A comparative study of UV-induced cell signalling pathways in human keratinocyte-derived cell lines

Ultraviolet (UV) radiation can activate the p38 mitogen-activated protein kinase (MAPK), Jun N-terminal kinase (JNK) and nuclear factor-κB (NFκB) pathways in skin cells. HaCaT cells are widely used as a primary keratinocyte substitute to study these pathways. However, like most squamous cell carcinomas (SCCs), it contains a dysfunctional p53. It is unclear if HaCaT cells activate these signalling pathways similarly to SCC cells (Colo16) or to primary human epidermal keratinocytes (HEK). In this study, the UV activation (UVA, UVB, UVA + B, UVB + A) of p38 MAPK, JNK and NFκB pathways, and TNFα secretion by HEK, HaCaT and Colo16 cells were investigated. The signalling pathway activation was UV-type and dose-dependent with UVB + A radiation inducing a high p38 and JNK activation. HaCaT cells exhibited 2- to 4-fold higher activity of the p38 (771 % at 60 min) and JNK (794 % at 30 min) pathways following UVB + A radiation than did HEK cells (p38: 367 % at 15 min and JNK: 184 % at 30 min). While both HaCaT and Colo16 cells did not activate the NFκB pathway, Colo16 cells had a lower p38 and higher JNK activity than HaCaT cells. Irradiated HaCaT cells produced less TNFα (UVB: 3.5 pg/ml), while HEK cells produced the most (UVB: 1,296 pg/ml). When co-exposed to IL1α, irradiated HaCaT had the greatest fold of TNFα release (UVB: 16.2-fold, UVA + B: 8.9-fold and UVB + A: 6.1-fold). The pattern of activation and TNFα secretion of HaCaT cells mirrored that of Colo16 cells. It is likely that the presence of molecular alterations in HaCaT cells may be responsible for its different responses to that seen for HEK cells. The results of this study suggest caution in using HaCaT cells as a substitute for normal keratinocytes in investigating UV-induced cells signalling pathways.     

Gene expression profiles of TNF-alpha, TACE, furin, IL-1beta and matrilysin in UVA- and UVB-irradiated HaCat cells

BACKGROUND/PURPOSE: It is known that solar ultraviolet (UV) irradiation exerts multiple effects on mammalian skin tissues, one of which is the induction of local and systemic immunosuppression as well as inflammation. Tumor necrosis factor-alpha (TNF-alpha) and other cytokines are suggested to play a role in these responses. Quantitative real-time polymerase chain reaction (TaqMan RTPCR) was used to elucidate the effect of UVA and UVB irradiation on the expression of genes coding for TNF-alpha, IL-1beta, IL-10, FasL, matrilysin, TACE and furin in HaCaT cells over a 48 h period (IL-1beta, interleukin-1beta; FasL, Fas ligand). METHODS: Cultured HaCaT cells were either sham irradiated (control) or exposed to UVA (2000 and 8000 J/m2) or UVB (200 and 2000 J/m2) radiation. RNA was extracted from cells at 0, 4, 8, 12, 16, 24, 48 h post-irradiation and reverse transcribed to generate cDNA for subsequent real-time PCR amplification. RESULTS: Significant increases in the mRNA levels for all genes tested were detected in both UVA- and UVB-irradiated HaCaT cells compared with control (sham-irradiated) cells. TNF-alpha mRNA levels were immediately up-regulated (0 h) after irradiation, with maximal induction at 8 h post 2000 J/m2 UVA and 200 J/m2 UVB irradiation, at 4 h post 8000 J UVA irradiation and at 48 h post 2000 J/m2 UVB irradiation. No correlation was observed between TNF-alpha, TACE and furin mRNA induction in the different irradiated cohorts. CONCLUSION: Results suggest that time-distinct gene induction of TNF-alpha, furin, IL-1beta and matrilysin may be involved in UV-induced cellular responses, but not for TACE. In general, mRNA induction was dose dependent at some time points post-irradiation, but not throughout the whole time course tested. Our results show that quantitative real-time PCR is a useful tool in the analysis of quantitative changes of mRNA levels in cultured HaCaT cells after UV exposure.     

