Cardiac anaphylaxis: pathophysiology and therapeutic perspectives

Function and Role of Histamine H1 Receptor in the Mammalian Heart

Histamine can change the force of cardiac contraction and alter the beating rate in mammals, including humans. However, striking species and regional differences have been observed. Depending on the species and the cardiac region (atrium versus ventricle) studied, the contractile, chronotropic, dromotropic, and bathmotropic effects of histamine vary. Histamine is present and is produced in the mammalian heart. Thus, histamine may exert autocrine or paracrine effects in the mammalian heart. Histamine uses at least four heptahelical receptors: H1, H2, H3 and H4. Depending on the species and region studied, cardiomyocytes express only histamine H1 or only histamine H2 receptors or both. These receptors are not necessarily functional concerning contractility. We have considerable knowledge of the cardiac expression and function of histamine H2 receptors. In contrast, we have a poor understanding of the cardiac role of the histamine H1 receptor. Therefore, we address the structure, signal transduction, and expressional regulation of the histamine H1 receptor with an eye on its cardiac role. We point out signal transduction and the role of the histamine H1 receptor in various animal species. This review aims to identify gaps in our knowledge of cardiac histamine H1 receptors. We highlight where the published research shows disagreements and requires a new approach. Moreover, we show that diseases alter the expression and functional effects of histamine H1 receptors in the heart. We found that antidepressive drugs and neuroleptic drugs might act as antagonists of cardiac histamine H1 receptors, and believe that histamine H1 receptors in the heart might be attractive targets for drug therapy. The authors believe that a better understanding of the role of histamine H1 receptors in the human heart might be clinically relevant for improving drug therapy.

Cellular and Immunohistochemical Changes in Anaphylactic Shock Induced in the Ovalbumin-Sensitized Wistar Rat Model

Anaphylactic shock (AS) is a life-threatening, multisystem disorder arising from sudden release of mast cell- and basophil-derived mediators into the circulation. In this study, we have used a Wistar rat model to investigate AS-associated histopathologic changes in various organs. Rats were sensitized with ovalbumin (1 mg s.c), and AS was induced by intravenous injection of ovalbumin (1 mg). Experimental groups included nonallergic rats (n = 6) and allergic rats (n = 6). Heart rate and blood pressure were monitored during one hour. Organs were harvested at the end of the experiment and prepared for histologic and immunohistochemical studies. Lung, small bowel mucosa and spleen were found to undergo heavy infiltration by mast cells and eosinophils, with less prominent mast cell infiltration of cardiac tissue. The mast cells in lung, small bowel and spleen exhibited increased expression of tryptase, c-kit and induced nitric oxide synthase (iNOS). Increased expression of endothelial nitric oxide synthase (eNOS) by vascular endothelial cells was noted principally in lung, heart and small bowel wall. The Wistar rat model of AS exhibited accumulation of mast cells and eosinophils in the lung, small bowel, and spleen to a greater extent than in the heart. We conclude that lung and gut are principal inflammatory targets in AS, and likely contribute to the severe hypotension of AS. Targeting nitric oxide (NO) production may help reduce AS mortality.

Histamine pharmacology: from Sir Henry Dale to the 21st century

Histamine has been one of the most studied substances in medicine, playing a major role in diverse (patho)physiological processes. It elicits its multifaceted modulatory functions by activating four types of GPCRs, designated as H_1-4 . Despite the heterogeneity and the complexity of histamine receptor pharmacology, many discoveries over the past 100 years resulted in the development of H₁ antihistamines and H₂ -targeting 'blockbuster' therapeutics for the management of allergies and gastrointestinal disorders respectively. Recently, a first-in-class H₃ inverse agonist was approved for the treatment of narcolepsy, whereas H₄ antagonists are under clinical evaluation for their potential therapeutic exploitation in immune-related diseases. This review critically presents the past successes and drawbacks in histamine research, complemented by the modern conceptual innovations in molecular and receptor pharmacology. It targets both young and experienced researchers in an ongoing effort to stimulate novel insights for the dissection of the translational potential of histamine pharmacology. LINKED ARTICLES: This article is part of a themed section on New Uses for 21st Century. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.3/issuetoc.

