The keratin-desmosome scaffold of internal epithelia in health and disease - The plot is thickening.

Keratin (K) intermediate filaments are attached to desmosomes and constitute the orchestrators of epithelial cell and tissue architecture. While their relevance in the epidermis is well recognized, our review focuses on their emerging importance in internal epithelia. The significance of keratin-desmosome scaffolds (KDSs) in the intestine is highlighted by transgenic mouse models and individuals with inflammatory bowel disease who display profound KDS alterations. In lung, high K8 expression defines a transitional cell subset during regeneration, and K8 variants are associated with idiopathic pulmonary fibrosis. Inherited variants in desmosomal proteins are overrepresented in idiopathic lung fibrosis, and familiar eosinophilic esophagitis. K18 serum fragments are established hepatocellular injury markers that correlate with the extent of histological inflammation. K17 expression is modified in multiple tumors, and K17 levels might be of prognostic relevance. These data should spur further studies on biological roles of these versatile tissue protectors and efforts on their therapeutic targeting.

Pediatric IBD Patients Treated With Infliximab and Proactive Drug Monitoring Benefit From Early Concomitant Immunomodulatory Therapy: A Retrospective Analysis of a 10-Year Real-Life Cohort.

BACKGROUND: Limited approval of second-line treatments in pediatric inflammatory bowel disease (pIBD) necessitates optimized use of infliximab (IFX) with proactive therapeutic drug monitoring (TDM). We investigated whether early combo-therapy with an immunomodulator (IMM) provides additional benefit. METHODS: In the retrospectively reviewed medical records of all children treated with IFX and proactive TDM between 2013 and 2022, IMMearly (IMM ≤3 months since IFX start) was evaluated against IMMother/no (late/short or no IMM) over follow-up of 3 to 60 months. Kaplan-Meier analysis was used to analyze time to loss of response (LOR) with IFX discontinuation or time to antibodies-to-IFX (ATI) development. RESULTS: Three hundred fifteen patients with pIBD were reviewed; of those, 127 with 2855 visits were included (77 CD, 50 UC/IBD-unclassified). Sixty patients received IMMearly, 20 patients IMMother, and 47 had IFX monotherapy. Median follow-up time was 30 and 26 months for IMMearly and IMMother/no, respectively, with comparable proactive TDM. Infliximab treatment persistence was 68% after 60 months. Loss of response was observed in 7 IMMearly and 15 IMMother/no patients (P = .16). Early combo-therapy significantly delayed LOR with IFX discontinuation (median LOR free interval IMMearly 30 months vs IMMother/no 9 months, P = .01). Patients with IMMother/no were 10-, 3- and 2-times more likely to experience LOR with IFX discontinuation after 1, 3, and 5 years, respectively. There were no significant group differences regarding the presence of any positive (>10 arbitrary units per milliliter [AU/mL]) or high (>100 AU/mL) ATI, median ATI concentrations, and ATI-free interval. CONCLUSIONS: Early IMM combo-therapy in proactively monitored patients with pIBD significantly prolonged the median LOR free interval compared with late/short or no IMM treatment.

A prospective longitudinal cohort study on risk factors for COVID-19 vaccination failure (RisCoin): methods, procedures and characterization of the cohort.

The primary objective of the RisCoin study was to investigate the interplay of genetic, metabolic, and lifestyle factors as well as stress levels on influencing the humoral immune response after at least two COVID-19 vaccinations, primarily with mRNAs, and the risk of SARS-CoV-2 breakthrough infections during follow-up. Here, we describe the study design, procedures, and study population. RisCoin is a prospective, monocentric, longitudinal, observational cohort study. Between October and December 2021, 4515 participants with at least two COVID-19 vaccinations, primarily BNT162b2 and mRNA-1273, were enrolled at the LMU University Hospital of Munich, thereof > 4000 healthcare workers (HCW), 180 patients with inflammatory bowel disease under immunosuppression, and 119 patients with mental disorders. At enrollment, blood and saliva samples were collected to measure anti-SARS-CoV-2 antibodies, their neutralizing capacity against Omicron-BA.1, stress markers, metabolomics, and genetics. To ensure the confidential handling of sensitive data of study participants, we developed a data protection concept and a mobile application for two-way communication. The application allowed continuous data reporting, including breakthrough infections by the participants, despite irreversible anonymization. Up to 1500 participants attended follow-up visits every two to six months after enrollment. The study gathered comprehensive data and bio-samples of a large representative HCW cohort and two patient groups allowing analyses of complex interactions. Our data protection concept combined with the mobile application proves the feasibility of longitudinal assessment of anonymized participants. Our concept may serve as a blueprint for other studies handling sensitive data on HCW.

