Bronchial Hyperresponsiveness In Mice Research Articles

Particulate matter 2.5 triggers airway inflammation and bronchial hyperresponsiveness in mice by activating the SIRT2-p65 pathway.

Exposure to particulate matter 2.5 (PM2.5) potentially triggers airway inflammation by activating nuclear factor-κB (NF-κB). Sirtuin 2 (SIRT2) is a key modulator in inflammation. However, the function and specific mechanisms of SIRT2 in PM2.5-induced airway inflammation are largely understudied. Therefore, this work investigated the mechanisms of SIRT2 in regulating the phosphorylation and acetylation of p65 influenced by PM2.5-induced airway inflammation and bronchial hyperresponsiveness. Results revealed that PM2.5 exposure lowered the expression and activity of SIRT2 in bronchial tissues. Subsequently, SIRT2 impairment promoted the phosphorylation and acetylation of p65 and activated the NF-κB signaling pathway. The activation of p65 triggered airway inflammation, increment of mucus secretion by goblet cells, and acceleration of tracheal stenosis. Meanwhile, p65 phosphorylation and acetylation, airway inflammation, and bronchial hyperresponsiveness were deteriorated in SIRT2 knockout mice exposed to PM2.5. Triptolide (a specific p65 inhibitor) reversed p65 activation and ameliorated PM2.5-induced airway inflammation and bronchial hyperresponsiveness. Our findings provide novel insights into the molecular mechanisms underlying the toxicity of PM2.5 exposure. Triptolide inhibition of p65 phosphorylation and acetylation could be an effective therapeutic approach in averting PM2.5-induced airway inflammation and bronchial hyperresponsiveness.

Th9 cells induce steroid-resistant bronchial hyperresponsiveness in mice

BackgroundReduced responsiveness to corticosteroid therapy is a major problem for patients with severe asthma. Although Th9 cells, along with Th2 cells, facilitate antigen-induced airway eosinophilia and bronchial hyperresponsiveness (BHR), the sensitivity of Th9 cell-mediated responses to steroid therapy remains unknown. In this study, we investigated the effect of dexamethasone (Dex) on antigen-induced airway inflammation in Th9 cell-transferred mice. MethodsOvalbumin (OVA)-specific Th2 and Th9 cells were polarized from the CD4+ T cells of DO11.10/RAG-2−/− mice. BALB/c mice were adoptively transferred with Th2 or Th9 cells and challenged with OVA. Dex treatment was performed twice, at 1 h before and at 24 h after the OVA challenge. Following treatment, the number of inflammatory cells in the bronchoalveolar lavage fluid and the bronchial responsiveness to inhaled methacholine were determined. ResultsIn both the Th2 and Th9 cell-transferred mice, substantial accumulation of eosinophils in the lungs and BHR were induced by challenge with the specific antigen. In the Th2 cell-transferred mice, these responses were significantly diminished by Dex treatment. In contrast, neither cellular infiltration nor BHR was affected by Dex treatment in the Th9 cell-transferred mice, although the Th9 cells substantially expressed glucocorticoid receptor α. Accordingly, antigen-induced interleukin-9 expression in the Th9 cells was attenuated by Dex treatment at least in vitro. Antigen-induced lung infiltration of infused Th2 cells but not Th9 cells was significantly suppressed by Dex. ConclusionsIn contrast to Th2-mediated responses, Th9-mediated airway inflammation was not affected by Dex. Th9 cells might be involved in the developmental mechanisms of steroid-resistant asthma.

