title: Catechol-O-methyltransferase activity is higher in psoriasis patients and is down-regulated by narrowband ultraviolet B treatment.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  To evaluate COMT activity in patients with psoriasis and determine whether nbUVB modifies this activity.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors: Department of Pharmacology, Therapeutics, University of Porto Porto, Portugal. smagina@med.up.pt
authors: Sofia
authors: S
authors: Magina
authors: Eduardo
authors: E
authors: Moura
authors: Maria Paula
authors: MP
authors: Serrão
authors: Daniel
authors: D
authors: Moura
authors: Maria Augusta
authors: MA
authors: Vieira-Coelho
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015992:Body Mass Index; D002394:Catechol O-Methyltransferase / Q000097:blood*; D015536:Down-Regulation / Q000528:radiation effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011565:Psoriasis / Q000201:enzymology* / Q000532:radiotherapy*; D011788:Quality of Life; D012044:Regression Analysis; D012720:Severity of Illness Index; D014467:Ultraviolet Therapy; D055815:Young Adult
chemical_list: D002394:Catechol O-Methyltransferase
keywords: Narrowband ultraviolet B; catechol-O-methyltransferase (COMT); psoriasis