Correction: Noureddine et al. Impact of the Renin-Angiotensin System on the Endothelium in Vascular Dementia: Unresolved Issues and Future Perspectives. Int. J. Mol. Sci. 2020, 21, 4268

The authors would like to make the following correction to the publication dealing with Reference #3 [...].

Exploring the Promise and Challenges of Artificial Intelligence in Biomedical Research and Clinical Practice

Artificial intelligence (AI) is poised to revolutionize how science, and biomedical research in particular, are done. With AI, problem solving and complex tasks using massive data sets can be performed at a much higher rate and dimensionality level compared to humans. With the ability to handle huge data sets and self-learn, AI is already being exploited in drug design, drug repurposing, toxicology, and material identification. AI could also be used in both basic and clinical research in study design, defining outcomes, analyzing data, interpreting findings, and even identifying the most appropriate areas of investigation and funding sources. State-of-the-art AI-based large language models (LLM), such as ChatGPT and Perplexity, are positioned to change forever how science is communicated and how scientists interact with one another and their profession, including post-publication appraisal and critique. Like all revolutions, upheaval will follow and not all outcomes can be predicted, necessitating guardrails at the onset, especially to minimize the untoward impact of the many drawbacks of LLMs, which include lack of confidentiality, risk of hallucinations, and propagation of mainstream albeit potentially mistaken opinions and perspectives. In this review, we highlight areas of biomedical research that are already being reshaped by AI and how AI is likely to impact it further in the near future. We discuss the potential benefits of AI in biomedical research and address possible risks, some surrounding the creative process, that warrant further reflection.

Caloric Restriction Rejuvenates Skeletal Muscle Growth in Heart Failure With Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a major clinical problem, with limited treatments. HFpEF is characterized by a distinct, but poorly understood, skeletal muscle pathology, which could offer an alternative therapeutic target. In a rat model, we identified impaired myonuclear accretion as a mechanism for low myofiber growth in HFpEF following resistance exercise. Acute caloric restriction rescued skeletal muscle pathology in HFpEF, whereas cardiac therapies had no effect. Mechanisms regulating myonuclear accretion were dysregulated in patients with HFpEF. Overall, these findings may have widespread implications in HFpEF, indicating combined dietary with exercise interventions as a beneficial approach to overcome skeletal muscle pathology.

Central role for BRAF in cardiac hypertrophy: rethinking the pathological-physiological divide

The RAF/MEK/ERK1/2 signaling cascade has been implicated in pathological cardiac hypertrophy downstream of some Gq-coupled receptors. The RAF family of kinases consists of three isoforms (ARAF, BRAF, and CRAF) and until recently most studies on this signaling pathway in the heart have focused on RAF1 (CRAF). In a recent issue of Clinical Science, Alharbi et al. utilized an inducible cardiac myocyte targeted knockout mouse model to define the role of BRAF in pathological versus physiological hypertrophy using angiotensin II and phenylephrine (PE) infusion, respectively. They reported that loss of BRAF attenuated both pathological cardiac hypertrophy and interstitial fibrosis. BRAF knockout decreased cardiac function with PE in male mice and enhanced both interstitial and perivascular cardiac fibrosis but had no effect on hypertrophy. In contrast, loss of BRAF attenuated physiological hypertrophy in female mice but had no effect on fibrosis or contractility. These observations extend those previously made by this group assessing the consequences of expressing an inducible activating mutant of BRAF in the heart and the benefit of enhancing RAF/MEK/ERK1/2 signaling by exploiting the 'RAF paradox'. Additional studies are needed to better define the role of BRAF under conditions reflective of chronic stress on the heart due to the biomechanical stimulation exerted by hypertension. In addition, the role of BRAF and its activation in overt heart failure remains to be established. Nevertheless, the new findings highlight the potential importance of additional signaling events, perhaps related to RAF1 or ERK1/2 activation, in shaping BRAF signaling in a sex- and context-dependent manner.

Genomic, Proteomic, and Metabolic Comparisons of Small Animal Models of Heart Failure With Preserved Ejection Fraction: A Tale of Mice, Rats, and Cats

Heart failure with preserved ejection fraction (HFpEF) remains a medical anomaly that baffles researchers and physicians alike. The overall phenotypical changes of diastolic function and left ventricular hypertrophy observed in HFpEF are definable; however, the metabolic and molecular alterations that ultimately produce these changes are not well established. Comorbidities such as obesity, hypertension, and diabetes, as well as general aging, play crucial roles in its development and progression. Various animal models have recently been developed to better understand the pathophysiological and metabolic developments in HFpEF and to illuminate novel avenues for pharmacotherapy. These models include multi‐hit rodents and feline aortic constriction animals. Recently, genomic, proteomic, and metabolomic approaches have been used to define altered signaling pathways in the heart associated with HFpEF, including those involved in inflammation, cGMP‐related, Ca²⁺ handling, mitochondrial respiration, and the unfolded protein response in endoplasmic reticulum stress. This article aims to present an overview of what has been learnt by these studies, focusing mainly on the findings in common while highlighting unresolved issues. The knowledge gained from these research models will not simply be of benefit for treating HFpEF but will undoubtedly provide new insights into the mechanisms by which the heart deals with external stresses and how the processes involved can fail.

