Airway Inflammation In Guinea Pigs Research Articles

Berberine Improves Histopathological Changes of Allergic Airway Inflammation in Guinea Pigs

<p><strong>Background and Objective:</strong> Berberine has anti-inflammatory properties through pathways that are also involved in asthma. Therefore, it is postulated that it will be effective in reducing airway inflammation in the allergic asthmatic model. The objective of the current study was to observe the effects of berberine on the histopathology of lungs in sensitized Guinea pigs and compare the changes with that of the standard drug, dexamethasone.</p>
 <p><strong>Methods:</strong> This experimental study was conducted at the Postgraduate Medical Institute, Lahore, Pakistan, from February 2016 to April 2016. Twenty-four healthy Guinea pigs were divided randomly into four groups: normal control, Ovalbumin (OVA ) group, OVA + berberine group, and OVA + dexa group. The last three groups were sensitized on days 0 and 14 and challenged on days 25, 26, and 27 with OVA. Berberine and dexamethasone were administered intraperitoneally to the respective groups before each challenge. The animals were then sacrificed on day 28 under anesthesia, lungs were dissected, and tissue samples were assessed microscopically for morphology and status of inflammation in each group. Data were analyzed by applying the Kruskal-Wallis analysis of variance test followed by the Mann Whitney U test using SPSS 20.</p>
 <p><strong>Results:</strong> The comparison of histopathological changes revealed that the infiltration of inflammatory cells in the lung airways was significantly higher (p-value ≤0.01) in the OVA group as compared to the normal control group. Both OVA + berberine and OVA + dexa groups showed a reduction in total lung inflammation (p-value ≤0.01 vs. OVA group) equally. The effect of berberine on epithelial changes was nonsignificant (p-value 0.206 vs. OVA group), while dexamethasone showed significant improvement as compared to the OVA group (p-value 0.007). However, the difference between berberine and dexamethasone treatment was nonsignificant (p-value ≤0.05).</p>
 <p><strong>Conclusion: </strong>It was concluded that berberine improved the histopathological score of lung inflammation in sensitized Guinea pigs, equivalent to that of dexamethasone, with lesser effects on epithelial changes.</p>

Endocannabinoid metabolism inhibition ameliorates ovalbumin-induced allergic airway inflammation and hyperreactivity in Guinea pigs

AimsEndocannabinoids are biologically active cannabinoid-related substances endogenously synthesized in many mammalian tissues. Mainly two enzymes carry out their degradation; Fatty Acid Amide Hydrolase (FAAH) and Monoacylglycerol Lipase (MAGL). Endocannabinoids are shown to affect the modulation of inflammatory processes and airway responsiveness. In the present study, we investigated the effects of FAAH and MAGL inhibitor treatments in experimental allergic airway inflammation in guinea pigs. Materials and methodsGuinea pigs were sensitized and challenged by ovalbumin to induce an allergic asthma model. Then, the effects of FAAH inhibitor URB597, MAGL inhibitor JZL184, and dual (FAAH/MAGL) inhibitor JZL195 on airway inflammation and hyperreactivity were evaluated. Key findingsOvalbumin challenge increased airway reactivity, IgE in serum, IL-4, and IL-13, and the percentage of eosinophils in bronchoalveolar lavage (BAL). In addition, inhibition of FAAH or MAGL enzymes leads to an increase in endocannabinoid levels. The selective inhibition of the FAAH enzyme prevented inflammation indicators such as cytokine production and inflammatory cell infiltration but had a negligible effect on airway hyperreactivity. However, the inhibition of the MAGL enzyme or dual inhibition of both FAAH and MAGL enzymes tent to moderate both pulmonary inflammation and airway hyperreactivity. SignificanceWe have previously demonstrated that modulation of endocannabinoid levels in the airways by FAAH or MAGL inhibition can be useful in preventing acute lung inflammation. The results of the present study further suggest that FAAH and MAGL inhibitor treatment can also be a promising strategy for bronchial hyperreactivity and airway inflammation in allergic asthma.

