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.

Potential Alternative Receptors for SARS-CoV-2-Induced Kidney Damage: TLR-4, KIM-1/TIM-1, and CD147

Kidney damage in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can occur even in patients with no underlying kidney disease. Signs of kidney problems can progress to a state that demands dialysis and hampering recovery. Although not without controversy, emerging evidence implicates direct infectivity of SARS-CoV-2 in the kidney. At the early stage of the pandemic, consideration was mainly on the well-recognized angiotensin-converting enzyme 2 (ACE2) receptor as being the site for viral interaction and subsequent cellular internalization. Despite the abundance of ACE2 receptors in the kidneys, researchers have expanded beyond ACE2 and identified novel viral entry pathways that could be advantageously explored as therapeutic targets. This review presents the potential involvement of toll-like receptor 4 (TLR-4), kidney injury molecule-1/T cell immunoglobulin mucin domain 1 (KIM-1/TIM-1), and cluster of differentiation 147 (CD147) in SARS-CoV-2-associated renal damage. In this context, we address the unresolved issues surrounding SARS-CoV-2 renal infectivity.

Nicotinamide Riboside Supplementation Restores Myocardial Nicotinamide Adenine Dinucleotide Levels, Improves Survival, and Promotes Protective Environment Post Myocardial Infarction

AIMS

Myocardial infarction (MI) is a major cause of death. Nicotinamide adenine dinucleotide (NAD+) is a coenzyme in oxidative phosphorylation and substrate of sirtuins and poly-ADP ribose polymerases, enzymes critical for cardiac remodeling post-MI. Decreased NAD+ is reported in several heart failure models with paradoxically an upregulation of nicotinamide riboside kinase 2, which uses nicotinamide riboside (NR) as substrate in an NAD+ biosynthetic pathway. We hypothesized that stimulating nicotinamide riboside kinase 2 pathway by NR supplementation exerts cardioprotective effects.

METHODS AND RESULTS

MI was induced by LAD ligation in 2-3-month-old male mice. NR was administered daily (1 µmole/g body weight) over 7 days. RT-PCR showed a 60-fold increase in nicotinamide riboside kinase 2 expression 4 days post-MI with a 60% drop in myocardial NAD+ and overall survival of 61%. NR restored NAD+ levels and improved survival to 92%. Assessment of respiration in cardiac fibers revealed mitochondrial dysfunction post-MI, and NR improved complexes II and IV activities and citrate synthase activity, a measure of mitochondrial content. Additionally, NR reduced elevated PARP1 levels and activated a type 2 cytokine milieu in the damaged heart, consistent with reduced early inflammatory and pro-fibrotic response.

CONCLUSION

Our data show that nicotinamide riboside could be useful for MI management.

Cooling Down Inflammation in the Cardiovascular System via the Nicotinic Acetylcholine Receptor

ABSTRACT

Inflammation is a major player in many cardiovascular diseases including hypertension, atherosclerosis, myocardial infarction, and heart failure. In many individuals, these conditions coexist and mutually exacerbate each other's progression. The pathophysiology of these diseases entails the active involvement of both innate and adaptive immune cells. Immune cells that possess the α7 subunit of the nicotinic acetylcholine receptor on their surface have the potential to be targeted through both pharmacological and electrical stimulation of the cholinergic system. The cholinergic system regulates the inflammatory response to various stressors in different organ systems by systematically suppressing spleen-derived monocytes and chemokines and locally improving immune cell function. Research on the cardiovascular system has demonstrated the potential for atheroma plaque stabilization and regression as favorable outcomes. Smaller infarct size and reduced fibrosis have been associated with improved cardiac function and a decrease in adverse cardiac remodeling. Furthermore, enhanced electrical stability of the myocardium can lead to a reduction in the incidence of ventricular tachyarrhythmia. In addition, improving mitochondrial dysfunction and decreasing oxidative stress can result in less myocardial tissue damage caused by reperfusion injury. Restoring baroreflex activity and reduction in renal damage can promote blood pressure regulation and help counteract hypertension. Thus, the present review highlights the potential of nicotinic acetylcholine receptor activation as a natural approach to alleviate the adverse consequences of inflammation in the cardiovascular system.

Assessing the outcomes of prescribing angiotensin converting enzyme inhibitors and angiotensin receptor blockers for COVID-19 patients

Background

Patients with heart failure were affected severely by COVID-19. Most heart failure patients are on guideline directed medical therapy, which includes ACE inhibitors (ACEI) and ARBs. These medications were controversial at the beginning of the pandemic due to their interplay with the receptor that SARS-CoV-2 binds in the lungs. We investigated the effect that ACEI and ARB had on patients with hypertension, coronary artery disease, and heart failure.