Is Autologous Fecal Microbiota Transfer after Exclusive Enteral Nutrition in Pediatric Crohn's Disease Patients Rational and Feasible? Data from a Feasibility Test.

BACKGROUND: Exclusive enteral nutrition (EEN) is a highly effective therapy for remission induction in pediatric Crohn's disease (CD), but relapse rates after return to a regular diet are high. Autologous fecal microbiota transfer (FMT) using stool collected during EEN-induced clinical remission might represent a novel approach to maintaining the benefits of EEN. METHODS: Pediatric CD patients provided fecal material at home, which was shipped at 4 °C to an FMT laboratory for FMT capsule generation and extensive pathogen safety screening. The microbial community composition of samples taken before and after shipment and after encapsulation was characterized using 16S rRNA amplicon sequencing. RESULTS: Seven pediatric patients provided fecal material for nine test runs after at least three weeks of nutritional therapy. FMT capsules were successfully generated in 6/8 deliveries, but stool weight and consistency varied widely. Transport and processing of fecal material into FMT capsules did not fundamentally change microbial composition, but microbial richness was <30 genera in 3/9 samples. Stool safety screening was positive for potential pathogens or drug resistance genes in 8/9 test runs. CONCLUSIONS: A high pathogen burden, low-diversity microbiota, and practical deficiencies of EEN-conditioned fecal material might render autologous capsule-FMT an unsuitable approach as maintenance therapy for pediatric CD patients.

Diet prevents the expansion of segmented filamentous bacteria and ileo-colonic inflammation in a model of Crohn's disease.

BACKGROUND: Crohn's disease (CD) is associated with changes in the microbiota, and murine models of CD-like ileo-colonic inflammation depend on the presence of microbial triggers. Increased abundance of unknown Clostridiales and the microscopic detection of filamentous structures close to the epithelium of Tnf ΔARE mice, a mouse model of CD-like ileitis pointed towards segmented filamentous bacteria (SFB), a commensal mucosal adherent bacterium involved in ileal inflammation. RESULTS: We show that the abundance of SFB strongly correlates with the severity of CD-like ileal inflammation in two mouse models of ileal inflammation, including Tnf ΔARE and SAMP/Yit mice. SFB mono-colonization of germ-free Tnf ΔARE mice confirmed the causal link and resulted in severe ileo-colonic inflammation, characterized by elevated tissue levels of Tnf and Il-17A, neutrophil infiltration and loss of Paneth and goblet cell function. Co-colonization of SFB in human-microbiota associated Tnf ΔARE mice confirmed that SFB presence is indispensable for disease development. Screening of 468 ileal and colonic mucosal biopsies from adult and pediatric IBD patients, using previously published and newly designed human SFB-specific primer sets, showed no presence of SFB in human tissue samples, suggesting a species-specific functionality of the pathobiont. Simulating the human relevant therapeutic effect of exclusive enteral nutrition (EEN), EEN-like purified diet antagonized SFB colonization and prevented disease development in Tnf ΔARE mice, providing functional evidence for the protective mechanism of diet in modulating microbiota-dependent inflammation in IBD. CONCLUSIONS: We identified a novel pathogenic role of SFB in driving severe CD-like ileo-colonic inflammation characterized by loss of Paneth and goblet cell functions in Tnf ΔARE mice. A purified diet antagonized SFB colonization and prevented disease development in Tnf ΔARE mice in contrast to a fiber-containing chow diet, clearly demonstrating the important role of diet in modulating a novel IBD-relevant pathobiont and supporting a direct link between diet and microbial communities in mediating protective functions. Video Abstract.

