Inflammatory bowel disease (IBD) represents a heterogeneous group of gastrointestinal disorders, where commensal gut flora provokes an either (a) insufficient or (b) uncontrolled immune response. ...This results either in a lack of or in excessive inflammation mainly manifesting as Crohn's disease or ulcerative colitis. IBD commonly presents in adolescence and adulthood and often follows a chronic relapsing course. Genetic and/or environmental factors contribute to the failure of gut immune homeostasis. Genome-wide association studies have identified over 160 susceptibility loci associated with IBD, including polymorphisms in interleukin-10 (IL-10). The anti-inflammatory cytokine IL-10 dampens intestinal inflammation and is therefore a good candidate gene for IBD. Polymorphisms in the IL-10 receptor are also associated with ulcerative colitis presenting in early childhood. Moreover, severe infantile enterocolitis resembling Crohn's disease, caused by loss-of-function mutations in IL-10 and IL-10 receptor, is characterised by a very early onset (usually within the first 3 months of life), unresponsiveness to standard treatment including immunosuppressive therapy, and severe perianal disease with abscesses and fistulas. In these patients, inflammation and polymorphic infiltrates are mainly confined to the colon with very little involvement of the small intestine. Ulceration and granulomas, bloody diarrhoea and failure to thrive also occur. Furthermore, patients may suffer from recurrent fever and respiratory infections. Individuals with IL-10 receptor mutations also experience cutaneous folliculitis and arthritis. Hematopoietic stem cell transplantation is currently the only curative therapy.
Molecular dissection of inborn errors of immunity can help to elucidate the nonredundant functions of individual genes. We studied 3 children with an immune dysregulation syndrome of susceptibility ...to infection, lymphadenopathy, hepatosplenomegaly, developmental delay, autoimmunity, and lymphoma of B-cell (n = 2) or T-cell (n = 1) origin. All 3 showed early autologous T-cell reconstitution following allogeneic hematopoietic stem cell transplantation. By whole-exome sequencing, we identified rare homozygous germline missense or nonsense variants in a known epigenetic regulator of gene expression: ten-eleven translocation methylcytosine dioxygenase 2 (TET2). Mutated TET2 protein was absent or enzymatically defective for 5-hydroxymethylating activity, resulting in whole-blood DNA hypermethylation. Circulating T cells showed an abnormal immunophenotype including expanded double-negative, but depleted follicular helper, T-cell compartments and impaired Fas-dependent apoptosis in 2 of 3 patients. Moreover, TET2-deficient B cells showed defective class-switch recombination. The hematopoietic potential of patient-derived induced pluripotent stem cells was skewed toward the myeloid lineage. These are the first reported cases of autosomal-recessive germline TET2 deficiency in humans, causing clinically significant immunodeficiency and an autoimmune lymphoproliferative syndrome with marked predisposition to lymphoma. This disease phenotype demonstrates the broad role of TET2 within the human immune system.
•We report autosomal-recessive germline deficiency of the methylcytosine dioxygenase TET2 in 3 immunodeficient children.•Their phenotype of immunodeficiency, autoimmunity and lymphoproliferation highlights requisite roles for TET2 in the human immune system.
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Mucocutaneous candidiasis and dermatophyte infections occur either in isolation or alongside other symptoms in patients with various primary immunodeficiency diseases with diverse genetic defects, ...which result in impaired IL-17 immunity, IL-22 immunity, or both. In patients with chronic mucocutaneous candidiasis, disease-associated polymorphisms in DECTIN1 act on the level of fungal recognition, whereas mutations in caspase recruitment domain–containing protein 9 (CARD9) disturb the subsequent spleen tyrosine kinase 2–CARD9/BCL10/MALT1–driven signaling cascade, impairing nuclear factor κB–mediated maturation of antigen-presenting cells and priming of naive T cells to differentiate into the TH 17 cell lineage. TH 17-priming cytokines signal through the transcription factor signal transducer and activator of transcription (STAT) 3, which in turn induces the TH 17 lineage–determining transcription factor retinoic acid–related orphan receptor γt. Dominant-negative mutations in STAT3 result in reduced numbers of TH 17 cells, causing localized candidiasis in patients with hyper-IgE syndrome. In patients with chronic mucocutaneous candidiasis, gain-of-function STAT1 mutations shift the cellular response toward TH 17 cell–inhibiting cytokines. TH 17 cells secrete IL-17 and IL-22, which are cytokines with potent antifungal properties, including production of antimicrobial peptides and activation and recruitment of neutrophils. Neutrophils mediate microbial killing through phagocytosis, degranulation, and neutrophil extracellular traps. Mutations in IL17F and IL17R in patients with chronic mucocutaneous candidiasis, as well as neutralizing autoantibodies against IL-17 and IL-22 in patients with autoimmune polyendocrinopathy–candidiasis–ectodermal dystrophy, directly impair IL-17 and IL-22 immunity.
The phenotype of human STK4 deficiency Abdollahpour, Hengameh; Appaswamy, Giridharan; Kotlarz, Daniel ...
Blood,
04/2012, Volume:
119, Issue:
15
Journal Article
Peer reviewed
Open access
We describe a novel clinical phenotype associating T- and B-cell lymphopenia, intermittent neutropenia, and atrial septal defects in 3 members of a consanguineous kindred. Their clinical histories ...included recurrent bacterial infections, viral infections, mucocutaneous candidiasis, cutaneous warts, and skin abscesses. Homozygosity mapping and candidate gene sequencing revealed a homozygous premature termination mutation in the gene STK4 (serine threonine kinase 4, formerly having the symbol MST1). STK4 is the human ortholog of Drosophila Hippo, the central constituent of a highly conserved pathway controlling cell growth and apoptosis. STK4-deficient lymphocytes and neutrophils exhibit enhanced loss of mitochondrial membrane potential and increased susceptibility to apoptosis. STK4 deficiency is a novel human primary immunodeficiency syndrome.
