Biological Sciences, School of
First Advisor
Peter Angeletti
Date of this Version
4-24-2020
Document Type
Thesis
Citation
Klein, C. (2020). The Relationship Between the Cervical Microbiome and Cervical Cancer Risk in Sub-Saharan Africa.
Abstract
Despite ongoing efforts, sub-Saharan Africa faces a higher cervical cancer burden than anywhere else in the world. Besides HPV infection, definitive factors of cervical cancer are still unclear. Dysbiosis of the cervicovaginal microbiota, particularly involving sexually transmitted infections, is associated with increased cervical cancer risk. Notably, HIV infection, which is prevalent in sub-Saharan Africa, greatly increases risk of cervicovaginal dysbiosis and cervical cancer. To better understand and address cervical cancer in sub-Saharan Africa, a better understanding of the regional cervicovaginal microbiome is required. In this study, I establish the relationship between cervical cancer, HPV, HIV, cervicovaginal infections, and the cervicovaginal microbiome in sub-Saharan Africa.
To investigate the role of the bacterial microbiome in cervical dysplasia, cytobrush samples were collected directly from cervical lesions of 144 Tanzanian women and analyzed using 16s metagenomic sequencing. I found that cervical microbiota varied significantly depending on HIV infection, HPV infection, and the presence of cervical lesions. The bacterial family ‘Mycoplasmataceae’ in particular was associated with the presence of pre-cancerous cervical lesions.
Mycoplasmataceae infection in sub-Saharan Africa is not well understood, especially when considering the differences between sexually transmitted species. To establish the prevalence of common Mycoplasmataceae cervical infections and evaluate their relationship with risk factors for cervical cancer, a cohort of 1160 Tanzanian women responded to an epidemiological questionnaire and were tested for HIV, HPV, cervical lesions, Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma spp., and Lactobacillus iners. I found that Mycoplasmataceae infection was present in 66% of women tested. In particular, Mycoplasma hominis was associated with HPV and HIV infection, and significantly increased in relative abundance among women with pre-cancerous cervical lesions.
The results of this study suggest that intracellular, inflammatory infections like M. hominis are prevalent and relate to the development of pre-cancerous cervical lesions. The prevalence of cervical cancer in sub-Saharan Africa may be partially attributed to the high prevalence of cervical infections like M. hominis.
Advisor: Peter C. Angeletti
Comments
A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Biological Sciences (Genetics, Cellular, and Molecular Biology), Under the Supervision of Professor Peter C. Angeletti. Lincoln, Nebraska: May, 2020
Copyright 2020 Cameron G. Klein