Methods

We recruited 176 patients with COVID-19 infection and cardiovascular comorbidities at the American University of Beirut Medical Center in Lebanon. Of these, 110 patients were taking ACEI or ARB and 66 were not. We collected clinical data and looked at inflammatory markers such as CRP and IL-6 and cardiac markers such as troponin T. We also reported the incidence of ARDS, sepsis, and death of each patient, and compared the 2 groups.

Results

We found that patients taking ACEI and ARB had a statistically significant decrease in levels of troponin T, IL-6, and CRP compared to patients not taking these medications (p < 0.05). We found no difference in rates of ARDS, sepsis, or death between the 2 groups.

Conclusion

Inhibition of the renin-angiotensin-aldosterone-system had no effect on the mortality of patients with COVID-19 and on their overall disease progression. However, it may be beneficial not to stop these medications as they decrease inflammation in the body and the levels of troponin, which are related to increased stress on the heart.

Inhibiting B cell activating factor attenuates preeclamptic symptoms in placental ischemic rats

PROBLEM

Preeclampsia (PE), new-onset hypertension during pregnancy, is associated with a pro-inflammatory state with activated T cells, cytolytic natural killer (NK) cells, dysregulated complement proteins, and B cells secreting agonistic autoantibodies to the angiotensin II type-1 receptor (AT1-AA). The reduced uterine perfusion pressure (RUPP) model of placental ischemia recapitulates these features of PE. Blocking CD40L-CD40 communication between T and B cells or B cell depletion with Rituximab prevents hypertension and AT1-AA production in RUPP rats. This suggests that T cell-dependent B cell activation contributes to the hypertension and AT1-AA associated with PE. B2 cells maturing into antibody producing plasma cells are the product of T cell-dependent B cell-interactions and B cell Activating Factor (BAFF) is an integral cytokine in the development of B2 cells specifically. Thus, we hypothesize that BAFF blockade will selectively deplete B2 cells, therefore reducing blood pressure, AT1-AA, activated NK Cells, and complement in the RUPP rat model of PE.

METHOD OF STUDY

Gestational Day (GD) 14 pregnant rats underwent the RUPP procedure, and a subset were treated with 1 mg/kg Anti-BAFF antibodies via jugular catheters. On GD19, blood pressure was measured, B cells and NK cells were measured by flow cytometry, AT1-AA was measured by cardiomyocyte bioassay, and complement activation was measured by ELISA.

RESULTS

Anti-BAFF therapy attenuated hypertension, AT1-AA, NK cell activation, and APRIL levels in RUPP rats without negatively impacting fetal outcomes.

CONCLUSIONS

This study demonstrates that B2 cells contribute to hypertension, AT1-AA, and NK cell activation in response to placental ischemia during pregnancy.

Risk of thromboembolic events in non-hospitalized COVID-19 patients: A systematic review

The risk of thromboembolism in non-hospitalized COVID-19 patients remains uncertain and was assessed in this review to better weigh benefits vs. risks of prophylactic anticoagulation in this population. A search was performed through three databases: Medline, Embase, and Cochrane Library until 2022. Self-controlled case series, case-control and cohort studies were included, and findings summarized narratively. Meta-analyses for risk of thromboembolism including deep vein thrombosis (DVT), pulmonary embolism (PE), and myocardial infarction (MI) between COVID-19 and non-COVID-19 non-hospitalized patients were conducted. Frequency, incidence rate ratio (IRR), and risk ratio (RR) of stroke were used to assess risk in non-hospitalized COVID-19 patients considering the lack of studies to conduct a meta-analysis. Ten studies met inclusion criteria characterized by adult non-hospitalized COVID-19 patients. Risk of bias was relatively low. Risk of DVT (RR: 1.98 with 95% CI: 1.03-3.83) and PE (OR: 6.72 with 95% CI: 4.81-9.39 and RR: 4.44 with 95% CI: 1.98-9.99) increased in non-hospitalized COVID-19 patients compared to controls. Risk of MI (OR: 1.91 with 95% CI: 0.89-4.09) is possibly increased in non-hospitalized COVID-19 patients with moderate certainty when compared to controls. A trend in favor of stroke was documented in the first week following infection. Our meta-analyses support the increase in risk of DVT and PE, and likely increase of MI, in non-hospitalized COVID-19 patients. The risk of stroke appears significant in the first week following infection but drops to insignificance two weeks later. More studies are needed to establish evidence-based recommendations for prophylactic anticoagulation therapy in non-hospitalized COVID-19 patients.

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.

Sex differences in cardiac remodeling post myocardial infarction with acute cigarette smoking

Background

Whether cigarette smoking affects the heart post-myocardial infarction (MI) in a sex-dependent way remains controversial. Using a mouse model, we investigated cardiac remodeling under the influence of acute cigarette smoke (CS) exposure following ischemic injury in both sexes.

