Exercise Training Favorably Modulates Gene and Protein Expression That Regulate Arterial Cholesterol Content in CETP Transgenic Mice.

Aerobic exercise training (AET) improves the reverse cholesterol transport (RCT) in cholesteryl ester transfer protein-transgenic (CETP-tg) mice. We aimed at investigating the role of AET in the expression of genes and proteins involved in lipid flux in the aorta and macrophages of CETP-tg mice. Three-month-old male mice were randomly divided into trained (T; treadmill 15 m/min; 30 min/day) and sedentary (S) groups. After 6 weeks, peritoneal macrophages and the aortic arch were obtained immediately (0 h) or 48 h after the last exercise session. mRNA was determined by RT-qPCR, protein levels by immunoblot and 14C-cholesterol efflux determined in macrophages. AET did not change body weight, plasma cholesterol, triglycerides, glucose and CETP activity. In macrophages, at time 0 h, a higher expression of genes that encode PPAR gamma, ABCA-1 and a lower expression of MCP-1 and IL-10, was observed in T as compared to S. After 48 h, lower expressions of MCP-1 and PPAR gamma genes were observed in T mice. Increase in ABCA-1, SR-BI and IL-6 and decrease of LOX-1, MCP-1, TNF and IL-10 gene expression was observed in the aorta of T compared to S mice (0 h) and LOX-1 and MCP-1 remained diminished after 48 h. The protein level of MCP-1 and SR-BI in the aortic arch was unchanged in T animals after 48 h as compared to S, but LOX-1 was reduced confirming data of gene expression. The apo A-I and the HDL2 mediated-cholesterol efflux (8 and 24 h) were not different between T and S animals. In the presence of CETP, AET positively influences gene expression in the arterial wall and macrophages of CETP-tg mice contributing to the RCT and prevention of atherosclerosis. These changes were perceptible immediately after the exercise session and were influenced by the presence of CETP although independent of changes in its activity. Reductions in gene and protein expression of LOX-1 were parallel and reflect the ability of exercise training in reducing the uptake of modified LDL by the arterial wall macrophages.

N-acetylcysteine Counteracts Adipose Tissue Macrophage Infiltration and Insulin Resistance Elicited by Advanced Glycated Albumin in Healthy Rats.

Background: Advanced glycation endproducts elicit inflammation. However, their role in adipocyte macrophage infiltration and in the development of insulin resistance, especially in the absence of the deleterious biochemical pathways that coexist in diabetes mellitus, remains unknown. We investigated the effect of chronic administration of advanced glycated albumin (AGE-albumin) in healthy rats, associated or not with N-acetylcysteine (NAC) treatment, on insulin sensitivity, adipose tissue transcriptome and macrophage infiltration and polarization. Methods: Male Wistar rats were intraperitoneally injected with control (C) or AGE-albumin alone, or, together with NAC in the drinking water. Biochemical parameters, lipid peroxidation, gene expression and protein contents were, respectively, determined by enzymatic techniques, reactive thiobarbituric acid substances, RT-qPCR and immunohistochemistry or immunoblot. Carboxymethyllysine (CML) and pyrraline (PYR) were determined by LC/mass spectrometry (LC-MS/MS) and ELISA. Results: CML and PYR were higher in AGE-albumin as compared to C. Food consumption, body weight, systolic blood pressure, plasma lipids, glucose, hepatic and renal function, adipose tissue relative weight and adipocyte number were similar among groups. In AGE-treated animals, insulin resistance, adipose macrophage infiltration and Col12a1 mRNA were increased with no changes in M1 and M2 phenotypes as compared to C-albumin-treated rats. Total GLUT4 content was reduced by AGE-albumin as compared to C-albumin. NAC improved insulin sensitivity, reduced urine TBARS, adipose macrophage number and Itgam and Mrc mRNA and increased Slc2a4 and Ppara. CD11b, CD206, Ager, Ddost, Cd36, Nfkb1, Il6, Tnf, Adipoq, Retn, Arg, and Il12 expressions were similar among groups. Conclusions: AGE-albumin sensitizes adipose tissue to inflammation due to macrophage infiltration and reduces GLUT4, contributing to insulin resistance in healthy rats. NAC antagonizes AGE-albumin and prevents insulin resistance. Therefore, it may be a useful tool in the prevention of AGE action on insulin resistance and long-term complications of DM.

Aerobic Exercise Training Selectively Changes Oxysterol Levels and Metabolism Reducing Cholesterol Accumulation in the Aorta of Dyslipidemic Mice.

