Could psoralen plus ultraviolet A1 ('PUVA1') work? Depth penetration achieved by phototherapy lamps.
Could psoralen plus ultraviolet A1 ('PUVA1') work? Depth penetration achieved by phototherapy lamps.
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补骨脂素加紫外线 A1（“PUVA1”）有效吗？
DOI：
10.1111/bjd.18561
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Barnard IRM
中科院分区：
文献类型：
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作者：
Barnard IRM
亲爱的编辑，补骨脂素和紫外线A(PUVA)对治疗各种手足皮肤病很有用。1大多数银屑病患者对光疗或PUVA反应良好。然而，对于一些疾病，如掌跖脓疱性银屑病，PUVA并不总是足以产生治疗效果。如果PUVA失败，有时有必要进行其他治疗，如格伦茨射线疗法(如果可行)，2全身维甲酸或全身免疫抑制。在传统的PUVA(补骨脂素加宽带UVA)已经不够用的情况下，‘PUVA1’(补骨脂素联合紫外线A1长波UVA)能奏效吗？先前的体外和体内研究表明，较长的UVA波长可以激活补骨脂素并诱导红斑。3、4结合这一事实，更长的紫外线波长可以更深入地渗透到组织中(这可能是为什么UVA1单一疗法可能对手掌足底脓疱病有效5)，一个潜在的结果是，补骨脂素加UVA1源在治疗影响到手掌和脚底等表皮较厚的部位的情况下可能比标准的宽带UVA源更有效。我们想要确定PUVA1是否可能是一种有用的治疗方法，然后再决定是否适合进行试点临床研究。蒙特卡罗辐射传输(MCRT)方法使用局部散射和吸收概率来描述光子包通过介质的路径，非常适合于模拟复杂的结构，如皮肤的上层。这些计算密集的方法依赖于重复的随机抽样来形成通过散射介质(如皮肤)的辐射传输的预测模型。7 MCRT方法被广泛使用，并且依赖于已公布的组织的光学属性。使用先前发表的五层MCRT皮肤模型的改进版本，模拟了几种光疗光源[金属卤化物UVA1、荧光灯UVA1、宽带UVA(PUVA管)和窄带UVB(标准光疗)]的照射。进行了四次模拟，每个光源一次，每次模拟运行1亿个光子包，以获得统计上显著的结果。恢复每个光源在深度处获得的总通量。对牛皮癣皮肤重复了四个模拟，通过将模拟的角质层(表皮角蛋白层)增厚2倍来实现。我们的模拟结果量化了UVA1(荧光灯和金属卤化物灯)比宽带UVA和窄带UVB所实现的深度穿透优势。当入射光通量为50%时，优势较小，但在考虑光通量为10%的深度时，优势更大(表1)。此外，我们发现牛皮癣组织大大降低了所有灯光所能达到的深度-角质层强烈地散射和吸收紫外线辐射，因此
DEAR EDITOR, Psoralen and ultraviolet A (PUVA) is useful in treating various hand and foot skin diseases. 1 Most cases of psoriasis respond well to phototherapy or PUVA. However, for some diseases, such as palmoplantar pustular psoriasis, PUVA is not always sufficient to produce therapeutic effect. If PUVA fails, it is sometimes necessary to progress to other treatments such as Grenz ray therapy (where available), 2 systemic retinoid or systemic immunosuppression. Could ‘PUVA1’(psoralen combined with ultraviolet A1 long-wavelength UVA) work in cases where conventional PUVA (psoralen plus broadband UVA) has been inadequate? Previous in vitro and in vivo work has indicated that longer UVA wavelengths can activate psoralen and induce erythema. 3, 4 Combine this with the fact that longer UV wavelengths penetrate deeper into tissue (this is probably why UVA1 monotherapy might work in palmoplantar pustulosis5), and a potential result is that psoralen plus a UVA1 source might be more effective than the standard broadband UVA source in treating conditions that affect sites with a thick epidermis, such as palms and soles of feet. We wanted to determine if PUVA1 might be a useful treatment, before deciding whether or not a pilot clinical study would be appropriate. Monte Carlo radiative transfer (MCRT) methods use localized scattering and absorption probabilities to describe the path of photon packets through a medium, and are ideally suited to modelling a complex structure such as the upper layers of the skin. 6 These computationally intensive methods rely on repeated random sampling to form predictive models of radiation transport through a scattering medium, such as the skin. 7 MCRT methods are widely used and rely on published optical properties of the tissue. Using a modified version of a previously published five-layered MCRT skin model, 8 irradiation by several phototherapy light sources [metal halide UVA1, fluorescent lamp UVA1, broadband UVA (‘PUVA tubes’) and narrowband UVB (a standard phototherapy)] was simulated. Four simulations were performed, one for each light source, and each simulation was run with 100 million photon packets, to achieve statistically significant results. The total fluence, at depth, achieved by each light source is recovered. The four simulations were repeated for psoriatic skin, achieved by thickening the modelled stratum corneum (the epidermal keratin layer) by a factor of two. The results of our simulations quantify the depth penetration advantage achieved by UVA1 (both fluorescent and metal halide lamps) over that achieved by broadband UVA and narrowband UVB. The advantage is smaller at 50% of incident fluence, but larger when considering the depth of 10% of the fluence (Table 1). In addition, we found that psoriatic tissue greatly reduced the depth achieved by all lamps–the stratum corneum strongly scatters and absorbs UV radiation, so