The superior role of coagulation factor FX over FVII in adenoviral-mediated innate immune induction of the hepatocyte: an in vitro experiment

Adenovirus vector-attributed hepatotoxicity blocks clinical application in gene therapy

Adenoviruses (Ads), common self-limiting pathogens in humans and animals, usually cause conjunctivitis, mild upper respiratory tract infection or gastroenteritis in humans and hepatotoxicity syndrome in chickens and dogs, posing great threats to public health and livestock husbandry. Artificially modified Ads, which wipe out virulence-determining genes, are the most frequently used viral vectors in gene therapy, and some Ad vector (AdV)-related medicines and vaccines have been licensed and applied. Inherent liver tropism enables AdVs to specifically deliver drugs/genes to the liver; however, AdVs are closely associated with acute hepatotoxicity in immunocompromised individuals, and the side effects of AdVs, which stimulate a strong inflammatory reaction in the liver and cause acute hepatotoxicity, have largely limited clinical application. Therefore, this review systematically elucidates the intimate relationship between AdVs and hepatotoxicity in terms of virus and host and precisely illustrates the accumulated understanding in this field over the past decades. This review demonstrates the liver tropism of AdVs and molecular mechanism of AdV-induced hepatotoxicity and looks at the studies on AdV-mediated animal hepatotoxicity, which will undoubtedly deepen the understanding of AdV-caused liver injury and be of benefit in the further safe development of AdVs.

The Inflammatory and Fibrotic Patterns of Hepatic Stellate Cells Following Coagulation Factors (VII or X)-Shielded Adenovirus Infection

The role of coagulation factors on the inflammatory effect of adenovirus (Ad) is an unresolved question that was considered herein. Adenovirus-36(Ad36) and adenovector-5-GFP(Ad5-GFP) were prepared; then, they were loaded with VII or FX factors. The size/charge parameters and transduction efficiency were evaluated using fluorescent microscopy and Zetasizer, respectively. The Ad36-coagulation factor complexes were added on the stellate cells, LX-2. Thereafter, the expression levels of inflammatory and fibrotic genes including PKR, IL-1β, TNF-α, TIMP-1, collagen, and TGF-β were measured by qPCR and ELISA assays. The loading of FVII or FX factors not only increased the size/charge of Ad5-GFP but also enhanced the transduction rate up to 60% and 75%, respectively, compared to the controls (45%). The PKR expression analysis showed an upregulation following treatment with all Ad36 forms (P = 0.0152). The IL-1β and TNF-α cytokines analyses demonstrated that the Ad36-FVII complex elicited the highest inflammatory response (P = 0.05). Similarly, the fibrosis-related expression analysis revealed a more inductive role of FVII when loaded on Ad36, compared to the FX factor. The findings suggested that adenovirus elicited the innate inflammatory and activation state in the hepatic stellate cell. In addition, adenovirus shielded by FVII exhibited more innate inflammation as well as activation of the stellate cells than the FX-loaded virus.