| 1. |
- Dahlin, Joakim S., et al.
(author)
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The ingenious mast cell : Contemporary insights into mast cell behavior and function
- 2022
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In: Allergy. European Journal of Allergy and Clinical Immunology. - : John Wiley & Sons. - 0105-4538 .- 1398-9995. ; 77:1, s. 83-99
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Research review (peer-reviewed)abstract
- Mast cells are (in)famous for their role in allergic diseases, but the physiological and pathophysiological roles of this ingenious cell are still not fully understood. Mast cells are important for homeostasis and surveillance of the human system, recognizing both endogenous and exogenous agents, which induce release of a variety of mediators acting on both immune and non-immune cells, including nerve cells, fibroblasts, endothelial cells, smooth muscle cells, and epithelial cells. During recent years, clinical and experimental studies on human mast cells, as well as experiments using animal models, have resulted in many discoveries that help decipher the function of mast cells in health and disease. In this review, we focus particularly on new insights into mast cell biology, with a focus on mast cell development, recruitment, heterogeneity, and reactivity. We also highlight the development in our understanding of mast cell-driven diseases and discuss the development of novel strategies to treat such conditions.
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| 2. |
- Doncheva, Atanaska, I, et al.
(author)
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Serglycin Is Involved in Adipose Tissue Inflammation in Obesity
- 2022
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In: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 208:1, s. 121-132
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Journal article (peer-reviewed)abstract
- Chronic local inflammation of adipose tissue is an important feature of obesity. Serglycin is a proteoglycan highly expressed by various immune cell types known to infiltrate adipose tissue under obese conditions. To investigate if serglycin expression has an impact on diet-induced adipose tissue inflammation, we subjected Srgn(+/+) and Srgn(-/-) mice (C57BL/6J genetic background) to an 8-wk high-fat and high-sucrose diet. The total body weight was the same in Srgn(+/+) and Srgn(-/-) mice after diet treatment. Expression of white adipose tissue genes linked to inflammatory pathways were lower in Srgn(-/)- mice. We also noted reduced total macrophage abundance, a reduced proportion of proinflammatory M1 macrophages, and reduced formation of crown-like structures in adipose tissue of Srgn(-/-) compared with Srgn(+/+) mice. Further, Srgn(-/-) mice had more medium-sized adipocytes and fewer large adipocytes. Differentiation of preadipocytes into adipocytes (3T3-L1) was accompanied by reduced Srgn mRNA expression. In line with this, analysis of single-cell RNA sequencing data from mouse and human adipose tissue supports that Srgn mRNA is predominantly expressed by various immune cells, with low expression in adipocytes. Srgn mRNA expression was higher in obese compared with lean humans and mice, accompanied by an increased expression of immune cell gene markers. SRGN and inflammatory marker mRNA expression was reduced upon substantial weight loss in patients after bariatric surgery. Taken together, this study introduces a role for serglycin in the regulation of obesity-induced adipose inflammation.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- Liu, Jielu, et al.
(author)
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Monensin inhibits mast cell mediated airway contractions in human and guinea pig asthma models
- 2022
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In: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12
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Journal article (peer-reviewed)abstract
- Asthma is a common respiratory disease associated with airway hyperresponsiveness (AHR), airway inflammation and mast cell (MC) accumulation in the lung. Monensin, an ionophoric antibiotic, has been shown to induce apoptosis of human MCs. The aim of this study was to define the effect of monensin on MC responses, e.g., antigen induced bronchoconstriction, and on asthmatic features in models of allergic asthma. Tracheal segments from house dust mite (HDM) extract sensitized guinea pigs were isolated and exposed to monensin, followed by histological staining to quantify MCs. Both guinea pig tracheal and human bronchi were used for pharmacological studies in tissue bath systems to investigate the monensin effect on tissue viability and antigen induced bronchoconstriction. Further, an HDM-induced guinea pig asthma model was utilized to investigate the effect of monensin on AHR and airway inflammation. Monensin decreased MC number, caused MC death, and blocked the HDM or anti-IgE induced bronchoconstriction in guinea pig and human airways. In the guinea pig asthma model, HDM-induced AHR, airway inflammation and MC hyperplasia could be inhibited by repeated administration of monensin. This study indicates that monensin is an effective tool to reduce MC number and MCs are crucial for the development of asthma-like features.
