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Higashio H, Yokoyama T, Saino T. A convenient fluorimetry-based degranulation assay using RBL-2H3 cells. Biosci Biotechnol Biochem 2024; 88:181-188. [PMID: 37968134 DOI: 10.1093/bbb/zbad160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 11/12/2023] [Indexed: 11/17/2023]
Abstract
Type I hypersensitivity is triggered by mast cell degranulation, a stimulus-induced exocytosis of preformed secretory granules (SGs) containing various inflammatory mediators. The degree of degranulation is generally expressed as a percentage of secretory granule markers (such as β-hexosaminidase and histamine) released into the external solution, and considerable time and labor are required for the quantification of markers in both the supernatants and cell lysates. In this study, we developed a simple fluorimetry-based degranulation assay using rat basophilic leukemia (RBL-2H3) mast cells. During degranulation, the styryl dye FM1-43 in the external solution fluorescently labeled the newly exocytosed SGs, whose increase in intensity was successively measured using a fluorescence microplate reader. In addition to the rate of β-hexosaminidase secretion, the cellular FM1-43 intensity successfully represented the degree and kinetics of degranulation under various conditions, suggesting that this method facilitates multi-sample and/or multi-time-point analyses required for screening substances regulating mast cell degranulation.
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Affiliation(s)
- Hironori Higashio
- Department of Chemistry, Center for Liberal Arts and Sciences, Iwate Medical University, Yahaba, Iwate, Japan
| | - Takuya Yokoyama
- Division of Cell Biology, Department of Anatomy, Iwate Medical University, Yahaba, Iwate, Japan
| | - Tomoyuki Saino
- Division of Cell Biology, Department of Anatomy, Iwate Medical University, Yahaba, Iwate, Japan
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2
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Stress and Nasal Allergy: Corticotropin-Releasing Hormone Stimulates Mast Cell Degranulation and Proliferation in Human Nasal Mucosa. Int J Mol Sci 2021; 22:ijms22052773. [PMID: 33803422 PMCID: PMC7967145 DOI: 10.3390/ijms22052773] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 02/27/2021] [Accepted: 03/06/2021] [Indexed: 12/12/2022] Open
Abstract
Psychological stress exacerbates mast cell (MC)-dependent inflammation, including nasal allergy, but the underlying mechanisms are not thoroughly understood. Because the key stress-mediating neurohormone, corticotropin-releasing hormone (CRH), induces human skin MC degranulation, we hypothesized that CRH may be a key player in stress-aggravated nasal allergy. In the current study, we probed this hypothesis in human nasal mucosa MCs (hM-MCs) in situ using nasal polyp organ culture and tested whether CRH is required for murine M-MC activation by perceived stress in vivo. CRH stimulation significantly increased the number of hM-MCs, stimulated both their degranulation and proliferation ex vivo, and increased stem cell factor (SCF) expression in human nasal mucosa epithelium. CRH also sensitized hM-MCs to further CRH stimulation and promoted a pro-inflammatory hM-MC phenotype. The CRH-induced increase in hM-MCs was mitigated by co-administration of CRH receptor type 1 (CRH-R1)-specific antagonist antalarmin, CRH-R1 small interfering RNA (siRNA), or SCF-neutralizing antibody. In vivo, restraint stress significantly increased the number and degranulation of murine M-MCs compared with sham-stressed mice. This effect was mitigated by intranasal antalarmin. Our data suggest that CRH is a major activator of hM-MC in nasal mucosa, in part via promoting SCF production, and that CRH-R1 antagonists such as antalarmin are promising candidate therapeutics for nasal mucosa neuroinflammation induced by perceived stress.
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Klein O, Sagi-Eisenberg R. Anaphylactic Degranulation of Mast Cells: Focus on Compound Exocytosis. J Immunol Res 2019; 2019:9542656. [PMID: 31011586 PMCID: PMC6442490 DOI: 10.1155/2019/9542656] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Accepted: 12/26/2018] [Indexed: 01/15/2023] Open
Abstract
Anaphylaxis is a notorious type 2 immune response which may result in a systemic response and lead to death. A precondition for the unfolding of the anaphylactic shock is the secretion of inflammatory mediators from mast cells in response to an allergen, mostly through activation of the cells via the IgE-dependent pathway. While mast cells are specialized secretory cells that can secrete through a variety of exocytic modes, the most predominant mode exerted by the mast cell during anaphylaxis is compound exocytosis-a specialized form of regulated exocytosis where secretory granules fuse to one another. Here, we review the modes of regulated exocytosis in the mast cell and focus on compound exocytosis. We review historical landmarks in the research of compound exocytosis in mast cells and the methods available for investigating compound exocytosis. We also review the molecular mechanisms reported to underlie compound exocytosis in mast cells and expand further with reviewing key findings from other cell types. Finally, we discuss the possible reasons for the mast cell to utilize compound exocytosis during anaphylaxis, the conflicting evidence in different mast cell models, and the open questions in the field which remain to be answered.
