Expression of endothelin-1 system in a pig model of endotoxic shock

Endothelin System Blockade Extenuates Sepsis-Induced Acute Heart and Kidney Injuries via Modulating ET-1/Klotho/p38-MAPK

Sepsis-induced organ failure is a major health problem, characterised by massive inflammatory and oxidative stress responses. Endothelin-1 (ET-1) is one of the peptides expressed during septicemia with proapoptotic, proinflammatory, and oxidant effects. ET-1 plays a role in heart and kidney injuries in sepsis. Accordingly, the current study was conducted to investigate, on a mechanistic basis, whether inhibition of ET-1 signalling either by blocking its receptors or inhibiting its formation attenuates sepsis-induced acute cardiorenal injuries. To analyse the role of ET-1 in sepsis, we used a cecal ligation and puncture (CLP) model of sepsis. The animals were divided into five groups: CLP non-treated group, CLP-treated groups with bosentan, ambrisentan, and phosphoramidon (30, 5, and 0.5 mg/kg, respectively), and sham-operated group. In addition to the same set of groups, survival analysis was assigned Survival rate, histopathological assessment, and cardiorenal functions were analysed. Oxidant and antioxidant activities, ET-1, IL-6, and lactate were measured. The expression of TNF-α, p38, Klotho, and caspase-3 was evaluated by immunohistochemistry. CLP caused acute cardiorenal damage, high mortality, upregulated levels of ET-1, IL-6, and lactate, as well as an imbalance in oxidant/antioxidant activities, elevated expression of TNF-α, p38, caspase-3 and reduced expression of klotho. Bosentan, ambrisentan, or phosphoramidon improved survival, reduced the levels of inflammatory and oxidative stress parameters, improved cardiorenal functions and structure, elevated the tissue contents of GSH and SOD, raised the expression of klotho protein, and reduced the cardiorenal expression of p38, TNF-α and caspase-3. Endothelin receptor antagonists (ERAs); bosentan and ambrisentan, or endothelin converting enzyme inhibitor (ECE-i) phosphoramidon, are promising agents against sepsis-induced organ damage. This was evident in their cardiorenal protective effects, up-regulation of klotho, suppression of inflammation, oxidation, apoptosis, and enhancement of the antioxidant status.

Cord Blood Natural Killer Cells Inhibit Sepsis Caused by Feces-Induced Acute Peritonitis via Increasing Endothelium Integrity

Sepsis is associated with acute peritonitis, which can be induced by lipopolysaccharide exposure and feces. Generally, lipopolysaccharide induces mono-microbial peritonitis, whereas feces cause poly-microbial peritonitis; the latter is a more complicated and closer to the clinical diseases. Although several reports have discussed the mechanism of immune response in peritonitis-induced sepsis, however, the role of natural killer (NK) cells in sepsis, especially the relationship between NK cells and stabilization of the vascular endothelial barrier, is still unclear. Accordingly, in this study, we assessed the roles of NK cells in an acute sepsis model in mice. NK cells were injected via the tail vein into mice with acute sepsis, and nitric oxide (NO), anti-inflammatory cytokine, and angiogenic factors were tested to explore the effects of NK cells on sepsis. The survival rate of septic model mice infused with NK cells was significantly improved compared with the control group. Interestingly, the levels of NO, interleukin-10, and vascular endothelial growth factor (VEGF) decreased in NK cells therapy group. After the injection of NK cells, CD31 positive endothelial cells significantly increased in the kidneys and liver, although the expression of VEGF, ANGPT-1, and ET-1 was downregulated. Consistent with our hypothesis, the transfusion of NK cells into mice with sepsis blocked inflammation and increased endothelium integrity. Overall, these findings suggest that NK cells may block sepsis by modulating the VEGF pathway.

Endothelial Damage in Sepsis: The Importance of Systems Biology

The early diagnosis and appropriate stratification of sepsis continues to be one of the most important challenges in modern medicine. Single isolated biomarkers have not been enough to improve diagnostic and prognostic strategies and to progress toward therapeutic goals. The information generated by the human genome project has allowed a more holistic approach to the problem. The integration of genomics, transcriptomics, proteomics and metabolomics in sepsis has allowed us to progress in the knowledge of new pathways which are pathophysiologically involved in this disease. Thus, we have understood the importance of and complex interaction between the inflammatory response and the endothelium. Understanding the role of important parts of the microcirculation, such as the endothelial glycocalyx and its interaction with the inflammatory response, has provided early recognition elements for clinical practice that allow the rational use of traditional medical interventions in sepsis. This comprehensive approach, which differs from the classical mechanistic approach, uses systems biology to increase the diagnostic and prognostic spectrum of endothelial damage biomarkers in sepsis, and to provide information on new pathways involved in the pathophysiology of the disease. This, in turn, provides tools for perfecting traditional medical interventions, using them at the appropriate times according to the disease's pathophysiological context, while at the same time discovering new and improved therapeutic alternatives. We have the challenge of transferring this ideal scenario to our daily clinical practice to improve our patients' care. The purpose of this article is to provide a general description of the importance of systems biology in integrating the complex interaction between the endothelium and the inflammatory response in sepsis.

