Airway endothelin levels in asthma: influence of endobronchial allergen challenge and maintenance corticosteroid therapy

Endothelins (ETs) are 21 amino acid peptides which, in addition to their other properties, are potent bronchoconstrictors. Whilst there is evidence of the involvement of ET in the pathophysiology of chronic asthma, its contribution to the acute allergic response is undefined. To examine this, we have undertaken segmental bronchoprovocation with allergen and saline at separate sites in six atopic asthmatics receiving treatment with bronchodilators only and six atopic asthmatics additionally receiving treatment with inhaled corticosteroids. Each challenged segment was lavaged 10 min after bronchoprovocation and concentrations of immunoreactive ET were measured in bronchoalveolar lavage fluid. In the non-steroid-treated subjects, there were significantly lower ET levels at the allergen-challenged sites compared to the saline-challenged sites (p<0.05). In the steroid-treated subjects, on the other hand, there was no significant difference between the two sites. Levels of ET at the saline-challenged sites were significantly lower in the steroid-treated subjects compared to the non-steroid-treated subjects (p<0.04). These findings do not support the hypothesis that allergen exposure in asthma results in immediate release of endothelin. However, release at later time-points and a role for endothelin in late-phase bronchoconstriction are not excluded.

Endothelin expression and responsiveness in human ovarian carcinoma cell lines

To elucidate the potential role of endothelins (ETs) as growth regulators in ovarian carcinoma cells in culture, expression of endothelins and their receptors were measured in two ovarian cancer cell lines (PEO4 and PEO14), together with the effect of the exogenous addition of endothelins on the growth of these cell lines in vitro. RT-PCR analysis of mRNA prepared from PEO4 and PEO14 indicated the presence of ET-1 and ET-3 mRNA. Immunoreactive ET-1-like peptide was found in media from cultures of both PEO4 (1.7 +/- 0.4 fmol/10(6) cells/72 h) and PEO14 (20.2 +/- 6.8 fmol/10(6) cells/72 h) cell lines. Radioligand binding studies using 125I-ET-1 and membrane fractions were consistent with PEO4 cells having two receptor sites of either high affinity (Kd = 0.065 nM, Bmax = 0.047 pmol/mg protein) or lower affinity sites (Kd = 0.49 nM, Bmax = 0.23 pmol/mg protein). Studies using membrane fractions of PEO14 cells indicated that this cell line has only a single lower affinity binding site (Kd = 0.56 nM, Bmax = 0.31 pmol/mg protein). However, RT-PCR analysis indicated the presence of mRNA from both ETA and ETB receptors in PEO4 and PEO14 cell lines. Exogenous addition of ETs to PEO4 and PEO14 cells at concentrations of 10(-10)-10(-7)M resulted in specific dose-dependent increases in cell number for ET-1 (with maximum effects at 10(-10) and 10(-9)M for PEO4 and PEO14, respectively) and ET-2 (maximum effects at 10(-8) and 10(-9)M for PEO4 and PEO14, respectively) but not for ET-3. Experiments on the growth of PEO14 cells using BQ123 (ETA-R) antagonist and "antisense" oligonucleotide against the ETA-R, in the absence of exogenous ETs, suggested that immunoreactive ET-1-like material secreted by PEO14 cells can affect their growth in an autocrine manner. These results would be consistent with ET-1 acting as a possible autocrine growth regulator in human ovarian carcinoma cells.

Methods for the isolation, culture and characterisation of equine pulmonary artery endothelial cells

Equine endothelial cells were isolated from the pulmonary artery by enzymatic digestion and grown to confluency. The cells were characterised by positive immunofluorescent staining for von Willebrand factor and NADPH-diaphorase staining for nitric oxide synthase. Measurements of endothelins indicated that there were significant release rates from the cells for up to six hours. Measurements of intracellular calcium concentration showed that the application of bradykinin caused a transient increase in calcium concentration with similar characteristics to those observed in other endothelial cell preparations. These tests verify the endothelial character of these cells and establish the method as a reliable means of producing a primary culture of equine endothelial cells.