Methods

Ten cigarettes were smoked twice daily for 2 weeks followed by MI and then 1 additional week post permanent LAD ligation. Cardiac function, histology, and infarct size were assessed, and inflammatory markers quantified by RT–PCR. Statistical comparisons were performed using an unpaired t test or ANOVA followed by Tukey post hoc test.

Results

We observed that cigarette smoking exacerbated both left and right ventricular remodeling only in males at an early stage of post-MI. Females did not display a significant structural and/or functional alteration within 7 days of cardiac remodeling post-MI upon CS exposure. Worsened right ventricular remodeling in males was independent of pulmonary congestion. CS-exposed males exhibited enhanced increases in left ventricular end systolic and diastolic volumes, as well as reductions in ejection fraction and fractional area changes of left ventricular base. At day 7, infarct size was increased by cigarette smoking in males only, which was accompanied by enhanced collagen deposition in both the infarcted and peri-infarcted areas. Both IL-6 and TNF-α mRNA expression significantly increased in CS-exposed MI male group only at day 7 post-MI suggestive of prolonged inflammation.

Conclusions

These findings indicate that CS exposure worsens the progression of cardiac remodeling post-MI in male sex in a significant manner compared to female sex at least at early stages.

Angiotensin II type 1 receptor agonistic autoantibody blockade improves postpartum hypertension and cardiac mitochondrial function in rat model of preeclampsia

Women with preeclampsia (PE) have a greater risk of developing hypertension, cardiovascular disease (CVD), and renal disease later in life. Angiotensin II type I receptor agonistic autoantibodies (AT1-AAs) are elevated in women with PE during pregnancy and up to 2-year postpartum (PP), and in the reduced uterine perfusion pressure (RUPP) rat model of PE. Blockade of AT1-AA with a specific 7 amino acid peptide binding sequence (‘n7AAc’) improves pathophysiology observed in RUPP rats; however, the long-term effects of AT1-AA inhibition in PP is unknown. Pregnant Sprague Dawley rats were divided into three groups: normal pregnant (NP) (n = 16), RUPP (n = 15), and RUPP + ‘n7AAc’ (n = 16). Gestational day 14, RUPP surgery was performed and ‘n7AAc’ (144 μg/day) administered via osmotic minipump. At 10-week PP, mean arterial pressure (MAP), renal glomerular filtration rate (GFR) and cardiac functions, and cardiac mitochondria function were assessed. MAP was elevated PP in RUPP vs. NP (126 ± 4 vs. 116 ± 3 mmHg, p < 0.05), but was normalized in in RUPP + ‘n7AAc’ (109 ± 3 mmHg) vs. RUPP (p < 0.05). PP heart size was reduced by RUPP + ’n7AAc’ vs. RUPP rats (p < 0.05). Complex IV protein abundance and enzymatic activity, along with glutamate/malate-driven respiration (complexes I, III, and IV), were reduced in the heart of RUPP vs. NP rats which was prevented with ‘n7AAc’. AT1-AA inhibition during pregnancy not only improves blood pressure and pathophysiology of PE in rats during pregnancy, but also long-term changes in blood pressure, cardiac hypertrophy, and cardiac mitochondrial function PP.

Abstract P173: The Impact Of Cigarette Smoking-oral Contraceptive Combination On Cardiac Remodeling In Premenopausal Female Mice

Introduction: Tobacco smoke is a major risk factor for coronary artery diseases (CAD) and chronic tobacco smoking (CS) increase the risk of CAD by 2 to 4 folds. CS effect on cardiac homeostasis has never been evaluated in premenopausal females taking oral contraceptive (OC). This study investigates CS effect on cardiac remodeling in female mice in the presence or absence of Ethinyl Estradiol (EE).

Methods: Blood pressure and echocardiography were recorded for female C57BL/6J mice on EE, EE-CS, vehicle, and vehicle-CS at baseline and after 8-weeks of exposure. Cardiac inflammatory cytokines and oxidative stress markers were evaluated by real time PCR and western blots. Interstitial collagen deposition was assessed by Masson Trichrome staining.

