Human papillomavirus type 16 antagonizes IRF6 regulation of IL-1β

Area of Science:

• Immunology
• Virology
• Molecular Biology

Background:

• Oncoviruses like HPV16 evade host immunity.
• The inflammasome pathway and IL-1β cytokine are crucial for innate immune responses against viral infections.
• It remains unclear if HPV16 can activate or evade the inflammasome pathway.

Purpose of the Study:

• To investigate whether HPV16 activates the inflammasome pathway and regulates IL-1β production.
• To elucidate the molecular mechanisms by which HPV16 interferes with IL-1β regulation.

Main Methods:

• Infection of human keratinocytes with HPV16.
• Analysis of IL-1β secretion and transcription.
• Expression of HPV16 early genes and oncoprotein E6.
• siRNA-mediated knockdown of E6.
• Investigation of p53 and IRF6 roles using mutants and ChIP assays.
• Analysis of cervical cancer patient tissues.

Main Results:

• HPV16 infection induced IL-1β secretion in keratinocytes.
• Expression of HPV16 early genes blocked IL-1β transcription.
• HPV oncoprotein E6 inhibited IRF6 transcription, which regulates IL-1β promoter activity.
• p53 was found to regulate IRF6 transcription, and HPV16 abrogated p53 binding to the IRF6 promoter.
• ChIP assays confirmed HPV16's abrogation of p53 binding to the IRF6 promoter in cervical cancer tissues.

Conclusions:

• HPV16 utilizes its oncoprotein E6 to inhibit IRF6 transcription, thereby blocking IL-1β production.
• This E6-mediated inhibition of IRF6 represents an escape strategy for HPV16 to evade host immune responses.
• The findings highlight a critical interplay between oncoviral persistence strategies and host immune regulation centered on IL-1β.