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Role of Cholesteryl Ester (CE) Hydrolase Mediated Mobilization of Intracellular CE in Regulating Inflammasome Activation
Author(s) -
Ghosh Shobha,
Tang QiongYao,
Logothetis Diomedes,
Wang Jing
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.715.2
Subject(s) - inflammasome , microbiology and biotechnology , chemistry , lipid raft , secretion , signal transduction , receptor , biochemistry , biology
Cellular cholesterol content and inflammatory pathways are thought to be linked but the underlying mechanisms are not completely defined. Dramatic (>20 fold) reduction in circulating IL‐1b in macrophage‐specific CE hydrolase (CEH) transgenic (Tg) mice indicates a role of macrophage cholesterol homeostasis in regulating IL‐1b production. Cellular priming for inducing transcription via NF‐kB (Signal 1) and activation of NLRP3 inflammasome for proteolytic cleavage of pro‐IL‐1b (Signal 2) are required for IL‐1b secretion. While activation of surface TLR4 represents Signal 1, several disparate signals can activate inflammasome and decrease in cellular K+ by increased efflux is an important convergence point. Since membrane cholesterol/lipid‐raft levels regulate the function of cell surface receptors and K+ channels, we hypothesized that CEH‐mediated reduction in cellular cholesterol attenuates IL‐1b secretion by reducing inflammasome activation. Mouse peritoneal macrophages (MPM) from C57BL/6 (WT) or CEHTg mice were used for all the studies. Membrane cholesterol content was reduced by CEH over‐expression with significant reduction in lipid‐raft cholesterol content (A).Delayed reappearance of TLR4 (MFI, B) following LPS stimulation in CEHTg MPMs indicates attenuation of Signal 1. Efflux of K+ (Signal 2) required for inflammasome activation occurs via K+ channels and single cell patch clamp studies were performed to monitor channel activity. Significantly lower outward K+ currents in CEHTg MPMs were observed in CEHTg MPMs (C). Pharmacological inhibition of CEH increased IL‐1b secretion from MPMs (D) confirming the role of CEH‐mediated cellular cholesterol homeostasis in regulating inflammasome activation.