Quality of platelet concentrates irradiated with UVB light: effect of UV dose and dose rate on glycocalicin release and correlation with other markers of the platelet storage lesion

Summary. The amount of membrane-associated glycoprotein Ib in platelet concentrates (PCs) irradiated with a high dose of UVB light has been shown to be significantly reduced after 48 h storage. We recently corroborated this finding when we noted an increase in the supernatant levels of glycocalicin (GC, a major segment of glycoprotein Ib) in UVB-treated PCs during storage. The aim of the present study was to determine whether GC release was related to both the UV dose and the rate of dose delivery. Plateletpheresis concentrates obtained from five donors were pooled and split into five equal parts. Four of these were treated with 7500 and 15000 mJ/cm² UVB using two prototype UV sources with differing rates of dose delivery; namely, Baxter (BAT) and British Aerospace (BAC) cabinets, with the latter having the slower rate of delivery. On days 1 and 5 of storage, GC levels in the supernatants of PCs were determined by ELISA. Moreover, the following parameters were also assessed: platelet and WBC count; hypotonic shock response (HSR) and platelet aggregation response to ADP, ADP +collagen, ADP + arachidonic acid and ristocetin; pH; supernatant levels of lactate, glucose, von Willebrand factor (vWf) and β-thrornboglobulin (βTG). The results revealed an association of GC release with UVB dose using both UV sources, although this was more apparent in the BAC system, in which glycocalicin release at day 5 of storage was as follows (μg/ml, mean ± SD): 4·8±0·3 and 9·5±3·6 at 7500 and 15000 mJ/cm² respectively. Moreover, at 15000 mJ/cm², PCs treated in the BAC system exhibited significantly higher levels of GC than those treated in the BAT system: 9·5±3·6 and 4·8± 3·6 respectively at day 5 of storage (P= 0·05). This differential GC increase in the BAC was coupled with a decrease in HSR and a significant increase in lactate and βTG levels compared with the BAT system. In contrast to the GC results, vWf supernatant levels in PCs treated with UVB were decreased relative to non-treated PCs of the same origin. Moreover, GC release correlated significantly with various standard tests of platelet function indicating its importance as a quality indicator for the investigation of the platelet storage lesion. Our results show that UVB not only increases GC release in a dose/rate-dependent manner but that it may also affect the quality of irradiated PCs and their shelf life.     

中波紫外线对人角质形成细胞MMP-9 mRNA的影响

目的：研究中波紫外线（UVB）诱导的永生化人角质形成细胞中MMP-9 mRNA的表达,探讨其与UVB照射所致的细胞损伤的关系。方法：绘制细胞生长曲线,采用MTT方法测定UVB照射后细胞的增殖活性,反转录-聚合酶链反应（RT-PCR）方法测定UVB照射后HaCaT细胞中MMP-9 mRNA的表达。结果：UVB照射后,HaCaT细胞的增殖活性受到抑制,MMP-9 mRNA表达增强;随UVB剂量增加,照射组的MMP-9 mRNA表达逐渐增多,与未照光组比较,差异有统计学意义（P〈0.01）。结论：UVB照射可引起HaCaT细胞中MMP-9 mRNA表达显著增加,且与UVB照射剂量呈正相关,与光老化的发生有一定的关系。     

UV-based therapy and vitamin D

The ultraviolet (UV) light spectrum has long been known to induce biologic effect on the skin. For a large number of cutaneous disorders, phototherapy and photochemotherapy are effective therapeutic options with excellent safety profiles and well-documented side effects. Despite their ease of administration and benefits, phototherapeutic treatment modalities require appropriate space for the equipment, trained staff, and patient education prior to initiating treatment. However, when the initial barriers to treatment can be overcome, UV therapy can offer patients significant relief from their cutaneous disease. Furthermore, UVB-based phototherapy can produce significant alteration to vitamin D levels. With the recent research implicating association of low vitamin D levels with a variety of health conditions, whether patients receiving phototherapy or, more specifically, those getting vitamin D supplement may be protected from these diseases remains to be established.     

