Project description:In this study, we isolated the exosomes derived from macrophage treated with or withnot silica for 48h, and identified a subset of differentially expressed miRNAs enriched in the exosomes compared with blank control
Project description:Exposure to crystalline silica results in serious health effects, most notably, silicosis and cancer. An understanding of the silica-induced lung toxicity is critical for the intervention and/or prevention of its adverse health effects. Rats were exposed by inhalation to air or crystalline silica (15 mg/m3, 6 hours/day for 5 days). At post-exposure time intervals of 1, 3, 6, 9, 12, and 18 months, the control and silica exposed rats were euthanized, and lung toxicity and gene expression profiles determined. Histological changes indicative of lung toxicity detected in the silica exposed rats included infiltration of neutrophils, thickening of alveolar epithelium, and fibrosis. Significant increases in lactate dehydrogenase activity, number of phagocytes, and inflammatory cytokine levels were detected in the bronchoalveolar lavage (BAL) obtained from the silica exposed rats compared with the corresponding time-matched controls. Significant changes in lung gene expression profiles, corresponding to the changes in the lung toxicity parameters analyzed, were detected in the silica exposed rats. The BAL parameters of toxicity and inflammation peaked at the 12-months post-exposure time interval and declined subsequently. However, lung fibrosis continued to progress being highest at the 18-month post-exposure time interval. These results suggest that inflammation may be required for the initiation but not for the progression and/or maintenance of lung fibrosis in response to silica exposure in the rats.
Project description:Our previous studies have shown that tobacco smoke exposure exacerbated the lung response to crystalline silica exposure in rats. The objective of the present study, a follow-up to our previous study, was to determine the effect of tobacco smoke exposure cessation on the lung response to crystalline silica exposure in the rats. Rats were exposed to air, crystalline silica (1 week followed by a 1 year progression/recovery period with no exposure), tobacco smoke (6 months of exposure followed by 6 months of recovery with no exposure), or crystalline silica (1 week) plus tobacco smoke (6 months of exposure followed by 6 months of recovery with no exposure). Lung toxicity was determined at the end of the 1-year progression/recovery period in all 4 groups of the rats. Silica exposure resulted in significant lung toxicity which was further exacerbated by tobacco smoke exposure in the rats. Cessation of cigarette smoke exposure did not result in reversal of the silica-induced lung toxicity despite exacerbation of the toxicity by tobacco smoke.
Project description:Using a macrophage cell line, we demonstrate the ability of amorphous silica particles to stimulate inflammatory protein secretion and induce cytotoxicity. Whole genome microarray analysis of early gene expression changes induced by 10nm and 500nm particles showed that the magnitude of change for the majority of genes correlated more tightly with particle surface area than either particle mass or number. Gene expression changes that were size-specific were also identified, however the overall biological processes represented by all gene expression changes were nearly identical, irrespective of particle diameter. Our results suggest that on an equivalent nominal surface area basis, common biological modes of action are expected for nano- and supranano-sized silica particles. Experiment Overall Design: RAW 264.7 mouse macrophage cells were treated with two sizes of amorphous silica particles at three doses each for 2 hours. Cells were exposed to 10nm silica at 5 (low), 20 (mid), or 50 (high) ug/ml or 500nm silica at 250 (low), 500 (mid), or 1000 (high) ug/ml in serum-free medium.
Project description:Occupational exposure to crystalline silica results in serious health effects, most notably, silicosis and cancer. A proper understanding of the mechanism(s) underlying the initiation and progression of silica-induced pulmonary toxicity is critical for the intervention and/or prevention of the adverse health effects associated with crystalline silica exposure. Rats were exposed to crystalline silica by inhalation at a concentration of 15 mg/m3, 6 hours/day, 5 days/week for 3, 6 or 12 weeks. At the end of each exposure time point, toxicity and global gene expression changes were determined in the lungs. In general, silica exposure resulted in pulmonary toxicity that was dependent on the duration of silica exposure. A significant and silica exposure time-dependent increase in lactate dehydrogenase activity and accumulation of alveolar macrophages and infiltrating neutrophils in the bronchoalveolar lavage fluid suggested crystalline silica-induced pulmonary toxicity in the rats. Histological changes indicative of pulmonary toxicity were detectable only in the lungs of rats that were exposed to silica for 6- or 12-weeks. Minimal, sub-acute pulmonary inflammation consisting mainly of macrophage accumulation and infiltration of neutrophils was seen in 2 out of 8 rats in the 6-week silica exposure group. Chronic active inflammation, type II pneumocyte hyperplasia, and fibrosis were detected following 12-weeks of silica exposure in all rat lungs. In addition, crystalline silica was visible in the lungs of the rats belonging to the 12-week exposure group. A significant increase in the number of neutrophils seen in the blood indicated silica-induced systemic inflammation in the rats. Microarray analysis of the global gene expression profiles of the rat lungs detected significant differential expression (FDR p <0.05 and fold change >1.5) of 38, 77 and 99 genes in the rats exposed to silica for 3-, 6- and 12-weeks, respectively, compared to the time-matched controls. Bioinformatics analysis of the differentially expressed genes identified significant enrichment of functions, networks and pathways related to inflammation, cancer, oxidative stress, fibrosis and tissue remodeling in the lungs of the silica exposed rats. Collectively, the results of our study provided insights into the molecular mechanisms underlying pulmonary toxicity following sub-chronic exposure to silica in rats.
