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AbstractBackgroundThe gut is the only organ system with intrinsic neural reflexes. Intrinsic primary afferent neurons (IPANs) of the enteric nervous system initiate intrinsic reflexes, form gut‐brain connections, and undergo considerable neuroplasticity to cause digestive diseases. They remain inaccessible to study in mice in the absence of a selective marker. Advillin is used as a marker for primary afferent neurons in dorsal root ganglia. The aim of this study was to test the hypothesis that advillin is expressed in IPANs of the mouse jejunum.MethodsAdvillin expression was assessed with immunohistochemistry and using transgenic mice expressing an inducible Cre recombinase under the advillin promoter were used to drive tdTomato and the genetically encoded calcium indicator GCaMP5. These mice were used to characterize the morphology and physiology of advillin‐expressing enteric neurons using confocal microscopy, calcium imaging, and whole‐cell patch‐clamp electrophysiology.Key ResultsAdvillin is expressed in about 25% of myenteric neurons of the mouse jejunum, and these neurons demonstrate the requisite properties of IPANs. Functionally, they demonstrate calcium responses following mechanical stimuli of the mucosa and during antidromic action potentials. They have Dogiel type II morphology with neural processes that mostly remain within the myenteric plexus, but also project to the mucosa and express NeuN and calcitonin gene‐related peptide (CGRP), but not nNOS.Conclusions and InferencesAdvillin marks jejunal IPANs providing accessibility to this important neuronal population to study and model digestive disease.

Abstract Introduction: The core-binding factor subunit RUNX1/CBFA2/AML1 (Runt-related transcription factor 1, Core-binding factor alpha 2 subunit, Oncogene AML1) is critical for generation of hematopoietic stem cells during embryogenesis and for normal megakaryopoiesis in adults. RUNX1/CBFA2/AML1 has long been recognized as an oncogene, and is frequently involved in leukemia-associated translocations that create aberrant fusion proteins (e.g., AML1-ETO). Recently, acquired somatic point mutations in the RUNX1/CBFA2/AML1 gene have been described in a subset of patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). These point mutations are associated with the loss of normal RUNX1 trans-activation potential and/or altered binding to the non-DNA-binding subunit of core-binding factor, CBFB. Given the importance of core-binding factor in megakaryocytic differentiation and platelet production and the central role of megakaryocytes in the pathophysiology of myelofibrosis with myeloid metaplasia (MMM), and in light of the myelofibrotic phenotype of GATA-1low mice (GATA-1 and RUNX1 are co-expressed and co-operate in megakaryocytic differentiation), we hypothesized that RUNX1 gene mutations might be common in MMM. In addition, we wanted to know whether patients with MDS-associated acquired alpha thalassemia (i.e., ATMDS), a special MDS subgroup with a very high incidence of point mutations in the X-linked ATRX gene, have an especially high incidence of RUNX1 mutations that might account for the more severe hematopoietic defect found in these patients compared with boys with inherited ATR-X syndrome (detailed in Steensma et al, Blood2004;103:2019). Methods and Results: We analyzed samples from 26 well-characterized patients with MMM and from 52 with MDS (11 RA, 3 RARS, 8 RCMD, 3 RAEB-1, 7 RAEB-2, 2 MDS in transition to AML-M6, 14 atypical/unclassifable MDS, 4 MDS subtype unknown - including 18 with ATMDS) for RUNX1 point mutations by denaturing high-performance liquid chromatography (DHPLC) followed by subcloning and sequencing of samples exhibiting heteroduplex peaks. We found 5 RUNX1 mutations in MDS patients (9.6%), all of whom had RAEB-2 (4 patients) or a history of treated AML (1 patient), but detected no mutations in MMM patients. All patients with RUNX1 mutations progressed to overt leukemia within 1 year. ATMDS patients did not have an increased risk of RUNX1 point mutations (2/18 patients with mutations, 11.1%) when compared with MDS without thalassemia (3/34 patients, 8.8%; p=0.58). Additionally, 1 MDS patient had a clonally restricted mutation in GATA-1 (c.1066 C>T) (also screened by DHPLC), but this is not predicted to change the GATA-1 amino acid sequence and is likely a random event reflecting the genomic instability characteristic of MDS. Conclusion: RUNX1 point mutations are common in high-risk MDS, but not in MMM, and that ATMDS patients do not have a risk of RUNX1 mutations in excess of that expected for MDS in general.

