Laccase/caffeic acid-catalyzed crosslinking coupled with galactomannan alters the conformational structure of ovalbumin and alleviates Th2-mediated allergic asthma

Ovalbumin(OVA)is the major allergenic protein that can induce T helper 2(Th2)-allergic reactions,for which current treatment options are inadequate.In this study,we developed a polymerized hypoallergenic OVA product via laccase/caffeic acid(Lac/CA)-catalyzed crosslinking in conjunction with galactomannan(Man).The formation of high molecular weight crosslinked polymers and the Ig G-binding were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)and Western blotting.The study indicated that Lac/CA-catalyzed crosslinking plus Man conjugation substantially altered secondary and tertiary structures of OVA along with the variation in surface hydrophobicity.Gastrointestinal digestion stability assay indicated that crosslinked OVA exhibited less resistance in simulated gastric fluid(SGF)and simulated intestinal fluid(SIF).Mouse model study indicated that Lac-Man/OVA ameliorated eosinophilic airway inflammatory response and efficiently downregulated the expression of Th2-related cytokines(interleukin(IL)-4,IL-5,and IL-13),and upregulated IFN-γand IL-10 expression.Stimulation of bone marrow-derived dendritic cells with Lac-Man/OVA suppressed the expression of phenotypic maturation markers(CD80 and CD86)and MHC class II molecules,and suppressed the expression levels of proinflammatory cytokines.The knowledge obtained in the present study offers an effective way to acquire a hypoallergenic OVA product that can have a therapeutic effect in alleviating OVA-induced allergic asthma.

Investigation into IgG/IgE binding capacity and gut microbiota of digestion products derived from glycated ovalbumin

Gut microbiota plays an important role in food allergy.The immunoglobulin G(IgG)/immunoglobulin E(IgE)binding capacity and human gut microbiota changes of digestion products derived from glycated ovalbumin(OVA)were investigated.Gastrointestinal digestion effectively destroyed the primary structure of glycated OVA,resulting in a significantly higher digestibility than gastric digestion,and more abundant peptides<3 kDa.Moreover,gastric and gastrointestinal digestion products have different fluorescence quenching and red shift of fluorescence peaks,and possess different conformational structures.These changes resulted in a decrease in 28.7%of the IgE binding capacity of gastrointestinal digestion products beyond that of pepsin.Moreover,gastrointestinal digestion products of glycated OVA increased significantly the proportion of Subdoligranulum,Collinsella,and Bifidobacterium.Therefore,gastrointestinal digestion products of glycated OVA altered human intestinal microbiota,reducing the risk of potential allergy.

Rosmarinic acid improves tracheal smooth muscle responsiveness and lung pathological changes in ovalbumin-sensitized rats

Objective:To evaluate the effect of rosmarinic acid on tracheal smooth muscle responsiveness and lung pathological changes in ovalbumin-sensitized rats.Methods:Rats were randomly divided into six groups:the control group,the asthmatic group,and the asthmatic groups treated with dexamethasone(1 mg/kg;oral gavage)or three doses of rosmarinic acid(0.5,1,and 2 mg/kg;oral gavage).For induction of asthma,rats received intraperitoneal injections and inhalation of ovalbumin.After 21 days,bronchoalveolar lavage fluid and lung samples were collected for histopathological analyses.Moreover,total and differential white blood cell counts were determined.Results:The rosmarinic acid-treated group had significantly lower tracheal smooth muscle responses to methacholine than the asthmatic group.In addition,rosmarinic acid reduced white blood cell count and the percentages of eosinophils,monocytes,and neutrophils while increasing the percentage of lymphocytes.Ovalbumin-induced lung pathological changes were significantly improved by treatment with rosmarinic acid.Conclusions:Rosmarinic acid improves tracheal smooth muscle responsiveness and lung pathological changes in ovalbumin-sensitized rats.

Preliminary Study on the Separation of Lysozyme,Ovotransferrin and Ovalbumin from Egg White

[Objective] A study on separation process of lysozyme, ovotransferrin and ovalbumin from egg white. [Method] The proteins were separated by ammonium sul-fates and ion-exchange chromatography. Purity of the proteins was assayed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS-PAGE）. [Result] The results showed that the proteins were electrophoresis-pure. The specific activity of lysozyme was increased from 144.13 to 2 235 U/mg, and purification factor was 15-fold. Lysozyme recovery rate was estimated to be 15.76%. Bacteriostasis rate of ovotransferrin was 48.84%. [Conclusion] The procedure for separating lysozyme, ovotransferrin and ovalbumin from egg white was simple, fast, low-cost and suitable for industrilization.

