A Perspective on the Use of NB-UVB Phototherapy vs. PUVA Photochemotherapy

Utility of prostaglandin analogues and phosphodiesterase inhibitors as promising last resorts for the treatment of vitiligo: A systematic review, from mechanisms of action to mono-, combination and comparative therapies

BACKGROUND

The treatment of vitiligo is a persistent challenge in dermatology. New treatments are being offered and studied in this field for those resistant to or intolerant of classical therapies.

AIMS

In this systematic review, we study the use of prostaglandin analogues (PGAs) and phosphodiesterase inhibitors (PDEIs) in the treatment of vitiligo, as they are known for their pigmentation inducing effects through activating melanocytes.

METHODS

We searched four main online databases with the keywords "Vitiligo", "Prostaglandin analogue" and "Phosphodiesterase inhibitor".

RESULTS

A total of 42 articles were included, with 1027 cases, studying drugs like bimatoprost, latanoprost, travoprost, dinoprostone, apremilast, crisaborole, etc. Among the included studies, the treatment regimens are commonly once or twice daily for 12-48 weeks, with a mean of 20.61 weeks, and the routes of administration are mainly topical gels or ophthalmic solutions and oral tablets. Side effects are mild and tolerable, namely erythema, itching or burning sensations at application site for topicals, or gastrointestinal problems with apremilast. Repigmentation results are significant in both adult and pediatric patients and progressive or stable vitiligo. PGAs and PDEIs outperform many classical therapies, for example, narrowband ultraviolet B phototherapy (NB-UVB), tacrolimus, mometasone or methylprednisolone mini-pulse. PGAs or PDEIs are usually used in combination therapies to either cause synergism or increase drug delivery, and almost always enhance repigmentation, for example, with NB-UVB, fractional CO2 laser, microneedling, and mometasone.

CONCLUSION

Monotherapy or add-on PGAs and PDEIs can be considered effective treatments for vitiligo and promising last resorts for those resistant to other therapies.

Role of non‑coding RNAs in UV‑induced radiation effects (Review)

Ultraviolet (UV) is divided into UVA (long-wave, 320-400 nm), UVB (middle-wave, 280-320 nm) and UVC (short-wave, 100-280 nm) based on wavelength. UV radiation (UVR) from sunlight (UVA + UVB) is a major cause of skin photodamage including skin inflammation, aging and pigmentation. Accidental exposure to UVC burns the skin and induces skin cancer. In addition to the skin, UV radiation can also impair visual function. Non-coding RNAs (ncRNAs) are a class of functional RNAs that do not have coding activity but can control cellular processes at the post-transcriptional level, including microRNA (miRNA), long non-coding RNA (lncRNA) and circulatory RNA (circRNA). Through a review of the literature, it was determined that UVR can affect the expression of various ncRNAs, and that this regulation may be wavelength specific. Functionally, ncRNAs participate in the regulation of photodamage through various pathways and play pathogenic or protective regulatory roles. In addition, ncRNAs that are upregulated or downregulated by UVR can serve as biomarkers for UV-induced diseases, aiding in diagnosis and prognosis assessment. Therapeutic strategies targeting ncRNAs, including the use of natural drugs and their extracts, have shown protective effects against UV-induced photodamage. In the present review, an extensive summarization of previous studies was performed and the role and mechanism of ncRNAs in UV-induced radiation effects was reviewed to aid in the diagnosis and treatment of UV-related diseases.

Deciphering the Molecular Mechanisms of Reactive Metabolite Formation in the Mechanism-Based Inactivation of Cytochrome p450 1B1 by 8-Methoxypsoralen and Assessing the Driving Effect of phe268

This study provides a comprehensive computational exploration of the inhibitory activity and metabolic pathways of 8-methoxypsoralen (8-MP), a furocoumarin derivative used for treating various skin disorders, on cytochrome P450 (P450). Employing quantum chemical DFT calculations, molecular docking, and molecular dynamics (MD) simulations analyses, the biotransformation mechanisms and the active site binding profile of 8-MP in CYP1B1 were investigated. Three plausible inactivation mechanisms were minutely scrutinized. Further analysis explored the formation of reactive metabolites in subsequent P450 metabolic processes, including covalent adduct formation through nucleophilic addition to the epoxide, 8-MP epoxide hydrolysis, and non-CYP-catalyzed epoxide ring opening. Special attention was paid to the catalytic effect of residue Phe268 on the mechanism-based inactivation (MBI) of P450 by 8-MP. Energetic profiles and facilitating conditions revealed a slight preference for the C4'=C5' epoxidation pathway, while recognizing a potential kinetic competition with the 8-OMe demethylation pathway due to comparable energy demands. The formation of covalent adducts via nucleophilic addition, particularly by phenylalanine, and the generation of potentially harmful reactive metabolites through autocatalyzed ring cleavage are likely to contribute significantly to P450 metabolism of 8-MP. Our findings highlight the key role of Phe268 in retaining 8-MP within the active site of CYP1B1, thereby facilitating initial oxygen addition transition states. This research offers crucial molecular-level insights that may guide the early stages of drug discovery and risk assessment related to the use of 8-MP.

An Overview of Potential Natural Photosensitizers in Cancer Photodynamic Therapy

Cancer is one of the main causes of death worldwide. There are several different types of cancer recognized thus far, which can be treated by different approaches including surgery, radiotherapy, chemotherapy or a combination thereof. However, these approaches have certain drawbacks and limitations. Photodynamic therapy (PDT) is regarded as an alternative noninvasive approach for cancer treatment based on the generation of toxic oxygen (known as reactive oxygen species (ROS)) at the treatment site. PDT requires photoactivation by a photosensitizer (PS) at a specific wavelength (λ) of light in the vicinity of molecular oxygen (singlet oxygen). The cell death mechanisms adopted in PDT upon PS photoactivation are necrosis, apoptosis and stimulation of the immune system. Over the past few decades, the use of natural compounds as a photoactive agent for the selective eradication of neoplastic lesions has attracted researchers' attention. Many reviews have focused on the PS cell death mode of action and photonanomedicine approaches for PDT, while limited attention has been paid to the photoactivation of phytocompounds. Photoactivation is ever-present in nature and also found in natural plant compounds. The availability of various laser light setups can play a vital role in the discovery of photoactive phytocompounds that can be used as a natural PS. Exploring phytocompounds for their photoactive properties could reveal novel natural compounds that can be used as a PS in future pharmaceutical research. In this review, we highlight the current research regarding several photoactive phytocompound classes (furanocoumarins, alkaloids, poly-acetylenes and thiophenes, curcumins, flavonoids, anthraquinones, and natural extracts) and their photoactive potential to encourage researchers to focus on studies of natural agents and their use as a potent PS to enhance the efficiency of PDT.

