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Muscarinic Receptors and BK Channels Are Affected by Lipid Raft Disruption of Salivary Gland Cells. Int J Mol Sci 2021; 22:ijms22094780. [PMID: 33946369 PMCID: PMC8125525 DOI: 10.3390/ijms22094780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 01/31/2023] Open
Abstract
Activity-dependent fluid secretion is the most important physiological function of salivary glands and is regulated via muscarinic receptor signaling. Lipid rafts are important for G-protein coupled receptor (GPCR) signaling and ion channels in plasma membranes. However, it is not well understood whether lipid raft disruption affects all membrane events or only specific functions in muscarinic receptor-mediated water secretion in salivary gland cells. We investigated the effects of lipid raft disruption on the major membrane events of muscarinic transcellular water movement in human salivary gland (HSG) cells. We found that incubation with methyl-β-cyclodextrin (MβCD), which depletes lipid rafts, inhibited muscarinic receptor-mediated Ca2+ signaling in HSG cells and isolated mouse submandibular acinar cells. However, MβCD did not inhibit a Ca2+ increase induced by thapsigargin, which activates store-operated Ca2+ entry (SOCE). Interestingly, MβCD increased the activity of the large-conductance Ca2+-activated K+ channel (BK channel). Finally, we found that MβCD did not directly affect the translocation of aquaporin-5 (AQP5) into the plasma membrane. Our results suggest that lipid rafts maintain muscarinic Ca2+ signaling at the receptor level without directly affecting the activation of SOCE induced by intracellular Ca2+ pool depletion or the translocation of AQP5 into the plasma membrane.
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Intracellular accumulation of PD-1 molecules in circulating T lymphocytes in advanced malignant melanoma: an implication for immune evasion mechanism. Int J Clin Oncol 2020; 25:1861-1869. [PMID: 32656742 DOI: 10.1007/s10147-020-01732-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 06/21/2020] [Indexed: 12/16/2022]
Abstract
BACKGROUND The blockade of cell surface PD-1 ((sur)PD-1) by monoclonal antibodies, represented by nivolumab, provides the strategy to treat advanced malignant melanoma (AMM). The intracellular presence of PD-1 molecules have been reported in some T cell subsets, however, their kinetic association with those expressed on the cell surface, let alone their significance in antitumor immunity has been ill-investigated. METHODS Intracellular PD-1 expression status in T cell subsets in AMM cases during nivolumab administration was chronologically characterized. The kinetics of PD-1 molecules within AMM-derived T cells was assessed in vitro in conjunction with their functional properties. RESULTS Increase in (sur)PD-1 and intracellular PD-1 ((int)PD-1+) expression was characteristic for AMM T cells. After short-term culture, virtually (sur)PD-1- nivolumab-treated AMM T cells restore (sur)PD-1 expression, which could not be explained by the detachment of nivolumab from PD-1 epitopes alone. The blockade of trans-Golgi network resulted in the decrease in the extent of (sur)PD-1 recovery, suggesting the translocation of accumulated (int)PD-1 to the cell surface. Antigen-specific PD-1+ T cells significantly increased in (int)PD-1+ cells after treatment. In addition, a surge in (int)PD-1+CD4+ T cells was observed prior to the emergence of skin rash as an immune-related adverse event (irAE). CONCLUSIONS Accumulated (int)PD-1 in T cells may contribute to enhanced immune evasion in AMM. Evaluation of intracellular PD-1 expression would be useful for better management of nivolumab-treated AMM patients in view of predicting treatment response and the incidence of irAE. Our findings further support the necessity of periodical administration of nivolumab for treating AMM.
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Chernyavsky A, Patel KG, Grando SA. Mechanisms of synergy of autoantibodies to M3 muscarinic acetylcholine receptor and secretory pathway Ca 2+/Mn 2+-ATPase isoform 1 in patients with non-desmoglein pemphigus vulgaris. Int Immunopharmacol 2020; 80:106149. [PMID: 31958740 DOI: 10.1016/j.intimp.2019.106149] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 12/14/2019] [Accepted: 12/20/2019] [Indexed: 01/03/2023]
Abstract
Pemphigus vulgaris (PV) is a potentially lethal mucocutaneous blistering disease characterized by IgG autoantibodies (AuAbs) binding to epidermal keratinocytes and inducing a devastating blistering disease affecting oral and/or esophageal surfaces and, sometimes, also the skin. Anti-keratinocyte AuAbs developed by the desmoglein (Dsg) 1/3 AuAb-negative acute PV patients are pathogenic, as they induced acantholysis and epidermal split in the experimental models of PV in vitro and in vivo. These PV patients have various combinations of AuAbs to keratinocyte muscarinic acetylcholine receptor subtype M3 (M3AR), the secretory pathway Ca2+/Mn2+-ATPase isoform 1 (SPCA1), and desmocollin 3 whose relative concentrations correlate with the disease activity. In this study, we identified new molecular mechanisms of the synergistic cooperation of AuAbs to M3AR and SPCA1 in inducing acantholysis in the anti-Dsg 1/3 AuAb-negative PV patients. Anti-M3AR AuAb was found to play an important role in determining the level of intraepidermal split just above the basal cells, caspase to mediate early pro-apoptotic events triggered by anti-SPCA1 AuAb, and the neonatal Fc receptor (FcRn) to contribute to the pathobiological actions of both anti-M3AR and anti-SPCA1 AuAbs. Altogether, these novel results support our original hypothesis that pemphigus acantholysis is a complex disease process (also known as apoptolysis) initiated by AuAbs directed against different keratinocyte proteins that play important roles in supporting cell viability and regulating vital cell functions.
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Affiliation(s)
- Alex Chernyavsky
- Department of Dermatology, University of California Irvine, CA, USA
| | - Krupa G Patel
- Oakland University William Beaumont School of Medicine, Rochester, MI, USA
| | - Sergei A Grando
- Department of Dermatology, University of California Irvine, CA, USA; Department of Biological Chemistry, University of California Irvine, CA, USA; Institute for Immunology, University of California Irvine, CA, USA.
