Exercise preconditioning prevents MCT-induced right ventricle remodeling through the regulation of TNF superfamily cytokines

Autonomic Dysregulation in Pulmonary Hypertension: Role of Physical Exercise

Pulmonary hypertension (PH) is a rare and severe condition characterized by increased pressure in the pulmonary circulation, often resulting in right ventricular failure and death. The autonomic nervous system (ANS) plays a crucial role in the cardiovascular and pulmonary controls. Dysfunction of ANS has been implicated in the pathogenesis of cardiopulmonary diseases. Conversely, dysfunctions in ANS can arise from these diseases, impacting cardiac and pulmonary autonomic functions and contributing to disease progression. The complex interaction between ANS dysfunction and PH plays a crucial role in the disease progression, making it essential to explore interventions that modulate ANS, such as physical exercise, to improve the treatment and prognosis of patients with PH. This review addresses autonomic dysfunctions found in PH and their implications for the cardiopulmonary system. Furthermore, we discuss how physical exercise, a significant modulator of ANS, may contribute to the prognosis of PH. Drawing from evidence of aerobic and resistance exercise training in patients and experimental models of PH, potential cardiovascular benefits of exercise are presented. Finally, we highlight emerging therapeutic targets and perspectives to better cope with the complex condition. A comprehensive understanding of the interaction between ANS and PH, coupled with targeted physical exercise interventions, may pave the way for innovative therapeutic strategies and significantly improve the treatment and prognosis of vulnerable patients.

Combined physical training protects the left ventricle from structural and functional damages in experimental pulmonary arterial hypertension

BACKGROUND

Under the adverse remodeling of the right ventricle and interventricular septum in pulmonary arterial hypertension (PAH) the left ventricle (LV) dynamics is impaired. Despite the benefits of combined aerobic and resistance physical trainings to individuals with PAH, its impact on the LV is not fully understood.

OBJECTIVE

To test whether moderate-intensity combined physical training performed during the development of PAH induced by MCT in rats is beneficial to the LV's structure and function.

METHODS

Male Wistar rats were divided into two groups: Sedentary Hypertensive Survival (SHS, n = 7); and Exercise Hypertensive Survival (EHS, n = 7) to test survival. To investigate the effects of combined physical training, another group of rats were divided into three groups: Sedentary Control (SC, n = 7); Sedentary Hypertensive (SH, n = 7); and Exercise Hypertensive (EH, n = 7). PAH was induced through an intraperitoneal injection of MCT (60 mg/kg). Echocardiographic evaluations were conducted on the 22nd day after MCT administration. Animals in the EHS and EH groups participated in a combined physical training program, alternating aerobic (treadmill running: 50 min, 60% maximum running speed) and resistance (ladder climbing: 15 climbs with 1 min interval, 60% maximum carrying load) exercises, one session/day, 5 days/week for approximately 4 weeks.

RESULTS

The physical training increased survival and tolerance to aerobic (i.e., maximum running speed) and resistance (i.e., maximum carrying load) exertions and prevented reductions in ejection fraction and fractional shortening. In addition, the physical training mitigated oxidative stress (i.e., CAT, SOD and MDA) and inhibited adverse LV remodeling (i.e., Collagen, extracellular matrix, and cell dimensions). Moreover, the physical training preserved the amplitude and velocity of contraction and hindered the reductions in the amplitude and velocity of the intracellular Ca2+ transient in LV single myocytes.

CONCLUSION

Moderate-intensity combined physical training performed during the development of MCT-induced PAH in rats protects their LV from damages to its structure and function and hence increases their tolerance to physical exertion and prolongs their survival.

Training programs in preclinical studies. The example of pulmonary hypertension. Systematic review and meta-analysis

Background

Exercise and cardiopulmonary exercise testing are essential in the evaluation of physiological, biochemical, and molecular responses in the experimental studies on chronic diseases such as diabetes, heart failure and hypertension. The exercise tolerance and seem to be a valuable contribution to the experiments that are performed in animal models of pulmonary hypertension (PH), as well. The current survey uses detailed quantitative analyses to assess the advantages of exercise training programs performed in preclinical studies based on outcomes such as exercise capacity, cardiopulmonary hemodynamics, and mortality.