Insights into the modulation of the interferon response and NAD+ in the context of COVID-19

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in dramatic worldwide mortality. Along with developing vaccines, the medical profession is exploring new strategies to curb this pandemic. A better understanding of the molecular consequences of SARS-CoV-2 cellular infection could lead to more effective and safer treatments. This review discusses the potential underlying impact of SARS-CoV-2 in modulating interferon (IFN) secretion and in causing mitochondrial NAD⁺ depletion that could be directly linked to COVID-19's deadly manifestations. What is known or surmised about an imbalanced innate immune response and mitochondrial dysfunction post-SARS-CoV-2 infection, and the potential benefits of well-timed IFN treatments and NAD⁺ boosting therapies in the context of the COVID-19 pandemic are discussed.

ProANP31-67 ameliorates adverse cardiac remodeling and improves systolic and diastolic functions in a preclinical model of cardiorenal syndrome

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): South-Eastern Norway Regional Health Authority (HSØ-RHF, Project No. 25674)

Background

The cardiac hormone proANP31-67, a linear fragment of the N-terminal Atrial Natriuretic Peptide, has known enhancing renal effects. More recently, we described the cardio protective effects of this hormone in a model of chronic hypertension. More specifically, independently of the blood pressure level, proANP31-67 improved diastolic function, attenuated cardiac fibrosis, and reduced hypertrophy.

Purpose

The current study was designed to assess the cardiorenal effects of proANP31-67 in a rodent model of hampered renal function, followed by cardiac injury produced by ischemia/reperfusion (I/R).

Methods

Right uninephrectomy (UNX) was performed in Wistar rats (n=28). Sixteen weeks after UNX, rats underwent cardiac I/R injury and randomly assigned to proANP31-67 (50 ng/kg/day s.c., n=15) or Vehicle (n=13) for four weeks post I/R. Echocardiographic examinations were performed at baseline (before UNX), 16 weeks after UNX, and four weeks after I/R. At the end of the study, cardiomyocytes were isolated and tissue samples were collected.

Results

Chronic UNX resulted in diastolic impairment (E/A: 1.47±0.08 at baseline vs 0.98±0.14 at 16 wks post UNX, p=0.0010). I/R further accentuated the development of the cardiorenal syndrome, and induced a mild systolic dysfunction in the placebo treated animals. However, four weeks of treatment with proANP31-67 preserved systolic function (EF: 62±3% placebo vs 74±2% proANP31-67, p<0.0001), and reverted the diastolic dysfunction (E/A: 0.72±0.15 placebo vs 1.24±0.11 proANP31-67, p=0.0134). ProANP31-67 ameliorated the adverse cardiac remodeling (i.e., reduction in the cardiomyocyte cross-sectional area and interstitial fibrosis), enhanced Ca2+ handling, and improved cardiomyocyte t-tubules´ structural changes compared to vehicle. At the cellular level, in vitro experiments demonstrated the direct effect of proANP31-67 on cardiomyocyte hypertrophy (assessed by [3H]-leucine incorporation) induced by endothelin 1 and angiotensin II.

Conclusion

ProANP31-67 has a direct cardiomyocyte protective effect, leading to an improvement in Ca2+ homeostasis and t-tubules´ structures and, prevents the development of systolic and diastolic dysfunction in a pre-clinical model of cardiorenal syndrome.

Etiology-Dependent Impairment of Diastolic Cardiomyocyte Calcium Homeostasis in Heart Failure With Preserved Ejection Fraction

BACKGROUND

Whereas heart failure with reduced ejection fraction (HFrEF) is associated with ventricular dilation and markedly reduced systolic function, heart failure with preserved ejection fraction (HFpEF) patients exhibit concentric hypertrophy and diastolic dysfunction. Impaired cardiomyocyte Ca²⁺ homeostasis in HFrEF has been linked to disruption of membrane invaginations called t-tubules, but it is unknown if such changes occur in HFpEF.

OBJECTIVES

This study examined whether distinct cardiomyocyte phenotypes underlie the heart failure entities of HFrEF and HFpEF.

METHODS

T-tubule structure was investigated in left ventricular biopsies obtained from HFrEF and HFpEF patients, whereas cardiomyocyte Ca²⁺ homeostasis was studied in rat models of these conditions.

RESULTS

HFpEF patients exhibited increased t-tubule density in comparison with control subjects. Super-resolution imaging revealed that higher t-tubule density resulted from both tubule dilation and proliferation. In contrast, t-tubule density was reduced in patients with HFrEF. Augmented collagen deposition within t-tubules was observed in HFrEF but not HFpEF hearts. A causative link between mechanical stress and t-tubule disruption was supported by markedly elevated ventricular wall stress in HFrEF patients. In HFrEF rats, t-tubule loss was linked to impaired systolic Ca²⁺ homeostasis, although diastolic Ca²⁺ removal was also reduced. In contrast, Ca²⁺ transient magnitude and release kinetics were largely maintained in HFpEF rats. However, diastolic Ca²⁺ impairments, including reduced sarco/endoplasmic reticulum Ca²⁺-ATPase activity, were specifically observed in diabetic HFpEF but not in ischemic or hypertensive models.

CONCLUSIONS

Although t-tubule disruption and impaired cardiomyocyte Ca²⁺ release are hallmarks of HFrEF, such changes are not prominent in HFpEF. Impaired diastolic Ca²⁺ homeostasis occurs in both conditions, but in HFpEF, this mechanism for diastolic dysfunction is etiology-dependent.

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.

Distorted assessment of left atrial size by echocardiography in patients with increased aortic root diameter

Background

Left atrial (LA) size is frequently assessed by posterior-anterior linear measurement of LA (LAD P-A) in the parasternal long axis to expedite examination. Aging, changes in body surface area, and several cardiovascular pathologies can affect aortic root (AoR) size, thereby affecting LA anatomical shape. We hypothesized that AoR dilatation influences LAD P-A and consequently correct assessment of LA size.

