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Abstract
OBJECTIVE An aetiological link between acute infection and major depression has long been hypothesized, and is increasingly gaining recognition within contemporary literature. This review aims to examine the evidence for such a link, specifically between acute, self-limiting infection and major depression, and to summarize the current understanding of pathophysiological mechanisms underlying this link. METHODS Relevant articles were sourced via an online search of published literature from Embase, MEDLINE, PsycINFO and PubMed using a variety of search terms including mood disorder, depression, infection and inflammation. Additionally, a search for articles from the bibliographies of retrieved papers was conducted. RESULTS Findings from retrospective studies suggest an association between infection and subsequent mood disturbance, including major depression. This association has been confirmed by studies employing prospective observational or experimental challenge designs. The available evidence supports a multifactorial basis of vulnerability towards major depression in the context of acute infection. Genetic, neuroendocrine, autonomic and psychosocial factors may interact to potentiate the likelihood of a severe and prolonged depressive response to an immunological stressor in some individuals. CONCLUSION Mood disturbance is likely to have a host-protective role in the context of an acute sickness response to infection. However, this usually adaptive and reversible response may progress in some vulnerable individuals into a more sustained and severe pattern of behavioural and physiological changes of major depression. Further research is needed to delineate the factors that predispose, precipitate and perpetuate depression in the context of acute infective illness. Such insights will inform effective prevention and treatment strategies.
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Affiliation(s)
- Pramudie Gunaratne
- 1Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, Australia
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52
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Ringel Y, Maharshak N. Intestinal microbiota and immune function in the pathogenesis of irritable bowel syndrome. Am J Physiol Gastrointest Liver Physiol 2013; 305:G529-41. [PMID: 23886861 PMCID: PMC3798736 DOI: 10.1152/ajpgi.00207.2012] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 07/17/2013] [Indexed: 02/08/2023]
Abstract
The pathophysiology of irritable bowel syndrome (IBS) is believed to involve alterations in the brain-gut axis; however, the etiological triggers and mechanisms by which these changes lead to symptoms of IBS remain poorly understood. Although IBS is often considered a condition without an identified "organic" etiology, emerging evidence suggests that alterations in the gastrointestinal microbiota and altered immune function may play a role in the pathogenesis of the disorder. These recent data suggest a plausible model in which changes in the intestinal microbiota and activation of the enteric immune system may impinge upon the brain-gut axis, causing the alterations in gastrointestinal function and the clinical symptoms observed in patients with IBS. This review summarizes the current evidence for altered intestinal microbiota and immune function in IBS. It discusses the potential etiological role of these factors, suggests an updated conceptual model for the pathogenesis of the disorder, and identifies areas for future research.
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Affiliation(s)
- Yehuda Ringel
- Division of Gastroenterology and Hepatology, Univ. of North Carolina at Chapel Hill School of Medicine, 4107 BioInformatics Bldg., CB# 7080, 130 Mason Farm Rd., Chapel Hill, NC 27599-7080.
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53
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Effects of afferent and efferent denervation of vagal nerve on endotoxin-induced oxidative stress in rats. J Neural Transm (Vienna) 2013; 120:1673-88. [PMID: 23794033 DOI: 10.1007/s00702-013-1053-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Accepted: 06/11/2013] [Indexed: 10/26/2022]
Abstract
This study investigated the role of vagal innervation in oxidative stress after systemic administration of lipopolysaccharide (LPS) endotoxin. Control rats and rats subjected to bilateral subdiaphragmatic vagotomy, perivagal capsaicin application (5 mg/ml) or cholinergic receptor blockade with subcutaneous atropine (1 mg/kg), were intraperitoneally injected with 300 μg/kg of LPS and euthanized 4 h later. Results indicated that; (1) surgical vagotomy and sensory denervation by perivagal capsaicin increased brain oxidative stress and decreased reduced glutathione in basal condition (saline-treated rats) and following endotoxin challenge; (2) oxidative stress decreased after cholinergic blockade with atropine in endotoxemic rats; (3) nitric oxide decreased by abdominal vagotomy, sensory deafferentation and cholinergic blockade after endotoxin injection; (4) liver lipid peroxidation decreased after surgical vagotomy and cholinergic blockade but increased after sensory deafferentation; (5) liver reduced glutathione decreased following vagotomy and sensory denervation in basal state and by cholinergic blockade in basal state and during endotoxemia; (6) nitric oxide increased by vagotomy in basal state and by sensory denervation and cholinergic blockade in basal state and during endotoxemia; (7) liver histological damage increased by subdiaphragmatic vagotomy, sensory denervation or cholinergic blockade. These findings suggest that: (1) sensory fibers (signals from the periphery) running in the vagus nerves are important in maintaining the redox status of the brain; (2) capsaicin vagal sensory nerves are likely to maintain nitric oxide tone in basal conditions; (3) the vagus nerve modulates liver redox status and nitric oxide release, (4) the vagus nerve mediates protective role in the liver with both cholinergic and capsaicin-sensitive mechanisms being involved.
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54
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Clarke G, Grenham S, Scully P, Fitzgerald P, Moloney RD, Shanahan F, Dinan TG, Cryan JF. The microbiome-gut-brain axis during early life regulates the hippocampal serotonergic system in a sex-dependent manner. Mol Psychiatry 2013; 18:666-73. [PMID: 22688187 DOI: 10.1038/mp.2012.77] [Citation(s) in RCA: 1221] [Impact Index Per Article: 111.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Bacterial colonisation of the intestine has a major role in the post-natal development and maturation of the immune and endocrine systems. These processes are key factors underpinning central nervous system (CNS) signalling. Regulation of the microbiome-gut-brain axis is essential for maintaining homeostasis, including that of the CNS. However, there is a paucity of data pertaining to the influence of microbiome on the serotonergic system. Germ-free (GF) animals represent an effective preclinical tool to investigate such phenomena. Here we show that male GF animals have a significant elevation in the hippocampal concentration of 5-hydroxytryptamine and 5-hydroxyindoleacetic acid, its main metabolite, compared with conventionally colonised control animals. Moreover, this alteration is sex specific in contrast with the immunological and neuroendocrine effects which are evident in both sexes. Concentrations of tryptophan, the precursor of serotonin, are increased in the plasma of male GF animals, suggesting a humoral route through which the microbiota can influence CNS serotonergic neurotransmission. Interestingly, colonisation of the GF animals post weaning is insufficient to reverse the CNS neurochemical consequences in adulthood of an absent microbiota in early life despite the peripheral availability of tryptophan being restored to baseline values. In addition, reduced anxiety in GF animals is also normalised following restoration of the intestinal microbiota. These results demonstrate that CNS neurotransmission can be profoundly disturbed by the absence of a normal gut microbiota and that this aberrant neurochemical, but not behavioural, profile is resistant to restoration of a normal gut flora in later life.
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Affiliation(s)
- G Clarke
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.
