Abstract Number: LPB0030
Meeting: ISTH 2021 Congress
Background: This study included two type 3 von Willebrand disease (VWD) index patients (IPs), characterized by a virtual absence of plasma von Willebrand factor (VWF), but due to disparate molecular pathogenic mechanisms. In IP-I, almost no production of VWF mRNA was contributed to the disease pathogenesis, demonstrated by quantitative reverse transcription assay. Whereas, IP-II carried a heterozygous in-frame large deletion of exons 4-34 of the VWF gene, which had a dominant-negative impact on VWF biosynthesis by affecting multimer elongation, confirmed by multimer analysis.
Aims: This study aimed to elucidate the impact of these VWF deficiencies on Weibel-palade bodies (WPBs) formation, trafficking of the WPBs inflammatory factors, and cellular signaling pathways using patient-derived blood outgrowth endothelial cells (BOECs).
Methods: Immunostaining of BOECs and imaging of the cells using an Apotome.2 microscope was conducted to visualize VWF as well as WPBs inflammatory cargos angiopoietin-2 (Ang2) and P-selectin. Moreover, whole-transcriptome RNA-sequencing of the BOECs and Ingenuity Pathway Analysis was done.
Results: The IP-I BOECs were devoid of WPBs, with altered trafficking of the WPBs inflammatory proteins. In IP-II, WPBs were formed but abnormal. Ang2 was mainly accumulated in the nucleus of the IP-II BOECs, showing a complete lack of Ang2/VWF co-localization. The co-localization of VWF/P-selectin in IP-II BOECs was reduced but still detected. The RNA-sequencing of the IP-II BOECs showed an upregulation in genes of the WPBs proteins, e.g. P-selectin, IL-6, IL8, and CXCL1, as well as significant alterations of canonical pathways related to inflammatory responses, extracellular organization, and angiogenesis. While, in IP-I no deviations in the expression of WPBs inflammatory cargos were observed, and changes in cellular canonical pathways were less prominent compared with IP-II.
Conclusions: Different VWF deficiencies may affect WPBs biogenesis and trafficking of the WPBs inflammatory proteins in a different way, which in turn may influence cellular signaling pathways discretely.
To cite this abstract in AMA style:Yadegari H, Jamil MA, Marquardt N, El-Maarri O, Oldenburg J. Investigating Impact of von Willebrand Factor Deficiencies on the Biogenesis of Weibel-Palade Bodies and Endothelial Cells Signaling Pathways [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/investigating-impact-of-von-willebrand-factor-deficiencies-on-the-biogenesis-of-weibel-palade-bodies-and-endothelial-cells-signaling-pathways/. Accessed October 1, 2023.
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