Fecal water as a non-invasive biomarker in nutritional intervention: comparison of preparation methods and refinement of different endpoints

The assessment of cellular effects by the aqueous phase of human feces (fecal water, FW) is a useful biomarker approach to study cancer risks and protective activities of food. In order to refine and develop the biomarker, different protocols of preparing FW were compared. Fecal waters were prepared by 3 methods: (A) direct centrifugation; (B) extraction of feces in PBS before centrifugation; and (C) centrifugation of lyophilized and reconstituted feces. Genotoxicity was determined in colon cells using the Comet assay. Selected samples were investigated for additional parameters related to carcinogenesis. Two of 7 FWs obtained by methods A and B were similarly genotoxic. Method B, however, yielded higher volumes of FW, allowing sterile filtration for long-term culture experiments. Four of 7 samples were non-genotoxic when prepared according to all 3 methods. FW from lyophilized feces and from fresh samples were equally genotoxic. FWs modulated cytotoxicity, paracellular permeability, and invasion, independent of their genotoxicity. All 3 methods of FW preparation can be used to assess genotoxicity. The higher volumes of FW obtained by preparation method B greatly enhance the perspectives of measuring different types of biological parameters and using these to disclose activities related to cancer development.

Dietary synbiotics reduce cancer risk factors in polypectomized and colon cancer patients

BACKGROUND

Animal studies suggest that prebiotics and probiotics exert protective effects against tumor development in the colon, but human data supporting this suggestion are weak.

OBJECTIVE

The objective was to verify whether the prebiotic concept (selective interaction with colonic flora of nondigested carbohydrates) as induced by a synbiotic preparation-oligofructose-enriched inulin (SYN1) + Lactobacillus rhamnosus GG (LGG) and Bifidobacterium lactis Bb12 (BB12)-is able to reduce the risk of colon cancer in humans.

DESIGN

The 12-wk randomized, double-blind, placebo-controlled trial of a synbiotic food composed of the prebiotic SYN1 and probiotics LGG and BB12 was conducted in 37 colon cancer patients and 43 polypectomized patients. Fecal and blood samples were obtained before, during, and after the intervention, and colorectal biopsy samples were obtained before and after the intervention. The effect of synbiotic consumption on a battery of intermediate bio-markers for colon cancer was examined.

RESULTS

Synbiotic intervention resulted in significant changes in fecal flora: Bifidobacterium and Lactobacillus increased and Clostridium perfringens decreased. The intervention significantly reduced colorectal proliferation and the capacity of fecal water to induce necrosis in colonic cells and improve epithelial barrier function in polypectomized patients. Genotoxicity assays of colonic biopsy samples indicated a decreased exposure to genotoxins in polypectomized patients at the end of the intervention period. Synbiotic consumption prevented an increased secretion of interleukin 2 by peripheral blood mononuclear cells in the polypectomized patients and increased the production of interferon gamma in the cancer patients.

CONCLUSIONS

Several colorectal cancer biomarkers can be altered favorably by synbiotic intervention.

Human fecal water inhibits COX-2 in colonic HT-29 cells: role of phenolic compounds

The inducible enzyme cyclooxygenase-2 (COX-2) plays a major role in the regulation of inflammation and possibly in the development of colon cancer. The aim of the present study was to screen for COX-2 inhibitors in samples of fecal water (the aqueous phase of feces) and investigate whether phenolic compounds are responsible for any observed effects on COX-2. Volunteers (n = 20) were recruited and asked to supply a 24-h stool sample. Fecal water samples were prepared and analyzed by GC-MS for their content of phenolic compounds. These samples were also evaluated for their effects on COX-2 protein levels (Western blot) and prostaglandin (PG)E2 production in tumor necrosis-alpha-stimulated HT-29 cells and pure enzymatic activity in a COX-2-catalyzed prostaglandin biosynthesis in vitro assay. The major phenolic compounds identified were phenylpropionic acid, phenylacetic acid, cinnamic acid, and benzoic acid derivatives. Of 13 fecal water samples analyzed, 12 significantly decreased PGE2 production (range 5.4-39.7% inhibition, P-value < 0.05) compared with control cells and 13 of 14 samples analyzed decreased COX-2 protein levels in HT-29 cells (19-63% inhibition). Of the 20 fecal water samples, 2 also weakly inhibited enzymatic activity of purified COX-2 (22-24% inhibition). Three compounds identified in fecal water, 3-phenylpropionic acid, 3-hydroxyphenylacetic acid, and 3-(4-hydroxyphenyl)-propionic acid, decreased the protein level at 250 micromol/L (15-62% inhibition). This study shows for the first time that human fecal water contains components that can affect both the COX-2 protein level and enzymatic activity.

