Anaphylaxis

Combined Treatment with KV Channel Inhibitor 4-Aminopyridine and either γ-Cystathionine Lyase Inhibitor β-Cyanoalanine or Epinephrine Restores Blood Pressure, and Improves Survival in the Wistar Rat Model of Anaphylactic Shock

Simple Summary

Allergic diseases are presenting a constant increase all over the world and caused by such different substances as food, drugs, and pollens. Anaphylactic shock is the more severe complication of allergy which can induce death if the treatment is not administered immediately. Some patients do not respond to the recommended treatment, intra venous or intramuscular epinephrine. The pathophysiology of anaphylactic shock is still under investigation. The mediators released after the activation of mast cells and basophiles act on endothelial cells and smooth muscle cells, inducing the vasodilation responsible for hypotension and shock. Nitric oxide and hydrogen sulphide are both intracellular mediators that induce vasodilation. The role of potassium voltage dependent channels is suspected. We aimed to demonstrate the ability of a blocker of potassium voltage dependent channels, 4-aminopyridine, alone or in combination with inhibitors of cystathionine γ-lyase to restore blood pressure and improve survival in an ovalbumin rat anaphylactic shock model. The blockade of potassium voltage dependent channels alone or combined with inhibitors of cystathionine γ-lyase, dl-propargylglycine, or β-cyanoalanine restored blood pressure and improved survival. These findings suggest possible investigative treatment pathways for research concerning epinephrine-refractory anaphylactic shock in patients.

Abstract

The mechanism of anaphylactic shock (AS) remains incompletely understood. The potassium channel blocker 4-aminopyridine (4-AP), the inhibitors of cystathionine γ-lyase (ICSE), dl-propargylglycine (DPG) or β-cyanoalanine (BCA), and the nitric oxide (NO) synthase produce vasoconstriction and could be an alternative for the treatment of AS. The aim of this study was to demonstrate the ability of L-NAME, ICSE alone or in combination with 4-AP to restore blood pressure (BP) and improve survival in ovalbumin (OVA) rats AS. Experimental groups included non-sensitized Wistar rats (n = 6); AS (n = 6); AS (n = 10 per group) treated i.v. with 4-AP (AS+4-AP), epinephrine (AS+EPI), AS+DPG, AS+BCA, or with L-NAME (AS+L-NAME); or AS treated with drug combinations 4-AP+DPG, 4-AP+BCA, 4-AP+L-NAME, or 4-AP+EPI. AS was induced by i.v. OVA (1 mg). Treatments were administered i.v. one minute after AS induction. Mean arterial BP (MAP), heart rate (HR), and survival were monitored for 60 min. Plasma levels of histamine, prostaglandin E2 (PGE2) and F2 (PGF2α), leukotriene B4 and C4, angiotensin II, vasopressin, oxidative stress markers, pH, HCO3, PaO2, PaCO2, and K+ were measured. OVA induced severe hypotension and all AS rats died. Moreover, 4-AP, 4-AP+EPI, or 4-AP+BCA normalized both MAP and HR and increased survival. All sensitized rats treated with 4-AP alone or with 4-AP+BCA survived. The time-integrated MAP “area under the curve” was significantly higher after combined 4-AP treatment with ICSE. Metabolic acidosis was not rescued and NO, ICSE, and Kv inhibitors differentially alter oxidative stress and plasma levels of anaphylactic mediators. The AS-induced reduction of serum angiotensin II levels was prevented by 4-AP treatment alone or in combination with other drugs. Further, 4-AP treatment combined with EPI or with BCA also increased serum PGF2α, whereas only the 4-AP+EPI combination increased serum LTB4. Serum vasopressin and angiotensin II levels were increased by 4-AP treatment alone or in combination with other drugs. Moreover, 4-AP alone and in combination with inhibition of cystathionine γ-lyase or EPI normalizes BP, increases serum vasoconstrictor levels, and improves survival in the Wistar rat model of AS. These findings suggest possible investigative treatment pathways for research into epinephrine-refractory anaphylactic shock in patients.

