Published papers

The efficacy of conventional radiation therapy for gastric cancer is controversial. In this study, we evaluated the in vitro and in vivo effects of continuous low-dose-rate irradiation by I-125 seeds on different histological types of gastric cancer cell lines. Three human gastric cancer cell lines (MKN74, MKN45, and NUGC4) were treated with or without continuous low-dose irradiation by I-125 seeds in vitro and in vivo. Cell viability, apoptosis, caspase-3 assay, and cell-cycle distribution were examined in vitro. Body weight and tumor volumes of BALB/c nude mice bearing MKN74, MKN45, and NUGC4 gastric cancer xenografts were measured, and in vivo cell proliferation and apoptosis assays were performed by Ki67 and TUNEL staining, respectively. Continuous low-dose-rate irradiation by I-125 seeds reduced cell viability and induced cell apoptosis through the activation of caspase-3, and led to the accumulation of cells in the G2/M phase in vitro. It also suppressed the growth of gastric cancer xenografts in nude mice, while inhibiting cell proliferation and inducing apoptosis as demonstrated by Ki67 and TUNEL staining. Therefore, our data suggest that continuous low-dose-rate irradiation by I-125 seeds could be a promising new option for gastric cancer treatment, regardless of histological origin.

The liver is a physiological site of immune tolerance, the breakdown of which induces immunity. Liver antigen-presenting cells may be involved in both immune tolerance and activation. Although inflammatory diseases of the liver are frequently associated with inflammatory bowel diseases, the underlying immunological mechanisms remain to be elucidated. Here we report two murine models of inflammatory bowel disease: RAG-2-/- mice adoptively transferred with CD4+CD45RBhigh T cells; and IL-10 -/- mice, accompanied by the infiltration of mononuclear cells in the liver. Notably, CD11b-CD11clowPDCA-1+ plasmacytoid dendritic cells (DCs) abundantly residing in the liver of normal wild-type mice disappeared in colitic CD4+CD45RBhigh T cell-transferred RAG-2-/- mice and IL-10-/- mice in parallel with the emergence of macrophages (Mφs) and conventional DCs (cDCs). Furthermore, liver Mφ/cDCs emerging during intestinal inflammation not only promote the proliferation of naïve CD4+ T cells, but also instruct them to differentiate into IFN-γ-producing Th1 cells in vitro. The emergence of pathological Mφ/cDCs in the liver also occurred in a model of acute dextran sulfate sodium (DSS)-induced colitis under specific pathogen-free conditions, but was canceled in germ-free conditions. Last, the Mφ/cDCs that emerged in acute DSS colitis significantly exacerbated Fas-mediated hepatitis. Collectively, intestinal inflammation skews the composition of antigen-presenting cells in the liver through signaling from commensal bacteria and predisposes the liver to inflammation.

Recent examples have highlighted how stem cells have the capability to initiate morphogenesis in vitro; that is, to generate complex structures in culture that closely parallel their in vivo counterparts. Lgr5, the receptor for the Wnt-agonistic R-spondins, marks stem cells in multiple adult organs of mice and humans. In R-spondin-based three-dimensional cultures, these Lgr5 stem cells can grow into ever-expanding epithelial organoids that retain their original organ identity. Single Lgr5 stem cells derived from the intestine can be cultured to build epithelial structures that retain hallmarks of the in vivo epithelium. Here, we review the mechanisms that support this notable example of self-organization and discuss applications of this technology for stem cell research, disease modeling (e.g., for colorectal cancer and cystic fibrosis), and regenerative medicine.

The intestinal epithelium is the most rapidly self-renewing tissue in adult mammals. We have recently shown that Lgr5 (Leucine-rich repeat-containing G protein-coupled receptor) is expressed in intestinal stem cells by an in vivo genetic lineage tracing strategy. In the past, extensive efforts have been made to establish primary small intestinal culture systems. However, no defined, reproducible and robust culture system had been developed. To establish such a system, we screened for optimal growth factor combinations based on genetic evidence of self-renewal regulation, differentiation, and carcinogenesis of intestinal stem cells. Here, we describe methods that we have established for the isolation and culture of primary small intestinal epithelial stem cells. In this culture system, isolated crypts form organoid structures with a histological hierarchy recapitulating in vivo small intestinal epithelium. Single isolated Lgr5+ intestinal stem cells also form these organoid structures, in which stem cells are maintained by self-renewal and give rise to all lineages of the intestinal epithelium. This culture system is particularly useful for studying the regulation of intestinal stem cell self-renewal and differentiation.