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| 7. |
- Meen, Astri J., et al.
(author)
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Obesity Is Associated with Distorted Proteoglycan Expression in Adipose Tissue
- 2023
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In: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 24:8
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Journal article (peer-reviewed)abstract
- Proteoglycans are central components of the extracellular matrix (ECM) and binding partners for inflammatory chemokines. Morphological differences in the ECM and increased inflammation are prominent features of the white adipose tissues in patients with obesity. The impact of obesity and weight loss on the expression of specific proteoglycans in adipose tissue is not well known. This study aimed to investigate the relationship between adiposity and proteoglycan expression. We analyzed transcriptomic data from two human bariatric surgery cohorts. In addition, RT-qPCR was performed on adipose tissues from female and male mice fed a high-fat diet. Both visceral and subcutaneous adipose tissue depots were analyzed. Adipose mRNA expression of specific proteoglycans, proteoglycan biosynthetic enzymes, proteoglycan partner molecules, and other ECM-related proteins were altered in both human cohorts. We consistently observed more profound alterations in gene expression of ECM targets in the visceral adipose tissues after surgery (among others VCAN (p = 0.000309), OGN (p = 0.000976), GPC4 (p = 0.00525), COL1A1 (p = 0.00221)). Further, gene analyses in mice revealed sex differences in these two tissue compartments in obese mice. We suggest that adipose tissue repair is still in progress long after surgery, which may reflect challenges in remodeling increased adipose tissues. This study can provide the basis for more mechanistic studies on the role of proteoglycans in adipose tissues in obesity.
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| 8. |
- Põlajeva, Jelena, et al.
(author)
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Glioma-derived macrophage migration inhibitory factor (MIF) promotes mast cell recruitment in a STAT5-dependent manner
- 2014
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In: Molecular Oncology. - : Wiley. - 1574-7891 .- 1878-0261. ; 8:1, s. 50-58
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Journal article (peer-reviewed)abstract
- Recently, glioma research has increased its focus on the diverse types of cells present in brain tumors. We observed previously that gliomas are associated with a profound accumulation of mast cells (MCs) and here we investigate the underlying mechanism. Gliomas express a plethora of chemoattractants. First, we demonstrated pronounced migration of human MCs toward conditioned medium from cultures of glioma cell lines. Subsequent cytokine array analyses of media from cells, cultured in either serum-containing or -free conditions, revealed a number of candidates which were secreted in high amounts in both cell lines. Among these, we then focused on macrophage migration inhibitory factor (MIF), which has been reported to be pro-inflammatory and -tumorigenic. Infiltration of MCs was attenuated by antibodies that neutralized MIF. Moreover, a positive correlation between the number of MCs and the level of MIF in a large cohort of human glioma tissue samples was observed. Further, both glioma-conditioned media and purified MIF promoted differential phosphorylation of a number of signaling molecules, including signal transducer and activator of transcription 5 (STAT5), in MCs. Inhibition of pSTAT5 signaling significantly attenuated the migration of MCs toward glioma cell-conditioned medium shown to contain MIF. In addition, analysis of tissue microarrays (TMAs) of high-grade gliomas revealed a direct correlation between the level of pSTAT5 in MCs and the level of MIF in the medium. In conclusion, these findings indicate the important influence of signaling cascades involving MIF and STAT5 on the recruitment of MCs to gliomas.
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| 9. |
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| 10. |
- Ackermann, Paul W., et al.
(author)
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Tendon pain : what are the mechanisms behind it?
