Host-pathogen-microbiome interactions in Mycoplasma genitalium infection, pathology, and treatment: experiments in a 3D organotypic cervical epithelium model to strengthen clinical guidelines

About This Grant

Mycoplasma genitalium (MG) is an emerging sexually transmitted pathogen whose clinical outcomes in women are poorly understood. Unlike Chlamydia trachomatis (CT), the CDC does not recommend MG screening for asymptomatic women because it is unclear how often asymptomatic MG leads to adverse reproductive outcomes like cervicitis, which can lead to further adverse outcomes, including pelvic inflammatory disease and infertility. Epidemiologic data on MG and cervicitis are mixed, and mechanistic data primarily come from models that did not faithfully recapitulate in vivo cervical conditions. Key elements they lacked are the cervicovaginal microbiota and sexually transmitted co-infections, which appear to contribute to MG outcomes. MG-CT co-infection is common, and my preliminary epidemiologic data indicate that (1) multi-way interactions of MG, CT, and bacterial vaginosis (BV) likely contribute to infection progression and persistence, and (2) MG and BV may synergize to promote cervicitis. MG care is complicated by its ongoing rise in antibiotic resistance, but recent clinical and in vitro data indicate two antibiotics used to treat BV, metronidazole and tinidazole, may hold promise for improving MG treatment outcomes. The overall objective of this K01 is to generate robust experimental data to clarify MG pathology, evaluate potential therapies, and inform more thorough and actionable clinical recommendations. Dr. Jacques Ravel, my primary K01 mentor, developed an in vitro 3D organotypic model of the cervical epithelium that is ideally suited for investigating MG pathology, host-microbiota-pathogen interactions, and potential therapies. The model uses primary human cervical cells and better recapitulates cervical epithelial structure and physiology than prior 2D models. It also allows for co-culture of live vaginal bacterial communities and sexually transmitted co-infection. Using the 3D organotypic cervical epithelium model, I will determine if MG causes microbiota-dependent cervical epithelial damage, a hallmark of cervicitis (Aim 1); compare infection progression and host-pathogen interactions of MG and CT mono- and co-infections (Aim 2); and test if metronidazole and tinidazole arrest MG infection (Aim 3). I will interrogate the potential mediating role of the cervicovaginal microbiota by exposing models to supernatants from representative vaginal bacterial cultures (Aims 1, 2) or inoculating models with live representative vaginal bacterial cultures (Aim 3). I hypothesize that a polymicrobial BV-like microbiota will exacerbate MG-induced cervical epithelial damage, enable rapid progression of MG/CT co-infection, and partially mediate metronidazole’s and tinidazole’s anti-MG activity. These aims will provide critical evidence to inform more thorough and actionable MG testing and treatment guidelines and improve reproductive health outcomes. My long-term career goal is to be an independent investigator using genomic, molecular, and epidemiologic methods to understand sexually transmitted infection natural history and translate knowledge into innovative prevention strategies. My K01 training with Dr. Ravel will include experiments in the 3D organotypic cervical epithelium model, host-pathogen interactions, and dual host-pathogen transcriptomics.