The effects of saturated fat intake from dairy on CVD markers: the role of food matrices.

CVD is the leading cause of death worldwide, and is commonly associated with modifiable risk factors. Most studies to date examining link between food intake and risk of CVD, have focused on modulation of plasma cholesterol concentrations (total cholesterol (TC), LDL-C). However, recent studies suggest LDL particle size is a more sensitive risk marker for CVD with smaller, dense LDL particles reported as more atherogenic than larger, more buoyant LDL. Although dietary guidelines recommend SFA intake of < 10 % of total energy, this does not consider food source, with recent evidence suggesting differing, sometimes beneficial, lipid responses following consumption of SFA from dairy compared to other food sources. This may be from differences in the physical food matrices, the nutrient content of the foods, and/or how these components interact with each other, described as a 'dairy matrix effect'. Dietary fat not only raises LDL-C, but also HDL cholesterol (HDL-C), associated with reduced CVD risk. HDL particles are complex emulsions of lipids, proteins and microRNAs that exhibit atheroprotective properties. In addition, HDL particles exhibit a very heterogeneous proteomic composition, dependent on a person's disease state - with a more pro-inflammatory proteome evident in patients with established CVD. This review will discuss the evidence to date on the importance of the food matrix in modulating response to dietary SFA and impact on CVD risk factors. A focus on potential biomarker properties of lipoprotein particles beyond cholesterol and current use of such biomarkers in human nutrition research will be considered.

Precision nutrition for targeting pathophysiology of cardiometabolic phenotypes.

Obesity is a heterogenous disease accompanied by a broad spectrum of cardiometabolic risk profiles. Traditional paradigms for dietary weight management do not address biological heterogeneity between individuals and have catastrophically failed to combat the global pandemic of obesity-related diseases. Nutritional strategies that extend beyond basic weight management to instead target patient-specific pathophysiology are warranted. In this narrative review, we provide an overview of the tissue-level pathophysiological processes that drive patient heterogeneity to shape distinct cardiometabolic phenotypes in obesity. Specifically, we discuss how divergent physiology and postprandial phenotypes can reveal key metabolic defects within adipose, liver, or skeletal muscle, as well as the integrative involvement of the gut microbiome and the innate immune system. Finally, we highlight potential precision nutritional approaches to target these pathways and discuss recent translational evidence concerning the efficacy of such tailored dietary interventions for different obesity phenotypes, to optimise cardiometabolic benefits.

Role of food matrix in modulating dairy fat induced changes in lipoprotein particle size distribution in a human intervention.

BACKGROUND: Intake of dairy fat within the matrix of cheese lowered circulating LDL cholesterol concentration to a greater extent than the same components consumed separately as butter, protein, and calcium. However, circulating LDL cholesterol is not indicative of concentration or size of LDL particles (LDL-P), which are recognized as more sensitive risk markers of CVD. OBJECTIVES: This was an exploratory analysis to investigate the role of the food matrix on lipoprotein particle size distribution, after a dairy fat intervention, in overweight adults aged ≥50 y. METHODS: Lipoprotein particle size distribution was measured in fasting EDTA blood samples taken at week 0 (baseline) and at week 6, using NMR. In total, 127 participants (BMI ≥ 25 kg/m2, aged ≥50 y) received ∼42 g dairy fat in 1 of 4 treatments: group A, 120 g full-fat cheddar cheese (FFCC); group B, reduced-fat cheese plus butter (RFC+B); group C, butter, calcium caseinate powder, and calcium supplement (CaCO3) (BCC); or group D, 120 g FFCC (as per group A) but after a 6-wk washout period during which they excluded cheese before intervention. RESULTS: Total VLDL and chylomicron particles (VLDL/CM-P) decreased after intervention. There was a strong correlation between reduced VLDL/CM-P and a reduction in small proatherogenic VLDL-P (r = 0.888, P < 0.001). Reductions in total LDL-P were associated with a reduction in small LDL-P and, to a lesser extent, with large LDL-P. There was a significant main effect of treatment for change in intermediate-density lipoprotein particles (IDL-P) after the intervention (P = 0.023) between groups B and D (-46.86 ± 30.38 and 40.69 ± 32.72 nmol/L, respectively). HDL particle (HDL-P) parameters (diameter, concentration, or size distribution) were not affected by diet. CONCLUSIONS: Our findings indicate that reductions in LDL cholesterol observed with dairy fat consumption are driven by reductions in LDL-P concentration. A trend toward a less atherogenic profile was observed, but there was no clear effect of the individual food matrices. This trial was registered at ISRCTN as ISRCTN86731958.

Palmitic Acid and Oleic Acid Differently Modulate TLR2-Mediated Inflammatory Responses in Microglia and Macrophages.

