Citations

The pathobiology of irritable bowel syndrome (IBS) is multifaceted. We aimed to identify candidate genes predisposing to quantitative traits in IBS. In 30 healthy volunteers, 30 IBS-constipation, and 64 IBS-diarrhea patients, we measured bowel symptoms, bile acid (BA) synthesis (serum 7α-hydroxy-4-cholesten-3-one and FGF19), fecal BA and fat, colonic transit (CT by scintigraphy), and intestinal permeability (IP by 2-sugar excretion). We assessed associations of candidate genes controlling BA metabolism ( KLB rs17618244 and FGFR4 rs351855), BA receptor ( GPBAR1 rs11554825), serotonin (5-HT) reuptake ( SLC6A4 through rs4795541 which encodes for the 44-bp insert in 5HTTLPR), or immune activation ( TNFSF15 rs4263839) with three primary quantitative traits of interest: colonic transit, BA synthesis, and fecal BA excretion. There were significant associations between fecal BA and CT at 48 h ( r = 0.43; P < 0.001) and IP ( r = 0.23; P = 0.015). GPBAR1 genotype was associated with CT48 ( P = 0.003) and total fecal BA [ P = 0.030, false detection rate (FDR) P = 0.033]. Faster CT48 observed with both CC and TT GPBAR1 genotypes was due to significant interaction with G allele of KLB, which increases BA synthesis and excretion. Other univariate associations ( P < 0.05, without FDR correction) observed between GPBAR1 and symptom phenotype and gas sensation ratings support the role of GPBAR1 receptor. Associations between SLC6A4 and stool consistency, ease of passage, postprandial colonic tone, and total fecal BA excretion provide data in support of future hypothesis-testing studies. Genetic control of GPBAR1 receptor predisposing to pathobiological mechanisms in IBS provides evidence from humans in support of the importance of GPBAR1 to colonic motor and secretory functions demonstrated in animal studies.

Abstract Background There have been significant advances in understanding the pathophysiological mechanisms in patients with neurogastroenterological disorders including irritable bowel syndrome (IBS) and functional abdominal pain, functional diarrhea, chronic constipation, gastroparesis, and functional dyspepsia. These advances have led to the development of novel pharmacological therapy of neurogastroenterological disorders. Purpose To review peer‐reviewed articles or prominent preliminary communications presented in the past year regarding medications in development for functional gastrointestinal disorders or gastroparesis. The medications fall into two main categories: first, established classes of medications within established classes, such as 5‐HT3 receptor antagonists and 5‐HT4 receptor agonists, and second, new classes of medications such as a combined μ‐opioid agonist and δ‐antagonist, or a small molecule ghrelin agonist.

Background Eosinophilic oesophagitis (EoE) is presumed to be an isolated oesophageal disease; yet other allergic diseases associated with eosinophilic infiltration of target tissues, such as asthma and eczema, show perturbed functions of other sites that may be involved in the diathesis of allergy modulation. Aim To analyse small intestinal permeability in patients with active EoE and in a separate group of patients in remission. Methods Small bowel permeability was determined using a dual sugar method by calculating lactulose:mannitol (L:M) ratio in 17 patients who met consensus criteria for active EoE (>15 eos/HPF) and 8 patients in remission (<5 eos/HPF). Data from 28 healthy controls was used for comparison. Results Patients with active EoE had significantly higher L:M ratios when compared to controls (0.045 vs. 0.033, p<0.001) and to EoE in remission (0.041 vs. 0.027, p<.001). There was no significant difference in L:M between the group with EoEin remission and healthy controls. The current data show that L:M ratio of 0.033 also provides a reasonable cut-off that defined the active EoE group compared to patients in remission. The main component explaining the change in L:M ratio was increased absorption (and excretion) of lactulose ((1601±106 ug) when compared to the EoE remission (969±91 ug) and control (1043±92 ug, p<.001) groups. Conclusions Small bowel permeability is overall increased in patients with active EoE, and is normal in patients with EoE in remission when compared to healthy controls. The role of the small bowel in active EoE deserves further investigation.

