Dysbiosis: Gut feeling

Abstract

A healthy host-microbiome relationship, crucial for intestinal homeostasis, is established early in postnatal life. Imbalance in the neonatal microbiome may lead to the development of chronic pathological conditions later in life. Dysbiosis of the gut microbiota is increasingly being linked to the etiology of both intestinal and systemic illnesses such as irritable bowel disease (IBD), cardiovascular diseases and diabetes, as well as kidney and neurological disorders. Gut dysbiosis also leads to the development of colorectal cancer (CRC). Despite substantial research, little is known about the interactions between microorganisms, their hosts, and their environments, or whether dysbiosis is a cause or consequence of disease. According to a recent hypothesis, bacterial species living in the mucus layer of the colon may determine whether cellular homeostasis is retained or inflammatory processes are elicited, either through direct interaction with intestinal epithelium or indirectly via bacterial metabolites. Recently, high throughput deep-sequencing technology has enabled the characterization of the microbiota in patients suffering from intestinal or extra-intestinal disorders, and a strong association between dysbiosis and disease development was found. However, specific disease drivers still need to be identified in most cases. Small compounds and metabolites produced by gut bacterial flora act as signaling molecules, such as neurotransmitters and neuropeptides that can profoundly influence host physiology. These metabolites play a crucial role in modulating gut-brain crosstalk. There is growing evidence that neurological disorders such as Alzheimer's disease, Parkinson’s and others, may originate or be exaggerated in response to microbial dysbiosis either directly or indirectly interfering with the drugs through metabolites. The present evidence on the role of the gut microbiota in disease development and drug metabolism is summarized in this review. Based on available studies, we can explore the potential of gut flora to alleviate disease progression.