The anti-asthmatic potential of flavonol kaempferol in an experimental model of allergic airway inflammation

Flavonol kaempferol possesses a broad spectrum of potent pharmacological activities that seem to be effective in the modulation of allergic respiratory diseases. In our study, an experimental animal model of ovalbumin (OVA)-induced allergic airway inflammation in guinea pigs was used to determine the anti-asthmatic potential of kaempferol. The parameters of specific airway resistance (sRaw) and cough reflex response were evaluated in vivo. In vitro, an assessment of tracheal smooth muscle (TSM) contractility and analyses of inflammatory cytokines (IL-4, IL-5, IL-13, GM-CSF, IFN-γ), transforming growth factor (TGF-β1), immune cells count and ciliary beating frequency (CBF) were performed. Both single (6, 20 mg/kg b. w. p. o.) and long-term administered doses of kaempferol (20 mg/kg b. w. p. o., 21 days) suppressed sRaw provoked by histamine in conscious animals. The administration of kaempferol for 21 days attenuated histamine-induced TSM contractility in vitro and ameliorated the progression of chronic airway inflammation by decreasing the levels of IL-5, IL-13, GM-CSF, eosinophil count in bronchoalveolar lavage (BAL) fluid and TGF-β1 protein level in lung tissue. Kaempferol also eliminated the alterations in cough reflex sensitivity invoked by OVA-sensitization, but it did not affect CBF. The results demonstrate that flavonol kaempferol can modulate allergic airway inflammation and associated asthma features (AHR, aberrant stimulation of cough reflex).

Stigmasterol Modulates Allergic Airway Inflammation in Guinea Pig Model of Ovalbumin-Induced Asthma.

We explored the potential benefits of stigmasterol in the treatment of asthma, an airway disorder characterized by immune pathophysiology and with an ever-increasing worldwide prevalence. We assessed the modulatory effect of the intraperitoneal administration of stigmasterol on experimentally induced airway inflammation in guinea pigs. The effect of stigmasterol on inflammatory cell proliferation, oxidative stress, lung histopathology, and remodeling was investigated. The results showed significant suppressive effects on ovalbumin-induced airway inflammatory damage. Stigmasterol at 10–100 mg/kg reduced proliferation of eosinophils, lymphocytes, and monocytes while reducing peribronchiolar, perivascular, and alveolar infiltration of inflammatory cells. Histopathology revealed stigmasterol maintained lung architecture and reversed collagen deposition, an index of lung remodeling. Overexpression of serum vascular cell adhesion molecule-1 (VCAM-1) and ovalbumin-specific immunoglobulin E (OVA sIgE) elicited by ovalbumin sensitization and challenge was significantly controlled with stigmasterol. Taken together, stigmasterol possessed significant antiasthmatic properties and had suppressive effects on key features of allergen-induced asthma.

Role of selective blocking of bradykinin receptor subtypes in attenuating allergic airway inflammation in guinea pigs

The present study was designed to evaluate the potential role of bradykinin antagonists (R-715; bradykinin B1 receptor antagonist and icatibant; bradykinin B2 receptor antagonist) in treatment of allergic airway inflammation in comparison to dexamethasone and montelukast. R-715 as dexamethasone significantly decreased peribronchial leukocyte infiltration, bronchoalveolar lavage fluid (BALF) albumin and interleukin 1β as well as serum OVA-specific IgE level. Also, R-715 like montelukast significantly decreased BALF cell count (total and eosinophils). Icatibant showed negative results. The current findings suggest that selective bradykinin B1 receptor antagonists may have the therapeutic potential for the treatment of allergic airway inflammation.

Inhibitory effect of sihuangxiechai decoction on ovalbumin-induced airway inflammation in Guinea pigs.

