In vivo neutralization of eosinophil-derived major basic protein inhibits antigen-induced bronchial hyperreactivity in sensitized guinea pigs.

This study examines the effect of purified rabbit antiguinea pig eosinophil-derived major basic protein (MBP) Ig on antigen-induced bronchial hyperreactivity to inhaled acetylcholine in aerosol-sensitized guinea pigs. Ovalbumin inhalation by sensitized guinea pigs induced a rise in the numbers of eosinophils and in the levels of MBP in the bronchoalveolar lavage fluid, which peaked at 24 h and resolved at 72 h. Antigen-challenged animals exhibited bronchial hyperreactivity to inhale acetylcholine at 72 h, but not at 6 or 24 h. The intranasal administration of 200 microliter of purified rabbit anti-guinea pig MBP Ig, at 2.5 mg/ml, but not of the control preimmune rabbit Ig, 1 h before and 5 h after ovalbumin inhalation suppressed bronchial hyperreactivity to acetylcholine at 72 h without affecting the number of eosinophils accumulating in the bronchoalveolar lavage fluid. These findings indicate that antigen challenge in sensitized guinea pigs is followed by early eosinophil infiltration and activation within the airways and by late bronchial hyperreactivity. Neutralization of endogenously secreted MBP by a specific antiserum prevented antigen-induced bronchial hyperreactivity, suggesting that eosinophil degranulation plays an important role in the alterations of bronchopulmonary function in the guinea pig.     

The importance of leukotrienes in airway inflammation in a mouse model of asthma

Inhalation of antigen in immunized mice induces an infiltration of eosinophils into the airways and increased bronchial hyperreactivity as are observed in human asthma. We employed a model of late-phase allergic pulmonary inflammation in mice to address the role of leukotrienes (LT) in mediating airway eosinophilia and hyperreactivity to methacholine. Allergen intranasal challenge in OVA-sensitized mice induced LTB4 and LTC4 release into the airspace, widespread mucus occlusion of the airways, leukocytic infiltration of the airway tissue and broncho-alveolar lavage fluid that was predominantly eosinophils, and bronchial hyperreactivity to methacholine. Specific inhibitors of 5- lipoxygenase and 5-lipoxygenase-activating protein (FLAP) blocked airway mucus release and infiltration by eosinophils indicating a key role for leukotrienes in these features of allergic pulmonary inflammation. The role of leukotrienes or eosinophils in mediating airway hyperresponsiveness to aeroallergen could not be established, however, in this murine model.     

Role of vascular cell adhesion molecule 1/very late activation antigen 4 and intercellular adhesion molecule 1/lymphocyte function-associated antigen 1 interactions in antigen-induced eosinophil and T cell recruitment into the tissue

To determine the role of vascular cell adhesion molecule 1 (VCAM- 1)/very late activation antigen 4 (VLA-4) and intercellular adhesion molecule 1 (ICAM-1)/lymphocyte function-associated antigen 1 (LFA-1) interactions in causing antigen-induced eosinophil and T cell recruitment into the tissue, we studied the effect of the in vivo blocking of VCAM-1, ICAM-1, VLA-4, and LFA-1 by pretreatment with monoclonal antibodies (mAb) to these four adhesion molecules on the eosinophil and T cell infiltration of the trachea induced by antigen inhalation in mice. The in vivo blocking of VCAM-1 and VLA-4, but not of ICAM-1 and LFA-1, prevented antigen-induced eosinophil infiltration into the mouse trachea. On the contrary, the in vivo blocking of VCAM-1 and VLA-4, but not of ICAM-1 and LFA-1, increased blood eosinophil counts after antigen challenge, but did not affect blood eosinophil counts without antigen challenge in sensitized mice. Furthermore, the expression of VCAM-1 but not ICAM-1 was strongly induced on the endothelium of the trachea after antigen challenge. In addition, pretreatment with anti-IL-4 mAb decreased the antigen-induced VCAM-1 expression only by 27% and had no significant effect on antigen-induced eosinophil infiltration into the trachea. The in vivo blocking of VCAM- 1 and VLA-4 inhibited antigen-induced CD4+ and CD8+ T cell infiltration into the trachea more potently than that of ICAM-1 and LFA-1. In contrast, regardless of antigen challenge, the in vivo blocking of LFA- 1, but not of ICAM-1, increased blood lymphocyte counts more than that of VCAM-1 and VLA-4. These results indicate that VCAM-1/VLA-4 interaction plays a predominant role in controlling antigen-induced eosinophil and T cell recruitment into the tissue and that the induction of VCAM-1 expression on the endothelium at the site of allergic inflammation regulates this eosinophil and T cell recruitment.     

