Abstract Background Acute severe colitis (ASC) is a potentially life-threatening event. Optimal timing for second-line treatment in children is mainly based on the clinical score Pediatric Ulcerative Colitis Activity Index (PUCAI) score. The aim of our study was to evaluate the potential role of bowel ultrasound scan (BUS) in predicting short-term treatment outcomes in pediatric ASC. Methods This was a prospective longitudinal study, conducted across ten European centers between March 2020 and March 2024. Biologic-naïve children with Ulcerative Colitis hospitalized for ASC, either at diagnosis or at disease relapse, were included. Each patient underwent two BUS, the first one within the first 48 hours of from IVCS intravenous corticosteroids administration and the second one within 5-7 days from treatment initiation. Key metrics assessed included colonic wall thickness (CWT), colonic wall stratification (CWS) and colonic wall blood flow via power Doppler. All the above-mentioned ultrasound parameters were recorded in 4 different segments of the bowel: ascending, transverse, descending, and sigmoid colon. Furthermore, Milan ultrasound criteria (MUC) score was also calculated for each colonic quadrant. Clinical, laboratory, and treatment data were gathered during hospitalization and at 2-, 4-, and 8-weeks follow-up. Results 59 patients (61% males, median age at ASC: 14.2 years) were included. Almost 60% of patients had pancolitis, 22 (37.3%) experienced ASC at disease onset. Table 1. summarizes patients’ characteristics at ASC. 38 (64.4%) patients failed to respond intravenous corticosteroids (IVCS) and required second-line therapy with infliximab (IFX). Patients who required step-up treatment with IFX had higher colonic wall thickness (CWT) and more frequently an increased vascularization (Limberg score > 2) (p=0.041 and p=0.005, respectively). Furthermore, patients who failed to respond to IVCS and required escalation to IFX had a higher MUC score at firs BUS (p=0.042). Ten patients (16.9%) failed to respond to medical treatment and required short-term colectomy (within 8 weeks of follow-up). Patients who required colectomy had a higher CWT both at first and at second BUS (p=0.033 and p=0.004, respectively). Moreover, patients who responded to medical therapy had higher DeltaCWT (difference between worse CWT at first and at second BUS) compared to those who required surgery (p=0.0018). Conclusion BUS may serve as an effective noninvasive tool to predict first-line therapy failure and the need for colectomy in patients with ASC. Its implementation in clinical practice may enable physician to support clinical evaluation and tailor treatment escalation upon patient’s individual characteristics.

Abstract Background Indigo naturalis (QingDai, QD) is effective in inducing remission in adults with ulcerative colitis (UC). However, data in pediatrics is limited and potential pulmonary hypertension and hepatitis remain a concern. In this prospective open-label study, we aimed to evaluate the efficacy and safety of QD for pediatric UC. Methods Children aged 4-18 years with mild-moderate UC (Pediatric Ulcerative Colitis Activity Index [PUCAI] 10-60) on stable medication, and not receiving steroids or biologics, were treated with QD for 6 weeks. Initial doses were weight-based (500/750/1000 mg/day for 20-30/30-40/40+ kg, respectively) with possible dose escalation at week 3. Echocardiography was performed at baseline and week 6. The primary outcome was corticosteroid-free remission at week 6 defined as PUCAI<10 and a ≥10-point reduction in PUCAI. Results were analyzed using intention-to-treat. Results Twenty children were enrolled (age 13.6±2.4 years, disease duration 7 [3-12] months, 50% female); all were treated at baseline with oral 5-ASA regimens. Two discontinued QD early (UC exacerbation, poor compliance), 18 completed the study and 9 required dose escalation at week 3. Clinical remission was achieved in 13 patients (65%). Calprotectin levels <250mg/kg and <100mg/kg at week 6 were observed in 13 (65%) and 10 (50%), patients, respectively. Significant reduction compared to baseline were noted in both PUCAI (30 [15-40] vs. 5 [5-15], p<0.01) and calprotectin (588 [305-1,137] vs 97 [44-438], p=0.03). Adverse events included headache (4 patients), vomiting (1) and nausea (1) and did not lead to treatment discontinuation. Mild transient hepatitis was noted in a single patient at week 3, and another patient had minimal ALT elevation at week 6. There was no evidence of pulmonary hypertension at week 6. Conclusion QD is effective in inducing remission in biologic-naïve children with mild-moderate UC. Headache was the most common adverse event; pulmonary hypertension was not observed. Additional efficacy and safety studies are required to determine whether QD can be used for maintenance.

