Intestinal Microbiota: Facts and Fiction

Abstract

In humans, the gut microbiota forms a complex ecosystem consisting of a vast number of bacteria, Archaea, fungi and viruses. It represents a major stimulus to the development of the immune system and many other physiological functions, so that it may shape the individual's susceptibility to infectious and immune-mediated diseases. The emergence of new ‘-omics' methods recently revolutionized the way we study the host-microbe interactions, but they also raised new questions and issues. In this review, we discuss the impact of these new data on the current and future therapies for chronic inflammatory diseases. We also outline the major conceptual, technical and interpretational issues that recently led to some misleading conclusions and discuss in brief the current research directions in the field.

Distinct gut microbiota profiles in patients with primary sclerosing cholangitis and ulcerative colitis

“…The intestinal microbiota is involved in the pathogenesis of various diseases and is, therefore, a potential biomarker or even a therapeutic target[33]. We identified specific signatures of the fecal microbiota that distinguished patients with PSC from those with UC and from HCs.…”

Intestinal microbiota changes after solid organ transplant: a systematic review.

“…The intestinal microbiota represents a stimulus for the development of the immune system, especially the establishment of lymphoid tissues, activation of neutrophils, induction of IgA and regulation of homeostasis of intestinal T cells (regulatory T cell and T helper), which may interfere in the human susceptibility to infections and immune-mediated diseases 50,51 . When altered, the microbiota shows a reduction in the number of bacteria that favor regulatory cells or an increase in the number of cells that help the induction of immune systems in response to pathogens, leading to infections and diseases in individuals 52 .…”

Helicobacter pylori and gut microbiota in multiple sclerosis versus Alzheimer's disease: 10 pitfalls of microbiome studies

“…3 This is true even in digestive diseases whose connection with gut microbiota appears to be straightforward. 3 For example, dysbiosis may only reflect constipation or diarrhea, which changes the gut and colonic transit, and fecal output.…”

“…3,138,153 Among the taxonomic ranks, from the phylum to the genus, there is no consensus on the bacterial components of “healthy gut microbiota” or its alteration (dysbiosis) that can be applicable for all individuals, while it may be possible to find the stable bacterial components/amounts at the genus or species level. Hoarau et al compared the gut microbiome between 1) patients with Crohn’s disease, 2) their healthy family members, and 3) unrelated healthy individuals living in the same area.…”

“…3 Currently, most microbiota studies focused on the community of bacteria (bacteriome), but not the other taxa. 4,5 Healthy gut bacteriome mainly consists of two major phyla, Bacteroidetes and Firmicutes , and three minor phyla, Actinobacteria, Proteobacteria , and Verrucomicrobia (Table 1).…”