Effect of Nitric Oxide Pathway Inhibition on the Evolution of Anaphylactic Shock in Animal Models: A Systematic Review

Simple Summary

Anaphylactic shock (AS) is the most serious consequence of anaphylaxis, with life-threatening sequelae including hypovolemia, shock, and arrhythmias. The literature lacks evidence for the effectiveness of interventions other than epinephrine in the acute phase of anaphylaxis. Our objective was to assess, through a systematic review, how inhibition of nitric oxide (NO) pathways affects blood pressure, and whether such blockade improves survival in AS animal models. AS was induced in all included studies after or before drug administration that targeted blockade of the NO pathway. In all animal species studied, the induction of AS caused a reduction in arterial blood pressure. However, the results show different responses to the inhibition of nitric oxide pathways. Overall, seven of fourteen studies using inhibition of nitric oxide pathways as pre-treatment before induction of AS showed improvement of survival and/or blood pressure. Four post-treatment studies from eight also showed positive outcomes. This review did not find strong evidence to propose modulation of blockade of the NO/cGMP pathway as a definitive treatment for AS in humans. Well-designed in vivo AS animal pharmacological models are needed to explore the other pathways involved, supporting the concept of pharmacological modulation.

Abstract

Nitric oxide (NO) induces vasodilation in various types of shock. The effect of pharmacological modulation of the NO pathway in anaphylactic shock (AS) remains poorly understood. Our objective was to assess, through a systematic review, whether inhibition of NO pathways (INOP) was beneficial for the prevention and/or treatment of AS. A predesigned protocol for this systematic review was published in PROSPERO (CRD42019132273). A systematic literature search was conducted till March 2022 in the electronic databases PubMed, EMBASE, Scopus, Cochrane and Web of Science. Heterogeneity of the studies did not allow meta-analysis. Nine hundred ninety unique studies were identified. Of 135 studies screened in full text, 17 were included in the review. Among six inhibitors of NO pathways identified, four blocked NO synthase activity and two blocked guanylate cyclase downstream activity. Pre-treatment was used in nine studies and post-treatment in three studies. Five studies included both pre-treatment and post-treatment models. Overall, seven pre-treatment studies from fourteen showed improvement of survival and/or arterial blood pressure. Four post-treatment studies from eight showed positive outcomes. Overall, there was no strong evidence to conclude that isolated blockade of the NO/cGMP pathway is sufficient to prevent or restore anaphylactic hypotension. Further studies are needed to analyze the effect of drug combinations in the treatment of AS.

Proposed Pathogenesis of Diffuse Alveolar Hemorrhage in Idiopathic Pulmonary Hemosiderosis

Idiopathic pulmonary hemosiderosis (IPH) is a rare disease that causes diffuse alveolar hemorrhage (DAH). The latest data suggests an immunologic origin of IPH, and a new name, immune mediated pulmonary hemosiderosis (ImPH), has been proposed. However, the exact immunologic mechanism has remained elusive for nearly eight decades despite extensive research, including detailed histopathologic analysis. Although several hypotheses have been proposed to describe the pathobiology of IPH, none of them explain the clinical and histopathologic findings conclusively. In this manuscript, we have presented a new hypothesis for the pathogenesis of DAH in IPH. We hypothesize that DAH in IPH is not immunocomplex mediated but due to histamine, eosinophilic cationic protein (ECP), and possibly vascular endothelial growth factor (VEGF). These bioactive proteins induce endothelial and alveolar epithelial damage, leading to the peri-capillary and intraalveolar escape of RBCs. The deformability of the RBC likely also plays a role. The supranormal secretion of histamine, ECP and VEGF occurs in genetically predisposed individuals with an aberrant immunologic response. The histamine is released from the basophils and possibly the mast cells in response to cytokines secreted by activated lymphocytes. The lymphocyte activation occurs after exposure to a known (gluten) or unknown antigen. The same lymphocyte-derived cytokines also induce eosinophilic degranulation of ECP and VEGF in the pulmonary circulation. We believe that our hypothesis unifies the observed clinical variabilities and histopathologic findings in IPH, and we hope that would promote future research in the field of IPH.