Interferon gamma regulates antigen-induced eosinophil recruitment into the mouse airways by inhibiting the infiltration of CD4+ T cells

We have previously shown that antigen-induced eosinophil recruitment into the tissue of sensitized mice is mediated by CD4+ T cells and interleukin 5. To determine whether interferon gamma (IFN-gamma) regulates antigen-induced eosinophil recruitment into the tissue, we studied the effect of recombinant (r) murine IFN-gamma and of anti-IFN- gamma monoclonal antibody (mAb) on the eosinophil infiltration of the trachea induced by antigen inhalation in mice. The intraperitoneal administration of rIFN-gamma prevented antigen-induced eosinophil infiltration in the trachea of sensitized mice. The administration of rIFN-gamma also decreased antigen-induced CD4+ T cell but not CD8+ T cell infiltration in the trachea. On the other hand, pretreatment with anti-IFN-gamma mAb enhanced antigen-induced eosinophil and CD4+ T cell infiltration in the trachea. These results indicate that IFN-gamma regulates antigen-induced eosinophil recruitment into the tissue by inhibiting CD4+ T cell infiltration.     

Interleukin-10 inhibits antigen-induced cellular recruitment into the airways of sensitized mice.

This report examines the effect of recombinant murine (rm) IL-10 on antigen-induced cellular recruitment into the airways of sensitized Balb/c mice. The intranasal instillation of 10 micrograms ovalbumin induced an early (6-24 h) increase in the number of neutrophils, and a late rise (24-96 h) in that of eosinophils in the bronchoalveolar lavage (BAL) fluid and bronchial tissue. A single intranasal instillation of 0.01-0.1 microgram of rmIL-10, administered concurrently with ovalbumin, but not 1 or 3 h thereafter, dose-dependently inhibited both airway neutrophilia and eosinophilia. This phenomenon was suppressed by treating the sensitized mice with 1 mg/mouse of a neutralizing anti-IL-10 mAb, which increased significantly ovalbumin-induced neutrophil and eosinophil accumulation in the BAL fluid. These results suggest that antigen stimulation may trigger the in vivo generation of IL-10, which, in turn, participates in the leukocyte infiltration into the airways. rmIL-10 also reduced TNF-alpha release in the BAL fluid observed 1 and 3 h after antigen challenge. Furthermore, the intranasal instillation of an anti-TNF-alpha antiserum to sensitized mice markedly reduced ovalbumin-induced neutrophil and eosinophil accumulation in the BAL fluid. These findings indicate that leukocyte infiltration into the airways of antigen-challenged mice is regulated by IL-10. Furthermore, inhibition of TNF-alpha production by rmIL-10 suggests that allergic airway inflammation and TNF-alpha formation are parallel events in this model.     

