Gut Helminth Infection-Induced Immunotolerance and Consequences for Human Papillomavirus Persistence

Cervical cancer, a malignancy caused by persistent human papillomavirus (HPV) infection, develops in more than 500,000 women annually. More than 90% of deaths from cervical cancer occur in low- and middle-income countries. A common epidemiological feature of countries with high cervical cancer incidence is a high burden of intestinal helminth infection. The ability of intestinal helminths to trigger immunoregulation, resulting in a "tolerogenic" systemic immune environment, provides fertile soil for the persistence of oncogenic viruses such as HPV. Animal models have shown that intestinal helminth infection permits the persistence of some viruses, however, HPV-specific and human studies are lacking. Large, well-organized trials evaluating the consequences of intestinal helminth infection on the human immune system and HPV persistence may lead to improved strategies for HPV prevention in helminth-endemic regions of the world. Additionally, such studies would offer insight into the specific ways that intestinal helminth infection contributes to immunomodulation, which could identify new therapeutic targets for a range of diseases, from inflammatory disorders to cancer. In this review, we discuss the evidence for helminth-induced systemic and local immune dysregulation, discuss possible mechanisms by which chronic intestinal helminth infection may facilitate HPV persistence, and suggest novel helminth-related interventions that could offer a high leverage (if somewhat unconventional) approach to HPV and cervical cancer control in resource-constrained regions.