Plasma Histamine Levels Research Articles

The preoperative plasma histamine level as a possible protective biomarker for postoperative acute kidney injury

Acute kidney injury (AKI) is a life-threatening complication of acute type A aortic dissection (ATAAD) patients. Increasing evidence suggests that histamine ameliorates the pathology of renal injury. However, data on the association between histamine levels and postoperative AKI in ATAAD patients are limited. The purpose of our study was to explore the incidence and independent risk factors of postoperative AKI, with special emphasis on the relationship between preoperative plasma histamine levels and the severity of postoperative ATAAD-AKI. This retrospective single-center study evaluated 160 patients with ATAAD admitted to the Beijing Anzhen Hospital aortic surgery database between April 2020 and December 2021. Univariate and multivariate logistic regression analyses were performed to determine the potential risk factors for postoperative ATAAD-AKI. A subgroup analysis was performed to investigate the association between preoperative plasma histamine levels and the severity of postoperative ATAAD-AKI or continuous renal replacement therapy (CRRT). ATAAD-AKI occurred in 84 of 160 patients (52.5%), including 32 with stage 1 (38.1%), 14 with stage 2 (16.7%), 38 with stage 3 (45.2%), and 34 (21.3%) received postoperative CRRT. The in-hospital mortality rate was 19.0% (16/84) in the AKI group and 2.6% (2/76) in the non-AKI group (P = .02). Preoperative lower plasma histamine levels (odds ratio [OR], 1.31; 95% confidence interval [CI], 1.10-1.52; P = .004) were an important factor related to postoperative ATAAD-AKI in multivariate logistic regression analysis. Subgroup analysis revealed that low preoperative plasma histamine level was independently associated with postoperative ATAAD-AKI (stage 3) (OR, 1.38; 95% CI, 1.10-1.73; P = .005) and CRRT (OR, 1.44; 95% CI, 1.13-1.79; P = .008). Low preoperative plasma histamine level was an independent prognostic indicator of postoperative AKI in patients with ATAAD, especially for postoperative AKI (stage 3) and CRRT. Preoperative plasma histamine levels may serve as potential protective biomarkers of postoperative ATAAD-AKI.

Stress response as a contributing factor in horses with laminitis.

Laminitis is a complex and debilitating disease of horses. Numerous predisposing factors contribute to laminitis development, however the exact pathogenesis remains undetermined. Serum T4, cortisol, and histamine are components of the innate stress response and could play a causative or contributory role. Stress hormone concentrations in laminitis are largely unknown. To evaluate parameters associated with stress response in horses with laminitis, and compare these to healthy horses and horses with gastrointestinal (GI) disease. Thirty-eight adult horses presenting for non-medical conditions, GI abnormalities, or clinical laminitis were prospectively enrolled. Horses were assigned to the appropriate disease group (healthy, GI disease, and laminitis) and had blood drawn on presentation to the hospital. Samples were analyzed for plasma endogenous adrenocorticotrophic hormone (eACTH), serum cortisol, serum thyroid hormone, and plasma histamine. Stress hormone concentrations were significantly different between horses in the laminitis and GI disease groups. Plasma histamine levels were highest in horses with laminitis, compared with GI disease and controls. Both horses with laminitis and GI disease had increased plasma eACTH when compared to healthy horses. Horses with GI disease had higher serum cortisol concentrations than horses with laminitis or controls. Serum T4 was lower in horses with GI disease than in horses with laminitis and controls. Horses with laminitis had relative increases in both plasma histamine and eACTH concentrations. Serum T4 and cortisol concentrations of horses with laminitis did not differ significantly when compared to healthy horses. The role of stress hormones in equine disease warrants further investigation.

Oral administration of Lactobacillus plantarum JC7 alleviates OVA-induced murine food allergy through immunoregulation and restoring disordered intestinal microbiota.

