Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0021051 (immunodeficiency)
 71,517 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Agammaglobulinemia is a rare primary immunodeficiency characterized by an early block of B cell development in the bone marrow, resulting in the absence of peripheral B cells and low/absent immunoglobulin serum levels. So far, mutations in Btk, mu heavy chain, surrogate light chain, Igalpha, and B cell linker have been found in 85-90% of patients with agammaglobulinemia. We report on the first patient with agammaglobulinemia caused by a homozygous nonsense mutation in Igbeta, which is a transmembrane protein that associates with Igalpha as part of the preBCR complex. Transfection experiments using Drosophila melanogaster S2 Schneider cells showed that the mutant Igbeta is no longer able to associate with Igalpha, and that assembly of the BCR complex on the cell surface is abrogated. The essential role of Igbeta for human B cell development was further demonstrated by immunofluorescence analysis of the patient's bone marrow, which showed a complete block of B cell development at the pro-B to preB transition. These results indicate that mutations in Igbeta can cause agammaglobulinemia in man.
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PMID:Mutations of the Igbeta gene cause agammaglobulinemia in man. 1770 24

Extensive research on molecular genetics in recent decades has provided a wealth of information regarding the underlying mechanisms of primary immunodeficiency diseases. The microarray technology has made its entry into the molecular biology research area and hereby enabled signature expression profiling of whole species genomes. Perhaps no other methodological approach has transformed molecular biology more in recent years than the use of microarrays. Microarray technology has led the way from studies of the individual biological functions of a few related genes, proteins or, at best, pathways towards more global investigations of cellular activity. The development of this technology immediately yielded new and interesting information, and has produced more data than can be currently dealt with. It has also helped to realize that even a 'horizontally exhaustive' molecular analysis is insufficient. Applications of this tool in primary immunodeficiency studies have generated new information, which has led to a better understanding of the underlying basic biology of the diseases. Also, the technology has been used as an exploratory tool to disease genes in immunodeficiency diseases of unknown cause as in the case of the CD3Delta-chain and the MAPBPIP deficiency. For X-linked agammaglobulinemia, the technique has provided better understanding of the genes influenced by Btk. There is considerable hope that the microarray technology will lead to a better understanding of disease processes and the molecular phenotypes obtained from microarray experiments may represent a new tool for diagnosis of the disease.
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PMID:Gene expression signatures in primary immunodeficiencies: the experience from human disease and mouse models. 1789 92

X-linked agammaglobulinemia (XLA) is a primary immunodeficiency disorder caused by germline mutation of the Bruton tyrosine kinase (BTK) gene. It is characterized by disturbed B-cell development, decreased immunoglobulin levels, and increased patient susceptibility to infection. An increased risk of cancer has been suggested, but most reports were described before the identification of BTK gene mutation as the cause of XLA. Here we describe 2 patients with genetically ascertained XLA and multiple colorectal neoplasms, supporting an increased risk of colorectal cancer in XLA and highlighting the potential importance of colorectal surveillance in these patients.
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PMID:Multiple colorectal neoplasms in X-linked agammaglobulinemia. 1796 62

Certain autoimmune diseases result in abnormal bone homeostasis, but association of immunodeficiency with bone is poorly understood. Osteoclasts, which derive from bone marrow cells, are under the control of the immune system. Differentiation of osteoclasts is mainly regulated by signaling pathways activated by RANK and immune receptors linked to ITAM-harboring adaptors. However, it is unclear how the two signals merge to cooperate in osteoclast differentiation. Here we report that mice lacking the tyrosine kinases Btk and Tec show severe osteopetrosis caused by a defect in bone resorption. RANK and ITAM signaling results in formation of a Btk(Tec)/BLNK(SLP-76)-containing complex and PLCgamma-mediated activation of an essential calcium signal. Furthermore, Tec kinase inhibition reduces osteoclastic bone resorption in models of osteoporosis and inflammation-induced bone destruction. Thus, this study reveals the importance of the osteoclastogenic signaling complex composed of tyrosine kinases, which may provide the molecular basis for a new therapeutic strategy.
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PMID:Tyrosine kinases Btk and Tec regulate osteoclast differentiation by linking RANK and ITAM signals. 1832 66