Abstract Background Anti-Saccharomyces cerevisiae antibodies (ASCA) have been associated with a more aggressive Crohn’s disease (CD) phenotype. However, the effect of ASCA serology on the response to biologic therapy, specifically in children on anti-TNF therapy, is unknown. Our goal was to assess whether ASCA levels are associated with clinical outcomes in pediatric CD patients treated with anti-TNF antibodies. Methods A single center retrospective study. Demographic, clinical and laboratory data were collected from pediatric CD patients (aged 2.2-17.9 years) treated with anti-TNF therapy, who were tested for IgG ASCA levels upon diagnosis, between 2010-2023. The cut-off value for a positive ASCA result was defined as 30 EU/mL. Clinical outcomes included durability of anti-TNF therapy, corticosteroid-free survival (CSFS) at week 52 of therapy, IBD-associated hospitalizations and IBD related surgery. Results One hundred seventy-two patients with CD (69 ,39% females) with a median age at diagnosis of 13.5 (11.1-15.4) years were included. Ninety-two (52%) patients had positive ASCA (> 30 EU/mL). ASCA positivity was associated with female sex (p=0.02) and ileocolonic disease location at diagnosis (p=0.02). Sixty-six (37%) patients were treated with infliximab and 111 (63%) with adalimumab. The median time of follow-up in our cohort was 115 (65-174) weeks. Time to discontinuation of anti-TNF was comparable between patients with ASCA positive and negative levels (97.8% vs. 97.4% and 89.3% vs. 87.4% at 1 and 3 years, respectively). In addition, time to IBD-associated hospitalization and surgery were also similar. Interestingly, patients with positive ASCA achieved CSFR more often, compared to patients with ASCA negative (P=0.04). Sub-analysis of patients with high ASCA values, the top 20%, (>80 EU/mL) demonstrated significantly longer durability of anti-TNF, compared to the patients with lower ASCA levels (<80 EU/mL,p= 0.02). Conclusion ASCA positivity is not associated with worse outcomes in pediatric patients with CD treated with TNF antagonists.

Abstract Background The intestinal mucosa regenerates every few days, and cells are continuously shed into the gut lumen. These cells, primarily epithelial and immune cells, have recently been shown to remain viable after shedding and hold critical information for assessing bowel pathology. Analysis of endoscopic washes of luminal material during colonoscopies suggests that the human transcriptome in fecal material accurately reflects degree of histologic inflammation in patients with inflammatory bowel diseases (IBD). We aimed to define whether transcriptomic analysis of stool samples can reflect degree of intestinal inflammation in patients with IBD. Methods Bulk RNA sequencing was performed on stool samples to obtain fecal human transcriptomes from 82 IBD patients, as well as from healthy controls. Each sample received an inflammation score derived from a group of pro-inflammatory transcripts. Inflammatory score was compared to fecal calprotectin as well as endoscopic evaluation. Results The quality of human RNA isolated from fecal content was high, with a median of 2,218 human genes detected per sample. The correlation between fecal calprotectin protein levels and mRNA expression was high (r=0.75). An inflammatory score was generated based on a group of differentially expressed genes. The inflammatory score provided high sensitivity and specificity (both 90%) in predicting endoscopic inflammatory activity when compared to colonoscopic findings. Conclusion Fecal shed cell transcriptomics provided a novel non-invasive tool to measure inflammatory activity at the endoscopic level in patients with IBD. Ongoing studies will address whether this technology can assist in defining degree and location of inflammation, as well as predict response to different therapies.

BACKGROUND:Loss of response (LOR) to anti-TNFα in patients with Crohn's disease (CD) is not uncommon. A particular challenge is pharmacodynamic LOR (inflammatory activity persisting despite adequate trough concentrations, TC). AIMS:To explore the outcomes of paediatric patients with CD following adalimumab pharmacodynamic failure. METHODS:We conducted a multi-centre retrospective cohort study. Data of patients who experienced adalimumab LOR with TC (≥7.5 µgr/ml) and switched to either infliximab or ustekinumab were retrieved. RESULTS:The cohort included 70 patients (57 % male), with median duration on adalimumab of 13 months (IQR 8-24.5) and 12 months (IQR 6-29) of follow-up on subsequent therapy. Median adalimumab TC before switching was 11.1 (IQR 8.5-15.1 µgr/ml). At switching, the 2 group (infliximab=33, ustekinumab=37), were comparable for all disease variables. The infliximab group demonstrated superior outcomes in drug sustainability (88 % vs. 30 %; p = 0.001), corticosteroid-free clinical remission (58 % vs. 32 %; p = 0.03), lower surgical rate (3 % vs. 27 %; p = 0.006), higher C-reactive protein normalization (76 % vs. 24 %; p < 0.001), and albumin levels (4.1 ± 0.3 vs. 3.8 ± 0.4; p = 0.001) CONCLUSIONS: For paediatric patients with CD following adalimumab pharmacodynamic failure, a switch in-class to infliximab may be more effective than a switch to ustekinumab.