Glycolysis is integral to histamine-induced endothelial hyperpermeability

Histamine-induced vascular leakage is a core process of allergic pathologies, including anaphylaxis. Here, we show that glycolysis is integral to histamine-induced endothelial barrier disruption and hyperpermeability. Histamine rapidly enhanced glycolysis in endothelial cells via a pathway that involved histamine receptor 1 and phospholipase C beta signaling. Consistently, partial inhibition of glycolysis with 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO) prevented histamine-induced hyperpermeability in human microvascular endothelial cells, by abolishing the histamine-induced actomyosin contraction, focal adherens junction formation, and endothelial barrier disruption. Pharmacologic blockade of glycolysis with 3PO in mice reduced histamine-induced vascular hyperpermeability, prevented vascular leakage in passive cutaneous anaphylaxis and protected from systemic anaphylaxis. In conclusion, we elucidated the role of glycolysis in histamine-induced disruption of endothelial barrier integrity. Our data thereby point to endothelial glycolysis as a novel therapeutic target for human pathologies related to excessive vascular leakage, such as systemic anaphylaxis.

Circulatory collapse during wound closure in spine surgery with an unknown cause: a possible adverse effect of topical application of vancomycin?

BACKGROUND

Vancomycin (VCM) is effective in fighting Gram-positive bacteria related severe infections, and topical application of VCM powder is widely used in orthopedic surgery to prevent wound infection. However, VCM could lead to infusion rate-dependent antibody-and complement-independent anaphylaxis reaction by inducing direct release of histamine.

CASE PRESENTATION

We retrospectively analyzed seven cases of severe hypotension and shock during wound closure or immediately after orthopedic surgery with unidentifiable reasons. We found that these cases were all associated with local application of VCM powder during wound closure process. Two patients experienced sudden cardiac arrest. Most of the cases (6/7) with circulatory collapse were discharged without severe sequelae. While one case with application of 3 g VCM developed cardiac arrest and remained in a coma due to hypoxic-hypoxic encephalopathy. The clinical presentations and the time of the shock onset were considered to be related with a VCM induced anaphylaxis reaction. However, as this was a retrospective study, and there was no laboratory examination performed, the conclusion was made upon differential diagnosis based on clinical manifestations and the timing of the shock.

CONCLUSIONS

Local application of VCM may not be as safe as was once believed and may lead to a related anaphylaxis. As VCM induced infusion-rate dependent, non-IgE mediated anaphylaxis is characterized by delayed occurrence, severe hypotension and even circulatory collapse, surgeons and anesthesiologists should be extra vigilant during and after VCM application.

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.

4-Aminopyridine, A Blocker of Voltage-Dependent K+ Channels, Restores Blood Pressure and Improves Survival in the Wistar Rat Model of Anaphylactic Shock

OBJECTIVES

Anaphylactic shock is associated with severe hypotension. Potassium channel blockers, such as 4-aminopyridine, induce vasoconstriction. The objective of this study was to test the ability of 4-aminopyridine to restore blood pressure and increase survival in anaphylactic shock.

DESIGN

Experimental study.

SETTING

Physiology laboratory.

SUBJECTS

Adult male Wistar rats.

INTERVENTIONS

Rats were sensitized with ovalbumin (1 mg SC), and anaphylactic shock was induced by IV injection of ovalbumin (1 mg). Experimental groups included non-allergic rats (NA) (n = 6); allergic rats (Controls) (n = 6); allergic rats treated with 4-aminopyridine (4-aminopyridine) (1 mg/kg) (n = 6); and allergic rats treated with epinephrine (EPI) (10 µg/kg) (n = 6). Treatments were administered 1 minute after induction of anaphylactic shock.

