Marker Of Mast Cell Activation Research Articles

Effect of omalizumab on inflammatory markers in COVID-19: an exploratory analysis of the COVID-19 immunologic antiviral therapy with omalizumab (CIAO) trial.

The CIAO trial recently demonstrated a probable clinical benefit of omalizumab in the treatment of severe COVID-19; however, the mechanism underlying this benefit remains unclear. Therefore, we sought to longitudinally assess the impact of omalizumab on serum cytokines in CIAO trial patients to determine its mechanism of action. Blood samples were collected on days 0, 2, 7, and 14 from patients recruited into the CIAO trial and who consented to this substudy. Blood samples were tested by a panel of 25 inflammatory cytokines, as well as for markers of mast cell activation. Levels of inflammatory biomarkers were compared over time between omalizumab- and placebo-treated patients by generalized linear mixed-effects model. Associations between biomarkers and clinical outcomes were investigated by mixed-effects logistic regression. Nineteen patients were recruited into this substudy; 10 were assigned to placebo and 9 to omalizumab. Monokine induced by gamma interferon was significantly positively associated with severe COVID-19 (Odds Ratio [OR] = 1.06, 95%CI = 1.00-1.11, p = 0.043). Further, omalizumab significantly reduced interleukin-15 (Coefficient = -0.95, p = 0.048) and macrophage inflammatory protein-1 (Coefficient = -1.31, p = 0.010) levels. However, neither was significant in analyses adjusting for multiple hypothesis testing. Although limited by a small sample size, these results suggest that omalizumab's potential benefit in COVID-19 may be mediated independently of modulation of the measured serum biomarkers. Further studies are needed to investigate omalizumab's mechanism of action in COVID-19.

Abstract B089: Intratumoral expression analysis of mast cells in high grade serous ovarian cancer

Abstract Objective: The goal of this study is to examine intratumoral expression and phenotypic changes in mast cells following neoadjuvant chemotherapy (NACT) exposure in high grade serous ovarian cancer (HGSOC). Methods: 37 HGSOC matched pre-and post-NACT patient tumors were stained with a commercially available mast cell hemotoxic-based kit and both intratumoral and stromal mast cells were quantified. Immunohistochemistry was employed to stain for histamine in 19 matched HGSOC patient tumors and mean intensity and integrated optical density was quantified using Image J. Kaplan Meier curve analysis was employed to determine the relationship between mast cells levels and progression-free survival (PFS). Immortalized human mast cells, LUVA were treated with carboplatin and paclitaxel and specific genomic changes were measured by quantitative PCR (qPCR). Results. Mast cells were more prominently expressed in intraepithelial regions compared to stromal cells, however both populations were significantly (p<0.05) increased following NACT. Total mast cells stratified by upper and lower quartile demonstrated that higher levels were significantly (p<0.05) associated with improved PFS. Furthermore, histamine, a marker of mast cell degranulation was significantly (p<0.05) increased in HGSOC tumors post-NACT and significantly correlated (r=0.553, p=0.013) with the change in total mast cells. Following chemotherapy treatment LUVA cells demonstrated an over 7-fold increase in amphiregulin (AREG) expression (p<0.01), a key marker of mast cell activation. Interestingly, angiogenic and pro-tumorigenic factors IL-10, IL-8, and VEGFA exhibited no significant differences in expression following chemotherapy exposure. Conclusions: Overall, our findings suggest a correlation in NACT exposure and intratumoral mast cell recruitment, degranulation, and activation. Further studies include investigating differences in specific tumorigenic genes and cell signaling pathways in mast cells pre- and post- NACT, as well as determining if mast cells can impact HGSOC chemotherapy response. Citation Format: Julia McAdams, Jasmine Ebott, Payton De La Cruz, Nicole E. James. Intratumoral expression analysis of mast cells in high grade serous ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B089.

Cytotoxicity assessment of exfoliated MoS2 using primary human mast cells and the progenitor cell-derived mast cell line LAD2.

Molybdenum disulfide is an emerging 2D material with several potential applications in medicine. Therefore, it is crucial to ascertain its biocompatibility. Mast cells are immune cells that are found in many organs and tissues in contact with the extracellular environment, and can be cultured from progenitor cells present in the bone marrow. Given the long period required for differentiation and proliferation of primary mast cells, human mast cell lines have emerged as a tractable model for biological and toxicological studies. Here, we compare two types of industrial MoS2 using CD34+-derived primary human mast cells and the LAD2 cell line. Minimal effects were observed on early-stage activation endpoints such as β-hexosaminidase release and expression of surface markers of mast cell activation. Transmission electron microscopy revealed limited uptake of the tested materials. Overall, MoS2 was found to be biocompatible, and the LAD2 cell line was validated as a useful in vitro model of mast cells.

Oleanolic Acid Acetate Inhibits Mast Cell Activation in Ovalbumin-Induced Allergic Airway Inflammation.

