| 1. |
- von Beek, Christopher, et al.
(författare)
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A two-step activation mechanism enables mast cells to differentiate their response between extracellular and invasive enterobacterial infection
- 2024
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Mast cells localize to mucosal tissues and contribute to innate immune defense against infection. How mast cells sense, differentiate between, and respond to bacterial pathogens remains a topic of ongoing debate. Using the prototype enteropathogen Salmonella Typhimurium (S.Tm) and other related enterobacteria, here we show that mast cells can regulate their cytokine secretion response to distinguish between extracellular and invasive bacterial infection. Tissue-invasive S.Tm and mast cells colocalize in the mouse gut during acute Salmonella infection. Toll-like Receptor 4 (TLR4) sensing of extracellular S.Tm, or pure lipopolysaccharide, causes a modest induction of cytokine transcripts and proteins, including IL-6, IL-13, and TNF. By contrast, type-III-secretion-system-1 (TTSS-1)-dependent S.Tm invasion of both mouse and human mast cells triggers rapid and potent inflammatory gene expression and >100-fold elevated cytokine secretion. The S.Tm TTSS-1 effectors SopB, SopE, and SopE2 here elicit a second activation signal, including Akt phosphorylation downstream of effector translocation, which combines with TLR activation to drive the full-blown mast cell response. Supernatants from S.Tm-infected mast cells boost macrophage survival and maturation from bone-marrow progenitors. Taken together, this study shows that mast cells can differentiate between extracellular and host-cell invasive enterobacteria via a two-step activation mechanism and tune their inflammatory output accordingly.
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| 2. |
- Magnúsdóttir, Elín Ingibjörg, et al.
(författare)
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Mouse mast cells and mast cell proteases do not play a significant role in acute tissue injury pain induced by formalin
- 2018
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Ingår i: Molecular Pain. - : SAGE Publications. - 1744-8069. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Subcutaneous formalin injections are used as a model for tissue injury-induced pain where formalin induces pain and inflammation indirectly by crosslinking proteins and directly through activation of the transient receptor potential A1 receptor on primary afferents. Activation of primary afferents leads to both central and peripheral release of neurotransmitters. Mast cells are found in close proximity to peripheral sensory nerve endings and express receptors for neurotransmitters released by the primary afferents, contributing to the neuro/immune interface. Mast cell proteases are found in large quantities within mast cell granules and are released continuously in small amounts and upon mast cell activation. They have a wide repertoire of proposed substrates, including Substance P and calcitonin gene-related peptide, but knowledge of their in vivo function is limited. We evaluated the role of mouse mast cell proteases (mMCPs) in tissue injury pain responses induced by formalin, using transgenic mice lacking either mMCP4, mMCP6, or carboxypeptidase A3 (CPA3), or mast cells in their entirety. Further, we investigated the role of mast cells in heat hypersensitivity following a nerve growth factor injection. No statistical difference was observed between the respective mast cell protease knockout lines and wild-type controls in the formalin test. Mast cell deficiency did not have an effect on formalin-induced nociceptive responses nor nerve growth factor-induced heat hypersensitivity. Our data thus show that mMCP4, mMCP6, and CPA3 as well as mast cells as a whole, do not play a significant role in the pain responses associated with acute tissue injury and inflammation in the formalin test. Our data also indicate that mast cells are not essential to heat hypersensitivity induced by nerve growth factor.
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| 3. |
- Pejler, Gunnar
(författare)
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The emerging role of mast cell proteases in asthma
- 2019
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Ingår i: European Respiratory Journal. - 0903-1936 .- 1399-3003. ; 54
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Tidskriftsartikel (refereegranskat)abstract
- It is now well established that mast cells play a crucial role in asthma. This is supported by multiple lines of evidence, including both clinical studies and studies on mast cell-deficient mice. However, there is still only limited knowledge of the exact effector mechanism(s) by which mast cells influence asthma pathology. Mast cells contain large amounts of secretory granules, which are filled with a variety of bioactive compounds including histamine, cytokines, lysosomal hydrolases, serglycin proteoglycans and a number of mast cell-restricted proteases. When mast cells are activated, e.g. in response to IgE receptor crosslinking, the contents of their granules are released to the exterior and can cause a massive inflammatory reaction. The mast cell-restricted proteases include tryptases, chymases and carboxypeptidase A3, and these are expressed and stored at remarkably high levels. There is now emerging evidence supporting a prominent role of these enzymes in the pathology of asthma. Interestingly though, the role of the mast cell-restricted proteases is multifaceted, encompassing both protective and detrimental activities. Here, I review the current knowledge of how the mast cell-restricted proteases impact on asthma.
