Cascading renal injury after brain death: Unveiling glycocalyx alteration and the potential protective role of tacrolimus.

Brain death (BD) is a complex medical state that triggers systemic disturbances and a cascade of pathophysiological processes. This condition significantly impairs both kidney function and structural integrity, thereby presenting considerable challenges to graft viability and the long-term success of transplantation endeavors. Tacrolimus (FK506), an immunosuppressive drug, was used in this study to assess its impact as a pretreatment on brain death-induced renal injury. This study aimed to investigate changes associated with brain death-induced renal injury in a 4-month-old female porcine model. The experimental groups included brain death placebo-pretreated (BD; n = 9), brain death tacrolimus-pretreated using the clinical dose of 0.25 mg/kg the day before surgery, followed by 0.05 mg/kg/day 1 hour before the procedure (BD + FK506; n = 8), and control (ctrl, n = 7) piglets, which did not undergo brain death induction. Furthermore, we aimed to assess the effect of FK506 on these renal alterations through graft preconditioning. We hypothesized that immunosuppressive properties of FK506 reduce tissue inflammation and preserve the glycocalyx. Our findings revealed a series of interconnected events triggered by BD, leading to a deterioration of renal function and increased proteinuria, increased apoptosis in the vessels, glomeruli and tubules, significant leukocyte infiltration into renal tissue, and degradation of the glycocalyx in comparison with ctrl group. Importantly, treatment with FK506 demonstrated significant efficacy in attenuating these adverse effects. FK506 helped reduce apoptosis, maintain glycocalyx integrity, regulate neutrophil infiltration, and mitigate renal injury following BD. This study offers new insights into the pathophysiology of BD-induced renal injury, emphasizing the potential of FK506 pretreatment as a promising therapeutic intervention for organ preservation, through maintaining endothelial function with the additional benefit of limiting the risk of rejection.

Inhibition of circulating dipeptidyl-peptidase 3 by procizumab in experimental septic shock reduces catecholamine exposure and myocardial injury.

BACKGROUND: Dipeptidyl peptidase 3 (DPP3) is a ubiquitous cytosolic enzyme released into the bloodstream after tissue injury, that can degrade angiotensin II. High concentrations of circulating DPP3 (cDPP3) have been associated with worse outcomes during sepsis. The aim of this study was to assess the effect of Procizumab (PCZ), a monoclonal antibody that neutralizes cDPP3, in an experimental model of septic shock. METHODS: In this randomized, open-label, controlled study, 16 anesthetized and mechanically ventilated pigs with peritonitis were randomized to receive PCZ or standard treatment when the mean arterial pressure (MAP) dropped below 50 mmHg. Resuscitation with fluids, antimicrobial therapy, peritoneal lavage, and norepinephrine was initiated one hour later to maintain MAP between 65-75 mmHg for 12 h. Hemodynamic variables, tissue oxygenation indices, and measures of organ failure and myocardial injury were collected. Organ blood flow was assessed using isotopic assessment (99mtechnetium albumin). cDPP3 activity, equilibrium analysis of the renin-angiotensin system and circulating catecholamines were measured. Tissue mRNA expression of interleukin-6 and downregulation of adrenergic and angiotensin receptors were assessed on vascular and myocardial samples. RESULTS: PCZ-treated animals had reduced cDPP3 levels and required less norepinephrine and fluid than septic control animals for similar organ perfusion and regional blood flow. PCZ-treated animals had less myocardial injury, and higher PaO2/FiO2 ratios. PCZ was associated with lower circulating catecholamine levels; higher circulating angiotensin II and higher angiotensin II receptor type 1 myocardial protein expression, and with lower myocardial and radial artery mRNA interleukin-6 expression. CONCLUSIONS: In an experimental model of septic shock, PCZ administration was associated with reduced fluid and catecholamine requirements, less myocardial injury and cardiovascular inflammation, along with preserved angiotensin II signaling.

Early Alteration of Right Ventricle-Pulmonary Artery Coupling in Experimental Heart Failure With Preserved Ejection Fraction.

