Project description:Although smoking cessation shows clear cardiovascular risk benefits, lung-related disease risk remains higher in former smokers than in never smokers. To better understand the factors involved in this phenomenon, ApoE-/- mice were exposed to mainstream cigarette smoke (CS) or a smoking cessation-mimicking protocol for up to six months. Analysis of bronchoalveolar lavage fluid (BALF) from CS-exposed ApoE-/- mice revealed the presence of high concentrations of mediators involved in functions ranging from inflammation to cell proliferation and tissue remodeling. Gene expression levels for many analytes found elevated in BALF were also increased in lung tissue, indicating that the inflammatory response was the result of local tissue activation and the contribution of recruited inflammatory cells. Gene set enrichment analysis (GSEA) of expression data from lungs of CS-exposed mice showed activation of pathways involved in cell proliferation and tissue remodeling and a progressive deactivation upon smoke exposure cessation. Distinct activation patterns of inflammation, complement, and xenobiotic metabolism pathways were found in nasal epithelium and lung parenchyma during CS exposure and smoking cessation. Exposure of ApoE-/- mice to CS for up to 6 months induced adaptive and inflammatory responses in the respiratory tract that were partially deactivated upon cessation. We were able to reveal molecular perturbations accompanying these changes during CS exposure and cessation. Differential CS-mediated responses of pulmonary and nasal tissues reflect common mechanisms but also the varying degrees of epithelial functional specialization along the respiratory tract. These findings provide novel clues for the identification of markers of COPD progression.
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:RNA was obtained longitudinally from normal nasal epithelium of smokers who have quit smoking over 6 months period. Statistical analysis of gene expression data identified genes differentially expressed with short-term smoking cessation and categorized the kinetics of of these genes in different biological functions with different dynamics following smoking cessation.
Project description:Production of cephalosporin precursors with recombinant strains of Penicillium chrysogenum has improved the economics and reduced the environmental impact of industrial cephalosporin production. The engineered P. chrysogenum strains used in these processes express heterologous enzymes that convert the intermediate acyl-6-aminopenicillanic acid into different tailor-made compounds. Activation of the cephalosporin side-chain precursor to its corresponding CoA thioester is an essential step for its incorporation into the β-lactam backbone. To identify the acyl-CoA ligase involved in activation of adipic acid, a frequently used cephalosporin side-chain precursor, we searched the genome of P.chrysogenum for putative structural genes encoding acyl-CoA ligases. Chemostat-based transcriptome analysis was then used to identify the one presenting the highest expression level when cells were grown in the presence of adipic acid. Deletion of the gene renamed aclA, led to a 32% decreased specific rate of adipic acid consumption and a three-fold reduction of adipoyl-6-aminopenicillanic acid levels in chemostat cultures of P. chrysogenum, but did not affect penicillin production. After cloning the gene and overexpressing it in Escherichia coli, its purified protein product was shown to have adipoyl-CoA ligase, but no phenylacetyl-CoA ligtase activity. Finally, by fusing the gene to a sequence encoding cyan fluorescent protein, the resulting fusion protein localized to microbodies, which indicates that activation of the side-chain precursor adipic acid takes place in this compartment, where also the subsequent acyltransferase step takes place. Identification and functional characterization of this adipoyl-CoA ligtase gene may aid in developing future metabolic engineering strategies for improving the production of different cephalosporins.
Project description:Background: Epigenetics is involved in various human diseases. Smoking is one of the most common environmental factors causing epigenetic changes. The DNA methylation changes and mechanisms after quitting smoking have not yet been defined. The present study examined the changes in DNA methylation level before and after short-term smoking cessation and explored the potential mechanism. Methods: Whole blood and clinical data were collected in 8 patients before and after short-term smoking cessation, DNA methylation was assessed, and differentially methylated sites were analyzed, followed by a comprehensive analysis of the differentially methylated sites with clinical data. GO/KEGG enrichment and protein-protein interaction (PPI) network identified the hub genes. The differentially methylated sites were detected by GEO2R between former smoking and current smoking in GSE50660 from the GEO database. Then, a Venn analysis was carried out using the differentially methylated sites. GO/KEGG enrichment analysis was performed on the genes corresponding to the common DNA methylation sites, the PPI network was constructed, and hub genes were predicted. The enriched genes associated with the cell cycle were selected, and the gene expression was analyzed in pan-cancer based on the TCGA database. Results: Most of the DNA methylation levels were decreased after short-term smoking cessation; a total of 694 hypermethylated CPG sites and 3184 hypomethylated CPG sites were identified. The DNA methylation levels altered according to the clinical data (body weight, expiratory, and tobacco dependence score). Enrichment analysis, construction of PPI network, and pan-cancer analysis suggested that smoking cessation may be involved in various biological processes. Conclusions: Smoking cessation leads to epigenetic changes, mainly observed in the decline of most DNA methylation levels. Bioinformatics further identified the biologically relevant changes after short-term smoking cessation.
Project description:Cigarette smoking is a major risk factor for the development and progression of cardiovascular disease (CVD) and chronic obstructive pulmonary disease (COPD), so modified risk tobacco products (MRTPs) are being developed to reduce smoking-related health risks. The present study investigated the hallmarks of COPD and CVD over an 8-month period in apolipoprotein E-deficient mice exposed to conventional cigarette smoke (CS) or to an aerosol from a candidate MRTP, the tobacco heating system (THS2.2). In addition to chronic exposure, cessation or switching to THS2.2 after 2 months of CS was investigated. In a systems toxicology approach, exposure effects were investigated using physiology and histology combined with transcriptomics, lipidomics, and proteomics. CS induced nasal epithelial hyperplasia and metaplasia, lung inflammation, and emphysematous changes (impaired pulmonary function and alveolar damage). Atherogenic effects of CS exposure included altered lipid profiles and increased aortic plaque formation. Exposure to THS2.2 aerosol (nicotine concentration matched to CS: 29.9 mg/m3) did not induce lung inflammation or emphysema, nor did it consistently change the lipid profile or enhance the plaque area. Cessation and switching reversed the inflammatory responses and led to no further progression of initial emphysematous changes or the aortic plaque area. Biological processes, including senescence, inflammation, and proliferation, were significantly impacted in CS, but not THS2.2-exposed tissues. Cessation or switching reduced these perturbations to become nearly indistinguishable from sham exposure. In conclusion, this mouse model indicated that cessation or switching to THS2.2 retarded the progression of atherosclerotic and emphysematous changes, while THS2.2 alone had no adverse effects.