The role of endosomal escape and mitogen-activated protein kinases in adenoviral activation of the innate immune response

• Published in: PloS one Vol. 6; no. 10; p. e26755
• Main Authors: Smith, Jeffrey S, Xu, Zhili, Tian, Jie, Palmer, Donna J, Ng, Philip, Byrnes, Andrew P
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 27.10.2011; Public Library of Science (PLoS)
• Subjects: Adenoviridae - genetics; Adenoviruses; Animals; Biology; Chemokines; Chemokines - metabolism; Cystic fibrosis; Cytokines; Cytokines - metabolism; Endosomes - metabolism; Expression vectors; Extracellular signal-regulated kinase; Food; Gene therapy; Genes; Genetic Vectors - administration & dosage; Genetic Vectors - immunology; Immune response; Immune system; Immunity, Innate; Inhibitors; Innate immunity; Kinases; Liver diseases; MAP kinase; MAP Kinase Signaling System; Medicine; Metabolic pathways; Mice; Mitogen-Activated Protein Kinases; Mitogens; p38 Mitogen-Activated Protein Kinases - metabolism; Pathogens; Pathways; Phosphorylation; Protein kinases; Signal transduction; Signaling; Transgenes; Viral infections; Virions; United States > US; Maryland; Texas
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0026755

Adenoviral vectors (AdV) activate multiple signaling pathways associated with innate immune responses, including mitogen-activated protein kinases (MAPKs). In this study, we investigated how systemically-injected AdVs activate two MAPK pathways (p38 and ERK) and the contribution of these kinases to AdV-induced cytokine and chemokine responses in mice. Mice were injected intravenously either with a helper-dependent Ad2 vector that does not express viral genes or transgenes, or with the Ad2 mutant ts1, which is defective in endosomal escape. We found that AdV induced rapid phosphorylation of p38 and ERK as well as a significant cytokine response, but ts1 failed to activate p38 or ERK and induced only a limited cytokine response. These results demonstrate that endosomal escape of virions is a critical step in the induction of these innate pathways and responses. We then examined the roles of p38 and ERK pathways in the innate cytokine response by administering specific kinase inhibitors to mice prior to AdV. The cytokine and chemokine response to AdV was only modestly suppressed by a p38 inhibitor, while an ERK inhibitor has mixed effects, lowering some cytokines and elevating others. Thus, even though p38 and ERK are rapidly activated after i.v. injection of AdV, cytokine and chemokine responses are mostly independent of these kinases.