Increased Mast Cell Tryptase Research Articles

Abstract 9889: Novel Mechanisms of Cardiac Macrophage-Mast Cell Interactions in Radiation-Induced Myocardial Fibrosis

Introduction: Both galectin-3 (gal3) and macrophages are implicated in myocardial fibrotic remodeling. Macrophages express gal3 on their surface, whereas mast cells express a high-affinity gal3 receptor, FcεRI. Understanding the mechanisms of their interactions will lead to highly targeted therapeutic approaches. Hypothesis: We hypothesize that a macrophage-expressed pro-fibrotic molecule, gal3, is a mediator of macrophage-mast cell interactions in a pre-clinical model of radiation-induced myocardial fibrosis. Methods: We studied myocardial fibrosis, cardiac macrophage-mast cell infiltration, and gal3 expression in a rodent model of thoracic radiation. We performed long-term culture of the bone-marrow cells isolated from gal3 KO (gal3 -/- ) and gal3 overexpression (gal3 +/+ ) mice. Recombinant M-CSF co-cultured cells transformed to macrophages (F4/80 + /CD11B + ), whereas IL-3-treated cells transformed to mast cells (FCεR1 + /c-kit + ). Then, we used microfluidic and transwell systems to examine the gal3-dependent macrophage-mast cell interactions in the live cell culture. Results: Thoracic radiation exposure induced myocardial fibrosis (% fibrosis, radiation: 5±2, controls: 2±0.6; p=0.01, N=5-8), which was also associated with macrophage (cells/cm 3 , radiation: 114±28, controls: 81±0.3; p=0.05, N=8) and mast cell (cells/cm 3 , radiation: 14±5, controls: 9±0.3; p=0.05, N=5-8) infiltration, and cardiac gal3 expression (pg/ng, radiation: 85±15, controls: 14±8; p=0.001, N=7). Exogenous gal3 treatment led to increased mast cell tryptase activity confirming their activation [tryptase (ng/ml), untreated: 291±46, gal3: 494±191; p<0.01, N=3-8]. Quantitative macrophage-mast cell activity in a microfluidic system showed 7.5-fold increased macrophage-mast cell adhesion in gal3 +/+ cells suggesting increased interactions with gal3 overexpression [cell adhesion (cells/mm 2 ), WT: 23±5.8, Gal3 +/+ :175±38; p<0.01, N=4]. Conclusion: In a pre-clinical model of radiation-induced myocardial fibrosis, gal3 can mediate crucial macrophage-mast cell interactions. Our data provide possible mechanistic evidence of gal3 involvement in macrophage-mast cell interactions en route to myocardial fibrosis after radiation exposure.

Postmortem serum levels of IgE and mast cell tryptase in fatal asthma

The aim of this study was to characterize the concentrations of total and specific IgE as well as mast cell-derived tryptase in postmortem serum from femoral blood and evaluate the usefulness of their determination for diagnostic purposes in cases of fatal asthma attacks. 36 autopsy cases were retrospectively selected including cases of witnessed death in asthmatic subjects, deaths in asthmatics and atopic subjects with causes of death unrelated to asthma or allergic anaphylaxis as well as deaths in non-atopic, non-allergic individuals with causes of death unrelated to asthma or allergic anaphylaxis. Initial results indicated increased postmortem serum total IgE in atopic and asthmatic individuals, irrespective of the cause of death. Conversely, increased mast cell tryptase levels were noted exclusively in fatal asthma attacks. This suggests that mast cell tryptase measurement in cases of death potentially caused by severe acute bronchial asthma may be useful for diagnostic purposes.

