Bronchial smooth muscle cells release prostaglandins and 15-LOX metabolites in response to different inflammatory stimuli

<bold>Background:</bold> Lipid mediators are pivotal for many inflammatory processes within the immune system and possess a variety of important functions including infiltration of immune cells and contraction of smooth muscle cells in the lung. Bronchial smooth muscle cells (BSMCs) are involved in airway hyperresponsiveness as well as crosstalk between immune cells and the airway epithelium. <bold>Aim:</bold> The project aim was to investigate production of lipid mediators from the cyclooxygenase (COX) and lipoxygenase (LOX) pathways in BSMCs after exposure to various inflammatory stimuli. We focused on production of COX-derived prostaglandins (PG) and 15-LOX-derived mono-oxygenated oxylipins from dihomo-γ-linolenic acid (DGLA), arachidonic acid (AA) and eicosapentaenoic acid (EPA). <bold>Methods:</bold> Primary BSMCs from 3 donors (Lonza) were treated with LPS, IL-1β, alarmins or IL-13 for 24 hr. Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was used to quantify the lipid profiles of cell supernatants from 500,000 cells/well. <bold>Results:</bold> IL-1β (10 ng/mL) was the most potent cytokine resulting in release of PGE1, PGE2, and PGE3, with PGE2 exhibiting the highest levels (558±355 ng/mL, p=0.0001). Among the PGD series, only PGD2 was detectable. Levels of the AA-derived 15-LOX metabolite 15-HETE were elevated following exposure to IL-1β (4.3±2.8 ng/mL, p=0.0045). Cells treated with LPS, IL-13, and alarmins exhibited responses similar to homeostatic conditions. <bold>Conclusions:</bold> Findings indicate that IL-1β stimulation markedly enhances production of the PGE series compared to other inflammatory stimuli and demonstrate that BSMCs are a potential source of lipid mediator release in the airways