Effects of sodium cromoglycate and nedocromil sodium on histamine secretion from human lung mast cells.

Sodium cromoglycate and nedocromil sodium produced a dose dependent inhibition of histamine secretion from human pulmonary mast cells obtained by bronchoalveolar lavage and by enzymatic dissociation of lung parenchyma. Both compounds were significantly more active against the lavage cells than against the dispersed lung cells, and nedocromil sodium was an order of magnitude more effective than sodium cromoglycate against both cell types. Tachyphylaxis was observed with the parenchymal cells but not with the lavage cells. Nedocromil sodium and sodium cromoglycate also inhibited histamine release from the lavage cells of patients with sarcoidosis and extrinsic asthma.     

Hypoxia and lung mast cells: influence of disodium cromoglycate.

Rats kept in 10% O2 for three or more weeks developed mast cell hyperplasia in the lungs, especially round the alveoli and the small peripheral blood vessels, which became thickened during chronic hypoxia. There was a significant correlation between the degree of right ventricular hypertrophy (RVH) and the numbers of alveolar and small vessel mast cells. However, mast cell hyperplasia developed more slowly than RVH. Daily treatment with disodium cromoglycate failed to prevent RVH in hypoxic conditions but was associated with retardation of growth in both hypoxic and control rats. Neither acute nor chronic hypoxia increased the degree of degranulation in the lung mast cells.     

Role of inflammation in nocturnal asthma.

BACKGROUND--Nocturnal airway narrowing is a common problem for patients with asthma but the role of inflammation in its pathogenesis is unclear. Overnight changes in airway inflammatory cell populations were studied in patients with nocturnal asthma and in control normal subjects. METHODS--Bronchoscopies were performed at 0400 hours and 1600 hours in eight healthy subjects and in 10 patients with nocturnal asthma (> 15% overnight fall in peak flow plus at least one awakening/week with asthma). The two bronchoscopies were separated by at least five days, and both the order of bronchoscopies and site of bronchoalveolar lavage (middle lobe or lingula with contralateral lower lobe bronchial biopsy) were randomised. RESULTS--In the normal subjects there was no difference in cell numbers and differential cell counts in bronchoalveolar lavage fluid between 0400 and 1600 hours, but in the nocturnal asthmatic subjects both eosinophil counts (median 0.11 x 10(5) cells/ml at 0400 hours, 0.05 x 10(5) cells/ml at 1600 hours) and lymphocyte numbers (0.06 x 10(5) cells/ml at 0400 hours, 0.03 x 10(5) cells/ml at 1600 hours) increased at 0400 hours, along with an increase in eosinophil cationic protein levels in bronchoalveolar lavage fluid (3.0 micrograms/ml at 0400 hours, 2.0 micrograms/l at 1600 hours). There were no changes in cell populations in the bronchial biopsies or in alveolar macrophage production of hydrogen peroxide, GM-CSF, or TNF alpha in either normal or asthmatic subjects at 0400 and 1600 hours. There was no correlation between changes in overnight airway function and changes in cell populations in the bronchoalveolar lavage fluid. CONCLUSIONS--This study confirms that there are increases in inflammatory cell populations in the airway fluid at night in asthmatic but not in normal subjects. The results have also shown a nocturnal increase in eosinophil cationic protein levels in bronchoalveolar lavage fluid, but these findings do not prove that these inflammatory changes cause nocturnal airway narrowing.     

Graft-infiltrating cells expressing a CD200 transgene prolong allogeneic skin graft survival in association with local increases in Foxp3(+)Treg and mast cells

Expression of the molecule CD200 has been reported to increase allograft survival by suppression of inflammation and acquired immunity. In previous studies we have shown that increased skin and cardiac allograft survival in transgenic mice over-expressing CD200 (CD200(tg)) occurs in association with increased intra-graft expression of mRNAs for genes associated with altered T cell subset differentiation. We investigated changes in graft-infiltrating cells, Treg and mast cells in skin grafts post transplantation into control or CD200(tg) mice, using focused gene array and real-time PCR to assess altered gene expression, and FACS, immunohistology and MLC to determine numbers/function of those cells. Graft-infiltrating cells isolated from CD200(tg) recipients suppressed induction of CTL from control lymph node cells in vitro, and contained increased numbers of infiltrating, non-degranulating, mast cells and Foxp3(+)Treg. Mast cells were also evident in graft tissue of control animals, but there these cells showed evidence for degranulation, and fewer Foxp3(+)Treg were present than was the case of CD200(tg) mice. The infusion of a competitive inhibitor of CD200:CD200R interactions, CD200(tr), at high concentrations (50μg/mouse iv) caused rapid rejection of grafts in CD200(tg) mice, mast cell degranulation within graft tissue, and a decrease in Treg infiltrates. These effects were attenuated by simultaneous infusion of the mast cell stabilizer, sodium cromoglycate. We conclude that CD200 expression contributes to graft prolongation through local suppression of mast cell degranulation, attraction/expansion of Treg, and attenuation of T cell effector activation.     

