Airway Responsiveness In Mice Research Articles

In vivo impact of tubulin polymerization promoting protein (Tppp) knockout to the airway inflammatory response

Microtubule dysfunction has been implicated as a mediator of inflammation in multiple diseases such as disorders of the cardiovascular and neurologic systems. Tubulin polymerization promoting protein (Tppp) facilitates microtubule elongation and regulates tubulin acetylation through inhibition of cytosolic deacetylase enzymes. Pathologic alterations in microtubule structure and dynamics have been described in cystic fibrosis (CF) and associated with inflammation, however the causality and mechanism remain unclear. Likewise, Tppp has been identified as a potential modifier of CF airway disease severity. Here we directly assess the impact of microtubule dysfunction on infection and inflammation by interrogating wild type and a Tppp knockout mouse model (Tppp − / −). Mice are challenged with a clinical isolate of Pseudomonas aeruginosa-laden agarose beads and assessed for bacterial clearance and inflammatory markers. Tppp − / − mouse model demonstrate impaired bacterial clearance and an elevated inflammatory response compared to control mice. These data are consistent with the hypothesis microtubule dysregulation is sufficient to lead to CF-like airway responses in mice.

Measurement of Airway Hyperresponsiveness in Mice.

Asthma has been the most prevalent chronic respiratory disease (Mensah et al. J Allergy Clin Immunol 142:744-748, 2018). To explore pathogenic mechanism or new treatments of asthma, mice have been utilized to model the disease. Eosinophilic airway inflammation, allergen specific-IgE, and airway hyperresponsiveness have been characteristic features of allergic asthma (Drake et al. Pulm Ther 5:103-115, 2019). In mouse models, airway hyperresponsiveness to inhaled broncho-constrictor agents such as methacholine chloride (MCh) has been a key disease marker (Alessandrini et al. Front Immunol 11:575936, 2020). A variety of systems to assess airway reactivity in mice are currently available. Here, three distinct systems are described as these have been used in many publications. In the first system, an invasive system in which mice are anesthetized and intubated followed by mechanical ventilation, lung resistance (R), dynamic compliance (C), and other respiratory parameters with MCh challenge are measured. In the second system, a noninvasive system equipped with a chamber in which mice can move freely and spontaneously breathe, changes in airways with MCh challenge are measured as enhanced pause (Penh) values. In the third system, in vitro airway smooth muscle (ASM) reactivity is monitored in an extracted mouse tracheal duct with a cholinergic agonist challenge or electrical stimulation. Each of these systems has unique features, benefits, or disadvantages.

Reduced allergic lung inflammation and airway responsiveness in mice lacking the cytoskeletal protein gelsolin.

Airway smooth muscle hyperresponsiveness associated with chronic airway inflammation leads to the typical symptoms of asthma including bronchoconstriction and wheezing. Asthma severity is associated with airway inflammation; therefore, reducing airway inflammation is an important therapeutic target. Gelsolin is an actin capping and severing protein that has been reported to be involved in modulation of the inflammatory response. Using mice genetically lacking gelsolin, we evaluated the role of gelsolin in the establishment of house dust mite (HDM) antigen-induced allergic lung inflammation. The genetic absence of gelsolin was found to be protective against HDM sensitization, resulting in reduced lung inflammation, inflammatory cytokines, and Muc5AC protein in bronchoalveolar lavage (BAL) fluid. The number of eosinophils, lymphocytes, and interstitial macrophages in the BAL were increased after HDM sensitization in wild-type mice but were attenuated in gelsolin-null mice. The observed attenuation of inflammation may be partly due to delayed migration of immune cells, because the reduced eosinophils in the BALs from gelsolin-null mice compared with controls occurred despite similar amounts of the chemoattractant eotaxin. Splenic T cells demonstrated similar proliferation rates, but ex vivo alveolar macrophage migration was delayed in gelsolin-null mice. In vivo, the reduced lung inflammation after HDM sensitization in gelsolin-null mice was associated with significantly diminished airway resistance to inhaled methacholine compared with HDM-treated wild-type mice. Our results suggest that modulation of gelsolin expression or function in selective inflammatory cell types that modulate allergic lung inflammation could be a therapeutic approach for asthma.

