Inhibition by reactive aldehydes of superoxide anion radical production from stimulated polymorphonuclear leukocytes and pulmonary alveolar macrophages

Alpha,beta-unsaturated aldehydes such as acrolein (ACR) and crotonaldehyde (CRO) have been shown previously in our laboratory to inhibit the production of Superoxide anion radical (O 2 − ) by stimulated phagocytic cells in vitro in a dose-related manner. Based on the known reactivity of these compounds towards cellular sulfhydryls (SH), the present studies were aimed at investigating cellular SH status in relation to O 2 − production. Plasma membrane surface SH groups were measured using carboxypyridinedisulfide and monitoring the resultant formation of mixed disulfides through assay of thione released into the supernatant fraction. Intracellular non-protein sulfhydryls were measured using 5,5′-dithiobis-2-nitrobenzoic acid. In both human polymorphonuclear leukocytes (PMN) and rat pulmonary alveolar macrophages (PAM) there was a dose-related decrease in surface SH and soluble SH after ACR and CRO treatment. Propionaldehyde, a three-carbon saturated aldehyde, was without effect. The decrease in surface SH was greater than the decrease in soluble SH. In addition, in PMN and PAM preincubated with 5–40 μM ACR, there was a dose-related inhibition in the rate of O 2 − production with no effect on the lag time as measured by cytochrome c reduction. In stimulated PMN, there was a dose-related decrease in the rate after addition of 5–40 μM ACR. These data suggest that changes in SH status by reactive aldehydes can modulate the activity of the plasma membrane NADPH oxidase responsible for O 2 − production.