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Cremin M, Ramirez VT, Sanchez K, Tay E, Murray K, Brust-Mascher I, Reardon C. Substance P receptor signaling contributes to host maladaptive responses during enteric bacterial infection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.24.599421. [PMID: 38979288 PMCID: PMC11230291 DOI: 10.1101/2024.06.24.599421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Immune responses in the intestine are intricately balanced to prevent pathogen entry without inducing immunopathology. The nervous system is well-established to interface with the immune system to fine-tune immunity in various organ systems including the gastrointestinal tract. Specialized sensory neurons can detect bacteria, bacterial products, and the resulting inflammation, to coordinate the immune response in the gastrointestinal tract. These sensory neurons release peptide neurotransmitters such as Substance P (SP), to induce both neuronal signaling and localized responses in non-neuronal cells. With this in mind, we assessed the immunoregulatory roles of SP receptor signaling during enteric bacterial infection with the non-invasive pathogen Citrobacter rodentium . Pharmacological antagonism of the SP receptor significantly reduced bacterial burden and prevented colonic crypt hyperplasia. Mice with SP receptor signaling blockade had significantly reduced inflammation and recruitment of T-cells in the colon. Reduced colonic T-cell recruitment is due to reduced expression of adhesion molecules on colonic endothelial cells in SP receptor antagonist-treated mice. Using SP receptor T-cell conditional knockout mice, we further confirmed SP receptor signaling enhanced select aspects of T-cell responses. Our data demonstrates that SP receptor signaling can significantly reduce inflammation and prevent host-maladaptive responses without impinging upon host protection.
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Gold MS, Loeza-Alcocer E. Experimental colitis-induced visceral hypersensitivity is attenuated by GABA treatment in mice. Am J Physiol Gastrointest Liver Physiol 2024; 326:G252-G263. [PMID: 38193198 PMCID: PMC11211035 DOI: 10.1152/ajpgi.00012.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 12/21/2023] [Accepted: 12/26/2023] [Indexed: 01/10/2024]
Abstract
Ulcerative colitis (UC) is linked with inflammation of the large intestine due to an overactive response of the colon-immune system. UC is associated with weight loss, rectal bleeding, diarrhea, and abdominal pain. Given that γ-amino butyric acid (GABA) suppresses immune cell activity and the excitability of colonic afferents, and that there is a decrease in colonic GABA during UC, we hypothesized that UC pain is due to a decrease in the inhibition of colonic afferents. Thus, restoring GABA in the colon will attenuate inflammatory hypersensitivity. We tested this hypothesis in a mouse model of colitis. Colon inflammation was induced with seven days of dextran sodium sulfate (DSS, 3%) in the drinking water. GABA (40 mg/kg) was administered orally for the same period as DSS, and body weight, colon length, colon permeability, clinical progression of colitis (disease activity index or DAI), and colon histological score (HS) were assessed to determine the effects of GABA on colitis. A day after the end of GABA treatment, visceral sensitivity was assessed with balloon distention (of the colon)-evoked visceromotor response and colon samples were collected for the measurement of GABA and cytokines. Treatment with GABA reduced the DSS-induced increase in the colon permeability, DAI, HS, and decrease in body weight and colon length. Furthermore, GABA inhibited the DSS-induced increase in the proinflammatory cytokines tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-12 (IL-12), and increased the expression of the anti-inflammatory cytokine IL-10 in the colon tissue. Importantly, GABA reduced DSS-induced visceral hypersensitivity. These data suggest that increasing gastrointestinal levels of GABA may be useful for the treatment of colitis.NEW & NOTEWORTHY GABA treatment reduces the severity of colitis and inflammation and produces inhibition of visceral hypersensitivity in colon-inflamed mice. These results raise the promising possibility that GABA treatment may be an effective therapeutic strategy for the management of symptoms associated with colitis. However, clinical studies are required to corroborate whether this mouse-model data translates to human colon.