Abstract Background Intensification of adalimumab (ADL) dosing to weekly 40 mg injections, in response to low drug levels, has been shown to provide beneficial outcomes in pediatric patients with Crohn’s disease (CD). Our study aimed to evaluate the safety and efficacy of weekly 80 mg ADL administration in children with CD. Methods In this retrospective cohort study conducted across five Israeli centers, we reviewed the medical records of pediatric CD patients who received a high dose of ADL 80 mg weekly injections between 2016 and 2023. Collected data included demographic characteristics, disease features, laboratory studies, and treatment outcomes. Results Thirty-two children with CD were included: mean age 15.8 (±1.7) years at intensification, 21 male (66%), 18 (56%) with L3 phenotype. The median time to ADL 80 mg intensification from ADL induction was 48.4 weeks (IQR 23.1-122.5). The mean weighted Pediatric Crohn's Disease Activity Index (wPCDAI) was 28.5 (±16.9) at the time of intensification and the median calprotectin and C-reactive protein levels were 937 μg/g (IQR 540-1410) and 1.3 mg/dL (IQR 0.6-5.2), respectively. Clinically active disease was the main reason for ADL intensification (30, 94%). Baseline ADL levels were available in 30 patients (94%) with a median of 3.8 μg/mL (IQR 2.4-7.2). Among these, 23 children (77%) failed to achieve a target of ≥ 7.5 μg/mL. The median follow-up duration from the intensification dose was 91.2 weeks (IQR 53.6-149.1). Corticosteroids were required in 5/32 (15.6%) children, with a median time of 32.3 weeks (IQR 10.7-51.3) from intensification. There was no statistically significant difference in steroid utilization rates between children who achieved a target baseline drug level of ≥ 7.5 μg/mL and those who did not (p=0.934). Thirteen individuals (41%) discontinued ADL treatment, within a median of 24.7 weeks (IQR 11.7-57.1) from intensification. CD-related exacerbation, hospitalization, and surgery rates were 9 (28%), 4 (13%), and 2 (6%), respectively. No statistically significant differences were found in exacerbation (p=0.406), hospitalization (p=0.322), or surgery rates (p=0.427) between children who achieved a baseline ADL trough concentration level of ≥ 7.5 μg/mL and those who did not. Overall, ADL intensification was safe, but 3 (9%) patients developed new-onset psoriasis. Conclusion Our findings support the safety and efficacy of administering ADL at a weekly dosage of 80 mg as maintenance therapy in pediatric patients with moderate to severe CD.

BACKGROUND:Whether primary sclerosing cholangitis related to inflammatory bowel disease (PSC-IBD) diagnosed before 6 years (ie, VEO-IBD) has a distinct phenotype and disease course is uninvestigated. We aimed to analyze the characteristics and natural history of VEO-PSC-IBD, compared with early and adolescent-onset PSC-IBD. METHODS:This is a multicenter, retrospective, case-control study from 15 centers affiliated with the Porto and Interest IBD group of ESPGHAN. Demographic, clinical, laboratory, endoscopic, and imaging data were collected at baseline and every 6 months. Inflammatory bowel disease-related (clinical remission, need for systemic steroids and biologics, and surgery) and PSC-related (biliary and portal hypertensive complications, need for treatment escalation and liver transplantation, cholangiocarcinoma, or death) outcomes were compared between the 2 groups. RESULTS:Sixty-nine children were included, with a median follow-up of 3.63 years (interquartile range, 1-11): 28 with VEO-PSC-IBD (23 UC [82%], 2 IBD-U [7%] and 3 [11%] CD), and 41 with PSC-IBD (37 UC [90%], 3 IBDU [7.5%] and 1 [2.5%] CD). Most patients with UC presented with pancolitis (92% in VEO-PSC-UC vs 85% in PSC-UC, P = .2). A higher number of patients with VEO-PSC-IBD were diagnosed with PSC/autoimmune hepatitis overlap syndrome than older children (24 [92%] vs 27 [67.5%] PSC-IBD, P = .03), whereas no other differences were found for PSC-related variables. Time to biliary strictures and infective cholangitis was lower in the VEO-PSC-IBD group (P = .01 and P = .04, respectively), while no difference was found for other outcomes. No cases of cholangiocarcinoma were reported. CONCLUSIONS:Primary sclerosing cholangitis related to inflammatory bowel disease has similar baseline characteristics whether diagnosed as VEO-IBD or thereafter. A milder disease course in terms of biliary complications characterizes VEO-PSC-IBD.

Abstract Background Chronic Recurrent Multifocal Osteomyelitis (CRMO) is a rare, autoinflammatory bone disorder. CRMO was linked with inflammatory bowel disease (IBD), either as an extra intestinal manifestation or as a paradoxical effect of anti-TNFa therapy. Our goal was to define the clinical features and natural history of patients carrying a dual diagnosis of CRMO and IBD Methods Medical records of pediatric patients with a dual diagnosis of IBD and CRMO were reviewed in nineteen centers from the Paediatric IBD Porto Group of ESPGHAN. Collected data included demographic characteristics, disease features, laboratory studies, bone imaging findings and outcomes of each disease Results Forty five patients (21 [47%] females) with a diagnosis of CRMO and IBD (32 [71%] with Crohn’s disease) were included. Median age at the time of dual diagnosis was was 10.2 (IQR 12-13.5) years. Patients were divided into 3 groups, based on whether CRMO developed before, during or after IBD diagnosis. In 15 patients (33%), CRMO was diagnosed ±3 months from the time of IBD diagnosis, with 8 (53%) and 2 (13%) exhibiting mild and moderate-severe IBD activity, respectively. In 20 children (44%) IBD preceded CRMO diagnosis by >3 months with a median time of 238 (85-344) weeks. At the time of dual diagnosis, 12 (60%) patients were in IBD remission and 5 (25%) exhibited moderate-severe disease activity; however, CRP and ESR were elevated (1.5 [0.4-3.4] mg/dL and 35 [21-55] mm/h, respectively) while median fecal calprotectin was 567 (68-1800) mcg/gr, including 4 patients <100 mcg/gr. 17 patients (85%) were on anti-TNFa medication at the time CRMO developed. In 10 (22%) patients CRMO preceded the diagnosis of IBD (>3 months before IBD evolution) with a median time 46 (25-248) weeks. At time of IBD presentation, CRMO was in remission in 5 patients (50%). 4 patients were diagnosed with IBD, despite the lack of any abnormal gastro-intestinal symptoms. In patients in which CRMO was diagnosed after or during IBD diagnosis, different therapeutic regimens were used, including anti-TNFa agents, methotrexate, ustekinumab, NSAID’s and corticosteroids. Two patients also received bisphosphonates. In patients in which CRMO was diagnosed after or during IBD diagnosis, CRMO remission, defined as lack of bone pain, was achieved in 22.2 (15-51.8) weeks. CRMO complications occurred in 4 patients and included vertebral collapse, length discrepancy, bone fracture and bone deformity Conclusion In the largest cohort to date, CRMO presentation was not necessarily related to clinically active intestinal inflammation and could present before, during or after IBD diagnosis. CRMO remission was achieved in all patients; Nevertheless, a small number of patients developed significant bone complications

