Time Course of Gene Expression of Inflammatory Mediators in Rat Lung after Diesel Exhaust Particle Exposure

Abstract

Diesel exhaust particles (DEPs) at three concentrations (5, 35, and 50 mg/kg body weight) were instilled into rats intratracheally. We studied gene expression at 1, 7, and 30 days postexposure in cells obtained by bronchoalveolar lavage (BAL) and in lung tissue. Using real-time reverse transcriptase-polymerase chain reaction (RT-PCR), we measured the mRNA levels of eight genes [interleukin (IL)-1β, IL-6, IL-10, iNOS (inducible nitric oxide synthase), MCP-1 (monocyte chemoattractant protein-1), MIP-2 (macrophage inflammatory protein-2), TGF-β1 (transforming growth factor-β1), and TNF-α (tumor necrosis factor-α)] in BAL cells and four genes [IL-6, ICAM-1 (intercellular adhesion molecule-1), GM-CSF (granulocyte/macrophage-colony stimulating factor), and RANTES (regulated upon activation normal T cell expressed and secreted)] in lung tissue. In BAL cells on day 1, high-dose exposure induced a significant up-regulation of IL-1β, iNOS, MCP-1, and MIP-2 but no change in IL-6, IL-10, TGF-β1, and TNF-α mRNA levels. There was no change in the mRNA levels of IL-6, RANTES, ICAM-1, and GM-CSF in lung tissue. Nitric oxide production and levels of MCP-1 and MIP-2 were increased in the 24-hr culture media of alveolar macrophages (AMs) obtained on day 1. IL-6, MCP-1, and MIP-2 levels were also elevated in the BAL fluid. BAL fluid also showed increases in albumin and lactate dehydrogenase. The cellular content in BAL fluid increased at all doses and at all time periods, mainly due to an increase in polymorphonuclear leukocytes. In vitro studies in AMs and cultured lung fibroblasts showed that lung fibroblasts are a significant source of IL-6 and MCP-1 in the lung.

Role of human pulmonary fibroblast-derived MCP-1 in cell activation and migration in experimental silicosis

“…Our study demonstrated that the MCP-1 levels in the supernatant from HPF-a increased in a time-dependent manner after exposure to SiO 2 , and the peak MCP-1 concentration was observed at 6 h. Previous studies have shown that the MCP-1 mRNA levels in rat pulmonary fibroblasts were significantly increased after SiO 2 exposure for 4 h (Rao et al, 2005). The mRNA expression of cytokines does not always correlate with their protein expression; therefore, it was necessary to ascertain whether the MCP-1 protein levels were also increased in the cell culture medium.…”

“…AMOs are the primary producers of the cytokines and chemokines that are involved in the acquired immune response (Fearon and Locksley, 1996). Recent studies have suggested that cytokines and chemokines secreted by lung parenchymal cells are also involved in the pathogenesis of silicosis (Kim et al, 2002;Moore et al, 2003;Rao et al, 2004Rao et al, , 2005. The aim of the current study was to investigate the role of pulmonary fibroblast-derived MCP-1 in cell activation and migration after exposure to SiO 2 .…”

“…Fibroblasts are an important source of inflammatory mediators, such as chemokines and cytokines (Kim et al, 2002;Rao et al, 2005). For instance, silica-stimulated Rat2 fibroblasts generated ROS via the NADPH oxidase, PKC and CaM kinase II pathways (Kim et al, 2002).…”

Time-dependent translocation and potential impairment on central nervous system by intranasally instilled TiO2 nanoparticles

“…The immune cytokines are synthesized by the activated microglia, astrocyte, monocyte, macrophages and neutrophil in response to foreign stimuli, such as TiO 2 , ultrafine particles, Ti and Ti alloys particulate wear debris, (Campbell et al, 2005;Vallés et al, 2006;Vermes et al, 2001). In lung tissue, the elevated releases of cytokines have been also reported in mammalians exposed to ultrafine particles (Rao et al, 2005;Inoue et al, 2005). It is demonstrated that there is a further increase in such inflammation in neurodegenerative disorders (Rothwell and Relton, 1993;Venters et al, 1999).…”

Oxidatively damaged DNA and inflammation in the liver of dyslipidemic ApoE−/− mice exposed to diesel exhaust particles

“…The regulation of iNOS can be investigated at the level of mRNA or as serum concentration of nitric oxide (NO) as functional endpoint. Intratracheal instillation of diesel exhaust particles (DEP) has been associated with elevated mRNA levels of components involved in the inflammation, including iNOS, in bronchoalveolar lavage cells and lung tissue (Ulrich et al, 2002;Rao et al, 2005).…”