Asthma is a complex, heterogeneous chronic inflammatory airway disease with multiple phenotypes. There has been a great progress in managing asthma, but there are still unmet needs for developing uncontrolled asthma treatments. The present study aimed to determine the effectiveness of oleanolic acid acetate (OAA) from Vigna angularis against allergic airway inflammation and the underlying mechanism of action with a focus on mast cells. To investigate the effect of OAA in allergic airway inflammation, we used the ovalbumin (OVA)-sensitized and challenged mice. To examine allergic airway inflammation associated with immune responses of mast cell activation in vitro, various types of mast cells were used. Systemic and cutaneous anaphylaxis models were used for mast cell-mediated hyper-responsiveness in vivo. OAA reduced OVA-induced airway inflammatory responses such as bronchospasm, increase of immune cell infiltration and serum immunoglobulin E and G1 levels. Especially, OAA decreased the mast cell infiltration, and β-hexosaminidase release as a mast cell activation marker in the bronchoalveolar lavage fluid. OAA inhibited mast cell degranulation in mast cell line (RBL-2H3) and primary cells (rat peritoneal mast cell and mouse bone marrow-derived mast cell). Mechanistically, OAA suppressed intracellular signaling pathways including the phosphorylation of phospholipase Cγ and nuclear factor-κB, resulting from the suppression of intracellular calcium influx and pro-inflammatory cytokine expression. Further, oral administration of OAA attenuated mast cell-mediated systemic and cutaneous anaphylaxis. Our study showed that OAA can inhibit mast cell-mediated allergic reaction. Consequently, the application of OAA to mast cells for the allergic airway inflammation facilitate a new direction of treating allergic asthma.

Changes in tryptase levels during cardiac surgery in patients at low risk for allergic reactions

Tryptase test can be used as a clinical marker of mast cell activation. The present study is was aimed to identify variations in serum tryptase levels and their possible relationships with allergic reactions to protamine in low-risk patients undergoing cardiac bypass surgery. Thirty patients according to American Society of Anesthesiologists physical status III who underwent cardiac bypass surgery were enrolled. This prospective, non-randomised, clinical study was conducted in an operating room. Venous blood samples for tryptase measurements were obtained from cardiac bypass surgery patients upon admission to the operating room and immediately before and 30 min after the initiation of protamine administration. Signs of allergic reactions were recorded and management steps based on rapid effect response-based clinical assessments for diagnosis and treatment decisions during protamine administrations were described. Serum tryptase levels and clinical signs of allergic reactions, primarily mean arterial pressure (MAP), were recorded. Serum tryptase levels increased significantly and progressively during the bypass procedure (study power, 80%; sample size, 28; power of analysis, 99.8% with α=0.05); however, tryptase levels did not reach a sufficiently high level to confirm an allergic reaction. The MAP and heart rate decreased in 50% of the patients. Although tryptase increased significantly when compared with baseline levels, protamine-associated increases were not significant and failed to provide an unequivocal indication of an allergic response to protamine.

1142: ANAPHYLACTIC REACTION AFTER SUGAMMADEX ADMINISTRATION

Introduction: Anaphylaxis in the perioperative and operative period is a potentially life-threatening reaction to medications or substances, most commonly neuromuscular blocking agents (NBMAs), antibiotics, disinfectants, and latex. The most frequently used NBMAs are succinylcholine and rocuronium, but sugammadex - typically used for rocuronium reversal and controversially touted as a possible treatment for rocuronium-induced anaphylaxis - has been increasingly reported in the literature as an anaphylaxis trigger itself. Description: A 44 year-old male with a past medical history significant for traumatic brain injury (TBI) and cerebral palsy presented with skin changes around his baclofen pump. He was admitted and taken to the operating room for pump explantation. There were no issues with induction of anesthesia. After pump explantation, 200mg of sugammadex was administered for reversal of rocuronium. Four minutes later, the patient’s blood pressure (BP) dropped to 58/32mmHg. The patient’s hypotension persisted despite boluses of epinephrine, phenylephrine, ephedrine, and albumin. For presumed anaphylactic reaction, the patient was given 100mg of hydrocortisone and further doses of epinephrine. A tryptase level was also sent. The patient became hemodynamically stable during his first day in the intensive care unit. The tryptase level down-trended from 44.9 micrograms/liter (mcg/L) initially to 6.8mcg/L after two days (normal: 2.2-13.2 mcg/L). The patient was safely discharged on hospital day 9. Discussion: Sugammadex-induced anaphylaxis is an emerging, life-threatening complication experienced during anesthesia. Management includes airway and hemodynamic support (with epinephrine), withdrawal of the offending agent, and serum tryptase measurements as a marker of mast cell activation in anaphylaxis. While NBMA-associated anaphylaxis is commonly peri-intubation and sugammadex reactions are typically peri-extubation, patients can also be allergic to the sugammadex-rocuronium complex, further complicating attempts to distinguish between the two for future avoidance. As research is devoted towards understanding sugammadex anaphylaxis and possible alternative approaches, providers will have more information for determining the risks and benefits of different anesthetic methods in patients.