- 2023
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In: Scandinavian Journal of Pain. - : Walter de Gruyter. - 1877-8860 .- 1877-8879. ; 23:1, s. 14-24
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Research review (peer-reviewed)abstract
- ObjectivesManagement of chronic tendon pain is difficult and controversial. This is due to poor knowledge of the underlying pathophysiology of chronic tendon pain, priorly known as tendinitis but now termed tendinopathy. The objective of this topical review was to synthesize evolving information of mechanisms in tendon pain, using a comprehensive search of the available literature on this topic.ContentThis review found no correlations between tendon degeneration, collagen separation or neovascularization and chronic tendon pain. The synthesis demonstrated that chronic tendon pain, however, is characterized by excessive nerve sprouting with ingrowth in the tendon proper, which corresponds to alterations oberserved also in other connective tissues of chronic pain conditions. Healthy, painfree tendons are devoid of nerve fibers in the tendon proper, while innervation is confined to tendon surrounding structures, such as sheaths. Chronic painful tendons exhibit elevated amounts of pain neuromediators, such as glutamate and substance p as well as up-regulated expression and excitability of pain receptors, such as the glutamate receptor NMDAR1 and the SP receptor NK1, found on ingrown nerves and immune cells. Increasing evidence indicates that mast cells serve as an important link between the peripheral nervous system and the immune systems resulting in so called neurogenic inflammation.SummaryChronic painful tendons exhibit (1) protracted ingrowth of sensory nerves (2) elevated pain mediator levels and (3) up-regulated expression and excitability of pain receptors, participating in (4) neuro-immune pathways involved in pain regulation. Current treatments that entail the highest scientific evidence to mitigate chronic tendon pain include eccentric exercises and extracorporeal shockwave, which both target peripheral neoinnervation aiming at nerve regeneration.OutlookPotential mechanism-based pharmacological treatment approaches could be developed by blocking promotors of nerve ingrowth, such as NGF, and promoting inhibitors of nerve ingrowth, like semaphorins, as well as blocking glutamate-NMDA-receptor pathways, which are prominent in chronic tendon pain.
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| 11. |
- Akula, Srinivas, et al.
(author)
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How Relevant Are Bone Marrow-Derived Mast Cells (BMMCs) as Models for Tissue Mast Cells? : A Comparative Transcriptome Analysis of BMMCs and Peritoneal Mast Cells
- 2020
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In: Cells. - : MDPI. - 2073-4409. ; 9:9
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Journal article (peer-reviewed)abstract
- Bone marrow-derived mast cells (BMMCs) are often used as a model system for studies of the role of MCs in health and disease. These cells are relatively easy to obtain from total bone marrow cells by culturing under the influence of IL-3 or stem cell factor (SCF). After 3 to 4 weeks in culture, a nearly homogenous cell population of toluidine blue-positive cells are often obtained. However, the question is how relevant equivalents these cells are to normal tissue MCs. By comparing the total transcriptome of purified peritoneal MCs with BMMCs, here we obtained a comparative view of these cells. We found several important transcripts that were expressed at very high levels in peritoneal MCs, but were almost totally absent from the BMMCs, including the major chymotryptic granule protease Mcpt4, the neurotrophin receptor Gfra2, the substance P receptor Mrgprb2, the metalloprotease Adamts9 and the complement factor 2 (C2). In addition, there were a number of other molecules that were expressed at much higher levels in peritoneal MCs than in BMMCs, including the transcription factors Myb and Meis2, the MilR1 (Allergin), Hdc (Histidine decarboxylase), Tarm1 and the IL-3 receptor alpha chain. We also found many transcripts that were highly expressed in BMMCs but were absent or expressed at low levels in the peritoneal MCs. However, there were also numerous MC-related transcripts that were expressed at similar levels in the two populations of cells, but almost absent in peritoneal macrophages and B cells. These results reveal that the transcriptome of BMMCs shows many similarities, but also many differences to that of tissue MCs. BMMCs can thereby serve as suitable models in many settings concerning the biology of MCs, but our findings also emphasize that great care should be taken when extrapolating findings from BMMCs to the in vivo function of tissue-resident MCs.
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| 12. |
- Akula, Srinivas, et al.
