Immortalization of Human Urethral Epithelial Cells: a Model for the Study of the Pathogenesis of and the Inflammatory Cytokine Response to Neisseria gonorrhoeae Infection

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Abstract
The primary human urethral epithelial cells developed by our laboratory have been immortalized by transduction with a retroviral vector expressing the human papillomavirus E6E7 oncogenes. Analysis of telomerase expression and comparison to that in primary cells revealed detectable levels in the transduced human urethral epithelial cells. Immortalized urethral cells could be passaged over 20 times. Immunofluorescence microscopy studies showed that the immortalized cells were phenotypically similar and responded to gonococcal infection similarly to primary cells. Specifically, positive cytokeratin staining showed that the immortalized cells are keratinocytes; cell surface levels of human asialoglycoprotein receptor increase following gonococcal infection, and, like the primary cells, the immortalized urethral epithelial cells are CD14 negative. Using enzyme-linked immunosorbent assay, we found that interleukin-6 (IL-6) and IL-8 levels in primary urethral epithelial cell supernatants increase after challenge with N. gonorrhoeae . Likewise, the immortalized urethral epithelial cells produced higher levels of IL-6 and IL-8 cytokines in response to gonococcal infection. Cells challenged with a gonococcal lipid A msbB mutant produced reduced IL-6 and IL-8 levels when compared to the parent strain. Additionally, these data suggest that the 1291 msbB lipooligosaccharide may suppress cytokine induction.