Cannabidiol Attenuates Chronic and Acute Hyperalgesia in Sickle Mice By Reducing Inflammation and Oxidative Stress

Pain is a major comorbidity of sickle cell disease (SCD) leading to hospitalization, opioid use and reduced survival. It can present as both chronic pain and/or unpredictable episodes of intense acute pain. Hydroxyurea (HU) is the mainstream FDA approved treatment for SCD, but its effect on reducing pain remains to be understood. A larger number of people with SCD use cannabis products for pain relief compared to those with other conditions. Cannabidiol (CBD) is one of the major constituents of Cannabis sativa, second to tetrahydrocannabinol, and has gained attention for its ability to treat pain without intoxicating side effects. CBD has been shown to decrease inflammation, oxidative stress, and inhibit mast cell activation, all of which occur in SCD. Thus, we hypothesize that CBD will ameliorate both chronic and acute hyperalgesia in humanized homozygous BERK sickle mice (called sickle) by inhibiting mast cell activation and decreasing inflammation and oxidative stress. To simulate the clinical condition, we treated female sickle mice intraperitoneally with [i] vehicle (1:1:18 DMSO:Tween-20:saline), [ii] HU (50 mg/kg/d HU), [iii] CBD (20 mg/kg/d) or [iv] HU + CBD and determined their effect on chronic and acute hyperalgesia (pain). Sickle mice treated with synthetic CBD alone or cotreatment with HU+CBD daily showed significantly reduced chronic mechanical (p<0.001) and cold (p<0.001) hyperalgesia compared to baseline after 7 days of treatment, which was maintained for up to 14 days. HU decreased mechanical (p<0.01) but not cold hyperalgesia after 14 days compared to baseline. Thus, CBD independently attenuates chronic hyperalgesia, whereas HU may have a modest effect on chronic pain. Following the initial 14 days of treatment above, we incited acute hyperalgesia by treating sickle mice with hypoxia/reoxygenation (H/R; 3 hours of hypoxia at 8% O2 and 92% N2, followed by 1 hour of reoxygenation at normoxia) on days 15 (H/R-1) and 18 (H/R-2). We observed that CBD, HU, and HU+CBD treatments were able to prevent an increase in H/R-incited hyperalgesia (acute response). CBD alone and HU+CBD significantly reduced mechanical (p<0.001) and cold hyperalgesia (p<0.001) compared to baseline following incitement of both H/R-1 and H/R-2, and up to 25 days, the last period of observation. HU alone did not show a significant decrease in mechanical or cold hyperalgesia compared to baseline following incitement of either H/R event, except for cold hyperalgesia 72h post-H/R-2 (p<0.05). CBD and HU+CBD treatments also reduced non-evoked cold avoidance compared to baseline in sickle mice, which spent significantly more time (p<0.01) in a cold chamber (4°C) 7d after H/R-2 (day 25), but HU alone did not. Thus, HU has a modest or no effect on different features of sickle pain, while CBD is able to ameliorate both chronic and acute pain. We next investigated the mechanism of CBD's analgesic effect in sickle mice. Following 9 days of daily treatment, we observed that CBD decreased total and degranulating mast cells (p<0.05 and p<0.01, respectively) in the skin compared to vehicle, and a reduction in tryptase (p<0.05), a marker of mast cell activation, in the skin secretagogue. CBD treatment decreased substance P (p=0.05) and malondialdehyde, (p<0.05), markers of neuroinflammation and oxidative stress respectively, in the skin secretagogue, and serum amyloid P (p<0.05), a marker of inflammation, in plasma. CBD significantly decreased inflammatory cytokines IL-3, which promotes mast cell proliferation, TNFα, a hallmark feature of cytokine storm, and MIP-1α and RANTES, which contribute to leukocyte recruitment. Thus, CBD attenuates inflammation, neuroinflammation and oxidative stress in sickle mice and may ameliorate leukocyte activities, a hallmark feature of SCD. We demonstrate that CBD is effective in attenuating chronic hyperalgesia and preventing acute pain by decreasing inflammation and oxidative stress. The effect of HU on reducing pain following H/R and chronic pain are modest and specific to certain characteristic features of sickle pain. Importantly, HU does not appear to interfere with the analgesic effect of CBD in sickle mice, which shows promise for CBD treatment in persons with SCD on HU. The availability of a >99% CBD-extract (Epidiolex) approved by the FDA to treat some forms of epilepsy may help facilitate clinical trials for assessing the effects of CBD on pain in persons with SCD.

PACAP38- and VIP-induced cluster headache attacks are not associated with changes of plasma CGRP or markers of mast cell activation.

