α-1-antitrypsin gene delivery reduces inflammation, increases T-regulatory cell population size and prevents islet allograft rejection

• Published in: Molecular medicine (Cambridge, Mass.) Vol. 17; no. 9-10; pp. 1000 - 1011
• Main Authors: Shahaf, Galit, Moser, Hadas, Ozeri, Eyal, Mizrahi, Mark, Abecassis, Avishag, Lewis, Eli C
• Format: Journal Article
• Language: English
• Published: England ScholarOne 01-09-2011
• Subjects: alpha 1-Antitrypsin - genetics; alpha 1-Antitrypsin - immunology; alpha 1-Antitrypsin - metabolism; Animals; Blotting, Western; Cell Line; Gene Transfer Techniques; Genetic Therapy - methods; Graft Rejection - genetics; Graft Rejection - metabolism; Graft Rejection - prevention & control; Humans; Immune Sera - immunology; Immune Sera - pharmacology; Inflammation - genetics; Inflammation - metabolism; Inflammation - prevention & control; Islets of Langerhans Transplantation - methods; Lipopolysaccharides - pharmacology; Lymphocyte Count; Macrophages - drug effects; Macrophages - immunology; Macrophages - metabolism; Mice; Mice, Inbred C57BL; Plasmids - genetics; Reverse Transcriptase Polymerase Chain Reaction; T-Lymphocytes, Regulatory - cytology; T-Lymphocytes, Regulatory - immunology; T-Lymphocytes, Regulatory - metabolism; Transplantation, Homologous
• ISSN: 1076-1551; 1528-3658
• DOI: 10.2119/molmed.2011.00145

Antiinflammatory clinical-grade, plasma-derived human α-1 antitrypsin (hAAT) protects islets from allorejection as well as from autoimmune destruction. hAAT also interferes with disease progression in experimental autoimmune encephalomyelitis (EAE) and in collagen-induced arthritis (CIA) mouse models. hAAT increases IL-1 receptor antagonist expression in human mononuclear cells and T-regulatory (Treg) cell population size in animal models. Clinical-grade hAAT contains plasma impurities, multiple hAAT isoforms and various states of inactive hAAT. We thus wished to establish islet-protective activities and effect on Treg cells of plasmid-derived circulating hAAT in whole animals. Islet function was assessed in mice that received allogeneic islet transplants after mice were given hydrodynamic tail-vein injection with pEF-hAAT, a previously described Epstein-Barr virus (EBV) plasmid construct containing the EBV nuclear antigen 1 (EBNA1) and the family of repeat EBNA1 binding site components (designated "EF") alongside the hAAT gene. Sera collected from hAAT-expressing mice were added to lipopolysaccharide (LPS)-stimulated macrophages to assess macrophage responsiveness. Also, maturation of peritoneal cells from hAAT-expressing mice was evaluated. hAAT-expressing mice accepted islet allografts (n = 11), whereas phosphate-buffered saline-injected animals (n = 11), as well as mice treated with truncated-hAAT-plasmid (n = 6) and untreated animals (n = 20) rapidly rejected islet allografts. In hAAT-expressing animals, local Treg cells were abundant at graft sites, and the IL-1 receptor antagonist was elevated in grafts and circulation. Sera from hAAT-expressing mice, but not control mice, inhibited macrophage responses. Finally, peritoneal cells from hAAT-expressing mice exhibited a semimature phenotype. We conclude that plasmid-derived circulating hAAT protects islet allografts from acute rejection, and human plasma impurities are unrelated to islet protection. Future studies may use this in vivo approach to examine the structure-function characteristics of the protective activities of AAT by manipulation of the hAAT plasmid.