Lack of thrombospondin-1 increases angiogenesis in a model of chronic inflammatory bowel disease.
OBJECTIVE
Vascular abnormalities and expression of pro-angiogenic factors are observed in inflammatory bowel diseases (IBD). In this study, the role of thrombospondin-1 (TSP-1), an antiangiogenic protein, was analyzed using the dextran sulfate sodium (DSS) model for IBD.


METHODS
Wild-type (WT) and thrombospondin-1-deficient (TSP-1(-/-)) mice were subjected to four cycles (7 days) of DSS. Basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), transforming growth factor beta 1 (TGFbeta-1), and pro-apoptotic proteins such as Fas and its ligand (FasL) were determined by enzyme-linked immunosorbent assay. Double immunohistochemistry for cluster of differential 31 (CD31) and panendothelial cell antigen-32 antibodies was performed for detecting blood vessels. The terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay was also performed for identifying apoptotic cells. Inflammation, dysplasia, microvascular density (MVD), apoptotic indices (AI), protein 53 (p53), and beta-catenin expression were determined.


RESULTS
VEGF and bFGF protein levels and MVD were higher in the TSP-1(-/-) mice (p = 0.0312, p = 0.0246, and p = 0.0085, respectively). AI in the endothelial cells (EC) and FasL levels were significantly lower in TSP-1(-/-) compared to WT mice (p = 0.0042 and p = 0.0362, respectively). Dysplasia was detected in 66% of TSP-1(-/-) mice compared to 14% in WT mice. Hscores of ss-catenin and areas overexpressing p53 were higher in TSP-1(-/-) mice (p = 0.0002 and p = 0.0339, respectively).


CONCLUSIONS
TSP-1 may decrease angiogenesis by reducing the levels of pro-angiogenic factors and inducing apoptosis in EC through the Fas or FasL pathway. These findings, along with the increased overexpression of p53 and beta-catenin in TSP-1(-/-) mice, underline its role in carcinogenesis.
Zak
Samantha
S
Department of Biology, Wilkes University, Wilkes-Barre, PA, USA.
Treven
John
J
Nash
Nolly
N
Gutierrez
Linda S
LS
D000818:Animals; D017209:Apoptosis; D015415:Biomarkers / Q000378:metabolism; D002908:Chronic Disease; D003093:Colitis, Ulcerative / Q000378:metabolism / Q000473:pathology*; D003106:Colon / Q000098:blood supply*; D004195:Disease Models, Animal; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay; D053222:Fas Ligand Protein / Q000096:biosynthesis; D016222:Fibroblast Growth Factor 2 / Q000096:biosynthesis; D020287:In Situ Nick-End Labeling; D051379:Mice; D008810:Mice, Inbred C57BL; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000473:pathology*; D011379:Prognosis; D019700:Thrombospondin 1 / Q000096:biosynthesis / Q000172:deficiency*; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis; D051176:beta Catenin / Q000096:biosynthesis
D015415:Biomarkers; D053222:Fas Ligand Protein; D019700:Thrombospondin 1; D016159:Tumor Suppressor Protein p53; D042461:Vascular Endothelial Growth Factor A; D051176:beta Catenin; D016222:Fibroblast Growth Factor 2