Serum bile acids, programmed cell death and cell proliferation in the mucosa of patients with colorectal adenomas

COULD THE INTESTINAL EPITHELIAL ALTERATIONS PROMOTED BY ROUX-EN-Y GASTRIC BYPASS EXPLAIN HIGHER TENDENCY FOR COLONIC DISEASES IN BARIATRIC PATIENTS?

BACKGROUND

Ki-67 in ascending colon: A) experiment and B) control. Intestinal diversions have revolutionized the treatment of morbid obesity due to its viability and sustained response. However, experimental studies suggest, after these derivations, a higher risk of colon cancer.

AIM

To analyze the histological and immunohistological changes that the jejunojejunal shunt can produce in the jejunum, ileum and ascending colon.

METHOD

Twenty-four male Wistar rats were randomly divided into two groups, control (n=12) and experiment (n=12) and subdivided into groups of four. Nine weeks after the jejunojejunal shunt, segmental resection of the excluded jejunum, terminal ileum and ascending colon was performed. Histological analysis focused on the thickness of the mucosa, height of the villi, depth of the crypts and immunohistochemistry in the expression of Ki-67 and p53.

RESULTS

Significant differences were found between the experiment and control groups in relation to the thickness of the mucosa in the jejunum (p=0.011), in the ileum (p<0.001) and in the colon (p=0.027). There was also a significant difference in relation to the height of the villus in the ileum (p<0.001) and the depth of the crypts in the jejunum (p0.001). The results indicated that there is a significant difference between the groups regarding the expression of Ki-67 in the colon (p<0.001). No significant differences were found between the groups regarding the expression of Ki-67 in the jejunum and ileum. In the P53 evaluation, negative nuclear staining was found in all cases.

CONCLUSION

The jejunojejunal deviation performed in the Roux-in-Y gastrojejunal bypass, predispose epithelial proliferative effects, causing an increase in the thickness of the mucosa, height of the villi and depth of the crypts of the jejunum, ileum and ascending colon.

Analysis of bile acids in human biological samples by microcolumn separation techniques: A review

Bile acids are a group of compounds essential for lipid digestion and absorption with a steroid skeleton and a carboxylate side chain usually conjugated to glycine or taurine. Bile acids are regulatory molecules for a number of metabolic processes and can be used as biomarkers of various disorders. Since the middle of the twentieth century, the detection of bile acids has evolved from simple qualitative analysis to accurate quantification in complicated mixtures. Advanced methods are required to characterize and quantify individual bile acids in these mixtures. This article overviews the literature from the last two decades (2000-2020) and focuses on bile acid analysis in various human biological samples. The methods for sample preparation, including the sample treatment of conventional (blood plasma, blood serum, and urine) and unconventional samples (bile, saliva, duodenal/gastric juice, feces, etc.) are shortly discussed. Eventually, the focus is on novel analytical approaches and methods for each particular biological sample, providing an overview of the microcolumn separation techniques, such as high-performance liquid chromatography, gas chromatography, and capillary electrophoresis, used in their analysis. This is followed by a discussion on selected clinical applications.

Repression of intestinal transporters and FXR-FGF15 signaling explains bile acids dysregulation in experimental colitis-associated colon cancer

Bile acids (BAs) are important endogenous signaling molecules that play vital roles in the pathological development of various diseases including colitis-associated cancer (CAC). BAs were previously found dysregulated under conditions of CAC; however, the exact patterns and underlying molecular mechanisms remain largely elusive. Based on the development of a method for comprehensive analysis of BAs, this study aims to elucidate the dysregulation patterns and involved mechanisms in a typical CAC model induced by azoxymethane (AOM)/dextran sodium sulfate (DSS). CAC mice showed decreased BAs transformation in gut and glucuronidation in colon, leading to accumulation of primary BAs but reduction of secondary BAs in colon. CAC mice were characterized by an accumulation of BAs in various compartments except ileum, which is in line with repressed ileal FXR-FGF15 feedback signaling and the increased expression of hepatic CYP7A1. The compromised ileal FXR-FGF15 signaling was caused in part by the reduced absorption of FXR ligands including free and tauro-conjungated BAs due to the downregulation of various transporters of BAs in the ileum of CAC mice.