Project description:Previous studies have shown that smoking induces oxidative stress and inflammation, known factors that coincide with the development and progression of silicosis. Nevertheless, the precise role of cigarette smoke exposure in silicosis and the underlying mechanisms are not clearly understood. Therefore, the objective of the present study was to determine the effect of smoking, if any, on silica-induced pulmonary response and the underlying mechanisms. Pulmonary toxicity and lung gene expression profiles were determined in male Fischer 344 rats exposed to air, crystalline silica, cigarette smoke or cigarette smoke plus crystalline silica. Silica exposure resulted in significant pulmonary toxicity which was further exacerbated by cigarette smoke exposure in the rats. Significant differences in the gene expression profiles were detected in the lungs of the rats exposed to cigarette smoke, silica or a combination of both compared with the control rats.
Project description:Exosomes are important mediators for cell-cell communication. In previous study, the clearance of exosomes were markedly delayed in systemic circulation of macrophage-depleted mice. To reveal the possible molecular regulation involved in exosome clearance, we performed exosomal proteomic analysis on MP-Exo from macrophage depleted mice and control ones.
Project description:Previous studies have shown that smoking induces oxidative stress and inflammation, known factors that coincide with the development and progression of lung toxicity in response to crystalline silica exposure. Nevertheless, the precise role of tobacco smoke exposure on the lung response to tobacco smoke exposure and the underlying mechanisms remain largely elusive. Therefore, the objective of the present study was to determine the effect of smoking, if any, on silica-induced pulmonary toxicity and the underlying molecular mechanisms. Pulmonary toxicity and lung gene expression profiles were determined in rats exposed to air, crystalline silica, tobacco smoke, or crystalline silica plus tobacco smoke. Silica exposure resulted in significant pulmonary toxicity which was further exacerbated by tobacco smoke exposure in the rats. Significant differences in the gene expression profiles were detected in the lungs of the rats exposed to tobacco smoke, silica or a combination of both compared with the air exposed control rats.
Project description:Using a macrophage cell line, we demonstrate the ability of amorphous silica particles to stimulate inflammatory protein secretion and induce cytotoxicity. Whole genome microarray analysis of early gene expression changes induced by 10nm and 500nm particles showed that the magnitude of change for the majority of genes correlated more tightly with particle surface area than either particle mass or number. Gene expression changes that were size-specific were also identified, however the overall biological processes represented by all gene expression changes were nearly identical, irrespective of particle diameter. Our results suggest that on an equivalent nominal surface area basis, common biological modes of action are expected for nano- and supranano-sized silica particles. Keywords: Dose-response study
Project description:Occupational exposure to crystalline silica results in serious health effects, most notably, silicosis and cancer. A proper understanding of the mechanism(s) underlying the initiation and progression of silica-induced pulmonary toxicity is critical for the intervention and/or prevention of the adverse health effects associated with crystalline silica exposure. Rats were exposed to crystalline silica by inhalation at a concentration of 15 mg/m3, 6 hours/day, 5 days/week for 3, 6 or 12 weeks. At the end of each exposure time point, toxicity and global gene expression changes were determined in the lungs. In general, silica exposure resulted in pulmonary toxicity that was dependent on the duration of silica exposure. A significant and silica exposure time-dependent increase in lactate dehydrogenase activity and accumulation of alveolar macrophages and infiltrating neutrophils in the bronchoalveolar lavage fluid suggested crystalline silica-induced pulmonary toxicity in the rats. Histological changes indicative of pulmonary toxicity were detectable only in the lungs of rats that were exposed to silica for 6- or 12-weeks. Minimal, sub-acute pulmonary inflammation consisting mainly of macrophage accumulation and infiltration of neutrophils was seen in 2 out of 8 rats in the 6-week silica exposure group. Chronic active inflammation, type II pneumocyte hyperplasia, and fibrosis were detected following 12-weeks of silica exposure in all rat lungs. In addition, crystalline silica was visible in the lungs of the rats belonging to the 12-week exposure group. A significant increase in the number of neutrophils seen in the blood indicated silica-induced systemic inflammation in the rats. Microarray analysis of the global gene expression profiles of the rat lungs detected significant differential expression (FDR p <0.05 and fold change >1.5) of 38, 77 and 99 genes in the rats exposed to silica for 3-, 6- and 12-weeks, respectively, compared to the time-matched controls. Bioinformatics analysis of the differentially expressed genes identified significant enrichment of functions, networks and pathways related to inflammation, cancer, oxidative stress, fibrosis and tissue remodeling in the lungs of the silica exposed rats. Collectively, the results of our study provided insights into the molecular mechanisms underlying pulmonary toxicity following sub-chronic exposure to silica in rats. 36 samples were analyzed in this experiment. 6 rats were exposed to crystalline silica by inhalation 15 mg/m3, 6 hours/day, 5 days, 3 weeks. 6 rats were exposed to crystalline silica by inhalation 15 mg/m3, 6 hours/day, 5 days, 6 weeks. 6 rats were exposed to crystalline silica by inhalation 15 mg/m3, 6 hours/day, 5 days, 12 weeks. 18 rats served as controls (6 for each 3 week, 6 week, and 12 week exposure) and were exposed to air during treatment times. Lung gene expression profiling was performed using RNA isolated from rat lung samples.