The relationship between systemic immunity and neuroinflammation is widely recognised. Infiltration of peripheral immune cells to the CNS during certain chronic inflammatory states contributes significantly to neuropathology. Obesity and its co-morbidities are primary risk factors for neuroinflammatory and neurodegenerative conditions, including Alzheimer's disease (AD). Dietary fats are among the most proinflammatory components of the obesogenic diet and play a prominent role in the low-grade systemic inflammation associated with the obese state. Saturated fatty acid (SFA) is largely implicated in the negative consequences of obesity, while the health benefits of monounsaturated fatty acid (MUFA) are widely acknowledged. The current study sought to explore whether SFA and MUFA differently modulate inflammatory responses in the brain, compared with peripheral immune cells. Moreover, we assessed the neuroinflammatory impact of high-fat-induced obesity and hypothesised that a MUFA-rich diet might mitigate inflammation despite obesogenic conditions. Toll-like receptor (TLR)2 mediates the inflammation associated with both obesity and AD. Using the TLR2 agonist lipoteichoic acid (LTA), we report that pre-exposure to either palmitic acid (PA) or oleic acid (OA) attenuated cytokine secretion from microglia, but heightened sensitivity to nitric oxide (NO) production. The reduction in cytokine secretion was mirrored in LTA-stimulated macrophages following exposure to PA only, while effects on NO were restricted to OA, highlighting important cell-specific differences. An obesogenic diet over 12 weeks did not induce prominent inflammatory changes in either cortex or hippocampus, irrespective of fat composition. However, we reveal a clear disparity in the effects of MUFA under obesogenic and non-obesogenic conditions.

Sodium salicylate rewires hepatic metabolic pathways in obesity and attenuates IL-1ß secretion from adipose tissue: The implications for obesity-impaired reverse cholesterol transport.

INTRODUCTION: High-fat diet (HFD)-induced obesity impairs clearance of cholesterol through the Reverse Cholesterol Transport (RCT) pathway, with downregulation in hepatic expression of cholesterol and bile acid transporters, namely ABCG5/8 and ABCB11, and reduced high-density lipoprotein (HDL) cholesterol efflux capacity (CEC). In the current study, we hypothesized that the development of hepatosteatosis, secondary to adipose-tissue dysfunction, contributes to obesity-impaired RCT and that such effects could be mitigated using the anti-inflammatory drug sodium salicylate (NaS). MATERIALS AND METHODS: C57BL/6J mice, fed HFD ± NaS or low-fat diet (LFD) for 24 weeks, underwent glucose and insulin tolerance testing. The 3H-cholesterol movement from macrophage-to-feces was assessed in vivo. HDL-CEC was determined ex vivo. Cytokine secretion from adipose-derived stromal vascular fraction (SVF) cells was measured ex vivo. Liver and HDL proteins were determined by mass spectrometry and analyzed using Ingenuity Pathway Analysis. RESULTS: NaS delayed HFD-induced weight gain, abrogated priming of pro-IL-1ß in SVFs, attenuated insulin resistance, and prevented steatohepatitis (ectopic fat accumulation in the liver). Prevention of hepatosteatosis coincided with increased expression of PPAR-alpha/beta-oxidation proteins with NaS and reduced expression of LXR/RXR-induced proteins including apolipoproteins. The latter effects were mirrored within the HDL proteome in circulation. Despite remarkable protection shown against steatosis, HFD-induced hypercholesterolemia and repression of the liver-to-bile cholesterol transporter, ABCG5/8, could not be rescued with NaS. DISCUSSIONS AND CONCLUSIONS: The cardiometabolic health benefits of NaS may be attributed to the reprogramming of hepatic metabolic pathways to increase fatty acid utilization in the settings of nutritional overabundance. Reduced hepatic cholesterol levels, coupled with reduced LXR/RXR-induced proteins, may underlie the lack of rescue of ABCG5/8 expression with NaS. This remarkable protection against HFD-induced hepatosteatosis did not translate to improvements in cholesterol homeostasis.

Microbiome Transfer Partly Overrides Lack of IL-1RI Signaling to Alter Hepatic but not Adipose Tissue Phenotype and Lipid Handling following a High-Fat Diet Challenge.