Mycobacterium tuberculosisChaperonin 60.1 Inhibits Leukocyte Diapedesis in a Murine Model of Allergic Lung Inflammation

Chaperonin 60.1 from Mycobacterium tuberculosis suppressed allergic lung inflammation and bronchial hyperresponsiveness in mice by a mechanism that is yet to be clarified. To investigate the possible antiinflammatory mechanism(s) of action of Cpn60.1 in a model of allergic lung inflammation, ovalbumin (OVA)-allergic mice were pretreated with Cpn60.1 intranasally 20 minutes before each OVA aerosol challenge in a total of three treatments. Readouts were performed 24 hours after last challenge. Pretreatment with Cpn60.1 (1.0-0.001 μg) significantly inhibited the number of eosinophils in bronchoalveolar lavage fluid (OVA, 49.2 ± 12.3 versus Cpn60.1 [1 μg dose], 90.4 ± 2.3 × 10(4) cells/ml) and IL-5 release (OVA, 43 ± 8.5 versus Cpn60.1 [1 μg dose], 3 ± 11 pg/ml) but increased IL-12 levels (OVA, 50 ± 24 versus Cpn60.1 [1 μg dose], 103 ± 13 pg/ml). The effect of Cpn60.1 on cell recruitment and IL-5, but not IL-12, release was abolished in TLR-4 knockout mice. Intravital microscopy demonstrated that Cpn60.1 reduced chemokine-mediated leukocyte rolling and transmigration across the vessel wall (rolling cells: eotaxin, 11.7 ± 1.1 versus Cpn60.1 [1 μg dose], 2.8 ± 1 cells in 30 s). Similarly, Cpn60.1 reduced eotaxin-induced leukocyte migration in vitro (eotaxin, 17.3 ± 3.3 versus Cpn60.1 [0.1 μg dose], 3.3 ± 0.4 cells × 10(4)/ml). Immunostaining demonstrated that Cpn60.1 inhibits VCAM-1 and increases vascular endothelial-cadherin expression in lung vascular tissue, suggesting that the antiinflammatory effect of Cpn60.1 is partly mediated by altering the expression of adhesion molecules. This study shows that Cpn60.1 inhibits leukocyte diapedesis by a TLR-4 and an adhesion molecule-dependent mechanism in allergic inflammation in mice.

Selective Nasal Allergen Provocation Induces Substance P–Mediated Bronchial Hyperresponsiveness

Although the concept of "global airway allergy" has become widely accepted during recent years, nasobronchial interaction and its mechanisms remain incompletely understood. The experimental study of the effect of nasal allergen deposition on lower airway pathology is hampered by the difficulty of avoiding lower airway penetration of the allergens. In ovalbumin-sensitized mice with experimental airway allergy, nasal allergen provocations were performed after complete anatomical separation of upper and lower airways by means of a tracheotomy. A canula was inserted in the trachea, and the trachea was ligated, thus inhibiting any passage of allergens from upper to lower airways. Mice showed bronchial hyperresponsiveness to methacholine as early as 4 hours after nasal allergen provocation in the absence of recruitment of inflammatory cells. An increased substance P (SP) concentration in the bronchial lumen was found, as well as an increased number of SP-positive pulmonary nerves. Treatment with a neurokinin (NK) 1 receptor antagonist abolished the allergen-induced bronchial hyperresponsiveness. Moreover, endobronchial administration of SP caused NK1 receptor-dependent bronchial hyperresponsiveness in mice with airway allergy. Nasal allergen provocation rapidly induces bronchial hyperresponsiveness via pulmonary up-regulation of SP and activation of NK1 receptors.

Acute Influenza A infection induces bronchial hyper-responsiveness in mice

This study aimed to determine whether the route of administration of methacholine (MCh) influenced the pattern of airway hyper-responsiveness (AHR) in mice. BALB/c mice were inoculated with a 50-microL volume containing 10(4.5)-pfu Influenza virus A/Mem/1/71(H3N1) or media. MCh responsiveness in vivo [inhaled (0.01-30 mg/mL), i.v. MCh (6-48 microg/min/kg)] and in vitro were measured at day 4 post-infection (D4) during acute lower respiratory infection (LRI) and following resolution of infection at day 20 (D20) using a low-frequency, forced oscillation technique. Inflammation was assessed in bronchoalveolar lavage fluid. Infected mice had pulmonary inflammation and heightened responsiveness to both inhaled (p<0.03) and intravenous (p<0.02) MCh on D4, but not on D20. In vitro responsiveness was not altered at either time point. Influenza A LRI results in AHR during acute infection associated with a marked inflammatory response and increased permeability of the alveolar-capillary barrier. These data suggest that intrinsic muscle properties are not altered but MCh has greater access to airway smooth muscle during acute infection.

