Gastrointestinal Microbiome ; physiology ; Gastrointestinal Tract ; microbiology ; Humans ; Intestinal Diseases ; microbiology

OBJECTIVEThis review aimed to summarize the relationship between intestinal microbiota metabolism and cardiovascular disease (CVD) and to propose a novel CVD therapeutic target.

DATA SOURCESThis study was based on data obtained from PubMed and EMBASE up to June 30, 2015. Articles were selected using the following search terms: "Intestinal microbiota", "trimethylamine N-oxide (TMAO)", "trimethylamine (TMA)", "cardiovascular", and "atherosclerosis".

STUDY SELECTIONStudies were eligible if they present information on intestinal microbiota metabolism and atherosclerosis. Studies on TMA-containing nutrients were also included.

RESULTSA new CVD risk factor, TMAO, was recently identified. It has been observed that several TMA-containing compounds may be catabolized by specific intestinal microbiota, resulting in TMA release. TMA is subsequently converted to TMAO in the liver. Several preliminary studies have linked TMAO to CVD, particularly atherosclerosis; however, the details of this relationship remain unclear.

CONCLUSIONSIntestinal microbiota metabolism is associated with atherosclerosis and may represent a promising therapeutic target with respect to CVD management.

Atherosclerosis ; metabolism ; microbiology ; Gastrointestinal Microbiome ; physiology ; Humans ; Methylamines ; metabolism

Childhood malnutrition is an important disease threatening healthy growth of children worldwide. Gut microbiota has close links to food digestion, absorption and intestinal function. Current research considers that alterations in gut microbiota have been strongly implicated in childhood malnutrition. This review article addresses the latest understanding and evidence of interrelationship between gut microbiota and individual nutrition status, the changes of gut microbiota in different types of malnutrition, and the attribution of gut microbiota in the treatment and prognosis of malnutrition. It provides in depth understanding of childhood malnutrition from the perspective of microbiome.
Child ; Gastrointestinal Microbiome ; physiology ; Humans ; Malnutrition ; etiology ; Nutritional Status

There are direct and indirect interactions between gut microbiota and host immune response, which can have a multifaceted impact on host health. Dysbiosis caused by disturbances in the gut microbiota is associated with susceptibility to many diseases, especially immune-related diseases. Based on the research results in recent years, this paper introduced the mechanism of the interaction between gut microbiota and host immunity, and expounded the role of gut microbiota in the occurrence and development of immune-related diseases, including intestinal system diseases such as inflammatory bowel disease and other systemic diseases such as rheumatoid arthritis, and summarized disease treatment strategies targeting gut microbiota. A better understanding of the research progress of gut microbiota and immune-related diseases will help us in the prevention and management of such diseases, and broaden our path to discover disease intervention targets.
Gastrointestinal Microbiome/physiology* ; Humans ; Inflammatory Bowel Diseases ; Intestines

Unique factors in the space environment can cause dysbiosis of astronauts' gut microbiota and its metabolites, which may exert systematic physiological effects on human body. Recent progress regarding the effect of space flight/simulated space environment (SF/SPE) on the composition of gut microbiota and its metabolites was reviewed in this paper. SF/SPE may cause the increase of invasive pathogenic bacteria and the decrease of beneficial bacteria, aggravating intestinal inflammation and increasing intestinal permeability. SF/SPE may also cause the decrease of beneficial metabolites or the increase of harmful metabolites of gut microbiota, leading to metabolism disorder in vivo, or inducing damage of other systems, thus not beneficial to the health and working efficiency of astronauts. Summarizing the effects of SF/SPE on gut microbiota may provide scientific basis for further researches in this field and the on-orbit health protection of astronauts.
Humans ; Gastrointestinal Microbiome/physiology* ; Dysbiosis/microbiology* ; Bacteria/metabolism*

Sepsis is a life-threatening organ dysfunction caused by dysregulated host responses to infection. Despite significant advances in anti-infective, immunomodulatory, and organ function support technologies, the precise and targeted management of sepsis remains a challenge due to its high heterogeneity. Studies have identified disturbed tryptophan (TRP) metabolism as a common mechanism in multiple diseases, which is involved in both immune regulation and the development of multi-organ damages. The rise of research on intestinal microflora has further highlighted the critical role of microflora-regulated TRP metabolism in pathogen-host interactions and the "cross-talk" among multi-organs, making it a potential key target for precision medicine in sepsis. This article reviews TRP metabolism, the regulation of TRP metabolism by the intestinal microflora, and the characteristics of TRP metabolism in sepsis, providing clues for further clinical targeting of TRP metabolism for precision medicine in sepsis.
Humans ; Gastrointestinal Microbiome/physiology* ; Tryptophan/metabolism* ; Precision Medicine ; Sepsis