Airborne particulate matter from goat farm increases acute allergic airway responses in mice

Background: Inhalation exposure to biological particulate matter (BioPM) from livestock farms may provoke exacerbations in subjects suffering from allergy and asthma. The aim of this study was to use a murine model of allergic asthma to determine the effect of BioPM derived from goat farm on airway allergic responses.Methods: Fine (<2.5 μm) BioPM was collected from an indoor goat stable. Female BALB/c mice were ovalbumin (OVA) sensitized and challenged with OVA or saline as control. The OVA and saline groups were divided in sub-groups and exposed intranasally to different concentrations (0, 0.9, 3, or 9 μg) of goat farm BioPM. Bronchoalveolar lavage fluid (BALF), blood and lung tissues were collected.Results: In saline-challenged mice, goat farm BioPM induced 1) a dose-dependent increase in neutrophils in BALF and 2) production of macrophage inflammatory protein-3a. In OVA-challenged mice, BioPM induced 1) inflammatory cells in BALF, 2) OVA-specific Immunoglobulin (Ig)G1, 3) airway mucus secretion-specific gene expression. RNAseq analysis of lungs indicates that neutrophil chemotaxis and oxidation-reduction processes were the representative genomic pathways in saline and OVA-challenged mice, respectively.Conclusions: A single exposure to goat farm BioPM enhanced airway inflammation in both saline and OVA-challenged allergic mice, with neutrophilic response as Th17 disorder and eosinophilic response as Th2 disorder indicative of the severity of allergic responses. Identification of the mode of action by which farm PM interacts with airway allergic pathways will be useful to design potential therapeutic approaches.

Effect of artesunate on airway responsiveness and airway inflammation in asthmatic mice

Objective: To observe the effects of artesunate on airway responsiveness and airway inflammation in asthmatic mice. Methods: Thirty female BALB/c mice aged 6-8 weeks were randomly divided into control group, asthma group and artesunate group. In the asthma group and the artesunate group, the mice were sensitized by intraperitoneal injection of 20 μg of ovalbumin (OVA) and 0.2 ml of aluminum hydroxide suspension (2 mg) on day 0 and 14, respectively, and 1% OVA 10 ml dissolved in sterile phosphate (PBS) buffer was aerosolized for 30 min from the 21st to 28th day. The control group was sensitized with 0.2 ml of 2 mg suspension of aluminum hydroxide on day 0 and 14, and aerosolized by 10 ml of sterile PBS from the 21st to 28th day. Before the challenge, the artesunate group was intraperitoneally injected with 0.2 ml of artesunate. Artesunate was replaced with the same amount of normal saline in the control group and the asthma group. The mice were treated after 24 hours of last stimulation. The airway responsiveness of mice was measured by airway intubation and the changes of airway resistance and compliance were observed. Bronchoalveolar lavage fluid (BALF) was classified by cytology, and pathological changes of left lung tissue were observed and scored. Results: The airway resistance of the three groups increased and the lung compliance decreased with the increase of methacholine (Ach) concentration. The airway resistance and lung compliance of the three groups were different under the same concentration (P<0.05). The airway resistance of the artesunate group at Ach 6.25, 12.5, 25, 50, 100 mg/ml was lower than that of the asthma group at the same concentration [(1.01±0.48) vs (1.30±0.22), (1.06±0.44) vs (1.70±0.31), (1.30±0.64) vs (2.66±0.79), (1.82±0.55) vs (3.38±1.35), (2.49±0.85) vs (4.07±1.34) cmH(2)O·s(-1)·ml(-1)(1 cmH(2)O=0.098 kPa); t=3.862, 7.376, 9.113, 7.051, 6.685, all P<0.05]; the degree of lung compliance decrease at the concentration of Ach 3.125, 6.25, 12.5, 25, 50, 100 mg/ml was lower than that of the asthma group at the same concentration [(3.89±0.55)×10(-2) vs (3.07±0.63)×10(-2), (3.61±0.52)×10(-2) vs (3.04±0.58)×10(-2), (3.48±0.38)×10(-2) vs (2.78±0.57)×10(-2), (3.09±0.52)×10(-2) vs (1.73±0.62)×10(-2), (2.32±0.60)×10(-2) vs (1.29±0.54)×10(-2), (1.87±0.59)×10(-2) vs (1.15±0.44)×10(-2) ml/cmH(2)O; t=-6.295, -4.921, -6.533, -11.135, -8.48, -6.319, all P<0.05]. The proportion of eosinophils in artesunate group in BALF was significantly lower than that in asthma group [(16.63±8.58)% vs (40.44±12.94)%; t=4.336, P<0.05]. In the asthma group, the inflammatory cells infiltration of the bronchi and the perivascular area, the bronchial epithelial edema and degeneration can be observed, and the artesunate could reduce the infiltration of inflammatory cells around the bronchus and blood vessels, and the mucus secretion was also reduced in the artesunate group. Conclusion: Artesunate can improve airway hyperresponsiveness and airway inflammation in asthmatic mice and has a certain therapeutic effect on asthma.