Background: Oral administration of tacrolimus is an effective remission induction therapy for steroid-refractory/dependent ulcerative colitis (UC). Aim: This study aimed to evaluate the short- as well as medium- and long-term effectiveness of tacrolimus therapy. Methods: The medical records of 51 patients treated with tacrolimus for UC at our hospital between July 2009 and December 2011 were reviewed retrospectively. Clinical remission and improvement were defined as a Lichtiger score of 4 or less and as a Lichtiger score of ≤. 10 and a reduction in the score of ≥. 3 compared with the baseline score, respectively. Endoscopic findings were evaluated based on the endoscopic activity index and Mayo endoscopic score. Results: The clinical effectiveness combining clinical remission and improvement was observed in 62.7% of the patients at 3. months. Thirty-six patients underwent colonoscopy at 3. months, and 12 (33.3%) and 10 patients (27.8%) showed Mayo endoscopic scores of 0 and 1, respectively. On Kaplan-Meier analysis, the overall percentage of event-free survivors, who did not require colectomy nor switching to other induction therapy such as infliximab, was 73.0% at 6. months, 49.9% at 1. year, and 37.8% at 2. years. Patients with a Mayo endoscopic score of 0-1 at 3. months showed significantly better medium- and long-term prognosis than those with a score of 2-3 (p<. 0.01). All adverse events, including infections in 2 patients, were reversible. Conclusions: Tacrolimus therapy was effective for inducing clinical and endoscopic remission of steroid-refractory/dependent UC. Endoscopic improvement was associated with favorable medium- and long-term prognosis.

Lgr5 marks adult stem cells in multiple adult organs and is a receptor for the Wnt-agonistic R-spondins (RSPOs). Intestinal, stomach and liver Lgr5 + stem cells grow in 3D cultures to form ever-expanding organoids, which resemble the tissues of origin. Wnt signalling is inactive and Lgr5 is not expressed under physiological conditions in the adult pancreas. However, we now report that the Wnt pathway is robustly activated upon injury by partial duct ligation (PDL), concomitant with the appearance of Lgr5 expression in regenerating pancreatic ducts. In vitro, duct fragments from mouse pancreas initiate Lgr5 expression in RSPO1-based cultures, and develop into budding cyst-like structures (organoids) that expand five-fold weekly for >40 weeks. Single isolated duct cells can also be cultured into pancreatic organoids, containing Lgr5 stem/progenitor cells that can be clonally expanded. Clonal pancreas organoids can be induced to differentiate into duct as well as endocrine cells upon transplantation, thus proving their bi-potentiality.

The objective of this study was to establish a novel prediction system of drug absorption in humans by utilizing human intestinal tissues. Based on the transport index (TI), a newly defined parameter, calculated by taking account of the change in drug concentrations because of precipitation on the apical side and the amounts accumulated in the tissue and transported to the basal side, the absorbability of drugs in rank order as well as the fraction of dose absorbed (Fa) in humans were estimated. Human intestinal tissues taken from ulcerative colitis or Crohn's disease patients were mounted in a mini-Ussing chamber and transport studies were performed to evaluate the permeation of drugs, including FD-4, a very low permeable marker, atenolol, a low permeable marker, and metoprolol, a high permeable marker. Although apparent permeability coefficients calculated by the conventional equation did not reflect human Fa values for FD-4, atenolol, and metoprolol, TI values were well correlated with Fa values, which are described by 100 · [1 - e - f · (TI - α)]. Based on this equation, Fa values in humans for other test drugs were predicted successfully, indicating that our new system utilizing human intestinal tissues would be valuable for predicting oral drug absorption in humans.

Imbalance in gut bacterial composition provokes host proinflammatory responses causing diseases such as colitis. Colonization with a mixture of Clostridium species from clusters IV and XIVa was shown to suppress colitis through the induction of IL-10-producing regulatory T (Treg) cells. We demonstrate that a distinct Clostridium strain from cluster I, Clostridium butyricum (CB), prevents acute experimental colitis in mice through induction of IL-10, an anti-inflammatory cytokine. However, while CB treatment had no effect on IL-10 production by T cells, IL-10-producing F4/80+CD11b +CD11cint macrophages accumulated in the inflamed mucosa after CB treatment. CB directly triggered IL-10 production by intestinal macrophages in inflamed mucosa via the TLR2/MyD88 pathway. The colitis-preventing effect of CB was negated in macrophage-specific IL-10-deficient mice, suggesting that induction of IL-10 by intestinal macrophages is crucial for the probiotic action of CB. Collectively, CB promotes IL-10 production by intestinal macrophages in inflamed mucosa, thereby preventing experimental colitis in mice.