SCOPE: IL-1RI-mediated inflammatory signaling alters metabolic tissue responses to dietary challenges (e.g., high-fat diet [HFD]). Recent work suggests that metabolic phenotype is transferrable between mice in a shared living environment (i.e., co-housing) due to gut microbiome exchange. The authors examine whether the metabolic phenotype of IL-1RI-/- mice fed HFD or low-fat diet (LFD) could be transferred to wild-type (WT) mice through gut microbiome exchange facilitated by co-housing. METHODS AND RESULTS: Male WT (C57BL/J6) and IL-1RI-/- mice are fed HFD (45% kcal) or LFD (10% kcal) for 24 weeks and housed i) by genotype (single-housed) or ii) with members of the other genotype in a shared microbial environment (co-housed). The IL-1RI-/-  gut microbiome is dominant to WT, meaning that co-housed WT mice adopted the IL-1RI-/- microbiota profile. This is concomitant with greater body weight, hepatic lipid accumulation, adipocyte hypertrophy, and hyperinsulinemia in co-housed WT mice, compared to single-housed counterparts. These effects are most evident following HFD. Primary features of microbiome differences are Lachnospiraceae and Ruminococcaceae (known producers of SCFA). CONCLUSION: Transfer of SCFA-producing microbiota from IL-1RI-/- mice highlights a new connection between diet, inflammatory signaling, and the gut microbiome, an association that is dependent on the nature of the dietary fat challenge.

HDL particle size is increased and HDL-cholesterol efflux is enhanced in type 1 diabetes: a cross-sectional study.

AIMS/HYPOTHESIS: The prevalence of atherosclerosis is increased in type 1 diabetes despite normal-to-high HDL-cholesterol levels. The cholesterol efflux capacity (CEC) of HDL is a better predictor of cardiovascular events than static HDL-cholesterol. This cross-sectional study addressed the hypothesis that impaired HDL function contributes to enhanced CVD risk within type 1 diabetes. METHODS: We compared HDL particle size and concentration (by NMR), total CEC, ATP-binding cassette subfamily A, member 1 (ABCA1)-dependent CEC and ABCA1-independent CEC (by determining [3H]cholesterol efflux from J774-macrophages to ApoB-depleted serum), and carotid intima-media thickness (CIMT) in 100 individuals with type 1 diabetes (37.6 ± 1.2 years; BMI 26.9 ± 0.5 kg/m2) and 100 non-diabetic participants (37.7 ± 1.1 years; 27.1 ± 0.5 kg/m2). RESULTS: Compared with non-diabetic participants, total HDL particle concentration was lower (mean ± SD 31.01 ± 8.66 vs 34.33 ± 8.04 µmol/l [mean difference (MD) -3.32 µmol/l]) in participants with type 1 diabetes. However, large HDL particle concentration was greater (9.36 ± 3.98 vs 6.99 ± 4.05 µmol/l [MD +2.37 µmol/l]), resulting in increased mean HDL particle size (9.82 ± 0.57 vs 9.44 ± 0.56 nm [MD +0.38 nm]) (p < 0.05 for all). Total CEC (14.57 ± 2.47%CEC/4 h vs 12.26 ± 3.81%CEC/4 h [MD +2.31%CEC/4 h]) was greater in participants with type 1 diabetes relative to non-diabetic participants. Increased HDL particle size was independently associated with increased total CEC; however, following adjustment for this in multivariable analysis, CEC remained greater in participants with type 1 diabetes. Both components of CEC, ABCA1-dependent (6.10 ± 2.41%CEC/4 h vs 5.22 ± 2.57%CEC/4 h [MD +0.88%CEC/4 h]) and ABCA1-independent (8.47 ± 1.79% CEC/4 h vs 7.05 ± 1.76% CEC/4 h [MD +1.42% CEC/4 h]) CEC, were greater in type 1 diabetes but the increase in ABCA1-dependent CEC was less marked and not statistically significant in multivariable analysis. CIMT was increased in participants with type 1 diabetes but in multivariable analysis it was only associated negatively with age and BMI. CONCLUSIONS/INTERPRETATION: HDL particle size but not HDL-cholesterol level is independently associated with enhanced total CEC. HDL particle size is greater in individuals with type 1 diabetes but even after adjusting for this, total and ABCA1-independent CEC are enhanced in type 1 diabetes. Further studies are needed to understand the mechanisms underlying these effects, and whether they help attenuate progression of atherosclerosis in this high-risk group. Graphical abstract.

Metabolic Inflammation in Obesity-At the Crossroads between Fatty Acid and Cholesterol Metabolism.