Serotonin Bronchial Hyperresponsiveness and Eosinophilic Cholangiopathy

To the Editor: The paper by Duseja et al. [1] is consistent with the assumption that TH-2 autoimmune diseases may trigger more than one physiological disorder, at different visceral levels. They reported that the patient had a history of recurrent rhinitis and cough since childhood. In addition to the above, Forbes et al. [2] found bronchial hyperresponsiveness in mice affected by eosinophil-associated gastrointesinal disease, although they could not determine which common factor(s) might be involved in this disorder, They suggest that the bronchial responsiveness they registered in experimental eosinophil-associated gastrointestinal disease was dependent on eotaxin expression in the gastrointestinal (GI) tract. In addition, they stated that bronchial hyperresponsiveness was linked to the aberrant CD4 T helper-2 lymphocyte production of interleukin 13 and the production of mucosal immunoglobulin G1 in the GI lumen. With respect to the above, we would like to offer some additional information. With respect to all of the above, we are able to report that free serotonin in the plasma (f-5HT) is the most important factor responsible for bronchoconstriction. We found a close negative correlation between FEV1 and free serotonin

T helper-2 immunity regulates bronchial hyperresponsiveness in eosinophil-associated gastrointestinal disease in mice

Background & Aims: Eosinophil-associated gastrointestinal diseases are frequently associated with extraintestinal features, including bronchopulmonary manifestations. The factors predisposing to bronchial hyperresponsiveness in eosinophil-associated gastrointestinal diseases are unknown. To elucidate the mechanistic link between eosinophil-associated gastrointestinal diseases and bronchial hyperresponsiveness, we used murine models of eosinophil-associated gastrointestinal diseases and eotaxin-1/transgene-induced eosinophil-associated gastrointestinal diseases. Methods: Mice were sensitized and orally challenged with ovalbumin-coated encapsulated particles to induce eosinophil-associated gastrointestinal disease, and bronchial responsiveness was examined. Furthermore, transgenic mice expressing eotaxin in the intestine (with the rat fatty acid-binding promoter) were used to specifically elucidate the contribution of this chemokine in eosinophil-associated gastrointestinal disease-associated bronchial hyperresponsiveness. Results: The induction of allergen-induced eosinophil-associated gastrointestinal disease was directly correlated with the development of bronchial hyperresponsiveness. The development of bronchial hyperresponsiveness in mice with allergen-induced eosinophil-associated gastrointestinal disease was dependent on eotaxin expression in the gastrointestinal tract. Expression of eotaxin in the gastrointestinal tract of transgenic mice was sufficient to promote bronchial hyperresponsiveness. Bronchial hyperresponsiveness was shown to be directly linked to the aberrant CD4 + T helper 2 lymphocyte production of interleukin-13. It is interesting to note that transgenic expression of eotaxin was linked with enhanced T helper 2 lymphocyte/cytokine synthesis (interleukin-4, -5, and -13) and the production of mucosal immunoglobulin G1 in the gastrointestinal lumen. We also showed that eotaxin treatment of CD4 + T cells enhanced interleukin-13 production in vitro. Conclusions: These studies suggest that increased expression of eotaxin in the gastrointestinal compartment can lead to increased CD4 + T cell-derived T helper 2 lymphocyte-cytokine production that drives aberrant immunophysiological responses in distant noninflamed mucosal tissue (the lung). These results provide a possible explanation for the altered lung function seen in some patients with inflammatory gastrointestinal disorders.