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Choi SS, Jang E, Jang K, Jung SJ, Hwang KG, Youn J. Autoantibody-Mediated Dysfunction of Salivary Glands Leads to Xerostomia in SKG Mice. Immune Netw 2019; 19:e44. [PMID: 31921474 PMCID: PMC6943169 DOI: 10.4110/in.2019.19.e44] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/29/2019] [Accepted: 12/13/2019] [Indexed: 01/10/2023] Open
Abstract
Sjögren's syndrome (SS) is a chronic heterogeneous disease that mainly affects exocrine glands, leading to sicca syndromes such as xerostomia. Despite the second highest prevalence rate among systemic autoimmune diseases, its pathophysiology remains largely unknown. Here we report that SKG mice, a cardinal model of Th17 cell-mediated arthritis, also develop a secondary form of SS-like disorder upon systemic exposure to purified curdlan, a type of β-glucan. The reduced production of saliva was not caused by focal immune cell infiltrates but was associated with IgG deposits in salivary glands. Sera from curdlan-injected SKG mice contained elevated titers of IgG (predominantly IgG1), autoantibody to the muscarinic type 3 receptor (M3R) and inhibited carbachol-induced Ca2+ signaling in salivary acinar cells. These results suggest that the Th17 cells that are elicited in SKG mice promote the production of salivary gland-specific autoantibodies including anti-M3R IgG; the antibodies are then deposited on acinar cells and inhibit M3R-mediated signaling required for salivation, finally leading to hypofunction of the salivary glands. This type II hypersensitivity reaction may explain the origin of secondary SS occurring without focal leukocyte infiltrates.
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Affiliation(s)
- Suk San Choi
- Laboratory of Autoimmunology, Department of Anatomy and Cell Biology, Hanyang University College of Medicine, Seoul 04763, Korea
| | - Eunkyeong Jang
- Laboratory of Autoimmunology, Department of Anatomy and Cell Biology, Hanyang University College of Medicine, Seoul 04763, Korea
| | - Kiseok Jang
- Department of Pathology, Hanyang University College of Medicine, Seoul 04763, Korea
| | - Sung Jun Jung
- Department of Physiology, Hanyang University College of Medicine, Seoul 04763, Korea
| | - Kyung-Gyun Hwang
- Division of Oral & Maxillofacial Surgery, Department of Dentistry, Hanyang University College of Medicine, Seoul 04763, Korea
| | - Jeehee Youn
- Laboratory of Autoimmunology, Department of Anatomy and Cell Biology, Hanyang University College of Medicine, Seoul 04763, Korea
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Disruption of endothelial barrier function is linked with hyposecretion and lymphocytic infiltration in salivary glands of Sjögren's syndrome. Biochim Biophys Acta Mol Basis Dis 2018; 1864:3154-3163. [DOI: 10.1016/j.bbadis.2018.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Revised: 05/17/2018] [Accepted: 07/02/2018] [Indexed: 11/18/2022]
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Han X, Liu Y, Kam WR, Sullivan DA. Effect of brimonidine, an α2 adrenergic agonist, on human meibomian gland epithelial cells. Exp Eye Res 2018; 170:20-28. [PMID: 29452108 DOI: 10.1016/j.exer.2018.02.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/09/2018] [Accepted: 02/12/2018] [Indexed: 01/15/2023]
Abstract
We recently discovered that the anti-glaucoma pharmaceuticals timolol, a β adrenergic antagonist, and pilocarpine, a cholinergic compound, negatively influence the morphology, proliferative capacity and survival of human meibomian gland epithelial cells (HMGECs). We hypothesize that another class of anti-glaucoma drugs, the α2 adrenergic agonists, also acts directly on HMGECs to affect their structure and function. We tested this hypothesis. Immortalized (i) HMGECs were cultured with brimonidine, as well as clonidine (α2 agonist), phenylephrine (α1 agonist), RX821002 (inverse α2 agonist) and MK912 (neutral α2 agonist) for up to 7 days. Cells were counted with a hemocytometer, and evaluated for morphology, signaling pathway activity, protein biomarker expression, and the accumulation of neutral lipids, phospholipids and lysosomes. Our findings demonstrate that brimondine treatment induces a dose-dependent decrease in Akt signaling and proliferation of iHMGECs. In contrast, brimonidine also promotes a dose-dependent differentiation of iHMGECs, including an increase in neutral lipid, phospholipid and lysosome levels. These effects were paralleled by an inhibition of p38 signaling, and duplicated by cellular exposure to clonidine, but not phenylephrine. Brimonidine also enhanced the cellular content of sterol regulatory binding protein-1, a master regulator of lipid synthesis. Of particular interest, the putative α2 antagonists, RX821002 and MK912, did not interfere with brimonidine action, but rather stimulated IHMGEC differentiation. Our results support our hypothesis and demonstrate that α2 adrenergic agonists act directly on iHMGECs. However, these compounds do not elicit an overall negative effect. Rather, the α2 agonists promote the differentiation of iHMGECs.
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Affiliation(s)
- Xi Han
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA; Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yang Liu
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Wendy R Kam
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - David A Sullivan
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.
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Mahmoud TI, Wang J, Karnell JL, Wang Q, Wang S, Naiman B, Gross P, Brohawn PZ, Morehouse C, Aoyama J, Wasserfall C, Carter L, Atkinson MA, Serreze DV, Braley-Mullen H, Mustelin T, Kolbeck R, Herbst R, Ettinger R. Autoimmune manifestations in aged mice arise from early-life immune dysregulation. Sci Transl Med 2017; 8:361ra137. [PMID: 27798262 DOI: 10.1126/scitranslmed.aag0367] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/19/2016] [Indexed: 12/13/2022]
Abstract
Autoantibodies can be present years to decades before the onset of disease manifestations in autoimmunity. This finding suggests that the initial autoimmune trigger involves a peripheral lymphoid component, which ultimately drives disease pathology in local tissues later in life. We show that Sjögren's syndrome manifestations that develop in aged NOD.H-2h4 mice were driven by and dependent on peripheral dysregulation that arose in early life. Specifically, elimination of spontaneous germinal centers in spleens of young NOD.H-2h4 mice by transient blockade of CD40 ligand (CD40L) or splenectomy abolished Sjögren's pathology of aged mice. Strikingly, a single injection of anti-CD40L at 4 weeks of age prevented tertiary follicle neogenesis and greatly blunted the formation of key autoantibodies implicated in glandular pathology, including anti-muscarinic receptor antibodies. Microarray profiling of the salivary gland characterized the expression pattern of genes that increased with disease progression and showed that early anti-CD40L greatly repressed B cell function while having a broader effect on multiple biological pathways, including interleukin-12 and interferon signaling. A single prophylactic treatment with anti-CD40L also inhibited the development of autoimmune thyroiditis and diabetes in NOD.H-2h4 and nonobese diabetic mice, respectively, supporting a key role for CD40L in the pathophysiology of several autoimmune models. These results strongly suggest that early peripheral immune dysregulation gives rise to autoimmune manifestations later in life, and for diseases predated by autoantibodies, early prophylactic intervention with biologics may prove efficacious.
