Fatal cerebral venous sinus thrombosis and thrombocytopenia due to anti-pf4 disorder following adenovirus infection in a 3-year-old boy

Vaccination against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has been crucial in managing the COVID-19 pandemic. In 2021, a rare syndrome characterized by thrombotic events and thrombocytopenia was identified in individuals who received the ChAdOx1 nCoV-19 or the Ad26.COV2.S vaccine, both of which use adenoviral vectors.[1] [2] [3] [4] [5] This syndrome, known as vaccine-induced immune thrombocytopenia and thrombosis (VITT), is linked to high levels of immunoglobulin G (IgG) antibodies targeting platelet factor 4 (PF4), a chemokine released from platelet α-granules.[6] Similar conditions associated with anti-PF4 antibodies include classic heparin-induced thrombocytopenia (HIT), autoimmune HIT (aHIT), and spontaneous HIT.[7] Additionally, prothrombotic, platelet-activating anti-PF4 antibodies not associated with heparin have been identified in a patient with monoclonal gammopathy.[8] These anti-PF4 disorders present with thrombosis and thrombocytopenia following exposure of PF4 to polyanions like DNA, heparin, or polyphosphate.[9] [10] Recently, anti-PF4 antibodies were detected in two individuals who developed a VITT-like syndrome after adenovirus infection, despite not receiving COVID-19 vaccination or heparin treatment.[11] In the meantime, further such cases, some of them with a preceding respiratory infection and positive testing for adenovirus, have been reported (see [Table 1]).[12] [13] [14] Here, we report the case of a 3-year-old boy who developed fatal cerebral venous sinus thrombosis (CVST) and thrombocytopenia several days after an adenovirus infection. Postmortem studies revealed the presence of anti-PF4 antibodies in his serum. This case further confirms the existence of adenovirus-triggered anti-PF4 antibodies, emphasizing the need to study anti-PF4 antibodies in patients with unexplained thrombosis and thrombocytopenia.</p

MIB-1 index is highly significant in CCM compared to age and gender controls (* = p < 0.05; student’s t-test; ccm: cranio-cervical meningioma; lit: literature).

MIB-1 index is highly significant in CCM compared to age and gender controls (* = p < 0.05; student’s t-test; ccm: cranio-cervical meningioma; lit: literature).</p

Pre- and postoperative MRI of craniocervical-menigioma which is operated on by a suboccipital midline approach with left lateral extension.

<p>Axial and sagittal MRI showing distortion and compression of the brain stem. With increasing growth of these lesions a surgical ‘door’ is opened thus allowing to attack the tumor in a less invasive manner. In our experience far lateral approaches with resection of the condyle are rarely, if at all, necessary in meningiomas due to their slow progression accompanied by minor clinical symptoms. But positioning of the patient may be already of great danger as inclination of the head will most likely increase the bending force on the brain stem, especially in large tumors. Therefore intraoperative SSEP and MEP monitoring are mandatory in this surgical area and should run while the patient is brought into the prone position thus minimizing the overall morbidity of this procedure.</p

PrP23-114-interacting proteins identified in the present study that were previously described as interactors of full length PrP.

PrP23-114-interacting proteins identified in the present study that were previously described as interactors of full length PrP.</p

Preparation of PrP23-114 beads.

A. Scheme for generating PrP23-114 beads. The strategy for the preparation of PrP23-114 coupled to amino-PEGA resin is based on two parallel tiers synthesis. On the left branch, the expressed protein ligation scheme for the synthesis of PrP23-114 thioester is depicted. The right tier illustrates the preparation of the cysteine-modified resin. Finally, the PrP23-114 thioester is coupled to the resin by native chemical ligation. B. Purification protocol for the preparation of PrP23-114 thioester. The respective fractions were analyzed by SDS-PAGE and stained with Coomassie Brilliant Blue. Left panel: purification of PrP23-114-MXE-His-CBD. L: E. coli cell lysate; FT: flow through of proteins not bound to the Ni-NTA column; W: wash; F12–F20: proteins eluted with 250 mM imidazole from the Ni-NTA column. Right panel: mesna thiolysis and HPLC purification. The eluted PrP23-114-MXE-His-CBD (E) was incubated with 300 mM mesna for 4 d (t = 4 d) and purified by HPLC. The pooled fractions of the PrP23-114 thioester were used for native chemical ligation.</p

Additional file 1: of Complement 3+-astrocytes are highly abundant in prion diseases, but their abolishment led to an accelerated disease course and early dysregulation of microglia

'Complement 3+-astrocytes are highly abundant in prion diseases, but their abolishment led to an accelerated disease course and early dysregulation of microglia' Supplementary Figures and Table. (DOCX 15895 kb

Scheme to illustrate possible cellular localizations of PrP/N-PrP.

After maturation in the secretory pathway PrPC is localized at the outer leaflet of the plasma membrane (1). During import into the ER PrP may attain a transmembrane topology, designated PrPCtm, with the N-terminus facing the cytosol (2). After an aborted ER import, or after retrograde transport from the ER lumen full length PrP, or C-terminal truncated variants linked to inherited prion diseases in humans, are missorted to the cytosol and/or nucleus (3). The N-terminal domain of neurotoxic GPI-anchored PrP mutants with a deletion of the hydrophobic domain has been described to penetrate the plasma membrane (4). After proteolytic processing of mature PrP (alpha-cleavage) the polybasic motif can mediate internalization of the liberated N-PrP (5). For references see main text.</p

Characterization of N-PrP-interacting proteins.

<p><b>A. Schematic representation of the experimental approach.</b> Parietal cortex samples of a non-AD and an AD brain were dissolved in lysis buffer (25% w/v) homogenized with 25 strikes in a glass douncer, and centrifuged (7,500 x g, 4°C). The supernatant was added to the PrP23-114 beads and incubated overnight at 4°C. As a control, lysates were incubated with cysteine-modified beads. To purify interaction partners, beads were washed extensively in lysis buffer. Finally, beads were pelleted by centrifugation and boiled in SDS buffer. The SDS-soluble fraction was separated by SDS-PAGE and proteins co-purified with the beads were identified by ESI-MS/MS after tryptic in-gel digestion. <b>B. Venn diagram of proteins interacting with PrP23-114 in non-AD and AD brain.</b> The overlap represents PrP23-114-interacting proteins identified in both brain samples.</p

Secretory proteins are enriched in the fraction of PrP23-114-interacting proteins derived from AD brain.

<p>A, B, C. Cellular localization of the N-PrP-interactors identified only in non-AD (A) or only in AD brain (B) or identified in both (C). D. Enrichment of N-PrP-interactors in AD or non-AD brain according to their cellular localization.</p

Brain samples used for the analysis.

<p>Brain samples used for the analysis.</p