ABSTRACT
The "X chromosome-nucleolus nexus" hypothesis provides a comprehensive explanation of how autoantibodies can develop following cellular stress. The hypothesis connects autoimmune diseases with the impact of environmental factors, such as viruses, through epigenetic disruption. The inactive X chromosome, a major epigenetic structure in the female cell's nucleus, is a key component of the hypothesis. The inactive X is vulnerable to disruption due to the following: (1) its heavy requirements for methylation to suppress gene expression, (2) its peripheral location at the nuclear envelope, (3) its late replication timing, and (4) its frequently observed close association with the nucleolus. The dynamic nucleolus can expand dramatically in response to cellular stress and this could disrupt the neighboring inactive X, particularly during replication, leading to expression from previously suppressed chromatin. Especially vulnerable at the surface of the inactive X chromosome would be genes and elements from Xp22 to the terminus of the short arm of the X. Expression of these genes and elements could interfere with nucleolar integrity, nucleolar efficiency, and future nucleolar stress response, and even lead to fragmentation of the nucleolus. Ribonucleoprotein complexes assembled in the nucleolus could be left in incomplete states and inappropriate conformations, and/or contain viral components when the nucleolus is disrupted and these abnormal complexes could initiate an autoimmune response when exposed to the immune system. Epitope spreading could then lead to an autoimmune reaction to the more abundant normal complexes. Many autoantigens reported in lupus and other autoimmune diseases are, at least transiently, nucleolar components.
Subject(s)
Autoimmune Diseases/immunology , Autoimmunity/immunology , Cell Nucleolus/immunology , X Chromosome/immunology , Animals , Autoantigens/immunology , HumansABSTRACT
Systemic lupus erythematosus (SLE) is an autoimmune disease with a high incidence in females and a complex phenotype. Using 564Igi mice, a model of SLE with knock-in genes encoding an autoreactive anti-RNA Ab, we investigated how expression of Toll-like receptors (TLRs) in B cells and neutrophils affects pathogenesis. We established that TLR signaling through MyD88 is necessary for disease. Autoantibody was produced in mice with single deletions of Tlr7, Tlr8, or Tlr9 or combined deletions of Tlr7 and Tlr9. Autoantibody was not produced in the combined absence of Tlr7 and Tlr8, indicating that TLR8 contributes to the break in tolerance. Furthermore, TLR8 was sufficient for the loss of B-cell tolerance, the production of class-switched autoantibody, heightened granulopoiesis, and increased production of type I IFN by neutrophils as well as glomerulonephritis and death. We show that dosage of X-linked Tlr8 plays a major role in the high incidence of disease in females. In addition, we show that the negative regulation of disease by TLR9 is exerted primarily on granulopoiesis and type I IFN production by neutrophils. Collectively, we suggest that individual TLRs play unique roles in the pathogenesis of systemic lupus erythematosus, suggesting new targets for treatment.
Subject(s)
Gene Dosage/immunology , Lupus Erythematosus, Systemic/immunology , Sex Characteristics , Toll-Like Receptor 8/immunology , X Chromosome/immunology , Animals , Autoantibodies/immunology , B-Lymphocytes/immunology , B-Lymphocytes/pathology , Female , Gene Dosage/genetics , Interferon Type I/genetics , Interferon Type I/immunology , Lupus Erythematosus, Systemic/genetics , Lupus Erythematosus, Systemic/pathology , Male , Membrane Glycoproteins/genetics , Membrane Glycoproteins/immunology , Mice , Mice, Inbred BALB C , Mice, Knockout , Myelopoiesis/genetics , Myelopoiesis/immunology , Toll-Like Receptor 7/genetics , Toll-Like Receptor 7/immunology , Toll-Like Receptor 8/genetics , Toll-Like Receptor 9/genetics , Toll-Like Receptor 9/immunology , X Chromosome/geneticsABSTRACT
Ploidy-level variation is common and can drastically affect organismal fitness. We focus on the potential consequences of this variation for parasite resistance. First, we elucidate connections between ploidy variation and key factors determining resistance, including allelic diversity, gene expression and physiological condition. We then argue that systems featuring both natural and artificially manipulated ploidy variation should be used to evaluate whether ploidy level influences host-parasite interactions.
