The interplay between the gut microbiota and the immune system

The impact of the gut microbiota on immune homeostasis within the gut and, importantly, also at systemic sites has gained tremendous research interest over the last few years. The intestinal microbiota is an integral component of a fascinating ecosystem that interacts with and benefits its host on several complex levels to achieve a mutualistic relationship. Host-microbial homeostasis involves appropriate immune regulation within the gut mucosa to maintain a healthy gut while preventing uncontrolled immune responses against the beneficial commensal microbiota potentially leading to chronic inflammatory bowel diseases (IBD). Furthermore, recent studies suggest that the microbiota composition might impact on the susceptibility to immune-mediated disorders such as autoimmunity and allergy. Understanding how the microbiota modulates susceptibility to these diseases is an important step toward better prevention or treatment options for such diseases.     

肠道微生物群组与肠道免疫的关系

人类肠道是一个生态系统,存在大量的微生物。肠道微生物群与肠道天然免疫及获得性免疫之间存在动态的相互作用,影响着肠道免疫系统的形成和功能。当这种相互作用中的一步或多步失效时,自身免疫性疾病和炎症性疾病就会发生。回顾肠道微生物群组与肠道免疫功能的关系,有助于提高微生物对免疫系统失调相关的肠道疾病治疗应用的认识。     

The gut microbiota keeps enteric glial cells on the move; prospective roles of the gut epithelium and immune system

The enteric nervous system (ENS) coordinates the major functions of the gastrointestinal tract. Its development takes place within a constantly changing environment which, after birth, culminates in the establishment of a complex gut microbiota. How such changes affect ENS development and its subsequent function throughout life is an emerging field of study that holds great interest but which is inadequately explored thus far. In this addendum, we discuss our recent findings showing that a component of the ENS, the enteric glial cell network that resides in the gut lamina propria, develops after birth and parallels the evolution of the gut microbiota. Importantly, this network was found to be malleable throughout life by incorporating new cells that arrive from the area of the gut wall in a process of directional movement which was controlled by the lumen gut microbiota. Finally, we postulate on the roles of the intestinal epithelium and the immune system as potential intermediaries between gut microbiota and ENS responses.     

The gut microbiota keeps enteric glial cells on the move; prospective roles of the gut epithelium and immune system

The enteric nervous system (ENS) coordinates the major functions of the gastrointestinal tract. Its development takes place within a constantly changing environment which, after birth, culminates in the establishment of a complex gut microbiota. How such changes affect ENS development and its subsequent function throughout life is an emerging field of study that holds great interest but which is inadequately explored thus far. In this addendum, we discuss our recent findings showing that a component of the ENS, the enteric glial cell network that resides in the gut lamina propria, develops after birth and parallels the evolution of the gut microbiota. Importantly, this network was found to be malleable throughout life by incorporating new cells that arrive from the area of the gut wall in a process of directional movement which was controlled by the lumen gut microbiota. Finally, we postulate on the roles of the intestinal epithelium and the immune system as potential intermediaries between gut microbiota and ENS responses.     

A survey on the developmental intestinal microbiota research in China: The history,funding, and frontiers of gut bacteria

Up to 100 trillion bacteria are harbored in the human intestine with a mutualistic and interdependent relationship with the host during a long period of co‐evolution. The so‐called intestinal microbiota (IM) fulfill important metabolic tasks and the impaired stability may lead to IM‐related diseases, including inflammatory bowel disease (IBD), colorectal cancer (CRC), metabolic syndrome (MS), liver diseases, and so on. Here, we review the past and development of IM research in China, including the achievements that Chinese researchers have made both in basic and clinical scientific field. Moreover, we evaluate the contributions of the National Natural Science Foundation of China (NSFC), the 973 National Basic Research Program of China (973 Program), the 863 National High Technology Research and Development Program of China (863 Program), and funds from the public health industry in the field of IM research.     

