The biosynthesis of endothelin-1 by human polymorphonuclear leukocytes

Association between Plasma Big Endothelin-1 Level and The Severity of Coronary Artery Disease in Patients with Non-ST Segment-Elevated Myocardial Infarction

BACKGROUND

Early risk stratification with simple biomarkers is essential in patients with non-ST segment-elevation myocardial infarction (NSTEMI).

OBJECTIVE

This study aimed to evaluate the association between plasma big endothelin-1 (ET-1) level and the SYNTAX score (SS) in patients with NSTEMI.

METHODS

A total of 766 patients with NSTEMI undergoing coronary angiography were recruited. Patients were divided into three groups: low SS (≤22), intermediate SS (23-32), and high SS (>32). Spearman correlation, smooth curve fitting, logistic regression, and receiver operating characteristic (ROC) curve analysis were performed to evaluate the association between plasma big ET-1 level and the SS. A p-value <0.05 was considered statistically significant.

RESULTS

There was a significant correlation between the big ET-1 and the SS (r=0.378, p<0.001). The smoothing curve indicated a positive correlation between the plasma big ET-1 level and the SS. The ROC curve analysis showed that the area under the curve was 0.695 (0.661-0.727) and the optimal cutoff of plasma big ET-1 level was 0.35pmol/l. Logistic regression showed that elevated big ET-1 was an independent predictor of intermediate-high SS in patients with NSTEMI, whether entered as a continuous variable [OR (95% CI): 1.110 (1.053-1.170), p<0.001] or as a categorical variable [OR (95% CI): 2.962 (2.073-4.233), p<0.001].

CONCLUSION

In patients with NSTEMI, the plasma big ET-1 level was significantly correlated with the SS. Elevated plasma big ET-1 level was an independent predictor for intermediate-high SS.

Plasma Big Endothelin-1 Levels and Long-Term Outcomes in Patients With Atrial Fibrillation and Acute Coronary Syndrome or Undergoing Percutaneous Coronary Intervention

Background

This study aimed to evaluate the association between plasma big ET-1 levels and long-term outcomes in patients with atrial fibrillation (AF) and acute coronary syndrome (ACS) or undergoing percutaneous coronary intervention (PCI).

Methods

A total of 930 patients were enrolled and followed up for a median duration of 2.3 years. According to the optimal cutoff of big ET-1 for predicting all-cause death, these patients were divided into two groups. The primary endpoints were all-cause death and net adverse clinical events (NACE). The secondary endpoints included cardiovascular death, major adverse cardiovascular events (MACE), BARC class ≥ 3 bleeding, and BARC class ≥ 2 bleeding. Cox regressions were performed to evaluate the association between big ET-1 and outcomes.

Results

Based on the optimal cutoff of 0.54 pmol/l, 309 patients (33.2%) had high big ET-1 levels at baseline. Compared to the low big ET-1 group, patients in the high big ET-1 group tended to have more comorbidities, impaired cardiac function, elevated inflammatory levels, and worse prognosis. Univariable and multivariable Cox regressions indicated that big ET-1 ≥ 0.54 pmol/l was associated with increased incidences of all-cause death [HR (95%CI):1.73 (1.10–2.71), p = 0.018], NACE [HR (95%CI):1.63 (1.23–2.16), p = 0.001], cardiovascular death [HR (95%CI):1.72 (1.01–2.92), p = 0.046], MACE [HR (95%CI):1.60 (1.19–2.16), p = 0.002], BARC class ≥ 3 [HR (95%CI):2.21 (1.16–4.22), p = 0.016], and BARC class ≥ 2 bleeding [HR (95%CI):1.91 (1.36–2.70), p < 0.001]. Subgroup analysis indicated consistent relationships between the big ET-1 ≥ 0.54 pmol/l and the primary endpoints.

Conclusion

Elevated plasma big ET-1 levels were independently associated with increased risk of all-cause death, NACE, cardiovascular death, MACE, BARC class ≥ 3 bleeding, and BARC class ≥ 2 bleeding in patients with AF and ACS or undergoing PCI.

Assessment of vascular function in complete glycaemic spectrum

Purpose: The present study was conceived to delineate the point of vascular dysfunction along the glycemic spectrum (normoglycemic individuals with no family history of diabetes, normoglycemic individuals with family history of diabetes, prediabetic individuals, and diabetic individuals).Materials and Methods: In this cross-sectional comparative study, we enrolled 252 participants of both gender in the age group of 30-50 years. They were classified based on their family history of diabetes and glycemic status into four groups along the glycemic spectrum as mentioned above. We measured flow-mediated dilation (FMD) from brachial artery and vascular function biomarkers such as enthothelin-1 (ET-1), von Willbrand Factor (vWF), Vascular Endothelial Growth Factor (VEGF) to assess the vascular function. The comparison of data between groups were done using One Way ANOVA/Kruskal-Wallis followed by post-hoc analysis using LSD/Mann-Whitney U Test depending on the normality of the data. Spearman correlation was done between vascular function and plasma glucose levels to identify its relationship. Linear regression was carried out to identify the factors influencing the FMD across the glycemic spectrum.Results: We observed that vascular function negatively correlated with blood glucose levels. However, endothelin-1 and vWF derangement was there even in normoglycemic first degree relatives of diabetes (FDRD) and the derangement increased in prediabetes and diabetes. Physiological dysfunction in terms of decreased flow-mediated dilation starts from prediabetes only. VEGF derangement is found only in diabetic individuals.Conclusion: Vascular dysfunction is found even in normoglycemic FDRD and the derangement increased and compounded with the advancement of disease.

Immune Dysfunction in Uremia 2020

Cardiovascular disease and infections are major causes for the high incidence of morbidity and mortality of patients with chronic kidney disease. Both complications are directly or indirectly associated with disturbed functions or altered apoptotic rates of polymorphonuclear leukocytes, monocytes, lymphocytes, and dendritic cells. Normal responses of immune cells can be reduced, leading to infectious diseases or pre-activated/primed, giving rise to inflammation and subsequently to cardiovascular disease. This review summarizes the impact of kidney dysfunction on the immune system. Renal failure results in disturbed renal metabolic activities with reduced renin, erythropoietin, and vitamin D production, which adversely affects the immune system. Decreased kidney function also leads to reduced glomerular filtration and the retention of uremic toxins. A large number of uremic toxins with detrimental effects on immune cells have been identified. Besides small water-soluble and protein-bound compounds originating from the intestinal microbiome, several molecules in the middle molecular range, e.g., immunoglobulin light chains, retinol-binding protein, the neuropeptides Met-enkephalin and neuropeptide Y, endothelin-1, and the adipokines leptin and resistin, adversely affect immune cells. Posttranslational modifications such as carbamoylation, advanced glycation products, and oxidative modifications contribute to uremic toxicity. Furthermore, high-density lipoprotein from uremic patients has an altered protein profile and thereby loses its anti-inflammatory properties.

Renal Autocrine and Paracrine Signaling: A Story of Self-protection

Autocrine and paracrine signaling in the kidney adds an extra level of diversity and complexity to renal physiology. The extensive scientific production on the topic precludes easy understanding of the fundamental purpose of the vast number of molecules and systems that influence the renal function. This systematic review provides the broader pen strokes for a collected image of renal paracrine signaling. First, we recapitulate the essence of each paracrine system one by one. Thereafter the single components are merged into an overarching physiological concept. The presented survey shows that despite the diversity in the web of paracrine factors, the collected effect on renal function may not be complicated after all. In essence, paracrine activation provides an intelligent system that perceives minor perturbations and reacts with a coordinated and integrated tissue response that relieves the work load from the renal epithelia and favors diuresis and natriuresis. We suggest that the overall function of paracrine signaling is reno-protection and argue that renal paracrine signaling and self-regulation are two sides of the same coin. Thus local paracrine signaling is an intrinsic function of the kidney, and the overall renal effect of changes in blood pressure, volume load, and systemic hormones will always be tinted by its paracrine status.