Subject(s)
Alleles , Host-Parasite Interactions , Parasites/immunology , Polyploidy , Animals , Evolution, Molecular , Fishes/genetics , Fishes/immunology , Fishes/parasitology , Genetic Variation , Heterozygote , Ostreidae/genetics , Ostreidae/immunology , Ostreidae/parasitology , Parasites/genetics , X Chromosome/genetics , X Chromosome/immunologyABSTRACT
In this paper, we hypothesize that X chromosome-associated mechanisms, which affect X-linked genes and are behind the immunological advantage of females, may also affect X-linked microRNAs. The human X chromosome contains 10% of all microRNAs detected so far in the human genome. Although the role of most of them has not yet been described, several X chromosome-located microRNAs have important functions in immunity and cancer. We therefore provide a detailed map of all described microRNAs located on human and mouse X chromosomes, and highlight the ones involved in immune functions and oncogenesis. The unique mode of inheritance of the X chromosome is ultimately the cause of the immune disadvantage of males and the enhanced survival of females following immunological challenges. How these aspects influence X-linked microRNAs will be a challenge for researchers in the coming years, not only from an evolutionary point of view, but also from the perspective of disease etiology.
Subject(s)
Gene Expression Regulation, Neoplastic , Genes, X-Linked , Immunity/genetics , MicroRNAs/immunology , X Chromosome/immunology , Animals , Cell Differentiation , Female , Genome, Human , Humans , Male , Mice , MicroRNAs/genetics , Mutation , Neoplasms/genetics , Neoplasms/immunology , Neoplasms/pathology , Sex Factors , Signal Transduction , X Chromosome/geneticsSubject(s)
Gene Expression Regulation, Neoplastic , Genes, X-Linked , Immunity/genetics , MicroRNAs/immunology , X Chromosome/immunology , Animals , Female , Humans , MaleABSTRACT
This study was designed to identify sex-specific antibodies (SSAb) in rabbit antisera against bovine sex-sorted sperm, and capture sex-specific proteins of bovine X- or Y- proteins by SSAb. The rabbit antisera against bovine X- or Y-sperm were first produced by a series of immunological approaches, and further purified through immuno-neutralization with excess sex-sorted Y- or X-sperm, respectively, to remove non-sex specific antibodies and enrich sex-specific antibodies. After removal of non-sex specific antibodies, the purified rabbit sera with enriched sex-specific antibodies were screened for sex-specific antibodies by immunofluorescence staining and flow cytometry. The results showed that 3.0, 2.2, and 4.2% of unsorted sperm, sex-sorted X-sperm, and sex-sorted Y-sperm were recognized by the purified rabbit antisera against Y-sperm, respectively, whereas 29.2, 19.7, and 3.9% of unsorted sperm, sex-sorted X-sperm, and sex-sorted Y-sperm were recognized by the purified rabbit antisera against X-sperm. These results suggested that the purified rabbit antisera against X-sperm contained SSAb that preferentially bound to sex-sorted X-sperm. Subsequently, the purified rabbit antisera against X- or Y-sperm were used to immunoprecipitate sex-specific proteins in bovine sperm proteins, and a 30-kDa protein was specifically captured by the rabbit antisera against X-sperm. In conclusion, our results implied that this 30-kDa protein might be a sex-specific protein in bovine X-sperm, which has the potential to be used in immunological procedures for sexing sperm.
Subject(s)
Membrane Proteins/immunology , Sex Preselection/veterinary , Spermatozoa/immunology , X Chromosome/immunology , Y Chromosome/immunology , Animals , Antibodies/analysis , Cattle , Immune Sera , Male , Membrane Proteins/isolation & purification , Rabbits , Sex Preselection/methodsABSTRACT
The X-chromosomal GPR34 gene encodes an orphan G(i) protein-coupled receptor that is highly conserved among vertebrates. To evaluate the physiological relevance of GPR34, we generated a GPR34-deficient mouse line. GPR34-deficient mice were vital, reproduced normally, and showed no gross abnormalities in anatomical, histological, laboratory chemistry, or behavioral investigations under standard housing. Because GPR34 is highly expressed in mononuclear cells of the immune system, mice were specifically tested for altered functions of these cell types. Following immunization with methylated BSA, the number of granulocytes and macrophages in spleens was significantly lower in GPR34-deficient mice as in wild-type mice. GPR34-deficient mice showed significantly increased paw swelling in the delayed type hypersensitivity test and higher pathogen burden in extrapulmonary tissues after pulmonary infection with Cryptococcus neoformans compared with wild-type mice. The findings in delayed type hypersensitivity and infection tests were accompanied by significantly different basal and stimulated TNF-α, GM-CSF, and IFN-γ levels in GPR34-deficient animals. Our data point toward a functional role of GPR34 in the cellular response to immunological challenges.