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Affiliation(s)
- Tamer I Mahmoud
- Respiratory, Inflammation, and Autoimmunity Group, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Jingya Wang
- Respiratory, Inflammation, and Autoimmunity Group, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Jodi L Karnell
- Respiratory, Inflammation, and Autoimmunity Group, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Qiming Wang
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Shu Wang
- Respiratory, Inflammation, and Autoimmunity Group, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Brian Naiman
- Respiratory, Inflammation, and Autoimmunity Group, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Phillip Gross
- Respiratory, Inflammation, and Autoimmunity Group, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Philip Z Brohawn
- Translational Sciences-Pharmacogenomics, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Chris Morehouse
- Translational Sciences-Pharmacogenomics, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Jordan Aoyama
- Translational Sciences-Pharmacogenomics, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Clive Wasserfall
- Departments of Pathology and Pediatrics, University of Florida, Gainesville, FL 32610, USA
| | - Laura Carter
- Respiratory, Inflammation, and Autoimmunity Group, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Mark A Atkinson
- Departments of Pathology and Pediatrics, University of Florida, Gainesville, FL 32610, USA
| | | | | | - Tomas Mustelin
- Respiratory, Inflammation, and Autoimmunity Group, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Roland Kolbeck
- Respiratory, Inflammation, and Autoimmunity Group, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Ronald Herbst
- Respiratory, Inflammation, and Autoimmunity Group, MedImmune LLC, Gaithersburg, MD 20878, USA
| | - Rachel Ettinger
- Respiratory, Inflammation, and Autoimmunity Group, MedImmune LLC, Gaithersburg, MD 20878, USA.
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Alam J, Koh JH, Kim N, Kwok SK, Park SH, Song YW, Park K, Choi Y. Detection of autoantibodies against aquaporin-5 in the sera of patients with primary Sjögren's syndrome. Immunol Res 2017; 64:848-56. [PMID: 26786004 PMCID: PMC4930796 DOI: 10.1007/s12026-016-8786-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The pathophysiology of exocrine dysfunction observed in Sjögren's syndrome (SS) is not fully understood. The purpose of this study was to investigate whether autoantibodies against human AQP5 are present in the sera of SS patients. Frozen sections of mouse submandibular salivary glands, CHO cells over-expressing a human AQP5-GFP fusion protein or GFP, and MDCK cells over-expressing AQP5 were used in the indirect immunofluorescence assay to detect anti-AQP5 autoantibodies in the sera from patients with primary SS. The lysates of HEK-293 cells over-expressing the AQP5-GFP fusion protein or GFP were used for immunoprecipitation. Serum IgG from the SS patients but not from the control subjects stained acinar cells in the mouse salivary glands, the signals of which colocalized with those of AQP5-specific antibodies. Serum IgG from the SS patients also selectively stained AQP5-GFP expressed in CHO cells. However, both the control and SS sera immunoprecipitated the AQP5-GFP, suggesting that autoantibodies against AQP5 were also present in the control sera. The screening of 53 control and 112 SS samples by indirect immunofluorescence assay using the AQP5-expressing MDCK cells revealed the presence of significantly higher levels of anti-AQP5 IgG in the SS samples than in the control samples with sensitivity of 0.73 and a specificity of 0.68. Furthermore, the presence of anti-AQP5 autoantibodies was associated with low resting salivary flow in SS patients. In conclusion, anti-AQP5 autoantibodies were detected in the sera from SS patients, which could be a novel biomarker of SS and provide new insight into the pathogenesis of SS.
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Affiliation(s)
- Jehan Alam
- Department of Oral Microbiology and Immunology, School of Dentistry and Dental Research Institute, Seoul National University, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea
| | - Jung Hee Koh
- Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - Nahyun Kim
- Department of Oral Microbiology and Immunology, School of Dentistry and Dental Research Institute, Seoul National University, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea
| | - Seung-Ki Kwok
- Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - Sung-Hwan Park
- Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - Yeong Wook Song
- College of Medicine, Seoul National University, Seoul, Republic of Korea
| | - Kyungpyo Park
- Department of Oral Physiology, School of Dentistry, Seoul National University, Seoul, Republic of Korea
| | - Youngnim Choi
- Department of Oral Microbiology and Immunology, School of Dentistry and Dental Research Institute, Seoul National University, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.
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Effect of anti-muscarinic autoantibodies on leukocyte function in Sjögren's syndrome. Mol Immunol 2017; 90:136-142. [PMID: 28750255 DOI: 10.1016/j.molimm.2017.07.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 07/04/2017] [Accepted: 07/10/2017] [Indexed: 02/06/2023]
Abstract
Patients with primary Sjögren's syndrome, a systemic autoimmune disease, have been shown to have serum autoantibodies that react with the muscarinic acetylcholine type 3 receptor (M3R).Primary Sjögren's syndrome is a systemic autoimmune disease. Patients with primary Sjögren's syndrome have been shown to have serum autoantibodies that react with the muscarinic acetylcholine type 3 receptor (M3R). Leukopenia has been reported to be significantly more common in primary Sjögren's syndrome patients who have anti-M3R-autoantibodies in their sera. In this study, we investigated whether these anti-M3R autoantibodies have effects on M3R and MHCI expression in Jurkat T cells. Purified IgG antibodies were isolated from the serum of healthy individuals and primary Sjögren's syndrome patients. Jurkat cell line was used to represent T lymphocytes. In situ immunofluorescence confocal microscopy was used to confirm the binding reactivity of primary Sjögren's syndrome IgG antibodies to M3R. Co-immunoprecipitation and immunofluorescence results suggested a direct interaction between M3R and MHC I. Co-internalization of M3R and MHC I was observed when Jurkat cells were exposed to the primary Sjögren's syndrome IgG, but this primary Sjögren's syndrome IgG-induced co-internalization of M3R and MHC I was prevented by the presence of exogenous IFN-γ. Primary Sjögren's syndrome IgG itself did not affect the viability of Jurkat cells, but Jurkat cells exposed to primary Sjögren's syndrome IgG were observed to undergo significant cell death when co-cultured with primary Natural Killer cells. Our results suggest that anti-M3R autoantibodies in primary Sjögren's syndrome induce downregulation of plasma membrane-resident M3R and MHC class I molecules in leukocytes followed by NK cell-mediated cell death. This mechanism may explain the frequency of leukopenia occurrence in patients with primary Sjögren's syndrome.