Risk Factors in Fatal Cases of Anaphylaxis due to Contrast Media: A Forensic Evaluation

Background: Fatalities following contrast medium exposure are extremely rare in clinical routine, though they may occur as an exception. Some may fall under the purview of the inquiring authorities and forensic pathologists due to their in-hospital occurrence. The purpose of this study was to assess the risk factors for anaphylaxis due to contrast medium administration that can be identified in fatal cases. Methods: Fatalities occurred during the course of clinical investigations with contrast media described in the literature and fatal reactions to contrast agents that had undergone forensic investigations in our medicolegal center were reviewed with respect to patient characteristics, administered contrast medium, performed biochemical investigations and potential risk factors identified based on clinical history and medical records. Results: Biochemical investigations into the fatal cases examined in our facility revealed increased mast cell tryptase, total IgE and activated mast cells in all subjects. Data obtained from the literature and our own investigations indicated that in only a minority of the fatal cases had there been previous exposure to contrast compounds, while most cases of severe anaphylaxis involved patients who apparently reacted on initial exposure. Conclusions: Most fatal cases failed to present any identifiable predisposing conditions out of those traditionally considered as risk factors for an anaphylactic reaction to contrast compounds in the medical histories of the patients. Comprehensive clinical histories and thorough reviews of medical data, along with exhaustive forensic investigations, provide information that is relevant in order to better appreciate the interwoven relationships linking all factors potentially involved in the pathogenesis of fatal anaphylaxis to contrast media.

Role of Mast Cells in Male Chronic Pelvic Pain

Chronic pelvic pain syndrome accounts for 90% of all chronic prostatitis but it has an unknown pathogenesis. We sought to understand the role of mast cells and nerve growth factor in chronic pelvic pain. Expressed prostatic secretions in men with chronic pelvic pain syndrome and controls were tested for mast cell tryptase and nerve growth factor. Mast cell number, activation status and nerve growth factor expression were examined in the NOD/ShiLtJ experimental autoimmune prostatitis model and in mast cell deficient KitW-sh/KitW-sh mice. Tactile allodynia was quantified using von Frey filaments as a measure of pelvic pain behavior. Inhibitors of mast cell degranulation, histamine receptor antagonists and anti-nerve growth factor neutralizing antibodies were tested to decrease pelvic pain behavior. Men with chronic pelvic pain syndrome showed increased mast cell tryptase and nerve growth factor in expressed prostatic secretions. In the experimental autoimmune prostatitis model increased total and activated mast cells were observed in the prostate. Mast cell deficient KitW-sh/KitW-sh mice showed attenuated pelvic pain behavior but no difference in inflammatory infiltrates in the prostate from controls. Mice with experimental autoimmune prostatitis also demonstrated increased intraprostatic nerve growth factor compared to that of KitW-sh/KitW-sh mice. Treatment of experimental autoimmune prostatitis with a mast cell stabilizer combined with a histamine 1 receptor antagonist resulted in a synergistic decrease in chronic pelvic pain. In contrast, neutralization of nerve growth factor in vivo did not result in pain relief. Results suggest that mast cells are important mediators of chronic pelvic pain in experimental autoimmune prostatitis cases. They may be potential targets for therapeutic intervention in men with chronic prostatitis/chronic pelvic pain syndrome.

Increased Mast Cell Tryptase Levels and Altered Proteinase-Activated Receptor 2 (PAR-2)-Dependent Control of Epithelial Barrier Function in a Rat Model of Post-Inflammatory Gut Dysfunction

Increased Mast Cell Tryptase Levels and Altered Proteinase-Activated Receptor 2 (PAR-2)-Dependent Control of Epithelial Barrier Function in a Rat Model of Post-Inflammatory Gut Dysfunction

Pulmonary Mastocytosis and Enhanced Lung Inflammation in Mice Heterozygous Null for the Foxf1 Gene

