Transient Receptor Potential Ankyrin 1 Enhances Ovalbumin-Induced Acute Allergic Inflammation in Murine Models

Transient receptor potential ankyrin 1 (TRPA1) is an ion channel known to mediate nociception and neurogenic inflammation, and to be activated by reactive oxygen and nitrogen species (ROS and RNS) produced at the sites of inflammation. Because neurogenic inflammation as well as the release of ROS and RNS are typical features of early stages of allergic responses, we hypothesized that TRPA1 may be involved in triggering and/or amplifying allergic inflammation.

This study aims at exploring the role of TRPA1 ion channel in acute ovalbumin-induced allergic inflammation in applicable murine models.

The effects of pharmacological blockade and genetic deletion of TRPA1 in ovalbumin-induced allergic conjunctivitis and acute paw inflammation were studied in mice sensitized to ovalbumin.

Ovalbumin-induced allergic conjunctivitis was milder in TRPA1-deficient mice and alleviated in wild-type mice treated with the TRPA1 antagonist TCS 5861528. Subcutaneous challenge with ovalbumin caused a significant paw edema and interleukin (IL)-4 production in sensitized mice; these responses were attenuated in animals treated with the TRPA1 antagonist and in TRPA1-deficient mice. Interestingly, blockade of the major secondary effector of TRPA1, substance P, also resulted in attenuated ovalbumin-induced paw edema and IL-4 production. However, the splenocytes' responses to ovalbumin were similar in cells from wild-type and TRPA1-deficient mice sensitized to ovalbumin.

These results introduce a novel concept that TRPA1 mediates early events in allergic inflammation, but does not seem to affect allergic sensitization, and could therefore be a novel drug target to treat conditions associated with allergic inflammation.