Association between circulating big endothelin-1 and noncalcified or mixed coronary atherosclerotic plaques

Background

Noncalcified plaques (NCPs) and mixed plaques (MPs) are considered as the high-risk coronary plaques. Endothelin-1 (ET-1) is a vasoactive peptide and shows a high expression in vulnerable plaque. The aim of this study is to investigate the relationship between the bigET-1, the precursor of ET-1, and NCPs/MPs in a Chinese population.

Methods and results

A total of 513 patients with chest pain and suspected coronary artery disease were collected and divided into three groups with no plaques, calcified plaques, or NCPs/MPs according to the characteristics of all the plaques. It demonstrated that NCPs/MPs were associated with elevated bigET-1 (P < 0.001). Moreover, the proportion of NCPs/MPs was significantly increased from 43.3% in bigET-1 tertile 1 to 61.0% in tertile 3 group (P = 0.001). Multiple logistic regression analysis further showed that bigET-1 was an independent predictor for the presence of NCPs/MPs (odds ratio = 1.858; 95% confidence interval: 1.017–3.394; P = 0.044).

Conclusion

The bigET-1 could be an independent predictor for the presence of NCPs/MPs.

Noncalcified plaques (NCPs) and mixed plaques (MPs) are considered as the high risk coronary plaques. Endothelin- 1(ET-1) is a vasoactive peptide and shows a high expression in vulnerable plaque. However, the relationship between circulating ET-1 and NCPs/MPs is still an unanswered question. In the present study, we found that NCPs and MPs were associated with elevated plasma bigET-1, the precursor of ET-1. The patients with NCPs and MPs had significantly elevated bigET-1, compared to those without coronary plaque or those have calcified plaques. Multiple logistic regression analysis further showed that bigET-1 was an independent predictor for the presence of NCPs/MPs. The finding highlights the potential value of this assay in predicting the characteristics of plaques in patients with suspected or known coronary artery disease.

Endothelins in inflammatory neurological diseases

Endothelins were discovered more than thirty years ago as potent vasoactive compounds. Beyond their well-documented cardiovascular properties, however, the contributions of the endothelin pathway have been demonstrated in several neuroinflammatory processes and the peptides have been reported as clinically relevant biomarkers in neurodegenerative diseases. Several studies report that endothelin-1 significantly contributes to the progression of neuroinflammatory processes, particularly during infections in the central nervous system (CNS), and is associated with a loss of endothelial integrity at the blood brain barrier level. Because of the paucity of clinical trials with endothelin-1 antagonists in several infectious and non-infectious neuroinflammatory diseases, it remains an open question whether the 21 amino acid peptide is a mediator/modulator rather than a biomarker of the progression of neurodegeneration. This review focuses on the potential roles of endothelins in the pathology of neuroinflammatory processes, including infectious diseases of viral, bacterial or parasitic origin in which the synthesis of endothelins or its pharmacology have been investigated from the cell to the bedside in several cases, as well as in non-infectious inflammatory processes such as neurodegenerative disorders like Alzheimers Disease or central nervous system vasculitis.

Adult Sickle Cell Anaemia Patients in Bone Pain Crisis have Elevated Pro-Inflammatory Cytokines

Background and Objectives

Inflammatory markers that influence bone pain crisis (BPC) and other complications of sickle cell anaemia (SCA) are numerous and play various roles. This study determined the plasma levels of tumour necrosis factor (TNF) - α, interleukin - 8 (IL-8), and endothelin - 1 (ET-1) in adult SCA patients during BPC and in steady state. In addition, the plasma levels of these cytokines were correlated with the severity of BPC of the patients.

Methods and Materials

Sixty adult SCA patients (30 during BPC and 30 during steady state) and 30 haemoglobin A controls were enrolled for this cross-sectional study. The severity of BPC was assessed clinically, and questionnaires were filled. Plasma levels of TNF- α, IL-8 and ET-1 were quantified by ELISA, and haematological parameters were determined using a 5-part auto-analyzer. Plasma levels were correlated with the severity of bone pain crisis. Results were considered statistically significant if p<0.05.

Results

Plasma TNF-α, IL-8, and ET-1 were significantly elevated in the BPC group than in the steady state group and the controls. Plasma TNF-α, IL-8 and ET-1 were markedly higher in the severe BPC groups than the steady state and control groups, There was a positive correlation between TNF-α and ET-1 in the bone pain crisis group.

Conclusion

Elevated levels of plasma TNF-α, IL-8, and ET-1 further establish the chronic inflammatory state in SCA and equally affirm their significant contribution, not only to pathogenesis but also to the severity of pain in SCA.

The endothelin B receptor plays a crucial role in the adhesion of neutrophils to the endothelium in sickle cell disease

Although the primary origin of sickle cell disease is a hemoglobin disorder, many types of cells contribute considerably to the pathophysiology of the disease. The adhesion of neutrophils to activated endothelium is critical in the pathophysiology of sickle cell disease and targeting neutrophils and their interactions with endothelium represents an important opportunity for the development of new therapeutics. We focused on endothelin-1, a mediator involved in neutrophil activation and recruitment in tissues, and investigated the involvement of the endothelin receptors in the interaction of neutrophils with endothelial cells. We used fluorescence intravital microscopy analyses of the microcirculation in sickle mice and quantitative microfluidic fluorescence microscopy of human blood. Both experiments on the mouse model and patients indicate that blocking endothelin receptors, particularly ET_B receptor, strongly influences neutrophil recruitment under inflammatory conditions in sickle cell disease. We show that human neutrophils have functional ET_B receptors with calcium signaling capability, leading to increased adhesion to the endothelium through effects on both endothelial cells and neutrophils. Intact ET_B function was found to be required for tumor necrosis factor α-dependent upregulation of CD11b on neutrophils. Furthermore, we confirmed that human neutrophils synthesize endothelin-1, which may be involved in autocrine and paracrine pathophysiological actions. Thus, the endothelin-ET_B axis should be considered as a cytokine-like potent pro-inflammatory pathway in sickle cell disease. Blockade of endothelin receptors, including ET_B, may provide major benefits for preventing or treating vaso-occlusive crises in sickle cell patients.

Nur77 attenuates endothelin-1 expression via downregulation of NF-κB and p38 MAPK in A549 cells and in an ARDS rat model

Acute respiratory distress syndrome (ARDS) is characterized by inflammatory injury to the alveolar and capillary barriers that results in impaired gas exchange and severe acute respiratory failure. Nuclear orphan receptor Nur77 has emerged as a regulator of gene expression in inflammation, and its role in the pathogenesis of ARDS is not clear. The objective of this study is to investigate the potential role of Nur77 and its underlying mechanism in the regulation of endothelin-1 (ET-1) expression in lipopolysaccharide (LPS)-induced A549 cells and an ARDS rat model. We demonstrate that LPS induced Nur77 expression and nuclear export in A549 cells. Overexpression of Nur77 markedly decreased basal and LPS-induced ET-1 expression in A549 cells, whereas knockdown of Nur77 increased the ET-1 expression. LPS-induced phosphorylation and nuclear translocation of NF-κB and p38 MAPK were blocked by Nur77 overexpression and augmented by Nur77 knockdown in A549 cells. In vivo, LPS induced Nur77 expression in lung in ARDS rats. Pharmacological activation of Nur77 by cytosporone B (CsnB) inhibited ET-1 expression in ARDS rats, decreased LPS-induced phosphorylation of NF-κB and p38 MAPK, and relieved lung, liver, and kidney injury. Pharmacological deactivation of Nur77 by 1,1-bis-(3'-indolyl)-1-(p-hydroxyphenyl)methane (DIM-C-pPhOH, C-DIM8) had no effect on ET-1 expression and lung injury. These results indicated that Nur77 decreases ET-1 expression by suppressing NF-κB and p38 MAPK in LPS-stimulated A549 cells in vitro, and, in an LPS-induced ARDS rat model, CsnB reduced ET-1 expression and lung injury in ARDS rats.

Potential role for ET-2 acting through ETA receptors in experimental colitis in mice

OBJECTIVE AND DESIGN

This study attempted to clarify the roles of endothelins and mechanisms associated with ET_A/ET_B receptors in mouse models of colitis.

