Department of Pharmacology, Therapeutics, University of Porto Porto, Portugal.
Eur J Dermatol. 2013 Jan-Feb;23(1):49-52. doi: 10.1684/ejd.2012.1912.
Narrowband ultraviolet B (nbUVB) phototherapy is widely used in psoriasis treatment. UVB irradiation decreases catechol-O-methyltransferase (COMT) activity in human keratinocytes and melanoma cells. COMT activity is higher in psoriatic lesions than in normal skin but the effect of nbUVB on COMT activity in psoriasis patients is unknown.
To evaluate COMT activity in patients with psoriasis and determine whether nbUVB modifies this activity.
An open observational study was conducted with 20 psoriasis patients and 15 healthy volunteers. Patients were treated with nbUVB thrice weekly during six weeks and evaluated at baseline, three and six weeks after phototherapy and four weeks after stopping. In each evaluation body mass index (BMI), Psoriasis Area and Severity Index (PASI) and Dermatology Life Quality Index (DLQI) were calculated and blood samples for erythrocytes soluble (S-) COMT activity assessment were taken.
Before phototherapy (baseline), using a single concentration of substrate adreneline (1,000 μM), S-COMT activity levels (pmol/mg protein/h) were significantly higher in psoriasis patients than in controls. After nbUVB treatment, S-COMT activity significantly decreased. This decrease correlated positively with baseline activity. Four weeks after stopping phototherapy, S-COMT activity returned to baseline levels. After phototherapy, PASI score improved significantly but no correlation to baseline S-COMT values or decrease in S-COMT activity was found.
This study shows that baseline S-COMT activity is higher in psoriasis patients than in controls and that this activity is significantly decreased by nbUVB treatment for psoriasis. This decrease is more evident in patients with higher baseline S-COMT activity.
窄谱中波紫外线（nbUVB）光疗被广泛应用于银屑病的治疗。UVB 辐射可降低人角质形成细胞和黑色素瘤细胞中的儿茶酚-O-甲基转移酶（COMT）活性。银屑病皮损中的 COMT 活性高于正常皮肤，但 nbUVB 对银屑病患者 COMT 活性的影响尚不清楚。
评估银屑病患者的 COMT 活性，并确定 nbUVB 是否能改变这种活性。
进行了一项开放性观察性研究，纳入 20 例银屑病患者和 15 例健康志愿者。患者接受 nbUVB 治疗，每周 3 次，共 6 周，并在治疗前、治疗后 3 周和 6 周以及停止治疗后 4 周进行评估。在每次评估中，计算体重指数（BMI）、银屑病面积和严重程度指数（PASI）和皮肤病生活质量指数（DLQI），并采集血样以评估红细胞可溶性（S-）COMT 活性。
在光疗前（基线），使用单一浓度的底物肾上腺素（1000μM）时，银屑病患者的 S-COMT 活性（pmol/mg 蛋白/h）明显高于对照组。接受 nbUVB 治疗后，S-COMT 活性显著降低。这种降低与基线活性呈正相关。停止光疗 4 周后，S-COMT 活性恢复到基线水平。光疗后，PASI 评分显著改善，但与基线 S-COMT 值或 S-COMT 活性降低均无相关性。
本研究表明，银屑病患者的基线 S-COMT 活性高于对照组，nbUVB 治疗银屑病可显著降低 S-COMT 活性。这种降低在基线 S-COMT 活性较高的患者中更为明显。
