The interplay between the intestinal microbiota and the brain

Humans coexist in a mutualistic relationship with the intestinal microbiota, a complex microbial ecosystem that resides largely in the distal bowel. The lower gastrointestinal tract contains almost 100 trillion microorganisms, most of which are bacteria. More than 1,000 bacterial species have been identified in this microbiota. The intestinal microbiota lives in a symbiotic relationship with the host. A bidirectional neurohumoral communication system, known as the gut–brain axis, integrates the host gut and brain activities (Mayer et al. 2015). Communication between the brain and gut occurs along a network of pathways collectively termed the brain-gut axis. The brain-gut axis encompass the CNS, ENS, sympathetic and parasympathetic branches of the autonomic nervous system, neuroendocrine and neuroimmune pathways, and the gut microbiota (Colins et al. 2012). The gut microbiota can signal to the brain via a number of pathways which include: regulating immune activity and the production of roinflammatory cytokines that can either stimulate the HPA axis to produce CRH, ACTH and cortisol, or directly impact on CNS immune activity; through the production of SCFAs such as propionate, butyrate, and acetate; the production of neurotransmitters which may enter circulation and cross the blood brain barrier; by modulating tryptophan metabolism and downstream metabolites, serotonin, kynurenic acid and quinolinic acid. Neuronal and spinal pathways, particularly afferent signaling pathways of the vagus nerve, are critical in mediating the effect of the gut microbiota on brain function and behavior. Microbial produced SCFAs and indole also impact on EC cells of the enteric nervous system (Romijn et al. 2008; Cani et al. 2013). The purpose of this presentation was to summarize our current knowledge regarding the role of microbiota in bottom-up pathways of communication in the gutbrain axis.

Environmental factors in multiple sclerosis

Chapter 12 - Gut Microbiota in Brain Development and Disorders of the CNS: Therapeutic Strategies Involving Dietary Modification, Pro- and Prebiotic Intervention, and Fecal Microbiota Transplantation (FMT) Therapy

The gut–brain axis (GBA) is a complex, bidirectional communication system between the central and enteric nervous systems and the gut microbiota. Increasing evidence points to its key role in the pathogenesis of neurodegenerative diseases and mood disorders, such as Parkinson’s disease, Alzheimer’s disease, multiple sclerosis, depression, and anxiety disorders. Communication within the GBA occurs through neural, immune, and endocrine pathways, with microbial metabolites-including short-chain fatty acids, tryptophan derivatives, and cytokines-playing a crucial role in neuroinflammatory and neurodegenerative processes. Gut dysbiosis, increased intestinal barrier permeability, and vagus nerve dysfunction link intestinal abnormalities with brain dysfunction. Preclinical and clinical studies suggest that modulation of the microbiota-through diet, probiotics, prebiotics, or fecal microbiota transplantation-may have therapeutic potential in neuropsychiatric and neurodegenerative diseases. However, individual variability, methodological limitations, and ethical considerations hinder the practical implementation of these strategies in clinical practice. Understanding the functioning of the gut–brain axis may open new avenues for the prevention and treatment of neurological and psychiatric disorders through targeted interventions on the gut microbiota.

Brain and the gastrointestinal (GI) tract are intimately connected to form a bidirectional neurohumoral communication system. The communication between gut and brain, knows as the gut-brain axis, is so well established that the functional status of gut is always related to the condition of brain. The researches on the gut-brain axis were traditionally focused on the psychological status affecting the function of the GI tract. However, recent evidences showed that gut microbiota communicates with the brain via the gut-brain axis to modulate brain development and behavioral phenotypes. These recent findings on the new role of gut microbiota in the gut-brain axis implicate that gut microbiota could associate with brain functions as well as neurological diseases via the gut-brain axis. To elucidate the role of gut microbiota in the gut-brain axis, precise identification of the composition of microbes constituting gut microbiota is an essential step. However, identification of microbes constituting gut microbiota has been the main technological challenge currently due to massive amount of intestinal microbes and the difficulties in culture of gut microbes. Current methods for identification of microbes constituting gut microbiota are dependent on omics analysis methods by using advanced high tech equipment. Here, we review the association of gut microbiota with the gut-brain axis, including the pros and cons of the current high throughput methods for identification of microbes constituting gut microbiota to elucidate the role of gut microbiota in the gut-brain axis.