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| 4. |
- Waern, Ida, et al.
(författare)
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PP-020-09 Protective role of mast cell chymase in house dust mite induced allergic airway inflammation
- 2010
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Ingår i: International Immunology. - : Oxford University Press (OUP). - 0953-8178 .- 1460-2377. ; 22, s. i134-
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Konferensbidrag (refereegranskat)abstract
- Mast cells release substantial amounts of active proteases, including chymase, upon activation and degranulation inresponse to e.g. IgE cross-linking. A chymase polymorphism has been associated with allergic asthma but the role of chymase in the pathogenesis is not fully understood. We recently showed that mouse mast cell protease 4 (mMCP-4) is the major chymotryptic enzyme in murine airways and that mMCP-4 can protect against bronchial hyperresponsiveness. We here assessed the role of chymase in a model of airway inflammation where mMCP-4 deficient (mMCP-4-/-) and wild type (WT) controls received repeated intranasal instillations of house dust mite (HDM). HDM-sensitization resulted in an accumulation of eosinophils and lymphocytes in the airways of both WT and mMCP-4-/- mice, but the numbers of eosinophils were approximately 5-fold higher in mMCP-4-/- mice. The airway inflammation correlated with the degree of T cell activation in draining lymph nodes. Moreover, the serum level of IgE was significantly higher in sensitized mMCP-4-/- mice than in WT mice. These results suggest a regulatory role for mMCP-4 in the early sensitization process when release of MC proteases in response to IgE cross-linking would be minimal. However, we found that HDM extract per se induced a low but significant degranulation in cultured MCs derived from both mMCP-4-/- and WT mice. Together these results suggest that MC chymase is released upon HDM exposure and that chymase has a protective role in HDM-induced airway inflammation by acting as a negative regulator of allergic sensitization.
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| 5. |
- Frisk, Jun Mei Hu, et al.
(författare)
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Mitogen-Activated Protein Kinase Signaling Regulates Proteoglycan Composition of Mast Cell Secretory Granules
- 2018
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Ingår i: Frontiers in Immunology. - : FRONTIERS MEDIA SA. - 1664-3224. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Mast cells (MCs) are characterized by an abundance of lysosome-like secretory granules filled with immunomodulatory compounds including histamine, cytokines, lysosomal hydrolases, MC-restricted proteases, and serglycin proteoglycans. The latter are essential for promoting the storage of other granule compounds and are built up of the serglycin core protein to which highly sulfated and thereby negatively charged glycosaminoglycan (GAG) side chains of heparin or chondroitin sulfate type are attached. In the search for mechanisms operating in regulating MC granule homeostasis, we here investigated the role of mitogen-activated protein kinase (MAPK) signaling. We show that inhibition of MEK1/2 (a MAPK kinase) leads to increased metachromatic staining of MC granules, indicative of increased proteoglycan content. Indeed, MEK1/2 inhibition caused a profound increase in the expression of the gene coding for the serglycin core protein and of genes coding for various enzymes involved in the biosynthesis/sulfation of the GAGs attached to the serglycin core protein. This was accompanied by corresponding increases in the levels of the respective GAGs. Deletion of the serglycin core protein abrogated the induction of enzymes operative in proteoglycan synthesis, indicating that availability of the serglycin proteoglycan core protein has a regulatory function impacting on the expression of the various serglycin-modifying enzymes. MEK1/2 inhibition also caused a substantial increase in the expression of granule-localized, proteoglycan-binding proteases. Altogether, this study identifies a novel role for MAPK signaling in regulating the content of secretory granules in MCs.
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| 6. |
- Garcia-Vilas, Javier A., et al.
