Background: Although the local anti-inflammatory, immunosuppressive and oxidative activity of UVB is known, the systemic effect of UVB phototherapy in dermatological patients has not been investigated.
Objective: We aimed to investigate the lipid peroxidation status (as represented by thiobarbituric acid reactive substance, TBARS) and nitrite-nitrate levels in psoriatic patients under broad-band ultraviolet B (BB-UVB) phototherapy in order to determine the systemic effects of UVB.
Subjects and methods: Thirty-two psoriatic patients and 20 healthy controls were included. Blood samples were obtained at the beginning, after 6-10 exposures to BB UVB phototherapy (mean 5 weeks) and at the end of the therapy period (mean 21 weeks). Serum TBARS and nitrite-nitrate levels were evaluated.
Results: There was no statistically significant difference in serum TBARS and nitrite-nitrate levels between psoriatic patients (basal) and healthy volunteers. There was no statistically significant correlation between disease duration, disease severity, or the total cumulative dose of UVB and serum levels of TBARS and nitrite-nitrate in psoriatic patients. Total nitrite levels in samples obtained during and at the end of therapy were significantly higher than basal levels (P=0.033 and P=0.005, respectively). TBARS levels in samples obtained during and at the end of therapy were significantly higher than basal levels (P=0 and P=0.026, respectively). There was a negative correlation (r=-0.576, P=0.039) between the total nitrite and TBARS levels in psoriatic patients at the end of therapy.
Conclusion: Our study showed that chronic exposure to UV irradiation may lead to a systemic effect on lipid peroxidation and NO levels, which are shown by a significant elevation in TBARS and nitrite-nitrate levels in serum.