Sequestration of Adenoviral Vector by Kupffer Cells Leads to a Nonlinear Dose Response of Transduction in Liver

Abstract

Systemic administration of a recombinant adenovirus encoding the human interferon-beta gene (H5.110CMVhIFN-beta) results in transduction of hepatocytes and detectable circulating levels of IFN-beta protein. In preclinical studies in mice, we noticed a distinctly nonlinear dose response, with low levels of virus (1-3 x 10(10) viral particles) yielding barely detectable levels of IFN-beta but with a higher viral dose (1 x 10(11) particles) resulting in disproportionately high IFN-beta levels. Further studies showed that transgene expression levels from low viral doses could be dramatically enhanced by coadministering an unrelated recombinant adenovirus (H5.110CMVlacZ), suggesting that there was a viral dose threshold effect for efficient viral transduction and/or IFN-beta expression. This enhancement of reporter expression by a nonreporter adenovirus, effective upon coadministration, was further enhanced by preadministration of H5.110CMVlacZ (up to 8 h), but was ineffective if the helper virus was administered as little as 5 min after the H5.110CMVhIFN-beta reporter virus. Our data suggest that the reticuloendothelial system plays a role in this threshold effect, such that low doses of virus are efficiently taken up by the RES/Kupffer cells without leading to appreciable transgene expression, whereas high doses saturate these cells and are able to productively transduce hepatocytes. A better understanding of this phenomenon could have an impact on gene therapy clinical trial safety and efficacy.

Antitumor efficacy and tumor-selective replication with a single intravenous injection of OAS403, an oncolytic adenovirus dependent on two prevalent alterations in human cancer

“…At the high dose, there appears to be a loss of gene regulation and unrestricted viral DNA replication in liver. These nonlinear effects on selected parameters in the liver are consistent with a threshold effect, which has been previously reported for intravenously delivered replication-defective adenoviral vectors, 55,56 and suggest that viral activity in the liver plays a role in the observed toxicities.…”

“…The subsequent decrease in liver at 24 hours may reflect Ad elimination by Kupffer cells. 56 While there is a chronic level of Ad maintained in liver for the duration of the study, the kinetics do not suggest that significant Ad DNA replication is taking place in the liver compared to tumors, demonstrating the proofof-concept for systemically delivered tumor-selective oncolytic Ads.…”

Transductional targeting of adenovirus vectors for gene therapy

“…31 Intravenous administration of Ad results in accumulation in the liver, spleen, heart, lung and kidneys of mice, although these tissues may not necessarily be the highest in CAR expression. 32,33 This is true with regard to the liver in particular, which sequesters the majority of systemically administered Ad particles via hepatic macrophage (Kupffer cell) uptake 34 and hepatocyte transduction, 35 leading to Ad-mediated inflammation and liver toxicity. [36][37][38][39] Thus, the nature of Ad-host interactions dictating the fate of systemically applied Ad has come under considerable scrutiny.…”

Gene therapy targeting to tumor endothelium

“…26 It is worth noting that most vectors do not transduce Kupffer cells; hence, analysis of transgene expression gives a very incomplete picture of virus distribution. As toxicities are normally associated with vector particles, rather than transgene expression, this remains an important issue that must be resolved.…”