Repeated Allergen Exposure in A/J Mice Causes Steroid-Insensitive Asthma via a Defect in Glucocorticoid Receptor Bioavailability.

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.

JM25-1, a Lidocaine Analog Combining Airway Relaxant and Antiinflammatory Properties: Implications for New Bronchospasm Therapy.

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 Ca; 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 × 10/µm (n = 6; P < 0.001) and neutrophils from 1.9 ± 0.4 to 0.2 ± 0.1 × 10/µm (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.

Nebulized lidocaine prevents airway inflammation, peribronchial fibrosis, and mucus production in a murine model of asthma.

BACKGROUND: Evidence suggests that nebulized lidocaine is beneficial in asthma therapy, but to what extent and the mechanisms underlying this effect remain poorly understood. The aim of this study was to assess the impact of lidocaine treatment using a murine model of allergic asthma characterized by expression of pivotal features of the disease: inflammation, mucus production, and lung remodeling. METHODS: A/J mice sensitized with ovalbumin were treated with inhaled lidocaine or vehicle immediately after ovalbumin intranasal challenges. Lung function, total and differential leukocytes in bronchoalveolar lavage fluid, peribronchial eosinophil density, interleukin (IL)-4, IL-5 and eotaxin-1 levels, epithelial mucus, collagen, extracellular-matrix deposition, matrix metalloproteinase-9 activity, and GATA-3 expression were evaluated. Between five and eight animals per group were used. RESULTS: Inhaled lidocaine inhibited ovalbumin-induced airway hyperreactivity to methacholine, and accumulation of lymphocytes, neutrophils, and eosinophils in bronchoalveolar lavage fluid 24 h after the last allergen provocation. Lidocaine administration also prevented other pathophysiological changes triggered by ovalbumin in lung tissue, including peribronchial eosinophil and neutrophil infiltration, subepithelial fibrosis, increased content of collagen and mucus, matrix metalloproteinase-9 activity, and increased levels of IL-4, IL-5, IL-13, and eotaxin-1. Furthermore, inhaled lidocaine inhibited lung tissue GATA-3 expression in ovalbumin-challenged mice. We also demonstrated that lidocaine inhibited the expression of GATA-3 in ovalbumin-stimulated T cells in vitro. CONCLUSIONS: 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.