HLA-B27 Expression Does Not Modulate IntracellularChlamydia trachomatisInfection of Cell Lines

Abstract

Chlamydia trachomatis is an obligate intracellular pathogen. Infection of susceptible individuals with this bacterium can trigger the development of reactive arthritis, an acute inflammation that is associated with the expression of the class I major histocompatibility antigen, HLA-B27. Other facultative intracellular pathogens, such as Yersinia and Salmonella spp., are also known triggers of reactive arthritis. Previous studies report conflicting results concerning whether the presence of HLA-B27 modulates the infection of cells with these enteric pathogens. In the present study, we have examined whether the expression of HLA-B27 can influence the infection of cell lines with C. trachomatis and also whether the replication of these bacteria is altered in HLA-B27-expressing cell lines. To do this, we have used a sensitive flow cytometric approach. We fixed and permeabilized cells and used fluorescein isothiocyanate-conjugated monoclonal antibody specific for chlamydia lipopolysaccharide to detect intracellular bacteria. The staining pattern obtained closely resembled the intracellular life cycle of chlamydia, with the appearance of brightly staining cells correlating to the microscopic detection of mature inclusion bodies. Moreover, since the percentage of cells that stained with the antibody was proportional to the infectious inoculum used, we were able to use the technique to quantitate the number of infectious organisms recoverable from infected cell lines. An important component of our study was the use of heparin to prevent reinfection of cells and thus enable the infection to be followed from a discrete time point. Our results suggest that HLA-B27 influences neither the infection nor replication of C. trachomatis serovar L2 within cell lines. Consequently, the role of HLA-B27 in the pathogenesis of reactive arthritis may lie downstream of the invasion and replication stages of the triggering pathogenic infection.

Infection of epithelial and dendritic cells byChlamydia trachomatisresults in IL-18 and IL-12 production, leading to interferon-γ production by human natural killer cells

“…C. trachomatis serovar L2 was used throughout this study, and was purified from infected HeLa cells as previously described [12]. DC were infected with C. trachomatis (50:1 bacteria per cell) at day 7 of culture and used 24 h post infection, this being sufficient time to induce productive infection [13].…”

Susceptibility of Prostate Epithelial Cells toChlamydia muridarumInfection and Their Role in Innate Immunity by Recruitment of Intracellular Toll-Like Receptors 4 and 2 and MyD88 to the Inclusion

“…Following incubation for 48 h, cells were fixed with methanol and stained with anti-cLPS monoclonal antibody, and the presence of inclusion bodies was measured by fluorescent microscopy. Intracellular staining of PPEC followed by flow cytometric analysis was performed on cells 48 h after the infection following the protocol described by Young et al (49). Briefly, cells were harvested by incubation with trypsin-EDTA (Sigma) for the intracellular staining; cells were then incubated with the antiChlamydia LPS monoclonal antibody or an appropriate isotype control in fluorescence-activated cell sorter wash buffer (5 mM EDTA, 0.1% sodium azide, and 1% bovine serum albumin in PBS) supplemented with 0.1% saponin for 30 min at 4°C.…”

Reactive and Enteropathic Arthritis

“…In contrast, some investigators have found that HLA-B27 expression alters neither the rates of infection nor the rate of replication of C. trachomatis in cell lines (24). Using synoviocytes harvested from HLA-B27-positive patients, it was observed that HLA-B27 had no direct role in either the internalization of S. typhimurium or in the kinetics of intracellular killing (25).…”