Local radiotherapy of exposed murine small bowel: apoptosis and inflammation.
BACKGROUND
Preoperative radiotherapy of the pelvic abdomen presents with complications mostly affecting the small bowel. The aim of this study was to define the features of early radiation-induced injury on small bowel.


METHODS
54 mice were divided into two groups (36 irradiated and 18 sham irradiated). Animals were placed on a special frame and (in the radiated group) the exteriorized segment of ileum was subjected to a single absorbed dose of 19 or 38 Gy radiation using 6 MV high energy photons. Specimens were collected for histology, immunohistochemistry (IHC) and ELISA analysis after 2, 24 and 48 hours. Venous blood was collected for systemic leucocyte count in a Burker chamber.


RESULTS
Histology demonstrated progressive infiltration of inflammatory cells with cryptitis and increased apoptosis. MIP-2 (macrophage inflammatory protein) concentration was significantly increased in irradiated animals up to 48 hours. No significant differences were observed in IL-10 (interleukin) and TNF-alpha (tumour necrosis factor) levels. IHC with CD45 showed a significant increase at 2 hours of infiltrating leucocytes and lymphocytes after irradiation followed by progressive decrease with time. Caspase-3 expression increased significantly in a dose dependent trend in both irradiated groups up to 48 hours.


CONCLUSIONS
Acute small bowel injury caused by local irradiation is characterised by increased apoptosis of crypt epithelial cells and by lymphocyte infiltration of the underlying tissue. The severity of histological changes tends to be dose dependent and may affect the course of tissue damage.
Polistena
Andrea
A
Department of Surgery, Malmö University Hospital, Lund University, Malmö, Sweden. apolis74@yahoo.it
Johnson
Louis Banka
LB
Ohiami-Masseron
Salomé
S
Wittgren
Lena
L
Bäck
Sven
S
Thornberg
Charlotte
C
Gadaleanu
Virgil
V
Adawi
Diya
D
Jeppsson
Bengt
B
D000818:Animals; D017209:Apoptosis; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D007082:Ileum / Q000503:physiopathology / Q000528:radiation effects* / Q000601:surgery; D007249:Inflammation / Q000473:pathology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011833:Radiation Injuries, Experimental