Mitchell-Riley Syndrome : Improving Clinical Outcomes and Searching for Functional Impact of RFX-6 Mutations

Aims/HypothesisCaused by biallelic mutations of the gene encoding the transcription factor RFX6, the rare Mitchell-Riley syndrome (MRS) comprises neonatal diabetes, pancreatic hypoplasia, gallbladder agenesis or hypoplasia, duodenal atresia, and severe chronic diarrhea. So far, sixteen cases have been reported, all with a poor prognosis. This study discusses the multidisciplinary intensive clinical management of 4 new cases of MRS that survived over the first 2 years of life. Moreover, it demonstrates how the mutations impair the RFX6 function. MethodsClinical records were analyzed and described in detail. The functional impact of two RFX6(R181W) and RFX6(V506G) variants was assessed by measuring their ability to transactivate insulin transcription and genes that encode the L-type calcium channels required for normal pancreatic beta-cell function. ResultsAll four patients were small for gestational age (SGA) and prenatally diagnosed with duodenal atresia. They presented with neonatal diabetes early in life and were treated with intravenous insulin therapy before switching to subcutaneous insulin pump therapy. All patients faced recurrent hypoglycemic episodes, exacerbated when parenteral nutrition (PN) was disconnected. A sensor-augmented insulin pump therapy with a predictive low-glucose suspension system was installed with good results. One patient had a homozygous c.1517T>G (p.Val506Gly) mutation, two patients had a homozygous p.Arg181Trp mutation, and one patient presented with new compound heterozygosity. The RFX6(V506G) and RFX6(R181W) mutations failed to transactivate the expression of insulin and genes that encode L-type calcium channel subunits required for normal pancreatic beta-cell function. Conclusions/InterpretationMultidisciplinary and intensive disease management improved the clinical outcomes in four patients with MRS, including adjustment of parenteral/oral nutrition progression and advanced diabetes technologies. A better understanding of RFX6 function, in both intestine and pancreas cells, may break ground in new therapies, particularly regarding the use of drugs that modulate the enteroendocrine system.Peer reviewe

Functional abdominal pain disorders and patient- and parent- reported outcomes in children with inflammatory bowel disease in remission

BACKGROUND: Chronic abdominal pain occurs frequently in pediatric patients with inflammatory bowel disease (IBD) in remission. AIMS: To assess the prevalence and factors associated with Functional Abdominal Pain Disorders among IBD children in remission (IBD-FAPD). METHODS: Patients with IBD for > 1 year, in clinical remission for ≥ 3 months were recruited from a National IBD network. IBD-FAPDs were assessed using the Rome III questionnaire criteria. Patient- or parent- reported outcomes were assessed. RESULTS: Among 102 included patients, 57 (56%) were boys, mean age (DS) was 15.0 (± 2.0) years and 75 (74%) had Crohn's disease. Twenty-two patients (22%) had at least one Functional Gastrointestinal Disorder among which 17 had at least one IBD-FAPD. Past severity of disease or treatments received and level of remission were not significantly associated with IBD-FAPD. Patients with IBD-FAPD reported more fatigue (peds-FACIT-F: 35.9 ± 9.8 vs. 43.0 ± 6.9, p = 0.01) and a lower HR-QoL (IMPACT III: 76.5 ± 9.6 vs. 81.6 ± 9.2, p = 0.04) than patients without FAPD, and their parents had higher levels of State and Trait anxiety than the other parents. CONCLUSIONS: Prevalence of IBD-FAPD was 17%. IBD-FAPD was not associated with past severity of disease, but with fatigue and lower HR-QoL

Effet anti-inflammatoire du microbiote intestinal (le modèle de la dysbiose au cours de la maladie de Crohn)

