Natriuretic peptides in the control of lipid metabolism and insulin sensitivity

Sacubitril/valsartan promotes white adipose tissue browning in rats with metabolic syndrome through activation of mTORC1

In addition to their usual use in the treatment of cardiovascular disease, weak evidence is available for the potential of combined use of neprilysin inhibitor (sacubitril) and AT1 receptor antagonist (valsartan) to promote browning of white adipose tissue (WAT) in rats with metabolic syndrome (MetS). This study involved 32 male Wistar albino rats divided into four groups: CTRL-healthy control rats; ENT-healthy rats treated with sacubitril/valsartan; MS-rats with MetS; MS + ENT-rats with MetS treated with sacubitril/valsartan. After finishing the experimental protocol, different WAT depots were isolated for further analysis of molecular pathways. Molecular docking and molecular dynamics studies were used for in silico assessment of the binding affinity of sacubitril and valsartan towards subunits of mechanistic target of rapamycin complex 1 (mTORC1). Sacubitril/valsartan treatment markedly diminished morphological changes in adipose tissue, resulting in smaller lipid size and multilocular lipid droplet structure in WAT. We showed significantly higher protein expression of uncoupling protein-1 (UCP-1) and mTORC1 in WAT of MS + ENT rats, correlating with increased relative gene expression of browning-related markers in tissue of rats treated with sacubitril/valsartan compared with MS group of rats. In silico analysis showed that sacubitrilat and valsartan exhibited the highest binding affinity against mTOR and mLST8, forming stable complexes with these mTORC1 subunits. The observed results confirmed strong potential of combined sacubitril/valsartan treatment to increase browning markers expression in different WAT depots in MetS condition and to form permanent complexes with mTOR and mLST8 subunits over the time.

Inflammation-mediated metabolic regulation in adipose tissue

Chronic inflammation of adipose tissue is a prominent characteristic of many metabolic diseases. Lipid metabolism in adipose tissue is consistently dysregulated during inflammation, which is characterized by substantial infiltration by proinflammatory cells and high cytokine concentrations. Adipose tissue inflammation is caused by a variety of endogenous factors, such as mitochondrial dysfunction, reactive oxygen species (ROS) production, endoplasmic reticulum (ER) stress, cellular senescence, ceramides biosynthesis and mediators of lipopolysaccharides (LPS) signaling. Additionally, the gut microbiota also plays a crucial role in regulating adipose tissue inflammation. Essentially, adipose tissue inflammation arises from an imbalance in adipocyte metabolism and the regulation of immune cells. Specific inflammatory signals, including nuclear factor-κB (NF-κB) signaling, inflammasome signaling and inflammation-mediated autophagy, have been shown to be involved in the metabolic regulation. The pathogenesis of metabolic diseases characterized by chronic inflammation (obesity, insulin resistance, atherosclerosis and nonalcoholic fatty liver disease [NAFLD]) and recent research regarding potential therapeutic targets for these conditions are also discussed in this review.

Increased sLRP1 and decreased atrial natriuretic peptide plasma levels in newly diagnosed T2DM patients are normalized after optimization of glycemic control

Background

Low-density lipoprotein receptor-related protein 1 (LRP1) negatively modulates circulating atrial natriuretic peptide (ANP) levels. Both molecules are involved in the regulation of cardiometabolism.

Objectives

To evaluate soluble LRP1 (sLRP1) and ANP levels in people with newly diagnosed type 2 diabetes mellitus (T2DM) and determine the effects of metabolic optimization.

Methods

This single-center longitudinal observational study recruited patients with newly diagnosed T2DM (n = 29, HbA1c > 8.5%), and 12 healthy control, age- and sex-matched volunteers. sLRP1 and ANP levels were measured by immunoassays at T2DM onset and at one year after optimization of glycemic control (HbA1c ≤ 6.5%).

Results

T2DM had higher sLRP1 levels than the control group (p = 0.014) and lower ANP levels (p =0.002). At 12 months, 23 T2DM patients reached the target of HbA1c ≤ 6.5%. These patients significantly reduced sLRP1 and increased ANP levels. Patients who did not achieve HbA1c < 6.5% failed to normalize sLRP1 and ANP levels. There was an inverse correlation in the changes in sLRP1 and ANP (p = 0.031). The extent of sLRP1 changes over 12 months of metabolic control positively correlated with those of total cholesterol, LDL cholesterol, TG, TG/HDLc, and apolipoprotein B.

Conclusions

Newly diagnosed T2DM patients have an increased sLRP1/ANP ratio, and increased sLRP1 and decreased ANP levels are normalized in the T2DM patients that reached an strict glycemic and metabolic control. sLRP1/ANP ratio could be a reliable marker of cardiometabolic function.