Children with Localized Crohn's Disease Benefit from Early Ileocecal Resection and Perioperative Anti-Tumor Necrosis Factor Therapy.

INTRODUCTION: In pediatric Crohn's disease ileocecal resection is performed reluctantly as postoperative recurrence is frequent. Anti-tumor necrosis factor (TNF) therapy reduces postoperative recurrence rates but increases the risk for infections. MATERIALS AND METHODS: We retrospectively reviewed pediatric Crohn's disease patients who underwent ileocecal resection in our center. We compared disease activity and z-scores for height, weight, and body mass index of patients, who continuously received perioperative anti-TNF therapy (TNF + ), with those who did not (TNF-). RESULTS: Of 29 patients (48% females), 13 and 16 were grouped to TNF+ and TNF-, respectively. Patients' characteristics did not differ between groups, except a longer follow-up time in TNF-. We saw significant postoperative improvement but no normalization in z-scores for weight (1.78 vs. 0.77, p < 0.001), body mass index (1.08 vs. 0.22, p < 0.001), and height (0.88 vs. 0.66, p < 0.001). Disease activity improved significantly more in patients receiving anti-TNF therapy (moderate improvement in 83% vs. 31%, p = 0.02). Endoscopic recurrence was more frequent in patients without anti-TNF therapy (80% vs. 20%; p = 0.023), but endoscopic follow-up was incomplete. There was no increase of infections under perioperative anti-TNF therapy (1 patient each; p = 1.000). CONCLUSION: In patients with localized Crohn's disease an ileocecal resection leads to short-term postoperative improvement of disease activity, body mass index, weight, and growth. For relevant catch-up growth an earlier intervention is necessary. Continuous perioperative anti-TNF therapy had no increased risk of perioperative infections.

Metabolic changes during exclusive enteral nutrition in pediatric Crohn's disease patients.

BACKGROUND AND AIMS: Exclusive enteral nutrition is recommended as a first-line treatment in active pediatric Crohn's Disease, but its mechanism of action is still not clear. We aimed to assess alterations in the metabolic profile of newly diagnosed pediatric Crohn's Disease patients before and during exclusive enteral nutrition therapy. METHODS: Plasma samples from 14 pediatric Crohn's Disease patients before and after 3-4 weeks on exclusive enteral nutrition were analyzed using mass spectrometry. T-test, fold change and orthogonal partial least squares discriminant analysis were used for mining significant features. Correlation analysis was performed between the annotated features and the weighted pediatric Crohn's disease activity index using Pearson r distance. RESULTS: Among the 13 compounds which decreased during exclusive enteral nutrition, most are related to diet, while one is a bacterial metabolite, Bacteriohopane-32,33,34,35-tetrol. The phosphatidic acid metabolite PA(15:1/18:0) was significantly reduced and correlated with the weighted pediatric Crohn's disease activity index. Lipids increased during exclusive enteral nutrition therapy included phosphatidylethanolamines; PE(24:1/24:1), PE(17:2/20:2) and one lactosylceramide; LacCer(d18:1/14:0). CONCLUSION: Food additives and other phytochemicals were the major metabolites, which decreased following the exclusion of a regular diet during exclusive enteral nutrition. An alteration in bacterial biomarkers may reflect changes in intestinal microbiota composition and metabolism. Thus, metabolomics provides an opportunity to characterize the molecular mechanisms of dietary factors triggering Crohn's Disease activity, and the mechanisms of action of exclusive enteral nutrition, thereby providing the basis for the development and evaluation of improved intervention strategies for prevention and treatment.

Anti-TNF therapy for inflammatory bowel disease in patients with neurodegenerative Niemann-Pick disease Type C.