中波紫外线照射对表皮朗格汉斯细胞p53蛋白磷酸化表达的影响

目的：研究皮肤朗格汉斯（Langerhans）细胞（LC）在不同剂量中波紫外线（UVB）照射前、后p53蛋白磷酸化水平的差异。方法：联合采用密度梯度离心和免疫磁珠的方法分离纯化LC，将LC分为实验组和对照组，实验组分别接受30、60和90mJ／cm^2 UVB辐射，辐射后4h提取总蛋白，采用Western—blotting法检测各组细胞中p53蛋白及磷酸化p53蛋白的表达量，并比较两者之间的差异。结果：接受UVB辐射后，皮肤LC中p53蛋白表达基本无变化，而p53蛋白磷酸化水平显著升高，差异具有统计学意义，并呈剂量依赖性。结论：UVB辐射可刺激p53蛋白磷酸化，并呈剂量依赖性，进而诱导p53蛋白活化，发挥其下游功能。     

Identification of p53-dependent genes potentially involved in UVB-mediated premature senescence of human skin fibroblasts using siRNA technology

Premature senescence of skin human diploid fibroblasts is induced after a series of 10 sublethal exposures to UVB at 2.5 kJ/m(2) with appearance of several biomarkers of cellular senescence like senescence-associated beta-galactosidase activity (SA beta-gal) and cell cycle arrest. Herein it is shown that the induction of UVB-induced premature senescence is associated with a transient increase of protein abundance and DNA-binding activity of p53. Silencing p53 expression with small interfering RNA (siRNA) affected the basal level of SA beta-gal and proliferative potential, but did not prevent UVB-induced increase of SA beta-gal and decrease of DNA synthesis. We used a senescence-specific low-density DNA array and p53 siRNA to study the mRNA abundance of 240 senescence-related genes and identified several potential p53-dependent genes differentially expressed after the repeated exposures to UVB.     

Protective role of histone deacetylase 4 from ultraviolet radiation-induced DNA lesions

Ultraviolet B (UVB) exposure is a core factor that leads to skin disease or carcinogenesis through the insufficient repair of DNA lesions. UVB-induced DNA lesions are mainly removed by the nucleotide excision repair (NER) mechanism. The expression of histone deacetylase 4 (HDAC4) is altered in the skin upon UVB exposure, indicating its possible implication in UVB-induced DNA lesions repair. Here, we investigated the role of HDAC4 in the NER removal of the main classes of UVB-induced DNA lesions consisting of cyclobutane pyrimidine dimers and pyrimidine (6-4) pyrimidone photoproducts (6-4PPs). We found that UVB irradiation increased HDAC4 expression at both the mRNA and protein levels. HDAC4 interacted with NER factor XPC, which played an important role in effectively removing the UVB-induced DNA lesions. This study provides an understanding of the HDAC4 function in DNA repair, which will allow the development of efficient strategies to protect the skin from UVR-induced diseases.     

The effects of UVB irradiance on vitiligo phototherapy and UVB-induced photocarcinogenesis