PPAR Alpha Activation by Clofibrate Alleviates Ischemia/Reperfusion Injury in Metabolic Syndrome Rats by Decreasing Cardiac Inflammation and Remodeling and by Regulating the Atrial Natriuretic Peptide Compensatory Response

Metabolic syndrome (MetS) is a cluster of factors that increase the risk of developing diabetes, stroke, and heart failure. The pathophysiology of injury by ischemia/reperfusion (I/R) is highly complex and the inflammatory condition plays an important role by increasing matrix remodeling and cardiac apoptosis. Natriuretic peptides (NPs) are cardiac hormones with numerous beneficial effects mainly mediated by a cell surface receptor named atrial natriuretic peptide receptor (ANPr). Although NPs are powerful clinical markers of cardiac failure, their role in I/R is still controversial. Peroxisome proliferator-activated receptor α agonists exert cardiovascular therapeutic actions; however, their effect on the NPs’ signaling pathway has not been extensively studied. Our study provides important insight into the regulation of both ANP and ANPr in the hearts of MetS rats and their association with the inflammatory conditions caused by damage from I/R. Moreover, we show that pre-treatment with clofibrate was able to decrease the inflammatory response that, in turn, decreases myocardial fibrosis, the expression of metalloprotease 2 and apoptosis. Treatment with clofibrate is also associated with a decrease in ANP and ANPr expression.

Review A State of Natriuretic Peptide Deficiency

Measurement of natriuretic peptides (NPs) has proven its clinical value as biomarker, especially in the context of heart failure (HF). In contrast, a state partial NP deficiency appears integral to several conditions in which lower NP concentrations in plasma presage overt cardiometabolic disease. Here, obesity and type 2 diabetes have attracted considerable attention. Other factors - including age, sex, race, genetics, and diurnal regulation - affect the NP "armory" and may leave some individuals more prone to development of cardiovascular disease. The molecular maturation of NPs has also proven complex with highly variable O-glycosylation within the biosynthetic precursors. The relevance of this regulatory step in post-translational propeptide maturation has recently become recognized in biomarker measurement/interpretation and cardiovascular pathophysiology. An important proportion of people appear to have reduced effective net NP bioactivity in terms of receptor activation and physiological effects. The state of NP deficiency, then, both entails a potential for further biomarker development and could also offer novel pharmacological possibilities. Alleviating the state of NP deficiency before development of overt cardiometabolic disease in selected patients could be a future path for improving precision medicine.

Natriuretic Peptides—New Targets for Neurocontrol of Blood Pressure via Baroreflex Afferent Pathway

Natriuretic peptides (NPs) induce vasodilation, natriuresis, and diuresis, counteract the renin–angiotensin–aldosterone system and autonomic nervous system, and are key regulators of cardiovascular volume and pressure homeostasis. Baroreflex afferent pathway is an important reflex loop in the neuroregulation of blood pressure (BP), including nodose ganglion (NG) and nucleus tractus solitarius (NTS). Dysfunction of baroreflex would lead to various hypertensions. Here, we carried out functional experiments to explore the effects of NPs on baroreflex afferent function. Under physiological and hypertensive condition (high-fructose drinking-induced hypertension, HFD), BP was reduced by NPs through NG microinjection and baroreflex sensitivity (BRS) was enhanced via acute intravenous NPs injection. These anti-hypertensive effects were more obvious in female rats with the higher expression of NPs and its receptor A/B (NPRA/NPRB) and lower expression of its receptor C (NPRC). However, these effects were not as obvious as those in HFD rats compared with the same gender control group, which is likely to be explained by the abnormal expression of NPs and NPRs in the hypertensive condition. Our data provide additional evidence showing that NPs play a crucial role in neurocontrol of BP regulation via baroreflex afferent function and may be potential targets for clinical management of metabolic-related hypertension.

Diabesity in Elderly Cardiovascular Disease Patients: Mechanisms and Regulators

Cardiovascular disease (CVD) is the leading cause of death in the world. In 2019, 550 million people were suffering from CVD and 18 million of them died as a result. Most of them had associated risk factors such as high fasting glucose, which caused 134 million deaths, and obesity, which accounted for 5.02 million deaths. Diabesity, a combination of type 2 diabetes and obesity, contributes to cardiac, metabolic, inflammation and neurohumoral changes that determine cardiac dysfunction (diabesity-related cardiomyopathy). Epicardial adipose tissue (EAT) is distributed around the myocardium, promoting myocardial inflammation and fibrosis, and is associated with an increased risk of heart failure, particularly with preserved systolic function, atrial fibrillation and coronary atherosclerosis. In fact, several hypoglycaemic drugs have demonstrated a volume reduction of EAT and effects on its metabolic and inflammation profile. However, it is necessary to improve knowledge of the diabesity pathophysiologic mechanisms involved in the development and progression of cardiovascular diseases for comprehensive patient management including drugs to optimize glucometabolic control. This review presents the mechanisms of diabesity associated with cardiovascular disease and their therapeutic implications.

Effects of sacubitril/valsartan on glycemia in patients with diabetes and heart failure: the PARAGON-HF and PARADIGM-HF trials

BACKGROUND

Compared with enalapril, sacubitril/valsartan lowered HbA1c and reduced new insulin therapy in patients with heart failure with reduced ejection fraction (HFrEF) and diabetes in the PARADIGM-HF trial. We sought to assess the glycemic effects of sacubitril/valsartan in heart failure with preserved ejection fraction (HFpEF) and diabetes, and across the spectrum of left ventricular ejection fraction (LVEF) in heart failure and diabetes.

