Remimazolam-Induced Anaphylaxis and Cardiovascular Collapse: A Narrative Systematic Review of Eleven Cases.

Background and Objectives: Remimazolam, a novel benzodiazepine, is used for procedural sedation and general anesthesia due to its rapid onset and short duration of action. However, remimazolam-induced anaphylaxis (RIA) is a rare but severe complication. This study aimed to analyze RIA characteristics, focusing on cardiovascular collapse, and provide guidelines for safe remimazolam use. Methods: This study conducted a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. Research articles retrieved from PubMed on 26 May 2023, using the keywords 'remimazolam AND anaphylaxis' were evaluated based on the inclusion criteria of being written in English and aligning with the World Allergy Organization criteria for anaphylaxis, while studies not meeting these criteria were excluded. All published articles up to the search date were included without any date restrictions. The review analyzed factors such as age, sex, type of anesthesia, remimazolam dose (bolus/continuous), allergic symptoms and sign, epinephrine use, serum tryptase levels, and skin prick tests. Results: Among eleven cases, the mean age was 55.6 ± 19.6 years, with 81.8% male. Hypotension (81.8%) was the most common symptom, followed by bradycardia (54.5%) and desaturation (36.4%). Two patients experienced cardiac arrest. Serum tryptase levels confirmed anaphylaxis in ten cases. Epinephrine was the primary treatment, with intravenous doses ranging from 0.1 mg to 0.3 mg. Conclusions: Vigilance is crucial when administering remimazolam, adhering to recommended dosages, and promptly treating RIA with epinephrine. Further research is needed to understand the risk factors and refine the management strategies. Guidelines for safe remimazolam use are proposed.

[PRACTICE AND TRAINING RELATED TO USING ADRENALINE AUTOINJECTORS FOR PARAMEDICS: FACTS AND ISSUES].

BACKGROUND: Although paramedics can use adrenaline autoinjectors (AAIs) during their duties, the actual conditions of their use and the challenges faced remain unclear. We investigated the actual situation and issues pertaining to creating an environment in which paramedics can operate AAIs more effectively. METHODS: A web-based survey was conducted among paramedics who participated in a web-based training session related to their latest knowledge on food allergies and emergency responses in 2022. The survey items included practice and training environments, practices of AAI administration, and regarding AAI administration. RESULTS: Seventy paramedics responded to the survey. Twenty-eight respondents (40%) had experienced cases in which they wished they had an AAI in their work to date, but only one had actually administered one. Thirty-four (49%) indicated that it would be good to have an AAI in the ambulance at all times; 48 (69%) were not concerned about the use of AAI, and the level of concern about its use was significantly related to length of service. The study also revealed that paramedics do not have an adequate training environment regarding AAI. CONCLUSION: Few paramedics have experience in administering AAI, although they are aware of the need for it. For more effective use of AAI, it is necessary to establish a training environment to familiarize paramedics with anaphylaxis and an environment that enables them to use AAI promptly in the field.

Evaluation of treatment and long-term management of anaphylaxis in pediatric departments of Greece: a 2-year nationwide survey.

BACKGROUND: Anaphylaxis proportions of incidence are increasing globally. However, limited data are available regarding anaphylaxis in the pediatric population of Greece. PURPOSE: The aim of the study was to evaluate management of anaphylaxis in Greek pediatric departments. METHODS: We performed a questionnaire-based study of children aged less than 16 years presenting with anaphylaxis in 10 national pediatric hospitals over a period of 2 years. Management of anaphylaxis was assessed prior to and after an informative intervention. RESULTS: In all, 127 cases of anaphylaxis were identified. Epinephrine was administered in almost half of all cases (51.2%), predominantly through intramuscular route (88.5%), while the majority of anaphylaxis patients were treated with antihistamines (92.9%) and corticosteroids (70.1%). Epinephrine was more likely administered by physicians if the elicitor was a drug (P < 0.003). Regarding long-term management, an epinephrine auto-injector was prescribed in 66.9% of patients. Follow-up information was available for most of the patients (92.9%), the majority of whom (76.3%) were referred to an allergist. More than half of these patients (63.6%) had a documented allergy follow-up, which identified a causative allergen in 53.3% of cases. No statistically significant differences were recorded prior to and after the intervention regarding management of anaphylaxis. CONCLUSIONS: This nationwide study highlighted the necessity of further improvement in terms of anaphylaxis treatment and secondary prevention measures. This presupposes appropriate education and training of healthcare professionals, thus contributing to proper and comprehensive care of the pediatric population.