Phototherapy is the most commonly used modality for repigmenting vitiligo. Currently, UVB emitting devices, including narrow-band UVB (NBUVB) and excimer laser/light, are considered as the treatment of choice. While emitting wavelengths at close proximity, excimer lights emit higher irradiance (HI; W/m²) compared to NBUVB. Clinical reports have shown that excimer light is more efficacious in treating vitiligo compared to NBUVB, and we demonstrated that irradiance plays a critical role in promoting melanoblasts differentiation. UVB radiation from the sun is closely associated with photocarcinogenesis of the skin. Sunscreens were used to protect the skin by reducing UVB irradiance (low irradiance (LI) UVB). Sunscreen use was associated with skin cancer reduction in clinical trials. Paradoxically, sunscreen use was associated with increased sunburn episodes in the real-world settings. It was shown that UVB-induced sunburn depends on fluence (J/m²) but not irradiance of UVB radiation. We investigated the significance of irradiance in the context of UVB-induced carcinogenesis of the skin. For mice receiving equivalent fluence of UVB exposure, the LIUVB-treated mice showed earlier tumor development, larger tumor burden, and more epidermal keratinocytes harboring mutant p53 as compared to their HIUVB-treated counterparts. These results suggested that at equivalent fluence, LIUVB radiation has more photocarcinogenic potential on the skin compared to its HI counterpart. Since development of sunburn with or without sunscreen use indicates that certain threshold of UVB fluence has been received by the skin at LI and HI, respectively, sunburn episodes with sunscreen use (LIUVB) are more damaging to the skin compared to that without sunscreen (HIUVB) application. In summary, since irradiance plays an important role determining the biological effects of UVB radiation on the skin, future related studies should take this critical parameter into consideration.     

P38 and JNK signal pathways are involved in the regulation of phlorizin against UVB‐induced skin damage

Phlorizin is well known to inhibit sodium/glucose cotransporters in the kidney and intestine for the treatment of diabetes, obesity and stress hyperglycaemia. However, the effects of phlorizin against ultraviolet B (UVB) irradiation and its molecular mechanism are still unknown. We examined the effects of phlorizin on skin keratinocyte apoptosis, reactive oxygen species (ROS) production, pro‐inflammatory responses after UVB irradiation and the changes of some signal molecules by in vitro and in vivo assay. We observed that phlorizin pretreatments inhibited HaCaT cell apoptosis and overproduction of ROS induced by UVB. Phlorizin also decreased the expression of UVB‐induced pro‐inflammatory cytokines, such as interleukin‐1 beta (IL‐1β), interleukin‐6 (IL‐6) and interleukin‐8 (IL‐8) at the mRNA level. Topical application of phlorizin on UVB‐exposed skin of nude mice prevented the formation of scaly skin and erythema, inhibited the increase of epidermal thickness and reduced acute inflammation infiltration in skin. Additionally, PCR, Western blot and immunohistochemical data showed that phlorizin reversed the overexpression of cyclooxygenase‐2 (Cox‐2) induced by UVB irradiation both in vitro and in vivo. The activation of p38 and JNK mitogen‐activated protein kinases (MAPK) after UVB irradiation was also inhibited by phlorizin. These findings suggest that phlorizin is effective in protecting skin against UVB‐induced skin damage by decreasing ROS overproduction, Cox‐2 expression and the subsequent excessive inflammation reactions. It seemed that p38 and JNK MAPK signal pathways are involved in the regulation of the protective function of phlorizin.     

Radiofrequency irradiation attenuates angiogenesis and inflammation in UVB-induced rosacea in mouse skin

Rosacea is a skin inflammatory condition accompanied by cutaneous signs such as oedema, flushing, erythema, telangiectasia and pustules. Generally, rosacea is triggered by ultraviolet B (UVB) exposure. When exposed to UVB, skin epidermis thickens and produces elevated levels of pro-inflammatory cytokines, especially keratinocyte-related VEGF, a potent angiogenic factor. The upregulations of VEGF expression and its secretion promote the formation of new blood vessels and exacerbates rosacea. In this study, radiofrequency (RF) irradiation reduced keratinocyte proliferation in the epidermal layer, the expressions of pro-inflammatory cytokines, angiogenesis-related inflammatory factors and VEGF in our UVB-induced model of rosacea in vitro and in vivo. RF irradiation attenuated VEGF-induced angiogenesis-associated processes such as tube formation, cell migration and endothelial cell proliferation. Notably, blood vessel densities in the skins of UVB-treated mice and rosacea patients were significantly decreased by RF irradiation. These results provide experimental and molecular evidence regarding the effectiveness of RF irradiation for the treatment of rosacea.