Abstract
Recently, consumers have been paying a lot of attention to improvement of enlarged facial pores. Investigation of the basic mechanism underlying enlarged pores and development of methods of improvement are big issues for cosmetic scientists. The purpose of this study is to define an image parameter which well expresses a visual impression of the situation of facial pores and to investigate whether oxidative stress is involved in the mechanism of the enlargement of pores. As a first step, we determined that the threshold of size which is recognized as an enlarged pore was 0.04 mm2. In addition, we found that image parameters in a determinate area, a total area of pores, mean area of pores and number of enlarged pores well expressed the visual impression, and also a correlation with the image parameter between total area of pores and age was shown. As a second step, we assessed the relationship between image parameters on total area of pores and parameters from stratum corneum (SC) including nucleated cells, thick abrasion, catalase activity and protein carbonylation (SCCP) in order to investigate mechanisms of the enlargement of pores. In analysis on parameters which were extracted from the entire face, there was no correlation with the total area of pores and SC derived parameters except catalase activity. In the study, we found that enlarged pores were concentrated more in the upper cheek than the lower cheek. In addition, the SC histological study pointed out that parakeratotic cells and SCCP-positive cells were localized at the peripheral area of open ducts in pores. We attempted further analysis using parameter ratios in which parameters in the upper cheek were internally normalized by those in the lower cheek. As a result, it was found that SCCP ratio and catalase ratio showed significant correlations with total area of facial pores. In the study, we proposed the possibility that epidermal oxidative stress was one of factors behind the enlargement of facial pores.