Results

We tested our hypothesis in a study of 70 patients with AoR diameter ranging from 2.7 to 4.8 cm. LA size assessed in parasternal long axis view as LAD P-A was compared to that with LA width and length acquired in the apical two and four chamber view. Simpson’s method of discs was used as standard measurement to assess LA volume.

We observed that LAD P-A in the parasternal long axis decreases when AoR diameter increases. Thus, the increase in LA size assessed in parasternal long axis did not correlate with the increase of LA volume. Further analysis revealed that a significant positive correlation was observed when LAV was plotted as a function of LAD P-A only for those with a normal size AoR. In contrast, LA volume increase correlated with LA diameters assessed in the apical two and four chamber view regardless of AoR size.

Conclusions

Our study documents that increases in AoR impact on the linear measurement of LA, resulting in an underestimated LAD P-A. LA size ought to be calculated from the apical two and four chambers view parameters, especially in patients with AoR dilatation.

Nicotinamide adenine dinucleotide: Biosynthesis, consumption and therapeutic role in cardiac diseases

Nicotinamide adenine dinucleotide (NAD) is an abundant cofactor that plays crucial roles in several cellular processes. NAD can be synthesized de novo starting with tryptophan, or from salvage pathways starting with NAD precursors like nicotinic acid (NA), nicotinamide (NAM) or nicotinamide riboside (NR), referred to as niacin/B₃ vitamins, arising from dietary supply or from cellular NAD catabolism. Given the interconversion between its oxidized (NAD⁺ ) and reduced form (NADH), NAD participates in a wide range of reactions: regulation of cellular redox status, energy metabolism and mitochondrial biogenesis. Plus, NAD acts as a signalling molecule, being a cosubstrate for several enzymes such as sirtuins, poly-ADP-ribose-polymerases (PARPs) and some ectoenzymes like CD38, regulating critical biological processes like gene expression, DNA repair, calcium signalling and circadian rhythms. Given the large number of mitochondria present in cardiac tissue, the heart has the highest NAD levels and is one of the most metabolically demanding organs. In several models of heart failure, myocardial NAD levels are depressed and this depression is caused by mitochondrial dysfunction, metabolic remodelling and inflammation. Emerging evidence suggests that regulating NAD homeostasis by NAD precursor supplementation has therapeutic efficiency in improving myocardial bioenergetics and function. This review provides an overview of the latest understanding of the different NAD biosynthesis pathways, as well as its role as a signalling molecule particularly in cardiac tissue. We highlight the significance of preserving NAD equilibrium in various models of heart diseases and shed light on the potential pharmacological interventions aiming to use NAD boosters as therapeutic agents.

Macrophage responses associated with COVID-19: A pharmacological perspective

COVID-19 has caused worldwide death and economic destruction. The pandemic is the result of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has demonstrated high rates of infectivity leading to great morbidity and mortality in vulnerable populations. At present, scientists are exploring various approaches to curb this pandemic and alleviate its health consequences, while racing to develop a vaccine. A particularly insidious aspect of COVID-19 is the delayed overactivation of the body's immune system that is manifested as the cytokine storm. This unbridled production of pro-inflammatory cytokines and chemokines can directly or indirectly cause massive organ damage and failure. Systemic vascular endothelial inflammation and thrombocytopenia are potential consequences as well. In the case of COVID-19, the cytokine storm often fits the pattern of the macrophage activation syndrome with lymphocytopenia. The basis for the imbalance between the innate and adaptive immune systems is not clearly defined, but highlights the effect of SARS-CoV-2 on macrophages. Here we discuss the potential underlying basis for the impact of SARS-CoV-2 on macrophages, both direct and indirect, and potential therapeutic targets. These include granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 6 (IL-6), interferons, and CXCL10 (IP-10). Various biopharmaceuticals are being repurposed to target the cytokine storm in COVID-19 patients. In addition, we discuss the rationale for activating the macrophage alpha 7 nicotinic receptors as a therapeutic target. A better understanding of the molecular consequences of SARS-CoV-2 infection of macrophages could lead to novel and more effective treatments for COVID-19.

Sex-based differences in myocardial infarction-induced kidney damage following cigarette smoking exposure: more renal protection in premenopausal female mice

The impact of cigarette smoking (CS) on kidney homeostasis in the presence of myocardial infarction (MI) in both males and females remains poorly elucidated. C57BL6/J mice were exposed to 2 weeks of CS prior to MI induction followed by 1 week of CS exposure in order to investigate the impact of CS on kidney damage in the presence of MI. Cardiac hemodynamic analysis revealed a significant decrease in ejection fraction (EF) in CS-exposed MI male mice when compared with the relative female subjects, whereas cardiac output (CO) comparably decreased in CS-exposed MI mice of both sexes. Kidney structural alterations, including glomerular retraction, proximal convoluted tubule (PCT) cross-sectional area, and total renal fibrosis were more pronounced in CS-exposed MI male mice when compared with the relative female group. Although renal reactive oxygen species (ROS) generation and glomerular DNA fragmentation significantly increased to the same extent in CS-exposed MI mice of both sexes, alpha-smooth muscle actin (α-SMA) and connective tissue growth factor (CTGF) significantly increased in CS-exposed MI male mice, only. Metabolically, nicotinamide phosphoribosyltransferase (NAMPT) and nicotinamide riboside-1 (NMRK-1) substantially increased in CS-exposed MI female mice only, whereas sirtuin (SIRT)-1 and SIRT-3 substantially decreased in CS-exposed MI male mice compared with their relative female group. Additionally, renal NAD levels significantly decreased only in CS-exposed MI male mice. In conclusion, MI female mice exhibited pronounced renal protection following CS when compared with the relative male groups.