Subject(s)
Cryptococcosis/immunology , Cryptococcus neoformans/immunology , Granulocytes/immunology , Hypersensitivity, Delayed/immunology , Macrophages/metabolism , Pneumonia/immunology , Receptors, Lysophospholipid/immunology , Animals , Cattle , Cryptococcosis/metabolism , Cytokines/biosynthesis , Cytokines/genetics , Cytokines/immunology , Granulocytes/metabolism , Hypersensitivity, Delayed/genetics , Hypersensitivity, Delayed/metabolism , Immunization , Macrophages/immunology , Mice , Mice, Knockout , Pneumonia/metabolism , Receptors, Lysophospholipid/genetics , Receptors, Lysophospholipid/metabolism , Serum Albumin, Bovine/immunology , Serum Albumin, Bovine/pharmacology , X Chromosome/genetics , X Chromosome/immunology , X Chromosome/metabolismABSTRACT
Scurfy (Foxp3(Sf)/Y), Il2(-/-), and Il2ralpha(-/-) mice are deficient in CD4(+)Foxp3(+) regulatory T cells (Treg), but only the latter two develop inflammation in the submandibular gland (SMG), a critical target of Sjögren's syndrome. In this study, we investigated the reason that SMG of Scurfy (Sf), Sf.Il2(-/-), Sf.Il2ralpha(-/-), and the long-lived Sf.Fas(lpr/lpr) mice remained free of inflammation, even though their lymph node cells induced SMG inflammation in Rag1(-/-) recipients. A strong correlation was observed between the development of the granular convoluted tubules (GCT) of the SMG in these mice and SMG resistance to inflammation. Moreover, GCT development in Sf.Rag1(-/-) mice was not impeded, indicating a role of adaptive immunity. In the Sf.Fas(lpr/lpr) mice, this block was linked to atrophy and inflammation in the accessory reproductive organs. Testosterone treatment restored GCT expression, but did not induce SMG inflammation, indicating GCT is not required for inflammation and additional mechanisms were controlling SMG inflammation. Conversely, oral application of LPS induced SMG inflammation, but not GCT expression. LPS treatment induced up-regulation of several chemokines in SMG with little effect on the chemokine receptors on CD4(+) T cells in Sf mice. Our study demonstrates that Sf mutation affects SMG development through adaptive immunity against accessory reproductive organs, and the manifestation of SMG inflammation in Sf mice is critically controlled through innate immunity.
Subject(s)
Forkhead Transcription Factors/genetics , Genes, Dominant/immunology , Immunity, Innate/genetics , Inflammation Mediators/antagonists & inhibitors , Mutation , Submandibular Gland/growth & development , Submandibular Gland/pathology , X Chromosome/genetics , Animals , Female , Forkhead Transcription Factors/physiology , Genetic Predisposition to Disease , Genitalia, Male/growth & development , Genitalia, Male/immunology , Genitalia, Male/pathology , Inflammation Mediators/physiology , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Mice, Transgenic , Organ Specificity/genetics , Organ Specificity/immunology , Submandibular Gland/immunology , X Chromosome/immunologyABSTRACT
Despite accumulating evidence in support of sex-based differences in innate and adaptive immune responses, in the susceptibility to infectious diseases and in the prevalence of autoimmune diseases, health research and clinical practice do not address these distinctions, and most research studies of immune responses do not stratify by sex. X-linked genes, hormones and societal context are among the many factors that contribute to disparate immune responses in males and females. It is crucial to address sex-based differences in disease pathogenesis and in the pharmacokinetics and pharmacodynamics of therapeutic medications to provide optimal disease management for both sexes.