Methods

Articles were identified through search engines in the online electronic databases Pubmed/Medline, Web of Science following the PRISMA Protocol. Studies conducted between 1991 and 2022 without language restrictions were included in this study. Heterogeneity was assessed using the Cochrane Q-test and I2 test statistics. Subgroup analysis was employed with evidence of heterogeneity. Quality assessment was carried out using SYRCLE’s risk of bias tool for animal studies. Publication bias across studies was determined using the funnel plot and Egger’s regression test statistic.

Results

The available protocols typically included treadmill running, swimming, and voluntary wheel running with a different series of intensities, times and durations; these were also used in studies examining the efficacy of chronic training programs. In 66 interventions, PH induction reduced exercise endurance by half compared to healthy subjects, while exposure to tested medical agents normalized exercise capacity. The other 58 interventions demonstrated the advantages of various exercise training programs for PH. Induction of PH reduced exercise endurance by half compared to healthy subjects (R = 0.52; 0.48 − 0.55 95%CI; P<0.0001; I2 = 98.9%), while the exposure to tested medical agents normalized exercise capacity (R = 1.75; 1.61 − 1.91 95%CI; P<0.0001; I2 = 97.8%).

Conclusion

Despite a wide spectrum of study protocols to measure exercise endurance in animals with PH, there is a significant correlation between worsening of exercise-related parameters and PH development, manifested by alterations in haemodynamic and remodeling parameters. Familiarization with exercise, training program schedule, method used for PH induction, or detailed training parameters such as slope, exercise intensity or individualization, can influence the final outcome. This in turn can impact on the diversity and reproducibility of results being obtained in particular experimental studies.

O Treinamento Físico Resistido Atenua as Disfunções Ventriculares Esquerdas em Modelo de Hipertensão Arterial Pulmonar

Fundamento

A hipertrofia e a dilatação do ventrículo direito observadas na hipertensão arterial pulmonar (HAP) prejudicam a dinâmica do ventrículo esquerdo (VE) achatando o septo interventricular.

Objetivo

Investigar se o treinamento físico resistido (TFR) de intensidade baixa a moderada é benéfico para funções contráteis do VE e de cardiomiócitos em ratos durante o desenvolvimento de HAP induzida por monocrotalina (MCT).

Métodos

Foram usados ratos Wistar machos (Peso corporal: ~ 200 g). Para avaliar o tempo até o possível surgimento de insuficiência cardíaca (ou seja, ponto de desfecho), os ratos foram divididos em dois grupos, hipertensão com sedentarismo até a insuficiência (HSI, n=6) e hipertensão com treinamento até a insuficiência (HTI, n=6). Para testar os efeitos do TFR, os ratos foram divididos entre grupos de controle sedentários (CS, n=7), hipertensão com sedentarismo (HS, n=7) e hipertensão com treinamento (HT, n=7). A HAP foi induzida por duas injeções de MCT (20 mg/kg, com um intervalo de 7 dias). Os grupos com treinamento foram submetidos a um protocolo de TFR (subir escadas; 55-65% da máxima carga carregada), 5 dias por semana. A significância estatística foi definida em p <0,05.

Resultados

O TFR prolongou o ponto de desfecho (~25%), melhorou a tolerância ao esforço físico (~55%) e atenuou as disfunções de contratilidade de VE e de cardiomiócitos promovidas pela MCT preservando a fração de ejeção e o encurtamento fracional, a amplitude do encurtamento, e as velocidades de contração e relaxamento nos cardiomiócitos. O TFR também preveniu os aumentos de fibrose e colágeno tipo I no ventrículo esquerdo causados pela MCT, além de manter as dimensões de miócitos e colágeno tipo III reduzidas por MCT.

Conclusão

O TFR de intensidade baixa a moderada é benéfico para funções contráteis de VE e cardiomiócitos em ratos durante o desenvolvimento de HAP induzida por MCT.

