Gastroenterology
Abstract
MicroRNA-29 (miR-29) is a critical regulator of fibro-inflammatory processes in human diseases. In this study, we find a decrease in miR-29a in experimental and human chronic pancreatitis leading us to investigate the regulatory role of miR-29a/b1 cluster in acute pancreatitis (AP) utilizing a novel conditional miR-29a/b1 knockout (KO) mouse model. miR-29a/b1 sufficient (WT) and deficient (KO) mice were administered with supramaximal caerulein to induce AP and characterized at different timepoints, utilizing an array of immunohistochemical and biochemical analyses for AP parameters. In caerulein-induced WT mice, miR-29a remained dramatically downregulated at injury. Despite high inflammatory milieu, fibrosis and parenchymal disarray in the WT mice during early AP, the pancreata fully restored during recovery. Whereas miR-29a/b1 KO mice showed significantly greater inflammation, lymphocyte infiltration, macrophage polarization and ECM deposition, continuing until late recovery with persistent parenchymal disorganization. The increased pancreatic fibrosis was accompanied by enhanced TGFb1 coupled with persistent aSMA+ PSC activation. Additionally, these mice exhibited higher circulating IL6 and inflammation in lung parenchyma. Together, this collection of studies indicates that depletion of miR-29a/b1 cluster impacts the fibro-inflammatory mechanisms of AP resulting in (i) aggravated pathogenesis, and (ii) delayed recovery from the disease, suggesting a protective role of the molecule against AP.
Authors
Shatovisha Dey, Lata M. Udari, Primavera RiveraHernandez, Jason J. Kwon, Brandon Willis, Jeffrey J. Easler, Evan L. Fogel, Stephen Pandol, Janaiah Kota
Abstract
Hyperstimulation of the cholecystokinin receptor (CCK1R), a Gq-protein coupled receptor (GPCR), in pancreatic acinar cells is commonly used to induce pancreatitis in rodents. Human pancreatic acinar cells lack CCK1R but express cholinergic receptor muscarinic 3 (M3R), another GPCR. To test whether M3R activation is involved in pancreatitis, a mutant M3R was conditionally expressed in pancreatic acinar cells in mice. This mutant receptor loses responsiveness to its native ligand acetylcholine but can be activated by an inert small molecule, clozapine-N-oxide (CNO). Intracellular calcium and amylase were elicited by CNO in pancreatic acinar cells isolated from mutant M3R mice but not WT mice. Similarly, acute pancreatitis (AP) could be induced by a single injection of CNO in the transgenic mice but not WT mice. Compared with the cerulein-induced AP, CNO caused more widespread acinar cell death and inflammation. Furthermore, chronic pancreatitis developed at 4 weeks after 3 episodes of CNO-induced AP. In contrast, in mice with three recurrent episodes of cerulein-included AP, pancreas histology was restored in 4 weeks. Furthermore, the M3R antagonist ameliorated the severity of cerulein-induced AP in WT mice. We conclude that M3R activation can cause the pathogenesis of pancreatitis. This model may provide an alternative approach for pancreatitis research.
Authors
Jianhua Wan, Jiale Wang, Larry E. Wagner II, Oliver H. Wang, Fu Gui, Jiaxiang Chen, Xiaohui Zhu, Ashley N. Haddock, Brandy H. Edenfield, Brian Haight, Debabrata Mukhopadhyay, Ying Wang, David I. Yule, Yan Bi, Baoan Ji
Abstract
Functional loss of MYO5B induces a variety of deficits in intestinal epithelial cell function and causes a congenital diarrheal disorder, microvillus inclusion disease (MVID). The impact of MYO5B loss on differentiated cell lineage choice has not been investigated. We quantified the populations of differentiated epithelial cells in tamoxifen-induced epithelial-specific MYO5B knockout (VilCreERT2;Myo5bflox/flox) mice utilizing digital image analysis. Consistent with our RNA-sequencing data, MYO5B loss induced a reduction in tuft cells in vivo and in organoid cultures. Paneth cells were significantly increased by MYO5B deficiency along with expansion of the progenitor cell zone. We further investigated the effect of lysophosphatidic acid (LPA) signaling on epithelial cell differentiation. Intraperitoneal LPA significantly increased tuft cell populations both in control and MYO5B knockout mice. Transcripts for Wnt ligands were significantly downregulated by MYO5B loss in intestinal epithelial cells, whereas Notch signaling molecules were unchanged. Additionally, treatment with the Notch inhibitor, dibenzazepine (DBZ), restored the populations of secretory cells, suggesting that the Notch pathway is maintained in MYO5B-deficient intestine. MYO5B loss likely impairs progenitor cell differentiation in the small intestine in vivo and in vitro, partially mediated by Wnt/Notch imbalance. Notch inhibition and/or LPA treatment may represent an effective therapeutic approach for treatment of MVID.
