Kiichiro Tsuchiya

Functional engraftment of colon epithelium expanded in vitro from a single adult Lgr5+ stem cell

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.

Crosstalk between Wnt and Notch signaling in intestinal epithelial cell fate decision

Continuous renewal of the intestinal epithelium requires coordinated regulation to maintain the balance between proliferation and differentiation of the epithelial stem cells and immature progenitor cells. Canonical Wnt signaling has long been regarded as the signaling pathway playing a central role in this epithelial cell fate determination; however, recent studies have shown that Notch signaling is also indispensable for this process. Here, we review the current concepts of how the Wnt and Notch pathways control intestinal epithelial cell fate decisions, particularly focusing on their crosstalk at both tissue and cellular levels. As several features are shared between stem cell renewal and cancer cell renewal, comprehensive understanding of how the Wnt and Notch signaling pathways cooperate and integrate in the gut epithelium has significant implications for the development of novel therapeutic modalities for intestinal neoplasia.

Inducible expression of microRNA-194 is regulated by HNF-1α during intestinal epithelial cell differentiation

Maintenance of the intestinal epithelium is based on well-balanced molecular mechanisms that confer the stable and continuous supply of specialized epithelial cell lineages from multipotent progenitors. Lineage commitment decisions in the intestinal epithelium system involve multiple regulatory systems that interplay with each other to establish the cellular identities. Here, we demonstrate that the microRNA system could be involved in intestinal epithelial cell differentiation, and that microRNA-194 (miR-194) is highly induced during this process. To investigate this inducible expression mechanism, we identified the genomic structure of the miR-194-2, -192 gene, one of the inducible class of miR-194 parental genes. Furthermore, we identified its transcriptional regulatory region that contains a consensus-binding motif for hepatocyte nuclear factor-1alpha (HNF-1alpha), which is well known as a transcription factor to regulate gene expression in intestinal epithelial cells. By chromatin immunoprecipitation assay and luciferase reporter analysis, we revealed that pri-miR-194-2 expression is controlled by HNF-1alpha, and its consensus binding region is required for the transcription of pri-miR-194-2 in vivo in an intestinal epithelial cell line, Caco-2. Our observations indicate that microRNA genes could be targets of lineage-specific transcription factors and that microRNAs are regulated by a tissue-specific manner in the intestinal epithelium. Therefore, our work suggests that induced expression of these microRNAs have important roles in intestinal epithelium maturation.

Requirement of Notch activation during regeneration of the intestinal epithelia

Notch signaling regulates cell differentiation and proliferation, contributing to the maintenance of diverse tissues including the intestinal epithelia. However, its role in tissue regeneration is less understood. Here, we show that Notch signaling is activated in a greater number of intestinal epithelial cells in the inflamed mucosa of colitis. Inhibition of Notch activation in vivo using a gamma-secretase inhibitor resulted in a severe exacerbation of the colitis attributable to the loss of the regenerative response within the epithelial layer. Activation of Notch supported epithelial regeneration by suppressing goblet cell differentiation, but it also promoted cell proliferation, as shown in in vivo and in vitro studies. By utilizing tetracycline-dependent gene expression and microarray analysis, we identified a novel group of genes that are regulated downstream of Notch1 within intestinal epithelial cells, including PLA2G2A, an antimicrobial peptide secreted by Paneth cells. Finally, we show that these functions of activated Notch1 are present in the mucosa of ulcerative colitis, mediating cell proliferation, goblet cell depletion, and ectopic expression of PLA2G2A, thereby contributing to the regeneration of the damaged epithelia. This study showed the critical involvement of Notch signaling during intestinal tissue regeneration, regulating differentiation, proliferation, and antimicrobial response of the epithelial cells. Thus Notch signaling is a key intracellular molecular pathway for the proper reconstruction of the intestinal epithelia.

Signaling pathway via TNF-α/NF-κB in intestinal epithelial cells may be directly involved in colitis-associated carcinogenesis

Treatment with anti-TNF-alpha MAb has been accepted as a successful maintenance therapy for patients with inflammatory bowel diseases (IBD). Moreover, it has been recently reported that blockade of TNF receptor (TNFR) 1 signaling in infiltrating hematopoietic cells may prevent the development of colitis-associated cancer (CAC). However, it remains unclear whether the TNF-alpha signaling in epithelial cells is involved in the development of CAC. To investigate this, we studied the effects of anti-TNF-alpha MAb in an animal model of CAC by administration of azoxymethane (AOM) followed by sequential dextran sodium sulfate (DSS) ingestion. We observed that the NF-kappaB pathway is activated in colonic epithelia from DSS-administered mice in association with upregulation of TNFR2 rather than TNFR1. Immunoblot analysis also revealed that the TNFR2 upregulation accompanied by the NF-kappaB activation is further complicated in CAC tissues induced in AOM/DSS-administered mice compared with the nontumor area. Such NF-kappaB activity in the epithelial cells is significantly suppressed by the treatment of MP6-XT22, an anti-TNF-alpha MAb. Despite inability to reduce the severity of colitis, sequential administration of MP6-XT22 reduced the numbers and size of tumors in association with the NF-kappaB inactivation. Taken together, present studies suggest that the TNFR2 signaling in intestinal epithelial cells may be directly involved in the development of CAC with persistent colitis and imply that the maintenance therapy with anti-TNF-alpha MAb may prevent the development of CAC in patients with long-standing IBD.