The relationship of mast cells and their secreted products to the volume of fibrosis in posttransplant hearts.

A series of 96 posttransplant endomyocardial biopsies taken from 11 patients was subjected to quantitative analysis of mast cells and fibrosis. Ultrastructural analysis showed that mast cell numbers were increased and there was obvious degranulation in some posttransplant hearts. Activated mast cells and their secreted products, which contain heparin and histamine, are toxic to the hearts and may contribute to interstitial and perimyocytic fibrosis. The numbers of mast cells and granules were correlated with volume of fibrosis (r = 0.63, P less than 0.025; r = 0.73, P less than 0.01). There were differences between the release of mast cell granule contents seen in the posttransplant hearts and the rapid and massive reaction of anaphylactic degranulation of mast cells. Some mast cells progressively lost their dense granule contents, displaying a variety of piecemeal degranulation that indicates a slow degranulation process. These events occurred from the first week; they lasted from weeks to months. The fibrosis developed quickly in the cases with more mast cells and degranulation. The cases with fewer mast cells and granules showed only mild increases in the volume of fibrosis. Mast cells appeared as early as the first posttransplantation week. Patients with greater numbers of mast cells underwent more severe rejection episodes. This study demonstrated that mast cells play an early and important role in the perimyocytic and interstitial fibrosis of posttransplant hearts. Mast cells may also be important in the inflammatory process of rejection reaction. The severity of fibrosis appears related to the density of mast cells and their granules.     

Effect of sleep deprivation on overnight bronchoconstriction in nocturnal asthma.

Nocturnal cough and wheeze are common in asthma. The cause of nocturnal asthma is unknown and there is conflicting evidence on whether sleep is a factor. Twelve adult asthmatic subjects with nocturnal wheeze were studied on two occasions: on one night subjects were allowed to sleep and on the other they were kept awake all night, wakefulness being confirmed by electroencephalogram. Every patient developed bronchoconstriction overnight both on the asleep night, when peak expiratory flow (PEF) fell from a mean (SE) of 418 (40) 1 min-1 at 10 pm to 270 (46) 1 min-1 in the morning, and on the awake night (PEF 10 pm 465 (43), morning 371 (43) 1 min-1). The morning values of PEF were, however, higher (p less than 0.1) after the awake night and both the absolute and the percentage overnight falls in PEF were greater when the patients slept (asleep night 38% (6%), awake night 20% (4%); p less than 0.01). This study suggests that sleep is an important factor in determining overnight bronchoconstriction in patients with nocturnal asthma.     

Role of mast cells in the pathogenesis of hypersensitivity pneumonitis.

To examine the possibility that mast cells have a central role in the pathogenesis of hypersensitivity pneumonitis, 20 patients with this disease were studied with the aim of seeking evidence for mast cell degranulation. The number of mast cells recovered by bronchoalveolar lavage from patients with hypersensitivity pneumonitis was more than 1,000 times greater than those recovered from normal individuals. Furthermore, discontinuation of antigen exposure resulted in an increase in the number of mast cells observed, consistent with the possibility that antigen exposure had induced mast cell degranulation. Cessation of antigen exposure also resulted in a rapid decrease in the number of neutrophils and eosinophils recovered by lavage, followed by an increase in the number of T8+ T lymphocytes present. In each case the time course of the changes was consistent with the possibility that mast cell degranulation had been important in regulating the number of the immune and inflammatory cells present in the lung. Histamine was present in lavage fluid supernatant from patients with hypersensitivity pneumonitis. The amount of histamine present was, however, closely correlated with the number of mast cells present and not with the interval since last antigen exposure. Delay in separating cells from lavage fluid supernatant resulted in an increase in histamine content. These results suggest that the free histamine in lavage fluid resulted from the degranulation of mast cells induced by the lavage procedure as histamine released in vivo has a short half life. We suggest that hypersensitivity pneumonitis results from a "late phase reaction" initiated by antigen induced mast cell degranulation.     

Morbidity in nocturnal asthma: sleep quality and daytime cognitive performance.