[EPIPEN INSTRUCTIONS FOR ANAPHYLAXIS PATIENTS DURING DISPENSING: FACTORS RELATED TO THE QUALITY OF PHARMACISTS' INSTRUCTIONS].

BACKGROUND AND AIM: We previously reported that pharmacists working in pharmacies don't have enough knowledge and enough experience teaching anaphylaxis (An) and EpiPen use. We administered a questionnaire survey to pharmacists with experience handling EpiPen prescriptions. We investigated the relationship between the questionnaire results and the factors in the pharmacists' background regarding the explanation and guidance to patients. RESULTS: The percentage of pharmacists working in pharmacies who provided guidance using visual information and demonstrations was insufficient. Moreover, this figure decreased after the second guidance session. Objective confirmation of patient understanding was also insufficient. The results indicated that self-examination and participation in drug information sessions were important background factors for pharmacists who provided detailed guidance to patients. DISCUSSION: For appropriate long-term management of their condition, An patients must master the EpiPen technique. Pharmacists' guidance plays a critical role in this regard. A support system should be established for proper instruction of pharmacy patients by improving pharmacists' self-education and other educational opportunities.

The confidence and competence of primary school staff to administer an adrenaline auto-injector.

School teachers are often inadequately prepared to use an adrenaline auto-injector (AAI), resulting in potentially dangerous treatment delays. The purpose of this study was to assess the observed competence, and self-reported confidence, of primary school teachers in the Republic of Ireland (RoI) to use an AAI. An evaluation of whether there was a link between confidence and competence was also assessed. Teachers from four primary schools in the RoI completed a questionnaire to assess their prior level of experience, training, and confidence levels with AAI administration. The four steps in administrating trainer AAI to a mannequin simulator were then assessed. A total of 61 teachers participated (out of a population of 80). The mean self-reported confidence was 1.82 out of 5 (SD = 0.96). There was no significant difference in confidence between trained and untrained participants (U = 240.5, NS). Participants who had received AAI administration training performed significantly more of the steps correctly (mean = 3.85, SD = 0.95) as compared to those who had received no training (mean = 2.97, SD = 1.10; U = 180.5, p = 0.008). There was no correlation between confidence in administrating AAI and the percentage of steps in the procedure performed correctly (rho = -0.17, NS).  Conclusion: Improvements in readiness to administer AAIs can be achieved through the application of more effective approaches to teaching clinical skills, changes to school policies and practices, and consideration of the design of AAIs in order to make their operation safer and simpler. It is important that teachers have the confidence and competence to safely administer an AAI. What is Known: • Poor ability in adrenaline auto-injector use seen across population groups-healthcare professionals, patients, carers, and school staff • Training in the use of adrenaline auto-injectors has positive impact on competency What is New: • Irish school teachers show poor levels of competency in adrenaline auto-injector use • No observed correlation between reported confidence and competency.

Revisiting dexamethasone use in the pediatric emergency department.

PURPOSE OF REVIEW: Dexamethasone is an essential treatment for common pediatric inflammatory, airway, and respiratory conditions. We aim to provide up-to-date recommendations for treatment of anaphylaxis, croup, coronavirus disease, multisystem inflammatory syndrome in children, and asthma with dexamethasone for use in the pediatric emergency department. RECENT FINDINGS: Literature largely continues to support the use of dexamethasone in most of the above conditions, however, recommendations for dosing and duration are evolving. SUMMARY: The findings discussed in this review will enable pediatric emergency medicine providers to use dexamethasone effectively as treatment of common pediatric conditions and minimize the occurrence of side-effects caused by gratuitous corticosteroid use.

A retrospective audit of adult and paediatric anaphylaxis management from two Australian metropolitan mixed emergency departments.

