Intestinal enteroids/organoids: A novel platform for drug discovery in inflammatory bowel diseases.

The introduction of biologics such as anti-tumor necrosis factor (TNF) monoclonal antibodies followed by anti-integrins has dramatically changed the therapeutic paradigm of inflammatory bowel diseases (IBD). Furthermore, a newly developed anti-p40 subunit of interleukin (IL)-12 and IL-23 (ustekinumab) has been recently approved in the United States for patients with moderate to severe Crohn's disease who have failed treatment with anti-TNFs. However, these immunosuppressive therapeutics which focus on anti-inflammatory mechanisms or immune cells still fail to achieve long-term remission in a significant percentage of patients. This strongly underlines the need to identify novel treatment targets beyond immune suppression to treat IBD. Recent studies have revealed the critical role of intestinal epithelial cells (IECs) in the pathogenesis of IBD. Physical, biochemical and immunologic driven barrier dysfunctions of epithelial cells contribute to the development of IBD. In addition, the recent establishment of adult stem cell-derived intestinal enteroid/organoid culture technology has allowed an exciting opportunity to study human IECs comprising all normal epithelial cells. This long-term epithelial culture model can be generated from endoscopic biopsies or surgical resections and recapitulates the tissue of origin, representing a promising platform for novel drug discovery in IBD. This review describes the advantages of intestinal enteroids/organoids as a research tool for intestinal diseases, introduces studies with these models in IBD, and gives a description of the current status of therapeutic approaches in IBD. Finally, we provide an overview of the current endeavors to identify a novel drug target for IBD therapy based on studies with human enteroids/organoids and describe the challenges in using enteroids/organoids as an IBD model.

Overview of gastrointestinal cancer prevention in Asia.

"War on cancer" was declared through the National Cancer Act by President Richard Nixon in 1971, but cancer statistics from the American Cancer Society and other sources indicated the failure of this war, suggesting instead focus on the message that a "prevention strategy" might be much more effective than cancer treatment. While cancer statistics notoriously showed sharp increases in incidence as well as in mortality concurrent with economic growth in Asia, fortunately Asian countries benefit from plentiful resources of natural compounds, which can prevent cancer. Just like cancer chemotherapeutics targeted to kill cancer cells in Western countries, natural agents activating molecular mechanisms for cancer prevention, reversion of premalignant tumors, and even ablation of cancer stem cells, are very abundant in Asia. Currently, these natural agents are under very active investigations targeting the hallmarks of cancer prevention, including selective induction of apoptosis in cancer cells, suppression of growth factors or their signaling, suppression of cell proliferation and of cancer-promoting angiogenesis, induction of mesenchymal-epithelial transition, and disruption of the tumor microenvironment, developing promising cancer preventive agents. However, Asia is the most populous continent in the world and some Asian countries do not have the resources to implement cancer screening programs for early detection or treatment. In addition, despite the excellent cancer preventive screening strategies in some Asian countries, well-designed clinical trials for cancer prevention are somewhat delayed compared to Western countries. In this review article, several phytochemicals/phytoceuticals produced and studied in different Asian countries will be introduced, including Korean red ginseng (pride of Korea), curcumin (Indian spice for life), black or green tea (popular in Japan/Sri Lanka), genistein from tofu (famous Chinese food), diallylsulfide or S-allylcysteine (garlic, popularly consumed as a food ingredient in many Asian countries), capsaicin, 6-gingerol, flavopiridol, and silymarin (abundant in various Asian foods). Whereas in Western countries cancer chemotherapeutics involve strategies not only to block the growth of the primary tumor, but also to inhibit its progression to metastatic disease, the endless pursuit of effective agents for cancer prevention may be a unique and featured strategy in Asia. More active efforts for clinical application of these principles should be supported.

Anti-fibrogenic effects of the anti-microbial peptide cathelicidin in murine colitis-associated fibrosis.