Most patients with asthma waken with nocturnal asthma from time to time. To assess morbidity in patients with nocturnal asthma nocturnal sleep quality, daytime sleepiness, and daytime cognitive performance were measured prospectively in 12 patients with nocturnal asthma (median age 43 years) and 12 age and intellect matched normal subjects. The median (range) percentage overnight fall in peak expiratory flow rate (PEF) was 22 (15 to 50) in the patients with nocturnal asthma and 4 (-4 to 7) in the normal subjects. The patients with asthma had poorer average scores for subjective sleep quality than the normal subjects (median paired difference 1.1 (95% confidence limits 0.1, 2.3)). Objective overnight sleep quality was also worse in the asthmatic patients, who spent more time awake at night (median difference 51 (95% CL 8.1, 74) minutes), had a longer sleep onset latency (12 (10, 30) minutes), and tended to have less stage 4 (deep) sleep (-33 (-58, 4) minutes). Daytime cognitive performance was worse in the patients with nocturnal asthma, who took a longer time to complete the trail making tests (median difference 62 (22, 75) seconds) and achieved a lower score on the paced serial addition tests (-10 (-24, -3)). Mean daytime sleep latency did not differ significantly between the two groups (2 (-3, 7) minutes). It is concluded that hospital outpatients with stable nocturnal asthma have impaired sleep quality and daytime cognitive performance even when having their usual maintenance asthma treatment.     

Breathing patterns during sleep in patients with nocturnal asthma.

Breathing patterns early and late in the night, at the same sleep stage, were compared in six healthy subjects and 15 adults with nocturnal asthma, to try to identify changes of overnight bronchoconstriction, and breathing patterns at different sleep stages, to see whether there were changes related to sleep stages that were indicative of bronchoconstriction. Despite an average 31% fall in FEV1 overnight in the patients with asthma, neither breathing frequency nor expiratory time, which might be expected to change during bronchoconstriction, was different early in the night from late in the night, nor did they differ between sleep stages. There was no evidence of asynchronous movement of the chest and abdomen in any patient. This study did not identify any abnormality of breathing pattern that would indicate the development of nocturnal asthma without the need to awaken the patient.     

Inhibition of aspirin-induced bronchoconstriction by sodium cromoglycate inhalation.

Five patients with asthma and severe aspirin hypersensitivity were challenged on separate days with increasing doses of aspirin given by mouth, starting with 5 mg, until a reduction in FEV1 greater than 15% was obtained. Sodium cromoglycate in doses of 20-40 mg inhibited the bronchoconstrictive reaction not only when inhaled before the challenge but also after it, at a time when progressive reduction in FEV1 values was taking place. According to these results, it seems reasonable to postulate sequential mast cell degranulation and liberation of mediators of anaphylaxis as the mechanism through which aspirin induces bronchoconstriction in aspirin-sensitive asthmatics. The differences between bronchial provocation tests and oral challenge with aspirin are stressed.     

Increased mast cells and neutrophils in submucosal mucous glands and mucus plugging in patients with asthma

BACKGROUND: Mucus plugging of the airways is invariably seen in cases of fatal asthma, mucus production is associated with asthma attacks, and the area of submucosal glands is increased in asthma. Mediators secreted from mast cells and neutrophils can stimulate mucous gland secretion. A study was undertaken to count the mast cells and neutrophils in submucosal glands and to relate cell numbers to the presence of mucus in the airway lumen. METHODS: Cartilaginous airways obtained at necropsy from cases of fatal asthma (n=8), non-fatal asthma (n=8), and control cases (n=8) were examined. Contiguous transverse sections were stained for mast cell tryptase and neutrophil elastase, and with Periodic Acid Schiff solution to identify mucus. Mucous gland area, lumen area, and the percentage of the relaxed lumen area occupied by mucus (mucus occupying ratio, MOR) were measured. Mast cells (intact and degranulated) and neutrophils per area of submucosal gland were calculated. RESULTS: Compared with controls, the cases of fatal asthma had increased mucous gland area, MOR, percentage of degranulated mast cells, and numbers of neutrophils in the submucosal glands (p<0.05). In cases of non-fatal asthma the MOR and the numbers of mast cells and neutrophils in the submucosal glands were increased (p<0.05). When all cases were pooled together, the MOR correlated with the total number of mast cells (r=0.55, p=0.005) and with the number of degranulated mast cells in the submucosal glands (r=0.51, p=0.013), but not with the number of neutrophils (r=0.21, p=0.121). CONCLUSION: These results show that mucous gland area, MOR, and mucous gland inflammation are increased in asthma and that degranulation of mast cells may contribute to secretion of mucus into the lumen in cases of fatal asthma.     

Posture and nocturnal asthma.

