Considerations for Use of Recombinant Adenoviral Vectors: Dose Effect on Hepatic Cytochromes P450

Abstract

Recombinant adenovirus (Ad) serotype 5 is a vector commonly used for gene delivery. Although this vector has a natural tropism for the liver, there is a limited understanding of how Ad administration affects one of the primary hepatic processes, drug metabolism. The effects of systemic administration of a model recombinant adenoviral vector on two hepatic cytochrome P450 (P450) enzymes, CYP3A2 and 2C11, were investigated. Sprague-Dawley rats were treated with one of six vector doses, ranging from 5.7 ϫ 10 6 to 5.7 ϫ 10 12 virus particles (vp)/kg. Hepatic P450 protein expression, catalytic activity, and mRNA levels were measured over 14 days. Ad administration (5.7 ϫ 10 10 -5.7 ϫ 10 12 vp/kg) reduced CYP3A2 over the duration of the study. Six hours after administration of 5.7 ϫ 10 12 vp/kg, CYP3A2 activity and mRNA levels were suppressed by 45 and 65%, respectively (P Յ 0.01). This continued throughout the study with levels dropping to 36 and 45% of controls by 14 days, respectively (P Յ 0.01). A similar trend was detected for CYP2C11 within this dosing range. Administration of 5.7 ϫ 10 6 , 5.7 ϫ 10 8 , and 5.7 ϫ 10 9 vp/kg of Ad significantly increased both CYP2C11 protein expression by 86, 71, and 107% and activity 110, 118, and 53%, respectively, above those of animals treated with saline (P Յ 0.01). These results clearly indicate that a single dose of adenovirus significantly alters key drug metabolizing enzymes for an extended period of time and should be investigated further in the context of the design and implementation of clinical trial protocols.

Evaluation of the HC-04 Cell Line as an In Vitro Model for Mechanistic Assessment of Changes in Hepatic Cytochrome P450 3A during Adenovirus Infection

“…1B). When primary hepatocytes from male SpragueDawley rats were infected with different concentrations of the virus, CYP3A4 activity was suppressed to a level similar to that observed in vivo (Callahan et al, 2005b;Fig. 1C).…”

“…To further refine protocols for infection of HC-04 cells and determine if results obtained from this model reflected those reported in vivo (Callahan et al, 2005b(Callahan et al, , 2008aWonganan et al, 2011), cells were infected with various concentrations of AdlacZ. Virus at a MOI of 100 modestly reduced CYP3A activity by 25%, whereas MOIs of 500 and 1000 reduced activity by 48.6 and 53.5%, respectively ( Fig.…”

Integrin Receptors Play a Key Role in the Regulation of Hepatic CYP3A

“…The performance of this rather diverse group of enzymes is also highly sensitive to microbial infection (Croyle, 2009;Gandhi et al, 2012). Although the primary paradigm of the field attributed this effect to the production of interferons, cytokines, and chemokines (Zanger and Schwab, 2013), we found that the expression and function of hepatic CYP3A2 in the rat is suppressed for 14 days after a single dose of a recombinant adenovirus, long after these inflammatory mediators dissipate (Callahan et al, 2005). Additional studies revealed that reducing the immunogenicity of the virus by chemical and physical means did not mitigate this effect (Callahan et al, 2008a).…”

“…During some of the initial studies conducted in our laboratory in which we characterized CYP3A expression and function in the rat (Callahan et al, 2005(Callahan et al, , 2006(Callahan et al, , 2008a, samples of liver tissue were taken and processed for assessment of changes in genes associated with different signal transduction patterns. Samples were taken 4 days after administration of four different live and inactivated recombinant adenovirus vectors: AdlacZ (a first-generation E1/E3 deleted adenovirus serotype 5 virus expressing the Escherichia coli b-galactosidase transgene under the control of a cytomegalovirus promoter), PEGAd (the AdlacZ virus modified by covalent attachment of PEG to the virus capsid, which reduces the immune response to the virus; Croyle et al, 2001Croyle et al, , 2002, HDAd (a third-generation adenovirus in which all elements of the viral genome except the inverted terminal repeats and the packaging signal [C] are removed and which also contains the constitutive androstane receptorgalactosidase transgene; Croyle et al, 2005), and UVAd (the AdlacZ vector inactivated by exposure to UV light; Callahan et al, 2008b).…”

Altered Drug Metabolism and Transport in Pathophysiological Conditions

“…With exceptions of CYP2D6 mRNA and CYP1A2 activity, other major CYPs such as CYP2C9, 2C19, and 3A4 in HCV-infected PXB mice (chimeric mouse with human hepatocytes) were comparable to the non-infected controls (Kikuchi et al, 2010). Recombinant adenovirus injections in Sprague-Dawley rats led to significant down-regulation of renal CYP2E1 and hepatic CYP3A2 and CYP2C11 expression and activity, and induction of CYP4A protein expression (Callahan et al, 2005;Le et al, 2006).…”