姜黄素对紫外线诱导损伤的HaCaT细胞的保护作用

目的比较姜黄素对UVA、UVB急性损伤的HaCaT细胞的保护作用。方法体外培养人永生化角质形成细胞株HaCaT细胞,UVA、UVB照射建立HaCaT细胞急性光损伤模型。姜黄素与HaCaT细胞共培养24 h后,MTT法检测细胞增殖能力,流式细胞仪检测细胞凋亡情况,确定无毒性姜黄素浓度。通过MTT法、流式细胞术分别检测添加姜黄素前后,UVA、UVB照射引起的HaCaT细胞损伤情况及胞内活性氧(Reactive oxygen species,ROS)水平变化。结果姜黄素浓度在5μmol/L以下时,正常细胞的增殖和凋亡不受影响。添加姜黄素前,UVA照射引起细胞增殖抑制、凋亡增加(P0.05),ROS增高67.9%;UVB照射引起细胞增殖抑制、凋亡增加(P0.05),ROS增高67.2%。添加姜黄素后,UVA、UVB组细胞损伤均减轻(P0.05),ROS水平升幅均下降,呈浓度依赖型。结论对于不同波长的紫外线诱导损伤的HaCaT细胞,姜黄素均可降低急性光损伤引起ROS水平升幅,具有抗氧化保护作用,其保护强度无差异,并且呈浓度依耐性。     

Caspase-3、Survivin在UVB诱导HaCaT凋亡细胞中的表达

目的探讨Caspase-3、Survivin在UVB诱导HaCaT凋亡细胞中的作用。方法研究对象为人角质形成细胞HaCaT细胞,实验分为正常对照组、10、20、40、80 m J/cm^2中波紫外线组(UVB)。四甲基偶氮唑蓝(MTT)比色法观察增殖能力;流式细胞仅(FCM)实验检测细胞凋亡;实时定量PCR、Western-blot检测细胞内的Survivin、Caspase-3表达水平。结果与正常对照组相比,NB-UVB照射组细胞增殖抑制作用及凋亡明显增强(P<0.05),并随着照射剂量的增加,其细胞凋亡作用增加。同时与正常对照组相比,不同UVB照射剂量组Caspase-3表达均增强,其表达增强程度随着照射剂量的增加而增加,与正常对照组相比,10 m J/cm^2照射组,细胞表达Survivin水平最高(P<0.05),20 m J/cm^2组Survivin表达水平下降,稍低于对照组水平,40、80 m J/cm^2组Survivin进一步下降,较对照组下降明显(P<0.05)。结论 Survivin、Caspase-3参与了UVB诱导HaCaT凋亡细胞。Survivin表达水平与UVB辐射剂量有关。     

紫外线对HaCaT细胞中瞬时受体电位锚蛋白1的影响

目的 探讨HaCaT细胞中瞬时受体电位锚蛋白1(TRPA1)的光控作用及其机制.方法 培养的HaCaT细胞分为225 mJ/cm2 UVA刺激组和25 mJ/cm2UVB刺激组,UVA刺激组分为空白对照组(仅有HaCaT细胞)、视黄醛组、UVA组、视黄醛+UVA组(UVA-TRPA1对照组)、视黄醛+UVA+肉桂醛组(UVA-TRPA1激动组)、视黄醛+UVA+樟脑组(UVA-TRPA1抑制组);UVB刺激组分为空白对照组(仅有HaCaT细胞)、视黄醛组、UVB组、视黄醛+UVB组(UVB-TRPA1对照组)、视黄醛+ UVB+肉桂醛组(UVB-TRPA1激动组)、视黄醛+UVB+樟脑组(UVB-TRPA1抑制组).qPCR、Western印迹检测HaCaT细胞中TRPA1的表达.流式细胞仪检测各组HaCaT细胞钙离子内流的变化.结果 qPCR和Western印迹显示,HaCaT细胞中有TRPA1 mRNA及蛋白的表达.UVA作用后空白对照组、视黄醛组、UVA组、视黄醛+UVA组荧光强度分别为155.06±7.62、148.37±18.77、166.92±3.71、331.333±40.563,组间差异有统计学意义(F=44.509,P＜0.01).UVB作用后空白对照组、视黄醛组、UVB组、视黄醛+UVB组荧光强度分别为150.20±1.73、171.66±56.23、147.56±6.60、250.44±9.13,组间差异有统计学意义(F=85.261,P＜ 0.01),视黄醛+UVA/UVB组荧光强度均高于空白对照组(q值分别为18.442、6.052,P＜0.01).TRPA1激动剂和拮抗剂可调节UVA、UVB所引起的钙离子内流的变化(P＜ 0.001),在UVA、UVB作用下,TRPA1激动剂组荧光强度均高于对照组(q值分别为14.934、32.770,P＜0.001),TRPA1抑制剂组荧光强度均低于对照组(q值分别为7.986、14.596,P＜0.001).结论 TRPA1在皮肤HaCaT细胞中有表达,UVA或UVB可通过TRPA1调控HaCaT细胞的钙离子内流.     