Metabolic inflammation is a classic hallmark of obesity that is associated with numerous cardiometabolic complications. Disturbances in fatty acid and cholesterol metabolism are evident in obesity and likely intricately linked to the development and/or sustainment of metabolic inflammation and insulin resistance. Elevations in triglyceride-rich lipoproteins and reductions in high-density lipoprotein-cholesterol in turn are two major disturbances that accompany obesity. How metabolic dyslipidemia may contribute to metabolic inflammation is discussed. How aberrant cholesterol homeostasis coupled with excessive fatty acid accumulation prime pro-IL-1ß and the evidence to support a synergistic partnership between cholesterol and fatty acids in driving metabolic inflammation are also discussed. Further, pharmaceutical and nutraceutical strategies aimed at attenuating low-grade inflammation and implications for cardiometabolic complications of obesity are reviewed. The current literature on the importance of the local tissue microenvironment in activating adipose tissue macrophages within obese adipose tissue and the contribution of these local immune cells to metabolic inflammation is reviewed. Finally, the limitations to current biomarkers of metabolic inflammation and the importance of novel sensitive biomarkers in driving obesity sub-type characterization to direct personalized medicine approaches to obesity treatment in the future are discussed.

Dietary substitution of SFA with MUFA within high-fat diets attenuates hyperinsulinaemia and pancreatic islet dysfunction.

Preliminary evidence has suggested that high-fat diets (HFD) enriched with SFA, but not MUFA, promote hyperinsulinaemia and pancreatic hypertrophy with insulin resistance. The objective of this study was to determine whether the substitution of dietary MUFA within a HFD could attenuate the progression of pancreatic islet dysfunction seen with prolonged SFA-HFD. For 32 weeks, C57BL/6J mice were fed either: (1) low-fat diet, (2) SFA-HFD or (3) SFA-HFD for 16 weeks, then switched to MUFA-HFD for 16 weeks (SFA-to-MUFA-HFD). Fasting insulin was assessed throughout the study; islets were isolated following the intervention. Substituting SFA with MUFA-HFD prevented the progression of hyperinsulinaemia observed in SFA-HFD mice (P < 0·001). Glucose-stimulated insulin secretion from isolated islets was reduced by SFA-HFD, yet not fully affected by SFA-to-MUFA-HFD. Markers of ß-cell identity (Ins2, Nkx6.1, Ngn3, Rfx6, Pdx1 and Pax6) were reduced, and islet inflammation was increased (IL-1ß, 3·0-fold, P = 0·007; CD68, 2·9-fold, P = 0·001; Il-6, 1·1-fold, P = 0·437) in SFA-HFD - effects not seen with SFA-to-MUFA-HFD. Switching to MUFA-HFD can partly attenuate the progression of SFA-HFD-induced hyperinsulinaemia, pancreatic inflammation and impairments in ß-cell function. While further work is required from a mechanistic perspective, dietary fat may mediate its effect in an IL-1ß-AMP-activated protein kinase α1-dependent fashion. Future work should assess the potential translation of the modulation of metabolic inflammation in man.

Conjugated Linoleic Acid and Alpha Linolenic Acid Improve Cholesterol Homeostasis in Obesity by Modulating Distinct Hepatic Protein Pathways.

SCOPE: High-fat diet (HFD)-induced obesity impairs macrophage-to-feces reverse cholesterol transport (RCT). It is hypothesized that dietary supplementation with the polyunsaturated fatty acids conjugated linoleic acid (CLA) or alpha linolenic acid (ALA) would prevent HFD-impaired RCT by modulating hepatic protein pathways. METHODS AND RESULTS: ApoE3L.CETP mice are fed a HFD supplemented ± CLA or ALA for 12 weeks and in vivo macrophage-to-feces RCT is determined. Hepatic cholesterol transporters and the hepatic proteome are assessed by immunoblotting and mass spectrometry, respectively. Mice fed HFD alone, but not ALA-HFD or CLA-HFD, exhibit increased systemic cholesterol levels, increased 3 H-cholesterol levels in plasma and liver but not feces during RCT, and reduced hepatic ABCG5/8 expression relative to LFD. ALA-HFD significantly reduces liver weight, hepatic cholesterol levels, and expression of the cholesterol synthesis enzyme farnesyl pyrophosphate synthase relative to HFD. ALA further increases the expression of acetyl-coA oxidase-associated proteins and suppress PPARα-induced proteins relative to HFD. CLA does not significantly attenuate hepatic lipid levels but is associated with reduced hepatic expression of fatty acid binding protein (FABP)-1/FABP4 levels relative to HFD, and reduced inflammatory pathway activation relative to ALA-HFD. CONCLUSION: ALA and CLA exert distinct mechanistic advantages on cholesterol homeostasis and RCT in obesity.

Different monocyte phenotypes result in proresolving macrophages in conjugated linoleic acid-induced attenuated progression and regression of atherosclerosis.