Abstract Background Current data on dual biologic or small molecules therapy in children are limited. The aim of the study was to evaluate the effectiveness and safety of dual therapy in paediatric patients with IBD. Methods This was a retrospective multicenter study from 14 centers affiliated with the IBD interest and Porto groups of ESPGHAN. We included children with IBD who were treated with combination of biologic agents or biologic and small molecule, with at least 3 months of follow-up under this therapy. Demographic, clinical, laboratory, endoscopic and imaging data were collected. Adverse events were recorded. All analyses were done in the intention-to-treat population. Children that discontinued therapy were considered treatment failures and were imputed for non-response, while missing data was imputed according to the last observation carried forward method. Results Sixty-two children [35 Crohn’s disease (CD), 27 ulcerative colitis (UC)], with a median age of 15.5 (IQR 13.1-16.8) years and disease duration of 3.8 (IQR 2.5-6.1) years were included. All children failed previous biologics and 47 (76%) failed at least two biologic agents. The dual therapy included anti-TNF agent and vedolizumab in 30 children (48%), anti-TNF and ustekinumab in 21 children (34%), vedolizumab and ustekinumab in 8 children (13%), and tofacitinib and other biologics in 3 children (5%). Clinical remission was observed in 21 (35%), 30 (50%) and 38 (63%) children at 3, 6 and 12 months, respectively. Of 27 children who were treated with corticosteroids at baseline, 20 (74.1%) were weaned within 3 months after the initiation of dual therapy. At 12 months of follow up, normalization of C-reactive protein and decrease in fecal calprotectin to < 250 mcg/g were achieved in 75% and 64%, respectively. Endoscopic and transmural healing were observed in 2/23 (9%) and 5/16 (31%) children, respectively. Male sex and diagnosis of UC were associated with higher likelihood of clinical remission (p=0.017 and p=0.020, respectively). Adverse events were reported in 29 (47%) children. While most adverse event were mild, 8 were regarded as serious and 6 (10%) led to discontinuation of dual therapy. The serious adverse events included infusion reaction to infliximab, fatigue and headache following vedolizumab infusion, severe skin eruptions (3 patients), cellulitis and skin abscess, elevated liver enzymes and deep vein thrombosis. Conclusion Dual biologic or small molecules therapy may be effective in children with otherwise refractory IBD. The risk of serious adverse events should be considered before recommending dual therapy.

Abstract Background Although sexual dysfunction (SD) and sexually transmitted infections (STI) are occasionally encountered in patients with inflammatory bowel disease (IBD), physicians may be embarrassed to discuss these issues. This is especially true in adolescent patients, where parents are active participants in clinic visits. In addition, data in the literature about SD in this age group is limited. Our aims were to assess pediatric gastroenterologists (PedGI) knowledge and common practice regarding sexual advice and STI in pediatric patients with IBD. Methods A questionnaire was sent to all registered PedGI in Israel, and included 24 questions addressing knowledge of adolescent sexual behavior, SD, receptive anal intercourse (RAI) and STI in pediatric patients with IBD. Results Overall, 52 physicians completed the questionnaire (27 males, 52%). Only 50% provided the correct answer regarding the mean age at which Israeli youth start practicing sexual activity, whereas none were correct regarding the mean age when RAI is practiced. Fifty eight percent rightfully stated that SD is equally distributed among males and females and 38% responded that it is equally prevalent among patients with Crohn’s and those with Ulcerative Colitis. The most quoted, incorrectly, risk factor for SD was perianal disease. Seventy five percent thought that providers should talk about sex with their patients, but only 19% actually do so, most often in response to a patient’s query. Ninety six percent felt they do not have enough knowledge about SD in IBD. Finally, only 2% routinely obtain bacterial swabs for STI in patients with refractory proctitis, although 15% encountered such as a problem in clinic. Conclusion Sexuality and SD are not discussed routinely in the pediatric IBD clinics by the majority of PedGI. Providers should obtain more knowledge in the field, and proactively discuss these issues with teenagers with IBD.