Severe COVID-19 Infection Associated with Endothelial Dysfunction Induces Multiple Organ Dysfunction: A Review of Therapeutic Interventions

Since December 2019, the SARS-CoV-2 (COVID-19) pandemic has transfixed the medical world. COVID-19 symptoms vary from mild to severe and underlying chronic conditions such as pulmonary/cardiovascular disease and diabetes induce excessive inflammatory responses to COVID-19 and these underlying chronic diseases are mediated by endothelial dysfunction. Acute respiratory distress syndrome (ARDS) is the most common cause of death in COVID-19 patients, but coagulation induced by excessive inflammation, thrombosis, and disseminated intravascular coagulation (DIC) also induce death by multiple-organ dysfunction syndrome. These associations imply that maintaining endothelial integrity is crucial for favorable prognoses with COVID-19 and therapeutic intervention to support this may be beneficial. Here, we summarize the extent of heart injuries, ischemic stroke and hemorrhage, acute kidney injury, and liver injury caused by immune-mediated endothelial dysfunction that result in the phenomenon of multi-organ dysfunction seen in COVID-19 patients. Moreover, the potential therapeutic effect of angiotensin receptor blockers and angiotensin-converting enzyme inhibitors that improve endothelial dysfunction as well as the bradykinin storm are discussed.

Targeting of G-protein coupled receptors in sepsis

The Third International Consensus Definitions (Sepsis-3) define sepsis as life-threatening multi-organ dysfunction caused by a dysregulated host response to infection. Sepsis can progress to septic shock-an even more lethal condition associated with profound circulatory, cellular and metabolic abnormalities. Septic shock remains a leading cause of death in intensive care units and carries a mortality of almost 25%. Despite significant advances in our understanding of the pathobiology of sepsis, therapeutic interventions have not translated into tangible differences in the overall outcome for patients. Clinical trials of antagonists of various pro-inflammatory mediators in sepsis have been largely unsuccessful in the past. Given the diverse physiologic roles played by G-protein coupled receptors (GPCR), modulation of GPCR signaling for the treatment of sepsis has also been explored. Traditional pharmacologic approaches have mainly focused on ligands targeting the extracellular domains of GPCR. However, novel techniques aimed at modulating GPCR intracellularly through aptamers, pepducins and intrabodies have opened a fresh avenue of therapeutic possibilities. In this review, we summarize the diverse roles played by various subfamilies of GPCR in the pathogenesis of sepsis and identify potential targets for pharmacotherapy through these novel approaches.

Ex vivo effect of vascular wall stromal cells secretome on enteric ganglia

BACKGROUND

Mesenchymal stromal cell (MSC)-based therapy is currently under study to treat inflammatory bowel diseases. MSC bioactive products could represent a valid alternative to overcome issues associated with systemic whole-cell therapies. However, MSC anti-inflammatory mechanisms differ between rodents and humans, impairing the reliability of preclinical models.

AIM

To evaluate the effect of conditioned medium (CM) derived from porcine vascular wall MSCs (pVW-MSCs) on survival and differentiation of porcine and guinea pig enteric ganglia exposed to lipopolysaccharide (LPS).

METHODS

Primary cultures of enteric ganglia were obtained by mechanic and enzymatic digestion of ileum resections from guinea pigs (Cavia porcellus) (GPEG) and pigs (Suus scrofa) (PEG). pVW-MSCs were derived by enzymatic digestion from vascular wall resections of porcine aorta and tested by immunoflowcytometry for MSC immune profile. Enteric ganglia were treated with increasing concentrations of LPS, CM derived by pVW-MSCs or a combination of CM and LPS 1 µg/mL. Cell count and morphometric analysis of HuD positive neurons and glial fibrillary acidic protein positive glial cells were performed by immunofluorecent staining of cultured ganglia.

RESULTS

PEG showed a higher number of neurons compared to GPEG. Overall, CM exerted a protective role on LPS-treated enteric ganglia. CM in combination with LPS increased the number of glial cells per ganglion in both cultures evoking glial cells differentiation in porcine cultures.

CONCLUSION

These findings suggest an immunomodulating activity of pVW-MSCs mediators on the enteric nervous system in inflammatory conditions.

Effects of Erdosteine in Experimental Sepsis Model in Rats

Objective

Erdosteine is a mucolytic agent that is known to possess antioxidant effects. This study investigated the effects of erdosteine on endothelin-1 (ET-1) levels and oxidative stress parameters superoxide dismutase (SOD) and malondialdehyde (MDA) in a rat sepsis model.

Methods

Four groups of Wistar albino rats (n=8 per group) were randomly allocated to the following groups: sham (group 1), sepsis (group 2), erdosteine control (group 3) and a sepsis group pretreated with erdosteine (group 4). Sepsis was induced using E. Coli ATCC 25922 inoculation. Serum ET-1, liver tissue SOD and MDA levels were determined in all groups.

Results

ET-1 levels were significantly higher in group 2 compared to groups 1, 3 and 4 (p<0.001, p=0.002 and p<0.001, respectively). Similarly, MDA levels in groups 1, 3 and 4 were significantly lower relative to group 2 (p<0.001, p=0.022 and p=0.010, respectively). Additionally, SOD activities in these same three groups were found to be significantly higher than those in group 2 (p<0.001, p=0.004 and p=0.028, respectively).

Conclusion

In conclusion, erdosteine decreases ET-1 levels and ameliorates oxidative stress parameters induced by sepsis in an experimental rat model of sepsis.