枸杞多糖粗提物对紫外线诱导HaCaT细胞清除活性氧的影响

目的 探讨枸杞多糖粗提物对紫外线诱导的HaCaT细胞清除活性氧(ROS)的影响及可能机制.方法 将HaCaT细胞分为空白组、枸杞多糖组、UVA组、UVB组、UVA+枸杞多糖组、UVB+枸杞多糖组.用噻唑蓝法检测细胞增殖活性;分光光度计检测枸杞多糖粗提物对UVA和UVB吸收情况;用DCFH-DA荧光探针检测细胞内ROS水平;酶生化法测定胞质超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性及乳酸脱氢酶(LDH)漏出量.结果 0、100、200、300、400、500、600、1 500、2 000 mg/L枸杞多糖粗提物对HaCaT细胞增殖活性无明显影响.枸杞多糖粗提物对280 ～400 nm紫外线透光率较大;与空白组比较,UVA和UVB组LDH漏出量、ROS水平显著升高,胞内SOD及GSH-Px活力降低,差异均有统计学意义(P＜0.001或0.05).照射前加枸杞多糖粗提物(UVA+枸杞多糖组、UVB+枸杞多糖组)可明显升高细胞内SOD、GSH-Px活性,减少LDH释放,降低ROS水平,与UVA或UVB组比较,差异均有统计学意义(P＜0.05).结论 枸杞多糖粗提物不具有遮光剂的作用,但可有效清除ROS,降低LDH漏出率,抑制紫外线致HaCaT细胞光损伤,可能与其增强抗氧化酶活性有关.     

紫外线辐射前后HaCaT及人成纤维细胞分子伴侣蛋白质组的差异分析

目的初步探讨紫外线辐射所致皮肤细胞分子伴侣蛋白质组整体变化规律。方法分别提取30mJ/cm2UVB照射前后角质形成细胞HaCaT株和10J/cm2UVA照射前后成纤维细胞的总蛋白,采用固相pH梯度双向凝胶电泳技术进行分离,经Imaging Master 2D软件分析以发现差异表达蛋白,并对部分差异表达蛋白进行基质辅助激光解吸电离飞行时间(MALDI-TOF)质谱分析,测定其肽质量指纹图谱,在网上蛋白质数据库检索鉴定差异蛋白。采用Western免疫印迹法对部分质谱鉴定的差异蛋白做进一步验证。结果获得良好的双向电泳图谱,图像分析显示在紫外线辐射前后很多蛋白质发生差异表达,对差异表达的部分蛋白点进行肽质量指纹图谱分析,经Mascot软件检索人非冗余蛋白质数据库后,在UVB辐射后角质形成细胞中鉴定出3个表达显著增加的分子伴侣蛋白:热休克蛋白70KDa 9B、热休克蛋白60KDa和PHB;在UVA辐射后成纤维细胞中鉴定出4个表达显著增加的分子伴侣蛋白:热休克蛋白70KDa A5、热休克蛋白70KDa9B、蛋白二硫键异构酶和PHB。Western免疫印迹法进一步验证上述结果。对这些蛋白的功能和与紫外线辐射的可能关系进行了初步探讨。结论紫外线辐射可以诱导皮肤细胞分子伴侣蛋白质组发生改变,而这些蛋白的变化可能与皮肤细胞应对紫外线辐射并清除其损伤相关。     

Dynamics of pigmentation induction by repeated ultraviolet exposures: dose, dose interval and ultraviolet spectrum dependence