A monoclonal antibody recognizing very late activation antigen-4 inhibits eosinophil accumulation in vivo

Using an in vivo test system, the role of the beta 1 integrin very late activation antigen-4 (VLA-4) in eosinophil accumulation in allergic and nonallergic inflammatory reactions was investigated. Eosinophil infiltration and edema formation were measured as the local accumulation of intravenously injected 111In-labeled eosinophils and 125I-human serum albumin. The inflammatory reactions investigated were a passive cutaneous anaphylaxis (PCA) reaction and responses elicited by intradermal soluble inflammatory mediators (platelet-activating factor, leukotriene B4, C5a des Arg), arachidonic acid, and zymosan particles. The in vitro pretreatment of 111In-eosinophils with the anti- VLA-4 monoclonal antibody (mAb) HP1/2, which crossreacts with guinea pig eosinophils, suppressed eosinophil accumulation in all the inflammatory reactions investigated. Eosinophil accumulation was inhibited to the same extent when mAb HP1/2 was administered intravenously. It is interesting that HP1/2 had no effect on stimulated edema formation. These results suggest a role for VLA-4 in eosinophil accumulation in vivo and indicate a dissociation between the inflammatory events of eosinophil accumulation and edema formation.     

Central role of immunoglobulin (Ig) E in the induction of lung eosinophil infiltration and T helper 2 cell cytokine production: inhibition by a non-anaphylactogenic anti-IgE antibody

Elevated levels of immunoglobulin (Ig) E are associated with bronchial asthma, a disease characterized by eosinophilic inflammation of the airways. Activation of antigen-specific T helper (Th) 2 cells in the lung with the subsequent release of interleukin (IL) 4 and IL-5 is believed to play an important role in the pathogenesis of this disease. In this study, we have used a non-anaphylactogenic anti-mouse-IgE antibody to investigate the relationship between IgE, airway eosinophil infiltration, and the production of Th2 cytokines. Immunization of mice with house dust mite antigen increased serum levels of IgE and IgG. Antigen challenge of immunized but not control mice induced an infiltration of eosinophils in the bronchoalveolar lavage associated with the production of IL-4 and IL-5 from lung purified Thy1.2+ cells activated through the CD3-T cell receptor complex. Administration of the anti-IgE monoclonal antibody (mAb) 6h before antigen challenge neutralized serum IgE but not IgG and inhibited the recruitment of eosinophils into the lungs and the production of IL-4 and IL-5 but not interferon gamma. Studies performed using an anti-CD23 mAb, CD23 deficient and mast cell deficient mice suggest that anti-IgE mAb suppresses eosinophil infiltration and Th2 cytokine production by inhibiting IgE-CD23-facilitated antigen presentation to T cells. Our results demonstrate that IgE-dependent mechanisms are important in the induction of a Th2 immune response and the subsequent infiltration of eosinophils into the airways. Neutralization of IgE, for example, non- anaphylactogenic anti-IgE mAbs may provide a novel therapeutic approach to the treatment of allergic airway disease.     

Antiasthmatic effect of YM976, a novel PDE4 inhibitor, in guinea pigs

YM976 is a novel and specific phosphodiesterase 4 inhibitor. In our previous report, we indicated that YM976 has less emetogenicity, a major adverse effect of PDE4 inhibitors, than rolipram. In the present study, we examined the antiasthmatic effects of YM976 in guinea pigs. YM976 orally administered exhibited inhibition of antigen-induced bronchoconstriction, airway plasma leakage, airway eosinophil infiltration, and airway hyperreactivity (AHR), with ED(50) values of 7.3, 5.7, 1.0, and 0.52 mg/kg, respectively. Rolipram also dose dependently suppressed these responses. Prednisolone suppressed eosinophil infiltration and AHR, whereas it failed to inhibit bronchoconstriction and plasma leakage. Theophylline moderately suppressed bronchoconstriction and edema, but neither eosinophil infiltration nor AHR. YM976 suppressed the peroxidase activity in the bronchoalveolar lavage fluid, and elevated the intracellular peroxidase activity and cAMP contents of infiltrated cells, suggesting that YM976 inhibited not only the infiltration but also the activation of leukocytes. In vitro studies revealed that YM976 potently suppressed eosinophil activation (EC(30) = 83 nM), and exerted a little relaxation on LTD(4)-precontracted tracheal smooth muscle (EC(50) = 370 nM). Rolipram exhibited a potent tracheal relaxation activity (EC(50) = 50 nM). In vivo studies indicated that the inhibitory effect of YM976 on LTD(4)-induced bronchospasm was marginal even at 30 mg/kg p.o., although rolipram significantly inhibited the bronchospasm at the same dose. These results suggested that YM976, unlike rolipram, showed the inhibition of antigen-induced airway responses due to anti-inflammatory effects, but not to direct tracheal relaxation. In conclusion, YM976 may have potential therapeutic value in the treatment of asthma through its anti-inflammatory activities.     