To investigate whether the supine posture caused sustained bronchoconstriction and could thus contribute to the development of nocturnal asthma, nine patients with nocturnal asthma were studied on two consecutive days, lying supine for four hours on one day and sitting upright for four hours on the other, the order of the two postures being randomised. Peak expiratory flow (PEF), forced expiratory volume in one second (FEV1), and forced vital capacity (FVC) were measured immediately before and after the four hours and over the subsequent hour. There was no significant difference between the erect and supine posture for PEF (248 v 248 l/min), FEV1 (1.31 v 1.22 l), or FVC (2.34 v 2.28 l) at the end of the four hours, nor did any significant change develop subsequently. Thus the supine posture is not associated with prolonged bronchoconstriction. As each patient had previously shown an average overnight fall in PEF of more than 20%, this study strongly suggests that the supine posture is not an important cause of overnight bronchoconstriction.     

Mast cells and inflammation

The prominent role for mast cells in the inflammatory response has been increasingly well documented in recent years. Mast cells not only contribute to maintain homeostasis via degranulation and to generate IgE-mediated allergic reactions, but also sit at a major crossroads for both innate and adaptive immune responses. The part played by mast cells in chronic inflammatory diseases such as rheumatoid arthritis and multiple sclerosis identifies mast cells as a valuable treatment target in these diseases. Tyrosine-kinase inhibitors targeting the c-Kit mast cell receptor have been found effective in treating rheumatoid arthritis, asthma, and multiple sclerosis. When used in combination with other available drugs, tyrosine-kinase inhibitors may improve the therapeutic management of these diseases.     

Does sleep cause nocturnal asthma?

The effects of sleep interruption and deprivation were studied in 21 patients with nocturnal asthma. Seven patients were awakened at 0200 on three consecutive night and exercised for 15 minutes. This produced no significant improvement in the overnight fall in peak expiratory flow rate (PEFR) compared with a control night of uninterrupted sleep. In a second study in five patients PEFR was measured at two-hourly intervals to estimate the time of onset of the nocturnal fall in PEFR. On three subsequent nights they were awakened and exercised one hour before this time. This also failed to prevent a fall in PEFR by 0600. Eleven patients, who had followed a similar protocol to the second study, were kept awake until after 0300 or later, and PEFR was observed hourly. Six of them (group A) sustained their usual fall in PEFR while awake, proving that sleep was not responsible for their nocturnal asthma. Five patients (group B) showed little fall in PEFR until they were allowed to sleep, when an appreciable fall was noted on waking at 0600. When sleep deprivation was repeated in two patients in group B, however, they sustained falls in PEFR while still awake. We conclude that the circadian rhythm in PEFR is often in phase with the timing of sleep but sleep does not cause nocturnal asthma. Disruption of sleep therefore has no apparent value in the treatment of nocturnal asthma.     

Histamine levels and cardiovascular responses during splenectomy and splenorenal shunt formation in a patient with systemic mastocytosis

Systemic mastocytosis is a rare disorder characterised by the infiltration of many tissues by abnormal numbers of mast cells. Life-threatening episodes of bronchospasm and hypotension are common in response to a variety of triggers which cause mast cell degranulation. We present the case history of a patient with severe mast cell disease who successfully underwent splenectomy and portocaval anastomosis. Peri-operative therapy was directed towards mast cell stabilisation, and histamine-releasing drugs were avoided. Cardiovascular data, together with blood histamine levels and thrombin times, indicated that mast cell degranulation did not occur. A review of the current literature concerning mast cell disease as it relates to anaesthesia is presented and suggestions for the safe management of such cases are given.     

Dose-response study of sodium cromoglycate in exercise-induced asthma.

Ten patients with exercise-induced asthma participated in a single-blind dose-response study comparing the protective effect of inhaled sodium cromoglycate in increasing concentrations from 2 to 40 mg/ml. Saline was used as a control. Effects were assessed from the mean maximal percentage fall in forced expiratory volume in one second (FEV1) after the patients had run on a treadmill for eight minutes. There was slight bronchodilation evident from the increase in baseline FEV1 after inhalation of sodium cromoglycate, the difference reaching statistical significance with the highest concentration (5.7%, p less than 0.05). After exercise the maximal percentage falls in FEV1 (means and SEM) after saline and after sodium cromoglycate at 2, 10, 20, and 40 mg/ml were 37.3 +/- 4.7, 17.3 +/- 4.1, 10 +/- 3.3, 7.6 +/- 2.4, and 12 +/- 2.9. Sodium cromoglycate inhibited the exercise-induced fall in FEV1 at all the concentrations used in the study (p less than 0.001) and its inhibitory effect increased from 2 to 20 mg/ml. The mean FEV1 returned to baseline values within 15 minutes at higher concentrations of sodium cromoglycate (20 and 40 mg/ml) and a small bronchodilator effect was noted at 30 minutes. The findings suggest that the protective effect of sodium cromoglycate in exercise asthma is dose related. At higher concentration the drug suppresses chemical mediator release from the lung mast cells and may also modify the bronchial reactivity to release mediators.     

