserving a well-defined ratio that constitutes a mechanical signature specific to each cell type. Our results indicate that simultaneously tracking both elastic and viscous properties during an active cell process provides a new, to our knowledge, way to investigate cell mechanical processes. Our findings also suggest that dynamic immunomechanical measurements can help discriminate between leukocyte subtypes during activation.
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Leucocitos , Elasticidad , ViscosidadRESUMEN
Efficient generation of antibodies by B cells is one of the prerequisites of protective immunity. B cell activation by cognate antigens via B cell receptors (BCRs), or pathogen-associated molecules through pattern-recognition receptors, such as Toll-like receptors (TLRs), leads to transcriptional and metabolic changes that ultimately transform B cells into antibody-producing plasma cells or memory cells. BCR signaling and a number of steps downstream of it rely on coordinated action of cellular membranes and the actin cytoskeleton, tightly controlled by concerted action of multiple regulatory proteins, some of them exclusive to B cells. Here, we dissect the role of Missing-In-Metastasis (MIM), or Metastasis suppressor 1 (MTSS1), a cancer-associated membrane and actin cytoskeleton regulating protein, in B cell-mediated immunity by taking advantage of MIM knockout mouse strain. We show undisturbed B cell development and largely normal composition of B cell compartments in the periphery. Interestingly, we found that MIM-/- B cells are defected in BCR signaling in response to surface-bound antigens but, on the other hand, show increased metabolic activity after stimulation with LPS or CpG. In vivo, MIM knockout animals exhibit impaired IgM antibody responses to immunization with T cell-independent antigen. This study provides the first comprehensive characterization of MIM in B cells, demonstrates its regulatory role for B cell-mediated immunity, as well as proposes new functions for MIM in tuning receptor signaling and cellular metabolism, processes, which may also contribute to the poorly understood functions of MIM in cancer.
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Linfocitos B/metabolismo , Proteínas de Microfilamentos/fisiología , Proteínas de Neoplasias/fisiología , Receptores de Antígenos de Linfocitos B/fisiología , Linfocitos T/inmunología , Animales , Formación de Anticuerpos , Femenino , Sinapsis Inmunológicas/fisiología , Lipopolisacáridos/farmacología , Activación de Linfocitos , Ratones , Ratones Endogámicos C57BL , Oligodesoxirribonucleótidos/farmacología , Transducción de Señal/fisiología , Receptores Toll-Like/fisiologíaRESUMEN
The ability of a cell to migrate, adhere, and change its morphology is determinant in developing its functions; these capacities reach their maximum relevance in immune cells. For an efficient immune response, immune cells must localize in the right place at the right time; that implies crossing tissue barriers and migrating in the interstitial space of the tissues at high velocities. The dependency on trafficking abilities is even higher for B cells, one of the arms of the adaptive immune system, considering that they must encounter specific antigens for their clonal receptor in the enormous tissue volume of the secondary lymphoid organs (spleen, lymph nodes, Peyer patches). The regulated interplay between cell motility and cell adhesion allows B cells to reach distinct lymphoid tissues and, within them, to explore the stromal cell networks where antigen might be exposed. In this meeting-invited review, I summarize the current knowledge on the molecular cues and mechanisms that shapes B cell dynamics at the initial phase of the humoral immune response, including homeostatic chemoattractants and innate/inflammatory stimuli. I also revised the B cell behavior alterations caused by BCR recognition of antigen and the molecular mechanisms involved.
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Linfocitos B/inmunología , Homeostasis/inmunología , Inmunidad Humoral , Ganglios Linfáticos/inmunología , Receptores de Antígenos de Linfocitos B/inmunología , Animales , Linfocitos B/citología , Adhesión Celular , Movimiento Celular , Expresión Génica , Humanos , Inmunidad Innata , Sinapsis Inmunológicas , Ganglios Linfáticos/citología , Ganglios Linfáticos Agregados/citología , Ganglios Linfáticos Agregados/inmunología , Receptores de Antígenos de Linfocitos B/genética , Bazo/citología , Bazo/inmunología , Células del Estroma/citología , Células del Estroma/inmunología , Receptores Toll-Like/genética , Receptores Toll-Like/inmunologíaRESUMEN
Diacylglycerol kinases (DGKs) limit antigen receptor signaling in immune cells by consuming the second messenger diacylglycerol (DAG) to generate phosphatidic acid (PA). Here, we showed that DGKζ promotes lymphocyte function-associated antigen 1 (LFA-1)-mediated adhesion and F-actin generation at the immune synapse of B cells with antigen-presenting cells (APCs), mostly in a PA-dependent manner. Measurement of single-cell mechanical force generation indicated that DGKζ-deficient B cells exerted lower forces at the immune synapse than did wild-type B cells. Nonmuscle myosin activation and translocation of the microtubule-organizing center (MTOC) to the immune synapse were also impaired in DGKζ-deficient B cells. These functional defects correlated with the decreased ability of B cells to present antigen and activate T cells in vitro. The in vivo germinal center response of DGKζ-deficient B cells was also reduced compared with that of wild-type B cells, indicating that loss of DGKζ in B cells impaired T cell help. Together, our data suggest that DGKζ shapes B cell responses by regulating actin remodeling, force generation, and antigen uptake-related events at the immune synapse. Hence, an appropriate balance in the amounts of DAG and PA is required for optimal B cell function.