The Forkhead Box f1 (Foxf1) transcriptional factor (previously known as HFH-8 or Freac-1) is expressed in endothelial and smooth muscle cells in the embryonic and adult lung. To assess effects of Foxf1 during lung injury, we used CCl(4) and butylated hydroxytoluene (BHT) injury models. Foxf1(+/-) mice developed severe airway obstruction and bronchial edema, associated with increased numbers of pulmonary mast cells and increased mast cell degranulation after injury. Pulmonary inflammation in Foxf1(+/-) mice was associated with diminished expression of Foxf1, increased mast cell tryptase, and increased expression of CXCL12, the latter being essential for mast cell migration and chemotaxis. After ovalbumin (OVA) sensitization and OVA challenge, increased lung inflammation, airway hyperresponsiveness to methacholine, and elevated expression of CXCL12 were observed in Foxf1(+/-) mice. During lung development, Foxf1(+/-) embryos displayed a marked increase in pulmonary mast cells before birth, and this was associated with increased CXCL12 levels in the lung. Expression of a doxycycline-inducible Foxf1 dominant-negative transgene in primary cultures of lung endothelial cells increased CXCL12 expression in vitro. Foxf1 haploinsufficiency caused pulmonary mastocytosis and enhanced pulmonary inflammation after chemically induced or allergen-mediated lung injury, indicating an important role for Foxf1 in the pathogenesis of pulmonary inflammatory responses.

293 Increased Intraepithelial Lymphocytes and Mast Cells with Depressed Serotonin Transporter in Duodenal Biopsies and Platelets of Patients with IBS and Diarrhoea (IBS-D): Correlation with Bowel Frequency

INTRODUCTION: Several groups report increased mucosal inflammation and increased circulating cytokines, which both cell and animal studies show to depress SERT, in IBS. We therefore assessed mucosal and platelet SERT function together with 5HT & Mast Cell tryptase release (MCT) from duodenal biopsies which were also assessed for mast cells (MC), intra-epithelial lymphocytes (IEL) & 5HT-containing enterochromaffin cells (EC) compared to coeliac patients who are known to have mucosal inflammation with depressed SERT mRNA. AIMS & METHODS: 28 healthy volunteers, 20 patients with IBS-D & 20 with untreated coeliac disease (CD) completed bowel symptom questionnaires and underwent duodenal biopsy. 5HT & MCT release was assayed after 6 hour incubation. MC, IELs & ECs were identified by immuno-histochemistry. SERT and cytokeratin 20(CK20) mRNA were assessed by Taqman qRT-PCR. Platelet SERT function was assayed by H3-5HT uptake. Project supported by Novartis Pharma AG. RESULTS: IBS-D showed increase IELs, mast cell numbers and increased mast cell tryptase release (see Table). DIBS also showed depressed SERT/CK20(arbitrary units) at 0.19(0.1-0.43) versus 0.96(0.14-1.40) for HV, p<0.02. Platelet uptake of H3-5HT was also depressed at 12.8(8.3-23.2) versus 45.2(27.7-69.3)pmol/min/ mg protein for HV, p<0.01. CD had intermediate values, difference NS v HV. Mast cell numbers correlated (r=0.56, p=0.02) with stool frequency in IBS patients but not in coeliacs nor HV. IELs, in HV and IBS, correlated positively with mast cell numbers r=0.45 , p=0.001 and with EC count r=0.39, p=0.006 but negatively with SERT r=-0.37 ,p=0.01 and platelet 5HT uptake -0.53, p=0.001. CONCLUSIONS: IBS-D is characterised by increased duodenal IELs and mast cells associated with increased mast cell tryptase release. The depressed SERT in mucosa and platelets correlates with mucosal IELs and may be secondary to increased inflammatory mediators. Depressed SERT may contribute to increased 5HT availability and diarrhoeal symptoms. Mast cell numbers correlate with stool frequency suggesting mast cell products also play a part in symptoms.