BACKGROUND AND AIMS: Cathelicidin (LL-37 in human and mCRAMP in mice) represents a family of endogenous antimicrobial peptides with anti-inflammatory effects. LL-37 also suppresses collagen synthesis, an important fibrotic response, in dermal fibroblasts. Here we determined whether exogenous cathelicidin administration modulates intestinal fibrosis in two animal models of intestinal inflammation and in human colonic fibroblasts. METHODS: C57BL/6J mice (n=6 per group) were administered intracolonically with a trinitrobenzene sulphonic acid (TNBS) enema to induce chronic (6-7 weeks) colitis with fibrosis. mCRAMP peptide (5 mg/kg every 3 day, week 5-7) or cathelicidin gene (Camp)-expressing lentivirus (107 infectious units week 4) were administered intracolonically or intravenously, respectively. 129Sv/J mice were infected with Salmonella typhimurium orally to induce cecal inflammation with fibrosis. Camp expressing lentivirus (107 infectious units day 11) was administered intravenously. RESULTS: TNBS-induced chronic colitis was associated with increased colonic collagen (col1a2) mRNA expression. Intracolonic cathelicidin (mCRAMP peptide) administration or intravenous delivery of lentivirus-overexpressing cathelicidin gene significantly reduced colonic col1a2 mRNA expression in TNBS-exposed mice, compared to vehicle administration. Salmonella infection also caused increased cecal inflammation associated with collagen (col1a2) mRNA expression that was prevented by intravenous delivery of Camp-expressing lentivirus. Exposure of human primary intestinal fibroblasts and human colonic CCD-18Co fibroblasts to transforming growth factor-beta1 (TGF-beta1) and/or insulin-like growth factor 1 induced collagen protein and mRNA expression, that was reduced by LL-37 (3-5 µM) through a MAP kinase-dependent mechanism. CONCLUSION: Cathelicidin can reverse intestinal fibrosis by directly inhibiting collagen synthesis in colonic fibroblasts.

Cathelicidin suppresses colon cancer development by inhibition of cancer associated fibroblasts.

BACKGROUND: Cathelicidin (LL-37 in humans and mCRAMP in mice) represents a family of endogenous antimicrobial and anti-inflammatory peptides. Cancer-associated fibroblasts can promote the proliferation of colon cancer cells and growth of colon cancer tumors. METHODS: We examined the role of cathelicidin in the development of colon cancer, using subcutaneous human HT-29 colon-cancer-cell-derived tumor model in nude mice and azoxymethane- and dextran sulfate-mediated colon cancer model in C57BL/6 mice. We also determined the indirect antitumoral mechanism of cathelicidin via the inhibition of epithelial-mesenchymal transition (EMT) of colon cancer cells and fibroblast-supported colon cancer cell proliferation. RESULTS: Intravenous administration of cathelicidin expressing adeno-associated virus significantly reduced the size of tumors, tumor-derived collagen expression, and tumor-derived fibroblast expression in HT-29-derived subcutaneous tumors in nude mice. Enema administration of the mouse cathelicidin peptide significantly reduced the size and number of colonic tumors in azoxymethane- and dextran sulfate-treated mice without inducing apoptosis in tumors and the adjacent normal colonic tissues. Cathelicidin inhibited the collagen expression and vimentin-positive fibroblast expression in colonic tumors. Cathelicidin did not directly affect HT-29 cell viability, but did significantly reduce tumor growth factor-ß1-induced EMT of colon cancer cells. Media conditioned by the human colonic CCD-18Co fibroblasts promoted human colon cancer HT-29 cell proliferation. Cathelicidin pretreatment inhibited colon cancer cell proliferation mediated by media conditioned by human colonic CCD-18Co fibroblasts. Cathelicidin disrupted tubulin distribution in colonic fibroblasts. Disruption of tubulin in fibroblasts reduced fibroblast-supported colon cancer cell proliferation. CONCLUSION: Cathelicidin effectively inhibits colon cancer development by interfering with EMT and fibroblast-supported colon cancer cell proliferation.

Effect of acute auditory stress on gastric motor responses to a meal in healthy volunteers.

BACKGROUND AND AIM: Stress is believed to play a role in the pathogenesis of functional gastrointestinal disorders. The aim of the present study was to investigate the effect of acute auditory stress on gastric motor responses to a meal in healthy subjects. METHODS: A total of eight healthy volunteers (seven men and one woman; median age, 33.4 years [30-35 years]) who had no recurrent gastrointestinal symptoms participated in the prospective, randomized, crossover study. Gastric half-emptying time and meal-induced proximal gastric accommodation were measured using gastric scintigraphy under the auditory stress and control conditions in a randomized crossover design. RESULTS: The gastric half-emptying time under the stress condition was significantly longer than that under the control condition (130.8 ± 16.6 vs. 105.0 ± 13.1 min; P = 0.005 by paired t-test). Under the stress and control conditions, the proximal gastric volume significantly increased after a meal (P < 0.001 by repeated measures analysis of variance). The degree of the postprandial increase in proximal gastric volume did not significantly differ between both conditions (P = 0.598 by tests of between-subjects effects using repeated measures analysis of variance). The severity scores of postprandial epigastric discomfort and fullness were significantly higher under the stress condition than under the control condition (P = 0.001 and P = 0.039, respectively, by paired t-test). CONCLUSIONS: Acute auditory stress delays gastric emptying and increases the severity of postprandial symptoms in the healthy subjects, suggesting the relevance of psychological stress to the pathophysiological mechanism of functional dyspepsia.