Accumulation of lipid peroxide in the content of comedones may be involved in the progression of comedogenesis and inflammatory changes in comedones

Background: Previous studies reported that lipid peroxide (LPO) caused by oxidation of sebum is associated with the progression of acne vulgaris, and that therapy with antioxidative ingredients is efficacious for treatment. In this study, we hypothesized that lipid accumulation in comedones induces progression of comedogenesis and inflammatory changes in comedones, and investigated the possible role of accumulated LPO in comedogenesis and its inflammatory changes. Mehods: We first sampled comedones and the stratum corneum from patients with acne vulgaris. The quantities of LPO, interleukin-1-alpha (IL-1α), and NF-kappa-B (NF-κB) in comedones and in the stratum corneum from each patient were measured for comparison. Next, comedones were sampled again from the same patients and classified into five groups: microcomedo (MC), noninflammatory open comedo (NIOC), noninflammatory closed comedo (NICC), inflammatory open comedo (IOC), and inflammatory closed comedo (ICC). We measured quantities of LPO in each group. Results: The quantities of LPO, IL-1α, and NF-κB were significantly higher in the content of comedones than those in the stratum corneum. The quantities of LPO in the content of IOC and ICC were significantly higher than those of MC, NIOC, and NICC; however, there were no significant differences in quantities of LPO between the content of MC, NIOC, and NICC. Conclusions: We conclude that the accumulation of a certain amount of LPO in the content of comedones may play an important role in the progression of comedogenesis and the excessive accumulation of LPO may be involved in inflammatory changes in comedones.