[Phototherapy and carcinogenesis]

Phototherapy: Theory and practice

Despite the development of highly effective biologics for skin diseases such as psoriasis or atopic dermatitis, UVA and UVB therapy, alone or in combination, are still essential components of various guidelines. Phototherapy is not only a first-line treatment and highly effective for a number of skin diseases, but is also economical and has few side effects. The targeted use of UVA and UVB, if necessary, in combination with the photosensitizer psoralen in the context of PUVA therapy, enables the dermatologist to effectively treat a wide variety of skin diseases. Indications for phototherapy include epidermal diseases such as atopic dermatitis, psoriasis and vitiligo, as well as photodermatoses, mycosis fungoides, graft-versus-host disease and deep dermal diseases such as scleroderma. This article reviews the physical principles, molecular mechanisms, current treatment regimens, and individual indications for phototherapy and photochemotherapy.

Phototherapie in Theorie und Praxis

Die Therapie oder Kombinationstherapie mit UV‐A‐ oder UV‐B‐Strahlen ist trotz der Entwicklung hochwirksamer Biologika bei Hauterkrankungen wie Psoriasis oder atopischer Dermatitis nach wie vor unverzichtbarer Bestandteil verschiedener Leitlinienempfehlungen. Die Phototherapie ist nicht nur eine sehr effektive Erstlinientherapie bei verschiedenen Hauterkrankungen, sondern auch kostengünstig und nebenwirkungsarm. Der gezielte Einsatz von UV‐A und UV‐B, gegebenenfalls auch in Kombination mit dem Photosensibilisator Psoralen im Rahmen einer PUVA‐Therapie, ermöglicht dem Dermatologen eine effektive Behandlung verschiedener Hautkrankheiten. Indikationen für die Phototherapie sind epidermale Erkrankungen wie die atopische Dermatitis, die Psoriasis und die Vitiligo, ferner Photodermatosen, die Mycosis fungoides, die Graft‐versus‐Host‐Erkrankung sowie tiefe dermale Erkrankungen wie die Sklerodermie. Dieser Artikel gibt einen Überblick über die physikalischen Grundlagen, die molekularen Mechanismen, die derzeitigen Behandlungsmethoden und die einzelnen Indikationen für die Phototherapie und die Photochemotherapie.

[UV phototherapy : UV phototherapy and photodiagnostics-a practical overview]

UV phototherapy is an essential and efficient therapeutic option in the treatment of dermatological diseases. It is an integral part of multiple guidelines and maintains its high clinical significance despite the development of new therapeutic options for systemic treatment. Due to the difficult revenue situation, the market for ready-to-use products of psoralen and UV therapy devices is constantly changing.

Advances in phototherapy for psoriasis and atopic dermatitis

Introduction: Phototherapy has long been used for the treatment of inflammatory skin diseases, such as psoriasis and atopic dermatitis. The most frequent treatment approach utilizes ultraviolet (UV) light, however, recently, different lasers and low-level light therapies (LLLT) emitting wavelengths in the spectrum of the visible light have also been tried for the treatment of inflammatory skin diseases with variable success.Areas covered: This review provides an update on the different forms of phototherapy used for the treatment of psoriasis and atopic dermatitis. The proposed mechanism of action of the different phototherapeutical approaches are covered, including the immunosuppressive effect of UV light, the anti-inflammatory effect of vascular lasers and the LLLT induced photobiomodulation. The clinical efficacy of the different treatment options is also discussed.Expert opinion: Based on the efficacy and safety, NB-UVB represents the gold standard for treating psoriasis and atopic dermatitis. The UVB excimer laser and excimer lamp might be the best option for clearing localized therapy-resistant lesions. Home UV phototherapy systems might promote treatment adherence and better compliance of the patients. Vascular lasers, IPLs and LLLT, however, can not currently be recommended for the treatment of inflammatory skin diseases because of the lack of well-controlled studies.

Efficacy assessment of UVA1 and narrowband UVB for treatment of scalp psoriasis

To compare the efficacy and safety of UVA1 and narrowband UVB (NB-UVB) therapy in the treatment of scalp psoriasis. Patients with scalp psoriasis were randomly assigned to either UVA1 or NB-UVB therapy. Both treatments were performed three times weekly for 6 weeks. Clinical efficacy was evaluated by using Psoriasis Scalp Severity Index (PSSI), and patient-reported quality of life (QoL) was assessed by Dermatology Life Quality Index (DLQI). Totally 68 patients completed the study. Both UVA1 and NB-UVB phototherapy achieved a statistically significant reduction of PSSI and DLQI scores at the end of the treatment period. Compared with the NB-UVB group, the significantly greater improvements occurred in UVA1 treatment group at week 3, although differences declined thereafter through week 10. Both UVA1 and NB-UVB therapy were well-tolerated in this study, and the occurrence of adverse events (AEs) was uncommon. Both UVA1 and NB-UVB phototherapy could offer relief of scalp symptoms in patients with scalp involvement. Furthermore, UVA1 treatment could improve the clinical manifestations and QoL more quickly than NB-UVB therapy.