Anaesthetic management of emergency caesarean section in a parturient with systemic mastocytosis

Mastocytosis is a rare disorder caused by the proliferation and accumulation of mast cells in various organs. It has a broad variety of clinical manifestations, including cardiovascular collapse. Diverse stimuli trigger the release of vasoactive substances and parturients with systemic mastocytosis are at high risk for precipitating mast cell degranulation. As a result, women with systemic mastocytosis should have an anaesthetic plan for labour and delivery. Anxiety, stress, sleep deprivation, pain and numerous pharmacological agents are all triggers for mast cell degranulation. For pain relief in labour, epidural analgesia is recommended. Pharmacological agents with a high potential for triggering mast cell degranulation should be avoided. This is particularly important in the case of an emergency caesarean section. Resuscitation equipment must be available should life-threatening haemodynamic instability occur during surgery. We report the case of a pregnant woman with systemic mastocytosis who required emergency caesarean section.     

Ultrastructural examination of bronchial biopsy specimens from children with moderate asthma

BACKGROUND: Few studies have evaluated the asthmatic airway in childhood. The aim of this study was to assess the histopathological changes occurring in the bronchi of children with moderate asthma using light and electron microscopy. METHODS: Bronchial biopsy specimens from 10 children with moderate asthma (seven boys) of mean (SD) age 9.3 (3.8) years (range 5-14) were examined by light and electron microscopy. Patients had not had a respiratory infection for at least one month and they had not been treated with steroids or sodium cromoglycate for four weeks before the study. Bronchoscopy was performed under general anaesthesia using a Karl Storz rigid paediatric bronchoscope. Biopsy materials were stained with uracyl acetate and lead citrate and evaluated under a Zeiss-10 electron microscope and light microscope. RESULTS: The most important finding was thickening and hyalinization of the basement membrane in nine patients. The ciliated epithelial cells showed loss of cilia in some cases. Overactive fibroblasts were consistently found. Six patients had degranulating mast cells and lymphocyte infiltration in the submucosa. Eosinophils were seen in only one biopsy sample. CONCLUSION: Children with moderate asthma develop bronchial inflammation similar to the reaction observed in adults. However, in our study the inflammation was rich in lymphocytes rather than eosinophils.     

Plasma histamine concentration during propranolol induced bronchoconstriction.

The mechanism of propranolol induced bronchoconstriction in asthma is uncertain, as airway beta adrenoceptors are not innervated by sympathetic nerves and circulating adrenaline concentrations are not raised. Propranolol 10 mg was infused over 27 minutes in 14 subjects with mild asthma. Peak expiratory flow (PEF) decreased by 80-235 l/min (17-51% of baseline) in nine subjects, who were called "responders," and by less than 50 l/min (12% of baseline) in five "non-responders". These two groups did not differ in baseline ventilatory function or in any clinical characteristic. In "responders" mean PEF had decreased significantly from 440 to 390 l/min after infusion of propranolol 2.1 mg, though the maximum fall in PEF occurred during or within five minutes of the end of the infusion. In nine of the subjects (six "responders" and three "non-responders") the possibility that propranolol induced bronchoconstriction is due to blockade of mast cell beta receptors leading to increased mediator release was examined by measurement of plasma histamine concentration as an index of mast cell degranulation. There was no consistent change in plasma histamine concentration in either group. No evidence of increased mast cell mediator release has been found in association with propranolol induced bronchoconstriction.     

Gastro-oesophageal reflux and childhood asthma: the acid test.

The presence of gastro-oesophageal reflux was investigated in 18 children with moderate to severe asthma by overnight oesophageal pH monitoring. Appreciable reflux was found during sleep in eight; its relevance to nocturnal asthma was not clear. On another occasion the same children were challenged in a double blind fashion with a drink of dilute hydrochloric acid (0.001 N) and the response of the airways was monitored by peak flow measurements and by histamine challenge tests. There was a significant increase in mean histamine sensitivity (p = 0.001) 90 minutes after the acid drink without any associated change in baseline peak flow rate. Eight children had a significant response to the acid drink, and a further three reacted to a more concentrated solution (0.01 N). In those asthmatic children in whom reflux is associated with a positive response to an acid drink (five out of 18 in the present study) it seems likely that reflux exacerbates nocturnal symptoms.