Impact of the Renin-Angiotensin System on the Endothelium in Vascular Dementia: Unresolved Issues and Future Perspectives

The effects of the renin-angiotensin system (RAS) surpass the renal and cardiovascular systems to encompass other body tissues and organs, including the brain. Angiotensin II (Ang II), the most potent mediator of RAS in the brain, contributes to vascular dementia via different mechanisms, including neuronal homeostasis disruption, vascular remodeling, and endothelial dysfunction caused by increased inflammation and oxidative stress. Other RAS components of emerging significance at the level of the blood-brain barrier include angiotensin-converting enzyme 2 (ACE2), Ang(1-7), and the AT2, Mas, and AT4 receptors. The various angiotensin hormones perform complex actions on brain endothelial cells and pericytes through specific receptors that have either detrimental or beneficial actions. Increasing evidence indicates that the ACE2/Ang(1-7)/Mas axis constitutes a protective arm of RAS on the blood-brain barrier. This review provides an update of studies assessing the different effects of angiotensins on cerebral endothelial cells. The involved signaling pathways are presented and help highlight the potential pharmacological targets for the management of cognitive and behavioral dysfunctions associated with vascular dementia.

Cardioprotective Effects of the Novel Compound Vastiras in a Preclinical Model of End-Organ Damage

Cardiac hypertrophy and renal damage associated with hypertension are independent predictors of morbidity and mortality. In a model of hypertensive heart disease and renal damage, we tested the actions of continuous administration of Vastiras, a novel compound derived from the linear fragment of ANP (atrial natriuretic peptide), namely pro-ANP_31-67, on blood pressure and associated renal and cardiac function and remodeling. Of note, this peptide, unlike the ring structured forms, does not bind to the classic natriuretic peptide receptors. Dahl/Salt-Sensitive rats fed a 4% NaCl diet for 6 weeks developed hypertension, cardiac hypertrophy, and renal damage. Four weeks of treatment with 50 to 100 ng/kg per day of Vastiras exhibited positive effects on renal function, independent of blood pressure regulation. Treated rats had increased urine excretion, natriuresis, and enhanced glomerular filtration rate. Importantly, these favorable renal effects were accompanied by improved cardiac structure and function, including attenuated cardiac hypertrophy, as indicated by decreased heart weight to body weight ratio, relative wall thickness, and left atrial diameter, as well as reduced fibrosis and normalized ratio of the diastolic mitral inflow E wave to A wave. A renal subtherapeutic dose of Vastiras (25 ng/kg per day) induced similar protective effects on the heart. At the cellular level, cardiomyocyte size and t-tubule density were preserved in Vastiras-treated compared with untreated animals. In conclusion, these data demonstrate the cardiorenal protective actions of chronic supplementation of a first-in-class compound, Vastiras, in a preclinical model of maladaptive cardiac hypertrophy and renal damage induced by hypertension.

STAT3 and Endothelial Cell-Cardiomyocyte Dialog in Cardiac Remodeling

This article presents an overview of the central role of STAT3 in the crosstalk between endothelial cells and cardiac myocytes in the heart. Endothelial cell STAT3 has a key role in inflammation that underlies cardiovascular disease and impacts on cardiac structure and function. STAT3 in endothelial cells contributes to adverse cardiomyocyte genetic reprograming, for instance, during peripartum cardiomyopathy. Conversely, cardiomyocyte STAT3 is important for maintaining endothelial cell function and capillary integrity with aging and hypertension. In addition, STAT3 serves as a sentinel for stress in the heart. Recent evidence has revealed that the redox nature of STAT3 is regulated, and STAT3 is responsive to oxidative stress (ischemia-reperfusion) so as to induce protective genes. At the level of the mitochondrion, STAT3 is important in regulating reactive oxygen species (ROS) formation, metabolism, and mitochondrial integrity. STAT3 may also control calcium release from the ER so as to limit its subsequent uptake by mitochondria and the induction of cell death. Under normal conditions, some STAT3 localizes to intercalated discs of cardiomyocytes and serves to transmit pro-fibrotic gene induction signals in the nucleus with increased blood pressure. Further research is needed to understand how the sentinel role of STAT3 in both endothelial cells and cardiomyocytes is integrated in order to coordinate the response of the heart to both physiological and pathological demands.

Conflicting vascular and metabolic impact of the IL-33/sST2 axis

Interleukin 33 (IL-33), which is expressed by several immune cell types, endothelial and epithelial cells, and fibroblasts, is a cytokine of the IL-1 family that acts both intra- and extracellularly to either enhance or resolve the inflammatory response. Intracellular IL-33 acts in the nucleus as a regulator of transcription. Once released from cells by mechanical stress, inflammatory cytokines, or necrosis, extracellular IL-33 is proteolytically processed to act in an autocrine/paracrine manner as an 'alarmin' on neighbouring or various immune cells expressing the ST2 receptor. Thus, IL-33 may serve an important role in tissue preservation and repair in response to injury; however, the actions of IL-33 are dampened by a soluble form of ST2 (sST2) that acts as a decoy receptor and is produced by endothelial and certain immune cells. Accumulating evidence supports the conclusion that sST2 is a biomarker of vascular health with diagnostic and/or prognostic value in various cardiovascular diseases, including coronary artery disease, myocardial infarction, atherosclerosis, giant-cell arteritis, acute aortic dissection, and ischaemic stroke, as well as obesity and diabetes. Although sST2 levels are positively associated with cardiovascular disease severity, the assumption that IL-33 is always beneficial is naïve. It is increasingly appreciated that the pathophysiological importance of IL-33 is highly dependent on cellular and temporal expression. Although IL-33 is atheroprotective and may prevent obesity and type 2 diabetes by regulating lipid metabolism, IL-33 appears to drive endothelial inflammation. Here, we review the current knowledge of the IL-33/ST2/sST2 signalling network and discuss its pathophysiological and translational implications in cardiovascular diseases.

