scholarly journals “Dialogue” between the Human Microbiome and the Brain

Author(s):  
Natalia Beloborodova ◽  
Andrey Grechko

In conditions of severe gut dysbiosis, there is a risk of developing diseases of the host organism in general and of the brain in particular, as evidenced by a growing number of studies. This chapter focuses on several groups of low-molecular-weight compounds that originate primarily from the gut microbiota. It discusses the results of experimental and clinical studies on the effect of microbial metabolites (such as short-chain fatty acids, phenolic metabolites of tyrosine, indolic metabolites of tryptophan, trimethylamines) on the brain. Several studies have proven that the microbial metabolite profiles in the gut and serum are interlinked and reflect a disruption of the gut microbial community. Using 16S ribosomal RNA gene sequencing, it was found that the gut microbiota of patients with positive or negative dynamics of neurological status differ taxonomically. The chapter also presents data obtained from animal germ-free (GF) models. Many researchers would like to consider the gut microbiota as a new therapeutic target, including for the treatment of brain diseases, stroke prevention, reduction of neuroinflammation, and more successful neurorehabilitation of patients.

2019 ◽  
Vol 20 (17) ◽  
pp. 4160 ◽  
Author(s):  
Elisa Borghi ◽  
Aglaia Vignoli

In this narrative review, we summarize recent pieces of evidence of the role of microbiota alterations in Rett syndrome (RTT). Neurological problems are prominent features of the syndrome, but the pathogenic mechanisms modulating its severity are still poorly understood. Gut microbiota was recently demonstrated to be altered both in animal models and humans with different neurodevelopmental disorders and/or epilepsy. By investigating gut microbiota in RTT cohorts, a less rich microbial community was identified which was associated with alterations of fecal microbial short-chain fatty acids. These changes were positively correlated with severe clinical outcomes. Indeed, microbial metabolites can play a crucial role both locally and systemically, having dynamic effects on host metabolism and gene expression in many organs. Similar alterations were found in patients with autism and down syndrome as well, suggesting a potential common pathway of gut microbiota involvement in neurodevelopmental disorders.


Author(s):  
Lin Xiao ◽  
Qin Liu ◽  
Mei Luo ◽  
Lishou Xiong

Irritable bowel syndrome (IBS) is the most common functional bowel disorder worldwide and is associated with visceral hypersensitivity, gut motility, immunomodulation, gut microbiota alterations, and dysfunction of the brain-gut axis; however, its pathophysiology remains poorly understood. Gut microbiota and its metabolites are proposed as possible etiological factors of IBS. The aim of our study was to investigate specific types of microbiota-derived metabolites, especially bile acids, short-chain fatty acids, vitamins, amino acids, serotonin and hypoxanthine, which are all implicated in the pathogenesis of IBS. Metabolites-focused research has identified multiple microbial targets relevant to IBS patients, important roles of microbiota-derived metabolites in the development of IBS symptoms have been established. Thus, we provide an overview of gut microbiota and their metabolites on the different subtypes of IBS (constipation-predominant IBS-C, diarrhea-predominant IBS-D) and present controversial views regarding the role of microbiota in IBS.


2021 ◽  
Vol 15 ◽  
Author(s):  
Mahmoud Salami

The human gastrointestinal tract hosts trillions of microorganisms that is called “gut microbiota.” The gut microbiota is involved in a wide variety of physiological features and functions of the body. Thus, it is not surprising that any damage to the gut microbiota is associated with disorders in different body systems. Probiotics, defined as living microorganisms with health benefits for the host, can support or restore the composition of the gut microbiota. Numerous investigations have proved a relationship between the gut microbiota with normal brain function as well as many brain diseases, in which cognitive dysfunction is a common clinical problem. On the other hand, increasing evidence suggests that the existence of a healthy gut microbiota is crucial for normal cognitive processing. In this regard, interplay of the gut microbiota and cognition has been under focus of recent researches. In the present paper, I review findings of the studies considering beneficial effects of either gut microbiota or probiotic bacteria on the brain cognitive function in the healthy and disease statuses.


