Figure 3. Anti-inflammatory functions of HDL on the macrophage.
ABCA1 and ABCG1 promote cholesterol efflux from macrophages to apoA-I/HDL. This interaction can attenuate macrophage inflammation via a number of pathways. A) The removal of cholesterol from lipid rafts can decrease TLR-4/CD14 expression on the surface of the macrophage desensitizing signaling by LPS. B) HDL can inhibit LPS stimulated type I INF response independent of sterol metabolism via a mechanism involving removal of the TRAM signaling molecule away from the cell membrane and into intracellular compartments. C) Binding of apoA-I to ABCA1 causes the activation of JAK-2 which then allows STAT-3 to directly bind and become activated by ABCA1. This results in the transcription of TTP which targets and degrades the inflammatory mRNAs transcribed by NF-κB from LPS signaling. C=Cholesterol