Results: Eight weeks of EE-CS treated mice showed no effect on BP but significant adverse structural and functional cardiac effects, represented by increased systolic (0.981 ± 0.035 N=11 (p<0.0332)) and diastolic (1.450 ± 0.037 N=11 (p<0.0002)) areas when compared to the vehicle and EE groups, along with increased systolic (1.981 ± 0.109 N=11 (p<0.033)) and diastolic ( 3.911 ± 0.159 N=11 (p<0.033)) volumes when compared to all groups. Functional changes were accompanied with a decreased fractional shortening (9.194 ± 1.006 N=11 (p<0.033)) when compared to vehicle and EE groups with no changes in ejection fraction parameter. Moreover EE-CS treatment significantly increased NOX-4 expression (2.297 ± 0.643 N=5 (p<0.033)) when compared to EE treatment alone, along with an increased pro-inflammatory profile including IL-1β (0.750 ±0.171N=5 (p<0.033)) and IL-4 (4.110 ± 0.623 N= 5 (p<0.002)) when compared to all groups, and IL-6 (3.045±0.910 N=5 (p<0.002)) and IL-13 (2.686 ± 0.648 N=5 (p<0.033)) when compared to vehicle-CS group. Morphologically, EE-CS exhibited a significant increase in interstitial fibrosis (1.186± 0.020 N=5, 3.2285 ± 0.683 N=5, (p<0.033)) when compared to the vehicle-CS group.

Conclusion: This study provides clear evidence that CS-exposed premenopausal female mice on OC regimen exhibited significant adverse cardiac events that could be classified under cardiac dysfunction with preserved ejection fraction. Additional experiments are warranted to further elaborate on these findings.

Abstract 15: The Cardio-renal Effects Of Il-33 Treatment In Myocardial Infarction-induced Kidney Damage

Introduction: Interleukin (IL)-33 is a nuclear alarmin released upon tissue damage and initiating a signaling cascade by binding to its cell membrane receptor ST2. Accumulating evidence shows that the IL-33/ST2 axis mediates both inflammatory and repair responses in different models of kidney diseases, suggesting a Janus-like effect that varies within disease context and progression. This study aimed to investigate the effect of IL-33 administration on acute kidney damage at 4 and 7 days post-MI in mice.

Methods: MI was induced by ligating the left anterior descending coronary artery, followed by IL-33 (1μg/day)/vehicle (PBS) treatment for 4 and 7 consecutive days. Cardiac systolic function was assessed, and kidneys were subjected to histological and molecular analysis.

Results: IL-33 had no significant effect on cardiac hemodynamic parameters at 4 days but significantly decreased the left ventricular ejection fraction (20 ± 1 vs 9.8 ± 2, P<0.01) at 7 days post-MI. In the kidneys, reduced glomerular retraction (0.57 ± 0.09 vs 0.24 ± 0.06, P < 0.05) was observed at day 4 post-MI only, along with a decrease in the protein expression of αSMA (2.89 ± 0.33 vs 0.43 ± 0.13, P < 0.001) and collagen 3 (1.96 ± 0.78 vs 0.34 ± 0.14, P < 0.05). Conversely, increased protein levels of αSMA (0.86 ± 0.42 vs 21.5 ± 2.53, P < 0.0001) and collagen 3 (0.33 ± 0.08 vs 1.71 ± 0.22, P<0.01) were observed at day 7 post-MI. Total renal fibrosis increased to levels comparable to the MI vehicle group at day 4 and 7 post-MI. The mRNA expression of the apoptotic BAX/BCL2 ratio (1.05 ± 0.09 vs 0.36 ± 0.23, P < 0.05) decreased only at day 4 post-MI, whereas an increase in the mRNA levels of the DNA repair enzyme PARP-1 (1.37 ± 0.06 vs 2.05 ± 0.4, P<0.05) was observed at day 7 post-MI. A marked increase in the mRNA expression of Sirtuin 3 (1.87 ± 0.57 vs 11.72 ± 4.24, P < 0.05) and in total renal NAD levels (386.75 ± 40.52 vs 706.36 ± 66.09, P < 0.05) was observed at day 4 post-MI.

Conclusion: Collectively, our findings suggest that although IL-33 treatment improves renal homeostasis 4 days post-MI, this protection is offset by day 7 post-MI through enhanced renal morphological and molecular alterations. The observed renal deterioration between day 4 and day 7 post-MI correlate with aggravated cardiac dysfunction.

Interferon γ neutralization reduces blood pressure, uterine artery resistance index, and placental oxidative stress in placental ischemic rats