Dose dependency PM2.5 aggravated airway inflammation in asthmatic mice via down-regulating expression of ITGB4.

We aimed to investigate whether PM2.5 has the potential to exacerbate neutrophil airway inflammation and to analyze the underlying mechanisms. The high-volume air sampler (Laoying 2033B, Qingdao, China) was used to collect PM2.5 from January 01, 2016 to December 21, 2016 in Yantai, Shandong Province, China. BALB/c mice were divided into the following four groups: control group, ovalbumin (OVA) group, low-dose PM2.5 group and high-dose PM2.5 group. Mice except for control group were sensitized and challenged by OVA, and those in low-dose PM2.5 group and high-dose PM2.5 group were intranasally administered by PM2.5 suspension. Airway responsiveness of mice was measured. Enzyme-linked immunosorbent assay (ELISA) kit was used to evaluate the expressions of interleukin 17 (IL-17) and tumor necrosis factor-α (TNF-α) in bronchoalveolar lavage fluid (BALF) and serum samples. Cell counting in BALF and histological examination were measured to explore PM2.5-induced airway inflammation. Protein expression of Integrin β4 (ITGB4) was assessed by Western blot. Airway hyperresponsiveness (AHR) exacerbated in PM2.5 exposed asthmatic mice in progressively increased doses of acetylcholine chloride (ACH). Levels of IL-17 and TNF-αin BALF and serum increased significantly in PM2.5 groups compared with other groups with significant differences between two PM2.5 groups. PM2.5 exposure exacerbated inflammatory cell infiltration and mucus secretion in airways of asthmatic mice. Percentage of neutrophils in PM2.5 groups was significantly higher in dose-dependent manner. OVA and PM2.5 co-exposure inhibited the expression of ITGB4. In particular, ITGB4 expression in mice of high-dose PM2.5 group was significantly lowered than the low-dose PM2.5 group. We showed that PM2.5 exposure exacerbates neutrophil airway inflammation in asthmatic mice though up-regulating expressions of IL-17 and TNF-α but down-regulating the expression of ITGB4.

Sulforaphane ameliorates steroid insensitivity through an Nrf2-dependent pathway in cigarette smoke-exposed asthmatic mice

Oxidative stress induced by cigarette smoke and other environmental pollutants contributes to refractory asthma. To better understand the role of smoking in asthma, we investigated the effects of cigarette smoke on allergic airway responses in mice and examined expression of nuclear factor-E2-related factor-2 (Nrf2) and its downstream factors, because Nrf2 is known to play a pivotal role in antioxidant responses. OVA-sensitized and challenged BALB/c mice were exposed to cigarette smoke and then treated with dexamethasone, sulforaphane (an activator of Nrf2), or their combination. Upon exposure to cigarette smoke, Nrf2 and associated transcripts were upregulated in response to oxidative stress, and asthmatic responses were steroid resistant. In OVA-sensitized and challenged mice exposed to cigarette smoke and treated with sulforaphane, Nrf2-mediated antioxidant responses were upregulated to a greater extent, and steroid sensitivity of asthmatic responses was restored. Moreover, the expression and activity of histone deacetylase 2 (HDAC2), a key regulator of steroid responsiveness, was reduced in mice exposed to cigarette smoke, but restored by sulforaphane treatment. No effects of sulforaphane were observed in Nrf2-deficient mice. These findings indicate that cigarette smoke induces steroid unresponsiveness in asthmatic airways, and that sulforaphane restores steroid sensitivity via upregulation of Nrf2 and enhancement of HDAC2 expression and activity. Thus, Nrf2 may serve as a potential molecular target for cigarette smoke-related refractory asthma resistant to steroid therapy.

