Proteome analysis of mast cell releasates reveals a role for chymase in the regulation of coagulation factor XIIIA levels via proteolytic degradation.
Mast cells are significantly involved in IgE-mediated allergic reactions; however, their roles in health and disease are incompletely understood.



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.



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.



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.



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.
Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, Wash.
Nicholas J
NJ
Shubin
Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, Wash.
Veronika A
VA
Glukhova
Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, Wash.
Morgan
M
Clauson
Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, Wash.
Phuong
P
Truong
Department of Biomedical Sciences and Veterinary Public Health, Swedish University for Agricultural Sciences, Uppsala, Sweden.
Magnus
M
Abrink
Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden; Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Gunnar
G
Pejler
Division of Emergency Medicine, Department of Medicine, University of Washington, Seattle, Wash.
Nathan J
NJ
White
Department of Laboratories, Seattle Children's Research Institute, Seattle, Wash.
Gail H
GH
Deutsch
Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, Wash; Department of Pediatrics, University of Washington, Seattle, Wash.
Stephen R
SR
Reeves
Division of Metabolism, Endocrinology, and Nutrition, Department of Medicine, University of Washington, Seattle, Wash.
Tomas
T
Vaisar
Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, Wash.
Richard G
RG
James
Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, Wash; Department of Pediatrics, University of Washington, Seattle, Wash. Electronic address: adrian.piliponsky@seattlechildrens.org.
Adrian M
AM
Piliponsky
D000818:Animals; D001853:Bone Marrow; D002478:Cells, Cultured; D053818:Chymases / Q000378:metabolism*; D005176:Factor XIII / Q000378:metabolism*; D006706:Homeostasis / Q000276:immunology; D008407:Mast Cells / Q000378:metabolism*; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010537:Peritoneum; D059748:Proteolysis; D020543:Proteome; D018805:Sepsis / Q000276:immunology
D020543:Proteome; D005176:Factor XIII; D053818:Chymases
Mast cells; chymase; proteases; proteomics