Severe Acute Respiratory Syndrome Coronavirus 2 Is Detected in the Gastrointestinal Tract of Asymptomatic Endoscopy Patients but Is Unlikely to Pose a Significant Risk to Healthcare Personnel.

Background and Aims: Recent evidence suggests that the gut is an additional target for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, whether SARS-CoV-2 spreads via gastrointestinal secretions remains unclear. To determine the prevalence of gastrointestinal SARS-CoV-2 infection in asymptomatic subjects, we analyzed gastrointestinal biopsy and liquid samples from endoscopy patients for the presence of SARS-CoV-2. Methods: We enrolled 100 endoscopic patients without known SARS-CoV-2 infection (cohort A) and 12 patients with a previous COVID-19 diagnosis (cohort B) in a cohort study performed at a regional hospital. Gastrointestinal biopsies and fluids were screened for SARS-CoV-2 by polymerase chain reaction (PCR), immunohistochemistry, and virus isolation assay, and the stability of SARS-CoV-2 in gastrointestinal liquids in vitro was analyzed. Results: SARS-CoV-2 ribonucleic acid was detected by PCR in the colonic tissue of 1/100 patients in cohort A. In cohort B, 3 colonic liquid samples tested positive for SARS-CoV-2 by PCR and viral nucleocapsid protein was detected in the epithelium of the respective biopsy samples. However, no infectious virions were recovered from any samples. In vitro exposure of SARS-CoV-2 to colonic liquid led to a 4-log-fold reduction of infectious SARS-CoV-2 within 1 hour (P ≤ .05). Conclusion: Overall, the persistent detection of SARS-CoV-2 in endoscopy samples after resolution of COVID-19 points to the gut as a long-term reservoir for SARS-CoV-2. Since no infectious virions were recovered and SARS-CoV-2 was rapidly inactivated in the presence of colon liquids, it is unlikely that performing endoscopic procedures is associated with a significant infection risk due to undiagnosed asymptomatic or persistent gastrointestinal SARS-CoV-2 infections.

A Synthetic Hydrogel, VitroGel® ORGANOID-3, Improves Immune Cell-Epithelial Interactions in a Tissue Chip Co-Culture Model of Human Gastric Organoids and Dendritic Cells.

Immunosurveillance of the gastrointestinal epithelium by mononuclear phagocytes (MNPs) is essential for maintaining gut health. However, studying the complex interplay between the human gastrointestinal epithelium and MNPs such as dendritic cells (DCs) is difficult, since traditional cell culture systems lack complexity, and animal models may not adequately represent human tissues. Microphysiological systems, or tissue chips, are an attractive alternative for these investigations, because they model functional features of specific tissues or organs using microscale culture platforms that recreate physiological tissue microenvironments. However, successful integration of multiple of tissue types on a tissue chip platform to reproduce physiological cell-cell interactions remains a challenge. We previously developed a tissue chip system, the gut organoid flow chip (GOFlowChip), for long term culture of 3-D pluripotent stem cell-derived human intestinal organoids. Here, we optimized the GOFlowChip platform to build a complex microphysiological immune-cell-epithelial cell co-culture model in order to study DC-epithelial interactions in human stomach. We first tested different tubing materials and chip configurations to optimize DC loading onto the GOFlowChip and demonstrated that DC culture on the GOFlowChip for up to 20 h did not impact DC activation status or viability. However, Transwell chemotaxis assays and live confocal imaging revealed that Matrigel, the extracellular matrix (ECM) material commonly used for organoid culture, prevented DC migration towards the organoids and the establishment of direct MNP-epithelial contacts. Therefore, we next evaluated DC chemotaxis through alternative ECM materials including Matrigel-collagen mixtures and synthetic hydrogels. A polysaccharide-based synthetic hydrogel, VitroGel®-ORGANOID-3 (V-ORG-3), enabled significantly increased DC chemotaxis through the matrix, supported organoid survival and growth, and did not significantly alter DC activation or viability. On the GOFlowChip, DCs that were flowed into the chip migrated rapidly through the V-ORG matrix and reached organoids embedded deep within the chip, with increased interactions between DCs and gastric organoids. The successful integration of DCs and V-ORG-3 embedded gastric organoids into the GOFlowChip platform now permits real-time imaging of MNP-epithelial interactions and other investigations of the complex interplay between gastrointestinal MNPs and epithelial cells in their response to pathogens, candidate drugs and mucosal vaccines.

A High-Throughput Metabolic Microarray Assay Reveals Antibacterial Effects of Black and Red Raspberries and Blackberries against Helicobacter pylori Infection.

Helicobacter pylori infection is commonly treated with a combination of antibiotics and proton pump inhibitors. However, since H. pylori is becoming increasingly resistant to standard antibiotic regimens, novel treatment strategies are needed. Previous studies have demonstrated that black and red berries may have antibacterial properties. Therefore, we analyzed the antibacterial effects of black and red raspberries and blackberries on H. pylori. Freeze-dried powders and organic extracts from black and red raspberries and blackberries were prepared, and high-performance liquid chromatography was used to measure the concentrations of anthocyanins, which are considered the major active ingredients. To monitor antibiotic effects of the berry preparations on H. pylori, a high-throughput metabolic growth assay based on the Biolog system was developed and validated with the antibiotic metronidazole. Biocompatibility was analyzed using human gastric organoids. All berry preparations tested had significant bactericidal effects in vitro, with MIC90 values ranging from 0.49 to 4.17%. Antimicrobial activity was higher for extracts than powders and appeared to be independent of the anthocyanin concentration. Importantly, human gastric epithelial cell viability was not negatively impacted by black raspberry extract applied at the concentration required for complete bacterial growth inhibition. Our data suggest that black and red raspberry and blackberry extracts may have potential applications in the treatment and prevention of H. pylori infection but differ widely in their MICs. Moreover, we demonstrate that the Biolog metabolic assay is suitable for high-throughput antimicrobial susceptibility screening of H. pylori.

