Gastroenterology
Abstract
Colon cancer is a devastating illness that is associated with gut inflammation. Here, we explored the possible role of lipin-1, a phosphatidic acid phosphatase, in the development of colitis-associated tumorigenesis. Azoxymethane and dextran sodium sulfate–treated (DSS-treated) animals deficient in lipin-1 harbored fewer tumors and carcinomas than WT animals due to decreased cellular proliferation, lower expression of antiapoptotic and protumorigenic factors, and a reduced infiltration of macrophages in colon tumors. They also displayed increased resistance to DSS-induced colitis by producing less proinflammatory cytokines and experiencing less immune infiltration. Lipin-1–deficient macrophages from the colon were less activated and displayed lower phosphatidic acid phosphatase activity than WT macrophages isolated from DSS-treated animals. Transference of WT macrophages into lipin-1–deficient animals was sufficient to increase colitis burden. Furthermore, treatment of lipin-1–deficient mice with IL-23 exacerbated colon inflammation. Analysis of human databases from colon cancer and ulcerative colitis patients showed that lipin-1 expression is increased in those disorders and correlates with the expression of the proinflammatory markers CXCL1 and CXCL2. And finally, clinically, LPIN1 expression had prognostic value in inflammatory and stem-cell subtypes of colon cancers. Collectively, these data demonstrate that lipin-1 is a critical regulator of intestinal inflammation and inflammation-driven colon cancer development.
Authors
Clara Meana, Ginesa García-Rostán, Lucía Peña, Gema Lordén, África Cubero, Antonio Orduña, Balázs Győrffy, Jesús Balsinde, María A. Balboa
Abstract
Paneth cells contribute to small intestinal homeostasis by secreting antimicrobial peptides and constituting the intestinal stem cell (ISC) niche. Certain T cell–mediated enteropathies are characterized by extensive Paneth cell depletion coincident with mucosal destruction and dysbiosis. In this study, mechanisms of intestinal crypt injury have been investigated by characterizing responses of mouse intestinal organoids (enteroids) in coculture with mouse T lymphocytes. Activated T cells induced enteroid damage, reduced Paneth cell and Lgr5+ ISC mRNA levels, and induced Paneth cell death through a caspase-3/7–dependent mechanism. IFN-γ mediated these effects, because IFN-γ receptor–null enteroids were unaffected by activated T cells. In mice, administration of IFN-γ induced enteropathy with crypt hyperplasia, villus shortening, Paneth cell depletion, and modified ISC marker expression. IFN-γ exacerbated radiation enteritis, which was ameliorated by treatment with a selective JAK1/2 inhibitor. Thus, IFN-γ induced Paneth cell death and impaired regeneration of small intestinal epithelium in vivo, suggesting that IFN-γ may be a useful target for treating defective mucosal regeneration in enteric inflammation.
Authors
Yoshihiro Eriguchi, Kiminori Nakamura, Yuki Yokoi, Rina Sugimoto, Shuichiro Takahashi, Daigo Hashimoto, Takanori Teshima, Tokiyoshi Ayabe, Michael E. Selsted, André J. Ouellette
Abstract
Altered response to the intestinal microbiota strongly associates with inflammatory bowel disease (IBD); however, how commensal microbial cues are integrated by the host during the pathogenesis of IBD is not understood. Epigenetics represents a potential mechanism that could enable intestinal microbes to modulate transcriptional output during the development of IBD. Here, we reveal a histone methylation signature of intestinal epithelial cells isolated from the terminal ilea of newly diagnosed pediatric IBD patients. Genes characterized by significant alterations in histone H3-lysine 4 trimethylation (H3K4me3) showed differential enrichment in pathways involving immunoregulation, cell survival and signaling, and metabolism. Interestingly, a large subset of these genes was epigenetically regulated by microbiota in mice and several microbiota-sensitive epigenetic targets demonstrated altered expression in IBD patients. Remarkably though, a substantial proportion of these genes exhibited H3K4me3 levels that correlated with the severity of intestinal inflammation in IBD, despite lacking significant differential expression. Collectively, these data uncover a previously unrecognized epigenetic profile of IBD that can be primed by commensal microbes and indicate sensitive targets in the epithelium that may underlie how microbiota predispose to subsequent intestinal inflammation and disease.