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55
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TILLISCH KIRSTEN, LABUS JENNIFER, KILPATRICK LISA, JIANG ZHIGUO, STAINS JEAN, EBRAT BAHAR, GUYONNET DENIS, LEGRAIN–RASPAUD SOPHIE, TROTIN BEATRICE, NALIBOFF BRUCE, MAYER EMERANA. Consumption of fermented milk product with probiotic modulates brain activity. Gastroenterology 2013; 144:1394-401, 1401.e1-4. [PMID: 23474283 PMCID: PMC3839572 DOI: 10.1053/j.gastro.2013.02.043] [Citation(s) in RCA: 713] [Impact Index Per Article: 64.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 01/30/2013] [Accepted: 02/27/2013] [Indexed: 12/14/2022]
Abstract
BACKGROUND & AIMS Changes in gut microbiota have been reported to alter signaling mechanisms, emotional behavior, and visceral nociceptive reflexes in rodents. However, alteration of the intestinal microbiota with antibiotics or probiotics has not been shown to produce these changes in humans. We investigated whether consumption of a fermented milk product with probiotic (FMPP) for 4 weeks by healthy women altered brain intrinsic connectivity or responses to emotional attention tasks. METHODS Healthy women with no gastrointestinal or psychiatric symptoms were randomly assigned to groups given FMPP (n = 12), a nonfermented milk product (n = 11, controls), or no intervention (n = 13) twice daily for 4 weeks. The FMPP contained Bifidobacterium animalis subsp Lactis, Streptococcus thermophiles, Lactobacillus bulgaricus, and Lactococcus lactis subsp Lactis. Participants underwent functional magnetic resonance imaging before and after the intervention to measure brain response to an emotional faces attention task and resting brain activity. Multivariate and region of interest analyses were performed. RESULTS FMPP intake was associated with reduced task-related response of a distributed functional network (49% cross-block covariance; P = .004) containing affective, viscerosensory, and somatosensory cortices. Alterations in intrinsic activity of resting brain indicated that ingestion of FMPP was associated with changes in midbrain connectivity, which could explain the observed differences in activity during the task. CONCLUSIONS Four-week intake of an FMPP by healthy women affected activity of brain regions that control central processing of emotion and sensation.
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Affiliation(s)
- KIRSTEN TILLISCH
- Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - JENNIFER LABUS
- Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - LISA KILPATRICK
- Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - ZHIGUO JIANG
- Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - JEAN STAINS
- Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - BAHAR EBRAT
- Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California
| | | | | | | | - BRUCE NALIBOFF
- Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - EMERAN A. MAYER
- Oppenheimer Family Center for Neurobiology of Stress, Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California
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56
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Los FCO, Ha C, Aroian RV. Neuronal Goα and CAPS regulate behavioral and immune responses to bacterial pore-forming toxins. PLoS One 2013; 8:e54528. [PMID: 23349920 PMCID: PMC3547950 DOI: 10.1371/journal.pone.0054528] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 12/12/2012] [Indexed: 12/13/2022] Open
Abstract
Pore-forming toxins (PFTs) are abundant bacterial virulence factors that attack host cell plasma membranes. Host defense mechanisms against PFTs described to date all function in the host tissue that is directly attacked by the PFT. Here we characterize a rapid and fully penetrant cessation of feeding of Caenorhabditis elegans in response to PFT attack. We demonstrate via analyses of C. elegans mutants that inhibition of feeding by PFT requires the neuronal G protein Goα subunit goa-1, and that maintenance of this response requires neuronally expressed calcium activator for protein secretion (CAPS) homolog unc-31. Independently from their role in feeding cessation, we find that goa-1 and unc-31 are additionally required for immune protection against PFTs. We thus demonstrate that the behavioral and immune responses to bacterial PFT attack involve the cross-talk between the nervous system and the cells directly under attack.
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Affiliation(s)
- Ferdinand C. O. Los
- University of California San Diego, Division of Biological Sciences, Section of cell and developmental biology, La Jolla, California, United States of America
| | - Christine Ha
- University of California San Diego, Division of Biological Sciences, Section of cell and developmental biology, La Jolla, California, United States of America
| | - Raffi V. Aroian
- University of California San Diego, Division of Biological Sciences, Section of cell and developmental biology, La Jolla, California, United States of America
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57
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Perez-Burgos A, Wang B, Mao YK, Mistry B, McVey Neufeld KA, Bienenstock J, Kunze W. Psychoactive bacteria Lactobacillus rhamnosus (JB-1) elicits rapid frequency facilitation in vagal afferents. Am J Physiol Gastrointest Liver Physiol 2013; 304:G211-20. [PMID: 23139216 DOI: 10.1152/ajpgi.00128.2012] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mounting evidence supports the influence of the gut microbiome on the local enteric nervous system and its effects on brain chemistry and relevant behavior. Vagal afferents are involved in some of these effects. We previously showed that ingestion of the probiotic bacterium Lactobacillus rhamnosus (JB-1) caused extensive neurochemical changes in the brain and behavior that were abrogated by prior vagotomy. Because information can be transmitted to the brain via primary afferents encoded as neuronal spike trains, our goal was to record those induced by JB-1 in vagal afferents in the mesenteric nerve bundle and thus determine the nature of the signals sent to the brain. Male Swiss Webster mice jejunal segments were cannulated ex vivo, and serosal and luminal compartments were perfused separately. Bacteria were added intraluminally. We found no evidence for translocation of labeled bacteria across the epithelium during the experiment. We recorded extracellular multi- and single-unit neuronal activity with glass suction pipettes. Within minutes of application, JB-1 increased the constitutive single- and multiunit firing rate of the mesenteric nerve bundle, but Lactobacillus salivarius (a negative control) or media alone were ineffective. JB-1 significantly augmented multiunit discharge responses to an intraluminal distension pressure of 31 hPa. Prior subdiaphragmatic vagotomy abolished all of the JB-1-evoked effects. This detailed exploration of the neuronal spike firing that encodes behavioral signaling to the brain may be useful to identify effective psychoactive bacteria and thereby offer an alternative new perspective in the field of psychiatry and comorbid conditions.
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Affiliation(s)
- Azucena Perez-Burgos
- McMaster Brain-Body Institute, St. Joseph's Healthcare, Hamilton, Ontario, Canada.
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58
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Arnett SV, Clark IA. Inflammatory fatigue and sickness behaviour - lessons for the diagnosis and management of chronic fatigue syndrome. J Affect Disord 2012; 141:130-42. [PMID: 22578888 DOI: 10.1016/j.jad.2012.04.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 04/09/2012] [Accepted: 04/09/2012] [Indexed: 12/18/2022]
Abstract
Persistent and severe fatigue is a common part of the presentation of a diverse range of disease processes. There is a growing body of evidence indicating a common inflammatory pathophysiology underlying many conditions where fatigue is a primary patient concern, including chronic fatigue syndrome. This review explores current models of how inflammatory mediators act on the central nervous system to produce fatigue and sickness behaviour, and the commonality of these processes in conditions as diverse as surgical trauma, infection, various cancers, inflammatory bowel disease, connective tissue diseases and autoimmune diseases. We also discuss evidence indicating chronic fatigue syndrome may have important pathophysiological similarities with cytokine mediated sickness behaviour, and what lessons can be applied from sickness behaviour to chronic fatigue syndrome with regards to the diagnosis and management.
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Affiliation(s)
- S V Arnett
- Research School of Biology, Australian National University, Australia.