Kv1.3 channel current changes in neutrophilic asthma and eosinophilic asthma

Objective Allergic asthma is a chronic inflammatory disease of the airways.T lymphocytes play important roles in the pathogenesis of asthma.The voltage-gated Kv1.3 potassium channel may be a key factor in the activation of T lymphocytes.This research aims to detect the function of Kv1.3 channel in the neutrophlial asthma(NA)model and eosinophilic asthma(EA)model. Methods A total of 24 mice were randomly assigned into three groups: control, neutrophilic asthma model and eosinophilic asthma group.Neutrophilic asthma model was established with ovalbumin(OVA)and lipopolysaccharide(LPS); eosinophilic asthma was established with OVA and Al(OH)3; airway responsiveness of mice in each group was measured with a noninvasive pulmonary function instrument; lung inflammation changes were observed by pathological HE staining; IL-17A and IL-4 cytokines levels in bronchoalveolar lavage fluid were evaluated by ELISA; Kv1.3 channel protein level in lung was evaluated by western blot; the change of current density in CD4+ .T lymphocytes were tested by whole-cell patch clamp technique. Results Levels of IL-17A and IL-4 in bronchoalveolar lavage fluid increased in both NA and EA model(P<0.05). Compare with EA model, the IL-17A level was significantly higer in NA model, while the IL-4 level was significantly lower.In NA and EA model, kv1.3 protein expression in lung tissue was significantly higher than that in the control group(P<0.05), and kv1.3 protein expression in NA model was significantly higer than that in the EA model(P<0.05). Current intensity and current density of kv1.3 channel increased in both NA and EA model.While the current intensity and current density of kv1.3 channel were significantly higher in NA model than that in EA model. Conclusion Kv1.3 protein level, Kv1.3 channel current intensity and kv1.3 channel current density increased in both NA and EA model, especially in NA group, providing a new way for treatment of bronchial asthma. Key words: Neutrophlial asthma; Eosinophilic Asthma; Kv1.3 channel

Role of ROCK2 in CD4+ cells in allergic airways responses in mice.

Rho kinases (ROCKs) contribute to allergic airways disease. ROCKs also play a role in lymphocyte proliferation and migration. To determine the role of ROCK2 acting within CD4+ cells in allergic airways responses. ROCK2-haploinsufficient (ROCK2+/- ) and wild-type mice were sensitized with ovalbumin (OVA). ROCK2+/- mice then received either CD4+ cells from ROCK2-sufficient OVA TCR transgenic (OT-II) mice or saline i.v. 48 h before challenge with aerosolized OVA. Wild-type mice received saline before challenge. Allergic airways responses were measured 48 h after the last challenge. Allergic airways responses were also assessed in mice lacking ROCK2 only in CD4+ cells (ROCK2CD4Cre mice) vs. control (CD4-Cre and ROCK2flox/flox ) mice. OVA-induced increases in bronchoalveolar lavage lymphocytes, eosinophils, IL-13, IL-5, and eotaxin were reduced in ROCK2+/- vs. wild-type mice, as were airway hyperresponsiveness and mucous hypersecretion. In ROCK2+/- mice, adoptive transfer with CD4+ cells from OT-II mice restored effects of OVA on lymphocytes, eosinophils, IL-13, IL-5, and mucous hypersecretion to wild-type levels, whereas eotaxin and airway hyperresponsiveness were not affected. ROCK2 inhibitors reduced IL-13-induced release of eotaxin from airway smooth muscle (ASM), similar to effects of these inhibitors on ASM contractility. Despite the ability of adoptive transfer to restore allergic airways inflammation in ROCK2-insufficient mice, allergic inflammation was not different in ROCK2CD4Cre vs. control mice. ROCK2 contributes to allergic airways responses likely via effects within ASM cells and within non-lymphocyte cells involved in lymphocyte activation and migration into the airways.