Pituitary adenylate cyclase-activating polypeptide-38 (PACAP38) and vasoactive intestinal polypeptide can provoke cluster headache attacks in up to half of cluster headache patients in their active phase. At present, it is unknown whether provoked attacks are mediated via calcitonin gene-related peptide or mast cell activation. All enrolled patients with cluster headache were randomly allocated to receive a continuous infusion of either PACAP38 (10 pmol/kg/min) or vasoactive intestinal polypeptide (8 pmol/kg/min) over 20 min. We collected clinical data and measured plasma levels of calcitonin gene-related peptide and markers of mast cell activation (tryptase and histamine) at fixed time points: at baseline (T0), at the end of the infusion (T20), 10 min after the infusion (T30), and 70 min after the infusion (T90). Blood was collected from episodic cluster headache patients in active phase (n = 14), episodic cluster headache patients in remission (n = 15), and chronic cluster headache patients (n = 15). At baseline, plasma levels of calcitonin gene-related peptide, tryptase, and histamine were not different among the three study groups. Plasma levels of calcitonin gene-related peptide (p = 0.7074), tryptase (p = 0.6673), or histamine (p = 0.4792) remained unchanged during provoked attacks compared to attack-free patients. Cluster headache attacks provoked by either PACAP38 or vasoactive intestinal polypeptide were not accompanied by alterations of plasma calcitonin gene-related peptide, tryptase or histamine. The provoked attacks may not be mediated by calcitonin gene-related peptide or mast cell activation.Trial Registration: The study is registered at ClinicalTrials.gov (NCT03814226).

Correlation between Gene Polymorphisms of Prostaglandin D Correlation between Gene Polymorphisms of Prostaglandin D

Background: Patients, their families and the community suffer a heavy burden when it comes to asthma because it is both common and possibly life-threatening. It has been postulated that arachidonic acid's most prevalent cyclooxygenase metabolite, prostaglandin D2 (PGD2), is a mast cell activation marker in asthma. Objective: To evaluate association between PGDR-441 polymorphism with risk factors, laboratory characteristics, and severity of asthma in children. Methods: In this cross-sectional study, Forty Egyptian children were genotyped using allele specific polymerase chain reaction (AS-PCR) to assess single nucleotide polymorphism of PTGDR2 receptors. Selected cases were classified according to GINA guidelines and spirometrically assessed to evaluate pulmonary functions. Results: There is significant difference between mild, moderate and severe asthma regarding total IgE level(P1<0.001). 68.0% of the studied patients had Homogenous PGDR2(TT) and 32% had Heterozygous PGDR2(TC). There were no statistically significant associations between PGDR2 Polymorphisms and both of asthma risk factors and laboratory characteristics. There was a statistically significant difference between PGDR2 Polymorphisms and bronchial asthma severity of the studied patients. Heterozygous PGDR2 was associated with more severe bronchial asthma. Conclusion: Our study showed a strong relationship between polymorphism of PTGDR2 receptor and severity of bronchial asthma.

Pseudo-Anaphylactic Reactions to Pfizer BNT162b2 Vaccine: Report of 3 Cases of Anaphylaxis Post Pfizer BNT162b2 Vaccination

Anaphylactic reactions were observed after Singapore’s national coronavirus disease 2019 (COVID-19) vaccination programme started in December 2020. We report the clinical and laboratory features of three patients in our institution who developed anaphylactic reactions after receiving the Pifzer BNT162b2 vaccine. IgM and IgG antibodies, but not IgE antibodies to the Pfizer BNT162b2 vaccine, were detected in all subjects. Similarly, mild to high elevated levels of anti-polyethylene glycol (PEG) IgG (1035–19709 U/mL, vs. vaccine-naive < 265 U/mL, vaccine-tolerant < 785 U/mL) and IgM (1682–5310 U/mL, vs. vaccine-naive < 1011 U/mL, vaccine-tolerant < 1007 U/mL) were detected in two out of three patients via commercial ELISA. High levels of serum anaphylatoxin C3a (79.0 ± 6.3 μg/mL, mean ± SD, vs. normal < 10 μg/mL) were observed in all three patients during the acute phase of the reaction, while tryptase levels, a marker of mast cell activation, were not elevated. Finally, one patient with the highest levels of anti-PEG IgG, IgM, and anti-Pfizer BNT162b2 IgG and IgM exhibited an enhanced Th2 cytokine serum profile during an acute reaction, with high levels of IL-4 (45.7 pg/mL, vs. vaccine-naive/tolerant < 2.30 pg/mL), IL-33 (86.4 pg/mL, vs. vaccine-naive/tolerant < 5.51 pg/mL) and IL-10 (22.9 pg/mL, vs. vaccine-naive/tolerant < 12.49 pg/mL) diminishing over time following corticosteroid treatment. Taken together, we propose these cases of anaphylaxis described are driven by a complement activation-related pseudoallergy (CAPRA), rather than classical IgE-mediated mechanisms.