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59
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Benson S, Engler H, Schedlowski M, Elsenbruch S. Experimental endotoxemia as a model to study neuroimmune mechanisms in human visceral pain. Ann N Y Acad Sci 2012; 1262:108-17. [PMID: 22823442 DOI: 10.1111/j.1749-6632.2012.06622.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The administration of bacterial endotoxin (i.e., lipopolysaccharide, LPS) constitutes a well-established experimental approach to study the effects of an acute and transient immune activation on physiological, behavioral, and emotional aspects of sickness behavior in animals and healthy humans. However, little is known about possible effects of experimental endotoxemia on pain in humans. This knowledge gap is particularly striking in the context of visceral pain in functional as well as chronic-inflammatory gastrointestinal disorders. Although inflammatory processes have been implicated in the pathophysiology of visceral pain, it remains incompletely understood how inflammatory mediators interact with bottom-up (i.e., increased afferent input) and top-down (i.e., altered central pain processing) mechanisms of visceral hyperalgesia. Considering the recent findings of visceral hyperalgesia after LPS application in humans, in this review, we propose that experimental endotoxemia with its complex peripheral and central effects constitutes an experimental model to study neuroimmune communication in human pain research. We summarize and attempt to integrate relevant animal and human studies concerning neuroimmune communication in visceral and somatic pain, discuss putative mechanisms, and conclude with future research directions.
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Affiliation(s)
- Sven Benson
- Institute of Medical Psychology and Behavioral Immunobiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
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60
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Learned Immunosuppression: Extinction, Renewal, and the Challenge of Reconsolidation. J Neuroimmune Pharmacol 2012; 8:180-8. [DOI: 10.1007/s11481-012-9388-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 07/04/2012] [Indexed: 12/17/2022]
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61
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Maes M, Berk M, Goehler L, Song C, Anderson G, Gałecki P, Leonard B. Depression and sickness behavior are Janus-faced responses to shared inflammatory pathways. BMC Med 2012; 10:66. [PMID: 22747645 PMCID: PMC3391987 DOI: 10.1186/1741-7015-10-66] [Citation(s) in RCA: 403] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 06/29/2012] [Indexed: 12/21/2022] Open
Abstract
It is of considerable translational importance whether depression is a form or a consequence of sickness behavior. Sickness behavior is a behavioral complex induced by infections and immune trauma and mediated by pro-inflammatory cytokines. It is an adaptive response that enhances recovery by conserving energy to combat acute inflammation. There are considerable phenomenological similarities between sickness behavior and depression, for example, behavioral inhibition, anorexia and weight loss, and melancholic (anhedonia), physio-somatic (fatigue, hyperalgesia, malaise), anxiety and neurocognitive symptoms. In clinical depression, however, a transition occurs to sensitization of immuno-inflammatory pathways, progressive damage by oxidative and nitrosative stress to lipids, proteins, and DNA, and autoimmune responses directed against self-epitopes. The latter mechanisms are the substrate of a neuroprogressive process, whereby multiple depressive episodes cause neural tissue damage and consequent functional and cognitive sequelae. Thus, shared immuno-inflammatory pathways underpin the physiology of sickness behavior and the pathophysiology of clinical depression explaining their partially overlapping phenomenology. Inflammation may provoke a Janus-faced response with a good, acute side, generating protective inflammation through sickness behavior and a bad, chronic side, for example, clinical depression, a lifelong disorder with positive feedback loops between (neuro)inflammation and (neuro)degenerative processes following less well defined triggers.
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Affiliation(s)
- Michael Maes
- Maes Clinics @ TRIA, Piyavate Hospital, 998 Rimklongsamsen Road, Bangkok 10310, Thailand.
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62
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Lucini D, Pagani M. From stress to functional syndromes: an internist's point of view. Eur J Intern Med 2012; 23:295-301. [PMID: 22560374 DOI: 10.1016/j.ejim.2011.11.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 11/21/2011] [Accepted: 11/23/2011] [Indexed: 01/01/2023]
Abstract
In this brief review we address schematically the relationship between two emerging issues in clinical medicine: stress and functional syndromes. It is becoming increasingly clear that they demand a multidimensional approach, considering simultaneously elements of behavioral therapy with traditional pharmacological treatment, guided by a better physiopathological understanding including autonomic assessment. New techniques, based on innovative analysis of continuous segments of electrocardiogram and non invasive arterial pressure recordings capable to extract hidden oscillations, provide quantitative indices of sympathetic and vagal modulation of the cardiovascular system. This more complete diagnostic process facilitates explanation of symptoms and reassurance of patients, based on functional evidence. The described clinical approach implies in addition an active collaboration of patients requiring the implementation of a creative alliance. Physical exercise, eating habits and muscular-mental relaxation are combined with pharmacological tools as needed.
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Affiliation(s)
- Daniela Lucini
- Centro di Ricerca Terapia Neurovegetativa e Medicina dell'Esercizio, Dipartimento Scienze Cliniche, Università degli Studi di Milano, Italy.
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63
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Prager G, Hadamitzky M, Engler A, Doenlen R, Wirth T, Pacheco-López G, Krügel U, Schedlowski M, Engler H. Amygdaloid signature of peripheral immune activation by bacterial lipopolysaccharide or staphylococcal enterotoxin B. J Neuroimmune Pharmacol 2012; 8:42-50. [PMID: 22639228 DOI: 10.1007/s11481-012-9373-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Accepted: 04/27/2012] [Indexed: 01/21/2023]
Abstract
Activated immune cells produce soluble mediators that not only coordinate local and systemic immune responses but also act on the brain to initiate behavioral, neuroendocrine and metabolic adaptations. Earlier studies have shown that the amygdala, a group of nuclei located in the medial temporal lobe, is engaged in the central processing of afferent signals from the peripheral immune system. Here, we compared amygdaloid responses to lipopolysaccharide (LPS) and staphylococcal enterotoxin B (SEB), two prototypic bacterial products that elicit distinct immune responses. Intraperitoneal administration of LPS (0.1 mg/kg) or SEB (1 mg/kg) in adult rats induced substantial increases in amygdaloid neuronal activity as measured by intracerebral electroencephalography and c-fos gene expression. Amygdaloid neuronal activation was accompanied by an increase in anxiety-related behavior in the elevated plus-maze test. However, only treatment with LPS, but not SEB, enhanced amygdaloid IL-1β and TNF-α mRNA expression. This supports the view of the immune system as a sensory organ that recognizes invading pathogens and rapidly relays this information to the brain, independent of the nature of the immune response induced. The observation that neuronal and behavioral responses to peripheral immune challenges are not necessarily accompanied by increased brain cytokine expression suggests that cytokines are not the only factors driving sickness-related responses in the CNS.
