Background
Most mouse models of house dust mite (HDM) challenge-induced allergic pulmonary inflammation utilise long challenge periods usually via the intranasal route that can typically last for up to 9 weeks. While these extended protocols are useful for investigating features of lung remodelling, the allergic phenotype, consisting of the cell and cytokine/chemokine network, usually develops early on. We describe here the phenotype of the allergic process in a truncated 3 week protocol.
Materials and methods
Female BALB/c mice were intra-nasally challenged once a day for 5 days a week for a 3 week period with HDM extract (25µg) in 50µl saline. Mice were sacrificed 4 hours after the last HDM challenge on the third week and bronchoalveolar lavage levels of; cells, chemokines, cytokines and serum IgE were quantified. Airways hyper-responsiveness (AHR) by whole body plethysmography to increasing concentrations of 5-Hydroxytryptamine was ascertained 24 hours prior to sacrificing animals. Separate groups of mice were also challenged intra-nasally with anti-CD3e (1µg in 50µl saline) at 24, 48 or 72 hours post 1, 2 or 3 weeks of HDM exposure. The resulting cytokine levels in bronchoalveolar lavage were ascertained 4 hours after anti-CD3e challenge. This was to test the ability of resident T cells to generate a cytokine response.
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Results
Apart from macrophages, all cell types investigated were elevated above background levels 4 hours after the last HDM challenge. The presence of CD4+ cells in lung lavage was associated with an increase in MDC and TARC levels. Serum total IgE levels were also elevated with a small, above background increase in HDM-specific IgE. HDM challenged animals exhibited an increased AHR compared to saline challenged animals. Anti-CD3e challenge elicited a robust cytokine signal at the 48 hour time-point on the third week of HDM challenge.
Conclusions
The model described here is a refinement of HDM protocols described in the literature that can last for months. This modified protocol allows for the investigation of allergic mechanisms at an earlier time-point resulting in less cost to animals and a quicker data turnaround time. This approach may be more conducive to the optimisation of novel therapeutic agents.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.