BACKGROUND: Pulmonary hypertension and right ventricular (RV) dysfunction are major prognostic determinants in patients with heart failure with preserved ejection fraction (HFpEF). The underlying pathomechanisms remain unknown. In this context, we sought to study the pathogenesis of pulmonary hypertension and RV dysfunction in a rat model of obesity-associated HFpEF. METHODS AND RESULTS: HFpEF was induced in obesity-prone rats fed a high-fat diet (n=13) and compared with obesity-resistant rats fed with standard chow (n=9). After 12 months, the animals underwent echocardiographic and hemodynamic evaluation followed by tissue sampling for pathobiological assessment. HFpEF rats presented mild RV pressure overload (with increased RV systolic pressure and pulmonary vascular resistance). No changes in pulmonary artery medial thickness and ex vivo vasoreactivity (to acetylcholine and endothelin-1) were observed and RNA sequencing analysis failed to identify gene clustering in HFpEF lungs. However, released nitric oxide levels were decreased in HFpEF pulmonary artery, while lung expression of preproendothelin-1 was increased. In HFpEF rats, RV structure and function were altered, with RV enlargement, decreased RV fractional area change and free wall longitudinal fractional shortening, together with altered right ventricle-pulmonary artery coupling (estimated by tricuspid annular plane systolic excursion/systolic pulmonary artery pressure). Hypertrophy and apoptosis (evaluated by transferase biotin- dUTP nick-end labeling staining) were increased in right and left ventricles of HFpEF rats. There was an inverse correlation between tricuspid annular plane systolic excursion/systolic pulmonary artery pressure and RV apoptotic rate. Plasma levels of soluble suppression of tumorigenicity-2, interleukin-1ß, -6 and -17A were increased in HFpEF rats. CONCLUSIONS: Obesity-associated HFpEF in rats spontaneously evolves to pulmonary hypertension-HFpEF associated with impaired right ventricle-pulmonary artery coupling that appears disproportionate to a slight increase in RV afterload.

Neutralization of extracellular histones by sodium-Β-O-methyl cellobioside sulfate in septic shock.

BACKGROUND: Extracellular histones have been associated with severity and outcome in sepsis. The aim of the present study was to assess the effects of sodium-ß-O-Methyl cellobioside sulfate (mCBS), a histone-neutralizing polyanion, on the severity and outcome of sepsis in an experimental model. METHODS: This randomized placebo-controlled experimental study was performed in 24 mechanically ventilated female sheep. Sepsis was induced by fecal peritonitis. Animals were randomized to three groups: control, early treatment, and late treatment (n = 8 each). mCBS was given as a bolus (1 mg/kg) followed by a continuous infusion (1 mg/kg/h) just after sepsis induction in the early treatment group, and 4 h later in the late treatment group. Fluid administration and antimicrobial therapy were initiated 4 h T4 after feces injection, peritoneal lavage performed, and a norepinephrine infusion titrated to maintain mean arterial pressure (MAP) between 65-75 mmHg. The experiment was blinded and lasted maximum 24 h. RESULTS: During the first 4 h, MAP remained > 65 mmHg in the early treatment group but decreased significantly in the others (p < 0.01 for interaction, median value at T4: (79 [70-90] mmHg for early treatment, 57 [70-90] mmHg for late treatment, and 55 [49-60] mmHg for the control group). mCBS-treated animals required significantly less norepinephrine to maintain MAP than controls (p < 0.01 for interaction) and had lower creatinine (p < 0.01), lactate (p < 0.01), and interleukin-6 (p < 0.01) levels, associated with reduced changes in H3.1 nucleosome levels (p = 0.02). Early treatment was associated with lower norepinephrine requirements than later treatment. Two control animals died; all the mCBS-treated animals survived. CONCLUSIONS: Neutralization of extracellular histones with mCBS was associated with reduced norepinephrine requirements, improved tissue perfusion, less renal dysfunction, and lower circulating IL-6 in experimental septic shock and may represent a new therapeutic approach to be tested in clinical trials.

Beneficial Effects of Tacrolimus on Brain-Death-Associated Right Ventricular Dysfunction in Pigs.

BACKGROUND: Right ventricular (RV) dysfunction remains a major problem after heart transplantation and may be associated with brain death (BD) in a donor. A calcineurin inhibitor tacrolimus was recently found to have beneficial effects on heart function. Here, we examined whether tacrolimus might prevent BD-induced RV dysfunction and the associated pathobiological changes. METHODS: After randomized tacrolimus (n = 8; 0.05 mg·kg-1·day-1) or placebo (n = 9) pretreatment, pigs were assigned to a BD procedure and hemodynamically investigated 1, 3, 5, and 7 h after the Cushing reflex. After euthanasia, myocardial tissue was sampled for pathobiological evaluation. Seven pigs were used as controls. RESULTS: Calcineurin inhibition prevented increases in pulmonary vascular resistance and RV-arterial decoupling induced by BD. BD was associated with an increased RV pro-apoptotic Bax-to-Bcl2 ratio and RV and LV apoptotic rates, which were prevented by tacrolimus. BD induced increased expression of the pro-inflammatory IL-6-to-IL-10 ratio, their related receptors, and vascular cell adhesion molecule-1 in both the RV and LV. These changes were prevented by tacrolimus. RV and LV neutrophil infiltration induced by BD was partly prevented by tacrolimus. BD was associated with decreased RV expression of the ß-1 adrenergic receptor and sarcomere (myosin heavy chain [MYH]7-to-MYH6 ratio) components, while ß-3 adrenergic receptor, nitric oxide-synthase 3, and glucose transporter 1 expression increased. These changes were prevented by tacrolimus. CONCLUSIONS: Brain death was associated with isolated RV dysfunction. Tacrolimus prevented RV dysfunction induced by BD through the inhibition of apoptosis and inflammation activation.

