Innate response of human endothelial cells infected with mycobacteria

Endothelial cells are susceptible to infection by several pathogens, but little is known about mycobacterial infection. We analyzed some features of mycobacteria-endothelial cell interactions and the innate response to the infection. Intracellular growth in human umbilical vein endothelial cells (HUVECs) of three Mycobacterium species: M. tuberculosis (MTB), M. abscessus (MAB) and M. smegmatis (MSM) was analyzed. M. smegmatis was eliminated; M. abscessus had an accelerate intracellular replication and M. tuberculosis did not replicate or was eliminated. M. abscessus infection induced profound cytoskeleton rearrangements, with M. tuberculosis infection changes were less marked, and with MSM were slight. Nitric oxide (NO) production was induced differentially: M. abscessus induced the highest levels followed by M. tuberculosis and M. smegmatis; the contrary was true for reactive oxygen species (ROS) production. Only M. tuberculosis infection caused beta-1 defensin over-expression. As a whole, our results describe some aspects of the innate response of HUVEC infected by mycobacteria with different virulence and suggest that a strong cytoskeleton mobilization triggers a high NO production in these cells.