Mast cell tryptase—role in the investigation of acute hypersensitivity reactions

Mast cells are granulocytes found in peripheral tissues that play a central role in acute hypersensitivity reactions. Tryptase, a neutral serine protease, is the most abundant mediator stored in mast cell granules. The release of tryptase is a characteristic feature of mast cell degranulation. β -tryptase has a role in airway homeostasis, angiogenesis, vascular relaxation and contraction, gastrointestinal smooth muscle activity and intestinal transport, mediated by activation of protease-activated receptor (PAR) type 2. Serum mast cell β -tryptase is increased in anaphylaxis and other allergic conditions. Increased tryptase levels are highly suggestive of an immunologically mediated reaction but may reflect direct histamine release. Patients with increased mast cell tryptase levels must be investigated for an allergic cause. However, if the clinical picture suggests severe anaphylaxis, investigations for an allergic cause must be undertaken in patients even if their mast cell tryptase levels are not increased.

Protease-activated receptor stimulation activates a Ca2+-independent phospholipase A2in bladder microvascular endothelial cells

Increased mast cell numbers and mast cell activation represent one of the prevalent etiologic theories for interstitial cystitis, an inflammatory condition in the bladder. This study was designed primarily to determine whether increased mast cell tryptase in the bladder wall may play a role in activating bladder endothelial cell phospholipase A(2) (PLA(2)), leading to increased inflammatory phospholipid metabolite accumulation, which may propagate the inflammatory process. We stimulated human bladder microvascular endothelial cells with thrombin or tryptase and measured the activation of PLA(2) and the production of multiple membrane phospholipid-derived inflammatory mediators. Thrombin and tryptase stimulation resulted in activation of a Ca(2+)-independent PLA(2), leading to increased release of arachidonic acid and prostacyclin and increased production of platelet-activating factor. These responses were blocked completely by pretreatment of human bladder microvascular endothelial cells with the Ca(2+)-independent PLA(2)-selective inhibitor bromoenol lactone. The combination of increased prostacyclin and platelet-activating factor in the bladder circulation may result in vasodilation and increased polymorphonuclear leukocyte adherence to the endothelium and may facilitate recruitment of polymorphonuclear leukocytes to the bladder wall of patients with interstitial cystitis.

Mast cell tryptase: a review of its physiology and clinical significance.

Mast cells, which are granulocytes found in peripheral tissue, play a central role in inflammatory and immediate allergic reactions. beta-Tryptase is a neutral serine protease and is the most abundant mediator stored in mast cell granules. The release of beta-tryptase from the secretory granules is a characteristic feature of mast cell degranulation. While its biological function has not been fully clarified, mast cell beta-tryptase has an important role in inflammation and serves as a marker of mast cell activation. beta-Tryptase activates the protease activated receptor type 2. It is involved in airway homeostasis, vascular relaxation and contraction, gastrointestinal smooth muscle activity and intestinal transport, and coagulation. Serum mast cell beta-tryptase concentration is increased in anaphylaxis and in other allergic conditions. It is increased in systemic mastocytosis and other haematological conditions. Serum beta-tryptase measurements can be used to distinguish mast cell-dependent reactions from other systemic disturbances such as cardiogenic shock, which can present with similar clinical manifestations. Increased beta-tryptase levels are highly suggestive of an immunologically mediated reaction but may also occur following direct mast cell activation. Patients with increased mast cell beta-tryptase levels must be investigated for an allergic cause. However, patients without increased mast cell tryptase levels should be investigated if the clinical picture suggests severe anaphylaxis.