METHODS

We compared the effect of sacubitril/valsartan, relative to valsartan, on HbA1c, new insulin therapy and hypoglycemia in the randomized controlled trial PARAGON-HF, and performed pooled analyses of PARAGON-HF and PARADIGM-HF.

RESULTS

Among 2395 patients with HFpEF and diabetes in PARAGON-HF, sacubitril/valsartan compared with valsartan reduced HbA1c (baseline-adjusted between-group difference in HbA1c change at 48 weeks: - 0.24%, 95% CI - 0.33 to - 0.16%, P < 0.001). Numerically, new insulin treatment was initiated less often in the sacubitril/valsartan group than in the valsartan group, but the difference was not statistically significant (12.8% vs. 16.1%; HR: 0.80, 95% CI 0.62-1.02, P = 0.07). Hypoglycemia adverse event reports were low, but more frequent in those receiving sacubitril/valsartan than in the valsartan group (4.2% vs. 2.6%; HR: 1.64, 95% CI 1.05-2.56, P = 0.030). In a pooled analysis of PARAGON-HF and PARADIGM-HF, the effect of sacubitril/valsartan on change in HbA1c was not significantly modified by LVEF (Pinteraction = 0.56). Across the spectrum of LVEF, sacubitril/valsartan reduced new insulin therapy (HR: 0.75, 95% CI 0.63-0.89, P = 0.001), compared with enalapril or valsartan.

CONCLUSIONS

Sacubitril/valsartan reduced HbA1c and new insulin therapy in patients with heart failure and diabetes across the spectrum of LVEF but may be associated with a slightly higher risk for hypoglycemia. Trial registration ClinicalTrials.gov NCT01920711.

Acute/Chronic Responses of Combined Training on Serum Pro-thermogenic/Anti-inflammatory Inducers and Its Relation With Fed and Fasting State in Overweight Type 2 Diabetic Individuals

Concentrations of pro-thermogenic/anti-inflammatory inductors are influenced by fed/fasting, sedentary/trained states, and metabolic pattern. However, there is a lack of information on the interactions of these conditions, especially in humans. Thus, the present study aimed to evaluate the chronic and acute training responses as well as the fed/fasted states of serum pro-thermogenic/anti-inflammatory inducers in overweight type 2 diabetics individuals. Fifteen individuals with type 2 diabetes [body mass index (BMI): 29.61 ± 3.60 kg/m2; age: 50.67 ± 3.97 years] participated in the study. In the pre- and post-experimental periods, baseline clinical parameters analyses were performed. Pro-thermogenic/anti-inflammatory inductors were evaluated pre/post-baseline and before, shortly after, and after 30′ and 60′ in the first and last sessions of a 16-week combined training (CT) period. These inducers were also compared for fasting and feeding before and after the training period. CT has improved baseline physical fitness, metabolic pattern, and it has also increased interleukin (IL)33 and FNDC5/irisin. In the first training session, there was a decrease in IL4, IL13, and IL33, besides an increase in FNDC5/irisin, and natriuretic peptides. In the last training session, there was an increase in natriuretic peptides and bone morphogenic protein 4 (BMP4). Differences in responses between the first and last training sessions were observed at certain post-session times for IL4, IL33, and natriuretic peptides, always with higher concentrations occurring in the last session. In evaluating the area under the curve (AUC) of the first and last training session, FNDC5/irisin, natriuretics peptides, and meteorin-like showed increased areas in the last training session. The pre-training fed state showed an increase in IL4 and IL33, while in fasting there was an increase in meteorin-like, natriuretic peptides, and FNDC5/irisin. In the post-training, IL4, IL13, and IL33 were increased in the fed state, while meteorin-like, natriuretic peptides, and FNDC5/irisin remained increased in the fast. Adaptation to physical training and a better metabolic pattern favor an improvement in the acute secretory pattern in part of pro-thermogenic and anti-inflammatory substances analyzed. The fed and fasting states also interfere differently in these substances, where fasting interferes with the increase of myokines, while the fed state induces an increase in interleukins.

Clinical Trial Registration: [http://www.ensaiosclinicos.gov.br/rg/RBR-62n5qn/], identifier [U1111-1202-1476].

