Vitamin A deficiency impairs colonic healing but not adhesion formation in germ-free and conventional rats

Mucosal healing in inflammatory bowel diseases: is there a place for nutritional supplementation?

Advanced mucosal healing (MH) after intestinal mucosal inflammation coincides with sustained clinical remission and reduced rates of hospitalization and surgical resection, explaining why MH is increasingly considered as a full therapeutic goal and as an endpoint for clinical trials. Intestinal MH is a complex phenomenon viewed as a succession of steps necessary to restore tissue structure and function. These steps include epithelial cell migration and proliferation, cell differentiation, restoration of epithelial barrier functions, and modulation of cell apoptosis. Few clinical studies have evaluated the needs for specific macronutrients and micronutrients and their effects on intestinal MH, most data having been obtained from animal and cell studies. These data suggest that supplementation with specific amino acids including arginine, glutamine, glutamate, threonine, methionine, serine, proline, and the amino acid-derived compounds, polyamines can favorably influence MH. Short-chain fatty acids, which are produced by the microbiota from undigested polysaccharides and protein-derived amino acids, also exert beneficial effects on the process of intestinal MH in experimental models. Regarding supplementation with lipids, although the effects of ω-3 and ω-6 fatty acids remain controversial, endogenous prostaglandin synthesis seems to be necessary for MH. Finally, among micronutrients, several vitamin and mineral deficiencies with different frequencies have been observed in patients with inflammatory bowel diseases and supplementation with some of them (vitamin A, vitamin D3, vitamin C, and zinc) are presumed to favor MH. Future work, including clinical studies, should evaluate the efficiency of supplementation with combination of dietary compounds as adjuvant nutritional intervention for MH of the inflamed intestinal mucosa.

High incidence of LRAT promoter hypermethylation in colorectal cancer correlates with tumor stage

Lecithin:retinol acyltransferase (LRAT) is a major enzyme involved in vitamin A/retinol metabolism, which regulates various physiological processes like cell proliferation and differentiation. LRAT expression is reduced in numerous cancers, yet the underlying mechanisms have remained undefined. We hypothesized that methylation silencing may contribute to decreased LRAT gene expression in colorectal cancer (CRC). LRAT hypermethylation status was analyzed in five CRC cell lines, 167 colorectal tumors, and 69 adjacent normal colonic mucosae, using a quantitative bisulfite/PCR/LDR/Universal Array assay. LRAT transcription levels were determined by real-time RT-PCR in a subset of tumors and matched normal tissues and in CRC cell lines that were treated with a demethylating agent, 5-aza-2'-deoxycytidine. The incidence of LRAT hypermethylation was significantly higher in colorectal tumors than in adjacent normal mucosae (p = 0.0025). Aberrant methylation occurred in 51 % of microsatellite-stable CRCs, in 84 % of microsatellite-unstable CRCs, and in 12 out of 13 colonic polyps. The number of hypermethylated LRAT events was inversely correlated with CRC stage (p < 0.0001). Importantly, LRAT hypermethylation was associated with decreased mRNA level in CRC clinical specimens, and demethylation treatment resulted in LRAT transcriptional reactivation. Our data support the idea that LRAT promoter hypermethylation associates with LRAT gene expression in CRC. The higher frequency of LRAT hypermethylation in colonic polyps and early-stage CRCs indicates that it may occur early in malignant progression.

Effects of Simultaneous Hepatic Resection on Healing of Left-Sided Colonic Anastomoses: An Experimental Study in Rats

BACKGROUND

A combined colorectal and hepatic resection is considered too risky by many surgeons owing to the high risk of postoperative septic complications. The aim of the present study was to investigate the effects of hepatic resection on the healing of left-sided colonic anastomoses in rats on postoperative day 7.

MATERIAL AND METHODS

Fifty-four Sprague-Dawley rats were block-randomized into three groups. In each group, 1 cm of the left side of the colon was resected and anastomosed. Additionally, 40 or 70% of the liver was resected in group 2 and 3, respectively. Rats were killed on postoperative day 7. The abdominal cavity was inspected for the presence of complications. The bursting pressure and hydroxyproline content of the anastomoses were measured.

RESULTS

The total number of complications was significantly higher in group 3 than in group 2. Anastomotic bursting pressure and hydroxyproline content did not differ significantly among the groups.

CONCLUSIONS

Increasing the extent of simultaneous hepatic resection did not significantly affect the healing of left-sided colonic anastomoses in rats on postoperative day 7, although there was a tendency towards lower bursting pressure paralleling the extent of liver resection. Excessive hepatic resection with colectomy may increase postoperative complications.

Orally delivered antibiotics which lower bacterial numbers decrease experimental intra-abdominal adhesions

BACKGROUND

Postsurgical adhesion formation is a common occurrence after most surgical procedures and is still a major cause of postoperative morbidity because no satisfactory treatment or prophylaxis has yet been developed. Further elucidation of the basic mechanisms of postsurgical adhesion formation is needed. Recent studies using germfree rats have found the indigenous bowel flora to be important in the adhesive response. The present study examined whether antibiotic treatment affects intra-abdominal adhesion formation.

METHODS

Using the cecal crush model to inflict adhesions, groups of rats ( n=12) were treated with placebo or amoxicillin/clavulanic acid in the drinking water. Treatment started 3 days before operation and continued until evaluation. Adhesion scores were recorded after 7 days. Bacterial counts were made from cultures of fecal samples on operation day and at termination.

RESULTS

Amoxicillin/clavulanic acid decreased adhesion score compared to placebo. Adhesion incidence was 50% in the treatment group and 92% in the placebo group. Bacterial numbers were lower in the treatment group.

CONCLUSIONS

Antibiotic treatment which lowers bacterial numbers can decrease adhesions.