LOCAL EXPRESSION OF CYTOKINE MESSENGER-RNA IN RAT MODEL OF ESCHERICHIA-COLI EPIDIDYMITIS

Purpose: In order to investigate whether cytokines play an important r ole in the regulation of host defense against bacterial epididymitis, we examined the local expression of cytokine mRNA in a rat model of Es cherichia coli epididymitis. Materials and Methods: Escherichia coli w as inoculated into the spermatic cord of the rats and provoked epididy mitis. At 6, 12, 24, 48, and 72 hours postinfection (p.i.) epididymide s were harvested. We examined interleukin-6 (IL-6) and other inflammat ory cytokine mRNAs in epididymides by Northern blotting and reverse tr anscriptase polymerase chain reaction (RT-PCR). Histopathological find ings and immunohistochemistry for IL-6 were also examined. Results: In fected epididymides expressed IL-6 mRNA maximally at 6 hours p.i. and then the signal decreased by Northern blotting. mRNA for IL-1 beta and TNF-alpha also increased within 6 hours by RT-PCR. Histopathological examination showed that no inflammatory cells were observed at 6 hours p.i. and that inflammatory changes were most prominent at 72 hours p. i. Epididymal epithelium expressed IL-6 locally in response to local b acterial infection by immunohistochemistry. Conclusions: mRNA for IL-1 beta, IL-6, and TNF-alpha is expressed locally in response to bacteri al infection before inflammatory cell infiltration. This rapid express ion in the epithelial cells may be important in host defense to local genital infection.