The canine gastrointestinal microbiota: early studies and research frontiers

ABSTRACT

The canine gut microbiota is a complex microbial population that is potentially related to metabolism, immunologic activity and gastrointestinal (GI) diseases. Early studies revealed that the canine gut microbiota was dynamic, and bacterial populations in the adjacent gut segments were similar, with anaerobes predominating. Metagenomics analysis revealed that nutrient contents in the diet modulated bacterial populations and metabolites in the canine gut. Further research revealed significant correlations between dietary factors and canine gut core microbiomes. Canine GI diseases are closely correlated with gut microbiota dysbiosis and metabolic disorders. Probiotic-related therapies can effectively treat canine GI diseases. Recent studies have revealed that the canine gut microbiota is similar to the human gut microbiota, and dietary factors affect both. Studying canine intestinal microorganisms enables clarifying changes in the canine intestinal bacteria under different conditions, simulating human diseases in dog models, and conducting in-depth studies of the interactions between intestinal bacteria and disease.     

Air pollution effects on the gut microbiota

Global incidence rates for inflammatory bowel disease (IBD) have gradually risen over the past 20 years. Genome-wide association studies (GWAS) have identified over 160 genetic loci associated with IBD; however, inherited factors only account for a partial contribution to the disease risk. We have recently shown that urban airborne particulate matter (PM) ingested via contaminated food can alter gut microbiome and immune function under normal and inflammatory conditions. In this addendum, we will discuss how PM can modify the gut microbial form and function, provide evidence on changes seen in intestinal barrier, and suggest a working hypothesis of how pollutants affect the gastrointestinal tract. The significance of the work presented could lead to identifying airborne pollutants as potential risk factors and thus provide better patient care management.     

The role of gut microbiota in immune homeostasis and autoimmunity

Keeping a delicate balance in the immune system by eliminating invading pathogens, while still maintaining self-tolerance to avoid autoimmunity, is critical for the body's health. The gut microbiota that resides in the gastrointestinal tract provides essential health benefits to its host, particularly by regulating immune homeostasis. Moreover, it has recently become obvious that alterations of these gut microbial communities can cause immune dysregulation, leading to autoimmune disorders. Here we review the advances in our understanding of how the gut microbiota regulates innate and adaptive immune homeostasis, which in turn can affect the development of not only intestinal but also systemic autoimmune diseases. Exploring the interaction of gut microbes and the host immune system will not only allow us to understand the pathogenesis of autoimmune diseases but will also provide us new foundations for the design of novel immuno- or microbe-based therapies.     

Intestinal microbiota as regulator of the immune system

The intestinal microbiota contributes to the regulation of the intestinal immune system and protection against intestinal infections. Recent studies revealed that the locally restricted intestinal microbiota affects systemic immunity and influences the induction of autoimmunity.     

The effects of gut microbiota on CNS function in humans

The role of the gastrointestinal microbiota in human brain development and function is an area of increasing interest and research. Preclinical models suggest a role for the microbiota in broad aspects of human health, including mood, cognition, and chronic pain. Early human studies suggest that altering the microbiota with beneficial bacteria, or probiotics, can lead to changes in brain function, as well as subjective reports of mood. As the mechanisms of bidirectional communication between the brain and microbiota are better understood, it is expected that these pathways will be harnessed to provide novel methods to enhance health and treat disease.     

Persistent effects of early infant diet and associated microbiota on the juvenile immune system

Early infant diet has significant impacts on the gut microbiota and developing immune system. We previously showed that breast-fed and formula-fed rhesus macaques develop significantly different gut microbial communities, which in turn are associated with different immune systems in infancy. Breast-fed animals manifested greater T cell activation and proliferation and harbored robust pools of T helper 17 (T_H17) cells. These differences were sustained throughout the first year of life. Here we examine groups of juvenile macaques (approximately 3 to 5 y old), which were breast-fed or formula-fed in infancy. We demonstrate that juveniles breast-fed in infancy maintain immunologic differences into the fifth year of life, principally in CD8⁺ memory T cell activation. Additionally, long-term correlation networks show that breast-fed animals maintain persistent relationships between immune subsets that are not seen in formula-fed animals. These findings demonstrate that infant feeding practices have continued influence on immunity for up to 3 to 5 y after birth and also reveal mechanisms for microbial modulation of the immune system.     

