Gastroenterology
Abstract
Hepatic ischemia and reperfusion (IR) injury contributes to the morbidity and mortality associated with liver transplantation. microRNAs (miRNAs) constitute a family of noncoding RNAs that regulate gene expression at the posttranslational level through the repression of specific target genes. Here, we hypothesized that miRNAs could be targeted to enhance hepatic ischemia tolerance. A miRNA screen in a murine model of hepatic IR injury pointed us toward the liver-specific miRNA miR122. Subsequent studies in mice with hepatocyte-specific deletion of miR122 (miR122loxP/loxP Alb-Cre+ mice) during hepatic ischemia and reperfusion revealed exacerbated liver injury. Transcriptional studies implicated hypoxia-inducible factor–1α (HIF1α) in the induction of miR122 and identified the oxygen-sensing prolyl hydroxylase domain 1 (PHD1) as a miR122 target. Further studies indicated that HIF1α-dependent induction of miR122 participated in a feed-forward pathway for liver protection via the enhancement of hepatic HIF responses through PHD1 repression. Moreover, pharmacologic studies utilizing nanoparticle-mediated miR122 overexpression demonstrated attenuated liver injury. Finally, proof-of-principle studies in patients undergoing orthotopic liver transplantation showed elevated miR122 levels in conjunction with the repression of PHD1 in post-ischemic liver biopsies. Taken together, the present findings provide molecular insight into the functional role of miR122 in enhancing hepatic ischemia tolerance and suggest the potential utility of pharmacologic interventions targeting miR122 to dampen hepatic injury during liver transplantation.
Authors
Cynthia Ju, Meng Wang, Eunyoung Tak, Boyun Kim, Christoph Emontzpohl, Yang Yang, Xiaoyi Yuan, Huban Kutay, Yafen Liang, David R. Hall, Wasim A. Dar, J. Steve Bynon, Peter Carmeliet, Kalpana Ghoshal, Holger K. Eltzschig
Abstract
A primordial gut-epithelial innate defense response is the release of hydrogen peroxide by dual NADPH oxidase (DUOX). In inflammatory bowel disease (IBD), a condition characterized by an imbalanced gut microbiota-immune homeostasis, DUOX2 isoenzyme is the highest induced gene. Performing multi-omic analyses using 2,872 human participants of a wellness program, we detected a substantial burden of rare protein-altering DUOX2 gene variants of unknown physiologic significance (155 unique variants with allele frequency < 1%; 12.9% carrier rate). We identified a significant association between these rare loss-of-function variants and increased plasma levels of interleukin-17C (FDR=2.6e-5), which is induced also in mucosal biopsies of IBD patients. DUOX2 deficient mice replicated increased IL17C induction in the intestine, with outlier high Il17c expression linked to the mucosal expansion of specific Proteobacteria pathobionts. Integrated microbiota/host gene expression analyses in IBD patients corroborated IL17C as a marker for epithelial activation by gram-negative bacteria. Finally, the impact of DUOX2 variants on IL17C induction provided a rationale for variant stratification in case-control studies that substantiated DUOX2 as an IBD risk gene (pooled OR = 1.54 [95% CI 1.09-2.18]; P = 7.1e-4). Thus, our study identifies an association of deleterious DUOX2 variants with a preclinical hallmark of disturbed microbiota-immune homeostasis that appears to precede the manifestation of IBD.
Authors
Helmut Grasberger, Andrew T. Magis, Elisa Sheng, Matthew P. Conomos, Min Zhang, Lea S. Garzotto, Guoqing Hou, Shrinivas Bishu, Hiroko Nagao-Kitamoto, Mohamad El-Zataari, Sho Kitamoto, Nobuhiko Kamada, Ryan Stidham, Yasutada Akiba, Jonathan Kaunitz, Yael Haberman, Subra Kugathasan, Lee A. Denson, Gilbert S. Omenn, John Y. Kao
Abstract
Omega-3 fatty acids from fish oil reduce triglyceride levels in mammals, yet the mechanisms underlying this effect have not been fully clarified despite the clinical use of omega-3 ethyl esters to treat severe hypertriglyceridemia and reduce cardiovascular disease risk in humans. Here we identified in bile a class of hypotriglyceridemic omega-3 fatty acid-derived N-acyl taurines (NATs) that, after dietary omega-3 fatty acid supplementation, increased to concentrations similar to those of steroidal bile acids. The biliary docosahexaenoic acid (DHA) containing NAT, C22:6 NAT, was increased in human and mouse plasma after dietary omega-3 fatty acid supplementation and potently inhibited intestinal triacylglycerol hydrolysis and lipid absorption. Supporting this observation, genetic elevation of endogenous NAT levels in mice impaired lipid absorption, while selective augmentation of C22:6 NAT levels protected against hypertriglyceridemia and fatty liver. When administered pharmacologically, C22:6 NAT accumulated in bile and reduced high fat diet-induced, but not sucrose-induced, hepatic lipid accumulation in mice, suggesting that C22:6 NAT was a negative feedback mediator that limited excess intestinal lipid absorption. Thus, biliary omega-3 NATs may contribute to the hypotriglyceridemic mechanism of action of fish oil and could influence the design of more potent omega-3 fatty acid-based therapeutics.