The Effectiveness of Laser Applications and Photodynamic Therapy on Relevant Periodontal Pathogens (Aggregatibacter actinomycetemcomitans) Associated with Immunomodulating Anti-rheumatic Drugs

Considering the current context of the increasing resistance of bacterial species to antibiotics and other antimicrobial agents, a major objective is to develop other antimicrobial approaches, which would be able to inactivate pathogens with considerable effectiveness. Two such methods are photodynamic disinfection therapy and laser irradiation. In view of the immunocompromised status of some patients under immunosuppressive therapy and potential drug interactions that can be established between systemic antimicrobial agents, the research of local, minimally invasive methods of inactivating periodontal pathogens in the context of these systemic therapies with modifying drugs of the immune response is justified. This in vitro study evaluated the antimicrobial action of a diode laser, wavelength 940 nm, and photodisinfection therapy at 670 nm (photosensitizer, 3,7 dimethyl phenothiazine chloride) on a type strain of Aggregatibacter actinomycetemcomitans, a known periodontal pathogen, in the presence and absence of active substances used in autoimmune disease therapy (Etanercept, Infliximab, Metothrexate). The association of a conventional antirheumatic drug with anti-TNF-α therapy determined a significantly greater inhibition of the strain of A. actinomycetemcomitans compared to monotherapy, in vitro. Photodisinfection caused a significant reduction in bacterial burden after a 30 s exposure in vitro, regardless of the pharmaceutical associations of biological and conventional disease-modifying antirheumatic drugs (DMARDs). Irradiation with a diode laser for 30 s at a power of 5 W caused a greater reduction compared to irradiation with 1 W. The application of laser and photodisinfection induced a significant reduction in Aggregatibacter actinomycetemcomitans in vitro and could be considered important adjunctive measures for the eradication of this oral pathogen in the context of immunomodulating therapy.

Portable Cold Atmospheric Plasma Patch-Mediated Skin Anti-Inflammatory Therapy

Although plasma is a promising technology in various fields, its clinical application is restricted by several limitations. A cold atmospheric plasma (CAP) patch is fabricated to help overcome hurdles, especially when treating skin diseases. This patch has surface dielectric barrier discharge, which generates reactive oxygen species (ROS) and reactive nitrogen species (RNS) on a flexible polymer film surface on which the embedded electrode induces a locally strong electric field. The effect of the CAP patch on psoriasis is also evaluated. The distinct characteristics of psoriasis between the lesion and non-lesion area allow the CAP patch to be suitable for only lesion area for its treatment. The CAP patch induces the opening of calcium channels in keratinocytes, thereby restoring abnormal keratinocyte differentiation and the collapse of the tight junction; thus, alleviating psoriatic symptoms. In addition, the favorable effect is due to the induction of ROS/RNS by the CAP patch, not the electric field generated during plasma generation. The findings indicate that the proposed portable CAP patch can help treat inflammatory skin disorders, especially psoriasis. As this can be used easily as a combination therapy with existing drugs, it may help reduce side effects caused by existing drugs.

Evaluation of Biological Effects and Transcriptome Changes Induced by LED Based Narrow Band UVB Phototherapy

Ultraviolet (UV), particularly UVB, is widely used in the treatment of skin diseases including psoriasis, atopic dermatitis, vitiligo, mycosis fungoides, and pruritus. Recently, there has been a trend of replacing broad band UVB (BB-UVB) units with narrow band UVB (NB-UVB), as studies have demonstrated that NB-UVB is more efficacious in the treatment of psoriasis. The purpose of this study is to evaluate the biological effects and transcriptome changes induced by light emitting diode based NB-UVB (NB-UVB LED) phototherapy. Cell viability and the cell migration ability was significantly decreased post treatment, as well as apoptosis and ROS levels were remarkably increased. NB-UVB induced S phase arrest was observed 12 hours post irradiation. Bioinformatics analysis of transcriptome sequencing data revealed that NB-UVB LED irradiation induced dose-depended changes in multiple key signaling pathways, such as PI3K and cytoskeletal-related pathways. The depolymerization of cytoskeleton induced by NB-UVB was observed 24 hours post treatment. In addition, the expression levels of cytoskeleton related proteins FN1, ITGB4, ITGA1, RAC2 and DOCK1 decreased significantly 12 hours after irradiation. Our results indicated that NB-UVB LED may serve as a novel option for the development of NB-UVB phototherapy devices.

Hemorrhagic dot score as a follow up marker in psoriasis on treatment: A prospective observational study

CONTEXT

Psoriasis assessment tools in use presently lack reproducibility and are cumbersome to use. An easily reproducible, objective tool with ability to maintain visual records for follow up is hence desirable. We conducted a study with the aim to assess dermoscopic changes in psoriasis while on treatment by recording the number of hemorrhagic dots (Hemorrhagic Dot Score-HDS) in a representative plaque and comparing it to the PASI score.

SETTINGS AND DESIGN

A longitudinal prospective study was conducted between October 2018 to March 2020 in a dermatology centre of a tertiary hospital on cases of chronic plaque psoriasis on treatment over 6 months, assessed at baseline and thereafter monthly for 6 months.

METHODS

Hundred consenting patients of chronic plaque psoriasis were assessed, clinically, PASI and dermoscopically. HDS and other dermoscopic features were noted at every visit.

STATISTICAL ANALYSIS USED

ANOVA and F test of testing of equality of Variance; effect size in terms of Cohen were used to report the strength of an apparent relationship.

RESULTS AND INTERPRETATION

Percentage improvement in the mean PASI scores and HDS and percentage improvement of mean was found significant in each month on follow up. Systemic therapy as compared to topical therapy showed higher effect size of 6.1 and 1.7, respectively.

CONCLUSION

Hemorrhagic dot score can be used as an objective, definite assessment tool correlating with clinical severity of psoriasis with more accuracy which shows changes early following institution of therapy.

Comparison of the Efficacy and Safety of Bexarotene and Photo(Chemo)Therapy Combination Therapy and Bexarotene Monotherapy for Cutaneous T-Cell Lymphoma

Introduction

Cutaneous T-cell lymphoma (CTCL) is a chronic condition with low malignancy. The combined use of therapeutic agents and photo(chemo)therapy is widely applied for the treatment of CTCL. The efficacy and safety of bexarotene and photo(chemo)therapy combination therapy were previously confirmed in Japanese patients with CTCL. The efficacy and safety of the bexarotene and photo(chemo)therapy combination therapy was compared with bexarotene monotherapy in Japanese patients with CTCL.

