Darien Shapiro, University of Utah
Pharmacology and Toxicology
Exposure to wood smoke particulate matter (WSPM) has been linked to exacerbation of asthma, development of chronic obstructive pulmonary disease (COPD), and premature death. Combustion-derived PM (cdPM) such as cigarette smoke (CS), diesel exhaust (DEP), and WSPM, activate transient receptor potential ankyrin-1 (TRPA1) which promotes neurogenic inflammation/edema and airway irritation/cough. The mechanism of TRPA1 activation by DEP and CS involves the electrophilic/oxidant binding (3CK) and menthol-binding (ST) sites, and a novel mechanosensitive site. We hypothesized that WSPM would activate TRPA1 through one or more of these sites similar to other cdPM. Pine and mesquite PM were generated in the laboratory. Both types of WSPM particles activated TRPA1 in human TRPA1 over-expressing HEK-293 and primary mouse trigeminal (TG) neurons. WSPM also activated TRPA1 in A549 cells, a human alveolar adenocarcinoma cell line, which has recently been shown to express TRPA1. HC030031, a TRPA1 specific antagonist, attenuated the calcium flux due to WSPM treatment in both human A459 cells and mouse primary TG neurons. Differential activation of TRPA1, as a function of particle size, demonstrated that PM2.5 m were most potent. Several known chemical components of WSPM, including 3,5-ditert-butylphenol and agathic acid were TRPA1 agonists. Both WSPM and agathic acid activated TRPA1 primarily via binding the 3CK site, based on inhibition of calcium flux by glutathione and mutation of the 3CK site. Conversely, 3,5-ditert-butylphenol activated TRPA1 through the ST site. This study established the mechanism by which WSPM and associated chemical components activated TRPA1 which may help tailor effective therapeutic treatments for WSPM pneumotoxicity. Support: NIEHS ES017431 and the University of Utah Undergraduate Research Opportunities Program.