(author)
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Quantitative In-Depth Analysis of the Mouse Mast Cell Transcriptome Reveals Organ-Specific Mast Cell Heterogeneity
- 2020
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In: CELLS. - : MDPI. - 2073-4409. ; 9:1
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Journal article (peer-reviewed)abstract
- Mast cells (MCs) are primarily resident hematopoietic tissue cells that are localized at external and internal surfaces of the body where they act in the first line of defense. MCs are found in all studied vertebrates and have also been identified in tunicates, an early chordate. To obtain a detailed insight into the biology of MCs, here we analyzed the transcriptome of MCs from different mouse organs by RNA-seq and PCR-based transcriptomics. We show that MCs at different tissue locations differ substantially in their levels of transcripts coding for the most abundant MC granule proteins, even within the connective tissue type, or mucosal MC niches. We also demonstrate that transcript levels for the major granule proteins, including the various MC-restricted proteases and the heparin core protein, can be several orders of magnitude higher than those coding for various surface receptors and enzymes involved in protease activation, as well as enzymes involved in the synthesis of heparin, histamine, leukotrienes, and prostaglandins. Interestingly, our analyses revealed an almost complete absence in MCs of transcripts coding for cytokines at baseline conditions, indicating that cytokines are primarily produced by activated MCs. Bone marrow-derived MCs (BMMCs) are often used as equivalents of tissue MCs. Here, we show that these cells differ substantially from tissue MCs with regard to their transcriptome. Notably, they showed a transcriptome indicative of relatively immature cells, both with respect to the expression of granule proteases and of various enzymes involved in the processing/synthesis of granule compounds, indicating that care should be taken when extrapolating findings from BMMCs to the in vivo function of tissue-resident MCs. Furthermore, the latter finding indicates that the development of fully mature tissue-resident MCs requires a cytokine milieu beyond what is needed for in vitro differentiation of BMMCs. Altogether, this study provides a comprehensive quantitative view of the transcriptome profile of MCs resident at different tissue locations that builds nicely on previous studies of both the mouse and human transcriptome, and form a solid base for future evolutionary studies of the role of MCs in vertebrate immunity.
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| 13. |
- Alanazi, Sultan, et al.
(author)
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Histone Methyltransferase Inhibition Has a Cytotoxic Impact on Transformed Mast Cells : Implications for Mastocytosis
- 2020
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In: Anticancer Research. - : INT INST ANTICANCER RESEARCH. - 0250-7005 .- 1791-7530. ; 40:5, s. 2525-2536
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Journal article (peer-reviewed)abstract
- Background/Aim: Mast cell transformation, as manifested in mastocytosis, can be a serious condition for which there are limited therapeutic options. Mastocytosis cells can be sensitive to histone deacetylase (HDAC) inhibitors, but their sensitivity to other histone-modifying enzymes has not been assessed. Here we addressed this issue.Materials and Methods: Inhibitors of histone methyl transferases, histone demethylases, histone acetyl transferases and HDACs were tested for their effects on growth, viability, caspase-3 activation and annexin V/DRAQ7 staining in transformed mast cells.Results: Transformed mast cells underwent cell death in response to histone methyl transferase and HDAC inhibition, but were not sensitive to histone demethylase or histone acetyl transferase inhibition. Histone methyl transferase inhibition led to cell death with characteristics of apoptosis, as judged by caspase-3 activation. However, DNA fragmentation was not apparent and Annexin V+/DRAQ7(-) cells were not predominant, suggesting a type of cell death differing from classical apoptosis.Conclusion: Histone methyl transferase inhibition could be developed as a novel regimen for targeting mastocytosis.
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| 14. |
- Alanazi, Sultan, et al.