Authors
Daniel Kelly, Michael Kotliar, Vivienne Woo, Sajjeev Jagannathan, Jordan Whitt, Jessica Moncivaiz, Bruce J. Aronow, Marla C. Dubinsky, Jeffrey S. Hyams, James F. Markowitz, Robert N. Baldassano, Michael C. Stephens, Thomas D. Walters, Subra Kugathasan, Yael Haberman, Nambirajan Sundaram, Michael J. Rosen, Michael Helmrath, Rebekah Karns, Artem Barski, Lee A. Denson, Theresa Alenghat
Abstract
SLC26A3 (downregulated in adenoma; DRA) is a Cl–/anion exchanger expressed in the luminal membrane of intestinal epithelial cells, where it facilitates electroneutral NaCl absorption. SLC26A3 loss of function in humans or mice causes chloride-losing diarrhea. Here, we identified slc26a3 inhibitors in a screen of 50,000 synthetic small molecules done in Fischer rat thyroid (FRT) cells coexpressing slc26a3 and a genetically encoded halide sensor. Structure-activity relationship studies were done on the most potent inhibitor classes identified in the screen: 4,8-dimethylcoumarins and acetamide-thioimidazoles. The dimethylcoumarin DRAinh-A250 fully and reversibly inhibited slc26a3-mediated Cl– exchange with HCO3–, I–, and thiocyanate (SCN–), with an IC50 of ~0.2 μM. DRAinh-A250 did not inhibit the homologous anion exchangers slc26a4 (pendrin) or slc26a6 (PAT-1), nor did it alter activity of other related proteins or intestinal ion channels. In mice, intraluminal DRAinh-A250 blocked fluid absorption in closed colonic loops but not in jejunal loops, while the NHE3 (SLC9A3) inhibitor tenapanor blocked absorption only in the jejunum. Oral DRAinh-A250 and tenapanor comparably reduced signs of constipation in loperamide-treated mice, with additive effects found on coadministration. DRAinh-A250 was also effective in loperamide-treated cystic fibrosis mice. These studies support a major role of slc26a3 in colonic fluid absorption and suggest the therapeutic utility of SLC26A3 inhibition in constipation.
Authors
Peter M. Haggie, Onur Cil, Sujin Lee, Joseph-Anthony Tan, Amber A. Rivera, Puay-Wah Phuan, Alan S. Verkman
Abstract
Adenosine-to-inosine (A-to-I) RNA editing, a process mediated by adenosine deaminases that act on the RNA (ADAR) gene family, is a recently discovered epigenetic modification dysregulated in human cancers. However, the clinical significance and the functional role of RNA editing in colorectal cancer (CRC) remain unclear. We have systematically and comprehensively investigated the significance of the expression status of ADAR1 and of the RNA editing levels of antizyme inhibitor 1 (AZIN1), one of the most frequently edited genes in cancers, in 392 colorectal tissues from multiple independent CRC patient cohorts. Both ADAR1 expression and AZIN1 RNA editing levels were significantly elevated in CRC tissues when compared with corresponding normal mucosa. High levels of AZIN1 RNA editing emerged as a prognostic factor for overall survival and disease-free survival and were an independent risk factor for lymph node and distant metastasis. Furthermore, elevated AZIN1 editing identified high-risk stage II CRC patients. Mechanistically, edited AZIN1 enhances stemness and appears to drive the metastatic processes. We have demonstrated that edited AZIN1 functions as an oncogene and a potential therapeutic target in CRC. Moreover, AZIN1 RNA editing status could be used as a clinically relevant prognostic indicator in CRC patients.
