Stem cell factor in mast cells and increased mast cell density in idiopathic and ischemic cardiomyopathy.

BACKGROUND: We compared cardiac mast cell (HHMC) density and the immunological and nonimmunological release of mediators from mast cells isolated from heart tissue of patients with idiopathic dilated (DCM) (n=24) and ischemic cardiomyopathy (ICM) (n = 10) undergoing heart transplantation and from control subjects (n = 10) without cardiovascular disease. METHODS AND RESULTS: HHMC density in DCM (18.4+/-1.6 cells/mm2) and ICM (18.4+/-1.5 cells/mm2) was higher than that in control hearts (5.3+/-0.7 cells/mm2; P<.01). The histamine and tryptase contents of DCM and ICM hearts were higher than those of control hearts. The histamine content of the hearts was correlated with mast cell density (r(s)=.91; P<.001). Protein A/gold staining of heart tissue revealed stem cell factor (SCF), the principal growth, differentiating, and activating factor of human mast cells, in HHMC secretory granules. Histamine release from cardiac mast cells caused by immunological (anti-IgE and rhSCF) and nonimmunological stimuli (Ca2+ ionophore A23187) was higher in patients with DCM and ICM compared with control subjects. Immunological activation of HHMC induced a significantly greater release of tryptase and LTC4 in patients with DCM and ICM compared with control subjects. CONCLUSIONS: Histamine and tryptase content and mast cell density are higher in failing hearts than in control hearts. SCF, present in secretory granules of HHMC, might represent an autocrine factor sustaining mast cell hyperplasia in heart tissue in these patients. The increased local release of fibrogenic factors (eg, histamine, tryptase, and leukotriene C4) might contribute to collagen accumulation in the hearts of patients with cardiomyopathy.

Heterogeneous effects of protamine on human mast cells and basophils.

To investigate the mechanisms of anaphylactoid reactions to protamine, we have examined the in vitro effects of increasing concentrations of protamine (10(-6)-3 x 10(-4) mol litre-1) on the release of preformed (histamine and tryptase) and de novo synthesized (peptide leukotriene C4 (LTC4) or prostaglandin D2 (PGD2)) mediators from human basophils and mast cells isolated from lung parenchyma, heart, skin and synovial tissues. Protamine 10(-6)-3 x 10(-4) mol litre-1 induced release of histamine, but not de novo synthesis of LTC4 from basophils. At concentrations from 10(-5) to 3 x 10(-4) mol litre-1 it induced histamine release from human heart (mean 6.5 (SEM 1.5)%), skin (17.7 (4.1)%) and to a lesser extent from synovial mast cells, but not from lung mast cells. Protamine also caused the release of tryptase from heart mast cells (12.8 (3.2) micrograms/10(7) cells), but did not induce de novo synthesis of LTC4 and PGD2 from lung and skin mast cells. In these experiments cross-linking of IgE by anti-IgE caused release of LTC4 or PGD2 from human basophils or mast cells. These results demonstrate that protamine acted as an incomplete secretagogue, causing the release of preformed mediators from human basophils and mast cells.

Eosinophil granule proteins are selective activators of human heart mast cells.

Eosinophilia in humans is associated with eosinophil infiltration and cardiac localization of eosinophil granule proteins. Eosinophil cationic proteins are responsible for cardiac disease in some patients with eosinophilia. We have investigated the in vitro effect of four eosinophil granule proteins: eosinophil cationic protein (ECP), major basic protein (MBP), eosinophil-derived neurotoxin (EDN) and eosinophil peroxidase (EPO), on mast cells isolated from human cardiac tissue (HHMC). ECP and, to a lesser extent MBP (0.3-3 microM), but not EDN and EPO, stimulated the release of histamine and tryptase from HHMC. This release reaction induced by ECP and MBP was Ca(2+)- and temperature-dependent and was abolished by preincubation with anti-ECP and anti-MBP, respectively. The activation of HHMC by ECP and MBP was abolished by preincubation with 2-deoxy-D-glucose and antimycin A. These data demonstrate that some eosinophil cationic proteins, ECP and MBP, are selective activators of HHMC, thus contributing to the cardiac lesions in patients with eosinophilia.