Subject(s)
Genetic Predisposition to Disease/genetics , Immunity/immunology , Sex Characteristics , X Chromosome/genetics , X Chromosome/immunology , Animals , Disease , Hormones/immunology , HumansABSTRACT
Organ allografts have been shown to provide a syngeneic microenvironment for organ-based donor hematopoietic stem cells to maintain long-lasting chimerism after transplantation. We hypothesized that organ allografts would also support engraftment and hematopoiesis of adjunctively infused donor marrow stem cells, syngeneic to organ grafts, in nonmyeloablated recipients. In BN-to-LEW and GFP-to-ACI rat combinations, donor bone marrow (BM) infusion together with small intestine transplantation (SITx) under short-course tacrolimus immunosuppression resulted in persistent macrochimerism (more than 5%) for 150 days. In contrast, after BM infusion or SITx alone, chimerism was temporary and disappeared by day 100. Y-chromosome polymerase chain reaction (PCR) in sex-mismatched male BM plus female intestine or female BM plus male intestine transplantation into female recipients suggested that persistent macrochimerism was derived from infused BM. BM infusion together with lymphoid-depleted intestine grafts also supported macrochimerism development; however, third-party intestine grafts did not. After GFP-positive BM plus wild-type (WT) SITx into ACI, large numbers of GFP-positive leukocytes were found in WT intestine grafts. Isolated cells from WT intestine grafts developed GFP-positive CFU-Cs and propagated multilineage GFP-positive leukocytes when adoptively transferred into lethally irradiated WT recipients. These findings suggest that intestine allograft supports simultaneously infused donor (syngeneic to organ grafts) marrow stem cell engraftment, differentiation, and persistence of chimerism.
Subject(s)
Bone Marrow Transplantation , Graft Survival , Intestine, Small/transplantation , Transplantation, Isogeneic , Animals , Animals, Genetically Modified , Cell Differentiation/immunology , Female , Graft Survival/drug effects , Graft Survival/immunology , Immunosuppression Therapy , Immunosuppressive Agents/pharmacology , Intestine, Small/immunology , Leukocytes/immunology , Lymphocyte Depletion , Male , Rats , Rats, Sprague-Dawley , Tacrolimus/pharmacology , Time Factors , Transplantation Chimera/immunology , X Chromosome/immunology , Y Chromosome/immunologyABSTRACT
The inactive X chromosome (Xi) forms a heterochromatic structure in the nucleus that is known to have several modifications to specific histones involving acetylation or methylation. Using three different antibodies in four different cell lines, we demonstrate that the Xi in human and mouse cells is highly enriched in ubiquitinated protein(s), much of which is polyubiquitinated. This ubiquitination appears specific for the Xi as it was not observed for centromeres or other regions of heterochromatin. Results using an antibody specific to ubiquitinated H2A provide a clear link between H2A ubiquitination and gene repression, as visualized across an entire inactive chromosome. Interestingly, the ubiquitination of the chromosome persists into mitosis and can be seen in a reproducible banded pattern. This pattern matches that of Xist RNA which forms bands as it detaches from the mitotic X chromosome. Both ubiquitination and Xist RNA appear enriched in gene dense regions and depleted in gene poor bands, but do not correlate with L1 LINE elements which have been suggested as key to X-inactivation. These results provide evidence that ubiquitination along with Xist RNA plays an important role in the formation of facultative heterochromatin during X-inactivation.
Subject(s)
Chromosomes, Human, X/metabolism , Dosage Compensation, Genetic , Histones/metabolism , RNA, Untranslated/metabolism , Ubiquitins/metabolism , X Chromosome/metabolism , Animals , Antibodies, Monoclonal/immunology , Cell Line , Chromosomes, Human, X/immunology , Down-Regulation , Gene Expression , Histones/analysis , Histones/immunology , Humans , Mice , Mitosis/physiology , RNA, Long Noncoding , RNA, Untranslated/analysis , Sex Chromatin/chemistry , Sex Chromatin/immunology , Sex Chromatin/metabolism , Ubiquitins/analysis , Ubiquitins/immunology , X Chromosome/chemistry , X Chromosome/immunologyABSTRACT
The Tec kinase Bruton's tyrosine kinase (Btk) represents a key intermediary for B cell receptor (BCR) signaling. Btk mutation produces B cell deficiency in mice with X-linked immunodeficiency (xid), and surface Ig-mediated responses of mature B cells are seriously deranged. The central role that Btk plays in directing downstream events produced by BCR engagement is demonstrated by the complete failure of NF-kappa B induction and cellular proliferation following anti-Ig treatment of B cells obtained from xid mice. In this study, we report that the block in BCR signaling produced by Btk mutation is reversed by CD40 engagement. Prior treatment with CD40 ligand normalized subsequent responses of xid B cells to BCR cross-linking, so that typical outcomes of BCR signaling such as NF-kappa B activation and cell cycle progression occurred in a Btk-independent fashion. These results demonstrate that a specific genetic lesion interrupting BCR-mediated intracellular signaling is circumvented through stimulation of CD40.