Mitochondria-meditated pathways of organ failure upon inflammation

Liver failure induced by systemic inflammatory response (SIRS) is often associated with mitochondrial dysfunction but the mechanism linking SIRS and mitochondria-mediated liver failure is still a matter of discussion. Current hypotheses suggest that causative events could be a drop in ATP synthesis, opening of mitochondrial permeability transition pore, specific changes in mitochondrial morphology, impaired Ca²⁺ uptake, generation of mitochondrial reactive oxygen species (mtROS), turnover of mitochondria and imbalance in electron supply to the respiratory chain. The aim of this review is to critically analyze existing hypotheses, in order to highlight the most promising research lines helping to prevent liver failure induced by SIRS. Evaluation of the literature shows that there is no consistent support that impaired Ca⁺⁺ metabolism, electron transport chain function and ultrastructure of mitochondria substantially contribute to liver failure. Moreover, our analysis suggests that the drop in ATP levels has protective rather than a deleterious character. Recent data suggest that the most critical mitochondrial event occurring upon SIRS is the release of mtROS in cytoplasm, which can activate two specific intracellular signaling cascades. The first is the mtROS-mediated activation of NADPH-oxidase in liver macrophages and endothelial cells; the second is the acceleration of the expression of inflammatory genes in hepatocytes. The signaling action of mtROS is strictly controlled in mitochondria at three points, (i) at the site of ROS generation at complex I, (ii) the site of mtROS release in cytoplasm via permeability transition pore, and (iii) interaction with specific kinases in cytoplasm. The systems controlling mtROS-signaling include pro- and anti-inflammatory mediators, nitric oxide, Ca²⁺ and NADPH-oxidase. Analysis of the literature suggests that further research should be focused on the impact of mtROS on organ failure induced by inflammation and simultaneously providing a new theoretical basis for a targeted therapy of overwhelmed inflammatory response.

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Relationship between mitochondrial dysfunction and high lethality upon sepsis.

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Criteria to define critical for lethality mitochondrial dysfunction.

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ATP, calcium, mitochondrial ultrastructure and apoptosis, upon inflammation.

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Regulation of inflammatory processes by mitochondrial ROS.

The biomedical piglet: establishing reference intervals for haematology and clinical chemistry parameters of two age groups with and without iron supplementation

Background

The similarities between swine and humans in physiological and genomic patterns, and the great correlation in size and anatomy, make pigs extremely useful in preclinical studies. New-born piglets can represent a model for congenital and genetic diseases in new-born children. It is known that piglets may have significant differences in clinicopathological results compared to adult pigs. Therefore, adult laboratory reference intervals cannot be applied to piglets. The aim of this study was to compare haematological and chemical variables in piglets of two ages and determinate age-related reference intervals for commercial hybrid young pigs.

Blood samples were collected under general anaesthesia from 130 animals divided into five- (P5) and 30- (P30) day-old piglets. Only P30 animals were treated with parenteral iron after birth. Samples were analysed using automated haematology (ADVIA 2120) and chemistry analysers, and age-related reference intervals were calculated.

Results

Significant higher values of RBC, Hb and HCT were observed in P30 animals when compared to P5, with an opposite trend for MCV. These results were associated with a reduction of the RBC regeneration process and the thrombopoietic response. The TSAT and TIBC were significantly higher in P30 compared to P5; however, piglets remained iron deficient compared to adult reference intervals reported previously.

Conclusions

In conclusion, this paper emphasises the high variability occurring in clinicopathological variables between new-born and 30-day-old pigs, and between piglets and adult pigs. This study provides valuable reference data for piglets at precise ages and could be used in the future as historical control improving the Reduction in animal experiments, as suggested by the 3Rs principle.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-017-0946-2) contains supplementary material, which is available to authorized users.

THE ENDOTHELIUM IN SEPSIS

Sepsis affects practically all aspects of endothelial cell (EC) function and is thought to be the key factor in the progression from sepsis to organ failure. Endothelial functions affected by sepsis include vasoregulation, barrier function, inflammation, and hemostasis. These are among other mechanisms often mediated by glycocalyx shedding, such as abnormal nitric oxide metabolism, up-regulation of reactive oxygen species generation due to down-regulation of endothelial-associated antioxidant defenses, transcellular communication, proteases, exposure of adhesion molecules, and activation of tissue factor. This review covers current insight in EC-associated hemostatic responses to sepsis and the EC response to inflammation. The endothelial cell lining is highly heterogeneous between different organ systems and consequently also in its response to sepsis. In this context, we discuss the response of the endothelial cell lining to sepsis in the kidney, liver, and lung. Finally, we discuss evidence as to whether the EC response to sepsis is adaptive or maladaptive. This study is a result of an Acute Dialysis Quality Initiative XIV Sepsis Workgroup meeting held in Bogota, Columbia, between October 12 and 15, 2014.

Landiolol hydrochloride ameliorates acute lung injury in a rat model of early sepsis through the suppression of elevated levels of pulmonary endothelin-1

Among the dysfunctions and pathologies associated with sepsis, the underlying molecular mechanisms of sepsis-induced acute lung injury (ALI) are poorly understood. Endothelin (ET)-1, a potent vasoconstrictor and pro-inflammatory peptide, is known to be involved in the pathogenesis of ALI in a rat model of sepsis. Here, we investigated whether landiolol hydrochloride, an ultra-short-acting β-blocker, plays a crucial role in ameliorating and attenuating LPS-induced ALI through modulation of the ET-1 system. Male Wistar rats at 8weeks of age were administered with either saline or lipopolysaccharide (LPS) for three hours (3h) and some of the LPS-administered rats were continuously treated with landiolol for 3h. ALI was induced by LPS, including levels of both circulatory and pulmonary TNF-α and IL-6 but [PaO₂] was significantly decreased. LPS also induced a significant increase in levels of pulmonary ET-1 and ET-A receptor, but levels of ET-B receptor, which has vasodilating effects, were remarkably diminished. Further, LPS administration upregulated the pulmonary expression of HIF-1α. Finally, the treatment of LPS-administered rats with landiolol for 3h ameliorated and prevented ALI, normalized the altered levels of pulmonary ET-1 and ET-A receptors. Landiolol also induced significant down-regulation of ET-B receptor in lung tissues in the early hours (phase) of sepsis. However, Landiolol treatment had no effect on the up-regulated inflammatory mediators (TNF-α, IL-6) in both plasma and lung tissues during sepsis, and expression of pulmonary HIF-1α also remained unchanged after landiolol treatment. Collectively, these data led us to conclude that landiolol may ameliorate sepsis-induced ALI via the pulmonary ET system.

