Modulation of sebum oxidation and interleukin-1α levels associates with clinical improvement of mild comedonal acne

BackgroundSebum plays a key role in the initiation of the acne lesions. Oxidized sebum lipids cause keratynocytes hyperproliferation and inflammatory cytokines release. Association between sebum oxidation and comedogenesis has been little investigated in comedonal acne. ObjectivesEvaluation of sebum oxidation parameters and levels of inflammatory cytokines (IL-1) in patients with mild comedonal acne (MCA) before and after the treatment with a mixed RetinSphere((R))- vitamin E formulation. MethodsSebum excretion rate (SER), squalene concentration, and oxidation degree of sebum were measured in 18 MCA patients and 10 controls. IL-1 levels in the stratum corneum were measured in both lesional and non-lesional facial areas of MCA patients. Sebum parameters and IL-1 were measured at week 4 of topical treatment. Reflectance confocal microscopy (RCM) was performed in a subset of four patients at the baseline and at week 4 and all patients were assessed clinically before and following the 8week-treatment. ResultsSebum excretion rate and squalene concentration were comparable between MCA patients and healthy controls. Lipid peroxidation (LPO) and the percentage of oxidized squalene (SQOX) were significantly elevated in the sebum of MCA patients. The concentration of the proinflammatory cytokine IL-1 in stratum corneum was significantly higher in the lesional area compared with non-lesional area of the MCA patients at the baseline. At week 4, while SER and squalene concentration did not vary significantly, the LPO levels and the SQOX percentage resulted decreased at a significant extent. Following the treatment, IL-1 concentration in the lesional area reached values comparable to those of unaffected areas. Consistent with the biochemical data, RCM showed the reduction of hyperkeratinization and of inflammatory cells infiltration of the adnexal structures epithelium, significant clinical improvement was recorded at week 8. ConclusionThe data further support the involvement of lipid oxidation and particularly by-products of squalene oxidation in comedogenesis.