Background: Oxysterols are bioactive lipids that control cellular cholesterol synthesis, uptake, and exportation besides mediating inflammation and cytotoxicity that modulate the development of atherosclerosis. Aerobic exercise training (AET) prevents and regresses atherosclerosis by the improvement of lipid metabolism, reverse cholesterol transport (RCT) and antioxidant defenses in the arterial wall. We investigated in dyslipidemic mice the role of a 6-week AET program in the content of plasma and aortic arch cholesterol and oxysterols, the expression of genes related to cholesterol flux and the effect of the exercise-mimetic AICAR, an AMPK activator, in macrophage oxysterols concentration. Methods: Sixteen-week old male apo E KO mice fed a chow diet were included in the protocol. Animals were trained in a treadmill running, 15 m/min, 5 days/week, for 60 min (T; n = 29). A control group was kept sedentary (S; n = 32). Plasma lipids and glucose were determined by enzymatic techniques and glucometer, respectively. Cholesterol and oxysterols in aortic arch and macrophages were measured by gas chromatography/mass spectrometry. The expression of genes involved in lipid metabolism was determined by RT-qPCR. The effect of AMPK in oxysterols metabolism was determined in J774 macrophages treated with 0.25 mM AICAR. Results: Body weight and plasma TC, TG, HDL-c, glucose, and oxysterols were similar between groups. As compared to S group, AET enhanced 7ß-hydroxycholesterol (70%) and reduced cholesterol (32%) in aorta. In addition, exercise increased Cyp27a1 (54%), Cd36 (75%), Cat (70%), Prkaa1 (40%), and Prkaa2 (51%) mRNA. In macrophages, the activation of AMPK followed by incubation with HDL2 increased Abca1 (52%) and Cd36 (220%) and decrease Prkaa1 (19%), Cyp27a1 (47%) and 7α-hydroxycholesterol level. Conclusion: AET increases 7ß-hydroxycholesterol in the aortic arch of dyslipidemic mice, which is related to the enhanced expression of Cd36. In addition, the increase and reduction of Cyp27a1 and Cyp7b1 in trained mice may contribute to enhance levels of 27-OH C. Both oxysterols may act as an alternative pathway for the RCT contributing to the reduction of cholesterol in the aortic arch preventing atherogenesis.

In type 2 diabetes mellitus glycated albumin alters macrophage gene expression impairing ABCA1-mediated cholesterol efflux.

Advanced glycation end products (AGE) are elevated in diabetes mellitus (DM) and predict the development of atherosclerosis. AGE-albumin induces oxidative stress, which is linked to a reduction in ABCA-1 and cholesterol efflux. We characterized the glycation level of human serum albumin (HSA) isolated from poorly controlled DM2 (n = 11) patients compared with that of control (C, n = 12) individuals and determined the mechanism by which DM2-HSA can interfere in macrophage lipid accumulation. The HSA glycation level was analyzed by MALDI/MS. Macrophages were treated for 18 h with C- or DM2-HSA to measure the (14) C-cholesterol efflux, the intracellular lipid accumulation and the cellular ABCA-1 protein content. Agilent arrays (44000 probes) were used to analyze gene expression, and the differentially expressed genes were validated by real-time RT-PCR. An increased mean mass was observed in DM2-HSA compared with C-HSA, reflecting the condensation of at least 5 units of glucose. The cholesterol efflux mediated by apo AI, HDL3 , and HDL2 was impaired in DM2-HSA-treated cells, which was related to greater intracellular lipid accumulation. DM2-HSA decreased Abcg1 mRNA expression by 26%. Abca1 mRNA was unchanged, although the final ABCA-1 protein content decreased. Compared with C-HAS-treated cells, NADPH oxidase 4 mRNA expression increased in cells after DM2-HSA treatment. Stearoyl-Coenzyme A desaturase 1, janus kinase 2, and low density lipoprotein receptor mRNAs were reduced by DM2-HSA. The level of glycation that occurs in vivo in DM2-HSA-treated cells selectively alters macrophage gene expression, impairing cholesterol efflux and eliciting intracellular lipid accumulation, which contribute to atherogenesis, in individuals with DM2.

N-acetylcysteine prevents endoplasmic reticulum stress elicited in macrophages by serum albumin drawn from chronic kidney disease rats and selectively affects lipid transporters, ABCA-1 and ABCG-1.