Authors
Trisha J. Grevengoed, Samuel A. J. Trammell, Jens S. Svenningsen, Mikhail Makarov, Thomas Svava Nielsen, Jens C. B. Jacobsen, Philip C. Calder, Marie E. Migaud, Benjamin Cravatt, Matthew P. Gillum
Abstract
Hirschsprung disease (HSCR) is the most frequent developmental anomaly of the enteric nervous system with an incidence of 1/5000 live births. Chronic intestinal pseudo-obstruction (CIPO) is less frequent and classified as neurogenic or myogenic. Isolated HSCR has an oligogenic inheritance with RET as the major disease-causing gene, while CIPO is genetically heterogeneous, caused by mutations in smooth muscle-specific genes. Here, we describe a series of patients with developmental disorders including gastrointestinal dysmotility, and investigate the underlying molecular bases. Trio-exome sequencing led to the identification of biallelic variants in ERBB3 and ERBB2 in eight individuals variably associating HSCR, CIPO, peripheral neuropathy and arthrogryposis. Thorough gut histology revealed aganglionosis, hypoganglionosis and intestinal smooth muscle abnormalities. The cell-type-specific ErbB3 and ErbB2 function was further analysed in mouse single-cell RNA sequencing data and in a conditional ErbB3-deficient mouse model, revealing a primary role for ERBB3 in enteric progenitors. The consequences of the identified variants were evaluated using RT-qPCR on patient-derived fibroblasts or immunoblot assays on Neuro-2a cells overexpressing either wild-type or mutant proteins, revealing either decreased expression or altered phosphorylation of the mutant receptors. Our results demonstrate that dysregulation of ERBB3 or ERBB2 leads to a broad spectrum of developmental anomalies including intestinal dysmotility.
Authors
Thuy-Linh Le, Louise Galmiche, Jonathan Levy, Pim Suwannarat, Debby M.E.I. Hellebrekers, Khomgrit Morarach, Franck Boismoreau, Tom E.J. Theunissen, Mathilde Lefebvre, Anna Pelet, Jelena Martinovic, Antoinette Gelot, Fabien Guimiot, Amanda Calleroz, Cyril Gitiaux, Marie Hully, Olivier Goulet, Christophe Chardot, Severine Drunat, Yline Capri, Christine Bole-Feysot, Patrick Nitschke, Sandra Whalen, Linda Mouthon, Holly E. Babcock, Robert Hofstra, Irenaeus F.M. de Coo, Anne-Claude Tabet, Thierry J. Molina, Boris Keren, Alice S. Brooks, Hubert J.M. Smeets, Ulrika Marklund, Christopher T. Gordon, Stanislas Lyonnet, Jeanne Amiel, Nadège Bondurand
Abstract
Innate lymphoid cells (ILCs) are enriched at barrier surfaces, including the gastrointestinal tract. While most studies have focused on the balance between pathogenic group 1 ILCs (ILC1s) and protective ILC3s in maintaining gut homeostasis and during chronic intestinal inflammation, such as Crohn’s disease (CD), less is known regarding ILC2s. Using an established murine model of CD-like ileitis, i.e., SAMP1/YitFc (SAMP) strain, we showed that ILC2s, compared to ILC1s and ILC3s, were increased within draining mesenteric lymph nodes and ilea of SAMP vs. AKR (parental control) mice early, during the onset of disease. Gut-derived ILC2s from Crohn’s patients vs. healthy controls were also increased and expand, similar to ILC1s, in greater proportion compared to ILC3s. Importantly, we report that the intracellular bacterial-sensing protein, nucleotide-binding oligomerization domaining-containing protein-2, encoded by NOD2, the first and strongest susceptibility gene identified for CD, promoted ILC2 expansion, which was dramatically reduced in SAMP lacking NOD2 and SAMP raised under germ-free conditions. Furthermore, these effects occurred through a mechanism involving the IL-33/ST2 ligand-receptor pair. Collectively, our results indicate a functional link between NOD2 and ILC2s, regulated by the IL-33/ST2 axis, that mechanistically may contribute to early events leading to CD pathogenesis.