In Silico Analysis of Differential Gene Expression in Three Common Rat Models of Diastolic Dysfunction

Standard therapies for heart failure with preserved ejection fraction (HFpEF) have been unsuccessful, demonstrating that the contribution of the underlying diastolic dysfunction pathophysiology differs from that of systolic dysfunction in heart failure and currently is far from being understood. Complicating the investigation of HFpEF is the contribution of several comorbidities. Here, we selected three established rat models of diastolic dysfunction defined by three major risk factors associated with HFpEF and researched their commonalities and differences. The top differentially expressed genes in the left ventricle of Dahl salt sensitive (Dahl/SS), spontaneous hypertensive heart failure (SHHF), and diabetes 1 induced HFpEF models were derived from published data in Gene Expression Omnibus and used for a comprehensive interpretation of the underlying pathophysiological context of each model. The diversity of the underlying transcriptomic of the heart of each model is clearly observed by the different panel of top regulated genes: the diabetic model has 20 genes in common with the Dahl/SS and 15 with the SHHF models. Advanced analytics performed in Ingenuity Pathway Analysis (IPA^®) revealed that Dahl/SS heart tissue transcripts triggered by upstream regulators lead to dilated cardiomyopathy, hypertrophy of heart, arrhythmia, and failure of heart. In the heart of SHHF, a total of 26 genes were closely linked to cardiovascular disease including cardiotoxicity, pericarditis, ST-elevated myocardial infarction, and dilated cardiomyopathy. IPA Upstream Regulator analyses revealed that protection of cardiomyocytes is hampered by inhibition of the ERBB2 plasma membrane-bound receptor tyrosine kinases. Cardioprotective markers such as natriuretic peptide A (NPPA), heat shock 27 kDa protein 1 (HSPB1), and angiogenin (ANG) were upregulated in the diabetes 1 induced model; however, the model showed a different underlying mechanism with a majority of the regulated genes involved in metabolic disorders. In conclusion, our findings suggest that multiple mechanisms may contribute to diastolic dysfunction and HFpEF, and thus drug therapies may need to be guided more by phenotypic characteristics of the cardiac remodeling events than by the underlying molecular processes.

Targeting Obesity and Diabetes to Treat Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is a major unmet medical need that is characterized by the presence of multiple cardiovascular and non-cardiovascular comorbidities. Foremost among these comorbidities are obesity and diabetes, which are not only risk factors for the development of HFpEF, but worsen symptoms and outcome. Coronary microvascular inflammation with endothelial dysfunction is a common denominator among HFpEF, obesity, and diabetes that likely explains at least in part the etiology of HFpEF and its synergistic relationship with obesity and diabetes. Thus, pharmacological strategies to supplement nitric oxide and subsequent cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) signaling may have therapeutic promise. Other potential approaches include exercise and lifestyle modifications, as well as targeting endothelial cell mineralocorticoid receptors, non-coding RNAs, sodium glucose transporter 2 inhibitors, and enhancers of natriuretic peptide protective NO-independent cGMP-initiated and alternative signaling, such as LCZ696 and phosphodiesterase-9 inhibitors. Additionally, understanding the role of adipokines in HFpEF may lead to new treatments. Identifying novel drug targets based on the shared underlying microvascular disease process may improve the quality of life and lifespan of those afflicted with both HFpEF and obesity or diabetes, or even prevent its occurrence.

Cardiac STAT3 Deficiency Impairs Contractility and Metabolic Homeostasis in Hypertension

Signal transducer and activator of transcription 3 (STAT3) protects the heart from acute ischemic stress. However, the importance of STAT3 to the heart in chronic stress, such as hypertension, is not known. To study this, we used cardiomyocyte-targeted STAT3 knockout (KO) mice and Angiotensin II (ANG II) infusion by osmotic minipumps. After 4 weeks, ANG II induced similar cardiac hypertrophy in wild type (WT) and cardiac Cre-expressing control (CTRL) mice with no impairment of cardiac function. In contrast, STAT3 KO mice exhibited reduced contractile function but similar hypertrophy to CTRL mice. Ejection fraction and fractional shortening decreased by 22.5 and 27.3%, respectively. Since STAT3 has direct protective effects on mitochondrial function, we examined rates of glucose and oleate oxidation by isolated perfused hearts using a Langendorff system. Hearts of ANG II-treated STAT3 KO and CTRL mice had similar rates of oleate oxidation as saline-infused WT mice. Rates of glucose oxidation were similar between hearts of WT plus saline and CTRL plus ANG II mice; however, glucose oxidation was increased by 66% in hearts of ANG II-treated STAT3 KO mice. The ratio of maximal ATP yield from glucose to fatty acid oxidation was 21.1 ± 3.1 in hearts of ANG II-treated STAT3 KO mice vs. 12.6 ± 2.2 in hearts of ANG II-treated CTRL mice. Lactate production was also elevated in hearts of ANG II-treated STAT3 KO mice by 162% compared to ANG II-treated CTRL mice. Our findings indicate that STAT3 is important for maintaining contractile function and metabolic homeostasis in the hypertensive heart, and STAT3 deficiency promotes a switch toward glucose utilization.

