Intestinal stroma guides monocyte differentiation to macrophages through GM-CSF.

Stromal cells support epithelial cell and immune cell homeostasis and play an important role in inflammatory bowel disease (IBD) pathogenesis. Here, we quantify the stromal response to inflammation in pediatric IBD and reveal subset-specific inflammatory responses across colon segments and intestinal layers. Using data from a murine dynamic gut injury model and human ex vivo transcriptomic, protein and spatial analyses, we report that PDGFRA+CD142-/low fibroblasts and monocytes/macrophages co-localize in the intestine. In primary human fibroblast-monocyte co-cultures, intestinal PDGFRA+CD142-/low fibroblasts foster monocyte transition to CCR2+CD206+ macrophages through granulocyte-macrophage colony-stimulating factor (GM-CSF). Monocyte-derived CCR2+CD206+ cells from co-cultures have a phenotype similar to intestinal CCR2+CD206+ macrophages from newly diagnosed pediatric IBD patients, with high levels of PD-L1 and low levels of GM-CSF receptor. The study describes subset-specific changes in stromal responses to inflammation and suggests that the intestinal stroma guides intestinal macrophage differentiation.

Clinical Features and Natural History of Paediatric Patients with Ulcerative Proctitis: A Multicentre Study from the Paediatric IBD Porto Group of ESPGHAN.

BACKGROUND AND AIMS: Ulcerative proctitis [UP] is an uncommon presentation in paediatric patients with ulcerative colitis. We aimed to characterize the clinical features and natural history of UP in children, and to identify predictors of poor outcomes. METHODS: This was a retrospective study involving 37 sites affiliated with the IBD Porto Group of ESPGHAN. Data were collected from patients aged <18 years diagnosed with UP between January 1, 2016 and December 31, 2020. RESULTS: We identified 196 patients with UP (median age at diagnosis 14.6 years [interquartile range, IQR 12.5-16.0]), with a median follow-up of 2.7 years [IQR 1.7-3.8]. The most common presenting symptoms were bloody stools [95%], abdominal pain [61%] and diarrhoea [47%]. At diagnosis, the median paediatric ulcerative colitis activity index [PUCAI] score was 25 [IQR 20-35], but most patients exhibited moderate-severe endoscopic inflammation. By the end of induction, 5-aminosalicylic acid administration orally, topically or both resulted in clinical remission rates of 48%, 48%, and 73%, respectively. The rates of treatment escalation to biologics at 1, 3, and 5 years were 10%, 22%, and 43%, respectively. In multivariate analysis, the PUCAI score at diagnosis was significantly associated with initiation of systemic steroids, or biologics, and subsequent acute severe colitis events and inflammatory bowel disease-associated admission, with a score ≥35 providing an increased risk for poor outcomes. By the end of follow-up, 3.1% of patients underwent colectomy. Patients with UP that experienced proximal disease progression during follow-up [48%] had significantly higher rates of a caecal patch at diagnosis and higher PUCAI score by the end of induction, compared to those without progression. CONCLUSION: Paediatric patients with UP exhibit high rates of treatment escalation and proximal disease extension.

The single-cell transcriptional landscape of innate and adaptive lymphocytes in pediatric-onset colitis.

Innate lymphoid cells (ILCs) are considered innate counterparts of adaptive T cells; however, their common and unique transcriptional signatures in pediatric inflammatory bowel disease (pIBD) are largely unknown. Here, we report a dysregulated colonic ILC composition in pIBD colitis that correlates with inflammatory activity, including accumulation of naive-like CD45RA+CD62L- ILCs. Weighted gene co-expression network analysis (WGCNA) reveals modules of genes that are shared or unique across innate and adaptive lymphocytes. Shared modules include genes associated with activation/tissue residency, naivety/quiescence, and antigen presentation. Lastly, nearest-neighbor-based analysis facilitates the identification of "most inflamed" and "least inflamed" lymphocytes in pIBD colon with unique transcriptional signatures. Our study reveals shared and unique transcriptional signatures of colonic ILCs and T cells in pIBD. We also provide insight into the transcriptional regulation of colonic inflammation, deepening our understanding of the potential mechanisms involved in pIBD.