PurposeThe incidence and prevalence of food allergy have sharply risen over the past several decades. Oral administration of probiotic stains has been proven as a safe and effective method to control food allergy. In this study, it aims to comprehensively investigate the anti-allergic effect of Lactobacillus plantarum JC7.MethodsBalb/c mice were randomly divided into three groups and received OVA (20 µg/mouse, intraperitoneal injection), L. plantarum JC7 (2 × 108 CFU/mouse, intragastric administration) + OVA (20 µg/mouse, intraperitoneal injection) or 0.9% saline (intragastric administration) for 3 weeks. Body weight was monitored weekly, and allergic reactions were evaluated after challenge of OVA. Serum levels of OVA-specific immunoglobulins and various cytokines were tested using ELISA, and the cecum microbiota was analysed by 16S rRNA sequencing to explore the relationships between these indicators and OVA-induced food allergy. Western blotting was used to identify the expression levels of phosphorylated IκBα and nuclear factor kappa B p65.ResultsOVA-sensitised mice showed mitigation of respiratory manifestations, alleviation of lung inflammation and congestion, and the presence of an intact intestinal villus structure. Furthermore, OVA-specific immunoglobulin E (IgE), OVA-specific-IgG1, and plasma histamine levels were declined in mice treated with L. plantarum JC7 than in OVA-sensitised mice. In addition, interferon-γ (IFN-γ) and interleukin 10 (IL-10) levels were significantly increased, while IL-4 and IL-17A levels were clearly decreased in mice that had undergone oral administration of L. plantarum JC7, compared with OVA-sensitised mice. These findings indicated imbalances of T helper cell type 1 (Th1)/Th2 and regulatory T cells (Treg)/Th17, which were confirmed by quantitative polymerase chain reaction (PCR). Western blotting demonstrated that the expression levels of phosphorylated IκBα and nuclear factor kappa B p65 were significantly increased in OVA-sensitised mice, but these changes were partly reversed after treatment with L. plantarum JC7. Oral administration of L. plantarum JC7 increased the richness, diversity, and evenness of cecum microbiota, characterised by higher Bacteroidetes abundance and lower Firmicutes abundance. Additionally, the intestinal microbial community composition was significantly altered in the OVA-sensitised group, indicating a disordered intestinal microbiota that was restored by the oral administration of L. plantarum JC7.ConclusionOverall, L. plantarum JC7 can prevent food allergy by rectifying Th1/Th2 and Treg/Th17 imbalances, combined with modifications of disordered intestinal microbiota.

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 SummaryAllergic 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.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.

Role of Mast Cells in HIV-associated Chronic Widespread Pain

Chronic widespread pain (CWP) in people with HIV-1 (PWH) is associated with a high rate of disability and low quality of life, with prevalence estimates ranging from 25%-85%. However, the specific mechanisms that contribute to CWP in HIV are not understood. Previously we demonstrated that PWH with CWP have increased hemolysis, elevated plasma levels of cell-free heme, and attenuated levels of the heme degrading enzyme, heme oxygenase 1 (HO-1). We also found that high cell-free heme and low HO-1 were associated with hypersensitivity in animals. In this study, we hypothesized that high heme and low HO-1 activates mast cells leading to degranulation and release of pain mediators like, histamine and bradykinin in HIV. PWH who self-report CWP were recruited from the University of Alabama at Birmingham HIV clinic. Animal models used in the study included, C57BL/6 mice subjected to hemolysis by intraperitoneal injection of phenylhydrazine hydrochloride (PHZ), HO-1 knockout mice, and HIV-1 transgenic rats overexpressing HIV-1 proteins. Cellular studies were performed in MC/9 mast cells. Human findings show that PWH with CWP have elevated plasma levels of histamine and bradykinin. HIV-1 transgenic rats also have elevated plasma levels of histamine and bradykinin and are hypersensitive as estimated by a decrease in withdrawal threshold to von Frey stimulation. In addition, data in mice with elevated plasma levels of free-heme, or decreased expression of HO-1, show significantly elevated levels of the pain mediators, histamine and bradykinin. Cellular data shows that high heme or low HO-1 induces mast cell degranulation and the release of histamine and bradykinin. Together, these data suggest that heme-dependent mast cell degranulation and the release of pain mediators may be contributing CWP in HIV. Future studies will focus on determining strategies to stabilize mast cell membrane in HIV and reduce hypersensitivity. Grant Number: RO1DA049657 Grant Name: Chronic Widespread Pain in HIV: Novel Mechanisms and Therapeutics.