[Immunohistochemical study on endothelin in rat kidney]

To elucidate the role of endothelin (ET) in the kidney, we immunohistochemically examined the precise distribution of various forms of ET-peptides in the rat kidney, using specific polyclonal antibodies to each precursor (Big ET-1, Big ET-2 and Big ET-3), and anti-mature ET antibodies. Immunoreactivity of Big ET-1 was localized mainly in some vascular endothelial cells, glomerular mesangial cells and epithelial cells of proximal tubules in the renal cortex and inner-medullary collecting ducts. The distribution of immunoreactivity for mature ETs was similar to those of Big ET-1. These observations suggest that mature ET-1 after conversion from Big ET-1 is secreted from these cells. Since similar findings were obtained using anti-Big ET-2 and anti-Big ET-3 antibodies, these two isopeptides are also considered to have certain physiological actions in the kidney. Immunohistochemical studies for ET-A receptor were also performed. The distribution of this receptor was similar to those of Big ETs and mature ETs. This suggests that secreted ET acts on adjacent cells in an autocrine/paracrine manner in the kidney.

Distribution of endothelin and endothelin-A receptor in the lacrimal glands of the monkey (Macaca fuscata)

Endothelin (ET) is well known to be a potent vasoconstrictor peptide with autocrine and paracrine function. It has been documented that ET is also present in non-muscle tissues. The distribution of ET and ET-A receptor (ET-AR) in the monkey lacrimal gland was investigated by immunohistochemistry. Three adult male monkeys (Macaca fuscata) were perfused with a fixative. The lacrimal glands were then dissected and sectioned. Using rabbit anti-ET and anti-ET-AR antibodies, the immunohistochemical procedure was performed following an ABC technique. Some sections were treated with rhodamine-phalloidin, which selectively binds to actin filaments. ET immunoreactivity was present in stellate-shaped cells located around the alveoli. In sections double-stained with anti-ET antibody and rhodamine-phalloidin, ET immunoreactivity and abundant filamentous actin were identified in the same stellate cells. Immunostaining for ET-AR was also found in the stellate shape cells. The configuration of, and the abundance of actin filaments in the stellate-shaped ET- and ET-AR immunoreactive cells suggest that they are myoepithelial cells, which are contractile and may contribute to the process of lacrimal gland secretion or maintenance of the contour of the glandular endpieces. Our results indicate that endothelin is present in myoepithelial cells of the monkey lacrimal gland.

Protracted elevation of endothelin immunoreactivity in hypothalamo-neurohypophysial system after ischemia

In the present study we investigated the effects of brain ischemia on endothelin expression in the hypothalamo-neurohypophysial system of the rat using the post-embedding immunogold technique for electron microscopy. From 24 hours to six months after ischemia, a relatively high endothelin immunoreactivity was observed in some neurosecretory cells of the supraoptic and paraventricular nuclei as well as in endothelial cells of some microvessels of the hypothalamus and neurohypophysis. The results indicate that ischemia is a potent stimulus for increased production of endothelin. The distribution of endothelin-immunoreactive neurons in the hypothalamus was similar to that of vasopressin and oxytocin, so it seems possible that endothelin participates directly in controlling hormonal synthesis and release from vasopressinergic and oxytocinergic neurons in the hypothalamo-neurohypophysial system.

Endothelin-like immunoreactivity in hippocampus following transient global cerebral ischemia. I. Neuronal and glial cells

The effect of transient, global ischemia on endothelin (ET) localization in CA1 area of hippocampus of the rats was investigated using post-embedding immunogold method. This paper provides immunocytochemical evidence that cerebral ischemia is accompanied by the increase of production of endothelin in CA1 area of the rat. This study focuses on the analysis ET-like immunoreactive neurons and glial cells in hippocampal CA1 area after long-term survival after ischemia: 1 week-12 months. One and two weeks after ischemia appearance of shrunken neurons and significant increase in ET-like immunoreactivity in astroglial cells as well as their proliferation was observed. Six and twelve months--marked immunoreactivity of endothelin in shrunken neurons and in perineuronal microglial macrophages was observed. The data suggest the possibility that the increased intracellular content of endothelin has a role in the development of neuronal death even following a long-term period after ischemia.

Endothelin-like immunoreactivity in hippocampus following transient global cerebral ischemia. II. The blood-brain interphase

The effect of transient, global cerebral ischemia on the distribution of endothelin (ET) in blood-brain barrier (BBB) in CA1 area of hippocampus long-time after ischemia was estimated using post-embedding immunogold technique. ET-like immunoreactivity as a gold particles was localized in all compartments of the blood-brain barrier e.g. in endothelial cells, in pericytes, in periendothelial space including basement membrane, and in astroglial processes. In control animal the density of labelling in all elements of BBB in CA1 area of hippocampus was moderate. ET-like immunoreactivity (ET-like IR) was estimated 1 week-12 months after ischemia. Intense ET-like IR in all elements of BBB was noted 2 and 6 months after ischemia. A potential pathophysiological role of endothelin in cerebral vasospasm in long-time after ischemia is well documented.