Effects of grape seed proanthocyanidin extract on airway inflammation and Treg/Th17 balance in asthmatic mice

Objective To explore effect of grape seed proanthocyanidin extract(GSPE)on airway inflammation and hyperresponsiveness of ovalbumin-induced murine asthma model and the associated regulatory effect on Treg/Th17 imbalance. Methods A total of 40 mice were randomly assigned to four experimental groups: control, asthma model, low dose GSPE(40 mg/kg), and high dose GSPE(80 mg/kg). Acute asthma model was established with OVA; airway responsiveness of mice in each group was measured with a noninvasive pulmonary function instrument; lung inflammation changes were observed by pathological HE staining; Treg/Th17 cytokines levels in bronchoalveolar lavage fluid were evaluated by ELISA; the expressions of forkhead/winged helix transcription factor(Foxp3)mRNA and retinoid-related orphan receptor gammat(RORγt)mRNA in lung tissue of each group were gained by Real-time PCR method. Results GSPE inhibited ovalbumin-induced increases in airway responsiveness(P<0.05). Histological studies demonstrated that GSPE substantially inhibited OVA-induced airway inflammation in lung tissue.GSPE decreased IL-17A levels and increased IL-10 levels in bronchoalveolar lavage fluid(P<0.05). In the asthma model group, RORγt mRNA expression in lung tissue was significantly higher than that in the control group(P<0.05)and Foxp3 mRNA expression was significantly lower than that in the control group(P<0.05). In the GSPE group, RORγt mRNA expression was lower than that in asthma model group(P<0.05), however the Foxp3 mRNA expression was higher than that in asthma model group(P<0.05). Conclusion GSPE could alleviate airway hyperresponsiveness and airway inflammation of in asthmatic mice.It can modify the asthmatic mice Treg/Th17 imbalance by decreasing IL-17A and increasing IL-10 concentration at the level of cytokines; and also by increasing Foxp3 mRNA expression and inhibiting the expression of RORγt mRNA at the transcriptional level, which provide a new way for treatment of bronchial asthma. Key words: Grape seed proanthocyanidin extract; Asthma; Forkhead/winged helix transcription factor; Retinoid-related orphan receptor gammat

Effect of lactobacillus salivarius on asthma Balb/c mouse in IL-4, IFN-γ and IgE of serum and lung tissue homogenates

Objective To invstigate the effect of Lactobacillus salivarius on asthma Balb/ c mouse in IgE, IL-4 and IFN-γ of serum and lung tissue homogenates. Methods Thirty female Balb/c mice weighing 16-18 g (4 weeks old), SPF grade, were randomly divided into three groups: normal control group (N), asthma group(A), asthma combined Lactobacillus salivarius group (AH). Acute asthma model was established by ovalbumin challenge method, mice were observed in behavioral changes, non-invasive method for the determination of airway responsiveness in mice, the changes in airway inflammation and the number changes of tracheal cilia were observed by pathological HE staining and the electron microscope.Respectively, the levels of IgE and IL-4/IFN-γ in the serum and lung tissue homogenate were measured by ELISA. Results five~ten min after 4%OVA saline solution atomization excitation mice in A group appeared obvious restlessness, head and facial itching, scratching, shortness of breath, perioral cyanosis with abdominal breathing, sneezing, stooping, forelimbs shrinkage, urine and feces incontinence and other asthma acute phase performances, The above reaction alleviated in AH group compared to A group; Pathology of HE staining in asthma group showed the thickening bronchial wall, narrow lumen, peribronchial and perivascular infiltration with a large number of eosinophil-based inflammatory cells, lumen with many inflammatory secretions, Pathological changes in lung tissue of mice in AH group significantly alleviated compared with asthma group; Under the electron microscope, the number of cilia in A group significantly decreased compared with N group, while AH group significantly increased compared with A group; Expression level of IgE, IL-4 in the serum and lung homogenate of A group was significantly higher than that of N group(P<0.05), the level of IFN-γ expression was significantly lower than N group(P<0.05), however the expression level of IgE, IL-4 in AH group significantly decreased compared with A group(P<0.05), and IFN-γ expression level elevated compared with A group(P<0.05). Conclusion Lavage with Lactobacillus salivarius before sensitization could alleviate clinical symptoms of asthmatic mice, partially correct Th1/Th2 imbalance as well as reduce airway inflammation. Key words: Lactobacillus salivarius; Asthma; IgE; IL-4; IFN-γ; Mouse

The gain of smooth muscle's contractile capacity induced by tone on in vivo airway responsiveness in mice