BACKGROUND: Anaphylaxis is a potentially life-threatening allergic reaction, with presentations to emergency departments (EDs) increasing across Australia. Understanding the features of those presenting with anaphylaxis and aspects related to its optimal clinical management across the admission, treatment and discharge settings is needed to minimise its impact. We aimed to evaluate the nature and management of presentations related to anaphylaxis across two Australian EDs. METHODS: Retrospective audit of paediatric and adult patients presenting to a community or tertiary level ED with anaphylaxis from 1 May 2018 to 30 April 2019. Data extracted from medical records included demographic characteristics, causative agents, clinical features, treatments administered across community, ambulance or ED settings, as well as post-discharge care arrangements including provision of Adrenaline Auto-Injector (AAI) and Allergy/Anaphylaxis Action Plan (AAP). RESULTS: A total of 369 (107 paediatric and 262 adult) ED presentations were identified. A total of 94 (36%) adult and 46 (43%) paediatric patients received pre-hospital adrenaline, with a further 91 (35%) adult and 29 (27%) paediatric patients receiving a dose of adrenaline in the ED. The most commonly administered treatment in ED were corticosteroids, given to 157 (60%) adult and 55 (51%) paediatric patients. Among those requiring an AAI for discharge, 123/210 (59%) adult and 57/91 (63%) of paediatric patients left hospital with an AAI. In contrast, among those requiring an allergy/anaphylaxis action plan (AAP) on discharge, 61/206 (30%) adult and 30/90 (33%) of paediatric patients left hospital with one. Factors associated with an increased likelihood of receiving AAI on discharge in paediatric and adult patients included receipt of any adrenaline, receipt of two or more doses of adrenaline, and longer duration of hospital stay. Adults presenting within business hours were more likely to be discharged with AAI, but no such difference was observed for paediatric patients. Similar findings were evident for provision of AAP on discharge. CONCLUSION: These findings demonstrate the need to improve assessment and treatment in the ED. In particular, the observed large variability in provision of AAI and AAP on discharge presents opportunities to explore strategies to improve awareness and provision of these critical components of post-discharge care.

Detecting epinephrine auto-injector shortages in Finland 2016-2022: Log-data analysis of online information seeking.

INTRODUCTION: Medicine shortages prevail as a worldwide problem causing life-threatening situations for adults and children. Epinephrine auto-injectors are used for serious allergic reactions called anaphylaxis, and alternative auto-injectors are not always available in pharmacies. Healthcare professionals in Finland use the dedicated internet source, Physician's Database (PD), when seeking medical information in practice, while Health Library (HL) provides health information for citizens (S1 Data). The objectives were to assess whether (1) professionals' searches for epinephrine auto-injectors and (2) citizens' anaphylaxis article openings relate to epinephrine shortages in Finland. METHODS: Monthly log data on epinephrine auto-injectors (EpiPen®, Jext®, Emerade®) from PD and on openings of anaphylaxis articles from HL were collected during 2016-2022. Professionals' searches of seven auto-injectors and citizens' openings of four anaphylaxis articles were compared to information on epinephrine shortages reported by Finnish Medicines Agency. Professionals' auto-injector prescriptions provided by Social Insurance Institution were also assessed. RESULTS: Total searches in EpiPen® (N = 111,740), Jext® (N = 25,631), and Emerade® (N = 18,329) could be analyzed during 2016-2022. EpiPen® only could visually show seasonal patterns during summertime, peaking vigorously in the summer of 2018 when the major EpiPen® shortage appeared worldwide. Anaphylaxis articles equaled 2,030,855 openings altogether. Openings of one anaphylaxis article ("Bites and Stings") peaked during summertime, while another article ("Anaphylactic Reaction") peaked only once (three-fold increase) at the end of 2020 when COVID-19 vaccinations started, and auto-injector prescriptions were lowest. Fifty EpiPen®, one Jext®, and twelve Emerade® shortages were reported. Almost a two-fold increase in peaks of auto-injector prescriptions was found during summertime. CONCLUSION: This study shows that (1) epinephrine shortages related to professionals' searching for auto-injectors, and (2) citizens' information seeking on anaphylaxis related to summertime and shortages with lesser prescriptions. Therefore, the dedicated internet databases aimed at professionals and citizens could be used as additional information sources to detect anaphylactic reactions and auto-injector shortages.

Prehospital and In-Hospital Treatment with Adrenaline and Related Prognosis in Anaphylaxis Patients.

