Establishment and characterization of murine models of asthma and
subcutaneous immunotherapy for Humulus pollen allergy
Abstract
Humulus pollen is an important cause of allergic asthma in East Asia.
There have been some murine models for Humulus pollen allergy
established by intraperitoneal (IP) sensitization and nasal drip
stimulation, but they were not comprehensive enough. Here, we used
atomized inhalation for challenge and compared the subcutaneous (SC) and
IP sensitization routes to determine the optimal method to establish a
model of asthma induced by Humulus pollen. Subsequently, we tried to
develop a rapid subcutaneous immunotherapy (SCIT) model. Mice were
sensitized through the SC or IP route and challenged with Humulus pollen
extract to induce asthma. To compare the two sensitization methods,
airway hyperresponsiveness (AHR), inflammatory cell infiltration,
allergen-specific serum immunoglobulin (Ig)E (sIgE) levels, cytokine
levels, and lung histopathology were assessed. The effects of SCIT (once
every other day for 16 days) on airway inflammation, AHR, sIgE, and
allergen-specific serum IgG2a (sIgG2a) levels were evaluated by using
the model established. Although mice sensitized by the SC or IP routes
both showed AHR and airway inflammation, the SC route elicited
significantly higher levels of sIgE, eosinophil inflammation, and T
helper type 2 cytokines, compared with the IP route. SCIT in the
treatment group significantly reduced the titers of sIgE, enhanced the
titers of sIgG2a, and effectively alleviated pulmonary inflammation and
AHR, compared with the vehicle group. These observations indicate that
the SC route can be a better sensitization route than IP route for
establishing a murine model of Humulus pollen allergy; short-term SCIT
improved symptoms and pathophysiology in asthmatic mice.