The effects of UV waveband and cis-urocanic acid on tumour outgrowth in mice

The safety and efficacy of light emitting diodes-based ultraviolet A1 phototherapy in bleomycin-induced scleroderma in mice

PURPOSE

To define the efficacy and safety of narrowband ultraviolet A1 (UVA1) for the treatment of dermal fibrosis in bleomycin-induced mouse model of scleroderma.

MATERIALS AND METHODS

42 DBA/2 strain mice were included in the study: healthy mice and mice with established scleroderma, treated with high or medium dose of UVA1. Non-treated groups served as control. The equipment emitting 365±5nm UVA1 radiation was used in the study. The average cumulative doses were 1200J/cm² for high and 600J/cm² for medium dose course. Histological analysis was performed for the evaluation of the dermal thickness and mast cells density. The expressions of p53 and Ki-67 proteins were assessed by immunohistochemical analyses.

RESULTS

Skin thickness of mice with scleroderma, treated with high and medium dose of UVA1, were lower (272.9±113.2μm and 394±125.9μm, respectively) in comparison to the dermal thickness of non-treated animals (599±55.7μm). The dermal mast cells count in mice with scleroderma was reduced after high and medium dose treatment to 11±1.7 and 13±2.2, respectively, as compared to that in non-treated mice (23±3.0). No significant upregulation of p53 nor Ki-67 proteins was observed in the skin of healthy mice and mice with scleroderma after high- and medium-dose of UVA1.

CONCLUSIONS

The results of this study indicate that 365nm UVA1 with the cumulative doses of 1200J/cm² and 600J/cm² is safe and effective for the dermal fibrosis treatment.

Effects of narrow band UVB (311 nm) irradiation on epidermal cells

Ultraviolet radiation (UVR) is known to be one of the most important environmental hazards acting on the skin. It was revealed that chronic exposure to UVR accelerates skin aging, induces immunosuppression and may lead to the development of skin cancers. On the other hand, UVR has been shown to be effective in the treatment of numerous skin diseases and thus, various phototherapy modalities have been developed to date. Narrow-band ultraviolet B (NB-UVB) emitting a light with a peak around 311 nm has been demonstrated to be effective in the treatment of various skin disorders; currently it is one of the most commonly used phototherapy devices. Despite NB-UVB has been developed more than 30 years ago, the exact mechanism of its therapeutic action remains poorly understood. To date, most of NB-UVB effects were attributed to its influence on immune cells; however, nearly 90% of NB-UVB irradiation is absorbed by epidermis and keratinocytes seem to be important players in mediating NB-UVB biological activity. Here, we have reviewed the current data about the influence of NB-UVB on epidermal cells, with a special emphasis on cell proliferation and death.

Modern aspects of phototherapy for atopic dermatitis

Phototherapy has still great importance in the treatment of atopic dermatitis, though costs, compliance, and long-term risks narrow its relevance. In spite of its long history, up to now, the therapeutic regimes are mostly empirical. Narrowband UVB und UVA1 are the most frequently applied regimens in atopic dermatitis with proven efficacy. However, even for these modalities randomized prospective and controlled studies are still pending. Advances in photoimmunology and molecular biology had demonstrated that phototherapy targets inflammatory cells, alters cytokine production, and has a significant antimicrobial effect within atopic skin. This paper summarizes the current literature on the different regimes of phototherapy and also discusses therapeutic modalities like photochemotherapy and extracorporeal photopheresis. These more complex regimes should be restricted to severe cases of atopic dermatitis, which are refractory to topical treatment.

Lipidome of narrow-band ultraviolet B irradiated keratinocytes shows apoptotic hallmarks

BACKGROUND

UV light triggers a variety of biological responses in irradiated keratinocytes that might be associated with global perturbation of their lipidome. However, lipids that are specifically affected and the exact molecular mechanisms involved remain poorly understood.

OBJECTIVES

To characterize time-dependent changes of the lipidome of cultured keratinocytes induced by narrow-band ultraviolet B (NB-UVB) irradiation.

METHODS

Immortalized human keratinocytes (HaCaT) were cultured under standard conditions, irradiated with NB-UVB light (311 nm) at 400 and 800 mJ/cm(2) and collected 1, 2, 3, 6, 12 and 24 h later for lipid extraction. Lipid extracts were separated on silica plates in chloroform/ethanol/water/triethylamine (35:40:9:35) and in n-hexane/ethylacetate (5:1) followed by quantitative shotgun lipidomics analysis.

RESULTS

Irradiation with 800 mJ/cm(2) of NB-UVB altered morphology and lipidome composition of HaCaT cells. Ceramide content increased two-fold 6- and 12-h postirradiation with 800 mJ/cm(2), followed by threefold increase in triacylglycerols (TAGs) that peaked at 24 h. In addition, we observed marked increase of various phosphatidylcholine and phosphatidylethanolamine ethers, whereas phosphatidylcholine-species with short-chain fatty acid moieties decreased. The abundance of other lipid species was altered to lesser extent or remained unchanged.

CONCLUSIONS

NB-UVB affected the cellular lipidome of keratinocytes in strictly apoptosis-specific manner.

Recent advances in urocanic acid photochemistry, photobiology and photoimmunology

Urocanic acid (UCA), produced in the upper layers of mammalian skin, is a major absorber of ultraviolet radiation (UVR). Originally thought to be a 'natural sunscreen', studies conducted a quarter of a century ago proposed that UCA may be a chromophore for the immunosuppression that follows exposure to UVR. With its intriguing photochemistry, its role in immunosuppression and skin cancer development, and skin barrier function, UCA continues to be the subject of intense research effort. This review summarises the photochemical, photobiological and photoimmunological findings regarding UCA, published since 1998.

[New and established indications for phototherapy with narrowband UVB]

Phototherapy with ultraviolet (UV) irradiation of wavelengths between 280 and 320 nm (UV-B) is a safe and effective treatment for a variety of inflammatory skin diseases. In addition to standard broad band UVB, narrow band phototherapy with fluorescent bulbs emitting near monochromatic UV between 310-315 nm has become an important treatment for diseases such as psoriasis, atopic dermatitis or vitiligo. Other diseases respond favorably to narrow band UV-B phototherapy, the number of potential indications for such phototherapy is continuously growing. The differential effects of narrow band UV-B phototherapy in comparison to other UV phototherapies, as well as new and established indications for this treatment modality are reviewed.

Phototherapy with narrowband vs broadband UVB

Phototherapy with ultraviolet (UV) radiation of wavelengths between 280 and 320 nm (UVB) is a safe and effective treatment for a variety of diseases. In addition to standard broadband UVB (bUVB), narrowband phototherapy with fluorescent bulbs emitting near monochromatic UV around 311 nm (nUVB) has become an important treatment for diseases such as psoriasis, atopic dermatitis and vitiligo. In addition to these indications, the number of diseases for which nUVB phototherapy is reported to be effective is continuously growing. The differential effects of nUVB phototherapy in comparison to other UV wavelengths as well as established and new indications for this treatment modality are reviewed.