Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q00604 (X-linked)
 16,883 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The scurfy (sf) murine mutation causes severe lymphoproliferation, which results in death of hemizygous males (sf/Y) by 22 to 26 days of age. The CD4+ T cells are crucial mediators of this disease. Recent publications have not only identified this mutation as the genetic equivalent of the human disease X-linked neonatal diabetes mellitus, enteropathy, and endocrinopathy syndrome, but also have indicated that the defective protein-scurfin-is a new forkhead/winged-helix protein with a frameshift mutation, resulting in a product without the functional forkhead. These results have lead to speculation that the scurfy gene acts by disrupting the T-cell tolerance mechanism, resulting in hyperresponsiveness and lack of down-regulation. The Rag1KO/sf/Y OVA strain, with virtually 100% of its CD4+ T cells reactive strictly to ovalbumin (OVA) peptide 323-339, is an excellent model for determination of the sf mutation's ability to disrupt tolerance. We hypothesized that Rag1KO/sf/OVA mice would not be tolerant to antigen at a dose that tolerizes control animals. We found that splenic cells from Rag1KO/sf/Y OVA mice injected with the same dose of OVA peptide that induces tolerance in cells from control mice proliferate in vitro in response to OVA peptide. These results are consistent with a defect in the pathway responsible for peripheral T-cell tolerization.
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PMID:A transgenic mouse strain with antigen-specific T cells (RAG1KO/sf/OVA) demonstrates that the scurfy (sf) mutation causes a defect in T-cell tolerization. 1190 Apr 14

Immune dysregulation, polyendocrinopathy and enteropathy with X-linked inheritance (IPEX) is a serious disease arising from mutations in FOXP3. This gene codifies for a transcription factor whose dysfunction results in hyperactivation of T cells. It is not clear, however, why an intermediate phenotype is not seen in heterozygous females, who are completely healthy. In order to address this question, we investigated X-chromosome inactivation in peripheral blood lymphocytes from a heterozygous female with a child affected by IPEX. No preferential inactivation was shown in freshly sorted CD4+, CD8+, CD19+ cells or in IL-2 cultured CD4 and CD8 T cells, indicating that peripheral blood lymphocytes in these women are randomly selected. Moreover, only one single FOXP3 transcript was expressed by CD4 T cell clones analysed by RT-PCR, confirming that this gene is subject to X- inactivation. We hypothesize that hyper-activation of T cell in carriers of FOXP3 mutations is regulated by the presence of normal regulatory T cells.
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PMID:X-chromosome inactivation analysis in a female carrier of FOXP3 mutation. 1229 63

Immune dysregulation, polyendocrinopathy, enteropathy, and X-linked inheritance (IPEX) is one of a group of clinical syndromes that present with multisystem autoimmune disease suggesting a phenotype of immune dysregulation. Clinically, IPEX manifests most commonly with diarrhea, insulin-dependent diabetes mellitus, thyroid disorders, and eczema. FOXP3, the gene responsible for IPEX, maps to chromosome Xp11.23-Xq13.3 and encodes a putative DNA-binding protein of the forkhead family. Recent data indicate that FOXP3 is expressed primarily in the CD4+CD25+ regulatory T-cell subset, where it may function as a transcriptional repressor and key modulator of regulatory T-cell fate and function. This review describes the clinical features of IPEX and the structure, function, and known mutations of FOXP3 that provide important insights into its role in maintenance of immune homeostasis.
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PMID:Immune dysregulation, polyendocrinopathy, enteropathy, and X-linked inheritance (IPEX), a syndrome of systemic autoimmunity caused by mutations of FOXP3, a critical regulator of T-cell homeostasis. 1281 71

