Spectrum of WAS gene mutations in Vietnamese patients with Wiskott-Aldrich syndrome.

BACKGROUND: WAS gene mutational analysis is crucial to establish a definite diagnosis of Wiskott-Aldrich syndrome (WAS). Data on the genetic background of WAS in Vietnamese patients have not been reported. METHODS: We recruited 97 male, unrelated patients with WAS and analyzed WAS gene mutation using Sanger sequencing technology. RESULTS: We identified 36 distinct hemizygous pathogenic mutations, with 17 novel variants, from 38 patients in the entire cohort (39.2%). The mutational spectrum included 14 missense, 12 indel, five nonsense, four splicing, and one non-stop mutations. Most mutations appear only once, with the exception of c.37C>T (p.R13X) and c.374G>A (p.G125E) each of which occurs twice in unrelated patients. CONCLUSION: Our data enrich the mutational spectrum of the WAS gene and are crucial for understanding the genetic background of WAS and for supporting genetic counseling.

Pan-Cancer Proteomics Analysis Reveals Wiskott-Aldrich Syndrome Protein as a Potential Regulator of Programmed Death-Ligand 1.

The programmed death-ligand 1 (PD-L1) is a key mediator of immunosuppression in the tumor microenvironment. The expression of PD-L1 in cancer cells is useful for the clinical determination of an immune checkpoint blockade (ICB). However, the regulatory mechanism of the PD-L1 abundance remains incompletely understood. Here, we integrated the proteomics of 52 patients with solid tumors and examined immune cell infiltration to reveal PD-L1-related regulatory modules. Wiskott-Aldrich syndrome protein (WASP) was identified as a potential regulator of PD-L1 transcription. In two independent cohorts containing 164 cancer patients, WASP expression was significantly associated with PD-L1. High WASP expression contributed to immunosuppressive cell composition, including cells positive for immune checkpoints (PD1, CTLA4, TIGIT, and TIM3), FoxP3+ Treg cells, and CD163+ tumor-associated macrophages. Overexpression of WASP increased, whereas knockdown of WASP decreased the protein level of PD-L1 in cancer cells without alteration of PD-L1 protein stability. The WASP-mediated cell migration and invasion were markedly attenuated by the silence of PD-L1. Collectively, our data suggest that WASP is a potential regulator of PD-L1 and the WASP/PD-L1 axis is responsible for cell migration and an immunosuppressive microenvironment.

Wiskott Aldrich syndrome protein (WASp)-deficient Th1 cells promote R-loop-driven transcriptional insufficiency and transcription-coupled nucleotide excision repair factor (TC-NER)-driven genome-instability in the pathogenesis of T cell acute lymphoblastic leukemia.

BACKGROUND: T-ALL is an aggressive hematological tumor that develops as the result of a multi-step oncogenic process which causes expansion of hematopoietic progenitors that are primed for T cell development to undergo malignant transformation and growth. Even though first-line therapy has a significant response rate, 40% of adult patients and 20% of pediatric patients will relapse. Therefore, there is an unmet need for treatment for relapsed/refractory T-ALL to develop potential targeted therapies. METHODS: Pediatric T-ALL patient derived T cells were grown under either nonskewingTh0 or Th1-skewing conditions to further process for ChIP-qPCR, RDIP-qPCR and other RT-PCR assays. Endogenous WASp was knocked out using CRISPR-Cas9 and was confirmed using flow cytometry and western blotting. LC-MS/MS was performed to find out proteomic dataset of WASp-interactors generated from Th1-skewed, human primary Th-cells. DNA-damage was assessed by immunofluorescence confocal-imaging and single-cell gel electrophoresis (comet assay). Overexpression of RNaseH1 was also done to restore normal Th1-transcription in WASp-deficient Th1-skewed cells. RESULTS: We discovered that nuclear-WASp is required for suppressing R-loop production (RNA/DNA-hybrids) at Th1-network genes by ribonucleaseH2 (RNH2) and topoisomerase1. Nuclear-WASp is associated with the factors involved in preventing and dissolving R-loops in Th1 cells. In nuclear- WASp-reduced malignant Th1-cells, R-loops accumulate in vivo and are processed into DNA-breaks by transcription-coupled-nucleotide-excision repair (TC-NER). Several epigenetic modifications were also found to be involved at Th1 gene locus which are responsible for active/repressive marks of particular genes. By demonstrating WASp as a physiologic regulator of programmed versus unprogrammed R-loops, we suggest that the transcriptional role of WASp in vivo extends also to prevent transcription-linked DNA damage during malignancy and through modification of epigenetic dysregulations. CONCLUSION: Our findings present a provocative possibility of resetting R-loops as a therapeutic intervention to correct both immune deficiency and malignancy in T-cell acute lymphoblastic leukemia patients and a novel role of WASp in the epigenetic regulation of T helper cell differentiation in T-ALL patients, anticipating WASp's requirement for the suppression of T-ALL progression.