Diamine oxidase knockout mice are not hypersensitive to orally or subcutaneously administered histamine

ObjectiveTo evaluate the contribution of endogenous diamine oxidase (DAO) in the inactivation of exogenous histamine, to find a mouse strain with increased histamine sensitivity and to test the efficacy of rhDAO in a histamine challenge model.MethodsDiamine oxidase knockout (KO) mice were challenged with orally and subcutaneously administered histamine in combination with the β-adrenergic blocker propranolol, with the two histamine-N-methyltransferase (HNMT) inhibitors metoprine and tacrine, with folic acid to mimic acute kidney injury and treated with recombinant human DAO. Core body temperature was measured using a subcutaneously implanted microchip and histamine plasma levels were quantified using a homogeneous time resolved fluorescence assay.ResultsCore body temperature and plasma histamine levels were not significantly different between wild type (WT) and DAO KO mice after oral and subcutaneous histamine challenge with and without acute kidney injury or administration of HNMT inhibitors. Treatment with recombinant human DAO reduced the mean area under the curve (AUC) for core body temperature loss by 63% (p = 0.002) and the clinical score by 88% (p < 0.001). The AUC of the histamine concentration was reduced by 81%.ConclusionsInactivation of exogenous histamine is not driven by enzymatic degradation and kidney filtration. Treatment with recombinant human DAO strongly reduced histamine-induced core body temperature loss, histamine concentrations and prevented the development of severe clinical symptoms.

The allergy mediator histamine confers resistance to immunotherapy in cancer patients via activation of the macrophage histamine receptor H1.

Reinvigoration of antitumor immunity remains an unmet challenge. Our retrospective analyses revealed that cancer patients who took antihistamines during immunotherapy treatment had significantly improved survival. We uncovered that histamine and histamine receptor H1 (HRH1) are frequently increased in the tumor microenvironment and induce Tcell dysfunction. Mechanistically, HRH1-activated macrophages polarize toward an M2-like immunosuppressive phenotype with increased expression of the immune checkpoint VISTA, rendering Tcells dysfunctional. HRH1 knockout or antihistamine treatment reverted macrophage immunosuppression, revitalized Tcell cytotoxic function, and restored immunotherapy response. Allergy, via the histamine-HRH1 axis, facilitated tumor growth and induced immunotherapy resistance in mice and humans. Importantly, cancer patients with low plasma histamine levels had a more than tripled objective response rate to anti-PD-1 treatment compared with patients with high plasma histamine. Altogether, pre-existing allergy or high histamine levels in cancer patients can dampen immunotherapy responses and warrant prospectively exploring antihistamines as adjuvant agents for combinatorial immunotherapy.

Iodixanol activation of mast cells: Implications in the pathogenesis of iodixanol-induced delayed cutaneous adverse reactions

Iodinated contrast media (ICM) is widely used in radiological examination and interventional therapy. In the commonly used ICM, iodixanol is considered to be the safer one. However, compared with other ICMs, it has a higher incidence of delayed cutaneous adverse reactions. The underlying mechanisms are unclear. In this study, mice with positive allergic reactions were selected based on the mouse clinical allergy symptom score and skin and blood samples taken 1, 6, 24, 48, and 72 h after ICMs (6 g iodine/kg) injection for histological and blood analyses. ICMs-induced pseudo-allergic reactions were investigated through in vivo intravital vascular imaging and passive cutaneous anaphylaxis (PCA) not mediated by IgE and through, calcium imaging degranulation of mast cells (MCs), and western blot assays in vitro. Results shows iodixanol-induced systemic anaphylaxis caused severe extravasation of plasma proteins and degranulation of skin MCs, and increased levels of plasma histamine, cytokines and inflammatory chemokines. Mechanistically, iodixanol increases degranulation of MCs and promotes the synthesis of inflammatory factors by activating PLC-γ and PI3K-related pathways. Trigonelline inhibit iodixanol-induced MC-related pseudo-allergic reactions in vitro and in vivo. These results suggest that mice in the iodixanol group had a higher incidence of delayed cutaneous reactions, characterized by cytokine release over time and delayed cutaneous MC degranulation. Iodixanol’s delayed cutaneous adverse reactions may be due to a delayed phase of MC-related pseudo-allergic reactions. Trigonelline revealed anti-allergic activity in iodixanol-induced MC-related pseudo-allergic reactions.