Cardioprotective Effects of Physical Activity: Focus on Ischemia and Reperfusion

This review aimed to revisit the old and introduce some of the new various cardioprotective effects of physical exercise, focusing on ischemia-reperfusion injury. A wealth of data shows that regular physical exercise is necessary to prevent cardiovascular diseases. In the last few years, a number of new training regimes, usually modified variations of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) protocols, have been rising in popularity among people of all ages. Since exercising is not limited to only healthy people, our study emphasized the benefits of HIIT and MICT in preventing or mitigating cardiac ischemia-reperfusion injury. Different kinds of research are being performed, studying the various positive and side effects of these training regimes, all in hopes of finding the most optimal ones. So far, all of them have shown that exercising to any extent, even for a short period of time, is beneficial in one way or another, and outweighs the possible risks it might have. We also revisited some of the known molecular mechanisms responsible for many of the effects of physical exercise and introduced some new findings related to them. Lastly, we summarized and compared the benefits of different HIIT and MICT protocols to narrow down the search for the most efficient training method.

The Effects of Exercise on Aging-Induced Exaggerated Cytokine Responses: An Interdisciplinary Discussion

Aging is generally known to be associated with dynamic biological changes, physiological dysfunction, and environmental and psychological decline. Several studies have suggested that aging is associated with increased inflammatory cytokines, causing several diseases. However, the effect of exercise on aging has been less delineated, and the relationships between cytokine activation, aging, and exercise also need further study. Here, we discuss some ideas about the effect of exercise on aging-induced exaggerated cytokine responses and discuss the possible roles of the aging-induced exaggerated cytokine response following exercise. Evidence from these findings suggests that exercise is a beneficially applicable model to use in studies on the mechanisms underlying the age-associated gradated cytokine response, and these results may provide guidelines for health professionals with diverse backgrounds.

Preventive training does not interfere with mRNA-encoding myosin and collagen expression during pulmonary arterial hypertension

To gain insight on the impact of preventive exercise during pulmonary arterial hypertension (PAH), we evaluated the gene expression of myosins and gene-encoding proteins associated with the extracellular matrix remodeling of right hypertrophied ventricles. We used 32 male Wistar rats, separated in four groups: Sedentary Control (S, n = 8); Control with Training (T, n = 8); Sedentary with Pulmonary Arterial Hypertension (SPAH, n = 8); and Pulmonary Arterial Hypertension with Training (TPAH, n = 8). All rats underwent a two-week adaptation period; T and TPAH group rats then proceeded to an eight-week training period on a treadmill. At the beginning of the 11th week, S and T groups received an intraperitoneal injection of saline, and SPAH and TPAH groups received an injection of monocrotaline (60 mg/kg). Rats in the T and TPAH groups then continued with the training protocol until the 13th week. We assessed exercise capacity, echocardiography analysis, Fulton's index, cross-sectional areas of cardiomyocytes, collagen content and types, and fractal dimension (FD). Transcript abundance of myosins and extracellular matrix genes were estimated through reverse transcription-quantitative PCR (RT-qPCR). When compared to the SPAH group, the TPAH group showed increases in functional capacity and pulmonary artery acceleration time/pulmonary ejection time ratio and decreases in Fulton's index and cross-sectional areas of myocyte cells. However, preventive exercise did not induce alterations in col1a1 and myh7 gene expression. Our findings demonstrate that preventive exercise improved functional capacity, reduced cardiac hypertrophy, and attenuated PH development without interfering in mRNA-encoding myosin and collagen expression during PAH.

Inflammatory Mechanisms in the Pathogenesis of Pulmonary Arterial Hypertension: Recent Advances

Inflammatory processes are increasingly recognized in the pathogenesis of the vascular remodeling that characterizes pulmonary arterial hypertension (PAH). Chronic inflammation may contribute to disease progression or serve as a biomarker of PAH severity. Furthermore, inflammatory pathways may represent possible therapeutic targets for novel PAH-specific drugs beyond the currently approved therapies targeting the endothelin, nitric oxide/cyclic GMP, and prostacyclin biological pathways. The main focus of this article is to provide recent advances in the understanding of the role of inflammatory pathways in the pathogenesis of PAH from preclinical studies and current clinical data supporting chronic inflammation in PAH patients and to discuss emerging therapeutic implications. © 2021 American Physiological Society. Compr Physiol 11:1805-1829, 2021.