MATERIALS AND METHODS

Colitis was induced by intracolonic administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS, 1.5 mg/animal) or dextran sulfate sodium (DSS, 3%). After colitis establishment, mice received Atrasentan (ET_A receptor antagonist, 10 mg/kg), A-192621 (ET_B receptor antagonist, 20 mg/kg) or Dexamethasone (1 mg/kg) and several inflammatory parameters were assessed, as well as mRNA levels for ET-1, ET-2 and ET receptors.

RESULTS

Atrasentan treatment ameliorates TNBS- and DSS-induced colitis. In the TNBS model was observed reduction in macroscopic and microscopic score, colon weight, neutrophil influx, IL-1β, MIP-2 and keratinocyte chemoattractant (KC) levels, inhibition of adhesion molecules expression and restoration of IL-10 levels. However, A192621 treatment did not modify any parameter. ET-1 and ET-2 mRNA was decreased 24 h, but ET-2 mRNA was markedly increased at 48 h after TNBS. ET-2 was able to potentiate LPS-induced KC production in vitro. ET_A and ET_B receptors mRNA were increased at 24, 48 and 72 h after colitis induction.

CONCLUSIONS

Atrasentan treatment was effective in reducing the severity of colitis in DSS- and TNBS-treated mice, suggesting that ET_A receptors might be a potential target for inflammatory bowel diseases.

Increased endothelin 1 type B receptors in nasal lesions of patients with granulomatosis with polyangiitis

BACKGROUND

Endothelin 1 (ET-1) is a locally produced vasoactive peptide with proinflammatory capabilities. Systemic levels of ET-1 seem elevated in granulomatosis with polyangiitis (GPA). The aim of this study was to examine the involvement of the endothelin system in patients with GPA using nasal mucosal biopsies.

METHODS

Formalin-fixed and paraffin-embedded nasal mucous membranes from eight patients with GPA and eight controls were analyzed for ET-1 type A receptor (ETAR) and type B receptor (ETBR) expression using immunohistochemistry.

RESULT

ETAR immunostaining was localized only to a few inflammatory cells and to multinucleate giant cells (MGCs) in the nasal mucosa in GPA subjects. Intense ETBR immunostaining was localized to lymphocytes and MGC in the nasal granulomatous lesions in GPA. CD3(+), CD4(+), CD8(+), and CD68(+) lymphocytes expressed ETBRs in GPA subjects.

CONCLUSION

This observation shows that ETBR(+) lymphocyte expression predominates in nasal granulomatous lesions in GPA compared with ETAR. ETBR immunostaining is located to T cells, CD68(+) cells, and MGCs. ETBR may play an active role in the progression of granulomatous lesions in GPA.

Endothelin-1 and its role in the pathogenesis of infectious diseases

Endothelins are potent regulators of vascular tone, which also have mitogenic, apoptotic, and immunomodulatory properties (Rubanyi and Polokoff, 1994; Kedzierski and Yanagisawa, 2001; Bagnato et al., 2011). Three isoforms of endothelin have been identified to date, with endothelin-1 (ET-1) being the best studied. ET-1 is classically considered a potent vasoconstrictor. However, in addition to the effects of ET-1 on vascular smooth muscle cells, the peptide is increasingly recognized as a pro-inflammatory cytokine (Teder and Noble, 2000; Sessa et al., 1991). ET-1 causes platelet aggregation and plays a role in the increased expression of leukocyte adhesion molecules, the synthesis of inflammatory mediators contributing to vascular dysfunction. High levels of ET-1 are found in alveolar macrophages, leukocytes (Sessa et al., 1991) and fibroblasts (Gu et al., 1991). Clinical and experimental data indicate that ET-1 is involved in the pathogenesis of sepsis (Tschaikowsky et al., 2000; Goto et al., 2012), viral and bacterial pneumonia (Schuetz et al., 2008; Samransamruajkit et al., 2002), Rickettsia conorii infections (Davi et al., 1995), Chagas disease (Petkova et al., 2000, 2001), and severe malaria (Dai et al., 2012; Machado et al., 2006; Wenisch et al., 1996a; Dietmann et al., 2008). In this minireview, we will discuss the role of endothelin in the pathogenesis of infectious processes.

New perspectives on endothelin-1 in atherosclerosis and diabetes mellitus

Endothelin-1 (ET-1) is a vasoconstrictor, proinflammatory and proliferative endothelial cell-derived peptide that is of significant importance in the regulation of vascular function. It is involved in the development of endothelial dysfunction including important interactions with nitric oxide. The expression and functional effects of ET-1 and its receptors are markedly altered during development of cardiovascular disease. Increased production of ET-1 and its receptors mediate many pathophysiological events contributing to the development of atherosclerosis and vascular complications in diabetes mellitus. The present review focuses on the pathophysiological role of ET-1 and the potential importance of ET receptors as a therapeutic target for treatment of these conditions.

Endothelin-1 induces neutrophil recruitment in adaptive inflammation via TNFα and CXCL1/CXCR2 in mice

Endothelin mediates neutrophil recruitment during innate inflammation. Herein we address whether endothelin-1 (ET-1) is involved in neutrophil recruitment in adaptive inflammation in mice, and its mechanisms. Pharmacological treatments were used to determine the role of endothelin in neutrophil recruitment to the peritoneal cavity of mice challenged with antigen (ovalbumin) or ET-1. Levels of ET-1, tumour necrosis factor α (TNFα), and CXC chemokine ligand 1 (CXCL1) were determined by enzyme-linked immunosorbent assay. Neutrophil migration and flow cytometry analyses were performed 4 h after the intraperitoneal stimulus. ET-1 induced dose-dependent neutrophil recruitment to the peritoneal cavity. Treatment with the non-selective ET(A)/ET(B) receptor antagonist bosentan, and selective ET(A) or ET(B) receptor antagonists BQ-123 or BQ-788, respectively, inhibited ET-1- and ovalbumin-induced neutrophil migration to the peritoneal cavity. In agreement with the above, the antigen challenge significantly increased levels of ET-1 in peritoneal exudates. The ET-1- and ovalbumin-induced neutrophil recruitment were reduced in TNFR1 deficient mice, and by treatments targeting CXCL1 or CXC chemokine receptor 2 (CXCR2); further, treatment with bosentan, BQ-123, or BQ-788 inhibited ET-1- and antigen-induced production of TNFα and CXCL1. Furthermore, ET-1 and ovalbumin challenge induced an increase in the number of cells expressing the Gr1(+) markers in the granulocyte gate, CD11c(+) markers in the monocyte gate, and CD4(+) and CD45(+) (B220) markers in the lymphocyte gate in an ET(A)- and ET(B)-dependent manner, as determined by flow cytometry analysis, suggesting that ET-1 might be involved in the recruitment of neutrophils and other cells in adaptive inflammation. Therefore, the present study demonstrates that ET-1 is an important mediator for neutrophil recruitment in adaptive inflammation via TNFα and CXCL1/CXCR2-dependent mechanism.

The role of endothelin-1 in the pathogenesis of idiopathic pulmonary fibrosis

The endothelin system participates in a number of critical biologic pathways, including normal wound healing. In addition, emerging basic science, and animal and human data all suggest that endothelin-1 (EDN1, also known as ET-1) is a potentially important contributor in the pathobiology of fibrosing disorders, including those that affect the lung. For example, EDN1 drives fibroblast activation, proliferation, as well as differentiation into myofibroblasts - processes that lead to excessive collagen deposition. Patients with idiopathic pulmonary fibrosis (IPF) have increased levels of EDN1 in both their bronchoalveolar lavage fluid and lung tissue. Beyond this, rodent models suggest that endothelin receptor antagonists can limit bleomycin-induced lung fibrosis. This suggests a biologic rationale for the blockade of EDN1 to limit the evolution of lung fibrosis in humans. Initial results from a trial examining the efficacy of a dual endothelin receptor antagonist suggest that this approach may delay disease progression in a subset of patients with IPF.