(author)
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Mast Cell β-Tryptase Is Enzymatically Stabilized by DNA
- 2020
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In: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 21:14
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Journal article (peer-reviewed)abstract
- Tryptase is a tetrameric serine protease located within the secretory granules of mast cells. In the secretory granules, tryptase is stored in complex with negatively charged heparin proteoglycans and it is known that heparin is essential for stabilizing the enzymatic activity of tryptase. However, recent findings suggest that enzymatically active tryptase also can be found in the nucleus of murine mast cells, but it is not known how the enzmatic activity of tryptase is maintained in the nuclear milieu. Here we hypothesized that tryptase, as well as being stabilized by heparin, can be stabilized by DNA, the rationale being that the anionic charge of DNA could potentially substitute for that of heparin to execute this function. Indeed, we showed that double-stranded DNA preserved the enzymatic activity of human β-tryptase with a similar efficiency as heparin. In contrast, single-stranded DNA did not have this capacity. We also demonstrated that DNA fragments down to 400 base pairs have tryptase-stabilizing effects equal to that of intact DNA. Further, we showed that DNA-stabilized tryptase was more efficient in degrading nuclear core histones than heparin-stabilized enzyme. Finally, we demonstrated that tryptase, similar to its nuclear localization in murine mast cells, is found within the nucleus of primary human skin mast cells. Altogether, these finding reveal a hitherto unknown mechanism for the stabilization of mast cell tryptase, and these findings can have an important impact on our understanding of how tryptase regulates nuclear events.
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| 15. |
- Alanazi, Sultan
(author)
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The Impact of Tryptase and Epigenetic Mechanisms on Mast Cells
- 2022
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Doctoral thesis (other academic/artistic)abstract
- Mast cells have a large influence on multiple immune-mediated responses, including allergic conditions, and they have been implicated in various diseases such as arthritis and cancer. Mastocytosis is characterized by abnormal mast cell proliferation induced by mutations in KIT, the stem cell factor (SCF) receptor. Mast cell leukemia is the most aggressive form of systemic mastocytosis, with no curative treatment options. Therefore, a therapy or study that help finding a cure for this disease is urgently needed.In paper I, we studied the effect of histone modification inhibition on mast cells. Our findings showed for the first time that mast cell leukemia cells are highly sensitive to histone methyltransferase inhibition. In paper II, we further investigated mast cell function, examining whether DNA can substitute heparin in stabilizing tryptase enzymatic activity. The mechanism by which tryptase retains its enzymatic activity in the nuclear environment is unknown. Our study demonstrated that double-stranded DNA maintained the enzymatic activity of human β-tryptase and identified that tryptase is located within the nucleus of primary human skin mast cells. The interaction of tryptase with DNA is further investigated in paper III, with the aim of determining whether tryptase can affect the formation of neutrophil extracellular traps (NETs). This study showed for the first time that tryptase of mast cells binds to DNA and it has a significant potentiating effect on the formation of NETs in reaction to neutrophil triggering stimuli. Furthermore, the study showed that DNA-stabilized tryptase has a high capacity for proteolytic modification of a variety of cytokines, implying a regulatory role for NET-bound tryptase in inflammatory processes. Finally, in paper IV, we examined the effect of mast cell apoptosis on histone processing, and the extent to which these processes are reliant on tryptase. The findings demonstrated that using a granule-mediated approach to induce mast cell death resulted in substantial processing of core histones. Additionally, they showed that tryptase is highly required for the processing and that tryptase regulates the amplitude of epigenetic core histone modifications during the process of cell death.Taken together, the findings provide a basis for investigating histone modification inhibition as a potential therapeutic strategy for the disease. Furthermore, they reveal a previously unknown way of mediating mast cell tryptase stabilization and indicate that tryptase plays a role in the regulation of mast cell death, having the potential to influence our experience and understanding of how tryptase affects nuclear processes.
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| 16. |
- Alanazi, Sultan, et al.
(author)
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Tryptase Regulates the Epigenetic Modification of Core Histones in Mast Cell Leukemia Cells
- 2021
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In: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 12
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Journal article (peer-reviewed)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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| 17. |
- Alim, Abdul, 1983-, et al.
(author)
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Do Mast Cells Have a Role in Tendon Healing and Inflammation?