Preeclampsia (PE) is characterized by maternal hypertension, intrauterine growth restriction, and increased cytolytic natural killer cells (cNKs), which secrete interferon γ (IFNγ). However, the precise role of IFNγ in contributing to PE pathophysiology remains unclear. Using the reduced uterine perfusion pressure (RUPP) rat model of placental ischemia, we tested the hypothesis that neutralization of IFNγ in RUPPs will decrease placental reactive oxygen species (ROS) and improve vascular function resulting in decreased MAP and improved fetal growth. On gestation day (GD) 14, the RUPP procedure was performed and on GDs 15 and 18, a subset of normal pregnant rats (NP) and RUPP rats were injected with 10 μg/kg of an anti-rat IFNγ monoclonal antibody. On GD 18, uterine artery resistance index (UARI) was measured via Doppler ultrasound and on GD 19, mean arterial pressure (MAP) was measured, animals were euthanized, and blood and tissues were collected for analysis. Increased MAP was observed in RUPP rats compared with NP and was reduced in RUPP + anti-IFNγ. Placental ROS was also increased in RUPP rats compared with NP rats and was normalized in RUPP + anti-IFNγ. Fetal and placental weights were reduced in RUPP rats, but were not improved following anti-IFNγ treatment. However, UARI was elevated in RUPP compared with NP rats and was reduced in RUPP + anti-IFNγ. In conclusion, we observed that IFNγ neutralization reduced MAP, UARI, and placental ROS in RUPP recipients. These data suggest that IFNγ is a potential mechanism by which cNKs contribute to PE pathophysiology and may represent a therapeutic target to improve maternal outcomes in PE.

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.

Recent Insights Into the Protective Mechanisms of Paeoniflorin in Neurological, Cardiovascular, and Renal Diseases

ABSTRACT

The monoterpene glycoside paeoniflorin (PF) is the principal active constituent of the traditional Chinese herbal medicines, Radix Paeoniae Alba and Radix Paeoniae Rubra, which have been used for millennia to treat cardiovascular diseases (eg, hypertension, bleeding, and atherosclerosis) and neurological ailments (eg, headaches, vertigo, dementia, and pain). Recent evidence has revealed that PF exerts inhibitory effects on inflammation, fibrosis, and apoptosis by targeting several intracellular signaling cascades. In this review, we address the current knowledge about the pharmacokinetic properties of PF and its molecular mechanisms of action. We also present results from recent preclinical studies supporting the utility of PF for the treatment of pain, cerebral ischemic injury, and neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. Moreover, new evidence suggests a general protective role of PF in heart attack, diabetic kidney, and atherosclerosis. Mechanistically, PF exerts multiple anti-inflammatory actions by targeting toll-like receptor-mediated signaling in both parenchymal and immune cells (in particular, macrophages and dendritic cells). A better understanding of the molecular actions of PF may lead to the expansion of its therapeutic uses.

The Role of Mitochondrial Dysfunction in Preeclampsia: Causative Factor or Collateral Damage?

Preeclampsia, new onset hypertension in pregnancy, affects ~5%-10% of the world's population. Preeclampsia is the leading cause of morbidity and mortality for both the mother and fetus. As of today, there is no cure for this disease except for delivery of the fetal-placental unit. The exact causation and onset of the disease are unknown. However, recent studies have shown a strong correlation between mitochondrial dysfunction and preeclampsia. Circulating mitochondrial DNA, elevated reactive oxygen species, angiotensin II type 1 receptor agonistic autoantibodies (AT1-AA), activated natural killer cells, and upregulated inflammatory responses all contribute to mitochondrial dysfunction and the pathophysiology of preeclampsia. This review summarizes the current literature of both experimental and clinical observations that support the hypothesis that mitochondrial dysfunction contributes to the pathophysiology of preeclampsia and may be a precursor to the disease onset. This review will also address the use of therapies to improve mitochondrial dysfunction in preeclampsia.

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.

Novel Mechanistic Insights and Potential Therapeutic Impact of TRPC6 in Neurovascular Coupling and Ischemic Stroke

Ischemic stroke is one of the most disabling diseases and a leading cause of death globally. Despite advances in medical care, the global burden of stroke continues to grow, as no effective treatments to limit or reverse ischemic injury to the brain are available. However, recent preclinical findings have revealed the potential role of transient receptor potential cation 6 (TRPC6) channels as endogenous protectors of neuronal tissue. Activating TRPC6 in various cerebral ischemia models has been found to prevent neuronal death, whereas blocking TRPC6 enhances sensitivity to ischemia. Evidence has shown that Ca2+ influx through TRPC6 activates the cAMP (adenosine 3',5'-cyclic monophosphate) response element-binding protein (CREB), an important transcription factor linked to neuronal survival. Additionally, TRPC6 activation may counter excitotoxic damage resulting from glutamate release by attenuating the activity of N-methyl-d-aspartate (NMDA) receptors of neurons by posttranslational means. Unresolved though, are the roles of TRPC6 channels in non-neuronal cells, such as astrocytes and endothelial cells. Moreover, TRPC6 channels may have detrimental effects on the blood-brain barrier, although their exact role in neurovascular coupling requires further investigation. This review discusses evidence-based cell-specific aspects of TRPC6 in the brain to assess the potential targets for ischemic stroke management.