Subject(s)
B-Lymphocytes/enzymology , CD40 Antigens/immunology , CD40 Antigens/metabolism , CD40 Ligand/physiology , NF-kappa B/metabolism , Protein-Tyrosine Kinases/physiology , Receptors, Antigen, B-Cell/physiology , Signal Transduction/immunology , Agammaglobulinaemia Tyrosine Kinase , Animals , Antibodies, Anti-Idiotypic/pharmacology , B-Lymphocytes/immunology , B-Lymphocytes/metabolism , B-Lymphocytes/pathology , CD40 Antigens/physiology , Cell Cycle/genetics , Cell Cycle/immunology , Cells, Cultured , Down-Regulation/genetics , Down-Regulation/immunology , Genetic Linkage/immunology , I-kappa B Proteins/antagonists & inhibitors , I-kappa B Proteins/metabolism , Immunoglobulin M/immunology , Lymphocyte Activation/genetics , Lymphopenia/genetics , Lymphopenia/immunology , Lymphopenia/pathology , Mice , Mice, Inbred CBA , Mice, Mutant Strains , NF-KappaB Inhibitor alpha , NF-kappa B/biosynthesis , Receptors, Antigen, B-Cell/metabolism , Signal Transduction/genetics , X Chromosome/genetics , X Chromosome/immunologyABSTRACT
X-linked autoimmunity-allergic disregulation syndrome (XLAAD) is an X-linked recessive immunological disorder characterized by multisystem autoimmunity, particularly early-onset type 1 diabetes mellitus, associated with manifestations of severe atopy including eczema, food allergy, and eosinophilic inflammation. Consistent with the allergic phenotype, analysis of two kindreds with XLAAD revealed marked skewing of patient T lymphocytes toward the Th2 phenotype. Using a positional-candidate approach, we have identified in both kindreds mutations in JM2, a gene on Xp11.23 that encodes a fork head domain-containing protein. One point mutation at a splice junction site results in transcripts that encode a truncated protein lacking the fork head homology domain. The other mutation involves an in-frame, 3-bp deletion that is predicted to impair the function of a leucine zipper dimerization domain. Our results point to a critical role for JM2 in self tolerance and Th cell differentiation.
Subject(s)
Autoimmune Diseases/genetics , Diabetes Mellitus, Type 1/genetics , Food Hypersensitivity/genetics , Genetic Linkage/genetics , Nuclear Proteins/genetics , Transcription Factors/genetics , X Chromosome/genetics , Amino Acid Sequence , Autoimmune Diseases/immunology , Base Sequence , Cell Differentiation , DNA Mutational Analysis , Diabetes Mellitus, Type 1/immunology , Female , Food Hypersensitivity/immunology , Forkhead Transcription Factors , Haplotypes , Humans , Leucine Zippers , Male , Molecular Sequence Data , Mutation/genetics , Nuclear Proteins/chemistry , Nuclear Proteins/immunology , Pedigree , Protein Structure, Tertiary , RNA Splice Sites/genetics , Sequence Alignment , Sequence Homology, Amino Acid , Syndrome , Th2 Cells/cytology , Th2 Cells/immunology , Transcription Factors/chemistry , Transcription Factors/immunology , X Chromosome/immunologyABSTRACT
X-linked lymphoproliferative disease (XLP) is characterized by a selective immune deficiency to EBV. The molecular basis of XLP has been attributed to mutations of signaling lymphocytic activation molecule-associated protein, an intracellular molecule known to associate with the lymphocyte-activating surface receptors SLAM and 2B4. We have identified a single nucleotide mutation in SLAM-associated protein that affects the NK cell function of males carrying the mutated gene. In contrast to normal controls, both NK and lymphokine-activated killer cell cytotoxicity was significantly reduced in two XLP patients. In addition to decreased baseline cytotoxicity, ligation of 2B4 significantly augmented NK lytic function in normal controls but failed to enhance the cytotoxicity of NK cells from XLP patients. These findings suggest that association of SAP with 2B4 is necessary for optimal NK/lymphokine-activated killer cytotoxicity and imply that alterations in SAP/2B4 signaling contribute to the immune dysfunction observed in XLP.
