Human papillomavirus (HPV) infection is the most common sexually transmitted disease. HPV causes more than 5% of all human cancers and claims more than 270,000 women?s lives from cervical cancer worldwide annually. Intriguingly, despite the development of three protective HPV vaccines to HPV related cancers, HPV-associated oropharyngeal cancers are becoming increasingly prevalent in patients, particularly in white men in developed countries. Marijuana (cannabis) usage has been linked to HPV-associated oropharyngeal cancers in some studies. Currently, about 1 in 16 youths in the U.S. is reported to use cannabis daily, and nine states and the District of Columbia have legalized marijuana for recreational use since April 2018. Whether cannabis use is associated with increasing HPV-associated oropharyngeal cancers remains unclear and is difficult to study in humans due to the complexities associated with controlling variables in these studies. Over the past five years, we and others have accumulated a significant published and unpublished data set to support the relevance of our newly established mouse papillomavirus (MmuPV1) model to study HPV-associated oropharyngeal cancer. Our long term goal is to use this unique model to explore clinically relevant questions regarding the biology of papillomavirus infections, and to elucidate the critical mechanisms of HPV-associated oropharyngeal cancer. We have developed in vitro and in vivo assays to conduct virological, immunological and histological analyses, and have used our Toponome Imaging System (TIS), the first robotic imaging machine in the US, to characterize innate immune cell landscapes in the MmuPV1- infected vs non-infected tissues. These preliminary studies have positioned us well to accomplish the proposed studies. We hypothesize that marijuana, via one or both of its two major psychoactive ingredients ?9- tetrahydocannabinol (THC) and cannabidiol (CBD), promotes viral persistence in the circumvallate papilla (CVP) and adjacent Von Ebners (VE) glands in the oropharyngeal mucosae.
In Specific Aim 1, we will define the role of chronic marijuana smoke (up to 36 weeks post viral infection) in viral persistence at the oropharyngeal mucosae.
In Specific Aim 2, we will determine the role of the two major psychoactive ingredients of marijuana (up to 36 weeks post viral infection) in viral persistence at the oropharyngeal mucosae. These studies will allow us to establish whether the oropharyngeal mucosae are more susceptible to papillomavirus infections when chronic marijuana smoke or its two major psychoactive ingredients (THC and/or CBD) are administered. This represents a key knowledge gap in HPV-associated oropharyngeal disease and cancer. Furthermore these studies will allow us to determine whether males are preferentially impacted, as has been noted in humans.
We are planning to investigate the role of chronic marijuana smoke as well as its two major psychoactive ingredients ?9-tetrahydocannabinol (THC) and Cannabidiol (CBD) in papillomavirus-associated infection and persistence in the CVP and associated VE glands of the oropharyngeal mucosae using our newly developed mouse papillomavirus oral infection model.