Background:  Blockade of tumour necrosis factor (anti-TNF) is effective in patients with Crohn's Disease but has been associated with infection risk and neurological complications such as demyelination. Niemann-Pick disease Type C1 (NPC1) is a lysosomal storage disorder presenting in childhood with neurological deterioration, liver damage and respiratory infections. Some NPC1 patients develop severe Crohn's disease. Our objective was to investigate the safety and effectiveness of anti-TNF in NPC1 patients with Crohn's disease. Methods: Retrospective data on phenotype and therapy response were collected in 2019-2020 for the time period 2014 to 2020 from patients in the UK, France, Germany and Canada with genetically confirmed NPC1 defects and intestinal inflammation. We investigated TNF secretion in peripheral blood mononuclear cells treated with NPC1 inhibitor in response to bacterial stimuli . Results: NPC1 inhibitor treated peripheral blood mononuclear cells (PBMCs) show significantly increased TNF production after lipopolysaccharide or bacterial challenge providing a rationale for anti-TNF therapy. We identified 4 NPC1 patients with Crohn's disease (CD)-like intestinal inflammation treated using anti-TNF therapy (mean age of onset 8.1 years, mean treatment length 27.75 months, overall treatment period 9.25 patient years). Anti-TNF therapy was associated with reduced gastrointestinal symptoms with no apparent adverse neurological events. Therapy improved intestinal inflammation in 4 patients. Conclusions: Anti-TNF therapy appears safe in patients with NPC1 and is an effective treatment strategy for the management of intestinal inflammation in these patients.

[Fecal Microbiota Transfer (FMT) in Children and Adolescents - Review and statement by the GPGE microbiome working group]. / Fäkaler Mikrobiota Transfer (FMT) bei Kindern und Jugendlichen ­ Review und Stellungnahme der GPGE AG Mikrobiom.

The human microbiome and especially the gastrointestinal microbiota are associated with health and disease. Disturbance in the composition or function of fecal microbiota (dysbiosis) plays a role in the development of pediatric gastrointestinal diseases. Fecal microbiota transfer (FMT) is a special intervention, where microbiota are transferred from a healthy donor.In this review we describe the current state of knowledge for FMT in pediatric patients. There is satisfactory evidence concerning FMT in patients with recurrent C. difficile infection. For inflammatory bowel disease, few studies show a potential benefit.Adverse events occurred frequently in clinical studies, but were mostly mild and transient. There are hardly any data on long-term side effects of FMT, which are particularly significant for pediatrics. In practice, there is uncertainty as to which application route, dosage or frequency should be used. Legally, donor stool is considered a drug in German-speaking countries, for which no marketing authorization exists.In conclusion, knowledge about physiology, efficacy and side effects of FMT is insufficient and legal concerns complicate its implementation. More studies on this topic are needed urgently.

Valosin-containing protein-regulated endoplasmic reticulum stress causes NOD2-dependent inflammatory responses.

NOD2 polymorphisms may affect sensing of the bacterial muramyl dipeptide (MDP) and trigger perturbed inflammatory responses. Genetic screening of a patient with immunodeficiency and enteropathy revealed a rare homozygous missense mutation in the first CARD domain of NOD2 (ENST00000300589; c.160G > A, p.E54K). Biochemical assays confirmed impaired NOD2-dependent signaling and proinflammatory cytokine production in patient's cells and heterologous cellular models with overexpression of the NOD2 mutant. Immunoprecipitation-coupled mass spectrometry unveiled the ATPase valosin-containing protein (VCP) as novel interaction partner of wildtype NOD2, while the binding to the NOD2 variant p.E54K was abrogated. Knockdown of VCP in coloncarcinoma cells led to impaired NF-κB activity and IL8 expression upon MDP stimulation. In contrast, tunicamycin-induced ER stress resulted in increased IL8, CXCL1, and CXCL2 production in cells with knockdown of VCP, while enhanced expression of these proinflammatory molecules was abolished upon knockout of NOD2. Taken together, these data suggest that VCP-mediated inflammatory responses upon ER stress are NOD2-dependent.

