SARS-CoV-2 Receptor ACE2 Is an Interferon-Stimulated Gene in Human Airway Epithelial Cells and Is Detected in Specific Cell Subsets across Tissues.

There is pressing urgency to understand the pathogenesis of the severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2), which causes the disease COVID-19. SARS-CoV-2 spike (S) protein binds angiotensin-converting enzyme 2 (ACE2), and in concert with host proteases, principally transmembrane serine protease 2 (TMPRSS2), promotes cellular entry. The cell subsets targeted by SARS-CoV-2 in host tissues and the factors that regulate ACE2 expression remain unknown. Here, we leverage human, non-human primate, and mouse single-cell RNA-sequencing (scRNA-seq) datasets across health and disease to uncover putative targets of SARS-CoV-2 among tissue-resident cell subsets. We identify ACE2 and TMPRSS2 co-expressing cells within lung type II pneumocytes, ileal absorptive enterocytes, and nasal goblet secretory cells. Strikingly, we discovered that ACE2 is a human interferon-stimulated gene (ISG) in vitro using airway epithelial cells and extend our findings to in vivo viral infections. Our data suggest that SARS-CoV-2 could exploit species-specific interferon-driven upregulation of ACE2, a tissue-protective mediator during lung injury, to enhance infection.

Reverse-engineered exclusive enteral nutrition in pediatric Crohn's disease: A pilot trial.

BACKGROUND: In pediatric Crohn's disease (CD), commercial formulas used as exclusive enteral nutrition (EEN) are effective at inducing remission. This study aims to assess the impact of a whole-food blended smoothie as EEN on CD activity and the intestinal microbiome. METHODS: A 4-week prospective trial assessed the impact of EEN with a whole-food smoothie on newly diagnosed mild-to-moderate active pediatric CD. The smoothie with a multivitamin were developed to meet age-appropriate nutritional requirements. Assessment over 4 weeks included Pediatric Crohn's Disease Activity Index (PCDAI), serum laboratories, fecal calprotectin (FCP), and stool collection for metagenomic shotgun sequencing and microbiota composition analysis. Clinical remission was defined as PCDAI ≤ 10 at week 4. RESULTS: Ten participants were enrolled with median age 14.5 years, and 8 completed the trial. Baseline mean PCDAI was 26.3 ± 9.1 and mean FCP 1149 ± 718 µg/g. At week 4, 80% of participants achieved clinical remission. FCP decreased by over half in 60% of participants, with FCP below 250 µg/g in 60% and below 100 µg/g in 40%. Microbiome analysis showed a significant increase in species richness over 4 weeks (p = 0.01). Compared to baseline, the relative abundance at week 2 and at week 4 was significantly increased for Bifidobacterium and Streptococcus and decreased for Blautia (p < 0.05 for all). CONCLUSION: A whole-food blended smoothie was effective for inducing clinical remission and decreasing FCP in pediatric CD similar to commercial EEN formulas. Further research may give insight into data-driven whole-food dietary approaches for CD management. CLINICALTRIALS: gov NCT03508193.

Sirolimus for management of GI bleeding in blue rubber bleb nevus syndrome: A case series.

Blue rubber bleb nevus syndrome (BRBNS) commonly presents with anemia from bleeding gastrointestinal (GI) vascular malformations. Management is highly variable, as no consensus guidelines for medical treatment currently exist. Sirolimus has been used in BRBNS to decrease GI bleeding and seems well tolerated, though questions remain regarding dosing, duration of therapy, and adverse effects. Here, we report our single-center experience of four pediatric patients with BRBNS who were successfully treated with sirolimus and review the existing literature regarding sirolimus for treatment of GI bleeding in BRBNS. Further prospective studies are needed to establish optimal dosage, drug monitoring, and duration.

Imaging and endoscopic tools in pediatric inflammatory bowel disease: What's new?