Protective effect of Bifidobacterium infantis CGMCC313-2 on ovalbumin-induced airway asthma and b-lactoglobulininduced intestinal food allergy mouse models

AIM To determine whether oral administration of Bifidobacterium infantis CGMCC313-2(B. infantis CGMCC313-2) inhibits allergen-induced airway inflammation and food allergies in a mouse model.METHODS Ovalbumin(OVA)-induced allergic asthma and b-lactoglobulin-induced food allergy mouse models were used in this study. Following oral administration of B. infantis CGMCC313-2 during or after allergen sensitization, histopathologic changes in the lung and intestine were evaluated by hematoxylin and eosin(HE) staining. In the allergic asthma mouse model, we evaluated the proportion of lung-infiltrating inflammatory cells. OVAspecific IgE and IgG1 levels in serum and cytokine levels in bronchoalveolar lavage fluid(BALF) were also assessed. In the food allergy mouse model, the levels of total Ig E and cytokines in serum were measured.RESULTS Oral administration of B. infantis CGMCC313-2 during or after allergen sensitization suppressed allergic inflammation in lung and intestinal tissues, while the proportion of infiltrating inflammatory cells was significantly decreased in the BALF of allergic asthma mice. Moreover, B. infantis CGMCC313-2 decreased the serum levels of total Ig E in food allergy mice, and reductions in IgE and IgG1 were also observed in OVA-induced allergic asthma mice. The expression of interleukin-4(IL-4) and IL-13 in both serum and BALF was suppressed following the administration of B. infantis CGMCC313-2, while an effect on serum IL-10 levels was not observed.CONCLUSION B. infantis CGMCC313-2 inhibits the secretion of allergen-induced IgE, IL-4 and IL-13, and attenuates allergic inflammation.

The influence of Trichosanthin on the induction of IgE responses to ovalbumin under adjuvant-free condition

Trichosanthin(TCS) is a potent allergen in mice. It can reproducibly induce specific IgE responses in C57BL/6J mice without the help of adjuvant alum. TCS can bring out the IgE responses to ovabumin(OVA), while OVA itself could not induce IgE responses to it. How- ever, TCS only works when QVA immunization is given one day after TCS immunization. Either time lag in OVA immunization, or immunization of both antigens at the same time, or OVA immunization given first, all has no effect on the induction of IgE responses to OVA. Through analysis of the antibody specificity of hybridoma clones, it indicated that specific antibodies to TCS or OVA were secreted by independent B cell clones. The IgE antibodies showed no polyreactivity to different antigens.

Structural and functional properties of hydrolyzed/glycosylated ovalbumin under spray drying and microwave freeze drying

Ovalbumin(OVA),the main protein in egg white,affects most of the functional properties of egg white protein in food processing.The aim of this study was to investigate the effects of spray drying(SD)and microwave freeze drying(MFD)on the preparation of hydrolyzed/glycosylated ovalbumin(HGOVA)and provide useful information on the applications of egg protein powders in the food industry.Results demonstrated that the structure of HGOVA was considerably changed,and its functional properties were improved compared with those of native OVA.SD and MFD processing did not lead to dissociation of HGOVA subunits.SD-HGOVA exhibited higher protein solubility,emulsifying activity,foaming capacities,and gel hardness than MFD-HGOVA.However,MFD-HGOVA was better than the SD-HGOVA in terms of color,emulsion stability,foam stability,water/oil absorption capacity,and thermal stability.Selection of an appropriate drying method could enhance the potential applications of HGOVA in the food industry.

Myricetin alleviates ovalbumin-induced allergic rhinitis in mice by regulating Th1/Th2 balance

Objective:To evaluate the effect of myricetin on ovalbumin(OVA)-induced allergic rhinitis in mice.Methods:Mice were sensitized and challenged using OVA(5%,500 mL)intraperitoneally and intranasally,respectively,on an alternative day for 14 days,followed by administration of myricetin(50,100,and 200 mg/kg)till day 21.Nasal symptoms,biochemical parameters,protein expressions,and histopathology were observed.Results:OVA-induced increased nasal symptoms including rubbing,sneezing,and discharge were significantly reduced by myricetin(100and 200 mg/kg)(P<0.05).Myricetin also protected against histamine challenge and attenuated elevated serum immunoglobulin E(IgE;total and OVA-specific),total IgG1,andβ-hexosaminidase levels,as well as leukotriene C4 and interleukins levels in nasal lavage fluid(P<0.05).Western blot analysis showed that myricetin significantly upregulated the protein expression of T-box expressed in T cells,while downregulating the protein expression of GATA binding protein 3,NF-κB,and IκB-α(P<0.05).Additionally,OVA-induced histopathological abberations in the nasal mucosa was markedly ameliorated by myricetin treatment(P<0.05).Conclusions:Myricetin exerts anti-allergic effects against OVAinduced allergic rhinitis via regulating Th1/Th2 balance.