The aim of this study was to investigate the effect of sihuangxiechai decoction on asthmatic Guinea pig model which was sensitized by intraperitoneal (i.p.) injection of ovalbumin (OVA) and challenged by OVA inhalation to induce chronic airway inflammation. Differential cell counts of cytospins were performed after staining with Giemsa solution. The quantity of leukocytes and its classification in bronchoalveolar lavage fluid (BALF) and blood were evaluated by blood cell analyzer and microscope. Histological analysis of the lung was performed by hematoxylin and eosin (H&E) staining. The levels of interleukin-4 (IL-4) and tumor necrosis factor-alpha (TNF-α) in BALF and serum were detected by radioimmunoassay (RIA). The total number of leukocytes in BALF and blood has no significant difference between Sihuangxiechaitang decoction treated group and dexamethasone (DXM) treated group but was significantly lower than those of asthma group. The percentage of eosinophils in lung tissues of sihuangxiechai decoction treated group was significantly lower than that of asthma group. The results demonstrated that the levels of IL-4 and TNF-α in the sihuangxiechai decoction treated group were significantly reduced compared with the asthma group. In conclusion, these findings demonstrate that sihuangxiechai decoction has a protective effect on OVA-induced asthma in reducing airway inflammation and airway hyperresponsiveness (AHR) in a Guinea pig model and may be useful as an adjuvant therapy for the treatment of bronchial asthma.

Therapeutic potential of anti-IL-1β IgY in guinea pigs with allergic asthma induced by ovalbumin

BackgroundInterleukin-1 beta (IL-1β) plays pivotal roles in the progression of allergic airway inflammation. This study aims to determine whether the blockade of IL-1β can inhibit airway inflammation in guinea pigs with allergic asthma induced by the inhalation of aerosolized ovalbumin (OVA). MethodsHealthy guinea pigs treated with saline were used as normal controls (group C). The guinea pigs with allergic asthma induced by the inhalation of aerosolized OVA were randomly divided into three groups: (1) the M group containing negative control animals treated with saline; (2) the Z1 group containing animals treated by the inhalation of atomized 0.1% anti-IL-1β immunoglobulin yolk (IgY); and (3) the Z2 group containing positive control animals that were treated with budesonide. The inflammatory cells in the peripheral blood (PB) and bronchoalveolar lavage fluid (BALF) were evaluated using methylene blue and eosin staining. Cytokine concentrations were measured using an enzyme-linked immunosorbent assay. Pulmonary sections were examined using hematoxylin-eosin staining. ResultsAllergic inflammation and damage to the pulmonary tissues were decreased in the Z1 group compared to the M group. Eosinophils and neutrophils in the PB and BALF were significantly decreased in the Z1 group compared to the M group (P<0.05). Treatment with anti-IL-1β IgY significantly reduced the levels of IL-1β, IL-4, IL-8, IL-13, TNF-α, TGF-β1 and IgE in the BALF (P<0.05). ConclusionThe inhalation of aerosolized anti-IL-1β IgY inhibits pathological responses in the pulmonary tissues of guinea pigs with allergic asthma. The inhibitory activity may be due to the decrease in the numbers of eosinophils and neutrophils and the reduced levels of inflammatory cytokines and IgE in the PB and BALF.

Toll-like Receptor 7 Rapidly Relaxes Human Airways

Toll-like receptors (TLRs) 7 and 8 detect respiratory virus single-stranded RNA and trigger an innate immune response. We recently described rapid TLR7-mediated bronchodilation in guinea pigs. To characterize TLR7 expression and TLR7-induced airway relaxation in humans and in eosinophilic airway inflammation in guinea pigs. To evaluate the relaxant effects of other TLRs. Human airway smooth muscle strips were contracted with methacholine in vitro, and responses to TLR7 and TLR8 agonists were assessed. TLR7-mediated nitric oxide production was measured using a fluorescent indicator, and TLR7 expression was characterized using immunofluorescence. TLR7 signaling was also evaluated in ovalbumin-challenged guinea pigs. The TLR7 agonist imiquimod (R837) caused rapid dose-dependent relaxation of methacholine-contracted human airways in vitro. This was blocked by the TLR7 antagonist IRS661 and by inhibiting nitric oxide production but not by inhibiting prostaglandin production. TLR7 activation markedly increased fluorescence of a nitric oxide detector. TLR7 was expressed on airway nerves, but not airway smooth muscle, implicating airway nerves as the source of TLR7-induced nitric oxide production. TLR7-mediated relaxation persisted in inflamed guinea pigs airways in vivo. The TLR8 agonists polyuridylic acid and polyadenylic acid also relaxed human airways, and this was not blocked by the TLR7 antagonist or by blocking nitric oxide or prostaglandin production. No other TLRs relaxed the airways. TLR7 is expressed on airway nerves and mediates relaxation of human and animal airways through nitric oxide production. TLR7-mediated bronchodilation may be a new therapeutic strategy in asthma.