Study on alleviation effect of stachyose on food allergy through TLR2/NF-κB signal pathway in a mouse model

AimsTo explore the effect on food allergy of stachyose. Main methodsThe egg allergen ovalbumin (OVA) was used to induce a food allergy model of BALB/c mice, and different doses of stachyose were given in process. Using enzyme-linked immunosorbent assay (ELISA) methods to detect the levels of IgE, IgG1, histamine and cytokines. And flow cytometry was used to analyze TH1/TH2 balance further. Besides, Hematoxylin-eosin (HE) staining was used to observe changes of intestinal morphology. Lastly, Reverse Transcription-Polymerase Chain Reaction (RT-qPCR) and western Blot was conducted to explore the possible mechanism. Key findingsCompared with OVA group, serum IgE and IgG1 levels in the low-dose (1mg/mouse) group and high-dose (5mg/mouse) group of stachyose were significantly reduced (P < 0.05); the level of plasma histamine was also decreased significantly (P < 0.05) and the body temperature were decreased. In all, allergic symptoms were alleviated after stachyose treatment. Furthermore, TH1/TH2 balance was improved after stachyose treatment. Lastly, the expression of TLR2 and NF-κB were increased significantly (P < 0.05) in both mRNA and protein levels after stachyose treatment. SignificanceFood allergy was alleviated through improving TH1/TH2 balance by activating TLR2/NF-κB signal by stachyose.

Experimental postoperative ileus: is Th2 immune response involved?

Rationale: Postoperative ileus (POI) is a frequent complication arising after gastrointestinal surgery but pathogenesis of POI is still not fully understood. While Th1 immune cells are implicated in POI, the involvement of Th2 cells has not yet been clarified. Given the impact of reactive oxygen species (ROS) in the regulation of Th1 and Th2 balance, we hypothesized that not only Th1 but also Th2 immune response can be involved in the development of experimental POI.Methods: The intestinal transit test was performed using carbon gum arabic. Electron microscopy was employed to assess tissue morphology and the presence of immune cells. Cytokines, IgE and ROS were measured. Immune cells from Peyer's patches were analyzed by Flow Cytometry and toluidine blue staining was used for detection of mast cells. Transcriptional factors were analyzed by Western blot.Results: POI is associated with an increase in both Th2 cytokines and Th2 cells. We have further demonstrated that POI induces a Th2-dependent activation of memory and non-memory B cells. This was accompanied by an increase in a number of mast cells in the colon of POI mice as well by an increased IgE and histamine plasma levels. We found that POI-induced accumulation of ROS was associated with an increased expression of the transcriptional factors HMBGI, NF-κB, and p38. This increased expression seemed to be associated with a Th2 response.Conclusion: Th2 immune response can be involved in the activation of mast cells in POI, which was associated with ROS mediated activation of NF-κB and p38 MAPK signaling pathway.

Assessment of allergenicity of oryza sativa recombinant human serum albumin in BALB/c mice

To investigate the potential allergenicity of oryza sativa recombinant human serum albumin(OsrHSA)in BALB/c mice. Eighty BALB/c mice were randomly divided into four groups i. e ovalbumin(OVA) positive control group, potato acid phosphatase(PAP) negative control group, Oryza sativa recombinant HAS(OsrHSA) group and solvent control group(phosphate buffer saline, PBS), respectively. Mice were administered by intraperitoneal injections of tested proteins and histamine levels in plasma and sIgE, sIgG, sIgG1, sIgG2 a, and tIgE antibody levels in serum were measured. Compared with the other groups, serum tIgE, sIgE, sIgG, sIgG1 and plasma histamine levels in the OVA group were significantly increased, while serum sIgG2 a levels were decreased(P&lt;0. 05). There was no significant difference in serum sIgE level and histamine level between the OsrHSA group and the control group(P&gt;0. 05). Serum sIgG, sIgG1 and sIgG2 a levels were lower than those in the PAP group(P&lt;0. 05). There was no significant difference in serum tIgE content between PAP group and OsrHSA group(P&gt;0. 05). The potential allergenicity of OsrHSA through traperitioneal injection in BALB/c mice was very low.

