Effect of 4-hydroxy-2,3-trans-nonenal and related aldehydes on phospholipase C activity of rat neutrophils

Our work has evaluated the effects of certain lipid peroxidation products, i.e. 4-hydroxy-2,3-trans-nonenal (HNE), 4-hydroxy-2,3-trans-octenal (HOE), 2-trans-nonenal and nonanal, on phosphoinositide-specific phospholipase C (PL-C). The enzymatic activity has been determined in vitro by measuring the hydrolysis of labelled phosphatidylinositol-4,5-bisphosphate added to plasma membranes isolated from rat neutrophils. Concentrations of HNE between 10(-8) and 10(-6) M, and concentrations of HOE ranging from 10(-11) to 10(-8) M, were able to activate PL-C. Neither 2-trans-nonenal nor nonanal induced any change of PL-C activity. HNE, HOE and 2-nonenal, but not nonanal, have been shown to possess chemotactic properties towards rat neutrophils. The good correlation between the concentrations of HNE and HOE active on PL-C and those able to stimulate cell migration suggests that their chemotactic activity might be mediated by the activation of PL-C, as in the case of most chemoattractants. On the contrary, this mechanism of action cannot be applied to 2-nonenal, an aldehyde much more hydrophobic than HNE or HOE; its chemotactic activity might be the consequence of some perturbation of the lipidic environment of the cell membrane where it dissolves easily.