Methods

This was a randomized, open-label, two-parallel-group, active-control specified clinical study in Japanese patients diagnosed with CTCL carried out over 8 weeks with a study extension conducted at two institutions. This study was registered in Japan Registry of Clinical Trials (jRCTs041180094).

Results

In the combination therapy group, 22 subjects received oral bexarotene (300 mg/m² body surface area) once daily, followed by bath-psoralen and ultraviolet (UV) A or narrowband UVB. In the monotherapy group, 24 subjects received oral bexarotene (300 mg/m²) once daily. The efficacy analysis using the modified Severity-Weighted Assessment Tool, which included 39 patients, showed a response rate of 81.0% (17/21) in the combination therapy group and 83.3% (15/18) in the monotherapy group. No statistically significant difference was detected between groups. In the combination therapy group, four subjects showed a complete clinical response or complete response, and subjects with a partial response exhibited a high rate of skin lesion resolution, significantly better than in the monotherapy group. In the safety analysis, which included 46 treated subjects (22 in the combination therapy group and 24 in the monotherapy group), no adverse events or adverse drug reactions were reported in either group.

Conclusion

Both bexarotene and photo(chemo)therapy combination therapy and bexarotene monotherapy were therapeutically effective in Japanese patients with CTCL and well tolerated. Combination therapy led to a higher skin lesion resolution rate and greater therapeutic effects compared with monotherapy.

Trial Registration

jRCTs041180094.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13555-021-00655-0.

This study evaluated the efficacy and safety of bexarotene monotherapy compared with bexarotene and photo(chemo)therapy combination therapy in Japanese patients with cutaneous T-cell lymphoma (CTCL). The study was a randomized, open-label, two-parallel-group, active-control specified clinical study in patients diagnosed with CTCL performed over an 8-week period with a study extension conducted in two institutions. In the combination therapy group, bexarotene (300 mg/m² body surface area) was administered orally once daily to 22 subjects, followed by treatment with bath-psoralen and ultraviolet A (bath-PUVA) or narrowband UVB. In the bexarotene monotherapy group, bexarotene (300 mg/m²) was administered orally once daily to 24 subjects. Efficacy was assessed using the modified Severity-Weighted Assessment Tool. Among the 39 subjects analyzed for treatment efficacy, the response rate of the combination therapy group was 81.0% (17/21) and that of the monotherapy group was 83.3% (15/18). Differences between the two treatment groups were not statistically significant. Of the 21 subjects in the combination therapy group, 4 had a complete clinical response or complete response, and those with a partial response showed a higher skin lesion resolution rate than in the monotherapy group. The safety analysis revealed no reports of adverse events or adverse drug reactions among the 46 treated subjects (combination therapy group = 22; monotherapy group = 24). Thus, both bexarotene and photo(chemo)therapy combination therapy and bexarotene monotherapy were therapeutically effective and well tolerated in Japanese patients with CTCL. Patients receiving the combined therapy, however, showed a higher rate of skin lesion resolution.

Fototerapia – metoda wykorzystywana w leczeniu przewlekłych schorzeń dermatologicznych

Wykorzystanie energii świetlnej w terapii schorzeń o różnej etiologii towarzyszy człowiekowi od czasów starożytnych. Elementem decydującym o powodzeniu terapii jest dobranie odpowiedniej długości promieniowania (terapia NB-UVB, BB-UVB i UVA1) lub wystąpienie interakcji między substancją światłoczułą skumulowaną w zmienionej chorobowo tkance a zastosowanym promieniowaniem (terapia PUVA oraz terapia fotodynamiczna). Metody terapeutyczne wykorzystujące energię świetlną są klasyfikowane na podstawie wykorzystywanego zakresu promieniowania. Obecnie wyróżnia się fototerapię UV, wykorzystującą promieniowanie UVA lub UVB oraz terapię fotodynamiczną (PDT; photodynamic therapy), podczas której stosowane jest promieniowanie o długości fali 350-700 nm.

Fototerapia UV wykorzystywana jest do leczenia schorzeń dermatologicznych, takich jak łuszczyca, bielactwo oraz atopowe zapalenie skóry, ze względu na jej działanie immunosupresyjne i antyproliferacyjne. Jest dostępna w postaci terapii PUVA polegającej na wykorzystaniu synergicznego działania promieniowania ultrafioletowego (UVA) oraz związków o działaniu światłouczulającym (8-metoksypsolaren, 5-metoksypsolaren). Ponadto wyróżniono monoterapię promieniowaniem ultrafioletowym A1 (UVA1), szerokozakresowym UVB (BB-UVB) i wąskozakresowym UVB (NB-UVB). Terapia fotodynamiczna obok konwencjonalnych metod leczenia jest nowoczesną i nieinwazyjną alternatywą wykorzystywaną zarówno w diagnostyce, jak i terapii chorób o różnej etiologii. W 90% przypadków PDT jest stosowana w schorzeniach dermatologicznych, takich jak trądzik pospolity czy łuszczyca. Selektywna aktywność cytotoksyczna wykazywana w kierunku złośliwych komórek nowotworowych powoduje, że terapia fotodynamiczna stosowana jest także z powodzeniem w leczeniu zmian onkologicznych. Duży postęp, przejawiający się zarówno w opracowywaniu innowacyjnych substancji światłoczułych, jak i nowych źródeł promieniowania, sprawia, iż zakres stosowalności terapii fotodynamicznej ciągle się poszerza.

W artykule przedstawiono obecnie dostępne formy fototerapii poprzez opis mechanizmu ich działania, zastosowania oraz możliwości powstania skutków niepożądanych.

