With the increase in the production of engineered nanomaterials, researchers are discovering that there is a direct impact of these nanomaterials on the cell membrane. The cell membrane contains many different types of lipids and proteins responsible for numerous cell functions. The assembly of cholesterols and sphingolipids within the membrane forms microdomain structures known as lipid rafts. Lipid rafts embed many receptors that are involved in regulating cytokine production. Studies have shown that engineered nanomaterials can erode the membrane and create holes. We hypothesized that nanoparticles can interfere with cellular signaling by inhibiting the assembly of receptors on the lipid rafts. Using alveolar epithelial cells containing an Interleukin-8 promoter Luciferase construct, we were able to evaluate the ability of charged nanoparticles to alter cytokine gene expression elicited by a secondary stimulus. We exposed cells to charged nanoparticles, followed with stimulation of the IL-8 promoter with the proinflammatory cytokine tumor necrosis factor-α (TNF-α). We then used endocytic inhibitors and cholesterol depletors to determine if the nanoparticles rely on endocytosis and membrane cholesterol to alter the TNF-α stimulated IL-8 promoter. We found that cationic nanoparticles were able to reduce the IL-8 promoter activity despite exposure to the endocytic inhibitors. When membrane cholesterol was removed from the cells, all the effects of the nanoparticles disappeared. Furthermore, cationic nanoparticles disrupt signaling by inducing receptor aggregation and reducing NF-κB translocation. These effects were cholesterol dependent. Our studies demonstrated that not only can nanoparticles induce cytotoxicity, they can have the potential to interfere with cellular signaling. Since particles are now being considered for applications in both consumer and medical products, it is important to evaluate whether the particles may possess these biological effects.
|Advisor:||Finkelstein, Jacob N.|
|Commitee:||Dean, David, McGrath, James L., Oberdorster, Gunter|
|School:||University of Rochester|
|Department:||School of Medicine and Dentistry|
|School Location:||United States -- New York|
|Source:||DAI-B 74/07(E), Dissertation Abstracts International|
|Subjects:||Cellular biology, Nanoscience, Nanotechnology|
|Keywords:||Cellular signaling, Cholesterol, Cytokine, Interleukin-8, Lipid microdomains, Nanoparticles, Tnfr1|
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