1010. Interference with the IL-1 Signaling Pathway Significantly Improves the Toxicity Profile of Systemically Applied Adenovirus Vectors
Authors: Dmitry M. Shayakhmetov, Zong-Yi Li, Shaoheng Ni, Andre Lieber
Journal: Molecular Therapy (2004)

Adenovirus vectors (Ad) are the second largest group of viral vectors that are extensively used in clinical trials in the US as prospective therapeutics against numerous inborn and acquired human diseases, including cancer. Most recently, interest in Ad has further expanded due to its potential as a vector for vaccination against life threatening infectious agents such as anthrax. It is currently recognized that manifestations of virus-related systemic toxicity greatly impairs safety and efficacy of Ad vectors. To better understand the molecular mechanisms and primary mediators involved in the initiation of the innate host response toward systemically applied Ad, and to analyze the feasibility of pharmacological management of Ad-mediated toxicity, we administered Ad5-based vectors intravenously into both wild type C57BL/6 and genetically manipulated mice knocked out for specific signaling pathways involved in activating and maintaining an innate immune response. At different times post virus injection, the hepatic mRNAs and plasma levels of different cytokines/chemokines were evaluated using an RNAse protection assay and mouse inflammatory cytometric bead arrays. These analyses revealed that immediately following systemic Ad application, the transcription of IL-1 and MIP-2 genes in the liver was up-regulated more than 30 times over their baseline. Although TNFα gene transcription was slightly up-regulated at 30 min post virus injection, its maximum levels were not reached before 6 h post virus administration. Importantly, although TNFα signaling was clearly involved in the host response toward systemically applied Ad, our data demonstrate that TNF signaling mediates a delayed rather than an immediate response, and that TNFα is not a primary mediator, initiating anti-Ad host inflammatory responses. Thus, pre-injection of wild type mice with anti-TNFα antibody prior to virus administration could neither reduce the levels of immediate IL-1 and MIP-2 gene up-regulation nor alleviate liver pathology seen following Ad administration. Using capsid-modified Ad vectors which have a reduced capacity to transduce liver cells in vivo, we found that the level of MIP-2 gene up-regulation directly correlates with the level of IL-1 gene transcription. Furthermore, we found that in wild type mice, the level of IL-1 gene up-regulation depends on the level of Ad hepatocyte transduction. Interference with IL-1 signaling pathways by pre-injection of mice with anti-IL-1α/β antibody dramatically reduced both the levels of immediate cytokine gene up-regulation and liver damage caused by systemic Ad administration. Importantly, interference with IL-1 signaling pathways did not affect the ability to Ad vectors to efficiently transduce liver cells in vivo. Our data provide new insights into molecular mechanisms involved in host innate immune and inflammatory responses toward systemically applied Ad. They also provide a rational approach for pharmacological management of anti-Ad host responses, allowing for significant improvement of the safety profiles of existing Ad vectors while preserving their gene transfer efficiency.