Exploration of the Activity of DNA Located Outside of Cellular Nucleus to Amplify Inflammation in Inflammatory Bowel Disease in Children Through Biological Pathway Cyclic GMP-AMP Synthase (cGAS) - Stimulator of Interferon Genes (STING)

Centre Hospitalier Régional d'Orléans40 enrolled

Overview

Frequency of Inflammatory Bowel Diseases in children (IBD)-Crohn's disease (CD), Ulcerative colitis (UC) is constantly increasing. Pediatric-onset IBD represent a different nosological entity (from adult IBD) because of their major inflammatory activity, their significant anatomical extent and their stenotic and/or fistulizing character sometimes from diagnosis. Intestinal lesions are due to dysregulation of the intestinal immune system but the cause is unknown. The investigators hypothesize that extranuclear DNA participates in the amplification of the inflammatory response at the intestinal and blood levels during pediatric IBD through the cGAS-STING pathway. The investigators will analyse blood and fecal samples, and colonic biopsies issued from ill children and control participants on age of 6 to 17 years. The investigators think that this study will provide a better understanding of the mechanisms involved in pediatric IBD, assess the place of the cGAS-STING pathway, identify potential biomarkers of pediatric IBD and new potential therapeutic targets based in particular on the inhibition of the cGAS-STING pathway.

Inflammatory Bowel Diseases in children (IBD)-Crohn's disease (CD), ulcerative colitis (UC) are severe pathology that can affect the entire digestive tract. Their annual incidence is however constantly increasing. IBD are complex multifactorial pathologies whose cause is still unknown today. IBD occurs on a predisposing genetic background in the presence of exogenous factors and alteration of the intestinal microbiota. Intestinal lesions are due to dysregulation of the intestinal immune system with increased secretion of pro-inflammatory cytokines at the expense of anti-inflammatory cytokines. Pediatric-onset IBD represent a different nosological entity (from adult IBD) because of their major inflammatory activity, their significant anatomical extent and their stenotic and/or fistulizing character sometimes from diagnosis. Their impact is not only individual (growth retardation, puberty delay, psychological disorders) but also family/parental, school and social. These particularities justify that biomedical research focuses on it in a more specific way. Extracellular and extranuclear DNA (enDNA) play a major role in innate immunity by stimulating pro-inflammatory responses and activating type I interferon production. The pro-inflammatory action of enDNA is mediated by enzyme cGAS, protein STING, toll-like receptor 9 (TLR9), and the inflammasome complex NLRP3. The investigators hypothesize that enDNA participates in the amplification of the inflammatory response at the intestinal and blood levels during pediatric IBD through the cGAS-STING pathway. They also hypothesize that there are links between the cGAS-STING pathway and other pathways involved in pediatric IBD such as NOD2 and Autophagy. The investigators will analyse blood and fecal samples, and colonic biopsies issued from ill children and controls on age of 6 to 17 years. The investigators think that this study will provide a better understanding of the mechanisms involved in pediatric IBD, assess the place of the cGAS-STING pathway, identify potential biomarkers of pediatric IBD and new potential therapeutic targets based in particular on the inhibition of the cGAS-STING pathway.

Eligibility

Sex: ALLMin age: 6 YearsMax age: 17 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Participants aged from 6 years inclusive to 17 years inclusive * Boys and girls * Presenting an IBD or suspicion of IBD * Requiring a colonoscopy for diagnosis or follow-up or other reason (abdominal pain, diarrhoea, rectal bleeding, weight loss) not confirming the diagnosis of Crohn's disease or Ulcerative Colitis * Active IBD if: * CD: PCDAI score \>5 and CRP\>20mg/L and faecal calprotectin\> 400 µg/g * UC: PUCAI score\>10 and faecal calprotectin\>250 µg/g * IBD in remission if: * CD: PCDAI score\<5 and CRP\<20mg/L and faecal calprotectin\<400 µg/g * UC: PUCAI score \<10 and faecal calprotectin \< 250 µg/g * Patients and their parents who gave their consent to participate in the study Exclusion Criteria: * Refusal of the participant and/or one of his two parents * Body weight less than or equal to 20 kg * Blood hemoglobin level less than or equal to 9 g/dl * Refusal or contraindication to general anesthesia * Co-existing severe chronic pathology and/or treatment that could interfere with the results of the study; example: trisomy 21, treatment with growth hormone etc. * Protected person (under guardianship or curatorship) * Person under legal protection * Person not affiliated to a social security scheme * Pregnant or breastfeeding woman

Outcomes

Primary Outcomes

Amount of mRNA specific for colonic cGAS

the comparison, between the 3 groups of patients, of the quantity of specific mRNA of colonic cGAS expressed as the number of "reads" during RNA sequencing (RNAseq), by a Mann-Whitney U test. It is planned from the outset to compare the groups 2 by 2, regardless of the result of an overall test such as a Kruskal-Wallis test.

