Unexpected enhancement of FVIII immunogenicity by endothelial expression in lentivirus-transduced and transgenic mice
Open Access
- 26 May 2020
- journal article
- research article
- Published by American Society of Hematology in Blood Advances
- Vol. 4 (10), 2272-2285
- https://doi.org/10.1182/bloodadvances.2020001468
Abstract
Factor VIII (FVIII) replacement therapy for hemophilia A is complicated by development of inhibitory antibodies (inhibitors) in similar to 30% of patients. Because endothelial cells (ECs) are the primary physiologic expression site, we probed the therapeutic potential of genetically restoring FVIII expression selectively in ECs in hemophilia A mice (FVIIInull). Expression of FVIII was driven by the Tie2 promoter in the context of lentivirus (LV)-mediated in situ transduction (T2F8LV) or embryonic stem cell-mediated transgenesis (T2F8(Tg)). Both endothelial expression approaches were associated with a strikingly robust immune response. Following in situ T2F8LV-mediated EC transduction, all FVIIInull mice developed inhibitors but had no detectable plasma FVIII. In the transgenic approach, the T2F8(Tg) mice had normalized plasma FVIII levels, but showed strong sensitivity to developing an FVIII immune response upon FVIII immunization. A single injection of FVIII with incomplete Freund adjuvant led to high titers of inhibitors and reduction of plasma FVIII to undetectable levels. Because ECs are putative major histocompatibility complex class II (MHCII)-expressing nonhematopoietic, "semiprofessional" antigen-presenting cells (APCs), we asked whether they might directly influence the FVIII immune responses. Imaging and flow cytometric studies confirmed that both murine and human ECs express MHCII and efficiently bind and take up FVIII protein in vitro. Moreover, microvascular ECs preconditioned ex vivo with inflammatory cytokines could functionally present exogenously taken-up FVIII to previously primed CD4(+)/CXCR5(+) T follicular helper (Tfh) cells to drive FVIII-specific proliferation. Our results show an unanticipated immunogenicity of EC-expressed FVIII and suggest a context-dependent role for ECs in the regulation of inhibitors as auxiliary APCs for Tfh cells.This publication has 123 references indexed in Scilit:
- An evolving new paradigm: endothelial cells – conditional innate immune cellsJournal of Hematology & Oncology, 2013
- The Brain Microvascular Endothelium Supports T Cell Proliferation and Has Potential for Alloantigen PresentationPLOS ONE, 2013
- Suppression of the Immune Response to FVIII in Hemophilia A Mice by Transgene Modified Tolerogenic Dendritic CellsMolecular Therapy, 2011
- Human Blood CXCR5+CD4+ T Cells Are Counterparts of T Follicular Cells and Contain Specific Subsets that Differentially Support Antibody SecretionImmunity, 2011
- Targeting FVIII expression to endothelial cells regenerates a releasable pool of FVIII and restores hemostasis in a mouse model of hemophilia ABlood, 2010
- Factor VIII−pulsed dendritic cells reduce anti−factor VIII antibody formation in the hemophilia A mouse modelExperimental Hematology, 2009
- Nanocapsule-delivered Sleeping Beauty mediates therapeutic Factor VIII expression in liver sinusoidal endothelial cells of hemophilia A miceJCI Insight, 2009
- Syngeneic transplantation of hematopoietic stem cells that are genetically modified to express factor VIII in platelets restores hemostasis to hemophilia A mice with preexisting FVIII immunityBlood, 2008
- An antigen-specific pathway for CD8 T cells across the blood-brain barrierThe Journal of Experimental Medicine, 2007
- Factor VIII ectopically targeted to platelets is therapeutic in hemophilia A with high-titer inhibitory antibodiesJCI Insight, 2006