Monocytes/macrophages drive progression and regression of atherosclerosis. Conjugated linoleic acid (CLA), an anti-inflammatory lipid, mediates atheroprotective effects. We investigated how CLA alters monocyte/macrophage phenotype during attenuated progression and regression of atherosclerosis. Apolipoprotein E knockout (ApoE-/-) mice were fed a high-fat (60%) high-cholesterol (1%) diet (HFHCD) for 2 wk, followed by 6-wk 1% CLA 80:20 supplementation to investigate disease progression. Simultaneously, ApoE-/- mice were fed a 12-wk HFHCD with/without CLA for the final 4 wk to investigate regression. Aortic lesions were quantified by en face staining. Proteomic analysis, real-time quantitative PCR and flow cytometry were used to interrogate monocyte/macrophage phenotypes. CLA supplementation inhibited atherosclerosis progression coincident with decreased proinflammatory and increased anti-inflammatory macrophages. However, CLA-induced regression was associated with increased proinflammatory monocytes resulting in increased proresolving M2 bone marrow-derived macrophages, splenic macrophages, and dendritic cells in lesion-draining lymph nodes. Proteomic analysis confirmed regulation of a proinflammatory bone marrow response, which was abolished upon macrophage differentiation. Thus, in attenuation and regression of atherosclerosis, regardless of the monocyte signature, during monocyte to macrophage differentiation, proresolving macrophages prevail, mediating vascular repair. This study provides novel mechanistic insight into the monocyte/macrophage phenotypes in halted atherosclerosis progression and regression of atherosclerosis.-Bruen, R., Curley, S., Kajani, S., Lynch, G., O'Reilly, M. E., Dillon, E. T., Fitzsimons, S., Mthunzi, L., McGillicuddy, F. C., Belton, O. Different monocyte phenotypes result in proresolving macrophages in conjugated linoleic acid-induced attenuated progression and regression of atherosclerosis.

Liraglutide Attenuates Preestablished Atherosclerosis in Apolipoprotein E-Deficient Mice via Regulation of Immune Cell Phenotypes and Proinflammatory Mediators.

We have shown that the glucagon-like peptide-1 receptor agonist (GLP-1RA) liraglutide (Lir) inhibits development of early atherosclerosis in vivo by modulating immune cell function. We hypothesized that Lir could attenuate pre-established disease by modulating monocyte or macrophage phenotype to induce atheroprotective responses. Human atherosclerotic plaques obtained postendarterectomy and human peripheral blood macrophages were treated ex vivo with Lir. In parallel, apolipoprotein E-deficient (ApoE-/-) mice received a high-fat, high-cholesterol diet to induce atherosclerosis for 8 weeks, after which ApoE-/- mice received 300 µg/kg of Lir daily or vehicle control for a further 4 weeks to investigate the attenuation of atherosclerosis. Lir inhibited proinflammatory monocyte chemoattractant protein-1 secretion from human endarterectomy samples and monocyte chemoattractant protein-1, tumor necrosis factor-α, and interleukin (IL)-1ß secretion from human macrophages after ex vivo treatment. An increase in CD206 mRNA and IL-10 secretion was also detected, which implies resolution of inflammation. Importantly, Lir significantly attenuated pre-established atherosclerosis in ApoE-/- mice in the whole aorta and aortic root. Proteomic analysis of ApoE-/- bone marrow cells showed that Lir upregulated the proinflammatory cathepsin protein family, which was abolished in differentiated macrophages. In addition, flow cytometry analysis of bone marrow cells induced a shift toward reduced proinflammatory and increased anti-inflammatory macrophages. We concluded that Lir attenuates pre-established atherosclerosis in vivo by altering proinflammatory mediators. This is the first study to describe a mechanism through which Lir attenuates atherosclerosis by increasing bone marrow proinflammatory protein expression, which is lost in differentiated bone marrow-derived macrophages. This study contributes to our understanding of the anti-inflammatory and cardioprotective role of GLP-1RAs. SIGNIFICANCE STATEMENT: It is critical to understand the mechanisms through which liraglutide (Lir) mediates a cardioprotective effect as many type 2 diabetic medications increase the risk of myocardial infarction and stroke. We have identified that Lir reduces proinflammatory immune cell populations and mediators from plaque-burdened murine aortas in vivo and augments proresolving bone marrow-derived macrophages in attenuation of atherosclerotic disease, which provides further insight into the atheroprotective effect of Lir.

Nutritionally Derived Metabolic Cues Typical of the Obese Microenvironment Increase Cholesterol Efflux Capacity of Adipose Tissue Macrophages.