Air Pollution and Chronic Cough in China: Response

We thank Dr Mao and colleagues for their interest and comments regarding our recent article in CHEST.1Lai K Chen R Lin J et al.A prospective, multicenter survey on causes of chronic cough in China.Chest. 2013; 143: 613-620Abstract Full Text Full Text PDF PubMed Scopus (127) Google Scholar We agree that air pollution may be associated with cough. In a survey performed in six cities of northeastern China with heavy industrial air pollution, it was found that three air pollutants (total suspended particulates, SO2, NO2) significantly increased the prevalence of persistent cough in children (approximately 21%-28%).2Pan G Zhang S Feng Y et al.Air pollution and children's respiratory symptoms in six cities of Northern China.Respir Med. 2010; 104: 1903-1911Abstract Full Text Full Text PDF PubMed Scopus (59) Google Scholar Another study in Hong Kong also showed that exposure to particulate matter in different geographic locations was associated with increased odds of having cough.3Lai HK Ho SY Wong CM Mak KK Lo WS Lam TH Exposure to particulate air pollution at different living locations and respiratory symptoms in Hong Kong—an application of satellite information.Int J Environ Health Res. 2010; 20: 219-230Crossref PubMed Scopus (13) Google Scholar It is reasonable to suppose that haze induces respiratory symptoms including cough. Air pollution is a common problem in China and is usually more serious in winter and spring. Therefore, the prevalence of cough may vary in different seasons because of air pollution, low temperature, and fireworks as mentioned by Dr Mao. However, our study was focused on the spectrum of causes of chronic cough in the specialist outpatient clinic but not the prevalence of chronic cough in the community. It is difficult to make a subgroup adjusted for air quality data across various regions to clarify its relationship with chronic cough in current cohort groups. A community survey with larger samples is needed in the future to confirm whether there are seasonal or regional differences on the prevalence of chronic cough related to air pollution in China. Dr Mao pointed out that haze should be the main cause of unexplained cough. In some patients with chronic cough, no cause is identified, leading to the diagnosis of idiopathic cough or unexplained cough, which is often associated with an increased response to tussive agents such as capsaicin. Common cold or influenza are often triggers of chronic cough (including the common causes and unexplained cough) in our experience. It is reported that air pollution exposure clearly exacerbates preexisting bronchial asthma,4Anderson HR Favarato G Atkinson RW Long-term exposure to air pollution and the incidence of asthma: meta-analysis of cohort studies.Air Qual Atmos Health. 2013; 6: 47-56Crossref Scopus (163) Google Scholar and sulfur dioxide exposure increases cough response and airway inflammation in guinea pigs.5McLeod RL Jia Y McHugh NA et al.Sulfur-dioxide exposure increases TRPV1-mediated responses in nodose ganglia cells and augments cough in guinea pigs.Pulm Pharmacol Ther. 2007; 20: 750-757Crossref PubMed Scopus (26) Google Scholar However, there is no study to identify that air pollutants are able to cause chronic cough or increase cough sensitivity in humans directly so far. As pointed out in our article, it is still unclear whether unexplained cough represents a single entity or includes certain undiscovered causes of chronic cough. We consider that air pollutants may contribute to persistent cough, but it is unknown whether haze is a main cause of the unexplained cough. As we addressed in the article, although there was variation on the frequency of certain single causes in different regions, the four common causes were consistent across five different regions in China. In summary, we suppose that air pollution (in particular, heavy pollution in mid to east China) as a cause of chronic cough should be further elicited. Air Pollution and Chronic Cough in ChinaCHESTVol. 144Issue 1PreviewIn a recent issue of CHEST (March 2013), Lai et al1 demonstrated that cough variant asthma, upper airway cough syndrome, eosinophilic bronchitis, and atopic cough (AC) constituted the main causes of chronic cough across five regions in China, based on a prospective survey using a modified diagnostic algorithm. They also concluded that geography, seasonality, age, and sex were not related to the spectrum of chronic cough. We do agree with the authors' viewpoint. However, of note, in developing countries like China one major concern with the environmental factors (haze) should be raised because indoor and outdoor pollutants can cause chronic cough; namely, exposure to pollutants, such as diesel exhaust, sulfur oxides, ozone, nitrogen oxides, and particulate matter, participates in the development of respiratory symptoms. Full-Text PDF

