RESUMEN

Memory B cells (MBCs) are essential for humoral immunological memory and can emerge during both the pre-germinal center (GC) and GC phases. However, the transcription regulators governing MBC development remain poorly understood. Here, we report that the transcription regulator Notch2 is highly expressed in MBCs and their precursors at the pre-GC stage and required for MBC development without influencing the fate of GC and plasma cells. Mechanistically, Notch2 signaling promotes the expression of complement receptor CD21 and augments B cell receptor (BCR) signaling. Reciprocally, BCR activation up-regulates Notch2 surface expression in activated B cells via a translation-dependent mechanism. Intriguingly, Notch2 is dispensable for GC-derived MBC formation. In summary, our findings establish Notch2 as a pivotal transcription regulator orchestrating MBC development through the reciprocal enforcement of BCR signaling during the pre-GC phase and suggest that the generation of GC-independent and -dependent MBCs is governed by distinct transcriptional mechanisms.

Asunto(s)

Activación de Linfocitos , Células B de Memoria , Receptor Notch2 , Receptores de Antígenos de Linfocitos B , Transducción de Señal , Animales , Receptor Notch2/metabolismo , Receptor Notch2/genética , Receptores de Antígenos de Linfocitos B/metabolismo , Ratones , Células B de Memoria/metabolismo , Células B de Memoria/inmunología , Activación de Linfocitos/inmunología , Ratones Endogámicos C57BL , Centro Germinal/inmunología , Centro Germinal/metabolismo , Linfocitos B/metabolismo , Linfocitos B/inmunología , Memoria Inmunológica , Receptores de Complemento 3d/metabolismo

RESUMEN

In order to explore a new mode for the diagnosis of angioimmunoblastic T-cell lymphoma (AITL), 31 cases of AITL and 28 cases of peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) were used as the study subjects. Identifying T follicular helper (TFH) cells with CD4, CD10, Bcl-6, and PD-1, identifying proliferative B cells with CD20 and EZH2, identifying proliferative follicular dendritic cells (FDCs) with CD21 and CD23, and analyzing the value of TFH/B/FDC proliferation and immunolocalization in the diagnosis of AITL. (1) Outside the inherent lymphoid follicles, simultaneous proliferation of TFH/B/FDC (a new diagnostic mode) were observed in AITL [83.87%; 26/31], with their immunolocalizations in the same site [83.87%; 26/31], while this phenomenon was not observed in 28 cases of PTCL-NOS (P<0.05). (2) The sensitivity and specificity of using this new mode to diagnose AITL were both high (83.87%, 100%), which was superior to CD2 (100%, 0%), CD3 (100%, 0%), CD4 (100%, 32.14%), CD5 (100%, 25%), CD10 (61.9%, 100%), Bcl-6 (42.86%, 100%), PD-1 (83.87%, 96.43%), and its Youden Index (0.84) was the highest. The areas under the curve (AUC) of CD10, Bcl-6, PD-1, and new mode to diagnosis AITL were 0.81, 0.71, 0.90, and 0.92, respectively, while the new mode had the highest AUC. The simultaneous proliferation of TFH/B/FDC cells outside the inherent lymphoid follicles can be used to assist in the diagnosis of AITL, and the simultaneous spatiotemporal proliferation of TFH/B/FDC cells is a specific immunomorphology of AITL.

Asunto(s)

Proteínas Proto-Oncogénicas c-bcl-6 , Humanos , Femenino , Masculino , Persona de Mediana Edad , Anciano , Proteínas Proto-Oncogénicas c-bcl-6/metabolismo , Neprilisina/metabolismo , Linfadenopatía Inmunoblástica/diagnóstico , Linfadenopatía Inmunoblástica/patología , Células Dendríticas Foliculares/patología , Células Dendríticas Foliculares/metabolismo , Receptor de Muerte Celular Programada 1/metabolismo , Adulto , Linfoma de Células T/diagnóstico , Linfoma de Células T/patología , Linfoma de Células T/metabolismo , Proteína Potenciadora del Homólogo Zeste 2/metabolismo , Proliferación Celular , Linfocitos B/inmunología , Linfocitos B/metabolismo , Células T Auxiliares Foliculares/inmunología , Células T Auxiliares Foliculares/metabolismo , Receptores de Complemento 3d/metabolismo , Receptores de Complemento 3d/análisis , Antígenos CD20/metabolismo , Antígenos CD20/análisis , Linfoma de Células T Periférico/diagnóstico , Linfoma de Células T Periférico/patología , Antígenos CD4/metabolismo , Sensibilidad y Especificidad , Anciano de 80 o más Años , Inmunohistoquímica/métodos , Curva ROC

