Disorders of regulatory T cell function in patients with the Wiskott-Aldrich syndrome.

Three patients with the Wiskott-Aldrich syndrome were studied. One of them had no past history of relevant infections. The other two presented different degrees of humoral and cellular immunodeficiency and their T cells in vitro showed a defect in regulatory activity of Ig production in PWM stimulated cultures. This defect was not observed in the third patient. All three had normal numbers of B cells, producing normal amounts of Ig in vitro when co-cultured with normal T cells. It is suggested that the immunoregulatory T cell abnormality might play an important role in the pathogenesis of the humoral immunodeficiency.     

The Wiskott-Aldrich syndrome

The Wiskott-Aldrich syndrome (WAS) is a rare X-linked disorder with variable clinical phenotypes that correlate with the type of mutations in the WAS protein (WASP) gene. WASP, a key regulator of actin polymerization in hematopoietic cells, has 5 well-defined domains that are involved in signaling, cell locomotion, and immune synapse formation. WASP facilitates the nuclear translocation of nuclear factor kappaB and was shown to play an important role in lymphoid development and in the maturation and function of myeloid monocytic cells. Mutations of WASP are located throughout the gene and either inhibit or dysregulate normal WASP function. Analysis of a large patient population demonstrates a phenotype-genotype correlation: classic WAS occurs when WASP is absent, X-linked thrombocytopenia when mutated WASP is expressed, and X-linked neutropenia when missense mutations occur in the Cdc42-binding site. The progress made in dissecting the function of WASP has provided new diagnostic possibilities and has propelled our therapeutic strategies from conservative symptomatic treatment to curative hematopoietic stem cell transplantation and toward gene therapy.     

Molecular biology of the Wiskott-Aldrich syndrome

The Wiskott-Aldrich syndrome (WAS) is an X-linked primary immunodeficiency associated with thrombocytopenia, bloody diarrhea, eczema, recurrent infections, and a high incidence of malignancies. X-linked thrombocytopenia (XLT) is a milder form with predominant platelet abnormalities. Both are caused by mutations of the cytoplasmic WAS protein (WASP). To date, mutations of WASP have been identified in over 340 families and consist of missense and nonsense mutations, deletions and insertions, and splice site mutations. There is a striking correlation between phenotype and genotype. The complex gene product of WASP has multiple functional domains that contribute to actin polymerization, cell motility, intracellular signaling, and apoptosis. Understanding the molecular basis of WAS/XLT not only explains the highly variable clinical phenotype, but also affects the medical management of this serious congenital disorder.     

The in vitro response of peripheral blood lymphocytes from patients with Wiskott-Aldrich syndrome

A comparison of serum immunoglobulin levels in children with Wiskott-Aldrich Syndrotne (WAS) and in children with chronic eczema demonstrated lower IgM, higher IgA and lower IgG concentrations in WAS patients. Seven patients with WAS were studied for in vitro lymphocyte function by phytohaemagglutinin (PHA) stimulation and by one-way mixed cell cultures. Lymphocytes from WAS patients were significantly depressed in their response to PHA when compared with lymphocytes from a control population of children of similar age. In contrast to this, lymphocytes from WAS patients and from their normal siblings and parents responded equally well to mitomycin-blocked homologous cells.     

Wiskott-Aldrich综合征10例临床特点与实验室诊断分析

目的探讨10例Wiskott-Aldrich综合征(WAS)患儿的临床及分子特点。方法总结10例拟诊WAS患儿临床资料,包括血常规、免疫功能、骨髓常规和扫描电镜检查及临床表型评分。流式细胞术(FCM)检测10例患儿外周血单个核细胞(PBMC)中WAS蛋白(WASP)表达。PCR扩增WASP基因序列并直接双向测序分析9例患儿及其亲属突变情况。结果本组均男性,多以自幼大便带血丝及皮肤瘀点瘀斑起病。均有血小板减少伴小血小板,湿疹和免疫缺陷表现。临床表型评分3例评5分,3例评4分,4例评3分。具有阳性家族史患儿临床诊断年龄明显早于无家族史者。多数患儿IgA(8/9)、IgE(8/9)和IgG(7/9)升高,除6例CD4~+T比例下降(6/9),其余患儿淋巴细胞亚群分类正常。1例淋巴细胞增殖功能降低(1/3)。骨髓常规缺乏特征性改变。5例患儿淋巴细胞扫描电镜(SEM)均可见典型微绒毛异常。10例患儿WASP均为阴性,9例行WASP基因分析发现7种不同突变,3例为新型突变(168 C>A,T45 K;747-748 del T,I 238 Fs X260;253 Ins A,C73X)。8例位于编码区,1例位于内含子。4...     