Deleterious effects of tributyltin on porcine vascular stem cells physiology

The vascular functional and structural integrity is essential for the maintenance of the whole organism and it has been demonstrated that different types of vascular progenitor cells resident in the vessel wall play an important role in this process. The purpose of the present research was to observe the effect of tributyltin (TBT), a risk factor for vascular disorders, on porcine Aortic Vascular Precursor Cells (pAVPCs) in term of cytotoxicity, gene expression profile, functionality and differentiation potential. We have demonstrated that pAVPCs morphology deeply changed following TBT treatment. After 48h a cytotoxic effect has been detected and Annexin binding assay demonstrated that TBT induced apoptosis. The transcriptional profile of characteristic pericyte markers has been altered: TBT 10nM substantially induced alpha-SMA, while, TBT 500nM determined a significant reduction of all pericyte markers. IL-6 protein detected in the medium of pAVPCs treated with TBT at both doses studied and with a dose response. TBT has interfered with normal pAVPC functionality preventing their ability to support a capillary-like network. In addition TBT has determined an increase of pAVPC adipogenic differentiation. In conclusion in the present paper we have demonstrated that TBT alters the vascular stem cells in terms of structure, functionality and differentiating capability, therefore effects of TBT in blood should be deeply explored to understand the potential vascular risk associated with the alteration of vascular stem cell physiology.

Effect of tributyltin on mammalian endothelial cell integrity

Tributyltin (TBT), is a man-made pollutants, known to accumulate along the food chain, acting as an endocrine disruptor in marine organisms, with toxic and adverse effects in many tissues including vascular system. Based on the absence of specific studies of TBT effects on endothelial cells, we aimed to evaluate the toxicity of TBT on primary culture of porcine aortic endothelial cells (pAECs), pig being an excellent model to study human cardiovascular disease. pAECs were exposed for 24h to TBT (100, 250, 500, 750 and 1000nM) showing a dose dependent decrease in cell viability through both apoptosis and necrosis. Moreover the ability of TBT (100 and 500nM) to influence endothelial gene expression was investigated at 1, 7 and 15h of treatment. Gene expression of tight junction molecules, occludin (OCLN) and tight junction protein-1 (ZO-1) was reduced while monocyte adhesion and adhesion molecules ICAM-1 and VCAM-1 (intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) levels increased significantly at 1h. IL-6 and estrogen receptors 1 and 2 (ESR-1 and ESR-2) mRNAs, after a transient decrease, reached the maximum levels after 15h of exposure. Finally, we demonstrated that TBT altered endothelial functionality greatly increasing monocyte adhesion. These findings indicate that TBT deeply alters endothelial profile, disrupting their structure and interfering with their ability to interact with molecules and other cells.

Adaptations of the endothelin system after exercise training in a porcine model of ischemic heart disease

OBJECTIVE

To the test the hypothesis that exercise training would increase endothelin-mediated vasoconstriction in collateral-dependent arteries via enhanced contribution of ET(A).

METHODS

An ameroid constrictor was surgically placed around the proximal LCX artery to induce gradual occlusion in Yucatan miniature swine. Eight weeks postoperatively, pigs were randomized into sedentary or exercise-training (treadmill; 5 days/week; 14 weeks) groups. Subsequently, arteries (~150 μm diameter) were isolated from collateral-dependent and nonoccluded myocardial regions and studied.

RESULTS

Following exercise training, ET-1-mediated contraction was significantly enhanced in collateral-dependent arteries. Exercise training induced a disproportionate increase in the ET(A) contribution to the ET-1 contractile response in collateral-dependent arteries, with negligible contributions by ET(B). In collateral-dependent arteries of sedentary pigs, inhibition of ET(A) or ET(B) did not significantly alter ET-1 contractile responses in collateral-dependent arteries, suggesting compensation by the functionally active receptor. These adaptations occurred without significant changes in ET(A), ET(B), or ECE mRNA levels but with significant exercise-training-induced elevations in endothelin levels in both nonoccluded and collateral-dependent myocardial regions.

CONCLUSIONS

Taken together, these data reveal differential adaptive responses in collateral-dependent arteries based upon physical activity level. ET(A) and ET(B) appear to compensate for one another to maintain contraction in sedentary pigs, whereas exercise-training favors enhanced contribution of ET(A).

Endotoxemia Induces IκBβ/NF-κB-Dependent Endothelin-1 Expression in Hepatic Macrophages

Elevated serum concentrations of the vasoactive protein endothelin-1 (ET-1) occur in the setting of systemic inflammatory response syndrome and contribute to distal organ hypoperfusion and pulmonary hypertension. Thus, understanding the cellular source and transcriptional regulation of systemic inflammatory stress-induced ET-1 expression may reveal therapeutic targets. Using a murine model of LPS-induced septic shock, we demonstrate that the hepatic macrophage is the primary source of elevated circulating ET-1, rather than the endothelium as previously proposed. Using pharmacologic inhibitors, ET-1 promoter luciferase assays, and by silencing and overexpressing NF-κB inhibitory protein IκB expression, we demonstrate that LPS-induced ET-1 expression occurs via an NF-κB-dependent pathway. Finally, the specific role of the cRel/p65 inhibitory protein IκBβ was evaluated. Although cytoplasmic IκBβ inhibits activity of cRel-containing NF-κB dimers, nuclear IκBβ stabilizes NF-κB/DNA binding and enhances gene expression. Using targeted pharmacologic therapies to specifically prevent IκBβ/NF-κB signaling, as well as mice genetically modified to overexpress IκBβ, we show that nuclear IκBβ is both necessary and sufficient to drive LPS-induced ET-1 expression. Together, these results mechanistically link the innate immune response mediated by IκBβ/NF-κB to ET-1 expression and potentially reveal therapeutic targets for patients with Gram-negative septic shock.

