Trachoma, a preventable blinding eye disease, is initiated by ocular infection with Chlamydia trachomatis (Ct). MicroRNA (miR) are post-transcriptional regulators of gene expression and play a major role in health and disease. We have investigated the miR profile during C. trachomatis infection of epithelial cells in vitro and in vivo during follicular trachoma with current C. trachomatis infection. Small RNA sequencing was carried out on human epithelial cells infected in vitro and on samples from five children with follicular trachoma with current Ct infection and five children with no evidence of clinical trachoma or infection. In vitro two strains of ocular Ct that differ in virulence, A2497 and isogenic plasmid-free A2497 were used to infect epithelial cell lines. RNAseq results were confirmed by qPCR in six in vitro biological replicates and in 163 clinical samples. Differential miR expression was not detected in isolated epithelial cells infected in vitro at 48 hours post infection. HCjE cells, a conjunctival epithelial cell line, have markedly different miR background expression compared to Hep2 cells. The differing miR profiles of Hep2c and HCjE suggest caution should be used when extrapolating data from Hep2 cells to a tissue-specific clinical scenario. In follicular trachoma, miR-155, miR-150, miR-142, miR-181b, miR-181a, miR-342 and miR-132 were up-regulated during current Ct infection. MiR-4728 and miR-184 were down-regulated in follicular trachoma independent of Ct infection. In follicular trachoma, miR expression reflects development and regulation of the immune response during current Ct infection and a prolonged period of wound healing following Ct clearance.

Trachoma, Chlamydia trachomatis