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Affiliation(s)
- Michael S Gold
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Emanuel Loeza-Alcocer
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
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Shu LZ, Ding YD, Xue QM, Cai W, Deng H. Direct and indirect effects of pathogenic bacteria on the integrity of intestinal barrier. Therap Adv Gastroenterol 2023; 16:17562848231176427. [PMID: 37274298 PMCID: PMC10233627 DOI: 10.1177/17562848231176427] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Accepted: 05/01/2023] [Indexed: 06/06/2023] Open
Abstract
Bacterial translocation is a pathological process involving migration of pathogenic bacteria across the intestinal barrier to enter the systemic circulation and gain access to distant organs. This phenomenon has been linked to a diverse range of diseases including inflammatory bowel disease, pancreatitis, and cancer. The intestinal barrier is an innate structure that maintains intestinal homeostasis. Pathogenic infections and dysbiosis can disrupt the integrity of the intestinal barrier, increasing its permeability, and thereby facilitating pathogen translocation. As translocation represents an essential step in pathogenesis, a clear understanding of how barrier integrity is disrupted and how this disruption facilitates bacterial translocation could identify new routes to effective prophylaxis and therapy. In this comprehensive review, we provide an in-depth analysis of bacterial translocation and intestinal barrier function. We discuss currently understood mechanisms of bacterial-enterocyte interactions, with a focus on tight junctions and endocytosis. We also discuss the emerging concept of bidirectional communication between the intestinal microbiota and other body systems. The intestinal tract has established 'axes' with various organs. Among our regulatory systems, the nervous, immune, and endocrine systems have been shown to play pivotal roles in barrier regulation. A mechanistic understanding of intestinal barrier regulation is crucial for the development of personalized management strategies for patients with bacterial translocation-related disorders. Advancing our knowledge of barrier regulation will pave the way for future research in this field and novel clinical intervention strategies.
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Affiliation(s)
- Lin-Zhen Shu
- Medical College, Nanchang University, Nanchang,
Jiangxi Province, China
| | - Yi-Dan Ding
- Medical College, Nanchang University, Nanchang,
Jiangxi Province, China
| | - Qing-Ming Xue
- Medical College, Nanchang University, Nanchang,
Jiangxi Province, China
| | - Wei Cai
- Medical College, Nanchang University, Nanchang,
Jiangxi Province, China
- Department of Pathology, the Fourth Affiliated
Hospital of Nanchang University, Nanchang, Jiangxi Province, China
| | - Huan Deng
- Department of Pathology, The Fourth Affiliated
Hospital of Nanchang University, No. 133 South Guangchang Road, Nanchang
330003, Jiangxi Province, China
- Tumor Immunology Institute, Nanchang
University, Nanchang, China
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Sharkey KA, Mawe GM. The enteric nervous system. Physiol Rev 2023; 103:1487-1564. [PMID: 36521049 PMCID: PMC9970663 DOI: 10.1152/physrev.00018.2022] [Citation(s) in RCA: 51] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022] Open
Abstract
Of all the organ systems in the body, the gastrointestinal tract is the most complicated in terms of the numbers of structures involved, each with different functions, and the numbers and types of signaling molecules utilized. The digestion of food and absorption of nutrients, electrolytes, and water occurs in a hostile luminal environment that contains a large and diverse microbiota. At the core of regulatory control of the digestive and defensive functions of the gastrointestinal tract is the enteric nervous system (ENS), a complex system of neurons and glia in the gut wall. In this review, we discuss 1) the intrinsic neural control of gut functions involved in digestion and 2) how the ENS interacts with the immune system, gut microbiota, and epithelium to maintain mucosal defense and barrier function. We highlight developments that have revolutionized our understanding of the physiology and pathophysiology of enteric neural control. These include a new understanding of the molecular architecture of the ENS, the organization and function of enteric motor circuits, and the roles of enteric glia. We explore the transduction of luminal stimuli by enteroendocrine cells, the regulation of intestinal barrier function by enteric neurons and glia, local immune control by the ENS, and the role of the gut microbiota in regulating the structure and function of the ENS. Multifunctional enteric neurons work together with enteric glial cells, macrophages, interstitial cells, and enteroendocrine cells integrating an array of signals to initiate outputs that are precisely regulated in space and time to control digestion and intestinal homeostasis.
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Affiliation(s)
- Keith A Sharkey
- Hotchkiss Brain Institute and Snyder Institute for Chronic Diseases, Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Gary M Mawe
- Department of Neurological Sciences, Larner College of Medicine, University of Vermont, Burlington, Vermont
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Saldana-Morales FB, Kim DV, Tsai MT, Diehl GE. Healthy Intestinal Function Relies on Coordinated Enteric Nervous System, Immune System, and Epithelium Responses. Gut Microbes 2022; 13:1-14. [PMID: 33929291 PMCID: PMC8096330 DOI: 10.1080/19490976.2021.1916376] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
During both health and disease, a coordinated response between the epithelium, immune system, and enteric nervous system is required for proper intestinal function. While each system responds to a number of common stimuli, their coordinated responses support digestion as well as responses and recovery following injury or pathogenic infections. In this review, we discuss how individual responses to common signals work together to support these critical functions.