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Linfocitos B/metabolismo , Citoesqueleto/inmunología , Diacilglicerol Quinasa/inmunología , Sinapsis Inmunológicas/inmunología , Animales , Citoesqueleto/genética , Diacilglicerol Quinasa/genética , Sinapsis Inmunológicas/genética , Ratones , Ratones NoqueadosRESUMEN
p38MAP kinase (MAPK) signal transduction pathways are important regulators of inflammation and the immune response; their involvement in immune cell development and function is still largely unknown. Here we analysed the role of the p38 MAPK isoforms p38γ and p38δ in B cell differentiation in bone marrow (BM) and spleen, using mice lacking p38γ and p38δ, or conditional knockout mice that lack both p38γ and p38δ specifically in the B cell compartment. We found that the B cell differentiation programme in the BM was not affected in p38γ/δ-deficient mice. Moreover, these mice had reduced numbers of peripheral B cells as well as altered marginal zone B cell differentiation in the spleen. Expression of co-stimulatory proteins and activation markers in p38γ/δ-deficient B cells are diminished in response to B cell receptor (BCR) and CD40 stimulation; p38γ and p38δ were necessary for B cell proliferation induced by BCR and CD40 but not by TLR4 signaling. Furthermore, p38γ/δ-null mice produced significantly lower antibody responses to T-dependent antigens. Our results identify unreported functions for p38γ and p38δ in B cells and in the T-dependent humoral response; and show that the combined activity of these kinases is needed for peripheral B cell differentiation and function.
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Bruton's tyrosine kinase (Btk) has a key role in the signaling pathways of receptors essential for the B lymphocyte response. Given its implication in B cell-related immunodeficiencies, leukemias/lymphomas and autoimmunity, Btk is studied intensely and is a target for therapy. Here, using primary B cells from distinct mouse models and the pharmacological inhibitors ibrutinib and acalabrutinib, we report distinct roles for Btk in antigen-triggered immune synapse (IS) formation. Btk recruitment to the plasma membrane regulates the B cell ability to trigger IS formation as well as its appropriate molecular assembly; Btk shuttling/scaffold activities seem more relevant than the kinase function on that. Btk-kinase activity controls antigen accumulation at the IS through the PLCγ2/Ca2+ axis. Impaired Btk membrane-recruitment or kinase function likewise alters antigen-triggered microtubule-organizing center (MTOC) polarization to the IS, B cell activation and proliferation. Data also show that, for B cell function, IS architecture is as important as the quantity of antigen that accumulates at the synapse.
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Agammaglobulinemia Tirosina Quinasa/metabolismo , Linfocitos B/inmunología , Membrana Celular/metabolismo , Sinapsis Inmunológicas/metabolismo , Adenina/análogos & derivados , Agammaglobulinemia Tirosina Quinasa/antagonistas & inhibidores , Agammaglobulinemia Tirosina Quinasa/genética , Animales , Antígenos/metabolismo , Benzamidas/farmacología , Señalización del Calcio , Polaridad Celular , Proliferación Celular , Células Cultivadas , Activación de Linfocitos , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Ratones Noqueados , Centro Organizador de los Microtúbulos , Mutación/genética , Fosfolipasa C gamma/metabolismo , Piperidinas , Transporte de Proteínas , Pirazinas/farmacología , Pirazoles/farmacología , Pirimidinas/farmacología , Receptores de Antígenos de Linfocitos B/metabolismoRESUMEN
The Myc family of oncogenic transcription factors regulates myriad cellular functions. Myc proteins contain a basic region/helix-loop-helix/leucine zipper domain that mediates DNA binding and heterodimerization with its partner Max. Among the Myc proteins, c-Myc is the most widely expressed and relevant in primary B lymphocytes. There is evidence suggesting that c-Myc can perform some of its functions in the absence of Max in different cellular contexts. However, the functional in vivo interplay between c-Myc and Max during B lymphocyte differentiation is not well understood. Using in vivo and ex vivo models, we show that while c-Myc requires Max in primary B lymphocytes, several key biological processes, such as cell differentiation and DNA replication, can initially progress without the formation of c-Myc/Max heterodimers. We also describe that B lymphocytes lacking Myc, Max, or both show upregulation of signaling pathways associated with the B-cell receptor. These data suggest that c-Myc/Max heterodimers are not essential for the initiation of a subset of important biological processes in B lymphocytes, but are required for fine-tuning the initial response after activation.