Failure of aerosolized endothelin (ET-1) to induce bronchial hyperreactivity in the guinea pig

Aerosol administration of endothelin (ET-1) has been shown to provoke a potent bronchoconstriction in the guinea pig. We investigated whether or not, aerosolized ET-1 induces a bronchial hyperreactivity in the guinea pig. Aerosolized ET-1 (10 micrograms/ml for 60 min) did not alter the dose-response curve, established by successive aerosol administration of acetylcholine (ACh) 3-4 h and 18-24 h after challenge with the peptide. In a second protocol, aerosolized ET-1 (10 micrograms/ml for 3 min) induced, in anaesthetized guinea pigs a bronchopulmonary response but did not alter the dose-response curve to aerosolized ACh established 30 min after the challenge. These results suggest that ET-1 may participate to the early, but not the late alteration of the bronchopulmonary tone observed during pathophysiological conditions.     

A role for CD44 in an antigen-induced murine model of pulmonary eosinophilia

Previous studies established that IL-5-producing CD4(+) T cells play a pivotal role in allergic respiratory inflammation. It was also reported that CD4(+) T cells express higher levels of CD44 in the airway than in peripheral blood of patients with allergic respiratory diseases. We have used experimental pulmonary eosinophilia induced in mice by Ascaris suum (Asc) extract to investigate the role of CD44 in the development of allergic respiratory inflammation. Intraperitoneal administration of anti-CD44 mAb prevented both lymphocyte and eosinophil accumulation in the lung. Anti-CD44 mAb also blocked antigen-induced elevation of Th2 cytokines as well as chemokines (CCL11, CCL17) in bronchoalveolar lavage fluid (BALF). Treatment with anti-CD44 mAb inhibited the increased levels of hyaluronic acid (HA) and leukotriene concentrations in BALF that typically result from antigen challenge. Anti-CD44 mAb also blocked antigen-induced airway hyperresponsiveness. An anti-CD44 mAb (IM7) inhibited the HA-binding ability of splenocytes associated with decreased levels of CD44. Soluble CD44 levels in serum were increased in Asc-challenged IM7-treated mice, but not in KM201-treated mice, compared with Asc-challenged rat IgG-treated mice. Ab's that block CD44-HA binding reduced allergic respiratory inflammation by preventing lymphocyte and eosinophil accumulation in the lung. Thus, CD44 may be critical for development of allergic respiratory inflammation.     

Is the guinea pig trachea a good in vitro model of human large and central airways? Comparison on leukotriene-, methacholine-, histamine- and antigen-induced contractions

To analyze comprehensively the relevance of the guinea pig trachea as a model of human large and central airways, the contractile effects of the peptidoleukotrienes (LTs), histamine, methacholine and antigen on guinea pig and human airways were compared in vitro. Although some differences were apparent, LTC4, LTD4, LTE4, histamine and methacholine had comparable EC50 values and elicited similar maximal responses in both guinea pig trachea and human bronchus (second-seventh generation). In the presence of l-serine borate (45 mM), LTC4 concentration-response curves were shifted significantly to the left in guinea pig trachea but not in human bronchus. Furthermore, the LT receptor antagonists (SK&F 102922 and FPL 55712) had similar potencies against LTC4- and LTD4-induced contractions of human bronchus, whereas, in the guinea pig trachea, they were much more effective antagonists of responses produced by LTD4 than those elicited by LTC4. These results provide further evidence that, unlike in human bronchus, LTC4- and LTD4-induced contractions in the guinea pig trachea are mediated via distinct leukotriene receptors. Ovalbumin-induced contractions of actively sensitized guinea pig tracheae exhibited the same profile as anti-immunoglobulin E-induced contractions of the passively sensitized human bronchus. Furthermore, antigen-induced contractions in both the guinea pig trachea and human bronchus possessed a similar sensitivity to inhibition by mepyramine (10 microM) and the LT antagonists (10 microM), added either alone or in combination. These results indicate that the isolated guinea pig trachea is a suitable model of human large and central airways.     