Potential effects and application prospect of angiotensin receptor-neprilysin inhibitor in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the main causes of end-stage renal disease (ESRD) and all-cause mortality in diabetic patients, despite the extensive use of angiotensin-converting enzyme inhibitor (ACEI) and angiotensin II receptor blocker (ARB). Angiotensin receptor-neprilysin inhibitor (ARNI), combining ARB and neutral endopeptidase inhibitor (NEPI), is likely to have potential favorable effects in DKD. This review summarizes existing preclinical and clinical studies on mechanism of ARNI and its potential effects on DKD. In preclinical studies, ARNI manifested its renoprotective effects by improving natriuresis, ameliorating inflammation, oxidative stress and renal dysfunction, and slowing down glomerulosclerosis and tubulointerstitial injury of kidney, but its effect on proteinuria is still controversial. Beneficial effects of ARNI on blood glucose regulation and glycometabolism have also been reported. There are no clinical studies of ARNI that specifically focus on DKD patients so far. ARNI has application potential in DKD, but there still need clinical studies that focus on DKD patients to determine its effectiveness, safety and underlying mechanism.

Inhibition of phosphodiesterase type 9 reduces obesity and cardiometabolic syndrome in mice

Central obesity with cardiometabolic syndrome (CMS) is a major global contributor to human disease, and effective therapies are needed. Here, we show that cyclic GMP-selective phosphodiesterase 9A inhibition (PDE9-I) in both male and ovariectomized female mice suppresses preestablished severe diet-induced obesity/CMS with or without superimposed mild cardiac pressure load. PDE9-I reduces total body, inguinal, hepatic, and myocardial fat; stimulates mitochondrial activity in brown and white fat; and improves CMS, without significantly altering activity or food intake. PDE9 localized at mitochondria, and its inhibition in vitro stimulated lipolysis in a PPARα-dependent manner and increased mitochondrial respiration in both adipocytes and myocytes. PPARα upregulation was required to achieve the lipolytic, antiobesity, and metabolic effects of PDE9-I. All these PDE9-I-induced changes were not observed in obese/CMS nonovariectomized females, indicating a strong sexual dimorphism. We found that PPARα chromatin binding was reoriented away from fat metabolism-regulating genes when stimulated in the presence of coactivated estrogen receptor-α, and this may underlie the dimorphism. These findings have translational relevance given that PDE9-I is already being studied in humans for indications including heart failure, and efficacy against obesity/CMS would enhance its therapeutic utility.

Atrial Natriuretic Peptide31-67: A Novel Therapeutic Factor for Cardiovascular Diseases

The characterization of the cardiac hormone atrial natriuretic peptide (ANP_99–126), synthesized and secreted predominantly by atrial myocytes under stimulation by mechanical stretch, has established the heart as an endocrine organ with potent natriuretic, diuretic, and vasodilating actions. Three additional distinct polypeptides resulting from proteolytic cleavage of proANP have been identified in the circulation in humans. The mid-sequence proANP fragment 31–67 (also known as proANP_31–67) has unique potent and prolonged diuretic and natriuretic properties. In this review, we report the main effects of this circulating hormone in different tissues and organs, and its mechanisms of actions. We further highlight recent evidence on the cardiorenal protective actions of chronic supplementation of synthetic proANP_31–67 in preclinical models of cardiorenal disease. Finally, we evaluate the use of proANP_31–67 as a new therapeutic strategy to repair end-organ damage secondary to hypertension, diabetes mellitus, renal diseases, obesity, heart failure, and other morbidities that can lead to impaired cardiac function and structure.

Cardiovascular, anthropometric, metabolic and hormonal profiling of normotensive women with polycystic ovary syndrome with and without biochemical hyperandrogenism

PURPOSE

Women with polycystic ovary syndrome (PCOS) present with or without biochemical hyperandrogenism (HAPCOS or non-HAPCOS, respectively). Cardiometabolic and hormonal abnormalities have been reported in women with PCOS, particularly those with hypertension. However, no direct comparison between normotensive (blood pressure <140/90 mmHg) patients with HAPCOS and non-HAPCOS has been made. This study compared different cardiovascular (CV), anthropometric, metabolic and hormonal features between normotensive patients with HAPCOS and non-HAPCOS and healthy women.

METHODS

We consecutively recruited 249 normotensive patients with PCOS and 85 healthy eumenorrheic women to a case-control observational study. Based on blood androgen concentration, patients with PCOS were divided into HAPCOS (n = 69) or non-HAPCOS (n = 180) groups.

RESULTS

Although within normal ranges, patients with HAPCOS had significantly (p < 0.05) higher peripheral and central systolic blood pressure and pulse pressure, C-reactive protein, low-density lipoprotein cholesterol, triglycerides, glucose, and insulin than subjects with non-HAPCOS, and healthy women. They also had lower N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) concentration. In contrast, their body mass index (BMI) was higher of over 4 kg/m² than patients with non-HAPCOS and nearly 6 kg/m² than in healthy participants. Except for BMI, statistical differences in the cardiometabolic profile were of little clinical relevance.

CONCLUSIONS

Young normotensive women with HAPCOS have a worse cardiometabolic profile but lower NT-proBNP concentration than patients with non-HAPCOS. Features of this profile in both PCOS groups are within ranges typical for healthy women. Increased BMI is the only clinically relevant feature differentiating hyperandrogenic from non-hyperandrogenic patients with PCOS, and healthy women.