RESUMEN

Porcine epidemic diarrhea virus (PEDV) is a devastating pathogen of acute- gastrointestinal infectious diseases, which can cause vomiting, diarrhea, dehydration and high morbidity and mortality among neonatal piglets. Humoral immunity plays a vital role in the host anti-PEDV infection process, but the mechanism of PEDV-induced B-cell immune response remains unknown. In this study, the effects of PEDV infection on CD21+ B cell activation were systematically analyzed through animal experiments. Enzyme-linked immunosorbent assays (ELISA) revealed that low levels of serum-specific IgA, IgM, or IgG were detected in piglets after PEDV infection, respectively. Serum interleukin (IL)-6 levels increased significantly at 4 d after infection, and the levels of IL-4, B-cell activating factor (BAFF), interferon (IFN)-γ, transforming growth factor (TGF)-ß and IL-10 decreased at 7 d after infection. Fluorescence-activated cell sorting (FACS) showed that expression levels of CD21, MHC Ⅱ, CD40, and CD38 on B cell surfaces were significantly higher. In contrast, the proportions of CD21+IgM+ B cells were decreased in peripheral blood mononuclear cells (PBMCs) from the infected piglets. No differences were found in the percentage of CD21+CD80+ and CD21+CD27+ B cells in PBMCs from the infected piglets. In addition, the number of CD21+B cells in PBMCs stimulated with PEDV in vitro was significantly lower. No significant change in the mRNA expression of BCR molecules was found while the expression levels of paired immunoglobulin-like receptor B (PIR-B), B cell adaptor molecule of 32 kDa (Bam32) and BAFF were decreased. In conclusion, our research demonstrates that virulent strains of PEDV profoundly impact B cell activation, leading to alterations in phenotypic expression and BCR signaling molecules. Furthermore, this dysregulation results in compromised specific antibody secretion and perturbed cytokine production, highlighting the intricate immunological dysfunctions induced by PEDV infection.

Asunto(s)

Linfocitos B , Infecciones por Coronavirus , Activación de Linfocitos , Virus de la Diarrea Epidémica Porcina , Receptores de Complemento 3d , Enfermedades de los Porcinos , Animales , Virus de la Diarrea Epidémica Porcina/inmunología , Porcinos , Linfocitos B/inmunología , Infecciones por Coronavirus/veterinaria , Infecciones por Coronavirus/inmunología , Infecciones por Coronavirus/virología , Receptores de Complemento 3d/inmunología , Receptores de Complemento 3d/metabolismo , Enfermedades de los Porcinos/virología , Enfermedades de los Porcinos/inmunología , Citocinas/inmunología , Citocinas/genética , Citocinas/metabolismo , Anticuerpos Antivirales/sangre , Inmunoglobulina A/sangre , Inmunoglobulina A/inmunología , Inmunoglobulina M/sangre , Inmunoglobulina M/inmunología

RESUMEN

Complement component 3d (C3d), the final cleavage product of complement component C3, interacts with CR2 and thus plays a crucial role in linking the innate and adaptive immune systems. Additionally, human C3d executes various functions in its dimeric form, which is more effective than its monomeric form. In this study, we aimed to explored whether chicken C3d (chC3d) exhibits similar characteristics, namely dimerization and binding of dimeric chC3d to chicken CR2 (chCR2). We investigated the interaction and co-localization of chC3d with itself using coimmunoprecipitation and confocal laser scanning microscopy, respectively. Then, dimeric chC3d was detected using native polyacrylamide gel electrophoresis and western blotting, and its equilibrium dissociation constant KD (827 nM) was determined using surface plasmon resonance. Finally, the interaction modes of dimeric chC3d were identified using molecular docking simulations, which revealed that dimeric chC3d could crosslink with chCR2 receptor. Overall, our findings will facilitate future explorations of the chicken complement system.

Asunto(s)

Complemento C3d , Receptores de Complemento 3d , Animales , Humanos , Receptores de Complemento 3d/química , Receptores de Complemento 3d/metabolismo , Pollos , Simulación del Acoplamiento Molecular , Factores Inmunológicos , Receptores de Complemento

RESUMEN

Complement receptor type 2 (CR2) is an important membrane molecule expressed on B cells and follicular dendritic cells. Human CR2 has been shown to play a critical role in bridging the innate complement-mediated immune response with adaptive immunity by binding complement component 3d (C3d). However, the chicken CR2 (chCR2) gene has not been identified or characterized. In this study, unannotated genes that contain short consensus repeat (SCR) domains were analyzed based on RNA sequencing data for chicken bursa lymphocytes, and a gene with >80% homology to CR2 from other bird species was obtained. The gene consisted of 370 aa and was much smaller than the human CR2 gene because 10-11 SCRs were missing. The gene was then demonstrated as a chCR2 that exhibited high binding activity to chicken C3d. Further studies revealed that chCR2 interacts with chicken C3d through a binding site in its SCR1-4 region. An anti-chCR2 mAb that recognizes the epitope 258CKEISCVFPEVQ269 was prepared. Based on the anti-chCR2 mAb, the flow cytometry and confocal laser scanning microscopy experiments confirmed that chCR2 was expressed on the surface of bursal B lymphocytes and DT40 cells. Immunohistochemistry and quantitative PCR analyses further indicated that chCR2 is predominantly expressed in the spleen, bursa, and thymus, as well as in PBLs. Additionally, the expression of chCR2 varied according to the infectious bursal disease virus infection status. Collectively, this study identified and characterized chCR2 as a distinct immunological marker in chicken B cells.

