Project description:We previously put forward a multi-layer systems toxicology framework for in vitro assessment of e-liquids that is meant to complement the battery of classical assays for genotoxicity testing. The framework started with the first layer to screen e-liquids for their potential toxicity, followed by the second layer to investigate the toxicity-related mechanism of a selected e-liquid(s), and finally the third layer to evaluate the toxicity-related mechanism of the corresponding aerosol(s). In this work, we leveraged this framework to assess the biological impact of an e-liquid MESH™ “Classic Tobacco” and its aerosol in comparison with the impact of 3R4F reference cigarettes. In the first layer, we evaluated the cytotoxicity profile of the MESH Classic Tobacco liquid (containing humectants, nicotine, and flavors) and its Base liquid (containing humectant and nicotine only) in comparison with total particulate matter (TPM) of 3R4F cigarette smoke (CS). In the second layer, we explored changes in specific markers using high content screening assays to identify potential toxicity-related mechanisms of the MESH Classic Tobacco and Base liquids beyond cell viability compared with the 3R4F TPM-induced effects. In the third layer, we compared the biological impact of exposure to the MESH Classic Tobacco aerosol with CS using human organotypic buccal and small airway epithelial cultures. The results showed that the cytotoxicity profile of the MESH Classic Tobacco liquid was similar to the Base liquid but lower than the toxicity of 3R4F TPM at comparable nicotine concentrations. When compared with CS exposure, MESH Classic Tobacco aerosol exposure did not cause tissue damage and elicited lower changes in the global mRNA, global microRNA, and protein markers. The global mRNA changes following Classic Tobacco aerosol exposure indicated perturbations in processes related to cell fate, cell stress, and inflammatory response that were less than 20% of the perturbations following CS exposure. In the context of tobacco-harm reduction strategy, the framework is suitable to assess the potential reduced impact of EC aerosol relative to CS.

Project description:Inflammatory responses triggered by either microbial or endogenous stimuli rely on a complex transcriptional program that involves the differential expression of hundreds of genes. Jmjd3, a JmjC family histone demethylase (HDM), is quickly induced by the transcription factor NF-kB in response to inflammatory stimuli. Jmjd3 erases a histone mark associated with transcriptional repression and silencing, trimethylated lysine 27 in histone H3 (H3K27me3). Thus, Jmjd3-mediated demethylation of H3K27me3 links inflammation to the control of a histone modification involved in lineage determination, differentiation and tissue homeostasis. However, the specific contribution of Jmjd3 induction to innate immunity and inflammation remains unknown. Here we combined genome-wide mapping and gene knockout studies to investigate this issue. Chromatin immunoprecipitation (ChIP) coupled to ultra high-throughput sequencing (ChIP-Seq) in LPS-stimulated primary mouse macrophages demonstrated that Jmid3 is recruited to a large number of genomic targets with a strong preference for active transcription start sites (TSS). Virtually all Jmjd3-bound TSSs were characterized by high levels of H3K4me3, a marker of gene activity, and high levels of RNA polymerase II (Pol_II). Inducible genes showing a strong increase in H3K4me3 and Pol_II recruitment after endotoxin treatment (including those encoding several cytokines, chemokines and antiviral proteins) were in most cases Jmjd3-associated. In Jmjd3-knockout macrophages, initial RNA_Pol II recruitment and activation of Jmjd3 target genes was unaffected, but RNA_Pol II was prematurely released, thus resulting in non-sustained responses. Importantly, most Jmjd3 target genes were not associated with detectable levels of H3K27me3, and transcriptional effects of Jmjd3 absence in the window of time analyzed here were uncoupled from measurable effects on this histone mark. Our data indicate that Jmjd3 is the effector of an NF-kB-controlled feed-forward transcriptional loop pervasively sustaining inflammatory transcriptional responses in a manner that is independent of H3K27me3 demethylation, and suggest the possible use of anti-Jmjd3 drugs to dampen pathologic inflammation. Keywords: Epigenetics Genome wide maps of histone demethylase jmjd3, the histone marks H3K4me3 and H3K27me3, and RNA-Polymerase II induction in mouse bone marrow-derived macrophages of two types: (a) untreated and (b) stimulated with lipopolysaccharide and interferon gamma to produce an inflammatory response.

Dataset Information

ATAC-seq data of Amphimedon queenslandica (Demosponge species) through eight developmental stages, from white stage (cleavage) to adult

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