Intestinal Lamina Propria Retaining CD4+CD25+ Regulatory T Cells Is A Suppressive Site of Intestinal Inflammation

It is well known that immune responses in the intestine remain in a state of controlled inflammation, suggesting that not only does active suppression by regulatory T (TREG) cells play an important role in the normal intestinal homeostasis, but also that its dysregulation of immune response leads to the development of inflammatory bowel disease. In this study, we demonstrate that murine CD4+CD25+ T cells residing in the intestinal lamina propria (LP) constitutively express CTLA-4, glucocorticoid-induced TNFR, and Foxp3 and suppress proliferation of responder CD4+ T cells in vitro. Furthermore, cotransfer of intestinal LP CD4+CD25+ T cells prevents the development of chronic colitis induced by adoptive transfer of CD4+CD45RBhigh T cells into SCID mice. When lymphotoxin (LT)α-deficient intercrossed Rag2 double knockout mice (LTα−/− × Rag2−/−), which lack mesenteric lymph nodes and Peyer’s patches, are transferred with CD4+CD45RBhigh T cells, they develop severe wasting disease and chronic colitis despite the delayed kinetics as compared with the control LTα+/+ × Rag2−/− mice transferred with CD4+CD45RBhigh T cells. Of note, when a mixture of splenic CD4+CD25+ TREG cells and CD4+CD45RBhigh T cells are transferred into LTα−/− × Rag2−/− recipients, CD4+CD25+ TREG cells migrate into the colon and prevent the development of colitis in LTα−/− × Rag2−/− recipients as well as in the control LTα+/+ × Rag2−/− recipients. These results suggest that the intestinal LP harboring CD4+CD25+ TREG cells contributes to the intestinal immune suppression.

Suppression of hath1 gene expression directly regulated by hes1 via notch signaling is associated with goblet cell depletion in ulcerative colitis

Background: The transcription factor Atoh1/Hath1 plays crucial roles in the differentiation program of human intestinal epithelium cells (IECs). Although previous studies have indicated that the Notch signal suppresses the differentiation program of IEC, the mechanism by which it does so remains unknown. This study shows that the undifferentiated state is maintained by the suppression of the Hath1 gene in human intestine. Methods: To assess the effect of Notch signaling, doxycycline‐induced expression of Notch intracellular domain (NICD) and Hes1 cells were generated in LS174T. Hath1 gene expression was analyzed by quantitative reverse‐transcription polymerase chain reaction (RT‐PCR). Hath1 promoter region targeted by HES1 was determined by both reporter analysis and ChIP assay. Expression of Hath1 protein in ulcerative colitis (UC) was examined by immunohistochemistry. Results: Hath1 mRNA expression was increased by Notch signal inhibition. However, Hath1 expression was suppressed by ectopic HES1 expression alone even under Notch signal inhibition. Suppression of the Hath1 gene by Hes1, which binds to the 5′ promoter region of Hath1, resulted in suppression of the phenotypic gene expression for goblet cells. In UC, the cooperation of aberrant expression of HES1 and the disappearance of caudal type homeobox 2 (CDX2) caused Hath1 suppression, resulting in goblet cell depletion. Conclusions: The present study suggests that Hes1 is essential for Hath1 gene suppression via Notch signaling. Moreover, the suppression of Hath1 is associated with goblet cell depletion in UC. Understanding the regulation of goblet cell depletion may lead to the development of new therapy for UC. (Inflamm Bowel Dis 2011;)