Gut microbiota have been validated to play a pivotal role in metabolic regulation. As the most effective treatment for obesity and related comorbidities, bariatric surgery has been shown to result in significant alterations to the gut microbiota. Literature have recently suggested temporal and spatial features of alterations to the intestinal bacteria following bariatric surgery, which is possibly attributed to the gut adaptation to the surgical modification on the gastrointestinal tract. More importantly, the gut microbiota have been appreciated as a critical contributor to the metabolic improvements following bariatric surgery. Although not fully elucidated, the underlying mechanisms are associated with the molecular pathways mediating the crosstalk between gut microbiota and host . On the other hand, change of the gut microbiota has been found to be related to the prognosis of patients receiving bariatric surgery. Some studies even point out negative effects of the gut microbiota on certain surgical complications . In this review, we summarize the characteristics of alterations to the gut microbiota following bariatric surgery as well as its relevant impacts to better understand the role of gut microbiota in bariatric surgery.
Bariatric Surgery ; Gastrointestinal Microbiome/physiology* ; Gastrointestinal Tract ; Humans ; Obesity/surgery* ; Treatment Outcome

The mammalian internal circadian clock system has been evolved to adapt to the diurnal changes in the internal and external environment of the organism to regulate diverse physiological functions, such as the sleep-wake cycle and feeding rhythm, thereby coordinating the rhythmic changes of energy demand and nutrition supply in each diurnal cycle. The circadian clock regulates glucose metabolism, lipid metabolism, and hormones secretion in diverse tissues and organs, including the liver, skeletal muscle, pancreas, heart, and vessels. As a special "organ" of the host, the gut microbiota, together with the intestinal microenvironment (tissues, cells, and metabolites) in a co-evolutionary process, constitutes a micro-ecosystem and plays an important role in the process of nutrient digestion and absorption in the intestine of the host. In recent years, accumulating evidence indicates that the compositions, quantities, colonization, and functional activities of the gut microbiota exhibit significant circadian variations, which are closely related to the changes of various physiological functions under the regulation of host circadian clock system. In addition, several studies have shown that the gut microbiota can produce many important metabolites such as the short-chain fatty acids through the degradation of indigestive dietary fibers. A portion of gut microbiota-derived metabolites can regulate the circadian clock system and metabolism of the host. This article mainly discusses the interaction between the host circadian clock system and the gut microbiota, and highlights its influence on energy metabolism of the host, providing a novel clues and thought for the prevention and treatment of metabolic diseases.
Animals ; Circadian Clocks/physiology* ; Circadian Rhythm/physiology* ; Ecosystem ; Energy Metabolism ; Gastrointestinal Microbiome/physiology* ; Lipid Metabolism/physiology* ; Mammals

OBJECTIVETo systematically review the updated information about the gut microbiota-brain axis.

DATA SOURCESAll articles about gut microbiota-brain axis published up to July 18, 2016, were identified through a literature search on PubMed, ScienceDirect, and Web of Science, with the keywords of "gut microbiota", "gut-brain axis", and "neuroscience".

STUDY SELECTIONAll relevant articles on gut microbiota and gut-brain axis were included and carefully reviewed, with no limitation of study design.

RESULTSIt is well-recognized that gut microbiota affects the brain's physiological, behavioral, and cognitive functions although its precise mechanism has not yet been fully understood. Gut microbiota-brain axis may include gut microbiota and their metabolic products, enteric nervous system, sympathetic and parasympathetic branches within the autonomic nervous system, neural-immune system, neuroendocrine system, and central nervous system. Moreover, there may be five communication routes between gut microbiota and brain, including the gut-brain's neural network, neuroendocrine-hypothalamic-pituitary-adrenal axis, gut immune system, some neurotransmitters and neural regulators synthesized by gut bacteria, and barrier paths including intestinal mucosal barrier and blood-brain barrier. The microbiome is used to define the composition and functional characteristics of gut microbiota, and metagenomics is an appropriate technique to characterize gut microbiota.

CONCLUSIONSGut microbiota-brain axis refers to a bidirectional information network between the gut microbiota and the brain, which may provide a new way to protect the brain in the near future.

Animals ; Brain ; metabolism ; physiology ; Central Nervous System ; metabolism ; physiology ; Gastrointestinal Microbiome ; physiology ; Gastrointestinal Tract ; microbiology ; Humans ; Hypothalamo-Hypophyseal System ; metabolism ; physiology ; Pituitary-Adrenal System ; metabolism ; physiology

Human physiology and pathology can be affected by different nutritional conditions. At cellular level, the availability of a nutritional component not only mediates metabolic reactions but also transmits signals for diverse biological activities. Epigenetic regulation such as DNA methylation and histone post-translational modifications is considered as one of the nutrient-mediated signaling receivers as almost all of the epigenetic enzyme activities require intermediary metabolites as cofactors. The gut microbiome as “forgotten organ” has been suggested as a metabolite generator as well as a nutrient sensor for its host organism, affecting human health and diseases. Given the metabolite-dependent activities of epigenetic regulators, the gut microbiome has a high potential to influence the epigenetics in human physiology. Here, I review the involvement of gut microbiome in diverse human diseases and the mechanisms of epigenetic regulation by different metabolites. Thereafter, I discuss how the gut microbiome-generated metabolites affect host epigenetics, raising a possibility to develop a therapeutic intervention based on the interaction between the microbiome and epigenetics for human health.
DNA Methylation ; Epigenomics* ; Gastrointestinal Microbiome* ; Histones ; Humans* ; Metabolism ; Microbiota ; Pathology ; Physiology ; Protein Processing, Post-Translational