Characterization of the Human Microbiome in Health and Disease
Commensal microbes are responsible for or associated with a seemingly innumerable list of physiological functions, such as colonization resistance, metabolism, behavior, carcinogenesis, and regulating various functions of the immune system. The microbiota is dynamic; it varies with environmental stimuli, including the circadian rhythm, diet, and drugs. Understanding how the microbiota functions is therefore inexorably linked to understanding the active processes that underpin health and disease states. The ideas inherent in the hygiene hypothesis—in sum, that microbial exposure can affect long-term health outcomes—laid the theoretical foundation for translational microbiome studies. The chapter describes the clinical and animal data for many different disease processes. These include: gastrointestinal diseases, cardiovascular disease, oncology, autoimmune diseases, atopic diseases, infectious diseases, and HIV infection. The numerous microbiome–disease associations identified thus far have generated a great deal of hope that understanding the relevant microbe–host interactions will open the door to unlimited therapeutic applications.