Pediatric inflammatory bowel disease (IBD) is a chronic inflammatory disorder, with increasing incidence and prevalence worldwide. There have been recent advances in imaging and endoscopic technology for disease diagnosis, treatment, and monitoring. Intestinal ultrasound, including transabdominal, transperineal, and endoscopic, has been emerging for the assessment of transmural bowel inflammation and disease complications (e.g., fistula, abscess). Aside from surgery, IBD-related intestinal strictures now have endoscopic treatment options including through-the-scope balloon dilatation, injection, and needle knife stricturotomy and new evaluation tools such as endoscopic functional lumen imaging probe. Unsedated transnasal endoscopy may have a role in patients with upper gastrointestinal Crohn's disease or those with IBD with new upper gastrointestinal symptoms. Improvements to dysplasia screening in pediatric patients with longstanding colonic disease or primary sclerosing cholangitis hold promise with the addition of virtual chromoendoscopy and ongoing research in the field of artificial intelligence-assisted endoscopic detection. Artificial intelligence and machine learning is a rapidly evolving field, with goals of further personalizing IBD diagnosis and treatment selection as well as prognostication. This review summarized these advancements, focusing on pediatric patients with IBD.

Characterizing the human intestinal chondroitin sulfate glycosaminoglycan sulfation signature in inflammatory bowel disease.

The intestinal extracellular matrix (ECM) helps maintain appropriate tissue barrier function and regulate host-microbial interactions. Chondroitin sulfate- and dermatan sulfate-glycosaminoglycans (CS/DS-GAGs) are integral components of the intestinal ECM, and alterations in CS/DS-GAGs have been shown to significantly influence biological functions. Although pathologic ECM remodeling is implicated in inflammatory bowel disease (IBD), it is unknown whether changes in the intestinal CS/DS-GAG composition are also linked to IBD in humans. Our aim was to characterize changes in the intestinal ECM CS/DS-GAG composition in intestinal biopsy samples from patients with IBD using mass spectrometry. We characterized intestinal CS/DS-GAGs in 69 pediatric and young adult patients (n = 13 control, n = 32 active IBD, n = 24 IBD in remission) and 6 adult patients. Here, we report that patients with active IBD exhibit a significant decrease in the relative abundance of CS/DS isomers associated with matrix stability (CS-A and DS) compared to controls, while isomers implicated in matrix instability and inflammation (CS-C and CS-E) were significantly increased. This imbalance of intestinal CS/DS isomers was restored among patients in clinical remission. Moreover, the abundance of pro-stabilizing CS/DS isomers negatively correlated with clinical disease activity scores, whereas both pro-inflammatory CS-C and CS-E content positively correlated with disease activity scores. Thus, pediatric patients with active IBD exhibited increased pro-inflammatory and decreased pro-stabilizing CS/DS isomer composition, and future studies are needed to determine whether changes in the CS/DS-GAG composition play a pathogenic role in IBD.

Application of single-cell omics in inflammatory bowel disease.

Over the past decade, the advent of single cell RNA-sequencing has revolutionized the approach in cellular transcriptomics research. The current technology offers an unbiased platform to understand how genotype correlates to phenotype. Single-cell omics applications in gastrointestinal (GI) research namely inflammatory bowel disease (IBD) has become popular in the last few years with multiple publications as single-cell omics techniques can be applied directly to the target organ, the GI tract at the tissue level. Through examination of mucosal tissue and peripheral blood in IBD, the recent boom in single cell research has identified a myriad of key immune players from enterocytes to tissue resident memory T cells, and explored functional heterogeneity within cellular subsets previously unreported. As we begin to unravel the complex mucosal immune system in states of health and disease like IBD, the power of exploration through single-cell omics can change our approach to translational research. As novel techniques evolve through multiplexing single-cell omics and spatial transcriptomics come to the forefront, we can begin to fully comprehend the disease IBD and better design targets of treatment. In addition, hopefully these techniques can ultimately begin to identify biomarkers of therapeutic response and answer clinically relevant questions in how to tailor individual therapy to patients through personalized medicine.

Pharmacologic Management of Monogenic and Very Early Onset Inflammatory Bowel Diseases.

