Quantification and comparison of toll-like receptor expression and responsiveness in primary and immortalized human female lower genital tract epithelia

Problem: To better understand innate immune responses to sexually-transmitted infection (STI) and the appropriateness of epithelial cell (EC) models of the vaginal and cervical mucosa, quantified toll-like receptor (TLR) expression from a population of women is needed. Methods of study: TLR gene expression was quantified in primary and immortalized endocervical, ectocervical, and vaginal EC from multiple donors. TLR bioactivity was evaluated by cytokine elaboration. Results: TLR1-3 and 5-9 were expressed in each EC type with TLR2, 3, 5, 6 and CD14 expressed most abundantly. TLR4 was expressed by endocervical and vaginal EC. Agonist stimulation of TLR2, 3, 5 and 6 elicited cytokines. TLR4 and 7-9 were minimally expressed and were not consistently bioactive. Immortalized EC generally modeled primary cultures but elaborated significantly reduced cytokine levels. Conclusion: TLR expression patterns were remarkably conserved across the study population and evaluated tissues indicating a predictable responsiveness to STI. The results support cautious use of immortalized cells for genital tract modeling.