Changes in Allergenicity of Ovalbumin in Vitro and in Vivo on Conjugation with Quercetin

A previous study demonstrated decreased allergenicity in vitro of some food allergens after conjugation with polyphenols. However, little is known about how polyphenol conjugation with food allergens affects in vivo allergenicity. We conjugated a well-known food allergen, ovalbumin (OVA), with quercetin (QUE) to assess the potential allergenicity of OVA in vitro and in vivo in a BALB/c mouse model. QUE could covalently conjugate with OVA and changed the protein structure, which might destroy and/or mask OVA epitopes. Conjugation with QUE decreased IgE binding properties and the release capacity of the conjugated OVA. In vivo, as compared with native protein, conjugation with QUE decreased the levels of IgE, IgG1, IgG, plasma histamine, and mast cell protease-1 (mMCP-1) on the surface of sensitized mast cells, along with decreased FcεRI+ and c-kit+ expression. The levels of Th2-related cytokines (IL-4, IL-5, IL-13) decreased and that of a Th1-related cytokine (IFN-γ) increased slightly, which suggests that conjugation with QUE modulated the imbalance of the Th1/Th2 immune response. Conjugation of OVA with QUE could reduce OVA allergenicity in vitro and in vivo, which could provide information for reducing food allergenicity by conjugation with polyphenols.

Correlation study between the pharmacokinetics of seven main active ingredients of Mahuang decoction and its pharmacodynamics in asthmatic rats

The aim of this study was to investigate the pharmacokinetics and pharmacodynamics of seven main active components of Mahuang decoction (MHD) and its time-concentration-effect relationship. The asthmatic rat model was established by the method of ovalbumin (OVA) sensttization. The plasma concentrations of ephedrine, pseudoephedrine, methylephedrine, amygdalin, liquiritin, cinnamic acid, glycyrrhizic acid in asthmatic model rat were investigated by a selective and rapid HPLC/MS-MS method. Simultaneously, the asthma-involved cytokines including leukotrienes B4 (LTB4), thromboxane B2 (TXB2), 6-Keto-Prostaglandin F1α (6-K-PGF1α) and histamine (HIS) levels in rat plasma were determined by using ELISA. A mathematics method was applied to assess the trend of percentage rate of change among different time intervals of the seven components. The sigmoid E max function was used to establish the PK-PD modeling of MHD. The results indicated that MHD could control or ameliorate asthma. There was a hysteresis between the peaked drug concentration and maximum therapeutic effect of MHD. The PK-PD curves of MHD showed clockwise or counter-clockwise hysteresis loop. In addition, amygdalin might exert a more significant influence on regulating cytokines levels in asthmatic rats among the seven components of MHD.

Plasma Histamine Level as a Distinguishing Factor between Stable Coronary Artery Disease and Acute Coronary Syndrome

Background: Angina can be caused by atherosclerosis in Coronary Artery Disease (CAD) patients either in Stable Coronary Artery Disease (SCAD) or Acute Coronary Syndrome (ACS). Histamine as a mast cell-preformed mediator is suspected to play a role in atherosclerosis. However, its mechanism is yet to be established and there is a lack of these data in the CAD population. To confirm the distinctness of plasma histamine level in patients with Acute Coronary Syndrome and Stable Coronary Artery Disease Patients, this research was an observational analytic study with transversal design in 49 CAD patients by purposive sampling which consists of 25 ACS patients (72% men, mean age 55,6±9,66 years) and 24 SCAD patients (83,3% men, mean age 52,71±8,03 years). The level of plasma histamine was measured using a Histamine ELISA-Kit. Median values of plasma histamine level in ACS group and SCAD group were 30,79 ng/ml (5,85-36,09 ng/ml) and 26,42 ng/ml (0,30-41,39 ng/ml). Comparison analysis on the median value of plasma histamine level between two groups was done with Mann-Whitney U Test and showed a statistical difference between two groups (p=0,011). There are significant differences in plasma histamine level between Acute Coronary Syndrome and Stable Coronary Artery Disease Patients.