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Affiliation(s)
- Fatima B. Saldana-Morales
- Graduate School of Biomedical Sciences, Baylor College of Medicine, HoustonTXUSA,Immunology Program of the Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NYUSA
| | - Dasom V. Kim
- Immunology Program of the Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NYUSA,Immunology and Microbial Pathogenesis Program, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Ming-Ting Tsai
- Graduate School of Biomedical Sciences, Baylor College of Medicine, HoustonTXUSA,Immunology Program of the Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NYUSA
| | - Gretchen E. Diehl
- Immunology Program of the Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NYUSA,Immunology and Microbial Pathogenesis Program, Weill Cornell Medical College, Cornell University, New York, NY, USA,CONTACT Gretchen E. Diehl Immunology Program of the Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY10021, USA. Immunology and Microbial Pathogenesis Program, Weill Cornell Medical College, Cornell University, New York, NY, USA
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Presence of TRPA1 Modifies CD4+/CD8+ T Lymphocyte Ratio and Activation. Pharmaceuticals (Basel) 2022; 15:ph15010057. [PMID: 35056114 PMCID: PMC8781558 DOI: 10.3390/ph15010057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/24/2021] [Accepted: 12/28/2021] [Indexed: 12/10/2022] Open
Abstract
Transient Receptor Potential Ankyrin 1 (TRPA1) has been reported to influence neuroinflammation and lymphocyte function. We analysed the immune phenotype and activation characteristics of TRPA1-deficient mice (knockout—KO) generated by targeted deletion of the pore-loop domain of the ion channel. We compared TRPA1 mRNA and protein expression in monocyte and lymphocyte subpopulations isolated from primary and secondary lymphatic organs of wild type (WT) and KO mice. qRT-PCR and flow cytometric studies indicated a higher level of TRPA1 in monocytes than in lymphocytes, but both were orders of magnitude lower than in sensory neurons. We found lower CD4+/CD8+ thymocyte ratios, diminished CD4/CD8 rates, and B cell numbers in the KO mice. Early activation marker CD69 was lower in CD4+ T cells of KO, while the level of CD8+/CD25+ cells was higher. In vitro TcR-mediated activation did not result in significant differences in CD69 level between WT and KO splenocytes, but lower cytokine (IL-1β, IL-6, TNF-α, IL-17A, IL-22, and RANTES) secretion was observed in KO splenocytes. Basal intracellular Ca2+ level and TcR-induced Ca2+ signal in T lymphocytes did not differ significantly, but interestingly, imiquimod-induced Ca2+ level in KO thymocytes was higher. Our results support the role of TRPA1 in the regulation of activation, cytokine production, and T and B lymphocytes composition in mice.
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Sansores-España LD, Melgar-Rodríguez S, Olivares-Sagredo K, Cafferata EA, Martínez-Aguilar VM, Vernal R, Paula-Lima AC, Díaz-Zúñiga J. Oral-Gut-Brain Axis in Experimental Models of Periodontitis: Associating Gut Dysbiosis With Neurodegenerative Diseases. FRONTIERS IN AGING 2021; 2:781582. [PMID: 35822001 PMCID: PMC9261337 DOI: 10.3389/fragi.2021.781582] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 11/08/2021] [Indexed: 12/12/2022]
Abstract
Periodontitis is considered a non-communicable chronic disease caused by a dysbiotic microbiota, which generates a low-grade systemic inflammation that chronically damages the organism. Several studies have associated periodontitis with other chronic non-communicable diseases, such as cardiovascular or neurodegenerative diseases. Besides, the oral bacteria considered a keystone pathogen, Porphyromonas gingivalis, has been detected in the hippocampus and brain cortex. Likewise, gut microbiota dysbiosis triggers a low-grade systemic inflammation, which also favors the risk for both cardiovascular and neurodegenerative diseases. Recently, the existence of an axis of Oral-Gut communication has been proposed, whose possible involvement in the development of neurodegenerative diseases has not been uncovered yet. The present review aims to compile evidence that the dysbiosis of the oral microbiota triggers changes in the gut microbiota, which creates a higher predisposition for the development of neuroinflammatory or neurodegenerative diseases.The Oral-Gut-Brain axis could be defined based on anatomical communications, where the mouth and the intestine are in constant communication. The oral-brain axis is mainly established from the trigeminal nerve and the gut-brain axis from the vagus nerve. The oral-gut communication is defined from an anatomical relation and the constant swallowing of oral bacteria. The gut-brain communication is more complex and due to bacteria-cells, immune and nervous system interactions. Thus, the gut-brain and oral-brain axis are in a bi-directional relationship. Through the qualitative analysis of the selected papers, we conclude that experimental periodontitis could produce both neurodegenerative pathologies and intestinal dysbiosis, and that periodontitis is likely to induce both conditions simultaneously. The severity of the neurodegenerative disease could depend, at least in part, on the effects of periodontitis in the gut microbiota, which could strengthen the immune response and create an injurious inflammatory and dysbiotic cycle. Thus, dementias would have their onset in dysbiotic phenomena that affect the oral cavity or the intestine. The selected studies allow us to speculate that oral-gut-brain communication exists, and bacteria probably get to the brain via trigeminal and vagus nerves.