Background The dynamics of ultraviolet (UV)‐induced melanogenesis have been well characterized for single UV exposures. However, our knowledge of the effects of repeated UV exposures on the development of new pigmentation is limited. Objectives To characterize the dynamics and dose dependence of pigmentation induction by repeated UV exposures using two different UV sources. Methods A total of 40 healthy subjects participated in the study: 21 were exposed to a 5% UVB/95% UVA source and 19 were exposed to a 2% UVB/98% UVA source. Skin phototypes 2–3 were represented. Subjects were exposed one to three times per week. The minimal erythemal dose and minimal melanogenic dose of all subjects were determined, and both visual and instrumental observations of the development of pigmentation and erythema were recorded. Results Dark‐brown pigmentation could be produced by a cumulative UV dose of 4200 J m^?2 given as 10 exposures over 5 weeks. However, comparable pigmentation could also be induced by a cumulative dose of 2900 J m^?2 given as eight exposures over 4 weeks. The lowest cumulative dose of 1900 J m^?2 given over 4 weeks produced moderate pigmentation. The 2% UVB source led to earlier and darker pigmentation than the 5% UVB source did for equally erythemogenic doses. Conclusions These observations show that the dynamics of melanogenesis induced by repeated exposures depends on UV dose, dose interval and emission spectrum. They also indicate that increasing the UV dose above a certain level of cumulative exposure does not significantly increase the level of UV‐induced pigmentation.     

Ultraviolet B radiation regulates cysteine‐rich protein 1 in human keratinocytes

Background: Cysteine‐rich protein 1 (CRP1) is a growth‐inhibitory cytoskeletal protein that is induced by ultraviolet (UV) C radiation radiation in fibroblasts. Our aim was to investigate the effects of UV radiation on CRP1 in keratinocytes, the main cell type subjected to UV radiation in the human body. Methods: The effects of physiologically relevant doses of UVB radiation on CRP1 protein levels were studied in cultured primary keratinocytes and transformed cell lines (HaCaT, A‐431) by immunoblotting. UVB‐induced keratinocyte apoptosis was assessed by flow cytometry and monitoring caspase activity. Expression of CRP1 in human skin in vivo was studied by immunohistochemistry in samples of normal skin, actinic keratosis (AK) representing UV‐damaged skin and squamous cell carcinoma (SCC), a UV‐induced skin cancer. Results: CRP1 expression increased by UVB radiation in primary but not in immortalized keratinocytes. Upon high, apoptosis‐inducing doses of UV radiation, CRP1 was cleaved in a caspase‐dependent manner. In normal skin, CRP1 was expressed in smooth muscle cells, vasculature, sweat glands, sebaceous glands and hair root sheath, but very little CRP1 was present in keratinocytes. CRP1 expression was elevated in basal cells in AK but not in SCC. Conclusion: CRP1 expression is regulated by UVB in human keratinocytes, suggesting a role for CRP1 in the phototoxic responses of human skin.     

Eruptive papules during efalizumab (anti-CD11a) therapy of psoriasis vulgaris: a case series

Background

Sunscreens are being widely used to reduce exposure to harmful ultraviolet (UV) radiation. The fact that some sunscreens are photounstable has been known for many years. Since the UV-absorbing ingredients of sunscreens may be photounstable, especially in the long wavelength region, it is of great interest to determine their degradation during exposure to UV radiation. Our aim was to investigate the photostability of seven commercial sunscreen products after natural UV exposure (UVnat) and artificial UV exposure (UVart).

Methods

Seven commercial sunscreens were studied with absorption spectroscopy. Sunscreen product, 0.5 mg/cm², was placed between plates of silica. The area under the curve (AUC) in the spectrum was calculated for UVA (320–400 nm), UVA1 (340–400 nm), UVA2 (320–340 nm) and UVB (290–320 nm) before (AUC_before) and after (AUC_after) UVart (980 kJ/m² UVA and 12 kJ/m² of UVB) and before and after UVnat. If theAUC Index (AUCI), defined as AUCI = AUC_after/AUC_before, was > 0.80, the sunscreen was considered photostable.

Results

Three sunscreens were unstable after 90 min of UVnat; in the UVA range the AUCI was between 0.41 and 0.76. In the UVB range one of these sunscreens was unstable with an AUCI of 0.75 after 90 min. Three sunscreens were photostable after 120 min of UVnat; in the UVA range the AUCI was between 0.85 and 0.99 and in the UVB range between 0.92 and 1.0. One sunscreen showed in the UVA range an AUCI of 0.87 after UVnat but an AUCI of 0.72 after UVart. Five of the sunscreens were stable in the UVB region.