Abstract Background The human circadian clock is present in cells throughout the body. It consists of CLOCK and BMAL1 that heterodimerize and bind to E-box sequences to mediate transcription of a large number of genes, including Periods (PERs) and Cryptochromes (CRYs). PERs and CRYs constitute part of the negative feedback loop and inhibit CLOCK:BMAL1-mediated transcription. Recently, we have shown that patients with active ulcerative colitis (UC) display tissue-specific misalignment of the molecular clock that reverts to normal following effective treatment. Several circadian clock genes also function as anti-inflammatory regulators. RORa, PPARa and PPARg are positive regulators of the clock mechanism and induce the expression of IkB, a suppressor of NFkB. In the same manner, PCG1a induces transcription of IL10. Our aim was to characterize the expression of these regulators compared to that of core clock genes and determine their correlation in UC patients. Methods Clock gene expression patterns using whole transcriptome RNA sequencing were retrieved from the IBD Transcriptome and Metatranscriptome Meta-Analysis platform (TaMMA IBD). We compared rectal biopsy gene expression of 12 clock genes and their isoforms (AMPK, BMAL1, CLOCK, CRY1, CRY2, PER1, PER2, PCG1a, PPARa, PPARg, REV-ERB, RORa, RORg and SIRT1) in 206 treatment naïve pediatric patients with UC (age 12.9±3.2; 54% male) and 20 healthy controls (age 13.9±3.3; 45% male). Spearman correlations were calculated between all 12 clock genes within each of the UC and control cohorts. Results Core clock genes: BMAL (p<0.0001), CLOCK (p<0.01) and CRY1 (p<0.0001), and the anti-inflammatory regulator gene RORa (p<0.0001) were upregulated in UC patients compared to controls. In contrast, expression of other anti-inflammatory regulatory genes: PCG1a (p<0.0001), PPARa (p<0.01), PPARg (p<0.0001) and RORg (p<0.0001) was decreased. Clock gene expression levels of healthy controls show discordant correlations compared to UC patients. For example, correlations between BMAL/REV-ERBa as well as PPARg/REV-ERBa were inverted between controls and UC patients (r=-0.44 vs. r=0.13 and r =-0.4 vs. r=0.3, respectively). Figure 1. Expression of clock and inflammation regulatory genes in UC patients vs. healthy controls. Conclusion Core clock gene expression was disrupted, and anti-inflammatory regulator gene expression was decreased in patients with active UC vs. controls. The demonstration of discordant correlations of some positive vs. negative feedback loop genes in UC highlights the clock disruption in active inflammation. Since these clock regulators also ameliorate inflammation, their reduced expression may explain not only clock dysregulation but also increased tissue inflammation.

Abstract Background Limited data are available on the use of Vedolizumab (VDZ) in paediatric Crohn’s Disease (CD) and Ulcerative Colitis (UC). We evaluated the effectiveness and safety of VDZ to induce remission at week 14 in the prospective, multicenter VEDOKIDS study. Methods We enrolled children (age 0–18 years) with CD or UC commenced on VDZ with a standardized dosing of 177mg/BSA up to 300mg at 0, 2, 6 and q8 weeks thereafter. Non-responders had their dose escalated to q4wks at the discretion of the local physician. Explicit demographic, clinical and safety data were prospectively recorded via REDcap. Clinical remission was defined as steroid- and EEN-free remission (i.e. wPCDAI<12.5 or PUCAI<10) without the need for new medications. Complete remission was defined as clinical remission with normal CRP and ESR. Predictors of response were explored by Logistic regression. Results 128 children were enrolled, 60 (47%) with CD, and 68 (53%) with UC (58 (45%) males, mean age 13.8±3.6, 93 (73%) failed previous anti-TNF, median disease duration 2.3 years (IQR 0.9–4.7)). Using the ITT principle, clinical and complete remission rates for CD at week 14 were 30% and 20%, respectively, and for UC 50% and 38%, respectively (Fig 1). Clinical remission rates of those receiving VDZ as first line biologics versus second line were 57% and 34%, respectively (p=0.019; Fig 2); the corresponding complete remission rates were 49% and 23% (p=0.004). In the UC group, disease activity at baseline measured by the PUCAI predicted clinical remission at week 14 (OR=0.95, 95%CI 0.93–0.98; median baseline PUCAI 15 (IQR 0–30) in those achieving remission and 45 (20–55) in those who did not; p=0.002). ESR (OR=0.94, 95%CI 0.89–0.98; p=0.009) and a trend towards extensive disease (L3 vs. L1 and L2; OR 0.14, 95%CI 0.18–1.036, p=0.054) predicted clinical remission in CD. During the 14 weeks, 113 adverse events (AE) were recorded in 58 children: 28 AEs were possibly related to VDZ, all of which were mild-moderate and only 3 (11%) led to discontinuation of VDZ (leukocytoclastic vasculitis, myalgia and dyspnea). There were 18 serious AEs, only one was graded as possibly related to VDZ (headache). There were 18 non-serious cases (19%) of upper respiratory infections (pharyngitis, tonsilitis, parotitis, and otitis media) and one Campylobacter jejuni which was graded as serious. Conclusion In this prospective multicenter study, VDZ was safe and effective for inducing remission in a refractory cohort of paediatric IBD, more so in UC. Disease severity and extent at baseline may predict clinical response.