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Alam J, Koh JH, Kwok SK, Park SH, Park K, Choi Y. Functional Epitopes for Anti-Aquaporin 5 Antibodies in Sjögren Syndrome. J Dent Res 2017; 96:1414-1421. [PMID: 28665757 DOI: 10.1177/0022034517717965] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We recently reported the presence of anti-aquaporin 5 (AQP5) immunoglobulin G (IgG) in patients with primary Sjögren syndrome (SS) with a sensitivity of 0.73 and a specificity of 0.68. The aim of this study was to identify functional epitopes for the anti-AQP5 autoantibodies detected in control subjects and patients with SS. Recognition of epitopes by anti-AQP5 autoantibodies in sera ( n = 13 for control and n = 24 for SS) or purified IgG ( n = 1 for control and n = 3 for SS) was evaluated by indirect immunofluorescence (IIF) assay performed in the presence or absence of peptides corresponding to the second transmembrane helix and extracellular loops A, C, and E of AQP5. Functional epitopes were determined by measuring the effects of purified IgG and neutralizing peptides on transepithelial osmotic permeability (PfT) of MDCK cells expressing AQP5. In the IIF assay, 89% of SS samples were inhibited by at least 1 peptide, while only half of control samples were inhibited by any peptide. Overall, SS samples were inhibited by peptides corresponding to extracellular loops A, C, and E by 40% to 50%, whereas control samples were inhibited only by peptides corresponding to loop E by <20%. A cyclized peptide (E1) mimicking loop E was most frequently recognized and best differentiated between the SS and control samples. Incubation of MDCK-AQP5 cells with SS but not with control IgG, significantly decreased PfT, which was reversed by neutralization of IgG binding to any of the extracellular loops. In conclusion, the anti-AQP5 autoantibodies detected in control and SS groups showed differences in fine specificity to the functional epitopes of AQP5. The prevalent recognition of functional epitopes by anti-AQP5 autoantibodies from SS patients suggests that anti-AQP5 autoantibodies act as mediators of glandular hypofunction and are a potential therapeutic target in SS.
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Affiliation(s)
- J Alam
- 1 School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
| | - J H Koh
- 2 Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - S-K Kwok
- 2 Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - S-H Park
- 2 Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - K Park
- 1 School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
| | - Y Choi
- 1 School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
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Role of flotillins in the endocytosis of GPCR in salivary gland epithelial cells. Biochem Biophys Res Commun 2016; 476:237-244. [DOI: 10.1016/j.bbrc.2016.05.103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 05/20/2016] [Indexed: 11/21/2022]
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Zuo J, Williams AEG, Park YJ, Choi K, Chan AL, Reeves WH, Bubb MR, Lee YJ, Park K, Stewart CM, Cha S. Muscarinic type 3 receptor autoantibodies are associated with anti-SSA/Ro autoantibodies in Sjögren's syndrome. J Immunol Methods 2016; 437:28-36. [PMID: 27460476 DOI: 10.1016/j.jim.2016.07.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 07/22/2016] [Accepted: 07/22/2016] [Indexed: 01/05/2023]
Abstract
Anti-muscarinic type 3 receptor autoantibodies (anti-M3R) are reported as potential inhibitors of saliva secretion in Sjögren's syndrome (SjS). However, despite extensive efforts to establish an anti-M3R detection method, there is no clinical test available for these autoantibodies. The purpose of this study was to propose inclusion of anti-M3R testing for SjS diagnosis through investigation of their prevalence using a modified In-Cell Western (ICW) assay. A stable cell line expressing human M3R tagged with GFP (M3R-GFP) was established to screen unadsorbed and adsorbed plasma from primary SjS (n=24), rheumatoid arthritis (RA, n=18), systemic lupus erythematosus (SLE, n=18), and healthy controls (HC, n=23). Anti-M3R abundance was determined by screening for the intensity of human IgG interacting with M3R-GFP cells by ICW assay, as detected by an anti-human IgG IRDye800-conjugated secondary antibody and normalized to GFP. Method comparisons and receiver-operating-characteristic (ROC)-curve analyses were performed to evaluate the diagnostic value of our current approaches. Furthermore, clinical parameters of SjS were also analyzed in association with anti-M3R. Anti-M3R was significantly elevated in SjS plasma in comparison with HC, SLE, or RA (P<0.01). SjS anti-M3R intensities were greater than two-standard deviations above the HC mean for both unadsorbed (16/24, 66.67%) and adsorbed (18/24, 75%) plasma samples. Furthermore, anti-M3R was associated with anti-SjS-related-antigen A/Ro positivity (P=0.0353). Linear associations for anti-M3R intensity indicated positive associations with focus score (R(2)=0.7186, P<0.01) and negative associations with saliva flow rate (R(2)=0.3052, P<0.05). Our study strongly supports our rationale to propose inclusion of anti-M3R for further testing as a non-invasive serological marker for SjS diagnosis.
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Affiliation(s)
- Jian Zuo
- Departments of Oral and Maxillofacial Diagnostic Sciences, University of Florida College of Dentistry, Gainesville, FL 32610, USA
| | - Adrienne E G Williams
- Departments of Oral and Maxillofacial Diagnostic Sciences, University of Florida College of Dentistry, Gainesville, FL 32610, USA
| | - Yun-Jong Park
- Departments of Oral and Maxillofacial Diagnostic Sciences, University of Florida College of Dentistry, Gainesville, FL 32610, USA
| | - Kevin Choi
- Departments of Oral and Maxillofacial Diagnostic Sciences, University of Florida College of Dentistry, Gainesville, FL 32610, USA
| | - Annie L Chan
- Department of Rheumatology and Clinical Immunology, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Westley H Reeves
- Department of Rheumatology and Clinical Immunology, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Michael R Bubb
- Department of Rheumatology and Clinical Immunology, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Yun Jong Lee
- Division of Rheumatology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Kyungpyo Park
- Department of Physiology, School of Dentistry, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Carol M Stewart
- Departments of Oral and Maxillofacial Diagnostic Sciences, University of Florida College of Dentistry, Gainesville, FL 32610, USA
| | - Seunghee Cha
- Departments of Oral and Maxillofacial Diagnostic Sciences, University of Florida College of Dentistry, Gainesville, FL 32610, USA.
