Downregulation of CD40 Signal and Induction of TGF-β by Phosphatidylinositol Mediates Reduction in Immunogenicity Against Recombinant Human Factor VIII

Abstract

Factor VIII (FVIII) is an important coagulation cofactor and its deficiency causes Hemophilia A, a bleeding disorder. Replacement therapy using recombinant FVIII is currently the first line of therapy for Hemophilia A, but the development of neutralizing antibody is a major clinical complication for this therapy. Recently, it has been shown that FVIII associated with Phosphatidylinositol (PI) containing lipidic nanoparticles reduced development of neutralizing antibodies in Hemophilia A mice (1). Here, we investigated the underlying mechanism of this reduction in antibody response in culturing conditions. In vitro, PI interfered with the processing of FVIII by cultured dendritic cells, resulting in a reduction in the up-regulation of phenotypic co-stimulatory signal CD40. Furthermore, PI increased secretion of regulatory cytokines Transforming Growth Factor beta1 (TGF-β1) and Interleukin 10 (IL-10) but reduced the secretion of pro-inflammatory cytokines IL-6 and IL-17. The data suggests that PI reduces the immunogenicity of FVIII by modulating DC maturation and by secretion of regulatory cytokines.

The polygenic nature of inhibitors in hemophilia A: results from the Hemophilia Inhibitor Genetics Study (HIGS) Combined Cohort

“…22 Again, the present analysis has not considered treatment-related factors, which may in some cases modulate the inhibitor risk. The SNPs located in immunoregulatory genes previously associated with inhibitor risk in independent cohorts [6][7][8][9][10][11][12] were not consistently associated with risk in this investigation and in the meta-analysis combining all 3 cohorts. Among these previously described candidates, the SNP at location Ϫ1082A/G in the promoter region of IL-10 is the most frequently reported finding.…”

“…Indeed, genetic markers have been reported, independent of the type of F8 mutation, such as single nucleotide polymorphisms (SNPs) in the genes coding for IL-1, IL-2, IL-10, TNFA, TGF␤, and CTLA-4. [6][7][8][9][10][11][12] Because several of the SNPs characterized in immunoregulatory molecules coded by the human genome will influence the level of immune modulators, immune system challenges in conjunction with replacement therapy and a genetic predisposition might interact. This is supported by the observations of brother pairs and monozygotic twins with discordant inhibitor status 5 and the formation of inhibitors in association with significant inflammatory reactions among patients considered to be at low risk.…”

PEGylation of a Factor VIII–Phosphatidylinositol Complex: Pharmacokinetics and Immunogenicity in Hemophilia A Mice

“…Additionally, PEG may shield PI and thus negate the immunoregulatory effects of PI. Recently, we showed that PI can downregulate the expression of costimulatory signals in antigen presenting cells (APCs), suppress T cell activation, and increase the secretion of regulatory cytokines such as TGF-beta (57). Further, after intravenous administration, liposomes are in direct contact with the spleen, promoting exposure to B cells.…”

FVIII inhibitors: pathogenesis and avoidance

“…These are summarized in Table 1. [40][41][42][43][44][45][46][47][48][49][50][51][52] Based on current understanding, it seems unlikely that a single marker of significantly greater importance than multiple others will be identified. In fact, the associations found between polymorphic genes and inhibitory antibodies have not been consistent across study cohorts, and the question, of course, is why?…”