Authors
Izumi Kaji, Joseph T. Roland, Sudiksha Rathan-Kumar, Amy C. Engevik, Andreanna Burman, Anna E. Goldstein, Masahiko Watanabe, James R. Goldenring
Abstract
Background: Abdominal pain and constipation are two main symptoms in patients with constipation-predominant irritable bowel syndrome (IBS-C). This study aimed to investigate the effects and possible mechanisms of transcutaneous auricular vagal nerve stimulation (taVNS) in patients with IBS-C. Methods: Forty-two patients with IBS-C were randomized into a 4-week sham-taVNS or taVNS treatment. The primary outcomes were complete spontaneous bowel movements per week (CSBMs/week) and visual analog scale (VAS) for abdominal pain. High-resolution anorectal manometry (HRAM) was performed to evaluate anorectal motor and sensory function. Cytokines and brain gut peptides were analyzed in blood samples. Electrocardiogram (ECG) was recorded for the assessment of autonomic function. Results: Compared with sham-taVNS, (1) taVNS increased CSBMs/week (P = 0.001) and decreased VAS pain score (P = 0.001); (2) It also improved quality of life (P = 0.020) and decreased IBS symptom score (P = 0.001); (3) taVNS improved rectoanal inhibitory reflex (P=0.014), and improved rectal sensation (P <0.04); (4) taVNS also decreased a number of pro-inflammatory cytokines and serotonin in circulation; (5) taVNS enhanced vagal activity (P = 0.040). The vagal activity was weakly correlated with the CSBMs/week (r = 0.391; P = 0.010) and the VAS pain score (r = -0.347; P = 0.025). Conclusions: Noninvasive taVNS improves both constipation and abdominal pain in patients with IBS-C. The improvement in IBS-C symptoms might be attributed to the integrative effects of taVNS on intestinal functions mediated via the autoimmune mechanisms. Trial registration: www.chictr.org.cn ChiCTR2000029644. Funding: National Natural Science Foundation of China (Grant No. 81970538 for Fei Liu).
Authors
Xiaodan Shi, Yedong Hu, Bo Zhang, Wenna Li, Jiande DZ Chen, Fei Liu
Abstract
Cancer cells re-program cellular metabolism to maintain adequate nutrient pools to sustain proliferation. Moreover, autophagy is a regulated mechanism to breakdown dysfunctional cellular components and recycle cellular nutrients. However, the requirement for autophagy and the integration in cancer cell metabolism is not clear in colon cancer. Here we show a cell-autonomous dependency of autophagy for cell growth in colorectal cancer. Loss of epithelial autophagy inhibits tumor growth in both sporadic and colitis associated cancer models. Genetic and pharmacological inhibition of autophagy inhibits cell growth in colon cancer-derived cell lines and patient-derived enteroid models. Importantly, normal colon epithelium and patient-derived normal enteroid growth was not decreased following autophagy inhibition. To couple the role of autophagy to cellular metabolism, a cell culture screen in conjunction with metabolomic analysis was performed. We identified a critical role of autophagy to maintain mitochondrial metabolites for growth. Loss of mitochondrial recycling through inhibition of mitophagy hinders colon cancer cell growth. These findings have revealed a cell-autonomous role of autophagy that plays a critical role in regulating nutrient pools in vivo and in cell models and provides therapeutic targets for colon cancer.
