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Neuroimmunomodulation in the Gut: Focus on Inflammatory Bowel Disease. Mediators Inflamm 2016; 2016:1363818. [PMID: 27471349 PMCID: PMC4947661 DOI: 10.1155/2016/1363818] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 06/07/2016] [Indexed: 12/17/2022] Open
Abstract
Intestinal immunity is finely regulated by several concomitant and overlapping mechanisms, in order to efficiently sense external stimuli and mount an adequate response of either tolerance or defense. In this context, a complex interplay between immune and nonimmune cells is responsible for the maintenance of normal homeostasis. However, in certain conditions, the disruption of such an intricate network may result in intestinal inflammation, including inflammatory bowel disease (IBD). IBD is believed to result from a combination of genetic and environmental factors acting in concert with an inappropriate immune response, which in turn interacts with nonimmune cells, including nervous system components. Currently, evidence shows that the interaction between the immune and the nervous system is bidirectional and plays a critical role in the regulation of intestinal inflammation. Recently, the maintenance of intestinal homeostasis has been shown to be under the reciprocal control of the microbiota by immune mechanisms, whereas intestinal microorganisms can modulate mucosal immunity. Therefore, in addition to presenting the mechanisms underlying the interaction between immune and nervous systems in the gut, here we discuss the role of the microbiota also in the regulation of neuroimmune crosstalk involved in intestinal homeostasis and inflammation, with potential implications to IBD pathogenesis.
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Sharkey KA, Savidge TC. Reprint of: Role of enteric neurotransmission in host defense and protection of the gastrointestinal tract. Auton Neurosci 2014; 182:70-82. [PMID: 24674836 DOI: 10.1016/j.autneu.2014.03.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Accepted: 12/11/2013] [Indexed: 12/11/2022]
Abstract
Host defense is a vital role played by the gastrointestinal tract. As host to an enormous and diverse microbiome, the gut has evolved an elaborate array of chemical and physicals barriers that allow the digestion and absorption of nutrients without compromising the mammalian host. The control of such barrier functions requires the integration of neural, humoral, paracrine and immune signaling, involving redundant and overlapping mechanisms to ensure, under most circumstances, the integrity of the gastrointestinal epithelial barrier. Here we focus on selected recent developments in the autonomic neural control of host defense functions used in the protection of the gut from luminal agents, and discuss how the microbiota may potentially play a role in enteric neurotransmission. Key recent findings include: the important role played by subepithelial enteric glia in modulating intestinal barrier function, identification of stress-induced mechanisms evoking barrier breakdown, neural regulation of epithelial cell proliferation, the role of afferent and efferent vagal pathways in regulating barrier function, direct evidence for bacterial communication to the enteric nervous system, and microbial sources of enteric neurotransmitters. We discuss these new and interesting developments in our understanding of the role of the autonomic nervous system in gastrointestinal host defense.
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Affiliation(s)
- Keith A Sharkey
- Hotchkiss Brain Institute and Snyder Institute for Chronic Diseases, Department of Physiology & Pharmacology, University of Calgary, Calgary, Alberta, Canada.
| | - Tor C Savidge
- Texas Children's Microbiome Center, Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
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Ikehara O, Hayashi H, Waguri T, Kaji I, Karaki SI, Kuwahara A, Suzuki Y. Luminal trypsin induces enteric nerve-mediated anion secretion in the mouse cecum. J Physiol Sci 2014; 64:119-28. [PMID: 24421180 PMCID: PMC10717537 DOI: 10.1007/s12576-013-0302-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 12/10/2013] [Indexed: 02/08/2023]
Abstract
Proteases play a diverse role in health and disease. An excessive concentration of proteases has been found in the feces of patients with inflammatory bowel disease or irritable bowel syndrome and been implicated in the pathogenesis of such disorders. This study examined the effect of the serine protease, trypsin, on intestinal epithelial anion secretion when added to the luminal side. A mucosal-submucosal sheet of the mouse cecum was mounted in Ussing chambers, and the short-circuit current (I sc) was measured. Trypsin added to the mucosal (luminal) side increased I sc with an ED50 value of approximately 10 μM. This I sc increase was suppressed by removing Cl(-) from the bathing solution. The I sc increase induced by 10-100 μM trypsin was substantially suppressed by tetrodotoxin, and partially inhibited by a neurokinin-1 receptor antagonist, but not by a muscarinic or nicotinic ACh-receptor antagonist. The trypsin-induced I sc increase was also significantly inhibited by a 5-hydroxytryptamine-3 receptor (5-HT3) antagonist and substantially suppressed by the simultaneous addition of both 5-HT3 and 5-HT4 receptor antagonists. We conclude that luminal trypsin activates the enteric reflex to induce anion secretion, 5-HT and substance P playing important mediating roles in this secreto-motor reflex. Luminal proteases may contribute to the cause of diarrhea occurring with some intestinal disorders.
