Radiation-induced variations in urothelial expression of intercellular adhesion molecule 1 (ICAM-1): association with changes in urinary bladder function.
OBJECTIVE
To assess the effect of single-dose irradiation on intercellular adhesion molecule 1 (ICAM-1) expression in the urothelium of mouse urinary bladder and to correlate ICAM-1 variations with fluctuations in storage capacity during the early and late radiation response.


METHODS
Groups of female C3H mice were subjected to irradiation with either 20 or 0 Gy. The intensity of immunohistochemical ICAM-1 staining in the urothelium was assessed in a semiquantitative way applying an arbitrary score (0-5). Changes in bladder storage function were assessed by transurethral cystometry.


RESULTS
For the early radiation response phase, a reduction in bladder capacity by >50%, i.e. a positive functional radiation response, was seen in 40% of the irradiated animals between days 0 and 15, and in 64% of animals during days 16-30. During the late response phase, 71% of the animals sacrificed after day 180 developed a positive functional response. Urothelial cells were found to express ICAM-1 constitutively. Irradiation resulted in an early rise in staining signal by day 2, with a maximum on day 4 and a return to control values on day 13. A permanent increase in ICAM-1 staining signal was observed in the late phase, from day 90 to 360 after irradiation. The expression of ICAM-1 in animals with a positive late response was 4.2+/-1.2 (mean+/-standard deviation), compared with 2.6+/-1.0 in non-responders (p=0.0009).


CONCLUSIONS
Irradiation induces significant acute and chronic changes in urothelial ICAM-1 expression indicating that the urothelium contributes to the pathogenesis of both acute and late radiation effects in the urinary bladder.
Jaal
J
J
Klinik und Poliklinik für Strahlentherapie und Radioonkologie, Medizinische Fakultät Carl Gustav Carus der Technischen Universität, D-01307 Dresden, Germany. Jana.Jaal@kliinikum.ee
Brüchner
K
K
Hoinkis
C
C
Dörr
W
W
D000818:Animals; D004307:Dose-Response Relationship, Radiation; D005260:Female; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D051379:Mice; D008809:Mice, Inbred C3H; D011829:Radiation Dosage; D013223:Statistics as Topic; D001743:Urinary Bladder / Q000502:physiology* / Q000528:radiation effects*; D019459:Urothelium / Q000378:metabolism* / Q000528:radiation effects*
D018799:Intercellular Adhesion Molecule-1