Airway hyperresponsiveness to a spasmogenic challenge such as methacholine, and an increased baseline tone measured by the reversibility of airway obstruction with a bronchodilator, are two common features of asthma. However, whether the increased tone influences the degree of airway responsiveness to a spasmogen is unclear. Herein, we hypothesized that increased tone augments airway responsiveness in vivo by increasing the contractile capacity of airway smooth muscle (ASM). Anesthetized, tracheotomized, paralyzed, and mechanically ventilated mice were either exposed (experimental group) or not (control group) to tone for 20 min, which was elicited by nebulizing serial small doses of methacholine. Respiratory system resistance was monitored during this period and the peak response to a large cumulative dose of methacholine was then measured at the end of 20 min to assess and compare the level of airway responsiveness between groups. To confirm direct ASM involvement, the contractile capacity of excised murine tracheas was measured with and without preexposure to tone elicited by either methacholine or a thromboxane A2 mimetic (U46619). Distinct spasmogens were tested because the spasmogens liable for increased tone in asthma are likely to differ. The results indicate that preexposure to tone increases airway responsiveness in vivo by 126 ± 37% and increases the contractile capacity of excised tracheas ex vivo by 23 ± 4% for methacholine and 160 ± 63% for U46619. We conclude that an increased tone, regardless of whether it is elicited by a muscarinic agonist or a thromboxane A2 mimetic, may contribute to airway hyperresponsiveness by increasing the contractile capacity of ASM.

Methods in assessment of airway reactivity in mice.

Due to the wealth of reagents and transgenic strains available, mice have become one of the most commonly used model organisms for the study of allergic airway inflammation. One of the major hallmarks of the asthma phenotype in humans is reversible airflow obstruction, or airway hyper-responsiveness. However, the ability to confidently obtain useful physiological responses from such a small animal has presented a large technological challenge in murine studies. Recent advances have provided the technology to obtain lung mechanics through either the forced oscillation technique or plethysmography. Here we describe the utility of these measurements in mouse models of allergic airway inflammation and anaphylaxis.

Toll-like receptor (TLR) 7 decreases and TLR9 increases the airway responses in mice with established allergic inflammation

Toll-like receptor (TLR) 7 and TLR9 recognise microbial products of viral descent. Since viruses are a common trigger of asthma exacerbations these TLRs have emerged as interesting therapeutic targets. Even though their effects on allergic inflammation have been evaluated in several models their effects on established allergic airway inflammation remains to be described. Therefore, mice with an on-going ovalbumin (OVA)-induced allergic airway inflammation were given R848 or CpG (TLR7 and TLR9 agonists, respectively) intranasally during four consecutive days. At day five, the R848 treatment had reduced OVA-induced airway hyperresponsiveness (measured as the increased resistance to methacholine), counteracted the accompanying influx of eosinophils and macrophages, and decreased the OVA-enhanced release of interleukin (IL)-5 and leukotriene (LT) B4 in bronchoalveolar lavage fluid. CpG, which by itself caused airway hyperresponsiveness, did not influence the OVA-induced airway hyperresponsiveness, and release of IL-5 and LTB4, but decreased the OVA-induced influx of cells in bronchoalveolar lavage fluid, and increased the amount of pro-inflammatory mediators like IL-12, CXCL1 and CXCL9. To conclude, TLR7 dampens the allergic airway reactivity and local inflammation, whereas TLR9 that causes airway hyperresponsiveness and increased cellular response per se, do generally not interfere with the effects induced by allergic inflammation.

Differential Effects of Allergen Challenge on Large and Small Airway Reactivity in Mice

The relative contributions of large and small airways to hyperresponsiveness in asthma have yet to be fully assessed. This study used a mouse model of chronic allergic airways disease to induce inflammation and remodelling and determine whether in vivo hyperresponsiveness to methacholine is consistent with in vitro reactivity of trachea and small airways. Balb/C mice were sensitised (days 0, 14) and challenged (3 times/week, 6 weeks) with ovalbumin. Airway reactivity was compared with saline-challenged controls in vivo assessing whole lung resistance, and in vitro measuring the force of tracheal contraction and the magnitude/rate of small airway narrowing within lung slices. Increased airway inflammation, epithelial remodelling and fibrosis were evident following allergen challenge. In vivo hyperresponsiveness to methacholine was maintained in isolated trachea. In contrast, methacholine induced slower narrowing, with reduced potency in small airways compared to controls. In vitro incubation with IL-1/TNFα did not alter reactivity. The hyporesponsiveness to methacholine in small airways within lung slices following chronic ovalbumin challenge was unexpected, given hyperresponsiveness to the same agonist both in vivo and in vitro in tracheal preparations. This finding may reflect the altered interactions of small airways with surrounding parenchymal tissue after allergen challenge to oppose airway narrowing and closure.