Suppression of ovalbumin-induced Th2-driven airway inflammation by β-sitosterol in a guinea pig model of asthma

In the present study, the efficacy of β-sitosterol isolated from an n-butanol extract of the seeds of the plant Moringa oleifera (Moringaceae) was examined against ovalbumin-induced airway inflammation in guinea pigs. All animals (except group I) were sensitized subcutaneously and challenged with aerosolized 0.5% ovalbumin. The test drugs, β-sitosterol (2.5 mg/kg) or dexamethasone (2.5 mg/kg), were administered to the animals (p.o.) prior to challenge with ovalbumin. During the experimental period (on days 18, 21, 24 and 29), a bronchoconstriction test (0.25% acetylcholine for 30 s) was performed and lung function parameters (tidal volume and respiration rate) were measured for each animal. On day 30, blood and bronchoalveolar lavaged fluid were collected to assess cellular content, and serum was collected for cytokine assays. Lung tissue was utilized for a histamine assay and for histopathology. β-sitosterol significantly increased the tidal volume (V t) and decreased the respiration rate ( f) of sensitized and challenged guinea pigs to the level of non-sensitized control guinea pigs and lowered both the total and differential cell counts, particularly eosinophils and neutrophils, in blood and bronchoalveolar lavaged fluid. Furthermore, β-sitosterol treatment suppressed the increase in cytokine levels (TNFα, IL-4 and IL-5), with the exception of IL-6, in serum and in bronchoalveolar lavaged fluid detected in model control animals. Moreover, treatment with β-sitosterol protected against airway inflammation in lung tissue histopathology. β-sitosterol possesses anti-asthmatic actions that might be mediated by inhibiting the cellular responses and subsequent release/synthesis of Th2 cytokines. This compound may have therapeutic potential in allergic asthma.

RS-1748, a Novel CC Chemokine Receptor 4 Antagonist, Inhibits Ovalbumin-Induced Airway Inflammation in Guinea Pigs

CC chemokine receptor 4 (CCR4) is generally recognized as a preferential marker for T helper 2 cells, and we have previously reported morpholine-derivative CCR4 antagonists, RS-1154 and RS-1269. Here, we investigate the pharmacological profiles of a novel pyrimidine-derivative CCR4 antagonist, 2-{4-[2-(diethylamino)ethoxy]phenyl}-N-(2,4-difluorobenzyl)-5-fluoropyrimidin-4-amine (RS-1748), which showed potency to inhibit the bindings of [(125)I]CCL17 and [(35)S]GTPgammaS to human CCR4-expressing Chinese hamster ovary (CHO) cells with IC(50) values of 59.9 nM and 18.4 nM, respectively. Furthermore, RS-1748 inhibited ovalbumin-induced airway inflammation in guinea pigs at a dose of 10 mg/kg. These results indicate that RS-1748 would be a promising lead compound for developing a therapeutic agent against asthma.

Inhibitory Effect of n-butanol Fraction of Moringa oleifera Lam. Seeds on Ovalbumin-Induced Airway Inflammation in a Guinea Pig Model of Asthma