BACKGROUND: Cholesterol retention within plasma membranes of macrophages is associated with increased inflammatory signaling. Cholesterol efflux via the transporters ABCA1, ABCG1, and SR-BI to high-density lipoprotein (HDL) particles is a critical mechanism to maintain cellular cholesterol homeostasis. Little is known about the impact of the obese microenvironment on cholesterol efflux capacity (CEC) of macrophages. In this study, the CEC of obese-derived primary adipose-tissue macrophages (ATM) is evaluated and the in vivo microenvironment is modeled in vitro to determine mechanisms underlying modulated CEC. MATERIALS AND METHODS: F4/80+ ATM are labeled with 3 H-cholesterol ex vivo, and CEC and ABCA1/ABCG1 protein levels are determined. Total, ABCA1-dependent, and ABCA1-independent CECs are determined in J774 macrophages polarized to M1 (LPS&IFNγ), M2 (IL-4&IL-13), or metabolic phenotypes (glucose, insulin, and palmitic acid). RESULTS: Obese ATM exhibit enhanced CEC and ABCA1 and ABCG1 expression compared to lean ATM. In contrast, ABCA1-CEC is suppressed from M1 polarized macrophages compared to untreated in vitro, by activation of the JAK/STAT pathway. Incubation of macrophages in vitro in high glucose augments cAMP-induced ABCA1 protein expression and ABCA1-CEC. CONCLUSIONS: These novel findings demonstrate remarkable plasticity of macrophages to respond to their environment with specific modulation of ABCA1 depending on whether classical pro-inflammatory or metabolic cues predominate.

SerpinA3N is a novel hypothalamic gene upregulated by a high-fat diet and leptin in mice.

BACKGROUND: Energy homeostasis is regulated by the hypothalamus but fails when animals are fed a high-fat diet (HFD), and leptin insensitivity and obesity develops. To elucidate the possible mechanisms underlying these effects, a microarray-based transcriptomics approach was used to identify novel genes regulated by HFD and leptin in the mouse hypothalamus. RESULTS: Mouse global array data identified serpinA3N as a novel gene highly upregulated by both a HFD and leptin challenge. In situ hybridisation showed serpinA3N expression upregulation by HFD and leptin in all major hypothalamic nuclei in agreement with transcriptomic gene expression data. Immunohistochemistry and studies in the hypothalamic clonal neuronal cell line, mHypoE-N42 (N42), confirmed that alpha 1-antichymotrypsin (α1AC), the protein encoded by serpinA3, is localised to neurons and revealed that it is secreted into the media. SerpinA3N expression in N42 neurons is upregulated by palmitic acid and by leptin, together with IL-6 and TNFα, and all three genes are downregulated by the anti-inflammatory monounsaturated fat, oleic acid. Additionally, palmitate upregulation of serpinA3 in N42 neurons is blocked by the NFκB inhibitor, BAY11, and the upregulation of serpinA3N expression in the hypothalamus by HFD is blunted in IL-1 receptor 1 knockout (IL-1R1 -/- ) mice. CONCLUSIONS: These data demonstrate that serpinA3 expression is implicated in nutritionally mediated hypothalamic inflammation.

Unravelling HDL-Looking beyond the Cholesterol Surface to the Quality Within.

High-density lipoprotein (HDL) particles have experienced a turbulent decade of falling from grace with widespread demotion from the most-sought-after therapeutic target to reverse cardiovascular disease (CVD), to mere biomarker status. HDL is slowly emerging from these dark times due to the HDL flux hypothesis wherein measures of HDL cholesterol efflux capacity (CEC) are better predictors of reduced CVD risk than static HDL-cholesterol (HDL-C) levels. HDL particles are emulsions of metabolites, lipids, protein, and microRNA (miR) built on the backbone of Apolipoprotein A1 (ApoA1) that are growing in their complexity due to the higher sensitivity of the respective "omic" technologies. Our understanding of particle composition has increased dramatically within this era and has exposed how our understanding of these particles to date has been oversimplified. Elucidation of the HDL proteome coupled with the identification of specific miRs on HDL have highlighted the "hormonal" characteristics of HDL in that it carries and delivers messages systemically. HDL can dock to most peripheral cells via its receptors, including SR-B1, ABCA1, and ABCG1, which may be a critical step for facilitating HDL-to-cell communication. The composition of HDL particles is, in turn, altered in numerous disease states including diabetes, auto-immune disease, and CVD. The consequence of changes in composition, however, on subsequent biological activities of HDL is currently poorly understood and this is an important avenue for the field to explore in the future. Improving HDL particle quality as opposed to HDL quantity may, in turn, prove a more beneficial investment to reduce CVD risk.

Personalized Cardio-Metabolic Responses to an Anti-Inflammatory Nutrition Intervention in Obese Adolescents: A Randomized Controlled Crossover Trial.

