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1.
Microb Pathog ; 172: 105759, 2022 Nov.
Article in English | MEDLINE | ID: mdl-36087692

ABSTRACT

Porcine pleuropneumonia caused by Actinobacillus pleuropneumoniae affects pig health status and the swine industry worldwide. Despite the extensive number of studies focused on A. pleuropneumoniae infection and vaccine development, a thorough analysis of the A. pleuropneumoniae exoproteome is still missing. Using a complementary approach of quantitative proteomics and immunoproteomics we gained an in-depth insight into the A. pleuropneumoniae serotype 2 exoproteome, which provides the basis for future functional studies. Label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) revealed 593 exoproteins, of which 104 were predicted to be virulence factors. The RTX toxins ApxIIA and ApxIIIA -were found to be the most abundant proteins in the A. pleuropneumoniae serotype 2 exoproteome. Furthermore, the ApxIVA toxin was one of the proteins showing the highest abundance, although ApxIVA is commonly assumed to be expressed exclusively in vivo. Our study revealed several antigens, including proteins with moonlight functions, such as the elongation factor (EF)-Tu, and proteins linked to specific metabolic traits, such as the maltodextrin-binding protein MalE, that warrant future functional characterization and might present potential targets for novel therapeutics and vaccines. Our Ig-classes specific serological proteome analysis (SERPA) approach allowed us to explore the development of the host humoral immune response over the course of the infection. These SERPAs pinpointed proteins that might play a key role in virulence and persistence and showed that the immune response to the different Apx toxins is distinct. For instance, our results indicate that the ApxIIIA toxin has properties of a thymus-independent antigen, which should be studied in more detail.


Subject(s)
Actinobacillus Infections , Actinobacillus pleuropneumoniae , Mycoplasma , Pleuropneumonia , Swine Diseases , Swine , Animals , Pleuropneumonia/veterinary , Actinobacillus Infections/veterinary , Proteomics , Proteome/metabolism , Antigens, T-Independent/metabolism , Chromatography, Liquid , Bacterial Proteins/metabolism , Tandem Mass Spectrometry , Virulence Factors/metabolism , Peptide Elongation Factors
2.
World J Microbiol Biotechnol ; 36(11): 161, 2020 Sep 29.
Article in English | MEDLINE | ID: mdl-32989599

ABSTRACT

Structurally diverse biopolymers, including extracellular polysaccharides (EPS), synthesized by bacteria can possess physicochemical and functional properties that make them important products of microbial synthesis with a broad and versatile biotechnological potential. Leuconostoc spp. belongs to the group of lactic acid bacteria as one of the predominant members and are relevant not only in varied food fermentations, but also can be employed in the production of extracellular homopolysaccharides (HoPS) such as α-glucans (dextran, alternan) and ß-fructans (levan,inulin) from the sucrose-containing substrates. EPS are synthesized by specific Leuconostoc spp. extracellular glycosyltransferases [dextran sucrase, alternansucrase (ASR)] and fructosyltransferases (levansucrase, inulosucrase) and enzymatic reactions can be performed in whole culture systems as well as using cell-free enzymes. Both α-glucans and ß-fructans have a wide range of properties, mostly depending on their pattern of linkages, which, although differing in some respects, make suitable prerequisites for their versatile application in many fields, especially in the food industry and biomedicine. As a rule, these properties (polymer type, molecular mass, rheological parameters), as well as the overall EPS yield, are strain-specific for the selected producers and depend to a large extent on the nutritional and growth conditions used, which in many cases remain not sufficiently optimized for Leuconostoc spp. This review summarizes the current knowledge on the potential of Leuconostoc spp. to produce commercially relevant EPS, including information on their applications in various fields, producer strains, production methods and techniques used, selected conditions, the productivity of bioprocesses as well as the possible use of renewable resources for their development.


Subject(s)
Leuconostoc/metabolism , Polysaccharides, Bacterial/metabolism , Antigens, T-Independent/metabolism , Dextrans/metabolism , Fructans/metabolism , Glucans/metabolism , Glycosyltransferases/metabolism , Inulin/metabolism , Molecular Weight , Sucrase/metabolism , Sucrose/metabolism
3.
J Med Chem ; 63(21): 12526-12541, 2020 11 12.
Article in English | MEDLINE | ID: mdl-32696648

ABSTRACT

Autoreactive B cell-derived antibodies form immune complexes that likely play a pathogenic role in autoimmune diseases. In systemic lupus erythematosus (SLE), these antibodies bind Fc receptors on myeloid cells and induce proinflammatory cytokine production by monocytes and NETosis by neutrophils. Bruton's tyrosine kinase (BTK) is a non-receptor tyrosine kinase that signals downstream of Fc receptors and plays a transduction role in antibody expression following B cell activation. Given the roles of BTK in both the production and sensing of autoreactive antibodies, inhibitors of BTK kinase activity may provide therapeutic value to patients suffering from autoantibody-driven immune disorders. Starting from an in-house proprietary screening hit followed by structure-based rational design, we have identified a potent, reversible BTK inhibitor, BIIB068 (1), which demonstrated good kinome selectivity with good overall drug-like properties for oral dosing, was well tolerated across preclinical species at pharmacologically relevant doses with good ADME properties, and achieved >90% inhibition of BTK phosphorylation (pBTK) in humans.


