The patients, aged between 5 and 12 years, exhibited the phenotypic variability associated with TMEM173-activating mutations,2-4 with lung disease and systemic inflammation being the major features ...in patient 1 (P1) and patient 3 (P3), while in patient 2 (P2) skin involvement was most prominent (Fig 1; see Supplemental Text and Table E1 in this article's Online Repository at www.jacionline.org). Modest and incomplete downregulation of ISG was recently described in splenic B cells of mice treated with tofacitinib, a JAK1/3 inhibitor, with differential signaling effects suggesting currently poorly understood facets of IFN regulation.9 In this regard, our kinetic ex vivo experiments provide insights into the rapid dynamic changes in IFN signaling secondary to JAK1 blockade.
Background Signals emanating from the antigen T-cell receptor (TCR) are required for T-cell development and function. The T lymphocyte–specific protein tyrosine kinase (Lck) is a key component of the ...TCR signaling machinery. On the basis of its function, we considered LCK a candidate gene in patients with combined immunodeficiency. Objective We identify and describe a child with a T-cell immunodeficiency caused by a homozygous missense mutation of the LCK gene (c.1022T>C) resulting from uniparental disomy. Methods Genetic, molecular, and functional analyses were performed to characterize the Lck deficiency, and the associated clinical and immunologic phenotypes are reported. Results The mutant LCK protein (p.L341P) was weakly expressed with no kinase activity and failed to reconstitute TCR signaling in LCK-deficient T cells. The patient presented with recurrent respiratory tract infections together with predominant early-onset inflammatory and autoimmune manifestations. The patient displayed CD4+ T-cell lymphopenia and low levels of CD4 and CD8 expression on the T-cell surface. The residual T lymphocytes had an oligoclonal T-cell repertoire and exhibited a profound TCR signaling defect, with only weak tyrosine phosphorylation signals and no Ca2+ mobilization in response to TCR stimulation. Conclusion We report a new form of T-cell immunodeficiency caused by a LCK gene defect, highlighting the essential role of Lck in human T-cell development and responses. Our results also point out that defects in the TCR signaling cascade often result in abnormal T-cell differentiation and functions, leading to an important risk factor for inflammation and autoimmunity.
We report three cases of pulmonary disease suggesting fibrosis in two familial and one sporadic case. Pulmonary symptoms were associated with various clinical features of systemic inflammation and ...vasculitis involving the skin, and appeared at different ages. A strong interferon signature was found in all three cases. Disease was not responsive to corticosteroids, and lung transplantation was considered for all three subjects at an early age. One of them underwent double-lung transplantation, but she immediately experienced a primary graft dysfunction and died soon after. Recognized causes of familial interstitial lung disease were all excluded. All three subjects had a mutation in the previously described autoinflammatory disease called SAVI (stimulator of interferon genes STING-associated vasculopathy with onset in infancy). These cases emphasize the need to consider this possibility in children and young adults with lung fibrosis after common causes have been ruled out.
Background Inflammatory bowel disease (IBD) is one of the most common chronic gastrointestinal diseases, but the underlying molecular mechanisms remain largely unknown. Studies of monogenic diseases ...can provide insight into the pathogenesis of IBD. Objective We thought to determine the underlying molecular causes of IBD occurring in 2 unrelated families in association with an immune deficiency. Methods We performed genetic linkage analysis and candidate gene sequencing on 13 patients from a large consanguineous family affected by early-onset IBD, progressive immune deficiency, and, in some cases, autoimmunity and alopecia, a condition we named enteropathy-lymphocytopenia-alopecia. The candidate gene was also sequenced in an unrelated patient with a similar phenotype. We performed histologic analysis of patients' intestinal biopsy specimens and carried out functional assays on PBMCs. Gut organoids derived from a patient's biopsy specimen were analyzed. Results We identified biallelic missense mutations in tetratricopeptide repeat domain 7A (TTC7A) in all patients from both families. The resulting TTC7A depletion modified the proliferation, adhesion, and migratory capacities of lymphocytes through inappropriate activation of the RhoA signaling pathway. Normal function was restored by wild-type TTC7A expression or addition of a RhoA kinase inhibitor. The growth and polarity of gut epithelial organoids were also found to be dependent on the RhoA signaling pathway. Conclusions We show that TTC7A regulates the actin cytoskeleton dynamics in lymphocytes through the RhoA signaling pathway and is required in both lymphocytes and epithelial cells for maintaining equilibrium between cell proliferation, migration, polarization, and cell death. Our study highlights variability in the phenotypic expression resulting from TTC7A deficiency and outlines that impairment of both epithelial cells and lymphocytes cooperatively causes IBD.
Background Gain-of-function mutations in transmembrane protein 173 (TMEM173) encoding stimulator of interferon genes (STING) underlie a recently described type I interferonopathy called ...STING-associated vasculopathy with onset in infancy (SAVI). Objectives We sought to define the molecular and cellular pathology relating to 3 individuals variably exhibiting the core features of the SAVI phenotype including systemic inflammation, destructive skin lesions, and interstitial lung disease. Methods Genetic analysis, conformational studies, in vitro assays and ex vivo flow-cytometry were performed. Results Molecular and in vitro data demonstrate that the pathology in these patients is due to amino acid substitutions at positions 206, 281, and 284 of the human STING protein. These mutations confer cGAMP-independent constitutive activation of type I interferon signaling through TBK1 (TANK-binding kinase), independent from the alternative STING pathway triggered by membrane fusion of enveloped RNA viruses. This constitutive activation was abrogated by ex vivo treatment with the janus kinase 1/2 inhibitor ruxolitinib. Conclusions Structural analysis indicates that the 3 disease-associated mutations at positions 206, 281, and 284 of the STING protein define a novel cluster of amino acids with functional importance in the regulation of type I interferon signaling.
