Dermal exposure to trimellitic anhydride (TMA) powder induces airway sensitization in an animal model.
Zhang-XD; Fedan-J; Millecchia-L; Lewis-D; Siegel-P
Toxicologist 2003 Mar; 72(S-1):60-61
TMA is a low-molecular-weight chemical used as a dry, fine powder by industry. Specific IgE and subsequent occupational asthma have been reported in exposed workers. The respiratory tract is considered to be a major route of TMA exposure, but dermal exposure is also possible. The role of exposure route in the development of TMA asthma is not known. The present study investigated the potential role of dermal exposure to dry TMA powder in both immunological sensitization and subsequent pulmonary responses to TMA inhalation challenge using the Brown Norway rat. Various doses of TMA were applied to the back (hair clipped carefully with scissors) on day 0, 7, 14 and 21, occluded with surgical tape and washed away after overnight, or after 5 hours of non-occluded exposure. Sera were collected on day 0, 7, 14, 21, 28 and 35 for specific IgE test. Exposed skin was also taken for morphologic study. TMA aerosol challenge was performed on day 35 and respiratory parameters including enhanced pause (Penh) recorded overnight. Bronchoalveolar lavage was performed and pulmonary eosinophils assessed. The application area appeared normal, without any sign of inflammation examined grossly or microscopically. Immunohistochemical study (with one exposure only) found TMA-adduct staining in the stratum corneum and hair follicle. Specific IgE was noted by day 14 and levels were TMA dose-dependent. Eosinophilic inflammation and both early (EAR) and late airway response (LAR), were observed after airway challenge. EAR subsided within 30 min following challenge. LAR typically began 2 or more hours following challenge and persisted longer than 8 hours. TMA specific IgE and airway responses occurred in both occluded and non-occluded dermally exposed rats. Dermal exposure to dry TMA powder can induce specific-IgE and subsequent asthmatic-like EAR and LAR following TMA aerosol challenge. This model may be useful for mechanism study of dermal exposure and asthma from low-molecular-weight chemicals.
Respiratory-irritants; Respiratory-system-disorders; Pulmonary-system-disorders; Hypersensitivity; Skin-absorption; Skin-exposure; Laboratory-animals
Disease and Injury: Asthma and Chronic Obstructive Pulmonary Disease
The Toxicologist. Society of Toxicology 42nd Annual Meeting and ToxExpo, Cutting-Edge Science, Networking, New Perspectives, March 9-13, 2003, Salt Lake City, Utah