Asunto(s)

Pollos , Complemento C3d , Animales , Humanos , Complemento C3d/metabolismo , Receptores de Complemento 3d/metabolismo , Sitios de Unión , Factores Inmunológicos , Receptores de Complemento

RESUMEN

The connection of Epstein Barr virus (EBV) with diseases such as Burkitt Lymphoma, Hodgkin disease, multiple sclerosis, systemic lupus erythematosus and various B-cell lymphomas made EBV glycoproteins one of the most popular vaccine immunogens. As a protein being encoded by EBV, the viral membrane envelope protein gp350 is studied extensively due to its abundancy on the surface and its interaction with complementary receptor, CR2. The binding of CR2 and gp350 not only leads to the entrance of the virus to the B-cells, but also prevents CR2 and C3d protein interactions that are required for immune response. Thus, understanding the inhibition of gp350 activity is crucial for vaccine development. Although, the active residues on gp350 structure were determined by several mutational studies, the exact mechanism of CR2 binding is still not clear. To this end, we have performed molecular docking followed by molecular dynamics simulations and MM-PBSA on wildtype and several mutated gp350 and CR2 structures. Apart from identifying crucial amino acids, the results of per-residue decomposition energy analysis clarified the individual energy contributions of amino acids and were also found to be accurate in differentiating the active site residues in CR2 binding. Here, we highlight the role of binding region residues (linker-1) but more interestingly, the dynamic relation between the distant sites of gp350 (linker-2 and D3 residues) and CR2. These findings can lead further vaccine development strategies by pointing to the importance of computationally found novel regions that can be potentially used to modulate gp350 activity.

Asunto(s)

Infecciones por Virus de Epstein-Barr , Herpesvirus Humano 4 , Aminoácidos/metabolismo , Anticuerpos Monoclonales , Glicoproteínas/metabolismo , Herpesvirus Humano 4/metabolismo , Humanos , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Receptores de Complemento 3d/química , Receptores de Complemento 3d/metabolismo , Proteínas del Envoltorio Viral/metabolismo

RESUMEN

Marginal zone (MZ) B cells produce broad-spectrum antibodies that protect against infection early in life. In some instances, antibody production requires MZ B cells to display pathogen antigens bound to major histocompatibility complex class II (MHC II) molecules to T cells. We describe the trogocytic acquisition of these molecules from conventional dendritic cells (cDCs). Complement component 3 (C3) binds to murine and human MHC II on cDCs. MZ B cells recognize C3 with complement receptor 2 (CR2) and trogocytose the MHC II-C3 complexes, which become exposed on their cell surface. The ubiquitin ligase MARCH1 limits the number of MHC II-C3 complexes displayed on cDCs to prevent their elimination through excessive trogocytosis. Capture of C3 by MHC II thus enables the transfer of cDC-like properties to MZ B cells.

Asunto(s)

Linfocitos B/inmunología , Complemento C3/metabolismo , Células Dendríticas/inmunología , Tejido Linfoide/inmunología , Trogocitosis , Adulto , Animales , Presentación de Antígeno , Linfocitos B/metabolismo , Membrana Celular/metabolismo , Activación de Complemento , Complemento C3/inmunología , Células Dendríticas/metabolismo , Femenino , Antígenos HLA-D/inmunología , Antígenos HLA-D/metabolismo , Antígenos de Histocompatibilidad Clase II/metabolismo , Humanos , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C3H , Ratones Endogámicos C57BL , Persona de Mediana Edad , Receptores de Complemento 3d/inmunología , Receptores de Complemento 3d/metabolismo , Linfocitos T/inmunología , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitinación

RESUMEN

Strict control of B lymphocyte development is required for the ability to mount humoral immune responses to diverse foreign antigens while remaining self-tolerant. In the bone marrow, B lineage cells transit through several developmental stages in which they assemble a functional B cell receptor in a stepwise manner. The immunoglobulin heavy chain gene is rearranged at the pro-B stage. At the large pre-B stage, cells with a functional heavy chain expand in response to signals from IL-7 and the pre-BCR. Cells then cease proliferation at the small pre-B stage and rearrange the immunoglobulin light chain gene. The fully formed BCR is subsequently expressed on the surface of immature B cells and autoreactive cells are culled by central tolerance mechanisms. Once in the periphery, transitional B cells develop into mature B cell subsets such as marginal zone and follicular B cells. These developmental processes are controlled by transcription factor networks, central to which are IRF4 and IRF8. These were thought to act redundantly during B cell development in the bone marrow, with their functions diverging in the periphery where IRF4 limits the number of marginal zone B cells and is required for germinal center responses and plasma cell differentiation. Because of IRF4's unique role in mature B cells, we hypothesized that it may also have functions earlier in B cell development that cannot be compensated for by IRF8. Indeed, we find that IRF4 has a unique role in upregulating the pre-B cell marker CD25, limiting IL-7 responsiveness, and promoting migration to CXCR4 such that IRF4-deficient mice have a partial block at the pre-B cell stage. We also find that IRF4 acts in early transitional B cells to restrict marginal zone B cell development, as deletion of IRF4 in mature B cells with CD21-cre impairs plasma cell differentiation but has no effect on marginal zone B cell numbers. These studies highlight IRF4 as the dominant IRF family member in early B lymphopoiesis.

