scholarly journals A Budding Relationship: Bacterial Extracellular Vesicles in the Microbiota-Gut-Brain Axis

2020 ◽  
Vol 21 (23) ◽  
pp. 8899
Author(s):  
Sandor Haas-Neill ◽  
Paul Forsythe

The discovery of the microbiota-gut-brain axis has revolutionized our understanding of systemic influences on brain function and may lead to novel therapeutic approaches to neurodevelopmental and mood disorders. A parallel revolution has occurred in the field of intercellular communication, with the realization that endosomes, and other extracellular vesicles, rival the endocrine system as regulators of distant tissues. These two paradigms shifting developments come together in recent observations that bacterial membrane vesicles contribute to inter-kingdom signaling and may be an integral component of gut microbe communication with the brain. In this short review we address the current understanding of the biogenesis of bacterial membrane vesicles and the roles they play in the survival of microbes and in intra and inter-kingdom communication. We identify recent observations indicating that bacterial membrane vesicles, particularly those derived from probiotic organisms, regulate brain function. We discuss mechanisms by which bacterial membrane vesicles may influence the brain including interaction with the peripheral nervous system, and modulation of immune activity. We also review evidence suggesting that, unlike the parent organism, gut bacteria derived membrane vesicles are able to deliver cargo, including neurotransmitters, directly to the central nervous system and may thus constitute key components of the microbiota-gut-brain axis.

2018 ◽  
Vol 94 (1114) ◽  
pp. 446-452 ◽  
Author(s):  
Borros M Arneth

BackgroundThe gut–brain axis facilitates a critical bidirectional link and communication between the brain and the gut. Recent studies have highlighted the significance of interactions in the gut–brain axis, with a particular focus on intestinal functions, the nervous system and the brain. Furthermore, researchers have examined the effects of the gut microbiome on mental health and psychiatric well-being.The present study reviewed published evidence to explore the concept of the gut–brain axis.AimsThis systematic review investigated the relationship between human brain function and the gut–brain axis.MethodsTo achieve these objectives, peer-reviewed articles on the gut–brain axis were identified in various electronic databases, including PubMed, MEDLINE, CIHAHL, Web of Science and PsycINFO.ResultsData obtained from previous studies showed that the gut–brain axis links various peripheral intestinal functions to brain centres through a broad range of processes and pathways, such as endocrine signalling and immune system activation. Researchers have found that the vagus nerve drives bidirectional communication between the various systems in the gut–brain axis. In humans, the signals are transmitted from the liminal environment to the central nervous system.ConclusionsThe communication that occurs in the gut–brain axis can alter brain function and trigger various psychiatric conditions, such as schizophrenia and depression. Thus, elucidation of the gut–brain axis is critical for the management of certain psychiatric and mental disorders.


It was in 1895 that Oliver & Schafer discovered the pressor activity of glycerol extracts of the pituitary. By 1928 it was clear that this activity, called vasopressin, was due to a peptide derived from the neural lobes of the pituitary and, in the early fifties, its structure and that of its ‘twin’, oxytocin, were determined by du Vigneaud and his colleagues, who were also able to prepare them synthetically. For a long time these two peptides, which were clearly of neural origin, were thought to have only peripheral physiological actions. However, evidence has gradually accumulated that these as well as some hormonal peptides not of neural origin, such as angiotensin and corticotrophin, could have actions on the central nervous system. The discovery of the enkephalins by Hughes & Kosterlitz in 1975 revealed the presence of an oligopeptide in the forebrain that could influence brain function and for which a specific receptor could be delineated which provided an immediate connection with the well documented non-peptide analgesic drugs of the morphine group. Within a short time discrete localization both of enkaphalin stores and of enkephalin receptors within the nervous system was demonstrated. In the ensuing period a growing number of peptides have either been isolated from the brain or have been inferred, from immunological evidence, to be present. Some of these peptides, such as insulin and gastrin, have well established peripheral biological actions, and their presence in the brain has engendered considerable surprise.


