D-199. Impact of Hypocholesterolemic Delta-Tocotrienol on Chlamydial Development In Vitro
Chlamydiae, inclusion-forming obligate intracellular bacteria, are associated with common pathologies including Alzheimer’s disease, atherosclerosis, coronary heart disease, asthma, and respiratory tract infections. Entry by Chlamydiae, including C. pneumoniae and most C. trachomatis genital tract serovars, involves cholesterol-rich lipid raft domains. These can contain caveolae, a key element in cholesterol homeostasis with which Chlamydia may associate at cholesterol-enriched plaque regions. We hypothesized that the hypocholesterolemic activity of delta-tocotrienol, a vitamin E compound, might impact infection by Chlamydia. Human mammary tumor (MCF-7, TMX2-28), epithelial (HEp-2), B-lymphocyte (JY), and murine macrophage (J774A.1) cell lines were incubated with delta-tocotrienol concentrations of 10-30 μmol/L for 6 h prior to infection by serovar K, a C. trachomatis strain of the sexually transmitted disease biovar. At intervals between 24-72 h, cells were fixed, then samples were assessed, and infected cells identified by immunofluorescent staining followed by quantitative flow cytometry and confocal microscopy. Detected infection levels for cells pretreated with delta-tocotrienol were decreased by >50%. In addition, confocal immunofluorescent microscopy demonstrated the concomitant occurrence of aberrant pathogen inclusion development, including an apparent failure of fusion among the individually internalized elementary body clusters, and the formation of notably smaller inclusions. Microscopic counts of large and small inclusions in the delta-tocotrienol vs. control cells showed decreases of 3- and 2-fold, respectively. For JY cells, flow cytometry showed that a decrease of Chlamydia-infected cells was at least 2-fold during an infection period of 72 h, with a 2.6-fold maximum at 36 h. Since lipids and lipid levels may be critical to Chlamydia infections in vivo, hyperlipidemic patients were assessed for blood cell borne Chlamydiae. The in vivo impact of dietary delta-tocotrienol on Chlamydia carriage is under examination in a clinical study with cholesterol-suppressive delta-tocotrienol.