Gender-biased kidney damage in mice following exposure to tobacco cigarette smoke: More protection in premenopausal females

Multiple clinical studies documented renal damage in chronic cigarette smokers (CS) irrespective of their age and gender. Premenopausal female smokers are known to exert a certain cardiovascular and renal protection with undefined mechanisms. Given the multiple demographic variables within clinical studies, this experimental study was designed to be the first to assess whether gender‐biased CS‐induced kidney damage truly exists between premenopausal female and age‐matched C57Bl6J male mice when compared to their relative control groups. Following 6 weeks of CS exposure, cardiac function, inflammatory marker production, fibrosis formation, total and glomerular ROS levels, and glomerulotubular homeostasis were assessed in both genders. Although both CS‐exposed male and female mice exhibited comparable ROS fold change relative to their respective control groups, CS‐exposed male mice showed a more pronounced fibrotic deposition, inflammation, and glomerulotubular damage profile. However, the protection observed in CS‐exposed female group was not absolute. CS‐exposed female mice exhibited a significant increase in fibrosis, ROS production, and glomerulotubular alteration but with a pronounced anti‐inflammatory profile when compared to their relative control groups. Although both CS‐exposed genders presented with altered glomerulotubular homeostasis, the alteration phenotype between genders was different. CS‐exposed males showed a significant decrease in Bowman's space along with reduced tubular diameter consistent with an endocrinization pattern of chronic tubular atrophy, suggestive of an advanced stage of glomerulotubular damage. CS‐exposed female group, on the other hand, displayed glomerular hypertrophy with a mild tubular dilatation profile suggestive of an early stage of glomerulotubular damage that generally precedes collapse. In conclusion, both genders are prone to CS‐induced kidney damage with pronounced female protection due to a milder damage slope.

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.

Angiotensin II type 1 receptor autoantibody blockade improves cerebral blood flow autoregulation and hypertension in a preclinical model of preeclampsia

Introduction:Women with preeclampsia (PE) and reduced uterine perfusion pressure (RUPP) pre-clinical rat model of PE have elevated angiotensin II type 1 receptor agonistic autoantibodies (AT1-AA) and cerebrovascular dysfunction. Methods:Sprague Dawley rats had RUPP surgery with/without AT1-AA inhibitor ('n7AAc'144 μg/day) osmotic minipumps. Mean arterial pressure (MAP), CBF autoregulation, blood brain barrier (BBB) permeability, cerebral edema, oxidative stress, and eNOS were assessed. Results:'n7AAc' improved MAP, restored CBF autoregulation, prevented cerebral edema, elevated oxidative stress, and increased phosphorylated eNOS protein in RUPP rats. Conclusion:Inhibiting the AT1-AA in placental ischemic rats prevents hypertension, cerebrovascular dysfunction, and improves cerebral metabolic function.

Science unites a troubled world: Lessons from the pandemic

European Journal of Pharmacology has published a special issue entitled Therapeutic targets and pharmacological treatment of COVID-19 that contains more than 30 manuscripts. Scientists from around the world contributed both review articles and original manuscripts that are remarkable in their diversity. Each contribution offers a unique perspective on the current approaches of the discipline called pharmacology. Yet the contributions share an enthusiasm to put forward a fresh viewpoint and make a positive difference by the exchange of ideas during the troubled times of this pandemic. What other enterprise but science can unite so many diverse cultures and nationalities in global uncertainty and discord, and mobilize an effective response against a common enemy. The efforts of science are in stark contrast to those of populism that has introduced division and a self-serving attitude that are not simply ill-matched to tackle the pandemic, but foster its spread and severity. We trust that the readers of European Journal of Pharmacology will discover new ideas and concepts in our special COVID-19 series as members of the scientific community and shared world.

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.

A Mutation in γ-Adducin Impairs Autoregulation of Renal Blood Flow and Promotes the Development of Kidney Disease

BACKGROUND

The genes and mechanisms involved in the association between diabetes or hypertension and CKD risk are unclear. Previous studies have implicated a role for γ-adducin (ADD3), a cytoskeletal protein encoded by Add3.

METHODS

We investigated renal vascular function in vitro and in vivo and the susceptibility to CKD in rats with wild-type or mutated Add3 and in genetically modified rats with overexpression or knockout of ADD3. We also studied glomeruli and primary renal vascular smooth muscle cells isolated from these rats.

