Influence of 5-fluorouracil on colonic healing and expression of transforming growth factor-beta 1.

BACKGROUND: Administration of chemotherapeutic agents in the immediate postoperative period may have beneficial effects by decreasing local cancer recurrence rates, but this must be weighed against possible impairment of wound healing. Since local expression of transforming growth factor-beta1 (TGF-beta1) is normally upreglated following creation of experimental colonic anastomoses, this study examines the effects of 5-fluorouracil (5-FU) on colonic healing and on the local expression of TGF-beta1. MATERIALS AND METHODS: Forty-eight male Sprague-Dawley rats underwent transection of the descending colon with primary anastomosis and were then randomly assigned to receive either intraperitoneal 5-FU (20 mg/kg/day) or saline (SAL). On Postoperative Days (PODs) 3, 5, and 7, bursting pressure (BP, mm Hg) and bursting energy (BE, mm Hg xs) were determined in situ. Anastomotic and nonoperated segments of colon were harvested and analyzed using the semiquantitative reverse transcriptase-polymerase chain reaction to determine the relative expression of TGF-beta1 normalized to that of a constitutive gene. RESULTS: Progressive increases in BP and BE were observed in both the 5-FU and the SAL groups, across the time course examined. Overall, these measures were decreased in the 5-FU groups compared to SAL, significantly so on PODs 5 and 7; BP, 127.8 +/- 7.6 vs 161.1 +/- 7.2 and 139.9 +/- 10.9 vs 186.0 +/- 8.6; BE, 1093.6 +/- 190.0 vs 2207.9 +/- 308.2, and 1518.5 +/- 326.5 vs 3279.3 +/- 225.7, respectively. Anastomotic TGF-beta1 expression also increased progressively in both groups over the postoperative time course. Expression in the 5-FU group, however, was significantly decreased compared to that in the SAL group on POD 3; 0.42 +/- 0.05 vs 0.84 +/- 0.04. Interestingly, this preceded the reduction in BP and BE in the 5-FU group on PODs 5 and 7. TGF-beta1 expression in nonoperated colonic segments did not change during the time points studied or in response to 5-FU administration. CONCLUSIONS: Wound healing following a colonic anastomosis is associated with local increases in TGF-beta1 expression, which in turn is diminished by the administration of 5-FU. If this deleterious effect on wound healing could be counteracted, then chemotherapy administration in the immediate postoperative period may become safer.

Temporal expression of TGF-beta1, 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-beta1) gene has been shown to be temporally associated with expression of the procollagen gene. This study examines the temporal expression of the TGF-beta1, 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-beta1, 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 all three of the PGFs genes were expressed in healing postoperative colonic tissue, only TGF-beta1 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-beta1 gene (r = 0.89, P < 0.05). CONCLUSIONS: The temporal correlation between an increase in the gene expression of TGF-beta1 and PROC I is initial evidence that that TGF-beta1 plays a significant role in collagen metabolism in a healing colonic anastomosis.

Effect of bowel preparation and a fiber-free liquid diet on expression of transforming growth factor and procollagen in colonic tissue preoperatively and postoperatively.

PURPOSE: Dehiscence of colonic anastomoses is prevalent and potentially fatal. In an attempt to reduce the likelihood of anastomotic dehiscence, the colon is cleansed before surgery and fiber-free diets are prescribed postoperatively. However, fiber-free diets induce colonic atrophy and impair healing. This study was designed to investigate the effect of bowel preparation and postoperative fiber-free diet on the local gene expression of transforming growth factor-beta 1 and procollagen type I. METHODS: Four Sprague-Dawley rats underwent bowel preparation with a fiber-free liquid diet and polyethylene glycol in a balanced electrolyte solution for two days (fiber-free preoperative diet group), whereas four rats received standard chow with fiber (preoperative diet with fiber group). On the third day tissue was obtained from the descending colon of each rat to assess the effect of bowel preparation. Forty additional rats had their bowels prepared and underwent transection of the descending colon and anastomosis. These rats were then randomly assigned to continue on the liquid diet (fiber-free postoperative diet group) or rat chow (postoperative diet with fiber group). On postoperative days 3, 5, 6, 7, and 14, colonic tissue was obtained from the anastomosis and analyzed with the use of semiquantitative reverse transcriptase-polymerase chain reaction to examine the relative expression of transforming growth factor-beta 1 and procollagen type I genes normalized to that of a constitutive gene. RESULTS: There was a decrease in the expression of the transforming growth factor-beta 1 and the procollagen type I genes in the fiber-free preoperative diet group compared with the preoperative diet with fiber group; however, this difference only reached statistical significance for procollagen type I. Postoperatively, significant increases in the expression of the transforming growth factor-beta 1 and procollagen type I genes over baseline levels were observed around postoperative day 7 in both groups, which temporally correlates with active phases of collagen deposition in the wounded colon. Expression of the procollagen type I gene, however, was significantly decreased at this time in the fiber-free postoperative diet group compared with the postoperative diet with fiber group. CONCLUSION: Although necessary to reduce septic complications, preoperative bowel preparation has a detrimental effect on the expression of transforming growth factor-beta 1 and procollagen type I. A postoperative fiber-free liquid diet also may be detrimental to the expression of these transcripts in the bowel. Alternative methods for delivery of colonic fuels are needed to create a better environment for colonic healing while eliminating bacteria and bulk.