Impact of Adiponectin Overexpression on Allergic Airways Responses in Mice

Obesity is an important risk factor for asthma. Obese individuals have decreased circulating adiponectin, an adipose-derived hormone with anti-inflammatory properties. We hypothesized that transgenic overexpression of adiponectin would attenuate allergic airways inflammation and mucous hyperplasia in mice. To test this hypothesis, we used mice overexpressing adiponectin (Adipo Tg). Adipo Tg mice had marked increases in both serum adiponectin and bronchoalveolar lavage (BAL) fluid adiponectin. Both acute and chronic ovalbumin (OVA) sensitization and challenge protocols were used. In both protocols, OVA-induced increases in total BAL cells were attenuated in Adipo Tg versus WT mice. In the acute protocol, OVA-induced increases in several IL-13 dependent genes were attenuated in Adipo Tg versus WT mice, even though IL-13 per se was not affected. With chronic exposure, though OVA-induced increases in goblet cells numbers per millimeter of basement membrane were greater in Adipo Tg versus WT mice, mRNA abundance of mucous genes in lungs was not different. Also, adiponectin overexpression did not induce M2 polarization in alveolar macrophages. Our results indicate that adiponectin protects against allergen-induced inflammatory cell recruitment to the airspaces, but not development of goblet cell hyperplasia.

Role of the Adiponectin Binding Protein, T-Cadherin (Cdh13), in Allergic Airways Responses in Mice

Adiponectin is an adipose derived hormone that declines in obesity. We have previously shown that exogenous administration of adiponectin reduces allergic airways responses in mice. T-cadherin (T-cad; Cdh13) is a binding protein for the high molecular weight isoforms of adiponectin. To determine whether the beneficial effects of adiponectin on allergic airways responses require T-cad, we sensitized wildtype (WT), T-cadherin deficient (T-cad−/−) and adiponectin and T-cad bideficient mice to ovalbumin (OVA) and challenged the mice with aerosolized OVA or PBS. Compared to WT, T-cad−/− mice were protected against OVA-induced airway hyperresponsiveness, increases in BAL inflammatory cells, and induction of IL-13, IL-17, and eotaxin expression. Histological analysis of the lungs of OVA-challenged T-cad−/− versus WT mice indicated reduced inflammation around the airways, and reduced mucous cell hyperplasia. Combined adiponectin and T-cad deficiency reversed the effects of T-cad deficiency alone, indicating that the observed effects of T-cad deficiency require adiponectin. Compared to WT, serum adiponectin was markedly increased in T-cad−/− mice, likely because adiponectin that is normally sequestered by endothelial T-cad remains free in the circulation. In conclusion, T-cad does not mediate the protective effects of adiponectin. Instead, mice lacking T-cad have reduced allergic airways disease, likely because elevated serum adiponectin levels act on other adiponectin signaling pathways.

Oral administration of Enterococcus faecalis FK-23 suppresses Th17 cell development and attenuates allergic airway responses in mice

Evidence is increasing that oral administration of probiotics can attenuate asthmatic responses both in murine models and clinical trials. T-helper 17 (Th17) cells, a subset of CD4+ T cells have been implicated as having an important role in the development of several allergic disorders, but the relationship between oral administration of probiotics and Th17 development has not been well studied. BALB/c mice were given lysed Enterococcus faecalis FK-23 (LFK) orally for 28 days. After sensitization by subcutaneous injection of ovalbumin (OVA) on Days 14 and 21 and 1% OVA inhalation on Days 25, 26 and 27, they were challenged with a 5% OVA aerosol on Day 28. Twenty-four hours later, airway resistance and accumulation of inflammatory cells in bronchoalveolar lavage fluid (BALF) and lung tissues were determined. Ιnterleukin (IL)-17-expressing CD4+ lymphocytes isolated from lung, spleen and lamina propria of the intestine were detected by flow cytometry. The expression of IL-6 and TGF-β mRNA was assessed by real-time PCR. Increases in airway hyperresponsiveness, and numbers of total leukocytes and mast cells in BALF induced by OVA challenge were significantly suppressed by oral administration of LFK. The increased percentage of IL-17-expressing CD4+ cells from lung, spleen and intestine in OVA-challenged mice was reduced following LFK treatment. We conclude that the oral administration of LFK suppresses the asthmatic response and that this is associated with attenuation of Th17 cell development.