2021 ◽  
Vol 15 ◽  
Author(s):  
Gabriele Deidda ◽  
Manuele Biazzo

Brain physiological functions or pathological dysfunctions do surely depend on the activity of both neuronal and non-neuronal populations. Nevertheless, over the last decades, compelling and fast accumulating evidence showed that the brain is not alone. Indeed, the so-called “gut brain,” composed of the microbial populations living in the gut, forms a symbiotic superorganism weighing as the human brain and strongly communicating with the latter via the gut–brain axis. The gut brain does exert a control on brain (dys)functions and it will eventually become a promising valuable therapeutic target for a number of brain pathologies. In the present review, we will first describe the role of gut microbiota in normal brain physiology from neurodevelopment till adulthood, and thereafter we will discuss evidence from the literature showing how gut microbiota alterations are a signature in a number of brain pathologies ranging from neurodevelopmental to neurodegenerative disorders, and how pre/probiotic supplement interventions aimed to correct the altered dysbiosis in pathological conditions may represent a valuable future therapeutic strategy.


2021 ◽  
Vol 19 ◽  
Author(s):  
Ya-Fei Zhao ◽  
Da-Neng Wei ◽  
Yong Tang

: Astrocytes are essential for maintaining the homeostasis of the central nervous system (CNS). Astrocytic dysfunction has been implicated in the progression of several neurodegenerative and psychiatric diseases; however, a multitude of factors and signals influencing astrocytic activity have not been entirely elucidated. Astrocytes respond to local signals from the brain, but are also indirectly modulated by gut microbiota. Previous studies revealed that most of the CNS diseases triggered by astrocytic dysfunction are closely associated with the dysbiosis of gut microbiome. Emerging data from preclinical and clinical studies suggest that maturation and functioning of astrocytes rely on gut microbiota, which plays a pivotal role in the decrease of astrocytic activation and may alleviate symptoms of brain diseases. Herein, we discuss the most recent advances concerning the complex connections between astrocytes and gut microbiota, which are involved in the immune, neurotransmission and neuroendocrine pathways. Deciphering these pathways will facilitate a better understanding of how perturbed gut microbiota contributes to the dysfunction of astrocytes and open therapeutic opportunities for the treatment of brain diseases.


2022 ◽  
Author(s):  
Jialin Liu ◽  
Yichao Fang ◽  
Lixun Cui ◽  
Zhongzhao Wang ◽  
Yusha Luo ◽  
...  

Abstract Background: Gut microbiota has emerged as a crucial target of gut-brain axis to influence brain and behavior and also has been closely connected with depression. Zhi-Zi-Chi decoctions (ZZCD), as a classic oral formula in clinic prescribed to clear heat and relieve restlessness traditionally, is widely applied in depression treatment nowadays. However, the underlying mechanism in the antidepressant activity of ZZCD remains largely unknown. Our previous study revealed that isoflavones, the bioactive constituents of Semen Sojae Praeparatum, benefited health by regulating the gut microbiota, which introduced the gut microbiota into understanding the mechanism of Traditional Chinese Medicine (TCM). Hence, in the present study, we aimed to investigate the antidepressant mechanism of ZZCD by focusing on the gut microbiota. Results: A classic depression model of chronic mild unpredictable stress (CUMS) was established in rats based on the results of behavioral tests and hippocampal histomorphology. 16S rRNA sequencing analysis indicated that ZZCD could increase short-chain fatty acid-producing and anti-inflammatory bacteria and reduce inflammatory and tryptophan-metabolizing bacteria, which reflected the changes of short-chain fatty acids (SCFAs), inflammation and tryptophan metabolism from the perspective of the gut microbiota. Furthermore, ZZCD reversed the alterations of BDNF, TNF-α, pro-inflammatory cytokines and neurotransmitters in the gut, blood and brain along the brain-gut axis and restored the decrease of butyrate in cecal content caused by CUMS. Then, butyrate was utilized to validate its ameliorative effect on pathological characteristics of depressive rats. Conclusions: Taken together, these results show that ZZCD exhibits antidepressant effect through modulating gut microbiota to facilitate the production of butyrate, which further regulate anti-inflammation, neurotransmitters, endocrine and BDNF along the gut-brain axis. Hence, this study fills the gap of the antidepressive mechanism of ZZCD in the light of the brain-gut axis and established a multi-targets and multi-levels platform eventually for further research into the mechanism of other TCM efficacy.


Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 715
Author(s):  
Emanuele Sinagra ◽  
Gaia Pellegatta ◽  
Valentina Guarnotta ◽  
Marcello Maida ◽  
Francesca Rossi ◽  
...  