Transcriptomic Analysis of Right Ventricular Remodeling in Two Rat Models of Pulmonary Hypertension: Identification and Validation of Epithelial-to-Mesenchymal Transition in Human Right Ventricular Failure

BACKGROUND

Right ventricular (RV) dysfunction is a significant prognostic determinant of morbidity and mortality in pulmonary arterial hypertension (PAH). Despite the importance of RV function in PAH, the underlying molecular mechanisms of RV dysfunction secondary to PAH remain unclear. We aim to identify and compare molecular determinants of RV failure using RNA sequencing of RV tissue from 2 clinically relevant animal models of PAH.

METHODS

We performed RNA sequencing on RV from rats treated with monocrotaline or Sugen with hypoxia/normoxia. PAH and RV failure were confirmed by catheterization and echocardiography. We validated the RV transcriptome results using quantitative real-time polymerase chain reaction, immunofluorescence, and Western blot. Immunohistochemistry and immunofluorescence were performed on human RV tissue from control (n=3) and PAH-induced RV failure patients (n=5).

RESULTS

We identified similar transcriptomic profiles of RV from monocrotaline- and Sugen with hypoxia-induced RV failure. Pathway analysis showed genes enriched in epithelial-to-mesenchymal transition, inflammation, and metabolism. Histological staining of human RV tissue from patients with RV failure secondary to PAH revealed significant RV fibrosis and endothelial-to-mesenchymal transition, as well as elevated cellular communication network factor 2 (top gene implicated in epithelial-to-mesenchymal transition/endothelial-to-mesenchymal transition) expression in perivascular areas compared with normal RV.

CONCLUSIONS

Transcriptomic signature of RV failure in monocrotaline and Sugen with hypoxia models showed similar gene expressions and biological pathways. We provide translational relevance of this transcriptomic signature using RV from patients with PAH to demonstrate evidence of epithelial-to-mesenchymal transition/endothelial-to-mesenchymal transition and protein expression of cellular communication network factor 2 (CTGF [connective tissue growth factor]). Targeting specific molecular mechanisms responsible for RV failure in monocrotaline and Sugen with hypoxia models may identify novel therapeutic strategies for PAH-associated RV failure.

Continuous Aerobic Exercise Prevents Detrimental Remodeling and Right Heart Myocyte Contraction and Calcium Cycling Dysfunction in Pulmonary Artery Hypertension

ABSTRACT

Pulmonary artery hypertension (PAH) imposes right heart and lung detrimental remodeling which impairs cardiac contractility, physical effort tolerance, and survival. The effects of an early moderate-intensity continuous aerobic exercise training on the right ventricle and lung structure, and on contractility and the calcium (Ca2+) transient in isolated myocytes from rats with severe PAH induced by monocrotaline were analyzed. Rats were divided into control sedentary (CS), control exercise (CE), monocrotaline sedentary (MS), and monocrotaline exercise (ME) groups. Animals from control exercise and ME groups underwent a moderate-intensity aerobic exercise on a treadmill (60 min/d; 60% intensity) for 32 days, after a monocrotaline (60 mg/kg body weight i.p.) or saline injection. The pulmonary artery resistance was higher in MS than in control sedentary (1.36-fold) and was reduced by 39.39% in ME compared with MS. Compared with MS, the ME group presented reduced alveolus (17%) and blood vessel (46%) wall, fibrosis (25.37%) and type I collagen content (55.78%), and increased alveolus (52.96%) and blood vessel (146.97%) lumen. In the right ventricle, the ME group exhibited diminished hypertrophy index (25.53%) and type I collagen content (40.42%) and improved myocyte contraction [ie, reduced times to peak (29.27%) and to 50% relax (13.79%)] and intracellular Ca2+ transient [ie, decreased times to peak (16.06%) and to 50% decay (7.41%)] compared with MS. Thus, early moderate-intensity continuous aerobic exercise prevents detrimental remodeling in the right heart and lung increases in the pulmonary artery resistance and dysfunction in single myocyte contraction and Ca2+ cycling in this model.

