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Neutrophilia, gelatinase release and microvascular leakage induced by human mast cell tryptase in a mouse model: lack of a role of protease activated receptor 2 (PAR2)

Neutrophilia, gelatinase release and microvascular leakage induced by human mast cell tryptase in a mouse model: lack of a role of protease activated receptor 2 (PAR2)
Neutrophilia, gelatinase release and microvascular leakage induced by human mast cell tryptase in a mouse model: lack of a role of protease activated receptor 2 (PAR2)

Background: tryptase, the most abundant protease of the human mast cell, has been implicated as a key mediator of allergic inflammation that acts through activation of PAR2.

Objectives: to investigate the contribution of PAR2 in the pro-inflammatory actions mediated by tryptase in a mice model.

Methods: we have injected recombinant human βII-tryptase into the peritoneum of PAR2-deficient and wild-type C57BL/6 mice. After 6, 12 and 24 hours mice were euthanized, peritoneal lavage performed and inflammatory changes investigated.

Results: tryptase stimulated an increase in neutrophil numbers in the peritoneum, but responses did not differ between PAR2-deficient and wild-type mice. Heat-inactivation of tryptase or pre-incubation with a selective tryptase inhibitor reduced neutrophilia, but neutrophil accumulation was not elicited with a peptide agonist of PAR2 (SLIGRL-NH2 ). Zymography indicated that tryptase stimulated the release of matrix metalloproteinases (MMP) 2 and 9 in the peritoneum of both mouse strains. Studies involving immunomagnetic isolation of neutrophils suggested that neutrophils represent the major cellular source of tryptase-induced MMP2 and MMP9. At 24 h after tryptase injection there was increased microvascular leakage as indicated by high levels of albumin in peritoneal lavage fluid, and this appeared to be partially abolished by heat-inactivating tryptase or addition of a protease inhibitor. There was no corresponding increase in levels of histamine or total protein. The extent of tryptase-induced microvascular leakage or gelatinase release into the peritoneum did not differ between PAR2-deficient and wild-type mice.

Conclusions: our findings indicate that tryptase is a potent stimulus for neutrophil accumulation, MMP release and microvascular leakage. Though these actions required an intact catalytic site, the primary mechanism of tryptase in vivo would appear to involve processes independent of PAR2. This article is protected by copyright. All rights reserved.

Journal Article
0954-7894
555-567
Khedr, Mogibelrahman M S
37c876ff-7226-4d51-bd20-dfe0bbca3d73
Abdelmotelb, Ahmed M
47ec298b-4ec1-48e4-8a19-39f2235de4a5
Pender, Sylvia L F
62528b03-ec42-41bb-80fe-48454c2c5242
Zhou, Xiaoying
84558a96-3129-44de-b295-869d9ee4d19f
Walls, Andrew F
aaa7e455-0562-4b4c-94f5-ec29c74b1bfe
Khedr, Mogibelrahman M S
37c876ff-7226-4d51-bd20-dfe0bbca3d73
Abdelmotelb, Ahmed M
47ec298b-4ec1-48e4-8a19-39f2235de4a5
Pender, Sylvia L F
62528b03-ec42-41bb-80fe-48454c2c5242
Zhou, Xiaoying
84558a96-3129-44de-b295-869d9ee4d19f
Walls, Andrew F
aaa7e455-0562-4b4c-94f5-ec29c74b1bfe

Khedr, Mogibelrahman M S, Abdelmotelb, Ahmed M, Pender, Sylvia L F, Zhou, Xiaoying and Walls, Andrew F (2018) Neutrophilia, gelatinase release and microvascular leakage induced by human mast cell tryptase in a mouse model: lack of a role of protease activated receptor 2 (PAR2). Clinical & Experimental Allergy, 48 (5), 555-567. (doi:10.1111/cea.13108).

Record type: Article

Abstract

Background: tryptase, the most abundant protease of the human mast cell, has been implicated as a key mediator of allergic inflammation that acts through activation of PAR2.

Objectives: to investigate the contribution of PAR2 in the pro-inflammatory actions mediated by tryptase in a mice model.

Methods: we have injected recombinant human βII-tryptase into the peritoneum of PAR2-deficient and wild-type C57BL/6 mice. After 6, 12 and 24 hours mice were euthanized, peritoneal lavage performed and inflammatory changes investigated.

Results: tryptase stimulated an increase in neutrophil numbers in the peritoneum, but responses did not differ between PAR2-deficient and wild-type mice. Heat-inactivation of tryptase or pre-incubation with a selective tryptase inhibitor reduced neutrophilia, but neutrophil accumulation was not elicited with a peptide agonist of PAR2 (SLIGRL-NH2 ). Zymography indicated that tryptase stimulated the release of matrix metalloproteinases (MMP) 2 and 9 in the peritoneum of both mouse strains. Studies involving immunomagnetic isolation of neutrophils suggested that neutrophils represent the major cellular source of tryptase-induced MMP2 and MMP9. At 24 h after tryptase injection there was increased microvascular leakage as indicated by high levels of albumin in peritoneal lavage fluid, and this appeared to be partially abolished by heat-inactivating tryptase or addition of a protease inhibitor. There was no corresponding increase in levels of histamine or total protein. The extent of tryptase-induced microvascular leakage or gelatinase release into the peritoneum did not differ between PAR2-deficient and wild-type mice.

Conclusions: our findings indicate that tryptase is a potent stimulus for neutrophil accumulation, MMP release and microvascular leakage. Though these actions required an intact catalytic site, the primary mechanism of tryptase in vivo would appear to involve processes independent of PAR2. This article is protected by copyright. All rights reserved.

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Khedr_et_al-2018-Clinical_&_Experimental_Allergy - Accepted Manuscript
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Accepted/In Press date: 20 January 2018
e-pub ahead of print date: 31 January 2018
Published date: May 2018
Keywords: Journal Article

Identifiers

Local EPrints ID: 417888
URI: http://eprints.soton.ac.uk/id/eprint/417888
ISSN: 0954-7894
PURE UUID: 5c80950d-f4f5-41c5-9eed-f1858cb1b134
ORCID for Mogibelrahman M S Khedr: ORCID iD orcid.org/0000-0001-9942-4409
ORCID for Sylvia L F Pender: ORCID iD orcid.org/0000-0001-6332-0333
ORCID for Andrew F Walls: ORCID iD orcid.org/0000-0003-4803-4595

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Date deposited: 16 Feb 2018 17:30
Last modified: 22 Nov 2021 06:08

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Contributors

Author: Mogibelrahman M S Khedr ORCID iD
Author: Ahmed M Abdelmotelb
Author: Xiaoying Zhou
Author: Andrew F Walls ORCID iD

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