INTRODUCTION: Although intramuscular adrenaline is the recommended first-line treatment for anaphylaxis, not all patients receive this treatment. The consequences in daily clinical practice are sparsely described. This study aimed to investigate the treatment administered to anaphylactic patients and the related prognosis. METHODS: A retrospective register-based study of patients with anaphylaxis referred to the allergy centre, Odense University Hospital (2019-2021). Each patient's medical records were reviewed for contacts with the emergency departments and the prehospital emergency medical service in the Region of Southern Denmark. The World Allergy Organization (WAO) grading system was used to assess the severity of prehospital and in-hospital anaphylaxis. Furthermore, the treatment administered to the patients was registered. RESULTS: In total, 315 patients were included. The prehospital system had contact with 256 of these patients (two were released prehospitally following treatment and 12 patients had insufficient data to assess anaphylaxis). Of the remaining 242 patients, 115 had anaphylaxis prehospitally (WAO grades 3-5); 59% (67/115) received adrenaline. Among the 67 patients who received prehospital adrenaline, 9 patients (13.4%; 95% CI: 6.3-24.0%) still had anaphylaxis at arrival at the emergency department. Of the 48 patients that were not treated with prehospital adrenaline, 17 patients (35.5%; 95% CI: 22.1-50.5) had anaphylaxis at the arrival to the emergency department. Among the 127 patients without prehospital anaphylaxis (WAO grades 0-2), 22 patients (18.2%; 95% CI: 11.8-26.2%) who did not receive prehospital adrenaline had anaphylaxis at arrival to the emergency department, while none of the 6 patients treated prehospitally with adrenaline had anaphylaxis. CONCLUSION: Omission of prehospital adrenaline in anaphylactic patients is associated with more severe anaphylactic symptoms at arrival to the hospital. Adrenaline treatment remains suboptimal since only half of the patients received prehospital adrenaline and only 1 out of 4 patients, with clinical signs of anaphylaxis, received adrenaline inside the hospital.

Allergy to Gibberellin-regulated proteins in an adolescent: A case of orange-induced anaphylaxis mediated by cofactors / Alergia a proteínas reguladas por giberelinas en un adolescente: un caso de anafilaxia inducida por naranja mediada por cofactores

This report is a case of anaphylaxis in an adolescent due to allergy to gibberellin-regulated proteins mediated by cofactors, in probable relation to a pollen/food allergy syndrome. It should also emphasizes the importance of obtaining a faithful clinical history, especially when it comes to adolescent patients as they tend to initiate toxic habits.(AU)

El pediatra de Atención Primaria y la anafilaxia / The primary care pediatrician and anaphylaxis

La anafilaxia es una reacción alérgica grave de instauración rápida y potencialmente mortal. El diagnóstico de anafilaxia es clínico y debe realizarse de manera precoz. Aparece en las 2 primeras horas tras exposición al alérgeno, en los primeros 30 minutos en alergia alimentaria y más precozmente con medicamentos intravenosos o picaduras de himenópteros. Los síntomas cutáneos suelen ser los primeros en manifestarse y están presentes en la mayoría de los casos, más de un 80%. Pueden ser leves o transitorios e incluso no estar presentes en un 18% de los casos. Si se afecta el sistema cardiocirculatorio estaríamos ante un shock anafiláctico. La causa más frecuente en Pediatría son los alimentos. Existen cofactores cuya presencia aumenta la probabilidad de anafilaxia; los más importantes son: el ejercicio, los fármacos, la fiebre y el estrés. El tratamiento de elección es la adrenalina intramuscular. Tanto los padres como los niños deben saber identificar los signos y/o síntomas del inicio de la anafilaxia para instaurar el tratamiento pautado en el plan de acción escrito.

Anaphylaxis is a severe, rapid and potentially fatal allergic reaction. The diagnosis of anaphylaxis is clinical and must be early. It appears in the first 2 hours after exposure to the allergen, in the first 30 minutes in food allergy and earlier with intravenous drugs or hymenoptera stings. Cutaneous symptoms are generally the first to appear and are present in most cases, more than 80%. They may be mild or transitory, or absent in 18% of cases. If the cardio-circulatory system is affected, an anaphylactic shock occurs. The most frequent cause in pediatrics is nutrition. There are several cofactors whose presence increases the likelihood of anaphylaxis; the most important are: exercise, medication, fever and stress. The treatment of choice is intramuscular adrenaline. Parents and children should be able to identify the signs and/or symptoms of anaphylaxis in order to implement the treatment prescribed in the written action plan. (AU)

NButGT Reinforces the Beneficial Effects of Epinephrine on Cardiac Mitochondrial Respiration, Lactatemia and Cardiac Output in Experimental Anaphylactic Shock.

