A review.Asthma is an inflammatory condition of the airways triggered by exposure to allergens and/or irritants.TRPA1 is an irritant-sensing cation channel expressed in TRPV1-pos., capsaicin-sensitive chemosensory neurons that innervate various organs, including the airways.Various exogenous noxious chems. have been described to activate TRPA1, including agents recognized to trigger and/or worsen asthma such as diisocyantes, cigarette smoke, acrolein, chlorine.During oxidative stress, a condition associated with asthma, various chem. species capable of activating TRPA1 are generated in the lungs, including reactive oxygen species (ROS), reactive nitrogen species (RNS), and several byproducts of lipid peroxidation including nitrooleic acid and 4-hydroxynonenal.Recently, a potential role of TRPA1 in mediating allergen-induced asthmatic responses has been described in ovalbumin-sensitized mice, in which genetic deletion of TRPA1 or pretreatment with a selective TRPA1 antagonist reduced leukocyte infiltration, decreased cytokine and mucus production and almost completely abolished airway hyperreactivity without affecting the immune response driven by the allergen.Moreover, two recent studies have provided strong pharmacol. evidence that inhalation of TRPA1 activators, like acrolein or cinnamaldehyde, elicits cough reflexes in guinea-pigs and human volunteers.In conclusion, a compelling series of recent findings highlights the TRPA1 channel as a mol. target for a wide variety of known exogenous and endogenous inflammatory and irritating chem. agents, and suggests that TRPA1 antagonists might be taken into consideration as a novel pharmacol. treatment of asthma, chronic cough and possibly other inflammatory conditions of the airways.