Angiotensin 1-7 in an experimental septic shock model.

BACKGROUND: Alterations in the renin-angiotensin system have been implicated in the pathophysiology of septic shock. In particular, angiotensin 1-7 (Ang-(1-7)), an anti-inflammatory heptapeptide, has been hypothesized to have beneficial effects. The aim of the present study was to test the effects of Ang-(1-7) infusion on the development and severity of septic shock. METHODS: This randomized, open-label, controlled study was performed in 14 anesthetized and mechanically ventilated sheep. Immediately after sepsis induction by bacterial peritonitis, animals received either Ang-(1-7) (n = 7) or placebo (n = 7) intravenously. Fluid resuscitation, antimicrobial therapy, and peritoneal lavage were initiated 4 h after sepsis induction. Norepinephrine administration was titrated to maintain mean arterial pressure (MAP) between 65 and 75 mmHg. RESULTS: There were no differences in baseline characteristics between groups. Septic shock was prevented in 6 of the 7 animals in the Ang-(1-7) group at the end of the 24-h period. Fluid balance and MAP were similar in the two groups; however, MAP was achieved with a mean norepinephrine dose of 0.4 µg/kg/min in the Ang-(1-7) group compared to 4.3 µg/kg/min in the control group. Heart rate and cardiac output index were lower in the Ang (1-7) than in the control group, as were plasma interleukin-6 levels, and creatinine levels. Platelet count and PaO2/FiO2 ratio were higher in the Ang-(1-7) group. Mean arterial lactate at the end of the experiment was 1.6 mmol/L in the Ang-(1-7) group compared to 7.4 mmol/L in the control group. CONCLUSIONS: In this experimental septic shock model, early Ang-(1-7) infusion prevented the development of septic shock, reduced norepinephrine requirements, limited interleukine-6 increase and prevented renal dysfunction.

Altered Left Ventricular Rat Gene Expression Induced by the Myosin Activator Omecamtiv Mecarbil.

To explore the impact of omecamtiv mecarbil (OM) on the gene expression profile in adult male rats. Fourteen male Wistar rats were randomly assigned to a single OM (1.2 mg/kg/h; n = 6) or placebo (n = 8) 30-min infusion. Echocardiography was performed before and after OM infusion. Seven days after infusion, rats were euthanized, and left ventricular (LV) tissues were removed for real-time quantitative polymerase chain reaction (RTq-PCR) experiments. After OM infusion, pro-apoptotic Bax-to-Bcl2 ratio was decreased, with increased Bcl2 and similar Bax gene expression. The gene expression of molecules regulating oxidative stress, including glutathione disulfide reductase (Gsr) and superoxide dismutases (Sod1/Sod2), remained unchanged, whereas the expression of antioxidant glutathione peroxidase (Gpx) increased. While LV gene expression of key energy sensors, peroxisome proliferator activator (Ppar) α and γ, AMP-activated protein kinase (Ampk), and carnitine palmitoyltransferase 1 (Cpt1) remained unchanged after OM infusion, and the expression of pyruvate dehydrogenase kinase 4 (Pdk4) increased. The LV expression of the major myocardial glucose transporter Glut1 decreased, with no changes in Glut4 expression, whereas the LV expression of oxidized low-density lipoprotein receptor 1 (Olr1) and arachidonate 15-lipoxygenase (Alox15) increased, with no changes in fatty acid transporter Cd36. An increased LV expression of angiotensin II receptors AT1 and AT2 was observed, with no changes in angiotensin I-converting enzyme expression. The Kalikrein-bradykinin system was upregulated with increased LV expression of kallikrein-related peptidases Klk8, Klk1c2, and Klk1c12 and bradykinin receptors B1 and B2 (Bdkrb1 and Bdkrb2), whereas the LV expression of inducible nitric oxide synthase 2 (Nos2) increased. LV expression in major molecular determinants involved in calcium-dependent myocardial contraction remained unchanged, except for an increased LV expression of calcium/calmodulin-dependent protein kinase II delta (Cacna1c) in response to OM. A single intravenous infusion of OM, in adult healthy rats, resulted in significant changes in the LV expression of genes regulating apoptosis, oxidative stress, metabolism, and cardiac contractility.

