Search

Background: Mast cells are involved in many distinct pathologic conditions, suggesting that they recognize and respond to various stimuli and thus require a rich repertoire of cell surface proteins. However, mast cell surface proteomes have not been comprehensively characterized., Objective: We aimed to further characterize the mast cell surface proteome to obtain a better understanding of how mast cells function in health and disease., Methods: We enriched for glycosylated surface proteins expressed in mouse bone marrow-derived cultured mast cells (BMCMCs) and identified them using mass spectrometry analysis. The presence of novel surface proteins in mast cells was validated by real-time quantitative PCR and flow cytometry analysis in BMCMCs and peritoneal mast cells (PMCs). We developed a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) gene editing approach to disrupt genes of interest in BMCMCs., Results: The glycoprotein enrichment approach resulted in the identification of 1270 proteins in BMCMCs, 378 of which were localized to the plasma membrane. The most common protein classes among plasma membrane proteins were small GTPases, receptors, and transporters. One such cell surface protein was CD98 heavy chain (CD98hc), encoded by the Slc3a2 gene. Slc3a2 gene disruption resulted in a significant reduction in CD98hc expression, adhesion, and proliferation., Conclusions: Glycoprotein enrichment coupled with mass spectrometry can be used to identify novel surface molecules in mast cells. Moreover, CD98hc plays an important role in mast cell function., (Copyright © 2021 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Respiratory viral infection in early childhood, including that from respiratory syncytial virus (RSV), has been previously associated with the development of asthma., Objective: We aimed to determine whether ex vivo RSV infection of bronchial epithelial cells (BECs) from children with asthma would induce specific gene expression patterns and whether such patterns were associated with lung function among BEC donors., Methods: Primary BECs from carefully characterized children with asthma (n = 18) and matched healthy children without asthma (n = 8) were differentiated at an air-liquid interface for 21 days. Air-liquid interface cultures were infected with RSV for 96 hours and RNA was subsequently isolated from BECs. In each case, we analyzed gene expression using RNA sequencing and assessed differences between conditions by linear modeling of the data. BEC donors completed spirometry to measure lung function., Results: RSV infection of BECs from subjects with asthma, compared with uninfected BECs from subjects with asthma, led to a significant increase in expression of 6199 genes. There was significantly greater expression of 195 genes in BECs from children with asthma and airway obstruction (FEV 1 /forced vital capacity < 0.85 and FEV 1  < 100% predicted) than in BECs from children with asthma without obstruction, or in BECs from healthy children. These specific genes were found to be highly enriched for viral response genes induced in parallel with types I and III interferons., Conclusions: BECs from children with asthma and with obstructive physiology exhibit greater expression of types I and III interferons and interferon-stimulated genes than do cells from children with normal lung function, and expression of interferon-associated genes correlates with the degree of airway obstruction. These findings suggest that an exaggerated interferon response to viral infection by airway epithelial cells may be a mechanism leading to lung function decline in a subset of children with asthma., (Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Mast cells are significantly involved in IgE-mediated allergic reactions; however, their roles in health and disease are incompletely understood., Objective: 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., Methods: 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., Results: 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., Conclusions: 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., Competing Interests: of Conflict of Interest: The authors declare no competing financial interests., (Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)