Development and assessment of new risk assessment methods

Title of Research:
12_S01-03-3

Establishment of animal testing for the prediction of respiratory
sensitizing potential of chemicals
Principal Investigator:
Kohji Aoyama, PhD (Assistant Professor, Department of Hygiene and Health Promotion
Medicine, Graduate School of Medicine and Dental Sciences, Kagoshima University,)
8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan(tel)+81-99-275-5291 (e-mail) aoyama@m.kufm.kagoshima-u.ac.jp
Collaborators:
Hiroaki Kawaguchi (Associate Professor, Department of Pathology, Graduate School ofMedicine and Dental Sciences, Kagoshima University)
8-35-1 Sakuragaoka, Kagoshima, 890-8544, Japan(tel)+81-99-275-5263 (e-mail) k3038952@kadai.jp
Kunihiko Yamashita (Senior Researcher, Corporate Research Center, R & D Management,Daicel Corporation)
1239 Shinzaike, Aboshi-ku, Himeji, 671-1283, Japan(tel)+81-79-274-4061 (e-mail) ku_yamashita@daicel.jp
Tomoko Muto (Senior Researcher, Safety Research Division, Safety Research Institute for
Chemical Compounds Co.,LTD.)363-24 Shin-ei, Kiyota-ku, Sappro, 004-0839, Japan(tel)+81-11-885-5031 (e-mail) muto-tomoko@ka-anken.co.jp
Summary of Research:
The purpose of this project was to establish an animal model for predicting respiratory sensitizers
and for evaluating their relative respiratory sensitizing potency. To this end, we developed a
respiratory sensitization test using an intratracheal administration method in mice. The degree ofTh2 type-allergic response in the lungs was determined using allergic inflammation scores basedon histopathological grading. With this method, mice were sensitized with three concentrations ofa test substance 5 days per week for 3 weeks. Three days following the last administration, mice
were challenged with one concentration for three days, and were sacrificed 2 days later.
Next, we investigated the differences resulting from the different sensitization and elicitation
treatment regimens in order to determine conditions that cause obvious allergic reactions.
Interestingly, we found that allergic reactions tended to be reduced in mice sensitized with thehighest concentration of a test substance. Therefore, we examined the influence of lower
substance concentrations on eliciting responses based on the hypothesis that overdosing of thetest substances in the sensitization and elicitation treatments suppressed allergic reactions. We
also investigated the influence of the frequency of sensitization and elicitation treatments on thosereactions. We found that toluene diisocyanate (TDI) and trimellitic anhydride (TMA) elicited allergic
responses at lower concentrations than those of conventional elicitation. Additionally, both test
substances resulted in allergic inflammation scores that were greater than or equal to conventionalscores when eliciting concentrations were lower than those of conventional elicitation.
These results indicate that lower elicitation concentrations contributed to enhanced allergic
reactions in our model system, which could be used to obtain obvious inflammatory responses byexcluding primary irritation. Upon examining the influence of lowered sensitization and elicitation
treatment frequency on inflammatory responses, we found that multiple elicitation treatments wererequired similar to the conventional elicitation study design. we will proceed with detailed studies
to elucidate the influence of conditions such as frequency and duration on sensitization.
Timeline:
March 1, 2015 – February 29, 2016
Topics:Publications:3