Inhaled lidocaine prevents eosinophilic inflammation, overproduction of mucus, and peribronchial fibrosis in a murine model of asthma, and impaired airway hyperreactivity, possibly by inhibiting allergen-evoked GATA-3 expression and the subsequent up-regulation of proinflammatory cytokines and chemokines.

Although gold nanoparticles have been shown to exhibit a range of beneficial biological properties, including antiinflammatory and anti-oxidant effects, their putative impact on allergic asthma has not been addressed. In this study, we evaluated the potential of nasal-instilled gold nanoparticles to prevent allergen-induced asthma in distinct murine models of this disease. Swiss-Webster (outbred) and A/J (inbred) mice were sensitized with ovalbumin and then treated with intranasal injections of gold nanoparticles (6 and 60 μg/kg), 1 h before ovalbumin challenges. Lung function, leukocyte infiltration, mucus exacerbation, extracellular matrix deposition, cytokine generation and oxidative stress were evaluated 24 h after the last challenge. In both mice strains, gold nanoparticles clearly inhibited (70-100%) allergen-induced accumulation of inflammatory cells as well as the production of both pro-inflammatory cytokines and reactive oxygen species. In A/J mice, recognized as genetic asthma prone animals, instilled gold nanoparticles clearly prevented mucus production, peribronchiolar fibrosis and airway hyper-reactivity triggered by allergen provocation. In conclusion, these findings demonstrate that gold nanoparticles prevented pivotal features of asthma, including airway hyper-reactivity, inflammation and lung remodelling. Such protective effects are accounted for by reduction in lung tissue generation of pro-inflammatory cytokines and chemokines, in a mechanism probably related to down-regulation in the levels of oxidative stress.

Background Inhaled lidocaine antagonized bronchospasm in animal models and patients, but adverse effects limited its efficacy. This study evaluated the antibronchospasm potential of the analog JM25-1, exploring in vitro mechanisms and translation to an animal model. Methods The effectiveness of JM25-1 was assessed in GH3 cells, rat tracheal rings, mouse lymphocytes, and human eosinophil systems in vitro, assessing changes in Na+ current, contraction, proliferation, and survival, respectively. Lung function and inflammatory changes were studied in ovalbumin-sensitized mice. Results The efficacy of JM25-1 was higher than lidocaine in inhibiting carbachol-induced and calcium-induced tracheal contractions (maximum effect inhibition at 1 mM [%]: 67 ± 10 [JM25-1] vs. 41 ± 11 [lidocaine] [P < 0.001] for carbachol; 100 ± 3 [JM25-1] vs. 36 ± 26 [lidocaine] [P < 0.001] for Ca2+; mean ± SD; n = 9 each) but lower in Na+ current (50% inhibitory concentration = 151.5, n = 8 vs. 0.2 mM; n = 5; P < 0.001). JM25-1 also inhibited eosinophil survival (dead cells [%]: 65 ± 6; n = 4; P < 0.001 at 1 mM) and lymphocyte proliferation (cells in phase S + G2 [%]: 94 ± 10; n = 6; P < 0.001) at 0.6 mM. Aerosolized JM25-1 (1%) decreased lung eosinophil numbers from 13.2 ± 2.4 to 1.7 ± 0.7 × 104/μm2 (n = 6; P < 0.001) and neutrophils from 1.9 ± 0.4 to 0.2 ± 0.1 × 104/μm2 (n = 7; P < 0.001). Other parameters, including airway hyperreactivity, cytokines, mucus, and extracellular matrix deposition, were also sensitive to aerosolized JM25-1. Conclusion These findings highlight the potential of JM25-1, emphasizing its putative value in drug development for clinical conditions where there is bronchospasm.

The importance of developing new animal models to assess the pathogenesis of glucocorticoid (GC)-insensitive asthma has been stressed. Because of the asthma-prone background of A/J mice, we hypothesized that asthma changes in these animals would be or become resistant to GCs under repeated exposures to an allergen. A/J mice were challenged with OVA for 2 or 4 consecutive d, starting on day 19 postsensitization. Oral dexamethasone or inhaled budesonide were given 1 h before challenge, and analyses were done 24 h after the last challenge. Airway hyperreactivity, leukocyte infiltration, tissue remodeling, and cytokine levels as well as phosphorylated GC receptor (p-GCR), p-GATA-3, p-p38, MAPK phosphatase-1 (MKP-1), and GC-induced leucine zipper (GILZ) levels were assessed. A/J mice subjected to two daily consecutive challenges reacted with airway hyperreactivity, subepithelial fibrosis, and marked accumulation of eosinophils in both bronchoalveolar lavage fluid and peribronchial space, all of which were clearly sensitive to dexamethasone and budesonide. Conversely, under four provocations, most of these changes were steroid resistant. A significant reduction in p-GCR/GCR ratio following 4- but not 2-d treatment was observed, as compared with untreated positive control. Accordingly, steroid efficacy to transactivate MKP-1 and GILZ and to downregulate p-p38, p-GATA-3 as well as proinflammatory cytokine levels was also seen after two but not four provocations. In conclusion, we report that repeated allergen exposure causes GC-insensitive asthma in A/J mice in a mechanism associated with decrease in GCR availability and subsequent loss of steroid capacity to modulate pivotal regulatory proteins, such as GATA-3, p-p38, MKP-1, and GILZ.

Background. Regulatory T cells (Tregs) are important in regulating responses to innocuous antigens, such as allergens, by controlling the Th2 response, a mechanism that appears to be compromised in atopic asthmatic individuals. Different isogenic mouse strains also have distinct immunological responses and susceptibility to the experimental protocols used to develop lung allergic inflammation. In this work, we investigated the differences in the frequency of Treg cell subtypes among A/J, BALB/c, and C57BL/6, under normal conditions and following induction of allergic asthma with ovalbumin (OVA). Methods. Subcutaneous sensitization followed by 4 consecutive intranasal OVA challenges induced asthma characteristic changes such as airway hyperreactivity, inflammation, and production of Th2 cytokines (IL-4, IL-13, IL-5, and IL-33) in the lungs of only A/J and BALB/c but not C57BL/6 strain and evaluated by invasive whole-body plethysmography, flow cytometry, and ELISA, respectively. Results. A/J strain naturally showed a higher frequency of CD4+IL-10+ T cells in the lungs of naïve mice compared to the other strains, accompanied by higher frequencies of CD4+IL-4+ T cells. C57BL/6 mice did not develop lung inflammation and presented higher frequency of CD4+CD25+Foxp3+ Treg cells in the bronchoalveolar lavage fluid (BALF) after the allergen challenge. In in vitro settings, allergen-specific stimulation of mediastinal LN (mLN) cells from OVA-challenged animals induced higher frequency of CD4+IL-10+ Treg cells from A/J strain and CD4+CD25+Foxp3+ from C57BL/6. Conclusions. The observed differences in the frequencies of Treg cell subtypes associated with the susceptibility of the animals to experimental asthma suggest that CD4+CD25+Foxp3+ and IL-10-producing CD4+ Treg cells may play different roles in asthma control. Similar to asthmatic individuals, the lack of an efficient regulatory response and susceptibility to the development of experimental asthma in A/J mice further suggests that this strain could be preferably chosen in experimental models of allergic asthma.