Glutamine metabolism improves left ventricular function but not macrophage-mediated inflammation following myocardial infarction.

Glutamine is a critical amino acid that serves as an energy source, building block, and signaling molecule for the heart tissue and the immune system. However, the role of glutamine metabolism in regulating cardiac remodeling following myocardial infarction (MI) is unknown. In this study, we show in adult male mice that glutamine metabolism is altered both in the remote (contractile) area and in infiltrating macrophages in the infarct area after permanent left anterior descending artery occlusion. We found that metabolites related to glutamine metabolism were differentially altered in macrophages at days 1, 3, and 7 after MI using untargeted metabolomics. Glutamine metabolism in live cells was increased after MI relative to no MI controls. Gene expression in the remote area of the heart indicated a loss of glutamine metabolism. Glutamine administration improved LV function at days 1, 3, and 7 after MI, which was associated with improved contractile and metabolic gene expression. Conversely, administration of BPTES, a pharmacological inhibitor of glutaminase-1, worsened LV function after MI. Neither glutamine nor BPTES administration impacted gene expression or bioenergetics of macrophages isolated from the infarct area. Our results indicate that glutamine metabolism plays a critical role in maintaining LV contractile function following MI, and that glutamine administration improves LV function. Glutamine metabolism may also play a role in regulating macrophage function, but macrophages are not responsive to exogenous pharmacological manipulation of glutamine metabolism.

Sex differences in weight gain, blood pressure control, and responses to melanocortin-4 receptor antagonism in offspring from lean and obese parents.

We examined potential sex differences in appetite and blood pressure (BP) responses to melanocortin-4 receptor (MC4R) blockade in offspring from lean and obese parents. Offspring from normal (N) diet-fed parents were fed N (NN) or high-fat (H) diets (NH) from weaning until adulthood. Offspring from obese H diet-fed parents were also fed N (HN) or H diets (HH). Adult male and female offspring were implanted with BP telemetry probes and intracerebroventricular cannulas to infuse MC4R antagonist or vehicle. Infusion of the MC4R antagonist SHU-9119 (1 nmol/h) for 7 days caused larger increases in calorie intake and body weight in obese compared with lean offspring. In male offspring, HH and HN groups exhibited higher baseline BP compared with NN and NH, and HH showed a greater reduction in BP during SHU-9119 infusion. In female offspring, HH also showed higher baseline BP and greater reduction in BP during MC4R blockade. SHU-9119 reduced heart rate in all groups, but reductions were more pronounced in offspring from lean parents. Combined α and ß-adrenergic blockade reduced BP more in male HH offspring compared with NN controls. Losartan reduced BP more in male NH, HN, and HH offspring compared with NN controls. Losartan and α- and ß-adrenergic blockade reduced BP similarly in all female groups. These results suggest that endogenous MC4R activity contributes to elevated BP in obese offspring from obese parents. Our findings also indicate important sex differences in the mechanisms of BP control in male and female offspring of obese parents.

Targeting immunometabolism during cardiorenal injury: roles of conventional and alternative macrophage metabolic fuels.

Macrophages play critical roles in mediating and resolving tissue injury as well as tissue remodeling during cardiorenal disease. Altered immunometabolism, particularly macrophage metabolism, is a critical underlying mechanism of immune dysfunction and inflammation, particularly in individuals with underlying metabolic abnormalities. In this review, we discuss the critical roles of macrophages in cardiac and renal injury and disease. We also highlight the roles of macrophage metabolism and discuss metabolic abnormalities, such as obesity and diabetes, which may impair normal macrophage metabolism and thus predispose individuals to cardiorenal inflammation and injury. As the roles of macrophage glucose and fatty acid metabolism have been extensively discussed elsewhere, we focus on the roles of alternative fuels, such as lactate and ketones, which play underappreciated roles during cardiac and renal injury and heavily influence macrophage phenotypes.

The Oligostilbene Gnetin H Is a Novel Glycolysis Inhibitor That Regulates Thioredoxin Interacting Protein Expression and Synergizes with OXPHOS Inhibitor in Cancer Cells.

