Immunomodulatory gene therapy prevents antibody formation and lethal hypersensitivity reactions in murine pompe disease

Infantile Pompe disease progresses to a lethal cardiomyopathy in absence of effective treatment. Enzyme-replacement therapy (ERT) with recombinant human acid alpha-glucosidase (rhGAA) has been effective in most patients with Pompe disease, but efficacy was reduced by high-titer antibody responses. Immunomodulatory gene therapy with a low dose adeno-associated virus (AAV) vector (2 x 10(10) particles) containing a liver-specific regulatory cassette significantly lowered immunoglobin G (IgG), IgG1, and IgE antibodies to GAA in Pompe disease mice, when compared with mock-treated mice (P < 0.05). AAV-LSPhGAApA had the same effect on GAA-antibody production whether it was given prior to, following, or simultaneously with the initial GAA injection. Mice given AAV-LSPhGAApA had significantly less decrease in body temperature (P < 0.001) and lower anaphylactic scores (P < 0.01) following the GAA challenge. Mouse mast cell protease-1 (MMCP-1) followed the pattern associated with hypersensitivity reactions (P < 0.05). Regulatory T cells (Treg) were demonstrated to play a role in the tolerance induced by gene therapy as depletion of Treg led to an increase in GAA-specific IgG (P < 0.001). Treg depleted mice were challenged with GAA and had significantly stronger allergic reactions than mice given gene therapy without subsequent Treg depletion (temperature: P < 0.01; symptoms: P < 0.05). Ubiquitous GAA expression failed to prevent antibody formation. Thus, immunomodulatory gene therapy could provide adjunctive therapy in lysosomal storage disorders treated by enzyme replacement.

Expression, purification, and refolding of mouse islet neogenesis associated protein-related protein for NMR studies

Islet neogenesis associated protein-related protein (INGAPrP) is thought to be involved in the differentiation of non-insulin-producing cells to insulin-secreting cells. INGAPrP is a mouse gene product that has a 72% identical amino acid sequence to a known islet-generating factor, hamster islet-neogenesis-associated protein (INGAP), which acts by differentiating pancreatic ductal cells into beta-cells. The three-dimensional structure of these proteins is unknown. The structure would provide information about the conformation of the active portion of INGAP, the so-called INGAP pentadecapeptide, leading to a well-defined target for rational drug design. An efficient procedure for the production of INGAPrP would facilitate the process of structure determination. We have successfully produced and isolated (15)N-labeled INGAPrP by expression in Escherichia coli Rosetta (DE3) cells in Spectra-9 media followed by a two-step purification and refolding protocol. The hexahistidine tag engineered at the N-terminus of the protein is used in the first step for standard immobilized-metal affinity chromatography purification under denaturing conditions. The secondary purification step utilizes a gel permeation chromatography column, producing homogeneous INGAPrP as well as refolding the protein. To verify that the protein was folded, we performed a (1)H-(15)N HSQC NMR experiment that showed excellent dispersion of signals, indicative of a folded protein. We also performed circular dichroism experiments, which demonstrated the presence of secondary structure. In summary, we report the first expression and isolation of INGAPrP, as well as demonstrate that our method produces a folded protein, which is necessary for structure determination.