Dr. Fasano holds stocks in Alba Therapeutics and receives financial support from Takeda Pharmaceuticals. Dr. Taneja receives financial support from Elysium Health and Evelo Biosciences. The other Topic Editors declare no competing interests with regards to the Research Topic subject.

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Microbiota-associated pathology can be a direct result of changes in general bacterial composition, such as might be found in periodontitis and bacterial vaginosis, and/or as the result of colonization and/or overgrowth of so called keystone species. The disruption in the composition of the normal human microbiota, or dysbiosis, plays an integral role in human health and human disease. The Human Microbiota and Human Chronic Disease: Dysbioses as a Cause of Human Pathology discusses the role of the microbiota in maintaining human health. The text introduces the reader to the biology of microbial dysbiosis and its potential role in both bacterial disease and in idiopathic chronic disease states. Divided into five sections, the text delineates the concept of the human bacterial microbiota with particular attention being paid to the microbiotae of the gut, oral cavity and skin. A key methodology for exploring the microbiota, metagenomics, is also described. The book then shows the reader the cellular, molecular and genetic complexities of the bacterial microbiota, its myriad connections with the host and how these can maintain tissue homeostasis. Chapters then consider the role of dysbioses in human disease states, dealing with two of the commonest bacterial diseases of humanity – periodontitis and bacterial vaginosis. The composition of some, if not all microbiotas can be controlled by the diet and this is also dealt with in this section. The discussion moves on to the major ‘idiopathic’ diseases afflicting humans, and the potential role that dysbiosis could play in their induction and chronicity. The book then concludes with the therapeutic potential of manipulating the microbiota, introducing the concepts of probiotics, prebiotics and the administration of healthy human faeces (faecal microbiota transplantation), and then hypothesizes as to the future of medical treatment viewed from a microbiota-centric position. Provides an introduction to dysbiosis, or a disruption in the composition of the normal human microbiota Explains how microbiota-associated pathology and other chronic diseases can result from changes in general bacterial composition Explores the relationship humans have with their microbiota, and its significance in human health and disease Covers host genetic variants and their role in the composition of human microbial biofilms, integral to the relationship between human health and human disease Authored and edited by leaders in the field, The Human Microbiota and Human Chronic Disease will be an invaluable resource for clinicians, pathologists, immunologists, cell and molecular biologists, biochemists, and system biologists studying cellular and molecular bases of human diseases.

Immune-mediated inflammatory diseases (IMID) represent a group of ostensibly unrelated, chronic and highly disabling diseases that preferentially affect different organ systems. IMID are assumed to manifest as a result of the accumulation of genetic, environmental and immunological factors. A fundamental commonality between IMID is the idiopathic nature of disease, and moreover, substantial similarities are apparent in disease etiopathogenesis. The complex assemblage of microbes and their genes that exists within and on the human body, collectively known as the microbiome has emerged as a critical factor in human health and, altered microbial populations within the gastrointestinal tract lumen and mucosa have been linked to several IMID. Accordingly, we conducted several studies investigating the association of the gut microbiome with IMID. Our main study investigated differences in the microbial profile and functional potential of multiple IMID utilizing 16S rDNA amplicon sequencing and analysis of stool. We also investigated the mucosal-associated microbiome in IBD to characterize the microbial populations and their functions residing in distinct gastrointestinal compartments from inflamed and noninflamed mucosa. We also explored a potential environmental factor; specifically assessing whether microbes present in drinking water in low or high incidence areas of IBD might contribute to disease etiology. The findings of these studies are manifold. First, we show important differences of the stool microbial profile in IMID. In doing so, we were able to identify distinct states of gut dysbiosis and have revealed numerous microbes that are consistently or uniquely disproportionate between IMID. Second, we have shown the microbial profile associated with inflamed and noninflamed mucosa and have reported that a localized dysbiosis is not observed in the presence of inflammation. Third, we have revealed that distinct gastrointestinal compartments are comprised of similar microbial communities. Lastly, we have reported the drinking water microbiome to differ between low and high incidence areas of IBD, thus suggesting a potential role in IBD etiology. Understanding the role of the gut microbiome in human disease will enable the development and application of more appropriate therapeutic strategies that specifically target microbes within the gut.

[Increasing evidence suggests that microbiota and especially the gut microbiota (the microbes inhabiting the gut including bacteria, archaea, viruses, and fungi) plays a key role in human physiology and pathology. Recent findings indicate how dysbiosis—an imbalance in the composition and organization of microbial populations—could severely impact the development of different medical conditions (from metabolic to mood disorders), providing new insights into the comprehension of diverse diseases, such as IBD, obesity, asthma, autism, stroke, diabetes, and cancer. Given that microbial cells in the gut outnumber host cells, microbiota influences human physiology both functionally and structurally. Microbial metabolites bridge various—even distant—areas of the organism by way of the immune and hormone system. For instance, it is now clear that the mutual interaction between the gastrointestinal tract and the brain (gut–brain axis), often involves gut microbiota, indicating that the crosstalk between the organism and its microbial residents represents a fundamental aspect of both the establishment and maintenance of healthy conditions. Moreover, it is crucial to recognize that beyond the intestinal tract, microbiota populates other host organs and tissues (e.g., skin and oral mucosa). We have edited this eBook with the aim of publishing manuscripts focusing on the impact of microbiota in the development of different diseases and their associated treatments.]

Why the microbiome--our rich inner ecosystem of microorganisms--may hold the keys to human health. We are at the dawn of a new scientific revolution. Our understanding of how to treat and prevent diseases has been transformed by knowledge of the microbiome--the rich ecosystem of microorganisms that is in and on every human. These microbial hitchhikers may hold the keys to human health. In Gut Feelings, Alessio Fasano and Susie Flaherty show why we must go beyond the older, myopic view of microorganisms as our enemies to a broader understanding of the microbiome as a parallel civilization that we need to understand, respect, and engage with for the benefit of our own health.

An accessible overview of the varied microorganisms of the gut The human gut contains an extraordinary array of microorganisms existing in intricate symbiosis with the body. These microbiota, numbering in the trillions, play a crucial role in maintaining overall gut health and warding off disease. With as much as 15% of the global population suffering from Irritable Bowel Syndrome (IBS) caused by improper composition of gut microbiota, understanding these organisms and their vital contribution to human health has never been more important. The Gut Microbiota in Health and Disease provides a concise, accessible introduction to gut microbiota and their contribution to human health. It offers not only an overview of the relevant microbiota and their roles in the body, but also extended discussion of diseases caused by gut dysbiosis. It offers a crucial window into this growing body of research into a critical area of overall human health. The Gut Microbiota in Health and Disease readers will also find: Detailed analysis of dysbiotic health conditions including obesity, diabetes, and more Thorough treatment of molecular techniques for analyzing gut microbial composition Discussion of lowering diversity of the gut microbiome and the corresponding impact on global health The Gut Microbiota in Health and Disease is essential for researchers and clinicians working in immunology, gastroenterology, clinical microbiology, and related fields, as well as for clinical dieticians and postgraduate or medical students studying in these areas.