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

hHEPATO-Cy5, a Bimodal Tracer for Image-Guided Hepatobiliary Surgery

Liver cancer is a leading cause of cancer deaths worldwide. Surgical resection of superficial hepatic lesions is increasingly guided by the disrupted bile excretion of the fluorescent dye indocyanine green (ICG). To extend this approach to deeper lesions, a dedicated bimodal tracer that facilitates both fluorescence guidance and radioguidance was developed. Methods: A tracer comprising a methylated cyanine-5 (Cy5) fluorescent dye and a mercaptoacetyltriserine chelate (hHEPATO-Cy5) was synthesized and characterized. Cellular uptake and excretion were evaluated in hepatocyte cultures (2-dimensional culture and in vitro lesion model), using a fluorescent bile salt, MitoTracker dye, and methylated Cy5 as a control. After radiolabeling, the pharmacokinetics of 99mTc-hHEPATO-Cy5 were assessed in mice over 24 h (percentage injected dose and percentage injected dose per gram of tissue, SPECT/CT imaging and fluorescence imaging). The ability to provide real-time fluorescence guidance during robot-assisted hepatobiliary surgery was evaluated in a porcine model using ICG as a reference. Results: The unique molecular signature of hHEPATO-Cy5 promotes hepatobiliary excretion. In vitro studies on hepatocytes showed that where methylated Cy5 remained internalized, hHEPATO-Cy5 showed fast clearance (10 min) similar to that of fluorescent bile salt. In vivo use of 99mTc-hHEPATO-Cy5 in mice revealed liver accumulation and rapid biliary clearance. The effectiveness of bile clearance was best exemplified by the 2-orders-of-magnitude reduction in count rate for the gallbladder (P = 0.008) over time. During hepatobiliary surgery in a porcine model, hHEPATO-Cy5 enabled fluorescence-based lesion identification comparable to that of ICG. Conclusion: The bimodal 99mTc-hHEPATO-Cy5 provides an effective means to identify liver lesions. Uniquely, it helps overcome the shortcomings of fluorescence-only approaches by allowing for an extension to in-depth radioguidance.

The Role of Cytochrome P450 Enzymes in COVID-19 Pathogenesis and Therapy

Coronavirus disease 2019 (COVID-19) has become a new public health crisis threatening the world. Dysregulated immune responses are the most striking pathophysiological features of patients with severe COVID-19, which can result in multiple-organ failure and death. The cytochrome P450 (CYP) system is the most important drug metabolizing enzyme family, which plays a significant role in the metabolism of endogenous or exogenous substances. Endogenous CYPs participate in the biosynthesis or catabolism of endogenous substances, including steroids, vitamins, eicosanoids, and fatty acids, whilst xenobiotic CYPs are associated with the metabolism of environmental toxins, drugs, and carcinogens. CYP expression and activity are greatly affected by immune response. However, changes in CYP expression and/or function in COVID-19 and their impact on COVID-19 pathophysiology and the metabolism of therapeutic agents in COVID-19, remain unclear. In this analysis, we review current evidence predominantly in the following areas: firstly, the possible changes in CYP expression and/or function in COVID-19; secondly, the effects of CYPs on the metabolism of arachidonic acid, vitamins, and steroid hormones in COVID-19; and thirdly, the effects of CYPs on the metabolism of therapeutic COVID-19 drugs.

Immunization and Drug Metabolizing Enzymes: Focus on Hepatic Cytochrome P450 3A

OBJECTIVE

Infectious disease emergencies like the 2013-2016 Ebola epidemic and the 2009 influenza and current SARS-CoV-2 pandemics illustrate that vaccines are now given to diverse populations with preexisting pathologies requiring pharmacological management. Many natural biomolecules (steroid hormones, fatty acids, vitamins) and ~60% of prescribed medications are processed by hepatic cytochrome P450 (CYP) 3A4. The objective of this work was to determine the impact of infection and vaccines on drug metabolism.

METHODS

The impact of an adenovirus-based vaccine expressing Ebola glycoprotein (AdEBO) and H1N1 and H3N2 influenza viruses on hepatic CYP 3A4 and associated nuclear receptors was evaluated in human hepatocytes (HC-04 cells) and in mice.

RESULTS

CYP3A activity was suppressed by 55% in mice 24 h after administration of mouse-adapted H1N1, while ˂10% activity remained in HC-04 cells after infection with H1N1 and H3N2 due to global suppression of cellular translation capacity, indicated by reduction (70%, H1N1, 56%, H3N2) of phosphorylated eukaryotic translation initiation factor 4e (eIF4E). AdEBO suppressed CYP3A activity in vivo (44%) and in vitro (26%) 24 hours after infection.

CONCLUSION

As the clinical evaluation of vaccines for SARS-CoV-2 and other global pathogens rise, studies to evaluate the impact of new vaccines and emerging pathogens on CYP3A4 and other metabolic enzymes are warranted to avoid therapeutic failures that could further compromise the public health during infectious disease emergencies.

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

Landmark studies describing the effect of microbial infection on the expression and activity of hepatic CYP3A used bacterial lipopolysaccharide as a model antigen. Our efforts to determine whether these findings were translatable to viral infections led us to observations suggesting that engagement of integrin receptors is key in the initiation of processes responsible for changes in hepatic CYP3A4 during infection and inflammation. Studies outlined in this article were designed to evaluate whether engagement of integrins, receptors commonly used by a variety of microbes to enter cellular targets, is vital in the regulation of CYP3A in the presence and absence of virus infection. Mice infected with a recombinant adenovirus (AdlacZ) experienced a 70% reduction in hepatic CYP3A catalytic activity. Infection with a mutant virus with integrin-binding arginine-glycine-aspartic acid (RGD) sequences deleted from the penton base protein of the virus capsid (AdΔRGD) did not alter CYP3A activity. CYP3A mRNA and protein levels in AdlacZ-treated animals were also suppressed, whereas those of mice given AdΔRGD were not significantly different from uninfected control mice. Silencing of the integrinβ-subunit reverted adenovirus-mediated CYP3A4 suppression in vitro. Silencing of theα-subunit did not. Suppression of integrin subunits had a profound effect on nuclear receptors pregnane X receptor and constitutive androstane receptor, whereas retinoid X receptorαwas largely unaffected. To our knowledge, this is the first time that extracellular receptors, like integrins, have been indicated in the regulation of CYP3A. This finding has several implications owing to the important role of integrins in normal physiologic process and in many disease states.