Abstract
Chlamydia infection targets the mucosal epithelium, where squamous and columnar epithelia can be found. Research on Chlamydia-epithelia interaction has predominantly focused on columnar epithelia, with very little known on how Chlamydia interacts with the squamous epithelium. The stratification and differentiation processes found in the squamous epithelium might influence chlamydial growth and infection dissemination. For this reason, three-dimensional (3D) organotypic stratified squamous epithelial cultures were adapted to mimic the stratified squamous epithelium and chlamydial infection was characterized. Chlamydia trachomatis infection in monolayers and 3D cultures were monitored by immunofluorescence and transmission electron microscopy to evaluate inclusion growth and chlamydial interconversion between elementary and reticulate body. We observed that the stratified epithelium varied in susceptibility to C. trachomatis serovars L2 and D infection. The undifferentiated basal cells were susceptible to infection by both serovars, while the terminally differentiated upper layers were resistant. The differentiating suprabasal cells exhibited different susceptibilities to serovars L2 and D, with the latter unable to establish a successful infection in this layer. Mature elementary body-containing inclusions were much more prevalent in these permissive basal layers, while the uppermost differentiated layers consistently harbored very few reticulate bodies with no elementary bodies, indicative of severely limited bacterial replication and development. For serovar D, the differentiation state of the host cell was a determining factor, as calcium-induced differentiation of cells in a monolayer negatively affected growth of this serovar, in contrast to serovar L2. The apparent completion of the developmental cycle in the basal layers of the 3D cultures correlated with the greater degree of dissemination within and the level of disruption of the stratified epithelium. Our studies indicate that the squamous epithelium is a suboptimal environment for growth, and thus potentially contributing to the protection of the lower genital tract from infection. The relatively more fastidious serovar D exhibited more limited growth than the faster-growing and more invasive L2 strain. However, if given access to the more hospitable basal cell layer, both strains were able to produce mature inclusions, replicate, and complete their developmental cycle.
Highlights
Three-dimensional (3D) organotypic stratified squamous models (3D cultures) have been used for decades in the field of epithelial biology to model the stratified squamous epithelium found in the human skin (Bell et al, 1981; Fusenig et al, 1983; Smola et al, 1993; Stark et al, 1999)
Increased susceptibility to Chlamydia infection is linked to ectopy, where a portion of the endocervix, which consists of a single layer of columnar epithelial cells, becomes exposed in the ectocervix (Lee et al, 2006)
We investigated how C. trachomatis interacted with three-dimensional (3D) organotypic stratified squamous models (3D cultures) to gain insight into the apparent resistance of this type of tissue to C. trachomatis infection as observed in clinical settings (Evans, 1982; Moorman et al, 1986)
Summary
Three-dimensional (3D) organotypic stratified squamous models (3D cultures) have been used for decades in the field of epithelial biology to model the stratified squamous epithelium found in the human skin (Bell et al, 1981; Fusenig et al, 1983; Smola et al, 1993; Stark et al, 1999) This tissue is characterized by multiple layers of cells where the proliferative and renewing basal layer divides asymmetrically to form an upper layer of nonreplicating suprabasal cells that begin to undergo differentiation (Fuchs and Raghavan, 2002; Simpson et al, 2011). It has the characteristics of mucosal tissues of the lower genital tract, oral cavity, esophagus, corneal epithelium, rectum, and foreskin (Chateau and Boehm, 1996; Kikuchi et al, 1997; Anderson et al, 2014)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.