gw-3965 and 7-ketocholesterol

Dyslipidemia causes renal damage; however, the detailed molecular mechanism has not been clarified. It is known that carnitine palmitoyl transferase 1-a (CPT1a) gene encodes an enzyme involved in fatty acid oxidation and, therefore, lipid content. In the present study, we investigated whether the accumulation of lipids induced by 7-ketocholesterol (7-KC) in tubular epithelial cells produce a fibrotic and inflammatory response through CPT1a.. Using an epithelial cell line, NRK-52E, we determine if intracellular accumulation of 7-KC modulates profibrotic and inflammatory events through CPT1a gene expression. In addition, the direct effects of CPT1a genetic modification has been studied.. Our results revealed that high levels of 7-KC induce increased expression of CPT1a, TGF-β1, α- SMA and NLRP3 that was correlated with lipid content. GW3965 treatment, which have shown to facilitate the efflux of cholesterol, eliminated the intracellular lipid droplets of 7-KC laden cells and decreased the expression of CPT1a, TGF-β1, α- SMA and NLRP3. Furthermore, CPT1a Knockdown and C75 pre-treatment increased lipid content but decreased TGF-β1, α- SMA and NLRP3.. Our findings reveal that the profibrotic effect of 7-KC on renal epithelial cells are mediated by CPT1a overexpression, which acts on TGF-β1, α-SMA and NLRP3. Thus, CPT1a downregulation protects against 7-KC-induced fibrosis in tubular epithelial cells by downregulating TGF-β1, α- SMA and NLRP3.

Topics: Animals; Benzoates; Benzylamines; Carnitine O-Palmitoyltransferase; Cell Line; Down-Regulation; Epithelial Cells; Fibrosis; Furans; Inflammasomes; Ketocholesterols; Kidney Tubules, Proximal; NLR Family, Pyrin Domain-Containing 3 Protein; Rats; Transforming Growth Factor beta1

Cholesterols are enriched in the brain and can be oxidized to oxysterols by several processes. Oxysterols are transport forms of cholesterols across cell membranes and the blood-brain barrier. Here, to elucidate the roles of oxysterols in brain inflammation, we treated lipopolysaccharide-stimulated rat brain astrocytes with two oxysterols, 7-ketocholesterol and 22(R)-hydroxycholesterol. Both oxysterols suppressed inducible nitric oxide synthase expression and nitric oxide release as well as upstream signaling molecules including interferon-beta, phosphorylated signal transducer and activator of transcription 1/3, and interferon regulatory factor-1. Oxysterols are known as liver X receptor agonists, and inhibitory effects were also observed with synthetic agonists of liver X receptor and retinoid X receptor. Thus, we conclude that it is most likely mediated by liver X receptor/retinoid X receptor heterodimers.

Topics: Animals; Animals, Newborn; Astrocytes; Benzoates; Benzylamines; Blotting, Western; Cells, Cultured; Cholesterol; Desmosterol; DNA-Binding Proteins; Dose-Response Relationship, Drug; Drug Interactions; Enzyme Activation; Enzyme Inhibitors; Gene Expression Regulation; Hydrocarbons, Fluorinated; Interferon Regulatory Factor-1; Interferon-beta; Ketocholesterols; Lipopolysaccharides; Liver X Receptors; Models, Biological; Nitric Oxide Synthase Type II; Orphan Nuclear Receptors; Rats; Receptors, Cytoplasmic and Nuclear; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sulfonamides