Authors
Kunitoshi Shigeyasu, Yoshinaga Okugawa, Shusuke Toden, Jinsei Miyoshi, Yuji Toiyama, Takeshi Nagasaka, Naoki Takahashi, Masato Kusunoki, Tetsuji Takayama, Yasuhide Yamada, Toshiyoshi Fujiwara, Leilei Chen, Ajay Goel
Abstract
Functional bowel disorder patients can suffer from chronic abdominal pain, likely due to visceral hypersensitivity to mechanical stimuli. As there is only a limited understanding of the basis of chronic visceral hypersensitivity (CVH), drug-based management strategies are ill defined, vary considerably, and include NSAIDs, opioids, and even anticonvulsants. We previously reported that the 1.1 subtype of the voltage-gated sodium (NaV; NaV1.1) channel family regulates the excitability of sensory nerve fibers that transmit a mechanical pain message to the spinal cord. Herein, we investigated whether this channel subtype also underlies the abdominal pain that occurs with CVH. We demonstrate that NaV1.1 is functionally upregulated under CVH conditions and that inhibiting channel function reduces mechanical pain in 3 mechanistically distinct mouse models of chronic pain. In particular, we use a small molecule to show that selective NaV1.1 inhibition (a) decreases sodium currents in colon-innervating dorsal root ganglion neurons, (b) reduces colonic nociceptor mechanical responses, and (c) normalizes the enhanced visceromotor response to distension observed in 2 mouse models of irritable bowel syndrome. These results provide support for a relationship between NaV1.1 and chronic abdominal pain associated with functional bowel disorders.
Authors
Juan Salvatierra, Joel Castro, Andelain Erickson, Qian Li, Joao Braz, John Gilchrist, Luke Grundy, Grigori Y. Rychkov, Annemie Deiteren, Rana Rais, Glenn F. King, Barbara S. Slusher, Allan Basbaum, Pankaj J. Pasricha, Stuart M. Brierley, Frank Bosmans
Abstract
BACKGROUND. Myeloid-derived suppressor cells (MDSCs) are a population of immature immune cells with several protumorigenic functions. CD38 is a transmembrane receptor–ectoenzyme expressed by MDSCs in murine models of esophageal cancer. We hypothesized that CD38 could be expressed on MDSCs in human colorectal cancer (CRC), which might allow for a new perspective on therapeutic targeting of human MDSCs with anti-CD38 monoclonal antibodies in this cancer. METHODS. Blood samples were collected from 41 CRC patients and 8 healthy donors, followed by peripheral blood mononuclear cell (PBMC) separation. Polymorphonuclear (PMN-) and monocytic (M-) MDSCs and CD38 expression levels were quantified by flow cytometry. The immunosuppressive capacity of M-MDSCs from 10 CRC patients was validated in a mixed lymphocyte reaction (MLR) assay. RESULTS. A significant expansion of CD38+ M-MDSCs and a trend of expansion of CD38+ PMN-MDSCs (accompanied by a trend of increased CD38 expression on both M- and PMN-MDSCs) were observed in PBMCs of CRC patients when compared with healthy donors. The CD38+ M-MDSCs from CRC patients were found to be immunosuppressive when compared with mature monocytes. CD38+ M- and PMN-MDSC frequencies were significantly higher in CRC patients who previously received treatment when compared with treatment-naive patients. CONCLUSIONS. This study provides a rationale for an attempt to target M-MDSCs with an anti-CD38 monoclonal antibody in metastatic CRC patients. FUNDING. NCI P01-CA14305603, the American Cancer Society, Scott and Suzi Lustgarten Family Colon Cancer Research Fund, Hansen Foundation, and Janssen Research and Development.
Authors
Tatiana A. Karakasheva, George A. Dominguez, Ayumi Hashimoto, Eric W. Lin, Christopher Chiu, Kate Sasser, Jae W. Lee, Gregory L. Beatty, Dmitry I. Gabrilovich, Anil K. Rustgi
Abstract
Inflammatory bowel disease (IBD) is associated with enhanced levels of the IL-1 family cytokines IL-1β and IL-18, which are activated by the Nlrp3 inflammasome. Here, we investigated the role of inflammasome-driven cytokine release on T cell polarization and DC differentiation in steady state and T cell transfer colitis. In vitro and in vivo data showed that IL-1β induces Th17 polarization and increases GM‑CSF production by T cells. Reduced IL-1β levels in Nlrp3–/– mice correlated with enhanced FLT3L levels and increased frequency of tolerogenic CD103+ DC. In the T cell transfer colitis model, Nlrp3 deficiency resulted in lower IL‑1β levels, reduced Th17 immunity, and less severe colitis. Unaltered IL-18 levels in both mouse strains pointed toward Nlrp3-independent processing. Importantly, cohousing revealed that the gut microbiome had no impact on the observed Nlrp3–/– phenotype. This study demonstrates that NLRP3 acts as a molecular switch of intestinal homeostasis by shifting local immune cells toward an inflammatory phenotype via IL-1β.
