Induction of immune tolerance to coagulation factor IX antigen by in vivo hepatic gene transfer

Abstract

Gene replacement therapy is an attractive approach for treatment of genetic disease, but may be complicated by the risk of a neutralizing immune response to the therapeutic gene product. There are examples of humoral and cellular immune responses against the transgene product as well as absence of such responses, depending on vector design and the underlying mutation in the dysfunctional gene. It has been unclear, however, whether transgene expression can induce tolerance to the therapeutic antigen. Here, we demonstrate induction of immune tolerance to a secreted human coagulation factor IX (hF.IX) antigen by adeno-associated viral gene transfer to the liver. Tolerized mice showed absence of anti-hF.IX and substantially reduced in vitro T cell responses after immunization with hF.IX in adjuvant. Tolerance induction was antigen specific, affected a broad range of Th cell subsets, and was favored by higher levels of transgene expression as determined by promoter strength, vector dose, and mouse strain. Hepatocyte-derived hF.IX expression induced regulatory CD4 + T cells that can suppress anti-hF.IX formation after adoptive transfer. With a strain-dependent rate of success, tolerance to murine F.IX was induced in mice with a large F.IX gene deletion, supporting the relevance of these data for treatment of hemophilia B and other genetic diseases.

Major role of local immune responses in antibody formation to factor IX in AAV gene transfer

“…20 Hepatic transduced mice failed to form antibody to hF.IX even after challenge with hF.IX protein formulated in complete Freund's adjuvant. After a second challenge with hF.IX in adjuvant, splenocytes from tolerized mice failed to proliferate after in vitro restimulation with hF.IX, while cells from naïve control mice showed hF.IX-specific proliferation after the repeated immunization.…”

“…3,[16][17][18][19] This route of vector administration was found to induce immune tolerance to the F.IX transgene product. 20 Tolerance induction was favored by higher levels of F.IX expression and was associated with induction of regulatory CD4 + T cells that could suppress antibody formation to F.IX after adoptive transfer. 20 Tolerance induction was successful in several inbred strains of mice with different MHC haplotypes and in outbred mice.…”

“…20 Tolerance induction was favored by higher levels of F.IX expression and was associated with induction of regulatory CD4 + T cells that could suppress antibody formation to F.IX after adoptive transfer. 20 Tolerance induction was successful in several inbred strains of mice with different MHC haplotypes and in outbred mice. Here, we provide further evidence that tolerance induction by hepatic gene transfer is associated with absence of T helper cell responses to F.IX, which is dependent on levels of transgene expression.…”

Liver gene therapy: advances and hurdles

“…102 From recent studies using various gene transfer vectors, it seems that the use of liver specific promoters may be an ideal way to achieve efficient gene transfer to the liver in vivo without induction of immune response. 32,46 In that case, infection of antigen-presenting cells does not result in presentation of foreign peptides and impair transgene product-directed immune response. Other effective approaches to prevent immune response against the transduced cells are vector administration in utero and to newborns.…”

“…Recent studies pointed out that these vectors may be tolerogenic to foreign proteins after delivery to the liver. 32 Moreover, they are relatively easy to prepare and clinical trials using this vector type have been performed or are still ongoing. Many studies have shown that AAV vectors are able to transduce hepatocytes for prolonged periods of time in animal models of various sizes.…”