Titanium Dioxide and Zinc Oxide Nanoparticles in Sunscreen: Potential Impact on Cytokine Expression in Human Skin Pre- and Post-UVB Exposure

Abstract

Background Nanoparticles have been widely used in sunscreen products to prevent UVB-mediated skin damage. Research has shown that ZnO and TiO2 nanoparticles effectively scatter, reflect, and absorb light in the UV range. However, little is known regarding the impact of nanoparticle and UVB exposure on cytokine expression. This study investigates the influence of ZnO and TiO2 nanoparticles on the expression of pro- and anti-inflammatory cytokines in human skin exposed to UVB radiation. Methods De-identified, discarded skin from three abdominoplasty surgeries were exposed to UVB with or without the application of ZnO or TiO2 nanoparticles. Samples were analyzed using a BioRad Bio-Plex Pro Human Cytokine 27-plex Assay to determine cytokine levels of various pro- and anti-inflammatory cytokines. Results UVB exposure or application of ZnO or TiO2 nanoparticles had very little effect on cytokine levels compared to the no treatment control when evaluated 24 hrs after exposure. However, application of TiO2 following UVB exposure resulted in increased cytokine levels for nearly all the cytokines evaluated. This effect was absent when a combination of ZnO and TiO2 nanoparticles were applied. Interestingly, pre-, and post-UVB application of ZnO or a combination of ZnO and TiO2 nanoparticles decreased IL-6 levels or IL-6 and IL-8 levels, respectively. Discussion These results suggest a potential for nanoparticle sunscreen to enhance or reduce the inflammatory response in skin depending on conditions of UVB exposure and the nanoparticle composition and how it is applied. Further studies to evaluate the safety and efficacy of using nanoparticle sunscreens are warranted.