Persistent effects of early infant diet and associated microbiota on the juvenile immune system

Early infant diet has significant impacts on the gut microbiota and developing immune system. We previously showed that breast-fed and formula-fed rhesus macaques develop significantly different gut microbial communities, which in turn are associated with different immune systems in infancy. Breast-fed animals manifested greater T cell activation and proliferation and harbored robust pools of T helper 17 (T_H17) cells. These differences were sustained throughout the first year of life. Here we examine groups of juvenile macaques (approximately 3 to 5 y old), which were breast-fed or formula-fed in infancy. We demonstrate that juveniles breast-fed in infancy maintain immunologic differences into the fifth year of life, principally in CD8⁺ memory T cell activation. Additionally, long-term correlation networks show that breast-fed animals maintain persistent relationships between immune subsets that are not seen in formula-fed animals. These findings demonstrate that infant feeding practices have continued influence on immunity for up to 3 to 5 y after birth and also reveal mechanisms for microbial modulation of the immune system.     

Modulation of the gut microbiota by metformin improves metabolic profiles in aged obese mice

The gut microbiota is a contributing factor in obesity-related metabolic disorders. The effect of metformin on the gut microbiota has been reported; however, the relationship between the gut microbiota and the mechanism of action of metformin in elderly individuals is unclear. In this study, the effect of metformin on the gut microbiota was investigated in aged obese mice. The abundance of the genera Akkermansia, Bacteroides, Butyricimonas, and Parabacteroides was significantly increased by metformin in mice fed a high-fat diet. Metformin treatment decreased the expression of IL-1β and IL-6 in epididymal fat, which was correlated with the abundance of various bacterial genera. In addition, both fecal microbiota transplantation from metformin-treated mice and extracellular vesicles of Akkermansia muciniphila improved the body weight and lipid profiles of the mice. Our findings suggest that modulation of the gut microbiota by metformin results in metabolic improvements in aged mice, and that these effects are associated with inflammatory immune responses.     

人体寄生虫与肠道菌群相互作用的研究进展

人体寄生虫与人和哺乳动物肠道内的共生菌会发生一些重要的相互作用。肠道内寄生虫与肠道菌群的相互作用及产生的潜在影响已有较多报道,然而有些通常并不寄生在肠道内的寄生虫也会对肠道菌群产生影响。本文就人体肠道内和肠道外寄生虫对肠道菌群影响的研究进展作一综述。     

The role of the immune system in regulating the microbiota

A diverse population of bacteria, archaea and fungi, collectively known as the microbiota, abounds within the gastrointestinal tract of the mammalian host. This microbial population makes many important contributions to host physiology through inter-kingdom signalling and by providing nutrients that have both local and systemic effects. In a healthy state the overall host-microbial interaction is symbiotic; however, a growing number of diseases have been associated with a dysregulated microbiota. To avoid these consequences, the host exerts substantial effort to maintain proper regulation of the microbiota with respect to localization and composition. Although important to maintaining microbial balance, the host immune response can also be the cause of a disrupted microbiota, contributing to disease severity. Here, we discuss the role of the host in both maintaining and disrupting a balanced gastrointestinal microbiota.     

The role of the immune system in regulating the microbiota

A diverse population of bacteria, archaea, and fungi, collectively known as the microbiota, abounds within the gastrointestinal tract of the mammalian host. This microbial population makes many important contributions to host physiology through inter-kingdom signalling and by providing nutrients that have both local and systemic effects. In a healthy state the overall host-microbial interaction is symbiotic; however, a growing number of diseases have been associated with a dysregulated microbiota. To avoid these consequences, the host exerts substantial effort to maintain proper regulation of the microbiota with respect to localization and composition. Although important to maintaining microbial balance, the host immune response can also be the cause of a disrupted microbiota, contributing to disease severity. Here, we discuss the role of the host in both maintaining and disrupting a balanced gastrointestinal microbiota.