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Affiliation(s)
- Osamu Ikehara
- Laboratory of Physiology, Department of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
| | - Hisayoshi Hayashi
- Laboratory of Physiology, Department of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
| | - Toshiharu Waguri
- Laboratory of Physiology, Department of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
| | - Izumi Kaji
- Laboratory of Physiology, Department of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
| | - Shin-ichiro Karaki
- Laboratory of Physiology, Department of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
| | - Atsukazu Kuwahara
- Laboratory of Physiology, Department of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
| | - Yuichi Suzuki
- Laboratory of Physiology, Department of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526 Japan
- Laboratory of Anatomy and Physiology, Department of Health and Nutrition, Sendai Shirayuri Women’s College, Hondacho 6-1, Izumi-ku, Sendai, 981-3107 Japan
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Role of enteric neurotransmission in host defense and protection of the gastrointestinal tract. Auton Neurosci 2013; 181:94-106. [PMID: 24412639 DOI: 10.1016/j.autneu.2013.12.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Accepted: 12/11/2013] [Indexed: 12/24/2022]
Abstract
Host defense is a vital role played by the gastrointestinal tract. As host to an enormous and diverse microbiome, the gut has evolved an elaborate array of chemical and physicals barriers that allow the digestion and absorption of nutrients without compromising the mammalian host. The control of such barrier functions requires the integration of neural, humoral, paracrine and immune signaling, involving redundant and overlapping mechanisms to ensure, under most circumstances, the integrity of the gastrointestinal epithelial barrier. Here we focus on selected recent developments in the autonomic neural control of host defense functions used in the protection of the gut from luminal agents, and discuss how the microbiota may potentially play a role in enteric neurotransmission. Key recent findings include: the important role played by subepithelial enteric glia in modulating intestinal barrier function, identification of stress-induced mechanisms evoking barrier breakdown, neural regulation of epithelial cell proliferation, the role of afferent and efferent vagal pathways in regulating barrier function, direct evidence for bacterial communication to the enteric nervous system, and microbial sources of enteric neurotransmitters. We discuss these new and interesting developments in our understanding of the role of the autonomic nervous system in gastrointestinal host defense.
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Tao K, Wang HT, Chen B, Wang BT, Li ZY, Zhu XX, Tang CW, Hu DH. Effect of nonpeptide NK1 receptor antagonist L-703,606 on the edema formation in rats at early stage after deep partial-thickness skin scalding. ASIAN PAC J TROP MED 2013; 6:387-94. [DOI: 10.1016/s1995-7645(13)60044-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 02/24/2013] [Accepted: 03/20/2013] [Indexed: 10/26/2022] Open
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Ikehara O, Hayashi H, Waguri T, Kaji I, Karaki SI, Kuwahara A, Suzuki Y. Subepithelial trypsin induces enteric nerve-mediated anion secretion by activating proteinase-activated receptor 1 in the mouse cecum. J Physiol Sci 2012; 62:211-9. [PMID: 22389134 PMCID: PMC10717934 DOI: 10.1007/s12576-012-0198-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2011] [Accepted: 02/07/2012] [Indexed: 12/19/2022]
Abstract
Serine proteases are versatile signaling molecules and often exert this function by activating the proteinase-activated receptors (PAR(1)-PAR(4)). Our previous study on the mouse cecum has shown that the PAR(1)-activating peptide (AP) and PAR(2)-AP both induced electrogenic anion secretion. This secretion mediated by PAR(1) probably occurred by activating the receptor on the submucosal secretomotor neurons, while PAR(2)-mediated anion secretion probably occurred by activating the receptor on the epithelial cells. This present study was aimed at using trypsin to further elucidate the roles of serine proteases and PARs in regulating intestinal anion secretion. A mucosal-submucosal sheet of the mouse cecum was mounted in Ussing chambers, and the short-circuit current (I(sc)) was measured. Trypsin added to the serosal side increased I(sc) with an ED(50) value of approximately 100 nM. This I(sc) increase was suppressed by removing Cl(-) from the bathing solution. The I(sc) increase induced by 100 nM trypsin was substantially suppressed by tetrodotoxin, and partially inhibited by an NK(1) receptor antagonist, by a muscarinic Ach-receptor antagonist, and by 5-hydroxytryptamine-3 (5-HT(3)) and 5-HT(4) receptor antagonists. The I(sc) increase induced by trypsin was partially suppressed when the tissue had been pretreated with PAR(1)-AP, but not by a pretreatment with PAR(2)-AP. These results suggest that the serine protease, trypsin, induced anion secretion by activating the enteric secretomotor nerves. This response was initiated in part by activating PAR(1) on the enteric nerves. Serine proteases and PARs are likely to be responsible for the diarrhea occurring under intestinal inflammatory conditions.