2020 ◽  
Vol 21 (23) ◽  
pp. 9111
Author(s):  
José Antonio López-Guerrero ◽  
Inés Ripa ◽  
Sabina Andreu ◽  
Raquel Bello-Morales

It is being increasingly demonstrated that extracellular vesicles (EVs) are deeply involved in the physiology of the central nervous system (CNS). Processes such as synaptic activity, neuron-glia communication, myelination and immune response are modulated by EVs. Likewise, these vesicles may participate in many pathological processes, both as triggers of disease or, on the contrary, as mechanisms of repair. EVs play relevant roles in neurodegenerative disorders such as Alzheimer’s or Parkinson’s diseases, in viral infections of the CNS and in demyelinating pathologies such as multiple sclerosis (MS). This review describes the involvement of these membrane vesicles in major demyelinating diseases, including MS, neuromyelitis optica, progressive multifocal leukoencephalopathy and demyelination associated to herpesviruses.


2021 ◽  
Vol 15 ◽  
Author(s):  
Yadaly Gassama ◽  
Alexandre Favereaux

Extracellular vesicles or EVs are secreted by most, if not all, eukaryote cell types and recaptured by neighboring or distant cells. Their cargo, composed of a vast diversity of proteins, lipids, and nucleic acids, supports the EVs’ inter-cellular communication. The role of EVs in many cellular processes is now well documented both in physiological and pathological conditions. In this review, we focus on the role of EVs in the central nervous system (CNS) in physiological as well as pathological conditions such as neurodegenerative diseases or brain cancers. We also discuss the future of EVs in clinical research, in particular, their value as biomarkers as well as innovative therapeutic agents. While an increasing number of studies reveal EV research as a promising field, progress in the standardization of protocols and innovation in analysis as well as in research tools is needed to make a breakthrough in our understanding of their impact in the pathophysiology of the brain.


1958 ◽  
Vol 104 (437) ◽  
pp. 1149-1159 ◽  
Author(s):  
R. Rodnight ◽  
E. K. Aves

A role in mental illness for an aberrant metabolism of indole compounds was first advanced some sixty years ago, when their alleged toxicity to the nervous system figured prominently in the then current theory of auto-intoxication by bacterial action in the bowel (Herter, 1898, 1907). Although in a modified form it continues to receive the support of Buscaino (1958), auto-intoxication of this nature is now generally rejected as a factor in mental illness (see particularly Alvarez, 1924) and the renewed interest in indoles and brain function of recent years has come from a different standpoint. Thus, study of the central nervous system effects of indoles such as 5-hydroxytryptamine (serotonin) and bufotenin, and of compounds containing an indole group such as lysergic acid and reserpine, has inspired several new theories concerning normal and abnormal roles for indoles in the brain (Woolley and Shaw, 1957; Brodie and Shore, 1957; Hoffer, 1957).


Author(s):  
S.S. Spicer ◽  
B.A. Schulte

Generation of monoclonal antibodies (MAbs) against tissue antigens has yielded several (VC1.1, HNK- 1, L2, 4F4 and anti-leu 7) which recognize the unique sugar epitope, glucuronyl 3-sulfate (Glc A3- SO4). In the central nervous system, these MAbs have demonstrated Glc A3-SO4 at the surface of neurons in the cerebral cortex, the cerebellum, the retina and other widespread regions of the brain.Here we describe the distribution of Glc A3-SO4 in the peripheral nervous system as determined by immunostaining with a MAb (VC 1.1) developed against antigen in the cat visual cortex. Outside the central nervous system, immunoreactivity was observed only in peripheral terminals of selected sensory nerves conducting transduction signals for touch, hearing, balance and taste. On the glassy membrane of the sinus hair in murine nasal skin, just deep to the ringwurt, VC 1.1 delineated an intensely stained, plaque-like area (Fig. 1). This previously unrecognized structure of the nasal vibrissae presumably serves as a tactile end organ and to our knowledge is not demonstrable by means other than its selective immunopositivity with VC1.1 and its appearance as a densely fibrillar area in H&E stained sections.


