Production of basic fibroblast growth factor and interleukin 6 by human smooth muscle cells following infection with Chlamydia pneumoniae

Chlamydia pneumoniae infection has been associated with asthma and atherosc lerosis, Smooth muscle cells represent host cells for chlamydiae during chr onic infection. In this study we demonstrated that C. pneumoniae infection of human smooth muscle cells in vitro increased production of interleukin 6 (IL-6) and basic fibroblast growth factor (bFGF) as shown by reverse trans cription-PCR, immunoblotting, and enzyme-linked immunosorbent assay. In con trast, levels of platelet-derived growth factor A-chain mRNA were not affec ted after infection. The stimulation of bFGF and IL-6 production was most e ffective when viable chlamydiae were used as inoculum, Furthermore, inhibit ion of bacterial protein synthesis with chloramphenicol prevented up-regula tion of IL-6 and bFGF in infected cells, Addition of IL-6 antibody to infec ted cultures diminished bFGF expression, indicating involvement of produced IL-6. These findings suggest that chlamydial infection of smooth muscle ce lls elicits a cytokine response that may contribute to structural remodelin g of the airway wall in chronic asthma and to fibrous plaque formation in a therosclerosis.