Subject(s)
Agammaglobulinaemia Tyrosine Kinase/antagonists & inhibitors , Protein Kinase Inhibitors/chemistry , Pyrimidines/chemistry , Administration, Oral , Agammaglobulinaemia Tyrosine Kinase/metabolism , Animals , Antigens, T-Independent/chemistry , Antigens, T-Independent/metabolism , Autoimmune Diseases/drug therapy , Autoimmune Diseases/immunology , Autoimmune Diseases/pathology , Binding Sites , Catalytic Domain , Dogs , Drug Evaluation, Preclinical , Female , Half-Life , Humans , Mice , Microsomes, Liver/metabolism , Molecular Dynamics Simulation , Protein Kinase Inhibitors/metabolism , Protein Kinase Inhibitors/therapeutic use , Pyrimidines/metabolism , Pyrimidines/therapeutic use , Rats , Structure-Activity Relationship
4.
Cell Rep ; 23(11): 3152-3159, 2018 06 12.
Article in English | MEDLINE | ID: mdl-29898388

ABSTRACT

Transitioning from a metabolically quiescent naive B cell to an antibody-secreting plasmablast requires division-dependent cellular differentiation. Though cell division demands significant ATP and metabolites, the metabolic processes used for ATP synthesis during plasmablast formation are not well described. Here, the metabolic requirements for plasmablast formation were determined. Following T-independent stimulation with lipopolysaccharide, B cells increased expression of the oxidative phosphorylation machinery in a stepwise manner. Such activated B cells have increased capacity to perform oxidative phosphorylation but showed dependency on glycolysis. Plasmablasts displayed higher oxidative metabolism to support antibody secretion, as inhibiting oxidative ATP production resulted in decreased antibody titers. Differentiation by Blimp1 was required for this increase in oxidative metabolism, as Blimp1-deficient cells proliferate but do not upregulate oxidative phosphorylation. Together, these findings identify a shift in metabolic pathways as B cells differentiate, as well as the requirement for increased metabolic potential to support antibody production.


Subject(s)
Antigens, T-Independent/metabolism , B-Lymphocytes/metabolism , Oxidative Phosphorylation , Plasma Cells/metabolism , Adenosine Triphosphate/metabolism , Animals , Antibodies/metabolism , B-Lymphocytes/cytology , Cell Differentiation , Female , Glycolysis/genetics , Lipopolysaccharides/pharmacology , Male , Metabolic Networks and Pathways , Mice , Mice, Inbred C57BL , Mice, Knockout , Oxidative Phosphorylation/drug effects , Plasma Cells/cytology , Positive Regulatory Domain I-Binding Factor 1/deficiency , Positive Regulatory Domain I-Binding Factor 1/genetics , Positive Regulatory Domain I-Binding Factor 1/metabolism , Up-Regulation
5.
Eur J Immunol ; 44(3): 662-72, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24242887

ABSTRACT

Formation of the splenic marginal zone (MZ) depends on the alternative NF-κB signaling pathway. Recently, we reported that unrestricted activation of this pathway in NF-κB2/p100-deficient (p100(-/-) ) knock-in mice alters the phenotype of MZ stroma and B cells. Here, we show that lack of the p100 inhibitor resulted in an expansion of both MZ B and peritoneal B-1 cells. However, these cells failed to generate proliferating blasts in response to T-cell-independent type 2 (TI-2) Ags, correlating with dampened IgM and absent IgG3 responses. This phenotype was in part due to increased activity of the NF-κB subunit RelB. Moreover, p100(-/-) →B6 BM chimeras were more susceptible to infection by encapsulated Streptococcus pneumoniae bacteria, pathogens that induce TI-2 responses. In contrast to the TI-2 defect, p100 deficiency did not impair immune responses to the TI-1 Ag LPS and p100(-/-) MZ B cells showed normal Ag transportation into B-cell follicles. Furthermore, p100(-/-) MZ B and B-1 cells failed to respond to TI-2 Ags in the presence of WT accessory cells. Thus, NF-κB2/p100 deficiency caused a predominant B-cell-intrinsic TI-2 defect that could largely be attributed to impaired proliferation of plasmablasts. Importantly, p100 was also necessary for efficient defense against clinically relevant TI-2 pathogens.