Prostacyclin receptor agonists induce DUSP1 to inhibit pulmonary artery smooth muscle cell proliferation.

AIMS: Upregulated p38MAPK signaling is implicated in the accelerated proliferation of pulmonary artery smooth muscle cells (PA-SMCs) and the pathogenesis of pulmonary artery remodeling observed in pulmonary arterial hypertension (PAH). Previously, we reported that after endothelin-1 (ET-1) pretreatment, bone morphogenetic protein 2 (BMP2) activates p38MAPK signaling and accelerates PA-SMC proliferation. The activity of p38MAPK signaling is tightly regulated by the inactivation of dual-specificity phosphatase 1 (DUSP1). Activated p38MAPK induces DUSP1 expression, forming a negative feedback loop. Prostacyclin IP receptor agonists (prostacyclin and selexipag) are used to treat PAH. In this study, we aimed to verify whether IP receptor agonists affect DUSP1 expression and accelerate the proliferation of PA-SMCs. MAIN METHODS: PA-SMCs were treated with BMP2, ET-1, prostacyclin, and MRE-269, an active metabolite of selexipag, either alone or in combination. We quantified mRNA expressions using real-time quantitative polymerase chain reaction. Pulmonary artery specimens and PA-SMCs were obtained during lung transplantation in patients with PAH. KEY FINDINGS: Both prostacyclin and MRE-269 increased DUSP1 expression. Combined treatment with BMP2 and ET-1 induced cyclin D1 and DUSP1 expression and increased PA-SMC proliferation. MRE-269 attenuated BMP2/ET-1-induced cell proliferation. ET-1 increased DUSP1 expression in PA-SMCs from control patients but not in PA-SMCs from patients with PAH. SIGNIFICANCE: This study showed that the p38MAPK/DUSP1 negative feedback loop is impaired in PAH, contributing to unregulated p38MAPK activation and PA-SMC hyperplasia. IP receptor agonist MRE-269 increases DUSP1 expression and inhibit p38MAPK-mediated PA-SMC proliferation. Future elucidation of the detailed mechanism underlying reduced DUSP1 expression would be informative for PAH treatment.

Detection of soluble suppression of tumorigenicity 2 and N-terminal B-type natriuretic peptide in a rat model of aortic regurgitation: differential responses to omecamtiv mecarbil.

OBJECTIVES: Both N-terminal fragment of B-type natriuretic peptide (NT-proBNP) and soluble isoform of ST2 (sST2) have been identified as biomarkers of heart failure. We evaluated the plasma levels of NT-proBNP and sST2 in a rat model of severe aortic valve regurgitation (AR) and correlated these findings with echocardiographic measurements. We also examined the impact of omecamtiv mecarbil (OM) on these parameters. METHODS: The plasma levels of NT-proBNP and sST2 were measured in 18 rats both before and 2 months after surgical induction of AR, and at these same time points, in six rats assigned to a sham-procedure control group. Plasma biomarkers were then measured again after infusion of OM or placebo in rats with AR (n=8 and 10, respectively) and OM alone in the sham control rats (n=6). Echocardiographic measurements were collected before and 2 months after induction of AR. RESULTS: Our results revealed increased levels of plasma NT-proBNP (219 ± 34 pg/mL vs. 429 ± 374 pg/mL; p<0.001) in rats with AR at day 7 after infusion of placebo, whereas plasma levels of sST2 were higher in this cohort after infusion of either OM or placebo. We identified a significant positive correlation between plasma sST2 with posterior wall thickness in diastole (r=0.34, p<0.05) and total body weight (r=0.45, p<0.01) in rats with surgically induced AR. CONCLUSIONS: Because sST2 increased markedly, whereas NT-proBNP remained unchanged, when OM was administered, we hypothesize that sST2 has a distinct capability to detect deleterious effects of passive muscle tension, not reliably assessed by NT-proBNP, in the setting of AR.

Myocardial effects of angiotensin II compared to norepinephrine in an animal model of septic shock.