Two novel mutations identified in the Wiskott-Aldrich syndrome protein gene cause Wiskott-Aldrich syndrome and thrombocytopenia

Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT) are rare X-linked genetic disorders caused by mutations of the Wiskott-Aldrich syndrome protein (WASP) gene. Both disorders are clinically characterized by chronic thrombocytopenia of small platelets. WAS is a more severe form of the disorder and also courses with eczema, and immune dysfunction. In the present study, we investigated two novel mutations of the WASP gene in two Spanish families with patients clinically diagnosed as having XLT and WAS, respectively. In one of the families a missense mutation in exon 12 (1488A>G), resulting in the highly conserved glutamic residue changing to glycine at position 485 (D485G), was identified in several members. Notably, a female of this family, with clinical signs of XLT, was determined as the carrier of the mutation and showed a skewed pattern of X-inactivation, preferentially inactivating the X-chromosome carrying the wild-type allele. In the case of the second family, we describe a WAS patient with a single base deletion in exon 2 (266-267delA), resulting in a frameshift (at codon 78) that creates a stop codon at amino acid 127. As a consequence, there was no WASP expression.     

Faecal microbial dysbiosis in children with Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is an X-linked primary immunodeficiency disease caused by a mutation in the WAS gene that encodes the WAS protein (WASp); up to 5-10% of these patients develop inflammatory bowel disease (IBD). The mechanisms by which WASp deficiency causes IBD are unclear. Intestinal microbial dysbiosis and imbalances in host immune responses play important roles in the pathogenesis of polygenetic IBD; however, few studies have conducted detailed examination of the microbial alterations and their relationship with IBD in WAS. Here, we collected faecal samples from 19 children (all less than 2 years old) with WAS and samples from WASp-KO mice with IBD and subjected them to 16S ribosomal RNA sequencing. We found that microbial community richness and structure in WAS children were different from those in controls; WAS children revealed reduced microbial community richness and diversity. Relative abundance of Bacteroidetes and Verrucomicrobiain in WAS children was significantly lower, while that of Proteobacteria was markedly higher. WASp-KO mice revealed a significantly decreased abundance of Firmicutes. Faecal microbial dysbiosis caused by WASp deficiency is similar to that observed for polygenetic IBD, suggesting that WASp may play crucial function in microbial homoeostasis and that microbial dysbiosis may contribute to IBD in WAS. These microbial alterations may be useful targets for monitoring and therapeutically managing intestinal inflammation in WAS.     

Stem-cell gene therapy for the Wiskott-Aldrich syndrome

The Wiskott-Aldrich syndrome (WAS) is an X-linked recessive primary immunodeficiency disorder associated with thrombocytopenia, eczema, and autoimmunity. We treated two patients who had this disorder with a transfusion of autologous, genetically modified hematopoietic stem cells (HSC). We found sustained expression of WAS protein expression in HSC, lymphoid and myeloid cells, and platelets after gene therapy. T and B cells, natural killer (NK) cells, and monocytes were functionally corrected. After treatment, the patients' clinical condition markedly improved, with resolution of hemorrhagic diathesis, eczema, autoimmunity, and predisposition to severe infection. Comprehensive insertion-site analysis showed vector integration that targeted multiple genes controlling growth and immunologic responses in a persistently polyclonal hematopoiesis. (Funded by Deutsche Forschungsgemeinschaft and others; German Clinical Trials Register number, DRKS00000330.).