Background Inherited deficiencies of IL-10 or IL-10 receptor (IL-10R) lead to immune dysregulation with life-threatening early-onset enterocolitis. Objectives We sought to gather clinical data of ...IL-10/IL-10R–deficient patients and devise guidelines for diagnosis and management, including hematopoietic stem cell transplantation (HSCT). Methods We enrolled 40 patients with early-onset enterocolitis and screened for mutations in IL10 / IL10R using genetic studies, functional studies, or both of the IL-10 signaling pathway. Medical records of IL-10/IL-10R–deficient patients were reviewed and compiled. Results Of 40 patients, we identified 7 with novel mutations, predominantly in consanguineous families with more than 1 affected member. IL-10/IL-10R–deficient patients had intractable enterocolitis, perianal disease, and fistula formation. HSCT was carried out in 2 patients with IL-10 deficiency and 1 patient with IL-10R α chain deficiency and proved to be an effective therapy, leading to rapid improvement of clinical symptoms and quality of life. Conclusion Because the defect in patients with IL-10/IL-10R deficiency resides in hematopoietic lineage cells and their colitis is resistant to standard immunosuppressive therapy, HSCT should be considered early as a potentially curative therapeutic option.
Patient 4 (sibling to patient 3) was well until he presented with inflammatory colitis and Hodgkin lymphoma (inguinal and para-aortic region) at age 16 years. Because of his sibling's history, CTLA4 ...haploinsufficiency was confirmed by both genetic and protein level testing, the only patient in this cohort to have an identified mutation before HSCT. In summary, 4 of 8 patients experienced GvHD despite having well-matched donors and receiving alemtuzumab in 3 out of 4 cases.\n9 (5.4-16.8)IgA 0.27 (0.74-2.61)IgM 0.84 (0.40-1.95)Preimmunoglobulin therapyPre-RTX 23 y Interstitial lung disease ("nodular lymphoid hyperplasia") Transverse myelitis Recurrent white matter and brainstem lesions with oligoclonal bands and elevated IgG index Arthritis Father:ITPSister:Patient no. 7 Table I Patients' characteristics ABVD, Adriamcyin (Doxorubicin), bleomycin, vinblastine, dacarbazine; naive CD4, CD3+CD4+CD27+CD45RA+; naive CD8, CD3+CD4-CD27+CD45RA+; Euronet PHL-C1, Euronet pediatric Hodgkin lymphoma-C1; F, female; IDDM, insulin-dependent diabetes mellitus; ITP, idiopathic thrombocytopenic purpura; M, male; NK, natural killer; PN, parenteral nutrition; RTX, rituximab.
Type I interferon (IFN-α/β) is a fundamental antiviral defense mechanism. Mouse models have been pivotal to understanding the role of IFN-α/β in immunity, although validation of these findings in ...humans has been limited. We investigated a previously healthy child with fatal encephalitis after inoculation of the live attenuated measles, mumps, and rubella (MMR) vaccine. By targeted resequencing, we identified a homozygous mutation in the high-affinity IFN-α/β receptor (IFNAR2) in the proband, as well as a newborn sibling, that rendered cells unresponsive to IFN-α/β. Reconstitution of the proband's cells with wild-type IFNAR2 restored IFN-α/β responsiveness and control of IFN-attenuated viruses. Despite the severe outcome of systemic live vaccine challenge, the proband had previously shown no evidence of heightened susceptibility to respiratory viral pathogens. The phenotype of IFNAR2 deficiency, together with similar findings in STAT2-deficient patients, supports an essential but narrow role for IFN-α/β in human antiviral immunity.
Inducible co-stimulator (ICOS) deficiency was the first monogenic defect reported to cause common variable immunodeficiency (CVID)-like disease in 2003. Since then, 16 patients have been reported ...worldwide with an increasing range of clinical phenotypes.
We sought to compare the clinical and immunological phenotype and provide clinical follow-up and therapeutic approaches for treating ICOS-deficient patients.
We describe the clinical and laboratory data of 15 patients with available clinical data. Previous publications and clinical assessment were used as data sources.
The observed ICOS gene mutations were all deletions leading to undetectable protein expression. The clinical phenotype of ICOS deficiency is much broader than initially anticipated and includes not only CVID-like disease but an increased susceptibility to viral and opportunistic infections, as well as cancer. Impaired B-cell development led to decreased memory B-cells in all patients, and hypogammaglobulinemia in all but one patient. Circulating CXCR5
CD4
follicular T-helper-cell numbers were also reduced in all patients. Treatment included immunoglobulin replacement, regular antibiotic prophylaxis, corticosteroids, and steroid-sparing agents. Three patients underwent hematopoietic stem cell transplantation; one of them died due to capillary leak syndrome on day 5 posttransplantation.
The disease spectrum of ICOS deficiency is expanding from solely B-cell to combined B- and T-cell immunodeficiency, suggesting genetic and environmental modifiers. Genetic diagnosis is the only tool to distinguish ICOS deficiency from other immunological defects. Patients with antibody deficiency, autoimmunity, and combined immunodeficiency should be screened for
mutations.
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