Asunto(s)

Proliferación Celular , Factores Reguladores del Interferón/metabolismo , Linfopoyesis , Células Precursoras de Linfocitos B/metabolismo , Receptores de Complemento 3d/metabolismo , Animales , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Quimiocina CXCL12/farmacología , Quimiotaxis de Leucocito , Regulación del Desarrollo de la Expresión Génica , Factores Reguladores del Interferón/genética , Interleucina-7/farmacología , Linfopoyesis/efectos de los fármacos , Ratones Endogámicos C57BL , Ratones Noqueados , Fenotipo , Células Precursoras de Linfocitos B/efectos de los fármacos , Células Precursoras de Linfocitos B/inmunología , Receptores de Complemento 3d/genética , Transducción de Señal

RESUMEN

Epstein-Barr virus (EBV) is an oncogenic herpesvirus implicated in the pathogenesis of several malignant and non-malignant conditions. However, a number of fundamental aspects about the biology of EBV and the mechanism(s) by which this virus induces pathology remain unknown. One major obstacle has been the lack of a suitable animal model for EBV infection. In this study, using our recently established rabbit model of EBV infection, we examined the early events following primary EBV infection. We show that, both immunocompetent and immunosuppressed animals were readily susceptible to EBV infection. However, immunosuppressed animals showed marked splenomegaly and widespread infection. Following EBV infection, the virus primarily targeted naïve IgM+, CD20+, CD21+ and CD79a+ B cells. Infected cells expressed varying sets of viral latent/lytic gene products. Notably, co-expression of latent and lytic proteins in the same cell was not observed. Infected cells in type 0/1 latency (EBERs+), were small and proliferating (Ki67+). By contrast, cells in type 2/3 latency (LMP1+), were large, non-proliferating (Ki-67-) and p53+. Although infected B-cells were widely present in splenic follicles, they did not express germinal center marker, BCL-6. Taken together, this study shows for the first time, some of the early events following primary EBV infection.

Asunto(s)

Infecciones por Virus de Epstein-Barr/inmunología , Centro Germinal/inmunología , Bazo/inmunología , Animales , Antígenos CD20/metabolismo , Linfocitos B/inmunología , Linfocitos B/virología , Antígenos CD79/metabolismo , Infecciones por Virus de Epstein-Barr/patología , Centro Germinal/virología , Inmunoglobulina M/inmunología , Antígeno Ki-67/metabolismo , Proteínas Proto-Oncogénicas c-bcl-6/metabolismo , Conejos , Receptores de Complemento 3d/metabolismo , Bazo/patología , Bazo/virología , Proteína p53 Supresora de Tumor/metabolismo

RESUMEN

Epstein-Barr virus (EBV)-associated gastric cancer belongs to 1 of the 4 subtypes of gastric cancer and accounts for 10% of total gastric cancers. However, most cases of gastric cancer have a history of Helicobacter pylori infection. Therefore, we investigated the possibility that H. pylori infection promotes the development of EBV-associated gastric cancer. H. pylori was exposed to principal EBV receptor, CD21, negative gastric epithelial cells, and then infected with EBV recombinant expressing enhanced green fluorescent protein. Changes in EBV infectivity due to prior H. pylori exposure were analyzed using flow cytometry. The treatment of gastric epithelial cells with H. pylori increased the efficiency of EBV infection. An increase was also observed when CagA-deficient, VacA-deficient, and FlaA-deficient H. pylori strains were used, but not when cag pathogenicity island-deficient H. pylori was used. The treatment of epithelial cells with H. pylori induced the expression of accessory EBV receptors, EphA2 and NMHC-IIA, and increased the efficiency of EBV infection depending on their expression levels. When gastric epithelial cells were treated with EPHA2 or NMHC-IIA siRNA, EBV infection via H. pylori attachment was decreased. The adhesion of H. pylori induced the expression of accessory EBV receptors in gastric epithelial cells and increased the efficiency of EBV infection.