Inflammatory bowel disease (IBD) is treated with a variety of immunomodulating and immunosuppressive therapies; however, for the majority of cases, these therapies are not targeted for specific disease phenotypes. Monogenic IBD with causative genetic defect is the exception and represents a disease cohort where precision therapeutics can be applied. With the advent of rapid genetic sequencing platforms, these monogenic immunodeficiencies that cause inflammatory bowel disease are increasingly being identified. This subpopulation of IBD called very early onset inflammatory bowel disease (VEO-IBD) is defined by an age of onset of less than six years of age. Twenty percent of VEO-IBDs have an identifiable monogenic defect. The culprit genes are often involved in pro-inflammatory immune pathways, which represent potential avenues for targeted pharmacologic treatments. This review will provide an overview of the current state of disease-specific targeted therapies, as well as empiric treatment for undifferentiated causes of VEO-IBD.

Esophagogastric Fistula: The Consequence of High-Powered Magnets Ingestion.

A 17-month-old female had an unwitnessed ingestion of 26 high-powered magnets, resulting in the creation of an esophagogastric fistula via the left crus of the diaphragm. This case highlights a rare injury to the stomach and esophagus caused by high-powered magnets requiring surgical intervention. Furthermore, this case report illustrates the risks that high-powered magnets pose to young children. Additionally, this case highlights the importance of maintaining a high level of suspicion for ingestion in young patients along with a multidisciplinary team to manage sequelae of injury.

Association between iron deficit repletion with ferric carboxymaltose relative to iron sucrose in children with inflammatory bowel disease: A retrospective cohort study.

BACKGROUND: Iron deficiency and iron deficiency anemia are common in pediatric inflammatory bowel disease and often require supplementation with iron. There is a paucity of literature regarding optimal iron formulation. The aim of this study is to compare outcomes in pediatric patients with inflammatory bowel disease receiving either iron sucrose or ferric carboxymaltose during inpatient hospitalizations. METHODS: This was a single-center retrospective study of pediatric patients with inflammatory bowel disease admitted for newly diagnosed disease or flare who received either iron sucrose or ferric carboxymaltose. Linear regression was used to assess differences in iron repletion. Longitudinal linear mixed-effects models and generalized estimating equations compared hematologic and iron outcomes 6 months post-iron repletion. RESULTS: Thirty patients received ferric carboxymaltose. Sixty-nine patients received iron sucrose. Baseline hemoglobin and iron deficits were similar in both groups. A larger percentage of iron deficit was repleted in the ferric carboxymaltose group (81.4%) compared with iron sucrose (25.9%) (P < 0.001) with fewer infusions. Cumulative doses of ferric carboxymaltose administered (18.7 mg/kg) were higher than iron sucrose (6.1 mg/kg) (P < 0.001). Hemoglobin increased more quickly with ferric carboxymaltose compared with iron sucrose (P = 0.04 and P = 0.02, respectively). Total iron binding capacity and red cell distribution width levels decreased more over time with ferric carboxymaltose vs iron sucrose (P < 0.01 and P = 0.01, respectively). No adverse effects were seen. CONCLUSIONS: Hematologic and iron parameters responded more quickly with fewer infusions in patients who received ferric carboxymaltose vs iron sucrose. Patients who received ferric carboxymaltose achieved a higher percentage of iron deficit repleted.

Notch signaling drives intestinal graft-versus-host disease in mice and nonhuman primates.

Notch signaling promotes T cell pathogenicity and graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT) in mice, with a dominant role for the Delta-like Notch ligand DLL4. To assess whether Notch's effects are evolutionarily conserved and to identify the mechanisms of Notch signaling inhibition, we studied antibody-mediated DLL4 blockade in a nonhuman primate (NHP) model similar to human allo-HCT. Short-term DLL4 blockade improved posttransplant survival with durable protection from gastrointestinal GVHD in particular. Unlike prior immunosuppressive strategies tested in the NHP GVHD model, anti-DLL4 interfered with a T cell transcriptional program associated with intestinal infiltration. In cross-species investigations, Notch inhibition decreased surface abundance of the gut-homing integrin α4ß7 in conventional T cells while preserving α4ß7 in regulatory T cells, with findings suggesting increased ß1 competition for α4 binding in conventional T cells. Secondary lymphoid organ fibroblastic reticular cells emerged as the critical cellular source of Delta-like Notch ligands for Notch-mediated up-regulation of α4ß7 integrin in T cells after allo-HCT. Together, DLL4-Notch blockade decreased effector T cell infiltration into the gut, with increased regulatory to conventional T cell ratios early after allo-HCT. Our results identify a conserved, biologically unique, and targetable role of DLL4-Notch signaling in intestinal GVHD.

