Abstract
Purpose :
Trachoma is a chronic ocular disease caused most frequently by Chlamydia trachomatis (Ct) strains A, B, Ba and C. Disease is characterized by inflammation of the conjunctiva and subsequent scarring, leading to trichiasis and blindness. The initial site of conjunctival infection is the mucosal epithelium, composed of a mixed epithelial population of goblet and stratified squamous epithelial cells. Eicosanoids are potent lipid-derived mediators of inflammation. Remarkably, there are no publications evaluating the role of eicosanoids in Ct infection and disease pathogenesis.
Methods :
We examined eicosanoid secretion in primary (CjE) and telomerase immortalized (HCjE) human conjunctival epithelial and HeLa229 cells in response to infection with trachoma strain Ba compared to uninfected cells. Cell supernatants were collected at 1, 2, 24, and 48 hpi, and 44 eicosanoids were measured by liquid chromatography tandem mass spectrometry. The relative mRNA expression of EP1-4 receptors, cyclooxygenase (COX-1/2), and lipoxygenase (5/15-LOX) pathway enzymes was measured using RT-qPCR in lysed EMS cells. Rate of Ct infection and cell characterization was done using immunofluorescence.
Results :
Ba infected CjE and HCjE cells increased secretion of eicosanoid precursor arachidonic acid in an MOI and time dependent manner (AA; p < 0.05). HCjE cells produced potent lipid mediators including prostaglandin-E2 (P3GE2; p < 0.0005) and prostaglandin-F2α (PGF2α; p < 0.005), while CjE cells secreted higher levels of 5-HETE (p< 0.005) but dampened pro-resolution lipoxin-A4 (LXA4; p < 0.0005). No significant changes in prostaglandin or lipoxin secretion were observed in HeLa229 cells. In EMS cells, mRNA expression for COX-2 enzyme and EP3 receptor increased while 15-LOX dioxygenase decreased when infected with Ba strain.
Conclusions :
Our data show that infection of physiologically relevant CjE cells with trachoma strain Ba induces a pro-inflammatory, anti-resolution mediator profile that is consistent with what occurs in vivo during phenotypic trachomatous inflammation-intense (TI) disease.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.