Wiskott-Aldrich syndrome: a study of 577 patients defines the genotype as a biomarker for disease severity and survival.

ABSTRACT: Wiskott-Aldrich syndrome (WAS) is a multifaceted monogenic disorder with a broad disease spectrum and variable disease severity and a variety of treatment options including allogeneic hematopoietic stem cell transplantation (HSCT) and gene therapy (GT). No reliable biomarker exists to predict disease course and outcome for individual patients. A total of 577 patients with a WAS variant from 26 countries and a median follow-up of 8.9 years (range, 0.3-71.1), totaling 6118 patient-years, were included in this international retrospective study. Overall survival (OS) of the cohort (censored at HSCT or GT) was 82% (95% confidence interval, 78-87) at age 15 years and 70% (61-80) at 30 years. The type of variant was predictive of outcome: patients with a missense variant in exons 1 or 2 or with the intronic hot spot variant c.559+5G>A (class I variants) had a 15-year OS of 93% (89-98) and a 30-year OS of 91% (86-97), compared with 71% (62-81) and 48% (34-68) in patients with any other variant (class II; P < .0001). The cumulative incidence rates of disease-related complications such as severe bleeding (P = .007), life-threatening infection (P < .0001), and autoimmunity (P = .004) occurred significantly later in patients with a class I variant. The cumulative incidence of malignancy (P = .6) was not different between classes I and II. It confirms the spectrum of disease severity and quantifies the risk for specific disease-related complications. The class of the variant is a biomarker to predict the outcome for patients with WAS.

Controlled WASp activity regulates the proliferative response for Treg cell differentiation in the thymus.

The Wiskott-Aldrich syndrome protein (WASp) regulates actin cytoskeletal dynamics and function of hematopoietic cells. Mutations in the WAS gene lead to two different syndromes; Wiskott-Aldrich syndrome (WAS) caused by loss-of-function mutations, and X-linked neutropenia (XLN) caused by gain-of-function mutations. We previously showed that WASp-deficient mice have a decreased number of regulatory T (Treg) cells in the thymus and the periphery. We here evaluated the impact of WASp mutations on Treg cells in the thymus of WAS and XLN mouse models. Using in vitro Treg differentiation assays, WAS CD4 single-positive thymocytes have decreased differentiation to Treg cells, despite normal early signaling upon IL-2 and TGF-ß stimulation. They failed to proliferate and express CD25 at high levels, leading to poor survival and a lower number of Foxp3+ Treg cells. Conversely, XLN CD4 single-positive thymocytes efficiently differentiate into Foxp3+ Treg cells following a high proliferative response to IL-2 and TGF-ß, associated with high CD25 expression when compared with WT cells. Altogether, these results show that specific mutations of WASp affect Treg cell development differently, demonstrating a critical role of WASp activity in supporting Treg cell development and expansion.

LncRNA MYLK antisense RNA 1 activates cell division cycle 42/Neutal Wiskott-Aldrich syndrome protein pathway via microRNA-101-5p to accelerate epithelial-to-mesenchymal transition of colon cancer cells.