Linking Genetic Diagnosis to Therapeutic Approach in Very Early Onset Inflammatory Bowel Disease: Pharmacologic Considerations.

Very early onset inflammatory bowel disease (VEO-IBD) is diagnosed in children < 6 years of age, and in rare cases may be due to an identifiable monogenic cause. Recent advances in genetic testing have allowed for more accurate diagnosis, with as many as 100 genes now known to be associated with monogenic inflammatory bowel disease. These genes are involved in many immune pathways and thus may represent potential avenues for targeted precision medicine with pharmacologic treatments aimed at these. This review describes the broad classifications of monogenic disorders known to cause VEO-IBD, as well as empiric and disease-specific medical therapies. These include immune-modulating or immunosuppressant medications, nutritional therapy, surgery, and hematopoietic stem cell transplantation. We aim to provide an overview of the current state of targeted therapy for VEO-IBD.

Risk Factors for Development of Pneumatosis Intestinalis after Pediatric Hematopoietic Stem Cell Transplantation: A Single-Center Case-Control Study.

The significance of pneumatosis intestinalis (PI) in pediatric patients following hematopoietic stem cell transplantation (HSCT) is poorly understood. A knowledge gap remains with respect to the etiology, risk factors, and evidence-based treatment of these patients. As a result, management is frequently based on each center's clinical practice, without standardization across treatment centers. In this single-center trial, we aimed to validate both previously proposed and additional risk factors for the development of PI and to examine our management and outcomes for these patients. We performed a retrospective case-control study examining risk factors for the development of PI in pediatric HSCT patients at a single tertiary referral children's hospital. We used univariate and multivariable conditional logistic regression analysis to explore differences in pharmacologic and other transplantation-specific risk factors. Between 2012 and 2019, PI was diagnosed in 212 patients at our pediatric hospital, of whom 42 were HSCT recipients. The majority of patients (88%; n = 37 of 42) with PI were diagnosed by X-ray. Eighteen patients (43%) were asymptomatic and diagnosed incidentally after imaging was obtained for standard post-transplantation surveillance or other nonrelated indications. All patients with PI were hospitalized and placed on strict bowel rest while receiving parenteral nutrition and antibiotics. Recurrence of PI occurred in 4 patients (10%) following their initial diagnosis. Increased doses of steroid exposure within 30 days of PI diagnosis (odds ratio [OR], 5.7; 95% confidence interval [CI], 2.1 to 15.3; P = .0006), presence of grade II-IV gastrointestinal acute graft-versus-host disease (GVHD) (OR, 5.3; 95% CI, 1.0 to 28.1; P = .05), and receipt of >50% of total daily nutrition by nasogastric (NG) tube feeds (OR, 22.0; 95% CI, 1.3 to 370.2; P = .03) were identified as independent risk factors for the development of PI. Intensity of the conditioning regimen, exposure to total body irradiation, stem cell source, donor type, HLA matching, use of mycophenolate mofetil, and presence of bacterial or viral infection at the time of PI diagnosis were not demonstrably associated with the development of PI in our study. We conclude that development of asymptomatic PI is a benign condition following HSCT, and that the risk for PI is increased in patients with gastrointestinal GVHD, patients receiving steroid therapy, and patients relying on supplemental NG tube feeds for at least one-half of their total daily nutrition.

Adjunctive Dietary Therapy Is Associated With Improved Gastrointestinal Symptoms in Steroid-Refractory Gastrointestinal Graft-Versus-Host Disease: A Case Series.