Subject(s)
Immunologic Deficiency Syndromes/genetics , Immunologic Deficiency Syndromes/immunology , Intracellular Signaling Peptides and Proteins , Killer Cells, Natural/immunology , Lymphocyte Activation , Lymphoproliferative Disorders/genetics , Lymphoproliferative Disorders/immunology , Receptors, Immunologic , X Chromosome , Adjuvants, Immunologic/physiology , Antigens, CD/biosynthesis , CD48 Antigen , Carrier Proteins/genetics , Cells, Cultured , Cytotoxicity Tests, Immunologic , Cytotoxicity, Immunologic/genetics , Genetic Linkage/immunology , Humans , K562 Cells , Killer Cells, Lymphokine-Activated/immunology , Killer Cells, Lymphokine-Activated/metabolism , Killer Cells, Natural/metabolism , Ligands , Lymphocyte Activation/genetics , Male , Membrane Glycoproteins/immunology , Membrane Glycoproteins/metabolism , Membrane Glycoproteins/physiology , Mutation , Signaling Lymphocytic Activation Molecule Associated Protein , Signaling Lymphocytic Activation Molecule Family , Tumor Cells, Cultured , X Chromosome/immunologyABSTRACT
Mutations of the common gamma chain (gammac) of cytokine receptors cause X-linked severe combined immunodeficiency (XSCID), a candidate disease for gene therapy. Using an XSCID murine model, we have tested the feasibility of stem cell gene correction. XSCID bone marrow (BM) cells were transduced with a retroviral vector expressing the murine gammac (mgammac) and engrafted in irradiated XSCID animals. Transplanted mice developed mature B cells, naive T cells, and mature natural killer (NK) cells, all of which were virtually absent in untreated mice. The mgammac transgene was detected in all treated mice, and we could demonstrate mgammac expression in newly developed lymphocytes at both the RNA and protein level. In addition, treated mice showed T cell proliferation responses to mitogens and production of antigen-specific antibodies upon immunization. Four of seven treated animals showed a clear increase of the transgene positive cells, suggesting in vivo selective advantage for gene-corrected cells. Altogether, these results show that retroviral-mediated gene transfer can improve murine XSCID and suggest that similar strategies may prove beneficial in human clinical trials.
Subject(s)
Bone Marrow Cells/immunology , Genetic Linkage , Genetic Therapy , Lymphatic System/growth & development , Lymphatic System/physiology , X Chromosome/genetics , X Chromosome/immunology , Animals , B-Lymphocytes/immunology , Bone Marrow Transplantation/immunology , Cell Division , Cell Line , Flow Cytometry , Genetic Vectors , Immunoglobulin G/metabolism , Immunophenotyping , Killer Cells, Natural/immunology , Lymphatic System/immunology , Lymphocyte Count , Mice , Mice, Knockout , Mice, SCID , Receptors, Cytokine/genetics , Receptors, Cytokine/immunology , Receptors, Interleukin-2/genetics , Retroviridae/genetics , Reverse Transcriptase Polymerase Chain Reaction , T-Lymphocytes/immunology , Transduction, Genetic , Transgenes/geneticsABSTRACT
We show that LPS-stimulated circulating CD14-positive monocytes from patients with common variable immunodeficiency (CVID) express a higher proportion of intracellular IL-12-positive cells than monocytes from patients with X-linked agammaglobulinemia or normal subjects. We used four-color flow cytometry and measured IL-12 with an Ab to the p40 subunit following stimulation with LPS. The raised IL-12 is associated with an increased frequency of IFN-gamma-positive T cells, but not of IFN-gamma-positive CD56+ NK cells. These increases in frequency of cytokine-positive cells are due to a decrease in the absolute numbers of circulating monocytes and T cells that are negative for IL-12 and IFN-gamma, respectively. The increased frequency of IL-12-positive monocytes appears to be selective because TNF-alpha was not increased, and is thus unlikely to reflect a general activation. Chronic infection is also unlikely to explain our data since cells from X-linked agammaglobulinemia patients with a similar Ig deficiency do not show these changes. Our data suggest a fundamental abnormality in the IL-12/IFN-gamma circuit in CVID, with up-regulation of IL-12 being the "primary" factor. This imbalance is likely to skew the immune response away from Ab production and also explains the failure of CVID T cells to make Ag-specific memory cells and the chronic inflammatory and granulomatous complications that are a feature of CVID. This disease appears to be a rare example of a polarized Th1-type response and may in part be due to a genetic defect in the control of IL-12 production.