Electrochemical study of pyrite-ovalbumin interaction in relation to flotation

Ovalbumin （OVA）, chicken egg albumin, is an environmentally friendly, non-toxic, cheap surface active agent. It has electrochemically active sulfhydryl residues in molecular structure. OVA adsorption on pyrite as an alternative depressant was investigated by cyclic voltammetry, FTIR spectroscopy and flotation. Tests were conducted in a wide potential range in alkaline pH to clarify the role of electrochemical condition on the adsorption mechanisms and the rate of depression. In the absence of OVA, the floatability reached its maxima around slightly oxidizing condition. Beyond the range, it decreased presumably due to the formation of Fe-oxyhydroxides together with the hydrophilic S-containing species. OVA-pyrite interaction occurred in the whole examined potential range. Depressing effect of OVA increased gradually from reducing to slightly oxidizing potential, open circuit potential （OCP） of pyrite, mainly due to weak conformational changes in OVA molecules together with the hydrophobic interaction around OCP. The rate of depression reached its maxima at moderately oxidizing potentials, which was referred to electrostatic attraction. This level was almost kept at higher potentials owing to OVA adsorption as metal-chelates.

Cyclodextrin/chitosan nanoparticles for oral ovalbumin delivery: Preparation, characterization and intestinal mucosal immunity in mice

A novel oral protein delivery system with enhanced intestinal penetration and improved antigen stability based on chitosan(CS) nanoparticles and antigen-cyclodextrin(CD) inclusion complex was prepared by a precipitation/coacervation method. Ovalbumin(OVA) as a model antigen was firstly encapsulated by cyclodextrin, either β-cyclodextrin( β-CD) or carboxymethyl-hydroxypropyl-β-cyclodextrin(CM-HP-β-CD) and formed OVA-CD inclusion complexes, which were then loaded to chitosan nanoparticles to form OVA loaded β-CD/CS or CM-HP-β-CD/CS nanoparticles with uniform particle size(836.3 and 779.2 nm, respectively) and improved OVA loading efficiency(27.6% and 20.4%, respectively). In vitro drug release studies mimicking oral delivery condition of OVA loaded CD/CS nanoparticles showed low initial releases at p H 1.2 for 2 h less than 3.0% and a delayed release which was below to 30% at p H 6.8 for further 72 h. More importantly, after oral administration of OVA loaded β-CD/CS nanoparticles to Balb/c mice, OVA-specific sIgA levels in jejunum of OVA loaded β-CD/CS nanoparticles were 3.6-fold and 1.9-fold higher than that of OVA solution and OVA loaded chitosan nanoparticles, respectively. In vivo evaluation results showed that OVA loaded CD/CS nanoparticles could enhance its efficacy for inducing intestinal mucosal immune response. In conclusion, our data suggested that CD/CS nanoparticles could serve as a promising antigen-delivery system for oral vaccination.

Preparation and Characterization of β-Cyclodextrin Derivatized Ovalbumin Used as Chiral Selector in Pressure Capillary Electrochromatography

Synthesis and properties of β-cyclodextrin derivatized ovalbumin used as chiral selector were investigated, β-cyclodextrin derivatized ovalbumin was synthesized using β-cyclodextrin and ovalbumin in the presence of ethylene glycol diglycidyl ether in boric acid buffer at pH value 8.7 at 37℃. Amino group was coated on the internal surface of the silica capillary by sol-gel technology with triethoxylmethylsiloxane and （3-aminopropyl）trimethoxysiloxane. Covalent binding of g-cyclodextrin derivatized ovalbumin was performed by glutaraldehyde. Enantiomers of chlorpheniramine, phenylalanine and atropine were separated by pressure capillary electrochromatography column coated with β-cyclodextrin derivatized ovalbumin.

