CTLA-4-expressing ILC3s restrain interleukin-23-mediated inflammation.

Interleukin (IL-)23 is a major mediator and therapeutic target in chronic inflammatory diseases that also elicits tissue protection in the intestine at homeostasis or following acute infection1-4. However, the mechanisms that shape these beneficial versus pathological outcomes remain poorly understood. To address this gap in knowledge, we performed single-cell RNA sequencing on all IL-23 receptor-expressing cells in the intestine and their acute response to IL-23, revealing a dominance of T cells and group 3 innate lymphoid cells (ILC3s). Unexpectedly, we identified potent upregulation of the immunoregulatory checkpoint molecule cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) on ILC3s. This pathway was activated by gut microbes and IL-23 in a FOXO1- and STAT3-dependent manner. Mice lacking CTLA-4 on ILC3s exhibited reduced regulatory T cells, elevated inflammatory T cells and more-severe intestinal inflammation. IL-23 induction of CTLA-4+ ILC3s was necessary and sufficient to reduce co-stimulatory molecules and increase PD-L1 bioavailability on intestinal myeloid cells. Finally, human ILC3s upregulated CTLA-4 in response to IL-23 or gut inflammation and correlated with immunoregulation in inflammatory bowel disease. These results reveal ILC3-intrinsic CTLA-4 as an essential checkpoint that restrains the pathological outcomes of IL-23, suggesting that disruption of these lymphocytes, which occurs in inflammatory bowel disease5-7, contributes to chronic inflammation.

ILC3s select microbiota-specific regulatory T cells to establish tolerance in the gut.

Microbial colonization of the mammalian intestine elicits inflammatory or tolerogenic T cell responses, but the mechanisms controlling these distinct outcomes remain poorly understood, and accumulating evidence indicates that aberrant immunity to intestinal microbiota is causally associated with infectious, inflammatory and malignant diseases1-8. Here we define a critical pathway controlling the fate of inflammatory versus tolerogenic T cells that respond to the microbiota and express the transcription factor RORγt. We profiled all RORγt+ immune cells at single-cell resolution from the intestine-draining lymph nodes of mice and reveal a dominant presence of T regulatory (Treg) cells and lymphoid tissue inducer-like group 3 innate lymphoid cells (ILC3s), which co-localize at interfollicular regions. These ILC3s are distinct from extrathymic AIRE-expressing cells, abundantly express major histocompatibility complex class II, and are necessary and sufficient to promote microbiota-specific RORγt+ Treg cells and prevent their expansion as inflammatory T helper 17 cells. This occurs through ILC3-mediated antigen presentation, αV integrin and competition for interleukin-2. Finally, single-cell analyses suggest that interactions between ILC3s and RORγt+ Treg cells are impaired in inflammatory bowel disease. Our results define a paradigm whereby ILC3s select for antigen-specific RORγt+ Treg cells, and against T helper 17 cells, to establish immune tolerance to the microbiota and intestinal health.

ZBTB46 defines and regulates ILC3s that protect the intestine.

RORγt is a lineage-specifying transcription factor that is expressed by immune cells that are enriched in the gastrointestinal tract and promote immunity, inflammation and tissue homeostasis1-15. However, fundamental questions remain with regard to the cellular heterogeneity among these cell types, the mechanisms that control protective versus inflammatory properties and their functional redundancy. Here we define all RORγt+ immune cells in the intestine at single-cell resolution and identify a subset of group 3 innate lymphoid cells (ILC3s) that expresses ZBTB46, a transcription factor specifying conventional dendritic cells16-20. ZBTB46 is robustly expressed by CCR6+ lymphoid-tissue-inducer-like ILC3s that are developmentally and phenotypically distinct from conventional dendritic cells, and its expression is imprinted by RORγt, fine-tuned by microbiota-derived signals and increased by pro-inflammatory cytokines. ZBTB46 restrains the inflammatory properties of ILC3s, including the OX40L-dependent expansion of T helper 17 cells and the exacerbated intestinal inflammation that occurs after enteric infection. Finally, ZBTB46+ ILC3s are a major source of IL-22, and selective depletion of this population renders mice susceptible to enteric infection and associated intestinal inflammation. These results show that ZBTB46 is a transcription factor that is shared between conventional dendritic cells and ILC3s, and identify a cell-intrinsic function for ZBTB46 in restraining the pro-inflammatory properties of ILC3s and a non-redundant role for ZBTB46+ ILC3s in orchestrating intestinal health.

