Chlamydia pneumoniae multiplies in human endothelial cells in vitro

The ability of three C. pneumoniae isolates, Kajaani 6, Helsinki 12 and TW-183, to grow in human umbilical vein endothelial cells (HUVEC) and in an immortalized endothelial cell line EA.hy 926 was studied. All C. pneumoniae isolates were capable of multiplying in endothelial cells. EA.hy926 cells could support the growth of C. pneumoniae better than HUVEC, yet less efficiently than HL and HEp-2 cells that are conventionally used in C. pneumoniae culturing. Although centrifugation of the inoculum greatly increased the inclusion yields, it was not necessary for infectivity. In addition, a persistent infection of C. pneumoniae in EA.hy 926 and HL cells ensued and it was followed up for two months. The fact that endothelial cells can serve as hosts to C. pneumoniae might be a significant contributing factor in the pathogenesis of atherosclerosis, a disease which recent studies show to be associated with chronic C. pneumoniae infection.