B Lymphocytes Contribute to Celiac Disease Pathogenesis.
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ABSTRACT:
SUBMITTER: Lejeune T
PROVIDER: S-EPMC8647930 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BACKGROUND AND AIM: Potential celiacs have the 'celiac type' HLA, positive anti-transglutaminase antibodies but no damage at small intestinal mucosa. Only a minority of them develops mucosal lesion. More than 40 genes were associated to Celiac Disease (CD) but we still do not know how those pathways transform a genetically predisposed individual into an affected person. The aim of the study is to explore the genetic features of Potential CD individuals. METHODS: 127 'potential' CD patients entered the study because of positive anti-tissue transglutaminase and no mucosal lesions; about 30% of those followed for four years become frankly celiac. They were genotyped for 13 polymorphisms of 'candidate genes' and compared to controls and celiacs. Moreover, 60 biopsy specimens were used for expression studies. RESULTS: Potential CD bear a lighter HLA-related risk, compared to celiac (?(2)?=?48.42; p value?=?1×10(-8)). They share most of the polymorphisms of the celiacs, but the frequency of c-REL* G allele was suggestive for a difference compared to celiac (?(2)?=?5.42; p value?=?0.02). One marker of the KIAA1109/IL-2/IL-21 candidate region differentiated potentials from celiac (rs4374642: ?2?=?7.17, p value?=?0.01). The expression of IL-21 was completely suppressed in potentials compared to celiacs (p value?=?0.02) and to controls (p value?=?0.02), in contrast IL-2, KIAA1109 and c-REL expression were over-expressed. CONCLUSIONS: Potential CD show genetic features slightly different from celiacs. Genetic and expression markers help to differentiate this condition. Potential CD is a precious biological model of the pathways leading to the small intestinal mucosal damage in genetically predisposed individuals.
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Project description:A number of lines of evidence suggest that transglutaminase 2 (TG2) may be one of the earliest disease-relevant proteins to encounter immunotoxic gluten in the celiac gut. These and other investigations also suggest that the reaction catalyzed by TG2 on dietary gluten peptides is essential for the pathogenesis of celiac disease. If so, several questions are of critical significance. How is TG2 activated in the celiac gut? What are the disease-specific and general consequences of activating TG2? Can local inhibition of TG2 in the celiac intestine suppress gluten induced pathogenesis in a dose-responsive manner? And what are the long-term consequences of suppressing TG2 activity in the small intestinal mucosa? Answers to these questions will depend upon the development of judicious models and chemical tools. They also have the potential of yielding powerful next-generation drug candidates for treating this widespread but overlooked chronic disease.
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Project description:Celiac disease (CD) is associated with intestinal dysbiosis, which can theoretically lead to dysfunctions in host-microbe interactions and contribute to the disease. In the present study, possible differences in Bacteroides spp. and their pathogenic features between CD patients and controls were investigated. Bacteroides clones (n = 274) were isolated, identified, and screened for the presence of the virulence genes (bft and mpII) coding for metalloproteases. The proteolytic activity of selected Bacteroides fragilis strains was evaluated by zymography and, after gastrointestinal digestion of gliadin, by high-pressure liquid chromatography/electrospray ionization/tandem mass spectrometry. The effects of B. fragilis strains on Caco-2 cell culture permeability and inflammatory response to digested gliadin were determined. B. fragilis was more frequently identified in CD patients than in healthy controls, in contrast to Bacteroides ovatus. B. fragilis clones carrying virulence genes coding for metalloproteases were more abundant in CD patients than in controls. B. fragilis strains, representing the isolated clones and carrying metalloprotease genes, showed gelatinase activity and exerted the strongest adverse effects on the integrity of the Caco-2 cell monolayer. All B. fragilis strains also showed gliadin-hydrolyzing activity, and some of them generated immunogenic peptides that preserved or increased inflammatory cytokine production (tumor necrosis factor alpha) and showed increased ability to permeate through Caco-2 cell cultures. These findings suggest that increased abundance of B. fragilis strains with metalloprotease activities could play a role in CD pathogenesis, although further in vivo studies are required to support this hypothesis.
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Project description:Interaction analysis of GWAS can detect signal that would be ignored by single variant analysis, yet few robust interactions in humans have been detected. Recent work has highlighted interactions in the MHC region between known HLA risk haplotypes for various autoimmune diseases. To better understand the genetic interactions underlying celiac disease (CD), we have conducted exhaustive genome-wide scans for pairwise interactions in five independent CD case-control studies, using a rapid model-free approach to examine over 500 billion SNP pairs in total. We found 14 independent interaction signals within the MHC region that achieved stringent replication criteria across multiple studies and were independent of known CD risk HLA haplotypes. The strongest independent CD interaction signal corresponded to genes in the HLA class III region, in particular PRRC2A and GPANK1/C6orf47, which are known to contain variants for non-Hodgkin's lymphoma and early menopause, co-morbidities of celiac disease. Replicable evidence for statistical interaction outside the MHC was not observed. Both within and between European populations, we observed striking consistency of two-locus models and model distribution. Within the UK population, models of CD based on both interactions and additive single-SNP effects increased explained CD variance by approximately 1% over those of single SNPs. The interactions signal detected across the five cohorts indicates the presence of novel associations in the MHC region that cannot be detected using additive models. Our findings have implications for the determination of genetic architecture and, by extension, the use of human genetics for validation of therapeutic targets.
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Project description:Our understanding of celiac disease and how it develops has evolved significantly over the last half century. Although traditionally viewed as a pediatric illness characterized by malabsorption, it is now better seen as an immune illness with systemic manifestations affecting all ages. Population studies reveal this global disease is common and, in many countries, increasing in prevalence. These studies underscore the importance of specific HLA susceptibility genes and gluten consumption in disease development and suggest that other genetic and environmental factors could also play a role. The emerging data on viral and bacterial microbe-host interactions and their alterations in celiac disease provides a plausible mechanism linking environmental risk and disease development. Although the inflammatory lesion of celiac disease is complex, the strong HLA association highlights a central role for pathogenic T cells responding to select gluten peptides that have now been defined for the most common genetic form of celiac disease. What remains less understood is how loss of tolerance to gluten occurs. New insights into celiac disease are now providing opportunities to intervene in its development, course, diagnosis, and treatment.
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Project description:Background & aimsThe early steps in the pathophysiology of celiac disease (CD) leading to loss of tolerance to gluten are poorly described. Our aim was to use RNA sequencing of duodenal biopsies in patients with active CD, CD in remission, and non-CD controls to gain insight into CD pathophysiology, identify additional genetic signatures linked to CD, and possibly uncover targets for future therapeutic agents.MethodsWe performed whole transcriptome shotgun sequencing of intestinal biopsies in subjects with active and remission CD and non-CD controls. We also performed functional pathway analysis of differentially expressed genes to identify statistically significant pathways that are up or down regulated in subjects with active CD compared to remission CD.ResultsWe identified the upregulation of novel genes including IL12R, ITGAM and IGSF4 involved in the immune response machinery and cell adhesion process in the mucosa of subjects with active CD compared to those in remission. We identified a unique signature of genes, related to innate immunity, perturbed exclusively in CD irrespective of disease status. Finally, we highlight novel pathways of interest that may contribute to the early steps of CD pathogenesis and its comorbidities such as the spliceosome, pathways related to the innate immune response, and pathways related to autoimmunity.ConclusionsOur study confirmed previous findings based on GWAS and immunological studies pertinent to CD pathogenesis and describes novel genes and pathways that with further validation may be found to contribute to the early steps in the pathogenesis of CD, ongoing inflammation, and comorbidities associated with CD.
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