Cyclobutane Pyrimidine Dimers Produced with Narrowband UVB Are on Average More Mutagenic than Those with Broadband UVB in Mouse Skin

Although narrowband UVB (NB-UVB) has replaced broadband UVB (BB-UVB) because of its greater effectiveness in dermatological phototherapy, it is twice as carcinogenic as BB-UVB at an equivalent inflammatory dose. To clarify the basis of the different genotoxicities, we comparatively evaluated the mutagenicities in mouse skin of the two UVB types along with their efficiencies in the formation of cyclobutane pyrimidine dimer (CPD), which is a major mutagenic DNA photolesion specifically produced by UVR. We found that the mutagenicity averaged per single molecule of CPD was 2.5- and 1.8-fold higher in NB-UVB-exposed epidermis and dermis, respectively, which indicates that NB-UVB is more mutagenic for the skin than BB-UVB at doses producing an equimolar amount of CPD. Analysis of effective wavelengths for UV photolesion formation with each UVB source revealed a remarkable difference in the peak effective wavelengths for CPD formation: 15 nm longer for NB-UVB in the epidermis. Although the analysis of mutation profiles showed largely similar UV-specific signatures between the two UVB types, a relatively stronger preference for UVA-specific mutations was observed for NB-UVB. These results suggest that the difference in the effective wavelengths for CPD formation leads to the different mutagenicities and carcinogenicities between the UVB sources.

Ketoprofen Combined with UVA Irradiation Exerts Higher Selectivity in the Mode of Action against Melanotic Melanoma Cells than against Normal Human Melanocytes

Malignant melanoma is responsible for the majority of skin cancer-related deaths. The methods of cancer treatment include surgical removal, chemotherapy, immunotherapy, and targeted therapy. However, neither of these methods gives satisfactory results. Therefore, the development of new anticancer therapeutic strategies is very important and may extend the life span of people suffering from melanoma. The aim of this study was to examine the effect of ketoprofen (KTP) and UVA radiation (UVAR) therapy on cell proliferation, apoptosis, and cell cycle distribution in both melanotic melanoma cells (COLO829) and human melanocytes (HEMn-DP) in relation to its supportive effect in the treatment of melanoma. The therapy combining the use of pre-incubation with KTP and UVAR causes a significant increase in the anti-proliferative properties of ketoprofen towards melanoma cells and the co-exposure of melanotic melanoma cells induced apoptosis shown as the mitochondrial membrane breakdown, cell-cycle deregulation, and DNA fragmentation. Moreover, co-treatment led to GSH depletion showing its pro-apoptotic effect dependent on ROS overproduction. The treatment did not show a significant effect on normal cells—melanocytes—which indicates its high selectivity. The results suggest a possible benefit from the use of the ketoprofen and ultraviolet A irradiation as a new concept of melanotic melanoma therapy.

Recommendations for Management of Childhood Psoriasis

Childhood psoriasis is recognized as a potential multisystem disorder and hence it is imperative to optimize disease management to arrest progression, minimize psychological burden and evolution of metabolic syndrome. Clinical practice recommendations are necessary to assist practitioners in appropriate decision making based on available evidence. Owing to the lack of Indian recommendations on childhood psoriasis, the SIG Pediatric Dermatology under IADVL Academy undertook an evidence-based approach based on published literature on the topic, between January 2000 and July 2020 to frame the recommendations.

Intravenous immunoglobulin-induced severe vesicular eczematous eruption successfully treated with narrow band-ultraviolet B therapy

Intravenous immunoglobulins (IVIg) are increasingly being used to treat a wide spectrum of dermatological and neurological autoimmune diseases. Although the administration of IVIg does not usually result in severe adverse reactions, side effects of IVIg reportedly occur in 6-13% of patients. Most reported cases were not severe, and IVIg is considered a relatively safe drug. Some reports described a vesicular eczematous eruption caused by IVIg that was cured by applying topical steroid ointments or systemic steroids. Herein, we present, to the best of our knowledge, the first case of severe vesicular eczematous eruption all over the body induced by IVIg that was unresponsive to topical steroid ointment and was subsequently treated with narrow band-ultraviolet B (NB-UVB) therapy successfully. NB-UVB was started at a dose of 400 mJ/cm² once a week, and swift improvement was observed. The skin rash disappeared in the first 2 months, and the pathogenesis of IVIg-induced eczematous eruption remains unelucidated. No change in eosinophils and complement levels were observed in our case. Given the increase in the widespread use of IVIg, we have shown that NB-UVB therapy is a candidate choice for the treatment of IVIg-induced severe vesicular eczematous eruption.

Lipid-based nanoparticles for psoriasis treatment: a review on conventional treatments, recent works, and future prospects

Psoriasis is a lingering inflammatory skin disease that attacks the immune system. The abnormal interactions between T cells, immune cells, and inflammatory cytokines causing the epidermal thickening. International guidelines have recommended topical treatments for mild to moderate psoriasis whilst systemic and phototherapy treatments for moderate to severe psoriasis. However, current therapeutic approaches have a wider extent to treat moderate to severe type of psoriasis especially since the emergence of diverse biologic agents. In the meantime, topical delivery of conventional treatments has prompted many unsatisfactory effects to penetrate through the skin (stratum corneum). By understanding the physiology of stratum corneum barrier functions, scientists have developed different types of lipid-based nanoparticles like solid lipid nanoparticles, nanostructured lipid carriers, nanovesicles, and nanoemulsions. These novel drug delivery systems help the poorly solubilised active pharmaceutical ingredient reaches the targeted site seamlessly because of the bioavailability feature of the nanosized molecules. Lipid-based nanoparticles for psoriasis treatments create a paradigm for topical drug delivery due to their lipids' amphiphilic feature to efficiently encapsulate both lipophilic and hydrophilic drugs. This review highlights different types of lipid-based nanoparticles and their recent works of nano formulated psoriasis treatments. The encapsulation of psoriasis drugs through lipid nanocarriers unfold numerous research opportunities in pharmaceutical applications but also draw challenges for the future development of nano drugs.

Effectiveness of narrowband UVB phototherapy and psoralen plus UVA photochemotherapy in the treatment of generalized lichen planus: Results from a large retrospective analysis and an update of the literature

Background

The aim of this retrospective study was to compare the efficacy and safety of different phototherapeutic modalities in the treatment of cutaneous lichen planus (LP).

Methods

We retrospectively analyzed the chart data of 53 patients with generalized LP who had been subjected to narrowband UVB (NB‐UVB) or photochemotherapy (PUVA) between January 1997 and April 2020. Of these, 30 patients had received NB‐UVB, 18 patients oral PUVA and 5 patients bath PUVA.

Results

Fifty patients completed a full treatment course. The percentage of patients with a complete (>90% clearing) or good (51%‐90% clearing) response was similar for NB‐UVB versus PUVA (86.2% vs. 90.5%; P = 1.00). The number of exposures required for obtaining a complete or good response was also comparable for both treatment groups (NB‐UVB: 28.9 ± 12.3 vs. PUVA: 25.4 ± 10.1; P = .209). Adverse events, in particular gastrointestinal upsets, were recorded in 26.1% of patients treated with oral PUVA while none were observed with NB‐UVB.

