Ozone and various oxidative products within air pollution are major contributors to oxidative stress to airway epithelial cells. We have previously described relative ozone resistance in primary vs cultured airway epithelial cells and have demonstrated changes in thioredoxin (Trx) production in response to acute and chronic ozone exposure that may account for the development of this resistance. The mechanisms of ozone resistance however have not been well delineated. During oxidative stress H2O2 can be produced and cause cell damage and death. Retinol is known to be an antioxidant capable of helping cells resist oxidative stress. The mechanism of this resistance however is again unclear. Previously described in our laboratory was the upregulation of Trx gene expression by retinol. We pursued a possible connection between H2O2 induced oxidative stress, retinol, and Trx. Primary monkey tracheal epithelial cells were cultured with or without retinol for six days. Both groups were then subjected to H2O2 for 12 hours in the absence of retinol. As measured by Alamar Blue assay, the retinol pretreated group had a higher percent viability than the non treated group. Western blot utilizing an antibody against the C terminal 15 amino acid sequence of the human Trx protein demonstrated higher Trx levels in the retinol treated group. Primary monkey tracheal epithelial cells were treated with H2O2 in the presence of Trx protein or BSA at 0.5 mcg/ml. After H2O2 treatment the Trx treated group had a higher percent viability than the untreated group. The cDNA of monkey Trx gene was constructed in a mammalian expression vector, pCDNA3 and oriented in both sense and antisense directions. Three constructs (sense, antisense and vector only) were transformed into a human tracheal epithelial cell line (HBE). At 0.01% H2O2 the sense construct had the highest percent viability, the vector only had intermediate and the antisense the lowest. These results indicate that although retinol has a direct antioxidant effect, it also has an indirect effect that protects cells from oxidant damage. Our findings indicate that retinol upregulates the expression of the Trx gene and in turn Trx either directly or indirectly protects cells from oxidative stress.
|Original language||English (US)|
|Journal||Journal of Investigative Medicine|
|State||Published - 1996|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)