TLR9 Expression and Function Is Abolished by the Cervical Cancer-Associated Human Papillomavirus Type 16

Cervical cancer development is linked to the persistent infection by high-risk mucosal human papillomaviruses (HPVs) types. The E6 and E7 major oncoproteins from this dsDNA virus play a key role in the deregulation of the cell cycle, apoptosis, and adaptive immune surveillance. In this study, we sho...

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Bibliographic Details
Published in:Journal of Immunology 2007-03, Vol.178 (5), p.3186-3197
Main Authors: Hasan, Uzma A, Bates, Elizabeth, Takeshita, Fumihiko, Biliato, Alexandra, Accardi, Rosita, Bouvard, Veronique, Mansour, Mariam, Vincent, Isabelle, Gissmann, Lutz, Iftner, Thomas, Sideri, Mario, Stubenrauch, Frank, Tommasino, Massimo
Format: Article
Language:English
Subjects:
Cell Transformation, Neoplastic - immunology
Cell Transformation, Neoplastic - metabolism
Cell Transformation, Neoplastic - pathology
Down-Regulation - immunology
Female
HeLa Cells
Human papillomavirus 16
Human papillomavirus 16 - immunology
Human papillomavirus 16 - metabolism
Human papillomavirus 18 - immunology
Human papillomavirus 18 - metabolism
Humans
Immunity, Innate
Oncogene Proteins, Viral - immunology
Oncogene Proteins, Viral - metabolism
Papillomavirus E7 Proteins
Papillomavirus Infections - immunology
Papillomavirus Infections - metabolism
Papillomavirus Infections - pathology
Repressor Proteins - immunology
Repressor Proteins - metabolism
Retrovirus
Toll-Like Receptor 9 - biosynthesis
Toll-Like Receptor 9 - immunology
Transcription, Genetic - immunology
Uterine Cervical Neoplasms - immunology
Uterine Cervical Neoplasms - metabolism
Uterine Cervical Neoplasms - pathology
Uterine Cervical Neoplasms - virology
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Summary:Cervical cancer development is linked to the persistent infection by high-risk mucosal human papillomaviruses (HPVs) types. The E6 and E7 major oncoproteins from this dsDNA virus play a key role in the deregulation of the cell cycle, apoptosis, and adaptive immune surveillance. In this study, we show for the first time that HPV type 16 (HPV16), the most carcinogenic type among the high-risk subgroup, interferes with innate immunity by affecting the expression of TLRs. Infection of human primary keratinocytes with HPV16 E6 and E7 recombinant retroviruses inhibits TLR9 transcription and hence functional loss of TLR9-regulated pathways. Similar findings were achieved in HPV16-positive cancer-derived cell lines and primary cervical cancers, demonstrating that this event occurs also in an in vivo context. Interestingly, E6 and E7 from the low-risk HPV type 6 are unable to down-regulate the TLR9 promoter. In addition, E6 and E7 from the high-risk HPV type 18, which are known to persist less competently in the host than HPV16, have reduced efficiency compared with HPV16 in inhibiting TLR9 transcription. Furthermore, a CpG motif derived from the HPV16 E6 DNA sequence activated TLR9, indicating this virus is able to initiate innate responses via the receptor it later down-regulates. This study reveals a novel mechanism used by HPV16 to suppress the host immune response by deregulating the TLR9 transcript, providing evidence that abolishing innate responses may be a crucial step involved in the carcinogenic events mediated by HPVs.
ISSN:0022-1767
1550-6606
1365-2567
DOI:10.4049/jimmunol.178.5.3186