Moringaceae, which belongs to the Moringa oleifera Lam. family, is a well-known herb used in Asian medicine as an antiallergic drug. In the present study, the efficacy of the n-butanol extract of the seeds of the plant (MONB) is examined against ovalbumin-induced airway inflammation in guinea pigs. The test drugs (MONB or dexamethasone) are administered orally prior to challenge with aerosolized 0.5% ovalbumin. During the experimental period, bronchoconstriction tests are performed, and lung function parameters are measured. The blood and bronchoalveolar lavage fluid are collected to assess cellular content, and serum is used for cytokine (tumor necrosis factor-alpha, interleukin-4, and interleukin-6) assays. Histamine assays of lung tissue are performed using lung tissue homogenate. The results suggest that in ovalbumin-sensitized model control animals, tidal volume is decreased, respiration rate is increased, and both the total and differential cell counts in blood and bronchoalveolar lavage fluid are increased significantly compared with nonsensitized controls. MONB treatment shows improvement in all parameters except bronchoalveolar lavage tumor necrosis factor-alpha and interleukin-4. Moreover, MONB treatment demonstrates protection against acetylcholine-induced bronchoconstriction and airway inflammation. These results indicate that MONB has an inhibitory effect on airway inflammation. Thus, MONB possesses an antiasthmatic property through modulation of the relationship between Th1/Th2 cytokine imbalances.

Effect of Moringa oleifera Lam. Seed Extract on Ovalbumin-Induced Airway Inflammation in Guinea Pigs

To determine the therapeutic potential of herbal medicine Moringa oleifera Lam. family: Moringaceae in the control of allergic diseases, the efficacy of the ethanolic extract of the seeds of the plant (MOEE) against ovalbumin (OVA)-induced airway inflammation in guinea pigs was examined. During the experimental period, the test drugs (MOEE or dexamethasone) were administered by oral route prior to challenge with aerosolized 0.5% OVA. Bronchoconstriction tests were performed and respiratory parameters (i.e., tidal volume and respiratory rate) were measured. At the end of experiment, blood was collected from each animal to perform total and differential counts and serum was used for assay of IL-4, IL-6, and TNFα. Lung lavage fluid (BAL) was collected for estimation of cellular content and cytokine levels. Lung tissue histamine assays were performed using the homogenate of one lobe from each animal; a separate lobe and the trachea were subjected to histopathology to measure the degree of any airway inflammation. The results suggest that in OVA-sensitized control animals that did not receive either drug, tidal volume (Vt) was decreased, respiration rate (f) was increased, and both the total and differential cell counts in blood and BAL fluid were increased significantly. MOEE-treatment of sensitized hosts resulted in improvement in all parameters except BAL TNFα and IL-4. Moreover, MOEE-treatment also showed protection against acetylcholine-induced broncho-constriction and airway inflammation which was confirmed by histological observations. The results of these studies confirm the traditional claim for the usefulness of this herb in the treatment of allergic disorders like asthma.

FK506 Aerosol Locally Inhibits Antigen-Induced Airway Inflammation in Guinea Pigs

Background: Eosinophilic airway inflammation is a common pathological feature of asthma. It has been shown that FK506 given systemically suppresses antigen-induced airway inflammation in animal models. However, it is unknown whether inhaled FK506 can suppress the airway allergic inflammation/immune response and whether it acts locally or systemically. Methods: We tested the effects of oral FK506 and inhaled FK506 on antigen-induced airway inflammation in guinea pigs. The tissue and blood concentrations of FK506 given via both routes were compared. The effect of inhaled FK506 on the expression of cytokine mRNA in lung and bronchoalveolar lavage fluid (BALF) cells was also tested. Results: Both routes of administration of FK506 suppressed the airway eosinophilia in egg albumin (EA)-sensitized and -challenged animals. The effect of three inhaled puffs was almost equal to that of 1 mg/kg administered by the oral route. Following inhalation of three puffs, FK506 concentration in blood (AUC_{0–24 h}) was approximately 1/21 of that following oral FK506 (1 mg/kg). After EA challenge, mRNA expression of interleukin (IL)-5, eotaxin and IL-1β in BALF cells and IL-5 in the lung increased significantly. FK506 aerosol markedly inhibited IL-5 mRNA expression in the lung. In situ hybridization indicated that in the BALF IL-5 mRNA expression by lymphocyte-like cells was inhibited by FK506 aerosol. In addition, anti-IL-5 antibody injected intratracheally almost completely abolished eosinophilia in this model. Conclusion: Inhaled FK506 can suppress airway inflammation in guinea pigs, where the local action, presumably the inhibition of T-cell activation/function in the lung and airways, was primarily important.