A Quality Improvement Initiative Is Associated With Reduced Time to Administer Biologics and Small Molecules and Emergency Room Visits in Inflammatory Bowel Disease.

BACKGROUND: Delays in biologic or small molecule medication administration are associated with increased adverse events, hospitalization, and surgery in inflammatory bowel disease (IBD). We evaluated the impact of a quality improvement (QI) intervention on the time to administration of biologics or small molecules (TABS) in IBD. METHODS: Data were retrospectively extracted for IBD patients prescribed biologics or small molecules from a convenience sample of providers participating in an accredited QI educational intervention (baseline cohort). Subsequent to the intervention, data were prospectively collected from patients prescribed these medications (postintervention cohort). Dates related to steps between a treatment decision to medication administration were collected. The primary outcome compared TABS in baseline and postintervention cohorts. RESULTS: Eighteen physicians provided survey and patient data for 200 patients in each cohort (n=400). The median time to medication administration (TABS) decreased from baseline to postintervention cohorts (30 vs. 26 d, P=0.04). Emergency room visits before medication administration also decreased (25.5% vs. 12.5%, P=0.001). Similar numerical TABS reductions were observed in subgroups limited to physicians providing patients to both cohorts and for individual medications prescribed. Primary contributors to delays included filling prescriptions subsequent to insurance approval and dispensation subsequent to this. CONCLUSIONS: A QI intervention successfully reduced medication administration times (TABS) by accelerating provider-dependent steps. This intervention was associated with reduced emergency room visits. We propose TABS as a quality metric to assess the effective delivery of therapies in IBD. Further evaluation of QI interventions, patient education on prescription drug insurance, and quality metrics are warranted.

Noninvasive Targeted Crohn Disease Management by Combining Endoscopic Healing Index and Therapeutic Drug Monitoring.

Background and Aims: Therapeutic drug monitoring (TDM) with measurement of serum drug and antidrug antibody concentrations is used to optimize tumor necrosis factor antagonists (anti-TNF). The endoscopic healing index (EHI) is a validated serum-based assay to measure mucosal inflammation in adults with Crohn disease (CD). Our objectives were to evaluate the relationship between EHI and TDM results and to determine the anti-TNF concentration range associated with EHI <20 (consistent with endoscopic remission). Methods: Adult and pediatric patients with CD (N = 1731) were selected retrospectively from a clinical laboratory cohort. Patients were selected if they had an ICD-10 code for CD and if results for EHI and TDM were available within 30 days of each other. The relationship between EHI and TDM results was examined and the anti-TNF concentration range associated with EHI <20 vs >50 was evaluated. Results: Median anti-TNF concentration was higher in patients with EHI <20 vs >50 for infliximab (N = 796): 11.1 vs 3.4 µg/mL and for adalimumab (N = 935): 9.2 vs 5.0 µg/mL (P < 0.0001 both drugs). Patients with antibodies to infliximab (12.8%) or adalimumab (14.9%) had lower anti-TNF concentrations (P < 0.001 both drugs) and higher EHI (P < 0.01 both drugs). The concentration range for infliximab: 5-15 µg/mL (5-9 µg/mL in pediatric patients) and for adalimumab: 5-10 µg/mL (8 µg/mL in pediatric patients) best discriminated EHI <20 vs >50. Conclusions: We report the anti-TNF concentration range associated with EHI <20. Combined testing of EHI and TDM is proposed as a noninvasive approach for treat-to-target management which could improve the ability to monitor disease and optimize anti-TNF therapy.

Dendritic cell-derived hepcidin sequesters iron from the microbiota to promote mucosal healing.

Bleeding and altered iron distribution occur in multiple gastrointestinal diseases, but the importance and regulation of these changes remain unclear. We found that hepcidin, the master regulator of systemic iron homeostasis, is required for tissue repair in the mouse intestine after experimental damage. This effect was independent of hepatocyte-derived hepcidin or systemic iron levels. Rather, we identified conventional dendritic cells (cDCs) as a source of hepcidin that is induced by microbial stimulation in mice, prominent in the inflamed intestine of humans, and essential for tissue repair. cDC-derived hepcidin acted on ferroportin-expressing phagocytes to promote local iron sequestration, which regulated the microbiota and consequently facilitated intestinal repair. Collectively, these results identify a pathway whereby cDC-derived hepcidin promotes mucosal healing in the intestine through means of nutritional immunity.