Association Between Serum Furin and Fasting Glucose: A Cross-Sectional Study in Chinese Adults

BACKGROUND

Furin has been associated with glucose metabolic phenotypes in small sampled clinical studies. However, this association has not yet been studied in Chinese. Here, we aimed to examine the association between serum furin and fasting glucose in Chinese adults.

METHODS

Serum furin and fasting plasma glucose were assayed for 2,172 participants (mean aged 53 years, 38% men) in the Gusu cohort. A median regression model was applied to examine the association between serum furin and fasting glucose, adjusting for age, sex, education level, cigarette smoking, alcohol drinking, obesity, blood pressure, and lipids. To facilitate data interpretation, the association between serum furin and prevalent diabetes was also examined.

RESULTS

Serum furin was negatively associated with fasting glucose (β=-0.18, P<0.001 for log-furin). In participants with diabetes, serum furin was significantly lower than those with normal glucose (median: 0.90 ng/mL vs. 1.05 ng/mL, P=0.001). Compared with participants in the highest quartile of serum furin, those in the lowest quartile had 42% and 80% increased risk of prevalent prediabetes (OR=1.42, 95%CI: 1.05-1.92, P=0.023) and diabetes (OR=1.80, 95%CI: 1.13-2.91, P=0.015), respectively.

CONCLUSIONS

Serum furin was negatively associated with prediabetes and diabetes in Chinese adults. Our findings suggest that serum furin may be a risk factor or a biomarker of diabetes.

Cardiac‑specific deletion of natriuretic peptide receptor A induces differential myocardial expression of circular RNA and mRNA molecules involved in metabolism in mice

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are important biological markers and regulators of cardiac function. The natriuretic peptide receptor A (NPRA), also known as NPR1 or guanylyl cyclase A, binds ANP and BNP to initiate transmembrane signal transduction by elevating the intracellular levels of cyclic guanosine monophosphate. However, the effects and mechanisms downstream of NPRA are largely unknown. The aim of the present study was to evaluate the changes in the global pattern of mRNA and circular RNA (circRNA) expression in NPRA‑/‑ and NPRA+/+ myocardium. Differentially expressed mRNA molecules were characterised using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis and were found to be primarily related to metabolic processes. Moreover, circRNA expression was also examined, and a possible competing endogenous RNA network consisting of circRNA, microRNA (miRNA), and mRNA molecules was constructed. The results of this study indicated that NPRA may play a role in cardiac metabolism, which could be mediated by circRNA through endogenous competition mechanisms. These findings may provide insight into future characterisation of various ceRNA network pathways.

Cardiac Autophagy Deficiency Attenuates ANP Production and Disrupts Myocardial-Adipose Cross Talk, Leading to Increased Fat Accumulation and Metabolic Dysfunction

Increased myocardial autophagy has been established as an important stress-induced cardioprotective response. Three weeks after generating cardiomyocyte-specific autophagy deficiency, via inducible deletion of autophagy-related protein 7 (Atg7), we found that these mice (AKO) had increased body weight and fat mass without altered food intake. Glucose and insulin tolerance tests indicated reduced insulin sensitivity in AKO mice. Metabolic cage analysis showed reduced ambulatory activity and oxygen consumption with a trend of elevated respiratory exchange ratio in AKO mice. Direct analysis of metabolism in subcutaneous and visceral adipocytes showed increased glucose oxidation and reduced ATGL expression and HSL phosphorylation with no change in lipid synthesis or fatty acid oxidation. Importantly, we found AKO mice had reduced myocardial and circulating levels of atrial natriuretic peptide (ANP), an established mediator of myocardial-adipose cross talk. When normal ANP levels were restored to AKO mice with use of osmotic pump, the metabolic dysfunction evident in AKO mice was corrected. We conclude that cardiac autophagy deficiency alters myocardial-adipose cross talk via decreased ANP levels with adverse metabolic consequences.

Angiotensin receptor neprilysin inhibitor as a novel antihypertensive drug: Evidence from Asia and around the globe

Hypertension is a worldwide epidemic that continues to grow, with a subset of patients responding poorly to current treatment available. This is especially relevant in Asia, which constitutes 61% of the global population. Hypertension in Asia is a unique entity that is often salt‐sensitive, nocturnal, and systolic predominant. Sacubitril/valsartan is a first‐in‐class angiotensin receptor neprilysin inhibitor that was first used in heart failure with reduced ejection fraction. Sacubitril inhibits neprilysin, a metallopeptidase that degrades natriuretic peptides (NPs). NPs exert sympatholytic, diuretic, natriuretic, vasodilatory, and insulin‐sensitizing effects mostly via cyclic guanosine monophosphate (cGMP)‐mediated pathways. As an antihypertensive agent, sacubitril/valsartan has outperformed angiotensin II receptor type 1 blockers (ARBs), with additional reductions of office systolic blood pressures ranging between 5 and 7 mmHg, in multiple studies in Asia and around the globe. The drug was well tolerated even in the elderly or those with chronic kidney disease. Its mechanisms of actions are particularly attractive for treatment of hypertension in Asia. Sacubitril/valsartan offers a novel, dual class, single‐molecule property that may be considered as first‐line antihypertensive therapy. Further investigations are needed to validate its safety for long‐term use and to explore other potentials such as in the management of insulin resistance and obesity, which often coexist with hypertension in Asia.

