Effect of misoprostol on the secretion of histamine from basophils of whole blood

Fatty-Acid-Based Membrane Lipidome Profile of Peanut Allergy Patients: An Exploratory Study of a Lifelong Health Condition

Peanut allergy is a lifelong, increasingly prevalent, and potentially life-threatening disease burdening families and communities. Dietary, particularly polyunsaturated fatty acids (PUFAs), intakes can exert positive effects on immune and inflammatory responses, and the red blood cell (RBC) membrane lipidome contains stabilized metabolic and nutritional information connected with such responses. The fatty-acid-based membrane lipidome profile has been exploratorily evaluated in a small cohort of patients (eight males and one female, age range 4.1−21.7 years old, body mass index BMI < 25) with angioedema and/or anaphylaxis after peanut ingestion. This analysis was performed according to an ISO 17025 certified robotic protocol, isolating mature RBCs, extracting membrane lipids, and transforming them to fatty acid methyl esters for gas chromatography recognition and quantification. Comparison with a group of age- and BMI-matched healthy individuals and with benchmark interval values of a healthy population evidenced significant differences, such as higher levels of ω-6 (arachidonic acid), lower values of ω-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), together with an increased ω-6/ω-3 ratio in allergic patients. A significant inverse correlation was also found between specific immunoglobulin E (IgE) levels and ω-6 di-homo-gamma-linolenic acid (DGLA) and total PUFAs. Results of this preliminary study encourage screenings in larger cohorts, also in view of precision nutrition and nutraceuticals strategies, and stimulate interest to expand basic and applied research for unveiling molecular mechanisms that are still missing and individuating treatments in chronic allergic disorders.

Immune-Mediated Mechanisms in Cofactor-Dependent Food Allergy and Anaphylaxis: Effect of Cofactors in Basophils and Mast Cells

Cofactors may explain why in some cases food ingestion leads to anaphylaxis while in others elicits a milder reaction or tolerance. With cofactors, reactions become more severe and/or have a lower allergen threshold. Cofactors are present in up to 58% of food anaphylaxis (FAn). Exercise, NSAIDs, and alcohol are the most frequently described, although the underlying mechanisms are poorly known. Several hypotheses have suggested the influence of these cofactors on basophils and mast cells (MCs). Exercise has been suggested to enhance MC activation by increasing plasma osmolarity, redistributing blood flow, and activating adenosine and eicosanoid metabolism. NSAIDs’ cofactor effect has been related with cyclooxygenase inhibition and therefore, prostaglandin E₂ (PGE₂) production. Indeed, overexpression of adenosine receptor 3 (A₃) gene has been described in NSAID-dependent FAn; A₃ activation potentiates FcϵRI-induced MC degranulation. Finally, alcohol has been related with an increase of histamine levels by inhibition of diamino oxidase (DAO) and also with and increase of extracellular adenosine by inhibition of its uptake. However, most of these mechanisms have limited evidence, and further studies are urgently needed. In conclusion, the study of the immune-related mechanisms involved in food allergic reactions enhanced by cofactors is of the utmost interest. This knowledge will help to design both tailored treatments and prophylactic strategies that, nowadays, are non-existent.

Effect of Prostaglandin E1 Analog Misoprostol in An Ovalbumin-Induced Allergic Rhinitis Model

Objective

The aim of the present study was to demonstrate the effects of misoprostol in ovalbumin-induced allergic rhinitis (AR). The second purpose was to compare the effect profile of the combination of an antihistamine with misoprostol during treatment of AR.

Materials and Methods

Twenty-five adult male rats were used and were randomly classified into five groups (n=5): healthy+saline, AR, AR and desloratadine (D)-treated group, AR and misoprostol (M)-treated group, and AR and combined-treated group.

Results

Desloratadine administration had significantly lower nasal symptoms than the AR group, but nasal symptoms in the AR+M group were better than those in the AR+D group. The best improvement in serum IgE levels was seen in the misoprostol alone and combination treatment groups.

Conclusion

We suggest that prostaglandins should be considered in the treatment of AR, and that the effects of these types of drugs should be tested clinically in patients.

Anaphylactic shock to vaginal misoprostol: a rare adverse reaction to a frequently used drug

Misoprostol is widely used in daily practice for induction of labor and cervical dilatation prior to intrauterine procedures, including dilatation and curettage or hysteroscopy. Anaphylactic shock to intravaginal misoprostol can occur not only in pregnant women, as reported in 2 previous cases, but also in a non-pregnant, perimenopausal woman, as in the case described herein. A 49-year-old woman received vaginal misoprostol for cervical ripening prior to hysteroscopic myomectomy and experienced anaphylactic shock. Two 400 μg doses of misoprostol 6 hours apart caused uncontrolled shaking and high fever followed by shock. In conclusion, the possibility of anaphylactic shock should be considered in patients with sudden hypotension following misoprostol administration. Prompt identification and management are crucial to prevent morbidity and mortality following an anaphylactic shock to misoprostol.