Long noncoding RNA MYLK antisense RNA 1 (MYLK-AS1) is the crux in multiple diseases. Therefore, the purpose of this study was to investigate the possible mechanism of MYLK-AS1. A total of 62 colon cancer (CC) specimens and paired adjacent normal tissues were collected, and the expression of MYLK-AS1, microRNA (miR)-101-5p/cell division cycle 42 (CDC42) was detected. CC cell lines were transfected with MYLK-AS1, miR-101-5p, CDC42-related plasmids, and the biological functions and markers of epithelial-mesenchymal transition (EMT) were analyzed. The binding relationship between MYLK-AS1, miR-101-5p, and CDC42 was evaluated. In CC tissues and cell lines, MYLK-AS1 and CDC42 were highly expressed, and miR-101-5p was lowly expressed. Inhibition of MYLK-AS1 or upregulation of miR-101-5p can inhibit CC cell growth and EMT. miR-101-5p inhibited CDC42/N-wasp axis activation in CC cells by targeting CDC42. Knockdown of CDC42 or upregulation of miR-101-5p partially reversed the effects caused by upregulation of MYLK-AS1. MYLK-AS1, which is significantly upregulated in CC, may be a molecular sponge for miR-101-5p, and MYLK-AS1 promotes the activation of the CDC42/N-wasp axis in CC cells by targeting CDC42 through miR-101-5p, which in turn promotes tumor development. MYLK-AS1 may be a potential biomarker and target for CC therapy.

Role of Wiskott Aldrich syndrome protein in haematological malignancies: genetics, molecular mechanisms and therapeutic strategies.

As patients continue to suffer from lymphoproliferative and myeloproliferative diseases known as haematopoietic malignancies can affect the bone marrow, blood, lymph nodes, and lymphatic and non-lymphatic organs. Despite advances in the current treatment, there is still a significant challenge for physicians to improve the therapy of HMs. WASp is an important regulator of actin polymerization and the involvement of WASp in transcription is thought to be linked to the DNA damage response and repair. In some studies, severe immunodeficiency and lymphoid malignancy are caused by WASp mutations or the absence of WASp and these mutations in WAS can alter the function and/or expression of the intracellular protein. Loss-of-function and Gain-of-function mutations in WASp have an impact on cancer malignancies' incidence and onset. Recent studies suggest that depending on the clinical or experimental situation, WASPs and WAVEs can operate as a suppressor or enhancers for cancer malignancy. These dual functions of WASPs and WAVEs in cancer likely arose from their multifaceted role in cells that could be targeted for anticancer drug development. The significant role and their association of WASp in Chronic myeloid leukaemia, Juvenile myelomonocytic leukaemia and T-cell lymphoma is discussed. In this review, we described the structure and function of WASp and its family mechanism, analysing major regulatory effectors and summarising the clinical relevance and drugs that specifically target WASp in disease treatment in various hematopoietic malignancies by different approaches.

Association of Wiskott-Aldrich syndrome protein (WASp) in epigenetic regulation of B cell differentiation in non-small-cell lung cancer (NSCLC).

Non-small-cell lung cancer (NSCLC) accounts for approximately 85% of all lung cancer which is the deadliest type of cancer for both men and women. Previous studies already showed that cell-intrinsic loss of WASp causes B cell tolerance and WASp deficiency in T helper (TH) cells is linked to negative effects on cytokine gene transcription necessary for TH1 differentiation. In the current study, we investigated the molecular mechanisms involved in WASp-mediated epigenetic regulation of B cell differentiation during NSCLC. Our ChIP-qPCR data suggest the less percentage enrichment of the B cell differentiating factors (Ikaros, Pax5, PU.1, BATF) and WASp across the WAS gene in the B cells of NSCLC patients in comparison with normal healthy donors and overexpression of WASp showed the reverse effects. WASp-depleted B cells while co-culturing with respective PBMCs isolated from normal healthy donors and NSCLC patients, we observed upregulation of TH2-, TH17-, and Treg-specific cytokines (IL4, ILI7A, IL10) & transcription factors (GATA3, RORC, FOXP3) and downregulation of TH1-specific cytokine (IFNγ) & transcription factor (TBX21). Our study showed that the overexpression of WASp resulted into upregulation of B cell differentiating factors, tumor suppressor protein (p53), histone methylation marker (H3K4me3) with concomitant downregulation of tumor-promoting factors (Notch 1, ß-Catenin, DNAPKcs) and histone deacetylation marker (HDAC2) and increase in percentage cytotoxicity of NSCLC-specific cells (A549). Successful overexpression of WASp not only helps in epigenetic regulation of B cell differentiation but also supports tumor suppression in NSCLC. Thus, WASp can be targeted for therapeutic intervention of NSCLC.

