Genes in inflammatory bowel disease: lessons from complex diseases

Prognostic Factors of Biologic Therapy in Pediatric IBD

This was a retrospective cohort study aimed at identifying parameters measured at diagnosis of pediatric IBD to predict subsequent biologic therapy, as an equivalent to an unfavorable clinical course. Identification of predictors of poor outcomes is an important issue in current ECCO guidelines on pIBD. The study population consisted of 119 children with Crohn’s disease and 112 with ulcerative colitis, diagnosed and monitored for at least 1 year from 2009–2019. The population was divided into the study groups separately: 39 children with CD and 14 with UC who received biologics before the age of 18 y compared to 80 with CD and 98 with UC who did not. The combined analysis of 53 biologic therapy recipients vs. 178 non-recipients with IBD was also conducted. Logistic regression tests (OR, RR) and sensitivity, specificity, PPV, and NPV were used. Factors significantly correlated with subsequent biologic therapy were perianal disease, complicated disease behavior, high PCDAI (CD), fatigue, hypoalbuminemia, high PUCAI (UC) and fever, fatigue, hypoalbuminemia, hypoproteinemia, and elevated CRP (IBD). Marginally significant factors were ileocecal disease, elevated serum IgA, anemia, and L4a–L4b coexistence. Apart from parameters already accepted as POPO (B2/3, perianal disease), interesting observations are the significance of IgA, L4a–L4b in CD, and hypoalbuminemia in UC.

The fungal microbiota of de-novo paediatric inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterised by an inappropriate chronic immune response against resident gut microbes. This may be on account of distinct changes in the gut microbiota termed as dysbiosis. The role of fungi in this altered luminal environment has been scarcely reported. We studied the fungal microbiome in de-novo paediatric IBD patients utilising next generation sequencing and compared with adult disease and normal controls. We report a distinct difference in fungal species with Ascomycota predominating in control subjects compared to Basidiomycota dominance in children with IBD, which could be as a result of altered tolerance in these patients.

Intestinal microbiota: The explosive mixture at the origin of inflammatory bowel disease?

Inflammatory bowel diseases (IBDs), namely Crohn’s disease and ulcerative colitis, are lifelong chronic disorders arising from interactions among genetic, immunological and environmental factors. Although the origin of IBDs is closely linked to immune response alterations, which governs most medical decision-making, recent findings suggest that gut microbiota may be involved in IBD pathogenesis. Epidemiologic evidence and several studies have shown that a dysregulation of gut microbiota (i.e., dysbiosis) may trigger the onset of intestinal disorders such as IBDs. Animal and human investigations focusing on the microbiota-IBD relationship have suggested an altered balance of the intestinal microbial population in the active phase of IBD. Rigorous microbiota typing could, therefore, soon become part of a complete phenotypic analysis of IBD patients. Moreover, individual susceptibility and environmental triggers such as nutrition, medications, age or smoking could modify bacterial strains in the bowel habitat. Pharmacological manipulation of bowel microbiota is somewhat controversial. The employment of antibiotics, probiotics, prebiotics and synbiotics has been widely addressed in the literature worldwide, with the aim of obtaining positive results in a number of IBD patient settings, and determining the appropriate timing and modality of this intervention. Recently, novel treatments for IBDs, such as fecal microbiota transplantation, when accepted by patients, have shown promising results. Controlled studies are being designed. In the near future, new therapeutic strategies can be expected, with non-pathogenic or modified food organisms that can be genetically modified to exert anti-inflammatory properties.

Immuno-genomic profiling of patients with inflammatory bowel disease: a systematic review of genetic and functional in vivo studies of implicated genes

BACKGROUND

Over the last 2 decades, there has been an ever-expanding catalog of genetic variants implicated in inflammatory bowel disease (IBD) through genome-wide association studies and next generation sequencing. In this article, we highlight the remarkable developments in understanding the genetic and immunological basis of IBD. The main objective of the study was to perform a systematic review of published literature detailing functional/immunological studies in patients known to harbor genetic variations in the implicated genes.

METHODS

A panel of 71 candidate genes implicated in IBD was prioritized using 5 network connectivity in silico methods. An electronic search using MEDLINE and EMBASE from 1996 to February 2014 for each of the selected genes was conducted. Only studies describing genotyped IBD cohorts with concurrent in vivo functional studies were included.

RESULTS

Between the reviewers, a total of 35,142 potentially eligible publications were identified. Only 8 genes had publications meeting the inclusion criteria. A total of 67 studies were identified across the selected genes. The NOD2 gene had the most number with 41 studies followed by IL-10 with 11 eligible studies. A meta-analysis was not practical given the heterogeneity of the study design and the number of implicated genes with diverse immunological and physiological functions.

CONCLUSIONS

There is a clear lack of functional studies in humans to assess the in vivo impact of the various genetic variants implicated. A collaborative approach merging genomics and functional studies will help to unravel the obscure mechanisms involved in IBD.

The microbiota in inflammatory bowel disease: friend, bystander, and sometime-villain

Ulcerative colitis and Crohn's disease, collectively known as inflammatory bowel disease, represent the heterogeneous outcome of three colliding influences: genetic risk factors, environmental modifiers, and immune effector mechanisms of tissue injury. The nature of these inputs is complex, with each having distinct and overlapping contributions to ulcerative colitis and Crohn's disease. Identification of specific genetic risk factors has improved the understanding of specific pathways to disease, but the primacy of environmental or lifestyle factors linked to changes in the gut microbiota, particularly in early life, is increasingly evident. Clarification of the molecular basis of host-microbe interactions in health and in susceptible individuals promises novel therapeutic strategies.