Pivotal Importance of STAT3 in Protecting the Heart from Acute and Chronic Stress: New Advancement and Unresolved Issues

The transcription factor, signal transducer and activator of transcription 3 (STAT3), has been implicated in protecting the heart from acute ischemic injury under both basal conditions and as a crucial component of pre- and post-conditioning protocols. A number of anti-oxidant and antiapoptotic genes are upregulated by STAT3 via canonical means involving phosphorylation on Y705 and S727, although other incompletely defined posttranslational modifications are involved. In addition, STAT3 is now known to be present in cardiac mitochondria and to exert actions that regulate the electron transport chain, reactive oxygen species production, and mitochondrial permeability transition pore opening. These non-canonical actions of STAT3 are enhanced by S727 phosphorylation. The molecular basis for the mitochondrial actions of STAT3 is poorly understood, but STAT3 is known to interact with a critical subunit of complex I and to regulate complex I function. Dysfunctional complex I has been implicated in ischemic injury, heart failure, and the aging process. Evidence also indicates that STAT3 is protective to the heart under chronic stress conditions, including hypertension, pregnancy, and advanced age. Paradoxically, the accumulation of unphosphorylated STAT3 (U-STAT3) in the nucleus has been suggested to drive pathological cardiac hypertrophy and inflammation via non-canonical gene expression, perhaps involving a distinct acetylation profile. U-STAT3 may also regulate chromatin stability. Our understanding of how the non-canonical genomic and mitochondrial actions of STAT3 in the heart are regulated and coordinated with the canonical actions of STAT3 is rudimentary. Here, we present an overview of what is currently known about the pleotropic actions of STAT3 in the heart in order to highlight controversies and unresolved issues.

Left Ventricular Dysfunction and CXCR3 Ligands in Hypertension: From Animal Experiments to a Population-Based Pilot Study

Detecting left ventricular (LV) dysfunction at an early stage is key in addressing the heart failure epidemic. In proteome profiling experiments in mice subjected either to aortic banding or sham, the circulating CXCR3 ligands monokine induced by interferon-γ (MIG) and interferon-γ inducible protein 10 (IP10) were 5 to 40 fold up-regulated at eight weeks. We assessed the diagnostic value of circulating NT-pro BNP and CXCR3 ligands (MIG, IP10, Interferon-inducible T-cell alpha chemo-attractant [I–TAC]) in patients with hypertension (≥140/90 mm Hg) associated with subclinical (n = 19) or symptomatic (n = 16) diastolic LV dysfunction on echocardiography and healthy controls. NT–pro BNP, MIG, IP10, I–TAC all increased (p ≤ 0.014) across the categories of worsening left ventricular dysfunction. In patients with symptomatic disease, MIG, IP10, and I–TAC increased 210% (p = 0.015), 140% (p = 0.007) and 120% (p = 0.035) more than NT-pro BNP. The optimal discrimination limits, obtained by maximizing Youden’s index were 246 pmol/L, 65 pg/mL, 93 pg/mL, and 24 pg/mL, respectively. The odds ratios associated with the four biomarkers were significant (p ≤ 0.010), ranging from 4.00 for IP10 to 9.69 for MIG. With adjustment for NT–pro BNP, the CXCR3 ligands retained significance (p ≤ 0.028). Adding optimized thresholds for the CXCR3 ligands to NT–pro BNP enhanced (p ≤ 0.014) the integrated discrimination improvement and the net reclassification improvement. In conclusion, congruent with the concept that inflammation plays a key role in the pathogenesis of LV dysfunction, MIG, IP10 and I–TAC add diagnostic accuracy over and beyond NT–pro BNP.

Temporal cardiac remodeling post-myocardial infarction: dynamics and prognostic implications in personalized medicine

Despite dramatic improvements in short-term mortality rates following myocardial infarction (MI), long-term survival for MI patients who progress to heart failure remains poor. MI occurs when the left ventricle (LV) is deprived of oxygen for a sufficient period of time to induce irreversible necrosis of the myocardium. The LV response to MI involves significant tissue, cellular, and molecular level modifications, as well as substantial hemodynamic changes that feedback negatively to amplify the response. Inflammation to remove necrotic myocytes and fibroblast activation to form a scar are key wound healing responses that are highly variable across individuals. Few biomarkers of early remodeling stages are currently clinically adopted. The discovery of underlying pathophysiological mechanisms and associated novel biomarkers has the potential of improving prognostic capability and therapeutic monitoring. Combining these biomarkers with other prominent ones could constitute a powerful diagnostic and prognostic tool that directly reflects the pathophysiological remodeling of the LV. Understanding temporal remodeling at the tissue, cellular, and molecular level and its link to a well-defined set of biomarkers at early stages post-MI is a prerequisite for improving personalized care and devising more successful therapeutic interventions. Here we summarize the integral mechanisms that occur during early cardiac remodeling in the post-MI setting and highlight the most prominent biomarkers for assessing disease progression.