Bile acids (BAs) play important roles not only in lipid metabolism, but also in signal transduction. TGR5, a transmembrane receptor of BAs, is an immunomodulative factor, but its detailed mechanism remains unclear. Here, we aimed to delineate how BAs operate in immunological responses via the TGR5 pathway in human mononuclear cell lineages. We examined TGR5 expression in human peripheral blood monocytes, several types of in vitro differentiated macrophages (Mφ{symbol}s) and dendritic cells. Mφ{symbol}s differentiated with macrophage colony-stimulating factor and interferon-γ (Mγ-Mφ{symbol}s), which are similar to the human intestinal lamina propria CD14+ Mφ{symbol}s that contribute to Crohn's disease (CD) pathogenesis by production of pro-inflammatory cytokines, highly expressed TGR5 compared with any other type of differentiated Mφ{symbol} and dendritic cells. We also showed that a TGR5 agonist and two types of BAs, deoxycholic acid and lithocholic acid, could inhibit tumour necrosis factor-α production in Mγ-Mφ{symbol}s stimulated by commensal bacterial antigen or lipopolysaccharide. This inhibitory effect was mediated by the TGR5-cAMP pathway to induce phosphorylation of c-Fos that regulated nuclear factor-κB p65 activation. Next, we analysed TGR5 levels in lamina propria mononuclear cells (LPMCs) obtained from the intestinal mucosa of patients with CD. Compared with non-inflammatory bowel disease, inflamed CD LPMCs contained more TGR5 transcripts. Among LPMCs, isolated CD14+ intestinal Mφ{symbol}s from patients with CD expressed TGR5. In isolated intestinal CD14+ Mφ{symbol}s, a TGR5 agonist could inhibit tumour necrosis factor-α production. These results indicate that TGR5 signalling may have the potential to modulate immune responses in inflammatory bowel disease.

Retinoid-related orphan receptor (ROR) γt is known to be related to the development and function of various immunological compartments in the liver, such as Th17 cells, natural killer T (NKT) cells, and innate lymphoid cells (ILCs). We evaluated the roles of RORγt-expressing cells in mouse acute hepatitis model using RORγt deficient (RORγt-/-) mice and RAG-2 and RORγt double deficient (RAG-2-/- × RORγt-/-) mice. Acute hepatitis was induced in mice by injection with carbon tetrachloride (CCl4), to investigate the regulation of liver inflammation by RORγt-expressing cells. We detected RORC expression in three compartments, CD4+ T cells, NKT cells, and lineage marker-negative SCA-1+Thy1high ILCs, of the liver of wild type (WT) mice. CCl4-treated RORγt-/- mice developed liver damage in spite of lack of RORγt-dependent cells, but with reduced infiltration of macrophages compared with WT mice. In this regard, ILCs were significantly decreased in RAG-2-/- × RORγt-/- mice that lacked T and NKT cells. Surprisingly, RAG-2-/- × RORγt-/- mice developed significantly severer CCl4-induced hepatitis compared with RAG-2-/- mice, in accordance with the fact that hepatic ILCs failed to produce IL-22. Lastly, anti-Thy1 monoclonal antibody (mAb), but not anti-NK1.1 mAb or anti-asialo GM1 Ab administration exacerbated liver damage in RAG-2-/- mice with the depletion of liver ILCs. Collectively, hepatic RORγt-dependent ILCs play a part of protective roles in hepatic immune response in mice.

Intestinal lamina propria dendritic cells (LPDCs) in mice are known to extend dendrites between the intestinal epithelia and the luminal side when processing luminal antigens. We conducted intrarectal cell transfer experiments of bone marrow-derived dendritic cells (BMDCs) in mice to assess dendritic cell penetration of the intestine. Intrarectally administered GFP+ BMDCs localized in the colonic LP within 3h and the spleen within 12h after administration. 72h after administration, recipient C57BL/6 mice showed acute diarrhea, and administration of BMDCs (once weekly for 3 weeks) induced intestinal inflammation with increased numbers of recipient macrophages and CD4+ T cells exhibiting a Th2-mediated immune response. These results demonstrate that DCs actively communicate across the intestinal barrier, and highlight a potential technique for controlling colonic immune tolerance.