Background Temporal declines in cardiac stress tests results, coronary revascularization, and cardiovascular mortality have suggested a decline in the population burden of coronary disease until the 2000s. However, recent data indicate these favorable trends could be ending. We aimed to assess the evolution of the population burden of coronary disease in the community by examining trends in angiography and revascularization. Methods and Results We analyzed age‐ and sex‐adjusted trends from all coronary angiographic diagnostic procedures and revascularizations performed in Olmsted County, MN from 2000 to 2018. A total of 12 981 invasive angiograms were performed among 9049 individuals (64% men; 55% aged ≥65 years). Adjusted angiography rates decreased by 30% (95% CI , 25%–34%) between 2000 and 2009 and leveled off thereafter. Including computed tomography, angiography uncovered an increase in angiography use in recent years (risk ratio=1.15 [95% CI , 1.07–1.23] for 2018 versus 2014) and a decline in the prevalence of anatomic CAD from 2000 to 2018. CAD severity declined substantially from 2000 to 2009, followed by a plateau. Among 6570 revascularizations (72% men; 57% aged ≥65 years), 77% were percutaneous coronary interventions and 23% coronary artery bypass graft surgeries. The adjusted revascularization rates declined by 34% (95% CI , 27%–39%) from 2000 to 2009, followed by a plateau (risk ratio=1.10 [95% CI , 1.00–1.22]). Conclusions Between 2000 and 2018 in the community, coronary angiography use declined initially, leveled off, and then increased. Trends in CAD severity and revascularization use decreased then plateaued. The most recent trends are concerning as they suggest the burden of coronary disease is no longer declining. This warrants reinvigorated primary prevention and population surveillance.

Objective This study was designed to evaluate the roles of microRNAs (miRNAs) in slow transit constipation (STC). Design All human tissue samples were from the muscularis externa of the colon. Expression of 372 miRNAs was examined in a discovery cohort of four patients with STC versus three age/sex-matched controls by a quantitative PCR array. Upregulated miRNAs were examined by quantitative reverse transcription qPCR (RT-qPCR) in a validation cohort of seven patients with STC and age/sex-matched controls. The effect of a highly differentially expressed miRNA on a custom human smooth muscle cell line was examined in vitro by RT-qPCR, electrophysiology, traction force microscopy, and ex vivo by lentiviral transduction in rat muscularis externa organotypic cultures. Results The expression of 13 miRNAs was increased in STC samples. Of those miRNAs, four were predicted to target SCN5A , the gene that encodes the Na + channel Na V 1.5. The expression of SCN5A mRNA was decreased in STC samples. Let-7f significantly decreased Na + current density in vitro in human smooth muscle cells. In rat muscularis externa organotypic cultures, overexpression of let-7f resulted in reduced frequency and amplitude of contraction. Conclusions A small group of miRNAs is upregulated in STC, and many of these miRNAs target the SCN5A-encoded Na + channel Na V 1.5. Within this set, a novel Na V 1.5 regulator, let-7f, resulted in decreased Na V 1.5 expression, current density and reduced motility of GI smooth muscle. These results suggest Na V 1.5 and miRNAs as novel diagnostic and potential therapeutic targets in STC.

Abstract Acquired hemoglobin H (HbH) disease (α thalassemia) can arise in the setting of marrow neoplasia, especially the myelodysplastic syndrome (MDS). This association has been termed α thalassemia-MDS (ATMDS, MIM #300448). Recently, we have linked ATMDS to acquired point mutations in the ATRX gene, which encodes an X-linked chromatin-associated factor whose precise normal cellular function is unknown (Steensma et al, Blood2004;103:2019, and Gibbons et al, Nature Genetics2003;34:446). We now describe a novel acquired splicing mutation in the helicase domain of the ATRX gene in a 71 year-old man of southern Italian descent. The patient, who previously had normal blood indices, presented with a 6-month history of microcytic anemia (Hb 7.7 g/dL, MCV 73.7 fL, reticulocytes 0.2%; WBC 11,800/uL with 29% circulating blasts). Peripheral smear demonstrated marked anisopoikilocytosis and the presence of poorly hemoglobinized ghost cells, while a marrow aspirate and biopsy revealed dysplastic features including atypical megakaryocytes, and approximately 20% blasts, consistent with a diagnosis of MDS in leukemic transformation. On supravital staining, approximately 30% of circulating erythrocytes contained HbH inclusions. The α/β globin transcript ratio measured by quantitative real-time PCR ranged between 0.11 and 0.39, compared with the mean ratio for 11 normals (α/β ratios in normals ranged between 0.8–1.2 fold of the mean). Despite this evidence of α thalassemia, no gross rearrangements of the α globin cluster were detected on Southern blotting or by FISH, and sequencing of the α globin genes was unremarkable. Screening of the entire coding region of the ATRX gene by denaturing high-performance liquid chromatograpy showed no abnormalities. Amplification and sequencing of cDNA made from the patient’s blood, however, revealed loss of ATRX exon 28 (in the middle of the putative helicase domain), resulting in a frame shift and generation of a premature stop codon. The causative mutation at the genomic level remains unknown, despite sequencing of the consensus splice sites framing both ATRX exon 28 and the surrounding regions. A clonally restricted mutation in a distant cryptic splice enhancer or inhibitor is suspected. Following treatment with idarubicin and Ara-C, the patient achieved a complete remission with normalization of red cell morphology and indices, and HbH was no longer detectable. This case emphasizes the need to search carefully for abnormal mRNA splicing when screening for ATRX mutations and provides further support for a link between ATRX mutations and ATMDS. Among 20 ATMDS patients analyzed molecularly, we have now characterized ATRX missense, null, and nonsense mutations in 9 patients, found a codon substitution of uncertain significance in 1 patient, and detected ATRX splicing mutations in 3 patients, including the present case. Additionally, one patient had an acquired α globin deletion limited to the neoplastic clone (Steensma et al, Blood2004; 103:1518). The molecular defect remains unknown in 6 cases. Since RNA is not available from these 6 archival cases, it is possible that they have ATRX splicing mutations as well.