- 2020
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In: Cells. - : MDPI AG. - 2073-4409. ; 9:5
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Research review (peer-reviewed)abstract
- Understanding the links between the tendon healing process, inflammatory mechanisms, and tendon homeostasis/pain after tissue damage is crucial in developing novel therapeutics for human tendon disorders. The inflammatory mechanisms that are operative in response to tendon injury are not fully understood, but it has been suggested that inflammation occurring in response to nerve signaling, i.e., neurogenic inflammation, has a pathogenic role. The mechanisms driving such neurogenic inflammation are presently not clear. However, it has recently been demonstrated that mast cells present within the injured tendon can express glutamate receptors, raising the possibility that mast cells may be sensitive to glutamate signaling and thereby modulate neurogenic inflammation following tissue injury. In this review, we discuss the role of mast cells in the communication with peripheral nerves, and their emerging role in tendon healing and inflammation after injury.
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| 18. |
- Alim, Abdul, 1983-, et al.
(author)
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Glutamate triggers the expression of functional ionotropic and metabotropic glutamate receptors in mast cells
- 2021
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In: Cellular & Molecular Immunology. - : Springer Nature. - 1672-7681 .- 2042-0226. ; 18:10, s. 2383-2392
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Journal article (peer-reviewed)abstract
- Mast cells are emerging as players in the communication between peripheral nerve endings and cells of the immune system. However, it is not clear the mechanism by which mast cells communicate with peripheral nerves. We previously found that mast cells located within healing tendons can express glutamate receptors, raising the possibility that mast cells may be sensitive to glutamate signaling. To evaluate this hypothesis, we stimulated primary mast cells with glutamate and showed that glutamate induced the profound upregulation of a panel of glutamate receptors of both the ionotropic type (NMDAR1, NMDAR2A, and NMDAR2B) and the metabotropic type (mGluR2 and mGluR7) at both the mRNA and protein levels. The binding of glutamate to glutamate receptors on the mast cell surface was confirmed. Further, glutamate had extensive effects on gene expression in the mast cells, including the upregulation of pro-inflammatory components such as IL-6 and CCL2. Glutamate also induced the upregulation of transcription factors, including Egr2, Egr3 and, in particular, FosB. The extensive induction of FosB was confirmed by immunofluorescence assessment. Glutamate receptor antagonists abrogated the responses of the mast cells to glutamate, supporting the supposition of a functional glutamate-glutamate receptor axis in mast cells. Finally, we provide in vivo evidence supporting a functional glutamate-glutamate receptor axis in the mast cells of injured tendons. Together, these findings establish glutamate as an effector of mast cell function, thereby introducing a novel principle for how cells in the immune system can communicate with nerve cells.
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| 19. |
- Alim, Abdul, 1983-
(author)
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Mechanisms in Tendon Healing : Pain, Biomarkers and the Role of Mast Cells
- 2019
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Doctoral thesis (other academic/artistic)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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| 20. |
- Alim, Md Abdul, et al.
(author)
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Increased mast cell degranulation and co-localization of mast cells with the NMDA receptor-1 during healing after Achilles tendon rupture
- 2017
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In: Cell and Tissue Research. - Berlin Heidelberg : Springer Science and Business Media LLC. - 0302-766X .- 1432-0878. ; 370:3, s. 451-460
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Journal article (peer-reviewed)abstract
- The role of inflammation and the mechanism of tendon healing after rupture has historically been a matter of controversy. The purpose of the present study is to investigate the role of mast cells and their relation to the NMDA receptor-1 (a glutamate receptor) during healing after Achilles tendon rupture. Eight female Sprague Dawley rats had their right Achilles tendon transected. Three weeks after rupture, histological quantification of mast cell numbers and their state of degranulation was assessed by histochemistry. Co-localization of mast cell tryptase (a mast cell marker) and NMDA receptor-1 was determined by immunofluorescence. The intact left Achilles tendon was used as control. An increased number of mast cells and a higher proportion of degranulated mast cells were found in the healing Achilles tendon compared to the intact. In addition, increased co-localization of mast cell tryptase and NMDA receptor-1 was seen in the areas of myotendinous junction, mid-tendon proper and bone tendon junction of the healing versus the intact tendon. These findings introduce a possible role for mast cells in the healing phase after Achilles tendon rupture.
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| 21. |
- Allam, Venkata, et al.