Conclusion

The present study shows that several sunscreens are photounstable in the UVA range after UVnat and UVart. There is a need for a standardized method to measure photostability, and the photostability should be marked on the sunscreen product.     

黑果枸杞水提取物抑制UVB辐射后HaCaT细胞的凋亡及p16、p53蛋白表达

目的：明确黑果枸杞水提取物对中波紫外线(UVB)辐射引起的HaCaT细胞凋亡及p16、p53蛋白表达的影响。方法： 体外培养HaCaT细胞,分为对照组、UVB组、UVB+黑果枸杞水提取物组,UVB照射剂量为30 mJ/cm2 UVB,黑果枸杞水提取物浓度为2 mg/mL。流式细胞仪检测各组UVB照射后24 h细胞凋亡率,Western blot检测各组HaCaT细胞p16、p53蛋白的表达水平。结果：与对照组（6.12±1.19）%比较,UVB组HaCaT细胞凋亡率为(74.89±3.90)%、UVB+黑枸杞水提取物组为（57.52±2.93）%,差异有统计学意义（P<0.05）。对照组p16和p53蛋白水平为0.1±0.03和0.21±0.07,UVB组为0.28±0.06和0.5±0.04、UVB+黑枸杞水提取物组为0.15±0.025和0.25±0.01,差异均有统计学意义（Ps<0.05）。结论：黑果枸杞水提物可抑制UVB引起的HaCaT细胞凋亡以及p16、p53蛋白表达。     

Characterization of coordinated immediate responses by p16INK4A and p53 pathways in UVB-irradiated human skin cells

While the precise mechanisms of melanoma development are unknown, recent in vivo studies have revealed that the p16(Ink4a)/Rb pathway is disrupted in melanomagenesis. Here, we characterize the role of p16/Rb in coordinating the early events in UVB-irradiated skin. Foreskins and melanoma cell cultures were irradiated with low and high acute UVB doses and examined for cell-cycle- and apoptosis-associated genes. In melanoma cells, low UVB dose upregulated p16, p53, and p21 expression levels in Malme-3M, and high UVB dose accentuated the expression of p53 and p21(Cip1/Waf1), in particular; however, in SkMel-28 cells only p16 expression was upregulated in response to UV irradiation. In HaCaT cells, high UVB dose caused dramatic increase in p53 expression followed by upregulation of p21(Cip1/Waf1) and Bax, and downregulation of Bcl-2 leading to apoptosis. In HaCaT cells, reinstatement of p16 pathway restored cell-cycle arrest in response to low dose. Foreskin organ culture experiments confirmed our in vitro cell results. These data indicate that the p53 and p16 pathways respond independently to UVB insult. The p16 pathway is favored at low doses and results in cell-cycle arrest; the p53 pathway is more responsive to higher doses and induces apoptosis depending on p53 mutation status.     

UVA tanning devices interact with solar-simulated UV radiation in skin tumor development in hairless mice

Summary The carcinogenic effect of three UVA tanning sources was studied in lightly pigmented hairless mice. The three tanning sources (Bellarium-S SA-1-12, Philips TL 09R and Philips TL 10R) have different emission spectra, and emit different amounts of UVB. Radiation from the tanning sources was administered for 20 min/day, 5 day/week in daily doses equivalent to those used in suntan salons. The radiation was given alone or after 12 weeks of exposure to solar-simulated UV radiation (SOLAR UV) (10min/day, 4 day/week; daily dose, 19.5 kJ/m² UVA and 3.9 kJ/m² UVB). Irradiation with Bellarium-S SA-1-12 for 47 weeks and Philips TL 09R for 74 weeks induced skin tumours in 20/20 and 13/20 of the animals, respectively. When irradiation with Bellarium-S SA-1-12 and Philips TL 09R was administered after 12 weeks of SOLAR-UV exposure, a strong enhancement of SOLAR-UV-induced photocarcinogenesis was observed (p<0.001). Irradiation with Philips TL 10R was only slightly carcinogenic, and during 85 weeks of irradiation only one skin tumor appeared in a group of 20 mice. However, when irradiation with Philips TL 10R was administered after 12 weeks of exposure to SOLAR UV, an enhancement of SOLAR-UV-induced carcinogenesis was observed (p<0.001). Our results suggest that the hazards of exposure to commercial tanning devices are increased when they are used after a period of natural sun exposure. Even tanning sources with a low carcinogenic potential are able to increase SOLAR-UV-induced carcinogenesis significantly.     

