Persistent Chlamydial Envelope Antigens in Antibiotic‐Exposed Infected Cells Trigger Neutrophil Chemotaxis

Abstract

An in vitro coculture model system was used to explore conditions that trigger neutrophil chemotaxis to Chlamydia trachomatis infected human epithelial cells (HEC-1B). Polarized HEC-1B monolayers growing on extracellular matrix (ECM) were infected with C. trachomatis serovar E. By 36 h, coincident with the secretion of chlamydial lipopolysaccharide and major outer membrane protein to the surfaces of infected cells, human polymorphonuclear neutrophils (PMNL) loaded with azithromycin migrated through the ECM and infiltrated the HEC-1B monolayer. Bioreactive azithromycin was delivered by the chemotactic PMNL to infected epithelial cells in concentrations sufficient to kill intracellular chlamydiae. However, residual chlamydial envelopes persisted for 4 weeks, and PMNL chemotaxis was triggered to epithelial cells containing residual envelopes. Infected endometrial cells demonstrated up-regulation of ENA-78 and GCP-2 chemokine mRNA. Thus, despite appropriate antimicrobial therapy, residual chlamydial envelope antigens may persist in infected tissues of culture-negative women and provide one source for sustained inflammation.

Chlamydial infection of polarized HeLa cells induces PMN chemotaxis but the cytokine profile varies between disseminating and non-disseminating strains

“…As found previously for serovar E-infected endometrial HEC-1B cells (Wyrick et al, 1999), a strong transepithelial PMN migration to infected HeLa cells was detected after 36 h of infection for both strains. However, in this study, analysis of epithelial cytokine production in response to infection and inhibition experiments of PMN chemotaxis showed differences between the C. trachomatis E and L2 infections; IL-8, IL-11 and IL-6 expression were upregulated at the transcriptional level but, for the first two cytokines, higher amounts of protein were found in serovar L2 infection.…”

“…Shortly after infection is initiated, neutrophils are the most predominant effector cells recruited to the infectious foci (Patton and Kuo, 1989;Kiviat et al, 1990), suggesting that PMNs are involved in controlling the early stages of C. trachomatis infection, and confirmed by a study from Barteneva et al (1996). The acute host response to Chlamydia in the genital tract is primarily initiated and sustained by epithelial cells, the first and main targets of chlamydial infection (Rasmussen et al, 1997;Wyrick et al, 1999).…”

“…Peripheral blood was obtained from healthy donors, and the PMNs were separated and isolated by the standard Hypaque±Ficoll±dextran procedure (Wyrick et al, 1999). After hypotonic lysis of the red cells, the PMNs were resuspended in Hanks' balanced salt solution (HBSS) and counted in a haematocytometer; PMN purity was .…”

“…Rasmussen et al (1998; first reported that infection of non-polarized cervical (HeLa, SiHa and primary endocervical cultures) and colonic (HT-29, SW620) epithelial cells with C. trachomatis LGV or Chlamydia psittaci induced the production of several proinflammatory cytokines, including interleukin (IL)-8, GRO-a, granulocyte macrophage colony-stimulating factor (GM-CSF), IL-1a and IL-6. Subsequently, our laboratory showed that C. trachomatis serovar E infection of polarized human endometrial epithelial cells (HEC-1B) elicited a PMN chemotactic response and that the likely chemoattractant signals were ENA-78 and GCP-2, two members of the C-X-C chemokine family (Wyrick et al, 1999). Interestingly, little IL-8 was detected in the serovar E-infected endometrial cells.…”

Comparison of Chlamydia trachomatis serovar L2 growth in polarized genital epithelial cells grown in three-dimensional culture with non-polarized cells

“…Thus, while physiological differences between endometrial and endocervical cells appear to greatly influence the growth of urogenital serovar E, the more invasive serovar L2 grows equally well in both environments. This finding is quite interesting as these cell lines respond differently to serovar E and L2 infections, in particular in regard to the nature and amount of the cytokines produced [29,30], which may, in turn, induce different immune responses in the lower vs. upper genital tracts in response to lumenal serovar E vs. invasive LGV infections.…”