The effect of inhibitor peptide for ADAM8 in attenuating ovalbumin-induced murine asthma

Targeted peptides have been identified as showing great promise for treatment of various diseases including asthma.Asthma is considered of difficuIt-to-treat due to its unclear etiology,thus usually requiring life-long treatment.Current strategies for asthma therapy are hampered with undesirable side effects,poor targeting and failure in modulating airway hyperresponsiveness,leading to pressing need of developing more targeted and effective therapeutic sites for asthma.Recently,a disintegrin and metalloproteinase 8(ADAM8)have been shown to over-

Molecular dynamics simulations of ovalbumin adsorption at squalene/water interface

The adsorption of protein molecules to oil/water(O/W)interface is of critical importance for the product design in a wide range of technologies and industries such as biotechnology,food industry and pharmaceutical industry.In this work,with ovalbumin(OVA)as the model protein,the adsorption conformations at the O/W interface and the adsorption stability have been systematically studied via multiple simulation methods,including all-atom molecular dynamic(AAMD)simulations,coarse-grained molecular dynamic(CGMD)simulations and enhanced sampling methods.The computational results of AAMD and CGMD show that the hydrophobic tail of OVA tends to be folded under long time relaxation in aqueous phase,and multiple adsorption conformations can exist at the interface due to heterogeneous interactions raising from oil and water respectively.To further study the adsorption sites of the protein,the adsorption kinetics of OVA at the O/W interface is simulated using metadynamics method combined with CGMD simulations,and the result suggests the existence of multiple adsorption conformations of OVA at interface with the head-on conformation as the most stable one.In all,this work focuses on the adsorption behaviors of OVA at squalene/water interface,and provides a theoretical basis for further functionalization of the proteins in emulsion-based products and engineering.

MBD2 promotes Th2 differentiation in ovalbumin-induced CD4+T cells

Introduction:Allergen-specific CD4+T cells play a central role in autoimmune disorders,allergies and asthma,with Th2-type immunity being the typical functional response of CD4+T cells.This study aimed to investigate the role of MBD2 in regulating Th2 cell differentiation.Methods:Splenic mononuclear cells were extracted from C57BL/6 mice,and CD4+T cells were isolated using magnetic beads and confirmed through flow cytometry.Lentivirus was employed to construct MBD2-silenced CD4+T cells.In vitro experiments were performed to treat splenogenic mononuclear cells and CD4+T cells with Ovalbumin(OVA),and Th2 cell ratios and IL-4 levels were assessed using flow cytometry and ELISA.Results:The purity of the isolated CD4+T cells was 95.73%,confirming successful isolation of primary CD4+T cells.Compared to the control group,the Th2 cell ratio exhibited an increase in the Th2-induced group.Treatment with 5-Aza(concentrations,1-100μM)promoted Th2 cell differentiation and increased IL-4 levels.Notably,when combined with Th2 induction and 10μM 5-Aza treatment,silencing MBD2 further amplified Th2 cell ratios and elevated IL-4 levels in cell supernatants.Furthermore,OVA(concentration,200μg/mL)induced the differentiation of CD4+T cells into Th2 cells and increased IL-4 secretion.Interestingly,silencing MBD2 significantly increased the Th2 cell ratio and IL-4 levels in OVA-treated CD4+T cells.Conclusion:In summary,OVA promoted CD4+T cell differentiation into Th2 cells and enhanced IL-4 levels.MBD2 was identified as a mediator of Th2 cell differentiation in splenic-derived CD4+T cells,influenced by OVA or 5-Aza treatment.

<i>Mycobacterium vaccae</i>Immunization to Pregnant BALB/c Mice Ameliorated Lung Histopathology and Bone Marrow Eosinophila in Ovalbumin Sensitized Offsprings

Context: One of the treatment strategies for atopic diseases is to skew immune response away from Th2 dominance by using Mycobacterial strains. Objective: We wanted to find out whether M. vaccae administration to pregnant mice had any preventive effect on the offsprings in the development of a murine asthma model. Materials and Methods: Pregnant BALB/c mice were divided into two groups;first group received heat-killed M. vaccae subcutaneously on 12th day of pregnancy and the latter group received PBS. After delivery, newborn mice of each group were further divided into two subgroups as M. vaccae/Ovalbumin (OVA), M. vaccae/control, PBS/OVA and PBS/ control. To establish experimental murine asthma model, mice were intraperitoneally sensitized and challenged intratracheally with Ovalbumin. We analysed airway histopathology, bone marrow eosinophil progenitors and splenic cell cytokine profiles of the offsprings. Results: Comparison of offsprings in M. vaccae/OVA group were not different than PBS controls with respect to thicknesses of airway epithelium, basement membrane, subepithelial smooth muscles and number of hyperplasic goblet cells as well as bronchial associated lymphoid tissue density and eosinophil progenitors in the bone marrow. Comparison of M. vaccae/OVA group to asthma model revealed significant differences and lower levels of OVA-induced IL-5. Conclusions: We propose that immunization of pregnant BALB/c with M. vaccae could prevent histopathological alterations in the airways related to the asthma model and down-regulates IL-5 secretion from splenocytes of offsprings.

