肠道菌群与脑-肠轴功能相互影响的研究进展

人体肠道内的菌群参与了许多生理功能的维持和疾病的发生。作为大脑和胃肠道功能相互调节的重要桥梁,脑-肠轴功能的正常发挥是肠道菌群维持稳定的条件。脑-肠轴紊乱可激活肠黏膜免疫,对肠道菌群产生影响,使菌群结构发生改变。反之,肠道菌群结构改变亦会影响神经系统发育,导致脑-肠轴功能紊乱,其中迷走神经和血清代谢物质在脑-肠轴功能的调节中发挥重要作用。本文就肠道菌群与脑-肠轴功能相互影响的研究进展作一综述。     

肠道菌群与自身免疫性肝炎的研究进展

肠道菌群是一个复杂的生态系统, 在多种生理和病理过程中发挥作用, 具有重要的科学研究价值。越来越多的学者发现肠道菌群的改变是自身免疫性肝炎发生、发展的重要因素。肠道菌群失调可以通过肠-肝轴影响肠道屏障的完整性、肠道和肝脏的免疫功能等, 从而介导自身免疫性肝炎。粪菌移植、益生菌、益生元、噬菌体等靶向肠道菌群的治疗有望成为预防或治疗自身免疫性肝炎的新方法。     

肠道微生物在非酒精性脂肪性肝病发病中的作用

肝脏和肠道不仅解剖学上而且在生物学功能上存在密切联系,即所谓"肠-肝轴"学说,其对某些疾病的影响越来越受到关注,其中肠道菌群在维持肠-肝轴的平衡方面起着重要作用.肠道菌群紊乱、肠道黏膜通透性改变、肠源性内毒素血症,这将破坏肝脏与肠道之间的正常关系进而导致多种肝脏疾病的发生,进而调整肠微生物成为一种治疗或预防慢性肝病的新手段.有研究表明其在非酒精性脂肪性肝病(nonalcoholic fatty liver disease,NAFLD)的发生发展中起到了重要作用,这里就肠道微生物对NAFLD的作用做一综述.     

肠道菌群对脑-肠轴和功能性消化不良的影响

肠道菌群是多种消化系统和神经系统疾病的致病因素。研究表明肠道菌群与脑-肠轴具有双向联系,对神经系统发育和功能、胃肠道功能等具有调节作用。功能性消化不良(FD)是常见的功能性胃肠病,其发病机制尚未完全阐明,近年研究表明肠道菌群在FD发病中起有重要作用。本文就肠道菌群对脑-肠轴和FD的影响作一综述。     

肠道菌群与脂肪性肝病研究新进展

目前,肠道菌群已成为一个当今研究的热点问题之一.脂肪性肝病是指由于各种原因引起的肝细胞内脂肪堆积过多的病变,引起肝的正常结构、生理及生化功能受损,最终出现临床症状的一类疾病总称,一般包括非酒精性脂肪性肝病和酒精性肝病两大类.肠道菌群和肠道通透性的变化可以通过肠-肝轴进一步影响脂肪性肝病的发展.同样,在脂肪性肝病的发生发展过程中,肠道菌群的也发生不同程度的改变.本文主要介绍肠-肝轴与脂肪性肝病的关系、脂肪性肝病进展过程中肠道菌群的变化及益生菌在脂肪性肝病治疗中的应用新进展.     

肥胖-肠道菌群-Toll样受体交互调控作用的研究进展

肥胖发病率逐年上升,已经成为全球性公共健康问题.肥胖的发生常伴有亚临床炎症表现,引起炎症水平升高与免疫功能紊乱,而这又与肠道菌群紊乱密切相关.肠道菌群与肠黏膜免疫构成动态平衡,其结构及功能异常均可引起机体免疫紊乱.肥胖性炎症反应的启动途径,涉及Toll样受体(Toll-like receptors,TLRs)活化、内质网应激与肠道菌群改变.其中,TLR4在感应肠道病原菌、诱导炎症与胰岛素抵抗进程中,扮演中心角色.另一方面,代谢、遗传与免疫等因素,整合性调控TLR功能.因此,我们从肥胖-肠道菌群-TLRs的复杂交互作用着手,阐释肠道菌群、肠道免疫与肥胖等代谢性疾病的高度相关性,以期发现这类疾病的新治疗靶点.     