IL-7 Is Essential for the Development and the Persistence of Chronic Colitis

Although IL-7 has recently emerged as a key cytokine involved in controlling the homeostatic turnover and the survival of peripheral resting memory CD4+ T cells, its potential to be sustained pathogenic CD4+ T cells in chronic immune diseases, such as inflammatory bowel diseases, still remains unclear. In this study, we demonstrate that IL-7 is essential for the development and the persistence of chronic colitis induced by adoptive transfer of normal CD4+CD45RBhigh T cells or colitogenic lamina propria (LP) CD4+ memory T cells into immunodeficient IL-7+/+ × RAG-1−/− and IL-7−/− × RAG-1−/− mice. Although IL-7+/+ × RAG-1−/− recipients transferred with CD4+CD45RBhigh splenocytes developed massive inflammation of the large intestinal mucosa concurrent with massive expansion of Th1 cells, IL-7−/− × RAG-1−/− recipients did not. Furthermore, IL-7−/− × RAG-1−/−, but not IL-7+/+ × RAG-1−/−, mice transferred with LP CD4+CD44highCD62L−IL-7Rαhigh effector-memory T cells (TEM) isolated from colitic CD4+CD45RBhigh-transferred mice did not develop colitis. Although rapid proliferation of transferred colitogenic LP CD4+ TEM cells was observed in the in IL-7−/− × RAG-1−/− mice to a similar extent of those in IL-7+/+ × RAG-1−/− mice, Bcl-2 expression was significantly down-modulated in the transferred CD4+ T cells in IL-7−/− × RAG-1−/− mice compared with those in IL-7+/+ × RAG-1−/− mice. Taken together, IL-7 is essential for the development and the persistence of chronic colitis as a critical survival factor for colitogenic CD4+ TEM cells, suggesting that therapeutic approaches targeting IL-7/IL-7R signaling pathway may be feasible in the treatment of inflammatory bowel diseases.

MyD88-Dependent Pathway in T Cells Directly Modulates the Expansion of Colitogenic CD4+ T Cells in Chronic Colitis

TLRs that mediate the recognition of pathogen-associated molecular patterns are widely expressed on/in cells of the innate immune system. However, recent findings demonstrate that certain TLRs are also expressed in conventional TCRαβ+ T cells that are critically involved in the acquired immune system, suggesting that TLR ligands can directly modulate T cell function in addition to various innate immune cells. In this study, we report that in a murine model of chronic colitis induced in RAG-2−/− mice by adoptive transfer of CD4+CD45RBhigh T cells, both CD4+CD45RBhigh donor cells and the expanding colitogenic lamina propria CD4+CD44high memory cells expresses a wide variety of TLRs along with MyD88, a key adaptor molecule required for signal transduction through TLRs. Although RAG-2−/− mice transferred with MyD88−/−CD4+CD45RBhigh cells developed colitis, the severity was reduced with the delayed kinetics of clinical course, and the expansion of colitogenic CD4+ T cells was significantly impaired as compared with control mice transferred with MyD88+/+CD4+CD45RBhigh cells. When RAG-2−/− mice were transferred with the same number of MyD88+/+ (Ly5.1+) and MyD88−/− (Ly5.2+) CD4+CD45RBhigh cells, MyD88−/−CD4+ T cells showed significantly lower proliferative responses assessed by in vivo CFSE division assay, and also lower expression of antiapoptotic Bcl-2/Bcl-xL molecules and less production of IFN-γ and IL-17, compared with the paired MyD88+/+CD4+ T cells. Collectively, the MyD88-dependent pathway that controls TLR signaling in T cells may directly promote the proliferation and survival of colitogenic CD4+ T cells to sustain chronic colitis.

Analysis of Interferon Signaling by Infectious Hepatitis C Virus Clones with Substitutions of Core Amino Acids 70 and 91

ABSTRACT Substitution of amino acids 70 and 91 in the hepatitis C virus (HCV) core region is a significant predictor of poor responses to peginterferon-plus-ribavirin therapy, while their molecular mechanisms remain unclear. Here we investigated these differences in the response to alpha interferon (IFN) by using HCV cell culture with R70Q, R70H, and L91M substitutions. IFN treatment of cells transfected or infected with the wild type or the mutant HCV clones showed that the R70Q, R70H, and L91M core mutants were significantly more resistant than the wild type. Among HCV-transfected cells, intracellular HCV RNA levels were significantly higher for the core mutants than for the wild type, while HCV RNA in culture supernatant was significantly lower for these mutants than for the wild type. IFN-induced phosphorylation of STAT1 and STAT2 and expression of the interferon-inducible genes were significantly lower for the core mutants than for the wild type, suggesting cellular unresponsiveness to IFN. The expression level of an interferon signal attenuator, SOCS3, was significantly higher for the R70Q, R70H, and L91M mutants than for the wild type. Interleukin 6 (IL-6), which upregulates SOCS3, was significantly higher for the R70Q, R70H, and L91M mutants than for the wild type, suggesting interferon resistance, possibly through IL-6-induced, SOCS3-mediated suppression of interferon signaling. Expression levels of endoplasmic reticulum (ER) stress proteins were significantly higher in cells transfected with a core mutant than in those transfected with the wild type. In conclusion, HCV R70 and L91 core mutants were resistant to interferon in vitro, and the resistance may be induced by IL-6-induced upregulation of SOCS3. Those mechanisms may explain clinical interferon resistance of HCV core mutants.