Dual Roles for Endothelin-B Receptors in Modulating Adjuvant-Induced Inflammatory Hyperalgesia in Rats

Injection of endothelin-1 (ET-1) into the plantar rat hindpaw causes acute pain at high concentrations and tactile sensitization at low concentrations. The pro-nociceptive actions are driven through ET(A) receptors for both levels of [ET-1], but the ET(B) receptors are only pro-nociceptive for allodynia from low [ET-1] and anti-nociceptive for pain from high [ET-1]. The goal of the present work was to discriminate the roles of the ET receptors in the acute hyperalgesia from inflammation by complete Freund's adjuvant (CFA, 20 mg/paw) into the rat hindpaw. Selective antagonists were injected l0 min before and then together with CFA. An ET(A) receptor antagonist, BQ-123, reduced CFA-induced thermal hyperalgesia (by up to 50%), as did an ET(B) receptor antagonist, BQ-788 (by up to 66%). BQ-123 and BQ-788 also delayed the onset (by 1.5 - 2 h) but insignificantly reduced the maximum degree of CFA-induced allodynia (~10%). Surprisingly, an ET(B) receptor agonist, IRL-1620, also reduced maximum thermal hyperalgesia induced by CFA, suppressed peak allodynia and delayed its occurrence by ~ 3 h. The latter actions of IRL-1620 were reversed by co-administration of BQ-788, naloxone hydrochloride and the peripherally restricted opiate receptor antagonist naloxone methiodide, and by antiserum against β-endorphin. These findings demonstrate an important role for endogenous ET-1 in acute inflammatory pain and a dual action of ET(B) receptors, including a pro-algesic action along with the important activation of a local analgesic pathway, implying that at least two different ET(B) receptors contribute to modulation of inflammatory pain.

Targeting endothelin ETA and ETB receptors inhibits antigen-induced neutrophil migration and mechanical hypernociception in mice

Endothelin may contribute to the development of inflammatory events such as leukocyte recruitment and nociception. Herein, we investigated whether endothelin-mediated mechanical hypernociception (decreased nociceptive threshold, evaluated by electronic pressure-meter) and neutrophil migration (myeloperoxidase activity) are inter-dependent in antigen challenge-induced Th1-driven hind-paw inflammation. In antigen challenge-induced inflammation, endothelin (ET) ET(A) and ET(B) receptor antagonism inhibited both hypernociception and neutrophil migration. Interestingly, ET-1 peptide-induced hypernociception was not altered by inhibiting neutrophil migration or endothelin ET(B) receptor antagonism, but rather by endothelin ET(A) receptor antagonism. Furthermore, endothelin ET(A), but not ET(B), receptor antagonism inhibited antigen-induced PGE(2) production, whereas either selective or combined blockade of endothelin ET(A) and/or ET(B) receptors reduced hypernociception and neutrophil recruitment caused by antigen challenge. Concluding, this study advances knowledge into the role for endothelin in inflammatory mechanisms and further supports the potential of endothelin receptor antagonists in controlling inflammation.

Polymorphisms of the endothelin-1 gene associate with hypertension in patients with rheumatoid arthritis

Rheumatoid arthritis (RA) associates with excess cardiovascular (CV) morbidity and mortality. Hypertension, a highly prevalent entity in RA, has been associated with the endothelin-1 (ET-1) gene locus (EDN1) in some groups, such as Afro-Caribbean, the obese, and in low-renin states, but not in the general population as a whole. High levels of plasma ET-1 have been observed in RA. This study evaluated the potential association of EDN1 gene locus and serum ET-1 levels with hypertension in patients with RA. Genomic DNA and serum samples were collected from 397 well-characterized RA patients; DNA was also available from 401 local general population controls without RA. To explore the overall relevance of EDN1, two suitable single-nucleotide polymorphisms (SNPs), rs1800541 and rs5370, were selected and haplotype analysis was performed. Both SNPs were identified using real-time polymerase chain reaction (PCR) and melting curve analysis. Genetic analysis was related to hypertension as dichotomous trait and to blood pressure indices as continuous variables. Serum endothelin levels were also assessed in the RA patients. No genotype or haplotype differences were observed between RA and control subjects. Within RA, logistic regression analysis of each SNP separately revealed a threefold increase in the adjusted odds of being hypertensive of rs5370 TT homozygotes compared to GG homozygotes (OR = 2.89, 95%CI: 1.02 to 8.19). After adjustment for multiple potential confounders, haplotype analysis revealed an additive effect of the rs1800541-rs5370 T-T haplotype on hypertension (OR = 2.96, 95%CI: 1.28 to 6.86; p = .011), systolic blood pressure (SBP) (beta = 6.75 +/- 2.57 mm Hg; p = .009), and pulse pressure (PP) (beta = 4.37 +/- 2.12 mm Hg; p = .040). There was an increased prevalence of raised ET-1 levels amongst hypertensive RA patients, whereas a similar trend was observed for T-T haplotype carriers. RA patients who carry the rs1800541-rs5370 T-T EDN1 haplotype appear more likely to be hypertensive with an increased SBP and PP. These findings, if replicated in future studies, could be used as a screening tool for RA patients at increased hypertension, and thus cardiovascular, risk.

The effects of endothelin receptor blockade by bosentan on the healing of a bowel anastomosis in an experimental Crohn's disease model

OBJECTIVE

It was previously described that endothelins may contribute to the pathogenesis of Crohn's disease. In this study, it was aimed to investigate the effects of endothelin receptor blockade by bosentan on the healing of a bowel anastomosis in an experimental Crohn's disease model.

MATERIAL AND METHODS

Twenty-eight Sprague-Dawley rats were divided into four groups. Groups I and II were used as sham-operated and control groups, respectively. Bowel inflammation induced by intrajejunal injection of iodoacetamide in groups III and IV. Rats in group IV were treated with oral preparation of bosentan 60 mg/kg/day. Three days after induction of the inflammation, partial resection of test loop and anastomosis was performed. Re-laparotomy was performed, anastomosis bursting pressures and peritonitis scores were measured, and tissue samples were obtained for the measurements of tissue hydroxylproline level and mucosal damage index 4 days later.

RESULTS

The mean mucosal damage index and peritonitis score of group IV were significantly lower, and the mean tissue hydroxyproline level and anastomotic bursting pressure of group IV were significantly higher than those of group III.

CONCLUSION

The blockade of endothelin receptors by bosentan decreases the severity of iodoacetamide induced intestinal inflammation, increases the wound healing in the inflamed intestinal tissue, and decreases the severity of peritonitis.

Crevicular fluid endothelin-1 levels in periodontal health and disease

BACKGROUND AND OBJECTIVE

Endothelin-1 is a 21-amino-acid peptide with multifunctional regulation. Initial research indicated that endothelin-1 levels in the gingival crevicular fluid from patients with chronic periodontitis were higher than those in the gingival crevicular fluid from healthy subjects. The aim of the present study was to assess the relationship between the clinical parameters and the concentrations of endothelin-1 within the gingival crevicular fluid from inflamed gingiva and periodontitis sites and, subsequently, after the treatment of periodontitis sites.

MATERIAL AND METHODS

A total of 60 subjects were divided into three groups - healthy (group I), gingivitis (group II) and chronic periodontitis (group III) - based on gingival index, pocket probing depth and clinical attachment loss. A fourth group consisted of 20 subjects from group III, 6-8 wk after treatment (i.e. scaling and root planing). Gingival crevicular fluid samples collected from each patient were quantified for endothelin-1 using an enzymatic immunometric assay.

RESULTS

Endothelin-1 was not detected in any sample from any of the study groups.

CONCLUSION

The results showed that all the gingival crevicular fluid samples were negative for the endothelin-1 molecule. Therefore, endothelin-1 cannot be considered as a potential biomarker of periodontal disease progression.