肠道菌群及其代谢物与非酒精性脂肪性肝病

总结相关的实验研究发现,人体肠道菌群是非酒精性脂肪性肝病(NAFLD)发生发展的关键因素,除了人体肠道菌群组成的变化外,肠道菌群的代谢物也成为调节NAFLD病理过程的关键因素;有研究发现,肠道菌群的代谢物如短链脂肪酸、胆汁酸、三甲胺和乙醇等通过肠-肝轴途径影响肝脏代谢功能,从而导致疾病发生。现从NAFLD患者肠道菌群和代谢物的变化及发病机制,总结并探讨通过调节肠道菌群及其代谢物来治疗NAFLD,期望这些治疗策略会成为未来优化治疗NAFLD等代谢性肝病的有效方法。     

肠道菌群与肌少症发病机制

社会老龄化加剧,原发性肌肉减少症(简称肌少症)患病率逐年增加,对于肌少症的机制、危险因素与治疗等均有大量研究。肠道菌群的变化被认为与多数疾病有相关性,目前认为肠道菌群与肌少症的发生与严重程度密切相关,是近几年的研究热点,但国内外相关研究有限,进一步研究肠道菌群对肌少症的影响对改善与治疗肌少症具有重要意义。本文着重于肠-肌轴,从老年人与肠道菌群的关系、相关机制等方面对肠道菌群与肌少症的机制研究现状进行综述。     

基于肠-肝轴理论探讨非酒精性脂肪性肝病和肠道菌群的关系

非酒精性脂肪性肝病(NAFLD)目前已成为最主要的慢性肝病,被认为是代谢综合征的肝脏表现,后期可能向肝纤维化及肝硬化,甚至是肝癌发展。肠道菌群作为人体重要的共生物,影响人体的代谢功能,可能和NAFLD的发病密切相关。肠-肝轴理论为"肠道菌群失调可引起肝脏改变"提供了理论基础。探讨了肠道菌群和NAFLD发病的关系,为后期研究肠道菌群靶向治疗NAFLD奠定理论基础。     

中药对肠道黏膜免疫保护的影响及其意义

肠道黏膜表面面积大,直接与外界抗原接触,也是接触微生物最多的部位.大量研究表明,肠道黏膜与多种疾病具有相关性.中药成分复杂,含多种生物活性成分和营养成分,能为黏膜结构完整性的维持和各项生理功能的实现提供能量和营养;能直接或间接调节肠道菌群,建立肠道黏膜免疫和屏障,治疗肠黏膜免疫的相关疾病.中医传统方药对肠道黏膜具有保护和修复作用.本文总结了中药对肠道黏膜结构、免疫、菌群和代谢的影响情况,为中药治疗肠道疾病的科学性提供依据.     

Gene expression profile of endothelial cells during perturbation of the gut vascular barrier

It has been widely demonstrated that tolerance against gut microbiota is compartmentalized to mucosal sites where microbes mostly reside. How the commensal bacteria are excluded from the entrance into the blood stream via intestinal capillaries that are located beneath the gut epithelium was not clear. We recently described the existence of a new anatomical structure, the ‘gut vascular barrier’ (GVB), both in murine and human intestines that plays a fundamental role in avoiding indiscriminate trafficking of bacteria from the gut into the blood circulation. The vascular barrier integrity could be altered by Salmonella typhimurium, a pathogen capable of systemic dissemination, through the modulation of the Wnt/β-catenin signaling pathway. Here we have analyzed the differences in gut endothelial gene expression profiles during Salmonella infection and have identified some interesting characteristics of endothelial to mesenchymal transition. These findings add new insights in the gut-liver axis.     

Gut microbes and metabolites as modulators of blood-brain barrier integrity and brain health

ABSTRACT

The human gastrointestinal (gut) microbiota comprises diverse and dynamic populations of bacteria, archaea, viruses, fungi, and protozoa, coexisting in a mutualistic relationship with the host. When intestinal homeostasis is perturbed, the function of the gastrointestinal tract and other organ systems, including the brain, can be compromised. The gut microbiota is proposed to contribute to blood-brain barrier disruption and the pathogenesis of neurodegenerative diseases. While progress is being made, a better understanding of interactions between gut microbes and host cells, and the impact these have on signaling from gut to brain is now required. In this review, we summarise current evidence of the impact gut microbes and their metabolites have on blood-brain barrier integrity and brain function, and the communication networks between the gastrointestinal tract and brain, which they may modulate. We also discuss the potential of microbiota modulation strategies as therapeutic tools for promoting and restoring brain health.     

Significance of gut microbiota in alcoholic and non-alcoholic fatty liver diseases

Liver-gut communication is vital in fatty liver diseases, and gut microbes are the key regulators in maintaining liver homeostasis. Chronic alcohol abuse and persistent overnutrition create dysbiosis in gut ecology, which can contribute to fatty liver disease. In this review, we discuss the gut microbial compositional changes that occur in alcoholic and nonalcoholic fatty liver diseases and how this gut microbial dysbiosis and its metabolic products are involved in fatty liver disease pathophysiology. We also summarize the new approaches related to gut microbes that might help in the diagnosis and treatment of fatty liver disease.     