Human adipose‐derived mesenchymal stromal cells (AMSCs) grown in platelet lysate are promising agents for therapeutic tissue regeneration. Here, we investigated whether manipulation of epigenetic events by the clinically relevant histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) alters differentiation of AMSCs. The multipotency of AMSCs was validated by their ability to differentiate into osteogenic, chondrogenic, and adipogenic lineages. High‐throughput RNA sequencing and RT‐qPCR established that human histone deacetylases (HDAC1 to HDAC11, and SIRT1 to SIRT7) are differentially expressed in AMSCs. SAHA induces hyper‐acetylation of histone H3 and H4, stimulates protein expression of the HDAC‐responsive gene SLC9A3R1/NHERF1 and modulates the AKT/FOXO1 pathway. Biologically, SAHA interferes with osteogenic, chondrogenic and adipogenic lineage commitment of multipotent AMSCs. Mechanistically, SAHA‐induced loss of differentiation potential of uncommitted AMSCs correlates with multiple changes in the expression of principal transcription factors that control mesenchymal or pluripotent states. We propose that SAHA destabilizes the multi‐potent epigenetic state of uncommitted human AMSCs by hyper‐acetylation and perturbation of key transcription factor pathways. Furthermore, AMSCs grown in platelet lysate may provide a useful biological model for screening of new HDAC inhibitors that control the biological fate of human mesenchymal stromal cells. J. Cell. Physiol. 230: 52–62, 2015. © 2014 Wiley Periodicals, Inc.

AbstractImproving the effectiveness of adipose‐tissue derived human mesenchymal stromal/stem cells (AMSCs) for skeletal therapies requires a detailed characterization of mechanisms supporting cell proliferation and multi‐potency. We investigated the molecular phenotype of AMSCs that were either actively proliferating in platelet lysate or in a basal non‐proliferative state. Flow cytometry combined with high‐throughput RNA sequencing (RNASeq) and RT‐qPCR analyses validate that AMSCs express classic mesenchymal cell surface markers (e.g., CD44, CD73/NT5E, CD90/THY1, and CD105/ENG). Expression of CD90 is selectively elevated at confluence. Self‐renewing AMSCs express a standard cell cycle program that successively mediates DNA replication, chromatin packaging, cyto‐architectural enlargement, and mitotic division. Confluent AMSCs preferentially express genes involved in extracellular matrix (ECM) formation and cellular communication. For example, cell cycle‐related biomarkers (e.g., cyclins E2 and B2, transcription factor E2F1) and histone‐related genes (e.g., H4, HINFP, NPAT) are elevated in proliferating AMSCs, while ECM genes are strongly upregulated (>10‐fold) in quiescent AMSCs. AMSCs also express pluripotency genes (e.g., POU5F1, NANOG, KLF4) and early mesenchymal markers (e.g., NES, ACTA2) consistent with their multipotent phenotype. Strikingly, AMSCs modulate expression of WNT signaling components and switch production of WNT ligands (from WNT5A/WNT5B/WNT7B to WNT2/WNT2B), while upregulating WNT‐related genes (WISP2, SFRP2, and SFRP4). Furthermore, post‐proliferative AMSCs spontaneously express fibroblastic, osteogenic, chondrogenic, and adipogenic biomarkers when maintained in confluent cultures. Our findings validate the biological properties of self‐renewing and multi‐potent AMSCs by providing high‐resolution quality control data that support their clinical versatility. J. Cell. Biochem. 115: 1816–1828, 2014. © 2014 Wiley Periodicals, Inc.

Ewing sarcoma is an aggressive pediatric small round cell tumor that predominantly occurs in bone. Approximately 85% of Ewing sarcomas harbor the EWS/FLI fusion protein, which arises from a chromosomal translocation, t(11:22)(q24:q12). EWS/FLI interacts with numerous lineage‐essential transcription factors to maintain mesenchymal progenitors in an undifferentiated state. We previously showed that EWS/FLI binds the osteogenic transcription factor RUNX2 and prevents osteoblast differentiation. In this study, we investigated the role of another Runt‐domain protein, RUNX3, in Ewing sarcoma. RUNX3 participates in mesenchymal‐derived bone formation and is a context dependent tumor suppressor and oncogene. RUNX3 was detected in all Ewing sarcoma cells examined, whereas RUNX2 was detected in only 73% of specimens. Like RUNX2, RUNX3 binds to EWS/FLI via its Runt domain. EWS/FLI prevented RUNX3 from activating the transcription of a RUNX‐responsive reporter, p6OSE2. Stable suppression of RUNX3 expression in the Ewing sarcoma cell line A673 delayed colony growth in anchorage independent soft agar assays and reversed expression of EWS/FLI‐responsive genes. These results demonstrate an important role for RUNX3 in Ewing sarcoma. J. Cell. Physiol. 229: 2049–2056, 2014. © 2014 Wiley Periodicals, Inc.