Pulmonary Manifestations in Adolescents With Inflammatory Bowel Disease.

Objectives. The available literature on pulmonary disease in pediatric inflammatory bowel disease is limited. We evaluated the prevalence of pulmonary manifestations in pediatric inflammatory bowel disease and their association with disease severity. Methods. Patients completed the St. George's Respiratory Questionnaire (SGRQ), a self-reported measure of quality of life in patients with pulmonary disease. Chart review provided demographic information and Pediatric Crohn's Disease Activity Index (PCDAI) and Pediatric Ulcerative Colitis Activity Index scores. Regression models were utilized to evaluate associations between SGRQ score and clinical risk factors. Results. The prevalence of pulmonary manifestations was 9.62% (95% confidence interval = 5.48% to -15.36%). PCDAI scores in Crohn's disease patients with pulmonary symptoms were significantly higher (SGRQ mean = 10.71 ± 10.94) than in patients without such symptoms. SGRQ score was also higher in patients with indeterminate colitis (8.64, 95% confidence interval = 0.72-16.57, P = .03), when compared with Crohn's disease. Conclusions. Additional investigations including pulmonary function tests and imaging could provide further insight into this issue.

Innate lymphoid cells support regulatory T cells in the intestine through interleukin-2.

Interleukin (IL)-2 is a pleiotropic cytokine that is necessary to prevent chronic inflammation in the gastrointestinal tract1-4. The protective effects of IL-2 involve the generation, maintenance and function of regulatory T (Treg) cells4-8, and the use of low doses of IL-2 has emerged as a potential therapeutic strategy for patients with inflammatory bowel disease9. However, the cellular and molecular pathways that control the production of IL-2 in the context of intestinal health are undefined. Here we show, in a mouse model, that IL-2 is acutely required to maintain Treg cells and immunological homeostasis throughout the gastrointestinal tract. Notably, lineage-specific deletion of IL-2 in T cells did not reduce Treg cells in the small intestine. Unbiased analyses revealed that, in the small intestine, group-3 innate lymphoid cells (ILC3s) are the dominant cellular source of IL-2, which is induced selectively by IL-1ß. Macrophages in the small intestine produce IL-1ß, and activation of this pathway involves MYD88- and NOD2-dependent sensing of the microbiota. Our loss-of-function studies show that ILC3-derived IL-2 is essential for maintaining Treg cells, immunological homeostasis and oral tolerance to dietary antigens in the small intestine. Furthermore, production of IL-2 by ILC3s was significantly reduced in the small intestine of patients with Crohn's disease, and this correlated with lower frequencies of Treg cells. Our results reveal a previously unappreciated pathway in which a microbiota- and IL-1ß-dependent axis promotes the production of IL-2 by ILC3s to orchestrate immune regulation in the intestine.

Assuring Quality for Non-hospital-based Biologic Infusions in Pediatric Inflammatory Bowel Disease: A Clinical Report From the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition.

The primary aim of this Clinical Report by the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition is to provide formal guidance to pediatric gastroenterologists and clinicians, health systems, and insurance payers regarding home- and office-based infusions for biologic therapies in pediatric inflammatory bowel disease. Patients in North America are increasingly denied coverage by payers based on "place of service" codes at hospital-based infusion units where the treating clinicians primarily provide care. A task force with topic expertise generated 8 best practice recommendations to ensure quality of care for pediatric patients with inflammatory bowel disease receiving non-hospital-based biologic infusions. Pragmatic considerations discussed in this report include patient safety, pediatric-trained nurse availability, care coordination, patient-centeredness, shared liability, administrative support, clinical governance, and costs of care.

Pediatric Gastroenterologists' Approach to Venous Thromboembolism Prophylaxis in Pediatric Inflammatory Bowel Disease.