Endothelin peptide and receptors in human atherosclerotic coronary artery and aorta

The aim of this study was to determine whether there is an alteration in the distribution or quantity of endothelin (ET) peptide or receptor subtypes in human atherosclerotic arteries. Levels of endogenous ET and big ET-1 detectable by radioimmunoassay in human aorta containing raised atherosclerotic plaques were significantly higher than those in histologically normal tissue (Student's t test, P < .01). Immunohistochemistry revealed ET-like immunoreactivity in endothelial cells lining the vessel lumen, neovascularization, recanalization of organized thrombus, and regions rich in macrophages. Little immunoreactivity was associated with vascular smooth muscle cells (VSMCs). Saturation binding assays with [125I]ET-1 indicated comparable affinities and maximal densities of receptors in the media of diseased and normal coronary arteries. Quantitative autoradiography with subtype-selective radioligands revealed similar small proportions of ETB receptors in the diseased and normal arterial media. In arteries with early and late disease, ETA receptors were localized to medial smooth muscle but were lacking in the VSMCs of the intimal layer, where ETB receptors were absent. ETB receptors were detected on perivascular nerves and lymphoid aggregates. In atherosclerotic arteries, microautoradiography localized ETB receptors to neovascularization and, interestingly, to macrophages. The results of this study indicate that there is an increase in ET and big ET-1 associated with fully developed atherosclerotic plaques. It is likely that this is derived from endothelial cells and macrophages but not VSMCs. ETA receptors predominate in the media of both normal and diseased arteries. ET receptors are deficient in intimal smooth muscle, and ETB receptors, where present, are found on endothelial cells and macrophages.

Tissue concentrations of endothelins and functional effects of endothelin-receptor activation in human arteries and veins

In the present study, the tissue content and functional effects of endothelin-1 and endothelin-3 were examined in human vessels of importance in coronary bypass operations. Human coronary arteries (i.e., the left anterior descending coronary artery) were obtained from eight cardiac valve donors within 6 hours after death, pulmonary arteries were perioperatively obtained from 15 patients operated on because of lung tumors, and internal thoracic arteries and great saphenous and cephalic veins were obtained at coronary bypass operations from a total of 28 patients. Endothelin-1 and endothelin-3 content was quantified by radioimmunoassay. For functional experiments, the vessels were mounted in organ baths for recordings of isometric contractions in response to endothelin-1, endothelin-3, and the endothelinA-receptor agonist sarafotoxin 6c. In all vessels investigated, the endothelin-1 content was higher than that of endothelin-3. The highest levels were found in the left anterior descending coronary artery, followed in declining order by the internal thoracic artery, pulmonary artery, saphenous vein, and cephalic vein. Endothelin-1 contracted all vessels in a concentration-dependent fashion. This effect was enhanced in the left anterior descending and internal thoracic arteries by inhibition of nitric oxide and prostaglandin formation. The contractile effect was attenuated in a concentration-dependent fashion in all vessels by incubation with the endothelinA-receptor blocker BQ-123. Furthermore, contractions evoked by endothelin-1 in the left anterior descending coronary and pulmonary arteries were antagonized by the combined endothelinA- and endothelinB-receptor blocker bosentan. Endothelin-3 contracted the left anterior descending coronary and pulmonary arteries and the saphenous vein, but not the internal thoracic artery, in a BQ-123-sensitive fashion. However, after inhibition with nitric oxide or prostaglandin, endothelin-3 also contracted the internal thoracic artery, and the response in the left anterior descending coronary artery was enhanced. Sarafotoxin 6c evoked a BQ-123-sensitive contraction of the left anterior descending coronary artery. It is concluded that endothelinA receptors mediate the major portion of the vasoconstriction observed on exposure to endothelin-1, endothelin-3, and sarafotoxin 6c in the left anterior descending coronary, pulmonary, and internal thoracic arteries and the saphenous vein. Furthermore, endothelinB-receptor activation, with subsequent formation of nitric oxide or prostaglandin (or both), counteracts the vasoconstrictor response to endothelin in the left anterior descending coronary and internal thoracic arteries, but not in the pulmonary artery or saphenous vein. The present findings therefore suggest that endothelinA-receptor antagonism might prove beneficial in preventing possible endothelin-induced coronary graft spasm.

