EFFECTS OF NIACINAMIDE ON KERATINOCYTE VIABILITY, PROLIFERATION, AND PROTECTION FROM OXIDATIVE STRESS

Sammanfattning

Based on clinical studies, niacinamide (NIA) is known for its ability to enhance the skin barrier and protect the skin from oxidative stress. Still, several of the molecular mechanisms underlying the beneficial effects of NIA are not fully elucidated. This study aimed to investigate cell viability and expression of genes related to proliferation, differentiation, and lipid synthesis in the human keratinocyte cell line (HaCaT) and the Human epidermal keratinocyte, adult (HEKa). In addition, the protective effect of NIA against oxidative stress was investigated using two oxidative stress models. The method used to investigate the viability of the cells was 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, digital holographic microscopy (DHM) to analyse proliferation visually, real time quantitative polymerase chain reaction to analyse the genes, oxidative stress model 1, utilizing live/dead assay, and lastly oxidative stress model 2 encompassing different concentrations of hydrogen peroxide and analysing it using MTT. Based on the results, the viability of cells treated with 10 mM NIA showed an increase in confluency and cells/ cm2. Of the tested genes, the most notable were filaggrin, involucrin, NIPAL4, and GPAT3, which were downregulated genes, and loricrin, CYP4F22, ELOVL4, and ALOXE12B, which were upregulated genes. The oxidative stress model 1, yielded no usable results and requires further study and optimization. The oxidative model 2, showed that cells pre-treated with 10 mM NIA can tolerate higher concentrations of oxidative stress when compared to HEKa cells not treated with any NIA. In conclusion, this study suggests that NIA increases proliferation, provides some insight into which genes were up- and downregulated, explores a new oxidative stress model, and offers new insights into oxidative stress and NIA, but nothing definitive can be concluded.