Allergenicity reduction and rheology property of Lactobacillus-fermented soymilk.

This study aimed to investigate the reduction in the potential allergenicity of soymilk, and its rheological properties, after fermentation with Lactobacillus. Soymilk (SM) was fermented with Lactobacillus brevis and Lactobacillus sp. The molecular weight of fermented soymilk (FSM) was characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and the potential allergenicity of FSM was analyzed using enzyme-linked immunosorbent assay in vitro and the BALB/c mouse model to detect changes in histamine, mouse mast cell protease-1 (mMCP-1), allergen-specific IgG/IgE, and cytokine levels and histomorphology of jejunum in vivo. The SDS-PAGE and enzyme linked immunosorbent assay (ELISA) showed that allergens of soybean (β-conglycinin and acidic subunit of glycinin) were almost degraded, and their immunoreactivity was decreased. In the BALB/c mouse model, the FSM group did not show anaphylactic shock symptoms compared with the SM group. Moreover, a tendency toward decreased serum allergen-specific IgG/IgE levels, plasma histamine levels, and mMCP-1 concentrations was observed in the FSM group. Furthermore, Th2-related cytokines were decreased, while IFN-γ production increased in spleen cell cultures. The intestinal villus was slightly damaged after the challenge. All these findings indicated that the Th1/Th2 balance in the FSM group shifted toward a Th1 response, ultimately reducing the potential allergenicity of FSM. Rheological assessment suggested that FSM has good viscous and pseudoplastic properties. Fermentation might be a promising method for producing tasty, hypoallergenic soybean products. © 2019 Society of Chemical Industry.

Oral administration of recombinant Bacillus subtilis spores expressing Helicobacter pylori neutrophil-activating protein suppresses peanut allergy via up-regulation of Tregs.

Helicobacter pylori neutrophil-activating protein (NAP) is an immune modulator with anti-Th2 inflammation activity that can be used to prevent IgE-mediated allergic reactions. Cholera toxin B (CTB) is a mucosal adjuvant that can induce antigen tolerance. Bacillus subtilis spores are an ideal vehicle for the oral delivery of heterologous antigens. We investigated the therapeutic effect of recombinant NAP Bsubtilis spores on peanut allergies in a mouse model. Female C3H/HeJ mice were sensitized and challenged with peanut extract by oral administration. Before challenge, recombinant NAP and CTB-NAP (CNAP) spores were orally administered to sensitized mice for 4weeks. Faecal peanut-specific IgA and serum-specific IgE, IgG1, and IgG2a levels were measured, and the intestinal microbiota was analysed. Mice were intraperitoneally injected with anti-CD25 antibodies for regulatory T cell (Treg) depletion to evaluate the efficacy of Tregs in preventing peanut allergy. After challenge, anaphylactic reactions, plasma histamine, Tregs, and splenocyte interleukin (IL)-10, IL-4, IL-5 and interferon-γ (IFN-γ) levels were evaluated. After 4weeks of recombinant spore treatment, faecal IgA levels and serum IgG2a levels were increased, while serum IgG1 and IgE levels were reduced. Intestinal microbiota analysis revealed that CNAP spores increased the taxonomic abundance of Firmicutes at the phylum level and Clostridia at the class level. After challenge, the administration of NAP or CNAP spores to mice was found to ameliorate anaphylactic reactions and decrease plasma histamine levels. Administration of NAP or CNAP spores also enhanced IL-10 and IFN-γ secretion, and suppressed IL-4 and IL-5 secretion. The protective effect of CNAP spores was more pronounced than that of NAP spores; this therapeutic effect was lost after Treg depletion. Recombinant NAP spores successfully suppressed Th2 inflammation via the up-regulation of Tregs; this may serve as a novel therapeutic approach for treating food allergies.

