204 JOURNAL OF COSMETIC SCIENCE UVB-induced Sunburn cell formation: Excised portions (8mm) were taken from living skin equivalents (Organogenesis) and cultured over transwell membrane plates. These excised portions were pretreated topically with either distilled water, or salicylic acid (200ug/ml). After the post- incubation, these excised portions were UVB irradiated at 0, I00and 150mJ/cm2. Following a 24hour post-incubation, these skin equivalents were fixed in formalin and stored at -4C. These samples were then sent to Paragon Biotech for H&E staining. Sections were then evaluated using a microscope at 400X magnification. A section was selected from each sample and counts of sunburn cells were made. Sunburn cell levels were detennined by%, (number of sunburn cells in a representative field divided by total number of cells in a representative field). DNA repair ofUVB-induced thymine dimers (TT-dimers): Excised portions (8mm) were taken from living skin equivalents (Organogenesis) and cultured over transwell membrane plates. Excised portions (8mm) were taken from living skin equivalents (Organogenesis) and cultured over transwell membrane plates. These excised portions were pre-treated topically with salicylic acid 200ug/ml (in sterile H20) for 6 hours. After the post- incubation, these excised portions were UVB irradiated at 0, I 00, and 150 mJ/cm2. Following a 24 hour post-incubation, these LSEs were fixed in formalin and stored at -4C. These samples were then sent to Paragon Biotech for immunostaining ofTI- dimers. Sections were then evaluated using a microscope at 400X magnification. Representative sections were selected from each sample and counts of cells at 400X magnification expressing TT-dimer staining were calculated. The TT-dimer levels of each section were expressed as number of cells expressing the immunofluorescent TI-dimer antibody tagged stainin that section. Conclusions Salicylic acid was found to have anti-inflammatory effect on normal human epidermal keratinocytes. We observed a significant inhibition ofUVB induced NF-kb.activation in keratinocytes. In addition, salicylic acid was found to significantly increase the induction ofHsp70 protein in keratinocytes. Salicylic acid was also found to increase keratinocyte cell viability to UVB toxicity, as well as increase DNA repair function of normal human dermal fibroblasts using the host cell reactivation assay. In living skin equivalents, salicylic acid significantly reduce UVB-induced sunburn cell formation and increase DNA repair (removal rate of DNA damage). These results suggest that salicylic acid which has previously been described to have anti-inflammatory properties as well as induce Hsp70 in mammalian cells may have benefits if used topically on the skin. Salicylic acid can act as an anti-inflammatory in the skin as well as increase DNA repair function in skin and may be a valuable topical agent to protect skin from sun damage. References: Al Mahroos M, Yarr M, Phillips TJ, Bhawan J, Gilchrest BA. (2002). Effect of sunscreen application on UV-induced thymine dimers. Arch Dermatol 138(11): 1480-1485 Beg AA and Baltimore D. ( 1996). An essential role for NF-kB in preventing TNF alpha induced cell death. Science. 274: 782- 784 Durbeef, B, Eriksson, LA. (2003 ). On the formation of cyclobutane pyrimidime dimers in UV-irradiated DNA: Why are thymines more reactive. Photochem Photobiol 78(2): 159-167 Wu, K. (2003) Aspirin and other cyclooxygenase inhibitors: new therapeutic insights. Semin Vase Med. 3(2):107-12. Wu, K. (2003) Control ofCOX2 and iNOS gene expressions by aspirin and salicylate. Thromb Res. 110(5-6):273-6. Kwon, K., Chae H.(2003). Sodium salicylate inhibits expression ofCOX2 through suppression of ERK and subsequent NF- kappaB activation in rat ventricular cardiomyocytes. Arch Phann Res. 26(7):545-53. Costanzo A, Moretti F, Burgio VL, Bravi C, Guido F, Levrero M, Puri PL. (2003) Endothelial activation by angiotensin II through NFkappaB and p38 pathways: Involvement of NFkappaB-inducible kinase (NIK), free oxygen radicals, and selective inhibition by aspirin. J Cell Physiol. 195(3):402-10. Ishihara K, Horiguchi K, Yamagishi N, Hatayama T (2003). Identification of sodium salicylate as an hsp inducer using a simple screening system for stress response modulators in mammalian cells. Eur J Biochem. 270(16):3461-8. Jurivich DA, Sistonen L, Kroes RA, Morimoto (1992). Effect of sodium salicylate on the human heat shock response. Science. 255(5049): 1243-5.