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Affiliation(s)
- Geraldine Prager
- Institute of Medical Psychology and Behavioral Immunobiology, University Hospital Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
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64
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Gałecki P, Gałecka E, Maes M, Chamielec M, Orzechowska A, Bobińska K, Lewiński A, Szemraj J. The expression of genes encoding for COX-2, MPO, iNOS, and sPLA2-IIA in patients with recurrent depressive disorder. J Affect Disord 2012; 138:360-6. [PMID: 22331023 DOI: 10.1016/j.jad.2012.01.016] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2011] [Revised: 01/09/2012] [Accepted: 01/10/2012] [Indexed: 01/22/2023]
Abstract
BACKGROUND There is evidence that inflammation, oxidative and nitrosative stress (IO&NS) play a role in the pathophysiology of depression. There are also data indicating altered inflammatory gene expression in depressive disorder and that genetic variants of IO&NS genes are associated with increased risk of the disease in question. The aim of this study was to explore mRNA expression of four IO&NS genes PTGS2, MPO, NOS2A, and PLA2G2A coding respectively: cyclooxygenase-2 (COX-2), myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS) and secretory phospholipase A2 type IIA (sPLA2-IIA). METHOD Expression of the mRNA was determined using quantitative real-time PCR, in peripheral blood cells of patients with recurrent depressive disorder (rDD) and normal controls. RESULTS The mRNA expressions of the genes encoding for COX-2, MPO, iNOS and sPLA2-IIA were significantly increased in the peripheral blood cells of depressed patients versus controls. LIMITATIONS Patients were treated with antidepressants. CONCLUSION Our results indicate and may confirm the role of peripheral IO&NS pathways in the pathophysiology of depression. The results represent a promising way to investigate biological markers of depression.
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Affiliation(s)
- Piotr Gałecki
- Department of Adult Psychiatry, Medical University of Łódź, Poland.
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65
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Singh PK, Chopra K, Kuhad A, Kaur IP. Role of Lactobacillus acidophilus loaded floating beads in chronic fatigue syndrome: behavioral and biochemical evidences. Neurogastroenterol Motil 2012; 24:366-e170. [PMID: 22296294 DOI: 10.1111/j.1365-2982.2011.01861.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND In recent years the interface between neuropsychiatry and gastroenterology has converged in to a new discipline referred to as enteric neuroscience. Implications of brain-gut communication in the pathogenesis of psychiatric disorders indicate a possible role of suitably packaged/delivered probiotics as newer therapeutic options. In the present study probable role of per-oral administration of free Lactobacillus acidophilus (LAB) and LAB loaded alginate beads in attenuation of the symptoms associated with chronic fatigue syndrome (CFS) were evaluated. METHODS Chronic fatigue syndrome following physical fatigue was induced in rats by forcing them to swim (forced swim test; FST) in water till exhaustion, after weighing them down with 10% their body weight, daily for 28 days. Immobility (I) and postswim fatigue time (PSF) were taken as suitable markers. Free LAB and LAB loaded floating beads (FBs) were administered, from 21 to 28 days. KEY RESULTS Immobility and PSF were found to increase considerably in FST rats (665 ± 22 s and 196 ± 6 s) as compared with the naïve (32 ± 7 s and 22 ± 2 s) at 20 days, establishing severe fatigue like behavior. FST control group exhibited significant (P < 0.05) hypertrophy of spleen, hypotrophy of thymus, and increased oxido-nitrosative stress in brain and tumor necrosis factor-α (TNF-α) levels in serum. Treatment with LAB and LAB FBs significantly decreased I and PSF and attenuated (P < 0.05) oxido-nitrosative stress and TNF-α levels. Spleen and thymus were also restored to their original size in this group. CONCLUSIONS & INFERENCES The findings suggest a valuable therapeutic role of LAB especially when incorporated into alginate beads for the treatment of CFS.
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Affiliation(s)
- P K Singh
- University Institute of Pharmaceutical Sciences, UGC Centre of Advanced Study, Panjab University, Chandigarh 160014, India
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66
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Petitto JM, Huang Z, Meola D, Ha GK, Dauer D. Interleukin-2 and the septohippocampal system: intrinsic actions and autoimmune processes relevant to neuropsychiatric disorders. Methods Mol Biol 2012; 829:433-443. [PMID: 22231830 DOI: 10.1007/978-1-61779-458-2_27] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The effects of IL-2 on brain development, function, and disease are the result of IL-2's actions in the peripheral immune system and its intrinsic actions in the central nervous system (CNS). Determining whether, and under what circumstances (e.g., development, acute injury), these different actions of IL-2 are operative in the brain is essential to make significant advances in understanding the multifaceted affects of IL-2 on CNS function and disease, including psychiatric disorders. For several decades, there has been a great deal of speculation about the role of autoimmunity in brain disease. More recently, we have learned a great deal about the role of cytokines on neurobiological processes, and there have been many studies that have found peripheral immune alterations in patients with neurological and neuropsychiatric diseases. Despite a plethora of published literature, almost all of this data in humans is correlative and much of the basic research has understandably relied on simpler models (e.g., in vitro models). Good animal models such as our IL-2 knockout mouse model could provide valuable new insight into understanding how the complex biology of a cytokine such as IL-2 can have simultaneous, dynamic effects on multiple systems (e.g., regulating homeostasis in the brain and immune system, autoimmunity that can affect both systems). Animal models can also provide much needed new data elucidating neuroimmunological and autoimmune processes involved in brain development and disease. Such information may ultimately provide critical new insight into the role of brain cytokines and autoimmunity in prominent neurological and neuropsychiatric diseases (e.g., Alzheimer's disease, autism, multiple sclerosis, schizophrenia).
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Affiliation(s)
- John M Petitto
- Department of Psychiatry, McKnight Brain Institute, University of Florida, Gainesville, FL, USA.
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Petitto JM, Meola D, Huang Z. Interleukin-2 and the brain: dissecting central versus peripheral contributions using unique mouse models. Methods Mol Biol 2012; 934:301-11. [PMID: 22933152 DOI: 10.1007/978-1-62703-071-7_15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Although many studies have documented peripheral immune alterations in patients with psychiatric and neurological disorders, almost all these data in humans are correlative. The actions of IL-2 on neurodevelopment, function, and disease are the result of both IL-2's actions in the peripheral immune system and intrinsic actions in the CNS. Determining if, and under what conditions (e.g., development, acute injury) these different actions of IL-2 are operative in the brain is essential to make advances in understanding the multifaceted affects of IL-2 on CNS function and disease. Mouse models have provided ways to obtain new insights into how the complex biology of a cytokine such as IL-2 can have simultaneous, dynamic effects on multiple systems (e.g., regulating homeostasis in the brain and immune system, autoimmunity that can affect both systems). Here we describe some of the relevant literature and our research using different mouse models. This includes models such as congenic IL-2 knockout mice bred on immunodeficient backgrounds coupled with immune reconstitution strategies used to dissect neuroimmunological processes involved in the development of septohippocampal pathology, and test the hypothesis that dysregulation of the brain's endogenous neuroimmunological milieu may occur with the loss of brain IL-2 gene expression and be involved in initiating CNS autoimmunity. Use of animal models like these in the field of psychoneuroimmunology may lead to critical advances into our understanding of the role of brain cytokines and autoimmunity in neurodegenerative diseases (e.g., Alzheimer's disease), neurodevelopmental disorder (e.g., autism, schizophrenia), and autoimmune diseases including multiple sclerosis.
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Affiliation(s)
- John M Petitto
- Departments of Psychiatry, Neuroscience, and Pharmacology and Therapeutics, McKnight Brain Institute, University of Florida, Gainesville, FL, USA.