Eosinophil granule proteins activate human heart mast cells.

Eosinophilia in humans is often associated with heart disease and cardiac localization of eosinophil granule proteins, and several results suggest that granule proteins mediate endomyocardial damage. Here we investigated the in vitro effects of the four principal eosinophil granule proteins (eosinophil cationic protein (ECP), major basic protein (MBP), eosinophil-derived neurotoxin, and eosinophil peroxidase (EPO)) on the activation of effector cells of inflammation (mast cells) isolated from human heart tissue (HHMC). ECP and, to a lesser extent, MBP (0.3-3 microM), but not eosinophil-derived neurotoxin and eosinophil peroxidase stimulated the release of preformed (histamine and tryptase) and the de novo synthesis of vasoactive and proinflammatory mediators (PGD2) from HHMC. Activation of HHMC by ECP and MBP was Ca2+- and temperature-dependent and was abolished by preincubation (15 min, 37 degrees C) with 2-deoxy-D-glucose (10 mM) and antimycin A (1 microM). There was a significant correlation between the maximal percentage of histamine release induced by ECP and anti-IgE from HHMC (rs = 0.73; p < 0.005), by MBP and anti-IgE (rs = 0.79; p < 0.001), and by ECP and MBP (rs = 0.65; p < 0.005). A positive correlation was also found between histamine and tryptase secretion (rs = 0.71; p < 0.001) and between histamine and PGD2 release induced by ECP from HHMC (rs = 0.85; p < 0.001). This is the first demonstration that some eosinophil cationic proteins, namely ECP and MBP, found at the site of heart damage in patients with eosinophilia, act as complete secretagogues on HHMC. This observation indicates another mechanism by which infiltrating eosinophils and their metabolic products cause inflammatory reactions and thus endomyocardial lesions in patients with eosinophilia.

Role of mast cells, basophils and their mediators in adverse reactions to general anesthetics and radiocontrast media.

General anesthetics and radiocontrast media (RCM) can cause anaphylactic or anaphylactoid reactions. These are usually underdiagnosed and underreported, but their incidence is apparently rising. Their pathogenesis is complex and not completely understood, but the release of vasoactive mediators from basophils and mast cells plays a central role. The recent development of in vitro techniques to study the release of preformed (histamine and tryptase) and de novo synthesized mediators (PGD2, LTC4, and PAF) from purified basophils and mast cells has made it possible to quantify the mediator-releasing activity of anesthetics such as muscle relaxants, general anesthetics, opioids, and benzodiazepines and RCM on human basophils and mast cells isolated from lung, skin and heart tissues. The majority of general anesthetics and RCM tested induced only the release of preformed mediators (histamine and tryptase), not of the de novo synthesized eicosanoids. There was wide variability in the response of basophils and mast cells from different donors to the same drug or RCM, presumably due to the releasability parameter. Hyperosmolality is probably not the only factor responsible for basophil and mast cell activation by RCM. The in vitro release of histamine induced by anesthetic drugs and RCM was correlated with the release of tryptase. Given the longer half-life of tryptase than histamine in plasma, measurements of plasma tryptase may become a useful diagnostic tool for identifying adverse reactions to anesthetics and RCM.

Contrast media are incomplete secretagogues acting on human basophils and mast cells isolated from heart and lung, but not skin tissue.

