Cholesterol crystals activate Syk and PI3 kinase in human macrophages and dendritic cells. (August 2016)

• Record Type: Journal Article
• Authors: Corr, Emma M.; Cunningham, Clare C.; Dunne, Aisling
• Is Part Of: Atherosclerosis. Volume 251(2016)
• Page Start: 197
• Page End: 205
• Publication Date: 2016-08
• Subjects: Cholesterol crystals -- Inflammation -- Syk -- PI3K -- S100 proteins; CHC cholesterol crystals -- Syk spleen tyrosine kinase -- PI3K phosphoinositide-3 kinase -- MMP matrix metalloprotease -- NLRP3 Nod-like receptor related protein 3 -- DAMPs damage associated molecular patterns -- CLR C-type lectin receptor -- MAP mitogen-activated protein kinases; Arteriosclerosis -- Periodicals; Electronic journals; 616.136
• DOI: 10.1016/j.atherosclerosis.2016.06.035
• Languages: English
• ISSNs: 0021-9150

Abstract

Abstract: Background and aims: Cholesterol crystals are a key component of atherosclerotic lesions where they promote pro-inflammatory cytokine production and plaque destabilization. Antagonists of inflammatory mediators and agents that dissolve or prevent the formation of cholesterol crystals are being explored as potential therapeutics for atherothrombosis. We sought to identify signalling molecules activated following exposure of immune cells to cholesterol crystals with the view to identifying novel therapeutic targets. Methods: Human macrophages and dendritic cells (DC) were exposed to cholesterol crystals and activation of signalling molecules was assessed by immunoblotting. The role of Syk and PI3K in crystal-induced interleukin (IL)-1 production was determined by ELISA using specific kinase inhibitors. Real-time PCR was employed to examine the role of Syk/PI3K in cholesterol crystal-induced expression of S100 proteins and MMPs. Results: Exposure of human macrophages and DC to cholesterol crystals induced robust activation of Syk and PI3K within 2–5 min. Pharmacological inhibition of Syk/PI3K reduced crystal-induced IL-1α/β production by approximately 80%. Activation of the downstream MAP kinases, MEK and ERK, was suppressed following inhibition of Syk and PI3K. Finally, inhibition of both Syk and PI3K significantly reduced cholesterol crystal-induced S100A8 and MMP1 gene expression by >70% while inhibition of PI3K also reduced S100A12 expression. Conclusion: Cholesterol crystals activate specific cell signalling pathways which drive the production of inflammatory cytokines and degradative enzymes known to contribute to disease initiation and progression. These molecular events are dependent on activation of Syk and PI3K, hence, they represent potential therapeutic targets for the treatment of cholesterol crystal-related pathologies. Highlights: Cholesterol crystals activate Syk and PI3 kinase in human innate immune cells. Cholesterol crystals drive IL-1 production in a Syk- and PI3K-dependent manner. Cholesterol crystals activate MAP kinases downstream of Syk and PI3 kinase. Cholesterol crystals induce S100 and MMP1 expression via tyrosine kinases.