Author(s):  
Grazia Tagliafierro ◽  
Cristiana Crosa ◽  
Marco Canepa ◽  
Tiziano Zanin

Barnacles are very specialized Crustacea, with strongly reduced head and abdomen. Their nervous system is rather simple: the brain or supra-oesophageal ganglion (SG) is a small bilobed structure and the toracic ganglia are fused into a single ventral mass, the suboesophageal ganglion (VG). Neurosecretion was shown in barnacle nervous system by histochemical methods and numerous putative hormonal substances were extracted and tested. Recently six different types of dense-core granules were visualized in the median ocellar nerve of Balanus hameri and serotonin and FMRF-amide like substances were immunocytochemically detected in the nervous system of Balanus amphitrite. The aim of the present work is to localize and characterize at ultrastructural level, neurosecretory neuron cell bodies in the VG of Balanus amphitrite.Specimens of Balanus amphitrite were collected in the port of Genova. The central nervous system were Karnovsky fixed, osmium postfixed, ethanol dehydrated and Durcupan ACM embedded. Ultrathin sections were stained with uranyl acetate and lead citrate. Ultrastructural observations were made on a Philips M 202 and Zeiss 109 T electron microscopy.


2018 ◽  
Vol 23 (1) ◽  
pp. 10-13
Author(s):  
James B. Talmage ◽  
Jay Blaisdell

Abstract Injuries that affect the central nervous system (CNS) can be catastrophic because they involve the brain or spinal cord, and determining the underlying clinical cause of impairment is essential in using the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), in part because the AMA Guides addresses neurological impairment in several chapters. Unlike the musculoskeletal chapters, Chapter 13, The Central and Peripheral Nervous System, does not use grades, grade modifiers, and a net adjustment formula; rather the chapter uses an approach that is similar to that in prior editions of the AMA Guides. The following steps can be used to perform a CNS rating: 1) evaluate all four major categories of cerebral impairment, and choose the one that is most severe; 2) rate the single most severe cerebral impairment of the four major categories; 3) rate all other impairments that are due to neurogenic problems; and 4) combine the rating of the single most severe category of cerebral impairment with the ratings of all other impairments. Because some neurological dysfunctions are rated elsewhere in the AMA Guides, Sixth Edition, the evaluator may consult Table 13-1 to verify the appropriate chapter to use.


2018 ◽  
Vol 25 (28) ◽  
pp. 3333-3352 ◽  
Author(s):  
Natalia Pessoa Rocha ◽  
Ana Cristina Simoes e Silva ◽  
Thiago Ruiz Rodrigues Prestes ◽  
Victor Feracin ◽  
Caroline Amaral Machado ◽  
...  

Background: The Renin-Angiotensin System (RAS) is a key regulator of cardiovascular and renal homeostasis, but also plays important roles in mediating physiological functions in the central nervous system (CNS). The effects of the RAS were classically described as mediated by angiotensin (Ang) II via angiotensin type 1 (AT1) receptors. However, another arm of the RAS formed by the angiotensin converting enzyme 2 (ACE2), Ang-(1-7) and the Mas receptor has been a matter of investigation due to its important physiological roles, usually counterbalancing the classical effects exerted by Ang II. Objective: We aim to provide an overview of effects elicited by the RAS, especially Ang-(1-7), in the brain. We also aim to discuss the therapeutic potential for neuropsychiatric disorders for the modulation of RAS. Method: We carried out an extensive literature search in PubMed central. Results: Within the brain, Ang-(1-7) contributes to the regulation of blood pressure by acting at regions that control cardiovascular functions. In contrast with Ang II, Ang-(1-7) improves baroreflex sensitivity and plays an inhibitory role in hypothalamic noradrenergic neurotransmission. Ang-(1-7) not only exerts effects related to blood pressure regulation, but also acts as a neuroprotective component of the RAS, for instance, by reducing cerebral infarct size, inflammation, oxidative stress and neuronal apoptosis. Conclusion: Pre-clinical evidence supports a relevant role for ACE2/Ang-(1-7)/Mas receptor axis in several neuropsychiatric conditions, including stress-related and mood disorders, cerebrovascular ischemic and hemorrhagic lesions and neurodegenerative diseases. However, very few data are available regarding the ACE2/Ang-(1-7)/Mas receptor axis in human CNS.


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