Journal of Clinical Immunology最新文献

Purpose: Wiskott-Aldrich syndrome (WAS) is an X-linked genetic disorder characterized by distinctive features including microthrombocytopenia, eczema and recurrent infections. In the present study we report clinical, immunological and molecular spectrum of 41 WAS patients diagnosed over last five years.

Methods: Clinical and family history was collected from case records. Comprehensive immunological assessments including lymphocyte subset analysis, and flow cytometry based evaluation of WAS protein (WASP) expressions were performed in patients along with evaluation of carrier status in mothers. Genetic analysis was carried out with either Sanger sequencing or targeted exome sequencing.

Results: The patients included in this study presented at a median age of 9.5 months, with two adult cases. Clinical manifestations encompassed thrombocytopenia, eczema, bleeding, diarrhea, respiratory tract infections, CMV infection, and malignancy. Immunological phenotype revealed T cell lymphopenia, B cell lymphopenia, and elevated IgE levels. Flow cytometry analysis of WASP was performed in 36 cases out of which 68.42% demonstrated complete absent expression while others showed reduced expression. Genetic analysis highlighted that the majority of mutations affect the WH1 domain of WASP while both adult patients showed intronic mutations. Molecular Dynamics analysis conducted for the novel variants P398R and G33R showed an average RMSD (Å) higher than that of the wild type, indicating greater structural perturbations in WASP.

Conclusion: In the present study we have documented 56.09% novel WAS mutations in Indian cohort. Notably, the application of flow cytometry has emerged as a valuable and efficient diagnostic tool for identifying these WAS patients.

Anterior gradient 2 (AGR2) is a protein disulfide isomerase that is important for protein processing in the endoplasmic reticulum and is essential for mucin production in the digestive and respiratory tracts. Bi-allelic AGR2 variants were recently found to cause recurrent respiratory infections and failure to thrive with or without diarrhea (RIFTD; MIM # 620233), although the mechanisms behind this condition remain unclear. To date, at least 15 patients with homozygous AGR2 variants have been reported. Here, we report two affected siblings in a consanguineous family who had recurrent respiratory infections and digestive symptoms, one of whom needed lung transplantation. To identify the genetic cause of their symptoms, we performed exome sequencing and identified a novel homozygous missense variant in AGR2 (NM_006408.4, c.250A>C, p.(Ser84Arg)) in both affected siblings. Both parents had the identical variant in a heterozygous state. This variant is quite rare in the general population and is clinically compatible with RIFTD, substituting a highly conserved CXXS motif with CXXR. We performed structural modeling and functional studies to investigate the effect of this variant. Through transient overexpression, Ser84Arg AGR2 decreased protein stability, and promoted aberrant dimerization under non-reducing conditions. AGR2 functions in a monomer-dimer equilibrium. Size-exclusion chromatography showed that the Ser84Arg mutant had a larger molecular size than the wild-type protein under non-reducing, but not reducing conditions, indicating that Ser84Arg enhanced intermolecular disulfide bonds. In conclusion, we identified a novel pathogenic AGR2 variant and indicated its abnormal monomer-dimer equilibrium as a possible mechanism involved in the pathogenesis of RIFTD.

TREX1 mutations underlie a variety of human diseases, including retinal vasculopathy with cerebral leukoencephalopathy (RVCL or RVCL-S), a catastrophic adult-onset vasculopathy that is often confused with multiple sclerosis, systemic vasculitis, or systemic lupus erythematosus. Patients with RVCL develop brain, retinal, liver, and kidney disease around age 35-55, leading to premature death in 100% of patients expressing an autosomal dominant C-terminally truncated form of TREX1. We previously demonstrated that RVCL is characterized by high levels of DNA damage, premature cellular senescence, and risk of early-onset breast cancer before age 45. Here, we report human TREX1 mosaicism causing organ-limited RVCL in the retina, as well as a gene therapy to synthetically create TREX1 mosaicism as a potential treatment for RVCL. In our patient with organ-limited disease, the mosaic TREX1 mutant allele underwent germline transmission to 3 children, who developed severe multi-organ disease at ~ age 40, unlike their mosaic parent, who has organ-limited disease at age 74. Additionally, we describe our TREX1 prime editor gene therapy that corrects the most common RVCL-causing TREX1 variant in cell culture and in mice. Thus, TREX1 mosaicism causes organ-limited RVCL with a normal lifespan, suggesting that a gene therapy to create TREX1 mosaicism in adults may someday become useful as a treatment for patients with RVCL.

