The Impairment of Macrophage-to-Feces Reverse Cholesterol Transport during Inflammation Does Not Depend on Serum Amyloid A
Figure 4
SAA has little impact on the impairment in biliary and fecal excretion of macrophage-derived 3H-cholesterol during endotoxemia. WT and SAAKO mice were injected subcutaneously with PBS or 0.8 μg/g LPS as indicated, followed 4 hr later by intraperitoneal injection of 3H-cholesterol-labeled J774 macrophages. (a) Radioactivity in bile was determined 24 hr after macrophage injection. The data shown are compiled from 3 separate experiments (n = 4-5 per group per experiment) and normalized to the PBS-injected WT mice. Values are the mean ± SEM; *%. For each of the 3 experiments, the amount of radioactivity recovered in the bile of PBS-injected WT and SAAKO mice was similar, ranging from 0.01% to 0.04% of injected tracer per μL of bile. (b) Feces were collected during the 24 hr RCT experiments, and the total amount of radioactivity was determined. Due to methodological issues in one of the experiments, data from only 2 experiments were compiled (n = 5 per group per experiment) and normalized to the PBS-injected WT mice. Values are the mean ± SEM; ***; *. For each of the 2 experiments, the amount of radioactivity recovered in feces of PBS-injected WT and SAAKO mice was similar, ranging from 1.8%–2.6% of the injected tracer. (c) ABCG1 in liver lysates (40 μg protein) was identified by immunoblotting and quantified by densitometry. Results from each of the 3 experiments (n = 4-5 per group per experiment) were expressed relative to PBS-injected WT mice after normalization to β-actin. A representative western blot is shown. (d) ABCG5 in liver membranes (50 μg protein) was detected by immunoblotting and quantified by densitometry. Results from each of the 3 experiments (n = 4-5 per group per experiment) were expressed relative to PBS-injected WT mice after normalization to calnexin. A representative western blot is shown, with the immature (reticular) and mature (post-Golgi) forms of ABCG5 indicated with a carat. The band indicated by an asterisk is observed in G5G8-deficient mice suggesting that it represents a nonspecific signal [23].