Establishment of an in vitro cell derived from human angiosarcoma

We have succeeded in the establishment of a human endothelial cell line derived from a human angiosarcoma. These cells grew as monolayers with a "cobble stone" morphology. The cells produced endothelin and showed Weibel-Palade bodies in their cytoplasm. These findings show that the cells have specific differenciated functions, and might be useful for both fundamental endothelial cell biology and biological investigation of angiosarcoma.

Hypoxia decreases constitutive nitric oxide synthase transcript and protein in cultured endothelial cells

Endothelial cell-generated nitric oxide (NO) accounts in large part for the labile vasodilator termed endothelium-derived relaxing factor. Two distinct types of NO synthase exist: a "constitutive' type (cNOS), found in endothelial cells, and an "inducible' enzyme. Endothelial cells sense pO2 levels in the range of 70-20 torr and respond to this hypoxia by inducing transcription of genes which encode the vasoactive proteins PDGF-B and endothelin-1. Exposure of human or bovine endothelial cells to low oxygen tensions results in a profound decrease in the transcript for cNOS and a corresponding fall in cNOS protein levels. The ability of endothelial cells exposed to hypoxia to produce NO in response to bradykinin, a stimulator of cNOS activity, was coordinately impaired. Cobalt inhibited the expression of cNOS transcripts, suggesting a mechanism comparable to that by which oxygen tension regulates expression of other vasoregulatory genes. In the presence of actinomycin-D, hypoxia had no effect on cNOS transcripts, suggesting that new gene transcription is required for cNOS suppression. The reducing agents PDTC and N-Ac did not mimic cNOS gene suppression by hypoxia, suggesting that this suppression is not related to the redox state of the intracellular environment. Thus, regulation of cNOS function in response to environmental factors can occur at the level of gene expression as well as at the level of enzyme activation.

[Endothelin-1 levels in sputum and plasma of asthmatic patient after allergen provocation]

Recently, endothelin-1 (ET-1) has a potent of contractive effect to bronchial smooth muscle, and it suggests that ET-1 contributes to pathophysiology of bronchial asthma. To study the role of endothelin-1 (ET-1) in allergic asthma, we measured ET concentration in plasma and in sputum of nine allergic subjects following allergen provocation by using sandwich-enzyme immunoassay (EIA). ET-1 concentration in plasma were higher during IAR (2.31 +/- 0.24 pg/ml) (0.05 < p < 0.1) and LAR (2.55 +/- 0.27 pg/ml) (0.05 < p < 0.1) than prechallenge value (1.99 +/- 0.23 pg/ml) but there was no significant difference. On the other hand ET-1 concentration in sputum were significantly higher during IAR (14.75 +/- 2.77 pg/ml) (p < 0.05) and LAR (18.51 +/- 4.57 pg/ml) (p < 0.05) than prechallenge values (4.29 +/- 2.55 pg/ml). Thus these results suggest that ET-1 play a role of allergic bronchoconstraction (IAR and LAR) after allergen challenge.

Expression of endothelin-1 gene and protein in human granulosa cells

Previous studies in animal models indicated an autocrine/paracrine action of endothelin-1 (ET-1) in the ovary. We now report evidence on the presence of ET-1 in human ovary during reproductive life. Immunohistochemical and in situ hybridization studies demonstrated a positive signal into cytoplasm of granulosa cells (GC) of follicles at different growth stages. The concentration of ET-1-like immunoreactivity (ET-1-LI) was also measured by a specific RIA in human follicular fluid (FF). FF samples were obtained from women in an in vitro fertilization program undergoing gonadotropin stimulation (group A; n = 24) or no treatment (group B; n = 7). The mean (+/-SD) ET-1-LI FF level in group A (4.85 +/- 2.06 pg/mL) was significantly higher than that in group B (1.29 +/- 0.43 pg/mL; P < 0.01), whereas the corresponding mean plasma levels were not significantly different and were not correlated to respective FF values. Our results indicate for the first time the presence of ET-1 and its messenger ribonucleic acid in the GC of the human ovary. The higher ET-1-LI levels found in the FF from women undergoing gonadotropin treatment suggest a modulation by gonadotropins and/or ovarian steroids of ET-1 production by GC.

