ABSTRACT
Objective: The main objective of our study was to evaluate the response of endothelial cells infected with Chlamydophila pneumoniae (C. pneumoniae), by using von Willebrand factor (vWf) antigen as a marker for endothelial damage and dysfunction. Another objective was to evaluate the effect of cycloheximide on C. pneumoniae infectivity and vWf secretion from human umbilical vein endothelial cells (HUVECs). Methods: HUVECs were harvested. After first passage, the HUVECs were inoculated with C. pneumoniae in three concentrations of cycloheximide (0, 1, and 2 µg/ml). At 24, 48, and 72 hours post-inoculation, supernatants from each HUVEC culture well were collected and measured for vWf antigen by sandwich ELISA as well as non-infected HUVECs were used as controls. C. pneumoniae infectivity was evaluated by indirect immunofluoresce technique and polymerase chain reaction. Results: The cycloheximide-treated HUVECs resulted in greater infection compared to the non-treated HUVECs. Means of vWf antigens from HUVECs infected with C. pneumoniae were not different from those of non-infected HUVECs. However, there was a significant change in vWf secretion when different concentrations of cycloheximide were used in the culture system. Conclusion: From our study, the results of vWf antigen secreted from HUVECs did not support the direct endothelial damage effect caused by C. pneumoniae infection. Therefore, vWf antigen is not a sensitive marker for this event. Furthermore, results from this study supported the infectious ability of C. pneumoniae on HUVECs and the importance of cycloheximide in improving the infectivity of this organism. However, the investigators had to use this substance cautiously, especially in protein synthesis study. Nevertheless, a non-variable dose of C. pneumoniae and the use of only one surrogate endothelial damage marker may limit the interpretation of this study.