RESULTS

This study identified a K572Q mutation in ADD3 in fawn-hooded hypertensive (FHH) rats-a mutation previously reported in Milan normotensive (MNS) rats that also develop kidney disease. Using molecular dynamic simulations, we found that this mutation destabilizes a critical ADD3-ACTIN binding site. A reduction of ADD3 expression in membrane fractions prepared from the kidney and renal vascular smooth muscle cells of FHH rats was associated with the disruption of the F-actin cytoskeleton. Compared with renal vascular smooth muscle cells from Add3 transgenic rats, those from FHH rats had elevated membrane expression of BKα and BK channel current. FHH and Add3 knockout rats exhibited impairments in the myogenic response of afferent arterioles and in renal blood flow autoregulation, which were rescued in Add3 transgenic rats. We confirmed these findings in a genetic complementation study that involved crossing FHH and MNS rats that share the ADD3 mutation. Add3 transgenic rats showed attenuation of proteinuria, glomerular injury, and kidney fibrosis with aging and mineralocorticoid-induced hypertension.

CONCLUSIONS

This is the first report that a mutation in ADD3 that alters ACTIN binding causes renal vascular dysfunction and promotes the susceptibility to kidney disease.

An Update on the Multifaceted Roles of STAT3 in the Heart

Signal transducer and activator of transcription 3 (STAT3) is a signaling molecule and transcription factor that plays important protective roles in the heart. The protection mediated by STAT3 is attributed to its genomic actions as a transcription factor and other non-genomic roles targeting mitochondrial function and autophagy. As a transcription factor, STAT3 upregulates genes that are anti-oxidative, anti-apoptotic, and pro-angiogenic, but suppresses anti-inflammatory and anti-fibrotic genes. Its suppressive effects on gene expression are achieved through competing with other transcription factors or cofactors. STAT3 is also linked to the modification of mRNA expression profiles in cardiac cells by inhibiting or inducing miRNA. In addition to these genomic roles, STAT3 is suggested to function protectively in mitochondria, where it regulates ROS production, in part by regulating the activities of the electron transport chain complexes, although our recent evidence calls this role into question. Nonetheless, STAT3 is a key player known to be activated in the cardioprotective ischemic conditioning protocols. Through these varied roles, STAT3 participates in various mechanisms that contribute to cardioprotection against different heart pathologies, including myocardial infarction, hypertrophy, diabetic cardiomyopathy, and peripartum cardiomyopathy. Understanding how STAT3 is involved in the protective mechanisms against these different cardiac pathologies could lead to novel therapeutic strategies to treat them.

Abstract P3016: High Glucose Induced Diabetic Dementia is Mediated by Mitochondria Dysfunction

Diabetes is an important risk factor for dementia. We previously reported that cognitive dysfunction is associated with impaired cerebral vascular function in our diabetic rat model. Hyperglycemia contributes to endothelial dysfunction by increasing the production of reactive oxygen species (ROS). However, the role of changes in mitochondrial dynamics in altering autoregulation of cerebral blood flow and the loss of cognitive function in diabetes is unknown. The present study examined the myogenic response of middle cerebral arteries (MCAs), as well as mitochondrial function and fission in primary vascular smooth muscle cells (VSMCs) maintained in normal glucose (NG) or high glucose (HG). ROS production assessed by DHE staining was significantly increased in freshly isolated MCAs of diabetic rats (55.77 ± 11.27 arbitrary unit (a.u.), n=4) vs. Sprague Dawley (SD, 15.46 ± 1.92 a.u. n=4) rats. In addition, HG-treated primary VSMCs from SD rats exhibited more mitochondrial ROS than controls, as detected by MitoSOX. The myogenic response of MCAs was impaired in 3-month old diabetic rats compared to age-matched controls. Treatment with superoxide dismutase (150 U/mL) restored the myogenic response. Mitochondrial respiration was decreased in HG-treated (91.1 ± 7.6 pmol/min/mg/ml, n=6) vs. NG-treated (153.2 ± 6.3 pmol/min/mg/ml, n=9) VSMCs as measured by a Seahorse XF e 24 analyzer. Treatment with HG also caused mitochondrial depolarization as assessed by staining with JC-1. The length of mitochondria in high glucose-treated VSMCs was significantly less than in control VSMCs (HG: 5.66 ± 0.14 μm vs. Control: 11.70 ± 0.23 μm, n=3, 100) as seen by Tomm20 immunostaining. In addition, levels of OPA1 were significantly lower and MFF levels were higher in HG-treated cells compared to controls, indicating an increase in mitochondrial fission and a decrease in fusion in the HG-treated VSMCs. This was associated with decreased levels of p-AMPK in HG-treated vs. control VSMCs. These results demonstrate that the impaired myogenic response in cerebral arteries in diabetes is associated with impaired mitochondrial dysfunction and elevated production of ROS via the p-AMPK/MFF signaling pathway, which may contribute to the loss of cognitive function in diabetes.