In vitro differentiation of porcine aortic vascular precursor cells to endothelial and vascular smooth muscle cells

Recent findings suggest that progenitor and multipotent mesenchymal stromal cells (MSCs) are associated with vascular niches. Cells displaying mesenchymal properties and differentiating to whole components of a functional blood vessel, including endothelial and smooth muscle cells, can be defined as vascular stem cells (VSCs). Recently, we isolated a population of porcine aortic vascular precursor cells (pAVPCs), which have MSC- and pericyte-like properties. The aim of the present work was to investigate whether pAVPCs possess VSC-like properties and assess their differentiation potential toward endothelial and smooth muscle lineages. pAVPCs, maintained in a specific pericyte growth medium, were cultured in high-glucose DMEM + 10% FBS (long-term medium, LTM) or in human endothelial serum-free medium + 5% FBS and 50 ng/ml of hVEGF (endothelial differentiation medium, EDM). After 21 days of culture in LTM, pAVPCs showed an elongated fibroblast-like morphology, and they seem to organize in cord-like structures. qPCR analysis of smooth muscle markers [α-smooth muscle actin (α-SMA), calponin, and smooth muscle myosin (SMM) heavy chain] showed a significant increment of the transcripts, and immunofluorescence analysis confirmed the presence of α-SMA and SMM proteins. After 21 days of culture in EDM, pAVPCs displayed an endothelial cell-like morphology and revealed the upregulation of the expression of endothelial markers (CD31, vascular endothelial-cadherin, von Willebrand factor, and endothelial nitric oxide synthase) showing the CD31-typical pattern. In conclusion, pAVPCs could be defined as a VSC-like population considering that, if they are maintained in a specific pericyte medium, they express MSC markers, and they have, in addition to the classical mesenchymal trilineage differentiation potential, the capacity to differentiate in vitro toward the smooth muscle and the endothelial cell phenotypes.

Value of caffeic acid phenethyl ester pretreatment in experimental sepsis model in rats

Background and Aim. The aim of this study was to determine the actions of caffeic acid phenethyl ester (CAPE) on the changes of endothelin-1 (ET-1) level, tumor necrosis factor- (TNF-) alpha, and oxidative stress parameters such as superoxide dismutase (SOD) activities and malondialdehyde (MDA) levels in experimental sepsis model in rats. Materials and Methods. Twenty-four rats were randomly divided into three experimental groups: sham (group 1), sepsis (group 2), and sepsis + CAPE (group 3), n = 8 each. CAPE was administered (10 µmol/kg) intraperitoneally to group 3 before sepsis induction. Serum ET-1, serum TNF-alpha, tissue SOD activity, and tissue MDA levels were measured in all groups. Results. Pretreatment with CAPE decreased ET-1, TNF-alpha, and MDA levels in sepsis induced rats. Additionally SOD activities were higher in rats pretreated with CAPE after sepsis induction. Conclusion. Our results demonstrate that CAPE may have a beneficial effect on ET and TNF-alpha levels and oxidative stress parameters induced by sepsis in experimental rat models. Therefore treatment with CAPE can be used to avoid devastating effects of sepsis.

Inhibition of sphingosine kinase prevents lipopolysaccharide-induced preterm birth and suppresses proinflammatory responses in a murine model

Premature delivery occurs in 12% of all births, and accounts for nearly half of long-term neurological morbidity, and 60% to 80% of perinatal mortality. Despite advances in obstetrics and neonatology, the rate of premature delivery has increased approximately 12% since 1990. The single most common cause of spontaneous preterm birth is infection. Several lines of evidence have demonstrated the role of endothelin-1 as both a constrictor of uterine myometrial smooth muscle and a proinflammatory mediator. Endothelin-1 activates the phospholipase C pathway, leading to activation of protein kinase C and, in turn, sphingosine kinase (SphK). The inhibition of SphK has been recently shown to control the proinflammatory response associated with sepsis. We show herein, for the first time, that SphK inhibition prevents inflammation-associated preterm birth in a murine model. Rescue of pups from premature abortion with an SphK inhibitor occurs by suppression of the proinflammatory cytokines tumor necrosis factor α, Il-1β, and Il-6 and attenuation of polymorphonuclear inflammatory cells into the placental labyrinth. Moreover, we postulate that inhibition of SphK leads to suppression of endothelin-converting enzyme-1 expression, indicating the presence of an endothelin-converting enzyme 1/endothelin 1-SphK positive feedback loop. This work introduces a novel approach for the control of infection-triggered preterm labor, a condition for which there is no effective treatment.

No redistribution of lung blood flow by inhaled nitric oxide in endotoxemic piglets pretreated with an endothelin receptor antagonist

Inhaled nitric oxide (INO) improves ventilation-perfusion matching and alleviates pulmonary hypertension in patients with acute respiratory distress syndrome. However, outcome has not yet been shown to improve, and nonresponse is common. A better understanding of the mechanisms by which INO acts may guide in improving treatment with INO in patients with severe respiratory failure. We hypothesized that INO may act not only by vasodilation in ventilated lung regions, but also by causing vasoconstriction via endothelin (ET-1) in atelectatic, nonventilated lung regions. This was studied in 30 anesthetized, mechanically ventilated piglets. The fall in oxygenation and rise in pulmonary artery pressure during a sepsislike condition (infusion of endotoxin) were blunted by INO 40 ppm. Endotoxin infusion increased serum ET-1, and INO almost doubled the ratio between mRNA expression of endothelin receptor A (mediating vasoconstriction) and B (mediating vasodilation and clearance of ET-1) (ET-A/ET-B) in atelectatic lung regions. INO caused a shift in blood flow away from atelectatic lung regions in the endotoxemic piglets, but not during ET receptor antagonism. We conclude that INO in short-term experiments, in addition to causing selective pulmonary vasodilation in ventilated lung regions, increases the ET-A/ET-B mRNA expression ratio in lung tissue. This might augment the vasoconstriction in atelectatic lung regions, enhancing the redistribution of pulmonary blood flow to ventilated lung regions which are reached by INO. Such vasoconstriction may be an important additional factor explaining the effect of INO.