Abstract 110: Importance of the C-Terminal Transactivation Domain of STAT3 in Hypertension-Induced Cardiac Hypertrophy

Signal transducer and activator of transcription 3 (STAT3) is known to have protective effects in the heart in acute oxidative stress such as myocardial infarction; however, the role of STAT3 in the heart in response to chronic stress, such as hypertension, is not defined. Here, we assessed the importance of STAT3 on cardiac remodeling post abdominal aortic constriction (AAC) using mice expressing a STAT3 protein lacking the transactivation domain (TAD; aa701-732) selectively in cardiomyocytes (cm-STAT3Δ). Loss of the TAD region impairs both the mitochondrial and transcriptional actions of STAT3. Both WT and cm-STAT3Δ mice developed hypertension to a comparable extent. However, cm-STAT3Δ mice exhibited a significant (p < 0.01) decline in ejection fraction (58.3 ± 4.7 to 24.2 ± 3.6, n=4) and fractional shortening (30.8 ± 3.4 to 11.2 ± 1.7, n=4) over 28 days following AAC, while WT mice exhibited a compensatory response in EF (58.6 ± 3.2 to 59.4 ± 6.0) and FS (30.7 ± 2.1 to 33.0 ± 2.8). Notably, hearts of cm-STAT3Δ exhibited a marked increase in diastolic left ventricular internal diameter (LVIDd), symptomatic of eccentric hypertrophy and dilated cardiomyopathy. In contrast, the pattern of change in LVIDd for WT mice was consistent with concentric remodeling. Banding caused comparable increases in heart to body weight ratios in WT (4.1 ± 0.1 to 6.4 ± 1.0) and cm-STAT3Δ (4.0 ± 0.1 to 7.2 ± 0.6) mice, although on average the increase was larger in cm-STAT3Δ mice. Interestingly, we also found that miR-199a-5p levels were only moderately higher (36%) after AAC in the ventricles of cm-STAT3Δ mice vs. wild type hearts as compared to cardiomyocyte-targeted STAT3 KO mice in which the DNA binding domain of STAT3 is deleted. miR-199a-5p is a known inhibitor of peroxisome proliferator-activated receptor delta (PPARδ) expression and mitochondrial fatty acid oxidation in the heart. These new findings emphasize the distinctive and important role of the C-terminus of STAT3 in the hypertrophic response of the heart to hypertension and the progression to heart failure.

The circular relationship between matrix metalloproteinase-9 and inflammation following myocardial infarction

Matrix metalloproteinase-9 (MMP-9) regulates remodeling of the left ventricle after myocardial infarction (MI) and is tightly linked to the inflammatory response. The inflammatory response serves to recruit leukocytes as part of the wound healing reaction to the MI injury, and infiltrated leukocytes produce cytokines and chemokines that stimulate MMP-9 production and release. In turn, MMP-9 proteolyzes cytokines and chemokines. Although in most cases, MMP-9 cleavage of the cytokine or chemokine substrate serves to increase activity, there are cases where cleavage results in reduced activity. Global MMP-9 deletion in mouse MI models has proven beneficial, suggesting inhibition of some aspects of MMP-9 activity may be valuable for clinical use. At the same time, overexpression of MMP-9 in macrophages has also proven beneficial, indicating that we still do not fully understand the complexity of MMP-9 mechanisms of action. In this review, we summarize the cycle of MMP-9 effects on cytokine production and cleavage to regulate leukocyte functions. Although we use MI as the example process, similar events occur in other inflammatory and wound healing conditions.

Diurnal rhythms of serum and plasma cytokine profiles in healthy elderly individuals assessed using membrane based multiplexed immunoassay

Background

Recent clinical studies suggest that inflammatory mediators have huge potential in individualized therapy and in efficacy screening and can be utilized as biomarkers for a plethora of pathological conditions. The standard approach for detecting and measuring these inflammatory mediators is via blood samples. Nevertheless, there is no scientific report providing solid evidence on the most suitable blood compartment that will give the optimal inflammatory mediator measurement, or regarding the diurnal variation of circulating mediators. In this study, we present the biological variability of circulating cytokines and chemokines from healthy individuals (mean age 59 years) assessed by a novel membrane-based assay.

Methods

Fifteen males and an equal number of females (all above 50 years) with no known inflammatory condition were selected. Through a planar method, named Proteome Profiler™, improved with fluorescence readout into a semi-quantitative multiplex assay, a screening of 36 inflammatory mediators was performed in serum and plasma of morning and afternoon blood withdrawals.

Results

The multiplex analysis revealed that the physiological variability of several circulating inflammatory mediators was relatively small within a cohort of 30 healthy aging subjects. There was no substantial gender effect in the inflammatory mediator profile. On the contrary, most of the cytokine/chemokine values measured in the afternoon collection were found to be higher compared to the morning ones, particularly in plasma.

Conclusions

In this study we provide evidence that circulating cytokine and chemokine levels of healthy individuals are elevated when blood is sampled in the afternoon compared to the morning, as influenced by the circulating cortisol levels. Furthermore, we report significant differences between cytokine/chemokine levels measured in serum and plasma. Our results provide essential information for future studies that will focus on examining circulating inflammatory mediator differences between healthy and diseased individuals.

