Heparin Antagonists Are Potent Inhibitors of Mast Cell Tryptase

Hallgren, Jenny; Estrada, Sergio; Karlson, Ulrika; Alving, Kjell; Pejler, Gunnar

doi:10.1021/bi001988c

Cited by 63 publications

(53 citation statements)

References 31 publications

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“…Tryptase is one of the most powerful angiogenic mediators released by human MCs and it may be angiogenic via several mechanisms (23)(24)(25)(26). Blair et al have demonstrated that direct addition of tryptase to microvascular endothelial cells cultured on Matrigel caused a pronounced increase of capillary growth, which was suppressed by specific tryptase inhibitors, and directly induced endothelial cell proliferation in a dose-dependent fashion (10).…”

Section: Discussionmentioning

confidence: 99%

Tryptase-positive mast cells correlate with angiogenesis in early breast cancer patients

et al. 2009

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Abstract. Literature data indicate that mast cells (MCs) are involved in tumor angiogenesis due to the release of several pro-angiogenetic factors among which tryptase, a serine protease stored in MCs granules, is one of the most active. However, no data are available concerning the role of MCs in angiogenesis in primary human breast cancer. In this study, we have evaluated the correlations between the number of MCs positive to tryptase (MCDPT), the area occupied by MCs positive to tryptase (MCAPT) and microvascular density (MVD) and endothelial area (EA) in a series of 88 primary T1-3, N0-2 M0 female breast cancer, by means of immunohistochemistry and image analysis methods. Data demonstrated a significant (r = from 0.78 to 0.89; p-value from 0.001 to 0.002 by Pearson's analysis respectively) correlation between MCDPT, MCAPT, MVD, EA to each other. No correlation concerning MCDPT, MCAPT, MVD, EA and the main clinicopathological features was found. Our results suggest that tryptase-positive MCs play a role in breast cancer angiogenesis. In this context several tryptase inhibitors such as gabexate mesilate and nafamostat mesilate might be evaluated in clinical trials as a new anti-angiogenetic approach.

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Section: Discussionmentioning

confidence: 99%

Tryptase-positive mast cells correlate with angiogenesis in early breast cancer patients

et al. 2009

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“…The mechanism for the formation of active tryptase monomers apparently involves interaction with heparin, similar to the generation of tetrameric tryptase. The continuous presence of heparin is known to be essential for maintaining the activity of tetrameric tryptase, and interfering with the interaction of tryptase with heparin leads to tetramer dissociation along with enzymatic inactivation (23). A possible explanation for this would be that heparin is needed for bridging the tryptase subunits (see above and Fig.…”

Section: Discussionmentioning

confidence: 99%

“…In this context, it is noteworthy that heparin-binding compounds (e.g. polycations) are strongly inhibitory for mast cell tryptase, apparently by competing with tryptase for binding to heparin (23,24). It has also been suggested that the presence of heparin is required in the autocatalytic processing of protryptase to mature tryptase monomer (25).…”

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confidence: 99%

Structural Requirements and Mechanism for Heparin-induced Activation of a Recombinant Mouse Mast Cell Tryptase, Mouse Mast Cell Protease-6

Hallgren¹,

Spillmann²,

Pejler³

2001

Journal of Biological Chemistry

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Mast cell tryptase is stored as an active tetramer in complex with heparin in mast cell secretory granules. Previously, we demonstrated the dependence on heparin for the activation/tetramer formation of a recombinant tryptase. Here we have investigated the structural requirements for this activation process. The ability of heparin-related saccharides to activate a recombinant murine tryptase, mouse mast cell protease-6 (mMCP-6), was strongly dependent on anionic charge density and size. The dose-response curve for heparin-induced mMCP-6 activation displayed a bell-shaped appearance, indicating that heparin acts by binding to more than one tryptase monomer simultaneously. The minimal heparin oligosaccharide required for binding to mMCP-6 was 8 -10 saccharide units. Gel filtration analyses showed that such short oligosaccharides were unable to generate tryptase tetramers, but instead gave rise to active mMCP-6 monomers. The active monomers were inhibited by bovine pancreatic trypsin inhibitor, whereas the tetramers were resistant. Furthermore, monomeric (but not tetrameric) mMCP-6 degraded fibronectin. Our results suggest a model for tryptase tetramer formation that involves bridging of tryptase monomers by heparin or other highly sulfated polysaccharides of sufficient chain length. Moreover, our results raise the possibility that some of the reported activities of tryptase may be related to active tryptase monomers that may be formed according to the mechanism described here.

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“…The chemokine has been previously suggested as a potential candidate as a heparin antagonist to effect ␤-tryptase inhibition by Pejler and colleagues (8,55). In fact, in our experiments we found that CXCL4 dose-dependently inhibits ␤-tryptase, exhibiting IC 50 values between 14 and 1.3 M. These results are comparable to the described efficacy of other heparin antagonists to ␤-tryptase, e.g., 3.6, 16, 65, and more than 24 M for polybrene, myeloperoxidase, protamine sulfate, and lactoferrin, respectively (11,12,55,56). As destabilization of ␤-tryptase by CXCL4 strongly depends on the concentration and type of heparin added for complexation of the enzyme, it was an interesting result that inhibition required a 4-fold excess of CXCL4 over 15-kDa heparin (ratio of IC 50 to c(Heparin) of 4.4, 2.9, and 3.8).…”

Section: Discussionmentioning

confidence: 99%

The Cathelicidin LL-37 Activates Human Mast Cells and Is Degraded by Mast Cell Tryptase: Counter-Regulation by CXCL4

Schiemann¹,

Brandt²,

Groß³

et al. 2009

The Journal of Immunology

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The cathelicidin LL-37 represents a potent antimicrobial and cell-stimulating agent, most abundantly expressed in peripheral organs such as lung and skin during inflammation. Because mast cells (MC) overtake prominent immunomodulatory roles in these organs, we wondered whether interactions exist between MC and LL-37. In this study, we show for the first time to our knowledge that physiological concentrations of LL-37 induce degranulation in purified human lung MC. Intriguingly, as a consequence LL-37 rapidly undergoes limited cleavage by a released protease. The enzyme was identified as β-tryptase by inhibitor studies and by comparison to the recombinant protease. Examining the resulting LL-37 fragments for their functional activity, we found that none of the typical capacities of intact LL-37, i.e., MC degranulation, bactericidal activity, and neutralization of LPS, were retained. Conversely, we found that another inflammatory protein, the platelet-derived chemokine CXCL4, protects LL-37 from cleavage by β-tryptase. Interestingly, CXCL4 did not act as a direct enzyme inhibitor, but destabilized active tetrameric β-tryptase by antagonizing the heparin component required for the integrity of the tetramer. Altogether our results suggest that interaction of LL-37 and MC initiates an effective feedback loop to limit cathelicidin activity during inflammation, whereas CXCL4 may represent a physiological counter-regulator of β-tryptase activity.

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Heparin Antagonists Are Potent Inhibitors of Mast Cell Tryptase

Cited by 63 publications

References 31 publications

Tryptase-positive mast cells correlate with angiogenesis in early breast cancer patients

Tryptase-positive mast cells correlate with angiogenesis in early breast cancer patients

Structural Requirements and Mechanism for Heparin-induced Activation of a Recombinant Mouse Mast Cell Tryptase, Mouse Mast Cell Protease-6

The Cathelicidin LL-37 Activates Human Mast Cells and Is Degraded by Mast Cell Tryptase: Counter-Regulation by CXCL4

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