Increased endothelin expression in a rat cardiac allograft model of chronic vascular rejection

Endothelins (ET) are potent vasoconstrictors that are directly mitogenic for vascular smooth muscle cells and fibroblasts. It is possible that the vasoconstrictor and mitogenic effects of ET could play a significant role in the vascular remodeling process that occurs in chronic vascular rejection (CVR). We have previously shown that cardiac allografts in the indefinitely surviving major histocompatibility complex identical WF.1L (RT1(1)) to Lewis (LEW) (RT1(1)) inbred rat strain combination provide a highly reproducible model of progressive CVR. The objective of this investigation was to measure endothelin-1 ventricular content of WF.1L-LEW cardiac allografts and to determine the immunohistochemical patterns of ET cellular reactivity at well defined posttransplant time periods. Data were compared with those obtained in similar studies of LEW-LEW syngeneic: heart grafts as well as all recipients' own hearts. The ventricular ET-1 content of the WF.1L cardiac allografts was markedly higher (4.3-, 7.0-, and 4.8-fold at 20, 40, and 60 days, respectively) than in corresponding recipients' hearts. Also, the increase in ventricular ET-1 levels as compared with the recipients' hearts rose significantly only in the allograft group. No comparable differences were observed in the syngeneic heart graft controls. Allografts consistently showed ET staining of intimal myocytes at sites of occlusive and subocclusive intimal proliferation associated with CVR. Allografts also showed ET cellular staining in areas of reparative fibrosis associated with indolent interstitial rejection and ischemic myocardial damage. The results of this study strongly suggest that ET may play a significant role in the pathogenesis of CVR.

Co-expression of endothelin-1 and endothelin-converting enzyme-1 in patients with chronic rhinitis

Several studies have suggested an important role for endothelin in the pathophysiology of the upper and lower respiratory tract. In the present study, we have investigated the localization of endothelin-1 (ET-1) and endothelin-converting enzyme-1 (ECE-1) messenger RNAs(mRNAs) and immunoreactivities in the human nasal mucosa by immunohistochemistry and in situ hybridization. Inferior turbinates were obtained from 32 patients at surgery. Histopathologic examination of nasal biopsy specimens revealed that 17 patients had chronic inflammation and 15 patients had normal mucosa. Immunostaining for ET-1 and ECE-1 was seen in the surface epithelium, endothelial cells, submucosal glands, and infrequently in vascular smooth muscle cells, in all subjects. There was significantly more staining for ET-1 and ECE-1 in nasal glands and inflammatory cells in patients with chronic inflammation than in those with normal nasal mucosa. In patients with chronic inflammation, strong immunoreactivity for ECE-1 was seen over inflammatory cells. In situ hybridization showed abundant expression of ET-1 and ECE-1 mRNAs over the surface epithelium, glands, vessels, and inflammatory cells. Both immunohistochemistry and in situ hybridization demostrated the expression of ET-1 and ECE-1 immunoreactivities and mRNAs in similar sites, and also independently. The present findings demonstrate the co-expression of ET-1 and its converting enzyme in the human nasal mucosa and suggest a possible role for the endothelin system in the pathogenesis of chronic rhinitis.

Localisation of immunoreactive factor VIII, nitric oxide synthase, substance P, endothelin-1 and 5-hydroxytryptamine in human postmortem middle cerebral artery

This pre-embedding electron-immunocytochemical study investigated the localisation of endothelial (type III) and neuronal (type I) isoforms of nitric oxide synthase, substance P, endothelin-1 and 5-hydroxytryptamine in the human middle cerebral artery taken up to 40 h postmortem. To ¿recover' from the anoxic period some of the vessels were incubated in oxygenated Krebs solution prior to the immunoprocedure. At this long postmortem time, immunoreactivity to type III and type I nitric oxide synthase, substance P, endothelin-1 and 5-hydroxytryptamine was found in a subpopulation of intact cells present in the vessel intima; immunoreactivity to type I nitric oxide synthase was also observed in a subpopulation of adventitial perivascular nerve fibres. Cultures of the cells from the intima of the postmortem vessels showed that the cells were proliferating and positive immunoreactivity to factor VII identified them as endothelial cells. The results therefore indicate that even after up to 40 h postmortem, endothelium of human middle cerebral artery is immunoreactive for a number of vasoactive agents and perivascular nerve fibres show nitric oxide synthase immunoreactivity.