Untargeted serum metabonomic reveals alleviated ovalbumin-induced asthma by Baijin Pingchuan(白金平喘)through primary bile acid biosynthesis

OBJECTIVE: To investigate the effect of baijinpingchuan(白金平喘, BJPC) on the asthma rat model and identify differential metabolites and disturbed metabolic pathways. METHODS: The rats were categorized into six groups: control, dexamethasone(DEX), ovalbumin(OVA), and low-, median-, and high-dose BJPC. The rats, except for the control group, were initially treated with OVA to develop the asthma model, which was then activated using DEX, OVA, and low-, median-, and high-dose BJPC. Enzyme-linked immunosorbent assay kit was used to detect the expression of interleukin(IL)-33, IL-25, thymic stromal lymphopoietin(TSLP), and transforming growth factor-beta 1(TGF-β1). Hematoxylin and eosin staining were performed to observe the pathological condition of the lung. Untargeted serum metabonomic analysis was conducted to identify differential metabolites and disturbed metabolic pathways. RESULTS: High-dose BJPC significantly inhibited the expression of IL-33, IL-25, TSLP, and TGF-β1(P < 0.0001). Further, high-dose BJPC improved inflammatory cell infiltration, which plays a similar role in asthma as DEX. OVA-induced and BJPC-treated rats were identified through 17 differential metabolites, especially cholic acid. Furthermore, primary bile acid biosynthesis was a significantly differential pathway in the mechanism of BJPC for treating asthma. CONCLUSIONS: BJPC plays an anti-inflammation role in asthma, which might be a promising therapy through mediating primary bile acid biosynthesis.

Development of ovalbumin implants with different spatial configurations for treatment of peripheral nerve injury

Peripheral nerve injury(PNI)seriously affects the health and life of patients,and is an urgent clinical problem that needs to be resolved.Nerve implants prepared from various biomaterials have played a positive role in PNI,but the effect should be further improved and thus new biomaterials is urgently needed.Ovalbumin(OVA)contains a variety of bioactive components,low immunogenicity,tolerance,antimicrobial activity,non-toxicity and biodegradability,and has the ability to promote wound healing,cell growth and antimicrobial properties.However,there are few studies on the application of OVA in neural tissue engineering.In this study,OVA implants with different spatial structures(membrane,fiber,and lyophilized scaffolds)were constructed by casting,electrospinning,and freeze-drying methods,respectively.The results showed that the OVA implants had excellent physicochemical properties and were biocompatible without significant toxicity,and can promote vascularization,show good histocompatibility,without excessive inflammatory response and immunogenicity.The in vitro results showed that OVA implants could promote the proliferation and migration of Schwann cells,while the in vivo results confirmed that OVA implants(the E5/70%and 20 kV 20μL/min groups)could effectively regulate the growth of blood vessels,reduce the inflammatory response and promote the repair of subcutaneous nerve injury.Further on,the high-throughput sequencing results showed that the OVA implants up-regulated differential expression of genes related to biological processes such as tumor necrosis factor-α(TNF-α),phosphatidylinositide 3-kinases/protein kinase B(PI3K-Akt)signaling pathway,axon guidance,cellular adhesion junctions,and nerve regeneration in Schwann cells.The present study is expected to provide new design concepts and theoretical accumulation for the development of a new generation of nerve regeneration implantable biomaterials.

Effects of phosphorylated ovalbumin on the quality of pork myofibrillar protein gel:an insight into gelling and physicochemical properties

This study aimed to investigate the effects of phosphorylated-ovalbumin(P-OVA)at different concentrations(0.5%and 1.0%)on the gel properties of pork myofibrillar protein(MP).The results showed that the textural properties such as gel hardness,cohesiveness,springiness and chewiness were improved with P-OVA addition at 0.5%.The water holding capacity(up to 75.89%)and gel strength(up to 168.56 g·mm)of MP gel were markedly increased after P-OVA addition.The absolute value of zeta potential reached 13.85 mV and maximum hydrophobicity(15.2μg)resulted from the addition of 0.5%P-OVA.The storage modulus(G’)and loss modulus(G’’)of MP gel were significantly increased from 50°C,and the G’and G’’significantly increased after 1.0%P-OVA addition,evidencing that the cross-linking effect of MP protein gel was enhanced.In addition,the P-OVA addition improved the structure of MP gel protein by reducing theα-helix,while increasing theβ-sheet and the r-value(the ratio between two ultraviolet second-derivative peak-to-trough distances),which further promoted the uniform and compact gel network structure.This work demonstrated that P-OVA is a highly effective modifier that significantly improves the quality of MP gel.From a view of practice,0.5%P-OVA is the optimal addition amount.