Ebselen suppresses late airway responses and airway inflammation in guinea pigs

Although ebselen, a seleno-organic compound, inhibits inflammation in various animal models, its efficacy as an anti-asthma drug remains to be clarified. In this study, we investigated the inhibitory effect of ebselen on a guinea pig asthma model. Ebselen was orally administered at dosages of 1–20 mg/kg 2 h before an ovalbumin (OA) challenge, and then airway responses, airway inflammation, the generation of superoxide, H 2O 2, and nitrotyrosine, and the induction of inducible nitric oxide synthase (iNOS) were evaluated. Sensitized animals challenged with OA aerosol showed dual airflow limitations, i.e., immediate and late airway responses (IAR and LAR). Ebselen significantly inhibited LAR at dosages greater than 10 mg/kg, but did not inhibit IAR at any dosage. Bronchoalveolar lavage (BAL) examination showed that airway inflammation was significantly suppressed by ebselen at 10 mg/kg. The generation of superoxide and H 2O 2 occurred on endothelial cells of LAR bronchi, and was inhibited by 10 mg/kg of ebselen. Superoxide generation was inhibited by diphenyleneiodonium chloride (DPI), a NAD(P)H oxidase inhibitor, but not by allopurinol, a xanthine oxidase inhibitor. Immunoreactivities for iNOS and nitrotyrosine were also observed on endothelial cells of LAR bronchi and were abolished in ebselen-treated animals. The present findings suggest that ebselen can be applied as a new therapeutic agent for asthma. The possible mechanisms by which ebselen inhibits LAR likely involve suppression of oxidant formation and iNOS induction in endothelial cells.

Isoquinuclidine-based expectorants. Synthesis and biological activities of N-alkoxybenzylisoquinuclidines

Summary N -Di-, trialkoxybenzylisoquinuclidines and related compounds were synthesized and evaluated for expectorant activities. Structure-activity relationship investigations in this series showed that both the trialkoxyphenyl ring and the basic nitrogen atom at the benzylic position were necessary for activity. N -Trialkoxybenzylisoquinuclidines 7a, 7c, 7d, 7f and 7g significantly increased bronchial secretion, and ethoxy derivative 7c showed the highest activity in these compounds. The n -propyloxy derivatives 7d and 7f also accelerated bronchoalveolar surfactant secretion with about two to four times more activity than ambroxol ( 7d and 7f ; ED 50 = 27.5 and 15.5 mg/kg po, respectively); however, compounds 7a, 7c and 7g were less active than ambroxol. Compounds 7d and 7f were selected for further examination. These compounds displayed antioxidant activity in vitro ( 7d and 7f ; IC 50 = 48.0 and 66.0 μM, respectively). Compound 7d also showed inhibition on bradykinin- or antigen-induced airway inflammation in guinea pigs. These findings suggest that compounds 7d and 7f are potent expectorants with antiinflammatory activity.

Effects of moguisteine, a peripheral nonnarcotic antitussive agent, on airway inflammation in guinea-pigs in vivo.

Cough is a common symptom of respiratory diseases associated with irritation or inflammation of the airways, and symptomatic antitussive drugs are frequently prescribed to control an abnormal cough reflex. Our aim was to evaluate the effects of moguisteine, a novel, peripheral, nonnarcotic antitussive agent, on airway inflammation induced in guinea-pigs with a variety of stimuli. These stimuli included exposure to tobacco smoke for 10 min, to elicit airway hyperreactivity, eosinophil recruitment in bronchoalveolar lavage (BAL), airway epithelial damage and plasma exudation; graded platelet-activating factor (PAF) infusion (600 ng.kg-1 over one h), to induce airway hyperreactivity; 2% ovalbumin (OA) aerosol challenge in 1% OA-sensitized animals, to induce late-phase (17 and 72 h) airway leucocyte accumulation. We also assessed the activity of moguisteine on plasma leakage induced by capsaicin, on bronchoconstriction induced by acetylcholine (ACh), histamine (H) and PAF, and on leukotriene mediated allergic bronchospasm in OA-sensitized guinea-pig. Moguisteine (p.o. and i.m.) and dexamethasone (p.o. and i.m.) dose-dependently reduced tobacco smoke-induced bronchial hyperreactivity. Moguisteine and dexamethasone abolished eosinophil recruitment in BAL, prevented the sloughing of the epithelium and significantly reduced airway microvascular leakage. Both agents were also highly effective in reducing bronchial hyperreactivity elicited by PAF infusion. In addition, moguisteine was active in inhibiting airway neutrophil and eosinophil accumulation in BAL observed 17 and 72 h after OA challenge in sensitized guinea-pigs. In contrast to dexamethasone, moguisteine did not prevent capsaicin-induced plasma leakage. It was also ineffective against bronchoconstriction as induced by ACh, H, and PAF and failed to inhibit leukotriene-dependent bronchospasm. Our data suggest that moguisteine represents an antitussive compound endowed with interesting airway anti-inflammatory properties in guinea-pigs in vivo. Its mechanism of action remains to be elucidated.