BACKGROUND: Angiotensin II is one of the vasopressors available for use in septic shock. However, its effects on the septic myocardium remain unclear. The aim of the study was to compare the effects of angiotensin II and norepinephrine on cardiac function and myocardial oxygen consumption, inflammation and injury in experimental septic shock. METHODS: This randomized, open-label, controlled study was performed in 20 anesthetized and mechanically ventilated pigs. Septic shock was induced by fecal peritonitis in 16 animals, and four pigs served as shams. Resuscitation with fluids, antimicrobial therapy and abdominal drainage was initiated one hour after the onset of septic shock. Septic pigs were randomly allocated to receive one of the two drugs to maintain mean arterial pressure between 65 and 75 mmHg for 8 h. RESULTS: There were no differences in MAP, cardiac output, heart rate, fluid balance or tissue perfusion indices in the two treatment groups but myocardial oxygen consumption was greater in the norepinephrine-treated animals. Myocardial mRNA expression of interleukin-6, interleukin-6 receptor, interleukin-1 alpha, and interleukin-1 beta was higher in the norepinephrine than in the angiotensin II group. CONCLUSIONS: In septic shock, angiotensin II administration is associated with a similar level of cardiovascular resuscitation and less myocardial oxygen consumption, and inflammation compared to norepinephrine.

Tacrolimus Prevents Mechanical and Humoral Alterations in Brain Death-induced Lung Injury in Pigs.

Rationale: Donor brain death-induced lung injury may compromise graft function after transplantation. Establishing strategies to attenuate lung damage remains a challenge because the underlying mechanisms remain uncertain. Objectives: The effects of tacrolimus pretreatment were evaluated in an experimental model of brain death-induced lung injury. Methods: Brain death was induced by slow intracranial infusion of blood in anesthetized pigs after randomization to tacrolimus (orally administered at 0.25 mg ⋅ kg-1 twice daily the day before the experiment and intravenously at 0.05 mg ⋅ kg-1 1 h before the experiment; n = 8) or placebo (n = 9) pretreatment. Hemodynamic measurements were performed 1, 3, 5, and 7 hours after brain death. After euthanasia of the animals, lung tissue was sampled for pathobiological and histological analysis, including lung injury score (LIS). Measurements and Main Results: Tacrolimus pretreatment prevented increases in pulmonary arterial pressure, pulmonary vascular resistance, and pulmonary capillary pressure and decreases in systemic arterial pressure and thermodilution cardiac output associated with brain death. After brain death, the ratio of PaO2 to FiO2 decreased, which was prevented by tacrolimus. Tacrolimus pretreatment prevented increases in the ratio of IL-6 to IL-10, VCAM1 (vascular cell adhesion molecule 1), circulating concentrations of IL-1ß, and glycocalyx-derived molecules. Tacrolimus partially decreased apoptosis (Bax [Bcl2-associated X apoptosis regulator]-to-Bcl2 [B-cell lymphoma-2] ratio [P = 0.07] and number of apoptotic cells in the lungs [P < 0.05]) but failed to improve LIS. Conclusions: Immunomodulation through tacrolimus pretreatment prevented pulmonary capillary hypertension as well as the activation of inflammatory and apoptotic processes in the lungs after brain death; however, LIS did not improve.

Early Hyperdynamic Sepsis Alters Coronary Blood Flow Regulation in Porcine Fecal Peritonitis.

Background: Sepsis is a common condition known to impair blood flow regulation and microcirculation, which can ultimately lead to organ dysfunction but such contribution of the coronary circulation remains to be clarified. We investigated coronary blood flow regulatory mechanisms, including autoregulation, metabolic regulation, and endothelial vasodilatory response, in an experimental porcine model of early hyperdynamic sepsis. Methods: Fourteen pigs were randomized to sham (n = 7) or fecal peritonitis-induced sepsis (n = 7) procedures. At baseline, 6 and 12 h after peritonitis induction, the animals underwent general and coronary hemodynamic evaluation, including determination of autoregulatory breakpoint pressure and adenosine-induced maximal coronary vasodilation for coronary flow reserve and hyperemic microvascular resistance calculation. Endothelial-derived vasodilatory response was assessed both in vivo and ex vivo using bradykinin. Coronary arteries were sampled for pathobiological evaluation. Results: Sepsis resulted in a right shift of the autoregulatory breakpoint pressure, decreased coronary blood flow reserve and increased hyperemic microvascular resistance from the 6th h after peritonitis induction. In vivo and ex vivo endothelial vasomotor function was preserved. Sepsis increased coronary arteries expressions of nitric oxide synthases, prostaglandin I2 receptor, and prostaglandin F2α receptor. Conclusion: Autoregulation and metabolic blood flow regulation were both impaired in the coronary circulation during experimental hyperdynamic sepsis, although endothelial vasodilatory response was preserved.