The scurfy mutant mouse is the genetic and phenotypic equivalent of the single-gene human autoimmune disease immunodysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX). The scurfy mutation disrupts the Foxp3 gene, a putative master switch for T regulatory cell development. Bone marrow transplant without conditioning was previously reported to be ineffective in scurfy mice, yet clinical remission occurs in transplanted human IPEX patients despite limited donor engraftment. In view of this contradiction, we sought to validate scurfy as a model for studying the pathogenesis and treatment of human IPEX, in particular the phenomenon of dominant immune regulation. One half of scurfy mice given bone marrow transplants after sublethal irradiation recovered and survived long-term with donor chimerism ranging from 1.7% to 50%. Early transfer of 2 x 107 normal T cell-enriched splenocytes also prevented or limited disease and permitted long-term survival. Donor T cells in rescued mice made up 3-5% of lymphocytes and became highly enriched for CD25+ T cells over time. Transfer of 106 CD4+ CD25+ sorted T cells showed some beneficial effect, while CD4+ CD25- cells did not. Thus, both partial bone marrow transplant and T-enriched splenocyte transfer are effective treatments for scurfy. These results indicate that scurfy results from a lack of cells with dominant immune regulatory capacity, possibly T regulatory cells. The potency of small numbers of normal cells indicates that IPEX may be a feasible target for gene therapy.
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PMID:Rescue of the autoimmune scurfy mouse by partial bone marrow transplantation or by injection with T-enriched splenocytes. 1286 24

Mutations of the forkhead/winged helix transcription factor FOXP3 gene on chromosome Xp11.23 cause a rare recessive monogenic disorder called IPEX (immune dysregulation, polyendocrinopathy, including type 1 diabetes, enteropathy, and X-linked syndrome). FOXP3 is necessary for the differentiation of a key immune suppressive subset of T-cells, the CD4+CD25+ regulatory T-cells. Previously, we reported a significant male-female bias in the common, multifactorial form of type 1 diabetes in Sardinia and evidence of linkage of chromosome Xp11 to the disease. These findings indicate that FOXP3 is a prime functional and positional candidate locus for the common form of type 1 diabetes. In the present study, we initially scanned 82 kb of the FOXP3 region for common polymorphisms, including sequencing all of the coding and functionally relevant portions of the gene in 64 Sardinian individuals. Then the most informative polymorphisms in 418 type 1 diabetic families and in 268 male case and 326 male control subjects were sequentially genotyped and tested for disease association. There is no evidence that variants in the FOXP3 regions analyzed are associated with type 1 diabetes and account for the male-female bias observed in Sardinia. Our data indicate that allelic variation in or near the coding regions of the FOXP3 gene does not have a major role in the inherited susceptibility to the common form of type 1 diabetes.
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PMID:No association between variation of the FOXP3 gene and common type 1 diabetes in the Sardinian population. 1522 Feb 19

IPEX syndrome is a genetic autoimmune disease characterized by immune-mediated polyendocrinopathy, enteropathy, and X-linked inheritance. We describe a case of IPEX in which lymphocyte phenotypes were assessed at birth, before initiation of Cyclosporin A therapy, and at frequent intervals to 18 months of age. We performed flow cytometry for lymphocyte subtypes and for activation markers (HLA-DR, CD25, and CD69 or CD71). The ratios of both T to B cells and CD4+ to CD8+ cells were elevated at birth, but CD4+ cells were not activated. HLA-DR+ and CD25+ activated T-cells increased in association with two episodes of clinical deterioration: colitis and the onset of type I diabetes mellitus. These results indicate that measures of activation, particularly HLA-DR+ and CD25+ frequency, correlate well with the development of early active disease and may presage clinical episodes. Continuous maintenance of immunosuppression, once started, appears critical for prevention of permanent tissue damage.
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PMID:Prospective immunological profiling in a case of immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome (IPEX). 1527 Aug 55

