Cytokine responses to E. coli-induced epididymitis in the rat: blockade by vasectomy.

OBJECTIVES: To determine cytokine responses in rat epididymal tissues after retrograde Escherichia coli inoculation of the cauda epididymidis via the intact and obstructed vas deferens.
METHODS: Adult male Sprague-Dawley rats were divided into 3 groups: bilateral sham vasectomy followed by unilateral sham retrograde inoculation in the vas deferens (group A), bilateral sham vasectomy followed by unilateral retrograde inoculation of E. coli (group B), and bilateral vasectomy followed by left-sided inoculation of E. coli (group C). Three days later, the cauda epididymides and proximal vasa were subjected to histologic examination and assay for 9 cytokines.
RESULTS: Groups A and C showed no histologic evidence of epididymal inflammation. Group B had leukocyte infiltrates in the inoculated tissue. Cytokine levels in the injected cauda epididymides were low in groups A and C; however, interleukin (IL)-1α, IL-1β, and IL-4 were significantly increased in group B. The 6 other cytokines showed no significant change after E. coli infection though tumor necrosis factor-α, and IL-6 did show strong trends for increase. Contralateral epididymides never showed an inflammatory response.
CONCLUSIONS: Experimental epididymitis induced by retrograde movement of bacteria in the vas deferens results in different responses by different cytokines. The cytokine responses and the histologically evident inflammation are prevented by vasectomy.