Asunto(s)

Infecciones por Virus de Epstein-Barr/etiología , Infecciones por Helicobacter/complicaciones , Helicobacter pylori/fisiología , Herpesvirus Humano 4 , Neoplasias Gástricas/virología , Antígenos Bacterianos/metabolismo , Sitios de Ligazón Microbiológica/fisiología , Adhesión Bacteriana/fisiología , Proteínas Bacterianas/metabolismo , Línea Celular Tumoral , Células Epiteliales/efectos de los fármacos , Células Epiteliales/microbiología , Proteínas Fluorescentes Verdes/metabolismo , Infecciones por Helicobacter/metabolismo , Helicobacter pylori/efectos de los fármacos , Helicobacter pylori/genética , Herpesvirus Humano 4/metabolismo , Herpesvirus Humano 4/patogenicidad , Humanos , Hidroliasas/deficiencia , Cadenas Pesadas de Miosina/genética , Cadenas Pesadas de Miosina/metabolismo , Oxidorreductasas/deficiencia , ARN Interferente Pequeño/farmacología , Receptor EphA2/genética , Receptor EphA2/metabolismo , Receptores de Complemento 3d/metabolismo , Neoplasias Gástricas/microbiología

RESUMEN

Follicular dendritic cells (FDCs) are rare and enigmatic cells that mainly reside in germinal centers (GCs). They are capable of capturing immune complexes, via their Fc (FcRs) and complement receptors (CRs) and storing them for long periods in non-degradative vesicles. Presentation of ICs on FDCs to B cells is believed to drive affinity maturation. CR1 and CR2 are expressed on B cells and FDCs. Cr2 knock out (KO) mice, lacking both receptors, have impaired antibody and GC responses. Utilizing a novel ImageJ macro to analyze confocal fluorescence microscopy images of spleen sections, we here investigate how FDCs in wild type (WT) and Cr2 KO mice behave during the first two weeks after immunization with sheep red blood cells (SRBC). Mice were immunized with SRBC i.v. and spleen and serum samples harvested at various time points. As expected, antibody and GC responses in Cr2 KO mice were impaired in comparison to WT mice. Fewer FDCs were identified in Cr2 KO mice, and these exhibited differential localization and organization in comparison to WT mice. WT FDCs were primarily located within GCs at the light zone/dark zone border. FDCs from WT but not Cr2 KO mice were actively dispersed in GCs, i.e. tended to move away from each other, presumably to increase their surface area for B cell interaction. FDCs from Cr2 KO mice were more often found on follicles outside of the GCs and those within the GCs were closer to the periphery in comparison to WT FDCs. Expression of CR1 and CR2, FcγRIIB, and FcµR increased in FDCs from WT mice during the course of immunization. The results suggest that decreased ability to capture ICs by FDCs lacking CR1 and CR2 may not be the only explanation for the impaired GC and antibody responses in Cr2 KO mice. Poor FDC organization in GCs and failure to increase receptor expression after immunization may further contribute to the inefficient immune responses observed.

Asunto(s)

Células Dendríticas Foliculares/inmunología , Células Dendríticas Foliculares/metabolismo , Centro Germinal/inmunología , Centro Germinal/metabolismo , Imagen Molecular , Receptores de Complemento 3d/metabolismo , Receptores de Complemento/metabolismo , Animales , Formación de Anticuerpos , Complejo Antígeno-Anticuerpo/inmunología , Linfocitos B/inmunología , Linfocitos B/metabolismo , Biomarcadores , Femenino , Técnica del Anticuerpo Fluorescente , Inmunofenotipificación , Masculino , Ratones , Ratones Noqueados , Receptores Fc/metabolismo , Bazo

RESUMEN

The objective of this study was to evaluate the predictive role of CD21low B cells as markers of new digital ulcers in systemic sclerosis patients. Peripheral blood B cell subpopulations and clinical assessments have been evaluated in 74 systemic sclerosis patients at baseline and after a 12-month follow-up. After a 12-month follow-up, 23 (31.1%) systemic sclerosis patients developed new digital ulcers. The median percentage of CD21low B cells was significantly higher in patients with than without new digital ulcers [10.1 (4.3-13.6) versus 4.8 (3.5-7.4); p < 0.01]. The 10% cut-off shows good diagnostic accuracy [area under the curve (AUC) = 0.732, confidence interval (CI) = 0.587-0.878; P = 0.01]. Kaplan-Meier curves show a significantly reduced free survival from new digital ulcers in systemic sclerosis patients with CD21low B cells ≥ 10% (p < 0.0001). In multivariate analysis, CD21low B cells ≥ 10%, modified Rodnan skin score (mRSS) and systolic pulmonary arterial pressure (sPAP) are associated with the development of new digital ulcers. We hypothesize that CD21low B cells are a predictive marker of new digital ulcers in systemic sclerosis patients.

Asunto(s)

Linfocitos B/inmunología , Biomarcadores/metabolismo , Receptores de Complemento 3d/metabolismo , Esclerodermia Sistémica/inmunología , Esclerodermia Sistémica/metabolismo , Úlcera Cutánea/inmunología , Úlcera Cutánea/metabolismo , Linfocitos B/metabolismo , Femenino , Humanos , Masculino , Persona de Mediana Edad

RESUMEN

The positive coreceptor function of complement receptor type 2 [CR2 (CD21)] on B cells is generally accepted, although its role in the enhancement of antibody production had only been proven in mice. The importance of this phenomenon prompted reinvestigation of the functional consequences of coclustering CD21 and the B cell receptor (BCR) on primary human cells. We found that, at non-stimulatory concentrations of anti-IgG/A/M, coclustering the BCR and CR2 enhanced the Ca2+ response, while activation marker expression, cytokine production, proliferation, and antibody production were all inhibited upon the coengagement of CR2 and BCR on human B cells. Thus, the "textbook dogma" claiming that C3d acts as an adjuvant to enhance humoral immunity is relevant only to mice and not to humans.