Adipokines, Myokines, and Cardiokines: The Role of Nutritional Interventions

It is now established that adipose tissue, skeletal muscle, and heart are endocrine organs and secrete in normal and in pathological conditions several molecules, called, respectively, adipokines, myokines, and cardiokines. These secretory proteins constitute a closed network that plays a crucial role in obesity and above all in cardiac diseases associated with obesity. In particular, the interaction between adipokines, myokines, and cardiokines is mainly involved in inflammatory and oxidative damage characterized obesity condition. Identifying new therapeutic agents or treatment having a positive action on the expression of these molecules could have a key positive effect on the management of obesity and its cardiac complications. Results from recent studies indicate that several nutritional interventions, including nutraceutical supplements, could represent new therapeutic agents on the adipo-myo-cardiokines network. This review focuses the biological action on the main adipokines, myokines and cardiokines involved in obesity and cardiovascular diseases and describe the principal nutraceutical approaches able to regulate leptin, adiponectin, apelin, irisin, natriuretic peptides, and follistatin-like 1 expression.

Lower levels of plasma NT-proBNP are associated with higher prevalence of NASH in patients with biopsy-proven NAFLD

BACKGROUND AND AIMS

Emerging evidence suggests that plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) levels are decreased in patients with imaging-defined nonalcoholic fatty liver disease (NAFLD), but no data are currently available on the association between plasma NT-proBNP levels and the histological severity of NAFLD.

METHODS AND RESULTS

We enrolled 351 (73.5% men) consecutive adult patients with biopsy-proven NAFLD without a prior history of cardiovascular disease (CVD). Plasma NT-proBNP levels were measured using a commercially available immunochemical system (VITROS® 5600, Johnson, New Jersey). Fifty-three percent of these subjects had nonalcoholic steatohepatitis (NASH). After stratification of patients by plasma NT-proBNP tertiles; compared to those in the 1st tertile (NT-proBNP ≤16 pg/ml), the odds ratio for NASH was 0.52 (95% CI 0.29-0.95) in patients in the 2nd tertile (NT-proBNP of 17-33 pg/ml) and 0.49 (95% CI 0.26-0.93) in those in the 3rd tertile (NT-proBNP ≥34 pg/ml) of plasma NT-proBNP levels, even after adjustment for age, sex, body mass index, homeostasis model assessment (HOMA)-estimated insulin resistance, pre-existing diabetes, hypertension, and dyslipidemia.

CONCLUSION

In subjects with biopsy-proven NAFLD without known CVD, this cross-sectional study shows for the first time, that lower plasma NT-proBNP levels are strongly associated with a higher prevalence of NASH.

Biomarker-defined pathways for incident type 2 diabetes and coronary heart disease-a comparison in the MONICA/KORA study

Background

Biomarkers may contribute to our understanding of the pathophysiology of various diseases. Type 2 diabetes (T2D) and coronary heart disease (CHD) share many clinical and lifestyle risk factors and several biomarkers are associated with both diseases. The current analysis aims to assess the relevance of biomarkers combined to pathway groups for the development of T2D and CHD in the same cohort.

Methods

Forty-seven serum biomarkers were measured in the MONICA/KORA case-cohort study using clinical chemistry assays and ultrasensitive molecular counting technology. The T2D (CHD) analyses included 689 (568) incident cases and 1850 (2004) non-cases from three population-based surveys. At baseline, the study participants were 35–74 years old. The median follow-up was 14 years. We computed Cox regression models for each biomarker, adjusted for age, sex, and survey. Additionally, we assigned the biomarkers to 19 etiological pathways based on information from literature. One age-, sex-, and survey-controlled average variable was built for each pathway. We used the R²_PM coefficient of determination to assess the explained disease risk.

Results

The associations of many biomarkers, such as several cytokines or the iron marker soluble transferrin receptor (sTfR), were similar in strength for T2D and CHD, but we also observed important differences. Lipoprotein (a) (Lp(a)) and N-terminal pro B-type natriuretic peptide (NT-proBNP) even demonstrated opposite effect directions. All pathway variables together explained 49% of the T2D risk and 21% of the CHD risk. The insulin-like growth factor binding protein 2 (IGFBP-2, IGF/IGFBP system pathway) best explained the T2D risk (about 9% explained risk, independent of all other pathway variables). For CHD, the myocardial-injury- and lipid-related-pathways were most important and both explained about 4% of the CHD risk.

Conclusions

The biomarker-derived pathway variables explained a higher proportion of the T2D risk compared to CHD. The ranking of the pathways differed between the two diseases, with the IGF/IGFBP-system-pathway being most strongly associated with T2D and the myocardial-injury- and lipid-related-pathways with CHD. Our results help to better understand the pathophysiology of the two diseases, with the ultimate goal of pointing out targets for lifestyle intervention and drug development to ideally prevent both T2D and CHD development.

