Background

Wiskott-Aldrich Syndrome (WAS) is an X-linked immunodeficiency characterized by eczema, infections and susceptibility to develop autoimmunity and malignancies. Thrombocytopenia is a constant finding, but its pathogenesis remains elusive.

Objective

To dissect the basis of WAS platelet (PLT) defect we used a novel conditional mouse model (CoWas) lacking WASp only in the megakaryocytic lineage in presence of a normal immunological environment and in parallel we analysed samples obtained from WAS patients.

Methods

Phenotypical and functional characterization of megakaryocytes and platelets in mutant CoWas mice and WAS patients with and without autoantibodies were performed. Platelet antigen expression was examined through protein expression profile and cluster proteomic interaction network. Platelet immunogenicity was tested by ELISA assays and B and PLTs co-culture.

Results

CoWas displayed increased MK numbers and normal thrombopoiesis in vitro but WASp-deficient PLTs had short lifespan and high expression of activation markers. Proteomic analysis identified signatures compatible with defects in cytoskeletal reorganization and metabolism, yet surprisingly increased antigen-processing capabilities. In addition, WASp-deficient PLTs expressed high levels of surface and soluble CD40L and were capable of inducing B-cell activation in vitro. WASp-deficient PLTs were highly immunostimulatory in mice and triggered the generation of antibodies specific for WASp-deficient PLTs even in the context of a normal immune system. WAS patients also showed PLT hyperactivation and elevated plasma soluble CD40L levels correlating with the presence of auto-antibodies.

Conclusion

Overall, these findings suggest that intrinsic defects in WASp-deficient PLTs decrease their lifespan and dysregulate immune responses, corroborating the role of PLTs as modulators of inflammation and immunity.

中文翻译：

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Wiskott-Aldrich综合征血小板缺乏症在诱导自身免疫和炎症中的自主作用

背景

Wiskott-Aldrich综合征（WAS）是一种X连锁免疫缺陷病，其特征是湿疹，感染和易患自身免疫性疾病和恶性肿瘤。血小板减少症是一个不断发现的疾病，但其发病机理仍然难以捉摸。

客观的

为了剖析WAS血小板（PLT）缺陷的基础，我们使用了在正常免疫环境下仅在巨核细胞谱系中缺乏WASp的新型条件小鼠模型（CoWas），并平行分析了从WAS患者获得的样品。

方法

在突变的CoWas小鼠和有或没有自身抗体的WAS患者中进行了巨核细胞和血小板的表型和功能表征。通过蛋白表达谱和簇蛋白质组学相互作用网络检查血小板抗原的表达。通过ELISA测定以及B和PLT共培养来测试血小板的免疫原性。

结果

CoWas在体外显示出MK数量增加和正常的血小板生成，但WASp缺乏的PLT寿命短且激活标记物高表达。蛋白质组学分析确定了与细胞骨架重组和代谢缺陷兼容的特征，但出人意料地提高了抗原加工能力。另外，WASp缺陷的PLT表达高水平的表面和可溶性CD40L，并能够在体外诱导B细胞活化。缺乏WASp的PLT在小鼠中具有高度的免疫刺激性，即使在正常免疫系统的情况下，也会引发针对WASp缺乏的PLT特异的抗体的产生。WAS患者还显示PLT过度活化和血浆可溶性CD40L水平升高，与自身抗体的存在有关。

结论

总体而言，这些发现表明，缺乏WASp的PLT的固有缺陷会缩短其寿命并调节免疫反应，从而证实PLT作为炎症和免疫调节剂的作用。