Induction of Metallothionein Expression After Exposure to Conventional Cigarette Smoke but Not Electronic Cigarette (ECIG)-Generated Aerosol in Caenorhabditis elegans

The use of the model organism Caenorhabditis elegans in the investigation of the adverse effects of electronic cigarettes

The use of tobacco products is one of the most preventable risk factors for mortality from a variety of diseases, including cardiovascular, infectious, respiratory, and neoplastic conditions. The use of electronic cigarettes (ECIGs), also known as electronic nicotine delivery devices, has increased significantly in recent years. Nicotine, propylene glycol, and / or glycerine, water, alcohol, flavorings, and other substances are among the many chemicals found in ECIGs that are vaporized and inhaled. A review of the existing literature shows that research dedicated to ECIGs is a rapidly developing and growing field of study. The rationale for the use of ECIGs is that they represent a safer alternative to traditional tobacco products. However, vaping safety profiles are still under development, as this is a relatively recent phenomenon. Various model organisms can be employed to examine the cellular processes that may be altered by exposure to the electronic liquids utilized for vaping. For example, the translucent multicellular eukaryote Caenorhabditis elegans is widely used as a model organism to explain a broad range of biological processes, including aging, stress response, development, and many others. Due to its short lifespan and easy use, C. elegans is an ideal model organism for studying chronic exposure to drugs and environmental toxicology. This review presents a summary of the most recent findings on the impact of electronic cigarettes on the physiological health of this nematode. Preliminary observations made in C. elegans can provide insight into the consequences of exposure to fundamental cellular physiology, which can then be used for future research in humans and mammalian models.

Differential gene expression of 3D primary human airway cultures exposed to cigarette smoke and electronic nicotine delivery system (ENDS) preparations

BACKGROUND

Acute exposure to cigarette smoke alters gene expression in several biological pathways such as apoptosis, immune response, tumorigenesis and stress response, among others. However, the effects of electronic nicotine delivery systems (ENDS) on early changes in gene expression is relatively unknown. The objective of this study was to evaluate the early toxicogenomic changes using a fully-differentiated primary normal human bronchial epithelial (NHBE) culture model after an acute exposure to cigarette and ENDS preparations.

RESULTS

RNA sequencing and pathway enrichment analysis identified time and dose dependent changes in gene expression and several canonical pathways when exposed to cigarette preparations compared to vehicle control, including oxidative stress, xenobiotic metabolism, SPINK1 general cancer pathways and mucociliary clearance. No changes were observed with ENDS preparations containing up to 28 µg/mL nicotine. Full model hierarchical clustering revealed that ENDS preparations were similar to vehicle control.

CONCLUSION

This study revealed that while an acute exposure to cigarette preparations significantly and differentially regulated many genes and canonical pathways, ENDS preparations containing the same concentration of nicotine had very little effect on gene expression in fully-differentiated primary NHBE cultures.

Trans-generational effects of copper on nerve damage in Caenorhabditis elegans

The potential toxicity of copper has received great attention for a long time, however, trans-generational effects of copper have not been extensively investigated. Caenorhabditis elegans (C. elegans) was used to evaluate the trans-generational toxicities of copper several physiological endpoints: growth, head thrashes and body bends and degree of neuronal damage. Copper significantly inhibited growth, body bends, head thrashes and caused degeneration of dopaminergic neurons in a concentration-dependent manner in parental worms. Further we found oxidative damage was to underlying the onset of neuron degeneration. In our study copper promoted ROS accumulation, and led to an increased expression of the oxidative stress response-related genes sod-3 and a decreased expression of metal detoxification genes mtl-1 and mtl-2. Moreover, copper increased the fluorescence intensity of the transgenic strain that encodes the antioxidant enzyme SOD-3. Gradually decline in copper-induced impairments were observed in the filial generations without exposure. No growth impairment was shown in F3, the trend of head thrashes recovery gradually appeared in F2 and no growth impairment was shown in F3, the body bends impairment caused by the parental copper exposure was recovery until F4 and no growth impairment was shown in F5. Besides, dopamine neurons revealed damage related to neurobehavioral endpoints, with hereditary effects in the progeny together. In addition, sequencing results suggested that copper exposure could cause epigenetic changes. QRT-PCR results showed that differentially expressed genes can also be passed on to offspring.

A Comparison of Flavorless Electronic Cigarette-Generated Aerosol and Conventional Cigarette Smoke on the Survival and Growth of Common Oral Commensal Streptococci

Background: The use of electronic cigarettes (ECIG) has become very common. Consequently, critical analysis of the biological effects of ECIG aerosol deserves attention. Flavorless ECIG aerosol is known to comprise fewer harmful constituents than cigarette smoke. Therefore, we hypothesize that aerosol has less immediate effect on the viability of oral commensal streptococci than smoke. Methods: Survival and growth of four strains of commensal streptococci were measured after exposure to flavorless ECIG aerosol ± nicotine and smoke. Peristaltic pumps were used to transport aerosol or smoke into chambers containing recently seeded colony-forming units (CFUs) of the oral commensal streptococci on agar plates. Bacterial survival and growth, based on colony counts and sizes, were determined 24 h post-exposure. Additionally, aerosol or smoke were delivered into chambers containing pre-adhered streptococci to plastic coverslips and biofilm formation was determined 24 h post-exposure via scanning electron microscopy. Results: The results suggest that flavorless aerosol ± nicotine has a modest effect on bacterial growth both as colonies on agar and as biofilms. In contrast, smoke dramatically decreased bacterial survival and growth in all parameters measured. Conclusion: Unlike cigarette smoke, flavorless ECIG aerosol has only a small effect on the survival and growth of oral commensal streptococci.