SCOPE: Chronic inflammation and hypoadiponectinemia are characteristics of obesity-induced insulin resistance (IR). The effect of an anti-inflammatory nutrition supplement (AINS) on IR and adiponectin biology in overweight adolescents was investigated. The secondary objective was to examine the extent to which individuals' biomarker profiles, derived from baseline phenotypes, predicted response or not to the AINS. Additionally, the impact of DNA methylation on intervention efficacy was assessed. METHODS AND RESULTS: Seventy overweight adolescents (13-18 years) were recruited to this randomized controlled crossover trial. Participants received an AINS (long chain n-3 PUFA, vitamin C, α-tocopherol, green tea extract, and lycopene) and placebo for 8 weeks each. Homeostatic model assessment (HOMA)-IR, adiponectin, inflammatory profiles, and DNA methylation were assessed. HOMA-IR was unchanged in the total cohort. High-molecular-weight (HMW) adiponectin was maintained following the AINS while it decreased over time following the placebo intervention. HOMA-IR decreased in 40% of subjects (responders) following the AINS. Responders' pretreatment phenotype was characterized by higher HOMA-IR, total and LDL cholesterol, but similar BMI in comparison to nonresponders. HMW adiponectin response to the AINS was associated with bidirectional modulation of adipogenic gene methylation. CONCLUSION: The AINS modulated adiponectin biology, an early predictor of type 2 diabetes risk, was associated with bidirectional modulation of adipogenic gene methylation in weight-stable overweight adolescents. HOMA-IR decreased in a sub-cohort of adolescents with an adverse metabolic phenotype. Thus, suggesting that more stratified or personalized nutrition approaches may enhance efficacy of dietary interventions.

Liraglutide dictates macrophage phenotype in apolipoprotein E null mice during early atherosclerosis.

BACKGROUND: Macrophages play a pivotal role in atherosclerotic plaque development. Recent evidence has suggested the glucagon-like peptide-1 receptor (GLP-1R) agonist, liraglutide, can attenuate pro-inflammatory responses in macrophages. We hypothesized that liraglutide could limit atherosclerosis progression in vivo via modulation of the inflammatory response. METHODS: Human THP-1 macrophages and bone marrow-derived macrophages, from both wild-type C57BL/6 (WT) and apolipoprotein E null mice (ApoE-/-) were used to investigate the effect of liraglutide on the inflammatory response in vitro. In parallel, ApoE-/- mice were fed a high-fat (60% calories from fat) high-cholesterol (1%) diet for 8 weeks to induce atherosclerotic disease progression with/without daily 300 µg/kg liraglutide administration for the final 6 weeks. Macrophages were analysed for MΦ1 and MΦ2 macrophage markers by Western blotting, RT-qPCR, ELISA and flow cytometry. Atherosclerotic lesions in aortae from ApoE-/- mice were analysed by en face staining and monocyte and macrophage populations from bone marrow derived cells analysed by flow cytometry. RESULTS: Liraglutide decreased atherosclerotic lesion formation in ApoE-/- mice coincident with a reduction in pro-inflammatory and increased anti-inflammatory monocyte/macrophage populations in vivo. Liraglutide decreased IL-1beta in MΦ0 THP-1 macrophages and bone marrow-derived macrophages from WT mice and induced a significant increase in the MΦ2 surface marker mannose receptor in both MΦ0 and MΦ2 macrophages. Significant reduction in total lesion development was found with once daily 300 µg/kg liraglutide treatment in ApoE-/- mice. Interestingly, liraglutide inhibited disease progression at the iliac bifurcation suggesting that it retards the initiation and development of disease. These results corresponded to attenuated MΦ1 markers (CCR7, IL-6 and TNF-alpha), augmented MΦ2 cell markers (Arg-1, IL-10 and CD163) and finally decreased MΦ1-like monocytes and macrophages from bone marrow-derived cells. CONCLUSIONS: This data supports a therapeutic role for liraglutide as an atheroprotective agent via modulating macrophage cell fate towards MΦ2 pro-resolving macrophages.

Nutritional modulation of metabolic inflammation.

Metabolic inflammation is a very topical area of research, wherein aberrations in metabolic and inflammatory pathways probably contribute to atherosclerosis, insulin resistance (IR) and type 2 diabetes. Metabolic insults arising from obesity promote inflammation, which in turn impedes insulin signalling and reverse cholesterol transport (RCT). Key cells in the process are metabolically activated macrophages, which up-regulate both pro- and anti-inflammatory pathways in response to lipid spillover from adipocytes. Peroxisome proliferator-activated receptors and AMP-activated protein kinase (AMPK) are regulators of cellular homeostasis that influence both inflammatory and metabolic pathways. Dietary fats, such as saturated fatty acids (SFAs), can differentially modulate metabolic inflammation. Palmitic acid, in particular, is a well-characterized nutrient that promotes metabolic inflammation via the NLRP3 (the nod-like receptor containing a pyrin domain) inflammasome, which is partly attributable to AMPK inhibition. Conversely, some unsaturated fatty acids are less potent agonists of metabolic inflammation. For example, monounsaturated fatty acid does not reduce AMPK as potently as SFA and n-3 polyunsaturated fatty acids actively resolve inflammation via resolvins and protectins. Nevertheless, the full extent to which nutritional state modulates metabolic inflammation requires greater clarification.