Endothelin-1 and its receptor in hypertrophic cardiomyopathy

Endothelin-1, a potent vasoconstrictor produced by vascular endothelial cells, activates the hypertrophic program in cultured heart muscle cells. However, the role of endothelin-1 in cardiac hypertrophy in humans is unknown. Therefore, we studied hypertrophic cardiomyopathy patients with normal pulmonary arterial pressure, in whom cardiac hypertrophy is a specific feature of the disease. Radioimmunoassay with a monoclonal antibody to human endothelin-1 showed that the plasma level of immunoreactive endothelin was more than twofold higher in hypertrophic cardiomyopathy patients than in control subjects (P < .005). In situ hybridization analysis of endomyocardial biopsy specimens showed positive signals of endothelin-1 type A receptor mRNA in ventricular myocytes of all specimens. The receptor expression in ventricular myocytes was similar between hypertrophic cardiomyopathy patients and control subjects. We propose that endothelin-1 might represent an important factor involved in hypertrophic cardiomyopathy. Whether endothelin-1 plays a causal role in cardiac hypertrophy or is a marker of its occurrence needs to be clarified.

Localization of endothelin peptides in human kidney

We investigated the synthesis and localization of endothelin isoforms in the human kidney using the reverse-transcriptase polymerase chain reaction (RT-PCR) and immunocytochemistry. PCR products corresponding to the expected size for mRNA encoding ET-1, ET-2 and ET-3 were found in homogenates of renal medulla, cortex and vessels from each of five individuals. Using four rabbit polyclonal antibodies to assess the distribution of mature ET, Big ET-1, Big ET-2 and Big ET-3 immunoreactivity in the human kidney, mature IR ET localized to the cytoplasm of endothelial cells lining intra-renal blood vessels including interlobular and arcuate arteries, arterioles and adjacent arcuate veins, all of which showed strongly positive staining. IR Big ET-1 co-localized with the mature peptide. No specific staining was detected within these anatomical regions when pre-immune sera were substituted or primary antibody omitted. Mature IR ET also localized to the cytoplasm of endothelial cells within the glomerulus. Other capillary endothelial cells did not stain, and other structures stained only faintly by comparison. IR Big ET-2 and Big ET-3 could not be detected. These results show that human kidney contains mRNA encoding all three peptide isoforms, but only mature ET and Big ET-1 peptides could be detected by immunocytochemical staining. This provides further evidence that ET-1 may function as a renal peptide in humans, as it is locally synthesized within the kidney.

Endothelin in bronchoalveolar lavage fluid is increased in lung-transplanted patients

Animal studies have shown increased endothelin in bronchoalveolar lavage (BAL) fluid during unmodified rejection. We performed radioimmunoassay of endothelin in 59 BAL fluid samples from ten patients at different times after lung transplantation. All patients received immunosuppressive therapy (cyclosporin, azathioprine and methylprednisolone). Reference BAL samples were obtained from six controls. Of the 59 test samples, five were collected during rejection episodes, confirmed by clinical outcome, BAL cytology and radiology (rejection group), and 19 were taken during bacterial, viral or fungal infection (infection group). The endothelin content of BAL (pg/ml) was significantly greater in the rejection group than in the infection group (61.1 +/- 3.8 vs 40.6 +/- 2.0) or in the 35 samples taken in uncomplicated course after lung transplantation (40.9 +/- 5.4), p < 0.01. The endothelin level in BAL fluid from the controls was only 3.0 +/- 1.4 pg/ml, significantly less (p < 0.005) than in all the lung-transplanted groups. Endothelin in BAL fluid thus was increased after lung transplantation, and still further during rejection.