To investigate the mechanisms of anaphylactoid reactions to radiocontrast media, in vitro mediator release induced by three iodinated contrast agents was examined using peripheral blood basophils and mast cells purified from human lung parenchyma, heart, and skin tissues. Three iodinated contrast agents, sodium and meglumine salts of ioxaglic acid, sodium and meglumine salts of ioxithalamic acid, and ioversol, were incubated with basophils purified from peripheral blood and human mast cells isolated and purified from different anatomical sites. Release of preformed (histamine and tryptase) and de novo synthesized mediators (prostaglandin D2 and leukotriene C4) into the supernatans was determined at various contrast medium concentrations after incubation for 60 min. Ioxaglate (0.2-0.3 M), ioxithalamate (0.3-0.5 M), and to a lesser extent ioversol (0.3-0.5 M) induced histamine release from basophils in a concentration-dependent manner. All three induced the release of preformed mediators (histamine and tryptase) from human lung, but not from skin mast cells. They also induced histamine and tryptase release from human heart mast cells. However, they did not induce the de novo synthesis of leukotriene C1 or prostaglandin D2 from human basophils or any type of mast cell examined. Cross-linking of IgE by anti-IgE induced the release of leukotriene C4 or prostaglandin D2 from human basophils or mast cells. Mannitol, an osmotic stimulus, induced the release of histamine from human basophils, but to a lesser extent from mast cells. These results show that different contrast media can differ in their ability to release mediators from enriched preparations of human basophils and mast cells. The three contrast agents examined act on basophils and mast cells as incomplete secretagogues, causing the release of preformed mediators, but not these novo synthesis of chemical mediators. It may be useful to measure plasma tryptase levels to detect adverse reactions caused by iodinated radiographic contrast materials.

Immunological characterization and functional importance of human heart mast cells.

Mast cells are present in normal and even more abundant in diseased human heart tissue and their localization is of particular relevance to their function. Within heart tissue mast cells lie between myocytes and in close contact with blood vessels. They are also found in the coronary adventitia and in the shoulder regions of a coronary atheroma. The density of cardiac mast cells is markedly higher in some patients with myocarditis and dilated cardiomyopathy than in accident victims without cardiovascular diseases. More importantly, in some of these conditions there is in situ evidence of mast cell activation. We have described an original technique to isolate and purify HHMC for in vitro study. This procedure gives viable cells and after stimulation with immunological or non-immunological stimuli they release performed (histamine and tryptase) and newly generated mediators (PGD2 and LTC4). We have demonstrated that HHMC differ from those in other anatomical districts in that they are activated by specific immunological and non-immunological stimuli, and in their relation to the arachidonic acid metabolism, suggesting that the local microenvironment can influence their phenotypic and biochemical characteristics. Our own and other findings suggest that HHMC have complex and significant roles in different pathophysiological conditions involving the cardiovascular system. Direct activation of HHMC by therapeutic and diagnostic substances injected intravenously explains some of the anaphylactoid reactions caused by these agents. HHMC possess Fc epsilon RI and IgE bound to the surface and C5a receptors, which could explain how cardiac mast cells are involved in systemic and cardiac anaphylaxis. Cardiac mast cells and those in human coronary arteries also play a role in the early and late stages of atherogenesis and during ischemic myocardial injury. In conclusion, although studies of HHMC are in their infancy, their in vitro isolation may be useful in identifying additional mediators synthesized and released, stimuli relevant to human pathophysiology, and pharmacological agents selectively modulating the activation of these cells and their mediators. Drugs specifically acting on HHMC or on their mediators may eventually be useful in treating different cardiovascular diseases.

[Analysis of heart rate variability. Background, method, and possible use in anesthesia]. / Analyse der Herzfrequenzvariabilität. Grundlagen, Methodik und mögliche Anwendungen in der Anästhesie.