The role of endothelin-1 and endothelin receptor antagonists in inflammatory response and sepsis

Endothelin-1 (ET-1) is a potent endogenous vasoconstrictor, mainly secreted by endothelial cells. It acts through two types of receptors: ETA and ETB. Apart from a vasoconstrictive action, ET-1 causes fibrosis of the vascular cells and stimulates production of reactive oxygen species. It is claimed that ET-1 induces proinflammatory mechanisms, increasing superoxide anion production and cytokine secretion. A recent study has shown that ET-1 is involved in the activation of transcription factors such as NF-κB and expression of proinflammatory cytokines including TNF-α, IL-1, and IL-6. It has been also indicated that during endotoxaemia, the plasma level of ET-1 is increased in various animal species. Some authors indicate a clear correlation between endothelin plasma level and morbidity/mortality rate in septic patients. These pathological effects of ET-1 may be abrogated at least partly by endothelin receptor blockade. ET-1 receptor antagonists may be useful for prevention of various vascular diseases. This review summarises the current knowledge regarding endothelin receptor antagonists and the role of ET-1 in sepsis and inflammation.

Use of insulin to decrease septic shock-induced myocardial depression in a porcine model

Insulin is known to attenuate septic shock-induced myocardial depression. Possible mechanisms include an anti-inflammatory or inotropic effect of insulin. The objective of this study was to determine whether the mechanism of action of insulin in attenuating septic shock-induced myocardial depression is through an immunomodulatory effect. Fourteen pigs were assigned to one of two groups. Both groups received a 4-h infusion of lipopolysaccharide endotoxin from Escherichia coli 0111:B4. Group 2 additionally received insulin at 1.5 U/kg/h with infusions of D50 normal saline and KCl to maintain normal serum glucose and potassium levels. Cardiac function was measured with shortening fraction using transthoracic echocardiogram. Plasma TNF-α, IL-1β, and IL-6 levels were obtained every 30 min. Postmortem cytokine analysis and histomorphology were performed on the heart tissue. Although insulin attenuated septic shock-induced myocardial depression, this was not due to an anti-inflammatory effect and, therefore, likely resulted from an inotropic effect of insulin.

Cells derived from porcine aorta tunica media show mesenchymal stromal-like cell properties in in vitro culture

Several studies have already described the presence of specialized niches of precursor cells in vasculature wall, and it has been shown that these populations share several features with mesenchymal stromal cells (MSCs). Considering the relevance of MSCs in the cardiovascular physiopathology and regenerative medicine, and the usefulness of the pig animal model in this field, we reported a new method for MSC-like cell isolation from pig aorta. Filling the vessel with a collagenase solution for 40 min, all endothelial cells were detached and discarded and then collagenase treatment was repeated for 4 h to digest approximately one-third of the tunica media. The ability of our method to select a population of MSC-like cells from tunica media could be ascribed in part to the elimination of contaminant cells from the intimal layer and in part to the overnight culture in the high antibiotic/antimycotic condition and to the starvation step. Aortic-derived cells show an elongated, spindle shape, fibroblast-like morphology, as reported for MSCs, stain positively for CD44, CD56, CD90, and CD105; stain negatively for CD34 and CD45; and express CD73 mRNA. Moreover, these cells show the classical mesenchymal trilineage differentiation potential. Under our in vitro culture conditions, aortic-derived cells share some phenotypical features with pericytes and are able to take part in the formation of network-like structures if cocultured with human umbilical vein endothelial cells. In conclusion, our work reports a simple and highly suitable method for obtaining large numbers of precursor MSC-like cells derived from the porcine aortic wall.

Therapeutic hypothermia activates the endothelin and nitric oxide systems after cardiac arrest in a pig model of cardiopulmonary resuscitation

Post-cardiac arrest myocardial dysfunction is a major cause of mortality in patients receiving successful cardiopulmonary resuscitation (CPR). Mild therapeutic hypothermia (MTH) is the recommended treatment after resuscitation from cardiac arrest (CA) and is known to exert neuroprotective effects and improve short-term survival. Yet its cytoprotective mechanisms are not fully understood. In this study, our aim was to determine the possible effect of MTH on vasoactive mediators belonging to the endothelin/nitric oxide axis in our porcine model of CA and CPR. Pigs underwent either untreated CA or CA with subsequent CPR. After state-of-the-art resuscitation, the animals were either left untreated, cooled between 32–34°C after ROSC or treated with a bolus injection of S-PBN (sodium 4-[(tert-butylimino) methyl]benzene-3-sulfonate N-oxide) until 180 min after ROSC, respectively. The expression of endothelin 1 (ET-1), endothelin converting enzyme 1 (ECE-1), and endothelin A and B receptors (ETAR and ETBR) transcripts were measured using quantitative real-time PCR while protein levels for the ETAR, ETBR and nitric oxide synthases (NOS) were assessed using immunohistochemistry and Western Blot. Our results indicated that the endothelin system was not upregulated at 30, 60 and 180 min after ROSC in untreated postcardiac arrest syndrome. Post-resuscitative 3 hour-long treatments either with MTH or S-PBN stimulated ET-1, ECE-1, ETAR and ETBR as well as neuronal NOS and endothelial NOS in left ventricular cardiomyocytes. Our data suggests that the endothelin and nitric oxide pathways are activated by MTH in the heart.