UVB irradiation decreases the magnitude of the Th1 response to hapten but does not increase the Th2 response

Exposure of murine skin to low doses of ultraviolet-B (UVB) radiation before sensitization with hapten reduces the ability of antigen presenting cells (APC) in the draining lymph nodes to initiate contact hypersensitivity responses in vivo and results in the induction of hapten-specific suppressor T cells. In the present study, we tested the hypothesis that exposure of skin to UVB radiation suppresses T cell responses to hapten in vivo by altering the functions of APC, resulting in decreased stimulation of Th1 lymphocytes, which mediate contact hypersensitivity responses, and preferential activation of Th2 cells. C3H/HeN mice were exposed to either a single 2 kJ/m² dose of UVB or to 400 J/m² of UVB daily from FS40 sunlamps for four consecutive days and sensitized with fluorescein isothiocyanate on UV-irradiated skin. Draining lymph node cells were collected 18 h after sensitization and co-cultured with nylon wool-purified T cells from naive or fluorescein-immunized mice. Unseparated lymph node cells or sorter-purified fluorescein-bearing APC from UV-irradiated mice induced less T cell proliferation than APC from non-UV-exposed mice. Lymph node cells produced less Th1 and Th2-associated cytokines, interferon-gamma and interleukin-4, respectively, in response to APC from UV-irradiated animals compared with APC from unirradiated, fluorescein-sensitized mice. Thus, low doses of UV radiation do not result in preferential stimulation of Th2 response in lymph nodes, and results from cloned cell lines may incompletely reflect T cell responses in vivo.     

Increased expression of Fas on human epidermal cells after in vivo exposure to single-dose ultraviolet (UV) B or long-wave UVA radiation

BACKGROUND: Apoptosis has been proposed to act as an important mechanism for eliminating keratinocytes that have been irreversibly damaged by ultraviolet (UV) irradiation. One way to induce apoptosis in keratinocytes is through activation of the cell surface receptor Fas (CD95), either with the ligand (FasL) or directly with UV radiation. OBJECTIVES: To investigate the regulation of Fas and FasL expression in human skin and the formation of apoptotic cells after in vivo exposure to UVB or long-wave UVA radiation. METHODS: Volunteers were irradiated with either 3 minimal erythema doses (MED) of UVB (n = 6) or 3 MED of long-wave UVA (n = 6) on buttock skin 12, 24 and 72 h before skin punch biopsies were taken. Expression of Fas and FasL was demonstrated by immunohistochemistry on cryostat sections. Apoptosis was assessed by the terminal deoxynucleotidyl transferase-mediated fluorescein-deoxyuridine triphosphate nick-end labelling reaction. RESULTS: In five of six subjects, exposure to UVB radiation resulted in increased homogeneous expression of Fas on epidermal cells, with greatest expression at 24 and 72 h after irradiation. In all subjects, exposure to long-wave UVA resulted in increased homogeneous expression of Fas on epidermal cells, with greatest expression at 12 h after irradiation. In five of six subjects, exposure to UVB radiation resulted in temporarily decreased expression of FasL, but after 72 h the expression of FasL had returned to the preirradiation level. The expression of FasL on epidermal cells after exposure to long-wave UVA showed considerable variation. UVB irradiation was a stronger inducer of epidermal apoptosis than was UVA irradiation. The number of apoptotic epidermal cells did not correlate with expression of Fas or FasL. CONCLUSIONS: In human skin the expression of Fas on epidermal cells increases after in vivo exposure to UVB or long-wave UVA. Exposure to UVB causes a temporary decrease in the expression of FasL on epidermal cells.     

Spectrum of ultraviolet radiation on human B and T lymphocyte viability

Human lymphocytes were irradiated with ultraviolet radiation (UV) of various wavelengths. Selective T cell killing was achieved with a dose of 0·1-0·067 J/cm² with UVC (a germicidal lamp) or 254 nm monochromatic radiation while preserving B cell function. Irradiation of lymphocytes with UVA up to 9 J/cm² caused no apparent T and B cell killing. Irradiation with monochromatic 280 and 296 nm radiation (UVB) showed similar susceptibility of both T and B cells with killing occurring with less than 0·5 J/cm².     

