In the last decade, it has become increasingly recognized that a balanced gut microbiota plays an important role in maintaining the health of the host. Numerous clinical and preclinical studies have shown that changes in gut microbiota composition are associated with a variety of neurological diseases, e.g., Parkinson's disease, Alzheimer's disease, and myasthenia gravis. However, the underlying molecular mechanisms are complex and remain unclear. Behavioral phenotypes can be transmitted from humans to animals through gut microbiota transplantation, indicating that the gut microbiota may be an important regulator of neurological diseases. However, further research is required to determine whether animal-based findings can be extended to humans and to elucidate the relevant potential mechanisms by which the gut microbiota regulates neurological diseases. Such investigations may aid in the development of new microbiota-based strategies for diagnosis and treatment and improve the clinical management of neurological disorders. In this review, we describe the dysbiosis of gut microbiota and the corresponding mechanisms in common neurological diseases, and discuss the potential roles that the intestinal microbiome may play in the diagnosis and treatment of neurological disorders.
Animals ; Humans ; Gastrointestinal Microbiome/physiology* ; Nervous System Diseases ; Parkinson Disease ; Microbiota ; Brain

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

BACKGROUND: : Tourette syndrome (TS) is a neuropsychiatric disorder with onset in childhood that warrants effective therapies. Gut microbiota can affect central physiology and function via the microbiota-gut-brain axis. Therefore, the gut microbiota plays an important role in some mental illnesses. A small clinical trial showed that fecal microbiota transplantation (FMT) may alleviate TS symptoms in children. Herein, FMT effects and mechanisms were explored in a TS mouse model. METHODS: : TS mice model (TSMO) (n = 80) were established with 3,3'-iminodipropionitrile, and 80 mice were used as controls. Mice were grouped into eight groups and were subjected to FMT with feces from children or mice with or without TS, or were given probiotics. Fecal specimens were collected 3 weeks after FMT. 16S rRNA sequencing, behavioral observation, and serum serotonin (5-HT) assay were performed. Differences between groups were analyzed using Mann-Whitney U test and Kolmogorov-Smirnov (KS) tests. RESULTS: : A total of 18 discriminative microbial signatures (linear discriminant analysis score > 3) that varied significantly between TS and healthy mice (CONH) were identified. A significant increase in Turicibacteraceae and Ruminococcaceae in TSMO after FMT was observed (P  < 0.05). Compared with non-transplanted TSMO, the symptoms of those transplanted with feces from CONH were alleviated (W = 336, P = 0.046). In the probiotic and FMT experiments, the serum 5-HT levels significantly increased in TSMO that received probiotics (KS = 1.423, P = 0.035) and in those transplanted with feces from CONH (W = 336.5, P = 0.046) compared with TSMO without transplantation. CONCLUSIONS : This study suggests that FMT may ameliorate TS by promoting 5-HT secretion, and it provides new insights into the underlying mechanisms of FMT as a treatment for TS.
Animals ; Disease Models, Animal ; Fecal Microbiota Transplantation ; Gastrointestinal Microbiome/physiology* ; Mice ; RNA, Ribosomal, 16S/genetics* ; Serotonin ; Tics ; Tourette Syndrome/therapy*