Since aerobic glycolysis was first observed in tumors almost a century ago by Otto Warburg, the field of cancer cell metabolism has sparked the interest of scientists around the world as it might offer new avenues of treatment for malignant cells. Our current study claims the discovery of gnetin H (GH) as a novel glycolysis inhibitor that can decrease metabolic activity and lactic acid synthesis and displays a strong cytostatic effect in melanoma and glioblastoma cells. Compared to most of the other glycolysis inhibitors used in combination with the complex-1 mitochondrial inhibitor phenformin (Phen), GH more potently inhibited cell growth. RNA-Seq with the T98G glioblastoma cell line treated with GH showed more than an 80-fold reduction in thioredoxin interacting protein (TXNIP) expression, indicating that GH has a direct effect on regulating a key gene involved in the homeostasis of cellular glucose. GH in combination with phenformin also substantially enhances the levels of p-AMPK, a marker of metabolic catastrophe. These findings suggest that the concurrent use of the glycolytic inhibitor GH with a complex-1 mitochondrial inhibitor could be used as a powerful tool for inducing metabolic catastrophe in cancer cells and reducing their growth.

Temporal changes in glucose metabolism reflect polarization in resident and monocyte-derived macrophages after myocardial infarction.

Introduction: Metabolic reprogramming from glycolysis to the mitochondrial tricarboxylic acid (TCA) cycle and oxidative phosphorylation may mediate macrophage polarization from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype. We hypothesized that changes in cardiac macrophage glucose metabolism would reflect polarization status after myocardial infarction (MI), ranging from the early inflammatory phase to the later wound healing phase. Methods: MI was induced by permanent ligation of the left coronary artery in adult male C57BL/6J mice for 1 (D1), 3 (D3), or 7 (D7) days. Infarct macrophages were subjected to metabolic flux analysis or gene expression analysis. Monocyte versus resident cardiac macrophage metabolism was assessed using mice lacking the Ccr2 gene (CCR2 KO). Results: By flow cytometry and RT-PCR, D1 macrophages exhibited an M1 phenotype while D7 macrophages exhibited an M2 phenotype. Macrophage glycolysis (extracellular acidification rate) was increased at D1 and D3, returning to basal levels at D7. Glucose oxidation (oxygen consumption rate) was decreased at D3, returning to basal levels at D7. At D1, glycolytic genes were elevated (Gapdh, Ldha, Pkm2), while TCA cycle genes were elevated at D3 (Idh1 and Idh2) and D7 (Pdha1, Idh1/2, Sdha/b). Surprisingly, Slc2a1 and Hk1/2 were increased at D7, as well as pentose phosphate pathway (PPP) genes (G6pdx, G6pd2, Pgd, Rpia, Taldo1), indicating increased PPP activity. Macrophages from CCR2 KO mice showed decreased glycolysis and increased glucose oxidation at D3, and decreases in Ldha and Pkm2 expression. Administration of dichloroacetate, a pyruvate dehydrogenase kinase inhibitor, robustly decreased pyruvate dehydrogenase phosphorylation in the non-infarcted remote zone, but did not affect macrophage phenotype or metabolism in the infarct zone. Discussion: Our results indicate that changes in glucose metabolism and the PPP underlie macrophage polarization following MI, and that metabolic reprogramming is a key feature of monocyte-derived but not resident macrophages.

Immunometabolism, extracellular vesicles and cardiac injury.

Recent evidence from our lab and others suggests that metabolic reprogramming of immune cells drives changes in immune cell phenotypes along the inflammatory-to-reparative spectrum and plays a critical role in mediating the inflammatory responses to cardiac injury (e.g. hypertension, myocardial infarction). However, the factors that drive metabolic reprogramming in immune cells are not fully understood. Extracellular vesicles (EVs) are recognized for their ability to transfer cargo such as microRNAs from remote sites to influence cardiac remodeling. Furthermore, conditions such as obesity and metabolic syndrome, which are implicated in the majority of cardiovascular disease (CVD) cases, can skew production of EVs toward pro-inflammatory phenotypes. In this mini-review, we discuss the mechanisms by which EVs may influence immune cell metabolism during cardiac injury and factors associated with obesity and the metabolic syndrome that can disrupt normal EV function. We also discuss potential sources of cardio-protective and anti-inflammatory EVs, such as brown adipose tissue. Finally, we discuss implications for future therapeutics.

Central Nervous System Actions of Leptin Improve Cardiac Function After Ischemia-Reperfusion: Roles of Sympathetic Innervation and Sex Differences.