Time frame: Baseline

Secondary Outcomes

quantitative difference of amount of circulating mtDNA

to find quantitative differences between the 3 groups concerning the circulating mtDNA, the circulating total DNA, by the qPCR technique: by specific primer sequences to identify the origin of the DNA (mitochondrial or nuclear). Results will be expressed by the -2∆∆Ct method ("fold increase") compared to the control.

Time frame: Baseline

Cytokine response

to find quantitative differences between the 3 groups concerning the cytokine response by Luminex®: in pg/ml or in ng/ml depending on the cytokines

Time frame: Baseline

inflammatory / dysimmune response of cytokines

to find quantitative differences between the 3 groups concerning the inflammatory / dysimmune response of cytokines, components of the cGAS-STING pathways autophagy, NOD2, intestinal mucins, integrins, cadherins by RNAseq type transcriptomic analysis in Transcript Per Million (TPM). This outcome wil be mesured at the blood level abd the colonic level.

Time frame: Baseline

Difference of DNA methylation by Methyl-Seq between the 3 groups

to find quantitative differences between the 3 groups concerning the study of DNA methylation by Methyl-Seq. Results expessed in pourcentage of methylation. This outcome will be mesured at the bllod level and the colonic level.

Time frame: Baseline

Activation (phosphorylation) of the components of the cGAS-STING pathway

Activation (phosphorylation) of the components of the cGAS-STING pathway (proteins cGAS, p-CGAS, STING,p-STING,TBK1, p-TBK1,IRF-3, p-IRF-3) by Western-Blot

Time frame: Baseline

plasma DNase activity

plasma DNase activity in Kunitz unitz

Time frame: baseline

differences in microbial distribution

search for quantitative differences in microbial distribution between the 3 groups by pyrosequencing RNA 16s of the microbiota at the fecal level

Time frame: Baseline

quantity (number of "reads") of colonic STING-specific mRNA

quantitative differences between the 3 groups concerning the quantity (number of "reads") of colonic STING-specific mRNA at the colonic level

Time frame: Baseline

extracellular DNA by qPCR

We will use specific primer sequences to identify the origin of the DNA (mitochondrial or nuclear). Results will be expressed by the -2∆∆Ct method ("fold increase") compared to the control. This outcome will be mesured at the colonic level.

Time frame: Baseline

Amount of STING in the cytoplasm

cytoplasmic presence of STING by histology, immunohistochemical staining and optical microscopy analysis. Results will be qualitative (present/absent; localization) and quantitative based on optical density (pourcentage of positive cells)

Time frame: Baseline

Amount of cGAS in the cytoplasm

cytoplasmic presence of cGAS by histology, immunohistochemical staining and optical microscopy analysis. Results will be qualitative (present/absent; localization) and quantitative based on optical density (pourcentage of positive cells)

Time frame: Baseline

Amount of nuclear DNA in teh cytoplasm

cytoplasmic presence of nuclear DNA by histology, immunohistochemical staining and optical microscopy analysis. Results will be qualitative (present/absent; localization) and quantitative based on optical density (pourcentage of positive cells)

Time frame: Baseline

Amount of mitochondrial DNA in the cytoplasm

cytoplasmic presence of mitochondrial DNA by histology, immunohistochemical staining and optical microscopy analysis. Results will be qualitative (present/absent; localization) and quantitative based on optical density (pourcentage of positive cells)

Time frame: Baseline

Amount of colonic DNase activity

Measurement of colonic DNase activity in Kunitz unitz

Time frame: Baseline

Exploration of the Activity of DNA Located Outside of Cellular Nucleus to Amplify Inflammation in Inflammatory Bowel Disease in Children Through Biological Pathway Cyclic GMP-AMP Synthase (cGAS) - Stimulator of Interferon Genes (STING)

Overview

Conditions

Interventions

Eligibility

Locations (1)

Outcomes

Primary Outcomes

Secondary Outcomes