Department of Dermatology, Royal Adelaide Hospital, North Terrace, Australia.
Arch Dermatol Res. 2011 May;303(4):285-92. doi: 10.1007/s00403-011-1128-x. Epub 2011 Feb 3.
Topical 5-aminolevulinic acid (ALA) and methyl aminolevulinate (MAL) photodynamic therapy (PDT) of skin lesions is an accepted treatment for skin tumours but success rates need improvement. The effectiveness of PDT is influenced by availability of oxygen. The aim of this study was to demonstrate, in normal skin, whether a decrease in skin oxygen tension reduces the photodynamic reaction (PDR); and whether the addition of topical hydrogen peroxide can reverse the effect. Topical MAL and red light were administered to the inner forearms of 40 healthy volunteers. Skin oxygen availability was lowered during the illumination phase of the PDT, by applying blanching pressure with a plastic slide. Topical hydrogen peroxide was applied under the pressure slide, immediately prior to illumination, to reverse the effect. Erythema was assessed by naked eye and laser Doppler perfusion imaging (LDPI), at baseline and at 1, 5, 24 and 48 h following illumination. Decreasing oxygen availability by pressure altered the PDR with a larger number of subjects (17.5%) not demonstrating any visible erythema at any time point after plastic slide pressure compared to a PDR Control site (7.5%). The addition of topical hydrogen peroxide during pressure application, restored the number of subjects showing no visible erythema compared to that of PDR Control. LDPI data showed that there was a decrease in mean perfusion after plastic slide pressure when comparing the change from baseline to 24 h (P < 0.05) with the PDR Control. The addition of hydrogen peroxide not only restored but also increased the mean perfusion compared to that of PDR Control when comparing the change from baseline to 5 h and the change from baseline to 24 h (P < 0.001). Increasing oxygen availability increased the PDR in normal skin. The possibility that addition of topical hydrogen peroxide to PDT protocols for non-melanoma skin cancer may increase reactivity and, thus, be relevant for outcomes warrants further study.
局部 5-氨基酮戊酸（ALA）和甲基 5-氨基酮戊酸（MAL）光动力疗法（PDT）是治疗皮肤肿瘤的一种公认方法，但成功率需要提高。PDT 的效果受氧气供应的影响。本研究旨在证明在正常皮肤中，皮肤氧张力的降低是否会降低光动力反应（PDR）；以及局部应用过氧化氢是否可以逆转这种效应。在 40 名健康志愿者的前臂内侧给予局部 MAL 和红光。在 PDT 的光照阶段，通过应用塑料幻灯片施加苍白压力来降低皮肤的氧气可用性。在光照前，立即在压力幻灯片下应用局部过氧化氢以逆转效果。在光照后 1、5、24 和 48 小时，通过肉眼和激光多普勒灌注成像（LDPI）评估红斑。通过压力降低氧气可用性改变了 PDR，与 PDR 对照部位相比，更多的受试者（17.5%）在任何时间点都没有显示任何可见的红斑（7.5%）。在压力应用过程中添加局部过氧化氢使显示无可见红斑的受试者数量恢复到与 PDR 对照相同。LDPI 数据显示，与 PDR 对照相比，在基线到 24 小时的变化中（P < 0.05），比较基线到 24 小时的变化时，使用塑料幻灯片压力后平均灌注减少。与 PDR 对照相比，在比较从基线到 5 小时的变化和从基线到 24 小时的变化时，添加过氧化氢不仅恢复了而且增加了平均灌注（P < 0.001）。增加氧气可用性可提高正常皮肤的 PDR。向非黑素瘤皮肤癌的 PDT 方案中添加局部过氧化氢以增加反应性的可能性，从而与结果相关，这值得进一步研究。