Authors
Samantha N. Devenport, Rashi Singhal, Megan D. Radyk, Joseph G. Taranto, Samuel A. Kerk, Brandon Chen, Joshua W. Goyert, Chesta Jain, Nupur K. Das, Katherine Oravecz-Wilson, Li Zhang, Joel K. Greenson, Y. Eugene Chen, Scott A. Soleimanpour, Pavan Reddy, Costas A. Lyssiotis, Yatrik M. Shah
Abstract
SLC26A6 (also known as putative anion transporter 1 [PAT1]) is a Cl–/HCO3– exchanger expressed at the luminal membrane of enterocytes where it facilitates intestinal Cl– and fluid absorption. Here, high-throughput screening of 50,000 synthetic small molecules in cells expressing PAT1 and a halide-sensing fluorescent protein identified several classes of inhibitors. The most potent compound, the pyrazolo-pyrido-pyrimidinone PAT1inh-B01, fully inhibited PAT1-mediated anion exchange (IC50 ~350 nM), without inhibition of the related intestinal transporter SLC26A3 (also known as DRA). In closed midjejunal loops in mice, PAT1inh-B01 inhibited fluid absorption by 50%, which increased to >90% when coadministered with DRA inhibitor DRAinh-A270. In ileal loops, PAT1inh-B01 blocked fluid absorption by >80%, whereas DRAinh-A270 was without effect. In colonic loops, PAT1inh-B01 was without effect, whereas DRAinh-A270 completely blocked fluid absorption. In a loperamide constipation model, coadministration of PAT1inh-B01 with DRAinh-A270 increased stool output compared with DRAinh-A270 alone. These results provide functional evidence for complementary and region-specific roles of PAT1 and DRA in intestinal fluid absorption, with PAT1 as the predominant anion exchanger in mouse ileum. We believe that PAT1inh-B01 is a novel tool to study intestinal ion and fluid transport and perhaps a drug candidate for small intestinal hyposecretory disorders such as cystic fibrosis–related meconium ileus and distal intestinal obstruction syndrome.
Authors
Onur Cil, Peter M. Haggie, Joseph-Anthony Tapia Tan, Amber A. Rivera, Alan S. Verkman
Abstract
Retinoic acid (RA) signaling is essential for enteric nervous system (ENS) development since vitamin A deficiency or mutations in RA signaling profoundly reduce bowel colonization by ENS precursors. These RA effects could occur because of RA activity within the ENS lineage or via RA activity in other cell types. To define cell-autonomous roles for retinoid signaling within the ENS lineage at distinct developmental time points, we activated a potent floxed dominant-negative RA receptor α (RarαDN) in the ENS using diverse CRE recombinase-expressing mouse lines. This strategy enabled us to block RA signaling at pre-migratory, migratory, and post-migratory stages for ENS precursors. We found that cell-autonomous loss of retinoic acid receptor (RAR) signaling dramatically affects ENS development. CRE activation of RarαDN expression at pre-migratory or migratory stages caused severe intestinal aganglionosis, but at later stages, RarαDN induced a broad range of phenotypes including hypoganglionosis, submucosal plexus loss, and abnormal neural differentiation. RNA-sequencing highlighted distinct RA-regulated gene sets at different developmental stages. These studies show complicated context-dependent RA-mediated regulation of ENS development.
Authors
Tao Gao, Elizabeth C. Wright-Jin, Rajarshi Sengupta, Jessica B. Anderson, Robert O. Heuckeroth
Abstract
Anastomotic leakage (AL) accounts for a major part of in-house mortality in patients undergoing colorectal surgery. Local ischemia and abdominal sepsis are common risk factors contributing to AL and are characterized by upregulation of the hypoxia-inducible factor (HIF) pathway. The HIF pathway is critically regulated by HIF-prolyl hydroxylases (PHDs). Here, we investigated the significance of PHDs and the effects of pharmacologic PHD inhibition (PHI) during anastomotic healing. Ischemic or septic colonic anastomoses were created in mice by ligation of mesenteric vessels or lipopolysaccharide-induced abdominal sepsis, respectively. Genetic PHD-deficiency (Phd1-/-, Phd2+/-, and Phd3-/-) or PHI were applied to manipulate PHD activity. Pharmacologic PHI and genetic PHD2-haplodeficiency (Phd2+/-) significantly improved healing of ischemic or septic colonic anastomoses, as indicated by increased bursting pressure and reduced AL rates. Only Phd2+/- (but not PHI or Phd1-/-) protected from sepsis-related mortality. Mechanistically, PHI and Phd2+/- induced immuno-modulatory (M2) polarization of macrophages, resulting in increased collagen content and attenuated inflammation-driven immune cell recruitment. We conclude that PHI improves healing of colonic anastomoses in ischemic or septic conditions by Phd2+/--mediated M2 polarization of macrophages, conferring a favourable microenvironment for anastomotic healing. Patients with critically perfused colorectal anastomosis or abdominal sepsis could benefit from pharmacologic PHI.