G6PC3 deficiency is a monogenic immunometabolic disorder that causes severe congenital neutropenia type 4. Patients display heterogeneous extra-hematological manifestations, contributing to delayed diagnosis. Here, we investigated the origin and functional consequence of the G6PC3 c.210delC variant found in patients of Mexican descent. Based on the shared haplotypes amongst mutation carriers, we estimated that this variant originated from a founder effect in a common ancestor. Furthermore, by ancestry analysis, we concluded that it appeared in the indigenous Mexican population. At the protein level, we showed that this frameshift mutation leads to an aberrant protein expression in overexpression and patient-derived Epstein-Barr Virus-immortalized B (EBV-B) cells. The neutropenia observed in G6PC3-deficient patients is driven by the intracellular accumulation of the metabolite 1,5-anhydroglucitol-6-phosphate (1,5-AG6P) that inhibits glycolysis. We characterized how the c.210delC variant impacts glycolysis by performing extracellular flux assays on patient-derived EBV-B cells. When treated with 1,5-anhydroglucitol (1,5-AG), the precursor to 1,5-AG6P, patient cells exhibited markedly reduced engagement of glycolysis. Finally, we compared the clinical presentation of patients with the mutation c.210delC and all other G6PC3-deficient patients reported in the literature, and we found that the c.210delC carriers display all prominent clinical features observed in prior patients. In conclusion, G6PC3 c.210delC is a loss-of-function mutation that arose from a founder effect in the indigenous Mexican population. These findings may facilitate the diagnosis of additional patients in this geographical area. Moreover, the in vitro 1,5-AG-dependent functional assay used in our study could be employed to assess the pathogenicity of additional G6PC3 variants.

Hereditary pulmonary alveolar proteinosis (hPAP) is a rare lung-related primary immunodeficiency. In hPAP, variants of genes encoding the heterodimeric GM-CSF receptor alpha or beta-chains (CSF2Rα, CSF2Rβ) lead to perturbations in GM-CSF signalling. These perturbations impair the scavenging function of pulmonary alveolar macrophages leading to accumulation of surfactant proteins and lipids within the alveoli. The replacement of defective pulmonary alveolar macrophages can be achieved with allogeneic hematopoietic stem cell transplantation. However, previous reports highlight undesirable pulmonary outcomes associated with this therapeutic approach. We report a 4-year-old developmentally normal girl born of second-degree consanguineous marriage diagnosed with severe form of CSFRα-deficient PAP. She required recurrent whole lung lavage and hence was treated with allogeneic hematopoietic stem cell transplantation. A reduced toxicity treosulfan-based myeloablative regimen with alemtuzumab serotherapy was used for conditioning. Ciclosporin, mycophenolate mofetil and FAM (fluticasone inhaler, azithromycin, montelukast) were used to prevent graft-versus-host disease and immune-related complications of lung. Her post-transplant course was uneventful with full donor chimerism and complete resolution of symptoms. We demonstrate for the first time in a case of severe CSF2Rα-deficient PAP, the successful use of hematopoietic stem cell transplantation as a primary curative treatment, restoring normal lungs both anatomically and functionally. The case report provides evidence for considering allogeneic hematopoietic stem cell transplant in severe forms of CSF2R-deficient PAP.

Background: Multisystem inflammatory syndrome in children (MIS-C) presents some clinical overlap with Kawasaki disease (KD). Although KD is common in Japan, the clinical characteristics of MIS-C in Japan remain unknown. Therefore, we aimed to determine the epidemiological and clinical features of MIS-C in Japan.

Methods: Using a case reporting form, a nationwide registry was created between November 2020 and March 2023, involving 2,080 facilities throughout Japan. We prospectively and retrospectively enrolled patients with MIS-C. The primary outcomes were the number and incidence rates of children with MIS-C. The secondary outcomes included clinical features, such as KD phenotype, organ involvement, shock, intensive care unit admission, and coronary artery lesions.

Results: Among 398 patients registered, central review identified 129 MIS-C cases (mean age: 8·8 ± 3·7 years). The overall incidence rate was estimated to be 1·5 per 100,000 COVID-19 cases, exhibiting a decline as the COVID-19 pandemic progressed, from 12·3 cases (Pre-Delta) to 1·3 cases (Omicron); 80% of MIS-C cases occurred during the Omicron variant predominant period, and 72% of children with MIS-C met the KD criteria. Cardiovascular (88%) and gastrointestinal (90%) involvement were frequent. In Japan, MIS-C cases showed comparatively less severe clinical features, with shock in 29% and admission to the intensive care unit in 12% of cases. Coronary artery lesions were identified in 15 cases (11·6%), irrespective of the presence of shock. No fatalities were reported.

Conclusion: The incidence of MIS-C was low in Japan. The clinical features distinctively exhibited a more KD-like phenotype, with less severe clinical features.

