Human Fallopian Tube Epithelial Cell Culture Model To Study Host Responses to Chlamydia trachomatis Infection

Abstract

Chlamydia trachomatis infection of the human Fallopian tubes can lead to damaging inflammation and scarring, ultimately resulting in infertility. To study the human cellular responses to chlamydial infection, researchers have frequently used transformed cell lines that can have limited translational relevance. We developed a primary human Fallopian tube epithelial cell model based on a method previously established for culture of primary human bronchial epithelial cells. After protease digestion and physical dissociation of excised Fallopian tubes, epithelial cell precursors were expanded in growth factor-containing medium. Expanded cells were cryopreserved to generate a biobank of cells from multiple donors and cultured at an air-liquid interface. Culture conditions stimulated cellular differentiation into polarized mucin-secreting and multi-ciliated cells, recapitulating the architecture of human Fallopian tube epithelium. The polarized and differentiated cells were infected with a clinical isolate of C. trachomatis, and inclusions containing chlamydial developmental forms were visualized by fluorescence and electron microscopy. Apical secretions from infected cells contained increased amounts of proteins associated with chlamydial growth and replication, including transferrin receptor protein 1, the amino acid transporters SLC3A2 and SLC1A5, and the T cell chemoattractants CXCL10, CXCL11, and RANTES. Flow cytometry revealed that chlamydial infection induced cell surface expression of T cell homing and activation proteins including ICAM-1, VCAM-1, HLA class I and II, and IFNγR. This human Fallopian tube epithelial cell culture model is an important tool with translational potential for studying cellular responses to Chlamydia and other sexually-transmitted pathogens.

Host–Pathogen Interactions of Chlamydia trachomatis in Porcine Oviduct Epithelial Cells

“…Our data demonstrate the following: (i) Ct developmental cycle in pOECs is productively completed within 48 hpi; (ii) pOECs mainly produce interferon regulated genes and T-cell attracting chemokines; and (iii) while Ct infection does not alter the overall mRNA and protein expression of CLDN-4, it leads to a temporary decrease in membrane-bound CLDN-4 with a coinciding increase of CLDN-4 within the Ct inclusion. Thereby, we have demonstrated that the Ct developmental cycle in pOECs as well as their immune response to infection is highly similar to what has previously been reported for their human cell counterparts [15]. We thereby establish pOECs as a relevant cell model for studies into Ct host-pathogen interactions.…”

“…Yet, surprisingly, none of these cytokines were upregulated to a level that crossed the biological relevance threshold of 1.5× and significance level of p < 0.05 (Table 1). While this lack in upregulation was unexpected, these same cytokines were also not upregulated by Ct infection of primary human Fallopian tube epithelial cells [15]. Therefore, at least in vitro, genital tract epithelial cells might not be a primary source of pro-inflammatory cytokines in Ct infection.…”

“…In addition, the receptor for the chemokine RANTES is also expressed on T cells-CCR5 [65]. With RANTES, CXCL10, and CXCL11, most of these targets have also been upregulated in apical secretions of primary human Fallopian epithelial cells 48 h post Ct infection [15]; and CXCL10 and CXCL11 have also been associated with the increased risk of Ct reinfection in women [66]. In addition, using murine genital mucosa, Olive et al showed that CXCR3 and CCR5 are both required for T-cell mediated protection against Ct [67].…”

“…This cycle can be divided into five steps: (i) the EB infects the host cell, mainly epithelial cells, via host receptors such as the protein disulfide isomerase (PDI), or the ephrin receptor A2 (EPHA2) [14]; (ii) within 2 h post infection (hpi), it differentiates in an "initial body" into an RB; (iii) thereafter, the RB divides by binary fission in an "inclusion" [14]; (iv) at ~18 hpi, the RB associates with the inclusion membrane and re-differentiates into EBs; (v) by 40-48 hpi, these EBs are released from the host cells by lysis or extrusion to start another round of infection [4]. The infected epithelial cell reacts by initiating an innate immune response that includes the production of immune effectors like chemokines and cytokines for the recruitment and activation of immune cells against infection [15,16].…”

Lactobacillus crispatus BC1 Biosurfactant Counteracts the Infectivity of Chlamydia trachomatis Elementary Bodies

“…Further studies are needed to exactly quantify the amount of the various fatty acids in L. crispatus BC1 BS, as well as to understand the mechanisms of action by which fatty acids counteract EBs infectivity. In this context, ex vivo and in vivo models, such as polarized human fallopian tube epithelial cells and animal models [ 43 , 44 ], could be employed to better represent the complexity of CT infection and improve translational relevance.…”