The molecular defects recently identified in the rare monogenic autoimmune diseases (AIDs) have pinpointed critical steps in the pathways that contribute to the development of normal immune responses and self-tolerance. Recent studies of autoimmune polyendocrinopathy syndrome type 1, autoimmune lymphoproliferative syndrome, immunodysregulation, polyendocrinopathy and enteropathy, X-linked, IL-2 receptor alpha-chain deficiency, and, in particular, their corresponding mouse models, have revealed the details of the molecular mechanisms of normal immune tolerance, and exposed how defects in these mechanisms result in human autoimmunity. In addition to a deeper understanding of the immune system, detailed molecular characterization of monogenic AIDs will help us to understand the mechanisms behind common polygenic AIDs and, furthermore, to develop novel therapies and intervention strategies to treat them.
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PMID:Monogenic autoimmune diseases - lessons of self-tolerance. 1622 39

The Scurfy mutation of the FoxP3 gene (FoxP3(sf)) in the mouse and analogous mutations in human result in lethal autoimmunity. The mutation of FoxP3 in the hematopoietic cells impairs the development of regulatory T cells. In addition, development of the Scurfy disease also may require mutation of the gene in nonhematopoietic cells. The T cell-extrinsic function of FoxP3 has not been characterized. Here we show that the FoxP3(sf) mutation leads to defective thymopoiesis, which is caused by inactivation of FoxP3 in the thymic stromal cells. FoxP3 mutation also results in overexpression of ErbB2 in the thymic stroma, which may be involved in defective thymopoiesis. Our data reveal a novel T cell-extrinsic function of FoxP3. In combination, the T cell-intrinsic and -extrinsic defects provide plausible explanation for the severity of the autoimmune diseases in the scurfy mice and in patients who have immunodysregulation, polyendocrinopathy, enteropathy, and X-linked syndrome.
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PMID:The Scurfy mutation of FoxP3 in the thymus stroma leads to defective thymopoiesis. 1623 Apr 79

Immunodysregulation, Polyendocrinopathy, Enteropathy, X-linked (IPEX) syndrome is a rare inborn error of immune regulation characterized by the early onset of one or more autoimmune diseases in boys. IPEX is caused by mutations in FOXP3, and is thus the homologue of the scurfy mutant mouse. The gene product, Scurfin, is required for the development of CD4+CD25+ T regulatory cells. In the absence of T regulatory cells, activated CD4+ T cells instigate multi-organ damage resulting in type 1 diabetes, enteropathy, eczema, hypothyroidism, and other autoimmune disorders. While effective therapies are currently limited, studies in the scurfy mouse are revealing aspects of pathophysiology and genetics that will lead to novel approaches for treating IPEX and other autoimmune disorders. Females carrying Foxp3 mutations are unaffected. In new experiments we show that female scurfy mice that are also heterozygous in trans for the X-linked recessive common gamma chain knockout contract autoimmune disease, proving that murine Foxp3 is subject to X-inactivation and providing an example of gene-gene interaction causing autoimmune disease in females. One explanation for the lesser disease severity in these females is proposed.
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PMID:IPEX and FOXP3: clinical and research perspectives. 1624 87

Autoimmune enteropathy (AIE) is a relatively rare condition found most frequently in children. It presents with persistent watery diarrhea and malabsorption and may require total parenteral nutrition for nutritional support. Rare cases have been reported in adults. On histology, the small intestinal villi are flattened but lack the intraepithelial lymphocytosis of celiac disease. In children and rarely in adults, some cases are linked to the IPEX syndrome (Immune dysregulation, Polyendocrinopathy, Enteropathy, X-linked inheritance). We report a 21-year-old man who presented with chronic persistent diarrhea for 4 years. The duodenal biopsies showed villous blunting, chronic inflammation, and decreased to absent goblet cells, Paneth cells, and endocrine cells by histology and electron microscopy. These changes are consistent with an AIE with involvement of non-enterocyte populations. Pathologists must be aware of the possibility of AIE in adults and consider it in the differential diagnosis of duodenitis, intraepithelial lymphocytosis, and small bowel villous flattening.
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PMID:Enteropathy with loss of enteroendocrine and paneth cells in a patient with immune dysregulation: a case of adult autoimmune enteropathy. 1699 80


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