Treatment Targets for Right Ventricular Dysfunction in Pulmonary Arterial Hypertension

Right ventricle (RV) dysfunction is the strongest predictor of mortality in pulmonary arterial hypertension (PAH), but, at present, there are no therapies directly targeting the failing RV. Although there are shared molecular mechanisms in both RV and left ventricle (LV) dysfunction, there are important differences between the 2 ventricles that may allow for the development of RV-enhancing or RV-directed therapies. In this review, we discuss the current understandings of the dysregulated pathways that promote RV dysfunction, highlight RV-enriched or RV-specific pathways that may be of particular therapeutic value, and summarize recent and ongoing clinical trials that are investigating RV function in PAH. It is hoped that development of RV-targeted therapies will improve quality of life and enhance survival for this deadly disease.

Genetic Deficiency and Pharmacological Stabilization of Mast Cells Ameliorate Pressure Overload-Induced Maladaptive Right Ventricular Remodeling in Mice

Although the response of the right ventricle (RV) to the increased afterload is an important determinant of the patient outcome, very little is known about the underlying mechanisms. Mast cells have been implicated in the pathogenesis of left ventricular maladaptive remodeling and failure. However, the role of mast cells in RV remodeling remains unexplored. We subjected mast cell-deficient WBB6F1-KitW/W-v (Kit^W/Kit^W-v) mice and their mast cell-sufficient littermate controls (MC^+/+) to pulmonary artery banding (PAB). PAB led to RV dilatation, extensive myocardial fibrosis, and RV dysfunction in MC^+/+ mice. In PAB Kit^W/Kit^W-v mice, RV remodeling was characterized by minimal RV chamber dilatation and preserved RV function. We further administered to C57Bl/6J mice either placebo or cromolyn treatment starting from day 1 or 7 days after PAB surgery to test whether mast cells stabilizing drugs can prevent or reverse maladaptive RV remodeling. Both preventive and therapeutic cromolyn applications significantly attenuated RV dilatation and improved RV function. Our study establishes a previously undescribed role of mast cells in pressure overload-induced adverse RV remodeling. Mast cells may thus represent an interesting target for the development of a new therapeutic approach directed specifically at the heart.

Exercise preconditioning prevents left ventricular dysfunction and remodeling in monocrotaline-induced pulmonary hypertension

Background:

Despite pulmonary arterial hypertension (PAH) directly affects the right ventricle (RV), important structural, functional, and molecular changes also occur in left ventricle (LV). The objective of our study was to analyze the hypothetical cardioprotective effects of exercise preconditioning on LV in rats with monocrotaline (MCT)-induced PAH.

Methods:

Forty male Wistar rats were randomly separated in sedentary (SED) and trained group (EX; running sessions of 60 min/day, 5 days/wk, at 25 m/min, for 4 weeks). After 4 weeks, animals were injected with MCT (60 mg/kg; SED + MCT; EX + MCT) or vehicle (SED + V). Following an additional period of 4 weeks where all animals remained sedentary, we completed LV hemodynamic evaluation in baseline and isovolumic conditions and collected LV samples for histological and molecular analysis.

Results:

Preconditioning with exercise was capable to restore LV systolic and diastolic dysfunction in both baseline and isovolumic conditions (P < .05). This improved was paralleled with prevention of LV cardiomyocytes atrophy, fibrosis, and endothelin 1 mRNA levels (P < .05).

Conclusions:

Our findings suggest that exercise preconditioning can prevent LV dysfunction secondary to MCT-induced PAH, which is of particular interest for the familial form of the disease that is manifested by greater severity or earlier onset.

Different Intensity Exercise Preconditions Affect Cardiac Function of Exhausted Rats through Regulating TXNIP/TRX/NF-ĸBp65/NLRP3 Inflammatory Pathways

Objective

To investigate whether exercise preconditioning (EP) improves the rat cardiac dysfunction induced by exhaustive exercise (EE) through regulating NOD-like receptor protein 3 (NLRP3) inflammatory pathways and to confirm which intensity of EP is better.