Subject(s)
Common Variable Immunodeficiency/immunology , Interleukin-12/biosynthesis , Interleukin-12/deficiency , Monocytes/metabolism , Up-Regulation/immunology , Agammaglobulinemia/genetics , Agammaglobulinemia/immunology , Agammaglobulinemia/pathology , CD28 Antigens/biosynthesis , CD3 Complex/biosynthesis , CD4-Positive T-Lymphocytes/metabolism , CD56 Antigen/biosynthesis , CD8-Positive T-Lymphocytes/metabolism , Cell Count , Common Variable Immunodeficiency/pathology , Dendritic Cells/immunology , Dendritic Cells/metabolism , Female , Genetic Linkage/immunology , Humans , Interleukin-12/blood , Intracellular Fluid/immunology , Intracellular Fluid/metabolism , Killer Cells, Natural/metabolism , Leukocyte Count , Lipopolysaccharides/pharmacology , Lymphocyte Depletion , Macrophage Activation , Male , Monocytes/immunology , T-Lymphocyte Subsets/metabolism , Tumor Necrosis Factor-alpha/biosynthesis , Tumor Necrosis Factor-alpha/metabolism , X Chromosome/immunologyABSTRACT
OBF-1 is a B cell-restricted transcriptional coactivator that is recruited to octamer-containing promoters by interacting with the POU domain of Oct-1 or Oct-2. We have shown earlier that mice lacking OBF-1 were dramatically impaired in their ability to mount humoral immune responses and did not develop germinal centers in the spleen; however, they had a largely normal B cell development in the bone marrow. In this study, we demonstrate that OBF-1-deficient mice also have an early defect in B cell development and show that OBF-1-/- immature B cells are greatly impaired at the transition from the bone marrow to the spleen. In addition, when the OBF-1 mutation is combined to a mutation in the gene encoding Bruton's tyrosine kinase, a striking phenotype is observed. These double-deficient animals lack peripheral B cells and have virtually no serum Igs, thus closely resembling human X chromosome-linked agammaglobulinemia.
Subject(s)
Agammaglobulinemia/genetics , B-Lymphocytes/immunology , Lymphopenia/genetics , Protein-Tyrosine Kinases/deficiency , Trans-Activators/deficiency , Agammaglobulinaemia Tyrosine Kinase , Agammaglobulinemia/enzymology , Agammaglobulinemia/immunology , Agammaglobulinemia/pathology , Animals , B-Lymphocytes/enzymology , B-Lymphocytes/pathology , Cell Differentiation/genetics , Cell Differentiation/immunology , Female , Gene Expression Regulation/immunology , Gene Expression Regulation, Developmental/immunology , Genes, Immunoglobulin , Genetic Linkage/immunology , Humans , Immunoglobulins/biosynthesis , Immunoglobulins/blood , Lymphoid Tissue/pathology , Lymphopenia/enzymology , Lymphopenia/immunology , Lymphopenia/pathology , Male , Mice , Mice, Inbred C57BL , Mice, Inbred CBA , Mice, Knockout , Multigene Family/immunology , Phenotype , Protein-Tyrosine Kinases/genetics , Trans-Activators/genetics , X Chromosome/genetics , X Chromosome/immunologyABSTRACT
The B cell receptor is required for the emigration of newly generated B lymphocytes and for their maintenance in the periphery. A specific maintenance defect was noted in fraction I (IgDhighIgMlow) B cells in Xid mice (which harbor a mutation in Btk). Although Bcl-2 levels in fractions I and II (IgDhighIgMhigh) are equivalent in normal and Xid B cells, a novel peak of Bcl-2low fraction III (IgDlowIgMhigh) B cells was noted in the Xid mouse. Since this B cell population resembled bone marrow immature B cells, we examined the emigration of newly formed B cells in normal and Xid mice. These studies revealed the accelerated emigration of newly formed Xid B cells. We conclude that distinct Btk-independent and Btk-dependent signals mediate emigration and maintenance events during peripheral B cell maturation.