Acute effects of hypouricemia on endothelium, oxidative stress, and arterial stiffness: A randomized, double-blind, crossover study.

We hypothesized acute moderate and drastic reductions in uric acid concentration exert different effects on arterial function in healthy normotensive and hypertensive adults. Thirty-six adults (aged 58 [55;63] years) with or without primary hypertension participated in a three-way, randomized, double-blind, crossover study in which [placebo] and [febuxostat] and [febuxostat and rasburicase] were administered. Febuxostat and rasburicase reduce the uric acid concentration by xanthine oxidoreductase inhibition and uric acid degradation into allantoin, respectively. Endothelial function was assessed in response to acetylcholine, sodium nitroprusside, heating (with and without nitric oxide synthase inhibition) using a laser Doppler imager. Arterial stiffness was determined by applanation tonometry, together with blood pressure, renin-angiotensin system activity, oxidative stress, and inflammation. Uric acid concentration was 5.1 [4.1;5.9], 1.9 [1.2;2.2] and 0.2 [0.2;0.3] mg/dL with [placebo], [febuxostat] and [febuxostat-rasburicase] treatments, respectively (p < 0.0001). Febuxostat improved endothelial response to heat particularly when nitric oxide synthase was inhibited (p < 0.05) and reduced diastolic and mean arterial pressure (p = 0.008 and 0.02, respectively). The augmentation index decreased with febuxostat (ANOVA p < 0.04). Myeloperoxidase activity profoundly decreased with febuxostat combined with rasburicase (p < 0.0001). When uric acid dropped, plasmatic antioxidant capacity markedly decreased, while superoxide dismutase activity increased (p < 0.0001). Other inflammatory and oxidant markers did not differ. Acute moderate hypouricemia encompasses minor improvements in endothelial function, blood pressure, and arterial stiffness. Clinical Trial Registration: NCT03395977, https://clinicaltrials.gov/ct2/show/NCT03395977.

A Preclinical Rat Model of Heart Failure With Preserved Ejection Fraction With Multiple Comorbidities.

Heart failure with preserved ejection fraction (HFpEF) is a common complex clinical syndrome for which there are currently few evidence-based therapies. As patients with HFpEF very often present with comorbidities comprising the metabolic syndrome, we hypothesized, that metabolic syndrome could lead over time to the development of diastolic dysfunction and HFpEF. Obesity-prone rats were exposed to high-fat diet and compared to obesity-resistant rats fed with standard chow. Phenotyping of metabolic syndrome, associated with echocardiographic and cardiac hemodynamic measurements, was performed after 4 and 12 months. Blood and myocardial tissue sampling were performed for pathobiological evaluation. High-fat diet in obesity-prone rats elicited metabolic syndrome, characterized by increased body and abdominal fat weights, glucose intolerance and hyperlipidemia, as well as increased left ventricular (LV) systolic pressure (after 12 months). This was associated with LV diastolic dysfunction (assessed by increased LV end-diastolic pressure) and pulmonary hypertension (assessed by increased right ventricular systolic pressure). Echocardiography revealed significant concentric LV hypertrophy, while LV ejection fraction was preserved. LV remodeling was associated with cardiomyocyte hypertrophy, as well as myocardial and perivascular fibrosis. Circulating levels of soluble ST2 (the interleukin-1 receptor-like) markedly increased in rats with HFpEF, while plasma NT-proBNP levels decreased. RNA-sequencing analysis identified clusters of genes implicated in fatty acid metabolism and calcium-dependent contraction as upregulated pathways in the myocardium of rats with HFpEF. High-fat diet during 12 months in obesity-prone rats led to the development of a relevant preclinical model of HFpEF with multiple comorbidities, suitable for investigating novel therapeutic interventions.

Chemerin Added to Endothelin-1 Promotes Rat Pulmonary Artery Smooth Muscle Cell Proliferation and Migration.