Outcomes of hematopoietic stem cell gene therapy for Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS) is a rare X-linked disorder characterized by combined immunodeficiency, eczema, microthrombocytopenia, autoimmunity, and lymphoid malignancies. Gene therapy (GT) to modify autologous CD34+ cells is an emerging alternative treatment with advantages over standard allogeneic hematopoietic stem cell transplantation for patients who lack well-matched donors, avoiding graft-versus-host-disease. We report the outcomes of a phase 1/2 clinical trial in which 5 patients with severe WAS underwent GT using a self-inactivating lentiviral vector expressing the human WAS complementary DNA under the control of a 1.6-kB fragment of the autologous promoter after busulfan and fludarabine conditioning. All patients were alive and well with sustained multilineage vector gene marking (median follow-up: 7.6 years). Clinical improvement of eczema, infections, and bleeding diathesis was universal. Immune function was consistently improved despite subphysiologic levels of transgenic WAS protein expression. Improvements in platelet count and cytoskeletal function in myeloid cells were most prominent in patients with high vector copy number in the transduced product. Two patients with a history of autoimmunity had flares of autoimmunity after GT, despite similar percentages of WAS protein-expressing cells and gene marking to those without autoimmunity. Patients with flares of autoimmunity demonstrated poor numerical recovery of T cells and regulatory T cells (Tregs), interleukin-10-producing regulatory B cells (Bregs), and transitional B cells. Thus, recovery of the Breg compartment, along with Tregs appears to be protective against development of autoimmunity after GT. These results indicate that clinical and laboratory manifestations of WAS are improved with GT with an acceptable safety profile. This trial is registered at clinicaltrials.gov as #NCT01410825.

[Wiskott-Aldrich syndrome with platelets of normal size and c.295C>T mutation of the WAS gene. Case report]. / Síndrome de Wiskott-Aldrich con plaquetas de tamaño normal y mutación c.295C>T en el gen WAS. Informe de caso.

BACKGROUND: Wiskott-Aldrich syndrome is an Inborn Error of Immunity characterized by thrombocytopenia, small platelets, severe eczema, recurrent infections, tendency to autoimmune diseases and neoplasms. The diagnosis of the syndrome can be difficult, especially when platelets are of normal size. CASE REPORT: A three-year-old male patient was referred to a specialized sector of university hospital for presenting acute otitis media that progressed to sepsis by Haemophilus influenzae. At one month of age, he had been diagnosed with autoimmune thrombocytopenia, and splenectomy was performed at two years of age. During follow-up, three hospitalizations were necessary: an infection by Streptococcus pneumoniae, which progressed to sepsis; one due to exacerbation of eczema, isolating S. epidermidis; another due to fever of undetermined origin. The tests showed normal number of platelets after splenectomy, platelets always with normal size. At age four, tests were performed: IgE 3128 Ku/L; IgA, IgG, and normal anti-polysaccharide antibodies; decreased IgM; decrease CD19, TCD4, naïve T and B; increased TCD8; normal NK. A diagnostic hypothesis of "probable" WAS was made. Genetic research has identified the c.295C>T mutation in the WAS gene. CONCLUSIONS: The case reported expressed a new mutation in the SWA gene, characterized by clinical manifestations of the mild phenotype of Wiskott-Aldrich syndrome, with thrombocytopenia, platelets of normal size, and X-linked inheritance. It is important to establish the early diagnosis and treatment to offer a better quality of life in these patients.