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Muscarinic cholinergic receptors (MR3) in saliva of patients with oral lichen planus. Arch Dermatol Res 2016; 308:481-6. [DOI: 10.1007/s00403-016-1670-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 05/10/2016] [Accepted: 06/27/2016] [Indexed: 01/04/2023]
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14
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Glišić S, Cavanaugh DP, Chittur KK, Sencanski M, Perovic V, Bojić T. Common molecular mechanism of the hepatic lesion and the cardiac parasympathetic regulation in chronic hepatitis C infection: a critical role for the muscarinic receptor type 3. BMC Bioinformatics 2016; 17:139. [PMID: 27000565 PMCID: PMC4802633 DOI: 10.1186/s12859-016-0988-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 03/14/2016] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND The pathophysiological overlapping between Sjorgen's Syndrome (SS) and HCV, presence of anti- muscarinic receptor type 3 (M3R) antibodies in SS, the role that M3R plays in the regulation of the heart rate, has led to the assumption that cardiovagal dysfunction in HCV patients is caused by anti-M3R antibodies elicited by HCV proteins or by their direct interaction with M3R. RESULTS To identify HCV protein which possibly is crossreactive with M3R or which binds to this receptor, we performed the Informational Spectrum Method (ISM) analysis of the HCV proteome. This analysis revealed that NS5A protein represents the most probable interactor of M3R or that this viral protein could elicit antibodies which modulate function of this receptor. Further detailed structure/function analysis of NS5A and M3R performed by the ISM method extended with other Digital Signal processing (DSP) approaches revealed domains of these proteins which participate in their crossreactivity or in their direct interaction, representing promising diagnostic and therapeutic targets. CONCLUSIONS Application of the ISM with other compatible bioinformatics methods offers new perspectives for identifying diagnostic and therapeutic targets for complicated forms of HCV and other viral infections. We show how the electron-ion interaction potential (EIIP) amino-acid scale used in the ISM combined with a robust, high performance hydrophobicity scale can provide new insights for understanding protein structure/function and protein-protein interactions.
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Affiliation(s)
- Sanja Glišić
- Institute of Nuclear Sciences Vinča, University of Belgrade, Center for Multidisciplinary Research, PO Box 522, Belgrade, Serbia
| | | | - Krishnan K Chittur
- Chemical and Materials Engineering, University of Alabama Huntsville, Huntsville, AL, 35899, USA
| | - Milan Sencanski
- Institute of Nuclear Sciences Vinča, University of Belgrade, Center for Multidisciplinary Research, PO Box 522, Belgrade, Serbia
| | - Vladimir Perovic
- Institute of Nuclear Sciences Vinča, University of Belgrade, Center for Multidisciplinary Research, PO Box 522, Belgrade, Serbia
| | - Tijana Bojić
- Institute of Nuclear Sciences Vinča, University of Belgrade, Laboratory of Radiobiology and Molecular Genetics, PO Box 522, 11000, Belgrade, Serbia.
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A novel cell-based assay for inhibitory anti-muscarinic type 3 receptor antibodies in primary Sjögren’s syndrome. J Immunol Methods 2015; 427:117-21. [DOI: 10.1016/j.jim.2015.11.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 10/04/2015] [Accepted: 11/11/2015] [Indexed: 11/21/2022]
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16
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Namkoong E, Shin YH, Bae JS, Choi S, Kim M, Kim N, Hwang SM, Park K. Role of Sodium Bicarbonate Cotransporters in Intracellular pH Regulation and Their Regulatory Mechanisms in Human Submandibular Glands. PLoS One 2015; 10:e0138368. [PMID: 26375462 PMCID: PMC4573515 DOI: 10.1371/journal.pone.0138368] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 08/28/2015] [Indexed: 01/16/2023] Open
Abstract
Sodium bicarbonate cotransporters (NBCs) are involved in the pH regulation of salivary glands. However, the roles and regulatory mechanisms among different NBC isotypes have not been rigorously evaluated. We investigated the roles of two different types of NBCs, electroneutral (NBCn1) and electrogenic NBC (NBCe1), with respect to pH regulation and regulatory mechanisms using human submandibular glands (hSMGs) and HSG cells. Intracellular pH (pHi) was measured and the pHi recovery rate from cell acidification induced by an NH4Cl pulse was recorded. Subcellular localization and protein phosphorylation were determined using immunohistochemistry and co-immunoprecipitation techniques. We determined that NBCn1 is expressed on the basolateral side of acinar cells and the apical side of duct cells, while NBCe1 is exclusively expressed on the apical membrane of duct cells. The pHi recovery rate in hSMG acinar cells, which only express NBCn1, was not affected by pre-incubation with 5 μM PP2, an Src tyrosine kinase inhibitor. However, in HSG cells, which express both NBCe1 and NBCn1, the pHi recovery rate was inhibited by PP2. The apparent difference in regulatory mechanisms for NBCn1 and NBCe1 was evaluated by artificial overexpression of NBCn1 or NBCe1 in HSG cells, which revealed that the pHi recovery rate was only inhibited by PP2 in cells overexpressing NBCe1. Furthermore, only NBCe1 was significantly phosphorylated and translocated by NH4Cl, which was inhibited by PP2. Our results suggest that both NBCn1 and NBCe1 play a role in pHi regulation in hSMG acinar cells, and also that Src kinase does not regulate the activity of NBCn1.