Effect of a Cytoprotective Dose of Dehydroleucodine, Xanthatin, and 3-Benzyloxymethyl-5H-furan-2-one on Gastric Mucosal Lesions Induced by Mast Cell Activation.

The aim of this study was to determine whether the lactones dehydroleucodine, xanthatin and 3-benzyloxymethyl-5H-furan-2-one, would be effective in an animal model of gastric ulcer induced by mast cell activation. Rats were divided into ten groups. Treatments were repeated for four days. The degree of gastric erosion was assessed with a scoring system and histological preparations. Gastric mast cell morphology was analyzed by histological procedures. Serum serotonin levels were determined as markers of mast cell activation. Statistical analyses were done using ANOVA and Tukey–Kramer test. We demonstrated that the repeated administration of compound 48/80 results in extensive mucosal lesions in the gastric mucosa and that such lesions occurred in association with mast cell degranulation and a significant increase of serum serotonin. We showed that these lesions were prevented by dehydroleucodine, xanthatin, and 3-benzyloxymethyl-5H-furan-2-one and that this effect was similar to that obtained with sodium cromoglycate. In conclusion, the results of the present study indicate that the optimal gastric cytoprotective dose of dehydroleucodine, xanthatin, and 3-benzyloxymethyl-5H-furan-2-one is efficacious in an animal model of gastric ulcer induced by mast cell activation. Our findings suggest that these lactones could be valuable tools for designing novel therapeutic agents for digestive disorders associated with inappropriate mast cell activation.

Impairment of platelet NO signalling in coronary artery spasm: role of hydrogen sulphide.

The pathophysiology of coronary artery spasm (CAS), with its associated ischaemic crises, is currently poorly understood and treatment is frequently ineffective. In view of increasing evidence that platelet-based defects may occur in CAS patients, we investigated platelet reactivity in CAS patients and whether symptomatic crises reflect activation of platelet-endothelial interactions. CAS patients were evaluated during acute and/or chronic symptomatic phases and compared with healthy control subjects. Inhibition of ADP-induced platelet aggregation by the NO donor sodium nitroprusside (SNP) and plasma concentrations of syndecan 1 (glycocalyx shedding marker), tryptase (mast cell activation marker) and platelet microparticles were measured. Inhibition of platelet aggregation by SNP was diminished in chronic CAS, with further (non-significant) deterioration during symptomatic crises, whereas plasma concentrations of syndecan 1, tryptase and platelet microparticles increased. Treatment of patients with high-dose N-acetylcysteine (NAC) plus glyceryl trinitrate rapidly increased platelet responsiveness to SNP and decreased plasma syndecan 1 concentrations. The effect of NAC on platelet responsiveness to SNP was confirmed in vitro and mimicked by the H2 S donor NaHS. Conversely, inhibition of enzymatic production of H2 S attenuated NAC effect. CAS is associated with substantial impairment of platelet NO signalling. During acute symptomatic exacerbations, platelet resistance to NO is aggravated, together with mast cell activation and damage to both vasculature and platelets. NAC, via release of H2 S, reverses platelet resistance to NO and terminates glycocalyx shedding during symptomatic crises: This suggests that H2 S donors may correct the pathophysiological anomalies underlying CAS.

CDK4/6 inhibitor palbociclib suppresses IgE-mediated mast cell activation

BackgroundMast cell activation causes degranulation and release of cytokines, thereby promoting inflammation. The aim of this study was to investigate the inhibitory effect of CDK4/6 inhibition on mast cell activation in vitro and in vivo.MethodsRBL-2H3 rat basophilic leukemia cells (BLCs) and mouse bone marrow-derived mast cells (BMMCs) were sensitized with anti-dinitrophenol (DNP) immunoglobulin (Ig)E antibodies, stimulated with DNP-human serum albumin (HSA) antigens, and treated with the CDK4/6 inhibitor palbociclib. Histological stains were applied to reveal cytomorphological changes. Murine IgE-mediated passive cutaneous anaphylaxis (PCA) and ovalbumin (OVA)-induced active systemic anaphylaxis (ASA) models were used to examine palbociclib effects on allergic reactions in vivo. Western blots were performed to detect the expression of cell signaling molecules associated with mast cell activation.ResultsActivated BLCs and BMMCs released copious granule-related mediators (histamine and β-hexosaminidase), which was reduced by palbociclib in a concentration-dependent manner. Palbociclib inhibited expression of the mast cell activation marker CD63 in activated BLCs and inhibited granule release (visualized with toluidine blue staining) while preventing morphological changes, (elongated shape maintained) and filamentous actin (F-actin) reorganization. Palbociclib suppressed molecular Lyn and/or mitogen-activated protein kinase (MAPK) signaling associated with mast cell activation in stimulated BLCs and attenuated allergic reactions in PCA mice dose dependently. Palbociclib attenuated body temperature reduction and diminished serum histamine levels in ovalbumin OVA-challenged ASA mice.ConclusionPalbociclib suppresses IgE-mediated mast cell activation in vitro and in vivo, suggesting that it may be developed into a therapy for mast cell-mediated allergic diseases via inhibition of mast cell degranulation.