Endothelin-1-induced pain and hyperalgesia: a review of pathophysiology, clinical manifestations and future therapeutic options

Pain in patients with metastatic cancer contributes to increased suffering in those already burdened by their advancing illness. The causes of this pain are unknown, but are likely to involve the action of tumour-associated mediators and their receptors. In recent years, several chemical mediators have increasingly come to the forefront in the pathophysiology of cancer pain. One such mediator, endothelin-1 (ET-1), is a peptide of 21 amino acids that was initially shown to be a potent vasoconstrictor. Extensive research has revealed that members of the ET family are indeed produced by several epithelial cancerous tumours, in which they act as autocrine and/or paracrine growth factors. Several preclinical and clinical studies of various malignancies have suggested that the ET axis may represent an interesting contributor to tumour progression. In addition, evidence is accumulating to suggest that ET-1 may contribute to pain states both in humans and in other animals. ET-1 both stimulates nociceptors and sensitises them to painful stimuli. Selective stimulation of ET receptors has been implicated as a cause of inflammatory, neuropathic and tumoural pain. ET-1-induced pain-related behaviour seems to be mediated either solely by one receptor type or via both endothelin-A receptors (ETAR) and endothelin-B receptors (ETBR). Whereas stimulation of ETAR on nociceptors always elicits a pain response, stimulation of ETBR may cause analgesia or elicit a pain response, depending on the conditions. The administration of ETAR antagonists in the receptive fields of these nociceptors has been shown to ameliorate pain-related behaviours in animals, as well as in some patients with advanced metastatic prostate cancer. The identification of tumour-associated mediators that might directly or indirectly cause pain in patients with metastatic disease, such as ET-1, should lead to improved, targeted analgesia for patients with advanced cancer. In this review, we will describe the current status of the role of ET-1 in different types of painful syndromes, with special emphasis on its role in the pathophysiology of cancer pain. Finally, potential new treatment options that are based on the role of the ET axis in the pathophysiology of cancer are elaborated.

Vasoactive peptides in cardiovascular (patho)physiology

Numerous vasoactive agents play an important physiological role in regulating vascular tone, reactivity and structure. In pathological conditions, alterations in the regulation of vasoactive peptides result in endothelial dysfunction, vascular remodeling and vascular inflammation, which are important processes underlying vascular damage in cardiovascular disease. Among the many vasoactive agents implicated in vascular (patho)biology, angiotensin II (Ang II), endothelin (ET), serotonin and natriuretic peptides appear to be particularly important because of their many pleiotropic actions and because they have been identified as potential therapeutic targets in cardiovascular disease. Ang II, ET-1, serotonin and natriuretic peptides mediate effects via specific receptors, which belong to the group of G-protein-coupled receptors. ET, serotonin and Ang II are primarily vasoconstrictors with growth-promoting actions, whereas natriuretic peptides, specifically atrial, brain and C-type natriuretic peptides, are vasodilators with natriuretic effects. Inhibition of vasoconstrictor actions with drugs that block peptide receptors, compounds that inhibit enzymes that generate vasoactive peptides or agents that increase levels of natriuretic peptides are potentially valuable therapeutic tools in the management of cardiovascular diseases. This review focuses on ET, natriuretic peptides and serotonin. The properties and distribution of these vasoactive agents and their receptors, mechanisms of action and implications in cardiovascular (patho)physiology will be discussed.

John R. Vane, « pharmacologue de l’endothélium vasculaire », 1927–2004

The work of John Vane greatly contributed to the use of aspirin in cardiology. The impact of aspirin administration at low dose for the prevention of stroke or coronary attack results from its effect on enzymes regulating the production of prostaglandins. After understanding the mechanism of interaction between aspirin and the vascular endothelium, Vane proposed assigning a major physiological function to the vascular endothelium which then became a pharmacological target for new drugs. Using an ingenious "real time" biological assay of bloodstream hormones irrigating an isolated organ called the "blood-bathed organ cascade", John Vane developed a system for highly sensitive monitoring of several mediators like angiotensin, bradykinin and prostaglandins and discovered prostacyclin, a potent platelet aggregation inhibitor. Vane explained anti-inflammatory drugs effects (among which aspirin remains the leader) through their activity on cyclo-oxygenase and inhibition of prostacyclin and thromboxane production. Another cyclooxygenase isoform, so-called type 2, has been discovered in 1991. Thus, besides the constitutive COX-1, participating to stomach protection and renal artery vasodilatation, a COX-2 enzyme is existing, induced by inflammatory phenomenons and cytokines stimulation, allowing to design specific inhibitors "coxibs", playing an increasing but controversial role in the struggle against inflammation. He won Albert Lasker Prize in 1977 and Nobel Prize in medicine and physiology (shared with Sune Bergström and Bengt I. Samuelson) in 1982.

Estrogen therapy and thrombotic risk

Post-menopausal hormone therapy increases the risk for venous thrombosis, and possibly myocardial infarction (MI) and ischemic stroke. However, most women using hormone therapy do not suffer thrombosis, and to date our ability to identify women at risk is limited. Thrombosis, arterial or venous, has 2 requisites: a vascular anomaly and a response of the hemostasis system to the anomaly. Consequently, experimental approaches to understand the pathophysiology of thrombosis require definition of vascular anatomy and function as well as characteristics of the blood within the context of genetic background, lifestyle choices and environmental exposures, which influence gene expression. Defining interactions among factors that affect individual propensity to thrombosis will allow physicians to better identify at-risk individuals, for example a woman contemplating estrogen therapy for symptoms of menopause, and prevent adverse thrombotic events.

Effect of endothelins on human neutrophil activation by immune complexes

Neutrophils are important effector cells of tissue injury in several pathological conditions, among them, immune complexes (IC)-induced inflammation and tissue injury. There is evidence that endothelins modulate IC-induced tissue injury in experimental models in vivo. In the present study we investigated the effect of endothelins on neutrophil activation by IC in vitro. To this purpose, pre-formed insoluble immune complexes were used to stimulate human neutrophils and production of leukotriene B(4) (LTB(4)) and hydrogen peroxyde (H(2)O(2)) were measured as indicative of phospholipase A(2) and oxidative burst activation and myeloperoxidase (MPO) release as indicative of cell degranulation. The effect of endothelins (ETs) in these events induced by IC was then examined. We found that IC stimulated all three events in human neutrophils. Addition of ET-1 but not ET-2 or ET-3 to the IC-stimulated neutrophils potentiated LTB(4) but not H(2)O(2) production. The endothelins added to resting neutrophils did not induce LTB(4) production but they were effective to stimulate H(2)O(2) production. The increased MPO activity induced by IC was not affected by endothelins nor did they stimulate the release of this enzyme in resting cells. These results show that endothelins are able to activate some neutrophil functions and to upregulate the IC-induced production of the pro-inflammatory molecule LTB(4). These data indicate that products of endothelial cells, such as endothelins, can be involved in the potentiation of neutrophil-dependent tissue injury.

Controlled release of a nitric oxide donor for the prevention of delayed cerebral vasospasm following experimental subarachnoid hemorrhage in nonhuman primates

OBJECT

Results of prior studies in rats and rabbits show that the alteration of vasomotor tone in vasospasm following periadventitial blood exposure may be reversed, at least in part, by the administration of compounds releasing nitric oxide (NO). The authors have now generalized this finding to nonhuman primates.

METHODS

Ten cynomolgus monkeys underwent cerebral angiography before and 7 days following the induction of subarachnoid hemorrhage (SAH) by the placement of 2 to 3 ml clotted autologous blood around the supraclinoid carotid, proximal anterior cerebral, and proximal middle cerebral arteries. An ethylene vinyl acetate copolymer, either blank (five animals) or containing 20% w/w (Z)-1-[2-(2-aminoethyl)-N-(2-aminoethyl)amino]diazen-1-ium-1,2-diolate (DETA/NO, 4.3 mg/kg; five animals) was placed adjacent to the vessels at the time of surgery. Animals were killed on Day 7 post-SAH following repeated cerebral angiography. The mean percentage of control vascular areal fraction was calculated from angiograms. Cerebral vessels were sectioned and the mean percentage of lumen patency was calculated. One animal that had received the DETA/NO polymer died prior to repeated angiography. In the remaining animals, DETA/NO caused a significant decrease in vasospasm compared with controls, according to both angiographic (84.8 +/- 8.6 compared with 56.6 +/- 5.2%, respectively, p < 0.05) and histological studies (internal carotid artery 99.3 +/- 1.8 compared with 60.1 +/- 4.4%, respectively, p < 0.001; middle cerebral artery 98.4 +/- 3 compared with 56.1 +/- 3.7%, respectively, p < 0.001; and anterior cerebral artery 89.2 +/- 8.5 compared with 55.8 +/- 6.3%, respectively, p < 0.05).