Epstein-Barr Virus Prevalence at Diagnosis and Seroconversion during Follow-Up in Pediatric Inflammatory Bowel Disease.

Primary Epstein-Barr virus infection in pediatric patients with inflammatory bowel disease during immunomodulation with thiopurines has been associated with increased risk for malignancies or hemophagocytic lymphohistiocytosis. We determined Epstein-Barr virus (EBV) seroprevalence at inflammatory bowel disease (IBD) diagnosis and seroconversion during follow-up in a large single center cohort of children with IBD. EBV serology results and patient characteristics were retrospectively retrieved from the hospital documentation system. EBV seronegative patients at IBD diagnosis were prospectively retested. We report on IBD patients with symptomatic active EBV infection and a complicated disease course, and those diagnosed with malignancy with respect to EBV status and drug exposure. Of 402 patients, 194 (48%) had available EBV serology results at time of IBD diagnosis at a median of 12 years (IQR 9-14 years). Thereof, 102 (53%) were EBV-positive. Of 92 EBV-negative patients, 66 were retested and 17% showed a seroconversion at a mean follow-up time of 4.3 years (SD 3 years). Three children treated with azathioprine experienced acute clinically relevant EBV infection 2, 2.5, and 4 years after IBD diagnosis, two developed signs of hemophagocytic lymphohistiocytosis. Three cases of malignancy occurred in the cohort, though none seemed to be triggered by EBV. In conclusion, almost 50% of pediatric IBD patients were EBV-naïve following diagnosis and may be at increased risk to develop severe EBV infection during immunosuppressive therapy, potentially associated with complications such as hemophagocytic lymphohistiocytosis or malignancy.

Deficiency in X-linked inhibitor of apoptosis protein promotes susceptibility to microbial triggers of intestinal inflammation.

Inflammatory bowel disease (IBD) is characterized by inappropriate immune responses to the microbiota in genetically susceptible hosts, but little is known about the pathways that link individual genetic alterations to microbiota-dependent inflammation. Here, we demonstrated that the loss of X-linked inhibitor of apoptosis protein (XIAP), a gene associated with Mendelian IBD, rendered Paneth cells sensitive to microbiota-, tumor necrosis factor (TNF)­, receptor-interacting protein kinase 1 (RIPK1)­, and RIPK3-dependent cell death. This was associated with deficiency in Paneth cell­derived antimicrobial peptides and alterations in the stratification and composition of the microbiota. Loss of XIAP was not sufficient to elicit intestinal inflammation but provided susceptibility to pathobionts able to promote granulomatous ileitis, which could be prevented by administration of a Paneth cell­derived antimicrobial peptide. These data reveal a pathway critical for host-microbial cross-talk, which is required for intestinal homeostasis and the prevention of inflammation and which is amenable to therapeutic targeting.

Following Pediatric and Adult IBD Patients through the COVID-19 Pandemic: Changes in Psychosocial Burden and Perception of Infection Risk and Harm over Time.

BACKGROUND: COVID-19-associated restrictions impact societies. We investigated the impact in a large cohort of inflammatory bowel disease (IBD) patients. METHODS: Pediatric (pIBD) and adult patients and pIBD parents completed validated questionnaires for self-perceived stress (Perceived Stress Questionnaire, PSQ) and quality of life from July to October 2020 (1st survey) and March to April 2021 (2nd survey). Analyses were stratified by age groups (6-20, >20-40, >40-60, >60 years). Perceived risk of infection and harm from COVID-19 were rated on a 1-7 scale. An index for severe outcome (SIRSCO) was calculated. Multivariable logistic regression analysis was performed. RESULTS: Of 820 invited patients, 504 (62%, 6-85 years) patients and 86 pIBD parents completed the 1st, thereof 403 (80.4%) the 2nd survey. COVID-19 restrictions resulted in cancelled doctoral appointments (26.7%), decreased physical activity, increased food intake, unintended weight gain and sleep disturbance. PSQ increased with disease activity. Elderly males rated lower compared to females or younger adults. PSQ in pIBD mothers were comparable to moderate/severe IBD adults. Infection risk and harm were perceived high in 36% and 75.4%. Multivariable logistic models revealed associations of higher perceived risk with >3 household members, job conditions and female gender, and of perceived harm with higher SIRSCO, unintended weight change, but not with gender or age. Cancelled clinic-visits were associated with both. SARS-CoV-2 antibodies prior 2nd infection wave were positive in 2/472 (0.4%). CONCLUSIONS: IBD patients report a high degree of stress and self-perceived risk of complications from COVID-19 with major differences related to gender and age. Low seroprevalence may indicate altered immune response.

