Wavelength dependent generation of singlet oxygen in the UV region of 280 to 400 nm by endogenous photosensitizers in solutions and skin cells

除了阳光不可否认的积极作用外，所含的紫外线辐射还会导致晒伤、皮肤过早老化和皮肤癌。体外研究和评估的潜在损伤机制通常在各自的光谱区域UVA(320-400 nm)和UVB(280-320 nm)中分开。UVB辐射直接被DNA吸收，并通过形成环丁烷、嘧啶二聚体和嘧啶二聚体对皮肤细胞造成损害。然而，UVA辐射(340-400 nm)被细胞中的其他分子(内源性光敏剂)吸收，吸收的能量可以转移到分子氧。这种高活性的单线态氧是暂时形成的，在皮肤细胞中引起氧化损伤和调节作用。初步结果表明，无论是在纯辐射吸收(UVB)还是氧化损伤(UVA)中，这种分离都难以维持。此外，UVB辐射可以产生单线态氧，其中维生素和脂肪酸作为内源性光敏剂参与其中。目前尚不清楚UVB辐射在多大程度上会在皮肤细胞中产生单线态氧，以及这在细胞损伤机制中扮演什么角色。此外，研究还表明，内源性光敏剂在UVA或UVB辐射下产生单线态氧的能力发生了显著变化。首先，利用发光光谱研究了尚未检测到的内源光敏剂在较短波长(280-340 nm)下产生单线态氧的程度。此外，还应澄清细胞中已知的损伤机制是否受到影响。其次，将研究紫外线辐射在多大程度上对辐射过程中的内源性光敏剂进行化学修饰，以及它们产生单线态氧的效率。因此，光敏剂应单独、顺序或并行地用UVA或UVB照射。这些步骤是按照在溶液中以及在体外对角质形成细胞和成纤维细胞的要求进行的。第三，在不同的照射条件下，基质金属蛋白酶、白介素酶和MAP激酶的调节与单线态氧的产生有关，在执行这些步骤后，需要弄清楚整个紫外光光谱中单线态氧的产生是否以及在多大程度上对细胞造成损伤。此外，通过UVA和UVB(如阳光)的平行照射以及照射过程中内源性光敏剂的光化学变化，单线态氧在细胞损伤模式中的作用将在多大程度上得到重新评估。

In addition to the undeniably positive effects of sunlight, the contained ultraviolet radiation can cause sunburn, premature skin aging and skin cancer. The underlying damage mechanisms investigated and evaluated in vitro are generally separated in the respective spectral areas UVA (320-400 nm) and UVB (280-320 nm). The UVB radiation is absorbed directly by DNA and causes damage to the skin cells by the formation of cyclobutane pyrimidine dimers and pyrimidine pyrimidone photoproducts. UVA radiation (340-400 nm), however, is absorbed by other molecules (endogenous photosensitizers) in the cells, where the absorbed energy can be transferred to molecular oxygen. This highly reactive singlet oxygen is formed temporarily, which causes oxidative damage as well as regulatory effects in the skin cells.Preliminary results have shown that the separation in either pure radiation absorption (UVB) or oxidative damage (UVA) is so not to maintain. Also UVB radiation can produce singlet oxygen, and here among others vitamins and fatty acids are involved as endogenous photosensitizers. To what extent UVB radiation generates singlet oxygen in skin cells and what role this plays for the cellular damage mechanisms, is currently not known. In addition, it was shown that endogenous photosensitizers irradiated by UVA or UVB radiation change their ability to generate singlet oxygen the significantly.First, by using luminescence spectroscopy, it will be investigated, to what extent singlet oxygen can be created at shorter wavelengths (280-340 nm) by not yet examined endogenous photosensitizers. Also, it shall be clarified whether the known damage mechanisms in cells are affected. Second, it will be investigated to what extent UV radiation chemically modifies the endogenous photosensitizers during irradiation, as well as their efficaccy to generate singlet oxygen. Therefore, the photosensitizers should be irradiated with UVA or UVB individually, sequentially or in parallel. These steps are carried out according to the requirements in solution and on keratinocytes and fibroblasts in vitro. Third, the regulation of Matrix Metallo Proteinases, Interleukins and MAP kinases are correlated with the generation of singlet oxygen under the various irradiation conditions.After performing these steps, it should be clarified whether and to what extent the production of singlet oxygen in the entire UV spectrum contributes to the damage of cells. Further it should be clarified to what extent by parallel irradiation with UVA and UVB (such as sunlight) and the photochemical change of endogenous photosensitizers during irradiation, the role of singlet oxygen is to re-evaluate in the cellular damage patterns.