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Affiliation(s)
- Ofir Klein
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ronit Sagi-Eisenberg
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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4
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D'Costa S, Ayyadurai S, Gibson AJ, Mackey E, Rajput M, Sommerville LJ, Wilson N, Li Y, Kubat E, Kumar A, Subramanian H, Bhargava A, Moeser AJ. Mast cell corticotropin-releasing factor subtype 2 suppresses mast cell degranulation and limits the severity of anaphylaxis and stress-induced intestinal permeability. J Allergy Clin Immunol 2018; 143:1865-1877.e4. [PMID: 30439403 DOI: 10.1016/j.jaci.2018.08.053] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 08/03/2018] [Accepted: 08/17/2018] [Indexed: 02/07/2023]
Abstract
BACKGROUND Psychological stress and heightened mast cell (MC) activation are linked with important immunologic disorders, including allergy, anaphylaxis, asthma, and functional bowel diseases, but the mechanisms remain poorly defined. We have previously demonstrated that activation of the corticotropin-releasing factor (CRF) system potentiates MC degranulation responses during IgE-mediated anaphylaxis and psychological stress through corticotropin-releasing factor receptor subtype 1 (CRF1) expressed on MCs. OBJECTIVE In this study we investigated the role of corticotropin-releasing factor receptor subtype 2 (CRF2) as a modulator of stress-induced MC degranulation and associated disease pathophysiology. METHODS In vitro MC degranulation assays were performed with bone marrow-derived mast cells (BMMCs) derived from wild-type (WT) and CRF2-deficient (CRF2-/-) mice and RBL-2H3 MCs transfected with CRF2-overexpressing plasmid or CRF2 small interfering RNA. In vivo MC responses and associated pathophysiology in IgE-mediated passive systemic anaphylaxis and acute psychological restraint stress were measured in WT, CRF2-/-, and MC-deficient KitW-sh/W-sh knock-in mice. RESULTS Compared with WT mice, CRF2-/- mice exhibited greater serum histamine levels and exacerbated IgE-mediated anaphylaxis and colonic permeability. In addition, CRF2-/- mice exhibited increased serum histamine levels and colonic permeability after acute restraint stress. Experiments with BMMCs and RBL-2H3 MCs demonstrated that CRF2 expressed on MCs suppresses store-operated Ca2+ entry signaling and MC degranulation induced by diverse MC stimuli. Experiments with MC-deficient KitW-sh/W-sh mice systemically engrafted with WT and CRF2-/- BMMCs demonstrated the functional importance of MC CRF2 in modulating stress-induced pathophysiology. CONCLUSIONS MC CRF2 is a negative global modulator of stimuli-induced MC degranulation and limits the severity of IgE-mediated anaphylaxis and stress-related disease pathogenesis.
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Affiliation(s)
- Susan D'Costa
- Thurston Arthritis Research Center, University of North Carolina, Chapel Hill, NC
| | - Saravanan Ayyadurai
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, East Lansing, Mich
| | | | - Emily Mackey
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, East Lansing, Mich; Comparative Biomedical Sciences Program, North Carolina State University, Raleigh, NC
| | - Mrigendra Rajput
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, East Lansing, Mich
| | | | - Neco Wilson
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, East Lansing, Mich
| | - Yihang Li
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, East Lansing, Mich
| | - Eric Kubat
- Department of Surgery, East Bay, University of California, San Francisco, Calif
| | - Ananth Kumar
- Department of Physiology, Michigan State University, East Lansing, Mich
| | | | - Aditi Bhargava
- Department of Surgery and Osher Center for Integrative Medicine, University of California, San Francisco, Calif
| | - Adam J Moeser
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, East Lansing, Mich; Department of Physiology, Michigan State University, East Lansing, Mich.
