The Human Papilloma Virus (HPV) may hide in small spaces on the surface of tonsils and tongues of people unaware of hosting the virus, according to a recent study by University of Rochester Medical Center researchers.
The same strains that cause cervical cancer can lead to head and neck cancers, such as the high risk strains HPV 16 and 18. Current tests can detect HPV before patients develop cervical cancer, but this is not the case for HPV-related head and neck cancers. From those infected, some five percent of cases will develop throat or mouth cancer. This suggests that most immune systems of people with HPV can easily hold back the virus’ infections.
Miller and Reith, co-authors of the report, studied 102 tissue samples with elective tonsillectomies. Of those, five contained HPV and four contained the HPV 16 and 18 strains. Every one of these HPV detections was made in tonsil crypts’ biofilms. For Matthew Miller, Associate Professor of Otolaryngology and Neurosurgery at the University of Rochester the lack of immune system protection for those cases evolving into cancer may be biofilms, thin sheets of bacteria found in tonsils’ surface pockets. It is in these pockets, known as tonsil crypts, where HPV-linked head and neck cancers may start.
The research team considers that tonsils could release HPV during an active infection. It is then when the virus is trapped in the biofilm and protected from an immune system response, only to eventually wait for an opportunity to reinstate an infection or invade the tonsil tissue to develop cancer. This finding is crucial since it identifies a mechanism of HPV to evade the immune system, even in cases where HPV is detectable in the blood. For Miller, this has far-reaching implications for the detection, prevention, and monitoring of HPV-related head and neck cancer types.
The research team will proceed to investigate potential screening and HPV detection tools for mouth and throat, such as an oral rinse. Eventually, their aim is to develop topical antimicrobials to target biofilms and enable immune systems to clear the virus in tonsil crypts. It is the hope that these findings and the development of oral HPV tools will help assess HPV vaccines’ impact and prevent head and neck cancers, which could outnumber cervical cancers by 2020.
Sources:
Rieth KKS, Gill SR, Lott-Limbach AA, Merkley MA, Botero N, Allen PD, Miller MC. Prevalence of High-Risk Human Papillomavirus in Tonsil Tissue in Healthy Adults and Colocalization in Biofilm of Tonsillar Crypts. JAMA Otolaryngol Head Neck Surg. Published online January 25, 2018. doi:10.1001/jamaoto.2017.2916