Procalcitonin gene expression after LPS stimulation in the porcine animal model

Procalcitonin (PCT), recognised as a marker of sepsis, was investigated in a porcine model of endotoxic shock. The results showed that continuous IV infusion (1-4 h) of LPS (40 μg/kg) in pigs was able to induce a generalised increase of PCT expression in lung, heart, kidney and liver. The increase in PCT was significant only in kidney and was accompanied by an increase in IL-6 gene expression. In vitro results demonstrated that peripheral blood mononuclear cells (PBMCs), as well as endothelial cells, were potentially capable of contributing to in vivo extrathyroidal PCT production. These findings support previous data from pigs concerning the occurrence of widespread activation of PCT extrathyroidal gene expression during endotoxic shock in pigs. Nevertheless, the levels of PCT detected were very low, suggesting the need for additional studies to validate the pig as a reliable animal model for investigating the role of PCT in sepsis.

Constriction of rat extra-splenic veins to lipopolysaccharide involves endothelin-1

The spleen has an important role in blood volume regulation and increased resistance of post-capillary hilar veins (in mesentery adjoining the spleen) can regulate this. This study investigated whether venular constriction to lipopolysaccharide (LPS) involved endothelin-1 (ET-1). Pressure myography was used to study isolated extra-splenic (hilar) vessels from male Wistar rats (n = 111). Arteries and veins were treated with LPS (50 microg ml(-1)) for 4 h. Extra-splenic veins constricted to LPS (p < 0.05), but there was no effect on arteries. Denudation did not abolish venular constriction to LPS, indicating an endothelial independent mechanism. However, the dual ET-1 receptor antagonist bosentan (10(-5) M) and specific ET(A) and ET(B) antagonists ABT-627 (atrasentan, 6.3 x 10(-6) M) and A-192621(1.45 x 10(-6) M) completely abolished constriction of LPS-treated veins. ET-1 alone also constricted the extra-splenic arteries and veins (p < 0.05), with a greater response observed in veins (p < 0.05). ELISA also confirmed that serum and spleen levels of ET-1 increased in response to LPS (p < 0.05). That LPS-induced constriction of extra-splenic veins is mediated by ET-1. Greater constriction of post- versus pre-capillary extra-splenic vessels to LPS would result in increased intra-splenic fluid extravasation and hypovolaemia in vivo.

The hepatic microcirculation: mechanistic contributions and therapeutic targets in liver injury and repair

The complex functions of the liver in biosynthesis, metabolism, clearance, and host defense are tightly dependent on an adequate microcirculation. To guarantee hepatic homeostasis, this requires not only a sufficient nutritive perfusion and oxygen supply, but also a balanced vasomotor control and an appropriate cell-cell communication. Deteriorations of the hepatic homeostasis, as observed in ischemia/reperfusion, cold preservation and transplantation, septic organ failure, and hepatic resection-induced hyperperfusion, are associated with a high morbidity and mortality. During the last two decades, experimental studies have demonstrated that microcirculatory disorders are determinants for organ failure in these disease states. Disorders include 1) a dysregulation of the vasomotor control with a deterioration of the endothelin-nitric oxide balance, an arterial and sinusoidal constriction, and a shutdown of the microcirculation as well as 2) an overwhelming inflammatory response with microvascular leukocyte accumulation, platelet adherence, and Kupffer cell activation. Within the sequelae of events, proinflammatory mediators, such as reactive oxygen species and tumor necrosis factor-alpha, are the key players, causing the microvascular dysfunction and perfusion failure. This review covers the morphological and functional characterization of the hepatic microcirculation, the mechanistic contributions in surgical disease states, and the therapeutic targets to attenuate tissue injury and organ dysfunction. It also indicates future directions to translate the knowledge achieved from experimental studies into clinical practice. By this, the use of the recently introduced techniques to monitor the hepatic microcirculation in humans, such as near-infrared spectroscopy or orthogonal polarized spectral imaging, may allow an early initiation of treatment, which should benefit the final outcome of these critically ill patients.

Acute subepicardial infarction associated with severe septic shock--insight in myocardial perfusion

Isolated infarctions of the subepicardial myocardium without changes in subendocardium are extremely rare. We present an autoptic case with an acute subepicardial infarction of the right- and left-ventricular myocardium. A 53-year-old male was admitted to hospital with acute upper abdominal pain. Clinical examination revealed an acute infero-lateral myocardial infarction. The patient succumbed to acute heart failure a few hours later. Autopsy revealed numerous pulmonary abscesses due to suppurative lobular pneumonia with consecutive pericardial effusion. Furthermore, we diagnosed an acute myocardial infarct encompassing the entire right and left ventricles but limited to the subepicardial myocardium only. Microscopically, we observed fibrin microemboli in the subepicardial microvessels. The existence of an isolated subepicardial myocardial infarct challenges our understanding of myocardial perfusion.

Voltage-independent calcium channels mediate lipopolysaccharide-induced hyporeactivity to endothelin-1 in the rat aorta

