Imiquimod suppresses propagation of herpes simplex virus 1 by upregulation of cystatin a via the adenosine receptor A<inf>1</inf>pathway
Imiquimod is recognized as an agonist for Toll-like receptor 7 (TLR7) in immunocompetent cells. TLR7, as well as TLR3 and TLR8, triggers the immune responses, such as the production of type I interferons (IFNs) and proinflammatory cytokines via recognition of viral nucleic acids in the infected cell...
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| Main Authors: | , , , , , |
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| Other Authors: | |
| Format: | Article |
| Published: |
2018
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| Subjects: | |
| Online Access: | https://repository.li.mahidol.ac.th/handle/123456789/13389 |
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| Institution: | Mahidol University |
| Summary: | Imiquimod is recognized as an agonist for Toll-like receptor 7 (TLR7) in immunocompetent cells. TLR7, as well as TLR3 and TLR8, triggers the immune responses, such as the production of type I interferons (IFNs) and proinflammatory cytokines via recognition of viral nucleic acids in the infected cells. In this study, we proposed that imiquimod has an IFN-independent antiviral effect in nonimmune cells. Imiquimod, but not resiquimod, suppressed replication of human herpes simplex virus 1 (HSV-1) in FL cells. We analyzed alternation of gene expression by treatment with imiquimod using microarray analysis. Neither type I IFNs, nor TLRs, nor IFN-inducible antiviral genes were induced in imiquimod-treated FL cells. Cystatin A, a host cysteine protease inhibitor, was strongly upregulated by imiquimod and took a major part in the anti-HSV-1 activity deduced by the suppression experiment using its small interfering RNA. Upregulation of cystatin A was suggested to be mediated by antagonizing adenosine receptor A1 and activating the protein kinase A pathway. Imiquimod, but not resiquimod, was shown to interact with adenosine receptor A1. Imiquimod-induced anti-HSV-1 activity was observed in other cells, such as HeLa, SiHa, and CaSki cells, in a manner consistent with the cystatin A induction by imiquimod. These results indicated that imiquimod acted as an antagonist for adenosine receptor A1 and induced a host antiviral protein, cystatin A. The process occurred independently of TLR7 and type I IFNs. © 2012, American Society for Microbiology. |
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