Browsing by Subject "factor VIII"

Now showing 1 - 3 of 3
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    Cellular stress and coagulation factor production: When more isn’t necessarily better
    (Elsevier, 2023-12) Chen, Zhouji; Herzog, Roland W.; Kaufman, Randal J.; Pediatrics, School of Medicine
    Remarkably, it has been 40 years since the isolation of the 2 genes involved in hemophilia A (HA) and hemophilia B (HB), encoding clotting factor (F) VIII (FVIII) and FIX, respectively. Over the years, these advances led to the development of purified recombinant protein factors that are free of contaminating viruses from human pooled plasma for hemophilia treatments, reducing the morbidity and mortality previously associated with human plasma-derived clotting factors. These discoveries also paved the way for modified factors that have increased plasma half-lives. Importantly, more recent advances have led to the development and Food and Drug Administration approval of a hepatocyte-targeted, adeno-associated viral vector-mediated gene transfer approach for HA and HB. However, major concerns regarding the durability and safety of HA gene therapy remain to be resolved. Compared with FIX, FVIII is a much larger protein that is prone to misfolding and aggregation in the endoplasmic reticulum and is poorly secreted by the mammalian cells. Due to the constraint of the packaging capacity of adeno-associated viral vector, B-domain deleted FVIII rather than the full-length protein is used for HA gene therapy. Like full-length FVIII, B-domain deleted FVIII misfolds and is inefficiently secreted. Its expression in hepatocytes activates the cellular unfolded protein response, which is deleterious for hepatocyte function and survival and has the potential to drive hepatocellular carcinoma. This review is focused on our current understanding of factors limiting FVIII secretion and the potential pathophysiological consequences upon expression in hepatocytes.
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    IL-15 blockade and rapamycin rescue multifactorial loss of factor VIII from AAV-transduced hepatocytes in hemophilia A mice
    (Elsevier, 2022-12-07) Butterfield, John S. S.; Yamada, Kentaro; Bertolini, Thais B.; Syed, Farooq; Kumar, Sandeep R. P.; Li, Xin; Arisa, Sreevani; Piñeros, Annie R.; Tapia, Alejandro; Rogers, Christopher A.; Li, Ning; Rana, Jyoti; Biswas, Moanaro; Terhorst, Cox; Kaufman, Randal J.; de Jong, Ype P.; Herzog, Roland W.; Pediatrics, School of Medicine
    Hepatic adeno-associated viral (AAV) gene transfer has the potential to cure the X-linked bleeding disorder hemophilia A. However, declining therapeutic coagulation factor VIII (FVIII) expression has plagued clinical trials. To assess the mechanistic underpinnings of this loss of FVIII expression, we developed a hemophilia A mouse model that shares key features observed in clinical trials. Following liver-directed AAV8 gene transfer in the presence of rapamycin, initial FVIII protein expression declines over time in the absence of antibody formation. Surprisingly, loss of FVIII protein production occurs despite persistence of transgene and mRNA, suggesting a translational shutdown rather than a loss of transduced hepatocytes. Some of the animals develop ER stress, which may be linked to hepatic inflammatory cytokine expression. FVIII protein expression is preserved by interleukin-15/interleukin-15 receptor blockade, which suppresses CD8+ T and natural killer cell responses. Interestingly, mice with initial FVIII levels >100% of normal had diminishing expression while still under immune suppression. Taken together, our findings of interanimal variability of the response, and the ability of the immune system to shut down transgene expression without utilizing cytolytic or antibody-mediated mechanisms, illustrate the challenges associated with FVIII gene transfer. Our protocols based upon cytokine blockade should help to maintain efficient FVIII expression.
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    The national blueprint for future basic and translational research to understand factor VIII immunogenicity: NHLBI State of the Science Workshop on factor VIII inhibitors
    (Wiley, 2019-07) Meeks, Shannon L.; Herzog, Roland W.; Pediatrics, School of Medicine
    Introduction Inhibitor formation against coagulation factor VIII (FVIII) is an unresolved serious problem in replacement therapy for the X‐linked bleeding disorder haemophilia A. Although FVIII inhibitors have been extensively studied, much of the basic mechanism of this immune response remains to be uncovered. Aim Within the NHLBI State of the Science Workshop on Factor VIII Inhibitors, Working Group 3 identified three scientific priorities for basic and translational research on FVIII inhibitor formation. Methods A larger list of potential areas of research was initially developed as a basis for subsequent prioritization. Each scientific goal was further evaluated based on required effort, potential impact, approach, methods, technologies and models. Results The three priorities include the following: activation signals and immune regulation that shape the response to FVIII (including innate immunity, microbiome, adaptive immunity and regulatory T cell studies in humans); utility of animal models and non‐animal approaches (in silico, genetic, single‐cell/sorted population “omics,” in vitro) to help predict inhibitor formation and identify novel therapeutics; and impact of the source of FVIII, its structure and von Willebrand factor on immunogenicity and tolerance. Conclusions Early interactions between FVIII and the immune system, biomarker development and studies in different patient groups (previously treated or untreated, with or without inhibitor formation, patients undergoing immune tolerance induction or gene therapy) deserve particular emphasis. Finally, linking basic to clinical studies, development of a repository for biospecimens and opportunities for interdisciplinary research training are important components to solving the urgent problem of inhibitor formation.