Our aim was to conduct a pilot case-control study of RNA expression profile using RNA sequencing of rectosigmoid mucosa of nine females with -diarrhea-predominant irritable bowel syndrome (IBS-D) with accelerated colonic transit and nine female healthy controls. Mucosal total RNA was isolated and purified, and next-generation pair-end sequencing was performed using Illumina TruSeq. Analysis was carried out using a targeted approach toward 12 genes previously associated with IBS and a hypothesis-generating approach. Of the 12 targeted genes tested, patients with IBS-D had decreased mRNA expression of TNFSF15 (fold change controls to IBS-D: 1.53, P = 0.01). Overall, up- and downregulated mRNA expressions of 21 genes ( P = 10−5 to 10−8; P values with false detection rates are shown) were potentially relevant to IBS-D including the following: neurotransmitters [ P2RY4 ( P = 0.001), vasoactive intestinal peptide ( VIP, P = 0.02)]; cytokines [ CCL20 ( P = 0.019)]; immune function [ C4BPA complement cascade ( P = 0.0187)]; interferon-related [ IFIT3 ( P = 0.016)]; mucosal repair and cell adhesion [trefoil protein ( TFF1, P = 0.012)], retinol binding protein [ RBP2 ( P = 0.017)]; fibronectin ( FN1, P = 0.009); and ion channel functions [guanylate cyclase ( GUCA2B, P = 0.017), PDZ domain-containing protein 3 ( PDZD3, P = 0.029)]. Ten genes associated with functions related to pathobiology of IBS-D were validated by RT-PCR. There was significant correlation in fold changes of the selected genes ( Rs = 0.73, P = 0.013). Up- or downregulation of P2RY4, GUC2AB, RBP2, FNI, and C4BPA genes were confirmed on RT-PCR, which also revealed upregulation of farnesoid X receptor ( FXR) and apical sodium-coupled bile acid transporter ( IBAT/ASBT). RNA-Seq and RT-PCR analysis of rectosigmoid mucosa in IBS-D show transcriptome changes that provide the rationale for validation studies to explore the role of mucosal factors in the pathobiology of IBS-D.

Chronic idiopathic constipation is highly prevalent among adults. Bile acids (BAs) and the enterohepatic BA circulation modulate colonic secretion and motility that affect transit. BAs in the colon have a dual action as osmotic and stimulant agents. Newer agents, such as elobixibat (A3309), an inhibitor of the ileal BA transporter, have the potential to improve significantly the management of chronic constipation, with minimal adverse effects. Elobixibat modulates the enterohepatic BA circulation, enhancing the delivery of BAs to the colon where they induce secretory and motor effects. Secondary effects of the inhibition of BA absorption are reduced activation of the farnesoid X receptor, decreased secretion of fibroblast growth factor-19 into the portal circulation, and increased BA synthesis. This review focuses on the role of BAs, the enterohepatic BA circulation, and an ileal BA transporter inhibitor (elobixibat) in chronic constipation.

AbstractThe gastrointestinal tract is a vast neuroendocrine organ with extensive extrinsic and intrinsic neural circuits that interact to control its function. Circulating and paracrine hormones (amine and peptide) provide further control of secretory, absorptive, barrier, motor and sensory mechanisms that are essential to the digestion and assimilation of nutrients, and the transport and excretion of waste products. Specialized elements of the mucosa (including enteroendocrine cells, enterocytes and immune cells) and the microbiome interact with other intraluminal contents derived from the diet, and with endogenous chemicals that alter the gut's functions. The totality of these control mechanisms is often summarized as the brain–gut axis. In irritable bowel syndrome (IBS), which is the most common gastrointestinal disorder, there may be disturbances at one or more of these diverse control mechanisms. Patients present with abdominal pain in association with altered bowel function. This review documents advances in understanding the pathophysiological mechanisms in the brain–gut axis in patients with IBS. It is anticipated that identification of one or more disordered functions in clinical practice will usher in a renaissance in the management of IBS, leading to effective therapy tailored to the needs of the individual patient.