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Affiliation(s)
- Luis Daniel Sansores-España
- Periodontal Biology Laboratory, Faculty of Dentistry, University of Chile, Santiago, Chile
- Faculty of Dentistry, Autonomous University of Yucatán, Mérida, México
| | | | | | - Emilio A. Cafferata
- Department of Periodontology, School of Dentistry, Universidad Científica Del Sur, Lima, Perú
| | | | - Rolando Vernal
- Periodontal Biology Laboratory, Faculty of Dentistry, University of Chile, Santiago, Chile
| | - Andrea Cristina Paula-Lima
- Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Santiago, Chile
| | - Jaime Díaz-Zúñiga
- Periodontal Biology Laboratory, Faculty of Dentistry, University of Chile, Santiago, Chile
- Department of Medicine, Faculty of Medicine, University of Atacama, Copiapó, Chile
- *Correspondence: Jaime Díaz-Zúñiga, ,
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Lenert ME, Avona A, Garner KM, Barron LR, Burton MD. Sensory Neurons, Neuroimmunity, and Pain Modulation by Sex Hormones. Endocrinology 2021; 162:bqab109. [PMID: 34049389 PMCID: PMC8237991 DOI: 10.1210/endocr/bqab109] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Indexed: 12/16/2022]
Abstract
The inclusion of women in preclinical pain studies has become more commonplace in the last decade as the National Institutes of Health (NIH) released its "Sex as a Biological Variable" mandate. Presumably, basic researchers have not had a comprehensive understanding about neuroimmune interactions in half of the population and how hormones play a role in this. To date, we have learned that sex hormones contribute to sexual differentiation of the nervous system and sex differences in behavior throughout the lifespan; however, the cycling of sex hormones does not always explain these differences. Here, we highlight recent advances in our understanding of sex differences and how hormones and immune interactions influence sensory neuron activity to contribute to physiology and pain. Neuroimmune mechanisms may be mediated by different cell types in each sex, as the actions of immune cells are sexually dimorphic. Unfortunately, the majority of studies assessing neuronal contributions to immune function have been limited to males, so it is unclear if the mechanisms are similar in females. Finally, pathways that control cellular metabolism, like nuclear receptors, have been shown to play a regulatory role both in pain and inflammation. Overall, communication between the neuroimmune and endocrine systems modulate pain signaling in a sex-dependent manner, but more research is needed to reveal nuances of these mechanisms.
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Affiliation(s)
- Melissa E Lenert
- Neuroimmunology and Behavior Laboratory, Center for Advanced Pain Studies (CAPS), Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Amanda Avona
- Neuroimmunology and Behavior Laboratory, Center for Advanced Pain Studies (CAPS), Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Katherine M Garner
- Neuroimmunology and Behavior Laboratory, Center for Advanced Pain Studies (CAPS), Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Luz R Barron
- Neuroimmunology and Behavior Laboratory, Center for Advanced Pain Studies (CAPS), Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas 75080, USA
| | - Michael D Burton
- Neuroimmunology and Behavior Laboratory, Center for Advanced Pain Studies (CAPS), Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas 75080, USA
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Maggi F, Morelli MB, Nabissi M, Marinelli O, Zeppa L, Aguzzi C, Santoni G, Amantini C. Transient Receptor Potential (TRP) Channels in Haematological Malignancies: An Update. Biomolecules 2021; 11:biom11050765. [PMID: 34065398 PMCID: PMC8160608 DOI: 10.3390/biom11050765] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/17/2021] [Accepted: 05/17/2021] [Indexed: 02/07/2023] Open
Abstract
Transient receptor potential (TRP) channels are improving their importance in different cancers, becoming suitable as promising candidates for precision medicine. Their important contribution in calcium trafficking inside and outside cells is coming to light from many papers published so far. Encouraging results on the correlation between TRP and overall survival (OS) and progression-free survival (PFS) in cancer patients are available, and there are as many promising data from in vitro studies. For what concerns haematological malignancy, the role of TRPs is still not elucidated, and data regarding TRP channel expression have demonstrated great variability throughout blood cancer so far. Thus, the aim of this review is to highlight the most recent findings on TRP channels in leukaemia and lymphoma, demonstrating their important contribution in the perspective of personalised therapies.