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Affiliation(s)
- Eun Namkoong
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Yong-Hwan Shin
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Jun-Seok Bae
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Seulki Choi
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Minkyoung Kim
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Nahyun Kim
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Sung-Min Hwang
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
| | - Kyungpyo Park
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, 110-749, Korea
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17
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Takagi Y, Sumi M, Nakamura H, Sato S, Kawakami A, Nakamura T. Salivary gland ultrasonography as a primary imaging tool for predicting efficacy of xerostomia treatment in patients with Sjögren’s syndrome. Rheumatology (Oxford) 2015; 55:237-45. [DOI: 10.1093/rheumatology/kev278] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Indexed: 12/14/2022] Open
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18
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Kim N, Shin Y, Choi S, Namkoong E, Kim M, Lee J, Song Y, Park K. Effect of Antimuscarinic Autoantibodies in Primary Sjögren's Syndrome. J Dent Res 2015; 94:722-8. [PMID: 25784251 DOI: 10.1177/0022034515577813] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The presence of functional autoantibodies against the muscarinic type 3 receptor (M3R) has been reported in primary Sjögren's syndrome (pSS). However, the pathogenic role of these autoantibodies in pSS development remains to be elucidated. In this experiment, we investigated a pathologic role of pSS autoantibodies (pSS IgG) associated with downregulation of the major histocompatibility complex I (MHC I) molecule with M3R through internalization. Anti-M3R autoantibodies in purified control and pSS IgG were detected using 4 synthesized cyclic M3R peptides by enzyme-linked immunosorbent assay. The binding reactivity of pSS IgG to M3R in situ was analyzed by a dual immunostaining method. Surface expression, interaction, and internalization of M3R with MHC I were analyzed by immunofluorescence confocal microscopy and biochemical assays. Synthetic cyclic peptides M3RP(205-221) and M3RP(520-527) showed significantly high reactivity with pSS IgG compared to the control IgG or the other 3 peptides (P < 0.05). Significantly high reactivity of pSS IgG to M3R in situ was observed. PSS IgG increased the interaction of membrane M3R with MHC I and induced their internalization in primary human submandibular gland cells. The pSS IgG-induced internalization of M3R with MHC I was significantly inhibited by the cholesterol-sequestering drug filipin. Our novel finding-namely, strong downregulation of the membrane MHC I with M3R through internalization of the cholesterol-rich microdomain associating with anti-M3R autoantibodies-could be an important mechanism contributing to the impaired salivation seen in pSS and linking secretory hypofunction to autoimmune pathogenesis.
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Affiliation(s)
- N Kim
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, Republic of Korea
| | - Y Shin
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, Republic of Korea
| | - S Choi
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, Republic of Korea
| | - E Namkoong
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, Republic of Korea
| | - M Kim
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, Republic of Korea
| | - J Lee
- Oral and Maxillofacial Surgery, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, Republic of Korea
| | - Y Song
- Internal Medicine, College of Medicine, Seoul National University, Seoul, Republic of Korea
| | - K Park
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul, Republic of Korea
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19
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Lee K, Choi S, Choi LM, Lee J, Kim JH, Chung G, Lee G, Choi SY, Park K. Desipramine inhibits salivary Ca(2+) signaling and aquaporin translocation. Oral Dis 2015; 21:530-5. [PMID: 25639149 DOI: 10.1111/odi.12317] [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: 06/11/2014] [Revised: 01/19/2015] [Accepted: 01/20/2015] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Desipramine is a tricyclic antidepressant with a negative side effect of dry mouth. The Na(+) /H(+) exchanger was suggested to be a target of desipramine in salivary gland cells. However, it is unclear whether desipramine has other targets in the salivary secretion pathway. Here, we studied the effect of desipramine on salivary Ca(2+) signaling. MATERIALS AND METHODS Cytosolic free Ca(2+) concentration ([Ca(2+) ]i ) was determined with the fluorescent Ca(2+) indicator fura-2/AM. Aquaporin translocation was analyzed by Western blotting and immunocytochemistry of confocal microscopy. RESULTS Desipramine inhibited the carbachol- and histamine-mediated increase in cytosolic Ca(2+) ([Ca(2+) ]i ) in a concentration-dependent manner. However, desipramine did not affect increases in [Ca(2+) ]i mediated by extracellular ATP, sphingosine-1-phosphate, or thapsigargin. The adrenergic receptor blockers prazosin and propranolol did not reverse the desipramine-mediated inhibition of carbachol- and histamine-induced increases in [Ca(2+) ]i . We also found that desipramine inhibits the increase in membrane aquaporin-5 level triggered by carbachol and histamine treatments. CONCLUSIONS These results imply that desipramine blocks muscarinic and histamine receptor-mediated Ca(2+) signaling and the subsequent translocation of aquaporin-5 in human salivary gland cells, suggesting a novel mechanism for the xerogenic effects of desipramine.
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Affiliation(s)
- K Lee
- Department of Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Korea
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20
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Choi S, Shin YH, Namkoong E, Hwang SM, Cong X, Yu G, Park K. TRPV1 in Salivary Gland Epithelial Cells Is Not Involved in Salivary Secretion via Transcellular Pathway. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2015; 18:525-30. [PMID: 25598668 PMCID: PMC4296043 DOI: 10.4196/kjpp.2014.18.6.525] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 11/12/2014] [Accepted: 11/18/2014] [Indexed: 11/15/2022]
Abstract
Transient receptor potential vanilloid subtype 1 (TRPV1) was originally found in sensory neurons. Recently, it has been reported that TRPV1 is expressed in salivary gland epithelial cells (SGEC). However, the physiological role of TRPV1 in salivary secretion remains to be elucidated. We found that TRPV1 is expressed in mouse and human submandibular glands (SMG) and HSG cells, originated from human submandibular gland ducts at both mRNA and protein levels. However, capsaicin (CAP), TRPV1 agonist, had little effect on intracellular free calcium concentration ([Ca2+]i) in these cells, although carbachol consistently increased [Ca2+]i. Exposure of cells to high temperature (>43℃) or acidic bath solution (pH5.4) did not increase [Ca2+]i, either. We further examined the role of TRPV1 in salivary secretion using TRPV1 knock-out mice. There was no significant difference in the pilocarpine (PILO)-induced salivary flow rate between wild-type and TRPV1 knock-out mice. Saliva flow rate also showed insignificant change in the mice treated with PILO plus CAP compared with that in mice treated with PILO alone. Taken together, our results suggest that although TRPV1 is expressed in SGEC, it appears not to play any direct roles in saliva secretion via transcellular pathway.