Esophageal Perforation and EVAC in Pediatric Patients: A Case Series of Four Children.

Introduction: In pediatric patients, esophageal perforation (EP) is rare but associated with significant morbidity and mortality rates of up to 20-30%. In addition to standard treatment options, endoscopic esophageal vacuum-assisted closure (EVAC) therapy has shown promising results, especially in adult patients. Thus far, the only data on technical success and effectiveness of EVAC in pediatric patients were published in 2018 by Manfredi et al. at Boston Children's Hospital. The sparse data on EVAC in children indicates that this promising technique has been barely utilized in pediatric patients. More data are needed to evaluate efficacy and outcomes of this technique in pediatric patients. Method: We reviewed five cases of therapy using EVAC, ArgyleTM Replogle Suction Catheter (RSC), or both on pediatric patients with EP in our institution between October 2018 and April 2020. Results: Five patients with EP (median 3.4 years; 2 males) were treated with EVAC, RSC, or a combination. Complete closure of EP was not achieved after EVAC alone, though patients' health stabilized and inflammation and size of EP decreased after EVAC. Four patients then were treated with RSC until the EP healed. One patient needed surgery as the recurrent fistula did not heal sufficiently after 3 weeks of EVAC therapy. Two patients developed stenosis and were successfully treated with dilatations. One patient treated with RSC alone showed persistent EP after 5 weeks. Conclusion: EVAC in pediatric patients is technically feasible and a promising method to treat EP, regardless of the underlying cause. EVAC therapy can be terminated as soon as local inflammation and C-reactive protein levels decrease, even if the mucosa is not healed completely at that time. A promising subsequent treatment is RSC. An earlier switch to RSC can substantially reduce the need of anesthesia during subsequent treatments. Our findings indicate that EVAC is more effective than RSC alone. In some cases, EVAC can be used to improve the tissues condition in preparation for a re-do surgery. At 1 year after therapy, all but one patient demonstrated sufficient weight gain. Further prospective studies with a larger cohort are required to confirm our observations from this small case series.

NBAS Variants Are Associated with Quantitative and Qualitative NK and B Cell Deficiency.

PURPOSE: Biallelic pathogenic NBAS variants manifest as a multisystem disorder with heterogeneous clinical phenotypes such as recurrent acute liver failure, growth retardation, and susceptibility to infections. This study explores how NBAS-associated disease affects cells of the innate and adaptive immune system. METHODS: Clinical and laboratory parameters were combined with functional multi-parametric immunophenotyping methods in fifteen NBAS-deficient patients to discover possible alterations in their immune system. RESULTS: Our study revealed reduced absolute numbers of mature CD56dim natural killer (NK) cells. Notably, the residual NK cell population in NBAS-deficient patients exerted a lower potential for activation and degranulation in response to K562 target cells, suggesting an NK cell-intrinsic role for NBAS in the release of cytotoxic granules. NBAS-deficient NK cell activation and degranulation was normalized upon pre-activation by IL-2 in vitro, suggesting that functional impairment was reversible. In addition, we observed a reduced number of naïve B cells in the peripheral blood associated with hypogammaglobulinemia. CONCLUSION: In summary, we demonstrate that pathogenic biallelic variants in NBAS are associated with dysfunctional NK cells as well as impaired adaptive humoral immunity.