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68
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The potential role of probiotics in the management of childhood autism spectrum disorders. Gastroenterol Res Pract 2011; 2011:161358. [PMID: 22114588 PMCID: PMC3205659 DOI: 10.1155/2011/161358] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 08/20/2011] [Indexed: 12/14/2022] Open
Abstract
Gastrointestinal (GI) dysfunction has been reported in a substantial number of children with autism spectrum disorders (ASD). Activation of the mucosal immune response and the presence of abnormal gut microbiota are repeatedly observed in these children. In children with ASD, the presence of GI dysfunction is often associated with increased irritability, tantrums, aggressive behaviour, and sleep disturbances. Moreover, modulating gut bacteria with short-term antibiotic treatment can lead to temporary improvement in behavioral symptoms in some individuals with ASD. Probiotics can influence microbiota composition and intestinal barrier function and alter mucosal immune responses. The administration of probiotic bacteria to address changes in the microbiota might, therefore, be a useful novel therapeutic tool with which to restore normal gut microbiota, reduce inflammation, restore epithelial barrier function, and potentially ameliorate behavioural symptoms associated with some children with ASD. In this review of the literature, support emerges for the clinical testing of probiotics in ASD, especially in the context of addressing GI symptoms.
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Hennessy MB, Fitch C, Jacobs S, Deak T, Schiml PA. Behavioral effects of peripheral corticotropin-releasing factor during maternal separation may be mediated by proinflammatory activity. Psychoneuroendocrinology 2011; 36:996-1004. [PMID: 21255937 PMCID: PMC3568995 DOI: 10.1016/j.psyneuen.2010.12.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 12/08/2010] [Accepted: 12/21/2010] [Indexed: 12/01/2022]
Abstract
When guinea pig pups are separated from their mothers in a novel environment, an initial period of active behavior (vocalizing, locomotor activity) wanes after an hour or so and is replaced by a second, passive stage characterized by a crouched stance, closed eyes, and extensive piloerection. If pups are given a peripheral injection of 7-14μg of corticotropin-releasing factor (CRF) prior to testing, the passive behaviors occur immediately upon separation. We found that intracerebroventricular infusion of 1-10μg of CRF did not increase passive behavior relative to vehicle infusion, but that peripheral injection of the anti-inflammatory cytokine, interleukin-10, attenuated the passive behavior induced by peripheral CRF injection. These results together with previous findings suggest that peripheral CRF administration affects behavior of separated guinea pig pups through a mechanism that involves peripheral proinflammatory activity. The possible role of endogenous peripheral CRF in the behavioral response of untreated pups during maternal separation is considered.
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Affiliation(s)
- Michael B. Hennessy
- Department of Psychology, Wright State University, Dayton OH, 45435, United States,Address Correspondence to: Michael B. Hennessy, PhD, Department of Psychology, 335 Fawcett Hall, Wright State University, 3640 Col. Glenn Hwy., Dayton, OH 45435, , Tel: 937.775.2943, FAX: 937.775.3347
| | - Christopher Fitch
- Department of Psychology, Wright State University, Dayton OH, 45435, United States
| | - Sarah Jacobs
- Department of Psychology, Wright State University, Dayton OH, 45435, United States
| | - Terrence Deak
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, Binghamton, NY 13902, United States
| | - Patricia A. Schiml
- Department of Psychology, Wright State University, Dayton OH, 45435, United States
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Shair HN, Smith JA, Welch MG. Cutting the vagus nerve below the diaphragm prevents maternal potentiation of infant rat vocalization. Dev Psychobiol 2011; 54:70-6. [PMID: 21761404 DOI: 10.1002/dev.20577] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Accepted: 05/13/2011] [Indexed: 12/17/2022]
Abstract
In maternal potentiation, the rate of vocalization by a young organism during isolation is greatly enhanced if that isolation has been immediately preceded by an interaction with the mother (or other adult female in the case of rats). The enhancement in isolation-induced vocalization rate does not occur if the young animal had an interaction with other social companions like littermates or with familiar inanimate stimuli like home cage shavings. The present study demonstrates that pups whose vagus nerve is cut below the diaphragm do not potentiate vocalization after an interaction with their dam. The vocalization rates of denervated pups in a first isolation, in the presence of the dam, and during cold exposure do not differ from control pups. Their non-vocal behaviors also appear unaffected by the surgery. Similar to what has been shown in studies of fever-induced behavioral changes, an intact vagus nerve from the gut is necessary for young rat pups to show normal social mediation of their isolation-induced vocal responses.
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Affiliation(s)
- Harry N Shair
- Division of Developmental Neuroscience, New York State Psychiatric Institute, New York, NY 10032, USA.
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71
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Brenu EW, van Driel ML, Staines DR, Ashton KJ, Ramos SB, Keane J, Klimas NG, Marshall-Gradisnik SM. Immunological abnormalities as potential biomarkers in Chronic Fatigue Syndrome/Myalgic Encephalomyelitis. J Transl Med 2011; 9:81. [PMID: 21619669 PMCID: PMC3120691 DOI: 10.1186/1479-5876-9-81] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 05/28/2011] [Indexed: 12/17/2022] Open
Abstract
Background Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) is characterised by severe prolonged fatigue, and decreases in cognition and other physiological functions, resulting in severe loss of quality of life, difficult clinical management and high costs to the health care system. To date there is no proven pathomechanism to satisfactorily explain this disorder. Studies have identified abnormalities in immune function but these data are inconsistent. We investigated the profile of markers of immune function (including novel markers) in CFS/ME patients. Methods We included 95 CFS/ME patients and 50 healthy controls. All participants were assessed on natural killer (NK) and CD8+T cell cytotoxic activities, Th1 and Th2 cytokine profile of CD4+T cells, expression of vasoactive intestinal peptide receptor 2 (VPACR2), levels of NK phenotypes (CD56bright and CD56dim) and regulatory T cells expressing FoxP3 transcription factor. Results Compared to healthy individuals, CFS/ME patients displayed significant increases in IL-10, IFN-γ, TNF-α, CD4+CD25+ T cells, FoxP3 and VPACR2 expression. Cytotoxic activity of NK and CD8+T cells and NK phenotypes, in particular the CD56bright NK cells were significantly decreased in CFS/ME patients. Additionally granzyme A and granzyme K expression were reduced while expression levels of perforin were significantly increased in the CFS/ME population relative to the control population. These data suggest significant dysregulation of the immune system in CFS/ME patients. Conclusions Our study found immunological abnormalities which may serve as biomarkers in CFS/ME patients with potential for an application as a diagnostic tool.
