Explore PMI Science, where innovation meets harm reduction. Learn about our scientists, smoke-free research, and commitment to transparency in research.
PMI offers smoke-free alternatives with the potential to reduce the risk of harm for adult smokers who do not quit. Learn about harm reduction, the role of nicotine, and the regulation of smoke-free products.
Discover PMI's rigorous scientific approach to smoke-free products and product assessment. Dive into our research results, peer-reviewed publications, independent research, and expert reports.
PMI believes that offering a range of smoke-free alternatives is essential to ensure individual smokers are able to find a smoke-free product that they can fully switch to.
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Explore PMI Science, where innovation meets harm reduction. Learn about our scientists, smoke-free research, and commitment to transparency in research.
PMI offers smoke-free alternatives with the potential to reduce the risk of harm for adult smokers who do not quit. Learn about harm reduction, the role of nicotine, and the regulation of smoke-free products.
Discover PMI's rigorous scientific approach to smoke-free products and product assessment. Dive into our research results, peer-reviewed publications, independent research, and expert reports.
PMI believes that offering a range of smoke-free alternatives is essential to ensure individual smokers are able to find a smoke-free product that they can fully switch to.
Explore the latest insights and stay informed about upcoming events and conference presentations from PMI scientists.
Ask a question or send us feedback. We're happy to answer.
Cigarette smoke (CS) is known to cause cancer and other diseases, but little is known about the global molecular and cellular changes that occur prior to the appearance of clinically detectable symptoms. Using DNA microarrays covering 2031 cDNA probes, we investigated differential gene expression in tissues of the rat respiratory tract, i.e. respiratory nasal epithelium (RNE) and lungs of rats exposed either acutely (3 h) or subchronically (3 h/day, 5 days/week, 3 weeks) to mainstream CS with death either immediately or at 20 h after exposure. Differential gene expression was most evident in RNE of rats exposed once and was characterized by strong up-regulation of genes encoding oxidative stress-responsive and Phase II drug-metabolizing enzymes, such as haem oxygenase-1 and NAD(P)H:quinone oxidoreductase, which are all, at least in part, transcriptionally regulated by NF-E2-related factor 2 (Nrf2). After 3 weeks of exposure, the strength of expression of this class of genes was markedly reduced, pointing to an adaptive response. The generally lower response in the lungs of exposed rats is indicative of a deposition gradient of active smoke constituents from the upper to the lower respiratory tract. In sharp contrast to the CS-induced expression of oxidative stress and Phase II-responsive genes, induction of the genes encoding the Phase I drug-metabolizing enzymes cytochrome P450 (CYP)1A1 and aldehyde dehydrogenase-3 was not reduced after 3 weeks of exposure and was similarly high in lungs and RNE. Gene expression patterns in rats allowed to recover for 20 h showed that the CS-induced transcriptional changes observed immediately after exposure returned almost completely to normal, even after 3 weeks of repeated CS exposure. In general, these results demonstrate that CS induces a specific differential gene expression pattern in vivo, which may be instrumental in identifying the molecular mechanisms leading to the onset of inflammatory and/or morphological changes.
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Reduced Risk Products ("RRPs”) is the term we use to refer to products that present, are likely to present, or have the potential to present less risk of harm to smokers who switch to these products versus continuing smoking. PMI has a range of RRPs in various stages of development, scientific assessment and commercialization. All of our RRPs are smoke-free products that deliver nicotine with far lower quantities of harmful and potentially harmful constituents than found in cigarette smoke.