In chronic kidney disease (CKD) nontraditional risk factors, such as oxidative stress and advanced glycation end products (AGE) contribute to cardiovascular disease. Particularly, disturbances in reverse cholesterol transport favor the development of atherosclerosis. We analyzed the influence of N-acetylcysteine (NAC) in CKD rats on plasma concentration of lipid peroxides (TBARS) and AGE and on the impact of serum albumin in the development of macrophage endoplasmic reticulum stress (ERS) and cholesterol efflux, namely apo A-I and HDL2-mediated cholesterol removal and ABCA-1 and ABCG-1 protein level. CKD was induced by 5/6 nephrectomy in 2-month old male Wistar rats. Controls (Sham) were false operated. Animals were treated or not with NAC (600 mg/L of water). After 60 days serum albumin was isolated by FPLC and purified by alcoholic extraction. J774 macrophages were incubated with serum albumin (1 mg/mL; 18 h) from all groups, and the expression of ERS markers (protein disulfide isomerase - PDI, Grp78 and Grp94), ABCA-1 and ABCG-1 determined by immunoblot. HDL2 or apo A-I were used for cholesterol efflux assays. Protein and lipid composition of total HDL from Sham and CKD was determined and these particles tested on their abilities to accept cell cholesterol. Comparisons were done by one-way ANOVA and Newman Keuls post test. After 60 days of CKD, body weight was 10% lower in CKD compared to Sham (p < 0.01). This was prevented by NAC. Urea, creatinine, total cholesterol (TC), triglycerides (TG) (mg/dL), proteinuria (mg/24 h) (Sham, n = 31; Sham + NAC, n = 20; CKD, n = 74; CKD + NAC, n = 32), total AGE and pentosidine (n = 8; fluorescence arbitrary unit) and TBARS (n = 7; nmoL/mL) were higher in CKD (122 ± 8; 0.9 ± 0.07; 151 ± 6; 83 ± 4; 46 ± 2.5; 32,620 ± 673; 16,700 ± 1,370; 6.6 ± 0.5, respectively) and in CKD + NAC (91.4 ± 5; 0.6 ± 0.02; 126 ± 7.5; 73 ± 6; 51 ± 3.5; 24,720 ± 1,114; 10,080 ± 748; 4.5 ± 0.5, respectively) in comparison to Sham (41 ± 0.9; 0.4 ± 0.03; 76 ± 2.7; 51.5 ± 3; 14 ± 0.9; 21,750 ± 960; 5,314 ± 129; 2.0 ± 0.2, respectively; p < 0.001) and Sham + NAC (40 ± 0.9; 0.3 ± 0.02; 76 ± 2.6; 68 ± 4; 18.4 ± 1.5; 20,040 ± 700; 5,050 ± 267; 1.8 ± 0.2, respectively; p < 0.001). TC, urea, creatinine, total AGE, pentosidine and TBARS were respectively, 17%, 25%, 33%, 24%, 40% and 28% (p < 0.01) lower in CKD + NAC, than in CKD. Glycemia was higher in Sham + NAC (107 ± 4.6) and CKD + NAC (107 ± 2.6) than in Sham (96 ± 1.8; p < 0.05) and CKD (98 ± 1.6; p < 0.01), respectively. In macrophages (n = 6), CKD albumin increased PDI (3 and 6 times, p < 0.01) and Grp94 (66% and 80%, p < 0.01) in comparison to Sham and CKD + NAC-albumin treated cells, respectively. ABCA-1 expression was lower (87% and 70%, p < 0.001) in macrophage treated with Sham + NAC and CKD albumin respectively in comparison to Sham albumin; ABCG-1 was higher (4 and 7 times, p < 0.001) in macrophages treated with Sham + NAC and CKD + NAC albumin, respectively in comparison to Sham and CKD albumin. Apo A-I mediated cholesterol efflux was lower (59% and 70%, p < 0.0001) in macrophage treated with Sham + NAC and CKD albumin respectively in comparison to Sham albumin, however, the HDL2 mediated cholesterol efflux was higher (54% and 25%, p < 0.0001) in macrophage treated with Sham + NAC albumin, in comparison to Sham and CKD + NAC albumin, respectively. CKD-HDL was enriched in total protein and lipids compared to Sham-HDL but preserved its capacity to remove cholesterol from macrophages. NAC reduces plasma lipid peroxidation and AGE and abrogates ERS induced by CKD-albumin. Despite diminishing ABCA-1, NAC increases ABCG-1 that counteracts the reduction in apo A-I-mediated cholesterol efflux. NAC may contribute to attenuate the deleterious effects of CKD-albumin on lipid accumulation in macrophages helping to prevent atherogenesis in CKD.

Advanced glycated albumin isolated from poorly controlled type 1 diabetes mellitus patients alters macrophage gene expression impairing ABCA-1-mediated reverse cholesterol transport.

