Cytokines induce an epithelial cell cytokine response

Intravesical inoculation of gram negative bacteria or isolated bacterial products into mice induces an IL-6 response which can be measured within miutes of the infection.1,2 In such infections, IL-6 is initially detected in the urine and subsequently in the serum. Similar IL-6 responses were found in human patients deliberately colonized in the urinary tract with E. coli Hu7343. IL-6 was secreted intermittantly into the urine in response to continuous bacterial infection in humans, but was not detected in serum. The rapid secretion of IL-6 into urine after bacterial stimulation, and the separation of local from systemic secretion in both humans and mice suggested that IL-6 was produced at the site of infection. Since epithelial cells dominate the naive urinary tract mucosal surface, we suggested that epithelial cells are one source of mucosally produced cytokines.4 Epithelial cell lines of urinary tract origin secrete IL-6 and IL-8, and can produce other cytokines after bacterial stimulation.5–7 In this paper we demonstrate that epithelial cell lines of urinary tract origin can respond to exogenous cytokines. This response includes the up-regulation of a variety of cytokine mRNA species as well as secretion of IL-6 and IL-8. Furthermore, this response is specific to the stimulus used, with different cytokine mRNA species induced by different cytokine stimuli