Study on safflower yellow for injection based on cell degranulation and acute anaphylactoid model

This paper was aimed to establish screening methods of anaphylactoid reaction caused by safflower yellow for injection based on RBL-2 H3 cell degranulation model and mice model for acute anaphylactoid reaction,and evaluate the hypersensitivity caused by safflower yellow for injection from different batches. An in vitro cell model was used to keep the cells stimulated for an hour with different batches of safflower yellow for injection as the drug group,serum-free MEM medium as negative control group and 30 mg·L-1 C48/80 as positive control group respectively. The supernatant was then absorbed,and neutral red staining technique was used to detect the effect of safflower yellow injection on the degranulation of RBL-2 H3 cells with the positive cell rate of degranulation as the indicator.An in vivo model was established to validate the experimental results,and mice model for acute anaphylactoid reaction and ELISA method were adopted to detect the plasma histamine content,and screen the hypersensitivity caused by safflower yellow for injection at the animal level by using plasma histamine content as a test index. The results of the neutral red staining experiments showed that the positive control C48/80 could cause cell degranulation,and most of the cells were deeply stained. There was significant difference in positive cell rate between different batches of safflower yellow and positive control group. In the mice model for acute anaphylactoid reaction,it was found that the positive control C48/80 significantly increased the histamine content in the plasma of mice,while the safflower yellow in each batch did not cause a significant increase in plasma histamine( P<0. 000 1). The mechanism of anaphylactoid reaction is relatively complicated. This study was mainly based on the release of histamine and other active substances by degranulation of mast cells. No significant degranulation reaction of RBL-2 H3 cells induced by safflower yellow for injection was detected,nor was the plasma histamine level significantly increased in mice from the in vitro and in vivo aspects.

Plasma histamine elevation in a large cohort of sickle cell disease patients.

The role of mast cells has been questioned in sickle cell disease (SCD). We performed a prospective study evaluating plasma histamine and tryptase levels in a cohort of paediatric and adult patients, in steady state (n=132) and during vaso-occlusive crisis (VOC) (n=121). Histamine level was elevated in 18% of patients in steady state and in 61% during VOC. Median histamine level was significantly higher during VOC than in steady state (24·1 [7·0-45·0] vs 9·6 [6·2-14·4]nmol/l, P<0·0001). Tryptase level was slightly increased during VOC without reaching pathological values. These results suggest a role of mast cell activation in SCD pathophysiology.

Inhibiting Histamine Signaling Ameliorates Vertigo Induced by Sleep Deprivation.

Although histamine inhibitors have been used in the motility-associated vertigo, the link between histamine and sleep deprivation (SD)-induced vertigo has not been clearly demonstrated. The histamine plasma levels were assayed in the SD volunteers before SD and 24h after SD. Pinnacle's automated sleep deprivation system was used to establish the female C57BL/6 mice SD model. Histidine decarboxylase inhibitor 4-bromo-3-hydroxybenzoic acid (BHOA), and antihistamine diphenhydramine (DPHM) were injected intraperitoneally to test their effects on SD-induced vertigo. Rotarod tests and vestibular scores 24 and 48h post SD were utilized to assay the vestibular function. Western blot was used to determine the expression of histidine decarboxylase (HDC) in the vestibular, and PowerChrom was utilized to quantify the concentrations of cerebrospinal fluid (CSF) histamine. SD increased plasma concentration of histamine in humans. Upregulated HDC in the vestibular and increased CSF concentration of histamine can be detected in the SD mice, indicating vestibular dysfunction which can be ameliorated by both BHOA and DPHM. Histamine signaling inhibition may ameliorate SD-induced vertigo, and histamine can be considered as a potential treatment target.