Abstract Background Although Crohn’s disease (CD) is associated with a marked hyper-inflammatory response, identifying serum biomarkers associated with disease activity and outcomes is considered challenging, given lack of sensitivity of different assays. Our aim was to identify novel markers using Olink, a novel technology based on proximity extension assay, enabling detection of minute amounts of proteins. Methods Serum samples were obtained from pediatric patients with CD at the time of diagnosis and following induction therapy, and from control subjects, consisting of pediatric patients with normal endoscopic procedures, without past or present history of an immune-mediated disorder (e.g. celiac, diabetes). Serums were subjected to Olink (two panels used, consisting of 184 proteins), and analysis was performed on a Normalized Protein eXpression file by supervised, multivariate, principal component analysis and verification by univariate ANOVA with Benjamini-Hochberg and post-hoc Tukey analysis. Results Eighty-eight serum samples were collected: 30 from control subjects and 58 from 32 patients with CD (24 of them pre- and post-induction therapy). The median age of patients in the control and CD groups was 13.9 years (IQR 11.1–16.6) and 14.6 years (IQR 12.2–16.9), respectively (P=0.32). Twenty-four patients were treated with anti-TNFa agents and 8 with EEN. The median pediatric Crohn’s Disease Activity Index (PCDAI) decreased from 35 (22.5–42.5) to 5 (0–12.5, P<0.001) following induction therapy. We identified 72 proteins that significantly differed between patients and controls, and many of them were associated with CRP or ESR levels. String analysis identified several important nodes linking different proteins, including MMPs, MPO, EGFR and TNFRSF1A. Many proteins, such as resistin and different MMPs, showed a strong positive correlation with disease activity, based on PCDAI, while others, such as EGFR, showed a negative correlation. Several novel markers were identified to be highly expressed in the serum of patients with CD, including LRIG1, an intestinal stem cell marker, that was highly correlated with disease activity among the patients. Conclusion We identified novel serum markers that are associated with disease activity in pediatric patients with CD. These findings should be validated in future studies, and be complemented with expression and functional studies to define their role in mediating intestinal immune responses.

Abstract Background In patients with IBD, data on trough concentration (TC) response to adjustments in anti-TNFα treatment are scarce. Methods We included pediatric patients with IBD who were treated with anti-TNFα agents from, 2015 to, 2020 and had sequential monitoring of TC. Treatment adjustments were detected and subsequent changes in TC were recorded (next infusion for infliximab and up to, 8 weeks TC measurement for adalimumab). Patients with positive anti-drug-antibodies or with concomitant change in immunomodulatory treatment were excluded. Results For the entire cohort (86 patients), median age at diagnosis was, 13.2 (10.7–14.9) years (Females, 48%; Crohn’s disease, 72%). For infliximab, 58 patients had, 201 interval changes (98 decrease and, 103 increase) and, 26 had dose increase. Dose increase resulted in TC change in the same direction but TC changes could not be predicted due to significant variability (p=0.9). This variability could not be attributed to any specific variable. Interval decrease: Median TC pre adjustment was, 4.3 mcg/ml (IQR, 3.1–6.9 mcg/ml). For every, 10% decrease in interval, TC was increased by, 1.6 mcg/ml (B=, 1.6, 95% CI;, 0.9–2.4; p<0.001) or by, 57.2% (B=57.2, 95% CI;12.8–124.6; p=0.014). The presence of perianal disease was associated with attenuated response to interval decrease (diminished TC increase), p=0.001. Interval increase: Median TC pre change was, 12.6 mcg/ml (IQR, 9.5–12.1 mcg/ml). For every, 10% increase in interval, TC was decreased by, 0.66 mcg/ml (B=, 0.66, 95% CI;, 0.2–1.2; p=0.01) or by, 4.2% (B=, 4.2, 95% CI;, 2.0–6.4; p<0.001). The diagnosis of Crohn’s disease (VS. diagnosis of UC) was associated with reduced response to interval increase (diminished TC decrease), p=0.012. For adalimumab, 28 patients had, 31 events of interval decrease from every, 2 weeks to every week and, 12 events of interval increase back to every, 2 weeks. Interval decrease resulted in increased median TC from, 4.5 (3.5–5.3) mcg/ml to, 8.1 (6.5–10.5) mcg/ml (X1.8) while interval increase resulted in TC change from, 15.5 (12.8–18.6) mcg/ml to, 9.7 (6.5–14.6) mcg/ml (:1.6). Changes in adalimumab TC were consistently significant (p<0.001). Increase in delta TC was associated with younger age (p=0.018), lower body surface area (p<0.001) and with the absence of perianal disease (p=0.001). Laboratory measures (CRP, albumin- mostly within normal limits) were not associated with TC response for both agents. Conclusion Changes in TC following treatment adjustment can be almost linearly predicted for adalimumab but not for infliximab. Thus, following infliximab adjustment, TC should be measured in-order to assess adequate TC response.

