Intracellular glutathione redox status modulates MCP-1 expression in pulmonary granulomatous vasculitis

A wide spectrum of human lung diseases is characterized by the presence of granulomas. Although understanding of the pathways leading to their development remains incomplete, data from in vitro studies suggest that neutrophils, monocytes, and their secreted products (eg, hydrogen peroxide, H2O2) influence the pathogenesis of pulmonary granulomatous disease through the regulation of local chemokine and cytokine production. Using a well-characterized rat model of glucan-induced pulmonary granulomatous vasculitis, we sought to determine the role of intracellular glutathione (GSH) redox status in the expression of monocyte chemoattractant protein-1 (MCP-1). Previous studies have revealed that vascular wall MCP-1 expression is obligatory for granuloma development and that both neutrophils and hydrogen peroxide are required for MCP-1 induction. Because in vitro expression of MCP-1 is in part mediated by the redox-sensitive transcription factors nuclear factor-kappa B (NF-kappaB) and activator protein-1 (AP-1), we studied their activation as a function of varying intracellular GSH redox status in the pathogenesis of glucan-induced pulmonary granulomatosis. Infusion of particulate yeast cell wall glucan into rats resulted in a rapid decrease in intracellular GSH concentrations which was accompanied by the activation of NF-kappaB and AP-1. The pattern of AP-1 and NF-kappaB activation in turn correlated temporally with the expression of MCP-1. Administration of L-buthionine-S, R-sulfoximine, a specific inhibitor of gamma-glutamyl cysteine synthetase, resulted in a significant reduction in intracellular GSH pools. GSH depletion resulted in a more than 100% increase in pulmonary MCP-1 concentrations and increased cytosolic to nuclear translocation of NF-kappaB while having no effect on AP-1 levels. These observations suggest that in the pathogenesis of pulmonary granulomatous disease, intracellular glutathione redox status modulates the expression of MCP-1 through redox-sensitive transcription factors.