Biphasic activation of complement and fibrinolysis during the human nasal allergic response

Biphasic activation of complement and fibrinolysis during the human nasal allergic response

P1: INTER‐LABORATORY VARIATION IN THE MEASUREMENT OF SERUM TRYPTASE

Serum tryptase quantitation is used as a marker of mast cell activation. Levels are elevated in allergic (anaphylactic) reactions, but can also be chronically high in conditions such as mastocytosis and haematological neoplasms. Blood samples for measurement of tryptase levels in the assessment of allergic conditions are optimally obtained 15 min to 3 h after symptom onset. Serial measurement of tryptase levels and measurement of a baseline level after recovery are reported to be more useful than measurement at only one point in time in this assessment. In all routine clinical laboratories enrolled in the RCPAQAP Tryptase Program levels of serum tryptase are measured using the Thermo Fisher ImmunoCAP systems. Considering this, there should be limited methodological variation in results obtained across laboratories. A retrospective review of results from January 2014 to June 2017 from the Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) tryptase module was undertaken. Average inter laboratory coefficient of variation (CV%) over a range of serum tryptase levels were reviewed. Twenty-eight samples were analysed, with 20–27 results submitted for each sample. Mean serum tryptase values ranged from 3.3 to 127 μg/L. The average CV% of all samples was 8% (range 4.4–12.7%). Good inter laboratory variation was seen at all levels. The inter laboratory CV% of serum tryptase as measured on the ImmunoCAP system shows good reproducibility across a range of levels.

KIT Inhibition by Imatinib in Patients with Severe Refractory Asthma

BackgroundMast cells are present in the airways of patients who have severe asthma despite glucocorticoid treatment; these cells are associated with disease characteristics including poor quality of life and inadequate asthma control. Stem cell factor and its receptor, KIT, are central to mast-cell homeostasis. We conducted a proof-of-principle trial to evaluate the effect of imatinib, a KIT inhibitor, on airway hyperresponsiveness, a physiological marker of severe asthma, as well as on airway mast-cell numbers and activation in patients with severe asthma.MethodsWe conducted a randomized, double-blind, placebo-controlled, 24-week trial of imatinib in patients with poorly controlled severe asthma who had airway hyperresponsiveness despite receiving maximal medical therapy. The primary end point was the change in airway hyperresponsiveness, measured as the concentration of methacholine required to decrease the forced expiratory volume in 1 second by 20% (PC20). Patients also underwent bronchoscopy.ResultsAmong the 62 patients who underwent randomization, imatinib treatment reduced airway hyperresponsiveness to a greater extent than did placebo. At 6 months, the methacholine PC20 increased by a mean (±SD) of 1.73±0.60 doubling doses in the imatinib group, as compared with 1.07±0.60 doubling doses in the placebo group (P=0.048). Imatinib also reduced levels of serum tryptase, a marker of mast-cell activation, to a greater extent than did placebo (decrease of 2.02±2.32 vs. 0.56±1.39 ng per milliliter, P=0.02). Airway mast-cell counts declined in both groups. Muscle cramps and hypophosphatemia were more common in the imatinib group than in the placebo group.ConclusionsIn patients with severe asthma, imatinib decreased airway hyperresponsiveness, mast-cell counts, and tryptase release. These results suggest that KIT-dependent processes and mast cells contribute to the pathobiologic basis of severe asthma. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT01097694.)

Expression of Silent Information Regulator-1(Sirt1), CD163 and Tryptase; Implications for Immune Dys-regulation, Prognosis and Therapeutic Targeting in Classical Hodgkin Lymphoma

Background: Many studies have assessed the relation between cHL histology and its clinical outcome but the results are still controversial. The most recent issue was the discovery of the methods of interaction between the elements of benign reactive inflammatory cells and their effect on cHL metabolism. Silent information regulator-1 (Sirt1) is a class III HDACs family member, it was expressed in T-cell lymphoma and was considered a recently discovered therapeutic target, we tried to detect that the significance of Sirt1 expression in malignant Reed-Sternberg cells and surrounding inflammatory infiltrate in cHL. Cluster of Differentiation 163 (CD163) is a scavenger receptor cystein-rich (SRCR) family member which identifies monocytes and macrophages, Tryptase is the secretory granules that were serine proteinase derived and it has been used as a mast cell activation marker. The tumor-infiltrating macrophages and mast cells have been found to have different roles in malignancies of many organs but their role in cHL prognosis had not been sufficiently clarified. Aim of the work: To assess the influence of Sirt1 expression in the malignant cells and the surrounding tumor microenvironment CD163 positive macrophages and tryptase positive mast cells on the pathological parameters and clinical outcome in cHL patients. Methods: We evaluated clinicopathological and prognostic significance of Sirt1, CD163 and tryptase expressions in sections from fifty paraffin blocks of cHL using immunehistochemistry. Results: The expression of Sirt1 in cHL was associated with advanced stage of the disease, presence of B symptoms, splenic affection, (p<0.001), bone marrow infiltration (p=0.002) and the presence of bulky mediastinal lymph node (p=0.004). The expression of CD163 and tryptase in cHL was associated with advanced stage of the disease and the presence of bulky mediastinal lymph node (p<0.001). High Sirt1, tryptase and CD163 expression was associated with poor response to therapy, high incidence of relapse after successful therapy and poor three-year overall survival rate (p<0.001). Conclusion: High levels of expression of Sirt1, CD163 and tryptase were found to be markers of poor prognosis in cHL.