Costimulation through B7-2 (CD86) Is Required for the Induction of a Lung Mucosal T Helper Cell 2 (TH2) Immune Response and Altered Airway Responsiveness

The recruitment of eosinophils into the airways after allergen exposure is dependent on interleukin (IL) 5 secreted from antigen-specific CD4⁺ T cells of the T helper cell (Th) 2 subset. However, while it is established that costimulation through CD28 is required for TCR-mediated activation and IL-2 production, the importance of this mechanism for the induction of a Th2 immune response is less clear. In the present study, we administered the fusion protein CTLA-4 immunoglobulin (Ig) into the lungs before allergen provocation to determine whether CD28/CTLA-4 ligands are required for allergen-induced eosinophil accumulation and the production of Th2 cytokines. Administration of CTLA-4 Ig inhibited the recruitment of eosinophils into the lungs by 75% and suppressed IgE in the bronchoalveolar lavage fluid. CTLA-4 Ig also inhibited the production of IL-4, IL-5, and IL-10 by 70–80% and enhanced interferon-γ production from CD3–T cell receptor–activated lung Thy1.2+ cells. Allergen exposure upregulated expression of B7-2, but not B7-1, on B cells from the lung within 24 h. Moreover, airway administration of an anti-B7-2 monoclonal antibody (mAb) inhibited eosinophil infiltration, IgE production, and Th2 cytokine secretion comparable in magnitude to that observed with CTLA-4 Ig. Treatment with an anti-B7-1 mAb had a small, but significant effect on eosinophil accumulation, although was less effective in inhibiting Th2 cytokine production. The anti-B7-2, but not anti-B7-1, mAb also inhibited antigen-induced airway hyperresponsiveness in vivo. In all of the parameters assessed, the combination of both the anti-B7-1 and anti-B7-2 mAb was no more effective than anti-B7-2 mAb treatment alone. We propose that strategies aimed at inhibition of CD28 interactions with B7-2 molecules may represent a novel therapeutic target for the treatment of lung mucosal allergic inflammation.     

Alpha 4-integrins mediate antigen-induced late bronchial responses and prolonged airway hyperresponsiveness in sheep.