Anaphylactic shock (AS) is the most severe form of acute systemic hypersensitivity reaction. Although epinephrine can restore patients' hemodynamics, it might also be harmful, supporting the need for adjuvant treatment. We therefore investigated whether NButGT, enhancing O-GlcNAcylation and showing beneficial effects in acute heart failure might improve AS therapy. Ovalbumin-sensitized rats were randomly allocated to six groups: control (CON), shock (AS), shock treated with NButGT alone before (AS+pre-Nbut) or after (AS+post-Nbut) AS onset, shock treated with epinephrine alone (AS+EPI) and shock group treated with combination of epinephrine and NButGT (AS+EPI+preNBut). Induction of shock was performed with an intravenous (IV) ovalbumin. Cardiac protein and cycling enzymes O-GlcNAcylation levels, mean arterial pressure (MAP), heart rate, cardiac output (CO), left ventricle shortening fraction (LVSF), mitochondrial respiration, and lactatemia were evaluated using Western blotting experiments, invasive arterial monitoring, echocardiography, mitochondrial oximetry and arterial blood samples. AS decreased MAP (-77%, p < 0.001), CO (-90%, p < 0.001) and LVSF (-30%, p < 0.05). Epinephrine improved these parameters and, in particular, rats did not die in 15 min. But, cardiac mitochondrial respiration remained impaired (complexes I + II -29%, p < 0.05 and II -40%, p < 0.001) with hyperlactatemia. NButGT pretreatment (AS+pre-Nbut) efficiently increased cardiac O-GlcNAcylation level as compared to the AS+post-Nbut group. Compared to epinephrine alone, the adjunction of NButGT significantly improved CO, LVSF and mitochondrial respiration. MAP was not significantly increased but lactatemia decreased more markedly. Pretreatment with NButGT increases O-GlcNAcylation of cardiac proteins and has an additive effect on epinephrine, improving cardiac output and mitochondrial respiration and decreasing blood lactate levels. This new therapy might be useful when the risk of AS cannot be avoided.

Free PEG Suppresses Anaphylaxis to PEGylated Nanomedicine in Swine.

Covalent conjugation of poly(ethylene glycol) (PEG) is frequently employed to enhance the pharmacokinetics and biodistribution of various protein and nanoparticle therapeutics. Unfortunately, some PEGylated drugs can induce elevated levels of antibodies that can bind PEG, i.e., anti-PEG antibodies (APA), in some patients. APA in turn can reduce the efficacy and increase the risks of allergic reactions, including anaphylaxis. There is currently no intervention available in the clinic that specifically mitigates allergic reactions to PEGylated drugs without the use of broad immunosuppression. We previously showed that infusion of high molecular weight free PEG could safely and effectively suppress the induction of APA in mice and restore prolonged circulation of various PEGylated therapeutics. Here, we explored the effectiveness of free PEG as a prophylaxis against anaphylaxis induced by PEG-specific allergic reactions in swine. Injection of PEG-liposomes (PL) resulted in anaphylactoid shock (pseudoanaphylaxis) within 1-3 min in both naïve and PL-sensitized swine. In contrast, repeated injection of free PEG alone did not result in allergic reactions, and injection of free PEG effectively suppressed allergic reactions to PL, including in previously PL-sensitized swine. These results strongly support the further investigation of free PEG for reducing APA and allergic responses to PEGylated therapeutics.

[TWO CASES OF LARYNGEAL EDEMA CAUSED BY SUBLINGUAL ALLERGEN IMMUNOTHERAPY].

Sublingual immunotherapy is a widely used treatment, and serious adverse reactions such as anaphylaxis are rare. We report two cases of laryngeal edema as adverse reactions to sublingual immunotherapy, which could be continued due to a change in the administration method. Case 1 presents a 15-year-old male suspected to have had anaphylaxis due to the dust at the age of 6 years. He started treatment with Miticure® and developed laryngeal edema 30 minutes after taking the 10000JAU dose on the 10th day. laryngeal edema was treated with intravenous infusion. Case 2 presents a 48-year-old woman. She started treatment with Cidacure® and developed respiratory distress and laryngeal edema 1 hour after taking the 5000JAU dose on the 5th day. she had resolved mildly without therapeutic intervention. In both cases, the patients were switched to sublingual spitting, resumed with the initial dose cautiously, and were able to continue. Sublingual immunotherapy is a safe treatment, but sudden adverse reactions may occur. Laryngeal symptoms may be treated by changing to the sublingual spitting method, but laryngeal findings should be examined, and the dosage should be carefully increased.