Mast Cells Contribute to Brain Microvascular Permeability in Sickle Cell Disease

Mast cells are in close proximity to the vasculature and cause endothelial activation, plasma extravasation, and vascular dysfunction (Gupta & Harvima, Immunol Rev 2018). Vascular dysfunction in sickle cell disease (SCD) is accompanied by increased expression of P-selectin. Treatment with Crizanlizumab, an antibody against P-selectin, led to significantly less sickle cell-related pain crises (Ataga et al., NEJM 2017) highlighting the role of endothelial P-selectin in vasoocclusive crises (VOC). Earlier studies demonstrated that mast cell activation with morphine or ischemia/reperfusion stimulates endothelial E- and/or P-selectin expression. However, it is unknown how mast cells stimulate endothelial selectin expression in SCD. Endothelial dysfunction contributes significantly to the pathobiology of SCD including VOC and may play a critical role in increased blood-brain barrier (BBB) permeability, which may contribute to stroke, another major comorbidity of SCD. One of the known triggers of endothelial dysfunction, inflammation and oxidative stress is endoplasmic reticulum (ER) stress. We hypothesize that in a sickle microenvironment, mediators derived from activated mast cells stimulate endothelial P-selectin expression via ER stress leading to increased BBB permeability. We examined the ability of mast cells to stimulate P-selectin expression and BBB permeability via ER stress in a sickle microenvironment.We isolated MCs from HbAA-BERK and HbSS-BERK, control and sickle mice, respectively; incubated them in vitro and collected mast cell conditioned media (MCCM) from HbAA MCs and HbSS MCs. Normal mouse brain microvascular endothelial cells (mBMECs) were treated with unconditioned MCCM, HbAA MCCM, or HbSS MCCM to examine the effect of mast cell activation on endothelium. We observed increased mast cell activity in HbSS mice evinced by significantlyhigher plasma and skin histamine levels, compared to HbAA mice (p< 0.02 for both). Mast cells from HbSS mouse skin showed significantly increased expression of histamine compared to HbAA skin mast cells (p< 0.04). mBMECs incubated with HbAA and HBSS MCCM exhibited about 3- and 6-fold fold increases in P-selectin expression, compared to unconditioned culture medium, respectively (p< 0.0001 for both). Therefore, mast cells in culture release substances that stimulate P-selectin expression which is further increased by mast cells from sickle (HbSS) microenvironment. Preincubation of mBMEC with 5 microM salubrinal, an inhibitor of dephosphorylation of elongation initiation factor-a, which reduces ER stress, significantly inhibited HbSS MCCM-induced P-selectin expression on mBMEC (p< 0.0001) to the level induced by HbAA-MCCM. In contrast, salubrinal did not inhibit HbAA-MCCM-induced P-selectin expression on mBMEC, suggesting that in a sickle microenvironment mast cells contribute to P-selectin expression via ER stress.We next examined mast cell activity on endothelial permeability in vitro on mBMEC monolayers and in vivo in the brain of HbSS mice. mBMECs incubated with HbSS MCCM showed a significant increase in Evans blue leakage compared to unconditioned or HbAA MCCM (p<0.0001 for both), which was inhibited by preincubation of mBMEC with 5 microM salubrinal prior to incubation with HbSS MCCM (p< 0.0001). In vivo female HbSS mice showed a significantly increased leakage in the brain of FITC-dextran injected through tail vein compared to HbAA mice (p< 0.01). HbSS mice treated with 1 mg/kg salubrinal demonstrated inhibition of FITC-dextran leakage in the brain compared to vehicle (p< 0.05). Thus, ER stress contributes to increased BBB permeability in HbSS mice. We observed activated degranulating mast cells in the brain parenchyma of HbSS mice. In HbAA mice, quiescent mast cells were confined to the meninges of the brain but not seen in the parenchyma. Together, these data suggest that mast cell activation contributes to BBB permeability in a sickle microenvironment via ER stress-mediated P-selectin expression. In turn, this mast cell-initiated activity in the brain may underlie the pathobiology of stroke in SCD. Inhibitors of mast cells and P-selectin have been tested clinically leading to reduced VOC in SCD without known adverse events. Therefore, mast cell activation-induced P-selectin via ER stress may serve as a treatable target for reducing the risk of stroke in SCD. DisclosuresGupta:Novartis: Honoraria; Tau tona: Consultancy.