The Wnt target gene Lgr5 (leucine-rich-repeat-containing G-protein-coupled receptor 5) marks actively dividing stem cells in Wnt-driven, self-renewing tissues such as small intestine and colon, stomach and hair follicles. A three-dimensional culture system allows long-term clonal expansion of single Lgr5+ stem cells into transplantable organoids (budding cysts) that retain many characteristics of the original epithelial architecture. A crucial component of the culture medium is the Wnt agonist RSPO1, the recently discovered ligand of LGR5. Here we show that Lgr5-lacZ is not expressed in healthy adult liver, however, small Lgr5-LacZ + cells appear near bile ducts upon damage, coinciding with robust activation of Wnt signalling. As shown by mouse lineage tracing using a new Lgr5-IRES-creERT2 knock-in allele, damage-induced Lgr5+ cells generate hepatocytes and bile ducts in vivo. Single Lgr5+ cells from damaged mouse liver can be clonally expanded as organoids in Rspo1-based culture medium over several months. Such clonal organoids can be induced to differentiate in vitro and to generate functional hepatocytes upon transplantation into Fah-/-mice. These findings indicate that previous observations concerning Lgr5+ stem cells in actively self-renewing tissues can also be extended to damage-induced stem cells in a tissue with a low rate of spontaneous proliferation.

Retinoid-related orphan receptor (ROR) γt-expressing and IL-22-producing NKp46+ innate lymphoid (ILC22) cells reside in the lamina propria of the intestine in mice, suggesting that ILC22 cells contribute to host defense during intestinal damage in models of colitis in mice. Nevertheless, another set of pathological interferon (IFN)-γ and/or IL-17A-producing innate lymphoid cells (ILC1 and ICL17) may participate in the pathogenesis in different models of colitis. We here showed that RORγt+IL-22+ ILC22 cells were localized in Thy-1highSCA-1high and/or Thy-1highSCA-1low subpopulations of the intestine in normal and dextran sodium sulfate (DSS)-induced colitic RORγt-sufficient Rag-2-/- mice. RORγt-deficient Rag-2-/- mice developed more severe DSS-induced colitis accompanied with lower expression of REG3β and REG3γ in the colon, but with a lower ratio and absolute number of IFN-γ-producing ILC1 cells as compared to control RORγt-sufficient Rag-2-/- mice. Collectively, not only the presence of ILC22 cells but also the balance of protective and pathogenic ILCs may be involved in the prevention of colitis.

Lgr5 + intestinal stem cells generate enterocytes and secretory cells. Secretory lineage commitment requires Notch silencing. The Notch ligand Dll1 is expressed by a subset of immediate stem cell daughters. Lineage tracing in Dll1 GFP-ires-CreERT2 knock-in mice reveals that single Dll1 high cells generate small, short-lived clones containing all four secretory cell types. Lineage specification thus occurs in immediate stem cell daughters through Notch lateral inhibition. Cultured Dll1 high cells form long-lived organoids (mini-guts) on brief Wnt3A exposure. When Dll1 high cells are genetically marked before tissue damage, stem cell tracing events occur. Thus, secretory progenitors exhibit plasticity by regaining stemness on damage.

In vitro culture of intestinal tissue has been attempted for decades. Only recently did Sato et al. [Sato, T., Vries, R. G., Snippert, H. J., van de Wetering, M., Barker, N., Stange, D. E., van Es, J. H., Abo, A., Kujala, P., Peters, P. J., et al. (2009) Nature459, 262-265] succeed in establishing long-term intestinal culture, demonstrating that cells expressing the Lgr5 gene can give rise to organoids with crypt-like domains similar to those found in vivo. In these cultures, Paneth cells provide essential signals supporting stem cell function. We have recently developed an individual cell-based computational model of the intestinal tissue [Buske, P., Galle, J., Barker, N., Aust, G., Clevers, H. & Loeffler, M. (2011) PLoS Comput Biol7, e1001045]. The model is capable of quantitatively reproducing a comprehensive set of experimental data on intestinal cell organization. Here, we present a significant extension of this model that allows simulation of intestinal organoid formation in silico. For this purpose, we introduce a flexible basal membrane that assigns a bending modulus to the organoid surface. This membrane may be re-organized by cells attached to it depending on their differentiation status. Accordingly, the morphology of the epithelium is self-organized. We hypothesize that local tissue curvature is a key regulatory factor in stem cell organization in the intestinal tissue by controlling Paneth cell specification. In simulation studies, our model closely resembles the spatio-temporal organization of intestinal organoids. According to our results, proliferation-induced shape fluctuations are sufficient to induce crypt-like domains, and spontaneous tissue curvature induced by Paneth cells can control cell number ratios. Thus, stem cell expansion in an organoid depends sensitively on its biomechanics. We suggest a number of experiments that will enable new insights into mechano-transduction in the intestine, and suggest model extensions in the field of gland formation.