Authors
Rachel Mak’Anyengo, Peter Duewell, Cornelia Reichl, Christine Hörth, Hans‑Anton Lehr, Sandra Fischer, Thomas Clavel, Gerald Denk, Simon Hohenester, Sebastian Kobold, Stefan Endres, Max Schnurr, Christian Bauer
Abstract
Crohn’s disease (CD) is a chronic inflammatory disease of the gastrointestinal tract (GIT). Cigarette smoke (CS) exposure and chronic obstructive pulmonary disease (COPD) are risk factors for CD, although the mechanisms involved are poorly understood. We employed a mouse model of CS-induced experimental COPD and clinical studies to examine these mechanisms. Concurrent with the development of pulmonary pathology and impaired gas exchange, CS-exposed mice developed CD-associated pathology in the colon and ileum, including gut mucosal tissue hypoxia, HIF-2 stabilization, inflammation, increased microvasculature, epithelial cell turnover, and decreased intestinal barrier function. Subsequent smoking cessation reduced GIT pathology, particularly in the ileum. Dimethyloxaloylglycine, a pan-prolyl hydroxylase inhibitor, ameliorated CS-induced GIT pathology independently of pulmonary pathology. Prior smoke exposure exacerbated intestinal pathology in 2,4,6-trinitrobenzenesulfonic acid–induced (TNBS-induced) colitis. Circulating vascular endothelial growth factor, a marker of systemic hypoxia, correlated with CS exposure and CD in mice and humans. Increased mucosal vascularisation was evident in ileum biopsies from CD patients who smoke compared with nonsmokers, supporting our preclinical data. We provide strong evidence that chronic CS exposure and, for the first time to our knowledge, associated impaired gas exchange cause systemic and intestinal ischemia, driving angiogenesis and GIT epithelial barrier dysfunction, resulting in increased risk and severity of CD.
Authors
Michael Fricker, Bridie J. Goggins, Sean Mateer, Bernadette Jones, Richard Y. Kim, Shaan L. Gellatly, Andrew G. Jarnicki, Nicholas Powell, Brian G. Oliver, Graham Radford-Smith, Nicholas J. Talley, Marjorie M. Walker, Simon Keely, Philip M. Hansbro
Mutant p53R270H drives altered metabolism and increased invasion in pancreatic ductal adenocarcinoma
Abstract
Pancreatic cancer is characterized by nearly universal activating mutations in KRAS. Among other somatic mutations, TP53 is mutated in more than 75% of human pancreatic tumors. Genetically engineered mice have proven instrumental in studies of the contribution of individual genes to carcinogenesis. Oncogenic Kras mutations occur early during pancreatic carcinogenesis and are considered an initiating event. In contrast, mutations in p53 occur later during tumor progression. In our model, we recapitulated the order of mutations of the human disease, with p53 mutation following expression of oncogenic Kras. Further, using an inducible and reversible expression allele for mutant p53, we inactivated its expression at different stages of carcinogenesis. Notably, the function of mutant p53 changes at different stages of carcinogenesis. Our work establishes a requirement for mutant p53 for the formation and maintenance of pancreatic cancer precursor lesions. In tumors, mutant p53 becomes dispensable for growth. However, it maintains the altered metabolism that characterizes pancreatic cancer and mediates its malignant potential. Further, mutant p53 promotes epithelial-mesenchymal transition (EMT) and cancer cell invasion. This work generates new mouse models that mimic human pancreatic cancer and expands our understanding of the role of p53 mutation, common in the majority of human malignancies.
Authors
Heather K. Schofield, Jörg Zeller, Carlos Espinoza, Christopher J. Halbrook, Annachiara del Vecchio, Brian Magnuson, Tania Fabo, Ayse Ece Cali Daylan, Ilya Kovalenko, Ho-Joon Lee, Wei Yan, Ying Feng, Saadia A. Karim, Daniel M. Kremer, Chandan Kumar-Sinha, Costas A. Lyssiotis, Mats Ljungman, Jennifer P. Morton, Stefanie Galbán, Eric R. Fearon, Marina Pasca di Magliano
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