Method

Ninety healthy male Sprague Dawley rats were randomly divided into five groups: a control group (CON), exhaustive exercise group (EE), low-, middle-, and high-intensity exercise precondition and exhaustive exercise group (LEP + EE, MEP + EE, HEP + EE group). We established the experimental model by referring to Bedford's motion load standard to complete the experiment. Then, the pathological changes of the myocardium were observed under a light microscope. Biomarker of myocardial injury in serum and oxidative stress factor in myocardial tissue were evaluated by ELISAs. The cardiac function parameters were detected using a Millar pressure and volume catheter. The levels of thioredoxin-interacting protein (TXNIP), thioredoxin protein (TRX), nuclear transcription factor kappa B_p65 (NF-ĸB_p65), NLRP3, and cysteinaspartate specific proteinase 1 (Caspase-1) protein in rats' myocardium were detected by western blotting.

Results

1. The myocardial structures of three EP + EE groups were all improved compared with EE groups. 2. The levels of the creatine phosphating-enzyme MB (CK-MB), reactive oxygen species (ROS), interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor alpha (TNF-α) in three EP + EE groups were all increased compared with CON but decreased compared with the EE group (P < 0.05). 3. Compared with the CON group, slope of end-systolic pressure volume relationship (ESPVR), ejection fraction (EF), and peak rate of the increase in pressure (dP/dt_max) all dropped to the lowest level in the EE group (P < 0.05), while the values of cardiac output (CO), stroke volume (SV), end-systolic volume (Ves), end-diastolic volume (Ved), and relaxation time constant (Tau) increased in the EE group (P < 0.05). 4. Compared with the CON group, the expression levels of TXNIP, NF-ĸB_p65, NLRP3, and Caspase-1 all increased obviously in the other groups (P < 0.05); meanwhile, they were all decreased in three EP + EE groups compared with the EE group (P < 0.05). 5. NLRP3 was positively correlated with heart rate, IL-6, and ROS, but negatively correlated with EF (P < 0.01).

Conclusion

EP protects the heart from EE-induced injury through downregulating TXNIP/TRX/NF-ĸB_p65/NLRP3 inflammatory signaling pathways. Moderate intensity EP has the best protective effect.

Right ventricular phenotype, function, and failure: a journey from evolution to clinics

The right ventricle has long been perceived as the "low pressure bystander" of the left ventricle. Although the structure consists of, at first glance, the same cardiomyocytes as the left ventricle, it is in fact derived from a different set of precursor cells and has a complex three-dimensional anatomy and a very distinct contraction pattern. Mechanisms of right ventricular failure, its detection and follow-up, and more specific different responses to pressure versus volume overload are still incompletely understood. In order to fully comprehend right ventricular form and function, evolutionary biological entities that have led to the specifics of right ventricular physiology and morphology need to be addressed. Processes responsible for cardiac formation are based on very ancient cardiac lineages and within the first few weeks of fetal life, the human heart seems to repeat cardiac evolution. Furthermore, it appears that most cardiogenic signal pathways (if not all) act in combination with tissue-specific transcriptional cofactors to exert inductive responses reflecting an important expansion of ancestral regulatory genes throughout evolution and eventually cardiac complexity. Such molecular entities result in specific biomechanics of the RV that differs from that of the left ventricle. It is clear that sole descriptions of right ventricular contraction patterns (and LV contraction patterns for that matter) are futile and need to be addressed into a bigger multilayer three-dimensional picture. Therefore, we aim to present a complete picture from evolution, formation, and clinical presentation of right ventricular (mal)adaptation and failure on a molecular, cellular, biomechanical, and (patho)anatomical basis.

Effects of Different Types of Exercise Training on Pulmonary Arterial Hypertension: A Systematic Review

Pulmonary arterial hypertension (PAH) represents a chronic progressive disease characterized by high blood pressure in the pulmonary arteries leading to right heart failure. The disease has been a focus of medical research for many years due to its worse prognosis and limited treatment options. The aim of this study was to systematically assess the effects of different types of exercise interventions on PAH. Electronic databases were searched until July 2019. MEDLINE database was used as the predominant source for this paper. Studies with regards to chronic physical activity in adult PAH patients are compared on retrieving evidence on cellular, physiological, and psychological alterations in the PAH setting. Twenty human studies and 12 rat trials were identified. Amongst all studies, a total of 628 human subjects and 614 rats were examined. Regular physical activity affects the production of nitric oxygen and attenuates right ventricular hypertrophy. A combination of aerobic, anaerobic, and respiratory muscle training induces the strongest improvement in functional capacity indicated by an increase of 6 MWD and VO₂peak. In human studies, an increase of quality of life was found. Exercise training has an overall positive effect on the physiological and psychological components of PAH. Consequently, PAH patients should be encouraged to take part in regular exercise training programs.

