The main hormonal driver of oily sebum production in the skin is dihydrotestosterone. Another androgenic hormone responsible for increased sebaceous gland activity is DHEA-S. The adrenal glands secrete higher amounts of DHEA-S during adrenarche (a stage of puberty), and this leads to an increase in sebum production. In a sebum-rich skin environment, the naturally occurring and largely commensal skin bacterium "C. acnes" readily grows and can cause inflammation within and around the follicle due to activation of the innate immune system. "C. acnes" triggers skin inflammation in acne by increasing the production of several pro-inflammatory chemical signals (such as IL-1α, IL-8, TNF-α, and LTB4); IL-1α is essential to comedo formation.