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

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

BACKGROUND: Anorexia nervosa (AN) is a psychological disorder, which is characterized by the misunderstanding of body image, food restriction, and low body weight. An increasing number of studies have reported that the pathophysiological mechanism of AN might be associated with the dysbiosis of gut microbiota. The purpose of our study was to explore the features of gut microbiota in patients with AN, hoping to provide valuable information on its pathogenesis and treatment. METHODS: In this cross-sectional study, from August 2020 to June 2021, patients with AN who were admitted into Peking University Third Hospital and Peking University Sixth Hospital ( n   =  30) were recruited as the AN group, and healthy controls (HC) were recruited from a middle school and a university in Beijing ( n   =  30). Demographic data, Hamilton Depression Scale (HAMD) scores of the two groups, and length of stay of the AN group were recorded. Microbial diversity analysis of gut microbiota in stool samples from the two groups was analyzed by 16S ribosomal RNA (rRNA) gene sequencing. RESULTS: The weight (AN vs. HC, [39.31 ± 7.90] kg vs. [56.47 ± 8.88] kg, P  < 0.001) and body mass index (BMI, AN vs. HC, [14.92 ± 2.54] kg/m 2vs. [20.89 ± 2.14] kg/m 2 , P  < 0.001) of patients with AN were statistically significantly lower than those of HC, and HAMD scores in AN group were statistically significantly higher than those of HC. For alpha diversity, there were no statistically significant differences between the two groups; for beta diversity, the two groups differed obviously regarding community composition. Compared to HC, the proportion of Lachnospiraceae in patients with AN was statistically significantly higher (AN vs. HC, 40.50% vs. 31.21%, Z  = -1.981, P  = 0.048), while that of Ruminococcaceae was lower (AN vs. HC, 12.17% vs. 19.15%, Z  = -2.728, P  = 0.007); the proportion of Faecalibacterium (AN vs. HC, 3.97% vs. 9.40%, Z  = -3.638, P  < 0.001) and Subdoligranulum (AN vs. HC, 4.60% vs. 7.02%, Z  = -2.369, P  = 0.018) were statistically significantly lower, while that of Eubacterium_hallii_group was significantly higher (AN vs. HC, 7.63% vs. 3.43%, Z  = -2.115, P  = 0.035). Linear discriminant effect (LEfSe) analysis (LDA score >3.5) showed that o_Lachnospirales, f_Lachnospiraceae, and g_Eubacterium_hallii_group (o, f and g represents order, family and genus respectively) were enriched in patients with AN. Microbial function of nutrient transport and metabolism in AN group were more abundant ( P  > 0.05). In AN group, weight and BMI were significantly negatively correlated with the abundance of Bacteroidota and Bacteroides , while positively correlated with Subdoligranulum . BMI was significantly positively correlated with Firmicutes; HAMD scores were significantly negatively correlated with Faecalibacterium. CONCLUSIONS The composition of gut microbiota in patients with AN was different from that of healthy people. Clinical indicators have correlations with the abundance of gut microbiota in patients with AN.
Humans ; Gastrointestinal Microbiome/physiology* ; Anorexia Nervosa ; Cross-Sectional Studies ; Dysbiosis/microbiology* ; Body Mass Index ; RNA, Ribosomal, 16S/genetics* ; Feces/microbiology*

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

Intestinal failure (IF) is defined as the critical reduction of functional intestines below the minimum needed to absorb nutrients and fluids, so that intravenous supplementation with parenteral nutrition (PN) is required to maintain health and/or growth. Although the benefits are evident, patients receiving PN can suffer from serious cholestasis due to lack of enteral feeding and small intestinal bacterial overgrowth (SIBO). One such complication that may arise is intestinal failure-associated liver disease (IFALD). Evidences from recent studies suggest that alterations in the intestinal microbiota, as well as intraluminal bile acid driven signaling, may play a critical role in both hepatic and intestinal injury. Since Marshall first proposed the concept of the gut-liver axis in 1998, the role of gut-liver axis disorders in the development of IFALD has received considerable attention. The conversation between gut and liver is the key to maintain liver metabolism and intestinal homeostasis, which influences each other and is reciprocal causation. However, as a "forgotten organ" , intestinal microbiota on the pathogenesis of IFALD has not been well reflected. As such, we propose, for the first time, the concept of gut-microbiota-liver axis to emphasize the importance of intestinal microbiota in the interaction of gut-liver axis. Analysis and research on gut-microbiota-liver axis will be of great significance for understanding the pathogenesis of IFALD and improving the prevention and treatment measures.
Bacterial Infections/physiopathology* ; Bile Acids and Salts/physiology* ; Cholestasis/physiopathology* ; Enteral Nutrition ; Gastrointestinal Microbiome/physiology* ; Humans ; Intestinal Diseases/physiopathology* ; Intestines/physiopathology* ; Liver/physiopathology* ; Liver Diseases/physiopathology* ; Parenteral Nutrition/adverse effects* ; Short Bowel Syndrome/physiopathology* ; Signal Transduction

Fecal microbiota transplantation (FMT) is to transplant the functional bacteria in the feces of healthy people into the patients' intestines, rebuild the new balance of intestinal flora, and achieve the treatment goals of intestinal and extraintestinal diseases. In the past 10 years, FMT has made a breakthrough in the treatment of intestinal and extraintestinal diseases, which is highly expected to treat difficult diseases. However, due to the complexity of FMT methodology and the lack of a unified standard, there is a high heterogeneity in FMT efficacy among various researches, greatly affected its clinical application. Under the initiative of Parenteral and Enteral Nutrition Branch of Chinese Medical Association, Enhanced Recovery after Surgery Branch of China International Health Care Promotion Exchange Association, China Microecological Treatment Innovation Alliance, and Microecology Committee of Shanghai Preventive Medicine Association, the first expert consensus on standardized methodology and clinical application of FMT was established in China, with a view to improving the efficacy of FMT, reducing the incidence of adverse reactions and promoting the clinical application of FMT.
China ; Consensus ; Fecal Microbiota Transplantation ; adverse effects ; methods ; standards ; Feces ; microbiology ; Gastrointestinal Microbiome ; physiology ; Humans ; Treatment Outcome