Background Therapeutic strategies for preventing paradoxical reperfusion injury after myocardial ischemia are limited. We tested whether central nervous system actions of leptin induce important protective effects on cardiac function and metabolism after myocardial ischemia/reperfusion (I/R) injury, the role of cardiac sympathetic innervation in mediating these effects, and whether there are major sex differences in the cardioprotective effects of chronic central nervous system leptin infusion. Methods and Results Myocardial I/R was induced by temporary ligation of the left descending coronary artery in male and female Wistar rats instrumented with intracerebroventricular cannula in the lateral ventricle. Vehicle or leptin (0.62 µg/h) infusion was started immediately after reperfusion and continued for 28 days using osmotic minipumps connected to the intracerebroventricular cannula. Cardiac function was assessed by echocardiography, ventricular pressures, and exercise performance. Intracerebroventricular leptin treatment markedly attenuated cardiac dysfunction post-I/R as evidenced by improved ejection fraction (56.7±1.9 versus 22.6%±1.1%), maximal rate of left ventricle rise (11 680±2122 versus 5022±441 mm Hg) and exercise performance (-4.2±7.9 versus -68.2±3.8 Δ%) compared with vehicle-treated rats. Intracerebroventricular leptin infusion reduced infarct size in females, but not males, when compared with ad-lib fed or pair-fed saline-treated rats. Intracerebroventricular leptin treatment also increased cardiac NAD+/NADH content (≈10-fold) and improved mitochondrial function when compared with vehicle treatment. Cervical ganglia denervation did not attenuate the cardiac protective effects of leptin after I/R injury. Conclusions These data indicate that leptin, via its central nervous system actions, markedly improves overall heart function and mitochondrial metabolism after I/R injury regardless of sex, effects that are largely independent of cardiac sympathetic innervation.

Direct Cardiac Actions of Sodium-Glucose Cotransporter 2 Inhibition Improve Mitochondrial Function and Attenuate Oxidative Stress in Pressure Overload-Induced Heart Failure.

Clinical trials showed that sodium-glucose cotransporter 2 (SGLT2) inhibitors, a class of drugs developed for treating diabetes mellitus, improve prognosis of patients with heart failure (HF). However, the mechanisms for cardioprotection by SGLT2 inhibitors are still unclear. Mitochondrial dysfunction and oxidative stress play important roles in progression of HF. This study tested the hypothesis that empagliflozin (EMPA), a highly selective SGLT2 inhibitor, improves mitochondrial function and reduces reactive oxygen species (ROS) while enhancing cardiac performance through direct effects on the heart in a non-diabetic mouse model of HF induced by transverse aortic constriction (TAC). EMPA or vehicle was administered orally for 4 weeks starting 2 weeks post-TAC. EMPA treatment did not alter blood glucose or body weight but significantly attenuated TAC-induced cardiac dysfunction and ventricular remodeling. Impaired mitochondrial oxidative phosphorylation (OXPHOS) in failing hearts was significantly improved by EMPA. EMPA treatment also enhanced mitochondrial biogenesis and restored normal mitochondria morphology. Although TAC increased mitochondrial ROS and decreased endogenous antioxidants, EMPA markedly inhibited cardiac ROS production and upregulated expression of endogenous antioxidants. In addition, EMPA enhanced autophagy and decreased cardiac apoptosis in TAC-induced HF. Importantly, mitochondrial respiration significantly increased in ex vivo cardiac fibers after direct treatment with EMPA. Our results indicate that EMPA has direct effects on the heart, independently of reductions in blood glucose, to enhance mitochondrial function by upregulating mitochondrial biogenesis, enhancing OXPHOS, reducing ROS production, attenuating apoptosis, and increasing autophagy to improve overall cardiac function in a non-diabetic model of pressure overload-induced HF.

Parental obesity alters offspring blood pressure regulation and cardiovascular responses to stress: role of P2X7R and sex differences.