Conclusion

The therapeutic outcome and the number of treatments required for achieving a complete or good response were comparable for NB‐UVB and PUVA; however, PUVA therapy was associated with a substantially higher rate of moderate adverse events.

Narrow-band UVB combined with compound clobetasol propionate can improve the therapeutic effect in hand eczema patients

OBJECTIVE

To explore the therapeutic effect of narrow-band UVB combined with compound clobetasol propionate on hand eczema patients.

METHODS

From June 2017 to June 2020, 102 patients with hand eczema in our hospital were recruited for this study and divided into group A (GA) and group B (GB). The 50 patients in GA were treated with narrow-band UVB irradiation only, and the 52 patients in GB were treated with compound clobetasol propionate in addition to the treatment administered to GA. The patients' general data and therapeutic effects were observed in both groups. The adverse reactions were also observed during the treatment. The severity index scores (EASI) of the pruritus and eczema areas of the skin lesions were observed before and after the therapy. The IFN-γ and IL-4 levels in the serum were tested using ELISA. After the therapy, the quality of life and any recurrences within 3 months were observed in both groups.

RESULTS

There were no differences in the baseline data between the two groups (P>0.05). The curative effect in GB was better than it was in GA (P<0.05). The incidence of adverse reactions in GB was significantly lower than the incidence in GA (P<0.05). After the therapy, the EASI scores of the pruritus and eczema areas of the skin lesions in GB were significantly lower than they were in GA (P<0.05). After the therapy, the patients' serum IFN-γ and IL-4 levels in GB were significantly better than they were in GA. After the therapy, the quality of life of the patients in GB was significantly higher than it was in in GA (P<0.05). After 3 months of therapy, the recurrence rate in GB was significantly lower than it was in GA (P<0.05).

CONCLUSION

Narrow-band UVB combined with compound clobetasol propionate is effective at treating patients with hand eczema, as it can effectively improve their clinical symptoms and is very safe.

IL-23/Th17 Axis: A Potential Therapeutic Target of Psoriasis

Psoriasis is an immune-mediated skin disease that leads to the initiation of abnormal production of inflammatory mediators and keratinocytes hyper-proliferation. Th-1 cell expressing cytokines such as IL-1β and TNF-α have been the important hallmarks in the management of psoriasis. However, investigations carried out in the previous few years underline the involvement of another subset of T helper cells, i.e. Th-17 in psoriasis exacerbation, and hence become the point of focus now. The immunopathogenesis of Th-17 is the result of the IL-23/Th-17 axis. It involves the release of IL-17 and IL-22 in response to the activated NF-kβ dependent activation of IL-23. The function of human Th-17 cells as well as the crucial role of IL-23/Th-17 axis in the exacerbation of psoriasis and treatment have been well explored. Therefore, considering IL-23/Th17 axis as a pertinent therapeutic target in immune driven disorders, extensive investigations are now highlighting the utility of biopharmaceuticals and/or biological agents acting on these targets. Here, we review the IL-23/Th-17 axis based therapeutic targets, different types of active moieties based on their source of availability and most useful USFDA approved Mabs targeting the IL-23/Th17 axis in psoriasis for a better understanding of the future possibilities in this area.

The effect of narrow-band ultraviolet B radiation on sleep, happiness, and appetite: A prospective cohort study

BACKGROUND

The health benefits of sunlight are well documented, including the effects on happiness and sleep. However, only a few studies have investigated the benefits of artificial narrow-band ultraviolet B (NB-UVB) radiation.

OBJECTIVES

To investigate the effect of NB-UVB on sleep quality, happiness, and appetite.

METHODS

Patients from a single phototherapy unit were selected, and their epidemiological characteristics were documented. Subjects were asked to complete questionnaires including the Pittsburg Sleep Quality Index (PSQI), Subjective Happiness Scale (SHS), and the Simplified Nutritional Appetite Questionnaire (SNAQ) 4 weeks before and after the initiation of the NB-UVB therapy. The sample consisted of 52 patients.

RESULTS

Four weeks after the initiation of NB-UVB sessions, sleep quality was significantly improved (the PSQI decreased from 6.5 to 5.23 (t = -3.52, P < .01). In contrast, subjective happiness did not improve (the SHS decreased from baseline 5.5 to 5.2, P > .05). Similarly, appetite did not change (the SNAQ score increased from baseline 14.75 to 15.05, P > .05) and body mass index was not affected by phototherapy. In general, men were found to have better sleep quality before and after UV light therapy.

CONCLUSION

Our data suggest that NB-UVB exposure over 4 weeks improves sleep quality; however, it does not influence happiness or appetite.

Effects of a Traditional Caraway Formulation on Experimental Models of Vitiligo and Mechanisms of Melanogenesis

Background

Kursi Karwiya or caraway tablet (CWT), a traditional medicine formula, is widely used in Xinjiang, China, for treating vitiligo, a common autoimmune disease for which there is currently no satisfactory cure. Clinical interventions include pharmacological treatment with psoralens, often in conjunction with UVA radiation, but toxic side effects limit this application. Studies on the activities and mechanisms of CWT are scarce.

Objective

To investigate the in vitro and in vivo effects of CWT in B16 cell line and in animal models of vitiligo, further exploring its mechanisms of regulating melanogenesis.

Methods

Effects of CWT on melanin synthesis in B16 cells and mushroom tyrosinase activity were investigated in vitro. The signaling pathway of melanogenesis in murine B16 melanoma cells was examined by Western blotting. Two different animal models were used, vitiligo induced by hydroquinone in the mouse model and by hydrogen peroxide in the guinea pig model. Relevant biochemical parameters in blood and skin tissue were measured, and visual inspection, histopathology, and immunohistochemical analysis of treated areas were carried out.

Results

CWT produced changes in biochemical parameters including TYR, MDA, MAO, AChE, IL-6, INF-α, β-EP, and cAMP in blood and/or skin tissue and in regulating melanogenesis. After treatment with CTW, skin color, melanin containing hair follicles, and expression of TYR, TRP-1, and TRP-2 in the skin of animals were significantly affected.

Conclusions

CWT alleviated many of detrimental effects in both models of vitiligo. Tyrosinase activity and melanin content in B16 cells were increased, at least in part, via activation of the PKA p38 MAPK signaling pathways. Our results show that CWT produces beneficial effects on parameters of vitiligo and is worthy of further investigation for use in this distressing autoimmune disorder which currently has no effective cure.