A novel peptide RIFV suppresses human adipocyte differentiation through the inhibition of C/EBP-β expression

Background

Obesity is a global epidemic disease that increases the risk of metabolic syndrome. However, therapeutic drugs for obesity are still scarce. In recent years, peptides have been identified as new biological regulators. RIFV (R-I-F-V-P-I-K-G-R-P-A-P), a novel active peptide from our peptide database.

Methods

We performed oil red O staining and triglyceride measurement to analyze the influence of RIFV on white preadipocytes differentiation. Then the effects of RIFV on cell proliferation, apoptosis and cell cycle were determined by using CCK-8 assay and flow cytometry. The mRNA and protein levels of adipogenesis-related genes were respectively detected by qRT-PCR and western blot. Rescue experiment was conducted to confirm whether RIFV could regulate adipocytes differentiation via targeting C/EBP-β. Finally, the luciferase reporter gene assay was performed to verify the regulation of RIFV on C/EBP-β gene.

Results

RIFV was revealed to inhibit the differentiation of human white adipocytes without affecting their proliferation. Additionally, RIFV could also suppress the differentiation of mouse primary white preadipocytes isolated from inguinal fat tissues. Furthermore, RIFV may have an inhibitory effect on adipogenesis by inhibiting the regulation of the adipogenic gene C/EBP-β.

Conclusions

Our results indicated that RIFV may be a novel essential regulator of adipocyte differentiation and represents a therapeutic strategy for obesity and related complications.

Natriuretic peptide signaling is involved in the expression of oxidative metabolism-related and muscle fiber constitutive genes in the gastrocnemius muscle

Natriuretic peptides regulate cyclic guanosine monophosphate (cGMP) levels via their receptors and have various physiological effects. Natriuretic peptide receptor C (NPR-C) increases cGMP signaling by functioning as a clearance receptor. We analyzed the role of natriuretic peptides in the skeletal muscle, which increases in mass with bone elongation, of NPR-C- mice. High-fat diet (HFD)-fed NPR-C- mice exhibited obesity resistance and higher oxygen consumption. PGC1α gene expression was upregulated in the gastrocnemius muscle of HFD-fed NPR-C- mice compared with HFD-fed NPR-C+ (wild-type) mice. Gene expression of proliferator-activated receptor delta and estrogen-related receptor α, which upregulate oxidative metabolism, was increased in the gastrocnemius muscle of NPR-C- mice, irrespective of diet. Expression of myosin heavy chain 7, a component of type I slow-twitch fiber, was enhanced. Natriuretic peptide signaling may influence oxidative metabolism-related and slow-twitch fiber constitutive gene expression in the fast-twitch gastrocnemius muscle but not in slow-twitch muscles such as the soleus.

Adrenergically and non-adrenergically mediated human adipose tissue lipolysis during acute exercise and exercise training

Obesity-related adipose tissue (AT) dysfunction, in particular subcutaneous AT (SCAT) lipolysis, is characterized by catecholamine resistance and impaired atrial natriuretic peptide (ANP) responsiveness. It remains unknown whether exercise training improves (non-)adrenergically mediated lipolysis in metabolically compromised conditions. We investigated the effects of local combined α-/β-adrenoceptor blockade on abdominal SCAT lipolysis in lean insulin sensitive (IS) (n=10), obese IS (n=10), and obese insulin resistant (IR) (n=10) men. Obese men participated in a 12-week exercise training intervention to determine the effects on SCAT lipolysis. Abdominal SCAT extracellular glycerol concentration and blood flow (ATBF) were investigated using microdialysis, with/without locally combined α-/β-adrenoceptor blockade at rest, during low-intensity endurance-type exercise and post-exercise recovery. In obese IR men, microdialysis was repeated after exercise intervention. The exercise-induced increase in SCAT extracellular glycerol was more pronounced in obese IS compared with lean IS men, possibly resulting from lower ATBF in obese IS men. The exercise-induced increase in extracellular glycerol was blunted in obese IR compared with obese IS men, despite comparable local ATBF. Abdominal SCAT extracellular glycerol was markedly reduced (remaining ~60% of exercise-induced SCAT extracellular glycerol) following the local α-/β-adrenoceptor blockade in obese IS but not in IR men, suggesting reduced catecholamine-mediated lipolysis during exercise in obese IR men. Exercise training did not affect (non-)adrenergically mediated lipolysis in obese IR men. Our findings showed a major contribution of non-adrenergically-mediated lipolysis during exercise in male abdominal SCAT. Furthermore, catecholamine-mediated lipolysis may be blunted during exercise in obese IR men but could not be improved by exercise intervention, despite an improved metabolic profile and body composition.

