Temporal expression of TGF-β1, EGF, and PDGF-BB in a model of colonic wound healing

Background. Dehiscence of colonic anastomoses is a multifactorial phenomenon. One mechanism by which this can occur is a deficiency of colonic submucosal collagen. Peptide growth factors (PGFs) have been shown to play a role in the synthesis, deposition, and maturation of collagen, Specifically, in tissues other than the colon, the transforming growth factor-beta (TGF-beta(1)) gene has been shown to be temporally associated with expression of the procollagen gene. This study examines the temporal expression of the TGF-beta(1), epidermal growth factor (EGF), and platelet-derived growth factor B (PDGF-BB) genes and their temporal relationship to the expression of the procollagen type 1 (PROC I)gene, Materials and methods. Forty-eight Sprague-Dawley rats underwent transection of the descending colon with primary anastomosis. Perianastomotic colonic tissue was harvested on Day 0 and postoperative days 3, 5, 6, 7, and 14, Colonic tissue was analyzed using semiquantitative reverse transcriptase-polymerase chain reaction and primers specific for the TGF-beta(1), EGF, and PDGF-B growth factors. Relative expression ratios of PGFs and PROC I genes were calculated versus a constitutive gene. Results. The data show that although an, three of the PGFs genes were expressed in healing postoperative colonic tissue, only TGF-beta(1) showed a significant increase in its level of expression versus a constitutive gene from a mean ratio of 0.4 +/- 0.08 on Day 0 to a mean ratio of 1.9 +/- 0.27 on Day 7 (P < 0.0001 by ANOVA). The PROC I gene also showed a significant increase in expression (P < 0.001 by ANOVA) in the postoperative period which temporally correlated with the increase in the expression of the TGF-beta(1) gene (r = 0.89, P < 0.05). Conclusions. The temporal correlation between an increase in the gene expression of TGF-beta(1) and PROC I is initial evidence that that TGF-beta(1) plays a significant role in collagen metabolism in a healing colonic anastomosis. (C) 1998 Academic Press.