Antioxidant and Anti-inflammatory Effect of Cannabidiol Contributes to the Decreased Lipid Peroxidation of Keratinocytes of Rat Skin Exposed to UV Radiation

There is a great need for compounds with antioxidant and anti-inflammatory properties for protection against UV radiation, which is the most prooxidative physical factor that skin cells are exposed to everyday. Therefore, the aim of the study was to evaluate the mechanism of phytocannabinoid-cannabidiol (CBD) action in vivo on lipid metabolism in keratinocytes of rat skin exposed to UVA/UVB radiation. Our results show that CBD protects keratinocytes against the effects of UVA/UVB radiation by reducing lipid peroxidation products: 4-HNE and 8-isoPGF2α. In addition, CBD significantly increases the level of endocannabinoids, such as anandamide, 2-arachidonylglycerol, and palmitoylethanolamide, and the activation of their receptors CB1/2 or TRPV1. The above changes are due to the protective effect of CBD against the UVA/UVB-induced decrease in the level/activity of superoxide dismutase and the components of the thioredoxin and glutathione systems. CBD also increases the in vivo transcriptional activity of Nrf2 and the expression of its Bach1 inhibitor as well as preventing the UVA/UVB-induced increase in the expression of Nrf2 activators p21, p62, p38, and KAP1 and proinflammatory factors such as NFκB and TNFα. By counteracting oxidative stress and changes in lipid structure in keratinocytes, CBD prevents cellular metabolic disturbances, protecting the epidermis against UV damage.

UVA-Triggered Drug Release and Photo-Protection of Skin

Light has attracted special attention as a stimulus for triggered drug delivery systems (DDS) due to its intrinsic features of being spatially and temporally tunable. Ultraviolet A (UVA) radiation has recently been used as a source of external light stimuli to control the release of drugs using a "switch on- switch off" procedure. This review discusses the promising potential of UVA radiation as the light source of choice for photo-controlled drug release from a range of photo-responsive and photolabile nanostructures via photo-isomerization, photo-cleavage, photo-crosslinking, and photo-induced rearrangement. In addition to its clinical use, we will also provide here an overview of the recent UVA-responsive drug release approaches that are developed for phototherapy and skin photoprotection.

A deep dive into UV-based phototherapy: Mechanisms of action and emerging molecular targets in inflammation and cancer

UV-based phototherapy (including psoralen plus UVA (PUVA), UVB and UVA1) has a long, successful history in the management of numerous cutaneous disorders. Photoresponsive diseases are etiologically diverse, but most involve disturbances in local (and occasionally systemic) inflammatory cells and/or abnormalities in keratinocytes that trigger inflammation. UV-based phototherapy works by regulating the inflammatory component and inducing apoptosis of pathogenic cells. This results in a fascinating and complex network of simultaneous events-immediate transcriptional changes in keratinocytes, immune cells, and pigment cells; the emergence of apoptotic bodies; and the trafficking of antigen-presenting cells in skin-that quickly transform the microenvironment of UV-exposed skin. Molecular elements in this system of UV recognition and response include chromophores, metabolic byproducts, innate immune receptors, neurotransmitters and mediators such as chemokines and cytokines, antimicrobial peptides, and platelet activating factor (PAF) and PAF-like molecules that simultaneously shape the immunomodulatory effects of UV and their interplay with the microbiota of the skin and beyond. Phototherapy's key effects-proapoptotic, immunomodulatory, antipruritic, antifibrotic, propigmentary, and pro-prebiotic-promote clinical improvement in various skin diseases such as psoriasis, atopic dermatitis (AD), graft-versus-host disease (GvHD), vitiligo, scleroderma, and cutaneous T-cell lymphoma (CTCL) as well as prevention of polymorphic light eruption (PLE). As understanding of phototherapy improves, new therapies (UV- and non-UV-based) are being developed that will modify regulatory T-cells (Treg), interact with (resident) memory T-cells and /or utilize agonists and antagonists as well as antibodies targeting soluble molecules such as cytokines and chemokines, transcription factors, and a variety of membrane-associated receptors.

Home Narrowband Ultraviolet B Phototherapy for Photoresponsive Skin Conditions: A Health Technology Assessment

BACKGROUND

Skin conditions are photoresponsive if they respond to ultraviolet (UV) radiation with partial or complete clearing. Ultraviolet phototherapy is performed by exposing the skin to UV radiation on a regular basis under medical supervision. Three types of UV radiation are used to treat photoresponsive skin conditions: broadband ultraviolet B (BB-UVB), psoralen plus ultraviolet A (PUVA), and narrowband ultraviolet B (NB-UVB). Narrowband UVB phototherapy is generally more effective than BB-UVB and safer than PUVA in the management of several photoresponsive skin conditions. While typically performed in an outpatient clinic setting, home NB-UVB phototherapy may be a viable option for people with limited access to outpatient treatment. We conducted a health technology assessment of home NB-UVB phototherapy for people with photoresponsive skin conditions that included an evaluation of the effectiveness, safety, cost-effectiveness, and budget impact of publicly funding home NB-UVB phototherapy, and patient preferences and values.

METHODS

We performed a systematic literature search of the clinical evidence. We assessed the risk of bias of each included study using version 2 of the Cochrane risk-of-bias tool for randomized studies, and we assessed the quality of the body of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. We performed a systematic economic literature search and conducted a cost-utility analysis with a 10-year horizon from a public payer perspective. The cost-utility analysis was conducted for psoriasis based on the available clinical evidence. We also analyzed the budget impact of publicly funding home NB-UVB phototherapy in people with photoresponsive skin conditions in Ontario. To contextualize the potential value of NB-UVB phototherapy, we spoke with people with photoresponsive skin conditions.