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Affiliation(s)
- Ekua W Brenu
- Population Health and Neuroimmunology Unit, Faculty of Health Science and Medicine, Bond University, Robina, Queensland, Australia
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Abstract
The ability of gut microbiota to communicate with the brain and thus modulate behavior is emerging as an exciting concept in health and disease. The enteric microbiota interacts with the host to form essential relationships that govern homeostasis. Despite the unique enteric bacterial fingerprint of each individual, there appears to be a certain balance that confers health benefits. It is, therefore, reasonable to note that a decrease in the desirable gastrointestinal bacteria will lead to deterioration in gastrointestinal, neuroendocrine or immune relationships and ultimately disease. Therefore, studies focusing on the impact of enteric microbiota on the host and in particular on the central nervous system are essential to our understanding of the influence of this system. Recent studies published in this Journal demonstrate that germ-free mice display alterations in stress-responsivity, central neurochemistry and behavior indicative of a reduction in anxiety in comparison to conventional mice. Such data offer the enticing proposition that specific modulation of the enteric microbiota may be a useful strategy for stress-related disorders and for modulating the co-morbid aspects of gastrointestinal disorders such as irritable bowel syndrome and inflammatory bowel disease.
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Affiliation(s)
- J F Cryan
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.
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73
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Maternal separation as a model of brain-gut axis dysfunction. Psychopharmacology (Berl) 2011; 214:71-88. [PMID: 20886335 DOI: 10.1007/s00213-010-2010-9] [Citation(s) in RCA: 279] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 08/28/2010] [Indexed: 12/13/2022]
Abstract
RATIONALE Early life stress has been implicated in many psychiatric disorders ranging from depression to anxiety. Maternal separation in rodents is a well-studied model of early life stress. However, stress during this critical period also induces alterations in many systems throughout the body. Thus, a variety of other disorders that are associated with adverse early life events are often comorbid with psychiatric illnesses, suggesting a common underlying aetiology. Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder that is thought to involve a dysfunctional interaction between the brain and the gut. Essential aspects of the brain-gut axis include spinal pathways, the hypothalamic pituitary adrenal axis, the immune system, as well as the enteric microbiota. Accumulating evidence suggest that stress, especially in early life, is a predisposing factor to IBS. OBJECTIVE The objective of this review was to assess and compile the most relevant data on early life stress and alterations at all levels of the brain gut axis. RESULTS In this review, we describe the components of the brain-gut axis individually and how they are altered by maternal separation. The separated phenotype is characterised by alterations of the intestinal barrier function, altered balance in enteric microflora, exaggerated stress response and visceral hypersensitivity, which are all evident in IBS. CONCLUSION Thus, maternally separated animals are an excellent model of brain-gut axis dysfunction for the study of disorders such as IBS and for the development of novel therapeutic interventions.
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74
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Vieira MM, Ferreira TB, Pacheco PA, Barros PO, Almeida CR, Araújo-Lima CF, Silva-Filho RG, Hygino J, Andrade RM, Linhares UC, Andrade AF, Bento CA. Enhanced Th17 phenotype in individuals with generalized anxiety disorder. J Neuroimmunol 2010; 229:212-8. [DOI: 10.1016/j.jneuroim.2010.07.018] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 07/02/2010] [Accepted: 07/22/2010] [Indexed: 01/22/2023]
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Lyte M, Vulchanova L, Brown DR. Stress at the intestinal surface: catecholamines and mucosa-bacteria interactions. Cell Tissue Res 2010; 343:23-32. [PMID: 20941511 DOI: 10.1007/s00441-010-1050-0] [Citation(s) in RCA: 178] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Accepted: 09/01/2010] [Indexed: 02/08/2023]
Abstract
Psychological stress has profound effects on gastrointestinal function, and investigations over the past few decades have examined the mechanisms by which neural and hormonal stress mediators act to modulate gut motility, epithelial barrier function and inflammatory states. With its cellular diversity and large commensal bacterial population, the intestinal mucosa and its overlying mucous environment constitute a highly interactive environment for eukaryotic host cells and prokaryotic bacteria. The elaboration of stress mediators, particularly norepinephrine, at this interface influences host cells engaged in mucosal protection and the bacteria which populate the mucosal surface and gut lumen. This review will address growing evidence that norepinephrine and, in some cases, other mediators of the adaptation to stress modulate mucosal interactions with enteric bacteria. Stress-mediated changes in this delicate interplay may shift the microbial colonization patterns on the mucosal surface and alter the susceptibility of the host to infection. Moreover, changes in host-microbe interactions in the digestive tract may also influence ongoing neural activity in stress-responsive brain areas.
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Affiliation(s)
- Mark Lyte
- Department of Pharmacy Practice, Texas Tech University Health Sciences Center, 3601 4th Street, MS 8162, Lubbock, TX 79430-8162, USA.
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76
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Lakhan SE, Kirchgessner A. Gut inflammation in chronic fatigue syndrome. Nutr Metab (Lond) 2010; 7:79. [PMID: 20939923 PMCID: PMC2964729 DOI: 10.1186/1743-7075-7-79] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 10/12/2010] [Indexed: 12/16/2022] Open
Abstract
Chronic fatigue syndrome (CFS) is a debilitating disease characterized by unexplained disabling fatigue and a combination of accompanying symptoms the pathology of which is incompletely understood. Many CFS patients complain of gut dysfunction. In fact, patients with CFS are more likely to report a previous diagnosis of irritable bowel syndrome (IBS), a common functional disorder of the gut, and experience IBS-related symptoms. Recently, evidence for interactions between the intestinal microbiota, mucosal barrier function, and the immune system have been shown to play a role in the disorder's pathogenesis.Studies examining the microecology of the gastrointestinal (GI) tract have identified specific microorganisms whose presence appears related to disease; in CFS, a role for altered intestinal microbiota in the pathogenesis of the disease has recently been suggested. Mucosal barrier dysfunction promoting bacterial translocation has also been observed. Finally, an altered mucosal immune system has been associated with the disease. In this article, we discuss the interplay between these factors in CFS and how they could play a significant role in GI dysfunction by modulating the activity of the enteric nervous system, the intrinsic innervation of the gut.If an altered intestinal microbiota, mucosal barrier dysfunction, and aberrant intestinal immunity contribute to the pathogenesis of CFS, therapeutic efforts to modify gut microbiota could be a means to modulate the development and/or progression of this disorder. For example, the administration of probiotics could alter the gut microbiota, improve mucosal barrier function, decrease pro-inflammatory cytokines, and have the potential to positively influence mood in patients where both emotional symptoms and inflammatory immune signals are elevated. Probiotics also have the potential to improve gut motility, which is dysfunctional in many CFS patients.
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Affiliation(s)
- Shaheen E Lakhan
- Global Neuroscience Initiative Foundation, Los Angeles, CA, USA.
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Painsipp E, Herzog H, Holzer P. Evidence from knockout mice that neuropeptide-Y Y2 and Y4 receptor signalling prevents long-term depression-like behaviour caused by immune challenge. J Psychopharmacol 2010; 24:1551-60. [PMID: 19939871 PMCID: PMC4359896 DOI: 10.1177/0269881109348171] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Neuropeptide Y participates in the acute behavioural responses to immune challenge, since Y2 receptor knockout (Y2⁻/⁻) mice are particularly sensitive to the short-term anxiogenic-like effect of bacterial lipopolysaccharide. The present exploratory study addressed the involvement of Y2 and Y4 receptors in the long-term behavioural responses to immune challenge. A single intraperitoneal injection of lipopolysaccharide (0.83 mg/kg) to control mice did not affect open field behaviour 3 h post-treatment but enhanced anxiety-like behaviour in Y2⁻/⁻ as well as Y4⁻/⁻ mice. Four weeks post-treatment this behavioural effect of lipopolysaccharide persisted in Y4⁻/⁻ mice but had gone in Y2⁻/⁻ mice. Depression-related behaviour in the forced swim test was enhanced 1 day post-lipopolysaccharide in control and Y2⁻/⁻ mice, but not in Y4⁻/⁻ mice. Four weeks post-treatment, the depressogenic-like effect of lipopolysaccharide had waned in control mice, persisted in Y2⁻/⁻ mice and was first observed in Y4⁻/⁻ mice. In summary, knockout of Y2 and/or Y4 receptors unmasks the ability of a single lipopolysaccharide injection to cause a delayed and prolonged increase in anxiety- and/or depression-like behaviour. These findings suggest that neuropeptide Y acting via Y2 and Y4 receptors prevents the development of long-term anxiety- and depression-like behaviour caused by acute immune challenge.
