Effects of Acrolein on Leukotriene Biosynthesis in Human Neutrophils

Abstract

Acrolein is a toxic, highly reactive α,β-unsaturated aldehyde that is present in high concentrations in cigarette smoke. In the current study, the effect of acrolein on eicosanoid synthesis in stimulated human neutrophils was examined. Eicosanoid synthesis in neutrophils was initiated by priming with granulocyte-macrophage colony-stimulating factor (GM-CSF) and subsequent stimulation with formyl-methionyl-leucyl-phenylalanine (fMLP) and 5-LO products in addition to small amounts of COX products were detected using LC/MS/MS. A dose-dependent decrease in the formation of 5-LO products was observed in GM-CSF/fMLP stimulated neutrophils when acrolein (0-50 μM) was present with almost complete inhibition at ≥25 μM acrolein. The production of COX products was not affected by acrolein in these cells. The effect of acrolein was examined on key parts of the eicosanoid pathway, such as arachidonic acid release, intracellular calcium ion concentration, and adenosine production. In addition, the direct effect of acrolein on 5-LO enzymatic activity was probed using a recombinant enzyme. Some of these factors were affected by acrolein, but did not completely explain the almost complete inhibition of 5-LO product formation in GM-CSF/fMLP treated cells with acrolein. In addition, the effect of acrolein on different stimuli that initiate the 5-LO pathway (platelet-activating factor (PAF)/fMLP, GM-CSF/PAF, opsonized zymosan, and A23187) was examined. Acrolein had no significant effect on the leukotriene production in neutrophils stimulated with PAF/fMLP, GM-CSF/PAF, or OPZ. Additionally, 50% inhibition of the 5-LO pathway was observed in A23187 stimulated neutrophils. Our results suggest that acrolein has a profound effect on the 5-LO pathway in neutrophils, which may have implications in disease states, such as COPD and other pulmonary disease where both activated neutrophils and acrolein are present.

The composition of cigarette smoke determines inflammatory cell recruitment to the lung in COPD mouse models

“…They are highly reactive towards nucleophilic molecules in the cell such as DNA, proteins, aminophospholipids and glutathione and thereby contribute to the development of smoking related diseases [46,47]. The findings of the present study are in line with previous observations that higher concentrations for CCs such as acetaldehyde, acrolein, methacrolein and crotonaldehyde in the sidestream model might be caused by the incomplete combustion of sidestream CS as already described above.…”

Ion mobility and tandem mass spectrometry of phosphatidylglycerol and bis(monoacylglycerol) phosphate (BMP)

“…Electrospray ionization generated significantly more abundant negative molecular ions [M−H] − than positive ions [M+H] + for both BMP and PG using the electrospray parameters and conditions that we have typically employed for lipids [19]. This is in contrast to a previous report that more abundant positive molecular ion species were observed [11].…”

A Potential Role for Acrolein in Neutrophil-Mediated Chronic Inflammation

“…LTA4H is a bifunctional enzyme that converts leukotriene A4 (LTA4) to leukotriene B4 (LTB4) through its hydrolase activity as well as PGP degradation via aminopeptidase activity. In human PMNs, micromolar concentrations of acrolein inhibit generation of LTB4 [40], presumably by inhibiting the activity of LTA4H. We have proposed a novel mechanism for chronic inflammation through increased enzymatic breakdown of collagengenerating PGP fragments that attract additional neutrophils to sites of inflammation.…”