(author)
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Nafamostat has anti-asthmatic effects associated with suppressed pro-inflammatory gene expression, eosinophil infiltration and airway hyperreactivity
- 2023
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In: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 14
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Journal article (peer-reviewed)abstract
- IntroductionAsthma is characterized by an imbalance between proteases and their inhibitors. Hence, an attractive therapeutic option could be to interfere with asthma-associated proteases. Here we exploited this option by assessing the impact of nafamostat, a serine protease inhibitor known to neutralize mast cell tryptase. MethodsNafamostat was administered in a mouse model for asthma based on sensitization by house dust mite (HDM) extract, followed by the assessment of effects on airway hyperreactivity, inflammatory parameters and gene expression. ResultsWe show that nafamostat efficiently suppressed the airway hyperreactivity in HDM-sensitized mice. This was accompanied by reduced infiltration of eosinophils and lymphocytes to the airways, and by lower levels of pro-inflammatory compounds within the airway lumen. Further, nafamostat had a dampening impact on goblet cell hyperplasia and smooth muscle layer thickening in the lungs of HDM-sensitized animals. To obtain deeper insight into the underlying mechanisms, a transcriptomic analysis was conducted. This revealed, as expected, that the HDM sensitization caused an upregulated expression of numerous pro-inflammatory genes. Further, the transcriptomic analysis showed that nafamostat suppressed the levels of multiple pro-inflammatory genes, with a particular impact on genes related to asthma. DiscussionTaken together, this study provides extensive insight into the ameliorating effect of nafamostat on experimental asthma, and our findings can thereby provide a basis for the further evaluation of nafamostat as a potential therapeutic agent in human asthma.
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| 22. |
- Allam, Venkata, et al.
(author)
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Treatment of chronic airway diseases using nutraceuticals : Mechanistic insight
- 2022
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In: Critical reviews in food science and nutrition. - : Taylor & Francis. - 1040-8398 .- 1549-7852. ; 62:27, s. 7576-7590
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Research review (peer-reviewed)abstract
- Respiratory diseases, both acute and chronic, are reported to be the leading cause of morbidity and mortality, affecting millions of people globally, leading to high socio-economic burden for the society in the recent decades. Chronic inflammation and decline in lung function are the common symptoms of respiratory diseases. The current treatment strategies revolve around using appropriate anti-inflammatory agents and bronchodilators. A range of anti-inflammatory agents and bronchodilators are currently available in the market; however, the usage of such medications is limited due to the potential for various adverse effects. To cope with this issue, researchers have been exploring various novel, alternative therapeutic strategies that are safe and effective to treat respiratory diseases. Several studies have been reported on the possible links between food and food-derived products in combating various chronic inflammatory diseases. Nutraceuticals are examples of such food-derived products which are gaining much interest in terms of its usage for the well-being and better human health. As a consequence, intensive research is currently aimed at identifying novel nutraceuticals, and there is an emerging notion that nutraceuticals can have a positive impact in various respiratory diseases. In this review, we discuss the efficacy of nutraceuticals in altering the various cellular and molecular mechanisms involved in mitigating the symptoms of respiratory diseases.