BACKGROUND: While chemerin has been shown to increase proliferation and migration of systemic vascular smooth muscle cells (SMCs) contributing therefore to the development of hypertension, this remains to be clarified for the pulmonary circulation. METHODS: Expression of chemerin and its three receptors (CMKRL1, CCRL2, GPR1) was examined by immunohistochemistry and RTq-PCR in lungs, pulmonary artery, and thoracic aorta from Wistar rats. Primary cultured rat pulmonary artery and thoracic aorta SMCs treated with recombinant chemerin (tested from 5.10-9 to 10-7 mol/L) were assessed for proliferation and migration (both with 10-7 mol/L endothelin-1), as well as for staurosporine-induced apoptosis. RESULTS: In pulmonary artery and thoracic aorta, CMKLR1 expression was detected in both endothelial cells and SMCs. In primary cultured pulmonary artery SMCs, chemerin and its three receptors were expressed, and CMKLR1 expression was higher than those of CCRL2 and GPR1. Chemerin added to endothelin-1 increased pulmonary artery SMC proliferation, while chemerin or endothelin-1 alone did not. This effect was less pronounced in thoracic aorta SMCs. Chemerin induced pulmonary artery and thoracic aorta SMC migration, which was exacerbated by endothelin-1 and more pronounced in thoracic aorta SMCs. Chemerin concentration-dependently reduced staurosporine-induced apoptosis in both pulmonary artery and thoracic aorta SMCs. In pulmonary artery SMCs, endothelin-1 treatment increased the expression of CMKLR1, CCRL2, and GPR1, while these expressions were not altered in thoracic aorta SMCs. CONCLUSION: Chemerin/CMKRL1 signaling, in conjunction with a key mediator in the pathogenesis of pulmonary hypertensive diseases, endothelin-1, stimulated proliferation and migration, and increased resistance to apoptosis in rat primary cultured pulmonary artery SMCs. Our results suggest that this signaling could play a role in pulmonary artery remodeling observed in pulmonary hypertension.

An intact animal model for the assessment of coronary blood flow regulation "Coronary blood flow regulation".

Coronary blood flow adapts to metabolic demand ("metabolic regulation") and remains relatively constant over a range of pressure changes ("autoregulation"). Coronary metabolic regulation and autoregulation are usually studied separately. We developed an intact animal experimental model to explore both regulatory mechanisms of coronary blood flow. Coronary pressure and flow-velocities were measured in four anesthetized and closed-chest pigs using an intracoronary Doppler wire. Metabolic regulation was assessed by coronary flow reserve defined as the ratio between the maximally vasodilated and the basal flow, with hyperemia achieved using intracoronary administration of adenosine (90 µg) or bradykinin (10-6  M) as endothelium-independent and -dependent vasodilators respectively. For both vasodilators, we found a healthy coronary flow reserve ≥ 3.0 at baseline, which was maintained at 2.9 ± 0.2 after a 6-hr period. Autoregulation was assessed by the lower breakpoint of coronary pressure-flow relationships, with gradual decrease in coronary pressure through the inflation of an intracoronary balloon. We found a lower limit of autoregulation between 42 and 55 mmHg, which was stable during a 6-hr period. We conclude that this intact animal model is adequate for the study of pharmacological interventions on the coronary circulation in health and disease, and as such suitable for preclinical drug studies.

Endothelin-1 induces lysyl oxidase expression in pulmonary artery smooth muscle cells.

The increase in thickening of the arterial wall of pulmonary arterial hypertension (PAH) includes cellular proliferation as well as matrix deposition and interrupted internal elastic lamina (IEL) consisting of a thick homogeneous sheet of elastin. Little is, although, known about the detail of IEL formation in PAH. Endothelin-1 is overexpressed in pulmonary arterioles of PAH. We aimed to examine the expression of genes contributing to IEL formation in pulmonary artery smooth muscle cells (PASMCs) especially focused on lysyl oxidase (LOx), an exreacellular matrix enzyme that catalyzes the cross-linking of collagens or elastin. We quantified mRNA expressions of genes contributing to IEL formation including LOx in PASMCs using real-time quantitative polymerase chain reaction. We stimulated human PASMCs with endothelin-1 with prostacyclin or trapidil. Endothelin-1 significantly increased LOx expression. Prostacyclin and trapidil restored endothelin-1-induced LOx expression to the basal level. Endothelin-1 increased LOx expression strongly in PASMCs from PAH patients compared to those from controls. Trapidil reduced LOx expression only in PASMCs from PAH patients. Overexpressed endothelin-1 in PAH patients can increase expression of LOx and agitate cross-linking of elastin and collagen, resulting in ectopic deposition of these in the vascular media.

High fat diet altered cardiac metabolic gene profile in Psammomys obesus gerbils.