Bruton's agammaglobulinemia tyrosine kinase (Btk) is a cytoplasmic tyrosine kinase important in B-lymphocyte development, differentiation, and signaling. Btk is a member of the Tec family of kinases. Mutations in the Btk gene lead to X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (Xid) in mice. Activation of Btk triggers a cascade of signaling events that culminates in the generation of calcium mobilization and fluxes, cytoskeletal rearrangements, and transcriptional regulation involving nuclear factor-kappaB (NF-kappaB) and nuclear factor of activated T cells (NFAT). In B cells, NF-kappaB was shown to bind to the Btk promoter and induce transcription, whereas the B-cell receptor-dependent NF-kappaB signaling pathway requires functional Btk. Moreover, Btk activation is tightly regulated by a plethora of other signaling proteins including protein kinase C (PKC), Sab/SH3BP5, and caveolin-1. For example, the prolyl isomerase Pin1 negatively regulates Btk by decreasing tyrosine phosphorylation and steady state levels of Btk. It is intriguing that PKC and Pin1, both of which are negative regulators, bind to the pleckstrin homology domain of Btk. To this end, we describe here novel mutations in the pleckstrin homology domain investigated for their transforming capacity. In particular, we show that the mutant D43R behaves similar to E41K, already known to possess such activity.
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PMID:Bruton's tyrosine kinase (Btk): function, regulation, and transformation with special emphasis on the PH domain. 1929 Sep 21

Sophisticated genetic tools have made possible the identification of the genes responsible for most well-described immunodeficiencies in the past 15 years. Mutations in Btk, components of the pre-B cell and B cell receptor (lambda5, Igalpha, Igbeta), or the scaffold protein BLNK account for approximately 90% of patients with defects in early B cell development. Hyper-IgM syndromes result from mutations in CD40 ligand, CD40, AID, or UNG in 70-80% of affected patients. Rare defects in ICOS or CD19 can result in a clinical picture that is consistent with common variable immunodeficiency, and as many as 10% of patients with this disorder have heterozygous amino acid substitutions in TACI. For all these disorders, there is considerable clinical heterogeneity in patients with the same mutation. Identifying the genetic and environmental factors that influence the clinical phenotype may enhance patient care and our understanding of normal B cell development.
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PMID:Primary B cell immunodeficiencies: comparisons and contrasts. 1930 39

The immunodeficiency disorder, X-linked agammaglobulinemia (XLA), results from mutations in the gene encoding Bruton tyrosine kinase (Btk). Btk is required for pre-B cell clonal expansion and B-cell antigen receptor signaling. XLA patients lack mature B cells and immunoglobulin and experience recurrent bacterial infections only partially mitigated by life-long antibody replacement therapy. In pursuit of definitive therapy for XLA, we tested ex vivo gene therapy using a lentiviral vector (LV) containing the immunoglobulin enhancer (Emu) and Igbeta (B29) minimal promoter to drive B lineage-specific human Btk expression in Btk/Tec(-/-) mice, a strain that reproduces the features of human XLA. After transplantation of EmuB29-Btk-LV-transduced stem cells, treated mice showed significant, albeit incomplete, rescue of mature B cells in the bone marrow, peripheral blood, spleen, and peritoneal cavity, and improved responses to T-independent and T-dependent antigens. LV-treated B cells exhibited enhanced B-cell antigen receptor signaling and an in vivo selective advantage in the peripheral versus central B-cell compartment. Secondary transplantation showed sustained Btk expression, viral integration, and partial functional responses, consistent with long-term stem cell marking; and serial transplantation revealed no evidence for cellular or systemic toxicity. These findings strongly support pursuit of B lineage-targeted LV gene therapy in human XLA.
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PMID:B cell-specific lentiviral gene therapy leads to sustained B-cell functional recovery in a murine model of X-linked agammaglobulinemia. 2009 6