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Abstract
Mast cells (MCs) are physiologically activated by binding of stem cell factor (SCF) to the extracellular domains of the Kit receptor. This binding increases the proliferation and prolongs the survival of normal mature MCs, as well as intensifies the release of mediators. In mastocytosis, somatic mutations of the coding Kit gene cause autocrine dysregulation and lead to constitutive KIT activation even in the absence of its ligand SCF. Clinical symptoms are caused by MC-mediator release and/or infiltration of MCs into tissues. Aberrant KIT activation may result in increased production of MCs in the skin and extracutaneous organs. Depending on the affected organ(s), the disease can be divided into cutaneous mastocytosis (CM), systemic mastocytosis (SM), and localized MC tumors. The updated classification of WHO discriminates between several distinct subvariants of CM and SM. While the prognosis in CM and indolent SM (ISM) is excellent with (almost) normal life expectancy, the prognosis in aggressive SM (ASM) and MC leukemia (MCL) is dismal. The symptoms may comprise urticaria, angioedema, flush, pruritus, abdominal pain, diarrhea, hypotension, syncope, and musculoskeletal pain and are the results of MC infiltration and mediator release into target organs, i.e., the skin, gastrointestinal tract, liver, spleen, lymph nodes, and bone marrow. Mastocytosis differs from a lot of other hematological disorders because its pathology is not only based on the lack of normal function of a specific pathway or of a specific cell type but additionally is a proliferative disease. Currently available treatments of mastocytosis include symptomatic, antimediator and cytoreductive targeted therapies.
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Ayyadurai S, Gibson AJ, D'Costa S, Overman EL, Sommerville LJ, Poopal AC, Mackey E, Li Y, Moeser AJ. Frontline Science: Corticotropin-releasing factor receptor subtype 1 is a critical modulator of mast cell degranulation and stress-induced pathophysiology. J Leukoc Biol 2017; 102:1299-1312. [PMID: 28684600 DOI: 10.1189/jlb.2hi0317-088rr] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/28/2017] [Accepted: 06/05/2017] [Indexed: 12/23/2022] Open
Abstract
Life stress is a major risk factor in the onset and exacerbation of mast cell-associated diseases, including allergy/anaphylaxis, asthma, and irritable bowel syndrome. Although it is known that mast cells are highly activated upon stressful events, the mechanisms by which stress modulates mast cell function and disease pathophysiology remains poorly understood. Here, we investigated the role of corticotropin-releasing factor receptor subtype 1 (CRF1) in mast cell degranulation and associated disease pathophysiology. In a mast cell-dependent model of IgE-mediated passive systemic anaphylaxis (PSA), prophylactic administration of the CRF1-antagonist antalarmin attenuated mast cell degranulation and hypothermia. Mast cell-deficient KitW-sh/W-sh mice engrafted with CRF1-/- bone marrow-derived mast cells (BMMCs) exhibited attenuated PSA-induced serum histamine, hypothermia, and clinical scores compared with wild-type BMMC-engrafted KitW-sh/W-sh mice. KitW-sh/W-sh mice engrafted with CRF1-/- BMMCs also exhibited suppressed in vivo mast cell degranulation and intestinal permeability in response to acute restraint stress. Genetic and pharmacologic experiments with murine BMMCs, rat RBL-2H3, and human LAD2 mast cells demonstrated that although CRF1 activation did not directly induce MC degranulation, CRF1 signaling potentiated the degranulation responses triggered by diverse mast cell stimuli and was associated with enhanced release of Ca2+ from intracellular stores. Taken together, our results revealed a prominent role for CRF1 signaling in mast cells as a positive modulator of stimuli-induced degranulation and in vivo pathophysiologic responses to immunologic and psychologic stress.