The risk of venous thromboembolism (VTE) is significantly increased in patients with inflammatory bowel disease (IBD). For the adult population, prophylaxis guidelines exist to help guide physicians in their management of high-risk IBD patients. Although it is known that children with IBD also experience increased rates of VTE, there is no clear consensus on how best to prevent these unwanted complications. We sought to better understand practicing pediatric gastroenterologists' awareness of this issue and practices surrounding prevention of VTE in their pediatric patients. We found that pediatric gastroenterologists are well aware of the increased risk for VTE in children with IBD, that anticoagulant prophylaxis is infrequently used for pediatric patients, and that the most commonly cited reason for not providing prophylaxis is the lack of available guidelines in the literature.

Health Care Maintenance for the Pediatric Patient With Inflammatory Bowel Disease.

Nearly one-quarter of patients with inflammatory bowel disease (IBD) are younger than 20 years of age at diagnosis. Furthermore, the incidence of IBD in children continues to increase. Nevertheless, variation in management exists within the care of patients with IBD with regards to disease screening and preventive care. A multidisciplinary approach that involves the general practitioner and pediatric gastroenterologist is needed to routinely monitor growth, bone health, vitamin and mineral deficiencies, vaccination status, and endoscopic surveillance. It is also important to monitor for extraintestinal manifestations of IBD that may affect the liver, joints, skin, and eyes. The purpose of this article is to provide an updated overview of comprehensive care for pediatric patients with IBD.

Cerebral venous thrombosis in inflammatory bowel disease.

Cerebral venous thrombosis (CVT) is a rare but devastating complication of inflammatory bowel disease (IBD). Here we describe six IBD patients with cerebral venous thrombosis. The patients presented with hours to days of headache and were found to have venous thrombosis on imaging. Four of the six patients had ulcerative colitis and two had Crohn's disease. All six patients were treated with therapeutic anticoagulation. There were two deaths; one patient became comatose and died despite anticoagulation while the other recovered well from the sinus thrombosis but died after a bowel perforation 3 weeks later. This case series demonstrates the critical need for early recognition of neurological symptoms in patients with IBD during disease flares. It is important to recognize the clinical signs in order to start anticoagulation expeditiously and improve neurological outcomes.

Development and validation of a celiac disease quality of life instrument for North American children.

OBJECTIVE: Given the social constraints imposed by a gluten-free diet, it can be hypothesized that children with celiac disease (CD) living in the United States have a reduced health-related quality of life (HRQOL); however, there is no validated CD-specific HRQOL instrument for children living in the United States. The goals of this study were to develop and validate a CD-specific HRQOL instrument for children 8 to 18 years of age with CD and to report HRQOL in these children using both generic- and disease-specific instruments. METHODS: This was a prospective study using focus group methodology to develop a CD-specific HRQOL instrument that was then administered to children 8 to 18 years of age with CD living throughout the United States. Instrument validation methods included construct, convergent, and divergent validities. RESULTS: Two instruments were developed: CD-specific pediatric HRQOL instrument (CDPQOL) 8 to 12 and CDPQOL 13 to 18. A total of 181 children with CD completed the CDPQOL as well as a comparator generic instrument. Exploratory factor analysis restructured the CDPQOL and reduced the total number of items. The CDPQOL showed a moderate agreement with the Psychosocial dimensions of the generic instrument confirming convergent validity and low-to-moderate agreement with the Physical Health Summary dimension of the generic instrument confirming divergent validity. CONCLUSIONS: The CDPQOL, consisting of 13 to 17 questions, is a validated instrument for the measurement of HRQOL in children 8 to 18 years of age with CD living in the United States.

Magnetic resonance enterography and wireless capsule endoscopy in the evaluation of patients with inflammatory bowel disease.

BACKGROUND: Magnetic resonance enterography (MRE) is increasingly used in children due to growing concerns of radiation. OBJECTIVE: To determine the performance of MRE, imaging findings were compared to wireless capsule endoscopy (WCE) and histology results in children with/or suspected inflammatory bowel disease (IBD). MATERIALS AND METHODS: Pathology and WCE reports were retrospectively reviewed in 23 patients who had MRE. RESULTS: The sensitivity of MRE was 75.0% while the sensitivity of WCE was 77.8%. CONCLUSION: MRE and WCE are complementary techniques in evaluation of the small bowel in IBD.