A casein hydrolysate protects mice against high fat diet induced hyperglycemia by attenuating NLRP3 inflammasome-mediated inflammation and improving insulin signaling.

SCOPE: Activation of the nod-like receptor protein 3 (NLRP3) inflammasome is required for IL-1ß release and is a key component of obesity-induced inflammation and insulin resistance. This study hypothesized that supplementation with a casein hydrolysate (CH) would attenuate NLRP3 inflammasome mediated IL-1ß secretion in adipose tissue (AT) and improve obesity-induced insulin resistance. METHODS AND RESULTS: J774.2 macrophages were LPS primed (10 ng/mL) and stimulated with adenosine triphosphate (5 mM) to assess NLRP3 inflammasome activity. Pretreatment with CH (1 mg/mL; 48 h) reduced caspase-1 activity and decreased IL-1ß secretion from J774.2 macrophages in vitro. 3T3-L1 adipocytes cultured with conditioned media from CH-pretreated J774.2 macrophages demonstrated increased phosphorylated (p)AKT expression and improved insulin sensitivity. C57BL/6JOLaHsd mice were fed chow or high fat diet (HFD) for 12 wk ± CH resuspended in water (0.5% w/v). CH supplementation improved glucose tolerance in HFD-fed mice as determined by glucose tolerance test. CH supplementation increased insulin-stimulated pAKT protein levels in AT, liver, and muscle after HFD. Cytokine secretion was measured from AT and isolated bone marrow macrophages cultured ex vivo. CH supplementation attenuated IL-1ß, tumor necrosis factor alpha (TNF-α) and IL-6 secretion from AT and IL-1ß, IL-18, and TNF-α from bone marrow macrophages following adenosine triphosphate stimulation ex vivo. CONCLUSION: This novel CH partially protects mice against obesity-induced hyperglycemia coincident with attenuated IL-1ß secretion and improved insulin signaling.

High-Density Lipoprotein Proteomic Composition, and not Efflux Capacity, Reflects Differential Modulation of Reverse Cholesterol Transport by Saturated and Monounsaturated Fat Diets.

BACKGROUND: Acute inflammation impairs reverse cholesterol transport (RCT) and reduces high-density lipoprotein (HDL) function in vivo. This study hypothesized that obesity-induced inflammation impedes RCT and alters HDL composition, and investigated if dietary replacement of saturated (SFA) for monounsaturated (MUFA) fatty acids modulates RCT. METHODS AND RESULTS: Macrophage-to-feces RCT, HDL efflux capacity, and HDL proteomic profiling was determined in C57BL/6j mice following 24 weeks on SFA- or MUFA-enriched high-fat diets (HFDs) or low-fat diet. The impact of dietary SFA consumption and insulin resistance on HDL efflux function was also assessed in humans. Both HFDs increased plasma (3)H-cholesterol counts during RCT in vivo and ATP-binding cassette, subfamily A, member 1-independent efflux to plasma ex vivo, effects that were attributable to elevated HDL cholesterol. By contrast, ATP-binding cassette, subfamily A, member 1-dependent efflux was reduced after both HFDs, an effect that was also observed with insulin resistance and high SFA consumption in humans. SFA-HFD impaired liver-to-feces RCT, increased hepatic inflammation, and reduced ABC subfamily G member 5/8 and ABC subfamily B member 11 transporter expression in comparison with low-fat diet, whereas liver-to-feces RCT was preserved after MUFA-HFD. HDL particles were enriched with acute-phase proteins (serum amyloid A, haptoglobin, and hemopexin) and depleted of paraoxonase-1 after SFA-HFD in comparison with MUFA-HFD. CONCLUSIONS: Ex vivo efflux assays validated increased macrophage-to-plasma RCT in vivo after both HFDs but failed to capture differential modulation of hepatic cholesterol trafficking. By contrast, proteomics revealed the association of hepatic-derived inflammatory proteins on HDL after SFA-HFD in comparison with MUFA-HFD, which reflected differential hepatic cholesterol trafficking between groups. Acute-phase protein levels on HDL may serve as novel biomarkers of impaired liver-to-feces RCT in vivo.