Authors
Moritz J. Strowitzki, Gwendolyn Kimmer, Julian S. Wehrmann, Alina S. Ritter, Praveen Radhakrishnan, Vanessa M. Opitz, Christopher Tuffs, Marvin Biller, Julia Kugler, Ulrich Keppler, Jonathan M. Harnoss, Johannes Klose, Thomas Schmidt, Alfonso Blanco, Cormac T. Taylor, Martin Schneider
Abstract
Background and aims: Pancreatic cancer is one of the deadliest cancers, still with low long term survival rates. Despite recent advances in treatment, it is extremely important to screen high-risk individuals in order to establish preventive and early detection measures and, in some cases, molecular driven therapeutic options. Familial pancreatic cancer (FPC) accounts for 4%-10% of pancreatic cancers. Several germline mutations are known to be related with an increased risk and might offer novel screening and therapy options. In this study, our goal was to discover the identity of a familial pancreatic cancer gene in two members of a family with FPC. Methods: Whole exome sequencing and PCR confirmation was performed on the surgical specimen and peripheral blood of an index patient and her sister in a family with high incidence of pancreatic cancer, to identify somatic and germline mutations associated with familial pancreatic cancer. Compartment-specific gene expression data and immunohistochemistry was used to characterize PALLD expression. Results: A germline mutation of the PALLD gene (NM_001166108.1:c.G154A:p.D52N) was detected in the index patient with pancreatic cancer. The identical PALLD mutation was identified in the tumor tissue of her sister. Whole genome sequencing showed similar somatic mutation patterns between the two sisters. Apart from the PALLD mutation, commonly mutated genes that characterize PDAC (KRAS and CDKN2A) were found in both tumor samples. However, the two patients harbored different somatic KRAS mutations (respectively G12D in the index patient and G12V in the index patient’s sister). Analysis for PALLD mutation in the healthy siblings of the two sisters was negative, indicating that the identified PALLD mutation might have a disease specific impact. Of note, compartment-specific gene expression data and IHC suggested a predominant role in cancer associated fibroblasts (CAFs). Conclusion: We identified a germline mutation of the palladin (PALLD) gene in two siblings in Europe, affected by familial pancreatic cancer, with a predominant function in the tumor stroma.
Authors
Lucia Liotta, Sebastian Lange, H. Carlo Maurer, Kenneth P. Olive, Rickmer Braren, Nicole Pfarr, Alexander Muckenhuber, Moritz Jesinghaus, Wilko Weichert, Katja Steiger, Sebastian Burger, Helmut Friess, Roland M. Schmid, Hana Alguel, Philipp Jost, Juliane Ramser, Christine Fischer, Anne S. Quante, Maximilian Reichert, Michael Quante
Abstract
Acute high fat diet (HFD) exposure induces a brief period of hyperphagia before caloric balance is restored. Previous studies have demonstrated this period of regulation is associated with activation of synaptic NMDA receptors (NMDARs) on dorsal motor nucleus of the vagus (DMV) neurons, which increases vagal control of gastric functions. Our aim was to test the hypothesis that activation of DMV NMDARs occurs subsequent to activation of extrasynaptic NMDA receptors (NMDARex). Sprague-Dawley rats were fed control or HFD for 3-5 days prior to experimentation. Whole cell patch clamp recordings from gastric-projecting DMV neurons, in vivo recordings of gastric motility, tone, compliance, and emptying, as well as food intake studies were used to assess the effects of NMDAR antagonism on caloric regulation. Following acute HFD exposure, inhibition of NMDARex prevented the NMDARs-mediated increase in glutamatergic transmission to DMV neurons, as well as the increase in gastric tone and motility, while chronic NMDARex inhibition attenuated the regulation of caloric intake. Following acute HFD exposure, the regulation of food intake involves NMDARs-mediated currents, which occur in response to NMDARex activation. Understanding these events may provide a mechanistic basis for hyperphagia and identify potential novel therapeutic targets for the treatment of obesity.
Authors
Courtney Clyburn, R. Alberto Travagli, Amy C. Arnold, Kirsteen N. Browning
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