Recombinant adeno-associated virus-mediated alpha-1 antitrypsin gene therapy prevents type I diabetes in NOD mice

Abstract

Type I diabetes results from an autoimmune destruction of the insulin-producing pancreatic b cells. Although the exact immunologic processes underlying this disease are unclear, increasing evidence suggests that immunosuppressive, immunoregulatory and anti-inflammatory agents can interrupt the progression of the disease. Alpha 1 antitrypsin (AAT) is a multifunctional serine proteinase inhibitor (serpin) that also displays a wide range of anti-inflammatory properties. To test the ability of AAT to modulate the development of type I diabetes, we performed a series of investigations involving recombinant adeno-associated virus vector (rAAV)-mediated gene delivery of human alpha-1 antitrypsin (hAAT) to nonobese diabetic (NOD) mice. Recombinant AAV-expressing hAAT (rAAV2-CB-AT) was administered intramuscularly to 4-week-old female NOD mice (1 Â 10 10 i.u./mouse). A single injection of this vector reduced the intensity of insulitis, the levels of insulin autoantibodies, and the frequency of overt type I diabetes (30% (3/10) at 32 weeks of age versus 70% (7/10) in controls). Transgene expression at the injection sites was confirmed by immunostaining. Interestingly, antibodies against hAAT were present in a majority of the vector-injected mice and circulating hAAT was undetectable when assessed 10 weeks postinjection. This study suggests a potential therapeutic role for AAT in preventing type I diabetes as well as the ability of AAV gene therapy-based approaches to ameliorate disease effectively.

Distinct immune responses to transgene products from rAAV1 and rAAV8 vectors

“…However, NOD mice are an exception and provide an excellent opportunity for studies of the immune response. In addition to high susceptibility for autoimmune disease such as type 1 diabetes and Sorgen's syndrome, NOD mice also display elevated immune responsiveness against foreign antigens and transgene products (16,21,22). The lack of immune response to transgene products from rAAV8 in the NOD mouse model strongly suggests that rAAV8 vector could be used in human clinical studies where immune response to transgene product must be avoided.…”

“…However, the host immune response to a transgene product is one of the major hurdles to limit the successes of gene therapy in humans (19). Mingozzi et al have shown that restricted the transgene expression in liver using a liver-specific promoter in rAAV2 vector induced immune tolerance to the transgene product (F.IX) (20,21). Vandenberghe et al showed that AAV8 failed to activate a T-cell response to the AAV8 capsid because the capsid lacks a heparin binding domain (RXXR), which is important for DC transduc- tion (8).…”

Gene Therapy Progress and Prospects: Gene therapy for diabetes mellitus

“…This has been shown to work in rodent models. [2][3][4][5][6][7] This area has been reviewed recently (see Bottino et al 8 ). Briefly, these strategies are aimed at inducing tolerance or hyporesponsiveness to islet autoantigens by either increasing tolerance inducing regulatory T lymphocytes (IL-10 gene therapy 2 ), suppressing reactive T lymphocytes (immunogene therapy using recombinant vaccinia virus expressing glutamic acid decarboxylase 3 or targeting these cells for apoptosis 6 ) or inducing tolerance in target cells (by overexpression of 'suppressor of cytokine signaling-1' 4 or by inducing antigen-presenting cells to express proinsulin, an autoantigen 5 ).…”

Molecular Multitasking in the Airspace

“…Furthermore, abnormal variants of A1AT may themselves have pathogenic effects in the lung, as oxidatively modified or polymerized A1AT activate monocytes or attract neutrophils, respectively (14,15). Another noncanonical function of A1AT is that of apoptosis inhibition, exerted in lung microvascular endothelial cells (16,17) or pancreatic B cells (18). The work of Churg and colleagues expanded the knowledge of the mechanisms by which A1AT may exert other activities beyond neutrophil elastase inhibition (49).…”

“…Bridging molecules, SP-A and -D are also decreased in the lungs of smokers (16), also potentially contributing to the defect. Of note, statins (17) and macrolides (18) were recently reported to enhance phagocytosis. This might help explain their anti-inflammatory properties and provide a mechanism of action to be pursued as therapy for COPD.…”