CONCLUSIONS

The controlled release of DETA/NO is effective in preventing delayed cerebral vasospasm in an SAH model in nonhuman primates. The death of one animal in the treatment group indicates that the present dosage is at the threshold between therapeutic efficacy and toxicity.

Role of endothelin 1 in the pathogenesis of chronic chagasic heart disease

On the basis of previous observations, endothelin 1 (ET-1) has been suggested as contributing to the pathogenesis of Chagasic cardiomyopathy. Therefore, ET-1flox/flox;alpha-MHC-Cre(+) mice in which the ET-1 gene was deleted from cardiac myocytes and ET-1flox/flox;Tie 2 Cre(+) mice in which the ET-1 gene was deleted from endothelial cells were infected with Trypanosoma cruzi. Genetic controls for these cell-specific ET-1 knockout mice were used. Ninety percentage of all mice survived acute infection with the Brazil strain and were evaluated 130 days postinfection. Inflammation and fibrosis were observed in all infected mice; however, fibrosis was reduced in ET-1flox/flox;alpha-MHC-Cre(+) mice. Cardiac magnetic resonance imaging revealed that infection resulted in a significant increase in right ventricular internal diameter (RVID) in all mice except ET-1flox/flox;alpha-MHC-Cre(+) mice; i.e., RVID was not changed in infected ET-1flox/flox;alpha-MHC-Cre(+) mice. Echocardiography of the left ventricle demonstrated increased left ventricular end-diastolic diameter, reduced fractional shortening, and decreased relative wall thickness in infected mice. However, the magnitude of the changes was significantly less in ET-1flox/flox;alpha-MHC-Cre(+) mice compared to other groups. These data provide further evidence of a role for ET-1, particularly cardiac myocyte-derived ET-1, in the pathogenesis of chronic Chagasic cardiomyopathy.

Expression of vasoactive mediators during mechanical ventilation in nitrofen-induced diaphragmatic hernia in rats

The high mortality in patients with congenital diaphragmatic hernia (CDH) has been attributed to pulmonary hypoplasia and persistent pulmonary hypertension (PPH). Endothelin-1 (ET-1), nitric oxide (NO), and calcitonin gene-related peptide (CGRP) have been reported to be important vasoactive mediators in the perinatal pulmonary circulation. The exact mechanism by which these vasoactive mediators interact to regulate the perinatal pulmonary vascular tone in CDH with PPH is not fully understood. We hypothesized that the altered pulmonary vascular reactivity in CDH is due to imbalance in vasoactive mediators. This study was designed to investigate mRNA expression of ET-1, eNOS, and CGRP in CDH lung in the perinatal period. A CDH model was induced in pregnant rats following administration of nitrofen. In control animals, the same dose of olive oil was given without nitrofen. Cesarean section was performed on day 21 of gestation. The newborn rats were intubated and ventilated, and ventilation was continued for 1-6 h. Left lungs were collected from both groups at 0, 1, and 6 h after ventilation (n=8 in each group). Reverse transcriptase-polymerase chain reaction on lung tissue was performed to evaluate the relative level of ET-1, eNOS, and CGRP mRNA expression. The results showed a significant increase in ET-1 mRNA in CDH lung at 1 and 6 h after ventilation compared with controls. In CDH lung, eNOS mRNA and CGRP mRNA levels were significantly increased at 1 h but were similar to control values at 6 h after ventilation. The increased expression of vasoconstrictor ET-1 mRNA and vasodilators eNOS mRNA and CGRP mRNA in the CDH lung at 1 h after ventilation suggests that pulmonary vascular tone is rapidly changing after birth. An imbalance in the production of vasoconstrictors and vasodilators by the CDH lung may contribute to high pulmonary vascular resistance.

Association of Endothelin with Lung Hemorrhage Induced by Immune Complexes in Rats

The participation of endothelins (ETs) in a model of neutrophil-dependent lung injury induced by intrabronchial instillation of rabbit antibodies to ovalbumin followed by i.v. injection of the antigens (Arthus reaction) was investigated. Hemorrhagic lesions were evaluated by measuring the extravasations of hemoglobin in lung parenchyma. From 5 min to 24 h after the Arthus reaction (AR), endothelin (ir-ET) levels in bronchoalveolar lavage fluid (BALF) and in plasma were measured by radioimmunoassay. BALF levels of ir-ET were not different between control and AR animals for the first 90 min after the antigen challenge but increased from 2 to 24 h after induction of AR. ET levels in the plasma did not change from the respective controls over the same 24 h period. Increased ir-ET in BALF was not affected by pretreatment with L-NAME (30 mg/kg, i.v.). A PAF antagonist (BN52021; 5 and 10 mg/kg, i.v.) increased ET content in BALF and decreased the intensity of the AR. Thiorphan (2 mg/kg, i.v.) inhibited the AR-induced hemorrhagic lesions in lungs. An ET(A) receptor antagonist, BQ-123 (1 mg/kg, i.v.) potentiated, whereas the ET(B) antagonist, BQ-788 (1 mg/kg, i.v.) inhibited the lung hemorrhage. It is concluded that ETs are released during and play a role in the lung AR.

Inhibition of cerebral vasospasm by intracranial delivery of ibuprofen from a controlled-release polymer in a rabbit model of subarachnoid hemorrhage

OBJECT

Leukocyte-endothelial cell interactions may play a role in the development of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) because the extravasation of circulating leukocytes into the periadventitial space within 24 hours after the hemorrhage appears to be a critical event in this process. Ibuprofen is an antiinflammatory agent that inhibits the expression of specific cell adhesion molecules and, consequently, disrupts leukocyte-endothelial cell interactions. The authors investigated the efficacy of ibuprofen delivered locally from controlled-release polymers in the rabbit basilar artery (BA) model of cerebral vasospasm.

METHODS

Ibuprofen was incorporated into controlled-release ethylene-vinyl acetate copolymer (EVAc) constituting 45% of the resulting polymer by weight. Fifty-four New Zealand White rabbits were randomized to 10 groups: sham operation (seven animals); SAH only (seven animals); and SAH plus either empty EVAc or ibuprofen-EVAc polymer at 30 minutes or 6, 12, or 24 hours (five animals per group; 40 total). The rabbits were killed 72 hours after induction of SAH, at the time of maximal vasospasm. The efficacy of ibuprofen in preventing vasospasm was assessed by measuring lumen patency of the rabbit's BAs. The intracranial controlled release of ibuprofen resulted in a significant inhibition of vasospasm when treatment was initiated at 30 minutes (patency 92.3 +/- 5.1% compared with 52.1 +/- 5.1% in animals given empty EVAc; p < 0.001) and 6 hours (patency 69.5 +/- 3.5% compared with 47.2 +/- 1.5% in animals given empty EVAc; p < 0.03) after blood deposition compared with treatment with empty EVAc. No effect was observed when treatment was begun at either 12 or 24 hours.

CONCLUSIONS

Local intracranial delivery of ibuprofen accomplished using controlled-release polymers prevents vasospasm in the rabbit BA model of vasospasm when administered within 6 hours after blood exposure.