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Affiliation(s)
- Osamu Ikehara
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka 422-8526 Japan
| | - Hisayoshi Hayashi
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka 422-8526 Japan
| | - Toshiharu Waguri
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka 422-8526 Japan
| | - Izumi Kaji
- Laboratory of Physiology, Department of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka 422-8526 Japan
| | - Shin-ichiro Karaki
- Laboratory of Physiology, Department of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka 422-8526 Japan
| | - Atsukazu Kuwahara
- Laboratory of Physiology, Department of Environmental Health Sciences, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka 422-8526 Japan
| | - Yuichi Suzuki
- Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka 422-8526 Japan
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Ma L, Dorling A. The roles of thrombin and protease-activated receptors in inflammation. Semin Immunopathol 2011; 34:63-72. [PMID: 21809138 DOI: 10.1007/s00281-011-0281-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 07/20/2011] [Indexed: 12/11/2022]
Abstract
Inflammation and coagulation constitute two host defence systems with complementary physiological roles in limiting tissue damage, restoring homeostasis and eliminating invading pathogens, functions reliant on effective regulation of both processes at a variety of levels. Dysfunctional activation or regulation of either pathway may lead to pathology and contribute to human diseases as diverse as myocardial infarction and septic shock. The serine protease thrombin, a key protein in the coagulation pathway, can activate cellular signalling directly via proteolytic cleavage of the N-terminal domain of a family of G protein-coupled receptors or indirectly through the generation of molecules such as activated protein C. These events transmit signals to many cell types and can elicit the production of various pro-inflammatory mediators such as cytokines, chemokines and growth factors, thereby influencing cell activation, differentiation, survival and migration. This review discusses recent progress in understanding how thrombin and protease-activated receptors influence biological processes, highlighting the detrimental and protective cellular effects of thrombin and its signalling pathways.
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Affiliation(s)
- Liang Ma
- Medical Research Council (MRC) Centre for Transplantation, King's College London, King's Health Partners, Guy's Hospital, London, UK
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Adams MN, Ramachandran R, Yau MK, Suen JY, Fairlie DP, Hollenberg MD, Hooper JD. Structure, function and pathophysiology of protease activated receptors. Pharmacol Ther 2011; 130:248-82. [PMID: 21277892 DOI: 10.1016/j.pharmthera.2011.01.003] [Citation(s) in RCA: 267] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 01/03/2011] [Indexed: 12/18/2022]
Abstract
Discovered in the 1990s, protease activated receptors(1) (PARs) are membrane-spanning cell surface proteins that belong to the G protein coupled receptor (GPCR) family. A defining feature of these receptors is their irreversible activation by proteases; mainly serine. Proteolytic agonists remove the PAR extracellular amino terminal pro-domain to expose a new amino terminus, or tethered ligand, that binds intramolecularly to induce intracellular signal transduction via a number of molecular pathways that regulate a variety of cellular responses. By these mechanisms PARs function as cell surface sensors of extracellular and cell surface associated proteases, contributing extensively to regulation of homeostasis, as well as to dysfunctional responses required for progression of a number of diseases. This review examines common and distinguishing structural features of PARs, mechanisms of receptor activation, trafficking and signal termination, and discusses the physiological and pathological roles of these receptors and emerging approaches for modulating PAR-mediated signaling in disease.
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Affiliation(s)
- Mark N Adams
- Mater Medical Research Institute, Aubigny Place, Raymond Terrace, South Brisbane Qld 4101, Australia
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