ANTECEDENTES: El síndrome de Wiskott-Aldrich es un error innato de la inmunidad, distinguido por trombocitopenia, plaquetas pequeñas, eccema severo, infecciones recurrentes, y susceptibilidad a enfermedades autoinmunes y neoplasias. El diagnóstico es difícil de establecer, especialmente cuando las plaquetas son de tamaño normal. REPORTE DE CASO: Paciente masculino de 3 años, enviado al Hospital Universitario da Santa Casa de São Paulo, Brasil, por otitis media aguda, con evolución a sepsis por Haemophilus influenzae. Al mes de edad fue diagnosticado con trombocitopenia autoinmune, y a los 2 años se llevó a cabo explenectomía. Durante el seguimiento requirió tres hospitalizaciones: una por infección por Streptococcus pneumoniae, que evolucionó a sepsis; otra por exacerbación de eccema, aislándose S. epidermidis, y la última por fiebre de origen indeterminado. Las pruebas de laboratorio informaron: concentración de plaquetas dentro de los valores de referencia después de la esplenectomía, y de tamaño normal. A los 4 años se efectuaron nuevas pruebas, que reportaron: IgE 3128 kU/L; IgA, IgG y anticuerpos anti-polisacáridos normales; disminución de IgM y de CD19, TCD4, T y B vírgenes; aumento de TCD8; NK normales. Se sospechó el diagnóstico de síndrome de Wiskott-Aldrich. Mediante estudios de genética se identificó la mutación c.295C>T en el gen WAS. CONCLUSIONES: El caso aquí expuesto expresó una nueva mutación en el gen SWA, caracterizado por manifestaciones clínicas de fenotipo leve del síndrome de Wiskott-Aldrich, con trombocitopenia, plaquetas de tamaño normal y herencia ligada al cromosoma X. Es importante establecer el diagnóstico y tratamiento oportunos para ofrecer una mejor calidad de vida en estos pacientes.

A Novel Mutation Leading to Wiskott-Aldrich Syndrome in an Ethiopian Boy: a Case Report and a Review of Literature.

Wiskott-Aldrich syndrome is an X-linked recessive primary immune-deficiency disorder very rarely reported from black African children. A 12-year old boy with recurrent sinopulmonary and diarrheal infections, eczema, thrombocytopenia, and low platelet volume was found by whole genome sequencing to harbor a predicted pathogenic c.1205dupC (p.Pro403Alafs*92) variant of a mutation in the WAS gene - confirming the diagnosis. This case report summarizes his presentation and management and provides a useful summary of the diagnosis and the responsible novel genetic mutation.

Branching out in different directions: Emerging cellular functions for the Arp2/3 complex and WASP-family actin nucleation factors.

The actin cytoskeleton impacts practically every function of a eukaryotic cell. Historically, the best-characterized cytoskeletal activities are in cell morphogenesis, motility, and division. The structural and dynamic properties of the actin cytoskeleton are also crucial for establishing, maintaining, and changing the organization of membrane-bound organelles and other intracellular structures. Such activities are important in nearly all animal cells and tissues, although distinct anatomical regions and physiological systems rely on different regulatory factors. Recent work indicates that the Arp2/3 complex, a broadly expressed actin nucleator, drives actin assembly during several intracellular stress response pathways. These newly described Arp2/3-mediated cytoskeletal rearrangements are coordinated by members of the Wiskott-Aldrich Syndrome Protein (WASP) family of actin nucleation-promoting factors. Thus, the Arp2/3 complex and WASP-family proteins are emerging as crucial players in cytoplasmic and nuclear activities including autophagy, apoptosis, chromatin dynamics, and DNA repair. Characterizations of the functions of the actin assembly machinery in such stress response mechanisms are advancing our understanding of both normal and pathogenic processes, and hold great promise for providing insights into organismal development and interventions for disease.

The proline-rich domain of fission yeast WASp (Wsp1p) interacts with actin filaments and inhibits actin polymerization.

Members of the Wiskott-Aldrich Syndrome protein (WASp) family activate Arp2/3 complex (actin-related proteins 2 and 3 complex) to form actin filament branches. The proline-rich domain (PRD) of WASp contributes to branching nucleation, and the PRD of budding yeast Las17 binds actin filaments [Urbanek AN et al. (2013) Curr Biol 23, 196-203]. Biochemical assays showed the recombinant PRD of fission yeast Schizosaccharomyces pombe Wsp1p binds actin filaments with micromolar affinity. Recombinant PRDs of both Wsp1p and Las17p slowed the elongation of actin filaments by Mg-ATP-actin monomers by half and slowed the spontaneous polymerization of Mg-ATP-actin monomers modestly. The affinity of PRDs of WASp-family proteins for actin filaments is high enough to contribute to the reported stimulation of actin filament branching by Arp2/3 complex.

Not too little, not too much: the impact of mutation types in Wiskott-Aldrich syndrome and RAC2 patients.