Abstract P1103: Angiotensin II Type I Receptor Agonistic Autoantibody Blockade Improves Hypertension and Immune Activation in Postpartum Preeclamptic Rats

Women with preeclampsia (PE) have a risk of developing cardiovascular diseases (CVD) later in life. The angiotensin II type I receptor agonistic autoantibodies (AT1-AAs) are elevated in women with PE, PE women 2 years post-partum (PP), and the reduced uterine perfusion pressure (RUPP) rat model of PE. Blockade of the AT1-AA by using a specific binding seven amino acid peptide sequence (7AA) improves the pathology of PE in RUPP rats. The long-term effects of AT1-AA inhibition on blood pressure, NK cell activation, heart mitochondria (mt) proteins, and CVD in the RUPP model PP is unknown. Therefore, we hypothesized that PP RUPP rats have elevated blood pressure, NK cell activation, and changes in heart mt proteins, which will be prevented in RUPP rats administered the 7AA during pregnancy.

Methods: Pregnant Sprague Dawley rats were divided into groups; normal pregnant (NP) (n=7), RUPP (n=10), and RUPP+7AA (n=9). Gestational day 14, RUPP surgery was performed and 7AA (2 μg/ml) administered via minipump.

Results: At 8 and 10 weeks (wks) PP, blood pressure (MAP), blood, and hearts were collected. NK cells were quantified by flow cytometry. At 8 wks PP, MAP was elevated in RUPP vs. NP (130±2 vs. 123±4 mmHg, ns), and RUPP+7AA (124±4 mmHg) treatment prevented this increase. At 10 wks, MAP was elevated in RUPP vs NP (133±5 vs. 120±5 mmHg, p=0.08), with a significant decrease in MAP in RUPP+7AA (107±6 mmHg) vs. RUPP (p<0.05). Total circulating NK cells were increased in RUPP vs NP (45±9. vs. 29± 8% gated cells, ns), which was prevented in RUPP+7AA (19±16 % gated cells) at 8 wks PP. Hearts were enlarged with RUPP vs NP (0.41±0.04 vs. 0.36±0.02g/100gBW, ns), which was normalized in RUPP+7AA (0.34±0.02g/100gBW). Previous studies show that during pregnancy complex IV is significantly lower along with a decrease mt function in RUPP vs NP. Complex IV mt proteins in the heart were elevated in RUPP+7AA vs. RUPP (5.5±1.7 vs. 3.0±0.2 AU, ns).

Conclusion: In summary, PP PE rats have an increase in MAP, NK cells, and larger hearts. AT1-AA inhibition restores complex IV mt levels and improves HTN, immune activation, and cardiac hypertrophy PP. This study highlights the importance of AT1-AA inhibition during PE to prevent CVD later in life. Supported: AHA18CDA34110264

Abstract P160: Dual-Specificity Protein Phosphatase 5 Regulates Renal Vessel Myogenic Response via Direct Modulating Extracellular Signal-Related Kinase and Protein Kinase C

Dual-specificity protein phosphatase 5 (DUSP5) is a serine-threonine phosphatase that regulates intracellular signal transduction by dephosphorylating extracellular signal-related kinase (ERK1/2) and protein kinase C (PKC). We previously reported that knockout (KO) of Dusp5 enhanced the myogenic response and autoregulation of cerebral and renal circulation in association with increased levels of phosphorylated ERK1/2 (p-ERK1/2) and phosphorylated protein kinase C (p-PKC) in the vessels. However, the influence of increased levels of p-ERK1/2 and p-PKC on vascular function is unknown. This study investigated whether Dusp5 regulates myogenic reactivity of freshly isolated middle cerebral arteries (MCA, ~140 um), cerebral penetrating arteries (PA, ~15 um), renal arcuate arterioles (AA, ~ 50 um), and interlobular arterioles (IA, ~25 um) of Dusp5 KO and WT rats via inhibition of ERK1/2 and PKC. The myogenic reactivity of both cerebral and renal vasculature was compared at different perfusion pressure. The inner diameters of IA and AA decreased to 87.24 ± 0.76 % and 92.81 ± 2.90 %, respectively, in Dusp5 KO rats (n=4), but only to 99.70 ± 2.76 % and 98.85 ± 2.79 %, respectively, in WT rats (n=4) when perfusion pressure was increased from 60 to 180 mmHg. Similar results were found in MCA and PA. Inhibition of ERK1/2 with FR 180204 (1 uM) or PKC with BIM III (300 nM) diminished myogenic reactivity to a greater extent in cerebral and renal vessels of Dusp5 KO versus WT rats. These results indicate that downregulation of DUSP5 expression increases the myogenic reactivity of both cerebral and renal arteries (both large and small vessels) by increasing p-ERK1/2 and p-PKC levels. Targeting Dusp5 may offer a novel approach for preventing hypertension-induced end-organ damage.

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.