Bronchial hyperresponsiveness in experimental eosinophil-associated GI diseases is critically regulated by CD4 + T-cells, interleukin-13 and eotaxin

Rationale Eosinophil-associated gastrointestinal diseases (EGID) are frequently associated with extraintestinal features including bronchopulmonary manifestations. The factors predisposing to bronchial hyperresponsiveness (BHR) in EGID are unknown. To elucidate the mechanistic link between EGID and BHR we employed murine models of EGID and eotaxin-1 (eotaxin)-transgene induced EGID. Methods Mice were sensitized and orally challenged with ovalbumin coated encapsulated particles to induce EGID and bronchial responsiveness was examined. Furthermore, transgenic mice expressing eotaxin in the intestine (using the rat fatty acid-binding promoter) were used to specifically elucidate the contribution of this chemokine in EGID-associated BHR. Results We show induction of allergen-induced EGID directly correlated with the development of BHR. The development of BHR in mice with allergen-induced EGID was dependent on eotaxin expression in the GI tract. Expression of eotaxin in the gastrointestinal tract of transgenic mice was sufficient to promote BHR. BHR was shown to be directly linked to the aberrant CD4 + Th 2-type T-cell (Th 2) production of interleukin-(IL)-13. Interestingly, transgenic expression of eotaxin was linked with enhanced Th 2-cytokine synthesis (IL-4, -5 and -13) and the production of mucosal IgG 1 in the gastrointestinal lumen. We also show that eotaxin treatment of CD4 + T-cells enhances IL-13 production in vitro. Conclusions These studies suggest that elevated expression of eotaxin in the gastrointestinal compartment can lead to increased CD4 + T-cell derived Th 2-cytokine production that drives aberrant immunophysiological responses in distant non-inflamed mucosal tissue (the lung). These results provide a possible explanation for altered lung function seen in some patients with inflammatory gastrointestinal disorders.

The role of the mast cell in asthma: a reassessment

Interest in the role of the mast cell in bronchial asthma has waxed and waned over several decades, but there is now compelling evidence that mast cells make an important contribution to the pathophysiology of this disease. This review will discuss current advances in this field. Mast cells, but not T cells or eosinophils, localize within the bronchial smooth muscle bundles in patients with asthma but not in normal individuals or those with eosinophilic bronchitis. Smooth muscle mast cell density correlates significantly with indices of bronchial hyperresponsiveness, and is likely to be an important factor determining the asthmatic phenotype. Tryptase induces proliferation in human airway smooth muscle, and the recently identified transmembrane form induces the development of bronchial hyperresponsiveness in mice. IL-4 and IL-13, known mast cell products, also induce bronchial hyperresponsiveness in the mouse, in the absence of an inflammatory response. There are therefore several pathways by which the close approximation of mast cells with airway smooth muscle cells might lead to disordered smooth muscle function. Mast cells also infiltrate the airway mucous glands in patients with asthma, showing features of degranulation, and a positive correlate with the amount of mucus obstructing the airway lumen. Taken together these observations suggest that mast cells also play an important role in regulating mucous gland secretion. The development of potent and specific inhibitors of mast cell secretion, which remain active when administered long term to asthmatic airways, should offer a novel approach to the treatment of asthma.

Effects of birch pollen and traffic particulate matter on Th2 cytokines, immunoglobulin E levels and bronchial hyper-responsiveness in mice.

Health effects due to air pollution arising from motor vehicles are a major public and political concern world-wide. Epidemiological studies have shown that the manifestations of asthma are increased by air pollution in already affected individuals. To investigate the potential role of air-polluted tunnel dust (traffic particulate matter, TPM) or pure carbon core particles in the initiation and persistence of experimental allergic inflammation. BP2 mice were immunized with birch pollen alone (group B) or pollen together with TPM (group A), or with birch pollen and Al(OH)3 (group C), or with birch pollen and carbon core particles (group D). Before methacholine challenge they were challenged intranasally and thereafter bronchial hyper-reactivity (BHR) was evaluated in a whole-body plethysmograph. Levels of Th2 cytokines, fibronectin and lactate dehydrogenase (LDH) were determined, and differential counts were performed in the bronchoalveolar lavage (BAL) fluid. Sera were collected for determination of antibody titres and cytokine levels. Specific IgE titres, BHR, the number of recruited eosinophils and levels of fibronectin and LDH in BAL were increased in mice immunized and challenged with a mixture of birch pollen and TPM. However, mice immunized with birch pollen alone and challenged intranasally with pollen or a mixture of pollen and TPM demonstrated the highest levels of IL-4 and IL-5. This study highlights the importance of the exposure to a combination of particulate matters and pollen allergens, in the induction of allergic disease in the airways, and we have demonstrated that polluted tunnel dust has an effect on both the inflammatory and immunological components of experimental allergy. Immunization and challenge with carbon core particles together with birch pollen increased neither the BHR nor the specific IgE production significantly. Our results therefore strongly suggest that it is most likely to be the organic phase bound to the carbon core of the diesel exhaust particles that might have an important adjuvant effect in the induction of experimental allergy.

