Transcriptional and translational regulation of IL-1 alpha and IL-1 beta account for the control of IL-1 in experimental yersiniosis.

Interleukin 1 (IL-1) gene expression was investigated in mice following oral infection with Yersinia enterocolitica 08. In Peyer's patches (PP), the primary site of bacterial invasion, induction of IL-1 alpha mRNA was delayed when compared to IL-1 beta mRNA. As shown by in situ hybridization. IL-1 alpha and IL-1 beta mRNA were found to be expressed within different cell types. These results indicate that expression of the two forms of IL-1 is regulated in a cell-specific manner at the transcriptional level. Moreover, IL-1 (alpha and beta) mRNA was increased in other organs such as spleen and lung. In spleens, IL-1 beta mRNA was found within the red pulp, and IL-1 alpha mRNA was located to the marginal zone confirming that differential expression of IL-1 alpha and IL-1 beta mRNA does not represent a tissue-specific event. However, as revealed by immunohistochemistry and measuring IL-1 activity in tissue homogenates, synthesis of IL-1 proteins was not detectable in spleens, unless mice were challenged with LPS. Because IL-1 synthesis was inducible in spleen cells following actinomycin D treatment, the results indicate that at distant sites of infection IL-1 (alpha and beta) mRNA is expressed but not translated into protein. It is concluded that cell-specific transcription of IL-1 alpha and IL-1 beta as well as dissociation between IL-1 mRNA and protein synthesis are two mechanisms effective in regulating the production of IL-1 during infection.