Lack of transient receptor potential vanilloid-1 enhances Th2-biased immune response of the airways in mice receiving intranasal, but not intraperitoneal, sensitization.

BACKGROUND

Transient receptor potential vanilloid-1 (TRPV1) may modulate allergic airway inflammation because it is expressed not only on the nerve endings but also on several cells of the immune system. We wanted to know the characteristics of airway and systemic responses against sensitization and challenge with allergens in TRPV1 receptor gene knockout mice (TRPV1(-/-)).

METHODS

TRPV1(-/-) and their wild-type counterparts (TRPV1(+/+)) were sensitized with either house dust mite (HDM) or ovalbumin (OVA) via intranasal (i.n.) or intraperitoneal (i.p.) route before the final i.n. challenge with the corresponding allergen. One day after the final challenge, serum IgE levels, cytokine levels in the bronchoalveolar lavage fluid (BALF), and the number of BALF cells were examined after measuring bronchial hyperresponsiveness against methacholine.

RESULTS

Compared to TRPV1(+/+), TRPV1(-/-) showed enhanced Th2-biased response after i.n. HDM or OVA sensitization, including increased levels of serum IgE, interleukin 4 (IL-4) and eosinophils in the BALF. By contrast, when sensitized via i.p. route, the response against OVA or HDM was almost similar between TRPV1(+/+) and TRPV1(-/-).

CONCLUSION

TRPV1 receptor may downregulate Th2-biased immune response when sensitized via airways, although this was not the case when sensitized systemically.