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Affiliation(s)
- Federica Maggi
- Department of Molecular Medicine, Sapienza University, 00185 Rome, Italy;
- Immunopathology Laboratory, School of Pharmacy, University of Camerino, 62032 Camerino, Italy; (M.B.M.); (M.N.); (O.M.); (L.Z.); (C.A.); (G.S.)
| | - Maria Beatrice Morelli
- Immunopathology Laboratory, School of Pharmacy, University of Camerino, 62032 Camerino, Italy; (M.B.M.); (M.N.); (O.M.); (L.Z.); (C.A.); (G.S.)
| | - Massimo Nabissi
- Immunopathology Laboratory, School of Pharmacy, University of Camerino, 62032 Camerino, Italy; (M.B.M.); (M.N.); (O.M.); (L.Z.); (C.A.); (G.S.)
| | - Oliviero Marinelli
- Immunopathology Laboratory, School of Pharmacy, University of Camerino, 62032 Camerino, Italy; (M.B.M.); (M.N.); (O.M.); (L.Z.); (C.A.); (G.S.)
| | - Laura Zeppa
- Immunopathology Laboratory, School of Pharmacy, University of Camerino, 62032 Camerino, Italy; (M.B.M.); (M.N.); (O.M.); (L.Z.); (C.A.); (G.S.)
| | - Cristina Aguzzi
- Immunopathology Laboratory, School of Pharmacy, University of Camerino, 62032 Camerino, Italy; (M.B.M.); (M.N.); (O.M.); (L.Z.); (C.A.); (G.S.)
| | - Giorgio Santoni
- Immunopathology Laboratory, School of Pharmacy, University of Camerino, 62032 Camerino, Italy; (M.B.M.); (M.N.); (O.M.); (L.Z.); (C.A.); (G.S.)
| | - Consuelo Amantini
- Immunopathology Laboratory, School of Biosciences and Veterinary Medicine, University of Camerino, 62032 Camerino, Italy
- Correspondence: ; Tel.: +30-0737403312
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Murray K, Rude KM, Sladek J, Reardon C. Divergence of neuroimmune circuits activated by afferent and efferent vagal nerve stimulation in the regulation of inflammation. J Physiol 2021; 599:2075-2084. [PMID: 33491187 DOI: 10.1113/jp281189] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 01/20/2021] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS It has previously been shown that afferent and efferent vagal nerve stimulation potently inhibits lipopolysaccharide (LPS)-induced inflammation Our data show inhibition of inflammation by efferent but not afferent vagal nerve stimulation requires T-cell derived acetylcholine We show that afferent and efferent neuroimmune circuits require β2 -adrenergic receptor signalling ABSTRACT: Chronic inflammation due to inappropriate immune cell activation can have significant effects on a variety of organ systems, reducing lifespan and quality of life. As such, highly targeted control of immune cell activation is a major therapeutic goal. Vagus nerve stimulation (VNS) has emerged as a therapeutic modality that exploits neuroimmune communication to reduce immune cell activation and consequently inflammation. Although vagal efferent fibres were originally identified as the primary driver of anti-inflammatory actions, the vagus nerve in most species of animals predominantly comprises afferent fibres. Stimulation of vagal afferent fibres can also reduce inflammation; it is, however, uncertain how these two neuroimmune circuits diverge. Here we show that afferent VNS induces a mechanism distinct from efferent VNS, ameliorating lipopolysaccharide (LPS)-induced inflammation independently of T-cell derived acetylcholine (ACh) which is required by efferent VNS. Using a β2 -adrenergic receptor antagonist (β2 -AR), we find that immune regulation induced by intact, afferent, or efferent VNS occurs in a β2- AR-dependent manner. Together, our findings indicate that intact VNS activates at least two distinct neuroimmune circuits each with unique mechanisms of action. Selective targeting of either the vagal efferent or afferent fibres may provide more personalized, robust and effective control over inappropriate immune responses.
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Affiliation(s)
- Kaitlin Murray
- Department of Anatomy, Physiology, and Cell Biology, UC Davis School of Veterinary Medicine, UC Davis, Davis, CA, USA
| | - Kavi M Rude
- Department of Anatomy, Physiology, and Cell Biology, UC Davis School of Veterinary Medicine, UC Davis, Davis, CA, USA
| | - Jessica Sladek
- Department of Anatomy, Physiology, and Cell Biology, UC Davis School of Veterinary Medicine, UC Davis, Davis, CA, USA
| | - Colin Reardon
- Department of Anatomy, Physiology, and Cell Biology, UC Davis School of Veterinary Medicine, UC Davis, Davis, CA, USA
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