Sepsis is a systemic inflammatory response to infection associated with multiple organ dysfunction syndrome and a high mortality rate. In septic shock induced by severe peritonitis, early response of peritoneal macrophages against infected microbes is vital in preventing the spread of infection. We found that the mucosal homing receptor CCR9, is induced in peritoneal macrophages in response to inflammatory stimulation. We used a cecal ligation and puncture (CLP) model of sepsis to determine the role of CCR9 with respect to peritoneal macrophages, and controlling peritoneal infection and systemic inflammation. CCR9-/- mice showed aggravated septic shock with higher mortality rates compared with wild-type (WT) mice. Six hours after CLP, CCR9-/- mice demonstrated a greater inflammatory response. This was associated with higher production of inflammatory cytokines, such as IL-6, TNF and IP-10 in peritoneal lavage compared with WT mice. Although the numbers of peritoneal bacteria were elevated in CCR9-/- mice subjected to CLP compared with WT mice, this was normalized in CCR9-/- mice subjected to CLP through the adoptive transfer of WT peritoneal macrophages. We conclude that CCR9 is required for recruitment of peritoneal macrophages in the steady state to control systemic sepsis during early phases of peritoneal infection.

Purpose Crohn's disease (CD) commonly recurs after surgery, and a number of patients need repeated surgery, especially smokers and those with repeated surgeries or penetrating disease. Whether infliximab prevents postsurgical recurrence in high-risk CD remains unknown. In the present pilot openlabeled study, we investigated the safety and efficacy of scheduled infliximab, which was started early after surgery, in maintaining remission of CD patients who have undergonemultiple surgeries due to penetrating disease. Methods Eleven patients (nine male, two female; age range, 26-48 years) who had undergone repeated surgeries (median, 4; range, 2-5) for penetrating disease were enrolled. Two to 4 weeks after surgery, the patients were started on intravenous infliximab (5 mg/kg) at an 8-week interval. The primary end points were the proportion of patients in clinical remission at the end of the study, the rate of endoscopic/ radiologic remission at 24 months, and the rate of adverse effects. Results One patient dropped out due to non-compliance, and ten patients were eligible for analysis. Clinical remission was maintained in six of ten patients (60.0%) at the end of the study. At 24 months, four out of ten patients were in endoscopic or radiological remission (40.0%). Two patients experienced adverse effects (18.2%), one of whom elected to withdraw from the study. Conclusion The findings of no major safety concern and possible clinical benefit in our study suggest that further investigation of infliximab as a treatment for prevention of postsurgical recurrence in high-risk CD is warranted.

The effect of granulocyte and monocyte adsorption apheresis (GMA) on prevention of relapse of ulcerative colitis (UC) is not clear. This was a pilot open-labeled, prospective, randomized, unblinded study to compare the tolerability and efficacy of intermittent GMA (once every 2weeks) with mercaptopurine to maintain remission of UC. Twenty-one patients with UC, who had achieved remission by induction therapies were randomly assigned to receive either intermittent GMA (N=10) or oral mercaptopurine (0.5mg/kg per day; N=11). The study period was 24months. The rate of the patients maintaining remission and the incidences of adverse effects were compared between the two groups. At 24months, seven of 10 patients (70.0%) on intermittent GMA and seven of 11 patients (63.6%, P=1.00) on oral mercaptopurine were still in remission. Three patients relapsed in each group. One patient taking mercaptopurine, but none receiving intermittent GMA, dropped out because of adverse effects. Intermittent therapy with GMA was well tolerated and a substantial proportion of patients maintained remission. Intermittent GMA therapy in maintaining remission of UC merits further investigation.

Adult stem-cell therapy holds promise for the treatment of gastrointestinal diseases. Here we describe methods for long-term expansion of colonic stem cells positive for leucine-rich repeat containing G protein-coupled receptor 5 (Lgr5 + cells) in culture. To test the transplantability of these cells, we reintroduced cultured GFP + colon organoids into superficially damaged mouse colon. The transplanted donor cells readily integrated into the mouse colon, covering the area that lacked epithelium as a result of the introduced damage in recipient mice. At 4 weeks after transplantation, the donor-derived cells constituted a single-layered epithelium, which formed self-renewing crypts that were functionally and histologically normal. Moreover, we observed long-term (>6 months) engraftment with transplantation of organoids derived from a single Lgr5 + colon stem cell after extensive in vitro expansion. These data show the feasibility of colon stem-cell therapy based on the in vitro expansion of a single adult colonic stem cell.