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Affiliation(s)
- Seulki Choi
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul 110-749, Korea
| | - Yong-Hwan Shin
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul 110-749, Korea
| | - Eun Namkoong
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul 110-749, Korea
| | - Sung-Min Hwang
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul 110-749, Korea
| | - Xin Cong
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing 100191, China
| | - Guangyan Yu
- Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing 100081, China
| | - Kyungpyo Park
- Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul 110-749, Korea
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21
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Reksten TR, Jonsson MV. Sjögren's syndrome: an update on epidemiology and current insights on pathophysiology. Oral Maxillofac Surg Clin North Am 2014; 26:1-12. [PMID: 24287189 DOI: 10.1016/j.coms.2013.09.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Primary Sjögren's syndrome (pSS) is an autoimmune chronic inflammatory disorder affecting 0.2% to 3.0% of the population, with a 9:1 female to male ratio. Features are oral and ocular dryness, local and systemic autoantibody production, and progressive focal mononuclear cell infiltration in the affected salivary and lacrimal glands. Lymphoma is the most severe complication of pSS, occurring in 4% to 5% of patients. Genetic studies identified an association with HLA and susceptibility genes in cytokine genes and genes involved in B-cell differentiation. Genetic variations may help explain why disease manifestations differ among patients and supports the hypothesis of certain distinct disease phenotypes.
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Affiliation(s)
- Tove R Reksten
- Broegelmann Research Laboratory, Department of Clinical Science, University of Bergen, The Laboratory Building, 5th Floor, Haukeland University Hospital, Bergen N-5021, Norway
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22
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Preuss B, Tunaru S, Henes J, Offermanns S, Klein R. A novel luminescence-based method for the detection of functionally active antibodies to muscarinic acetylcholine receptors of the M3 type (mAchR3) in patients' sera. Clin Exp Immunol 2014; 177:179-89. [PMID: 24628494 DOI: 10.1111/cei.12324] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2014] [Indexed: 12/11/2022] Open
Abstract
In different bioassays, functional antibodies reacting with the human muscarinic acetylcholine receptor M3(mAchR3) have been detected in sera from patients with Sjögren's syndrome (SS), and there is strong evidence that those antibodies may have pathogenetic relevance. However, depending on the method of detection, their prevalence varied. Furthermore, those bioassays are difficult to standardize. We report on the development and optimization of a novel test system based on a luminometric method to determine downstream signalling of mAchR3 which produces specific and reproducible results. Chinese hamster ovarian (CHO) cells were transfected with plasmids encoding mAchR3 and a green fluorescence protein (GFP)/aequorin fusion protein. Incubation of cells with carbachol resulted in an increase in intracellular [Ca(2+)], which was detected by measuring light emission with a luminometer, and the effect of incubation with patients' immunoglobulins (Ig) was evaluated. Optimal cell density, Ig preparation and time of incubation with patients' sera were determined. Sera from patients with primary Sjögren's syndrome (pSS; n = 40), systemic sclerosis (SSc; n = 47), myasthenia gravis (MG; n = 133) and 50 blood donors were analysed. Optimal assay conditions were obtained with a cell density of 100 000 cells/ml, isolation of Ig by ammonium sulphate precipitation and short-term incubation. Based on this highly reliable assay, 50% of the pSS patients had antibodies which inhibited carbachol-induced activation of mAchR3; none of the SSc patients, 6% of the patients with MG and 12% of the blood donors had antibodies which reacted with the mAchR3. This method facilitates the determination of functional anti-mAchR3 antibodies in patients' sera, confirmed their high prevalence in pSS patients and may, therefore, help to analyse their pathogenetic and clinical relevance in more detail.
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Affiliation(s)
- B Preuss
- Department of Internal Medicine II, University of Tuebingen, Tuebingen, Germany
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23
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Abstract
PURPOSE OF REVIEW Sjögren syndrome is a chronic autoimmune disease affecting lacrimal and salivary glands that often is accompanied by extraglandular disease manifestations. Although common in adults, the prevalence and prognosis of childhood Sjögren syndrome are unknown, in part due to lack of child-specific diagnostic and classification criteria. This review discusses difficulties in diagnosing childhood Sjögren syndrome and highlights recent findings in Sjögren syndrome treatment and pathogenesis from studies in adults and animal models over the past 18 months. RECENT FINDINGS Studies of rituximab show some therapeutic potential in adult Sjögren syndrome, whereas newer modalities including gene therapy and mesenchymal stem cell transfer are promising. The pathogenesis of Sjögren syndrome is emerging, including roles of T and B lymphocytes, autoantibodies, interferons, and glandular epithelial cells. Specific recent notable findings in Sjögren syndrome pathogenesis include identification of a type II interferon signature in salivary glands of Sjögren syndrome patients, characterization of salivary gland-infiltrating T-cell subsets, and characterization of antimuscarinic acetylcholine receptor type 3 autoantibodies. SUMMARY Childhood Sjögren syndrome is a poorly defined and underdiagnosed autoimmune disease that requires child-specific criteria in order to study disease burden and prognosis. Studies in adults and animal models continue to elucidate new potential diagnostic and therapeutic targets, which may be relevant for childhood Sjögren syndrome. VIDEO ABSTRACT http://links.lww.com/COR/A3.
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The role of M3 muscarinic acetylcholine receptor reactive T cells in Sjögren's syndrome: a critical review. J Autoimmun 2014; 51:44-50. [PMID: 24397962 DOI: 10.1016/j.jaut.2013.12.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Accepted: 12/15/2013] [Indexed: 12/13/2022]
Abstract
CD4+ T cells constitute the majority of infiltrating cells in salivary glands and lachrymal glands of patients with Sjögren's syndrome (SS). The pathophysiology of SS involves T cell recognition of antigens through the T cell antigen receptor, which triggers cytokine production and chronic inflammation. The M3 muscarinic acetylcholine receptor (M3R) molecule is expressed in exocrine glands, such as salivary glands and lachrymal glands, and plays an important role in exocrine secretion. Previous studies indicated the presence of M3R reactive T cells in peripheral blood of 40% of patients with SS and autoantibodies against M3R in sera of 9-100% of the same patients. Thus, M3R is considered a candidate receptor for autoantigen recognition by T and B cells. The relationship between B cell epitopes and the function of anti-M3R antibodies has been reported, suggesting the pathogenic role of anti-M3R antibodies in xerostomia commonly seen in SS patients. We generated new experimental mouse model, M3R-induced sialadenitis (MIS), using Rag1(-/-) mice inoculated with splenocytes from M3R(-/-) mice immunized with M3R synthetic peptides. Mice with MIS developed severe SS-like sialadenitis. Cell transfer experiments using M3R(-/-)xIFNγ(-/-) mice and M3R(-/-)xIL-17(-/-) mice showed that IFNγ and IL-17 are key cytokines in the pathogenesis of sialadenitis. These findings indicate the crucial roles of M3R-reactive Th1 and Th17 cells in autoimmune sialadenitis, and suggest that these cells, in addition to anti-M3R antibodies, are potential targets in new treatments for SS.