Abatacept for treatment-refractory pediatric CTLA4-haploinsufficiency.

CTLA4-haploinsufficiency is a complex disease of immune dysregulation presenting with a broad spectrum of clinical manifestations. CTLA4-Fc fusion proteins such as abatacept have been described to alleviate immune dysregulation in several adult cases of CTLA4-haploinsufficiency. However, until now only few cases of pediatric CTLA4-haploinsufficiency treated with abatacept have been described. Here we present two pediatric cases of severe CTLA4-haploinsufficiency refractory to conventional immunosuppressive therapies that responded rapidly to treatment with abatacept. No side effects were observed during a follow-up period of 7-15 months. While one patient has successfully undergone HSCT the second patient continues to receive abatacept. Our cases demonstrate safe medium-term use of abatacept in the pediatric population.

Clinical Genomics for the Diagnosis of Monogenic Forms of Inflammatory Bowel Disease: A Position Paper From the Paediatric IBD Porto Group of European Society of Paediatric Gastroenterology, Hepatology and Nutrition.

BACKGROUND: It is important to identify patients with monogenic IBD as management may differ from classical IBD. In this position statement we formulate recommendations for the use of genomics in evaluating potential monogenic causes of IBD across age groups. METHODS: The consensus included paediatric IBD specialists from the Paediatric IBD Porto group of the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and specialists from several monogenic IBD research consortia. We defined key topics and performed a systematic literature review to cover indications, technologies (targeted panel, exome and genome sequencing), gene panel setup, cost-effectiveness of genetic screening, and requirements for the clinical care setting. We developed recommendations that were voted upon by all authors and Porto group members (32 voting specialists). RESULTS: We recommend next-generation DNA-sequencing technologies to diagnose monogenic causes of IBD in routine clinical practice embedded in a setting of multidisciplinary patient care. Routine genetic screening is not recommended for all IBD patients. Genetic testing should be considered depending on age of IBD-onset (infantile IBD, very early-onset IBD, paediatric or young adult IBD), and further criteria, such as family history, relevant comorbidities, and extraintestinal manifestations. Genetic testing is also recommended in advance of hematopoietic stem cell transplantation. We developed a diagnostic algorithm that includes a gene panel of 75 monogenic IBD genes. Considerations are provided also for low resource countries. CONCLUSIONS: Genomic technologies should be considered an integral part of patient care to investigate patients at risk for monogenic forms of IBD.

Metabolomic Signatures in Pediatric Crohn's Disease Patients with Mild or Quiescent Disease Treated with Partial Enteral Nutrition: A Feasibility Study.

Little is known about the metabolic response of pediatric Crohn's disease (CD) patients to partial enteral nutrition (PEN) therapy and the impact of disease activity and inflammation. We analyzed plasma samples from a nonrandomized controlled intervention study investigating the effect of partial enteral nutrition (PEN) on bone health and growth throughout one year with untargeted metabolomics using high-performance liquid chromatography (HPLC) coupled with high-resolution mass spectrometry (HRMS). Thirty-four paired samples from two time points (baseline and 12 months) were analyzed. Patients (median age: 13.9 years, range: 7-18.9 years, 44% females) were in remission or had mild disease activity. The intervention group received a casein-based formula for 12 months, providing ~25% of estimated daily energy requirements. Sparse partial least squares discriminant analysis (splsda) was applied for group discrimination and identifying sources of variation to identify the impact of PEN. We also investigated the correlation of metabolites with inflammation markers, including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and fecal calprotectin. After 12 months, our results show substantial difference between PEN and non-PEN groups in the metabolome of CD patients in remission or with mild disease activity. Inflammatory markers were associated with individual compounds and chemical classes such as isoprenoids and phospholipids. Identified compounds comprise metabolites produced by human or bacterial metabolism, as well as xenobiotics recognized as flavoring agents and environmental contaminants and their biotransformation products. Further longitudinal studies that also include patients with higher disease activity are warranted to evaluate the suitability of these metabolic biomarkers for predicting disease activity.