Subject(s)
Antigens, T-Independent/immunology , B-Lymphocyte Subsets/immunology , B-Lymphocyte Subsets/metabolism , NF-kappa B p52 Subunit/deficiency , Animals , Antibody Formation/genetics , Antibody Formation/immunology , Antigens, T-Independent/metabolism , B-Lymphocyte Subsets/drug effects , Bacteria/immunology , Bacterial Infections/genetics , Bacterial Infections/immunology , Cell Movement/genetics , Cytokines/pharmacology , Genetic Predisposition to Disease , Immunity, Humoral/genetics , Mice , Mice, Knockout , NF-kappa B p52 Subunit/genetics , NF-kappa B p52 Subunit/metabolism , Protein Binding , Protein Transport , Receptors, Antigen, B-Cell/metabolism , Toll-Like Receptors/metabolism , Transcription Factor RelB/genetics , Transcription Factor RelB/metabolism
6.
J Immunol ; 186(10): 5620-8, 2011 May 15.
Article in English | MEDLINE | ID: mdl-21490159

ABSTRACT

Memory B cells generated during a T cell-dependent immune response rapidly respond to a secondary immunization by producing abundant IgG Abs that bind cognate Ag with high affinity. It is currently unclear whether this heightened recall response by memory B cells is due to augmented IgG-BCR signaling, which has only been demonstrated in the context of naive transgenic B cells. To address this question, we examined whether memory B cells can respond in vivo to Ags that stimulate only through BCR, namely T cell-independent type II (TI-II) Ags. In this study, we show that the TI-II Ag (4-hydroxy-3-nitrophenyl) acetyl (NP)-Ficoll cannot elicit the recall response in mice first immunized with the T cell-dependent Ag NP-chicken γ-globulin. Moreover, the NP-Ficoll challenge in vivo as well as in vitro significantly inhibits a subsequent recall response to NP-chicken γ-globulin in a B cell-intrinsic manner. This NP-Ficoll-mediated tolerance is caused by the preferential elimination of IgG(+) memory B cells binding to NP with high affinity. These data indicate that BCR cross-linking with a TI-II Ag does not activate IgG(+) memory B cells, but rather tolerizes them, identifying a terminal checkpoint of memory B cell differentiation that may prevent autoimmunity.


Subject(s)
Antigens, T-Independent/immunology , B-Lymphocytes/immunology , Immune Tolerance , Immunoglobulin G/biosynthesis , Immunologic Memory , Adoptive Transfer , Animals , Antigens, T-Independent/metabolism , Base Sequence , Enzyme-Linked Immunosorbent Assay , Ficoll/analogs & derivatives , Ficoll/immunology , Flow Cytometry , Lymphocyte Activation , Mice , Mice, Inbred C57BL , Microscopy, Fluorescence , Polymerase Chain Reaction , Receptors, Antigen/immunology , Receptors, Antigen/metabolism , Signal Transduction , gamma-Globulins/immunology
7.
Int Immunol ; 21(11): 1225-37, 2009 Nov.
Article in English | MEDLINE | ID: mdl-19737782

ABSTRACT

CD81 is a component of the CD19/CD21 co-receptor complex in B cells. However, the role of CD81 in B cell activation has not been clearly elucidated. Here, we demonstrate that Cd81(-/-) B cells stimulated via their B cell receptor fluxed higher intracellular-free calcium ion along with increased phosphorylation of spleen tyrosine kinase and phospholipase gamma 2. Additionally, Cd81(-/-) B cells responded to toll like receptor 4 stimulation with increased nuclear factor-kappa B activation, cell proliferation and antibody secretion compared with wild-type B cells. Cd81(-/-) mice also mounted a significantly higher immune response to T-independent antigens than their wild-type counterparts. Finally, analysis of Cd81(-/-) B cells that were generated by bone marrow transplantation into Rag1(-/-) mice confirmed that the hyperactive phenotype is not dependent on the CD81-deficient environment. Taken together, these results indicate that CD81 plays a negative role in B cell activation in vitro and in vivo.


Subject(s)
Antigens, CD/immunology , Antigens, CD/metabolism , Antigens, T-Independent/immunology , B-Lymphocytes/immunology , Calcium/metabolism , Adoptive Transfer , Animals , Antigens, CD/genetics , Antigens, T-Independent/metabolism , B-Lymphocytes/metabolism , Calcium/immunology , Homeodomain Proteins/genetics , Homeodomain Proteins/immunology , Homeodomain Proteins/metabolism , Lymphocyte Activation/immunology , Mice , Mice, Inbred BALB C , Mice, Knockout , NF-kappa B/immunology , NF-kappa B/metabolism , Phosphorylation/immunology , Protein-Tyrosine Kinases/immunology , Protein-Tyrosine Kinases/metabolism , Tetraspanin 28 , Toll-Like Receptor 4/immunology , Toll-Like Receptor 4/metabolism
8.
Biochem J ; 417(3): 673-83, 2009 Feb 01.
Article in English | MEDLINE | ID: mdl-18925876

ABSTRACT

CD22 [Siglec-2 (sialic acid-binding, immunoglobulin-like lectin-2)], a negative regulator of B-cell signalling, binds to alpha2,6- sialic acid-linked glycoconjugates, including a sialyl-Tn antigen that is one of the typical tumour-associated carbohydrate antigens expressed on various mucins. Many epithelial tumours secrete mucins into tissues and/or the bloodstream. Mouse mammary adenocarcinoma cells, TA3-Ha, produce a mucin named epiglycanin, but a subline of them, TA3-St, does not. Epiglycanin binds to CD22 and inhibits B-cell signalling in vitro. The in vivo effect of mucins in the tumour-bearing state was investigated using these cell lines. It should be noted that splenic MZ (marginal zone) B-cells were dramatically reduced in the mice bearing TA3-Ha cells but not in those bearing TA3-St cells, this being consistent with the finding that the thymus-independent response was reduced in these mice. When the mucins were administered to normal mice, a portion of them was detected in the splenic MZ associated with the MZ B-cells. Furthermore, administration of mucins to normal mice clearly reduced the splenic MZ B-cells, similar to tumour-bearing mice. These results indicate that mucins in the bloodstream interacted with CD22, which led to impairment of the splenic MZ B-cells in the tumour-bearing state.


