Heat shock protein 10 of Chlamydophila pneumoniae induces proinflammatory cytokines through Toll-like receptor (TLR) 2 and TLR4 in human monocytes THP-1.

Inflammatory response is the first line of infection. Previous studies have suggested that Chlamydophila pneumoniae heat shock protein (CHSP) 60 is present in human atheromata, and it plays an important role on the chronic infection elicited by C. pneumoniae. Here, we demonstrated in vitro the impact of heat shock protein 10 (HSP10) of C. pneumoniae on THP-1 cells and the role of Toll-like receptors (TLRs) in the procedures of inflammatory response. The production of proinflammatory cytokines, including tumor necrosis factor alpha (TNF-alpha), interleukin (IL)-6, and IL-1beta were induced by recombinant HSP10 dose-dependently, and the proinflammatory activity of HSP10 was greatly reduced by heating and deproteinization treatment. The expression of TLR4 and TLR2 on the cultured cells were determined by reverse transcriptase-polymerase chain reaction and immunofluorescence. Peritoneal macrophages isolated from wild-type (C3H/HeN) and TLR4-deficient mice (C3H/HeJ) were respectively stimulated with endotoxin-free proteins. Cytokine responses after stimulation were significantly different, depending on the presence of TLR4. The effect on cytokine expression was blocked by anti-TLR2 or anti-TLR4 MAb partially or dramatically. Thus, HSP10 of C. pneumoniae which could elicit inflammatory reactions in human monocytes may contribute to the inflammatory processes in Chlamydophila infection, and the effects were mediated by TLR4 and, to a lesser extent, TLR2.