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Affiliation(s)
- Saravanan Ayyadurai
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | | | - Susan D'Costa
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Elizabeth L Overman
- Department of Biology, Methodist University, Fayetteville, North Carolina, USA
| | - Laura J Sommerville
- Department of Pathology, Duke University, School of Medicine, Durham, North Carolina, USA
| | - Ashwini C Poopal
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Emily Mackey
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA.,Comparative Biomedical Sciences Graduate Program, North Carolina State University, Raleigh, North Carolina, USA
| | - Yihang Li
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
| | - Adam J Moeser
- Gastrointestinal Stress Biology Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA; .,Neuroscience Program, Michigan State University, East Lansing, Michigan, USA; and.,Department of Physiology, Michigan State University, East Lansing, Michigan, USA
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7
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Singh J, Shah R, Singh D. Targeting mast cells: Uncovering prolific therapeutic role in myriad diseases. Int Immunopharmacol 2016; 40:362-384. [PMID: 27694038 DOI: 10.1016/j.intimp.2016.09.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Revised: 09/16/2016] [Accepted: 09/22/2016] [Indexed: 01/08/2023]
Abstract
The mast cells are integral part of immune system and they have pleiotropic physiological functions in our body. Any type of abnormal stimuli causes the mast cells receptors to spur the otherwise innocuous mast cells to degranulate and release inflammatory mediators like histamine, cytokines, chemokines and prostaglandins. These mediators are involved in various diseases like allergy, asthma, mastocytosis, cardiovascular disorders, etc. Herein, we describe the receptors involved in degranulation of mast cells and are broadly divided into four categories: G-protein coupled receptors, ligand gated ion channels, immunoreceptors and pattern recognition receptors. Although, activation of pattern recognition receptors do not cause mast cell degranulation, but result in cytokines production. Degranulation itself is a complex process involving cascade of events like membrane fusion events and various proteins like VAMP, Syntaxins, DOCK5, SNAP-23, MARCKS. Furthermore, we described these mast cell receptors antagonists or agonists useful in treatment of myriad diseases. Like, omalizumab anti-IgE antibody is highly effective in asthma, allergic disorders treatment and recently mechanistic insight of IgE uncovered; matrix mettaloprotease inhibitor marimistat is under phase III trial for inflammation, muscular dystrophy diseases; ZPL-389 (H4 receptor antagonist) is in Phase 2a Clinical Trial for atopic dermatitis and psoriasis; JNJ3851868 an oral H4 receptor antagonist is in phase II clinical development for asthma, rheumatoid arthritis. Therefore, research is still in inchoate stage to uncover mast cell biology, mast cell receptors, their therapeutic role in myriad diseases.
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Affiliation(s)
- Jatinder Singh
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala 147002, Punjab, India
| | - Ramanpreet Shah
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala 147002, Punjab, India
| | - Dhandeep Singh
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala 147002, Punjab, India.
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8
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Balseiro-Gomez S, Flores JA, Acosta J, Ramirez-Ponce MP, Ales E. Transient fusion ensures granule replenishment to enable repeated release after IgE-mediated mast cell degranulation. J Cell Sci 2016; 129:3989-4000. [PMID: 27624612 DOI: 10.1242/jcs.194340] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 09/07/2016] [Indexed: 11/20/2022] Open
Abstract
To ensure normal immune function, mast cells employ different pathways to release mediators. Here, we report a thus far unknown capacity of mast cells to recycle and reuse secretory granules after an antigen-evoked degranulation process under physiological conditions; this phenomenon involves the existence of a recycling secretory granule pool that is available for release in a short time scale. Rapid endocytic modes contributed to the recycling of ∼60% of the total secretory granule population, which involved kiss-and-run and cavicapture mechanisms, causing retention of the intragranular matrix. We found the presence of normal-size granules and giant actomyosin- and dynamin-dependent granules, which were characterized by large quantal content. These large structures allowed the recovered mast cells to release a large amount of 5-HT, compensating for the decrease in the number of exocytosed secretory granules. This work uncovers a new physiological role of the exo-endocytosis cycle in the immunological plasticity of mast cells and reveals a new property of their biological secretion.