BACKGROUND: We evaluated the effects of albumin isolated from control individuals and from patients with poorly controlled type 1 diabetes mellitus on macrophage gene expression and on reverse cholesterol transport. METHODS: Serum albumin was purified from control subjects (n = 12) and from patients with poorly controlled type 1 diabetes mellitus (n = 13). (14)C-cholesterol-labelled J774 macrophages treated with albumin were employed to measure cholesterol efflux mediated by apo A-I, HDL(3) or HDL(2), the intracellular lipid accumulation and the cellular ABCA-1 protein content. Agilent arrays (44000 probes) were used to analyse gene expression. Several differentially expressed genes were validated by real-time reverse transcription-PCR using TaqMan Two Step RT-PCR. RESULTS: Levels of glycation-modified and (carboxymethyl)lysine-modified albumin were higher in diabetic patients than in control subjects. Apo A-I-mediated and HDL(2)-mediated cellular cholesterol efflux were impaired in macrophages treated with albumin from diabetic patients in comparison with control albumin-treated cells, which was attributed to the reduction in ABCA-1 protein content. Even in the presence of cholesterol acceptors, a higher level of intracellular lipid was observed in macrophages exposed to albumin from diabetic individuals in comparison with the control. The reduction in ABCA-1 content was associated with enhanced expression of stearoyl CoA desaturase 1 and decreased expression of janus kinase 2, which were induced by albumin from patients with type 1 diabetes mellitus. CONCLUSIONS: (Carboxymethyl)lysine-modified albumin isolated from poorly controlled type 1 diabetic patients impairs ABCA-1-mediated reverse cholesterol transport and elicits intracellular lipid accumulation, possibly contributing to atherosclerosis.

Advanced glycation in macrophages induces intracellular accumulation of 7-ketocholesterol and total sterols by decreasing the expression of ABCA-1 and ABCG-1.

BACKGROUND: Advanced glycation end products (AGE) alter lipid metabolism and reduce the macrophage expression of ABCA-1 and ABCG-1 which impairs the reverse cholesterol transport, a system that drives cholesterol from arterial wall macrophages to the liver, allowing its excretion into the bile and feces. Oxysterols favors lipid homeostasis in macrophages and drive the reverse cholesterol transport, although the accumulation of 7-ketocholesterol, 7alpha- hydroxycholesterol and 7beta- hydroxycholesterol is related to atherogenesis and cell death. We evaluated the effect of glycolaldehyde treatment (GAD; oxoaldehyde that induces a fast formation of intracellular AGE) in macrophages overloaded with oxidized LDL and incubated with HDL alone or HDL plus LXR agonist (T0901317) in: 1) the intracellular content of oxysterols and total sterols and 2) the contents of ABCA-1 and ABCG-1. METHODS: Total cholesterol and oxysterol subspecies were determined by gas chromatography/mass spectrometry and HDL receptors content by immunoblot. RESULTS: In control macrophages (C), incubation with HDL or HDL + T0901317 reduced the intracellular content of total sterols (total cholesterol + oxysterols), cholesterol and 7-ketocholesterol, which was not observed in GAD macrophages. In all experimental conditions no changes were found in the intracellular content of other oxysterol subspecies comparing C and GAD macrophages. GAD macrophages presented a 45% reduction in ABCA-1 protein level as compared to C cells, even after the addition of HDL or HDL + T0901317. The content of ABCG-1 was 36.6% reduced in GAD macrophages in the presence of HDL as compared to C macrophages. CONCLUSION: In macrophages overloaded with oxidized LDL, glycolaldehyde treatment reduces the HDL-mediated cholesterol and 7-ketocholesterol efflux which is ascribed to the reduction in ABCA-1 and ABCG-1 protein level. This may contribute to atherosclerosis in diabetes mellitus.

HDL atheroprotection by aerobic exercise training in type 2 diabetes mellitus.

PURPOSE: In this study we analyzed the role played by aerobic exercise training in the plasma lipoprotein profile, prebeta 1-HDL concentration, and in the in vitro HDL3 ability to remove cholesterol from macrophages and inhibit LDL oxidation in type 2 diabetes mellitus (DM) patients and control subjects, in the fasting and postprandial states. METHODS: Healthy controls (HTC, N = 11; 1 M/10 F) and subjects with type 2 diabetes mellitus (DMT, N = 11; 3M/8F) were engaged in a 4-month aerobic training program, and compared with a group of sedentary subjects with type 2 diabetes mellitus (DMS, N = 10; 4 M/6 F). All groups were submitted to an oral fat load test to analyze all parameters, both at the beginning of the investigation protocol (basal) and at the end of the study period (final). RESULTS: Exercising did not modify body weight, BMI, plasma concentrations of total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides (TG), glucose, insulin, or HOMA-IR, but it reduced the waist circumference. The HDL3 composition did not change, and its ability to remove cell cholesterol was unaltered by aerobic training. In DMT but not in HTC, aerobic training improved 15% the HDL3 protective effect against LDL maximal oxidation rate in the fasting state, and reduced 24% the plasma prebeta 1-HDL concentration in the postprandial state, suggesting an enhanced prebeta 1-HDL conversion into larger, more mature HDL particles. In this regard, regular aerobic exercise enriched HDL2 with TG in the fasting and postprandial states in HTC and in the fasting phase in DMT. CONCLUSION: Our results show that aerobic exercise training in diabetes mellitus improves the HDL efficiency against LDL oxidation and favors HDL maturation. These findings were independent of changes in insulin resistance and of the rise of plasma HDL cholesterol concentration.