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Linfocitos B/química , Factores de Transcripción Básicos con Cremalleras de Leucinas y Motivos Hélice-Asa-Hélice/genética , Diferenciación Celular/genética , Proteínas Proto-Oncogénicas c-myc/genética , Secuencia de Aminoácidos/genética , Animales , Linfocitos B/metabolismo , Factores de Transcripción Básicos con Cremalleras de Leucinas y Motivos Hélice-Asa-Hélice/química , Replicación del ADN/genética , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/genética , Dimerización , Secuencias Hélice-Asa-Hélice/genética , Humanos , Leucina Zippers/genética , Ratones , Unión Proteica/genética , Proteínas Proto-Oncogénicas c-myc/química , Activación Transcripcional/genéticaRESUMEN
A current challenge in cell motility studies is to understand the molecular and physical mechanisms that govern chemokine receptor nanoscale organization at the cell membrane, and their influence on cell response. Using single-particle tracking and super-resolution microscopy, we found that the chemokine receptor CXCR4 forms basal nanoclusters in resting T cells, whose extent, dynamics, and signaling strength are modulated by the orchestrated action of the actin cytoskeleton, the co-receptor CD4, and its ligand CXCL12. We identified three CXCR4 structural residues that are crucial for nanoclustering and generated an oligomerization-defective mutant that dimerized but did not form nanoclusters in response to CXCL12, which severely impaired signaling. Overall, our data provide new insights to the field of chemokine biology by showing that receptor dimerization in the absence of nanoclustering is unable to fully support CXCL12-mediated responses, including signaling and cell function in vivo.
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Citoesqueleto de Actina/metabolismo , Membrana Celular/metabolismo , Movimiento Celular , Nanopartículas , Receptores CXCR4/metabolismo , Linfocitos T/metabolismo , Citoesqueleto de Actina/efectos de los fármacos , Citoesqueleto de Actina/inmunología , Secuencias de Aminoácidos , Animales , Antígenos CD4/metabolismo , Membrana Celular/efectos de los fármacos , Membrana Celular/inmunología , Quimiocina CXCL12/farmacología , Células HEK293 , Humanos , Células Jurkat , Ligandos , Ratones Endogámicos C57BL , Mutación , Multimerización de Proteína , Transporte de Proteínas , Receptores CXCR4/efectos de los fármacos , Receptores CXCR4/genética , Receptores CXCR4/inmunología , Transducción de Señal , Imagen Individual de Molécula , Linfocitos T/efectos de los fármacos , Linfocitos T/inmunologíaRESUMEN
The development of experimental systems that allow in vivo antigen tracking as well as the study of B cell dynamics in real time and in situ, have transformed our understanding of the "how, when and where" B lymphocytes find antigen at secondary lymphoid organs in the last 10 years. Here, I described one of these experimental models, which uses highly fluorescent particulate antigen and B cell receptor (BCR)-transgenic B cells labeled with long-term fluorescent probes, combined with confocal and multiphoton microscopy.
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Antígenos/inmunología , Linfocitos B/inmunología , Rastreo Celular/métodos , Ganglios Linfáticos/inmunología , Microscopía de Fluorescencia por Excitación Multifotónica/métodos , Animales , Linfocitos B/citología , Ganglios Linfáticos/citología , RatonesRESUMEN
The antigen-induced formation of an immune synapse (IS) between T cells and antigen-presenting cells results in the rapid generation of the lipid second messenger diacylglycerol (DAG) in T cells. Diacylglycerol kinase ζ (DGKζ) converts DAG into phosphatidic acid (PA). Cytotoxic T lymphocytes (CTLs) from mice deficient in DGKζ have enhanced antiviral and antitumor activities, indicating that the amount of DAG controls the effectiveness of the T cell response. We characterized the second C1 domain of protein kinase Cθ (PKCθ), a DAG-binding protein that is specifically recruited to the IS, as a biological sensor to observe the generation of a DAG gradient during IS formation. In experiments with transgenic mouse CTLs expressing the OT-I T cell receptor (TCR), we showed that both strong and weak interactions between antigen and the TCR led to the rapid generation of DAG, whereas only strong interactions induced the movement of DAG-enriched organelles toward the IS. In DGKζ-deficient CTLs, antigen stimulation led to the enhanced accumulation of DAG-containing organelles at the IS; however, impaired activation of the PA effector PKCζ resulted in lack of reorientation of the microtubule-organizing center toward the IS, a process needed for effective T cell activation. Together, these data suggest that the activation of DGKζ downstream of antigen recognition provides a mechanism that ensures the activation of PA-dependent signaling as a direct result of the strength of TCR-dependent DAG mobilization.
