Silicosis
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Researchers from University of Genoa publish new studies and findings in the area of respiratory medicine
2009 MAY 18 - (NewsRx.com) -- According to a study from Genoa, Italy, "Inhalation of crystalline silica induces a pulmonary fibrotic degeneration called silicosis caused by the inability of alveolar macrophages to dissolve the crystalline structure of phagocytosed quartz particles. Ascorbic acid is capable of partially dissolving quartz crystals, leading to an increase of soluble silica concentration and to the generation of new radical sites on the quartz surface." "The reaction is specific for the crystalline forms of silica. It has been already demonstrated an increased cytotoxicity and stronger induction of pro-inflammatory cyclooxygenase-2 (COX-2) by ascorbic acid pre-treated quartz (QA) compared to untreated quartz (Q) in the murine macrophage cell line RAW 264.7. Taking advantage of the enhanced macrophage response to QA as compared to Q particles, we investigated the first steps of cell activation and the contribution of early signals generated directly from the plasma membrane to the production of TNF-alpha, a cytokine that activates both inflammatory and fibrogenic pathways. Here we demonstrate that TNF-alpha mRNA synthesis and protein secretion are significantly increased in RAW 264.7 macrophages challenged with QA as compared to Q particles, and that the enhanced response is due to an increase of intracellular ROS. Plasma membrane-particle contact, in the absence of phagocytosis, is sufficient to trigger TNF-alpha production through a mechanism involving membrane lipid peroxidation and this appears to be even more detrimental to macrophage survival than particle phagocytosis itself," wrote S. Scarfi and colleagues, University of Genoa. The researchers concluded: "Taken together these data suggest that an impairment of pulmonary macrophage phagocytosis, i.e. in the case of alcoholic subjects, could potentiate lung disease in silica-exposed individuals." Scarfi and colleagues published the results of their research in Respiratory Research (Ascorbic acid pre-treated quartz stimulates TNF-alpha release in RAW 264.7 murine macrophages through ROS production and membrane lipid peroxidation. Respiratory Research, 2009;10():25). For additional information, contact S. Scarfi, University of Genoa, Dept. of Experimental Medical, Biochemistry Sect, I-16132 Genoa, Italy. The publisher of the journal Respiratory Research can be contacted at: Biomedical Central Ltd., Current Science Group, Middlesex House, 34-42 Cleveland St., London W1T 4LB, England. Keywords: Italy, Genoa, Life Sciences, Silicosis, Enzymology, Cyclooxygenase, Pain Medicine, COX-2 Inhibitors, Respiratory Research, Respiratory Medicine, University of Genoa. This article was prepared by Respiratory Therapeutics Week editors from staff and other reports. Copyright 2009, Respiratory Therapeutics Week via NewsRx.com.
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