We examined the impact of parental obesity on offspring blood pressure (BP) regulation and cardiovascular responses to stress. Offspring from normal (N) diet-fed C57BL/6J parents were fed either N (NN) or a high-fat (H) diet (NH) from weaning until adulthood. Offspring from obese H diet-fed parents were also fed N (HN) or H diet (HH). Body weight, calorie intake, and fat mass were measured at 22 wk of age when cardiovascular phenotyping was performed. Male and female HH offspring were 15% heavier than NH and 70% heavier than NN offspring. Male HH and HN offspring had elevated BP (121 ± 2 and 115 ± 1 mmHg, by telemetry) compared with male NH and NN offspring (108 ± 6 and 107 ± 3 mmHg, respectively) and augmented BP responses to angiotensin II, losartan, and hexamethonium. Male HH and HN offspring also showed increased BP responses to air-jet stress (37 ± 2 and 38 ± 2 mmHg) compared with only 24 ± 3 and 25 ± 3 mmHg in NH and NN offspring. Baseline heart rate (HR) and HR responses to air-jet stress were similar among groups. In females, BP and cardiovascular responses to stress were similar among all offspring. Male H diet-fed offspring from obese H diet-fed purinoreceptor 7-deficient (HH-P2X7R-KO) parents had normal BP that was similar to control NN-P2X7R-KO offspring from lean parents. These results indicate that parental obesity leads to increased BP and augmented BP responses to stress in their offspring in a sex-dependent manner, and the impact of parental obesity on male offspring BP regulation is markedly attenuated in P2X7R-KO mice.

Sex differences in the impact of parental obesity on offspring cardiac SIRT3 expression, mitochondrial efficiency, and diastolic function early in life.

Previous studies suggest that parental obesity may adversely impact long-term metabolic health of the offspring. We tested the hypothesis that parental (paternal + maternal) obesity impairs cardiac function in the offspring early in life. Within 1-3 days after weaning, offspring from obese rats fed a high-fat diet (HFD-Offs) and age-matched offspring from lean rats (ND-Offs) were submitted to echocardiography and cardiac catheterization for assessment of pressure-volume relationships. Then, hearts were digested and isolated cardiomyocytes were used to determine contractile function, calcium transients, proteins related to calcium signaling, and mitochondrial bioenergetics. Female and male HFD-Offs were heavier (72 ± 2 and 61 ± 4 g vs. 57 ± 2 and 49 ± 1 g), hyperglycemic (112 ± 8 and 115 ± 12 mg/dL vs. 92 ± 10 and 96 ± 8 mg/dL) with higher plasma insulin and leptin concentrations compared with female and male ND-Offs. When compared with male controls, male HFD-Offs exhibited similar systolic function but impaired diastolic function as indicated by increased IVRT (22 ± 1 vs. 17 ± 1 ms), E/E' ratio (29 ± 2 vs. 23 ± 1), and tau (5.7 ± 0.2 vs. 4.8 ± 0.2). The impaired diastolic function was associated with reduced resting free Ca2+ levels and phospholamban protein expression, increased activated matrix metalloproteinase 2, and reduced SIRT3 protein expression, mitochondrial ATP reserve, and ATP-linked respiration. These results indicate that male and female Offs from obese parents have multiple metabolic abnormalities early in life (1-3 days after weaning) and that male, but not female, Offs have impaired diastolic function as well as reductions in cardiac SIRT3, resting free Ca2+ levels, and mitochondrial biogenesis.NEW & NOTEWORTHY Parental obesity contributes to diastolic dysfunction in young offspring (1-3 days after weaning) in a sex-dependent manner, as well as reduced cardiac SIRT3 expression and altered mitochondrial bioenergetics, resting Ca2+ levels, and reduced phospholamban protein levels.

Dimethyl fumarate preserves left ventricular infarct integrity following myocardial infarction via modulation of cardiac macrophage and fibroblast oxidative metabolism.

Myocardial infarction (MI) is one of the leading causes of mortality and cardiovascular disease worldwide. MI is characterized by a substantial inflammatory response in the infarcted left ventricle (LV), followed by transition of quiescent fibroblasts to active myofibroblasts, which deposit collagen to form the reparative scar. Metabolic shifting between glycolysis and mitochondrial oxidative phosphorylation (OXPHOS) is an important mechanism by which these cell types transition towards reparative phenotypes. Thus, we hypothesized that dimethyl fumarate (DMF), a clinically approved anti-inflammatory agent with metabolic actions, would improve post-MI remodeling via modulation of macrophage and fibroblast metabolism. Adult male C57BL/6J mice were treated with DMF (10 mg/kg) for 3-7 days after MI. DMF attenuated LV infarct and non-infarct wall thinning at 3 and 7 days post-MI, and decreased LV dilation and pulmonary congestion at day 7. DMF improved LV infarct collagen deposition, myofibroblast activation, and angiogenesis at day 7. DMF also decreased pro-inflammatory cytokine expression (Tnf) 3 days after MI, and decreased inflammatory markers in macrophages isolated from the infarcted heart (Hif1a, Il1b). In fibroblasts extracted from the infarcted heart at day 3, RNA-Seq analysis demonstrated that DMF promoted an anti-inflammatory/pro-reparative phenotype. By Seahorse analysis, DMF did not affect glycolysis in either macrophages or fibroblasts at day 3, but enhanced macrophage OXPHOS while impairing fibroblast OXPHOS. Our results indicate that DMF differentially affects macrophage and fibroblast metabolism, and promotes anti-inflammatory/pro-reparative actions. In conclusion, targeting cellular metabolism in the infarcted heart may be a promising therapeutic strategy.