Subject(s)
Adenocarcinoma/metabolism , B-Lymphocytes/immunology , Mucins/metabolism , Sialic Acid Binding Ig-like Lectin 2/metabolism , Spleen/immunology , Adenocarcinoma/immunology , Animals , Antigens, T-Independent/immunology , Antigens, T-Independent/metabolism , B-Lymphocytes/metabolism , Binding Sites , CHO Cells , Cell Line, Tumor , Cricetinae , Cricetulus , Female , Membrane Glycoproteins/metabolism , Mice , Mice, Inbred Strains , Receptors, Antigen, B-Cell/metabolism , Sialic Acid Binding Ig-like Lectin 2/immunology , Signal Transduction
9.
J Autoimmun ; 31(4): 345-53, 2008 Dec.
Article in English | MEDLINE | ID: mdl-18845419

ABSTRACT

B6.Sle1b mice, which contain the Sle1b gene interval derived from lupus prone NZM2410 mice on a C57BL/6 background, present with gender-biased, highly penetrant anti-nuclear antibody (ANA) production. To obtain some insight into the possible induction mechanism of autoantibodies in these mice we compared antigen-specific T dependent (TD) and T independent (TI-II) responses between B6.Sle1b and B6 mice before the development of high ANA titers. Our results show that B6.Sle1b mice mount enhanced responses to a TI-II antigen. Additionally, the memory T cell response generated by a TD antigen also increased. This enhancement correlates with the greater ability of B cells from B6.Sle1b mice to present antigen to T cells. The SLAM Associated Protein (SAP) is critical for signaling of many of the molecules encoded by the SLAM/CD2 gene cluster, candidates for mediating the Sle1b phenotype; therefore, we also investigated the effect of sap deletion in these strains on the TD and TI-II responses as well as on ANA production. The results of these studies of responses to non-self-antigens provide further insight into the mechanism by which responses to self-antigens might be initiated in the context of specific genetic alterations.


Subject(s)
Antibodies, Antinuclear/immunology , Intracellular Signaling Peptides and Proteins/immunology , Lupus Erythematosus, Systemic/immunology , T-Lymphocytes/immunology , Animals , Antibodies, Antinuclear/biosynthesis , Antigen Presentation/immunology , Antigens, T-Independent/immunology , Antigens, T-Independent/metabolism , B-Lymphocytes/immunology , B-Lymphocytes/metabolism , Intracellular Signaling Peptides and Proteins/genetics , Killer Cells, Natural/immunology , Killer Cells, Natural/metabolism , Lupus Erythematosus, Systemic/metabolism , Lymphocyte Activation/immunology , Mice , Mice, Inbred C57BL , Mice, Knockout , Signal Transduction , Signaling Lymphocytic Activation Molecule Associated Protein , T-Lymphocytes/metabolism
10.
Curr Top Microbiol Immunol ; 319: 17-40, 2008.
Article in English | MEDLINE | ID: mdl-18080413

ABSTRACT

While most complex antigens can induce antibody responses in a mature immunological system, this is not the case when injected into ontogenetically immature systems, as are found in neonates and pediatric-age children. Thus the antibody response to polysaccharides, which would in theory provide protection against infection by all polysaccharide encapsulated bacteria, including Streptococcus pneumoniae, Neisseria meningitides, and Haemophilus influenzae, cannot be stimulated by immunization with the polysaccharides by themselves. It was only with the introduction of conjugate vaccines that protection from these bacterial infections was provided to this susceptible age group. The introduction of these conjugate vaccines into the arsenal of vaccines serves as a remarkable example of how valuable it is to understand the mechanisms of biological processes. Many years of intense laboratory investigation demonstrated that when polysaccharides are covalently conjugated to proteins, the characteristics of the immune response are similar to that of the protein rather than the polysaccharide. These characteristics would induce an anti-polysaccharide response even in the pediatric population, which was heretofore unable to mount protective responses to the polysaccharide. With the advent of conjugate vaccines for the above three mentioned bacteria, the incidence of bacteremia, meningitis, and otitis media has almost been eliminated. This chapter discusses in some detail the mechanisms which underlie the effectiveness of conjugate vaccines and discusses some of the vaccines that have been commercialized.