Risk modification of colorectal adenoma by CYP7A1 polymorphisms and the role of bile acid metabolism in carcinogenesis

Cholesterol 7α-hydroxylase (CYP7A1), the rate-limiting enzyme in the conversion of cholesterol to bile acids, is a postulated gene modifier of colorectal cancer risk and target for the therapeutic bile acid, ursodeoxycholic acid (UDCA). We investigated associations between CYP7A1 polymorphisms and fecal bile acids, colorectal adenoma (CRA), and UDCA efficacy for CRA prevention. Seven tagging, single-nucleotide polymorphisms (SNP) in CYP7A1 were measured in 703 (355 UDCA, 348 placebo) participants of a phase III chemoprevention trial, of which 495 had known baseline fecal bile acid concentrations. In the placebo arm, participants with two minor G(rs8192871) alleles (tag for a low activity promoter polymorphism at -204) had lower odds of high secondary bile acids (OR = 0.26, 95% CI: 0.10-0.69), and CRA at 3 years' follow-up (OR = 0.41, 95% CI: 0.19-0.89), than AA carriers. Haplotype construction from the six polymorphic SNPs showed participants with the third most common haplotype (C(rs10957057)C(rs8192879)G(rs8192877)T(rs11786580)A(rs8192871)G(rs13251096)) had higher odds of high primary bile acids (OR = 2.34, 95% CI: 1.12-4.89) and CRA (OR = 1.89, 95% CI: 1.00-3.57) than those with the most common CTACAG haplotype. Furthermore, three SNPs (rs8192877, rs8192871, and rs13251096) each modified UDCA efficacy for CRA prevention, and CCGTAG-haplotype carriers experienced 71% lower odds of CRA recurrence with UDCA treatment, an effect not present for other haplotypes (test for UDCA-haplotype interaction, P = 0.020). Our findings support CYP7A1 polymorphisms as determinants of fecal bile acids and risk factors for CRA. Furthermore, UDCA efficacy for CRA prevention may be modified by genetic variation in CYP7A1, limiting treatment benefit to a subgroup of the population.

Bile acids and liver regeneration

Bile acids possess many important physiological functions. They have been shown to play pivotal roles in the absorption of dietary lipids and fat soluble vitamins as well as in regulating bile acid homeostasis, lipoprotein and glucose metabolism. Recent evidence suggests that bile acid signaling pathway plays an important role in normal liver regeneration. This review aims to elucidate the potential role of the bile acid signaling pathway in liver regeneration and to highlight possible mechanisms involved.

Ponicidin inhibits cell growth on hepatocellular carcinoma cells by induction of apoptosis

BACKGROUND AND AIM

Ponicidin is recently reported to have anti-tumour effects on a large variety of cancers. The present study was undertaken to investigate the anti-proliferation effects of ponicidin on hepatocellular carcinoma cells and its mechanism.

METHODS

Two hepatocellular carcinoma cell lines, QGY-7701 and HepG-2 cells, were used. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell apoptosis was assessed by flow cytometry and deoxyribonucleic acid fragmentation analysis. Cell morphology was observed by Hoechst 33258 staining. Reverse transcriptase-polymerase chain reaction and Western blot analysis were used to detect Survivin as well as Bax and Bcl-2 expressions.

RESULTS

Ponicidin could inhibit the growth of QGY-7701 and HepG-2 cells significantly by induction of apoptosis. Marked morphological changes of apoptosis were observed clearly. Both Survivin and Bcl-2 expressions were down-regulated remarkably while Bax expression up-regulated when apoptosis occurred.

CONCLUSIONS

Ponicidin has significant anti-proliferation effects by inducing apoptosis on hepatocellular carcinoma cells in vitro, down regulation of Survivin and Bcl-2 as well as upregualation of Bax expressions may be the important apoptotic inducing mechanisms.

Evaluation of intestinal trophism: review of current methods and techniques

PURPOSE OF REVIEW

This review aims to cover the methods and techniques currently used by researchers to evaluate intestinal trophism.

RECENT FINDINGS

Although subjected to criticisms, conventional gut trophism evaluation by both morphological and histological parameters continues to be largely reported. The metaphase arrest technique and the detection of H-tymidine have been used less frequently in recent years due to increasing interest in the immunohistochemical methods such as 5-bromo-2'deoxy-uridine, Ki-67, and proliferating cell nuclear antigen. Along with common techniques for the evaluation of intestinal trophism, the combination of methods that includes a measurement of cell proliferation and an apoptotic index in the same study are most valuable and are increasing in the current literature.

SUMMARY

Evaluation of intestinal trophism is an important issue for both clinical and experimental nutritional studies. The immunohistochemical techniques are the gold standard to access cell proliferation. Evaluation of proliferation and apoptosis at the same time may offer a more reliable evaluation of the actual status of gut trophism.