MEASUREMENTS AND MAIN RESULTS

Mean arterial blood pressure, heart rate, and survival were measured for 60 minutes. Plasma levels of histamine, leukotriene B4, prostaglandin E2, prostaglandin F2, pH, and HCO3 were measured. Mean arterial blood pressure was normal in the NA group; severe hypotension and high mortality were observed in controls; normalization of mean arterial blood pressure, heart rate, and increased survival were observed in 4-aminopyridine and EPI groups. All allergic 4-aminopyridine-treated rats survived after the induction of anaphylactic shock. Histamine level was higher in controls and the 4-aminopyridine group but reduced in the EPI group. Prostaglandin E2 increased in controls and EPI group and decreased in 4-aminopyridine group; prostaglandin F2 increased in controls but decreased in 4-aminopyridine and EPI groups. Leukotriene B4 decreased in 4-aminopyridine and EPI groups. Metabolic acidosis was prevented in the 4-aminopyridine group.

CONCLUSIONS

Our data suggest that voltage-dependent K+ channel inhibition with 4-aminopyridine treatment restores blood pressure and increases survival in the Wistar rat model of anaphylactic shock. 4-aminopyridine or related voltage-dependent K channel blockers could be a useful additional therapeutic approach to treatment of refractory anaphylactic shock.

RhoA and ROCK mediate histamine-induced vascular leakage and anaphylactic shock

Histamine-induced vascular leakage is an integral component of many highly prevalent human diseases, including allergies, asthma, and anaphylaxis. Yet, how histamine induces the disruption of the endothelial barrier is not well defined. By using genetically modified animal models, pharmacologic inhibitors, and a synthetic biology approach, here we show that the small GTPase RhoA mediates histamine-induced vascular leakage. Histamine causes the rapid formation of focal adherens junctions, disrupting the endothelial barrier by acting on H1R Gα_q-coupled receptors, which is blunted in endothelial Gα_q/11 KO mice. Interfering with RhoA and ROCK function abolishes endothelial permeability, while phospholipase Cβ plays a limited role. Moreover, endothelial-specific RhoA gene deletion prevents vascular leakage and passive cutaneous anaphylaxis in vivo, and ROCK inhibitors protect from lethal systemic anaphylaxis. This study supports a key role for the RhoA signaling circuitry in vascular permeability, thereby identifying novel pharmacological targets for many human diseases characterized by aberrant vascular leakage.

Exercise-induced Anaphylaxis: the Role of Cofactors

Introduction:

Anaphylaxis is a dramatic clinical emergency. It is a very severe, life-threatening generalized or systemic hypersensitivity reaction. Based on immunologic mechanism the anaphylaxis is divided in IgE, IgG, complement, or immune complexes-mediated vs non allergic anaphylaxis. There are a lot of etiologic factors of anaphylaxis, but the three principal immunologic triggers are drugs, insect stings, and foods. Regarding the clinical severity there are several proposed grading systems. The diagnosis of anaphylaxis is mainly clinical.

Discussion:

The anaphylaxis markers measured in clinical laboratories are total tryptase and histamine. There are some conditions that modulate the onset of anaphylaxis, acting as co- or augmentation factors, which significantly lower the allergen dose necessary for triggering anaphylaxis. The well-documented cofactors of anaphylaxis are physical exercise, alcohol consumption, some foods, co-administration of nonsteroidal anti-inflammatory drugs (NSAID), and concomitant infectious diseases. Development of anaphylaxis depends on the sensitization pattern, the proportion of the involved immunoglobulin classes, characteristics of the allergen, the proportion of the involved immunoglobulin classes, the avidity and affinity of immunoglobulins to bind an allergen, the route of allergen application, and, last but not least, the presence of cofactors of anaphylaxis.

Conclusion:

Anaphylaxis remains a continuous challenge for the diagnosis and treatment. The adequate management of anaphylaxis requires rapid diagnosis, implementation of primary and secondary prevention measures, and immediate administration of subcutaneous epinephrine.