Primary immune deficiencies (PIDs) are genetic disorders impacting the appropriate development or functioning of any portion of the immune system. The broad adoption of high-throughput sequencing has driven discovery of new genes as well as expanded phenotypes associated with known genes. Beginning with the identification of WAS mutations in patients with severe Wiskott-Aldrich Syndrome, recognition of WAS mutations in additional patients has revealed phenotypes including isolated thrombocytopenia and X-linked neutropenia. Likewise RAC2 patients present with vastly different phenotypes depending on the mutation-ranging from reticular dysgenesis or severe neutrophil dysfunction with neonatal presentation to later onset common variable immune deficiency. This review examines genotype-phenotype correlations in patients with WAS (Wiskott-Aldrich Syndrome) and RAC2 mutations, highlighting functional protein domains, how mutations alter protein interactions, and how specific mutations can affect isolated functions of the protein leading to disparate phenotypes.

Genome editing for primary immunodeficiencies: A therapeutic perspective on Wiskott-Aldrich syndrome.

Primary immunodeficiency diseases (PIDs) are a group of rare inherited disorders affecting the immune system that can be conventionally treated with allogeneic hematopoietic stem cell transplantation and with experimental autologous gene therapy. With both approaches still facing important challenges, gene editing has recently emerged as a potential valuable alternative for the treatment of genetic disorders and within a relatively short period from its initial development, has already entered some landmark clinical trials aimed at tackling several life-threatening diseases. In this review, we discuss the progress made towards the development of gene editing-based therapeutic strategies for PIDs with a special focus on Wiskott - Aldrich syndrome and outline their main challenges as well as future directions with respect to already established treatments.

Impairment of cytokine production following immunological synapse formation in patients with Wiskott-Aldrich syndrome and leukocyte adhesion deficiency type 1.

T cells following immunological synapse (IS) formation with antigen-presenting cells produce multiple cytokines through T cell receptor, integrin, and costimulatory signaling. Here, we investigated the cytokine profiles following IS formation in response to staphylococcal superantigen exposure in three adolescent patients with classical Wiskott-Aldrich syndrome (WAS) and in one patient with leukocyte adhesion deficiency (LAD) type 1. All WAS patients showed lower Th1 and Th2-skewed cytokine production; similar results were observed in the flow cytometric analysis of IFNγ- and IL-4-producing T cells. The patient with LAD type 1 with somatic mosaicism in 2% of CD8+ T cells showed lower Th1 and Th2 cytokine production than healthy controls. The patients with WAS were susceptible to infections and atopic manifestations, and the patients with LAD type 1 showed cold abscess on their skin, our findings using patient samples provide clinical insights into the mechanisms underlying immunodeficiency related to the symptoms of each disease.

The mouse homolog of the mutant WASp responsible for human X-linked neutropenia renders granulopoiesis ineffective.

Severe congenital neutropenia (SCN) is characterized by severe neutropenia and recurrent critical infections. X-linked neutropenia (XLN) is caused by a gain-of-function mutation in the Wiskott-Aldrich syndrome gene (WAS), the product of which (WASp) is expressed only in blood cells, especially during neutrophil maturation. To investigate the mechanism of neutropenia, we established a novel knock-in mouse line expressing WASp-I292T. WASp-I292T neutrophils exhibited activated (dysregulated) actin polymerization. Although WASp-I292T mice did not recapitulate neutropenia, neutrophil levels were increased in the bone marrow, and extramedullary hematopoiesis was observed. Bone marrow neutrophils from WASp-I292T mice exhibited attenuated transmigration. These abnormalities were associated with downregulation of NFκB and TP53 and faulty activation of their downstream pathways.

Severe antenatal intraventricular hemorrhage in a newborn with WASP pathogenic variant.

Wiskott-Aldrich syndrome (WAS) is a rare X-linked immunodeficiency disorder caused by abnormal expression of the Wiskott-Aldrich syndrome protein due to WAS gene mutation, usually characterized by microthrombocytopenia, eczema, hematological malignancies, recurrent infections, and a high risk of autoimmune complications. In this report, we present a family presenting with severe intrauterine cranial hemorrhage. The family has novel c.1377_1378dup (p.Pro460Hisfs*12) variant of WAS gene. The severe and early onset clinic in the family seems to be related to location of the variant on VCA domain of the WAS protein.