Increased Lipid Accumulation under Hypoxia in SZ95 Human Sebocytes

BACKGROUND: Excessive sebum is produced by specialized cells called sebocytes and is considered a cause or consequence of acne, sebaceous cysts, hyperplasia, and sebaceous adenoma. OBJECTIVE: To report changes in lipid accumulation in human sebocytes under hypoxia, which occurs under conditions of seborrhea. METHODS: Sebocytes from the immortalized human gland cell line SZ95 were cultured under conditions of hypoxia for 48 h; lipid formation was confirmed by Nile red and Oil Red O staining. To investigate whether HIF-1α plays a role in lipid accumulation, SZ95 cells transfected or treated with dimethyloxalylglycine (DMOG) were assessed by Nile red. For protein expression of the sterol regulatory element-binding protein-1 (SREBP-1) and perilipin 2 (PLIN2), Western blot analysis was performed. Differentially expressed genes (DEGs) in SZ95 sebocytes under hypoxia were revealed by RNA-Seq analyses, and the statistical significance of the correlation between hypoxic and acne/non-acne skin was evaluated using gene set enrichment analysis. RESULTS: Hypoxia induces lipid accumulation in SZ95 sebocytes. In addition, the levels of SREBP-1 and PLIN2 were regulated by HIF-1α in SZ95 sebocytes under hypoxia. RNA-Seq analyses of DEGs in SZ95 sebocytes under hypoxia revealed 256 DEGs, including several lipid droplet-associated genes. DEGs between acne and non-acne skin are significantly enriched in hypoxia gene sets. We also detected 93 differentially expressed inflammatory mediators. CONCLUSIONS: To the best of our knowledge, this study is the first to show that a hypoxic microenvironment can increase lipogenesis and provides a link between seborrhea and inflammation.