Interaction of Obesity and Hypertension on Cardiac Metabolic Remodeling and Survival Following Myocardial Infarction.

Background Obesity and hypertension are risk factors for myocardial infarction (MI); however, their potential interactions on post-MI outcomes are unclear. We examined interactions of obesity and hypertensionon post-MI function, remodeling, metabolic changes, and recovery. Methods and Results Male and female C57BL/6J mice were provided standard chow or high-fat/fructose diet for 8 weeks and then infused with angiotensin II for 2 weeks to induce hypertension. MI was then induced by surgical ligation of the left coronary artery for 7 days. Obesity alone did not cause cardiac injury or exacerbate hypertension-induced cardiac dysfunction. After MI, however, obese-normotensive mice had lower survival rates compared with chow-fed mice (56% versus 89% males; 54% versus 75% females), which were further decreased by hypertension (29% males; and 35% females). Surviving obese-normotensive males displayed less left ventricular dilation and pulmonary congestion compared with chow-fed males after MI; hypertension reversed left ventricular dilation because of high-fat/fructose diet and promoted significant pulmonary congestion compared with chow-fed controls. Obese-normotensive males displayed higher left ventricular α-MHC (alpha-myosin heavy chain) protein, phosphorylated Akt (protein kinase B) and AMPK (adenosine-monophosphate activated kinase), PPAR-γ (peroxisome proliferator activated receptor gamma), and plasma adiponectin levels after MI, indicating favorable contractile and metabolic changes. However, these favorable contractile and metabolic changes were attenuated by hypertension. Obese-hypertensive males also had lower levels of collagen in the infarcted region, indicating decreased ability to promote an adaptive wound healing response to MI. Conclusions Obesity reduces post-MI survival but is associated with improved post-MI cardiac function and metabolism in surviving normotensive mice. When hypertension accompanies obesity, favorable metabolic pathways associated with obesity are attenuated and post-MI cardiac function and remodeling are adversely impacted.

Obesity, kidney dysfunction, and inflammation: interactions in hypertension.

Obesity contributes 65-75% of the risk for human primary (essential) hypertension (HT) which is a major driver of cardiovascular and kidney diseases. Kidney dysfunction, associated with increased renal sodium reabsorption and compensatory glomerular hyperfiltration, plays a key role in initiating obesity-HT and target organ injury. Mediators of kidney dysfunction and increased blood pressure include (i) elevated renal sympathetic nerve activity (RSNA); (ii) increased antinatriuretic hormones such as angiotensin II and aldosterone; (iii) relative deficiency of natriuretic hormones; (iv) renal compression by fat in and around the kidneys; and (v) activation of innate and adaptive immune cells that invade tissues throughout the body, producing inflammatory cytokines/chemokines that contribute to vascular and target organ injury, and exacerbate HT. These neurohormonal, renal, and inflammatory mechanisms of obesity-HT are interdependent. For example, excess adiposity increases the adipocyte-derived cytokine leptin which increases RSNA by stimulating the central nervous system proopiomelanocortin-melanocortin 4 receptor pathway. Excess visceral, perirenal and renal sinus fat compress the kidneys which, along with increased RSNA, contribute to renin-angiotensin-aldosterone system activation, although obesity may also activate mineralocorticoid receptors independent of aldosterone. Prolonged obesity, HT, metabolic abnormalities, and inflammation cause progressive renal injury, making HT more resistant to therapy and often requiring multiple antihypertensive drugs and concurrent treatment of dyslipidaemia, insulin resistance, diabetes, and inflammation. More effective anti-obesity drugs are needed to prevent the cascade of cardiorenal, metabolic, and immune disorders that threaten to overwhelm health care systems as obesity prevalence continues to increase.

Novel roles of immunometabolism and nonmyocyte metabolism in cardiac remodeling and injury.