Authors
Carlo De Salvo, Kristine-Ann Buela, Brecht Creyns, Daniele Corridoni, Nitish Rana, Hannah L. Wargo, Chiara Cominelli, Peter G. Delaney, Fabio Cominelli, Alexander Rodriguez-Palacios, Séverine Vermeire, Theresa T. Pizarro
Abstract
Chronic pancreatitis affects over 250,000 people in the US and millions worldwide. It is associated with chronic debilitating pain, pancreatic exocrine failure, high-risk of pancreatic cancer, and usually progresses to diabetes. Treatment options are limited and ineffective. We developed a new potential therapy, wherein a pancreatic ductal infusion of 1-2% acetic acid in mice and non-human primates resulted in a non-regenerative, near-complete ablation of the exocrine pancreas, with complete preservation of the islets. Pancreatic ductal infusion of acetic acid in a mouse model of chronic pancreatitis led to resolution of chronic inflammation and pancreatitis-associated pain. Furthermore, acetic acid-treated animals showed improved glucose tolerance and insulin secretion. The loss of exocrine tissue in this procedure would not typically require further management in patients with chronic pancreatitis because they usually have pancreatic exocrine failure requiring dietary enzyme supplements. Thus, this procedure, which should be readily translatable to humans through an endoscopic retrograde cholangiopancreatography (ERCP), may offer a potential innovative non-surgical therapy for chronic pancreatitis that relieves pain and prevents the progression of pancreatic diabetes.
Authors
Mohamed Saleh, Kartikeya Sharma, Ranjeet S. Kalsi, Joseph C. Fusco, Anuradha Sehrawat, Jami L. Saloman, Ping Guo, Ting Zhang, Nada Mohamed, Yan Wang, Krishna Prasadan, George Gittes
Abstract
As the interface between the gut microbiota and the mucosal immune system, there has been great interest in the maintenance of colonic epithelial integrity through mitochondrial oxidation of butyrate, a short-chain fatty acid produced by the gut microbiota. Herein, we showed that the intestinal epithelium can also oxidize long-chain fatty acids, and that luminally-delivered acylcarnitines in bile can be consumed via apical absorption by the intestinal epithelium resulting in mitochondrial oxidation. Finally, intestinal inflammation led to mitochondrial dysfunction in the apical domain of the surface epithelium that may reduce the consumption of fatty acids, contributing to higher concentrations of fecal acylcarnitines in murine Citrobacter rodentium-induced colitis and human inflammatory bowel disease. These results emphasized the importance of both the gut microbiota and the liver in the delivery of energy substrates for mitochondrial metabolism by the intestinal epithelium.
Authors
Sarah A. Smith, Sayaka A. Ogawa, Lillian Chau, Kelly A. Whelan, Kathryn E. Hamilton, Jie Chen, Lu Tan, Eric Z. Chen, Sue Keilbaugh, Franz Fogt, Meenakshi Bewtra, Jonathan Braun, Ramnik J. Xavier, Clary B. Clish, Barry Slaff, Aalim M. Weljie, Frederic D. Bushman, James D. Lewis, Hongzhe Li, Stephen R. Master, Michael J. Bennett, Hiroshi Nakagawa, Gary D. Wu
Abstract
A growing number of long non-coding RNAs (lncRNAs) have emerged as vital metabolic regulators. However, most human lncRNAs are non-conserved and highly tissue-specific, vastly limiting our ability to identify human lncRNA metabolic regulators (hLMRs). In this study, we establish a pipeline to identify putative hLMRs that are metabolically sensitive, disease-relevant, and population applicable. We first progressively processed multilevel human transcriptome data to select liver lncRNAs that exhibit highly dynamic expression in the general population, show differential expression in a nonalcoholic fatty liver disease (NAFLD) population, and response to dietary intervention in a small NAFLD cohort. We then experimentally demonstrated the responsiveness of selected hepatic lncRNAs to defined metabolic milieus in a liver-specific humanized mouse model. Furthermore, by extracting a concise list of protein-coding genes that are persistently correlated with lncRNAs in general and NAFLD populations, we predicted the specific function for each hLMR. Using gain- and loss-of-function approaches in humanized mice as well as ectopic expression in conventional mice, we validated the regulatory role of one non-conserved hLMR in cholesterol metabolism by coordinating with an RNA-binding protein, PTBP1, to modulate the transcription of cholesterol synthesis genes. Our work overcome the heterogeneity intrinsic to human data to enable the efficient identification and functional definition of disease-relevant human lncRNAs in metabolic homeostasis.
