Mechanisms for the oxidation of reduced gluthathione by stimulated granulocytes

Abstract

We have reported previously that human granulocytes have an irreversible fall in their endogenous reduced soluble sulfhydryls following zymosan stimulation. In the present study, we demonstrate that stimulated granulocytes release one or more reactive oxygen species (ROS) with the capacity to oxidize reduced glutathione (GSH). One or more of these compounds is stable enough to be detected in the supernatant. The formation of these stable oxidants appears to require H2O2 and heme or a heme-containing enzyme. However, once formed, the compound reacts with GSH without these factors. The ROS is not superoxide or hydroxyl radical, since neither superoxide dismutase nor the hydroxyl scavengers, mannitol and benzoic acid, change the rate of the reaction. Methionine has recently been demonstrated to be oxidized to a sulfoxide by a reactive oxygen species that is dependent on H2O2 and heme for its production. We found that methionine could directly react with the same ROS that degrades GSH. The ROS also has the capacity to oxidize iodide and fix halogen to proteins. Our data indicate that stimulated granulocytes release a ROS with the capacity to oxidize GSH, react with methionine, and oxidize and fix I- to protein. The compound, therefore, appears dependent on H2O2 and the myeloperoxidase system for its production, and is either hypochlorous acid (HOCI) or a compound derived from HOCI, such as a chloramine. The capacity of GSH to react with this ROS suggests an additional role for this tripeptide in cellular protection against oxidant injury.

Alveolar Fluid Glutathione Decreases in Asymptomatic HIV-Seropositive Subjects Over Time

“…The concentration of total glutathione in ELF was 689.0±100. 4 |xM. This significantly decreased when measured 6 and 12 months later (355.9±41.7 jxM, and 397.9±52.7 |jlM, respectively, p=0.01 compared to baseline, both comparisons).…”

“…BAL was performed as previously described.9 The BAL fluid was filtered immediately through coarse surgical gauze and centrifuged (300 g, 10 min) to separate cellular and noncellular elements. The supernatant was acidified to a pH of 5.5 using 4 fiL/mL of 50% 5-sulfosalicylic acid (SSA) and immediately assayed for GSH and oxidized GSH (GSSG) (see below). Once the supernatant was decanted, the cell pellet was suspended in 10 mL of Hanks' balanced salt solution without calcium or magne¬ sium.…”

Glutathione Homeostasis and Functions: Potential Targets for Medical Interventions

“…GSH may be oxidized directly by oxidants such as hydroxyl radical (HO • ) [ 28 , 29 ] or peroxynitrite (ONOO − ) [ 30 , 31 ]. Direct oxidation leads to the production of thiyl radicals [ 32 ], the fusion of which results in GSSG formation ( Figure 2 ).…”

The Glutathione System: A New Drug Target in Neuroimmune Disorders

“…As mentioned above, the glutathione system is the most important protectant in the detoxification of ROS and RNS and as such is a vital component of the cellular anti-oxidant defenses [2,167]. Glutathione reacts directly with different radical molecules and may be directly oxidized by HO [168,169] and peroxinitrite [170,171]. Glutathione is involved in the detoxification of NO.…”