Increased levels of endothelin-1 in bronchoalveolar lavage fluid of patients with lung allografts

The aim of the present study was to determine levels of endothelin-1 in bronchoalveolar lavage fluid and in plasma in patients with lung and heart-lung allografts. The aim was based on the hypothesis that levels of endothelin-1 are elevated in the bronchoalveolar lavage fluid of patients with lung allografts. Patients (n = 23) undergoing heart-lung (n = 8), single-lung (n = 10), or bilateral lung (n = 5) transplantation were included in the study. In patients with single-lung allografts, endothelin-1 levels were analyzed in bronchoalveolar lavage fluid from both the transplanted and the nontransplanted, native lung. The level of endothelin-1 was also analyzed in bronchoalveolar lavage fluid from 12 patients who did not undergo transplantation. Transbronchial biopsies and bronchoalveolar lavage were done routinely or when clinically indicated on 64 different occasions, between 2 and 104 weeks after transplantation. The level of endothelin-1 was measured in bronchoalveolar lavage fluid and plasma by radioimmunoassay. Immunoreactive endothelin-1 was detectable in bronchoalveolar lavage fluid from all patients. The concentration of endothelin-1 in bronchoalveolar lavage fluid from transplanted lungs (2.94 +/- 0.30 pg/ml, n = 64) was significantly higher compared with that in bronchoalveolar lavage fluid from patients without allografts (0.86 +/- 0.20 pg/ml, n = 12, p < 0.01). In patients who received single-lung transplantation because of emphysema, the level of endothelin-1 in bronchoalveolar lavage fluid from the transplanted lung was significantly greater than that from the native lung (5.61 +/- 1.9 versus 0.39 +/- 0.05 pg/ml, p < 0.05). Concentrations of endothelin-1 in bronchoalveolar lavage fluid did not correlate with grade of rejection, infection, or time after transplant. Plasma levels of endothelin-1 were unchanged with pulmonary rejection. These results indicate that endothelin-1 is released into bronchi of transplanted human lungs. The release is not associated with rejection or infection. Because of its potent mitogenic properties, endothelin-1 may have a potential impact in the development of posttransplant complications such as bronchiolitis obliterans.

Validation of endothelin (ET) immunoreactivity in human bile by HPLC. Comparison of biliary ET concentration in liver transplant recipients with values obtained during cholecystectomy

High endothelin (ET) concentrations were recently detected in human bile after orthotopic liver transplantation (OLT). In the present study we compared biliary ET/big-ET levels measured by radioimmunoassay (RIA) in liver graft recipients (n = 37) with levels measured in non-transplant patients during cholecystectomy (n = 38) to clarify the influence of transplantation on the levels of biliary ET peptides. HPLC elution profiles of biliary ET were analyzed for characterization of ET peptide composition and validation of RIA analysis in bile extracts. Mean ET/big-ET levels in the common bile duct after OLT were significantly elevated (ET, 20.9 +/- 15; big-ET, 39.2 +/- 19 fmol/ml) compared to levels in non-transplant patients (ET, 5.7 +/- 4.9; big-ET, 12 +/- 8 fmol/ml). Highest ET/big-ET levels were measured in the gall bladder during cholecystectomy (ET, 61.7 +/- 41; big-ET, 75 +/- 28 fmol/ml). ET and big-ET levels were correlated by linear regression. HPLC analysis reveals the presence of high levels of ET/big-ET in human bile. Biliary ET mostly represents ET-1. High biliary ET levels after OLT appear to be derived from active endothelial secretion and probably reflect hepatic endothelial stress after preservation/ reperfusion. High biliary ET levels could be involved in the mediation of functional cholestatic syndromes after OLT.

Reactions of astrocytes and microglial cells around hematogenous metastases of the human brain. Expression of endothelin-like immunoreactivity in reactive astrocytes and activation of microglial cells

An immunohistochemical study was made on the peritumoral gliosis which is produced around hematogenous metastases of the human brain. The material was derived from 73 autopsy cases with different primary malignancies and six control cases without evidence of brain disease. Reactive astrocytes of hypertrophic and gemistocytic types were present around and within all the metastases. Eighty-five percent of the cases with metastases showed expression of endothelin-like immunoreactivity in the peritumoral astrocytes. Such immunoreactive astrocytes were not present in the normal controls but have previously been found in reactive astrocytes around infarcts, lacunas, inflammatory and degenerative brain diseases. The endothelin-like immunoreactivity probably reflects an increased intracellular content of endothelin. If this peptide is released from the reactive astrocytes it may act as a mitogen and influence microcirculation by inducing vasoconstriction. Activation of microglial cells, detected by ferritin immunohistochemistry, was another frequent and widespread glial cell alteration around the metastases. In conclusion, the reactive gliosis, which is formed around metastases involves activated astrocytes as well as activated microglial cells. Both cell types can release numerous biologically active compounds which may influence the structure and function of the brain tissue around the metastases.