Changes in cardiomyocyte metabolism have been heavily implicated in cardiac injury and heart failure (HF). However, there is emerging evidence that metabolism in nonmyocyte populations, including cardiac fibroblasts, immune cells, and endothelial cells, plays an important role in cardiac remodeling and adaptation to injury. Here, we discuss recent advances and insights into nonmyocyte metabolism in the healthy and injured heart. Metabolic switching from mitochondrial oxidative phosphorylation to glycolysis is critical for immune cell (macrophage and T lymphocyte) and fibroblast phenotypic switching in the inflamed and fibrotic heart. On the other hand, cardiac endothelial cells are heavily reliant on glycolytic metabolism, and thus impairments in glycolytic metabolism underlie endothelial cell dysfunction. Finally, we review current and ongoing metabolic therapies for HF and the potential implications for nonmyocyte metabolism.

Role of Hyperinsulinemia and Insulin Resistance in Hypertension: Metabolic Syndrome Revisited.

Hyperinsulinemia and insulin resistance were proposed more than 30 years ago to be important contributors to elevated blood pressure (BP) associated with obesity and the metabolic syndrome, also called syndrome X. Support for this concept initially came from clinical and population studies showing correlations among hyperinsulinemia, insulin resistance, and elevated BP in individuals with metabolic syndrome. Short-term studies in experimental animals and in humans provided additional evidence that hyperinsulinemia may evoke increases in sympathetic nervous system (SNS) activity and renal sodium retention that, if sustained, could increase BP. Although insulin infusions may increase SNS activity and modestly raise BP in rodents, chronic insulin administration does not significantly increase BP in lean or obese insulin-resistant rabbits, dogs, horses, or humans. Multiple studies in humans and experimental animals have also shown that severe insulin resistance and hyperinsulinemia may occur in the absence of elevated BP. These observations question whether insulin resistance and hyperinsulinemia are major factors linking obesity/metabolic syndrome with hypertension. Other mechanisms, such as physical compression of the kidneys, activation of the renin-angiotensin-aldosterone system, hyperleptinemia, stimulation of the brain melanocortin system, and SNS activation, appear to play a more critical role in initiating hypertension in obese subjects with metabolic syndrome. However, the metabolic effects of insulin resistance, including hyperglycemia and dyslipidemia, appear to interact synergistically with increased BP to cause vascular and kidney injury that can exacerbate the hypertension and associated injury to the kidneys and cardiovascular system.

Obesity, Hypertension, and Cardiac Dysfunction: Novel Roles of Immunometabolism in Macrophage Activation and Inflammation.

Obesity and hypertension, which often coexist, are major risk factors for heart failure and are characterized by chronic, low-grade inflammation, which promotes adverse cardiac remodeling. While macrophages play a key role in cardiac remodeling, dysregulation of macrophage polarization between the proinflammatory M1 and anti-inflammatory M2 phenotypes promotes excessive inflammation and cardiac injury. Metabolic shifting between glycolysis and mitochondrial oxidative phosphorylation has been implicated in macrophage polarization. M1 macrophages primarily rely on glycolysis, whereas M2 macrophages rely on the tricarboxylic acid cycle and oxidative phosphorylation; thus, factors that affect macrophage metabolism may disrupt M1/M2 homeostasis and exacerbate inflammation. The mechanisms by which obesity and hypertension may synergistically induce macrophage metabolic dysfunction, particularly during cardiac remodeling, are not fully understood. We propose that obesity and hypertension induce M1 macrophage polarization via mechanisms that directly target macrophage metabolism, including changes in circulating glucose and fatty acid substrates, lipotoxicity, and tissue hypoxia. We discuss canonical and novel proinflammatory roles of macrophages during obesity-hypertension-induced cardiac injury, including diastolic dysfunction and impaired calcium handling. Finally, we discuss the current status of potential therapies to target macrophage metabolism during heart failure, including antidiabetic therapies, anti-inflammatory therapies, and novel immunometabolic agents.

The prevalence of cardio-metabolic risk factors is differentially elevated in obesity-prone Osborne-Mendel and obesity-resistant S5B/Pl rats.