Risk of Anaphylaxis Among New Users of GLP-1 Receptor Agonists: A Cohort Study.

OBJECTIVE: To assess risk of anaphylaxis among patients with type 2 diabetes mellitus who are initiating therapy with a glucagon-like peptide 1 receptor agonist (GLP-1 RA), with a focus on those starting lixisenatide therapy. RESEARCH DESIGN AND METHODS: A cohort study was conducted in three large, U.S. claims databases (2017-2021). Adult (aged ≥18 years) new users of a GLP-1 RA who had type 2 diabetes mellitus and ≥6 months enrollment in the database before GLP-1 RA initiation (start of follow-up) were included. GLP-1 RAs evaluated were lixisenatide, an insulin glargine/lixisenatide fixed-ratio combination (FRC), exenatide, liraglutide or insulin degludec/liraglutide FRC, dulaglutide, and semaglutide (injectable and oral). The first anaphylaxis event during follow-up was identified using a validated algorithm. Incidence rates (IRs) and 95% CIs were calculated within each medication cohort. The unadjusted IR ratio (IRR) comparing anaphylaxis rates in the lixisenatide cohort with all other GLP-1 RAs combined was analyzed post hoc. RESULTS: There were 696,089 new users with 456,612 person-years of exposure to GLP-1 RAs. Baseline demographics, comorbidities, and use of other prescription medications in the 6 months before the index date were similar across medication cohorts. IRs (95% CIs) per 10,000 person-years were 1.0 (0.0-5.6) for lixisenatide, 6.0 (3.6-9.4) for exenatide, 5.1 (3.7-7.0) for liraglutide, 3.9 (3.1-4.8) for dulaglutide, and 3.6 (2.6-4.9) for semaglutide. The IRR (95% CI) for the anaphylaxis rate for the lixisenatide cohort compared with the pooled other GLP-1 RA cohort was 0.24 (0.01-1.35). CONCLUSIONS: Anaphylaxis is rare with GLP-1 RAs. Lixisenatide is unlikely to confer higher risk of anaphylaxis than other GLP-1 RAs.

Butyrate, Valerate, and Niacin Ameliorate Anaphylaxis by Suppressing IgE-Dependent Mast Cell Activation: Roles of GPR109A, PGE2, and Epigenetic Regulation.

Short-chain fatty acids (SCFAs) are produced by the intestinal microbiota during the fermentation of dietary fibers as secondary metabolites. Several recent studies reported that SCFAs modulate the development and function of immune-related cells. However, the molecular mechanisms by which SCFAs regulate mast cells (MCs) remain unclear. In the current study, we analyzed the function and gene expression of mouse MCs in the presence of SCFAs in vitro and in vivo. We found that the oral administration of valerate or butyrate ameliorated passive systemic anaphylaxis and passive cutaneous anaphylaxis in mice. The majority of SCFAs, particularly propionate, butyrate, valerate, and isovalerate, suppressed the IgE-mediated degranulation of bone marrow-derived MCs, which were eliminated by the Gi protein inhibitor pertussis toxin and by the knockdown of Gpr109a. A treatment with the HDAC inhibitor trichostatin A also suppressed IgE-mediated MC activation and reduced the surface expression level of FcεRI on MCs. Acetylsalicylic acid and indomethacin attenuated the suppressive effects of SCFAs on degranulation. The degranulation degree was significantly reduced by PGE2 but not by PGD2. Furthermore, SCFAs enhanced PGE2 release from stimulated MCs. The SCFA-mediated amelioration of anaphylaxis was exacerbated by COX inhibitors and an EP3 antagonist, but not by an EP4 antagonist. The administration of niacin, a ligand of GPR109A, alleviated the symptoms of passive cutaneous anaphylaxis, which was inhibited by cyclooxygenase inhibitors and the EP3 antagonist. We conclude that SCFAs suppress IgE-mediated activation of MCs in vivo and in vitro involving GPR109A, PGE2, and epigenetic regulation.