Transcriptional and Posttranslational Regulation of Nucleotide Excision Repair: The Guardian of the Genome against Ultraviolet Radiation

Ultraviolet (UV) radiation from sunlight represents a constant threat to genome stability by generating modified DNA bases such as cyclobutane pyrimidine dimers (CPD) and pyrimidine-pyrimidone (6-4) photoproducts (6-4PP). If unrepaired, these lesions can have deleterious effects, including skin cancer. Mammalian cells are able to neutralize UV-induced photolesions through nucleotide excision repair (NER). The NER pathway has multiple components including seven xeroderma pigmentosum (XP) proteins (XPA to XPG) and numerous auxiliary factors, including ataxia telangiectasia and Rad3-related (ATR) protein kinase and RCC1 like domain (RLD) and homologous to the E6-AP carboxyl terminus (HECT) domain containing E3 ubiquitin protein ligase 2 (HERC2). In this review we highlight recent data on the transcriptional and posttranslational regulation of NER activity.

Phototherapy for alopecia areata

Phototherapy is a useful therapeutic method for various skin diseases due to its modulatory effect on the cutaneous immune system. Alopecia areata is a dermatosis characterized by partial or complete hair loss. Collapse of the immune privilege of the hair follicle, which induces noncicatricial alopecia, is an important factor in its etiology. Several forms of phototherapy are used in dermatology.

Laser-induced autofluorescence spectroscopy: can it be of importance in detection of bladder lesions?

BACKGROUND

Non-muscle invasive bladder cancer can be missed during white light endoscopy in up to 50% of cases. We aimed to test whether or not we could find a difference between benign and cancerous tissue wavelengths using laser induced autofluorescence spectroscopy can increase cancer detection.

MATERIALS AND METHODS

We analysed 67 tissue samples using spectral analysis. The WavSTAT (Spectra Science) optical biopsy device was used to record fluorescence spectra from biopsied tissue enabling calculation of an AUC for each spectrum, a measure of the mean spectral wavelength (λ¯ (nm)) and a dimensionless fluorescence ratio. Mann-Whitney test was used to compare the two groups.

RESULTS

We found that 49.3% (33/67) of the tissue was benign, 44.8% (30/67) was CIS/cancerous tissue, and the remaining 4/67 samples were atypia (2) and dysplasia (2). The median AUC for the benign tissue was 19.53 (interquartile range [IQR]: 5.35-30.39) and that for CIS/cancerous tissue was 7.05 (IQR: 2.89-14.24) (P=0.002). The median wavelengths for the benign tissue and malignant tissue were 502.4nm (IQR: 500.3-504.3nm) and 505.2nm (IQR: 502.1-513.2nm), respectively (P=0.003). The median fluorescence ratio was 0.080 (IQR: 0.070-0.088) for benign tissue and 0.096 (IQR: 0.079-0.221) for CIS/cancerous tissue (P=0.002).

CONCLUSIONS

We found statistical differences between the median AUC calculations and median wavelengths for the benign and cancerous tissue. We also found a statistical difference between the fluorescence ratios between the two tissue types. There seems to be a role for optical spectroscopy in verifying bladder lesions.

Phototoxicity of narrowband ultraviolet (UV) B (311 nm) compared with broadband UVB in the photo hen's egg test

BACKGROUND

Broadband ultraviolet B (BB-UVB) is a well-established treatment option in dermatology. However, during the last decade BB-UVB has increasingly been replaced by narrowband UVB 311 nm (NB-UVB), especially in the therapy of psoriasis, atopic eczema and vitiligo. Several studies have indicated a better therapeutic response for almost all indications compared with BB-UVB.

OBJECTIVES

The aim of our study was to investigate the phototoxic effects of NB-UVB in comparison with BB-UVB in vivo.

METHODS

Therefore, we employed the photo hen's egg test (PHET), an established phototoxic model, based on the yolk sac blood vessel system of incubated hen's eggs. NB-UVB and BB-UVB dosages increasing from 30 up to 1200 mJ cm(-2) were applied on 17 test groups (each n = 12 eggs) and two unirradiated test groups served as controls. Twenty-four hours after irradiation we observed the following test parameters: lethality, membrane discoloration and haemorrhages.

RESULTS

Following our results, the lethal half dose (LD50) was 60 and 720 mJ cm(-2) for BB-UVB and NB-UVB, respectively. These LD50 dosages provoked severe membrane discoloration and haemorrhaging. Summarizing our results, the LD50 of NB-UVB was 12-fold higher than BB-UVB.

CONCLUSIONS

Interestingly, these findings are in good accordance with the literature, where the minimal erythema dose (MED) of NB-UVB in human skin is up to 14 times higher than the MED of BB-UVB. These results show that the PHET is a valid test model to evaluate the phototoxic effects of various UVB wavelengths. Moreover, our results indicate that regarding the investigation of phototoxic effects the PHET might serve as a model representative for human skin, which might reduce the extent of photoprovocation in humans in the future.