Respiratory Syncytial Virus Infections Augment Airway Reactivity in Mice Exposed to Chlorine (Cl2)

Chlorine (Cl2) gas inhalation causes respiratory system injury including epithelial cell sloughing, edema and airway hyperreactivity, leading to reactive airway dysfunction syndrome (RADS), a prelude to asthma. However, little is known about how pre‐existing infections alter the responses of animals to a subsequent Cl2 exposure. Herein Balb/c mice were infected with respiratory syncytial virus (RSV), a common respiratory infection in children, via intranasal instillation of 100 microliters of RSV A2 (106 PFU/ml) or vehicle. Four days later they were exposed to 187 ppm Cl2 for 30 minutes in environmental chambers and returned to room air. Measurements of airway resistance and elastance, prior to and following challenge with aerosolized methacholine (up to 50 mg/ml) were conducted in anesthetized mice with a flexiVent, 24 h post exposure. RSV infection greatly increased: (1) airway resistance and elastance after methacholine challenge in Cl2 exposed mice as compared to vehicle infected mice; (2) levels of IL‐10, interferon‐γ and RANTES and (3) levels of low molecular weight hyaluronan and inter‐α‐trypsin inhibitor (IaI; a factor necessary for the binding of hyaluronan to its receptor) in the BAL. Hyaluronan has been shown to contribute to airway hyperresponsiveness in mice exposed to ozone. We concluded that pre‐existing viral infections increase the susceptibility of mice to Cl2 induced airway injury via the upregulation of a variety of inflammatory cytokines and hyaluronan.

Effects of simulated downwind coal combustion emissions on pre-existing allergic airway responses in mice

Context: Coal-fired power plant emissions can contribute a significant portion of the ambient air pollution in many parts of the world.Objective: We hypothesized that exposure to simulated downwind coal combustion emissions (SDCCE) may exacerbate pre-existing allergic airway responses.Methods: Mice were sensitized and challenged with ovalbumin (OVA). Parallel groups were sham-sensitized with saline. Mice were exposed 6 h/day for 3 days to air (control, C) or SDCCE containing particulate matter (PM) at low (L; 100 μg/m3), medium (M; 300 μg/m3), or high (H; 1000 μg/m3) concentrations, or to the H level with PM removed by filtration (high-filtered, HF). Immediately after SDCCE exposure, mice received another OVA challenge (pre-OVA protocol). In a second (post-OVA) protocol, mice were similarly sensitized but only challenged to OVA before air/SDCCE. Measurement of airway hyperresponsiveness (AHR), bronchoalveolar lavage (BAL), and blood collection were performed ~24 h after the last exposure.Results: SDCCE significantly increased BAL macrophages and eosinophils in OVA-sensitized mice from the post-OVA protocol. However, there was no effect of SDCCE on BAL macrophages or eosinophils in OVA-sensitized mice from the pre-OVA protocol. BAL neutrophils were elevated following SDCCE in both protocols in nonsensitized mice. These changes were not altered by filtering out the PM. In the post-OVA protocol, SDCCE decreased OVA-specific IgG1 in OVA-sensitized mice but increased levels of total IgE, OVA-specific IgE and OVA-specific IgG1 and IgG2a in non-sensitized animals. In the pre-OVA protocol, SDCCE increased OVA-specific IgE in both sensitized and non-sensitized animals. Additionally, BAL IL-4, IL-13, and IFN-γ levels were elevated in sensitized mice.Conclusion: These results suggest that acute exposure to either the particulate or gaseous phase of SDCCE can exacerbate various features of allergic airway responses depending on the timing of exposure in relation to allergen challenge.