Abstract Background Genetics plays a key role in the pathogenesis of inflammatory bowel disease (IBD). With the expanding use of next-generation sequencing, >70 different monogenic disorders associated with IBD have been identified, and most of them present in the first years of life. Recently, several patients with severe IBD were identified to harbor pathogenic mutations in Receptor-interacting serine/threonine-protein kinase 1 (RIPK1) gene, which regulates necroptosis, a necrotic cell death mechanism. We present the clinical features, genetic analysis and immune work-up of three patients with infantile-onset IBD resulting from novel RIPK1 mutations. Methods Whole exome sequencing was performed in three patients with severe infantile-onset IBD, along with sanger sequencing for conformation. Mass cytometry time of flight was conducted for in-depth immunophenotyping, including cytokine secretion analysis following lipopolysaccharide (LPS) or Phorbol myristate acetate with ionomycin (PMA-I), on one of the patient’s peripheral blood mononuclear cells, and compared to control subjects and patients with Crohn’s disease. Results All patients, born to consanguineous Muslim families, presented with severe colitis and multiple perianal fistulas in the first months of life, without severe or atypical infections. One of the patients had a partial response to high doses of inlfliximab and azathioprine, while another one failed to respond to adaliumab and later to low dose anakinra, an IL-1 receptor antagonist. Genetic studies identified novel and pathogenic genetic variants in the RIPK1 gene in all patients, that were confirmed by Sanger sequencing. Using mass cytometry time of flight unbiased clustering analysis, we identified peripheral immune dysregulation in one of these patients, characterized by an increase in IFNγ CD8+ T cells along with a decrease in monocytes, dendritic cells and B cells. Moreover, RIPK1-deficient patient’s immune cells exhibited decreased IL-6 production in response to LPS across multiple cell types including T cells B cells and innate immune cells. Conclusion Mutations in RIPK1 should be considered in very young patients presenting with colitis and perianal fistulas. Given RIPK1’s role in both immune cells (and specifically in inflammasome activation), and epithelial cells, it is unclear whether immunosuppressive medications (including IL1 blockade) as well as allogeneic hematopoietic stem cell transplantation can suppress or cure the hyper-inflammatory response in these patients. Additional studies in humans are required to better define the role of RIPK1 in regulating intestinal immune responses, and how treatment can be optimized for patients with RIPK1 deficiency.

Abstract Background Isolated colonic (L2) Crohn’s disease (CD) in adults is thought to have unique clinical and genetic features compared with ileal (L1) CD and ulcerative colitis (UC). Similar studies in paediatrics are scarce. Our goal was to characterize the clinical features of paediatric patients with isolated colonic CD and compare them to patients with ileo-cecal CD and those with UC. Methods This was a multi-center retrospective study including 21 sites affiliated with the Porto IBD group and IBD interest group of ESPGHAN. Data of paediatric patients diagnosed between 2014–2017 with L1 or L2 CD, or with UC, was collected, including information on demographic, clinical and laboratory parameters at diagnosis, end of induction, 1 year and 3 years after diagnosis (or at last follow-up). Results Data was collected on 300 children (102 L1, 94 L2, 104 UC) with similar demographic features. At diagnosis, bloody stools were identified in 45% of L2 patients, compared with 15% and 95% of L1 and UC patients, respectively (P<0.001), while fever was documented in 27% of L2 patients, compared to 13% and 3% of L1 and UC patients, respectively (P<0.001). At the time of diagnosis, the median pediatric Crohn’s disease activity index for patients with L1 and L2 was 25 (IQR 17.5–37) and 27.5 (20–40), respectively, while the median pediatric ulcerative colitis activity index was 40 (30–55) for patients with UC. C-reactive protein levels were significantly higher among CD patients (both L1 and L2), compared to patients with UC, and calprotectin values were comparable. ASCA was positive in 55%, 25% and 2% (P<0.001) and pANCA in 2%, 17% and 53% (P<0.001) in L1, L2 and UC patients, respectively. Granulomas were identified in 36% of L2 patients, similar to patients with L1 (33%). For induction therapy, exclusive enteral nutrition, oral steroids and mesalazine were used in 50%, 45% and 38% of patients with L2 CD, compared with 72%, 28% and 9%, and 0%, 52% and 75% of L1 and UC patients, respectively (P<0.001). Steroid-free clinical remission at the end of induction was overall similar between groups, around 55%. At 1-year post-diagnosis, 62%, 68% and 40% were on an immunomodulator (P=0.03) and 41%, 26% and 22% were receiving anti-TNFα agent (P=0.01), of patients with L1, L2 and UC, respectively. While time to initiation of an anti-TNFα agent was significantly shorter in L1 patients compared with L2 and UC (P=0.03), time to admission and time to surgery were similar. Conclusion Paediatric patients with isolated colonic CD exhibit several clinical features which differentiate them from ileo-cecal CD and UC. Prospective studies are required to understand the pathogenesis of this unique entity and define short- and long-term outcomes.