Griscelli syndrome type 2 (GS2) is a rare, life-threatening immunodysregulatory disorder characterised by impaired cytotoxic activity leading to susceptibility to haemophagocytic lymphohistiocytosis (HLH) and hypopigmentation. We completed a literature review and analysis of clinical data of 149 patients with GS2 including 8 new patients.We identified three founder mutations which show diverse phenotypic profiles (RAB27A c.244 C > T, p.R82C, c.514_518delCAAGC, p.Q172NfsX2, c.550 C > T, p.R184X). The most common presentation was HLH (119/149, 80%), with high proportion of central nervous system involvement (68/149, 46%). Features of partial albinism were present in 105 of 149 cases (70%). Hypopigmentation can be absent in GS2 and should not exclude the diagnosis. Patients with biallelic protein truncating variants (PTV) were more likely to have systemic HLH (44/56, 79%) and partial albinism (45/56, 80%), in comparison to hypomorphic variants (9/41, 22%; 20/41, 49%). Patients with hypomorphic variants presented later (5.4 years cf. 0.4 years, p = < 0.0001) and were more likely to have isolated CNS HLH (2% cf. 42%, p = 0.001).Mortality was high in the cohort (50/149, 34%). Survival of cases post-HLH who underwent transplantation is superior to un-transplanted patients, suggesting adequate HLH control followed by early HSCT is highly beneficial. Mortality was reduced in HSCT recipients versus the un-transplanted group where follow-up data was available (14% compared to 58%).Asymptomatic cases identified through family history/genetic screening may benefit from pre-emptive HSCT, but access and development of robust functional testing are required. High mortality related to HLH remains concerning and emphasises the need for improved molecular characterisation and clinical prognostic factors to guide management decisions.

Multisystem inflammatory syndrome in children (MIS-C) has been reported in patients with inborn errors of immunity (IEI), providing insights into disease pathogenesis. Here, we present the first case of MIS-C in a child affected by Wiskott-Aldrich syndrome (WAS) gene mutation, elucidating underlying predisposing factors and the involved inflammatory pathways. Genetic analysis revealed a frameshift truncating variant in the WAS gene, resulting in WAS protein expression between mild and severe forms, despite a clinical phenotype resembling X-linked thrombocytopenia (XLT). IL-1β secretion by LPS-stimulated peripheral blood mononuclear cells from patient during MIS-C was lower compared to healthy subjects but increased during follow-up. Conversely, the percentage of ASC (apoptosis-associated speck-like protein containing a CARD) specks in the patient's circulating monocytes during the acute phase was higher than in healthy subjects. The type I interferon (IFN) signature during MIS-C was normal, in contrast to the raised IFN signature measured far from the acute event. This case supports the association of IEI with MIS-C, potentially linked to delayed immune responses to SARS-CoV-2. The XLT phenotype underlies a subclinical immunodysregulation involving the NLRP3 inflammasome and the type-I IFN response.

We studied a family with three male individuals across two generations affected by common variable immune deficiency (CVID). We identified a novel missense heterozygous variant (c.2602T>A:p.Y868N) of NFKB2 in all patients and not in healthy relatives. Functional studies of the mutant allele in an overexpression system and of the patients' cells confirmed the deleteriousness of the NFKB2 variant and genotype, respectively, on the activation of the non-canonical NF-κB signaling pathway. Impaired processing of p100 into p52 underlies p100 accumulation, which results in gain-of-function (GOF) of IκBδ inhibitory activity and loss-of-function (LOF) of p52 transcriptional activity. The three patients' plasma contained autoantibodies that neutralized IFN-α2 and/or IFN-ω, accounting for the severe or recurrent viral diseases of the patients, including influenza pneumonia in one sibling, and severe COVID-19 and recurrent herpes labialis in another. Our results confirm that NFKB2 alleles that are IκBδ GOF and p52 LOF can underlie CVID and drive the production of autoantibodies neutralizing type I IFNs, thereby predisposing to severe viral diseases.

Purpose: CTLA4 deficiency is an inborn error of immunity (IEI) due to heterozygosity for germline loss-of-function variants of the CTLA4 gene located on chromosome 2q33.2. CTLA4 deficiency underlies pleiotropic immune and lymphoproliferation-mediated features with incomplete penetrance. It has been identified in hundreds of patients but copy number variants (CNVs) have been reported in only 12 kindreds, including nine which displayed large 2q33.1-2q33.2 deletions encompassing CTLA4.

Methods: We conducted a nationwide study in France to identify patients with 2q33 deletions encompassing CTLA4. We investigated the clinical and immunological phenotypes and genotypes of these patients.

Results: We identified 12 patients across six unrelated kindreds with clinical immunodeficiency. Neurological features were recorded in three patients, including one with syndromic neurodevelopmental disorder. Single-nucleotide polymorphism (SNP) or comparative genomic hybridization (CGH) array analysis, and targeted high-throughput sequencing revealed five different heterozygous 2q33 deletions of 26 kilobases to 7.12 megabases in size and encompassing one to 41 genes. We identified a contiguous gene syndrome (CGS) due to associated KLF7 deficiency in a kindred with a neurodevelopmental phenotype.

Conclusion: Deletions within the 2q33 region encompassing CTLA4 are rare and not extensively explored, and are probably underdiagnosed in cytogenetic practice. A literature review identified 14 different CGS loci including at least one gene responsible for an IEI. The deletions involved in IEIs should be systematically delimited, to facilitate screening for CGS.