Transcriptional analysis of the IL‐33 receptor suppression of tumourigenicity 2 and its effects on canine Type 2 T helper cells: a preliminary study

BACKGROUND: Interleukin (IL)-33 has been implicated in the pathogenesis of canine atopic dermatitis, a Type 2 T helper cell (Th2)-associated disease. In humans, IL-33 mediates its biological effects through the receptor suppression of tumourigenicity 2 (ST2), which is preferentially expressed on Th2 cells. The effects of IL-33 on canine Th2 cells are unclear. HYPOTHESIS/OBJECTIVES: ST2 may be preferentially expressed on canine Th2 cells; IL-33 may induce the transcription of Th2 cytokines from these cells. ANIMALS: Three healthy dogs were used. METHODS: The transcription level of st2 was quantified in helper T cells, cytotoxic T cells and Th2 cells isolated from healthy dogs. The transcription levels of Th2 cytokines including il-4, il-5, il-13 and il-31 were quantified in Th2 cells stimulated with recombinant canine (rc) IL-33 and/or recombinant human (rh) IL-2. RESULTS: Transcription of st2 was the strongest in Th2 cells. Th2 cells also transcribed the genes for il-5 and il-13 after being stimulated with rcIL-33 and rhIL-2. CONCLUSIONS AND CLINICAL IMPORTANCE: These results indicate that canine Th2 cells activated by IL-33 enhance Th2-mediated inflammation through the production of IL-5 and IL-13.