Effect of dexamethasone injection into Zusanli(ST 36) acupoint on ovalbumin-induced allergic rhinitis

OBJECTIVE:To investigate the effects of acupunc ture with dexamethasone(A.Dex)on allergic rhini tis(AR)by injecting dexamethasone into the Zusan li(ST 36)acupoint.METHODS:Thirty 6-week-old female BALB/c mice were sensitized on days 1,5,and 14 by intraperitoneal injection of 100 pg of ovalbumin(OVA).The mice were then randomly divided into six groups(n =5 in each group).Five groups were sensitized intranasally with 2μL of 1.5 mg of OVA for 10 consecutive days,while one group was sensitized intranasally with PBS in a similar manner as a negative control group.One hour before each administration of intranasal OVA,two groups were orally administered either a control vehicle(distilled water;AR control group)or 200 pg/kg Dex(O.Dex group),while three groups received A.Dex at Zusanli(ST36)with Dex concentrations of 2,20,and 200μg/kg for each group,respectively.AR symptoms were evaluated by measuring the rubbing score,which comprised the number of nose,ear,and eye rubs that occurred in the initial 10 min after OVA intranasal provocation on the 10 th day.We isolated spleen,serum,and nasal mucosal tissue after measuring the rubbing score.Spleen weight was measured using an electronic microbalance.The levels of IgE,thymic stromal lymphopoietin,tumor necrosis factor-a,intercellular adhesion molecule-1,and macrophage-inflammatory protein-2 in serum or nasal mucosal tissue were measured using enzyme-linked immunosorbent assays.The serum histamine levels of OVA-sensitized AR mice were measured using O-phthaldialdehyde spectrofluorometry.Western blot analysis was performed on nasal mucosal tissue extracts.RESULTS:A.Dex significantly reduced the rubbing score,spleen weight,serum IgE,and serum histamine in OVA-sensitized mice.A.Dex significantly decreased the serum levels of inflammatory cytokines(thymic stromal lymphopoietin and tumor necrosis factor-a)in OVA-sensitized mice.A.Dex significantly reduced the nasal mucosal levels of inflammatory markers(intercellular adhesion molecule-land macrophage-inflammatory protein-2)in AR mice.A.Dex effectively attenuated the expression of caspase-1 and receptorinteractingprotein-2 in nasal mucosal tissue.CONCLUSION:A.Dex may be a new and useful therapy for AR.

Effects of phosphodiesterase 4 inhibitor on cough response in guinea pigs sensitized and challenged with ovalbumin

BACKGROUND: There is currently considerable interest in the potential value of selective inhibitors of cyclic nucleotide phosphodiesterase 4 in the treatment of asthma. However, whether they influence eosinophilic airway inflammation-associated cough remains unclear. The objective of this study was to investigate the effects of selective phosphodiesterase 4 inhibitor SB207499 on cough response and airway inflammation in guinea pigs sensitized and challenged with ovalbumin. METHODS: Forty sensitized guinea pigs were randomly divided into four groups: control (n = 10), challenge (n = 10), SB207499 (n = 10) and aminophylline (n = 10), then challenged with aerosol of 1% ovalbumin or saline. Two hours later, animals were intraperitoneally injected with either saline, 25 mg/kg of SB207499 or aminophylline. At the 24th hour, the injection was repeated with 2.5 mg/kg and 25 mg/kg SB207499 or aminophylline, then cough response to inhaled capsaicin and airway responsiveness to methacholine inducing a 150% of the peak airway pressure to the baseline (PC150) was measured. Finally, total cell number and differentials in bronchoalveolar lavage fluid were analysed. RESULTS: The cough frequency per 3 minutes and PC150 in the challenge group were (22 +/- 4) times/3 minutes and (198 +/- 54) microg/ml, which were significantly different from (6 +/- 2) times/3 minutes and (691 +/- 81) microg/ml in the control group (P