PMC:3086762 / 19189-21786
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{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/3086762","sourcedb":"PMC","sourceid":"3086762","source_url":"https://www.ncbi.nlm.nih.gov/pmc/3086762","text":"To explore potential mechanisms through which dietary choline and its metabolites might exert their pro-atherosclerotic effects, C57BL/6J.Apoe−/− mice at time of weaning were placed on a normal chow diet supplemented with either choline, TMAO or betaine (for \u003e 3 weeks). Both mRNA levels (Supplementary Fig. 19) and surface protein levels (Figs. 4f, g; Supplementary Fig. 20) of two macrophage scavenger receptors implicated in atherosclerosis, CD36 and SR-A1, were then determined in peritoneal macrophages. Relative to normal chow diet, animals supplemented with either choline, TMAO or betaine all showed enhanced macrophage levels of CD36 and SR-A1. We next examined the impact of dietary choline and gut flora on endogenous formation of cholesterol-laden macrophage foam cells, one of the earliest cellular hallmarks of the atherosclerotic process. Hyperlipidemic C57BL/6J.Apoe−/− mice were fed diets with defined levels of choline as follows: (i) “control” (0.07–0.08%, wt/wt), which is similar to the choline content of normal chow (0.08–0.09%); versus (ii) high “choline”, corresponding to \u003e 10-fold higher level of choline (1.0%, wt/wt) than normal chow. Concomitantly, half of the mice were administered broad spectrum antibiotics for 3 weeks in order to suppress intestinal microflora, which was confirmed by the reduction of plasma TMAO levels by \u003e100-fold (plasma TMAO concentrations in groups receiving antibiotics were \u003c100 nM). While mice on the control diet showed modest evidence of endogenous macrophage foam cell formation, as indicated by oil-red-O staining of peritoneal macrophages, mice on the 1% choline supplemented diet showed markedly enhanced lipid-laden macrophage development (Fig. 5a). In contrast, suppression of intestinal flora significantly inhibited dietary choline-induced macrophage foam cell formation (Fig. 5a,b). These results were confirmed by microscopic quantification of endogenous foam cell levels (Fig. 5b), and analytical quantification of the cholesterol content of recovered macrophages (Fig. 5c). Histopathology and biochemical studies of livers recovered from these mice showed no evidence of steatosis (Supplementary Fig. 21). Parallel analyses of plasma PC metabolites also demonstrated no significant changes in choline or betaine levels between the different dietary groups, and significant increases of plasma TMAO levels only in mice on the high choline diet in the absence of antibiotics (males, control vs. choline diet, 2.5±0.1 μM vs. 28.3±2.4 μM, p\u003c0.001; for females, control vs. choline diet, 4.0±0.5 μM vs. 158.6±32.9 μM, p\u003c0.001).","tracks":[]}