Human Neutrophil Oxidative Bursts and their in vitro Modulation by Different N-Acetylcysteine Concentrations

Abstract

Reactive oxygen species released by activated polymorphonuclear leukocytes as an expression of their defensive function are considered to be a major source of the cytotoxic oxidant stress, that triggers a self-sustaining phlogogenic loop in the respiratory system. N-Acetylcysteine (CAS 616-91-1, NAC), a known mucolytic drug, possesses also antioxidant properties, but it undergoes a rapid and extensive first-pass metabolism resulting in low tissue availability. Thus to further improve the NAC bioavailability a single oral administration of 1200 mg NAC has been recently proposed. This study has been performed to investigate in vitro by means of luminol amplified chemiluminescence the ability of the concentration of 35 mumol/l NAC available after single oral administration of 1200 NAC to interfere with human neutrophil oxidative burst evoked by both corpuscolate and soluble stimulants, in comparison with 16 mumol/l NAC, the serum concentration obtainable after single oral administration of 600 mg NAC. At concentrations of 16 and 35 mumol/l, NAC significantly reduced in a concentration-dependent manner the activation of polymorphonuclear neutrophils (PMNs) oxidative bursts induced by all of the stimulants (C. albicans, formyl-methionyl-leucyl-phenylalanine (fMLP), phorbol myristate acetate (PMA)). This effect was also present in cell-free systems, thus confirming the scavenger activity of these two concentrations of NAC. The fact that no effects were seen on PMN phagocytosis and bacterial killing indicates that NAC has no negative influence on other PMN functions such as antimicrobial activity.

Pharmacological investigation on the anti-oxidant and anti-inflammatory activity of N-acetylcysteine in an ex vivo model of COPD exacerbation

“…Plasma concentrations of NAC reaches values of ≈ 5 μM after oral administration of 200 mg, ≈16 μM after oral administration of 600 mg, and ≈ 35 μM after an oral administration of 1,200 mg [14, 41, 42]. Therefore, the results of our study confirm that NAC administered at 600 mg may elicit prevalently anti-oxidant activity, whereas higher doses are necessary to produce anti-inflammatory effect.…”

Influence of the Protein Kinase C Activator Phorbol Myristate Acetate on the Intracellular Activity of Antibiotics against Hemin- and Menadione-Auxotrophic Small-Colony Variant Mutants of Staphylococcus aureus and Their Wild-Type Parental Strain in Human THP-1 Cells

“…Differentiation of THP-1 cells by PMA is known to activate cell defense mechanisms, including the production of reactive oxygen species (ROS) (43). We therefore examined whether the general antioxidant N-acetylcysteine, a scavenger of oxidative species widely used to counteract the pro-oxidant effects of phorbol esters (1,11,50), modulated the potency of antibiotics. For this purpose, infected cells were incubated for 24 h with each of the investigated antibiotics at its C s determined from the results of the concentration-effect experiments [ Table 1]) alone or in the presence of 25 mM N-acetylcysteine.…”

Free radical–scavenging activity of sulfurous water investigated by electron paramagnetic resonance (EPR) spectroscopy

“…In the third series of experiments, the radicalscavenging ability of sulfurous water was examined in relation to the water-soluble stable free nitroxide radical Tempol (4-hydroxy-2,2,6,6tetramethylpiperidine-N-oxyl) [22] 9.64 GHz, attenuation 7, and gain 100. The resultant spectrum consisted of a triplet, with 1:1:1 relative intensities, whose spectral constants (g = 2.00288, a14 N = 1.42 mT) were in accordance with previous literature findings [23].…”

“…This molecule has emerged as one of the most important antioxidant defence mechanisms in oxidant-induced lung injury and inflammation [3], and the fact that lung and nose concentrations are respectively 140 and 40 times those found in plasma [4][5][6][7] provides an important indication of the natural defensive strategy adopted by the human airways. On the basis of this observation, various low-weight soluble molecules bearing HS groups, such as N-acetylcysteine, mesna, thiopronine, and dithiotreitol, or the prodrugs stepronine and erdosteine, have been used for therapeutic purposes [1,[8][9][10]. However, in addition to using thiolic molecules, HS groups can be therapeutically administered by means of the inhalation of sulfurous thermal waters, which contain them in various concentrations.…”