Airway responsiveness to mannitol in asthma is associated with chymase-positive mast cells and eosinophilic airway inflammation.

Airway hyperresponsiveness (AHR) to inhaled mannitol is associated with indirect markers of mast cell activation and eosinophilic airway inflammation. It is unknown how AHR to mannitol relates to mast cell phenotype, mast cell function and measures of eosinophilic inflammation in airway tissue. We compared the number and phenotype of mast cells, mRNA expression of mast cell-associated genes and number of eosinophils in airway tissue of subjects with asthma and healthy controls in relation to AHR to mannitol. Airway hyperresponsiveness to inhaled mannitol was measured in 23 non-smoking, corticosteroid-free asthmatic individuals and 10 healthy controls. Mast cells and eosinophils were identified in mucosal biopsies from all participants. Mast cells were divided into phenotypes based on the presence of chymase. mRNA expression of mast cell-associated genes was measured by real-time PCR. The proportion of submucosal MCTC was higher in asthmatic individuals with AHR to mannitol compared with asthmatic individuals without AHR (median: 40.3% vs. 18.7%, P=0.03). Increased submucosal MCTC numbers were associated with increased levels of mRNA for thymic stromal lymphopoietin (TSLP) and CPA3 in asthmatics. Reactivity to mannitol correlated significantly with eosinophils in submucosa (r(s): 0.56, P=0.01). Airway hyperresponsiveness to inhaled mannitol is associated with an altered submucosal mast cell profile in asthmatic individuals. This mast cell profile is associated with increased levels of TSLP and CPA3. The degree of AHR to mannitol is correlated with the degree of eosinophilic inflammation in the airway submucosa.

Pharmacological Inhibition of TLR4 Reduces Mast Cell Activation, Neuroinflammation and Hyperalgesia in Sickle Mice

Sickle cell disease (SCD) is characterized by chronic hemolysis, inflammation, vascular dysfunction, and pain. Earlier we showed that mast cell activation contributes to neuroinflammation and pain and is accompanied by increased toll-like receptor 4 (TLR4) expression on mast cells (Vincent et al., Blood 2013), and that genetic deletion of TLR4 ameliorates neurogenic inflammation and hyperalgesia in HbSS-BERK sickle mice. Several other studies have shown increased TLR4 expression in peripheral system and its involvement in sickle pathobiology. We propose that free heme, due to hemolysis, activates TLR4 in the central nervous system in addition to peripheral activation, which further exacerbates neuroinflammation and hyperalgesia. Spinal cords of HbSS-BERK sickle mice show 3-fold mRNA transcripts for TLR4 and a 2-fold increase in hemin as compared to the spinal cords of HbAA-BERK control mice. Therefore, targeting TLR4 with pharmacological inhibitors may provide a therapeutic approach to attenuate peripheral and central inflammation and hyperalgesia. In the present study we examined the potential of pharmacological inhibition of mast cell activation, neuroinflammation and hyperalgesia in HbSS-BERK sickle mice with TLR4 inhibitor, TAK242. Sickle mice were administrated intravenously with TLR4 inhibitor TAK242 (1 mg/kg body weight/day) for 5 days. Sensory testing was performed at baseline at recruitment and periodically during the 5-day treatment and for another 8 days after concluding the treatment to evaluate mechanical hyperalgesia with von Frey filaments, thermal hyperalgesia in response to heat/cold and grip force for musculoskeletal/deep tissue hyperalgesia. Following the 5-day treatment with TAK242, release of cytokines, tryptase (marker of mast cell activation) and substance P released from skin biopsies and spinal cords were analyzed by ELISA. TAK242 significantly decreased the release of tryptase (TAK242: 5.178 ± 0.7613 pg/ml vs vehicle: 8.801 ± 0.9403 pg/ml, p = 0.0181), substance P (TAK242: 11.56 ± 1.945 pg/ml vs vehicle: 25.51 ± 4.283 pg/ml, p = 0.018), and IL-6 (TAK242: 15.59 ± 0.4541 pg/ml vs vehicle: 29.74 ± 0.8249 pg/ml, p = 0.0045) from skin biopsies, suggesting that TAK242 reduced SCD-induced mast cell activation and inflammation. TAK242 also significantly decreased substance P (TAK242: 0.7198 ± 0.0587 pg/mg vs vehicle: 0.931 ± 0.0676 pg/mg, p = 0.0462) and phosphorylation of p38/MAPK (p = 0.0184) in the spinal cord, as well as dorsal cutaneous blood flow (TAK242: 6.392 ± 0.3857 PU vs vehicle: 12.32 ± 0.5575 PU, p < 0.0001), indicating that TAK242 ameliorated SCD-evoked central and peripheral activation of inflammation and nociceptive mechanisms. Furthermore, TAK242 administration gradually reduced the mechanical, deep tissue, and thermal hyperalgesia upto 5-day treatment (p < 0.01, vs vehicle HbSS). However, discontinuation of treatment led to a gradual increase in hyperalgesia observed upto day-8 post-treatment. TAK242 also significantly decreased acute pain induced by hypoxia/reoxygenation and accelerated recovery from injury of hypoxia/reoxygenation. These data reveal the significant therapeutic effect of pharmacological inhibition of TLR4 on inflammation and hyperalgesia in sickle mice. Therapies targeting TLR4 inhibition may be potentially beneficial in ameliorating sickle pathobiology and pain. DisclosuresNo relevant conflicts of interest to declare.