Macrophage-based immune dysregulation plays a critical role in development of delayed gastric emptying in diabetic mice. Loss of anti-inflammatory macrophages and increased expression of genes associated with pro-inflammatory macrophages has been reported in full-thickness gastric biopsies from gastroparesis patients. We aimed to determine broader protein expression (proteomics) and protein-based signaling pathways in gastric biopsies of diabetic (DG) and idiopathic gastroparesis (IG) patients. Additionally, we determined correlations between protein expressions, gastric emptying, and symptoms. Full-thickness gastric antrum biopsies were obtained from nine DG patients, seven IG patients, and five nondiabetic controls. Aptamer-based SomaLogic tissue scan that quantitatively identifies 1,305 human proteins was used. Protein fold changes were computed, and differential expressions were calculated using Limma. Ingenuity pathway analysis and correlations were carried out. Multiple-testing corrected P < 0.05 was considered statistically significant. Seventy-three proteins were differentially expressed in DG, 132 proteins were differentially expressed in IG, and 40 proteins were common to DG and IG. In both DG and IG, “Role of Macrophages, Fibroblasts and Endothelial Cells” was the most statistically significant altered pathway [DG false discovery rate (FDR) = 7.9 × 10−9; IG FDR = 6.3 × 10−12]. In DG, properdin expression correlated with GCSI bloating ( r = −0.99, FDR = 0.02) and expressions of prostaglandin G/H synthase 2, protein kinase C-ζ type, and complement C2 correlated with 4 h gastric retention ( r = −0.97, FDR = 0.03 for all). No correlations were found between proteins and symptoms or gastric emptying in IG. Protein expression changes suggest a central role of macrophage-driven immune dysregulation in gastroparesis, specifically, complement activation in diabetic gastroparesis. NEW & NOTEWORTHY This study uses SOMAscan, a novel proteomics assay for determination of altered proteins and associated molecular pathways in human gastroparesis. Seventy-three proteins were changed in diabetic gastroparesis, 132 in idiopathic gastroparesis compared with controls. Forty proteins were common in both. Macrophage-based immune dysregulation pathway was most significantly affected in both diabetic and idiopathic gastroparesis. Proteins involved in the complement and prostaglandin synthesis pathway were associated with symptoms and gastric emptying delay in diabetic gastroparesis.

Postsurgical gastric dysfunction is common, but the mechanisms are varied and poorly understood. The pylorus normally acts as an electrical barrier isolating gastric and intestinal slow waves. In this report, we present an aberrant electrical conduction pathway arising between the stomach and small intestine, following pyloric excision and surgical anastomosis, as a novel disease mechanism. A patient was referred with postsurgical gastroparesis following antrectomy, gastroduodenostomy, and vagotomy for peptic ulceration. Scintigraphy confirmed markedly abnormal 4-h gastric retention. Symptoms included nausea, vomiting, postprandial distress, and reflux. Intraoperative, high-resolution electrical mapping was performed across the anastomosis immediately before revision gastrectomy, and the resected anastomosis underwent immunohistochemistry for interstitial cells of Cajal. Mapping revealed continuous, stable abnormal retrograde slow-wave propagation through the anastomosis, with slow conduction occurring at the scar (4.0 ± 0.1 cycles/min; 2.5 ± 0.6 mm/s; 0.26 ± 0.15 mV). Stable abnormal retrograde propagation continued into the gastric corpus with tachygastria (3.9 ± 0.2 cycles/min; 1.6 ± 0.5 mm/s; 0.19 ± 0.12 mV). Histology confirmed ingrowth of atypical ICC through the scar, defining an aberrant pathway enabling transanastomotic electrical conduction. In conclusion, a “gastrointestinal aberrant pathway” is presented as a novel proposed cause of postsurgical gastric dysfunction. The importance of aberrant anastomotic conduction in acute and long-term surgical recovery warrants further investigation. NEW & NOTEWORTHY High-resolution gastric electrical mapping was performed during revisional surgery in a patient with severe gastric dysfunction following antrectomy and gastroduodenostomy. The results revealed continuous propagation of slow waves from the duodenum to the stomach, through the old anastomotic scar, and resulting in retrograde-propagating tachygastria. Histology showed atypical interstitial cells of Cajal growth through the anastomotic scar. Based on these results, we propose a “gastrointestinal aberrant pathway” as a mechanism for postsurgical gastric dysfunction.

Suppression of ZEB1 through miR-200 expression or HDAC inhibition with mocetinostat sensitizes resistant KRAS mutant lung cancers to MEK inhibition.