Nitrate and nitrite in exhaled breath condensate are derived from the lower airway

Nitrate and nitrite in exhaled breath condensate are derived from the lower airway

Effect of repeated antigen inhalation on airway inflammation and bronchial responsiveness to acetylcholine in interleukin-5 transgenic mice

Bronchial hyperresponsiveness (BHR) is a characteristic feature of bronchial asthma, yet its precise mechanism remains obscure. Human studies have demonstrated that T helper 2 cytokines, including interleukin (IL)-4 and IL-5, are involved in the development of airway inflammation and BHR. In the present study, we examined the role of IL-5 in the onset and aggravation of bronchial responsiveness to acetylcholine in two strains of IL-5 transgenic (Tg) mice, derived from the C3H/HeN and BALB/c strains. Three inhalations of antigen (ovalbumin) caused an increase in the number of eosinophils in bronchoalveolar lavage fluid (BALF) and a significant elevation in serum IgE in wild-type mice. In contrast with wild-type animals, systemic overproduction of IL-5 resulted in massive airway eosinophilia, especially around the peribronchi and perivascular regions of the tissues, after repeated antigen provocation. In C3H/HeN background IL-5 Tg mice, repeated antigen provocation did not induce BHR similar to that of wild-type mice. In contrast, antigen-induced BHR was observed in BALB/c-background mice, but there were no significant differences between the magnitude of BHR in wild-type and IL-5 Tg mice. Furthermore, antigen-induced IL-5 production in BALF was detected in both C3H/HeN and BALB/c mice and was elevated to a similar degree in both wild-type and IL-5 Tg mice. These findings suggest that systemic overproduction of IL-5 or airway eosinophilia is not, by itself, important in the development or aggravation of antigen-induced BHR in mice.

CD40L, but not CD40, is required for allergen-induced bronchial hyperresponsiveness in mice.

Asthma is characterized by immunoglobulin (Ig) E production, infiltration of the respiratory mucosa by eosinophils (EOSs) and mononuclear cells, and bronchial hyperresponsiveness (BHR). Interaction of CD40 on B cells and antigen presenting cells, with its ligand (CD40L) expressed transiently on activated T cells, is known to augment both T cell-driven inflammation and humoral immune responses, especially IgE production. Considering both the prominent role of inflammation in asthma and the association of the disease with IgE, we hypothesized that CD40-CD40L interactions would be important in pathogenesis. To test this hypothesis, we subjected wild-type (WT) mice and animals lacking either CD40 or CD40L to repeated inhalation of Aspergillus fumigatus (Af ) antigen. Af-treated WT mice displayed elevated IgE levels, bronchoalveolar lavage and pulmonary tissue eosinophilic inflammation, and BHR. IgE production was markedly suppressed in both the CD40 -/- and CD40L -/- strains. However, pulmonary inflammation did not appear to be inhibited by either of these mutations. Paradoxically, development of BHR was prevented by the lack of CD40L but not by the absence of CD40. We conclude that CD40/CD40L interactions, although critical in the induction of IgE responses to inhaled allergen, are not required for the induction of EOS-predominant inflammation. CD40L, but not CD40, is necessary for the development of allergen-induced BHR.

Allergen-induced airway inflammation and bronchial responsiveness in interleukin-5 receptor alpha chain-deficient mice.