History is full of women who made enormous contributions to science. While there is little to no imbalance at the early career stage, a decreasing proportion of women is found as seniority increases. In the multiple sclerosis (MS) field, 44% of first authors and only 35% of senior authors were female. So, in this review, we highlight ground-breaking research done by women in the field of MS, focusing mostly on their work as principal investigators. MS is an autoimmune disorder of the central nervous system (CNS), with evident paradigm shifts in the understating of its pathophysiology. It is known that the immune system becomes overactivated and attacks myelin sheath surrounding axons. The resulting demyelination disrupts the communication signals to and from the CNS, which causes unpredictable symptoms, depending on the neurons that are affected. Classically, MS was reported to cause mostly physical and motor disabilities. However, it is now recognized that cognitive impairment affects more than 50% of the MS patients. Another shifting paradigm was the involvement of gray matter in MS pathology, formerly considered to be a white matter disease. Additionally, the identification of different T cell immune subsets and the mechanisms underlying the involvement of B cells and peripheral macrophages provided a better understanding of the immunopathophysiological processes present in MS. Relevantly, the gut-brain axis, recognized as a bi-directional communication system between the CNS and the gut, was found to be crucial in MS. Indeed, gut microbiota influences not only different susceptibilities to MS pathology, but it can also be modulated in order to positively act in MS course. Also, after the identification of the first microRNA in 1993, the role of microRNAs has been investigated in MS, either as potential biomarkers or therapeutic agents. Finally, concerning MS therapeutical approaches, remyelination-based studies have arisen on the spotlight aiming to repair myelin loss/neuronal connectivity. Altogether, here we emphasize the new insights of remarkable women that have voiced the impact of cognitive impairment, white and gray matter pathology, immune response, and that of the CNS-peripheral interplay on MS diagnosis, progression, and/or therapy efficacy, leading to huge breakthroughs in the MS field.

In this paper, a scheme of a bidirectional hyperchaotic communication system is proposed. The hyperchaotic communication system including the transmitter and the receiver is composed of a pair of Chua circuit with coupling characteristics respectively. From the viewpoint of communication security, directly adopting the bidirectional communication system would provide a so-called "theoretical security". This is caused by the coupling relationship between the transmitter and the receiver. With the technique of frequency spectrum, the theoretical security of bidirectional communication systems can be proven. In other words, even if an intruder knows the parameter values of the system, he could not steal information from the system. As a result, it is not necessary for us to use the additional encryption. On the other hand, to achieve the synchronization of bidirectional communications, the method which applies a suitable Lyapunov function and the property of positive definite of a matrix is proposed to design the feedback controllers. Therefore, the message masked by chaotic signal from the transmitter can be perfectly recovered in the receiver. Finally, the simulation results can verify that the proposed method and the scheme of the bidirectional communication are favorable.

Covering the Cover

The gut-brain axis has been described as a bi-directional neuro-humeral communication system and is implicated in the pathogenesis of functional gastrointestinal disorders such as irritable bowel syndrome (IBS). Recent work has shown that a subset of patients with IBS show evidence of low grade immune activation and inflammation in the colonic mucosa. This review focuses on the role of the intestinal microbiota and discusses the interrelationship between the intestinal microbiota and maintaining of low grade inflammation, gut dysfunction or behavioral changes using murine models and clinical studies. The findings in murine models show that perturbation of gut flora is a putative mechanism for gut dysfunction in IBS and together with clinical studies they indicate that dysbiosis in patients with IBS psychiatric co-morbidity.

In order to achieve low-cost scalability, the same-wavelength bidirectional (SWB) fiber communication system is a better solution. We present a detailed investigation of the performance of the different orders Raman amplifiers in same-wavelength bidirectional fiber communication systems. We discuss how to suppress the main factor affecting system performance which is Rayleigh scattering noise (RSN). By using different Raman amplifiers to construct different quasi-lossless transmission, the performance changes in the same-wavelength bidirectional fiber optic communication system were studied. On this basis, multi-channel and same-wavelength single fiber bidirectional system experiments were conducted to compare the performance of second-order Raman systems and first-order Raman systems. The results indicate that the Rayleigh scattering suppression effect of second-order Raman systems is better, and compared to first-order Raman systems, the average signal-to-noise ratio (SNR) can be increased by 2.88 dB.

