Unexpected enhancement of FVIII immunogenicity by endothelial expression in lentivirus-transduced and transgenic mice. Blood Adv 2020 May 26;4(10):2272-2285
Date
05/27/2020Pubmed ID
32453842Pubmed Central ID
PMC7252558DOI
10.1182/bloodadvances.2020001468Scopus ID
2-s2.0-85086840336 (requires institutional sign-in at Scopus site) 6 CitationsAbstract
Factor VIII (FVIII) replacement therapy for hemophilia A is complicated by development of inhibitory antibodies (inhibitors) in ∼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 (T2F8Tg). 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 T2F8Tg 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.
Author List
Shi Q, Carman CV, Chen Y, Sage PT, Xue F, Liang XM, Gilbert GEAuthor
Qizhen Shi MD, PhD Professor in the Pediatrics department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AnimalsEndothelial Cells
Factor VIII
Hemophilia A
Humans
Lentivirus
Mice
Mice, Transgenic
