Lipid mediator metabolic profiling demonstrates differences in eicosanoid patterns in two phenotypically distinct mast cell populations

Susanna L Lundström,Rohit Saluja,Jesper Z Haeggström,Mikael Adner,Craig E Wheelock,Gunnar Nilsson

doi:10.1194/jlr.m030171

Abstract

Mast cells are inflammatory cells that play key roles in health and disease. They are distributed in all tissues and appear in two main phenotypes, connective tissue and mucosal mast cells, with differing capacities to release inflammatory mediators. A metabolic profiling approach was used to obtain a more comprehensive understanding of the ability of mast cell phenotypes to produce eicosanoids and other lipid mediators. A total of 90 lipid mediators (oxylipins) were characterized using liquid chromatography-tandem mass spectrometry (LC-MS/MS), representing the cyclooxygenase (COX), lipoxygenase (LO), and cytochrome P450 (CYP) metabolic pathways. In vitro-derived murine mucosal-like mast cells (MLMC) and connective tissue-like mast cells (CTLMC) exhibited distinct mRNA expression patterns of enzymes involved in oxylipin biosynthesis. Oxylipins produced by 5-LO and COX pathways were the predominant species in both phenotypes, with 5-LO products constituting 90 ± 2% of the CTLMCs compared with 58 ± 8% in the MLMCs. Multivariate analyses demonstrated that CTLMCs and MLMCs secrete differing oxylipin profiles at baseline and following calcium ionophore stimulation, evidencing specificity in both a time- and biosynthetic pathway-dependent manner. In addition to the COX-regulated prostaglandin PGD(2) and 5-LO-regulated cysteinyl-leukotrienes (e.g., LTC(4)), several other mediators evidenced phenotype-specificity, which may have biological implications in mast cell-mediated regulation of inflammatory responses.

Highlights

Mast cells are inflammatory cells that play key roles in health and disease
To confirm the presence of the necessary message of the enzymes responsible for oxylipin formation in both connective tissue-like mast cells (CTLMC) and mucosal-like mast cells (MLMC), we performed a PCR array on mRNA purified from resting CTLMCs and MLMCs as well as on the bone marrow cells (BMC) that are the source for differentiation
For LT synthesis, CTLMCs expressed the highest levels of LTA4 hydrolase (LTA4H), whereas MLMCs expressed the highest levels of 5-LO and leukotrienes C4 (LTC4) synthase (LTC4S)

Summary

Introduction

Mast cells are inflammatory cells that play key roles in health and disease They are distributed in all tissues and appear in two main phenotypes, connective tissue and mucosal mast cells, with differing capacities to release inflammatory mediators. A metabolic profiling approach was used to obtain a more comprehensive understanding of the ability of mast cell phenotypes to produce eicosanoids and other lipid mediators. Mast cells are distributed in all tissues and are numerous in those tissues that are in close contact with the environment, e.g., the skin, the gastrointestinal tract, and the respiratory system [2] They express a variety of receptors that recognize both endogenous (e.g., cytokines, neuropeptides, complement) and exogenous molecules (e.g., pathogen-derived molecules, allergens through IgE receptor cross-linking). The spectra of released mediators are dictated by the stimuli; for example, IgE-receptor aggregation causes degranulation, lipid mediator secretion, and release of cytokines, whereas other stimuli, such as CD153, only lead to a specific release of primarily chemokines [3]

Methods

Results

Conclusion