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Diacilglicerol Quinasa/inmunología , Diglicéridos/inmunología , Sinapsis Inmunológicas/inmunología , Orgánulos/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Linfocitos T/inmunología , Animales , Diacilglicerol Quinasa/genética , Diglicéridos/genética , Activación Enzimática/genética , Activación Enzimática/inmunología , Humanos , Sinapsis Inmunológicas/genética , Células Jurkat , Activación de Linfocitos/genética , Activación de Linfocitos/inmunología , Ratones , Ratones Noqueados , Orgánulos/genética , Receptores de Antígenos de Linfocitos T/genéticaRESUMEN
NKX2 homeobox family proteins have a role in cancer development. Here we show that NKX2-3 is overexpressed in tumour cells from a subset of patients with marginal-zone lymphomas, but not with other B-cell malignancies. While Nkx2-3-deficient mice exhibit the absence of marginal-zone B cells, transgenic mice with expression of NKX2-3 in B cells show marginal-zone expansion that leads to the development of tumours, faithfully recapitulating the principal clinical and biological features of human marginal-zone lymphomas. NKX2-3 induces B-cell receptor signalling by phosphorylating Lyn/Syk kinases, which in turn activate multiple integrins (LFA-1, VLA-4), adhesion molecules (ICAM-1, MadCAM-1) and the chemokine receptor CXCR4. These molecules enhance migration, polarization and homing of B cells to splenic and extranodal tissues, eventually driving malignant transformation through triggering NF-κB and PI3K-AKT pathways. This study implicates oncogenic NKX2-3 in lymphomagenesis, and provides a valid experimental mouse model for studying the biology and therapy of human marginal-zone B-cell lymphomas.
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Proteínas de Homeodominio/genética , Linfocitos/metabolismo , Linfoma de Células B de la Zona Marginal/genética , Receptores de Antígenos de Linfocitos B/genética , Transducción de Señal/genética , Factores de Transcripción/genética , Animales , Moléculas de Adhesión Celular/genética , Moléculas de Adhesión Celular/metabolismo , Perfilación de la Expresión Génica , Proteínas de Homeodominio/metabolismo , Humanos , Estimación de Kaplan-Meier , Tejido Linfoide/metabolismo , Linfoma de Células B de la Zona Marginal/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , Fosforilación , Receptores de Antígenos de Linfocitos B/metabolismo , Quinasa Syk/genética , Quinasa Syk/metabolismo , Factores de Transcripción/metabolismoRESUMEN
BACKGROUND AIMS: Mesenchymal stromal cells hold special interest for cell-based therapy because of their tissue-regenerative and immunosuppressive abilities. B-cell involvement in chronic inflammatory and autoimmune pathologies makes them a desirable target for cell-based therapy. Mesenchymal stromal cells are able to regulate B-cell function; although the mechanisms are little known, they imply cell-to-cell contact. METHODS: We studied the ability of human adipose tissue-derived mesenchymal stromal cells (ASCs) to attract B cells. RESULTS: We show that ASCs promote B-cell migration through the secretion of chemotactic factors. Inflammatory/innate signals do not modify ASC capacity to mediate B-cell motility and chemotaxis. Analysis of a panel of B cell-related chemokines showed that none of them appeared to be responsible for B-cell motility. Other ASC-secreted factors able to promote cell motility and chemotaxis, such as the cytokine interleukin-8 and prostaglandin E2, did not appear to be implicated. CONCLUSIONS: We propose that ASC promotion of B-cell migration by undefined secreted factors is crucial for ASC regulation of B-cell responses.
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Tejido Adiposo/metabolismo , Linfocitos B/metabolismo , Quimiotaxis , Dinoprostona/metabolismo , Interleucina-8/metabolismo , Células Madre Mesenquimatosas/metabolismo , Tejido Adiposo/citología , Linfocitos B/citología , Células Cultivadas , Técnicas de Cocultivo , Femenino , Humanos , Masculino , Células Madre Mesenquimatosas/citologíaRESUMEN
B cells use a plethora of TLR to recognize pathogen-derived ligands. These innate signals have an important function in the B cell adaptive immune response and modify their trafficking and tissue location. The direct role of TLR signaling on B cell dynamics nonetheless remains almost entirely unknown. In this study, we used a state-of-the-art two-dimensional model combined with real-time microscopy to study the effect of TLR4 stimulation on mouse B cell motility in response to chemokines. We show that a minimum stimulation period is necessary for TLR4 modification of B cell behavior. TLR4 stimulation increased B cell polarization, migration, and directionality; these increases were dependent on the MyD88 signaling pathway and did not require ERK or p38 MAPK activity downstream of TLR4. In addition, TLR4 stimulation enhanced Rac GTPase activity and promoted sustained Rac activation in response to chemokines. These results increase our understanding of the regulation of B cell dynamics by innate signals and the underlying molecular mechanisms.