Micronucleus frequencies in urothelial cells of catheterized patients with chronic bladder inflammation.

Epidemiological studies suggest an association between chronic inflammation and increased risk for cancer, although the mechanism underlying this relationship is unresolved. In the present study, we test the hypothesis that DNA damage is induced in the epithelium of tissues during such inflammation by products of activated inflammatory cells. Individuals on long-term indwelling urinary catheterization were used as a study population. These individuals have chronic bladder inflammation and, as a population, an increased risk for bladder cancer. Urine of 29 patients and 26 age-matched non-catheterized controls was collected and micronucleus (MN) frequencies were determined in exfoliated urothelial cells in the urinary sediments. The urine from the catheterized group had large numbers of white blood cells (mean count, 26.6 +/- 3.6 cells per high-power field), indicating the presence of a chronic bladder infection and an inflammatory reaction. In contrast, white blood cells were not present in urine from individuals in the control group. There was no significant difference in MN frequencies in the 2 groups (mean frequencies, controls: 0.098 +/- 0.030%; catheterized: 0.140 +/- 0.025%, p = 0.13). These data imply that chromosomal damage does not always occur during chronic inflammation. Although the reasons for this observation are yet to be determined, possible explanations include the pathophysiology of the inflammatory reaction and the influence of vitamins, non-steroidal anti-inflammatory drugs and the catheter itself in protection against inflammatory cell-mediated DNA damage.