Lowering apolipoprotein CIII protects against high-fat diet–induced metabolic derangements

Figures

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  Fig. 1. Lowering apoCIII in mice on HFD improves the metabolic status. (A) Body weight (BW). Black arrow indicates start of ASO treatment in the prevention study (week 0), and white arrow in the reversibility study (week 10, N = 10 to 11). (B and C) Representative pictures of mice treated for (B) 14 weeks with Scr (left) and ASO (right) and (C) 4 weeks with Scr (left) and ASO (right). (D) Fat–to–lean mass ratio analyzed with NMR (N = 6). (E) Twelve-hour fasting plasma leptin levels (N = 4). (F) Liver mRNA levels of apoCIII analyzed by qRT-PCR (N = 10). (G and H) Representative immunoblots and densitometry analysis of apoCIII in (G) liver and (H) plasma (N = 7 and 6, respectively). (I to N) Parameters evaluated in metabolic cages (CLAMS) at the end of the studies (N = 7 to 8). (I) Calorie intake. (J) Locomotion (x and y axes). (K) Oxygen consumption (VO2). (L) Carbon dioxide production (VCO2). (M) Respiratory exchange ratio (RER). (N) Calculated energy expenditure (EE). Data are presented as mean ± SEM. *ASO 14w versus Scr 14w; #ASO 4w versus Scr 4w. Single symbol, P < 0.05; double symbol, P < 0.01; and triple symbol, P < 0.001. Photo credit: Ismael Valladolid-Acebes, The Rolf Luft…

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  Fig. 2. Lowering apoCIII affects BAT and improves glucose homeostasis and insulin sensitivity. (A) BAT mRNA levels of ADRB3 analyzed by qRT-PCR (N = 6). (B) Body temperature (N = 6). (C) Representative images of hematoxylin and eosin–stained cryosections from BAT. Scale bar, 50 μm (N = 4). (D) LPL activity in BAT (N = 6). (E) Expression of thermogenic genes in BAT by qRT-PCR (N = 6). (F to I) In vivo metabolic tests performed at the end of the studies. Injection of bolus doses is indicated with arrows (black, glucose; blue, insulin; and green, pyruvate). (F) Glucose tolerance test (IPGTT; N = 6), (G) glucose-stimulated insulin secretion (GSIS) during IPGTT (N = 4), (H) insulin tolerance test (IPITT; N = 6), and (I) pyruvate tolerance test (IPPTT; N = 4 to 5. (J to L) Twelve-hour fasting levels of (J) blood glucose (N = 4 to 5), (K) plasma insulin (N = 4), and (L) plasma glucagon (N = 4). (M) Liver mRNA levels of G-6-P analyzed by qRT-PCR (N = 6). Data are presented as mean ± SEM. *ASO 14w versus Scr 14w; #ASO 4w versus Scr 4w. Single symbol, P < 0.05; double symbol, P < 0.01; and triple symbol, P < 0.001.

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  Fig. 3. Liver function in ASO-treated mice on HFD. (A) Hepatic lipase (HL) activity in liver samples (N = 6). (B) Gene expression levels of receptors involved in hepatic lipid clearance by qRT-PCR (N = 5 to 6). (C and D) Representative chromatograms for Tg lipid profiles measured in VLDL and chylomicron–, IDL/LDL-, HDL-, and glycerol-eluted plasma fractions at the end of (C) prevention and (D) reversibility study (N = 6). (E) Representative images of ORO-stained cryosections from liver. Nuclei counterstained with hematoxylin. Scale bar, 100 μm (N = 4). (F) Spectrophotometric measurements of liver Tg content (N = 6). (G and H) Nonfasting plasma (G) AST and (H) ALT (N = 6). Data are presented as mean ± SEM. *ASO 14w versus Scr 14w; #ASO 4w versus Scr 4w. Single symbol, P < 0.05; double symbol, P < 0.01; and triple symbol, P < 0.001.

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  Fig. 4. Lipid catabolism and ketogenesis. (A) Expression levels of genes involved in liver lipid catabolism by qRT-PCR (N = 6). (B) In vivo FAO (N = 7 to 8). (C) Expression levels of genes involved in liver ketogenesis and ketone transport by qRT-PCR (N = 6). (D and E) Nonfasting plasma levels of (D) ACAC (N = 5) and (E) BHB (N = 5). (F) Expression levels of genes involved in BAT ketone transport and ketolysis, as well as BAT lipid catabolism by qRT-PCR (N = 6). Data are presented as mean ± SEM. *ASO 14w versus Scr 14w; #ASO 4w versus Scr 4w. Single symbol, P < 0.05; double symbol, P < 0.01; and triple symbol, P < 0.001.

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  Fig. 5. ApoCIII reduction reverses the metabolic phenotype induced by HFD. (A) Body weight (BW). Black arrow indicates start of ASO treatment (week 10, N = 12). (B) Representative pictures of mice from the long-lasting reversibility study treated for 14 weeks with Scr (left) and ASO (right). (C) PgAT weight in relation to BW (N = 7). (D and E) Twelve-hour fasting plasma levels of (D) leptin (N = 4) and (E) adiponectin (N = 6). (F) Liver mRNA levels of apoCIII analyzed by qRT-PCR (N = 4). (G and H) Representative immunoblots and densitometry analysis of apoCIII in (G) liver and (H) plasma (N = 4). (I to K) In vivo metabolic tests performed at the end of the study. Injection of bolus doses is indicated with arrows (black, glucose; blue, insulin; and green, pyruvate). (I) IPGTT (N = 5), (J) IPITT (N = 5), and (K) IPPTT (N = 5). (L) Twelve-hour fasting plasma glucagon levels (N = 4). (M) Representative chromatograms for Tg lipid profiles measured in VLDL and chylomicron–, IDL/LDL-, HDL-, and glycerol-eluted plasma fractions at the end of the study (N = 7). (N) Spectrophotometric measurements of liver Tg content (N = 7). (O and P) Nonfasting plasma (O) AST (N = 5) and (P) ALT (N = 5). Data…

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  Fig. 6. Schematic overview of the beneficial metabolic effects of lowering apoCIII in vivo under HFD conditions. Targeting apoCIII protects against HFD-induced metabolic derangements by increasing lipolysis (1), hepatic clearance of circulating lipids (2), liver lipid catabolism (3), and shifting liver metabolism toward ketogenesis (4). The ketones are taken up (5 and 6) and used for energy production in BAT (7 to 9). LP-Rs, lipoprotein receptors; ECF, extracellular fluid.