The roles of intracellular calcium concentration ([Ca(2+)](i)) and Ca(2+) sensitization in lipopolysaccharide (LPS)-induced vascular smooth muscle (VSM) hyporesponsiveness are incompletely understood. To investigate these roles, contraction responses to endothelin-1 (ET-1) and 80 mM KCl; relaxation responses to nifedipine; the expression levels of mRNAs of ET-1 and its receptors (ET(A) or ET(B)); the expression levels of protein kinase C (PKC) and phosphorylation of Rho kinase (ROKalpha), CPI-17, and myosin phosphatase target subunit-1 (MYPT1); and changes in aortic VSM cell [Ca(2+)](i) were measured in LPS-treated aortic rings from male Wistar rats (250-300 g). LPS (10 mug/ml, 20 h) decreased contraction induced by ET-1 (0.3-100 nM) or 80 mM KCl. LPS-induced hypocontractility was not observed in the absence of external Ca(2+), but LPS-treated aorta remained hypocontractile on subsequent stepwise restoration of extracellular Ca(2+) (0.01-10 mM). Vascular relaxation to nifedipine; mRNA expression levels of ET-1, ET(A), or ET(B); protein expression levels of PKC; and phosphorylation levels of ROKalpha, CPI-17, and MYPT1 were not affected by LPS. In isolated aortic VSM cells, ET-1 caused a transient initial increase in [Ca(2+)](i), followed by a maintained tonic increase in [Ca(2+)](i), which was decreased by LPS pretreatment and was dependent on external Ca(2+). Subsequent restoration of extracellular Ca(2+) increased [Ca(2+)](i), but this increase was lower in the LPS-treated group. This difference in response to extracellular Ca(2+) addition was not affected by diltiazem, but was abolished by SKF-96365. Therefore, LPS induces hyporeactivity to ET-1 in rat aorta that depends on external Ca(2+) influx through non-voltage-operated Ca(2+) channels, but not on ET-1 receptor expression or Ca(2+) sensitization.

Endothelin-1 potentiates smoke-induced acute lung inflammation

The current study examined the role of endothelin-1 (ET-1) in mediating acute lung inflammation induced by short-term cigarette smoke exposure. Hamsters received intraperitoneal injections of ET-1, followed by a 2-hour period of smoke exposure, for 3 consecutive days. The lungs were then evaluated for inflammatory changes, using the following parameters: (1) lung histopathology, (2) neutrophil content of bronchoalveolar lavage fluid (BALF), (3) percent tumor necrosis factor receptor 1 (TNFR1)-labeled BALF macrophages, and (4) alveolar septal cell apoptosis. Results indicate that ET-1 significantly amplified the effect of smoke on each of these inflammatory markers and that these responses could be blocked by pretreatment with a novel endothelin receptor A antagonist, HJP272. In particular, exogenous ET-1 induced a marked increase in BALF neutrophils, consistent with a role for this mediator as an inflammatory cell "gatekeeper."

Preferential recruitment of neutrophils by endothelin-1 in acute lung inflammation induced by lipopolysaccharide or cigarette smoke

This study examined the role of endothelin-1 (ET-1) in recruiting inflammatory cells to the lung after induction of injury with either lipopolysaccharide (LPS) or cigarette smoke. Hamsters injected with either ET-1 or its precursor peptide (Big ET-1) prior to treatment with LPS or cigarette smoke had markedly increased concentrations of neutrophils in bronchoalveolar lavage fluid (BALF) despite a reduction in total numbers of BALF leukocytes. Furthermore, the effect of ET-1 on smoke-exposed animals was reversed by addition of an endothelin-A receptor antagonist. These results are consistent with preferential recruitment of neutrophils by ET-1, and suggest that inhibition of this proinflammatory mediator may decrease acute pulmonary inflammation associated with cigarette smoke and other pulmonary toxins.

LPS abolishes extrasplenic vasoconstriction to atrial natriuretic peptide: the role of NO and endothelin 1

Sepsis causes changes in vascular resistance and hypovolemia. Previous studies have demonstrated that the spleen regulates blood volume via atrial natiuretic peptide (ANP). We hypothesized that LPS alters extrasplenic responses to ANP via endothelial-dependent mechanisms and studied the role of NO and endothelin 1 (ET-1). Isolated extrasplenic arteries and veins (vessels in mesentery adjoining spleen) were obtained from male Wistar rats weighing 200 to 280 g (n = 102) and mounted on a pressure myograph to determine intraluminal diameter for 4 h. Isolated vessels constricted in response to the half-maximum response of ANP (veins, 30% +/- 1.7%; arteries, 34.5 +/- 1.7%; P < 0.05), and this was abolished by the NO donor S-nitroso-N-acetylpenicillamine (SNAP 75 microM). Arteries and veins incubated with LPS (50 microg mL(-1) for 4 h) were unresponsive to ANP, and constriction was not restored by the NOS inhibitor N omega-nitro-L-arginine methyl ester (L-NAME 100 microM). However, venular constriction returned in the presence of the ET-1 antagonist Bosentan, increasing from -1.5 +/- 1.2 (10 min) to -10 +/- 2.5% (4 h) with LPS + Bosentan (3 x 10(-6) M) compared with -2.3 +/- 1.2 and 0% with LPS alone. In conclusion, LPS abolished endothelial-dependent extrasplenic venular constriction to ANP partially due to increased ET-1, whereas NO seemed to modulate vascular responses to ANP.

Phosphoramidon, an endothelin-converting enzyme inhibitor, attenuates lipopolysaccharide-induced acute lung injury

Phosphoramidon blocks the formation of endothelin-1 (ET-1), a proinflammatory mediator implicated in the pathogenesis of a variety of lung diseases. To determine whether phosphoramidon can ameliorate pulmonary inflammation, our laboratory undertook a series of experiments involving treatment of hamsters with either intraperitoneal (i.p.) or aerosolized phosphoramidon prior to induction of acute lung injury by intratracheal administration of lipopolysaccharide (LPS). The results indicate that phosphoramidon significantly reduces LPS-induced pulmonary inflammation as measured by lung histology, neutrophil content of bronchoalveolar lavage (BAL) fluid, percent tumor necrosis factor receptor 1 (TNFR1)-labeled BAL macrophages, and alveolar septal cell apoptosis. In additional experiments, i.p. administration of a novel endothelin A receptor anatgonist (HJP272) similarly decreased BAL neutrophils, whereas i.p. administration of either ET-1, or its precursor peptide, "big" ET-1, had the opposite effect. These findings support further evaluation of phosphoramidon and other ET-1 suppressors as potential treatments for human inflammatory lung disease.