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Affiliation(s)
- Evelin Painsipp
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Graz, Austria
| | - Herbert Herzog
- Neurobiology Research Program, Garvan Institute of Medical Research, Sydney, Australia
| | - Peter Holzer
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Graz, Austria
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LIND R, LILLESTØL K, VALEUR JØRGEN, ERIKSEN HR, TANGEN T, BERSTAD A, ARSLAN LIED G. Job stress and coping strategies in patients with subjective food hypersensitivity. Scand J Psychol 2010; 51:179-84. [DOI: 10.1111/j.1467-9450.2009.00761.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Schedlowski M, Pacheco-López G. The learned immune response: Pavlov and beyond. Brain Behav Immun 2010; 24:176-85. [PMID: 19698779 DOI: 10.1016/j.bbi.2009.08.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 08/10/2009] [Accepted: 08/14/2009] [Indexed: 01/26/2023] Open
Abstract
The ability to associate physiological changes with a specific flavor was most likely acquired during evolution as an adaptive strategy aimed at protecting the organism while preparing it for danger. The behaviorally conditioned or learned immune response is an exquisite example of the bidirectional communication between the central nervous system (CNS) and the peripheral immune system. How is it possible that specific immuno-modulating properties of a drug or substance (unconditioned stimulus) can be re-enlisted just by the mere re-exposure to a particular taste, odor or environment (conditioned stimulus)? To answer this key question, we review the neurobiological mechanism mediating this type of associative learning, as well as the pathways and mechanisms employed by the brain to harness the immune system during the execution of the conditioned immune response. Finally, we focus on the potential therapeutic relevance of such learned immune responses, and their re-conceptualization within the framework of "learned placebo effects".
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Affiliation(s)
- Manfred Schedlowski
- Institute of Medical Psychology and Behavioral Immunobiology, University of Duisburg-Essen, Medical Faculty, 45122 Essen, Germany.
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80
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Psychological correlates of medical comorbidities in patients with temporomandibular disorders. J Am Dent Assoc 2010; 141:22-31. [DOI: 10.14219/jada.archive.2010.0017] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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81
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Goodhand JR, Wahed M, Rampton DS. Management of stress in inflammatory bowel disease: a therapeutic option? Expert Rev Gastroenterol Hepatol 2009; 3:661-79. [PMID: 19929586 DOI: 10.1586/egh.09.55] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
There is increasing evidence that psychological stress and associated mood disorders are linked with, and can adversely affect the course of, inflammatory bowel disease (IBD). Unfortunately, owing to methodological difficulties inherent in undertaking appropriately targeted and blinded trials, there are limited high-quality data regarding the effects on IBD of interventions aimed to ameliorate stress and mood disorders. Nevertheless, patients want psychological intervention as well as conventional medical strategies. Emerging trial evidence supports the suggestion that psychologically orientated therapy may ameliorate IBD-associated mood disorders, but there are no strong data as of yet to indicate that stress management has a beneficial effect on the activity or course of IBD. As yet, which, when and how interventions targeted at psychological stress and mood disturbances should be offered to individual patients with IBD is not clear.
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Affiliation(s)
- James R Goodhand
- Centre for Gastroenterology, Institute of Cell and Molecular Science, Barts and the London School of Medicine and Dentistry, 4 Newark Street, London, E1 2AT, UK.
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82
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Lyte M. The microbial organ in the gut as a driver of homeostasis and disease. Med Hypotheses 2009; 74:634-8. [PMID: 19900764 DOI: 10.1016/j.mehy.2009.10.025] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Accepted: 10/14/2009] [Indexed: 01/01/2023]
Abstract
Based on the ability of bacteria to both recognize and synthesize neuroendocrine hormones, it is hypothesized that microbes within the intestinal tract comprise a community that interfaces with the mammalian nervous system that innervates the gastrointestinal tract to form a microbial organ. Given the evolutionary context in which the central nervous system is an outgrowth of the more primitive enteric nervous system and the time in which microbes have colonized the mammalian intestinal tract, it is further hypothesized that this microbial organ enters into a symbiotic relationship with its mammalian host to influence both homeostasis (aspects such as behavior) and susceptibility to disease. Contained within the overall hypothesis are three main thematic elements: the species composition of the microbial organ influences host homeostasis and disease susceptibility; the host's nervous system influences the species composition of the microbial organ and the microbial organ itself possesses its own nervous system. Elucidation of the mechanisms by which this evolutionary symbiosis occurs would dramatically alter current medical thought by providing a biological basis for linking these two disparate organ systems and provide a new paradigm with which to understand and design new therapeutic approaches for a range of clinical diseases.
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Affiliation(s)
- Mark Lyte
- Department of Pharmacy Practice, School of Pharmacy, Texas Tech University Health Sciences Center, 3601 4th Street, MS8162, Lubbock, TX 79430, USA.
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83
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Barajon I, Serrao G, Arnaboldi F, Opizzi E, Ripamonti G, Balsari A, Rumio C. Toll-like receptors 3, 4, and 7 are expressed in the enteric nervous system and dorsal root ganglia. J Histochem Cytochem 2009; 57:1013-23. [PMID: 19546475 DOI: 10.1369/jhc.2009.953539] [Citation(s) in RCA: 205] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The aim of the present study was to evaluate the expression of innate immunity receptors belonging to the Toll-like family in the neural plexuses of the different tracts of murine intestine, of the human ileum, and in lower dorsal root ganglia (DRGs) from where extrinsic afferents to these plexuses originate. Results obtained by immunohistochemistry and immunofluorescence on paraffin-embedded tissue and whole-mount preparations show that Toll-like receptors (TLRs) -3 and -7, recognizing viral RNA, and TLR4, recognizing lipopolysaccharide (membrane component of Gram-negative bacteria), are expressed in the myenteric and submucous plexuses of murine intestine and human ileum, and in DRGs primary sensory neurons. They also show that TLR4 immunostaining is stronger in murine distal large bowel. In murine tissue, expression of TLRs was present in both neurons and glial cells. These observations indicate that the enteric neural network might be directly activated by bacterial and viral components and is therefore more in the forefront than previously envisaged in defense responses of the intestinal wall and in the cross-talk with intestinal microbiota. They also highlight the presence of a peripheral neural network that by way of hardwired neurotransmission could potentially convey to the central nervous system specific information on our microbial counterpart and invading or potentially invading pathogens.