Alterations of mast cell mediator production and release by gamma-linolenic and docosahexaenoic acid

The purpose of our investigations was to evaluate the supposed beneficial effects of gamma-linolenic (GLA) and docosahexaenoic acid (DHA) in a canine mastocytoma cell line (C2) as a model for canine atopic dermatitis. Cells were cultured in a basic medium (DEH) and in DEH supplemented with 14.3 microM GLA (DEH-GLA) or 14.3 microM DHA (DEH-DHA) for 8 days. Chymase and tryptase activity, as well as histamine and prostaglandin (PG)E(2) release were measured. To stimulate histamine and PGE(2) release, cells were incubated with the wasp venom peptide mastoparan (50 microM) for 30 min. GLA increased tryptase activity and decreased histamine release after C2 stimulation. DHA diminished PGE(2) production in activated C2. These results support the prescription of GLA- and DHA-enriched diets to reduce inflammatory signs in canine atopic dermatitis.

Effects of Prostaglandin D2and 5-Lipoxygenase Products on the Expression of CD203c and CD11b by Basophils

Basophils are important in allergic diseases such as asthma because they produce a variety of inflammatory mediators. Activation of these cells with IgE and N-formyl-methionyl-leucyl-phenylalanine results in a variety of responses, including increased surface expression of CD203c and CD11b and release of histamine. Although considerable information is available on the effects of eicosanoids on neutrophils, eosinophils, and monocytes, less is known about their effects on basophils. In the present study, we examined the effects of various eicosanoids on the above basophil responses. Of the naturally occurring eicosanoids tested, prostaglandin D(2) (PGD(2); EC(50), 10 nM) was by far the most potent activator of CD203c expression, with other prostanoids having little effect. This response was mediated by the DP(2) receptor/chemoattractant receptor-homologous molecule expressed on Th2 cells because it was shared by the selective agonist 15R-methyl-PGD(2) (EC(50), 3 nM). The 5-lipoxygenase products leuko-triene B(4) and 5-oxo-6,8,11,14-eicosatetraenoic acid also stimulated CD203c expression but to a lesser extent than PGD(2), whereas leukotriene D(4) was inactive. Neither PGD(2) nor 5-oxo-6,8,11,14-eicosatetraenoic acid stimulated histamine release or CD63 expression on basophils. Both PGE(2) and the DP(1) receptor agonist BW245C [(4S)-(3-[(3R,S)-3-cyclohexyl-3-hydroxypropyl]-2,5-dioxo)-4-imidazolidineheptanoic acid] strongly inhibited DP(2) receptor-mediated CD203c expression. The DP(1) receptor antagonist BWA868C [3-[(2-cyclohexyl-2-hydroxyethyl)amino]-2,5-dioxo-1-(phenylmethyl)-4-imidazolidine-heptanoic acid] enhanced PGD(2)-induced CD203c expression, suggesting that interaction of PGD(2) with DP(1) receptors can limit activation of basophils by this prostaglandin. In conclusion, PGD(2) is the most potent inducer of basophil CD203c expression among eicosanoids and may be a key mediator in asthma and other allergic diseases. The balance between DP(1) and DP(2) receptors may be important in determining the magnitude of basophil responses to this prostaglandin.

A randomized controlled trial of misoprostol monotherapy for canine atopic dermatitis: effects on dermal cellularity and cutaneous tumour necrosis factor-alpha

In this blinded randomized placebo-controlled trial, 20 dogs with atopic dermatitis (AD) were given placebo (8 dogs) or misoprostol (12 dogs) at 5 micro g kg-1, orally, three times daily for 3 weeks. Administration of the active drug, but not of placebo, led to a significant decrease in lesional and pruritus scores. The median reduction from baseline of both scores was approximately 30%. Misoprostol therapy did not lead to decreases of dermal cell counts or skin tumour necrosis factor (TNF)alpha mRNA copy numbers that were significantly different from those of placebo. Skin TNFalpha protein production, assessed using indirect immunofluorescence, decreased or remained unchanged in dogs receiving misoprostol. In contrast, post treatment TNFalpha fluorescence scores were higher in all but two dogs given placebo. The changes from baseline of TNFalpha fluorescence scores did not correlate significantly with those of lesional or pruritus indices. These observations confirm the modest efficacy of misoprostol for treatment of canine AD and suggest that its mild anti-allergic effects are not associated with either inhibition of inflammatory cell emigration or TNFalpha production.