Development of inhibitory antibodies to therapeutic factor VIII in severe hemophilia A is associated with microsatellite polymorphisms in the HMOX1 promoter

Abstract

Induction of heme oxygenase-1, a stress-inducible enzyme with anti-inflammatory activity, reduces the immunogenicity of therapeutic factor VIII in experimental hemophilia A. In humans, heme oxygenase-1 expression is modulated by polymorphisms in the promoter of the heme oxygenase-1-encoding gene (HMOX1). We investigated the relationship between polymorphisms in the HMOX1 promoter and factor VIII inhibitor development in severe hemophilia A. We performed a case-control study on 99 inhibitor-positive patients and 263 patients who did not develop inhibitors within the first 150 cumulative days of exposure to therapeutic factor VIII. Direct sequencing and DNA fragment analysis were used to study (GT) n polymorphism and single nucleotide polymorphisms located at -1135 and -413 in the promoter of HMOX1. We assessed associations between the individual allele frequencies or genotypes, and inhibitor development. Our results demonstrate that inhibitor-positive patients had a higher frequency of alleles with large (GT) n repeats (L: n≥30), which are associated with lesser heme oxygenase-1 expression (odds ratio 2.31; 95% confidence interval 1. 46-3.66; P<0.001]. Six genotypes (L/L, L/M, L/S, M/M, M/S and S/S) of (GT) n repeats were identified (S: n<21; M: 21≤n<30). The genotype group including L alleles (L/L, L/M and L/S) was statistically more frequent among inhibitor-positive than inhibitor-negative patients, as compared to the other genotypes (33.3% versus 17.1%) (odds ratio 2.21, 95% confidence interval 1.30-3.76; P<0.01). To our knowledge, this is the first association identified between HMOX1 promoter polymorphism and development of anti-drug antibodies. Our study paves the way towards modulation of the endogenous anti-inflammatory machinery of hemophilia patients to reduce the risk of inhibitor development Development of inhibitory antibodies to therapeutic factor VIII in severe hemophilia A is associated with microsatellite polymorphisms in the HMOX1 promoter

Humanized cobra venom factor: Structure, activity, and therapeutic efficacy in preclinical disease models

“…Up to 30% of hemophilia A patients develop antibodies against recombinant human Factor VIII (Ehrenforth et al, 1992;Repesse et al, 2013). We used mice deficient in Factor VIII (Bi et al, 1995;Delignat et al, 2012;Qian et al, 1999) to assess the effect of complement depletion with hCVF protein HC3-1496 on the production on a Human PNH cells were incubated in the presence of rH19-20 with normal human serum or human serum complement-depleted with hCVF or CVF.…”

New predictive approaches for ITI treatment

“…A useful approach, therefore, is to prevent inhibitor development in the first phase of the immune response. Some potential strategies for inhibitor prevention may include : ‘Deimmunization’ of FVIII whereby amino acid residues that serve as contact sites are eliminated. Modification of FVIII domains (i.e. C1) to prevent its uptake by dendritic cells, e.g.…”

FVIII inhibitors: pathogenesis and avoidance

“…22 Thus, the recent report of associations between inhibitor development and polymorphisms in the HMOX-1 gene is of interest and requires further follow-up. 23 Tregs have also been implicated in the process of inducing tolerance in patients with an established memory using immune tolerance induction (ITI) therapy. Here, frequent exposure to the deficient factor in the absence of systemic inflammation may induce Tregs with a subsequent lack of T-helper cells, preventing B-cell differentiation and promoting tolerance through B-cell anergy and/or deletion.…”