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| 23. |
- Andersson, Mattias K., 1978-
(author)
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Cleavage Specificity of Mast Cell Chymases
- 2008
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Doctoral thesis (other academic/artistic)abstract
- Mast cells (MC) are potent inflammatory cells that are known primarily for their prominent role in IgE mediated allergies. However, they also provide beneficial functions to the host, e.g. in bacterial and parasitic defence. MCs react rapidly upon stimulation by releasing potent granule-stored mediators, and serine proteases of the chymase or tryptase families are such major granule constituents. As a first step towards a better understanding of the biological function of these proteases, we have determined the extended cleavage specificities of four mammalian mast cell chymases, by utilizing a substrate phage display approach. The specificities of these enzymes have then been used to compare their functional characteristics.The major mucosal MC chymase in mice, mMCP-1, was found to possess a strict preference in four amino acid positions of the peptide substrate. Using this sequence to search the mouse proteome for potential in vivo substrates led to the identification of several very interesting potential novel substrates. Some of them may explain the increased epithelial permeability provided by this enzyme.Human MCs, express only one single α-chymase, and the rodent α-chymases have secondarily gained elastase-like primary cleavage specificity. However, rodents express additional chymases, the β-chymases, and rodent β-chymases may have adopted the function of the α-chymases. The cleavage specificities of the human chymase and two rodent β-chymases were therefore determined (rat rMCP-1 and mouse mMCP-4). N-terminal of the cleaved bond the three chymases showed similar preferences, but C-terminal the human chymase and mMCP-4 shared a high preference for acidic amino acids in the P2´ position and therefore seem to be functional homologues. The molecular interactions mediating the preference for acidic amino acids in position P2´ were further investigated. By site-directed mutagenesis of the human chymase, amino acids Arg143 and Lys192 were concluded to synergistically mediate this preference.Our data show that chymases, of different MC subpopulations, display quite different extended cleavage specificities. However mouse do possess a MC chymase with almost identical cleavage specificity as the human MC chymase indicating a strong evolutionary pressure to maintain this enzyme specificity.
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| 24. |
- Bradding, Peter, et al.
(author)
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The controversial role of mast cells in fibrosis
- 2018
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In: Immunological Reviews. - : John Wiley & Sons. - 0105-2896 .- 1600-065X. ; 282:1, s. 198-231
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Research review (peer-reviewed)abstract
- Fibrosis is a medical condition characterized by an excessive deposition of extracellular matrix compounds such as collagen in tissues. Fibrotic lesions are present in many diseases and can affect all organs. The excessive extracellular matrix accumulation in these conditions can often have serious consequences and in many cases be life-threatening. A typical event seen in many fibrotic conditions is a profound accumulation of mast cells (MCs), suggesting that these cells can contribute to the pathology. Indeed, there is now substantialv evidence pointing to an important role of MCs in fibrotic disease. However, investigations from various clinical settings and different animal models have arrived at partly contradictory conclusions as to how MCs affect fibrosis, with many studies suggesting a detrimental role of MCs whereas others suggest that MCs can be protective. Here, we review the current knowledge of how MCs can affect fibrosis.
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| 25. |
- Braga, Tiago, et al.
(author)
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Reduction with dithiothreitol causes serglycin-specific defects in secretory granule integrity of bone marrow derived mast cells
- 2009
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In: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 46:3, s. 422-428
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Journal article (peer-reviewed)abstract
- Mast cell granule maturation and storage of granule components has previously been shown to be critically dependent on serglycin (SG), a proteoglycan abundantly stored in mast cell secretory granules. The N-terminal portion of serglycin contains a conserved disulfide motif that is similar to motifs found in secretory granule compounds of neuroendocrine cells. Interference with such motifs of neuroendocrine cells with dithiothreitol (DTT) has previously been shown to cause cellular missorting. To investigate the implication for serglycin, serglycin(+/+) and serglycin(-/-) bone marrow derived mast cells (BMMCs) were treated with DTT followed by assessment of proteoglycan synthesis and secretory granule integrity. Treatment of serglycin(+/+) BMMCs with DTT almost completely abolished biosynthetic incorporation of (35)S-sulfate into proteoglycans, caused a dramatic reduction of granular staining with May Grünwald/Giemsa as well as disruption of granule dense core formation as shown by transmission electron microscopy. In addition, the storage of carboxypeptidase A, a major secretory granule compound, was markedly reduced following DTT treatment. In contrast, none of these effects were seen after treatment of SG(-/-) BMMCs with DTT, indicating that they were serglycin-specific. Notably, DTT treated serglycin(+/+) BMMCs showed similar morphology as did the serglycin(-/-) BMMCs. DTT treatment affected neither the viability of the BMMCs nor the mRNA levels for serglycin or carboxypeptidase A. Together, these data indicate that DTT causes dramatic, serglycin-specific effects on mast cell granule. These findings are thus in accordance with a role for the N-terminal disulfide motif in serglycin for regulation of mast cell secretory granule integrity.
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