Immunologic evaluation of immediate hypersensitivity to cefaclor

PURPOSE

Cefaclor is widely prescribed for various infectious diseases. As its consumption increases, the number of hypersensitivity reactions to cefaclor has increased. This study aimed to evaluate the immunologic findings of immediate hypersensitivity to cefaclor.

MATERIALS AND METHODS

We enrolled 47 patients with immediate hypersensitivity to cefaclor from Ajou University Hospital and Asan Medical Center. Serum specific IgE, IgG1, and IgG4 antibodies to cefaclor-human serum albumin (HSA) conjugate were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The most common phenotype was anaphylaxis (Group I, 78.7%), followed by urticaria (Group II, 21.3%). The detection of specific IgE, IgG1, and IgG4 to cefaclor-HSA conjugate by ELISA tended to be higher in Group I (40.5%, 41.7%, 21.6%) than in Group II (20.0%, 20.0%, 0%) with no statistical significance. Significant associations were found between specific IgE and IgG1 or IgG4 (p<0.001, p=0.019). ELISA inhibition tests showed significant inhibitions by both free cefaclor and cefaclor-HSA conjugate. For basophil activation tests in patients having no specific IgE antibody, the CD63 expression level on basophils increased with incubations of free cefaclor.

CONCLUSION

The most common manifestation of immediate hypersensitivity to cefaclor was anaphylaxis, most of which was mediated by IgE; however, a non-IgE mediated direct basophil activation mechanism was suggested in a subset of anaphylaxis patients.

Shock

Critically ill patients with undifferentiated shock are complex and challenging cases in the ED. A systematic approach to assessment and management is essential to prevent unnecessary morbidity and mortality. The simplified, systematic approach described in this article focuses on determining the presence of problems with cardiac function (the pump), intravascular volume (the tank), or systemic vascular resistance (the pipes). With this approach, the emergency physician can detect life-threatening conditions and implement time-sensitive therapy.

Omalizumab, an anti-immunoglobulin E antibody: state of the art

A large number of trials show that the anti-immunoglobulin (Ig) E antibody omalizumab is very effective in patients with severe allergic asthma. This is acknowledged in consensus documents. The drug also has a good safety profile and a pharmacoeconomic advantage due to a reduction in the number of hospitalizations for asthma attacks. In recent years, some studies have shown that omalizumab is effective also in nonallergic asthma. Effects on the complex signaling mechanisms leading to activation of effector cells and to mediator release may account for this outcome. Indeed, omalizumab has been reported to be effective in a number of IgE-mediated and non-IgE-mediated disorders. Concerning the former, clinical efficacy has been observed in rhinitis, allergic bronchopulmonary aspergillosis, latex allergy, atopic dermatitis, allergic urticaria, and anaphylaxis. In addition, omalizumab has been demonstrated to be able to prevent systemic reactions to allergen immunotherapy, thus enabling completion of treatment in patients who otherwise would have to stop it. Concerning non-IgE-mediated disorders, omalizumab has been reported to be effective in nasal polyposis, autoimmune urticaria, chronic idiopathic urticaria, physical urticaria, idiopathic angioedema, and mastocytosis. Current indications for treatment with omalizumab are confined to severe allergic asthma. Consequently, any other prescription can only be off-label. However, it is reasonable to expect that the use of omalizumab will be approved for particularly important indications, such as anaphylaxis, in the near future.

S1P control of endothelial integrity

Sphingosine 1-phosphate (S1P), a lipid mediator produced by sphingolipid metabolism, promotes endothelial cell spreading, vascular maturation/stabilization, and barrier function. S1P is present at high concentrations in the circulatory system, whereas in tissues its levels are low. This so-called vascular S1P gradient is essential for S1P to regulate much physiological and pathophysiological progress such as the modulation of vascular permeability. Cellular sources of S1P in blood has only recently begun to be identified. In this review, we summarize the current understanding of S1P in regulating vascular integrity. In particular, we discuss the recent discovery of the endothelium-protective functions of HDL-bound S1P which is chaperoned by apolipoprotein M.