(författare)
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Damnacanthal inhibits IgE receptor-mediated activation of mast cells
- 2015
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Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 65:1, s. 86-93
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Tidskriftsartikel (refereegranskat)abstract
- Damnacanthal, an anthraquinone obtained from the noni fruit (Morinda citrifolia L), has been described to possess anti-cancer and anti-inflammatory properties. Since mast cells are key players in various inflammatory conditions as well as in cancer, we considered the possibility that the biological actions of damnacanthal, at least partly, could be due to effects on mast cells. Many of the biological activities of mast cells are mediated by IgE receptor cross-linking, which results in degranulation with release of preformed granule mediators, as well as de nova synthesis and release of additional compounds. Here we show that damnacanthal has profound inhibitory activity on mast cell activation through this pathway. The release of the granule compounds beta-hexosaminidase and tryptase release was completely abrogated by damnacanthal at doses that were non-toxic to mast cells. In addition, damnacanthal inhibited activation-dependent pro-inflammatory gene induction, as well as cytokine/chemokine release in response to mast cell stimulation. The mechanism underlying damnacanthal inhibition was linked to impaired phosphorylation of Syk and Akt. Furthermore, damnacanthal inhibited mast cell activation in response to calcium ionophore A23187. Altogether, the data presented here demonstrate that damnacanthal inhibits mast cell activation induced by different stimuli and open a new window for the use of this compound as a mast cell stabilizer.
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| 7. |
- Rönnberg, Elin, et al.
(författare)
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Granzyme H Is a Novel Protease Expressed by Human Mast Cells
- 2014
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Ingår i: International Archives of Allergy and Immunology. - : S. Karger AG. - 1018-2438 .- 1423-0097. ; 165:1, s. 68-74
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Tidskriftsartikel (refereegranskat)abstract
- Background: Many of the functions attributed to mast cells depend on the various pro-inflammatory mediators that are secreted upon mast cell activation. These include a panel of mast cell-specific proteases. In addition, recent studies have indicated that murine mast cells also express granzyme D, a protease previously thought to be confined to cytotoxic lymphocytes. Here, we address the human relevance of the latter findings by investigating whether human mast cells express granzyme H, the granzyme that may represent the functional counterpart to murine granzyme D. Methods: Cord blood-derived mast cells, LAD2 cells and skin mast cells in situ were evaluated for their expression of granzymes using quantitative PCR, Western blot analysis and immunostaining. Mast cells were activated by either calcium ionophore stimulation or IgE receptor cross-linking. Results: Cord blood-derived mast cells and LAD2 cells were shown to express granzyme H and B mRNA, while granzyme A, K and M expression was undetectable. Mast cell activation by either calcium ionophore or IgE receptor cross-linking caused down-regulated expression of granzyme H. In contrast, granzyme B expression was up-regulated by the same stimuli. Granzyme H expression was also confirmed at the protein level, as shown by both Western blot analysis and confocal microscopy. Further, we show that granzyme H is expressed by human skin mast cells in situ. Conclusions: The present findings implicate granzyme H as a novel protease expressed by human mast cells and support earlier findings obtained in natural killer cells suggesting that granzymes B and H are reciprocally regulated.
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| 8. |
- Garcia-Faroldi, Gianni, et al.
(författare)
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Inhibition of the BET family of epigenetic reader proteins : A novel principle for modulating gene expression in IgE-activated mast cells
- 2017
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Ingår i: Immunity, Inflammation and Disease. - : Wiley. - 2050-4527. ; 5:2, s. 141-150
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The BET family of bromodomain-containing proteins constitute epigenetic readers that bind to acetylated lysine residues of core histones, thereby translating epigenetic histone marks to effects on gene expression. BET inhibitors are currently emerging as promising therapeutic agents for treatment of various pathological conditions. Here, we explored the potential of using BET inhibition to modulate IgE-mediated responses in mast cells.Methods: We assessed the effects of BET inhibitors PFI-1, I-BET151, and I-BET762 on responses downstream of mast cell activation through IgE receptor cross-linking.Results: BET inhibitors were neither toxic for mast cells (at doses up to 20M), nor did they prevent IgE-mediated mast cell degranulation. However, we found that BET inhibition, in particular by I-BET151, suppressed IL-6 gene expression and IL-6 protein release in response to IgE-mediated mast cell activation. This was observed in both bone marrow-derived mast cells (BMMCs) and in mature peritoneal-cell derived mast cells. Further analysis showed that BET inhibition also suppressed the expression of a number of additional genes of those that were upregulated by IgE receptor cross-linking, including IL-3, IL-7R, CCR1, and ADAMTS9. However, BET inhibition was selective, i.e., several genes that were upregulated by IgE receptor cross-linking were not affected by BET inhibitors.Conclusions: These findings suggest that BET inhibition can interfere with the upregulated expression of selected genes in mast cells activated by IgE receptor cross-linking. Further, our findings introduce the concept of utilizing epigenetic mechanisms for modulating mast cell function in the context of IgE-driven disease.
