Published online Aug 28, 2019. doi: 10.5497/wjp.v8.i3.26
Peer-review started: January 23, 2019
First decision: January 30, 2019
Revised: July 5, 2019
Accepted: July 16, 2019
Article in press: July 16, 2019
Published online: August 28, 2019
Inflammatory bowel disease (IBD) has been a worldwide health problem. It is characterized by severe intestinal inflammation due to immune responses against the gut microbes in genetically susceptible individuals. The understanding of gut microbiota for its composition and complex interaction in normal and diseased conditions has been assisted by the use of molecular, metagenomics and meta transcriptomics studies. The alteration of intestinal microbiota is the key determinant in the degree of inflammation caused and the prolonged course of disease. The relationship between luminal gut bacteria and innate immunity is also of prime significance. Such developments have further led to the search of specific (including bacteria and fungi) as a causative agent of IBD. Although detailed research has been done for the role of gut microbiota in IBD, molecular mechanisms and related gene expression are still not well understood in this disease, which hampers the generation of effective therapeutic agents for IBD. This paper assessed various factors contributing to IBD, genetic dysbiosis and pathogenic influence in the gut microbiota, interactions such as microbiome-host immune system interaction and microbe-microbe interactions involved in IBD, currently available IBD therapies, followed by a detailed review on bacterial infections that might be involved in IBD, globally and specifically in India.
Core tip: Ulcerative colitis and Crohn’s disease are two clinical forms of inflammatory bowel disease (IBD) causing recurring diarrhea, abdominal bleeding, pain and inflammation. Scientific evidence clearly indicated the role of heredity in IBD, but an accurate cause of IBD is still unclear. However, complex interactions between genes, environmental factors and the immune system could be one of the leading causes in IBD. Gut microbiome is a key link between these factors and progression of IBD. This article reviews all contributing factors and pathogenic association in IBD. Identifying such microbial causes of the onset of IBD can help researchers to develop effective treatment strategies.