Acute myocardial infarction in a patient suffering from penicillin-induced laryngeal edema : Kounis syndrome aggravated by adrenaline

Kounis syndrome or allergic angina is defined as the coincidental occurrence of chest pain and allergic reactions accompanied by clinical and laboratory findings of classical angina pectoris. It is triggered by the action of potent vasoactive and inflammatory mediators, which are released from the mast cells during the allergic reaction. Epinephrine is a life-saving medication in anaphylaxis; however, it can aggravate ischemia and induce coronary vasospasm and arrhythmias. Here, we present a patient with Kounis syndrome that was caused by intramuscular injection of procaine penicillin G, and in whom epinephrine administration for treatment of laryngeal edema had provoked severe myocardial ischemia.

Allergic angina following wasp sting: Kounis syndrome

Kounis syndrome is defined as an acute coronary syndrome triggered by the release of inflammatory mediators following an allergic insult characterized by acute onset of breathlessness, palpitations, diaphoresis and chest tightness (Gázquez V, Dalmau G, Gaig P, Gómez C, Navarro S, Mercé J. Kounis syndrome: report of 5 cases. J Investig Allergol Clin Immunol 2010;20:162–5). We report a 20-year-male patient who presented with acute myocardial infarction following a wasp sting at our institute. ECG showed non-ST-elevation myocardial infarction. Symptoms settled with hydrocortisone and adrenaline. Coronary angiogram revealed normal epicardial coronaries.

Intraoperative "Kounis syndrome" that improved electrocardiography changes and hemodynamic situation after administering nitroglycerine

A 58-year-old female without cardiovascular risk factors, was going to be operated to repair the rotator cuff. Induction and interscalene brachial plexus block were uneventful, but after her placement for surgery the patient started with severe bronchospasm, hypotension, cutaneous allergic reaction and ST elevation on the electrocardiogram. An anaphylactic shock was suspected and treated but until the perfusion of nitroglycerina was started no electrocardiographic changes resolved. After necessary diagnostic test the final diagnosis was variant I of Kounis syndrome due to cefazolin and rocuronium. Ephinephrine is the cornerstone of treatment for anaphylaxis but should we use it if the anaphylactic reaction is also accompanied by myocardial ischemia? The answer is that we should not use it because myocardial ischemia in this syndrome is caused by vasospasm, so it would be more useful drugs such as nitroglycerin. But what if we do not know if it is a Kounis syndrome or not? In this article we report our experience that maybe could help you in a similar situation.

Kounis syndrome resulting from anaphylaxis to diclofenac

“Kounis syndrome” refers to acute coronary syndromes of varying degree (myocardial ischaemia to infarction) induced by mast cell activation as a result of allergic and anaphylactic reactions. ST-segment elevated myocardial infarction is a rare complication that can occur even in patients with normal coronary arteries due to anaphylactic reactions. We present a case that developed acute myocardial infarction following a diclofenac sodium-induced anaphylaxis. The patient did not have any previous coronary artery disease, but there was a temporal relationship with development of the anaphylactic reaction due to diclofenac sodium and the cardiac event. The patient was managed conservatively and the recovery was uneventful.

Immediate hypersensitivity elicits renin release from cardiac mast cells

BACKGROUND

We recently reported that murine and cavian heart mast cells are a unique extrarenal source of renin. Ischemia/reperfusion releases this renin leading to local angiotensin formation and norepinephrine release. As mast cells are a primary target of hypersensitivity, we assessed whether anaphylactic mast cell degranulation also results in renin and norepinephrine release.

METHODS

Hearts isolated from presensitized guinea pigs were challenged with antigen.

RESULTS

Cardiac anaphylaxis was characterized by mast cell degranulation, evidenced by beta-hexosaminidase release and associated with renin and norepinephrine release. Mast cell stabilization with cromolyn or lodoxamide markedly attenuated the release of beta-hexosaminidase, renin and norepinephrine. Renin inhibition with BILA2157 did not affect mast cell degranulation, but attenuated norepinephrine release.

CONCLUSIONS

Our findings disclose that immediate-type hypersensitivity elicits renin release from mast cells, activating a local renin-angiotensin system, thereby promoting norepinephrine release. As renin is stored in human heart mast cells, allergic reactions could initiate renin release, leading to local angiotensin formation and hyperadrenergic dysfunction.

Midventricular hypokinesis as a cardiac manifestation of anaphylaxis: a case report

We report a case of anaphylaxis in which left midventricular hypokinesis was found by echocardiogram performed while the patient was hypotensive shortly after the onset of acute chest pain with S-T segment elevations. Cardiac injury was confirmed by elevation of cardiac enzymes. Repeated echocardiogram 2 days later demonstrated normal ventricular wall function and coronary angiogram demonstrated no angiographically apparent disease. We discuss possible mechanisms for cardiac injury and suggest mast cell-mediated coronary spasm as the most likely.