Subject(s)
Antibodies, Bacterial/immunology , Antigens, Bacterial/immunology , Antigens, T-Independent/immunology , Bacterial Vaccines/immunology , Polysaccharides, Bacterial/immunology , Animals , Antibodies, Bacterial/biosynthesis , Antigens, T-Independent/metabolism , Humans , Polysaccharides, Bacterial/metabolism , Vaccines, Conjugate/immunology , Vaccines, Conjugate/microbiology
11.
Curr Top Microbiol Immunol ; 319: 105-30, 2008.
Article in English | MEDLINE | ID: mdl-18080416

ABSTRACT

Pathogenesis of infectious disease is not only determined by the virulence of the microbe but also by the immune status of the host. Vaccination is the most effective means to control infectious diseases. A hallmark of the adaptive immune system is the generation of B cell memory, which provides a long-lasting protective antibody response that is central to the concept of vaccination. Recent studies revealed a distinct function for B1b lymphocytes, a minor subset of mature B cells that closely resembles that of memory B cells in a number of aspects. In contrast to the development of conventional B cell memory, which requires the formation of germinal centers and T cells, the development of B1b cell-mediated long-lasting antibody responses occurs independent of T cell help. T cell-independent (TI) antigens are important virulence factors expressed by a number of bacterial pathogens, including those associated with biological threats. TI antigens cannot be processed and presented to T cells and therefore are known to possess restricted T cell-dependent (TD) immunogenicity. Nevertheless, specific recognition of TI antigens by B1b cells and the highly protective antibody responses mounted by them clearly indicate a crucial role for this subset of B cells. Understanding the mechanisms of long-term immunity conferred by B1b cells may lead to improved vaccine efficacy for a variety of TI antigens.


Subject(s)
Antigens, Bacterial/immunology , Antigens, T-Independent/immunology , B-Lymphocyte Subsets/immunology , Bacterial Infections/immunology , Toll-Like Receptors/immunology , Animals , Antigens, T-Independent/metabolism , B-Lymphocyte Subsets/physiology , Bacterial Infections/microbiology , CD40 Antigens/immunology , CD40 Ligand/immunology , Humans , Immunologic Memory , Lymphocyte Activation , Toll-Like Receptors/metabolism
12.
Immunol Lett ; 113(2): 70-5, 2007 Nov 15.
Article in English | MEDLINE | ID: mdl-17850884

ABSTRACT

Humoral responses against thymus-dependent (TD) antigens are characterized by Ig class switch, somatic hypermutations (SHM) and generation of memory. These processes are thought to occur in the specialized environment of the germinal center (GC). Some thymus-independent (TI) antigens, such as native dextran B512 (Dx) can also induce formation of GCs, but the responses do not undergo substantial affinity maturation or induction of memory. Immunization with TI Dx affects later TD responses against the same epitope, reducing Dx specific IgG1. We have studied if the different outcome of the TI- and TD-induced GC reaction is due to differences in plasma cell differentiation. The transcriptional repressor B lymphocyte-induced maturation protein, Blimp-1, was used as a marker for differentiation of plasma cells. We show that TI GCs contain Blimp-1 in early and mature GCs, in contrast to TD-induced GCs which strongly express Blimp-1 only in established GCs. Furthermore, the intensity of the Blimp-1 staining is stronger in TI GCs. In addition, we demonstrate that in TD responses after TI priming the pattern of Blimp-1 expression is a mixture of both TI and TD responses. This is novel evidence since these TD humoral responses against Dx display a TI isotype pattern.


Subject(s)
Antigens, T-Independent/immunology , B-Lymphocytes/immunology , Germinal Center/immunology , Immunization , Repressor Proteins/metabolism , Transcription Factors/metabolism , Animals , Antibody Formation , Antigens, T-Independent/metabolism , B-Lymphocytes/metabolism , Female , Germinal Center/metabolism , Mice , Mice, Inbred C57BL , Mice, Nude , Plasma Cells/immunology , Plasma Cells/metabolism , Positive Regulatory Domain I-Binding Factor 1 , Repressor Proteins/isolation & purification , Thymus Gland/immunology , Thymus Gland/metabolism , Transcription Factors/isolation & purification
13.
J Immunol ; 174(9): 5516-25, 2005 May 01.
Article in English | MEDLINE | ID: mdl-15843550

ABSTRACT

The IGF-1 receptor (IGF-1R) is expressed on T and B lymphocytes, and the expression of the insulin- and IGF-1-signaling machinery undergoes defined changes throughout lineage differentiation, offering a putative role for IGF-1 in the regulation of immune responses. To study the role of the IGF-1R in lymphocyte differentiation and function in vivo, we have reconstituted immunodeficient RAG2-deficient mice with IGF-1R(-/-) fetal liver cells. Despite the absence of IGF-1Rs, the development and ex vivo activation of B and T lymphocytes were unaltered in these chimeric mice. By contrast, the humoral immune response to the T cell-independent type 2 Ag 4-hydroxy-3-nitrophenyl acetyl-Ficoll was significantly reduced in mice reconstituted with IGF-1R-deficient fetal liver cells, whereas responses to the T cell-dependent Ag 4-hydroxy-3-nitrophenyl acetyl-chicken globulin were normal. Moreover, in an in vitro model of T cell-independent type 2 responses, IGF-1 promoted Ig production potently upon polyvalent membrane-IgD cross-linking. These data indicate that functional IGF-1R signaling is required for T cell-independent B cell responses in vivo, defining a novel regulatory mechanism for the immune response against bacterial polysaccharides.