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Affiliation(s)
- Santiago Balseiro-Gomez
- Departamento Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de 41009 Sevilla, Spain
| | - Juan A Flores
- Departamento Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de 41009 Sevilla, Spain
| | - Jorge Acosta
- Departamento Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de 41009 Sevilla, Spain
| | - M Pilar Ramirez-Ponce
- Departamento Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de 41009 Sevilla, Spain
| | - Eva Ales
- Departamento Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de 41009 Sevilla, Spain
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9
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Maturana CJ, Aguirre A, Sáez JC. High glucocorticoid levels during gestation activate the inflammasome in hippocampal oligodendrocytes of the offspring. Dev Neurobiol 2016; 77:625-642. [PMID: 27314460 DOI: 10.1002/dneu.22409] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 06/13/2016] [Accepted: 06/14/2016] [Indexed: 12/12/2022]
Abstract
Exposure to high levels of glucocorticoids (GCs) during early life induces long-lasting neuroinflammation. GCs induce rapid degranulation of mast cells, which release proinflammatory molecules promoting activation of microglia and astrocytes. The possible involvement of oligodendrocytes, however, remains poorly understood. It was studied whether high GC levels during gestation activates the inflammasome in hippocampal oligodendrocytes of mouse offspring. Oligodendrocytes of control pups showed expression of inflammasome components (NLRP3, ACS, and caspase-1) and their levels were increased by prenatal administration of dexamethasone (DEX), a synthetic GC. These cells also showed high levels of IL-1β and TNF-α, revealing activation of the inflammasome. Moreover, they showed increased levels of the P2X7 receptor and pannexin1, which are associated to inflammasome activation. However, levels of connexins either were not affected (Cx29) or reduced (Cx32 and Cx47). Nonetheless, the functional states of pannexin1 and connexin hemichannels were elevated and directly associated to functional P2X7 receptors. As observed in DEX-treated brain slices, hemichannel activity first increased in hippocampal mast cells and later in microglia and macroglia. DEX-induced oligodendrocyte hemichannel activity was mimicked by urocortin-II, which is a corticotropin-releasing hormone receptor (CRHR) agonist. Response to DEX and urocortin-II was inhibited by antalarmin (a CRHR blocker) or by mast cells or microglia inhibitors. The increase in hemichannel activity persisted for several weeks after birth and cross-fostering with a control mother did not reverse this condition. It is proposed that activation of the oligodendrocyte inflammasome might be relevant in demyelinating diseases associated with early life exposure to high GC levels. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 625-642, 2017.
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Affiliation(s)
- Carola J Maturana
- Departamento De Fisiología, Facultad De Ciencias Biológicas, Pontificia Universidad Católica De Chile, Santiago, Chile.,Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto Milenio, Valparaíso, Chile
| | - Adam Aguirre
- Departamento De Fisiología, Facultad De Ciencias Biológicas, Pontificia Universidad Católica De Chile, Santiago, Chile
| | - Juan C Sáez
- Departamento De Fisiología, Facultad De Ciencias Biológicas, Pontificia Universidad Católica De Chile, Santiago, Chile.,Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto Milenio, Valparaíso, Chile
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10
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Balseiro-Gomez S, Ramirez-Ponce MP, Acosta J, Ales E, Flores JA. Intestinal and peritoneal mast cells differ in kinetics of quantal release. Biochem Biophys Res Commun 2015; 469:559-64. [PMID: 26692491 DOI: 10.1016/j.bbrc.2015.12.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 12/09/2015] [Indexed: 10/22/2022]
Abstract
5-hydroxytriptamine (5-HT, serotonin) storage and release in mast cell (MC) secretory granules (SG) are dependent on serglycin proteoglycans (PG). This notion is based on the studies of MC of the connective tissue subtype that predominantly contain PG of the heparin type, whereas intestinal mucosal MC, which contain predominantly chondroitin sulfate, have been poorly explored. In the present study, we addressed the possibility that PG contents may differently affect the storage and release of preformed mediators in these two MC subclasses and explain in part their different functional properties. Rat peritoneal (PMC) and intestinal mast cells (IMC) were isolated and purified using a percoll gradient, and the efflux of 5-HT from each SG was measured by amperometric detection. IMC exhibited a ∼34% reduction in the release of 5-HT compared with PMC because of a lower number of exocytotic events, rather than a lower secretion per single exocytotic event. Amperometric spikes from IMC exhibited a slower decay phase and increased half-width but a similar ascending phase and foot parameters, indicating that the fusion pore kinetics are comparable in both MC subclasses. We conclude that both PG subtypes are equally efficient systems, directly involved in serotonin accumulation, and play a crucial role in regulating the kinetics of exocytosis from SG, providing specific secretory properties for the two cellular subtypes.
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Affiliation(s)
- Santiago Balseiro-Gomez
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009 Seville, Spain.
| | - M Pilar Ramirez-Ponce
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009 Seville, Spain.
| | - Jorge Acosta
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009 Seville, Spain.
| | - Eva Ales
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009 Seville, Spain.
| | - Juan A Flores
- Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, 41009 Seville, Spain.
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