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25
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Korkmaz S, Zitron E, Bangert A, Seyler C, Li S, Hegedüs P, Scherer D, Li J, Fink T, Schweizer PA, Giannitsis E, Karck M, Szabó G, Katus HA, Kaya Z. Provocation of an autoimmune response to cardiac voltage-gated sodium channel NaV1.5 induces cardiac conduction defects in rats. J Am Coll Cardiol 2013; 62:340-9. [PMID: 23684688 DOI: 10.1016/j.jacc.2013.04.041] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 04/27/2013] [Accepted: 04/30/2013] [Indexed: 12/30/2022]
Abstract
OBJECTIVES This study sought to test the hypothesis that inducing an autoimmune response against the cardiac sodium channel (NaV1.5) induces arrhythmias. BACKGROUND Sporadic evidence supports the concept that autoantibodies may cause cardiac arrhythmias but substantial experimental investigations using in vivo models have been lacking to date. The NaV1.5 is essential for cardiac impulse propagation and its dysfunction has been linked to conduction disease. METHODS Rats were immunized with a peptide sequence derived from the third extracellular loop of the first domain of NaV1.5. After 28 days, we evaluated in vivo both the electrical and mechanical parameters of cardiac function. Histopathology, myocardial gene and protein expression were assessed. Whole-cell patch-clamp was used to measure sodium current (INa) density in isolated cardiomyocytes. RESULTS NaV1.5-immunized rats had high titers of autoantibodies against NaV1.5. On ECG recording, NaV1.5-immunized animals showed significantly prolonged PR-intervals. During Holter ECG-monitoring we observed repeated prolonged episodes of third-degree atrioventricular and sinoatrial block in every NaV1.5-immunized animal, but not in controls. Immunization had no effect on cardiac function. In comparison to controls, myocardial NaV1.5 mRNA and protein levels were decreased in immunized rats. INa density was reduced in cardiomyocytes incubated with sera from NaV1.5-immunized rats and from patients with idiopathic atrioventricular block (AVB) in comparison to sera from respective controls. In patients with idiopathic AVB, we observed autoantibodies against NaV1.5 that were absent in sera from healthy controls. CONCLUSIONS Provocation of an autoimmune response against NaV1.5 induces conductance defects probably caused by a reduced expression level and an inhibition of NaV1.5 by autoantibodies, resulting in decreased INa.
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Affiliation(s)
- Sevil Korkmaz
- Department of Cardiac Surgery, University of Heidelberg, Heidelberg, Germany
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26
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Ockenga W, Kühne S, Bocksberger S, Banning A, Tikkanen R. Non-neuronal functions of the m2 muscarinic acetylcholine receptor. Genes (Basel) 2013; 4:171-97. [PMID: 24705159 PMCID: PMC3899973 DOI: 10.3390/genes4020171] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 03/10/2013] [Accepted: 03/25/2013] [Indexed: 12/26/2022] Open
Abstract
Acetylcholine is an important neurotransmitter whose effects are mediated by two classes of receptors. The nicotinic acetylcholine receptors are ion channels, whereas the muscarinic receptors belong to the large family of G protein coupled seven transmembrane helix receptors. Beyond its function in neuronal systems, it has become evident that acetylcholine also plays an important role in non-neuronal cells such as epithelial and immune cells. Furthermore, many cell types in the periphery are capable of synthesizing acetylcholine and express at least some of the receptors. In this review, we summarize the non-neuronal functions of the muscarinic acetylcholine receptors, especially those of the M2 muscarinic receptor in epithelial cells. We will review the mechanisms of signaling by the M2 receptor but also the cellular trafficking and ARF6 mediated endocytosis of this receptor, which play an important role in the regulation of signaling events. In addition, we provide an overview of the M2 receptor in human pathological conditions such as autoimmune diseases and cancer.
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Affiliation(s)
- Wymke Ockenga
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
| | - Sina Kühne
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
| | - Simone Bocksberger
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
| | - Antje Banning
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
| | - Ritva Tikkanen
- Institute of Biochemistry, Medical Faculty, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany.
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27
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Sumida T, Tsuboi H, Iizuka M, Asashima H, Matsumoto I. Anti-M3 muscarinic acetylcholine receptor antibodies in patients with Sjögren's syndrome. Mod Rheumatol 2012; 23:841-5. [PMID: 23135882 DOI: 10.1007/s10165-012-0788-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 10/17/2012] [Indexed: 10/27/2022]
Abstract
Sjögren's syndrome (SS) is an autoimmune disease that affects exocrine glands including salivary and lacrimal glands. Recently, autoantibodies against muscarinic acetylcholine receptor M3 (M3R) have been detected in serum from 9 to 100 % of patients with SS in addition to anti-SS-A and anti-SS-B antibodies. These observations suggest the possibility that anti-M3R antibodies could serve as a new diagnostic test in patients with SS. Some anti-M3R antibodies are directly responsible for salivary underproduction in patients with SS. Thus, strategies designed to eliminate such pathogenic antibodies could help cure SS sufferers. In this review, we summarize the current state of knowledge of anti-M3R autoantibodies in patients with SS and the correlation between B cell epitopes and the function of anti-M3R antibodies.
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Affiliation(s)
- Takayuki Sumida
- Department of Internal Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan,
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28
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Abstract
The role of B cells in autoimmune diseases involves different cellular functions, including the well-established secretion of autoantibodies, autoantigen presentation and ensuing reciprocal interactions with T cells, secretion of inflammatory cytokines, and the generation of ectopic germinal centers. Through these mechanisms B cells are involved both in autoimmune diseases that are traditionally viewed as antibody mediated and also in autoimmune diseases that are commonly classified as T cell mediated. This new understanding of the role of B cells opened up novel therapeutic options for the treatment of autoimmune diseases. This paper includes an overview of the different functions of B cells in autoimmunity; the involvement of B cells in systemic lupus erythematosus, rheumatoid arthritis, and type 1 diabetes; and current B-cell-based therapeutic treatments. We conclude with a discussion of novel therapies aimed at the selective targeting of pathogenic B cells.
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Affiliation(s)
- Christiane S. Hampe
- Department of Medicine, University of Washington, SLU-276, 850 Republican, Seattle, WA 98109, USA
- *Christiane S. Hampe:
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