CD36 Inhibitors Reduce Postprandial Hypertriglyceridemia and Protect against Diabetic Dyslipidemia and Atherosclerosis

CD36 is recognized as a lipid and fatty acid receptor and plays an important role in the metabolic syndrome and associated cardiac events. The pleiotropic activity and the multiple molecular associations of this scavenger receptor with membrane associated molecules in different cells and tissues have however questioned its potential as a therapeutic target. The present study shows that it is possible to identify low molecular weight chemicals that can block the CD36 binding and uptake functions. These inhibitors were able to reduce arterial lipid deposition, fatty acid intestinal transit, plasma concentration of triglycerides and glucose, to improve insulin sensitivity, glucose tolerance and to reduce the plasma concentration of HbAc1 in different and independent rodent models. Correlation between the anti-CD36 activity of these inhibitors and the known pathophysiological activity of this scavenger receptor in the development of atherosclerosis and diabetes were observed at pharmacological doses. Thus, CD36 might represent an attractive therapeutic target

Effect of CD36 inhibitor on the metabolic syndrome parameters.

<p>A: effect of AP5258 on OGT, B: Effect of 5258 on insulin sensitivity, C: Effect of AP5055 on plasma glucose, D: Effect of 5055 on the plasma concentration of HbAc1.</p

Inhibition of ppTG in the plasma at four hours following the olive oil gavage following administration of 50 mg/kg of active (AP5055, AP5258) or inactive (AP5156) analogues.

<p>Inhibition of ppTG in the plasma at four hours following the olive oil gavage following administration of 50 mg/kg of active (AP5055, AP5258) or inactive (AP5156) analogues.</p

Reduction of plasma triglycerides.

<p>Comparative effect of CD36 inhibitors on the plasma concentrations of TG in different rat models, A: Dose dependent reduction in a fructose fed rat, AP5055 was administrated at different doses for 3 w (n = 12), B: AP5258 was administrated to diabetic ZDF rats (C = Control, T = Treated) for a period of 2w at 10 mg/kg (n = 8).</p

Anti-CD36 activity.

<p>Effect of AP5055 on the molecular interaction between CD36 and ox-LDL using CD36-HEK and wild type (wt) cells at 4°C. A: effect on the electrophoretic mobility of ox-LDL, B: Affinity crosslinking of ox-LDL to membrane expressed CD36, biotinylated ox-LDL were cross linked at 4°C, the ox-LDL complex was immunoprecipitated with an anti ox-LDL antibody and complex-associated CD36 was detected on immunoblot, using an anti CD36 antibody.</p

Anti-CD36 activity of AP5055 (dark) and AP5258 (grey) on CD36-HEK cells.

<p>Non transfected cells (wt), were used as control: A: ox-LDL uptake at 37°C, B: Palmitate uptake at 37°C, C: typical inhibition of ox-LDL binding at 4°C, D: dose dependent inhibition of AP 5055 and AP5258 on ox-LDL binding, AP5156 used as negative control had no effect (hatched bar), E: Comparative inhibition of ox-LDL binding by AP5055 and AP5258 at different ox-LDL concentrations.</p

Chemical structures and activities of the CD36 inhibitors AP 5055, AP 5258 and the negative analog AP5156.

<p>Dose dependent inhibition of ox-LDL uptake and accumulation by THP1 cells at 37°C. Uptake was measured as the cyanin3 labeled ox-LDL uptake at constant cell number.</p

Protection against atherosclerosis.

<p>Effect of AP 5055 on the development of atherosclerosis in double LDL-R and Leptin deficient mice (DKO). A: lipid deposition in the aorta, B: plaque volume, C: plasma TG concentration.</p

Oxidized low-density lipoprotein correlates positively with toll-like receptor 2 and interferon regulatory factor-1 and inversely with superoxide dismutase-1 expression: studies in hypercholesterolemic swine and THP-1 cells

BACKGROUND: Oxidized low-density lipoprotein (LDL) is associated with cardiovascular disease. Macrophages contribute to LDL oxidation, and oxidized LDL (oxLDL) affects macrophage function. We searched for the strongest gene correlates of oxLDL in macrophages in coronary plaques and studied the effect of oxLDL on their expression in THP-1 cells. METHODS AND RESULTS: Gene expression in macrophages isolated from coronary plaque macrophages from hypercholesterolemic swine was measured on Agilent Human cDNA microarrays. Compared with a universal reference, 1653 transcripts were deregulated. The expression of 11 genes correlated positively and the expression of 5 genes correlated negatively with plaque oxLDL. Interferon regulatory factor-1 (IRF1; R2 = 0.69) and toll-like receptor 2 (TLR2; R2 = 0.18) were the strongest positive correlates of oxLDL. Superoxide dismutase 1 (SOD1) was the strongest inverse correlate of oxLDL (R2 = 0.57). Immunohistochemical analysis showed colocalization of IRF1, TLR2, and SOD1 protein in macrophages and confirmed the RNA expression data. OxLDL-induced foam cell formation in THP-1 macrophages was associated with increased expression of IRF1 and TLR2 and decreased expression of SOD1. CONCLUSIONS: Our data support the hypothesis that oxLDL is a proinflammatory stimulus that induces the expression of TLR2 and IRF1, 2 important gene regulators of innate immune response, and inhibits the expression of the antioxidant SOD1