Eosinophils and T lymphocytes are thought to be involved in allergic airway inflammation. Both cells express the alpha 4 beta 1-integrin, very late antigen-4 (VLA-4, CD49d/CD29); alpha 4-integrins can promote cellular adhesion and activation. Therefore, we examined the in vivo effects of a blocking anti-alpha 4 monoclonal antibody, HP 1/2, on antigen-induced early and late bronchial responses, airway hyperresponsiveness, inflammatory cell influx, and peripheral leukocyte counts in allergic sheep. Sheep blood lymphocytes, monocytes, and eosinophils expressed alpha 4 and bound HP 1/2. In control sheep, Ascaris antigen challenge produced early and late increases in specific lung resistance of 380 +/- 42% and 175 +/- 16% over baseline immediately and 7 h after challenge, respectively, as well as airway hyperresponsiveness continuing for 14 d after antigen challenge. Treatment with HP 1/2 (1 mg/kg, i.v.) 30 min before antigen challenge did not affect the early increase in specific lung resistance but inhibited the late-phase increase at 5-8 h by 75% (P < 0.05) and inhibited the post-antigen-induced airway hyperresponsiveness at 1, 2, 7, and 14 d (P < 0.05, for each time). Intravenous HP 1/2 given 2 h after antigen challenge likewise blocked late-phase airway changes and postchallenge airway hyperresponsiveness. Airway administration of HP 1/2 (16-mg dose) was also effective in blocking these antigen-induced changes. Response to HP 1/2 was specific since an isotypic monoclonal antibody, 1E6, was ineffective by intravenous and aerosol administration. Inhibition of leukocyte recruitment did not totally account for the activity of anti-alpha 4 antibody since HP 1/2 neither diminished the eosinopenia or lymphopenia that followed antigen challenge nor consistently altered the composition of leukocytes recovered by bronchoalveolar lavage. Because airway administration of HP 1/2 was also active, HP 1/2 may have inhibited cell activation. Reduction of platelet-activating factor-induced eosinophil peroxidase release from HP 1/2-treated eosinophils supports such a mechanism. These findings indicate a role for alpha 4-integrins in processes that lead to airway late phase responses and persisting airway hyperresponsiveness after antigen challenge.     

T lymphocytes adhere to airway smooth muscle cells via integrins and CD44 and induce smooth muscle cell DNA synthesis

Asthma is a disease of airway inflammation and hyperreactivity that is associated with a lymphocytic infiltrate in the bronchial submucosa. The interactions between infiltrating T lymphocytes with cellular and extracellular matrix components of the airway and the consequences of these interactions have not been defined. We demonstrate the constitutive expression of CD44 on human airway smooth muscle (ASM) cells in culture as well as in human bronchial tissue transplanted into severe combined immunodeficient mice. In contrast, basal levels of intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) expression are minimal but are induced on ASM by inflammatory mediators such as tumor necrosis factor alpha (TNF-alpha). Activated, but not resting T cells, adhere to cultured ASM; stimulation of the ASM with TNF-alpha enhanced this adhesion. Adhesion was partially blocked by monoclonal antibodies (mAb) specific for lymphocyte function-associated antigen 1 (LFA-1) and very late antigen 4 (VLA-4) on T cells and ICAM-1 and VCAM-1 on ASM cells. The observed integrin-independent adhesion was mediated by CD44/hyaluronate interactions as it was inhibited by anti-CD44 mAb 5F12 and by hyaluronidase. Furthermore, the adhesion of activated T lymphocytes induced DNA synthesis in growth-arrested ASM cells. Thus, the interaction between T cells and ASM may provide insight into the mechanisms that induce bronchial inflammation and possibly ASM cell hyperplasia seen in asthma.     

Interleukin 4, but not interleukin 5 or eosinophils, is required in a murine model of acute airway hyperreactivity [published erratum appears in J Exp Med 1997 May 5;185(9):1715]

Reversible airway hyperreactivity underlies the pathophysiology of asthma, yet the precise mediators of the response remain unclear. Human studies have correlated aberrant activation of T helper (Th) 2-like effector systems in the airways with disease. A murine model of airway hyperreactivity in response to acetylcholine was established using mice immunized with ovalbumin and challenged with aerosolized antigen. No airway hyperractivity occurred in severe combined immunodeficient mice. Identically immunized BALB/c mice developed an influx of cells, with a predominance of eosinophils and CD4+ T cells, into the lungs and bronchoalveolar lavage fluid at the time that substantial changes in airway pressure and resistance were quantitated. Challenged animals developed marked increases in Th2 cytokine production, eosinophil influx, and serum immunoglobulin E levels. Neutralization of interleukin (IL) 4 using monoclonal antibodies administered during the period of systemic immunization abrogated airway hyperractivity but had little effect on the influx of eosinophils. Administration of anti-IL-4 only during the period of the aerosol challenge did not affect the subsequent response to acetylcholine. Finally, administration of anti- IL-5 antibodies at levels that suppressed eosinophils to < 1% of recruited cells had no effect on the subsequent airway responses. BALB/c mice had significantly greater airway responses than C57BL/6 mice, consistent with enhanced IL-4 responses to antigen in BALB/c mice. Taken together, these data implicate IL-4 generated during the period of lymphocyte priming with antigen in establishing the cascade of responses required to generate airway hyperractivity to inhaled antigen. No role for IL-5 or eosinophils could be demonstrated.     

