Browsing by Author "Joubert, Bronwyn C."

Now showing 1 - 5 of 5

Antimicrobial susceptibility testing of four 5-nitroimidazoles against trichomonas vaginalis.
(2016) Mtshali, Andile.; Joubert, Bronwyn C.
Abstract available in PDF file.
The development of a stratified keratinocyte model for chlamydia trachomatis pathogenesis studies.
(2017) Jadoo, Sasha.; Sturm, Adriaan Willem.; Joubert, Bronwyn C.
A number of different methods to generate stratified keratinocyte layers have been published. These involved the use of normal human epidermal keratinocytes (NHEKs/NEKS), which have a better ability to stratify compared to HaCaT keratinocytes, which usually require supplemented growth factors or stromal interactions with fibroblasts to do so. This study aimed to generate a model of stratified keratinocytes, closely resembling in vivo skin, using HaCaT cells and to demonstrate the effect that C. trachomatis has on these layered keratinocytes, allowing us to gain insight on the pathophysiology of this organism. All cells and bacteria were propagated and titrated according to conventional protocols. HaCaT cells were subcultured upon confluence, seeded (1x106 cells/ml) onto collagen-coated PTFE Transwell membrane inserts and incubated at 33°C and 37°C for 24 days to allow differentiation and stratification. Once cells became confluent they were exposed to the air-liquid interface and fed with KGM Gold (Lonza) supplemented with 10% FBS and additional calcium. Thereafter, cells were fixed in 3.7% phosphate-buffered formaldehyde, embedded in a paraffin block, sectioned, stained and viewed. Hematoxylin and Eosin (H&E) staining was used to determine the resemblance to in vivo human skin. Immunofluorescence was used to detect keratin 10, keratin 14 and involucrin which are markers of keratinocyte differentiation. Stratified keratinocyte layers were infected with C. trachomatis and this was confirmed using the MicroTrak ® C. trachomatis Culture Confirmation Test Kit. Subsequent changes to the layers were also observed and recorded. It was shown that HaCaT cells grown at the air-liquid interface on collagen-coated PTFE Transwell membrane inserts were able to stratify at 33°C. However, more layers of keratinocytes were seen at 37°C after the same duration of incubation (24 days). Keratin 10, keratin 14 and involucrin were all detected in the layers grown at both temperatures, suggesting that the keratinocytes had committed to differentiation. However, the fluorescence seen at 33°C for keratin 10 and involucrin was more intense as compared to that seen at 37°. This suggests that although stratification was faster at 37°C, differentiation was quicker at 33°C. C. trachomatis was able to infect layered keratinocytes grown at both temperatures although not all layers formed at 33°C were infected. Degradation of keratinocyte layers after infection with C. trachomatis was more prominent in those grown at 37°C, which is in keeping with previous findings that the optimum growth temperature of the C. trachomatis LGV biovar is 37°C. This study provided a novel insight in suggesting the manner in which C. trachomatis is able to infect and migrate through in vivo skin, leaving room for further studies in which similar methods of generating stratified keratinocytes may be used to better understand the pathophysiology of various other organisms that affect keratinocytes.
The interaction of lymphogranuloma venereum and oculogenital chlamydia trachomatis with human keratinocytes and cervical epithelium.
(2010) Joubert, Bronwyn C.; Sturm, Adriaan Willem.
Background. Keratinocytes are the first target of infection for lymphogranuloma venereum (LGV) Chlamydia trachomatis, yet they have been omitted from pathogenesis studies. We infect keratinocytes and cervical cells with C. trachomatis and hypothesize different growth and cytotoxicity profiles among the strains. Methods. HaCaT human keratinocytes and ME-180 cervical cells were infected with C. trachomatis (multiplicity of infection (MOI) 0.025) serovars L1, L2, L3, 3 LGV clinical isolates or serovar E and incubated at 37 or 33°C for 5 days. Cytotoxicity was quantified daily using the CytoTox96® Non-Radioactive Cytotoxicity Assay, cells stained with the MicroTrak C. trachomatis Culture Confirmation kit and growth quantified by area of 100X photographs covered by Chlamydia. HaCaT and ME-180 cervical cells were infected with C. trachomatis (MOI 0.25) serovar L2 or E, incubated at 37 or 33°C for 48 hours and viewed with a transmission electron microscope (TEM). Mitochondrial activity was quantified using the MTT assay. The DeadEndTM Colorimetric TUNEL System with C. trachomatis Culture Confirmation kit as a counter-stain was used to assess cell death in infected versus uninfected cells. The BioVisionTM CaspGLOW Fluorescein Caspase Staining Kit and Transwell® Permeable Supports was used to differentiate between apoptosis mediated by cell-to-cell contact or a secreted molecule. Results. Growth in ME-180 versus HaCaT cells at 37°C was similar, but slower at 33 versus 37°C in HaCaT cells (p < 0.05). By day 5 L2 had grown faster than other strains in HaCaT cells at 37°C (p < 0.05), faster than clinical isolates in ME180 cells (p < 0.01), and faster than serovar E, and 2 clinical isolates at 33°C (p < 0.01). After 5 days L2 induced cytotoxicty was 11% in ME180 cells, which was higher than the clinical isolates (p < 0.01). In HaCaT cells at 33°C L2 EB were identified in a non-membrane state in the cytoplasm but not in the inclusion at 48 hours post infection. Serovar E but not L2 caused mitochondrial swelling at 1 h post infection in HaCaT cells at 37°C. This corresponded with a 16% reduction in mitochondrial activity (p < 0.001). TUNEL assay analyses demonstrated numerous dead cells adjacent to chlamydial inclusions for strains L2 and L3 but not L1 and E. An elevated number of caspase positive cells was detected in uninfected cell monolayers exposed to both L2 and E at 37°C but not 33°C. Conclusions. 1. C. trachomatis infects human keratinocytes in vitro. 2. Fresh clinical isolates behaved differently to the L2 reference strain. This demonstrates the need for fresh clinical isolates in pathogenesis studies of LGV. 3. In HaCaT cells at 33°C serovar L2 EB leave the intact inclusion and migrate through the cytoplasm in a non-membrane bound state 4. C. trachomatis induces apoptosis in uninfected cells exposed to infected cells via a secreted molecule at 37°C. This is more marked with serovar L2 exposure than serovar E exposure.
Quantitative susceptibility testing of chlamydia trachomatis against clinically relevant drugs.
(2017) Matadin, Riona.; Joubert, Bronwyn C.; Sturm, Adriaan Willem.
Abstract available in PDF file.
Temporal gene expression of Chlamydia trachomatis in keratinocytes at 37° versus 33°C.
(2017) Mzobe, Gugulethu Favourate.; Joubert, Bronwyn C.; Sturm, Adriaan Willem.
Abstract available in PDF file.