Asunto(s)

Formación de Anticuerpos/inmunología , Linfocitos B/inmunología , Linfocitos B/metabolismo , Activación de Linfocitos/inmunología , Receptores de Antígenos de Linfocitos B/metabolismo , Receptores de Complemento 3d/metabolismo , Formación de Anticuerpos/genética , Antígenos CD/metabolismo , Antígenos de Diferenciación de Linfocitos T/metabolismo , Biomarcadores , Células Cultivadas , Citocinas/metabolismo , Humanos , Lectinas Tipo C/metabolismo , Activación de Linfocitos/genética , Unión Proteica

RESUMEN

Human memory B cells (MBCs) are generated and diversified in secondary lymphoid tissues throughout the organism. A paired immunoglobulin (Ig)-gene repertoire analysis of peripheral blood (PB) and splenic MBCs from infant, adult, and elderly humans revealed that throughout life, circulating MBCs are comprehensively archived in the spleen. Archive MBC clones are systematically preserved and uncoupled from class-switching. Clonality in the spleen increases steadily, but boosts at midlife, thereby outcompeting small clones. The splenic marginal zone (sMZ) represents a primed MBC compartment, generated from a stochastic exchange within the archive memory pool. This is supported by functional assays, showing that PB and splenic CD21+ MBCs acquire transient CD21high expression upon NOTCH2-stimulation. Our study provides insight that the human MBC system in PB and spleen is composed of three interwoven compartments: the dynamic relationship of circulating, archive, and its subset of primed (sMZ) memory changes with age, thereby contributing to immune aging.

Asunto(s)

Envejecimiento/inmunología , Linfocitos B/inmunología , Memoria Inmunológica , Bazo/inmunología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Animales , Biopsia , Donantes de Sangre , Línea Celular , Niño , Preescolar , Técnicas de Cocultivo , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Células Madre Mesenquimatosas/metabolismo , Ratones , Persona de Mediana Edad , Fenotipo , Receptores de Complemento 3d/metabolismo , Bazo/patología , Adulto Joven

RESUMEN

BACKGROUND: Diffuse large B cell lymphoma (DLBCL) is the commonest lymphoma that is highly aggressive where one-third of the patients relapse despite effective treatment. Interaction between the lymphoma cells and the non-clonal immune cells within the bone marrow microenvironment is thought to play a critical role in the pathogenesis of DLBCL. METHODS: We used flow cytometry to characterize the proportion of B cell subpopulations in the bone marrow (N = 47) and peripheral blood (N = 54) of 75 DLBCL patients at diagnosis and study their impact on survival. RESULTS: Anergic B cells in the bone marrow (BM), characterized as having CD21(-/low)/CD38- expression, influenced survival with high numbers (defined as > 13.9%) being associated with significantly shorter overall survival (59.7 months vs 113.6 months, p = 0.0038). Interestingly, low numbers of anergic B cells in the BM (defined as ≤13.9%) was associated with germinal center B cell type of DLBCL (p = 0.0354) that is known to have superior rates of survival when compared to activated B cell type. Finally, Cox regression analysis in our cohort of patients established that the inferior prognosis of having high numbers of anergic B cells in the bone marrow was independent of the established Revised International Prognostic Index (R-IPI) score. CONCLUSIONS: High proportion of anergic B cells in the BM characterized by CD21(-/low)/CD38- expression predicts poor survival outcomes in DLBCL.

Asunto(s)

ADP-Ribosil Ciclasa 1/metabolismo , Linfocitos B/inmunología , Médula Ósea/inmunología , Linfoma de Células B Grandes Difuso/mortalidad , Glicoproteínas de Membrana/metabolismo , Receptores de Complemento 3d/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Anergia Clonal , Regulación hacia Abajo , Femenino , Citometría de Flujo , Humanos , Linfoma de Células B Grandes Difuso/inmunología , Masculino , Persona de Mediana Edad , Pronóstico , Análisis de Regresión , Análisis de Supervivencia

RESUMEN

Rationale: A subpopulation of B cells (age-associated B cells [ABCs]) is increased in mice and humans with infections or autoimmune diseases. Because depletion of these cells might be valuable in patients with certain lung diseases, the goal was to find out if ABC-like cells were at elevated levels in such patients.Objectives: To measure ABC-like cell percentages in patients with lung granulomatous diseases.Methods: Peripheral blood and BAL cells from patients with sarcoidosis, beryllium sensitivity, or hypersensitivity pneumonitis and healthy subjects were analyzed for the percentage of B cells that were ABC-like, defined by expression of CD11c, low levels of CD21, FcRL 1-5 (Fc receptor-like protein 1-5) expression, and, in some cases, T-bet.Measurements and Main Results: ABC-like cells in blood were at low percentages in healthy subjects and higher percentages in patients with sarcoidosis as well as at high percentages among BAL cells of patients with sarcoidosis, beryllium disease, and hypersensitivity pneumonitis. Treatment of patients with sarcoidosis led to reduced percentages of ABC-like cells in blood.Conclusions: Increased levels of ABC-like cells in patients with sarcoidosis may be useful in diagnosis. The increase in percentage of ABC-like cells in patients with lung granulomatous diseases and decrease in treated patients suggests that depletion of these cells may be valuable.

