• Germline gain-of-function mutations in STAT3 lead to lymphoproliferation and autoimmunity with prominent cytopenias.• Mutations in STAT3 cause altered regulatory T cells and cytokine signaling.Germline loss-of-function mutations in the transcription factor signal transducer and activator of transcription 3 (STAT3) cause immunodeficiency, whereas somatic gain-offunction mutations in STAT3 are associated with large granular lymphocytic leukemic, myelodysplastic syndrome, and aplastic anemia. Recently, germline mutations in STAT3 have also been associated with autoimmune disease. Here, we report on 13 individuals from 10 families with lymphoproliferation and early-onset solid-organ autoimmunity associated with 9 different germline heterozygous mutations in STAT3. Patients exhibited a variety of clinical features, with most having lymphadenopathy, autoimmune cytopenias, multiorgan autoimmunity (lung, gastrointestinal, hepatic, and/or endocrine dysfunction), infections, and short stature. Functional analyses demonstrate that these mutations confer a gain-of-function in STAT3 leading to secondary defects in STAT5 and STAT1 phosphorylation and the regulatory T-cell compartment. Treatment targeting a cytokine pathway that signals through STAT3 led to clinical improvement in 1 patient, suggesting a potential therapeutic option for such patients. These results suggest that there is a broad range of autoimmunity caused by germline STAT3 gain-of-function mutations, and that hematologic autoimmunity is a major component of this newly described disorder. Some patients for this study were enrolled in a trial registered at www.clinicaltrials.gov as #NCT00001350. (Blood. 2015;125(4):591-599)

The results indicate a marked rise in the incidence of CD in contrast to no increase in UC in South-Eastern Norway, compared with the figures from the last 15 years. Time from onset of symptoms to diagnosis still represents a challenge for early characterization in IBD.

In UC, both biochemical and fecal markers are related to disease activity and extent of disease, whereas in CD, the fecal calprotectin concentration is a reliable marker of mucosal affection, but not for systemic disease activity.

PurposeImbalance in the microbiota, dysbiosis, has been identified in inflammatory bowel disease (IBD). We explored the fecal microbiota in pediatric patients with treatment-naïve IBD, non-IBD patients with gastrointestinal symptoms and healthy children, its relation to IBD subgroups, and treatment outcomes.Patients and methodsFecal samples were collected from 235 children below 18 years of age. Eighty children had Crohn’s disease (CD), 27 ulcerative colitis (UC), 3 IBD unclassified, 50 were non-IBD symptomatic patients, and 75 were healthy. The bacterial abundance of 54 predefined DNA markers was measured with a 16S rRNA DNA-based test using GA-Map™ technology at diagnosis and after therapy in IBD patients.ResultsBacterial abundance was similarly reduced in IBD and non-IBD patients in 51 of 54 markers compared to healthy patients (P<0.001). Only Prevotella was more abundant in patients (P<0.01). IBD patients with ileocolitis or total colitis had more Ruminococcus gnavus (P=0.02) than patients with colonic CD or left-sided UC. CD patients with upper gastrointestinal manifestations had higher Veillonella abundance (P<0.01). IBD patients (58%) who received biologic therapy had lower baseline Firmicutes and Mycoplasma hominis abundance (P<0.01) than conventionally treated. High Proteobacteria abundance was associated with stricturing/penetrating CD, surgery (P<0.01), and nonmucosal healing (P<0.03). Low Faecalibacterium prausnitzii abundance was associated with prior antibiotic therapy (P=0.001), surgery (P=0.02), and nonmucosal healing (P<0.03). After therapy, IBD patients had unchanged dysbiosis.ConclusionFecal microbiota profiles differentiated IBD and non-IBD symptomatic children from healthy children, but displayed similar dysbiosis in IBD and non-IBD symptomatic patients. Pretreatment fecal microbiota profiles may be of prognostic value and aid in treatment individualization in pediatric IBD as severe dysbiosis was associated with an extensive, complicated phenotype, biologic therapy, and nonmucosal healing. The dysbiosis persisted after therapy, regardless of treatments and mucosal healing.

The purpose of this study was to assess the sensitivity, specificity, and diagnostic accuracy of magnetic resonance imaging (MRI) in pediatric patients with clinical suspicion of inflammatory bowel disease (IBD) by comparing MRI and ultrasound (US) to endoscopy, the gold standard. A median volume of 300 ml of mannitol in a 15% [corrected] watery solution were ingested by 43 children prior to examination. The 53 MRI examinations were compared with 20 endoscopies and 41 US of the terminal ileum. The outcomes were MRI quality; pathologic findings; level of adverse events; and concordance between endoscopy, MRI, and US estimated by kappa statistics. The ileum and terminal ileum were very good or excellently imaged in approximately 80% of cases. Wall thickening and enhancement were most frequent in the terminal ileum. MRI compared with endoscopy had a sensitivity of 81.8% [95% confidence interval (CI)], specificity of 100%, diagnostic accuracy of 90%, and kappa value of 0.80 (95% CI), indicating a good degree of concordance. A similar degree of concordance was achieved between US and endoscopy. In spite of the frequent adverse reactions, such as diarrhea and nausea, half of the patients were prepared to repeat the examination. The results of MRI are concordant with endoscopy and US of the terminal ileum.