The gut microbiota is emerging as an important player in neurodevelopment and aging as well as in brain diseases including stroke, Alzheimer’s disease, and Parkinson’s disease. The complex interplay between gut microbiota and the brain, and vice versa, has recently become not only the focus of neuroscience, but also the starting point for research regarding many diseases such as inflammatory bowel diseases (IBD). The bi-directional interaction between gut microbiota and the brain is not completely understood. The aim of this review is to sum up the evidences concerning the role of the gut–brain microbiota axis in ischemic stroke and to highlight the more recent evidences about the potential role of the gut–brain microbiota axis in the interaction between inflammatory bowel disease and ischemic stroke.


2021 ◽  
Vol 22 (11) ◽  
pp. 5830
Author(s):  
Marina Romaní-Pérez ◽  
Clara Bullich-Vilarrubias ◽  
Inmaculada López-Almela ◽  
Rebeca Liébana-García ◽  
Marta Olivares ◽  
...  

Obesity currently represents a major societal and health challenge worldwide. Its prevalence has reached epidemic proportions and trends continue to rise, reflecting the need for more effective preventive measures. Hypothalamic circuits that control energy homeostasis in response to food intake are interesting targets for body-weight management, for example, through interventions that reinforce the gut-to-brain nutrient signalling, whose malfunction contributes to obesity. Gut microbiota–diet interactions might interfere in nutrient sensing and signalling from the gut to the brain, where the information is processed to control energy homeostasis. This gut microbiota–brain crosstalk is mediated by metabolites, mainly short chain fatty acids, secondary bile acids or amino acids-derived metabolites and subcellular bacterial components. These activate gut–endocrine and/or neural-mediated pathways or pass to systemic circulation and then reach the brain. Feeding time and dietary composition are the main drivers of the gut microbiota structure and function. Therefore, aberrant feeding patterns or unhealthy diets might alter gut microbiota–diet interactions and modify nutrient availability and/or microbial ligands transmitting information from the gut to the brain in response to food intake, thus impairing energy homeostasis. Herein, we update the scientific evidence supporting that gut microbiota is a source of novel dietary and non-dietary biological products that may beneficially regulate gut-to-brain communication and, thus, improve metabolic health. Additionally, we evaluate how the feeding time and dietary composition modulate the gut microbiota and, thereby, the intraluminal availability of these biological products with potential effects on energy homeostasis. The review also identifies knowledge gaps and the advances required to clinically apply microbiome-based strategies to improve the gut–brain axis function and, thus, combat obesity.


2021 ◽  
Vol 8 ◽  
Author(s):  
Uttam Kumar Jana ◽  
Naveen Kango ◽  
Brett Pletschke

The gut microbiota in the human body is an important component that plays a pivotal role in the ability of the host to prevent diseases and recover from these diseases. If the human microbiome changes for any reason, it affects the overall functioning of the host. Healthy and vigorous gut microbiota require dietary fiber supplementation. Recently, oligosaccharides have been found to play a significant role in the modulation of microbiota. Several such oligosaccharides, i.e., xylooligosaccharides (XOS), mannooligosaccharides (MOS), and arabino-xylooligosaccharides (AXOS), are derived from hemicellulosic macromolecules such as xylan, mannan, and arabino-xylan, respectively. These oligosaccharides serve as substrates for the probiotic production of health-promoting substances (short-chain fatty acids, branched chain amino acids etc.), which confer a variety of health benefits, including the prevention of some dreaded diseases. Among hemicellulose-derived oligosaccharides (HDOs), XOS have been largely explored, whereas, studies on MOS and AXOS are currently underway. HDOs, upon ingestion, help reduce morbidities by lowering populations of harmful or pathogenic bacteria. The ATP-binding cassette (ABC) transporters are mainly utilized for the uptake of oligosaccharides in probiotics. Butyrate generated by the selective fermentation of oligosaccharides, along with other short-chain fatty acids, reduces gut inflammation. Overall, oligosaccharides derived from hemicelluloses show a similar potential as conventional prebiotics and can be supplemented as functional foods. This review summarizes the role of HDOs in the alleviation of autoimmune diseases (inflammatory bowel disease, Crohn's disease), diabetes, urinary tract infection, cardiovascular diseases, and antimicrobial resistance (AMR) through the modulation of the gut microbiota. The mechanism of oligosaccharide utilization and disease mitigation is also explained.


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