Asunto(s)

Alveolitis Alérgica Extrínseca/sangre , Subgrupos de Linfocitos B/metabolismo , Beriliosis/sangre , Líquido del Lavado Bronquioalveolar/citología , Sarcoidosis Pulmonar/sangre , Adulto , Anciano , Anciano de 80 o más Años , Alveolitis Alérgica Extrínseca/inmunología , Subgrupos de Linfocitos B/inmunología , Beriliosis/inmunología , Antígeno CD11c/metabolismo , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Proteínas de la Membrana/metabolismo , Persona de Mediana Edad , Receptores de Superficie Celular/metabolismo , Receptores de Complemento 3d/metabolismo , Receptores Fc/metabolismo , Receptores Inmunológicos/metabolismo , Sarcoidosis Pulmonar/inmunología , Proteínas de Dominio T Box/metabolismo , Adulto Joven

RESUMEN

Purpose: Risk for age-related macular degeneration (AMD), a slowly progressing, complex disease, is tied to an overactive complement system. Efforts are under way to develop an anticomplement-based treatment to be delivered locally or systemically. We developed an alternative pathway (AP) inhibitor fusion protein consisting of a complement receptor-2 fragment linked to the inhibitory domain of factor H (CR2-fH), which reduces the size of mouse choroidal neovascularization (CNV) when delivered locally or systemically. Specifically, we confirmed that ARPE-19 cells genetically engineered to produce CR2-fH reduce CNV lesion size when encapsulated and placed intravitreally. We extend this observation by delivering the encapsulated cells systemically in Matrigel. Methods: ARPE-19 cells were generated to stably express CR2 or CR2-fH, microencapsulated using sodium alginate, and injected subcutaneously in Matrigel into 2-month-old C57BL/6J mice. Four weeks after implantation, CNV was induced using argon laser photocoagulation. Progression of CNV was analyzed using optical coherence tomography. Bioavailability of CR2-fH was evaluated in Matrigel plugs with immunohistochemistry, as well as in ocular tissue with dot blots. Efficacy as an AP inhibitor was confirmed with protein chemistry. Results: An efficacious number of implanted capsules to reduce CNV was identified. Expression of the fusion protein systemically did not elicit an immune response. Bioavailability studies showed that CR2-fH was present in the RPE/choroid fractions of the treated mice, and reduced CNV-associated ocular complement activation. Conclusions: These findings indicate that systemic production of the AP inhibitor CR2-fH can reduce CNV in the mouse model.

Asunto(s)

Cápsulas/química , Encapsulación Celular/métodos , Neovascularización Coroidal/metabolismo , Neovascularización Coroidal/terapia , Colágeno/química , Factor H de Complemento/antagonistas & inhibidores , Inactivadores del Complemento/farmacología , Laminina/química , Proteoglicanos/química , Animales , Disponibilidad Biológica , Línea Celular , Factor H de Complemento/metabolismo , Inactivadores del Complemento/metabolismo , Combinación de Medicamentos , Expresión Génica , Humanos , Inmunohistoquímica , Ratones , Ratones Endogámicos C57BL , Microscopía Fluorescente , Dominios Proteicos , Receptores de Complemento 3d/genética , Receptores de Complemento 3d/metabolismo , Proteínas Recombinantes , Tomografía de Coherencia Óptica

RESUMEN

Background: Multiple lines of evidence have suggested that genetic factors may contribute to steroid-induced osteonecrosis of the femoral head (SONFH). Complement receptor 2 (CR2), constituting a family of regulators of complement activation, has been recently reported to be associated with osteonecrosis of the femoral head (ONFH) in Koreans. The aim of this study was to evaluate the relationships between polymorphisms of the CR2 gene and susceptibility to SONFH in the male Han Chinese population. Materials and Methods: A total of 468 SONFH patients and 1224 healthy controls were recruited for this study. Ten tag single nucleotide polymorphisms (SNPs) located within the CR2 gene were genotyped. Genetic association analyses, including SNP and haplotypic analyses, were performed for the 10 SNPs. Furthermore, bioinformatic analyses were conducted to examine the functional consequences of SNPs shown to be significantly associated with SONFH. Results: An intronic SNP, rs311306, was identified to be significantly associated with the risk of SONFH (p = 0.0008, odds ratio = 1.44). Allelic analyses showed that the C allele of this SNP significantly elevated the risk of SONFH, which was replicated in genotypic association analyses. Moreover, a 3-SNP haplotype was significantly associated with SONFH (rs311306-rs17044576-rs3767933, p = 7.49 × 10-8). Furthermore, bioinformatic analyses indicated limited functional consequences of SNP rs311306, but a complex interaction network was constructed for the protein encoded by the SLC44A2 gene and proteins encoded by the CD19, CD81, and C3 genes. Conclusion: Our findings shed new light on the link between the CR2 gene and SONFH in Han Chinese males, providing clues as to the nature of the mechanisms involved in the etiology of ONFH.