Exercise Training Attenuates Hypertension Through TLR4/MyD88/NF-κB Signaling in the Hypothalamic Paraventricular Nucleus

Exercise training (ExT) is beneficial for cardiovascular health, yet the central mechanism by which aerobic ExT attenuates the hypertensive responses remains unclear. Activation of pro-inflammatory cytokines (PICs) in the hypothalamic paraventricular nucleus (PVN) is important for the sympathoexcitation and hypertensive response. We thus hypothesized that aerobic ExT can decrease the blood pressure of hypertensive rats by reducing the levels of PICs through TLR4/MyD88/NF-κB signaling within the PVN. To examine this hypothesis, two-kidney-one-clip (2K1C) renovascular hypertensive rats were assigned to two groups: sedentary or exercise training and examined for 8 weeks. At the same time, bilateral PVN infusion of vehicle or TAK242, a TLR4 inhibitor, was performed on both groups. As a result, the systolic blood pressure (SBP), renal sympathetic nerve activity (RSNA) and plasma levels of norepinephrine (NE), epinephrine (EPI) were found significantly increased in 2K1C hypertensive rats. These rats also had higher levels of Fra-like activity, NF-κB p65 activity, TLR4, MyD88, IL-1β and TNF-α in the PVN than SHAM rats. Eight weeks of ExT attenuated the RSNA and SBP, repressed the NF-κB p65 activity, and reduced the increase of plasma levels of NE, EPI, and the expression of Fra-like, TLR4, MyD88, IL-1β and TNF-α in the PVN of 2K1C rats. These findings are highly similar to the results in 2K1C rats with bilateral PVN infusions of TLR4 inhibitor (TAK242). This suggests that 8 weeks of aerobic ExT may decrease blood pressure in hypertensive rats by reducing the PICs activation through TLR4/MyD88/NF-κB signaling within the PVN, and thus delays the progression of 2K1C renovascular hypertension.

One year of exercise training promotes distinct adaptations in right and left ventricle of female Sprague-Dawley rats

Aerobic exercise training induces a unique cardioprotective phenotype, but it is becoming clear that it does not promote the same structural, functional, and molecular adaptations in both ventricles. In the present study, we aimed to better characterize and compare the molecular pathways involved in the exercise-induced remodeling of both ventricles. Female Sprague-Dawley rats were randomly assigned to control and exercise groups. Animals in the exercise group were submitted to low-intensity treadmill exercise for 54 weeks. After the experimental period, biventricular hemodynamic analysis was performed and right and left ventricles were harvested for morphological and biochemical analyses. Data showed that long-term low-intensity exercise training improves cardiac function, especially left ventricular diastolic function; however, the expression of connexin-43, CCAAT-enhancer binding protein β, and c-kit did not change in none of the ventricles. In the right ventricle, long-term exercise training induced an increase of manganese superoxide dismutase and sirtuin 3 protein expression, suggestive of improved antioxidant capacity. Our results also support that long-term aerobic exercise training imposes greater metabolic remodeling to the right ventricle, mainly by increasing mitochondrial ability to produce ATP, with no association to estrogen-related receptor α regulation.

Plexiform Arteriopathy in Rodent Models of Pulmonary Arterial Hypertension

As time progresses, our understanding of disease pathology is propelled forward by technological advancements. Much of the advancements that aid in understanding disease mechanics are based on animal studies. Unfortunately, animal models often fail to recapitulate the entirety of the human disease. This is especially true with animal models used to study pulmonary arterial hypertension (PAH), a disease with two distinct phases. The first phase is defined by nonspecific medial and adventitial thickening of the pulmonary artery and is commonly reproduced in animal models, including the classic models (ie, hypoxia-induced pulmonary hypertension and monocrotaline lung injury model). However, many animal models, including the classic models, fail to capture the progressive, or second, phase of PAH. This is a stage defined by plexogenic arteriopathy, resulting in obliteration and occlusion of the small- to mid-sized pulmonary vessels. Each of these two phases results in severe pulmonary hypertension that directly leads to right ventricular hypertrophy, decompensated right-sided heart failure, and death. Fortunately, newly developed animal models have begun to address the second, more severe, side of PAH and aid in our ability to develop new therapeutics. Moreover, p38 mitogen-activated protein kinase activation emerges as a central molecular mediator of plexiform lesions in both experimental models and human disease. Therefore, this review will focus on plexiform arteriopathy in experimental animal models of PAH.