P-478 - Effect of ZCR-2060 on experimental asthma and airway inflammation in guinea pigs.

P-478 - Effect of ZCR-2060 on experimental asthma and airway inflammation in guinea pigs.

Isbufylline, a new xanthine derivative, inhibits airway hyperresponsiveness and airway inflammation in guinea pigs

The pharmacological actions of the new xanthine, isbufylline, were evaluated in several models of airway hyperresponsiveness and airway inflammation in guinea pigs. At a dose (106 μmol kg −1 i.p.) providing complete protection against acetylcholine aerosol-induced dyspnea in the guinea pig, isbufylline inhibited platelet activating factor (PAF)- and antigen-induced eosinophil infiltration into bronchoalveolar lavage fluid 24 h after challenge of normal and actively immunized guinea pigs, respectively. In addition, this dose of isbufylline also inhibited capsaicin-induced extravasation of protein into bronchoalveolar lavage fluid. Isbufylline, 4.2 μmol kg −1 i.v., significantly inhibited PAF-induced bronchial hyper-responsiveness to i.v. histamine, without exerting evident bronchodilator activity. On the other hand the bronchodilator, salbutamol, at dose (10.4 μmol kg −1 i.p.) shown to be equieffective to isbufylline (106 μmol kg −1 i.p.) for blocking acetylcholine aerosol-induced dyspnea, had no protective action against PAF- or antigen-induced eosinophil recruitment in bronchoalveolar lavage fluid, or against capsaicin-induced plasma protein extravasation. Furthermore, salbutamol (3.5 μmol kg −1) significantly potentiated allergen-induced cell infiltration and PAF-induced bronchial hyperresponsiveness. The results suggest that isbufylline can exert significant anti-inflammatory actions in guinea pig airways, in addition to its bronchodilator activity. These pharmacological activities are not shared by the β 2-adrenoceptor agonist, salbutamol.

The effect of formoterol on the late asthmatic phenomena in guinea pigs

We investigated the effects of formoterol, a new, long-acting, selective β 2-adrenoceptor agonist, on the antigen-induced late asthmatic response (LAR) and airway inflammation in guinea pigs. Animals were sensitized by exposure to aerosolized ovalbumin (2% in saline). After antigen challenge, preceded by administration of an H 1-receptor antagonist, specific airway conductance was measured with a two-chambered whole-body plethysmograph. An aerosolized solution of formoterol, isoproterenol, or saline was inhaled 15 minutes before challenge. Bronchoalveolar lavage (BAL) was performed 24 hours after challenge. The provocative concentrations of histamine required to decrease specific airway conductance by 50% were obtained before challenge, at 24 hours, and at 72 hours after challenge. The LAR (52.7% ± 7.7% of the baseline; p < 0.02) was observed 6 to 8 hours after antigen challenge. An increased cellular influx in BAL (mainly eosinophils and macrophages) and an increased bronchial responsiveness to histamine occurred 24 hours after antigen challenge. Formoterol completely inhibited the LAR and the cellular increase in BAL; however, isoproterenol failed to prevent either the cellular infiltration or the LAR. Formoterol also decreased the antigen-induced increase in bronchial reactivity. These findings suggest that formoterol has inhibitory effects on the underlying inflammatory processes in antigen-induced asthma in addition to prolonged bronchodilation.