In recent years, the field of primary immunodeficienciency diseases (PID) has experienced remarkable progress with the identification of a number of new genes associated with specific diseases. Yet the diagnosis of PID remains difficult. In fact, this field requires continuous updating because once a novel molecule related to the immune function is discovered, the corresponding PID will soon be described. Since comprehensive reviews on the classification of PID are available, we concentrate here on reviewing some controversial and new issues, mainly those related to the role of T-cells and innate immunity. We will consider common variable immunodeficiency as an example of a PID where several immune pathways are impaired. We will also discuss the restricted usage of the T-cell receptor repertoire in PID. Innate immunity and Toll-like receptors (TLR) are new major players in this field. We will therefore discuss the association of TLR with the function of Bruton tyrosine kinase (Btk) that is essential in the development of B-cells and in the pathogenesis of X-linked agammaglobulinemia. Finally, we will discuss the role of mast-cells. These cells were once thought to be relevant almost exclusively to the pathogenesis of allergy. Now we know that mast cells are involved in initiating the adaptive response and may contribute to ineffective immune responses.
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PMID:Recent insights in primary immunodeficiency diseases: the role of T-lymphocytes and innate immunity. 2012 23

The immune response consists of two main components: humoral immunity represented by B lymphocytes and cellular immunity maintained by the T lymphocytes. Immunoglobulins, produced by B-lymphocytes, are the main mediators of humoral immunity, and deficiencies at this level affect the body's response to infection. Plasmocytes produce nine antibody izotypes: immunoglobulins G (IgG1, IgG2, IgG3, IgG4), immunoglobulins M (IgM), immunoglobulins A (IgA1, IgA2), immunoglobulins D (IGD) and immunoglobulins E (IgE). Primary hypogammaglobulinemias are characterized by the occurrence of recurrent infections and, paradoxically, by the occurrence of autoimmune diseases. Characteristic for these diseases is that symptoms occur at 7-9 months after birth, when transplacental antibody titers transmitted from the mother decrease, and the infant's body is unable to synthesize them to normal levels. Primary hypogammaglobulinemias are transmitted genetically, but mutations at the molecular level are still not fully understood. The most common are: Bruton agammaglobulinemia, transient newborn hypogammaglobulinemia, selective immunoglobulin deficiency and variable common immunodeficiency. Treatment consists of monthly antibiotics and immunoglobulins, depending on antibody titers (except for IgA deficiency).
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PMID:Primary immunodeficiencies of the B lymphocyte. 2030 97

X-linked agammaglobulinemia (XLA) is the most common primary immunodeficiency (PID) in man and caused by mutations in the Bruton's tyrosine kinase (BTK) gene. XLA is characterized by a B-cell differentiation arrest in bone marrow, absence of mature B cells and immunoglobulins (Igs), and recurrent bacterial infections. We used self-inactivating lentiviral vectors expressing codon-optimized human BTK under the control of three different ubiquitous or B cell-specific promoters. Btk-/- mice engrafted with transduced cells showed correction of both precursor B-cell and peripheral B-cell development. Lentiviral vectors containing the wildtype BTK sequence did not correct the phenotype. All treated mice with codon-optimized BTK exhibited the recovery of B1 cells in the peritoneal cavity, and of serum IgM and IgG3 levels. Calcium mobilization responses upon B-cell receptor stimulation as well as in vivo responses to T cell-independent antigens were restored. Viral promoters overexpressing BTK >100-fold above normal resulted in erythro-myeloid proliferations independent of insertional mutagenesis. However, transplantation into secondary Btk-/- recipients using cellular promoters resulted in functional restoration of peripheral B cells and IgM levels, without any adverse effects. In conclusion, transduction of human BTK corrects B-cell development and antigen-specific antibody responses in Btk-/- mice, thus indicating the feasibility of lentiviral gene therapy for XLA, provided that BTK expression does not vastly exceed normal levels.
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PMID:Correction of B-cell development in Btk-deficient mice using lentiviral vectors with codon-optimized human BTK. 2057 53


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