Regulation of LPS induced IL-12 production by IFN-γand IL-4 through intracellular glutathione status in human alveolar macrophages

Abstract

SUMMARYInterleukin-12 (IL-12) is secreted from monocytes and macrophages; it exerts pleiotropic effects on T cells and natural killer (NK) cells, and stimulates interferon-g (IFN-g ) secretion. Glutathione tripeptide regulates the intracellular redox status and other aspects of cell physiology. We examined whether IFNg and IL-4 affect the balance between intracellular reduced glutathione (GSH) and oxidized (GSSG) glutathione, as this may affect IL-12 production in human alveolar macrophages (AM). We used both AM from healthy non-smokers obtained by bronchoalveolar lavage and the monocytic THP-1 cell line in this study. Incubation of AM for 2 h with the GSH precursor N-acetylcysteine (NAC) increased the intracellular GSH/GSSG ratio, and enhanced lipopolysaccharide (LPS)-induced IL-12 secretion by AM. In THP-1 cells, NAC increased the GSH/GSSG ratio and the expression of LPS-induced IL-12 mRNA, whereas l-buthionine-[S,R]-sulphoximine (BSO) decreased these. NAC and BSO offset their own effects on the intracellular GSH/GSSG ratio and the expression of LPS-induced IL-12 mRNA. Furthermore, exposure of AM to the helper T cell type 1 (Th1) cytokine IFN-g or the helper T cell type 2 (Th2) cytokine IL-4 for 72 h increased and decreased the GSH/GSSG ratio, respectively. Lipopolysaccharide (LPS)-induced secretion of IL-12 in AM was enhanced by IFN-g but inhibited by IL-4. These results suggest that IFN-g and IL-4 oppositely affect the GSH/GSSG balance, which may regulate IL-12 secretion from AM in response to LPS.

Evidence That Glutathione Depletion Is a Mechanism Responsible for the Anti-Inflammatory Effects of Ethyl Pyruvate in Cultured Lipopolysaccharide-Stimulated RAW 264.7 Cells

“…Although both EP and NAC inhibited LPS-induced TBARS formation and cytokine and NO release, these two compounds had qualitatively different effects on cellular concentrations of GSH. Although NAC increased cellular GSH levels as expected (Dobashi et al, 2001;Haddad, 2002b), EP had the opposite effect. Furthermore, the anti-inflammatory effects of EP were partially reversed if the cells were treated with glutathione ethyl ester (GSH-Et), an established approach for increasing cellular levels of GSH (Buchmuller-Rouiller et al, 1995).…”

Glutathione-Redox Balance Regulates c-rel–Driven IL-12 Production in Macrophages: Possible Implications in Antituberculosis Immunotherapy

“…1B). Intracellular glutathione-redox balance was indicated as GSH/GSSG (29). The GSH/GSSG balance showed predominantly a reducing state when macrophages were treated with NAC up to 3 mM due to increased levels of intracellular GSH (Fig.…”

SOD1 overexpression alters ROS production and reduces neurotoxic inflammatory signaling in microglial cells

“…For instance, activation of the oxidative burst system has been specifically implicated in the induction of well-known inflammatory signaling pathways, including activation of NFκB, and synthesis of TNFα (Kaul and Forman, 1996) and prostaglandin E 2 (Wang et al, 2004). Similarly, levels of reduced glutathione in macrophages tightly regulate the release of many immune mediators, including prostaglandins, interleukin-4, interleukin-6, and interleukin-12 (Murata et al, 2002), (Dobashi et al, 2001).…”