Safety and Potential Efficacy of Escalating Dose of Ustekinumab in Pediatric Crohn Disease (the Speed-up Study): A Multicenter Study from the Pediatric IBD Porto Group of ESPGHAN.

OBJECTIVES: Escalation of the ustekinumab (UST) maintenance dosage was effective in adults with Crohn disease (CD), but no data are available for children. We evaluated the effectiveness and safety of dose escalation of UST in pediatric CD. METHODS: This was a retrospective multicenter study from 25 centers affiliated with the IBD Interest and Porto groups of ESPGHAN. We included children with CD who initiated UST at a standard dosing and underwent either dose escalation to intervals shorter than 8 weeks or re-induction of UST due to active disease. Demographic, clinical, laboratory, endoscopic, imaging, and safety data were collected up to 12 months of follow-up. RESULTS: Sixty-nine children were included (median age 15.8 years, interquartile range 13.8-16.9) with median disease duration of 4.3 years (2.9-6.3). Most children were biologic (98.6%)- and immunomodulator (86.8%)- experienced. Clinical response and remission were observed at 3 months after UST escalation in 46 (67%) and 29 (42%) children, respectively. The strongest predictor for clinical remission was lower weighted Pediatric Crohn Disease Activity Index (wPCDAI) at escalation ( P = 0.001). The median C-reactive protein level decreased from 14 (3-28.03) to 5 (1.1-20.5) mg/L ( P = 0.012), and the fecal calprotectin level from 1100 (500-2300) to 515 (250-1469) µg/g ( P = 0.012) 3 months post-escalation. Endoscopic and transmural healing were achieved in 3 of 19 (16%) and 2 of 15 (13%) patients, respectively. Thirteen patients (18.8%) discontinued therapy due to active disease. No serious adverse events were reported. CONCLUSIONS: Two-thirds of children with active CD responded to dose escalation of UST. Milder disease activity may predict a favorable outcome following UST dose escalation.

Exclusive Enteral Nutrition: Clinical Effects and Changes in Mucosal Cytokine Profile in Pediatric New Inflammatory Bowel Disease.

Exclusive Enteral Nutrition (EEN) is the first-line treatment in children with Crohn's disease (CD) for induction of remission. However, the mode of action remains conjectural. The aim of this study was to investigate whether the effect of EEN is paralleled by changes in the mucosal cytokine profiles (MCP). Twelve children with new onset inflammatory bowel disease (IBD) received induction treatment with a polymeric EEN. We assessed clinical, endoscopic and histologic scoring before and after EEN. Twelve colonic cytokines were analyzed by Polymerase Chain Reaction (PCR) in six of the IBD patients at onset and after EEN as well as in six non-IBD control children at the diagnostic colonoscopy. Twelve children completed 6 weeks of EEN, except from one child who completed 4 weeks. At the control colonoscopy, 83% were in complete clinical remission. Changes were found in the MCPs of individual patients after EEN. In particular, children with IBD showed significantly higher values of Interleukin (IL)-12ß (p = 0.008) and IL-23α (p = 0.02) compared to non-IBD controls at the diagnostic colonoscopy. Furthermore, an overall change in proinflammatory cytokines was noted in the IBD-group after treatment. Further studies are warranted to understand the role of EEN in MCP.

Granulocyte and Monocyte Apheresis for Induction of Remission in Children With New-Onset Inflammatory Bowel Colitis.