Every single human consists of thousands of genes, billions of neurons and trillions of bacteria. There is a rapidly growing number of data that links the gut microbiome to the development and functioning of the central nervous system, which is a currently proposed paradigm shift in neuroscience. Knowledge on the relationship between gut microbiota and mental disorders is constantly increasing. This phenomenon is known as "gut-brain axis". The strongest evidence for the role of microbes in the gut-brain axis comes from animal studies. Nevertheless, the gutbrain crosstalk is a bidirectional communication system that not only provides gastrointestinal homeostasis, but can also affect motivation as well as higher cognitive functions. Moreover, gut microbiome can be associated with obesity and inflammatory gastrointestinal disorders. According to the recent studies, there is a link between the composition of gut microbiota and mental disorders in animals (response to depression and chronic stress). This subject requires further examination, especially taking into consideration potential therapeutic options.

BackgroundThe gut–brain axis (GBA) represents a complex, bidirectional communication network that connects the central nervous system (CNS) and the gastrointestinal system. Our study aimed to explore the correlation between the intestinal microbiota and demyelinating diseases from a bibliometric perspective, focusing on research since 2014.MethodsA comprehensive search was carried out on the Web of Science Core Collection (WoSCC) to locate studies on the intestinal microbiota and demyelinating diseases, with a focus on publications from 1 January 2014 to 29 March 2024. We visualized and analyzed the data using VOSviewer, CiteSpace, and Charticulator.ResultsWe gathered 429 scholarly articles on the intestinal microbiota and demyelinating disorders published in the past 10 years. Research concerning the intestinal microbiota and demyelinating diseases has demonstrated a consistent increase in frequency over time. The USA has the highest number of publications, while Canada has the highest average number of citations, reaching as high as 3,429, which is greater than that of the USA. Moreover, the journal with the highest number of publications was Frontiers in Immunology, with 33 publications and 1,494 citations. The majority of the scholars focused on “multiple sclerosis” and “gut microbiota,” which are the primary keywords in the field of the intestinal microbiota and demyelinating diseases.ConclusionThis study conducted a comprehensive analysis of existing research investigating the correlation between the intestinal microbiota and demyelinating diseases. Using advanced bibliometric tools such as VOSviewer and CiteSpace, this study analyzed the intricate relationship between the intestinal microbiota and the pathogenesis of demyelinating conditions. In addition, the study used literature statistical analysis to identify research hotspots and future directions in the field.

We present the bidirectional power line communication system developed in parallel to an electronic board for driving and control of HID (high-intensity discharge) and LED (light-emitting diode) lamps. The communication system, developed to be applied in the sector of public illumination, is been designed to combine high efficiency and reliability with low production costs; it consists indeed of discrete cheap components. The communication system described in this paper implements the technique of transporting digital information over existing power lines, avoiding the issue of installing new cables. Digitized signals can use power line cables through the amplitude voltage and current modulation. The solution proposed is more advantageous compared to communication techniques currently on the market which are essentially two types, power line carrier (modem for high-voltage lines) or radio (zig-Bee transceiver).

The bidirectional communication between the gut and central nervous system (CNS) through microbiota is known as the microbiota–gut–brain axis. The brain, through the enteric neural innervation and the vagus nerve, influences the gut physiological activities (motility, mucin, and peptide secretion), as well as the development of the mucosal immune system. Conversely, the gut can influence the CNS via intestinal microbiota, its metabolites, and gut-homing immune cells. Growing evidence suggests that gut immunity is critically involved in gut–brain communication during health and diseases, including multiple sclerosis (MS). The gut microbiota can influence the development and function of gut immunity, and conversely, the innate and adaptive mucosal immunity can influence microbiota composition. Gut and systemic immunity, along with gut microbiota, are perturbed in MS. Diet and disease-modifying therapies (DMTs) can affect the composition of the gut microbial community, leading to changes in gut and peripheral immunity, which ultimately affects MS. A high-fat diet is highly associated with gut dysbiosis-mediated inflammation and intestinal permeability, while a high-fiber diet/short-chain fatty acids (SCFAs) can promote the development of Foxp3 Tregs and improvement in intestinal barrier function, which subsequently suppress CNS autoimmunity in the animal model of MS (experimental autoimmune encephalomyelitis or EAE). This review will address the role of gut immunity and its modulation by diet and DMTs via gut microbiota during MS pathophysiology.

The role of IL-23/IL-17 axis in ischemic stroke from the perspective of gut-brain axis