Acute gastrointestinal graft-versus-host disease (GI GVHD) is a complication after hematopoietic stem cell transplant with high morbidity and mortality. In particular, steroid-refractory GI GVHD can be difficult to treat. Recent investigations have revealed that patients after transplant can experience intestinal dysbiosis contributing to the progression of GVHD. Modulation of the gut microbiome through dietary intake could potentially improve the intestinal dysbiosis in GI GVHD. In this case series, we present 3 patients where dietary therapy was used in conjunction with immunosuppression to achieve clinical remission of GI GVHD.

Effective Use of Topical Sucralfate in the Conservative Management of Expanded Gastrostomy Tract Reduction.

Sucralfate is a common medication used to treat duodenal ulcers, gastric ulcers, and gastritis. The off-label use of topical sucralfate has been described in the literature to induce wound healing in epithelial injury. Yet, current literature lacks clinical depictions in the application of sucralfate to treat a common gastrostomy tube complication, that of a dilated gastrostomy site. We present a case report of a medically complex pediatric patient where topical sucralfate was applied to reduce the size of a large gastrostomy stomal defect. Sucralfate was used to reduce healing time and allow introduction of a new gastrostomy device through the same stomal opening without the need for additional procedures or surgeries.

The Growing Need to Understand Very Early Onset Inflammatory Bowel Disease.

Very Early Onset Inflammatory Bowel Disease (VEO-IBD) represents a cohort of inflammatory bowel disease (IBD) patients diagnosed before 6 years of age. Unlike IBD diagnosed at older ages, VEO-IBD can be associated with underlying primary immunodeficiencies. VEO-IBD has been linked to monogenic variations in over 70 genes involved in multiple pathways of immunity. As sequencing technologies and platforms evolve and become readily available, an increasing number of genes linked to VEO-IBD have emerged. Although monogenic defects are rare in VEO-IBD, diagnosis of these variants can often dictate specific treatment. In this mini-review, we set out to describe monogenic variants previously characterized in multiple patients in the literature that contribute to VEO-IBD, diagnostic tools, unique treatment modalities for specific genetic diagnoses, and future directions in the field of VEO-IBD. Although this mini-review is by no means comprehensive of all the novel monogenic variants linked to VEO-IBD, we hope to provide relevant information that is readily accessible to clinicians and educators.

Spatiotemporal single-cell profiling reveals that invasive and tissue-resident memory donor CD8+ T cells drive gastrointestinal acute graft-versus-host disease.

Organ infiltration by donor T cells is critical to the development of acute graft-versus-host disease (aGVHD) in recipients after allogeneic hematopoietic stem cell transplant (allo-HCT). However, deconvoluting the transcriptional programs of newly recruited donor T cells from those of tissue-resident T cells in aGVHD target organs remains a challenge. Here, we combined the serial intravascular staining technique with single-cell RNA sequencing to dissect the tightly connected processes by which donor T cells initially infiltrate tissues and then establish a pathogenic tissue residency program in a rhesus macaque allo-HCT model that develops aGVHD. Our results enabled creation of a spatiotemporal map of the transcriptional programs controlling donor CD8+ T cell infiltration into the primary aGVHD target organ, the gastrointestinal (GI) tract. We identified the large and small intestines as the only two sites demonstrating allo-specific, rather than lymphodepletion-driven, T cell infiltration. GI-infiltrating donor CD8+ T cells demonstrated a highly activated, cytotoxic phenotype while simultaneously developing a canonical tissue-resident memory T cell (TRM) transcriptional signature driven by interleukin-15 (IL-15)/IL-21 signaling. We found expression of a cluster of genes directly associated with tissue invasiveness, including those encoding adhesion molecules (ITGB2), specific chemokines (CCL3 and CCL4L1) and chemokine receptors (CD74), as well as multiple cytoskeletal proteins. This tissue invasion transcriptional signature was validated by its ability to discriminate the CD8+ T cell transcriptome of patients with GI aGVHD from those of GVHD-free patients. These results provide insights into the mechanisms controlling tissue occupancy of target organs by pathogenic donor CD8+ TRM cells during aGVHD in primate transplant recipients.