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| 9. |
- Alanazi, Sultan, et al.
(författare)
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Tryptase Regulates the Epigenetic Modification of Core Histones in Mast Cell Leukemia Cells
- 2021
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Ingår i: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Mast cells are immune cells that store large amounts of mast cell-restricted proteases in their secretory granules, including tryptase, chymase, and carboxypeptidase A3. In mouse mast cells, it has been shown that tryptase, in addition to its canonical location in secretory granules, can be found in the nuclear compartment where it can impact core histones. Here we asked whether tryptase can execute core histone processing in human mast cell leukemia cells and whether tryptase thereby can affect the epigenetic modification of core histones. Our findings reveal that triggering of cell death in HMC-1 mast cell leukemia cells is associated with extensive cleavage of core histone 3 (H3) and more restricted cleavage of H2B. Tryptase inhibition caused a complete blockade of such processing. Our data also show that HMC-1 cell death was associated with a major reduction of several epigenetic histone marks, including H3 lysine-4-mono-methylation (H3K4me1), H3K9me2, H3 serine-10-phosphorylation (H3S10p), and H2B lysine-16-acetylation (H2BK16ac), and that tryptase inhibition reverses the effect of cell death on these epigenetic marks. Further, we show that tryptase is present in the nucleus of both viable and dying mast cell leukemia cells. In line with a role for tryptase in regulating nuclear events, tryptase inhibition caused an increased proliferation of the mast cell leukemia cells. Altogether, the present study emphasizes a novel principle for how epigenetic modification of core histones is regulated and provides novel insight into the biological function of human mast cell tryptase.
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| 10. |
- Alim, Abdul, 1983-
(författare)
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Mechanisms in Tendon Healing : Pain, Biomarkers and the Role of Mast Cells
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tendon injuries and tendinopathy are common disorders, but the underlying mechanisms are not well understood. The overall aim of this thesis was to better understand the mechanisms underlying tendon healing, pain, and inflammation.The aim of the first study was to assess biomarkers of tendon healing, including procollagen type I (PINP) and type III (PIIINP) in relation to patient outcome in 65 patients with Achilles tendon rupture (ATR). At two weeks post-ATR, PINP and PIIINP-levels were quantified using microdialysis followed by ELISA. At one-year post-ATR patient outcome was assessed using the validated Achilles tendon Total Rupture Score. We found that higher ratio of PINP and PIIINP to total protein were significantly associated with less pain but more fatigue in the affected limb.In the second study, we applied Intermittent Pneumatic Compression (IPC) therapy for two weeks to stimulate tendon healing. The patients received either adjuvant IPC treatment or treatment-as-usual in a plaster cast without IPC. We observed that IPC therapy significantly increased PINP levels in the injured tendon, suggesting enhanced healing response.In our third study, we investigated healing response and the role of mast cells (MCs) in-vivo using an ATR rat model. Three weeks postoperatively, we demonstrated an increased number of MCs and a higher proportion of degranulated MCs in the injured tendon compared to the control. We further established that MCs in the injured tendon were positive for the glutamate receptor NMDAR1.In our final study, we assessed the effect of glutamate stimulation on in-vitro-derived mouse bone marrow MCs. Mast cell degranulation was quantified through β-hexosaminidase release, immunofluorescence was used to quantify NMDARs at the protein level, and RT-qPCR/microarray was used to study the expression of NMDARs and associated genes. Glutamate induced a robust upregulation of glutamate receptors of both ionotropic and metabotropic type, both at the mRNA and at protein level. NMDAR1 co-localized with glutamate in the membrane of MCs, thereby confirming an interaction between glutamate and its receptor. Glutamate also induced expression of pro-inflammatory compounds such as IL-6 and CCL2 and transcription factors such as Egr2, Egr3 and FosB. Moreover, the NMDA-channel blocker MK-801 completely abrogated the response of MCs to glutamate, supporting a functional glutamate–glutamate receptor axis in MCs.Together, findings presented in this dissertation reveal possible mechanisms of tendon healing in relation to pain and function, and establish a novel principle for how immune cells can communicate with nerve cells after ATR.
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