BACKGROUND AND METHODS. Small, periodic fluctuations in heart rate are well known to physicians, the respiratory sinus arrhythmia (RSA) being the most easily detectable form of this heart rate variability (HRV). Since it is caused by changing activity of the autonomic nervous system (ANS) controlling heart rate, HRV is investigated to gain information on the functional states of the ANS. Recent developments have led to computer-aided processing of EKG signals based on time and frequency domain methods--the latter using power spectral analysis by fast Fourier or autoregressive algorithms--to exactly describe and quantify HRV. Three major regions in the frequency spectrum between 0.03 and 0.5 Hz (the suitable range for shortterm recordings) have been established: (1) a region around the respiratory rate, usually between 0.2 and 0.35 Hz, called high frequency (HF), (2) a region around 0.1 Hz attributed to vasomotor activity feedback, called low (or mid-) frequency (LF), (3) a peak around 0.04-0.05 Hz correlated to thermoregulation, called very low (or low)frequency (VLF). Power spectral density of HRV is now commonly accepted as a measure of autonomic cardiovascular control activity. By studies on vagal or sympathetic blockade, the HF (or RSA) region has been attributed solely to vagal activity, while both parts of the ANS may contribute to the other two, with, however, the vagal part predominating the resting, healthy individuals. CLINICAL APPLICATIONS/ANAESTHESIA. Thus, spectral analysis of HRV provides a measure for quantifying sympatho-vagal balance in its physiological range. Additionally, reduction of HRV along with cardiovascular disease, including hypertension, myocardial infarction, heart failure and sudden cardiac death, as well as with autonomic dysregulation, has been reported. Since is also a striking reduction produced by most anaesthetic agents, RSA and HRV are investigated as measures of anaesthetic depth. There are contradictory data on the influence of ventilation, medication, and co-existing disease on the spectrum, and thus validation of the method is still to be achieved. It has, however, been proven useful in some studies as a parameter for risk assessment of perioperative or post-infarction cardiovascular complications.

Human heart mast cells in anaphylaxis and cardiovascular disease.

All sections of human heart tissue demonstrate tryptase- and chymase-containing mast cells (HHMCs) which have for the first time been isolated, partially purified and studied in vitro. HHMCs contain similar histamine levels as lung and skin mast cells, but tryptase levels are lower than in skin and higher than in lung mast cells. Complement C5a causes rapid dose-dependent release of histamine from HHMCs, but they are refractory to substance P and fMLP. Cross-linking IgE receptors on HHMCs leads to arachidonic acid metabolism through both the cyclooxygenase and 5-lipoxygenase pathways. HHMCs and their vasoactive mediators may be involved in anaphylactic/anaphylactoid reactions in humans and in the pathogenesis of some cardiovascular diseases.

Human heart mast cells: a definitive case of mast cell heterogeneity.

Mast cells and their chemical mediators play a role in cardiac and systemic anaphilaxis. Perivascular and cardiac mast cells have been implicated in the pathogenesis of coronary artery spasm, atherosclerosis, myocardial ischemia, and cardiomyopathy. Despite this, nothing is known about the immunological and biochemical characteristics of the human heart mast cell (HHMC). We have isolated and partially purified HHMC and compared them with mast cells isolated from lung (HLMC) and skin (HSMC) tissues. Cross-linking of the high-affinity receptor for IgE (Fc epsilon RI) by a polyclonal anti-Fc epsilon antibody caused the release of preformed (histamine and tryptase) and de novo synthesized mediators [peptide leukotriene C4 (LTC4) and prostaglandin D2 (PGD2)]. The tryptase content of HHMC (19.4 +/- 1.5 micrograms/10(6) cells) was lower than HSMC (33.4 +/- 2.5 micrograms/10(6) cells) and higher than HLMC (10.6 +/- 1.9 micrograms/10(6) cells). Maximal stimulation of HHMC with anti-IgE led to the release of LTC4 (17.5 +/- 5.1 ng/10(6) mast cells) and PGD2 (17.8 +/- 5.0 ng/10(6) mast cells, whereas HSMC synthesized more PGD2 (65.0 +/- 6.8 ng/10(6) mast cells) and much less LTC4 (< 5 ng/10(6) cells). Recombinant human C5a anaphylatoxin and protamine induced histamine release from HHMC and HSMC, but not from HLMC. Substance P and morphine selectively induced the release of histamine from HSMC, but not from HHMC and HLMC. Compound 48/80 caused histamine release from HSMC and HHMC, but not from HLMC. The pattern of mediators synthesized and the responsiveness of HHMC to different secretagogues appear unique providing strong evidence of human mast cell heterogeneity.

Human heart mast cells. Isolation, purification, ultrastructure, and immunologic characterization.

