Development of IL-17-mediated delayed-type hypersensitivity is not affected by down-regulation of IL-25 expression.

BACKGROUND: IL-25, which is a member of the IL-17 family, induces Th2 cell differentiation and Th2 cytokine production, contributing to induction of Th2-type immune responses and diseases, as a result of which it suppresses Th1- and Th17-type immune responses. METHODS: To elucidate the role of IL-25 in the pathogenesis of IL-17-mediated delayed-type hypersensitivity (DTH), IL-25-deficient mice were sensitized with methylated BSA (mBSA), and then a DTH reaction was induced by mBSA challenge. mBSA-specific T-cell induction was assessed on the basis of cell proliferation and cytokine production. The DTH reaction was evaluated on the basis of tissue swelling, histology and inflammatory mediator expression. RESULTS: IL-25 expression was markedly reduced in local DTH lesions. However, mBSA-specific Th1, Th2 and Th17 cell induction, and the mBSA-induced DTH reaction were comparable in IL-25-deficient and wild-type mice. CONCLUSIONS: IL-25 is not essential for differentiation of Th1, Th2 and Th17 cells in the sensitization phase or induction of local inflammation in the elicitation phase of the mBSA-induced DTH reaction.

Differentiation of Trichophyton rubrum clinical isolates from Japanese and Chinese patients by randomly amplified polymorphic DNA and DNA sequence analysis of the non-transcribed spacer region of the rRNA gene.

BACKGROUND: Trichophyton rubrum is the most common pathogen causing dermatophytosis worldwide. Recent genetic investigations showed that the microorganism originated in Africa and then spread to Europe and North America via Asia. OBJECTS: We investigated the intraspecific diversity of T. rubrum isolated from two closely located Asian countries, Japan and China. METHODS: A total of 150 clinical isolates of T. rubrum obtained from Japanese and Chinese patients were analyzed by randomly amplified polymorphic DNA (RAPD) and DNA sequence analysis of the non-transcribed spacer (NTS) region in the rRNA gene. RESULTS: RAPD analysis divided the 150 strains into two major clusters, A and B. Of the Japanese isolates, 30% belonged to cluster A and 70% belonged to cluster B, whereas 91% of the Chinese isolates were in cluster A. The NTS region of the rRNA gene was divided into four major groups (I-IV) based on DNA sequencing. The majority of Japanese isolates were type IV (51%), and the majority of Chinese isolates were type III (75%). CONCLUSIONS: These results suggest that although Japan and China are neighboring countries, the origins of T. rubrum isolates from these countries may not be identical. These findings provide information useful for tracing the global transmission routes of T. rubrum.