Abstract
PURPOSE: In the skin of elderly people with dryness, the production of inflammatory cytokines tends to be induced under the influence of external stimuli. Therefore, there has been a hypothesis that the deterioration of skin conditions due to aging is linked to systemic inflammation. This study aimed to verify the possibility that the use of moisturizer improves skin condition and suppresses systemic inflammation. METHODS: As an open study, the participants (n=75) were randomly assigned to either control group or moisturizer group. Participants in the moisturizer group used a moisturizer called Grafa Moisture Keep Milk MC at least twice a day for four weeks on the entire body below the neck. Objective skin conditions (overall dry skin score, water content of the stratum corneum, and transepidermal water loss) and serum cytokine levels (IL-1α, IL-1β, IL-4, IL-5, IL-6, IL-8, and TNF-α) were evaluated before and after the study in both groups. Subjective skin condition (questionnaire evaluation) was also assessed in the moisturizer group after the study. RESULTS: Serum IL-6 level was significantly reduced in the moisturizer group (n=16) compared with the control group (n=36). In addition, there was an inverse correlation between serum IL-5 and the subjective moisturizing effect in the questionnaire evaluation, suggesting that the moisturizer improved subjective symptoms of dryness by reducing IL-5 levels. Furthermore, there was a positive correlation between IL-5 and IL-6, indicating that they are regulated by common upstream factors. A significant positive correlation of transepidermal water loss with serum IL-4 levels was also detected. CONCLUSION: The application of the moisturizer to the entire body not only improved subjective and objective skin condition, it may also reduce the levels of circulating inflammatory cytokines. UMIN CLINICAL TRIALS REGISTRY: Registration number: UMIN 000052024.