The role of IL-5 receptor alpha chain (IL-5Ralpha) in the onset of bronchial hyperresponsiveness (BHR) to acetylcholine was investigated by testing IL-5Ralpha knockout (IL-5Ralpha KO) mice. Mice were immunized with antigen at intervals of 12 days. Starting 10 days after the secondary immunization, mice were exposed to antigen three times every fourth day. Twenty-four hours after the last antigen challenge, bronchial responsiveness to acetylcholine was measured and bronchoalveolar lavage was carried out. Twenty-four hours after the last antigen inhalation, total and differential cells counts of bronchoalveolar lavage revealed a significant increase in eosinophils and lymphocytes in ovalbumin-exposed wild-type mice. In IL-5Ralpha KO mice, there was little increase of eosinophils in bronchoalveolar lavage fluid (BALF). The production of IL-5 in BALF increased in both mice after repeated antigen challenge, and there was no significant difference between wild-type and IL-5Ralpha KO mice. Similar to the BAL study, histological sections of lung tissue from ovalbumin-exposed wild-type mice exhibited airway eosinophilic inflammation, which was attenuated by the deficiency of IL-5Ralpha chain. There was no significant difference in serum antigen-specific IgE levels between wild-type and IL-5Ralpha KO mice after immunization nor antigen inhalation. Repeated antigen provocation caused BHR to acetylcholine in wild-type mice. In contrast, no BHR was observed in IL-5Ralpha KO mice after repeated inhalation of antigen. These findings indicate that IL-5Ralpha plays an important role in the development of antigen-induced airway eosinophilia and BHR in mice.

The role of CD23 on allergen-induced IgE levels, pulmonary eosinophilia and bronchial hyperresponsiveness in mice.

The role of Immunoglobulin (Ig)E in inflammation is the subject of considerable study and a number of studies have shown conflicting evidence for its role in eosinophil recruitment and bronchial hyperresponsiveness in a number of murine models. The low affinity IgE receptor, CD23, is known to act as a negative regulator of IgE production and we have used knockout mice deficient in CD23 to investigate the role of IgE in eosinophil recruitment and bronchial hyperresponsiveness in a murine model of airway inflammation. To study the role of the low affinity FcepsilonII receptor, CD23 in IgE production, lung inflammation and bronchial hyperresponsiveness. Wild-type and CD23 knockout C57Bl/6 mice (CD23-/-) were immunized by intraperitoneal injection with ovalbumin on days 0 and 14 and challenged with aerosolized antigen on day 21 for a period of up to 1 week. Blood samples, bronchoalveolar lavage and lung tissue samples were obtained to determine serum IgE levels and inflammatory cell numbers, respectively. Furthermore, airway resistance was measured to increasing concentrations of aerosolized 5-hydroxytryptamine in order to evaluate the effect of CD23 deficiency on bronchial hyperresponsiveness to antigen challenge. Sensitization of wild-type C57Bl/6 mice to ovalbumin resulted in elevated levels of total serum IgE and ovalbumin-specific IgE, which was significantly augmented in CD23 knockout C57Bl/6 mice (CD23-/-). A significant increase in the percentage of eosinophils recovered in bronchoalveolar lavage fluid from wild-type and CD23-/- mice was observed 24 h following 3 or 7 days aerosol exposure with ovalbumin (10 mg/mL). At 3 days, the increase in the percentage of eosinophils was significantly greater in CD23-/- groups. Immunohistochemical analysis of lungs sections revealed the presence of CD3+, CD4+ and CD23+ cells in wild-type mice but a lack of immunofluorescence of CD23+ cells in CD23-/- mice. In wild-type ovalbumin-immunized mice, bronchial hyperresponsiveness to aerosolized 5-hydroxytryptamine was observed following a 3-day antigen challenge, which was significantly greater in CD23-/- ovalbumin-immunized mice. These studies demonstrate that CD23-/- mice have increased capacity to produce IgE consistent with the view of a negative feedback role for membrane-bound CD23 and under such conditions, may account for the greater numbers of eosinophils recruited to the airways and bronchial hyperresponsiveness observed following acute but not chronic antigen challenge.