Novel insights into the molecular mechanisms underlying the beneficial effects of exercise training on pulmonary arterial hypertension

BACKGROUND

Recent animal and clinical studies report that exercise training exerts positive influences in pulmonary arterial hypertension (PAH); however, the underlying mechanisms are largely unknown. To give insight into the molecular mechanisms of the improvement effects, we performed gene expression analysis.

METHODS

Three Gene Expression Omnibus (GEO) datasets were analyzed, including peripheral blood mononuclear (PBMC) gene expression profiles of exercise training in men and patients with PAH. Differentially expressed genes (DEGs) in each dataset were identified, and then, the common DEGs positively regulated by PAH and negatively regulated by exercise training, or the opposite, were further identified. Subsequently, biological processes and pathways were analyzed.

RESULTS

A total of 7229 DEGs with logFC>0.3 and P<0.05 were identified in exercise, whereas 749 and 2207 DEGs were identified in PAH from the two datasets. After overlapping the whole DEGs from all three datasets, total 16 common DEGs were identified, including BCLAF1, SATB1 and ZFP36L2. Seven of them were up-regulated in exercise training and down-regulated in PAH, and the others were opposite. In addition, these common DEGs were mainly enriched in negative regulation of cellular process, negative regulation of biological process and negative regulation of cellular macromolecule biosynthetic process.

CONCLUSIONS

Some genes have been implicated in the improvement of pulmonary vascular remodeling and PAH. These findings could not only improve the knowledge about the molecular mechanisms underlying the beneficial effects of exercise training on PAH, but also provide clues for further clinical and animal studies.

Role of cardiac inflammation in right ventricular failure

Right ventricular failure (RVF) is the main determinant of mortality in patients with pulmonary arterial hypertension (PAH). Although the exact pathophysiology underlying RVF remains unclear, inflammation may play an important role, as it does in left heart failure. Perivascular pulmonary artery and systemic inflammation is relatively well studied and known to contribute to the initiation and maintenance of the pulmonary vascular insult in PAH. However, less attention has been paid to the role of cardiac inflammation in RVF and PAH. Consistent with many other types of heart failure, cardiac inflammation, triggered by systemic and local stressors, has been shown in RVF patients as well as in RVF animal models. RV inflammation likely contributes to impaired RV contractility, maladaptive remodelling and a vicious circle between RV and pulmonary vascular injury. Although the potential to improve RV function through anti-inflammatory therapy has not been tested, this approach has been applied clinically in left ventricular failure patients, with variable success. Because inflammation plays a dual role in the development of both pulmonary vascular pathology and RVF, anti-inflammatory therapies may have a potential double benefit in patients with PAH and associated RVF.

Inflammatory Mediators Drive Adverse Right Ventricular Remodeling and Dysfunction and Serve as Potential Biomarkers

Adverse right ventricular (RV) remodeling leads to ventricular dysfunction and failure that represents an important determinant of outcome in patients with pulmonary hypertension (PH). Recent evidence indicates that inflammatory activation contributes to the pathogenesis of adverse RV remodeling and dysfunction. It has been shown that accumulation of inflammatory cells such as macrophages and mast cells in the right ventricle is associated with maladaptive RV remodeling. In addition, inhibition of inflammation in animal models of RV failure ameliorated RV structural and functional impairment. Furthermore, a number of circulating inflammatory mediators have been demonstrated to be associated with RV performance. This work reviews the role of inflammation in RV remodeling and dysfunction and discusses anti-inflammatory strategies that may attenuate adverse structural alterations while promoting improvement of RV function.