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

Abstract

Reproductive tract pathology caused by Chlamydia trachomatis infection is an important 24 global cause of human infertility. To better understand the mechanisms associated with 25 Chlamydia-induced genital tract pathogenesis in humans, we used CRISPR genome 26 editing to disrupt TLR3 function in the human oviduct epithelial (hOE) cell-line OE-27 E6/E7, in order to investigate the possible role(s) of TLR3 signaling in the immune 28 response to Chlamydia. Disruption of TLR3 function in these cells significantly 29 diminished the Chlamydia-induced synthesis of several inflammation biomarkers 30including IFN-β, IL-6, IL-6Ra, sIL-6Rβ (gp130), 31 TNFSF13B, MMP-1, MMP-2, and MMP-3. In contrast, the Chlamydia-induced synthesis 32 of CCL-5, IL-29 (IFNλ1) and IL-28A (IFNλ2) were significantly increased in the TLR3-33 deficient hOE cells when compared to their wild-type counterparts. Our results propose 34 a role for TLR3 signaling in limiting the genital tract fibrosis, scarring, and chronic 35 inflammation often associated with human chlamydial disease. Interestingly, we saw 36 that Chlamydia infection induced the production of biomarkers associated with 37 persistence, tumor metastasis, and autoimmunity such as soluble CD163 (sCD163), 38 chitinase-3-like protein 1, osteopontin, and pentraxin-3 in the hOE cells; however, their 39 expression levels were significantly dysregulated in the TLR3-deficient hOE cells. 40Finally, we demonstrate using the hOE cells that TLR3 deficiency resulted in an 41 increased amount of chlamydial LPS within the Chlamydia inclusion, which is 42 suggestive that TLR3 deficiency leads to enhanced chlamydial replication and possibly 43 increased genital tract pathogenesis during human infection. 44 45 3 KEYWORDS: Chlamydia trachomatis, TLR3, human oviduct epithelial cells. 46 Abbreviations: hOE, human OE-E6/E7 cells; TLR3 KO, TLR3 knockout cell line; poly 47 (I:C), Polyinosinic-polycytidylic acid sodium salt. 48 49 50 51 52 53 The bacterial pathogen Chlamydia trachomatis has caused 1,526,658 infections in the 54 United States in 2015 (an increase of 6% since 2014), and it is the most commonly 55 reported bacterial sexually transmitted disease (STD) in the United States (1). Genital 56 tract C. trachomatis infections are easily cured with antibiotics if properly diagnosed at 57 early stages of infection. However, because 75-90% of women infected with Chlamydia 58 are asymptomatic for clinical disease, opportunities for therapeutic interventions are 59 usually missed. The asymptomatic nature of the clinical symptoms is the major 60contributing factor to the continuing spread of the disease to uninfected partners, and 61 the more severe pathogenesis and sequelae that often lead to infertility in women. 62Further contributing to the growing rates of infectivity amongst the previously uninfected 63 populations are the statistics showing that up to 90% of men infected with Chlamydia 64 exhibit no symptoms (2, 3) and that an effective vaccine remains elusive (4). 65Chlamydia infections are also lead...