Identification of cellular factors involved in Neisseria gonorrhoea induced enhanced HIV-1 transmission in a cervical tissue based organ culture model

The presence of sexually transmitted infections (STI) such as Neisseria gonorrhoeae (NG) can enhance the transmission of HIV-1. Our goal in this study is to elucidate mechanism by which NG induces enhanced HIV-1 transmission. A cervical tissue based organ culture system was developed to study the interaction between NG and HIV-1 which provided a unique opportunity to elucidate mechanism of NG induced enhanced HIV-1 transmission across cervical mucosa. We demonstrated that the NG exposure on the cervical tissue in the organ culture model showed physical characteristics of NG infection and induced high levels of inflammatory cytokines IL1-β and TNF-α that have been observed during in-vivo NG infection in the cervix. In elucidating the mechanism of NG induced enhancement of HIV-1 transmission, we demonstrated that NG not by itself but the culture fluids from NG exposed tissues (reminiscent of cervical milieu) increased HIV-1 transcription from the HIV- LTR in TZM-bl cells, induced full length HIV-1 from latently infected U1 and ACH2 cells and increased transmission of HIV-1 across cervical mucosa. The whole genome transcriptome analysis using second-generation sequencing of the micro-dissected epithelial layer of the tissues exposed to NG and HIV-1 identified with high statistical significance differentially expressed genes in NG exposed and HIV-1 exposed tissues, and identified common cellular factors as well as pathways involved in cell activation, migration and stimulation expressed in the epithelia. Out of these only two differentially expressed genes that were common between tissues exposed to both NG and HIV-1 are CXCL10 and IL8. Addition of inhibitors of CXCL10 and IL8 suppressed HIV-1 transmission, while addition of CXCL10 and IL8 increased HIV-1 transmission indicating that CXCL10 and IL8 could be involved in HIV-1 transmission across cervical epithelia. IL-1β also increased CXCL10 and IL8 expression in cervical tissues and enhanced HIV-1 transmission Altogeth