AIMS: Individual susceptibility to develop obesity may impact the development of cardio-metabolic risk factors that lead to obesity-related comorbid conditions. Obesity-prone Osborne-Mendel (OM) rats expressed higher levels of visceral adipose inflammation than obesity-resistant, S5B/Pl (S5B) rats. However, the consumption of a high fat diet (HFD) differentially affected OM and S5B rats and induced an increase in visceral adipose inflammation in S5B rats. The current study examined the effects of HFD consumption on cardio-metabolic risk factors in OM and S5B rats. MATERIALS & METHODS: Glucose regulation and circulating levels of lipids, adiponectin and C-reactive protein were assessed following 8 weeks of HFD or low fat diet (LFD) consumption. Left ventricle hypertrophy and mRNA expression of cardiovascular disease biomarkers were also quantified in OM and S5B rats. KEY FINDINGS: Circulating levels of triglycerides were higher, while HDL cholesterol, adiponectin and glycemic control were lower in OM rats, compared to S5B rats. In the left ventricle, BNP and CTGF mRNA expression were higher in OM rats and IL-6, IL-1ß, VEGF, and iNOS mRNA expression were higher in S5B rats. SIGNIFICANCE: These findings support the hypothesis that cardio-metabolic risk factors are increased in obesity-prone individuals, which may increase the risk for the development of obesity-related comorbidities. In the current models, obesity-resistant S5B rats also exhibited cardiovascular risk factors supporting the importance of monitoring cardiovascular health in individuals characterized as obesity-resistant.

Prenatal Alcohol Exposure Causes Adverse Cardiac Extracellular Matrix Changes and Dysfunction in Neonatal Mice.

Fetal alcohol syndrome (FAS) is the most severe condition of fetal alcohol spectrum disorders (FASD) and is associated with congenital heart defects. However, more subtle defects such as ventricular wall thinning and cardiac compliance may be overlooked in FASD. Our studies focus on the role of cardiac fibroblasts in the neonatal heart, and how they are affected by prenatal alcohol exposure (PAE). We hypothesize that PAE affects fibroblast function contributing to dysregulated collagen synthesis, which leads to cardiac dysfunction. To investigate these effects, pregnant C57/BL6 mice were intraperitoneally injected with 2.9 g EtOH/kg dose to achieve a blood alcohol content of approximately 0.35 on gestation days 6.75 and 7.25. Pups were sacrificed on neonatal day 5 following echocardiography measurements of left ventricular (LV) chamber dimension and function. Hearts were used for primary cardiac fibroblast isolation or protein expression analysis. PAE animals had thinner ventricular walls than saline exposed animals, which was associated with increased LV wall stress and decreased ejection fraction. In isolated fibroblasts, PAE decreased collagen I/III ratio and increased gene expression of profibrotic markers, including α-smooth muscle actin and lysyl oxidase. Notch1 signaling was assessed as a possible mechanism for fibroblast activation, and indicated that gene expression of Notch1 receptor and downstream Hey1 transcription factor were increased. Cardiac tissue analysis revealed decreased collagen I/III ratio and increased protein expression of α-smooth muscle actin and lysyl oxidase. However, Notch1 signaling components decreased in whole heart tissue. Our study demonstrates that PAE caused adverse changes in the cardiac collagen profile and a decline in cardiac function in the neonatal heart.

Fibroblast polarization over the myocardial infarction time continuum shifts roles from inflammation to angiogenesis.

Cardiac fibroblasts are the major producers of extracellular matrix (ECM) to form infarct scar. We hypothesized that fibroblasts undergo a spectrum of phenotype states over the course of myocardial infarction (MI) from early onset to scar formation. Fibroblasts were isolated from the infarct region of C57BL/6J male mice (3-6 months old, n = 60) at days 0 (no MI control) and 1, 3, or 7 after MI. Whole transcriptome analysis was performed by RNA-sequencing. Of the genes sequenced, 3371 were differentially expressed after MI. Enrichment analysis revealed that MI day 1 fibroblasts displayed pro-inflammatory, leukocyte-recruiting, pro-survival, and anti-migratory phenotype through Tnfrsf9 and CD137 signaling. MI day 3 fibroblasts had a proliferative, pro-fibrotic, and pro-angiogenic profile with elevated Il4ra signaling. MI day 7 fibroblasts showed an anti-angiogenic homeostatic-like myofibroblast profile and with a step-wise increase in Acta2 expression. MI day 7 fibroblasts relied on Pik3r3 signaling to mediate Tgfb1 effects and Fgfr2 to regulate PI3K signaling. In vitro, the day 3 MI fibroblast secretome stimulated angiogenesis, while day 7 MI fibroblast secretome repressed angiogenesis through Thbs1 signaling. Our results reveal novel mechanisms for fibroblasts in expressing pro-inflammatory molecules and regulating angiogenesis following MI.