Anti-tumor necrosis factor alpha (anti-TNFα) therapy is commonly used to treat refractory pediatric inflammatory bowel disease (IBD). Prolonged use of anti-TNFα therapy has been linked to a number of adverse events. We aimed to assess the relationship between serum trough concentrations (TC) of anti-TNFα and adverse events rate among patients with pediatric IBD. The medical records of 135 pediatric patients with IBD who were treated with anti-TNFα agents from 2015 to 2020 and had sequential monitoring of TC were reviewed retrospectively for the presence of adverse events (infusion reactions, infections, acute cutaneous reactions, psoriatiform rashes, elevated transaminases and others). The association between demographic or disease related variables and adverse events were analyzed using multivariate analysis. Out of 135 patients, [59 (43.7%) female, mean age at diagnosis 12.9 (±3)years, 111 (82.2%) Crohn’s disease] who had 1645 measurements of TC [1037(63%) infliximab, range 0-46 µgr/ml] during a median follow-up period of 1.7 years (1.1-2.7), we recorded 120 adverse events in 42 patients (31%). When analyzing TC as continuous measure or as a categorical measure (> or <10 µgr/ml) there were not associated with a higher rate of adverse events (p=0.9).Patients who reported non-infusion related adverse events were younger at the time of diagnosis (mean age 11.4±3.9 vs.13.3±2.8years) than those without adverse effect (p=0.029). There was no statistically significant correlation between other variables (gender, disease type, Paris classification, extra-intestinal manifestation, perianal disease, and the pediatric disease activity index) and the occurrence of adverse events. Based on our cohort, higher TCs were not associated with higher rate of anti-TNF related adverse events whereas younger age at diagnosis increased the risk for such events. The study protocol was approved by the local Internal Review Board at the Rabin/Schneider Medical Center (RMC0320-10).

Abstract Background Enteric infections due to Clostridium difficile toxin (CDT) is more common in patients with inflammatory bowel disease (IBD). We aimed to assess the frequency and outcomes of CDT and non-CDT enteric infections in symptomatic paediatric patients with IBD. Methods Patients’ records were retrospectively searched for disease flares in which stool samples were collected. Each patient with a positive sample was matched with a patient with IBD flares and negative sample in order to analyse 1-year outcomes following sampling. Results A total of 618 paediatric patients with IBD (Crohn’s disease, n = 439, 71%, mean age at diagnosis 12.99 ± 3.4, females, n = 264, 42.7%) had 1204 stool samples during the study period (2001–2018). Of these, 43 (3.6%) were positive for bacteria, and 32 (74.4%) of which positive for Campylobacter jejuni. Of 463 samples for CDT, 31 (6.7%) were positive while parasitic infection was rare, 11/765 (1.4%). Overall, 19 positive C. jejuni cases and 19 positive CDT cases with matching controls were examined. During 12 months of follow-up, the mean number of disease flares and ER visits was higher among patients with positive CDT (1.5 ± 1.4 vs. 0.5 ± 0.9, p = 0.019, 1.3 ± 1.5 vs. 0.4 ± 0.8, p = 0.05, respectively) with a numeric increase of surgical interventions (3 vs. 0). There were no significant differences in disease outcomes between patients with C. jejuni infections and matched controls. Conclusion Clostridium difficile and Campylobacter jejuni are the most common enteric infections among paediatric patients with IBD but only clostridial infection results in a more severe disease course within 12 months of infection.

ABSTRACTObjectives:Growth impairment is common in children with Crohn disease (CD). We aimed to assess the effect of adalimumab (ADL) treatment on linear growth in children with CD in a post‐hoc analysis of the Pediatric Crohn's Disease AdalImumab Level–based Optimization Treatment randomized controlled trial.Methods:Children 6 to 17 years who responded to ADL induction were assessed consecutively for anthropometric parameters. Associations of these parameters with disease characteristics and disease activity were analyzed.Results:Overall, 66 patients completed 72 weeks of follow‐up (25% girls, mean age of 15.6 ± 2.5 years). Median (interquartile range [IQR]) height z score improved from −0.6 (−1.6–0.15) at baseline to −0.33 (−1.3–0.5) at week 72 (P = 0.005) with lesser improvement in patients with perianal disease. Similar effect was noted in children with growth potential (boys younger than 16 years, girls younger than 14 years). Median (IQR) height velocity standard deviation was −0.32 (−1.5–0.8) at week 26, and +0.11 (−1.1–1.3) at week 72. Median weight z score increased from −0.54 (−1.2–0.15) to −0.1 (−0.9–0.6), P < 0.001 and body mass index from −0.4 (−1.0–0.5) to 0.0 (−0.8–0.9), P = 0.005. Pediatric CD activity index and erythrocyte sedimentation rate at week 4 correlated negatively with height z score changes (P = 0.043 and P = 0.048, respectively), whereas sustained clinical and biologic remission (week 4–72) were positively associated with changes in height z scores. Significant improvement in linear growth was predicted by lower pediatric CD activity index and erythrocyte sedimentation rate at the end of induction and sustained clinical remission (P = 0.05) and sustained normal C‐reactive protein (P = 0.001) at all visits.Conclusion:In children with moderate‐to‐severe CD, ADL treatment had a significant effect on linear growth, with normalization of weight and body mass index (clinicaltrials.gov no: NCT02256462).