TLR3 Deficiency Leads to Altered Immune Responses toChlamydia trachomatisInfection in Human Oviduct Epithelial Cells

Abstract

ABSTRACTReproductive tract pathology caused byChlamydia trachomatisinfection is an important global cause of human infertility. To better understand the mechanisms associated withChlamydia-induced genital tract pathogenesis in humans, we used CRISPR genome editing to disrupt TLR3 function in the human oviduct epithelial (hOE) cell-line OE-E6/E7, in order to investigate the possible role(s) of TLR3 signaling in the immune response toChlamydia. Disruption of TLR3 function in these cells significantly diminished theChlamydia-induced synthesis of several inflammation biomarkers including IFN-β, IL-6, IL-6Ra, sIL-6Rβ (gp130), IL-8, IL-20, IL-26, IL-34, sTNF-R1, TNFSF13B, MMP-1, MMP-2, and MMP-3. In contrast, theChlamydia-induced synthesis of CCL-5, IL-29 (IFNλ1) and IL-28A (IFNλ2) were significantlyincreasedin the TLR3-deficient hOE cells when compared to their wild-type counterparts. Our results propose a role for TLR3 signaling in limiting the genital tract fibrosis, scarring, and chronic inflammation often associated with human chlamydial disease. Interestingly, we saw thatChlamydiainfection induced the production of biomarkers associated with persistence, tumor metastasis, and autoimmunity such as soluble CD163 (sCD163), chitinase-3-like protein 1, osteopontin, and pentraxin-3 in the hOE cells; however, their expression levels were significantly dysregulated in the TLR3-deficient hOE cells. Finally, we demonstrate using the hOE cells that TLR3 deficiency resulted in an increased amount of chlamydial LPS within theChlamydiainclusion, which is suggestive that TLR3 deficiency leads to enhanced chlamydial replication and possibly increased genital tract pathogenesis during human infection.AbbreviationshOE, human OE-E6/E7 cells; TLR3 KO, TLR3 knockout cell line; poly (I:C), Polyinosinic–polycytidylic acid sodium salt.