Mast cell tryptase and hemolysis after trauma

Background: We have previously found increased mast cell tryptase in accidental deaths due to trauma, indicating that mast cell degranulation had occurred. The present study was designed to confirm the previous observation and to determine if tryptase release after trauma is acute or delayed. Furthermore, the importance of hemolysis and direct trauma to the mast cells was investigated. Materials and methods: Mast cell tryptase was measured in post-mortem blood from the femoral vein in 27 cases of death from trauma and in 27 control cases by means of a commercially available immunoassay. The trauma cases were further classified into groups with single versus multiple trauma, and groups with short survival time (i.e. death at the scene of the accident) versus longer survival time (death in hospital). In five multi-trauma deaths, blood was sampled locally from the sites of crush injury. Results: The mean value of tryptase in femoral vein blood was 35.6±34.6 μg/l in the entire trauma group and 14.7±6.5 μg/l in the controls ( P<0.005). In bloody liquid sampled from crush injuries, tryptase was substantially elevated in all cases, with a mean of 227±146 μg/l. In cases with short survival time, tryptase was significantly higher than in those who died after several hours or days in hospital ( P<0.001). No statistically significant difference was seen between multi- and single-trauma cases. A correlation between hemolysis in the samples and elevated tryptase was found only in the trauma cases ( P<0.05), but experimentally induced hemolysis in vitro was not found to influence the measurements. Conclusion: Mast cell tryptase becomes elevated in trauma deaths and this seems to be ascribable either to direct mechanical injury to tissue mast cells and/or to cell lysis. In patients initially surviving severe injuries, the effects of massive release of histamine and other mast cell mediators might be of importance for treatment strategies and prognosis.

Increased mast cell tryptase in sudden infant death - anaphylaxis, hypoxia or artefact?

Increased concentrations of mast cell tryptase in post mortem blood have frequently been observed in sudden infant deaths but the cause of this has not yet been clarified. The aim was to evaluate factors (immunological, morphological and anamnestic data) behind the observed increase in mast cell tryptase in sudden infant deaths with elevated tryptase. Mast cell tryptase and total immunoglobulin (Ig) E were measured in post mortem sera from 44 infants younger than 1.5 years. Radioallergosorbent tests were performed for possible allergens (mixture for relevant food allergens, Phadiatop and latex). IgG subclasses, IgM, and complement factors (C3, C4 and factor B) were measured with radial immunodiffusion. Mast cells, labelled with antibodies against mast cell tryptase, were counted in the lungs and heart. The circumstances of death and medical history of the deceased infant and family were obtained through police and hospital records. In 40% of the SIDS cases tryptase was elevated (>10 microg/L). Total IgE in serum was increased in 33% compared with clinical reference values but showed no association with mast cell tryptase. RAST tests were positive in three cases. In one of these cases both tryptase and total IgE were elevated. The only variable that was associated with high tryptase values was prone position at death (P < or = 0.05 ). Allergy or asthma in the family were alleged in 50% of the cases, but was not associated with elevated tryptase or IgE. Children with elevated total IgE also displayed high concentrations of IgG1 and IgG2. Infants who died in the spring had significantly higher IgE than the others (P < or = 0.05). The results do not support the hypothesis that the elevated tryptase concentrations in sudden infant death are caused by allergy. The association between prone position at death and elevated tryptase could hypothetically be explained by mast cell degranulation due to, for example, a hypoxic stimulus in these infants.

Mast cell tryptase in anaesthetic anaphylactoid reactions

Increased concentrations of mast cell tryptase are a highly sensitive indicator of anaphylactic reactions during anaesthesia. We obtained serum specimens from 350 patients after possible anaphylactic reactions during anaesthesia. Serum was collected from patients in our own institution (27), and transported by mail and courier from other hospitals in response to a request in the medical literature (323). Concentrations of mast cell tryptase were measured in 416 specimens. Intradermal testing was performed in 217 patients and radioimmunoassay for drug-specific antibodies with serum in 198 patients. Mast cell tryptase concentrations were increased in 158 patients, equivocal in 10 and not increased in 182. There was a significant difference in the incidence of positive intradermal tests, radioimmunoassay tests and evidence of an IgE-mediated reaction in patients whose mast cell tryptase concentrations were increased. Seven of 143 patients whose mast cell tryptase concentrations were not increased at appropriate sampling times had positive tests for IgE antibodies, and in 33 of 158 patients with increased mast cell tryptase concentrations no IgE antibodies were detected. We conclude that increased mast cell tryptase concentrations are a valuable indicator of an anaphylactic reaction during anaesthesia. Their presence favours an IgE-mediated cause but does not always distinguish between anaphylactoid and anaphylactoid reactions, and patients in whom mast cell tryptase concentrations are not increased still require skin testing.