Cholesterol Efflux Decreases TLR4-Target Gene Expression in Cultured Macrophages Exposed to Ghosts.

causes African trypanosomiasis in humans. Infection with elicits a potent pro-inflammatory immune response within infected human hosts, and this response is thought to at least be partially due to Toll-like receptor (TLR) activation. In response to stimulation by lipopolysaccharide and other pathogen antigens, TLR4 translocates to lipid rafts, which induces the expression of pro-inflammatory genes. However, cholesterol efflux is acknowledged as anti-inflammatory due to promoting lipid raft disruption. In this study, we wanted to assess the impact of "ghosts", which are non-viable essentially devoid of intracellular contents, in stimulating macrophage TLR4 translocation to lipid rafts, and whether promoting cholesterol efflux in macrophages incubated with ghosts attenuates TLR4-target gene expression. When cultured macrophages were exposed to ghosts, we observed an increase in lipid raft TLR4 protein content, which suggests certain surface molecules of serve as ligands for TLR4. However, pretreating macrophages with cholesterol acceptors before ghost exposure decreased lipid raft TLR4 protein content and the expression of pro-inflammatory TLR4-target genes. Taken together, these results imply that macrophage cholesterol efflux weakens pro-inflammatory responses which occur from infection via increasing macrophage lipid raft disruption.