BACKGROUND: In metabolic disorders, myocardial fatty infiltration is critically associated with lipotoxic cardiomyopathy. METHODS: Twenty Psammomys obesus gerbils were randomly assigned to normal plant or high fat diet. Sixteen weeks later, myocardium was sampled for pathobiological evaluation. RESULTS: A sixteen-week high fat diet resulted in myocardial structure disorganization, with collagen deposits, lipid accumulation, cardiomyocyte apoptosis and inflammatory cell infiltration. Myocardial expressions of glucose transporter GLUT1 and pyruvate dehydrogenase (PDH) inhibitor, PDH kinase (PDK)4 increased, while insulin-regulated GLUT4 expression remained unchanged. Myocardial expressions of molecules regulating fatty acid transport, CD36 and fatty acid binding protein (FABP)3, were increased, while expression of rate-controlling fatty acid ß-oxidation, carnitine palmitoyl transferase (CPT)1B decreased. Myocardial expression of AMP-activated protein kinase (AMPK), decreased, while expression of peroxisome proliferator activated receptors (PPAR)-α and -γ did not change. CONCLUSION: In high fat diet fed Psammomys obesus, an original experimental model of nutritionally induced metabolic syndrome mixing genetic predisposition and environment interactions, a short period of high fat feeding was sufficient to induce myocardial structural alterations, associated with altered myocardial metabolic gene expression in favor of lipid accumulation.

Chemerin influences endothelin- and serotonin-induced pulmonary artery vasoconstriction in rats.

AIMS: Chemerin has been recently identified as a vasoactive adipokine implicated in blood pressure regulation. In this context, we evaluated whether chemerin could influence pulmonary vasoreactive response. MATERIALS AND METHODS: Vascular reactivity to chemerin and to phenylephrine, serotonin and endothelin-1 after chemerin pretreatment was evaluated in rat isolated pulmonary artery versus thoracic aorta with and without endothelium. Vasoreactivity to acetylcholine in presence of nitric oxide (NO)-synthase inhibitor (L-NAME) and to NO donor sodium nitroprusside (SNP) was evaluated in chemerin-pretreated pulmonary artery versus thoracic aorta with endothelium. Pretreatment with ODQ, a soluble guanylate cyclase inhibitor and apocynin, a ROS production inhibitor, were also tested. Arteries and lung tissue were harvested for pathobiological evaluation. KEY FINDINGS: Chemerin contracted endothelium-denuded pulmonary artery, while no response was observed in arteries with endothelium. Chemerin potentiated phenylephrine-, endothelin-1- and serotonin-induced vasoconstriction, which was further enhanced by endothelium removal. Chemerin decreased acetylcholine-induced vasorelaxation in arteries with endothelium, while it did not affect SNP-induced relaxation. In presence of L-NAME, there remained a vasorelaxation in chemerin-pretreated arteries. Chemerin or ODQ alone partly decreased acetylcholine-induced vasorelaxation in pulmonary artery and thoracic aorta, while combined chemerin and ODQ incubation abolished it. Treatment with apocynin partly or totally reversed chemerin effects. In both types of arteries, chemerin reduced acetylcholine-induced NO production, as well as endothelial and inducible NO-synthase expression. SIGNIFICANCE: Chemerin potentiates vascular responses to vasoconstrictors in pulmonary artery and thoracic aorta and, impairs acetylcholine-induced pulmonary artery vasodilatation, by mechanisms involving at least partly NO signaling and oxidative stress.

Inflammation in Right Ventricular Failure: Does It Matter?

Right ventricular (RV) failure is a common consequence of acute and chronic RV overload of pressure, such as after pulmonary embolism and pulmonary hypertension. It has been recently realized that symptomatology and survival of patients with pulmonary hypertension are essentially determined by RV function adaptation to increased afterload. Therefore, improvement of RV function and reversal of RV failure are treatment goals. Currently, the pathophysiology and the pathobiology underlying RV failure remain largely unknown. A better understanding of the pathophysiological processes involved in RV failure is needed, as there is no proven treatment for this disease at the moment. The present review aims to summarize the current understanding of the pathogenesis of RV failure, focusing on inflammation. We attempt to formally emphasize the importance of inflammation and associated representative inflammatory molecules and cells in the primum movens and development of RV failure in humans and in experimental models. We present inflammatory biomarkers and immune mediators involved in RV failure. We focus on inflammatory mediators and cells which seem to correlate with the deterioration of RV function and also explain how all these inflammatory mediators and cells might impact RV function adaptation to increased afterload. Finally, we also discuss the evidence on potential beneficial effects of targeted anti-inflammatory agents in the setting of acute and chronic RV failure.