中药对哮喘豚鼠嗜酸粒细胞凋亡与自由基的影响

目的：探讨中药对哮喘豚鼠嗜酸粒细胞（EOS）凋亡与自由基在气道炎症中的作用。方法：采用卵蛋白致敏激发豚鼠哮喘,观察中药对哮喘豚鼠血浆丙二醛（MDA）、全血谷胱甘肽过氧化物酶（GSH－Px)及红细胞超氧化物歧化酶（SOD）含量的影响,计算支气管肺泡灌洗液（BALF）中不同密度嗜酸性粒细胞凋亡百分比。结果：中药能提高哮喘豚鼠全血GSH－Px和红细胞SOD的含量,降低MDA的含量,促进EOS凋亡。结论：中药能够有效地清除自由基,促进EOS凋亡,减轻气道炎症引起的气道高反应。     

Effects of nedocromil sodium on antigen-induced conjunctivitis in guinea pigs

We evaluated nedocromil sodium in a guinea pig model of allergic conjunctivitis. Ten days after the animals were passively sensitized to ovalbumin, nedocromil sodium (2 mg) or normal saline was instilled into the conjunctival sac, followed by antigen challenge with ovalbumin (100 μg or 300 μg/10 μL). Conjunctival hyperemia, edema, and eyelid edema were evaluated at 10 minutes and 4 hours in the 100-μg ovalbumin group. Eyes with nedocromil sodium exhibited fewer early and late clinical signs of allergic conjunctivitis than control eyes. Infiltrating eosinophils were counted at 24 hours in the 300-μg ovalbumin group. Nedocromil sodium inhibited antigen-induced eosinophil infiltration into the limbus, fornix, and eyelids by 77%, 66%, and 74%, compared with controls. Nedocromil sodium can effectively suppress early- and late-phase conjunctival hyperemia, conjunctival edema, eyelid edema, and eosinophil infiltration in the guinea pig passive-sensitization model. Nedocromil sodium may represent a versatile option for the treatment of allergic conjunctivitis.     

Effects of carbocysteine on antigen-induced increases in cough sensitivity and bronchial responsiveness in guinea pigs

Carbocysteine is a mucoactive drug and is being used for both acute and chronic infectious airway diseases. Although carbocysteine can repair the damage of epithelial cells caused by exposure to various agents, the effects of this agent on allergic airway diseases such as asthma and eosinophilic bronchitis with an isolated chronic cough, in both of which epithelial damage may be characteristic, is not clear. We investigated the effects of carbocysteine on antigen-induced cough hypersensitivity to inhaled capsaicin at 48 h and bronchial hyperresponsiveness to inhaled methacholine at 72 h after challenge with an aerosolized antigen in actively sensitized guinea pigs. After measuring bronchial responsiveness, we examined neutral endopeptidase (NEP) activity in the tracheal tissue. Carbocysteine (10, 30, or 100 mg/kg) was given intraperitoneally every 12 h for 3 days after antigen challenge. The number of coughs elicited by an aerosol of capsaicin (10(-4) M) was significantly (p < 0.01) decreased in carbocysteine groups (6.13 +/- 0.59 at 10 mg/kg, 4.88 +/- 0.67 at 30 mg/kg, and 4.50 +/- 0.33 at 100 mg/kg during 3 min measurement) compared with the control group (9.75 +/- 0.53). Furthermore, carbocysteine dose dependently repaired the antigen-induced decrease of NEP activity in the tracheal tissue, but it did not influence the bronchial hyperresponsiveness or bronchoalveolar lavage cell component. These findings suggest that carbocysteine promotes the repair of damaged epithelium by allergic reaction and may be useful in allergic airway diseases accompanied by isolated chronic coughing, especially eosinophilic bronchitis without asthma and tracheobronchitis with cough hypersensitivity.     