Asunto(s)

Necrosis de la Cabeza Femoral/genética , Receptores de Complemento 3d/genética , Adulto , Alelos , Pueblo Asiatico/genética , Estudios de Casos y Controles , China/epidemiología , Etnicidad/genética , Cabeza Femoral/metabolismo , Frecuencia de los Genes/genética , Predisposición Genética a la Enfermedad/genética , Genotipo , Haplotipos , Humanos , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Osteonecrosis/genética , Polimorfismo de Nucleótido Simple/genética , Receptores de Complemento 3d/metabolismo , Esteroides/efectos adversos , Esteroides/farmacología

RESUMEN

We aimed to assess expression of genes encoding the heterodimeric IL-27 cytokine and constituent subunits of the Il-27 receptor in rheumatoid arthritis (RA), including in extra-articular, subcutaneous rheumatoid nodules. Comparing between nodules and joint synovia, significantly elevated expression of IL27A within nodules, and comparable IL27B expression, identified nodules as a significant source of IL-27 in RA. T-lymphocytes were the main source of IL27RA transcript, and IL27RA expression correlated with a number of plasma cytokines, as well as tissue TNF expression in both nodules and RA synovia. In synovia, correlations between IL27A, IL27RA IL17A and CD21L expression, and significantly elevated expression of the genes encoding IL-27, associated the presence of IL-27 with B cell-dominated synovial inflammation. Impact from nodule derived IL-27 on systemic or synovial inflammation in RA remains unknown and further study of these implications is required. Our study raises questions regarding the appropriate circumstances for the blockade or administration of IL-27 as a potential therapeutic adjunct in RA.

Asunto(s)

Artritis Reumatoide/genética , Inflamación/genética , Interleucina-17/metabolismo , Interleucinas/genética , Interleucinas/metabolismo , Receptores de Complemento 3d/metabolismo , Anciano , Artritis Reumatoide/inmunología , Linfocitos B/metabolismo , Femenino , Expresión Génica , Humanos , Interleucina-17/genética , Masculino , Persona de Mediana Edad , Receptores de Complemento 3d/genética , Nódulo Reumatoide/inmunología , Nódulo Reumatoide/patología , Membrana Sinovial/inmunología , Membrana Sinovial/patología

RESUMEN

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of coronavirus disease 2019 (COVID-19), which has become a public health emergency of international concern1. Angiotensin-converting enzyme 2 (ACE2) is the cell-entry receptor for severe acute respiratory syndrome coronavirus (SARS-CoV)2. Here we infected transgenic mice that express human ACE2 (hereafter, hACE2 mice) with SARS-CoV-2 and studied the pathogenicity of the virus. We observed weight loss as well as virus replication in the lungs of hACE2 mice infected with SARS-CoV-2. The typical histopathology was interstitial pneumonia with infiltration of considerable numbers of macrophages and lymphocytes into the alveolar interstitium, and the accumulation of macrophages in alveolar cavities. We observed viral antigens in bronchial epithelial cells, macrophages and alveolar epithelia. These phenomena were not found in wild-type mice infected with SARS-CoV-2. Notably, we have confirmed the pathogenicity of SARS-CoV-2 in hACE2 mice. This mouse model of SARS-CoV-2 infection will be valuable for evaluating antiviral therapeutic agents and vaccines, as well as understanding the pathogenesis of COVID-19.

Asunto(s)

Betacoronavirus/patogenicidad , Infecciones por Coronavirus/patología , Infecciones por Coronavirus/virología , Pulmón/patología , Peptidil-Dipeptidasa A/genética , Peptidil-Dipeptidasa A/metabolismo , Neumonía Viral/patología , Neumonía Viral/virología , Transgenes , Enzima Convertidora de Angiotensina 2 , Animales , Antígenos Virales/inmunología , Antígenos Virales/metabolismo , Betacoronavirus/inmunología , Betacoronavirus/metabolismo , Bronquios/patología , Bronquios/virología , COVID-19 , Infecciones por Coronavirus/inmunología , Modelos Animales de Enfermedad , Células Epiteliales/patología , Células Epiteliales/virología , Femenino , Humanos , Inmunoglobulina G/inmunología , Pulmón/inmunología , Pulmón/virología , Linfocitos/inmunología , Macrófagos Alveolares/inmunología , Macrófagos Alveolares/virología , Masculino , Ratones , Ratones Transgénicos , Pandemias , Neumonía Viral/inmunología , Receptores de Complemento 3d/genética , Receptores de Complemento 3d/metabolismo , SARS-CoV-2 , Replicación Viral , Pérdida de Peso