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- Gendrin, Claire, et al.
(författare)
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Mast cell chymase decreases the severity of group B Streptococcus infections
- 2018
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Ingår i: Journal of Allergy and Clinical Immunology. - : Elsevier BV. - 0091-6749 .- 1097-6825. ; 142:1, s. 120-129
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Group B Streptococcus (GBS) or Streptococcus agalactiae are β-hemolytic gram-positive bacteria that colonize the lower genital tracts of women and are frequently associated with infections during pregnancy. Innate immune defenses are critical for controlling GBS dissemination and systemic infection. Mast cells are resident sentinel cells that come into contact with pathogens early during colonization and infection.OBJECTIVE: We aimed to investigate the contribution of chymase to systemic GBS infection and rates of preterm birth.METHODS: Pharmacologic and genetic approaches using mice deficient in mast cell protease (MCPT) 4, the mouse functional homologue of human chymase, were used.RESULTS: Our studies show that mast cells release a protease with chymotrypsin-like cleavage specificity in response to GBS. Additionally, increased GBS systemic infection and preterm births were observed in MCPT4-deficient mice versus MCPT4-sufficient mice. Furthermore, we observed that proteolytic cleavage of the host extracellular matrix protein fibronectin by peritoneal cell-derived mast cell lysates diminished GBS adherence. Consistent with this observation, the increase in GBS dissemination and preterm births observed in MCPT4-deficient mice was abolished when GBS was deficient in expression of the fibronectin-binding protein SfbA.CONCLUSIONS: Taken together, our results suggest that the protective effect of MCPT4 against GBS dissemination and preterm labor can be attributed in part to MCPT4-mediated proteolysis of fibronectin. Our studies reveal a novel role of mast cells in defense against bacterial infections.
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| 4. |
- Melo, Fabio R., et al.
(författare)
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Tryptase-catalyzed core histone truncation : A novel epigenetic regulatory mechanism in mast cells
- 2017
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Ingår i: Journal of Allergy and Clinical Immunology. - : MOSBY-ELSEVIER. - 0091-6749 .- 1097-6825. ; 140:2, s. 474-485
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Tidskriftsartikel (refereegranskat)abstract
- Background: Mast cells are key effector cells in allergic reactions. When activated to degranulate, they release a plethora of bioactive compounds from their secretory granules, including mast cell-restricted proteases such as tryptase. In a previous study, we showed that tryptase, in addition to its intragranular location, can be found within the nuclei of mast cells where it truncates core histones at their N-terminal ends. Objective: Considering that the N-terminal portions of the core histones constitute sites for posttranslational modifications of major epigenetic impact, we evaluated whether histone truncation by tryptase could have an impact on epigenetic events in mast cells. Methods: Mast cells were cultured from wild-type and tryptase null mice, followed by an assessment of their profile of epigenetic histone modifications and their phenotypic characteristics. Results: We show that tryptase truncates nucleosomal histone 3 and histone 2B (H2B) and that its absence results in accumulation of the epigenetic mark, lysine 5-acetylated H2B. Intriguingly, the accumulation of lysine 5-acetylated H2B was cell age-dependent and was associated with a profound upregulation of markers of non-mast cell lineages, loss of proliferative control, chromatin remodeling as well as extensive morphological alterations. Conclusions: These findings introduce tryptase-catalyzed histone clipping as a novel epigenetic regulatory mechanism, which in the mast cell context may be crucial for maintaining cellular identity.
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| 5. |
- Shubin, Nicholas J., et al.
(författare)
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Proteome analysis of mast cell releasates reveals a role for chymase in the regulation of coagulation factor XIIIA levels via proteolytic degradation
- 2017
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Ingår i: Journal of Allergy and Clinical Immunology. - : MOSBY-ELSEVIER. - 0091-6749 .- 1097-6825. ; 139:1, s. 323-334
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Tidskriftsartikel (refereegranskat)abstract
- Background: Mast cells are significantly involved in IgE-mediated allergic reactions; however, their roles in health and disease are incompletely understood. Objective: We aimed to define the proteome contained in mast cell releasates on activation to better understand the factors secreted by mast cells that are relevant to the contribution of mast cells in diseases. Methods: Bone marrow-derived cultured mast cells (BMCMCs) and peritoneal cell-derived mast cells were used as "surrogates'' for mucosal and connective tissue mast cells, respectively, and their releasate proteomes were analyzed by mass spectrometry. Results: Our studies showed that BMCMCs and peritoneal cell-derived mast cells produced substantially different releasates following IgE-mediated activation. Moreover, we observed that the transglutaminase coagulation factor XIIIA (FXIIIA) was one of the most abundant proteins contained in the BMCMC releasates. Mast cell-deficient mice exhibited increased FXIIIA plasma and activity levels as well as reduced bleeding times, indicating that mast cells are more efficient in their ability to downregulate FXIIIA than in contributing to its amounts and functions in homeostatic conditions. We found that human chymase and mouse mast cell protease-4 (the mouse homologue of human chymase) had the ability to reduce FXIIIA levels and function via proteolytic degradation. Moreover, we found that chymase deficiency led to increased FXIIIA amounts and activity, as well as reduced bleeding times in homeostatic conditions and during sepsis. Conclusions: Our study indicates that the mast cell protease content can shape its releasate proteome. Moreover, we found that chymase plays an important role in the regulation of FXIIIA via proteolytic degradation.
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| 6. |
- Wang, Bo, et al.
(författare)
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Heparanase affects secretory granule homeostasis of murine mast cells through degrading heparin
- 2011
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Ingår i: Journal of Allergy and Clinical Immunology. - : Elsevier BV. - 0091-6749 .- 1097-6825. ; 128:6, s. 1310-1317.e8
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Tidskriftsartikel (refereegranskat)abstract
- Background: Heparanase degradation of heparan sulfate plays important roles in a number of pathological processes, including inflammation. In vitro experiments show that heparanase is capable of degrading heparin, a polysaccharide present in mast cells (MCs), in which it has a key role in promoting the storage of secretory granule compounds. Objective: We sought to investigate the functions of heparanase in MCs. Methods: Primarily cultured fetal skin-derived mast cells (FSMCs) isolated from embryos and adult peritoneal MCs were analyzed for storage and release of granule molecules in response to MC activation. Results: FSMCs from heparanase-overexpressing mice contained substantially shorter heparin chains and significantly less proteases than control cells. Conversely, FSMCs lacking heparanase contained heparin of larger size and more proteases than control cells. Correspondingly, heparanase-overexpressing adult MCs exhibited reduced release of heparin-bound proteases, a finding that could be attributed to spontaneous release of granular compounds. Heparanase was found to be upregulated in MCs on activation. Conclusion: These findings reveal a novel function of heparanase in maintaining MC homeostasis through controlled degradation of heparin present in the MC secretory granules.
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