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Affiliation(s)
- Isabella Barajon
- Department of Human Morphology and Biomedical Sciences, Città Studi, 20133 Milano, Italy.
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84
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Abstract
Development of therapeutic measures to reduce the risk of potentially fatal episodes of hypoglycaemia and thus to achieve the full benefits of intensive insulin therapy in diabetic patients requires a complete understanding of the multi-factorial mechanisms for repeated hypoglycaemia-induced blunting of the sympatho-adrenal response (BSAR). After critical analysis of the hypotheses, this review paper suggests a heuristic theory. This theory suggests two mechanisms for the BSAR, each involving a critical role for the central brain noradrenergic system. Furthermore, this theory also suggests that the lateral hypothalamus (LH) plays an important role in this phenomenon. Within the framework of this theory, explanations for 1) sexual dimorphism in the adrenomedullary response (AR), 2) dissociation in the blunting of the AR and the sympathetic response (SR) and 3) antecedent exercise-induced blunting of the AR are provided. In addition, habituation of orexin-A neurons is suggested to cause defective awakening. Moreover, potential therapeutics measures have been also suggested that will reduce or prevent severe episodes of hypoglycaemia.
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Affiliation(s)
- B Parekh
- Institute of Metabolic Science, University of Cambridge, Cambridge CB2 0QQ, UK.
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85
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Collins SM, Bercik P. The relationship between intestinal microbiota and the central nervous system in normal gastrointestinal function and disease. Gastroenterology 2009; 136:2003-14. [PMID: 19457424 DOI: 10.1053/j.gastro.2009.01.075] [Citation(s) in RCA: 386] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2008] [Revised: 01/13/2009] [Accepted: 01/25/2009] [Indexed: 12/14/2022]
Abstract
Although many people are aware of the communication that occurs between the gastrointestinal (GI) tract and the central nervous system, fewer know about the ability of the central nervous system to influence the microbiota or of the microbiota's influence on the brain and behavior. Within the GI tract, the microbiota have a mutually beneficial relationship with their host that maintains normal mucosal immune function, epithelial barrier integrity, motility, and nutrient absorption. Disruption of this relationship alters GI function and disease susceptibility. Animal studies suggest that perturbations of behavior, such as stress, can change the composition of the microbiota; these changes are associated with increased vulnerability to inflammatory stimuli in the GI tract. The mechanisms that underlie these alterations are likely to involve stress-induced changes in GI physiology that alter the habitat of enteric bacteria. Furthermore, experimental perturbation of the microbiota can alter behavior, and the behavior of germ-free mice differs from that of colonized mice. Gaining a better understanding of the relationship between behavior and the microbiota could provide insight into the pathogenesis of functional and inflammatory bowel disorders.
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Affiliation(s)
- Stephen M Collins
- The Farncombe Family Digestive Health Research Institute, Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada.
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86
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A randomized, double-blind, placebo-controlled pilot study of a probiotic in emotional symptoms of chronic fatigue syndrome. Gut Pathog 2009; 1:6. [PMID: 19338686 PMCID: PMC2664325 DOI: 10.1186/1757-4749-1-6] [Citation(s) in RCA: 374] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Accepted: 03/19/2009] [Indexed: 12/12/2022] Open
Abstract
Chronic fatigue syndrome (CFS) is complex illness of unknown etiology. Among the broad range of symptoms, many patients report disturbances in the emotional realm, the most frequent of which is anxiety. Research shows that patients with CFS and other so-called functional somatic disorders have alterations in the intestinal microbial flora. Emerging studies have suggested that pathogenic and non-pathogenic gut bacteria might influence mood-related symptoms and even behavior in animals and humans. In this pilot study, 39 CFS patients were randomized to receive either 24 billion colony forming units of Lactobacillus casei strain Shirota (LcS) or a placebo daily for two months. Patients provided stool samples and completed the Beck Depression and Beck Anxiety Inventories before and after the intervention. We found a significant rise in both Lactobacillus and Bifidobacteria in those taking the LcS, and there was also a significant decrease in anxiety symptoms among those taking the probiotic vs controls (p = 0.01). These results lend further support to the presence of a gut-brain interface, one that may be mediated by microbes that reside or pass through the intestinal tract.
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Li W, Dowd SE, Scurlock B, Acosta-Martinez V, Lyte M. Memory and learning behavior in mice is temporally associated with diet-induced alterations in gut bacteria. Physiol Behav 2008; 96:557-67. [PMID: 19135464 DOI: 10.1016/j.physbeh.2008.12.004] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 11/04/2008] [Accepted: 12/10/2008] [Indexed: 12/20/2022]
Abstract
The ability of dietary manipulation to influence learning and behavior is well recognized and almost exclusively interpreted as direct effects of dietary constituents on the central nervous system. The role of dietary modification on gut bacterial populations and the possibility of such microbial population shifts related to learning and behavior is poorly understood. The purpose of this study was to examine whether shifts in bacterial diversity due to dietary manipulation could be correlated with changes in memory and learning. Five week old male CF1 mice were randomly assigned to receive standard rodent chow (PP diet) or chow containing 50% lean ground beef (BD diet) for 3 months. As a measure of memory and learning, both groups were trained and tested on a hole-board open field apparatus. Following behavioral testing, all mice were sacrificed and colonic stool samples collected and analyzed by automated rRNA intergenic spacer analysis (ARISA) and bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP) approach for microbial diversity. Results demonstrated significantly higher bacterial diversity in the beef supplemented diet group according to ARISA and bTEFAP. Compared to the PP diet, the BD diet fed mice displayed improved working (P=0.0008) and reference memory (P<0.0001). The BD diet fed animals also displayed slower speed (P<0.0001) in seeking food as well as reduced anxiety level in the first day of testing (P=0.0004). In conclusion, we observed a correlation between dietary induced shifts in bacteria diversity and animal behavior that may indicate a role for gut bacterial diversity in memory and learning.
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Affiliation(s)
- Wang Li
- School of Pharmacy, Texas Tech University Health Sciences Center, Lubbock, TX 79430, United States
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88
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Kipnis J, Derecki NC, Yang C, Scrable H. Immunity and cognition: what do age-related dementia, HIV-dementia and 'chemo-brain' have in common? Trends Immunol 2008; 29:455-63. [PMID: 18789764 DOI: 10.1016/j.it.2008.07.007] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2008] [Revised: 07/01/2008] [Accepted: 07/03/2008] [Indexed: 11/24/2022]
Abstract
Until recently, dogma dictated that the immune system and the central nervous system (CNS) live mostly separate, parallel lives, and any interactions between the two were assumed to be limited to extreme cases of pathological insult. It was only a decade ago that T cells in the injured brain were shown to play a protective rather than a destructive role. In this article, we explore the role of the immune system in the healthy brain, focusing on the key function that T lymphocytes have in the regulation of cognition. We discuss candidate mechanisms underlying T cell-mediated control of cognitive function in human cognitive diseases associated with immune decline, such as age- and HIV-related dementias, 'chemo-brain' and others.
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Affiliation(s)
- Jonathan Kipnis
- Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, USA.
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