Hyaluronan minimizes effects of UV irradiation on human keratinocytes

Exposure to ultraviolet (UV) irradiation has detrimental effects on skin accompanied by the increased metabolism of hyaluronan (HA), a linear polysaccharide important for the normal physiological functions of skin. In this study, the modulation of human keratinocyte response to UVB irradiation by HA (970 kDa) was investigated. Immortalized human keratinocytes (HaCaT) were irradiated by a single dose of UVB and immediately treated with HA for 6 and 24 h. The irradiation induced a significant decrease in the gene expression of CD44 and toll-like receptor 2 6 h after irradiation. The expressions of other HA receptors, including toll-like receptor 4 and the receptor for HA-mediated motility, were not detected in either the control or UVB-irradiated or HA-treated HaCaT cells. UVB irradiation induced a significant decrease in the gene expression of HA synthase-2 and hyaluronidase-2 6 h after irradiation. The expressions of HA synthase-3 and hyaluronidase-3 were not significantly modulated by UV irradiation. Interestingly, HA treatment did not significantly modulate any of these effects. In contrast, HA significantly suppressed UVB-induced pro-inflammatory cytokine release including interleukin-6 and interleukin-8. Similarly, HA treatment reduced the UVB-mediated production of transforming growth factor β1. HA treatment also significantly reduced the UV irradiation-mediated release of soluble CD44 into the media. Finally, HA partially, but significantly, suppressed the UVB-induced decrease in cell viability. Data indicate that HA had significant protective effects for HaCaT cells against UVB irradiation.     

中波紫外线辐射剂量与HaCaT细胞凋亡时相的相关性研究

目的 探讨中波紫外线(UVB)辐射角质形成细胞后,UVB辐射剂量与角质形成细胞凋亡时相的相关性。方法 以20,40,60,80,100和120mJ/cm²的UVB辐射永生化人角质形成细胞株HaCaT细胞,检测辐射后2,12,24,48和72h的细胞活性和细胞周期的变化,以及代表不同时相的凋亡通路:即应用广谱Caspase抑制剂VAD-FMK与凋亡细胞中活化的Caspase不可逆的结合检测早期Caspase介导的凋亡;应用AnnexinV及PI双染方法检测后发的细胞膜介导的凋亡;以及应用DNA的梯度凝胶电泳检测晚期细胞核介导的凋亡。结果 UVB辐射可使HaCaT细胞的细胞周期受滞于G2/M期,G2/M期的百分比与辐射剂量成正比。细胞活性于24h后与辐射剂量成反比。各时相的凋亡率均与辐射剂量成正比,但凋亡通路有明显的时相性:即早期(48h内)由Caspase和细胞膜介导凋亡为主,晚期(48h后)则由细胞核介导凋亡为主。结论 UVB诱导的角质形成细胞凋亡具有显著的剂量与时相依赖性特征。宜对其进行多指标、多时相的检测。     

紫外线对HaCaT细胞结合珠蛋白mRNA表达的影响

目的 观察紫外线照射对人角质形成细胞系HaCaT细胞表达结合珠蛋白的影响。方法 用逆转录-聚合酶链反应法检测长波紫外线UVA、中波紫外线UVB照射后HaCaT细胞各时相结合珠蛋白mRNA表达水平。结果 UVA12J/cm²照射后HaCaT细胞结合珠蛋白mRNA表达明显升高。照射后20min结合珠蛋白mRNA表达已开始升高,6h达第一高峰,48h出现第二高峰。照射后2h、4h、6h、24h、48h组与对照组比较,差异有统计学意义(P<0.05)UVB30mJ/cm²照射HaCaT细胞后结合珠蛋白mRNA表达也出现时相变化:4h达第一高峰,48h出现第二高峰。照射后20min、2h、4h、6h、12h、48h、72h组与对照组比较,差异有统计学意义(P<0.05)。结论 紫外线UVA、311nmUVB上调HaCaT细胞结合珠蛋白mRNA表达,随照射时间,结合珠蛋白mRNA表达呈时相变化。