Acupuncture Led Attenuation of Inflammatory and Nociceptive Peripheral and Central Microenvironment in Sickle Mice

Background: Inflammation, neurogenic inflammation and pain remain challenging to treat in sickle cell disease (SCD). Alternative therapies including acupuncture have been used for centuries to reduce pain and ameliorate underlying pathobiology of many disorders. We examined the mechanisms underlying acupuncture therapy in sickle mice. To prevent the influence of anesthetics and constraint on the pathobiology we developed electroacupuncture (EA) treatment for awake/conscious freely moving mice to simulate treatment conditions in patients, and then examined the peripheral and central mechanisms of neuroinflammation and nociception.Methods: HbSS-BERK sickle and HbAA-BERK control mice were treated with four EA treatments (every 3rd day, frequency: 4 or 10 Hz, pulse width: 100 microsecond, duration: 30 min) at acupoint GB30. Untreated and sham-EA treated (acupuncture without electrical stimulation) were used as controls. Hyperalgesia was evaluated daily by determining mechanical threshold, deep tissue hyperalgesia and thermal hyperalgesia using von Frey filaments, grip force, and cold plate, respectively. Blood and tissues were collected for analysis after four sessions of treatment. Skin biopsies were incubated overnight and culture medium was analyzed for mast cell activation marker tryptase, and neuromodulatory marker substance P.Results: Varied analgesic response to EA treatment was observed in sickle mice. About 86% treated mice equally showed positive (>50% pain relief) or moderate (20-30% pain relief) response and 14% were non-responsive (<20% pain relief) to EA. In positive responders, EA significantly reduced white blood cells (p<.001 Vs moderate- and non-responders), serum amyloid protein (p<.01 Vs untreated), IL-1beta (p<.05 Vs untreated, p<.01 Vs non-responders), and substance P (p<.05 Vs untreated and p<.001 Vs non-responders and p<.05 Vs moderate-responders). Concurrently, spinal cord analysis of EA treated positive-responders showed reduced substance P (p<.05 Vs untreated and non-responders), IL-1 beta (p<.01 Vs untreated), TNF alpha (p<.05 and p<.01 Vs moderate- and non-responders, respectively). Consistent with this central and peripheral anti-inflammatory response, culture medium from skin biopsies of positive responders demonstrated reduced substance P (p<.01 Vs moderate- and non-responders) and tryptase (p<.01 Vs untreated, moderate- and non-responders), and significantly less toluidine blue stained degranulating mast cells in the skin (p<.05 Vs untreated and non-responders) suggestive of attenuation of mast cell and peripheral nervous system activation. Functionally, capsaicin and substance P-induced neurogenic inflammation were significantly attenuated in positive-responders vs non-responders (p<.05) or untreated (p<.05). Peripheral and central attenuation of inflammatory and neurogenic response to EA was accompanied by inhibition of nociceptive signaling in the spinal cord. Spinal phosphorylation of p38 MAPK decreased in EA treated mice (p<.05 Vs sham-EA and untreated control; and positive-responders Vs non-responders).Conclusions: EA treatment on conscious free-moving mice simulates clinical conditions in patients and excludes the potential influence due to restraint or anesthetics. EA leads to peripheral and central neuromodulation and anti-inflammatory response by attenuating mast cell activation, substance P, and cytokine release in the periphery and by abrogating spinal nociceptive signaling of p38MAPK and inflammation. Together, these molecular and cellular effects lead to EA-induced attenuation of neurogenic inflammation and hyperalgesia in sickle mice. Importantly, these data explain the cause of variable effectiveness of EA in SCD. DisclosuresNo relevant conflicts of interest to declare.