β Cell-specific deletion of guanylyl cyclase A, the receptor for atrial natriuretic peptide, accelerates obesity-induced glucose intolerance in mice

BACKGROUND

The cardiac hormones atrial (ANP) and B-type natriuretic peptides (BNP) moderate arterial blood pressure and improve energy metabolism as well as insulin sensitivity via their shared cGMP-producing guanylyl cyclase-A (GC-A) receptor. Obesity is associated with impaired NP/GC-A/cGMP signaling, which possibly contributes to the development of type 2 diabetes and its cardiometabolic complications. In vitro, synthetic ANP, via GC-A, stimulates glucose-dependent insulin release from cultured pancreatic islets and β-cell proliferation. However, the relevance for systemic glucose homeostasis in vivo is not known. To dissect whether the endogenous cardiac hormones modulate the secretory function and/or proliferation of β-cells under (patho)physiological conditions in vivo, here we generated a novel genetic mouse model with selective disruption of the GC-A receptor in β-cells.

METHODS

Mice with a floxed GC-A gene were bred to Rip-Cre^TG mice, thereby deleting GC-A selectively in β-cells (β GC-A KO). Weight gain, glucose tolerance, insulin sensitivity, and glucose-stimulated insulin secretion were monitored in normal diet (ND)- and high-fat diet (HFD)-fed mice. β-cell size and number were measured by immunofluorescence-based islet morphometry.

RESULTS

In vitro, the insulinotropic and proliferative actions of ANP were abolished in islets isolated from β GC-A KO mice. Concordantly, in vivo, infusion of BNP mildly enhanced baseline plasma insulin levels and glucose-induced insulin secretion in control mice. This effect of exogenous BNP was abolished in β GC-A KO mice, corroborating the efficient inactivation of the GC-A receptor in β-cells. Despite this under physiological, ND conditions, fasted and fed insulin levels, glucose-induced insulin secretion, glucose tolerance and β-cell morphology were similar in β GC-A KO mice and control littermates. However, HFD-fed β GC-A KO animals had accelerated glucose intolerance and diminished adaptative β-cell proliferation.

CONCLUSIONS

Our studies of β GC-A KO mice demonstrate that the cardiac hormones ANP and BNP do not modulate β-cell's growth and secretory functions under physiological, normal dietary conditions. However, endogenous NP/GC-A signaling improves the initial adaptative response of β-cells to HFD-induced obesity. Impaired β-cell NP/GC-A signaling in obese individuals might contribute to the development of type 2 diabetes.

N-terminal pro B-Type natriuretic peptide is inversely correlated with low density lipoprotein cholesterol in the very elderly

BACKGROUND AND AIMS

Laboratory studies on human adipose tissue and differentiated adipocytes indicate that natriuretic peptides (NPs) affect lipid metabolism and plasma cholesterol. Few previous clinical studies in non-elderly populations found associations between NPs in the physiological range and cholesterol.

AIM

evaluate the association between NT-proBNP and lipid profile in very elderly hospitalized patients characterized by a wide range of NT-proBNP levels.

METHODS AND RESULTS

Cross-sectional study on 288 very elderly patients hospitalized for medical conditions, in which increased NT-proBNP levels are very common. NT-proBNP, total cholesterol (TC), HDL cholesterol (HDLc) and triglycerides were collected just few days before discharge. Patients taking lipid-lowering drugs and patients with an admission diagnosis of acute heart failure were excluded. Calculated LDL-cholesterol (LDLc) was used for the analyses. Mean age: 87.7 ± 6.2 years; female prevalence (57.3%). Median NT-proBNP: 2949 (1005-7335) pg/ml; mean TC: 145.1 ± 40.3 mg/dl; mean HDLc: 38.4 ± 18.6 mg/dl; median triglycerides: 100 (75-129) mg/dl; mean LDLc: 84.0 ± 29.5 mg/dl. We found negative correlations between NT-proBNP and both TC and LDLc (Rho = -0.157; p = 0.008 and Rho = -0.166; p = 0.005, respectively), while no correlations emerged between NT-proBNP and HDLc (Rho = -0.065; p = 0.275) or triglycerides (Rho = -0.009; p = 0.874). These associations were confirmed considering NT-proBNP tertiles. The inverse association between NT-proBNP and LDLc was maintained even after adjusting for confounding factors.

CONCLUSION

Our real-life clinical study supports the hypothesis that NPs play a role on cholesterol metabolism, given the association found between LDLc and NT-proBNP even in very elderly patients where NT-proBNP values are often in the pathological range.

Regulation of Lipolysis in Adipose Tissue and Clinical Significance

Lipolysis is a critical process to hydrolyze triglyceride in adipose tissue, thereby breaking down the stored lipid and maintaining energy homeostasis. Recent studies have made significant progress in understanding the steps of lipolysis. This chapter discusses the major pathways that regulate lipolysis in adipose tissue. Specifically we focus on the mechanisms by which the activities of critical lipolytic enzymes are regulated. We further discuss how the lipolysis is regulated by other factors, including insulin and neurotransmitters, in particular catecholamines and the role of sympathetic nervous system in the whole process. Finally we provide clinical perspectives about the novel therapeutic strategies to target or promote adipose tissue lipolysis for treatment/prevention of obesity and type 2 diabetes.