Subject(s)
Antigens, T-Independent/immunology , Antigens, T-Independent/metabolism , B-Lymphocyte Subsets/immunology , B-Lymphocyte Subsets/metabolism , Insulin-Like Growth Factor I/physiology , Receptor, IGF Type 1/physiology , Animals , B-Lymphocyte Subsets/cytology , B-Lymphocyte Subsets/enzymology , Cell Differentiation/genetics , Cell Differentiation/immunology , Down-Regulation/genetics , Down-Regulation/immunology , Fetal Tissue Transplantation/immunology , Ficoll/administration & dosage , Ficoll/immunology , Immunoglobulins/biosynthesis , Insulin-Like Growth Factor I/metabolism , Liver Transplantation/immunology , Lymphocyte Activation/genetics , Lymphopoiesis/genetics , Lymphopoiesis/immunology , Mice , Mice, Inbred C57BL , Mice, Knockout , Nitrophenols/administration & dosage , Nitrophenols/immunology , Phenylacetates , Phosphorylation , Phosphotyrosine/metabolism , Radiation Chimera/immunology , Receptor, IGF Type 1/deficiency , Receptor, IGF Type 1/genetics , Signal Transduction/genetics , Signal Transduction/immunology , T-Lymphocytes/cytology , T-Lymphocytes/immunology , T-Lymphocytes/metabolism , Up-Regulation/genetics , Up-Regulation/immunology
14.
Hum Pathol ; 35(1): 113-21, 2004 Jan.
Article in English | MEDLINE | ID: mdl-14745733

ABSTRACT

Infants are more susceptible to infections caused by T cell- independent type 2 (TI-2) polysaccharide antigens of certain encapsulated bacteria. Immune responses against this type of antigen are related to the splenic marginal zone (MZ). However, only few data exist on the age-dependent developmental stages of the human spleen in early childhood and on their association with different diseases. Therefore, the present study aimed to investigate spleens of a large number of children at very young ages (12 days to 32 months), derived from autopsy cases. Immunohistochemical labeling was performed on paraffin sections of 34 spleens using a panel of monoclonal antibodies. The shape and size of the white pulp compartments were examined and correlated to the cause of death of the children. Results show that the development of the different compartments was statistically age-dependent, but no clear-cut time point for the maturity of each compartment was seen. Furthermore, the MZ was significantly more often missing when sudden infant death (SID) and/or infection were the cause of death, compared with other violent or traumatic reasons that served as controls. This association supports the concept that an immature state of the spleen and especially of the MZ might contribute to the increased susceptibility to bacterial infections in young infants.


Subject(s)
Aging/immunology , Cause of Death , Immunity, Cellular , Spleen/immunology , Sudden Infant Death/immunology , Antigens, CD/metabolism , Antigens, T-Independent/metabolism , Biomarkers/analysis , Child, Preschool , Female , Humans , Immunoenzyme Techniques , Infant , Infant, Newborn , Male , Spleen/growth & development , Spleen/pathology , Sudden Infant Death/pathology
15.
Curr Biol ; 13(21): 1858-66, 2003 Oct 28.
Article in English | MEDLINE | ID: mdl-14588241

ABSTRACT

BACKGROUND: Bam32/DAPP1 is a B cell adaptor composed of both a PH and an SH2 domain. Previous studies in cell culture and chicken DT40 cells have indicated that Bam32 is critical for normal signaling downstream of the B cell receptor (BCR). RESULTS: We now study the function of Bam32 in mice in which Bam32 has been disrupted by a viral gene trap approach. Although B and T cell development is normal in Bam32(-/-) mice, B cell proliferation is reduced by about 50% after BCR crosslinking when compared with Bam32(+/+) mice. Differences in the activation of Erk, Jnk and p38 Map kinases, PLCgamma, and Ca(2+) flux do not account for the defect in proliferation as activation was similar in Bam32(+/+) and Bam32(-/-) B cells. Interestingly, whereas antibody response to T-dependent (TD) and T-independent (TI)-I antigens was similar between Bam32(+/+) and Bam32(-/-) mice, TI-II responses were defective in Bam32(-/-) mice; Bam32(-/-) mice failed to undergo isotype class switch recombination (CSR) to produce IgG3 antibodies due to a cell-autonomous defect in generation of IgG3 germline transcripts. The defect in TI-II antigen response led to an impaired antibody response to immunization with type 3 Streptococcus pneumoniae capsular polyschaccharide (PS), resulting in a markedly increased susceptibility to infection by Streptococcus pneumoniae. CONCLUSIONS: These findings indicate that Bam32 specifically couples an upstream signal to the IgG3 isotype heavy chain CSR and suggest that defects in Bam32 may account for the increased susceptibility to encapusulated organisms in a subset of immunodeficient patients.