Subject(s)
B-Lymphocytes/pathology , Cell Movement/genetics , Cell Movement/immunology , Immunologic Deficiency Syndromes/genetics , Immunologic Deficiency Syndromes/pathology , Agammaglobulinaemia Tyrosine Kinase , Animals , Apoptosis/genetics , Apoptosis/immunology , B-Lymphocytes/enzymology , B-Lymphocytes/metabolism , Cell Differentiation/genetics , Cell Differentiation/immunology , Cell Separation , Disease Models, Animal , Immunologic Deficiency Syndromes/enzymology , Mice , Mice, Inbred CBA , Mice, Mutant Strains , Protein-Tyrosine Kinases/deficiency , Protein-Tyrosine Kinases/genetics , Proto-Oncogene Proteins c-bcl-2/deficiency , Proto-Oncogene Proteins c-bcl-2/genetics , Proto-Oncogene Proteins c-bcl-2/metabolism , Stem Cells/enzymology , Stem Cells/metabolism , Stem Cells/pathology , X Chromosome/immunologyABSTRACT
Bruton's tyrosine kinase (Btk) plays a critical role in B cell Ag receptor (BCR) signaling, as indicated by the X-linked immunodeficiency and X-linked agammaglobulinemia phenotypes of mice and men that express mutant forms of the kinase. Although Btk activity can be regulated by Src-family and Syk tyrosine kinases, and perhaps by phosphatidylinositol 3,4,5-trisphosphate, BCR-coupled signaling pathways leading to Btk activation are poorly understood. In view of previous findings that CD19 is involved in BCR-mediated phosphatidylinositol 3-kinase (PI3-K) activation, we assessed its role in Btk activation. Using a CD19 reconstituted myeloma model and CD19 gene-ablated animals we found that BCR-mediated Btk activation and phosphorylation are dependent on the expression of CD19, while BCR-mediated activation of Lyn and Syk is not. Wortmannin preincubation inhibited the BCR-mediated activation and phosphorylation of Btk. Btk activation was not rescued in the myeloma by expression of a CD19 mutant in which tyrosine residues previously shown to mediate CD19 interaction with PI3-K, Y484 and Y515, were changed to phenylalanine. Taken together, the data presented indicate that BCR aggregation-driven CD19 phosphorylation functions to promote Btk activation via recruitment and activation of PI3-K. Resultant phosphatidylinositol 3,4,5-trisphosphate probably functions to localize Btk for subsequent phosphorylation and activation by Src and Syk family kinases.
Subject(s)
Antigens, CD19/metabolism , Immunologic Deficiency Syndromes/enzymology , Phosphatidylinositol 3-Kinases/metabolism , Protein-Tyrosine Kinases/metabolism , Receptors, Antigen, B-Cell/physiology , Tyrosine/metabolism , Agammaglobulinaemia Tyrosine Kinase , Animals , Antigens, CD19/physiology , B-Lymphocytes/enzymology , B-Lymphocytes/metabolism , B-Lymphocytes/pathology , Calcium Signaling/immunology , Enzyme Activation/genetics , Enzyme Activation/immunology , Enzyme Precursors/metabolism , Enzyme Precursors/physiology , Humans , Immunologic Deficiency Syndromes/genetics , Immunologic Deficiency Syndromes/immunology , Intracellular Signaling Peptides and Proteins , Isoenzymes/metabolism , Mice , Mice, Inbred CBA , Mice, Knockout , Phosphatidylinositol 3-Kinases/physiology , Phospholipase C gamma , Phosphorylation , Protein-Tyrosine Kinases/genetics , Protein-Tyrosine Kinases/physiology , Spleen/cytology , Spleen/enzymology , Syk Kinase , Tumor Cells, Cultured , Type C Phospholipases/metabolism , Tyrosine/physiology , X Chromosome/immunology , src-Family Kinases/metabolism , src-Family Kinases/physiologyABSTRACT
The incidence of the X-linked immunodeficiency (Xid) on the outcome of Schistosoma mansoni infection has been evaluated through a comparative analysis of parasitological and immune parameters in two different mouse strains: control BALB/c and BALB. Xid mice which carry the Xid mutation and lack B1 (CD5+ B) cells. This study clearly demonstrates that infected B1 cell-deficient animals display a higher susceptibility to S. mansoni infection as revealed by an increase in the tissue egg loads and a significantly elevated mortality, as well as an increase in the granuloma densities. The analysis of the humoral and the cellular responses, conducted in the same experimental conditions, indicates differences in terms of cytokine production after specific antigenic stimulation of splenocytes. Larger amounts of IFN-gamma and IL-4 are observed in BALB. Xid mice while IL-10 production is reduced. In parallel, the study of the specific antibody isotype profiles shows higher amounts of specific IgE and IgG1 antibodies and lower amounts of IgM and IgA in BALB. Xid mice. Taken together, these observations support the idea that B cells are playing a role in the ability of mice to tolerate infection with Schistosoma mansoni.