Project description:Formaldehyde (FA), an endogenous cellular aldehyde, is a rat nasal carcinogen. In this study, concentration- and exposure-duration transitions in FA mode of action (MOA) were examined with pharmacokinetic (PK) modeling for tissue formaldehyde acetal (FAcetal) and glutathione (GSH) and with histopathology and gene expression studies for tissue responses in nasal epithelium from rats exposed to 0, 0.7, 2, 6, 10 or 15 ppm FA 6 hr/day for 1, 4 or 13 weeks. The study had two goals. The first goal was to develop a basic PK model to estimate various forms of tissue formaldehyde and tissue glutathione (GSH). The second goal was to compare histopathology and gene expression changes in nasal tissues caused by inhalation of FA with changes in tissue FAcetal and free GSH calculated from the PK model. Patterns of gene expression varied with concentration and with duration. At 0.7 and 2 ppm, sensitive response genes (SRGs) - associated with cellular stress, thiol transport/reduction, inflammation, and cell proliferation - were similarly upregulated at all exposure durations. At 6 ppm and greater, gene expression changes showed enrichment of pathways involved in cell cycle, DNA repair, and apoptosis processes. ERBB, EGFR, WNT, TGF-β, Hedgehog, and Notch signaling were also enriched in differentially expressed genes. Benchmark doses (BMDs) for genes in significantly enriched pathways were lower at 13 weeks than at 1 or 4-week. The transcriptional and histological changes corresponded to PK model-predicted changes in free GSH at 0.7 and 2 ppm and in FAcetal at 6 ppm. DNA-replication stress, enhanced proliferation, metaplasia, and stem cell-niche activation appear to be associated with FA carcinogenesis at 6 ppm and above. Dose dependencies in MOA, the presence of high physiological FAcetal, and non-linear FAcetal/GSH tissue kinetics indicate that FA concentrations below 150 ppb (and probably any concentrations below irritant levels, i.e., ~ 1 ppm) would not increase cancer risks of inhaled FA in the nose or any other tissue. Closer examination of dose response relationships for endogenous compound toxicity could help guide biologically relevant approaches for chemical risk assessment.

Project description:Formaldehyde (FA), an endogenous cellular aldehyde, is a rat nasal carcinogen. In this study, concentration- and exposure-duration transitions in FA mode of action (MOA) were examined with pharmacokinetic (PK) modeling for tissue formaldehyde acetal (FAcetal) and glutathione (GSH) and with histopathology and gene expression studies for tissue responses in nasal epithelium from rats exposed to 0, 0.7, 2, 6, 10 or 15 ppm FA 6 hr/day for 1, 4 or 13 weeks. The study had two goals. The first goal was to develop a basic PK model to estimate various forms of tissue formaldehyde and tissue glutathione (GSH). The second goal was to compare histopathology and gene expression changes in nasal tissues caused by inhalation of FA with changes in tissue FAcetal and free GSH calculated from the PK model. Patterns of gene expression varied with concentration and with duration. At 0.7 and 2 ppm, sensitive response genes (SRGs) - associated with cellular stress, thiol transport/reduction, inflammation, and cell proliferation - were similarly upregulated at all exposure durations. At 6 ppm and greater, gene expression changes showed enrichment of pathways involved in cell cycle, DNA repair, and apoptosis processes. ERBB, EGFR, WNT, TGF-β, Hedgehog, and Notch signaling were also enriched in differentially expressed genes. Benchmark doses (BMDs) for genes in significantly enriched pathways were lower at 13 weeks than at 1 or 4-week. The transcriptional and histological changes corresponded to PK model-predicted changes in free GSH at 0.7 and 2 ppm and in FAcetal at 6 ppm. DNA-replication stress, enhanced proliferation, metaplasia, and stem cell-niche activation appear to be associated with FA carcinogenesis at 6 ppm and above. Dose dependencies in MOA, the presence of high physiological FAcetal, and non-linear FAcetal/GSH tissue kinetics indicate that FA concentrations below 150 ppb (and probably any concentrations below irritant levels, i.e., ~ 1 ppm) would not increase cancer risks of inhaled FA in the nose or any other tissue. Closer examination of dose response relationships for endogenous compound toxicity could help guide biologically relevant approaches for chemical risk assessment. Eight week old male F344/CrlBR rats were exposed to formaldehyde through whole body inhalation. Whole-body exposures were performed at doses of 0, 0.7, 2, 6, 10, and 15 ppm (6 hours per day, 5 days per week). Inhalation animals were sacrified at 1, 4, and 13 weeks following initiation of exposure. Following sacrifice, tissue from the Level II region of the nose was dissected and digested with a mixture of proteases to remove the epithelial cells. The epithelial cells acquired from this section of the nose consisted primarily of transitional epithelium with some respiratory epithelium. Gene expression microarray analysis was performed on the epithelial cells.

Project description:Purpose: To identify how axitinib stabilized the rabbit's engineered cartilage through the niche Methods: Rabbit's engineered cartilage was encapsulated in the PCL/collagen nanofibrous membrane containing no axitinib (0%-Axitinib group) or 3% axitinib (3%-Axitinib group) and implanted into nude mice. After 12 weeks of implantation, samples from the 0%-Axitinib group and 3%-Axitinib group were harvested, with the murine tissues entangled. Transcriptional profiles were generated by deep sequencing, in triplicate, using an Illumina HiSeqTM2000 machine, and filtered using Fastp software. The trimmed reads were mapped to the mouse genome (mm10, genome.UCSC.edu) using the STAR software to identify the transcriptional information in the niche of engineered cartilage. Then, the DESeq2 “counts” function of the R package was used to normalize gene expression levels based on the number of total reads of each sample. Differentially expressed genes between the 0%-Axitinib group and 3%-Axitinib group were identified as meeting the criteria of fold change ≥ 1.5 and P-value＜0.05. Lastly, we used Metascape (http://metascape.org) for gene ontology analysis. Results: Using an optimized data analysis workflow, we mapped about 20 to 30 million sequence reads per sample to the mouse genome (build mm10) and identified 20318 transcripts in the 0%-Axitinib and 3%-Axitinib groups. 837 genes were differentially expressed by more than 1.5-fold, p-value <0.05, with 313 genes downregulated and 524 genes upregulated in the 3%-Axitinib group. Gene ontology (GO) analysis revealed that the genes downregulated in the 3%-Axitinib group were mainly enriched in endothelial development, angiogenesis, and immune response. Genes upregulated in the 3%-Axitinib group were mainly enriched in response to hypoxia, Hif-1 signaling pathway, cartilage differentiation and development, and muscle structure development. Altered expression of 15 genes was further illustrated by heatmap, demonstrating the inhibited angiogenesis and improved chondrogenesis. Especially, Timp1, as a response to hypoxia, was remarkably upregulated, which also in turn inhibited the activity of matrix metalloproteinases (MMPs) and played an important role in preventing ossification. Conclusion: In this study, we proposed the first detailed transcriptional analysis of the effects of the sustainable and localized release of axitinib on the subcutaneous niche of engineered cartilage. The sustainable and localized release of axitinib created a relatively avascular, hypoxia, and low immune response niche in the 3%-Axitinib group. In this niche, Timp1 was remarkably upregulated, which inhibited the activity of MMPs and prevented endochondral ossification.

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An exploratory study of PRecision dOsing of moLecular targeted agents based On therapeutic drug monitoriNG

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