Polyethylene glycol reduces inflammation and aberrant crypt foci in carcinogen-initiated rats

Polyethylene glycol 8000 inhibits the formation of tumors and of aberrant crypt foci (ACF) in carcinogen-initiated rats. We asked: is the inhibition associated with a reduction of colonic inflammation and an increase in colonic cell permeability? Twenty-eight, male F 344 rats were divided into two groups, 10 control animals and 18 animals initiated with azoxymethane. Nine of the rats in the carcinogen-initiated group were given a diet with 5% PEG 8000 in an AIN-93 based, high fat diet. The other nine, and the control group received the diet without the addition of PEG. Nine weeks later, the rats receiving the diet containing PEG had a 43% reduction in ACF (P<0.001) compared with the carcinogen-initiated rats on the control diet, a result confirming earlier observations that PEG inhibits colon carcinogenesis. The animals receiving the diet containing PEG also had a 10-fold reduction in fecal granulocyte marker protein (GMP) (P<0.001) compared with both the carcinogen-treated and the control animals. PEG reduced inflammation below the levels of carcinogen-treated and of untreated animals. Fecal water from the rats receiving PEG did not reduce transepithelial resistance of, or manitol flux through, human Caco-cells grown as monolayers in vitro. PEG may reduce colon carcinogenesis through a mechanism involving colonic inflammation.

Effects on cell proliferation, activator protein-1 and genotoxicity by fecal water from patients with colorectal adenomas

BACKGROUND

The free water phase of feces (fecal water) may mediate the effects of diet on colon carcinogenesis. We examined the effects of fecal water from adenoma patients and controls on three parameters in colonocytes believed to be relevant to tumorigenesis, i.e. genotoxicity in intact cells and on isolated DNA, proliferative activity and activator protein-1 (AP-1) activity.

METHODS

Genotoxicity in intact colonic cells was assayed using the single-cell gel electrophoresis assay ('comet' assay) and on isolated DNA using double-stranded DNA from the X-174 RF plasmid. Cell proliferation was assessed using the commercially available 'alamar blue' proliferation kit and AP-1 activity using cells transiently transfected with an AP-1-luciferase reporter construct.

RESULTS

The data showed that lipid extracts of fecal water samples from the adenoma patients had a significantly higher capacity to induce cell proliferation than those from controls, and that this effect could be explained to a large extent by the concentrations of deoxycholic and chenodeoxycholic acids in the fecal water using regression models. No difference between patients and controls was observed for induction of AP-1 activity or induction of DNA strand breaks in intact cells. However, induction of DNA strand breaks in isolated DNA was significantly higher for the fecal waters from patients than for those from controls, which could be explained in part in a regression model by concentrations of lithocholic acid in fecal water and fecapentaene-12 in feces.

CONCLUSIONS

Our results support the hypothesis that the biochemistry of fecal waters from adenoma patients and controls differs.

Effects on Cell Proliferation, Activator Protein-1 and Genotoxicity by Fecal Water from Patients with Colorectal Adenomas

BACKGROUND

The free water phase of feces (fecal water) may mediate the effects of diet on colon carcinogenesis. We examined the effects of fecal water from adenoma patients and controls on three parameters in colonocytes believed to be relevant to tumorigenesis, i.e. genotoxicity in intact cells and on isolated DNA, proliferative activity and activator protein-1 (AP-1) activity.

METHODS

Genotoxicity in intact colonic cells was assayed using the single-cell gel electrophoresis assay (`comet' assay) and on isolated DNA using double-stranded DNA from the X-174 RF plasmid. Cell proliferation was assessed using the commercially available `alamar blue' proliferation kit and AP-1 activity using cells transiently transfected with an AP-1-luciferase reporter construct.

RESULTS

The data showed that lipid extracts of fecal water samples from the adenoma patients had a significantly higher capacity to induce cell proliferation than those from controls, and that this effect could be explained to a large extent by the concentrations of deoxycholic and chenodeoxycholic acids in the fecal water using regression models. No difference between patients and controls was observed for induction of AP-1 activity or induction of DNA strand breaks in intact cells. However, induction of DNA strand breaks in isolated DNA was significantly higher for the fecal waters from patients than for those from controls, which could be explained in part in a regression model by concentrations of lithocholic acid in fecal water and fecapentaene-12 in feces.

CONCLUSIONS

Our results support the hypothesis that the biochemistry of fecal waters from adenoma patients and controls differs.