Subject(s)
Adaptor Proteins, Signal Transducing , Antigens, T-Independent/metabolism , B-Lymphocytes/immunology , Carrier Proteins/metabolism , Lipoproteins/metabolism , Membrane Proteins/metabolism , Signal Transduction , src Homology Domains/physiology , Animals , Antibody Formation , Antigens, T-Independent/immunology , B-Lymphocytes/physiology , Carrier Proteins/immunology , Electrophoresis, Polyacrylamide Gel , Enzyme-Linked Immunosorbent Assay , Immunoglobulin G/immunology , Immunoglobulin G/metabolism , Lipoproteins/immunology , Membrane Proteins/immunology , Mice , Mice, Mutant Strains , Molecular Probe Techniques , Precipitin Tests , Receptors, Antigen, B-Cell/immunology , Receptors, Antigen, B-Cell/metabolism , Reverse Transcriptase Polymerase Chain Reaction
16.
Mol Cell Biol ; 22(24): 8580-91, 2002 Dec.
Article in English | MEDLINE | ID: mdl-12446777

ABSTRACT

Many receptor and nonreceptor tyrosine kinases activate phosphoinositide 3-kinases (PI3Ks). To assess the role of the delta isoform of the p110 catalytic subunit of PI3Ks, we derived enzyme-deficient mice. The mice are viable but have decreased numbers of mature B cells, a block in pro-B-cell differentiation, and a B1 B-cell deficiency. Both immunoglobulin M receptor-induced Ca(2+) flux and proliferation in response to B-cell mitogens are attenuated. Immunoglobulin levels are decreased substantially. The ability to respond to T-cell-independent antigens is markedly reduced, and the ability to respond to T-cell-dependent antigens is completely eliminated. Germinal center formation in the spleen in response to antigen stimulation is disrupted. These results define a nonredundant signaling pathway(s) utilizing the delta isoform of p110 PI3K for the development and function of B cells.


Subject(s)
B-Lymphocytes/physiology , Phosphatidylinositol 3-Kinases/metabolism , Receptors, Antigen, B-Cell/metabolism , Signal Transduction/physiology , Animals , Antigens, T-Independent/metabolism , Calcium/metabolism , Cells, Cultured , Class I Phosphatidylinositol 3-Kinases , Flow Cytometry , Gene Targeting , Germinal Center/cytology , Germinal Center/metabolism , Hematopoietic Stem Cells/cytology , Hematopoietic Stem Cells/metabolism , Humans , Immunoglobulins/blood , Macromolecular Substances , Mice , Mice, Knockout , Phosphatidylinositol 3-Kinases/genetics , Stem Cells/cytology , Stem Cells/physiology , T-Lymphocytes/physiology
17.
Eur J Immunol ; 32(2): 561-7, 2002 02.
Article in English | MEDLINE | ID: mdl-11828373

ABSTRACT

CD22 is a B cell-specific member of the immunoglobulin superfamily and binds to sialic acid. CD22 inhibits B cell receptor signaling. Mice deficient for CD22 show a largely normal B cell development. Here, we have performed a detailed analysis of the splenic B cell population and found that the subset of marginal zone (MZ) B cells was selectively reduced in CD22-deficient mice. CD22-deficient mice showed a lack of TNP-ficoll capturing cells in the MZ and a reduced response to TNP-ficoll, particularly when the antigen was applied intravenously. CD22-deficient B cells showed both enhanced motility as well as enhanced chemotaxis to certain chemokines. The altered chemokine responsiveness or the higher signaling capacity of CD22-deficient B cells may lead to the compromised MZ B cell compartment, as both processes have previously been shown to affect MZ composition.


Subject(s)
Antigens, CD/metabolism , Antigens, Differentiation, B-Lymphocyte/metabolism , B-Lymphocyte Subsets/immunology , Cell Adhesion Molecules , Ficoll/analogs & derivatives , Lectins , Animals , Antigens, CD/genetics , Antigens, Differentiation, B-Lymphocyte/genetics , Antigens, T-Independent/metabolism , B-Lymphocyte Subsets/cytology , Cell Movement/immunology , Lymphocyte Count , Mice , Mice, Inbred C57BL , Mice, Knockout , Sialic Acid Binding Ig-like Lectin 2 , Signal Transduction , Spleen/cytology , Spleen/immunology , Trinitrobenzenes
18.
Dev Immunol ; 9(3): 169-72, 2002 Sep.
Article in English | MEDLINE | ID: mdl-12885157

ABSTRACT

Adaptive immunity is dependent on proliferation of antigen-driven B cells for clonal expansion in germinal centers (GCs) against T cell-dependent antigens (TD-Ag), accompanied with somatic hypermutation of variable-region gene and class switching of B cell antigen receptors. To study molecular mechanisms for B cell differentiation in GCs, we have identified and studied a 210kDa GANP protein expressed in GC-B cells. GANP has domains for MCM3-binding and RNA-primase activities and is selectively up-regulated in centrocytes surrounded with follicular dendritic cells (FDCs) upon immunization with TD-Ag in vivo and in B cells stimulated with anti-CD40 monoclonal antibody in vitro, which suggested that GANP plays a certain important role in the maturation of immunoglobulin or selection of B cells in GC during the immune response to TD-Ag. Since this up-regulation has not been detected in T cells in GCs and in Concanavalin A-stimulated T cells in vitro, selective function of GANP molecule on B cell proliferation and differentiation might exist.