OBJECTIVE: The aim of the study was to analyze the effect of granulocyte and monocyte apheresis (GMA) with mesalazine for induction of remission in pediatric patients with newly onset chronic inflammatory bowel disease (IBD) colitis. METHODS: Thirteen pediatric patients with newly onset extensive IBD colitis were investigated per the ECCO/ESPGHAN IBD protocol. Of these 13, 12 received 10 treatments with Adacolumn (ADA) during a median of 6.25 weeks in combination with low-to-moderate doses of mesalazine, which was continued after apheresis. A control colonoscopy was performed 12 to 16 weeks after GMA treatment. Primary outcomes were mucosal healing (Mayo endoscopic score) and histopathologic grading of biopsies. A secondary outcome was disease activity as measured by the Pediatric Ulcerative Colitis Activity Index. RESULTS: Twelve children (6 girls) with a median age of 14.6 years and a median duration of symptoms at diagnosis of 3.2 months received all planned 10 treatment sessions with ADA. Ten of 12 patients had pancolitis and 2 of 12 extensive colitis. A final diagnosis, however, indicated ulcerative colitis in 10 children and Crohn disease in 2 children. At control colonoscopy, 8 of 12 children were in clinical remission and the Mayo endoscopic score showed significant improvement in 9 of 12 patients (P = 0.006). Complete microscopic remission, according to the Geboes score, was observed in 2 patients. CONCLUSIONS: In this small study GMA for induction of remission of newly onset pediatric IBD colitis was effective in 8 of 12 patients. Further controlled studies are warranted to confirm the efficacy of this treatment model.

Mucosal Cytokine Profiles After Induction Therapy With Granulocyte/Monocyte Apheresis in New-onset Inflammatory Colitis.

Granulocyte/monocyte apheresis (GMA) selectively removes circulating granulocytes and monocytes; important producers of proinflammatory cytokines. Seven children with new-onset inflammatory bowel disease (IBD) colitis were treated with GMA together with mesalazine, and had significant decreases in Pediatric UC Activity Index (P = 0.018) and Mayo endoscopic score (P = 0.013). We investigated the colonic mucosal cytokine profiles (analyzed with real-time polymerase chain reaction), before and after induction treatment, and in 6 non-IBD controls. Significant decreases were seen in Colony Stimulating Factor 2 (P = 0.018), tumor necrosis factor-α (P = 0.028), interleukin (IL)-23α (P = 0.043), IL-1ß (P = 0.028), IL-36γ (P = 0.018), IL-10 (P = 0.028), and transforming growth factor beta 1 (P = 0.043) after treatment. In 6 non-IBD controls there were significantly lower levels of IL-12ß (P = 0.023) and IL-23α (P = 0.046) compared to the patients with IBD at onset, and IL-22 (P = 0.088) and IL-36γ (P = 0.062) showed lower values without reaching significant differences. We speculate that the decreases in colonic mucosal cytokine profiles after treatment may explain the observed clinical efficacy in the GMA-treated children with IBD.

Serum-Infliximab Trough Levels in 45 Children with Inflammatory Bowel Disease on Maintenance Treatment.

The role of trough serum infliximab (s-IFX) and antibodies toward IFX (ATI) during maintenance treatment remains unclear in children. The aim of the present study was to investigate trough s-IFX and ATI to identify any correlation with inflammatory activity and clinical response in a pediatric inflammatory bowel disease (IBD) cohort. We investigated the s-IFX trough levels in pediatric IBD patients (n = 45) on maintenance IFX treatment. Ninety-three blood samples were collected and demographics, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and albumin were recorded. The mean s-IFX trough level was 5.2 µg/mL. The mean trough s-IFX level was significantly higher in the samples taken during remission (7.2 µg/mL) compared to active disease (4.5 µg/mL, p < 0.05). The trough s-IFX levels correlated with ESR, CRP, and albumin. S-IFX was undetectable in eight of the patients, all with positive ATI and active disease. Surprisingly, clinical and biochemical remission was observed at only 26 of the 93 visits. The correlation between dose variations and changes in trough s-IFX was not evident. In line with studies in adults, the s-IFX trough levels correlated with response to infliximab.