Background We investigated 7 male patients (from 5 different families) presenting with profound lymphopenia, hypogammaglobulinemia, fluctuating monocytopenia and neutropenia, a poor immune response ...to vaccine antigens, and increased susceptibility to bacterial and varicella zoster virus infections. Objective We sought to characterize the genetic defect involved in a new form of X-linked immunodeficiency. Methods We performed genetic analyses and an exhaustive phenotypic and functional characterization of the lymphocyte compartment. Results We observed hemizygous mutations in the moesin (MSN) gene (located on the X chromosome and coding for MSN) in all 7 patients. Six of the latter had the same missense mutation, which led to an amino acid substitution (R171W) in the MSN four-point-one, ezrin, radixin, moesin domain. The seventh patient had a nonsense mutation leading to a premature stop codon mutation (R533X). The naive T-cell counts were particularly low for age, and most CD8+ T cells expressed the senescence marker CD57. This phenotype was associated with impaired T-cell proliferation, which was rescued by expression of wild-type MSN. MSN-deficient T cells also displayed poor chemokine receptor expression, increased adhesion molecule expression, and altered migration and adhesion capacities. Conclusion Our observations establish a causal link between an ezrin-radixin-moesin protein mutation and a primary immunodeficiency that could be referred to as X-linked moesin-associated immunodeficiency.
Abstract Objective RASopathies (Noonan syndrome (NS) and Noonan-related syndromes) are neurodevelopmental syndromes resulting from germline mutations in genes that participate in the rat ...sarcoma/mitogen-activated protein kinases (RAS/MAPK) pathway (PTPN11, SOS1, RAF, KRAS or NRAS, and SHOC2). Some monogenic conditions are associated with the development of systemic lupus erythematosus (SLE), and a few reports described the association of SLE with NS. We aim to search for a relationship between RASopathy and the development of SLE. Methods We reported for the first time a case of 13-year-old boy with NS with loose anagen hair (NSLAH) resulting from mutation in SHOC2 who developed an autoimmune disorder that fulfilled four American College of Rheumatology (ACR) criteria for the classification of SLE (polyarthritis, pericarditis, antinuclear antibodies, and anti-DNA antibodies). The case report then prompted a literature review by a systematic search for English and French articles on the subjects of RASopathies and SLE that had English abstracts in PubMed from 1966 to 2012. Results We identified seven additional patients with RASopathy and SLE. The male-to-female ratio was 1:1 and age at onset of SLE ranged from 5 to 32 years. The most common features were polyarthritis (7/8 patients), autoimmune cytopenia (4/8 patients), and pericarditis (4/8 patients) while only one patient presented with skin involvement. Conclusion The association of two rare diseases in eight patients suggests that RASopathies may be associated with the development of SLE, which is characterized by a higher male-to-female ratio, a lower rate of skin involvement, and a higher rate of pericarditis than “classic” SLE.
SMB cell subset Low (n = 30) Normal (n = 13) P value MZB cell subset Low (n = 17) Normal (n = 13) P value Normal (n = 13) Upper respiratory tract infections 13 11 NS 11 NS Lower respiratory tract ...infections 11 12 NS 9 NS Pneumonia 10 8 NS 2 .017 Bronchiectasis 6 3 NS 0 .041 Autoimmune diseases 2 3 NS 0 NS Splenomegaly 3 2 NS 0 NS Gastroenteritis 3 1 NS 6 .02 Invasive acute infection 4 1 NS 2 NS IgRT 17 6 .0008 11 NS No response to vaccines 9/14 3/11 NS 1/9 NS Normal CD40+IL4-induced proliferation 11/16 10/12 NS 9/9 NS Normal CD40 class-switch recombination 11/16 6/10 NS 9/9 NS Normal BAFF-induced proliferation 6/13 7/12 NS 2/6 NS Normal CpG-induced proliferation 6/13 8/12 NS 3/6 NS Normal anti-A/B allohemagglutinins 2/10 3/9 NS 5/7 NS Table II Characteristics of patients as a function of their SMB and MZB cell counts BAFF, B-cell activating factor; NS, not significant.Low SMB and MZB cell counts were defined as being at least 2 SDs below the age-adjusted normal value (NS, P > .05). Characteristic No. (%) or median (min; max) Sex: male 20 (45.4) Age at onset (y) 1.77 (0.06; 5.9) Age at diagnosis (y) 5.15 (0.33; 17.3) Age at last follow-up (y) 14.46 (4.17; 35.87) Time between symptom onset and diagnosis years 3.00 (0.0; 13.23) Follow-up period (y) 6.29 (0.23; 27.09) Patients with another case in their family 13 (29.5) IgG deficiency 6 (13.6) IgG and IgA deficiency 9 (20.4) IgG and IgM deficiency 3 (6.8) IgA and IgM deficiency 1 (2.2) IgG, IgA, and IgM deficiency 25 (56.8) Patients with upper respiratory tract infections 35 (79.5) Patients with lower respiratory tract infections 33 (75) * Repeated acute bronchitis 17 (38.6) * Pneumonia 20 (45.5) * Bronchiectasis 9 (20.4) Patients with gastroenteritis 10 (22.7) Patients with autoimmune diseases 5 (11.4) Patients with splenomegaly 5 (11.4) Patients with lymphoma 1 (2.2) Table E1 Demographic, clinical, and biological characteristics of patients
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