Infection of U937 monocytic cells with Chlamydia pneumoniae induces extensive changes in host cell gene expression.

The effect of infection with Chlamydia pneumoniae on host messenger RNA expression in human monocytic cells with complement DNA microarrays was studied. The data chronicle a cascade of transcriptional events affecting 128 genes, many of which have not previously been reported to be affected by C. pneumoniae infection. Down-regulated genes are primarily associated with RNA and DNA metabolism, chromosomal stability, and cell-cycle regulation. Up-regulated messages include those for a variety of genes with important proinflammatory functions. Many of the up-regulated genes-including the hyaluron receptor CD44, vasoconstrictor endothelin-1, smooth muscle growth factor heparin-binding EGF-like growth factor, and fatty acid binding protein-4-had been previously described as linked to the development of atherosclerosis and other chronic inflammatory diseases. C. pneumoniae-infected monocytes can contribute to the development and progression of diseases for which acute or chronic inflammation has been shown to be important, such as atherosclerosis.