肠黏膜屏障在炎症性肠病中作用机制的研究进展

炎症性肠病(inflammatory bowel disease,IBD)是肠道慢性非特异性炎症,黏膜屏障与IBD的关系密切.正常的肠黏膜屏障能维持肠道内菌群的稳定、防止肠道内细菌及毒素的移位以及对微生物进行适当的免疫防御反应起重要作用.而当发生IBD时存在肠黏膜屏障功能的障碍.本文就肠黏膜屏障功能在IBD中作用机制的研究进展作一综述.     

Microbiome-liver crosstalk: A multihit therapeutic target for liver disease

Liver disease has become a leading cause of death, particularly in the West, where it is attributed to more than two million deaths annually. The correlation between gut microbiota and liver disease is still not fully understood. However, it is well known that gut dysbiosis accompanied by a leaky gut causes an increase in lipopolysaccharides in circulation, which in turn evoke massive hepatic inflammation promoting liver cirrhosis. Microbial dysbiosis also leads to poor bile acid metabolism and ...     

Listeriolysin S: A bacteriocin from epidemic Listeria monocytogenes strains that targets the gut microbiota

Listeria monocytogenes is a Gram-positive food-borne pathogen that in humans may traverse the intestinal, placental and blood/brain barriers, causing gastroenteritis, abortions and meningitis. Crossing of these barriers is dependent on the bacterial ability to enter host cells, and several L. monocytogenes surface and secreted virulence factors are known to facilitate entry and the intracellular lifecycle. The study of L. monocytogenes strains associated to human listeriosis epidemics has revealed the presence of novel virulence factors. One such factor is Listeriolysin S, a thiazole/oxazole modified microcin that displays bactericidal activity and modifies the host microbiota during infection. Our recent results therefore highlight the interaction of L. monocytogenes with gut microbes as a crucial step in epidemic listeriosis. In this article, we will discuss novel implications for this family of toxins in the pathogenesis of diverse medically relevant microorganisms.     

Systemic antibody responses to gut microbes in health and disease

Gastrointestinal commensal microbes usually exist in mutualistic relationship with their mammalian host. This relationship exists even though the mammalian host immune system is equipped with exquisite sensors for microbial chemical structures which trigger powerful immune defense mechanisms. Such beneficial mutualism is specifically maintained at the gut mucosal interface by a variety of physical and bioactive barriers as well as specific immunregulatory mechanisms. In addition, there is a strict compartmentalization between systemic and gut mucosal immunity--at least in inbred mice--which focuses adaptive immunity to gut microbes specifically to the gut tissue and the gut lumen. Only in circumstances of increased gut microbial exposure due to elevated gut epithelial permeability, due to genetic deficiencies in local defense mechanisms, due to imbalances in local immune regulation or in case of gastrointestinal pathogenic bacterial infections this compartmentalization is broken and systemic immune responses to gut microbes are induced, which manifest for example as systemic antibody responses specific for gut microbial antigens. Here we briefly discuss the abundance of systemic antibody responses to commensal gut bacteria in healthy humans and how it is altered in situations with chronic enteropathies such as in inflammatory bowel disease and HIV-1 infection or infection with gut bacterial pathogens.     

Gut Bacteria have a novel sweet tooth: ribose sensing and scavenging from fiber

ABSTRACT

Dietary fiber is known to influence symbiotic gut microbiota community structure and physiology; however, how and if dietary fiber can induce further exogenous nutrient uptake within gut microbes is ill-defined. Recent findings highlight how during periods of high-fiber consumption, a prevalent gut bacteria senses and scavenges the ubiquitous sugar ribose. This molecular adaptation exemplifies how particular gut microbes have developed a sophisticated system to scavenge nutrients in a diet-dependent manner.     

The influence of the human microbiome and probiotics on cardiovascular health

Cardiovascular disease (CVD) is a major cause of death worldwide. Of the many etiological factors, microorganisms constitute one. From the local impact of the gut microbiota on energy metabolism and obesity, to the distal association of periodontal disease with coronary heart disease, microbes have a significant impact on cardiovascular health. In terms of the ability to modulate or influence the microbes, probiotic applications have been considered. These are live microorganisms which when administered in adequate amounts confer a benefit on the host. While a number of reports have established the beneficial abilities of certain probiotic bacterial strains to reduce cholesterol and hypertension, recent research suggests that their use could be more widely applied. This review presents an up-to-date summary of the known associations of the microbiome with CVD, and potential applications of probiotic therapy.