咪喹莫特治疗支气管哮喘的动物实验研究

目的 :研究咪喹莫特治疗支气管哮喘的疗效及可能的机制。方法 :建立豚鼠哮喘模型 ,随机分为 :①对照组 (哮喘组 ) ;②咪喹莫特吸入组 ;③咪喹莫特灌胃组 ;④咪喹莫特外用组 ;⑤安慰剂组。治疗 2周后 ,支气管肺泡灌洗液 (BALF)及肺组织 ,分别测定外周血IgE ,支气管肺泡灌洗液 (BALF)细胞计数、分类 ,计数肺组织切片 0 1～ 0 3mm范围的支气管壁嗜酸性粒细胞 (EOS)、淋巴细胞 (L)数。结果 :咪喹莫特治疗组外周血IgE值 ,BALF细胞计数、EOS分类及 0 1～ 0 3mm支气管周围EOS计数、L计数与对照组间或安慰剂组间有统计学意义 (P <0 0 5 ) ,而BALFL分类百分比 ,治疗组与对照组间或安慰剂组间无统计学意义。咪喹莫特治疗组间IgE值、BALF计数、EOS分类、支气管旁EOS计数、L计数方差分析均有统计学意义。 结论 :咪喹莫特能显著减轻支气管肺周围的炎性细胞的浸润 (主要表现为下调EOS与L数、EOS百分率和IgE)。咪喹莫特吸入可能是治疗支气管哮喘的一种新方法。     

Inhibition of nitric-oxide synthase enhances antigen-induced contractions and increases release of cysteinyl-leukotrienes in guinea pig lung parenchyma: nitric oxide as a protective factor

Nitric oxide (NO) in exhaled air is a biomarker of airway inflammation. However, the role of NO in the peripheral lung is not known. The aim of this study was to determine the role of endogenous NO in antigen-induced contractions of ovalbumin (OVA)-sensitized guinea pig lung parenchyma (GPLP). The contraction in this in vitro model of the peripheral lung closely resembles the corresponding response in human airways. Cumulatively increasing concentrations (10-10,000 microg/l) of OVA induced concentration-dependent contractions of the GPLP that were enhanced by the NO synthase (NOS) inhibitors N(omega)-nitro-L-arginine (L-NOARG; 100 microM), N(omega)-monomethyl-L-arginine (100 microM), N(omega)-nitro-L-arginine methyl ester (100 microM), and N-(3-(aminomethyl)benzyl)acetamidine (1400W; 1 microM). The enhancement induced by L-NOARG was reversed by coadministration with the 5-lipoxygenase inhibitor (R)-2-[4-(quinolin-2-yl-methoxy)phenyl]-2-cyclopentyl acetic acid (BAY x1005; 3 microM), whereas coadministration of L-NOARG with the cyclooxygenase inhibitor indomethacin (10 microM) did not change the effect of L-NOARG alone. L-NOARG (100 microM) did not affect the cumulative concentration-response relations for either leukotriene (LT) D4 (0.1-100 nM) or histamine (1-30 microM). The NO donor NONOate (0.001-100 microM) was ineffective in GPLP but potently relaxed precontracted guinea pig pulmonary artery. Furthermore, L-NOARG enhanced the release of LTE4 and decreased the release of prostaglandin E2 induced by OVA. In conclusion, endogenous NO exerts an inhibitory effect on antigen-induced contractions in the peripheral lung. The action of NO apparently involves inhibition of the release of mediators rather than direct relaxation of airway smooth muscle. The findings support the belief that endogenous NO has a protective anti-inflammatory effect in the airways.