Role of gut microbiota in pathogenesis of selected chronic diseases

The human digestive system is colonized by a huge number of microorganisms, that are referred to collectively as the gut microbiota. The composition of intestinal microorganisms are shaped from an early life and undergoes constant changes depending on the influence of external factors, such as: type of delivery, feeding the young child, diet in subsequent years of life, pharmaceuticals use, stress, lifestyle or infections and previous inflammation within the digestive tract. Despite transient changes in microbiota composition, the intestinal ecosystem is constantly striving to maintain homeostasis, both qualitative and quantitative, which is fundamental to human health and human development. Microbes present in the intestines are responsible for sealing the intestinal barrier, mucin production, stimulation of the angiogenesis process, supporting digestive processes by fermentation and decomposition of undigested food residues, vitamin production or protection from pathogenic microorganisms. As shown by numerous studies carried out in recent years, intestinal dysbiosis plays a fundamental role in the development of many chronic diseases such as inflammatory bowel disease, diabetes, obesity, celiac disease, connective tissue diseases and others. Insightful understanding of the interactions between microorganisms and the host organisms can provide new information about pathogenesis of diseases as well as new ways to prevent and treat intestinal or systemic disorders. The aim of this work is to review the latest reports on the role of the gastrointestinal microbiome in selected chronic diseases.