Respiratory infections and chronic cough due to triple A (Allgrove) syndrome.

Cough and respiratory infections are common in pediatrics. Our case report illustrates the need for pediatricians to consider rare diagnoses such as genetic syndromes and primary gastrointestinal motility disorders in patients with unremitting respiratory and gastrointestinal symptoms. Early identification provides early intervention and reduces long-term morbidity for pediatric patients.

Relationship Between Esophageal Abnormalities on Fluoroscopic Esophagram and Pulmonary Function Testing in Juvenile Systemic Sclerosis.

OBJECTIVE: Juvenile systemic sclerosis (SSc) is a disabling autoimmune condition that affects multiple organs in addition to skin, notably the gastrointestinal and pulmonary systems. The relationship between esophageal abnormalities and pulmonary disease in juvenile SSc is not well understood. We describe associations between radiologic esophageal abnormalities and pulmonary function. METHODS: Clinical and radiographic data of children ages >18 years who fulfilled the 2007 Pediatric Rheumatology Provisional Classification Criteria for juvenile SSc between 1994 and 2016 were reviewed. Fluoroscopic upper gastrointestinal (UGI) studies, high-resolution computed tomography (HRCT), and pulmonary function tests (PFTs) within 12 months of presentation to Seattle Children's Hospital were extracted. RESULTS: Twenty-one children with juvenile SSc (67% female, ages 8-17 years) were studied. Esophageal abnormalities, defined as abnormal esophageal peristalsis and/or bolus clearance, were found in 12 patients. Abnormal esophagus on UGI tests was not associated with gastrointestinal or pulmonary symptoms, disease duration, use of medications (proton pump inhibitor or immunosuppressant), or specific autoantibodies. Compared with patients with a normal esophagus on UGI tests, children with an abnormal esophagus had decreased PFTs: mean forced expiratory volume in 1 second 96% versus 78% (P = 0.03), forced vital capacity 94% versus 76% (P = 0.02), and vital capacity 95% versus 76% (P = 0.02). Children with an abnormal esophagus on UGI tests had a larger mean esophageal diameter on HRCT (14.6 mm compared to 8.5 mm; P < 0.01). CONCLUSION: There was an association between esophageal and pulmonary disease in children with juvenile SSc. Esophageal findings on UGI tests or HRCT, despite lack of symptoms, should raise concern for esophageal dysfunction and prompt heightened surveillance for concurrent lung disease.

Chimeric Antigen Receptor T Cell-Mediated Neurotoxicity in Nonhuman Primates.

Chimeric antigen receptor (CAR) T-cell immunotherapy has revolutionized the treatment of refractory leukemias and lymphomas, but is associated with significant toxicities, namely cytokine release syndrome (CRS) and neurotoxicity. A major barrier to developing therapeutics to prevent CAR T cell-mediated neurotoxicity is the lack of clinically relevant models. Accordingly, we developed a rhesus macaque (RM) model of neurotoxicity via adoptive transfer of autologous CD20-specific CAR T cells. Following cyclophosphamide lymphodepletion, CD20 CAR T cells expand to 272 to 4,450 cells/µL after 7 to 8 days and elicit CRS and neurotoxicity. Toxicities are associated with elevated serum IL6, IL8, IL1RA, MIG, and I-TAC levels, and disproportionately high cerebrospinal fluid (CSF) IL6, IL2, GM-CSF, and VEGF levels. During neurotoxicity, both CD20 CAR and non-CAR T cells accumulate in the CSF and in the brain parenchyma. This RM model demonstrates that CAR T cell-mediated neurotoxicity is associated with proinflammatory CSF cytokines and a pan-T cell encephalitis.Significance: We provide the first immunologically relevant, nonhuman primate model of B cell-directed CAR T-cell therapy-mediated CRS and neurotoxicity. We demonstrate CAR and non-CAR T-cell infiltration in the CSF and in the brain during neurotoxicity resulting in pan-encephalitis, accompanied by increased levels of proinflammatory cytokines in the CSF. Cancer Discov; 8(6); 750-63. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 663.