Authors
Xiangbo Ruan, Ping Li, Yonghe Ma, Chengfei Jiang, Yi Chen, Yu Shi, Nikhil Gupta, Fayaz Seifuddin, Mehdi Pirooznia, Yasuyuki Ohnishi, Nao Yoneda, Megumi Nishiwaki, Gabrijela Dumbovic, John L. Rinn, Yuichiro Higuchi, Kenji Kawai, Hiroshi Suemizu, Haiming Cao
Abstract
Protein tyrosine phosphatase non-receptor type 2 (PTPN2) recently emerged as a promising cancer immunotherapy target. We set to investigate the functional role of PTPN2 in the pathogenesis of human colorectal carcinoma (CRC) as its role in immune-silent solid tumors is poorly understood. We demonstrate that in human CRC, increased PTPN2 expression and activity correlated with disease progression and decreased immune responses in tumor tissues. Particularly, stage II and III tumors displayed enhanced PTPN2 protein expression in tumor-infiltrating T-cells and increased PTPN2 levels negatively correlated with PD1, CTLA4, STAT1 and granzyme A. In vivo, T-cell and dendritic cell-specific PTPN2 deletion reduced tumor burden in several CRC models by promoting CD44+ effector/memory T-cells, as well as CD8+ T-cell infiltration and cytotoxicity into the tumor. In direct relevance to CRC treatment, T-cell-specific PTPN2 deletion potentiated anti-PD-1 efficacy and induced anti-tumor memory formation upon tumor re-challenge in vivo. Our data suggest a role for PTPN2 in suppressing anti-tumor immunity and promoting tumor development in CRC patients. Our in vivo results uncover PTPN2 as a key player in controlling immunogenicity of CRC, with the strong potential to be exploited to promote cancer immunotherapy.
Authors
Egle Katkeviciute, Larissa Hering, Ana Montalban-Arques, Philipp Busenhart, Marlene Schwarzfischer, Roberto Manzini, Javier Conde, Kirstin Atrott, Silvia Lang, Gerhard Rogler, Elisabeth Naschberger, Vera S. Schellerer, Michael Stürzl, Andreas Rickenbacher, Matthias Turina, Achim Weber, Sebastian Leibl, Gabriel E. Leventhal, Mitchell Levesque, Onur Boyman, Michael Scharl, Marianne R. Spalinger
Abstract
Interstitial cells of Cajal (ICCs) are pacemaker cells in the intestine, and their function can be compromised due to loss of C-KIT expression. Macrophage activation has been identified in intestine affected by Hirschsprung disease associated enterocolitis (HAEC). In this study, we examined proinflammatory macrophage activation and explored the mechanisms by which this down-regulates C-KIT expression in ICCs in colon affected by HAEC. We found that macrophage activation and TNF-α production were dramatically increased in the proximal dilated colon of HAEC patients and 3-week old Ednrb-/- mice. Moreover, ICCs lost their C-KIT+ phenotype in the dilated colon, resulting in damaged pacemaker function and intestinal dysmotility. However, macrophage depletion or TNF-α neutralization led to recovery of ICC phenotype and restored their pacemaker function. In isolated ICCs, TNF-α-mediated phosphorylated-P65 induced over-expression of miR221, resulting in suppression of C-KIT expression and pacemaker currents. We also identified a TNF-α-NF-κB-miR221 pathway which downregulated C-KIT expression in ICCs in the colon affected by HAEC. These findings suggest the important roles of proinflammatory macrophage activation in a phenotypic switch of ICCs, representing a promising therapeutic target for HAEC.
Authors
Xuyong Chen, Xinyao Meng, Hongyi Zhang, Chenzhao Feng, Bin Wang, Ning Li, Khalid Mohamoud Abdullahi, Xiaojuan Wu, Jixin Yang, Zhi Li, Chunlei Jiao, Jia Wei, Xiaofeng Xiong, Kang Fu, Lei Yu, Gail Besner, Jiexiong Feng
Copyright © 2021 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)