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Lentiviral gene therapy corrects platelet phenotype and function in patients with Wiskott-Aldrich syndrome.

ABSTRACT: BACKGROUND:Thrombocytopenia is a serious issue for all patients with classical Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT) because it causes severe and life-threatening bleeding. Lentiviral gene therapy (GT) for WAS has shown promising results in terms of immune reconstitution. However, despite the reduced severity and frequency of bleeding events, platelet counts remain low in GT-treated patients. OBJECTIVE:We carefully investigated platelet defects in terms of phenotype and function in untreated patients with WAS and assessed the effect of GT treatment on platelet dysfunction. METHODS:We analyzed a cohort of 20 patients with WAS/XLT, 15 of them receiving GT. Platelet phenotype and function were analyzed by using electron microscopy, flow cytometry, and an aggregation assay. Platelet protein composition was assessed before and after GT by means of proteomic profile analysis. RESULTS:We show that platelets from untreated patients with WAS have reduced size, abnormal ultrastructure, and a hyperactivated phenotype at steady state, whereas activation and aggregation responses to agonists are decreased. GT restores platelet size and function early after treatment and reduces the hyperactivated phenotype proportionally to WAS protein expression and length of follow-up. CONCLUSIONS:Our study highlights the coexistence of morphologic and multiple functional defects in platelets lacking WAS protein and demonstrates that GT normalizes the platelet proteomic profile with consequent restoration of platelet ultrastructure and phenotype, which might explain the observed reduction of bleeding episodes after GT. These results are instrumental also from the perspective of a future clinical trial in patients with XLT only presenting with microthrombocytopenia.

SUBMITTER: Sereni L

PROVIDER: S-EPMC6721834 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Lentiviral gene therapy corrects platelet phenotype and function in patients with Wiskott-Aldrich syndrome.

Sereni Lucia L Castiello Maria Carmina MC Di Silvestre Dario D Della Valle Patrizia P Brombin Chiara C Ferrua Francesca F Cicalese Maria Pia MP Pozzi Loris L Migliavacca Maddalena M Bernardo Maria Ester ME Pignata Claudio C Farah Roula R Notarangelo Lucia Dora LD Marcus Nufar N Cattaneo Lorella L Spinelli Marco M Giannelli Stefania S Bosticardo Marita M van Rossem Koen K D'Angelo Armando A Aiuti Alessandro A Mauri Pierluigi P Villa Anna A

The Journal of allergy and clinical immunology 20190327 3

<h4>Background</h4>Thrombocytopenia is a serious issue for all patients with classical Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT) because it causes severe and life-threatening bleeding. Lentiviral gene therapy (GT) for WAS has shown promising results in terms of immune reconstitution. However, despite the reduced severity and frequency of bleeding events, platelet counts remain low in GT-treated patients.<h4>Objective</h4>We carefully investigated platelet defects in term ...[more]

PMID: 30926529

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Project description:BackgroundWiskott-Aldrich syndrome (WAS) is a severe X-linked immunodeficiency characterized by microthrombocytopenia, eczema, recurrent infections, and susceptibility to autoimmunity and lymphomas. Hematopoietic stem cell transplantation is the treatment of choice; however, administration of WAS gene-corrected autologous hematopoietic stem cells has been demonstrated as a feasible alternative therapeutic approach.ObjectiveBecause B-cell homeostasis is perturbed in patients with WAS and restoration of immune competence is one of the main therapeutic goals, we have evaluated reconstitution of the B-cell compartment in 4 patients who received autologous hematopoietic stem cells transduced with lentiviral vector after a reduced-intensity conditioning regimen combined with anti-CD20 administration.MethodsWe evaluated B-cell counts, B-cell subset distribution, B cell-activating factor and immunoglobulin levels, and autoantibody production before and after gene therapy (GT). WAS gene transfer in B cells was assessed by measuring vector copy numbers and expression of Wiskott-Aldrich syndrome protein.ResultsAfter lentiviral vector-mediated GT, the number of transduced B cells progressively increased in the peripheral blood of all patients. Lentiviral vector-transduced progenitor cells were able to repopulate the B-cell compartment with a normal distribution of B-cell subsets both in bone marrow and the periphery, showing a WAS protein expression profile similar to that of healthy donors. In addition, after GT, we observed a normalized frequency of autoimmune-associated CD19(+)CD21(-)CD35(-) and CD21(low) B cells and a reduction in B cell-activating factor levels. Immunoglobulin serum levels and autoantibody production improved in all treated patients.ConclusionsWe provide evidence that lentiviral vector-mediated GT induces transgene expression in the B-cell compartment, resulting in ameliorated B-cell development and functionality and contributing to immunologic improvement in patients with WAS.

Dataset Information

Lentiviral gene therapy corrects platelet phenotype and function in patients with Wiskott-Aldrich syndrome.

Publications

Lentiviral gene therapy corrects platelet phenotype and function in patients with Wiskott-Aldrich syndrome.

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