RESULTS

We included one randomized controlled trial in the clinical evidence review. We found that home NB-UVB phototherapy is at least as effective as outpatient clinic NB-UVB phototherapy for the treatment of mild to severe psoriasis (the only photoresponsive skin condition investigated in the included study). In the included study, 82% of participants were treated at home, compared with 79% treated in an outpatient clinic setting (many participants had experience with both treatment settings). They demonstrated an improvement in baseline Psoriasis Area and Severity Index 50 (mean difference 2.8%, 95% confidence interval -8.6% to 14.2%), with the mean difference exceeding the preset noninferiority margin of -15%. Similar results were observed for other psoriasis area and severity indices (GRADE: Moderate). Episodes of mild erythema, burning sensation, severe erythema, and blistering were reported in both treatment groups, but were too few to allow a comparative safety assessment (GRADE: Low).The primary economic evaluation showed that home NB-UVB phototherapy is more costly (incremental cost $4,509) and has higher quality-adjusted life-years (QALYs; incremental QALY 0.29) than outpatient clinic NB-UVB. Our best estimate of the incremental cost-effectiveness ratio of home NB-UVB compared with outpatient clinic NB-UVB is $15,675 per QALY gained. The probability of home NB-UVB being cost-effective versus outpatient clinic NB-UVB is 77% at a willingness-to-pay of $50,000 per QALY gained. Publicly funding home NB-UVB phototherapy in the psoriasis population would lead to about $0.7 million each year and a total 5-year net budget impact of about $3.3 million. Publicly funding home treatment for people with photoresponsive skin conditions would lead to about $1.3 million each year and a total 5-year net budget impact of $6.3 million; however, this scenario accounted for the cost of phototherapy only (it did not include treatment-specific medical costs for conditions other than psoriasis).People with photoresponsive skin conditions with whom we spoke viewed home NB-UVB phototherapy as beneficial for those with health conditions that make it difficult to travel, for those with busy schedules, and for those who may not have the means to pay for travel to clinics.

CONCLUSIONS

Home NB-UVB phototherapy is at least as effective as outpatient clinic NB-UVB phototherapy for the treatment of mild to severe psoriasis (GRADE: Moderate). We are uncertain if adverse events happen more often or less often with home NB-UVB phototherapy than outpatient clinic NB-UVB phototherapy (GRADE: Low).Home NB-UVB phototherapy has an ICER of $15,675 per QALY gained, and the probability of home NB-UVB phototherapy being cost-effective is 77% at a willingness-to-pay of $50,000 per QALY gained. When accounting for the cost of phototherapy and other psoriasis-specific treatment costs (e.g., physician visits and adjuvant treatments), publicly funding home NB-UVB phototherapy in the psoriasis population would lead to a total 5-year net budget impact of about $3.3 million. Funding home NB-UVB phototherapy to people with photoresponsive skin conditions would lead to a total 5-year net budget impact of $6.3 million.People with photoresponsive skin conditions with whom we spoke viewed both outpatient clinic and home NB-UVB phototherapy to be effective treatment options.

A thermal radiation exchange model of whole-body UV phototherapy

A novel model of the skin dose in whole-body UV phototherapy treatment cabins is presented. The model is based on an analysis of the thermal radiation exchange between two surfaces, in this case the UV source and the patient. It is shown to allow analytical treatment of the multiple internal reflections in a treatment cabin that account for around 40% of the skin irradiance. The model provides predictions of the absolute irradiance at the skin and shielding factors in seven different UVA and NB-UVB cabins that are within 6% of those measured using a calibrated radiometer and within 12% for all nine cabins. The model predicts reducing skin irradiances with increasingly patient size, a trend demonstrated in clinical measurements. The exact sensitivity to patient size in automated cabin dosimetry systems, however, varies with in-built sensor positioning. The potential to extend the use of the model to investigate improved design of automated dosimetry systems is discussed.

Safe and effective use of phototherapy and photochemotherapy in the treatment of psoriasis

Psoriasis is a chronic, multisystem inflammatory disease, predominantly affecting the skin and joints, which is present in 2-3% of the world's population. Narrow band ultraviolet B (NB-UVB) and Psoralen + ultraviolet A (PUVA) are recognised, effective and, in the case of UVB, economical second-line treatments for psoriasis where topical therapies fail to control the disease or are an impracticable option due to the extent of skin involvement. This article examines the history of phototherapy and photochemotherapy and looks at current phototherapy treatments used for psoriasis. It discusses side effects of treatment and regimens that can be followed to increase effectiveness of treatment and minimise risks. The role of the nurse phototherapist is also discussed.

Photoadaptation to ultraviolet B TL01 in psoriatic patients

BACKGROUND

In the biologic era, narrow-band ultraviolet B (NB-UVB) phototherapy still remains a valuable, effective, inexpensive, safe anti-psoriatic treatment. Patients can lose response to NB-UVB over time due to photoadaptation. This phenomenon is the tendency of the skin to respond to ultraviolet (UV) exposure by undergoing changes that may result in a decreased future response to an equivalent dose of radiation, thus leading to the need for an increased exposure during phototherapy course.

AIM

To characterize and quantify the determinants of photoadaptation in NB-UVB treated psoriatic patients.

METHODS

We enrolled 57 adult patients with moderate plaque psoriasis. Patients underwent 24 sessions of NB-UVB phototherapy delivered thrice a week. Dosing was started with 70% of the minimal erythema dose (MED) with percentage-based dose increments every two treatments. MED as well as change in the erythema and melanin index (MI) were measured at baseline and at the end of phototherapy course. Moreover, an adaptation factor (AF) was calculated for each patient.

RESULTS

Adaptation factor was not influenced by both baseline MED and skin type. We found a weak correlation between higher cumulative dosages and the initial MED (Spearman's rho = 0.32, P = 0.0154) as well as with the mean initial MI (Spearman's rho = 0.25, P = 0.0624, statistically borderline). Clearance and mean number of treatments were correlated (Spearman's rho = 0.48, P < 0.001).

CONCLUSION

Photoadaptation is a physiological skin response that negatively influences NB-UVB responsiveness and is not predictable by the baseline MED and skin type. Thus, starting with more aggressive protocols and increasing rapidly dosage progression to prevent AF may increase NB-UVB response.

Efficacy and safety of bexarotene combined with photo(chemo)therapy for cutaneous T-cell lymphoma

Cutaneous T‐cell lymphoma (CTCL) is a chronic condition with low malignancy. International treatment guidelines for CTCL are widely followed in Europe and the USA. Combination therapy with therapeutic agents for CTCL and phototherapy is effective on the basis of European data. The efficacy and safety of combination therapy for Japanese CTCL patients are not established. We investigated the efficacy and safety of combination therapy with photo(chemo)therapy and bexarotene in Japanese CTCL patients. Twenty‐five patients received daily oral bexarotene (300 mg/m² body surface), followed by bath‐psoralen plus ultraviolet (UV)‐A (PUVA) or narrowband UV‐B. Treatment results were evaluated using the modified Severity‐Weighted Assessment Tool (mSWAT) and the Physician Global Assessment of Clinical Condition (PGA) up to week 24. Safety was also assessed. Twenty‐four weeks after initiating treatment, the total response rate was 80.0% (mSWAT) and 84.0% (PGA). Response rates did not differ when stratified by disease stage. Number of days (mean ± standard deviation) for time to response, duration of response and time to progression determined by the mSWAT were 20.7 ± 9.62, 117.0 ± 43.0 and 163.6 ± 28.8, respectively. T‐helper 2 chemokine levels in patients at stage IIA or more decreased significantly at weeks 12 and 24. All patients experienced adverse events and adverse drug reactions. Serious adverse drug reactions included sepsis, anemia and congestive cardiac insufficiency (n = 1 each). Other adverse drug reactions were of mild to moderate severity. Combination therapy with bexarotene and PUVA was safe and effective in Japanese CTCL patients.

