Species-Specific Activation of Transient Receptor Potential Ankyrin 1 by Phthalic Acid Monoesters

Abstract

Phthalic acid (PA) diesters are widely used in consumer products, as plasticizers, and are ubiquitous environmental pollutants. There is a growing concern about their adjuvant effect on allergic diseases. Although its precise mechanism remains unknown, possible involvement of TRPA1 has been suggested. Hence, in this study, the activation of human and mouse TRPA1s by a series of PA di-and monoesters was investigated using a heterologous expression system in vitro.Consequently, it was found that monoesters activated human TRPA1, where EC50 values were in the order of mono-hexyl > mono-heptyl > mono-n-octyl > mono-2-ethylhexyl > mono-isononyl and mono-isodecyl esters. Significant species differences in TRPA1 activation by PA monoesters were also discovered; PA monoesters activated human TRPA1 but not mouse TRPA1 in a concentrationdependent manner up to 50 μM. These findings suggest that PA esters may exert TRPA1-dependent adverse effects on humans, which have never been demonstrated in experimental animals.

Species differences in activation of TRPA1 by resin additive-related chemicals relevant to indoor air quality

“…The Flp-In 293 cell lines stably expressing wild-type hTRPA1 and mTRPA1 (Flp-In 293/hTRPA1 and Flp-In 293/ mTRPA1 cells) were established in our previous studies (Mori et al, 2022;Ohkawara et al, 2012). The cells were cultured in Dulbecco's Modified Eagle Medium (DMEM, high glucose; Thermo Fisher Scientific, Waltham, MA, USA) containing 10% fetal bovine serum (Thermo Fisher Scientific), antibiotic solution (100 U/mL penicillin and 100 µg/mL streptomycin; Wako), and 2 mM GlutaMAX (Thermo Fisher Scientific).…”

“…Full-length human TRPA1 (hTRPA1; GenBank accession number NM_007332.3) and mouse TRPA1 (mTRPA1; GenBank accession number NM_177781) cDNAs were cloned as previously reported (Mori et al, 2022;Ohkawara et al, 2012). The hTRPA1 and mTRPA1 cDNAs were recombined with a pDONR207 (Thermo Fisher Scientific) entry plasmid through a BP (attB and attP) reaction using the Gateway BP clonase enzyme mix (Thermo Fisher Scientific).…”

“…TRPA1 expressed in the airway plays causative and exacerbating roles in respiratory diseases, such as bronchial hyperresponsiveness and airway infl ammation ( Simon and Liedtke, 2008 ). TRPA1 is activated by many types of indoor air pollutants, such as formaldehyde, acrolein, cigarette smoke, 1-hexanol, 1-ocatanol, and phthalic acid mono(2-ethylhexyl) ester (MEHP) (Conklin et al, 2017;Jin et al, 2019 ;Komatsu et al, 2012 ;Kurhanewicz et al, 2017 ;Mori et al, 2022 ), as well as the representative TRPA1 agonists, allyl isothiocyanate (AITC) and menthol ( Jordt et al, 2004 ;Karashima et al, 2007 ). Among these chemicals,1-hexanol, 1-ocatanol, MEHP, and menthol have been reported to show species-specifi c responses to TRPA1.…”