Endoscopic ultrasound does not accurately stage early adenocarcinoma or high-grade dysplasia of the esophagus.

BACKGROUND & AIMS: Patients with esophageal high-grade dysplasia or mucosal esophageal cancer can be successfully treated by endoscopy. We performed a systematic review of the literature to determine whether endoscopic ultrasound (EUS) correctly predicts the T-stage of early esophageal cancers, compared with pathology specimens obtained by using endoscopic mucosal resection (EMR) or surgery. METHODS: Standard systematic review methods were used to perform reference searches, determine eligibility, abstract data, and analyze data. When possible, individual patient-level data were abstracted, in addition to publication-level aggregate data. RESULTS: Twelve studies had sufficient information to abstract and review for quality; 8 had individual patient-level data (n = 132). Compared with surgical or EMR pathology staging, EUS had T-stage concordance of 65%, including all studies (n = 12), but only 56% concordance when limited to individual patient-level data. Factors such as initial biopsy pathology (high-grade dysplasia vs early-stage cancer) did not appear to affect the concordance of staging between EUS and EMR/surgical staging. CONCLUSIONS: EUS is not sufficiently accurate in determining the T-stage of high-grade dysplasias or superficial adenocarcinomas; other means of staging, such as EMR, should be used.

CT colonography predictably overestimates colonic length and distance to polyps compared with optical colonoscopy.

OBJECTIVE: The purpose of this study was to determine the discrepancy between CT colonography (CTC) and optical colonoscopy (OC) measurements for both anus-to-cecum length and anus-to-polyps distance and then determine whether a conversion factor could be generated to equate these CTC and OC distances. MATERIALS AND METHODS: We retrospectively reviewed CTC and OC reports from patients who had undergone both procedures as part of an established protocol. The anus-to-cecum measurement recorded on a single proprietary CTC workstation was compared with the OC cecal length for each patient. Likewise, anus-to-polyp distances were compared as measured by the radiologist and endoscopist. RESULTS: Three hundred thirty-eight patients and 437 polyps were identified with complete data from both CTC and same-day OC. The average anus-to-cecum distance measured at CTC was 189 cm (range, 75-257 cm) and at OC, 108 cm (range, 65-150 cm). For polyps proximal to the splenic flexure (n = 145), the CTC anus-to-polyp measurement was on average 1.7 times that measured at OC. For left-sided polyps (n = 292), the CTC measurement was, on average, within 12 cm or 1.3 times that of the OC anus-to-polyp measurement. All the differences between CTC and OC measurements of cecal length and polyp distances were found to be statistically significant using a paired Student's t test of means (p < 0.001). CONCLUSION: Anus-to-cecum and anus-to-polyp distances are disparate but comparable using a conversion factor of 0.57 for the CTC anus-to-cecum measurement and 0.59 for right-sided CTC anus-to-polyp or 0.78 for left-sided CTC anus-to-polyp measurements. These anus-to-polyp conversion factors could potentially augment current CTC guidelines for accurate and precise polyp localization and removal at endoscopy.

Gastroenterologists' interpretation of CTC: a pilot study demonstrating feasibility and similar accuracy compared with radiologists' interpretation.

OBJECTIVES: Computed tomography colonography (CTC) is an emerging colon cancer screening modality that has the potential to increase adherence to current screening recommendations. Traditionally, the interpretation of CTC has been limited to radiologists. As the technology of CTC has developed, three-dimensional endoluminal fly-through images have largely replaced two-dimensional CT images as the primary reading modality. Such a display is a realistic corollary to the endoscopic view obtained during colonoscopy. Our study sought to determine whether gastroenterologists could interpret the colonic display of CTC with an accuracy similar to that of trained radiologists. METHODS: Three board-certified gastroenterologists and four gastroenterology fellows in various stages of training interpreted a mean of 45 CTCs (range: 30-50) in which colonoscopy had also been performed. Before reading any cases, each reader underwent CTC interpretation training with an experienced CTC radiologist. After interpreting each CTC, the gastroenterologist had access to both the original radiology interpretation of the CTC and the corresponding colonoscopy results. Outcomes included accuracy of the gastroenterologists' interpretation, time required for CTC interpretation, evidence of learning, and the level of diagnostic agreement between gastroenterologists and radiologists. RESULTS: Gastroenterologist readers identified polyps >or=6 mm on CTC with a mean sensitivity and specificity of 83.5% (67-100%) and 78.8% (69-100%), respectively. Corresponding values for polyps >or=8 mm were 83.8% (68-100%) and 74% (30-93%), respectively, and those for polyps >or=10 mm were 87.8% (67-100%) and 85.2% (60-94%), respectively. Overall, 83% (5 of 6) of gastroenterologists achieved kappa scores >or=0.60, suggesting good agreement with radiologists; 66% achieved kappa>or=0.75. There was a direct relationship between diagnostic accuracy and level of gastroenterology training, with third-year fellows being nearly as accurate as the attendings. The average gastroenterologist CTC reading time was 18.4 min (range: 11.2-25.6). CONCLUSIONS: The gastroenterologists in this study were able to read CTCs with an accuracy that approaches that of radiologists. The level of training affected the accuracy of CTC interpretation by the gastroenterologist. Average gastroenterologist CTC interpretation times in this study were similar to recommended colonoscopy times. Further studies are warranted to determine whether gastroenterologists are able to interpret CTCs independently in clinical practice.