Trypanosoma cruzi infection activates extracellular signal-regulated kinase in cultured endothelial and smooth muscle cells

Trypanosoma cruzi infection causes cardiomyopathy and vasculopathy. We examined the consequence of this infection for the mitogen-activated protein kinase (MAPK) pathways, which regulate cell proliferation in cultured human umbilical vein endothelial and vascular smooth muscle cells. Infection of these cells resulted in activation of extracellular signal-regulated kinases 1and 2 (ERK1/2) but not c-Jun N-terminal kinase or p38 MAPK. Treatment of these cells with the MAPK kinase inhibitor PD98059 prior to infection blocked the increase in phosphorylated ERK1/2 seen with infection. Heat-killed parasites did not activate ERK1/2, indicating that activation of ERK1/2 was dependent on infection of these cells by live parasites. Furthermore, transfection with dominant-negative Raf(301) or Ras(N17) constructs reduced the infection-associated levels of phospho-ERK1/2, indicating that the activation of ERK1/2 involved the Ras-Raf-ERK pathway. Infection also resulted in an increase in activator protein 1 (AP-1) activity, which was inhibited by transfection with a dominant-negative Raf(301) construct. T. cruzi-infected endothelial cells secreted endothelin-1 and interleukin-1beta, which activated ERK1/2 and induced cyclin D1 expression in uninfected smooth muscle cells. These data suggest a possible molecular paradigm for the pathogenesis of the vasculopathy and the cardiovascular remodeling associated with T. cruzi infection.

Neutralizing Antibody against Interleukin-6 Attenuates Posthemorrhagic Vasospasm in the Rat Femoral Artery Model

OBJECTIVE

The degree to which inflammation contributes to the development of posthemorrhagic vasospasm is controversial. In the present study, we investigated the relationship between various inflammatory cytokines (tumor necrosis factor-alpha, interleukin [IL]-1alpha, IL-1beta, and IL-6) and the development of experimental vasospasm.

METHODS

Posthemorrhagic vasospasm was produced in the rat femoral artery model. A latex pouch was placed around each femoral artery, and one pouch was injected with autologous blood and the other with saline as an internal control. Animals were killed at various time points (1 h to 16 d) after surgery (blood exposure), and the degree of vasospasm was assessed by image analysis of artery cross sectional area. Levels of inflammatory cytokines were determined by enzyme-linked immunosorbent assay, and the ability of a polyclonal antibody against rat IL-6 to inhibit vasospasm was tested.

RESULTS

The rat femoral artery model produced a biphasic vasospasm response, with maximal chronic delayed vasospasm occurring at 8 days after hemorrhage. Enzyme-linked immunosorbent assay revealed a significant increase in IL-6 concentrations in blood-exposed arteries relative to saline-exposed arteries at multiple time points (6, 12, 24, and 48 h) after hemorrhage (P < 0.0001). A relative increase in IL-1alpha levels was noted at 24 hours (P < 0.01). IL-1beta levels were similarly elevated in both blood- and saline-exposed arteries, and tumor necrosis factor-alpha levels were not detectable. Administration of a neutralizing polyclonal antibody against rat IL-6 directly into the blood-exposed periarterial pouch at the time of initial surgery resulted in a dose-dependent reduction in the degree of vasospasm compared with vehicle-treated controls at 8 days after hemorrhage (P < 0.05).

CONCLUSIONS

These results indicate that cytokine-mediated inflammation is active in the setting of posthemorrhagic vasospasm produced by the rat femoral artery model. In particular, the profound increase in IL-6 levels after exposure to hemorrhage and the ability of a polyclonal antibody against IL-6 to reduce vasospasm suggest that IL-6 may play a prominent role in the development of vasospasm in this model.

Prevention of cerebral vasospasm by a humanized anti-CD11/CD18 monoclonal antibody administered after experimental subarachnoid hemorrhage in nonhuman primates

OBJECT

Leukocyte-endothelial cell interactions occurring in the first hours after subarachnoid hemorrhage (SAH) initiate changes in the endothelium and vessel wall that lead to an influx of leukocytes and the development of chronic vasospasm days later. Upregulation of intercellular adhesion molecule-1 (ICAM-1), also called CD54, appears to be a crucial step in this process. There is increasing experimental evidence that blocking the interaction between ICAM-1, which is expressed on endothelium, and integrins such as lymphocyte function-associated antigen-1 (CD11a/CD18) and macrophage antigen-1 (complement receptor 3, CD11b/CD18), which are expressed on the surface of leukocytes,prevents not only inflammation of vessel walls but also chronic vasospasm. The authors extend their previous work with monoclonal antibody (mAb) blockade of leukocyte migration to a nonhuman primate model of chronic, posthemorrhagic cerebral vasospasm.

METHODS

Before surgery was performed, six young adult male cynomolgus monkeys underwent baseline selective biplane common carotid and vertebrobasilar artery cerebral angiography via a transfemoral route. On Day 0, a right frontosphenotemporal craniectomy was performed with arachnoid microdissection and placement of 2 to 3 ml of clotted autologous blood in the ipsilateral basal cisterns. The animals were given daily intravenous infusions of 2 mg/kg of either a humanized anti-CD11/CD18 or a placebo mAb beginning 30 to 60 minutes postoperatively. The monkeys were killed on Day 7 after a repeated selective cerebral angiogram was obtained. The area of contrast-containing vessels observed in each hemisphere on anteroposterior angiographic views was calculated for the angiograms obtained on Day 7 and expressed as a percentage of the area on baseline angiograms (percent control areal fraction). Review of flow cytometry and enzyme immunoassay data confirmed the presence of the anti-CD11/CD18 antibody in the serum and bound to leukocytes in the peripheral blood of treated animals. Comparisons of the groups revealed 53 +/- 4.8% control vascular areal fraction in the placebo group (two animals) and 95.8 +/- 9.4% in the anti-CD11/CD18-treated group (three animals), a statistically significant difference (p = 0.043, t-test).

CONCLUSIONS

These results show that blockade of leukocyte migration into the subarachnoid space by an anti-CD11/CD18 mAb is effective in preventing experimental cerebral vasospasm in nonhuman primates, despite the unaltered presence of hemoglobin in the subarachnoid space. These experimental data support the hypothesis that inflammation plays a role in cerebral vasospasm after SAH.

Expression of endothelin-1 in gingival epithelial cells

OBJECTIVES AND BACKGROUND

Endothelin-1 (ET-1) is a 21-amino acid peptide with multifunctional regulation. ET-1 expresses in various cells during inflammation. The present study aimed to examine the ET-1 expression in oral epithelial cells after infection with the periodontal pathogen and to investigate the presence of ET-1 in human inflamed and uninflamed gingival tissues.

MATERIALS AND METHODS

The KB cells were infected with Porphyromonas gingivalis and the expression level of ET-1 was examined using reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). The immunohistochemical analysis of ET-1 was performed in gingival tissues obtained from patients. In addition, the ET-1 mRNA expression in each tissue was also investigated by RT-PCR.

RESULTS

The expression of ET-1 in KB cells was strongly induced by the P. gingivalis infection. On the other hand, the strong immunoreactivity for ET-1 was observed in the epithelium and vascular endothelial cells of the inflamed gingival tissue. Furthermore, the level of ET-1 mRNA was greater in the inflamed tissues.

CONCLUSION

These results suggested that the expression level of ET-1 in gingival epithelial cells might be enhanced during the periodontal inflammation.

Enrasentan, an antagonist of endothelin receptors

Endothelins are powerful vasoconstrictor agents produced by endothelial cells and identified by Yanagisawa et al. in 1988. Two types of receptors for endothelins have been identified: ET(A) receptors are located on smooth muscle cells of the vascular wall and are responsible for endothelin-induced vasoconstriction while ET(B) receptors are located on endothelial cells and induce these cells to release NO and prostacyclin. Moreover, these peptides not only cause a potent and prolonged vasoconstriction but are also known to enhance cell proliferation and to stimulate extracellular matrix accumulation. High levels of plasma or tissue endothelins have been found in patients with heart failure, diabetes, stroke, primary pulmonary hypertension, liver cirrhosis and other diseases. Given these effects of endothelins, blocking their receptors might be a new way to reduce blood pressure and to treat other illnesses. Accordingly, many endothelin antagonists have been developed and evaluated in animals and humans. Enrasentan is a mixed ET(A) and ET(B) receptor antagonist with a higher affinity for ET(A) receptors, although it cannot be considered a selective antagonist. In an animal model of hypertension and cardiac hypertrophy the drug has reduced blood pressure, prevented cardiac hypertrophy and preserved myocardial function. In rats with hyperinsulinemia and hypertension enrasentan normalized blood pressure and prevented cardiac and renal damage. In rats with stroke the drug reduced the ischemic area in the brain. Enrasentan has been added to conventional treatment in patients with heart failure (NYHA Class 2-3) and no addictive effect of the drug has been observed. This is in contrast with results obtained in animal models and still has not been explained. In conclusion, many possible clinical applications can be suggested for this drug, but further studies are necessary to better evaluate its therapeutic efficacy.