Subject(s)
Acetyltransferases/metabolism , Antigens, Differentiation/immunology , B-Lymphocytes/immunology , Lymphocyte Activation/immunology , Phosphoproteins/metabolism , T-Lymphocytes/immunology , Acetyltransferases/chemistry , Acetyltransferases/genetics , Animals , Antigens, T-Independent/metabolism , DNA Primase/metabolism , Female , Germinal Center/metabolism , Humans , Intracellular Signaling Peptides and Proteins , Male , Mice , Mice, Inbred C57BL , Phosphoproteins/chemistry , Phosphoproteins/genetics , RNA, Messenger/metabolism , Up-Regulation
19.
Mol Pathol ; 54(5): 324-30, 2001 Oct.
Article in English | MEDLINE | ID: mdl-11577175

ABSTRACT

AIMS: Differential display reverse transcription polymerase chain reaction (RT-PCR) was performed to identify genes associated with the invasive potential of human epithelioid sarcoma. METHODS: Two different clonal subpopulations, GRU-1A and GRU-1B, derived from the same human epithelioid sarcoma cell line GRU-1 and known to differ greatly in their invasive potential were compared by means of mRNA fingerprinting. RESULTS: Using a set of 10 arbitrary upstream primers and nine anchored oligo-dT primers, 22 candidate gene fragments were identified; differential expression was confirmed in four of these fragments by northern blot analysis. At the mRNA level, apoferritin light chain was predominantly expressed by the highly invasive cell line GRU-1A. In contrast, the mitochondrial gene M1, encoding cytochrome c oxidase I, and the TI-227H gene were expressed more strongly by the low invasive cell line GRU-1B. Furthermore, a novel gene fragment was identified and cloned that was preferentially expressed in the low invasive cell line GRU-1B, and therefore might have an inhibitory role in invasion. Consequently, this gene fragment was designated as expressed in low invasive sarcoma cells (ELISC-1). CONCLUSIONS: A novel gene fragment (ELISC-1) and three known genes were identified as potential regulators of tumour invasiveness. Cloning of the entire sequence of ELISC-1 and subsequent investigations are required to establish its biological role.


Subject(s)
Neoplasm Invasiveness/genetics , Sarcoma/genetics , Antigens, T-Independent/metabolism , Apoferritins/metabolism , Blotting, Northern , DNA Fingerprinting , Electron Transport Complex IV/metabolism , Gene Expression , Humans , RNA, Messenger/analysis , Reverse Transcriptase Polymerase Chain Reaction , Tumor Cells, Cultured
20.
Immunol Rev ; 176: 154-70, 2000 Aug.
Article in English | MEDLINE | ID: mdl-11043775

ABSTRACT

Antigens that are expressed on the surface of pathogens in an organized, highly repetitive form can activate specific B cells by cross-linking of antigen receptors in a multivalent fashion. B cells respond to these multivalent antigens in the absence of MHC class II-restricted T-cell help by a mechanism that depends on the expression of a functional Bruton's tyrosine kinase (Btk). Accordingly, this class of immunogens has been designated T-cell-independent type 2 (TI-2) antigens. The unique properties of the B-cell response to TI-2 antigens are critically dependent on the formation of a small number of antigen receptor clusters, each of which contains approximately 10 to 20 antigen-bound membrane Ig (mIg) molecules. These clusters induce local membrane association of multiple activated Btk molecules, which results in long-term mobilization of intracellular ionized calcium. Such persistent calcium fluxes efficiently recruit transcription factors and thereby induce T-cell-independent B-cell activation and proliferation. While this first signal of multivalent mIg cross-linking can induce B-cell proliferation, we propose that a second signal is required for a TI-2 Ig secretory response. We have found that engagement of members of the Toll-like receptor (TLR) family could provide second signals that selectively induce Ig secretion in B cells that were activated by multivalent, but not by bivalent, antigen receptor engagement. This finding demonstrates a general mechanism by which TLRs recognize molecular motifs on the surface of pathogens and provide the TI-2-activated B cell with a second signal. In addition, TLR-dependent recognition of these non-self motifs by cells of the innate immune system can induce these cells to provide alternative and/or additional second signals in the TI-2 response. The complement system provides another link between the B cell and the innate immune system, and facilitates the mIg signal transduction by recruitment of CD21 in the immune response. Thus, the TI-2 response provides the host with a combination of "the best of both worlds": the recruitment of the fine specificity of the adaptive immune response and the utilization of both the speed of the innate immune system and the wealth of cytokines produced by its member cells upon stimulation by pathogenic organisms or their products. By combining these two pathways, the TI-2 response enables the host to rapidly produce antigen-specific Ig effector molecules that can be secreted at a sufficient rate to keep up with the rapid multiplication of invading infectious microorganisms, and will also prevent the intracellular spreading of a significant part of this population.


Subject(s)
Antigens, T-Independent/metabolism , B-Lymphocytes/immunology , Bacteria/immunology , Animals , Antibodies, Bacterial/biosynthesis , Bacteria/pathogenicity , Complement System Proteins/metabolism , Humans , Killer Cells, Natural/immunology , Lymphocyte Activation , Receptors, Antigen, B-Cell/metabolism , Receptors, Antigen, T-Cell, alpha-beta/metabolism , Signal Transduction , T-Lymphocyte Subsets/immunology
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