p-Pyridinyl oxime carbamates: synthesis, DNA binding, DNA photocleaving activity and theoretical photodegradation studies

A number of p-pyridinyl oxime carbamate derivatives were prepared upon the reaction of the corresponding oximes with isocyanates. These novel compounds reacted photochemically in the presence of supercoiled plasmid DNA. Structure-activity relationship (SAR) studies revealed that the substituent on the imine group was not affecting the extend of the DNA damage, whereas the substituent of the carbamate group was critical, with the halogenated derivatives to be able to cause extensive single and double stranded DNA cleavages, acting as "synthetic nucleases", independently of oxygen and pH. Calf thymus-DNA affinity studies showed a good-to-excellent affinity of selected both active and non-active derivatives. Preliminary theoretical studies were performed, in an effort to explain the reasons why some derivatives cause photocleavage and some others not, which were experimentally verified using triplet state activators and quenchers. These theoretical studies seem to allow the prediction of the activity of derivatives able to pass intersystem crossing to their triplet energy state and thus create radicals able to damage DNA. With this study, it is shown that oxime carbamate derivatives have the potential to act as novel effective photobase generating DNA-photocleavers, and are proposed as new leads for "on demand" biotechnological applications in drug discovery and medicine.

Successful treatment of verruca plana with NB-UVB: A case report

Verruca plana is a kind of benign proliferative skin disease that generally occurs in exposed parts, but the treatment of warts poses a therapeutic challenge for physicians, as there is no method, among numerous approaches, that has been proven effective for completely curing this disease. We report a case of verruca plana cured by narrow-band ultraviolet B (NB-UVB), which provides a new treatment of verruca plana.

Is there still a role for UV therapy in itch treatment?

Itching is a frequent and greatly distressing symptom related to many skin and systemic diseases. New insights into the pathophysiology of itchy skin and potentially involved mediators have increased the interest in and development of new treatments that specifically act on targets involved in the transmission and perception of itching. Phototherapy has long been known and used as an effective treatment for various kinds of chronic itching. However, despite its well-known beneficial effects, the mechanisms behind the antipruritic effect of phototherapy are less well-known. In addition, phototherapy requires the use of expensive equipment in dermatology offices, patients must undergo repeated treatments and no large, randomized, controlled trials have yet supported the antipruritic effect of UV. Therefore, phototherapy is rarely recommended as a treatment method for chronic pruritic diseases or only used as a last recourse. However, the wide range of pruritic conditions that can be successfully treated with phototherapy, together with its low acute side effects, extremely low frequency of interactions with other medications, possibilities to combine phototherapy with other treatment modalities and the fact that patients of almost all ages-from childhood to old age, including women during pregnancy or lactation-can be treated make UV therapy advantageous over other treatments of chronic pruritus. Thus, despite the development of new targeted therapies against pruritus, UV therapy is neither outdated nor the 'last recourse', but should be considered early on in the treatment of chronic pruritus.

The photoactivity of natural products - An overlooked potential of phytomedicines?

BACKGROUND

Photoactivity, though known for centuries, is only recently shifting back into focus as a treatment option against cancer and microbial infections. The external factor light is the ingenious key-component of this therapy: Since light activates the drug locally, a high level of selectivity is reached and side effects are avoided. The first reported photoactive medicines were plant extracts. Synthetic entities (so-called photosensitizers PSs), however, paved the route towards the clinical approval of the so-called photodynamic therapy (PDT), and thus natural PSs took a backseat in the past.

HYPOTHESIS

Many isolated bioactive phytochemicals hold a hidden photoactive potential, which is overlooked due to the reduced common awareness of photoactivity.

METHODS

A systematic review of reported natural PSs and their supposed medicinal application was conducted by employing PubMed, Scifinder, and Web of Science. The identified photoactive natural products were compiled including information about their natural sources, their photoyield, and their pharmacological application. Furthermore, the common chemical scaffolds of natural PS are shown to enable the reader to recognize potentially overlooked natural PSs.

RESULTS

The literature review revealed over 100 natural PS, excluding porphyrins. The PSs were classified according to their scaffold. Thereby it was shown that some PS-scaffolds were analyzed in a detailed way, while other classes were only scarcely investigated, which leaves space for future discoveries. In addition, the literature revealed that many PSs are phytoalexins, thus the selection of the starting material significantly matters in order to find new PSs.

CONCLUSION

Photoactive principles are ubiquitous and can be found in various plant extracts. With the increasing availability of light-irradiation setups for the identification of photoactive natural products, we anticipate the discovery of many new natural PSs in the near future. With the accumulation of chemically diverse PSs, PDT itself might finally reach its clinical breakthrough as a promising alternative treatment against multi-resistant microbes and cancer types.

The Antipruritic Effect of Phototherapy

Phototherapy is widely used to treat inflammatory skin diseases such as psoriasis and atopic dermatitis. Repeated suberythemogenic doses of UV-light reduce inflammation in these diseases and ultimately may lead to a complete disappearance of cutaneous symptoms for weeks or months. Chronic pruritus is an important and highly distressing symptom of many of these inflammatory skin diseases. Interestingly, pruritus is also reduced or completely abolished by UV-treatment of psoriasis and atopic dermatitis, and sometimes reduction of pruritus is the first indication for skin improvement by phototherapy. The cutaneous nervous system is an integral part of skin anatomy, and free nerve endings of sensory cutaneous nerve fibers reach up into the epidermis getting in close contact with epidermal cells and mediators from epidermal cells released into the intercellular space. Stimulation of “pruriceptors” within this group of sensory nerve fibers generates a neuronal signal eventually transmitted via the dorsal root and the spinal cord to the brain, where it is recognized as “itch”. UV-light may directly affect cutaneous sensory nerve fibers or, via the release of mediators from cells within the skin, indirectly modulate their function as well as the transmission of itch to the central nervous system inducing the clinically recognized antipruritic effect of phototherapy.