L étude du microbiote de patients atteints de MICI a montré l existence d une dysbiose avec diminution des firmicutes et plus particulièrement des Clostridium leptum dont Faecalibacterium prausnitzii. Ce travail de thèse s est centré sur le rôle de cette bactérie sur les voies de l inflammation. Nous avons d abord montré que F. prausnitzii et son surnageant de culture avaient des effets anti-inflammatoires in vitro sur des cellules intestinales polarisées en culture et in vivo sur modèles murins de colite au TNBS. L effet anti-inflammatoire semble lié à des molécules sécrétées par F. prausnitzii bloquant la voie NF-kB. Dans le but de caractériser les molécules bioactives, nous avons ensuite étudié le surnageant de culture de cette bactérie. Une analyse différentielle (surnageant versus milieu de culture) par peptidomique a détecté plusieurs peptides, appartenant tous à une même protéine de 15kDA de fonction inconnue. Un screening de la banque génomique de F. prausnitzii n a pas permis de trouver de clone porteur du gène de la protéine par PCR, mais un test fonctionnel a isolé 100 clones inhibant la voie NF-kB. Le gène de la protéine a été cloné dans différentes souches de Lactococcus lactis et E. coli permettant sa production cytoplasmique en vue d une analyse structure-fonction. Ces premiers travaux ont permis l obtention d outils pour la poursuite du travail. Enfin, nous avons montré que chez les patients atteints de Maladie de Crohn, des modifications du microbiote induites par un traitement nutritionnel (Modulen) pourraient expliquer la rémission clinique et la cicatrisation muqueuse observées. Ces travaux ouvrent des voies de recherche pour de nouvelles thérapeutiques dans les MICI.Inflammatory Bowel diseases are characterised by a dysbiosis. We have shown in this work that Faecalibacterium prausnitzii, a commensal bacteria belonging to the phylum Firmicutes, exerts powerful anti-inflammatory properties both in in vitro models of epithelial cells in culture and in a mouse model of colitis. The anti-inflammatory effect of F. prausnitzii was related to molecules from the culture supernatant, by blocking NF-kB activity. Comparative analysis of the supernatant of F. prausnitzii and its culture medium by mass spectrometry revealed occurrence of peptides in the supernatant. Thoses were all derived from a single protein of approximately 15kD synthesized by F. prausnitzii and whose function and structure are unknown. We hypothesize that the immunomodulatory effect of supernatant of F. prausnitzii observed could be due to those peptides and/or the protein. Its gene was investigated by PCR on genomic library of F.prausnitzii without success. Hundred clones inhibiting the activation of NF-kB from the screening of the library have been pointed out. To obtain the protein, its gene was cloned in different strains of Lactococcus lactis and Escherichia coli. We were able to obtain cytoplasmic production of the protein. Finally, we have shown that nutritional therapy using Modulen IBD induces clinical remission and mucosal healing in CD patients by modifying the composition of the gut microbiota through expansion of mucolytic bacteria. These works provide a better understanding of the anti-inflammatory effect of F. prausnitzii and allow considering using this bacteria, this protein or nutritional tools as a therapeutic agent in IBD.PARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

Efficacy of exclusive nutritional therapy in pediatric Crohn's disease comparing fractionated oral versus continuous enteral feeding

International audienceBackground: Nutritional therapy has an established role as induction therapy in paediatric Crohn's disease (CD). However, compliance is the main difficulty and may be greatly influenced by the administration route. Aim: To analyse efficiency of exclusive nutrition to induce remission in children with CD comparing fractionated oral versus continuous enteral feeding. Methods: The medical records of 106 patients treated by exclusive nutritional therapy (Modulen IBD®) by either oral or continuous enteral route were reviewed retrospectively. Comparative analyses of remission rates, changes in anthropometry, Paediatric CD Activity Index (PCDAI), laboratory indices and compliance rates were performed. Results: On exclusive enteral nutrition, at 8 weeks, 34/45 patients achieved remission in the oral group (75% on intention-to-treat analysis) and 52/61 (85%) in the enteral nutrition group (P=0.157). All patients showed a significant decrease in disease severity assessed by PCDAI (P<0.0001) and significant improvements in anthropometric measures and inflammatory indices. No difference was observed whether Modulen IBD® was administered orally or by continuous enteral feeding, apart from weight gain which was greater in the enteral group (P=0.041). In a subgroup of patients mucosal healing was evidenced on follow-up endoscopies showing a clear correlation to remission. Compliance rates (87 and 90%) were similar. Nevertheless, non-compliant patients had lower mucosal healing and remission rates. Conclusions: These retrospective data suggest that the use of fractionated oral nutritional therapy might be as efficacious as continuous enteral administration to induce remission and mucosal healing in children with CD. However, appropriate prospective clinical trials are needed to confirm these findings