LOS ANGELES (Dispatches) -- Thirdhand smoke can damage epithelial cells in the respiratory system by stressing cells and causing them to fight for survival, a research team led by scientists at the University of California, Riverside, has found.
Thirdhand smoke, or THS, results when exhaled smoke and smoke emanating from the tip of burning cigarettes settles on surfaces such as clothing, hair, furniture, and cars. Not strictly smoke, THS refers to the residues left behind by smoking.
The researchers obtained nasal scrapes from four healthy nonsmokers who had been exposed to THS for three hours in a laboratory setting at UC San Francisco. The UCR researchers then worked to get good quality RNA from the scrapes -- necessary to examine gene expression changes. RNA sequencing identified genes that were over- or under-expressed. They found 382 genes were significantly over-expressed; seven other genes were under-expressed. They then identified pathways affected by these genes.
Because gene expression in the nasal epithelium is similar to the bronchial epithelium, the researchers note that their data is relevant to cells deeper in the respiratory system. In the samples they studied, the researchers also found that brief THS exposure affected mitochondrial activity. Mitochondria are organelles that serve as the cell's powerhouses. If left unchecked, the observed effects would lead to cell death.