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Expression data for Male Fischer 344 rat exposed to nickel subsulfide

ABSTRACT: To provide insights into the mode of action for Ni3S2 lung carcinogenicity by examining gene expression changes in target cells after inhalation exposure. Gene expression changes were determined in micro-dissected lung broncho-alveolar cells from Fischer F344 rats following inhalation of Ni3S2 at 0.0, 0.04, 0.08, 0.15, and 0.60 mg/m3 (0.03, 0.06, 0.11, and 0.44 mg Ni/m3) for one and four weeks (6 hours per day, 5 days per week). Results: Broncho-alveolar lavage fluid evaluation and lung histopathology provided evidence of inflammation only at the two highest concentrations, which were similar to those tested in the 2-year bioassay. The number of statistically significant up- and down-regulated genes decreased markedly from one to four weeks of exposure, suggesting adaptation. Cell signal pathway enrichment at both time-points primarily reflected responses to toxicity, including inflammatory and proliferative signaling. While proliferative signaling was up-regulated at both time points, some inflammatory signaling reversed from down-regulation at 1 week to up-regulation at 4 weeks. Conclusions: These results support a mode of action for Ni3S2 carcinogenicity driven by chronic toxicity, inflammation and proliferation, leading to mis-replication, rather than by direct genotoxicity. Benchmark dose (BMD) analysis identified the lowest pathway transcriptional BMD exposure concentration as 0.026 mg Ni/m3, for apoptosis/survival signaling. When conducted on the basis of lung Ni concentration the lowest pathway BMD was 0.64 µg Ni/g lung, for immune/inflammatory signaling. Implications: These highly conservative BMDs could be used to derive a point of departure in a nonlinear risk assessment for Ni3S2 toxicity and carcinogenicity.

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE59593 | GEO | 2014/07/19

SECONDARY ACCESSION(S): PRJNA255670

REPOSITORIES: GEO

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Project description:To provide insights into the mode of action for Ni3S2 lung carcinogenicity by examining gene expression changes in target cells after inhalation exposure. Gene expression changes were determined in micro-dissected lung broncho-alveolar cells from Fischer F344 rats following inhalation of Ni3S2 at 0.0, 0.04, 0.08, 0.15, and 0.60 mg/m3 (0.03, 0.06, 0.11, and 0.44 mg Ni/m3) for one and four weeks (6 hours per day, 5 days per week). Results: Broncho-alveolar lavage fluid evaluation and lung histopathology provided evidence of inflammation only at the two highest concentrations, which were similar to those tested in the 2-year bioassay. The number of statistically significant up- and down-regulated genes decreased markedly from one to four weeks of exposure, suggesting adaptation. Cell signal pathway enrichment at both time-points primarily reflected responses to toxicity, including inflammatory and proliferative signaling. While proliferative signaling was up-regulated at both time points, some inflammatory signaling reversed from down-regulation at 1 week to up-regulation at 4 weeks. Conclusions: These results support a mode of action for Ni3S2 carcinogenicity driven by chronic toxicity, inflammation and proliferation, leading to mis-replication, rather than by direct genotoxicity. Benchmark dose (BMD) analysis identified the lowest pathway transcriptional BMD exposure concentration as 0.026 mg Ni/m3, for apoptosis/survival signaling. When conducted on the basis of lung Ni concentration the lowest pathway BMD was 0.64 M-BM-5g Ni/g lung, for immune/inflammatory signaling. Implications: These highly conservative BMDs could be used to derive a point of departure in a nonlinear risk assessment for Ni3S2 toxicity and carcinogenicity. Gene expression changes were determined in micro-dissected lung broncho-alveolar cells from Fischer F344 rats following inhalation of Ni3S2 at 0.0, 0.04, 0.08, 0.15, and 0.60 mg/m3 (0.03, 0.06, 0.11, and 0.44 mg Ni/m3) for one and four weeks (6 hours per day, 5 days per week).

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.

Project description:The present research aimed to investigate peripheral blood gene expression profiling as a minimally invasive surrogate approach to study silica-induced pulmonary toxicity. Rats were exposed to crystalline silica by inhalation (15 mg/m3, 6 hours/day, 5 days). Pulmonary damage and blood gene expression profiles were determined at various latency periods (0 - 16 weeks). Silica exposure resulted in pulmonary toxicity and this was evidenced by histological changes in the lungs and elevation of LDH activity, and total protein and albumin contents in the bronchoalveolar lavage fluid (BALF) of the rats. Microarray analysis of global gene expression profiles in the blood of the rats identified genes that were differentially expressed in response to silica exposure and toxicity. The number of significantly differentially expressed genes in the blood of silica exposed rats correlated with the severity of silica-induced pulmonary toxicity. Genes involved in biological functions such as inflammatory response, cancer, pulmonary damage, oxidative stress, energy metabolism, fibrosis, etc, were found differentially expressed in the blood of the silica exposed rats compared with the controls. Induction of pulmonary inflammation in the silica exposed rats, as suggested by differential expression of inflammatory response genes in the blood, was supported by significant increases in the number of macrophages and infiltrating neutrophils as well as the activity of pro-inflammatory chemokines M-bM-^@M-^S MCP1 and MIP2, observed in the BALF of the silica exposed rats. A silica-responsive blood gene expression signature developed using the gene expression data predicted with significant accuracy the exposure of rats to lower concentrations (1 and 2 mg/m3) of silica. Taken together our findings suggest the potential application of peripheral blood gene expression profiling as a minimally invasive and efficient surrogate approach to detect and study silica-induced pulmonary toxicity. 96 samples were analyzed in this experiment. The RNA from rat blood samples was isolated for gene expression studies. Rats (48) were exposed to crystalline silica by inhalation (15 mg/m3, 6 hours/day, 5 days) and air (24). Blood gene expression profiling was performed using rat blood samples, 8 each for silica exposed and 4 each for air exposed controls at various post-exposure time periods (0, 1, 2, 4, 8, and 16 weeks). A silica-responsive blood gene expression signature was developed using the gene expression data obtained from the 0 week post-exposure group and the control rats. The signature was tested for predicting silica exposure and resulting toxicity in the rats exposed to lower concentrations (1 and 2 mg/m3) of silica (8 rats per group) and air (8 rats).

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Expression data for Male Fischer 344 rat exposed to nickel subsulfide

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