we examined the corresponding chromameter measurements of the representative subjects, we noted an improvement in the L*values of the sunscreen panelist and a decrease in the L* Value of the real-life control subject on the cheeks indicating a lightning and darkening respectively. In the dermis, 2 out of 3 of the real-life samples showed an increase in CD68 positive macrophage cells (Figure 5b) when compared to baseline (Figure 5a), while such changes were not observed in the biopsies from the sunscreen group (Figure 5c, 5d). Between the real life and the sunscreen groups, there were no observable differences in the number of sunburn cells, epidermal hyperplasia and changes to the dermal matrix (data not shown).
DISCUSSIONS AND CONCLUSIONS
The clinical evaluation demonstrated significant visible improvement in sunscreen group starting from 3 months and progressive increased over time. Benefits on multiple facial areas and body sites were visible (upper, mid- and lower face, neck, and hands), not only on pigmentary-related concerns (skin tone evenness, overall hyperpigmentation, dark spots, and blotchiness), but also on aging parameters such as fine lines, skin texture, and overall skin quality. This suggests that beyond the preventative benefits, long-term persistent use of a proper sunscreen may also allow the photodamaged skin to self-heal and repair over time.
Histological observations further supported the clinical findings. The observation that the real-life group had higher tendency for pigmentation incontinence is of strong research interest. It has been reported that UV irradiation can destabilize and damage the dermal-epidermal junction (DEJ), which facilitates the entrapment of melanin in the dermis.23 The dermal melanin is extremely difficult to remove, often resulting in stubborn hyperpigmentation.24 This is especially important for skin of color population in whom dermal hyperpigmentation lesions are common and can be worsened with excessive sun exposure. This study provides the first evidence that effective daily photoprotection can be a strategy to prevent dermal melanin formation by protecting the DEJ. A larger sample size study with DEJ biomarkers will help to further elucidate this hypothesis. Infiltration of CD68-positive Macrophages is a hallmark of the inflammatory response after UV irradiation. In the dermis, 2 out of 3 of the real-life biopsy samples showed significant increase in CD68 positive macrophage cells at 12 months compared to baseline, while such change was not observed in the sunscreen group. This suggests the potential preventative benefits of sunscreen in subclinical skin inflammation induced by chronic exposure to UV. In all of the histological evaluations, the