759:
Urinary Prostaglandin D2 metabolite is an useful index of oral desensitization against food antigen in mice
Monday, March 5, 2018
South Hall A2 (Convention Center)
Takahisa Murata, DVM, PhD., Tatsuro Nakamura, DVM, PhD, Rina Hirai, Yuri Tachibana
RATIONALE: The development of food allergy largely depends on the intestinal mast cell number and its activation. Previously, we demonstrated that the urinary tetranor-PGDM (te-PGDM), a metabolite of prostaglandin D2, positively correlated with the number and activation of intestinal mast cells. In this study, we examined how the urinary level of te-PGDM change in oral desensitization against food antigen using murine model.

METHODS: Increasing dose of ovalbumin (OVA, 1~50 mg) was orally administrated to the OVA-sensitized BALB/c mice. The number of intestinal mast cell and its degranulation were determined in chloroacetate esterase stained sections. The urinary levels of te-PGDM were measured by using liquid chromatography-tandem mass spectronomy.

RESULTS: Until the 2nd 50 mg OVA challenge, oral food challenges exacerbated allergic manifestations including diarrhea and body temperature drop (exacerbating phase). After the 3nd 50 mg OVA challenge, the manifestations immediately ameliorated (desensitizing phase). The degranulation rate of intestinal mast cell was significantly reduced in the ameliorated phase compared with that in the exacerbated phase. Consistently, urinary te-PGDM level increase in the exacerbating phase, and decreased in the desensitizing phase. Of interest, urinary te-PGDM level tended to change prior to the change in manifestations.

CONCLUSIONS: Urinary te-PGDM can be an objective and non-invasive biomarker reflecting manifestations. It may be useful to monitor oral immunotherapy.