We have isolated, partially purified, and characterized the mast cells from human heart tissue. The histamine content of left and right ventricles and septum of hearts obtained from 25 patients undergoing heart transplantation was 5.4 +/- 0.6, 5.3 +/- 0.5, and 5.6 +/- 0.5 micrograms/g of wet tissue, respectively. Ultrastructural study of cardiac mast cells revealed scroll, crystal, and mixed granules, homogeneously dense granules, and lipid bodies in the cytoplasm. A mild collagenase digestion was used to disperse the heart mast cells; the average yield was 3.2 +/- 0.6% (range: 0.8 to 13.6%). The average histamine and tryptase content/heart mast cells was 3.3 +/- 0.2 pg (n = 25) and 24.2 +/- 4.3 micrograms/10(6) cells (n = 11), respectively. Survival of cardiac mast cells after overnight culture was 71.9 +/- 5.4% (n = 23). The purification of human heart mast cells can be brought from less than 0.1 to 12% by a combination of low-speed centrifugation over albumin (2%) solution and Percoll gradient. Viability as shown by trypan blue exclusion was greater than 90%. Heart mast cells released histamine in response to immunologic (anti-IgE, anti-Fc epsilon RI, and C5a) and nonimmunologic stimuli (recombinant human stem cell factor, A23187, and compound 48/80) but did not respond to substance P, FMLP, 12-O-tetradecanoylphorbol-13-acetate, or acetylcholine. There was a linear correlation between the percentage of release caused by anti-IgE and anti-Fc epsilon RI, whereas there was no correlation between the release caused by C5a and anti-IgE-mediated stimuli. Cross-linking with anti-IgE of IgE on heart mast cells induced the release of tryptase (10.1 +/- 2.1 micrograms/10(7) cells; n = 10) and the de novo synthesis of PGD2 (17.3 +/- 4.3 ng/10(6) cells; n = 10) and of leukotriene C4 (19.1 +/- 4.5 ng/10(6) cells; n = 10). There was a linear correlation between the percentage of histamine secretion and tryptase release (r = 0.67; p < 0.001) induced by cross-linking of Fc epsilon RI. similarly, there was a significant correlation between percentage of histamine secretion and PGD2 (r = 0.63; p < 0.001) and LTC4 (r = 0.64; p < 0.001) release. Immunoelectron microscopy demonstrated the presence of chymase in cardiac mast cells. Mast cells isolated from human heart can be a useful model with which to study the role of these cells and their mediators in cardiac anaphylaxis and cardiovascular diseases.

Perioperative arrhythmia associated with aortic valve stenosis.

Peri-operative arrhythmia is one of the major complications in anaesthesia for valve replacement surgery in patients with aortic stenosis. In this retrospective study, 58 patients with sinus rhythm were investigated from induction of anaesthesia until arrival at the recovery room by close haemodynamic monitoring and Holter ECG recording. After cardiopulmonary bypass (CPB), they received either lidocaine (L, n = 35) or mexiletine (M, n = 23) via infusion for 24 hours. Pre-bypass incidence was 14% for supraventricular (SPBs) and 19% for ventricular serious arrhythmia (VPBs), i.e. high-grade forms which indicate possible deterioration and may require therapy (for all arrhythmia, incidences were 45 resp. 28%). VPBs was independently related to impaired left ventricular function (11 patients) and preoperative digitalis therapy (20 patients) but not to severity of stenosis, serum concentration of potassium (between 3.3 and 5.2 meq/l), or any other clinical parameters. Post-bypass incidence was SPBs 11% and VPBs 33%, the latter representing a significant increase compared to the first period (p < 0.03)--(all arrhythmia: 26 resp. 40%). VPBs was related to the need for multiple therapy including catecholamines and antiarrhythmic agents other than L or M, but no longer to preoperative parameters nor duration of intraoperative ischaemia. Incidences of arrhythmia for L and M were identical. While in these patients digitalis therapy may account for arrhythmia also in general anaesthesia, in valve replacement there is a post-bypass increase in VPBs which is not fully explained. Since the incidence is 33% in spite of anti-arrhythmic therapy, both administered class IB drugs may not be the best therapeutic approach.