A review of major Crohn’s disease susceptibility genes and their role in disease pathogenesis

Biologic Therapy in Crohn's Disease-What We Have Learnt So Far

Crohn's disease (CD) is an autoimmune disorder from the group of inflammatory bowel diseases. The etiology of CD is not clear; currently, the interaction between the genetic, immunological and environmental factors is assumed as the cause of the disease. Partial knowledge of those factors has led to the development of drugs, which control the clinical symptoms and improve the overall condition of the infected; the main objective of the modern therapeutic strategies is the induction and maintenance of remission. Among the wide range of available treatments, older generation molecules: mesalazine, corticosteroids and thiopurine derivatives as well as biological drugs and biosimilars can be distinguished. Moreover, some novel biologics and small molecule drugs have shown potential in CD clinical trials, providing safe and effective results. This article provides an overview of the achievements in the field of biologic therapy, its efficacy and safety with an indication of future directions in CD treatment.

MAGMA: generalized gene-set analysis of GWAS data

By aggregating data for complex traits in a biologically meaningful way, gene and gene-set analysis constitute a valuable addition to single-marker analysis. However, although various methods for gene and gene-set analysis currently exist, they generally suffer from a number of issues. Statistical power for most methods is strongly affected by linkage disequilibrium between markers, multi-marker associations are often hard to detect, and the reliance on permutation to compute p-values tends to make the analysis computationally very expensive. To address these issues we have developed MAGMA, a novel tool for gene and gene-set analysis. The gene analysis is based on a multiple regression model, to provide better statistical performance. The gene-set analysis is built as a separate layer around the gene analysis for additional flexibility. This gene-set analysis also uses a regression structure to allow generalization to analysis of continuous properties of genes and simultaneous analysis of multiple gene sets and other gene properties. Simulations and an analysis of Crohn’s Disease data are used to evaluate the performance of MAGMA and to compare it to a number of other gene and gene-set analysis tools. The results show that MAGMA has significantly more power than other tools for both the gene and the gene-set analysis, identifying more genes and gene sets associated with Crohn’s Disease while maintaining a correct type 1 error rate. Moreover, the MAGMA analysis of the Crohn’s Disease data was found to be considerably faster as well.

Gene and gene-set analysis are statistical methods for analysing multiple genetic markers simultaneously to determine their joint effect. These methods can be used when the effects of individual markers is too weak to detect, which is a common problem when studying polygenic traits. Moreover, gene-set analysis can provide additional insight into functional and biological mechanisms underlying the genetic component of a trait. Although a number of methods for gene and gene-set analysis are available however, they generally suffer from various statistical issues and can be very time-consuming to run. We have therefore developed a new method called MAGMA to address these issues, and have compared it to a number of existing tools. Our results show that MAGMA detects more associated genes and gene-sets than other methods, and is also considerably faster. The way the method is set up also makes it highly flexible. This makes it suitable as a basis for more general statistical analyses aimed at investigating more complex research questions.

Bovine immunoglobulin protein isolates for the nutritional management of enteropathy

The gastrointestinal tract is responsible for a multitude of digestive and immune functions which depend upon the balanced interaction of the intestinal microbiota, diet, gut barrier function, and mucosal immune response. Disruptions in one or more of these factors can lead to intestinal disorders or enteropathies which are characterized by intestinal inflammation, increased gut permeability, and reduced capacity to absorb nutrients. Enteropathy is frequently associated with human immunodeficiency virus (HIV) infection, inflammatory bowel disease, autoimmune enteropathy, radiation enteritis, and irritable bowel syndrome (IBS), where pathologic changes in the intestinal tract lead to abdominal discomfort, bloating, abnormal bowel function (e.g., diarrhea, urgency, constipation and malabsorption). Unfortunately, effective therapies for the management of enteropathy and restoring intestinal health are still not available. An accumulating body of preclinical studies has demonstrated that oral administration of plasma- or serum-derived protein concentrates containing high levels of immunoglobulins can improve weight, normalize gut barrier function, and reduce the severity of enteropathy in animal models. Recent studies in humans, using serum-derived bovine immunoglobulin/protein isolate, demonstrate that such protein preparations are safe and improve symptoms, nutritional status, and various biomarkers associated with enteropathy. Benefits have been shown in patients with HIV infection or diarrhea-predominant IBS. This review summarizes preclinical and clinical studies with plasma/serum protein concentrates and describes the effects on host nutrition, intestinal function, and markers of intestinal inflammation. It supports the concept that immunoglobulin-containing protein preparations may offer a new strategy for restoring functional homeostasis in the intestinal tract of patients with enteropathy.