Mechanisms of Fallopian tube damage in gonococcal pelvic inflammatory disease

About This Grant

PROJECT SUMMARY Neisseria gonorrhoeae releases large amounts of pro-inflammatory peptidoglycan and lipooligosaccharide during infection. The inflammatory response to these molecules in the human Fallopian tube causes the death and sloughing of the ciliated cells and scarring of the tissue, making it nearly impossible to move an egg down the oviduct. This tubal-factor infertility, together with chronic pelvic pain, and risk of ectopic pregnancy make up the severe sequelae of gonococcal infection. While the effects of gonococcal secreted products in Fallopian tube damage have been known for over forty years, the mechanisms involved have not been determined. In our recently-published RNA-sequencing study, we found that treatment of Fallopian tube tissue with gonococcal supernatants or N. gonorrhoeae infection resulted in a strong inflammatory cytokine response including increased IL-17C, CCL4, IL-1b, and TNF-a. Transcripts for cell-cell junction proteins were decreased, and transcripts for matrix metalloproteinases were increased, suggesting mechanisms for ciliated cell sloughing. Furthermore, the decreases in cell-cell junction protein transcripts were not seen if the gonococcal soluble products did not contain GlcNAc-anhydro-MurNAc-tripeptide (TriDAP), the NOD1-agonist form of peptidoglycan fragments. This proposal will determine mechanisms involved in ciliated cell sloughing and tissue damage using human Fallopian tube tissue in organ culture. We propose a model of tissue damage in gonococcal pelvic inflammatory disease in which peptidoglycan fragments and lipooligosaccharide induce inflammatory cytokine responses and cause increases in matrix metalloproteinases and decreases in cell junction proteins allowing detachment of ciliated cells. Programmed cell death, possibly pyroptosis, kills the ciliated cells, and they slough from the epithelium. We will test this model by performing a comprehensive analysis of ciliated cell sloughing using high-resolution live cell imaging as well as super-resolution microscopy to examine matrix metalloproteinases, cell junctions and cell junction proteins, cell morphological changes, and markers of cell death pathways following gonococcal infection or treatment with gonococcal soluble products. We will use spatial transcriptomics to determine how cellular responses in ciliated Fallopian tube cells differ from those of secretory cells, examining different time points in infection or following treatments with gonococcal products as the ciliated cells die and are lost from the epithelium. These studies will reveal why ciliated cells are destroyed in various bacterial infections, and this knowledge will be useful for designing treatments for gonococcal pelvic inflammatory disease.