Multiple Innate Inflammatory Responses Induced after Systemic Adenovirus Vector Delivery Depend on a Functional Complement System

Abstract

Excessive complement activation can result in extreme tissue damage and systemic inflammatory responses, similar to innate immune responses rapidly elicited after systemic adenovirus (Ad) injections. To determine if Ad interactions with the complement system impact upon Ad-induced innate immune responses, we injected Ad into complement-deficient, C3-knockout mice (C3-KO) or wild-type mice (WT) and quantitatively compared multiple anti-Ad innate immune responses in both strains of mice. In Ad-treated WT mice, we noted rapid increases in plasma KC levels (1 h post injection), followed by increases in IL-6, IFN-gamma, RANTES, IL-12(p40), IL-5, G-CSF, and GM-CSF and subsequently thrombocytopenia. Conversely, in Ad-treated C3-KO mice, many of these inflammatory responses were significantly blunted, including the avoidance of Ad-induced thrombocytopenia. Global liver transcriptome responses in Ad-treated WT mice were assessed by RT-PCR-validated gene array analysis and were found to be also significantly affected by the lack of complement activity in Ad-treated C3-KO mice. Finally, our results confirmed the ability of high dose Ads to transduce hepatocytes despite a lack of complement activity. In summary, Ad interactions with the mammalian complement system are significant and likely initiate and/or exacerbate many of the inflammatory responses noted after systemic Ad injections.

Factors influencing retention of adenovirus within tumours following direct intratumoural injection

“…15,23,[28][29][30][31] Although IT injection of adenovirus vectors should reduce the overall likelihood of inflammatory responses, our data suggest that the use of larger volumes of injectate may give substantial dissemination of virus into the systemic circulation. This might account for the incidences of flu-like symptoms widely reported in clinical trials.…”

“…In addition, drainage of virus into the systemic circulation can trigger the activation of complement and cytokine/chemokine cascades 9,10 increasing the possibility of systemic toxicities. [11][12][13][14][15] Dissemination into the circulation following IT injection has already been reported in both animal studies and clinical trials. [16][17][18] For example Wang et al (2006) 19 explored injecting 20 or 50 ml of adenovirus solution IT, using an infusion rate of 1.0 ml s À1 .…”

Wild-type adenoviruses from groups A–F evoke unique innate immune responses, of which HAd3 and SAd23 are partially complement dependent

“…Furthermore, this study highlights the important role the complement system has in the induction of portions of these serotypespecific toxicities, dependencies originally noted after use of HAd5 vectors. 10 In summary, this study reveals that use of alternative Ad serotypes to address one set of concerns may also precipitate another set of unforeseen problems and/or limitations inherent to each serotype's biology. This knowledge will inform the decision to proceed with a respective virus serotype for use as a gene-transfer vector in diverse gene therapy or vaccine applications…”

“…Our recent publications describe the specific transcriptome profile of Ad-infected mouse embryonic fibroblasts in vitro, and the general transcriptome responses in the livers of Ad-injected C57BL/6 mice in vivo. 9,10,36 The results of these array-based analyses indicated a global induction of host immune response genes, inclusive of several immune response gene networks, such as TLR pathways among others. From these analyses, it became clear that many known innate immunity genes, such as NOD-like receptors and TLRs were induced following Ad injection, and that TLR adaptor proteins, such as MyD88 and TRIF were required in Ad-specific innate immune responses.…”

“…injection of high-titer HAd5-based vectors can cause several innate immune responses and hepatotoxicities, some associated with activation of complement and Toll-like receptor (TLR) pathways. [9][10][11] These responses can include induction of thrombocytopenia, and expression of a spectrum of cytokines and chemokines including interleukin (IL)-1a, IL-6, IL-12, keratinocyte chemoattractant (KC), monocyte chemotactic protein-1 (MCP-1), granulocyte-colony stimulating factor (G-CSF), interferon (IFN)-g, macrophage inflammatory protein-1 (MIP-1)b and RANTES (regulated on activation normal T-cell-expressed and -secreted).…”