Fibrogenic signals in patients with radiation enteritis are associated with increased connective tissue growth factor expression.
OBJECTIVE
To investigate the expression of a new fibrogenic cytokine the connective tissue growth factor (CTGF) in intestinal radiation fibrosis and to characterize the mesenchymal cell subtypes involved in CTGF synthesis and collagen deposition.


METHODS
Sixteen patients with radiation enteritis that occurred after radiotherapy for pelvic malignancies and 6 with histologically normal bowel entered the study. Immunohistochemistry, Western blot analysis, and real-time reverse transcriptase-polymerase chain reaction were performed to study CTGF expression, along with other known markers of radiation fibrosis: the pro-fibrogenic cytokine transforming growth factor (TGF)-beta1 and phenotypic markers of the fibroblast differentiation the alpha-sm actin (A), vimentin (V), and desmin (D). Finally, the collagen accumulation was measured by Sirius red staining and colorimetric assay.


RESULTS
Radiation enteritis was characterized by increased collagen content within the intestinal wall. CTGF immunoreactivity, protein, and mRNA level were increased in radiation enteritis compared with the healthy bowel. On the contrary, no increase of the TGF-beta1 mRNA level was observed in radiation enteritis compared with healthy bowel, and the level of TGF-beta protein was slightly increased in radiation enteritis. A co-localization of CTGF immunoreactivity and collagen deposition was found in the extracellular matrix and subtypes of activated mesenchymal cells with a fibroblast phenotype (V(+)/D(-)/A(-)) and myofibroblast phenotype (V(+)/D(-/+)/A(+)).


CONCLUSIONS
The increased level of CTGF protein and mRNA associated with the accumulation of fibroblasts/myofibroblasts and collagen deposition were parts of the fibrogenic signals involved in the persistence of late intestinal radiation fibrosis.
Laboratoire UPRES EA 27-10 Radiosensibilité des tumeurs et tissus sains, Institut Gustave Roussy/Institut de Radioprotection et de Sureté Nucléaire, Villejuif, France. vozenin@igr.fr
Marie Catherine
MC
Vozenin-Brotons
Fabien
F
Milliat
Jean Christophe
JC
Sabourin
Anne Charlotte
AC
de Gouville
Agnès
A
François
Philipe
P
Lasser
Philipe
P
Morice
Christine
C
Haie-Meder
Antoine
A
Lusinchi
Sami
S
Antoun
Jean
J
Bourhis
Denis
D
Mathé
Theo
T
Girinsky
Jocelyne
J
Aigueperse
D000328:Adult; D000368:Aged; D015415:Biomarkers; D015152:Blotting, Northern; D003094:Collagen; D055513:Connective Tissue Growth Factor; D004751:Enteritis / Q000378:metabolism*; D005260:Female; D005347:Fibroblasts; D005355:Fibrosis / Q000378:metabolism; D006801:Humans; D017874:Immediate-Early Proteins / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D011832:Radiation Injuries / Q000378:metabolism*
D015415:Biomarkers; C526317:CCN2 protein, human; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D055513:Connective Tissue Growth Factor; D003094:Collagen