Myocardial Infarction Superimposed on Aging: MMP-9 Deletion Promotes M2 Macrophage Polarization

In this study, we examined the combined effect of aging and myocardial infarction on left ventricular remodeling, focusing on matrix metalloproteinase (MMP)-9-dependent mechanisms. We enrolled 55 C57BL/6J wild type (WT) and 85 MMP-9 Null (Null) mice of both sexes at 11-36 months of age and evaluated their response at Day 7 post-myocardial infarction. Plasma MMP-9 levels positively linked to age in WT mice (r = .46, p = .001). MMP-9 deletion improved survival (76% for WT vs 88% for Null, p = .021). Post-myocardial infarction, there was a progressive increase in left ventricular dilation with age in WT but not in Null mice. By inflammatory gene array analysis, WT mice showed linear age-dependent increases in three different proinflammatory genes (C3, CCl4, and CX3CL1; all p < .05), whereas Null mice showed increases in three proinflammatory genes (CCL5, CCL9, and CXCL4; all p < .05) and seven anti-inflammatory genes (CCL1, CCL6, CCR1, IL11, IL1r2, IL8rb, and Mif; all p < .05). Compared with WT, macrophages isolated from Null left ventricle infarct demonstrated enhanced expression of anti-inflammatory M2 markers CD163, MRC1, TGF-β1, and YM1 (all p < .05), without affecting proinflammatory M1 markers. In conclusion, MMP-9 deletion stimulated anti-inflammatory polarization of macrophages to attenuate left ventricle dysfunction in the aging post-myocardial infarction.

Improving membrane based multiplex immunoassays for semi-quantitative detection of multiple cytokines in a single sample

Background

Inflammatory mediators can serve as biomarkers for the monitoring of the disease progression or prognosis in many conditions. In the present study we introduce an adaptation of a membrane-based technique in which the level of up to 40 cytokines and chemokines can be determined in both human and rodent blood in a semi-quantitative way. The planar assay was modified using the LI-COR (R) detection system (fluorescence based) rather than chemiluminescence and semi-quantitative outcomes were achieved by normalizing the outcomes using the automated exposure settings of the Odyssey readout device. The results were compared to the gold standard assay, namely ELISA.

Results

The improved planar assay allowed the detection of a considerably higher number of analytes (n = 30 and n = 5 for fluorescent and chemiluminescent detection, respectively). The improved planar method showed high sensitivity up to 17 pg/ml and a linear correlation of the normalized fluorescence intensity with the results from the ELISA (r = 0.91).

Conclusions

The results show that the membrane-based technique is a semi-quantitative assay that correlates satisfactorily to the gold standard when enhanced by the use of fluorescence and subsequent semi-quantitative analysis. This promising technique can be used to investigate inflammatory profiles in multiple conditions, particularly in studies with constraints in sample sizes and/or budget.

Soluble apoptotic factors and adhesion molecules in rhegmatogenous retinal detachment

PURPOSE

To investigate the association between soluble apoptosis and adhesion molecules and the development of proliferative vitreoretinopathy (PVR) after reattachment surgery for rhegmatogenous retinal detachment (RRD).

METHODS

A multiplex immunoassay was used to measure soluble Fas (sFas), sFas ligand (sFasL), soluble intercellular adhesion molecule (sICAM)-1, and soluble vascular cell adhesion molecule (sVCAM)-1 levels in 55 subretinal fluid samples collected during scleral buckling surgery for primary RRD. Seventeen patients who developed a redetachment due to postoperative PVR after reattachment surgery (PVR group) were compared with age-, sex-, and storage-time-matched RRD samples from 38 patients with an uncomplicated postoperative course (RRD group). Ten vitreous samples from patients with macular hole and ten vitreous samples from eye bank eyes served as additional controls.

RESULTS

A 2- to 3-fold increase in levels of sFas, sFasL, sICAM-1, and sVCAM-1 was found in the PVR group compared with those of the RRD group (P < 0.05 for all analytes), as well as a 5- to 20-fold increase in the PVR group compared with those of additional control groups (P < 0.001 for all analytes). Significant associations (P < 0.001) were found between sFas and both sICAM-1 (r = 0.84) and sVCAM-1 (r = 0.93) and between sFasL and both sICAM-1 (r = 0.82) and sVCAM-1 (r = 0.85). In addition, sFas, sFasL, and sVCAM-1 were significantly correlated (P < 0.05) with the extent and duration of retinal detachment.

CONCLUSIONS

These findings indicate that an increased expression of soluble apoptosis and adhesion molecules at the time of primary retinal detachment surgery is associated with the future development of PVR.

Hepatitis C virus (HCV)-driven stimulation of subfamily-restricted natural IgM antibodies in mixed cryoglobulinemia

Hepatitis C virus (HCV) infection has been closely related to mixed cryoglobulinemia (MC). During HCV infection, cryoglobulins derive from the restricted expression of few germline genes as VH1-69, a subfamily highly represented in anti-HCV humoral response. Little is known about the self-reacting IgM component of the cryoprecipitate. In the present study, the IgM/K repertoire of an HCV-infected cryoglobulinemic patient was dissected by phage-display on well-characterized anti-HCV/E2 VH1-69-derived monoclonal IgG1/Kappa Fab fragments cloned from the same patient. All selected IgM clones were shown to react with the anti-HCV/E2 antibodies belonging to VH1-69 subfamily. More than 60% of selected clones showed a bias in VH gene usage, restricted to two VH subfamilies frequently described in autoimmune manifestations (VH3-23; VH3-21). Moreover, all selected clones showed an high similarity (>98.5%) to germline genes evidencing their natural origin. A possible hypothesis is that clones belonging to some subfamilies are naturally prone to react against other VH gene subfamilies, as VH 1-69. An antigen-driven stimulation of these subfamilies, and their overexpression as in HCV infection, could lead to a breaking of humoral homeostatic balance exposing the patients to the risk of developing autoimmune disorders.