Prepro-endothelin-1 mRNA and its mature peptide in human appendix

Because the precise immunopathological events occurring in appendicitis are not completely understood, possible local production of endothelin-1 (ET-1) in human appendix was investigated. We used immunohistochemistry and in situ hybridization to detect the presence, distribution, and phenotype of ET-1-positive cells and prepro-ET-1 (pp-ET-1) mRNA-expressing cells. ET-1-positive stromal cells and pp-ET-1 mRNA-expressing cells were detected with different distributions and relative frequencies in normal control appendix, histologically normal appendix, and inflamed appendix. Six of 20 histologically normal appendixes from patients with a clinical diagnosis of acute appendicitis had many ET-1-positive stromal cells and high pp-ET-1 mRNA expression, similar to inflamed appendix. Forty percent of the pp-ET-1 mRNA-expressing cells were neutrophils, and the other positive cells were mast cells and macrophages. We suggest that local production of ET-1 by neutrophils and other inflammatory cells could be a molecular sign of focal inflammation in histologically normal appendixes and that ET-1 could be implicated, with other cytokines, in the pathogenesis of appendicitis by inducing appendiceal ischemia through vasoconstriction.

Cardioprotective effects of phosphoramidon on myocardial structure and function in murine Chagas' disease

Chagas' disease is an important cause of cardiomyopathy. Endothelin-1, a vasoactive peptide has been implicated in the pathogenesis of chagasic cardiomyopathy. C57BL/6 x 129sv and CD1 mice were thus, infected with trypomastigotes of Trypanosoma cruzi (Brazil strain) and these infected mice were compared with infected mice treated with phosphoramidon. This compound inhibits endothelin-converting enzyme and neutral endopeptidases and does not affect the growth of the parasite in culture. Phosphoramidon was given in a dose of 10mg/kg for the initial 15 days post-infection None of the C57Bl/6 x 129sv mice died as a result of infection. However, there was marked myocardial inflammation and fibrosis in infected, untreated mice. The hearts of the infected, phosphoramidon-treated mice showed significantly less pathology. Cardiac magnetic resonance imaging of infected mice revealed right ventricular dilation that was less severe in those treated with phosphoramidon. Phosphoramidon-treated CD1 mice survived the acute infection. Transthoracic echocardiography demonstrated left ventricular dilation and reduced percent fractional shortening and relative wall thickness. These alterations were also attenuated as a result of phosphoramidon treatment. These data suggest that endothelin-1 contributes to the pathogenesis of chagasic cardiomyopathy and interventions that inhibit the synthesis of endothelin-1 and/or neutral endopeptidase might have a protective effect on myocardial structure and function in murine Chagas' disease.

Endothelin in human inflammatory bowel disease: comparison to rat trinitrobenzenesulphonic acid-induced colitis

There have been suggestions that endothelins (ET-1, ET-2, ET-3) are involved in the pathogenesis of human inflammatory bowel disease (IBD). Furthermore, the non-selective endothelin receptor antagonist, bosentan, ameliorates colonic inflammation in TNBS colitis in rats. However, no studies have measured the tissue expression and release of endothelins in human IBD in direct comparison to experimental TNBS colitis. Mucosal biopsies were obtained from 114 patients (42 Crohn's colitis, 35 ulcerative colitis and 37 normal) and compared to whole colonic segments from rats with TNBS colitis. ET-1/2 levels were reduced in human IBD but greatly increased in experimental TNBS colitis. RT-PCR indicated ET-2 was the predominant endothelin isoform in human IBD whereas ET-1 prevailed in the TNBS model. No associations were found between human IBD and tissue expression, content or release of ET-1/2. Our study shows, therefore, that unlike TNBS colitis in rats, in which ET-1/2 levels are greatly elevated and ET receptor antagonists are efficacious, there is no significant link between endothelins and human IBD.

Inhibition of vasospasm with lymphocyte function-associated antigen—1 monoclonal antibody in a femoral artery model in rats

Object. The authors have previously shown that a monoclonal antibody (mAb) that recognizes intercellular adhesion molecule—1 (ICAM-1), also known as CD54, when administered systemically inhibits experimental vasospasm in a rat femoral artery model, suggesting that ICAM-1 and leukocyte-endothelial adhesion play a crucial role in the molecular chain of events leading to posthemorrhagic vasospasm. In this report the authors confirm this hypothesis with mAbs directed against lymphocyte function-associated antigen—1 ([LFA-1] CD11a/CD18), the molecule on the surface of leukocytes that interacts with ICAM-1.

Methods. Femoral arteries in 38 Sprague—Dawley rats were isolated and exposed to autologous blood. Twenty-nine animals were then randomized into three groups and received intraperitoneal injections of anti—LFA-1 mAb (10 rats), anti—ICAM-1 mAb (10 rats), or an isotype-matched control mAb (nine rats). Injections were administered at 3 hours and 3, 6, and 9 days after surgery. Before their deaths, six animals underwent spleen harvest, and splenocytes were used in fluorescence-activated cell sorter (FACS) analysis to verify saturation of appropriate binding sites. Animals were killed at 12 days and vessels were harvested for histological study and measurement of the luminal cross-sectional area. Nine animals were randomized as earlier, killed 24 hours after a single injection of mAb, and evaluated for periadventitial infiltration of granulocytes and macrophages. Results of FACS analysis demonstrated saturation of both LFA-1 and ICAM-1 binding sites in animals treated with the respective mAb. The mean ratios of blood-exposed to saline-exposed luminal cross-sectional areas (expressed as the percentage of lumen patency) were 90.1 ± 5.8% (mean ± standard error of the mean) for animals treated with the anti—LFA-1 mAb (p = 0.0218), 94.2 ± 3.3% for animals treated with the anti-ICAM-1 mAb (p = 0.0067), and 62 ± 7.4% for animals treated with the isotype-matched control mAb. Macrophage and granulocyte counts in the periadventitial region were 39.5 ± 3.2/hpf for animals treated with anti—LFA-1 mAb (p = 0.001), 42 ± 3.7/hpf for animals treated with anti—ICAM-1 mAb (p = 0.003), and 72.2 ± 6.2/hpf for control animals.

Conclusions. The systemic administration of anti—LFA-1 or anti—ICAM-1 mAb initiated 3 hours after exposure to autologous blood inhibits the development of delayed chronic vasospasm at 12 days in a rat femoral artery model and leads to a significant reduction in periadventitial inflammatory cells at 24 hours. The authors conclude that blocking the migration of inflammatory cells across the endothelial surface of an artery after adventitial exposure to blood prevents the initiation of biological cascades necessary for the subsequent development of chronic vasospasm.

Gender-related differences in proliferative responses of vascular smooth muscle cells to endothelin-1

Endothelin-1 is an endothelium-derived factor which alters tone and proliferation of vascular smooth muscle and has been implicated in the development of atherosclerosis. Estrogen modulates production of and contractile responses to endothelin-1. Since atherosclerosis is less in estrogen-replete women compared to men, experiments were designed to determine whether or not there were gender-associated differences in proliferative responses to endothelin-1 and effect of estrogen status on those responses. Proliferation of smooth muscle cells derived from coronary arteries of sexually mature, gondally intact male and female and oophorectomized female pigs was determined by thymidine incorporation in the absence and presence of endothelin-1 with and without 17beta-estradiol. Endothelin-1 (10(-9) M to 10(-7) M) significantly inhibited proliferation only in coronary smooth muscle cells from intact female pigs. Addition of beta-estradiol inhibited proliferation of cells from intact females but there was not a synergistic effect with endothelin-1. Gender associated inhibition of smooth muscle proliferation by endothelin-1 may contribute, in part, to cardioprotection noted in estrogen-replete states.