Aryl Hydrocarbon Receptor Activity in Patients Receiving Narrowband UVB Therapy

Rowland Noakes*

Narrowband UVB is used by dermatologists to treat atopic dermatitis and psoriasis. Although multimodal in its mechanism of action, the photo-oxidation of L-tryptophan to 6-formylindolo [3,2-b] carbazole, a potent Aryl Hydrocarbon Receptor (AHR) agonist, is proposed to play a role. This study aimed to assess AHR induction in patients treated with Narrowband UVB (NBUVB). 10 patients undergoing NBUVB therapy for psoriasis and atopic dermatitis had biopsies taken from a treatment site, with photo-protected buttock skin used as the control. Fitzpatrick skin types were one to three. Ages ranged from 29 to 82, with a median age of 63. The sex ratio was 4:6 (M: F). NBUVB was introduced at a commencing dose of 100 mJ with 20% increments three times weekly. Following 36 sessions of therapy, 4 mm punch biopsies were taken. Cytochrome P450 1A2 (CYP1A2) immunohistochemistry was used as a marker for AHR activity. Analysis was via Aperio Imagescope using Positive Pixel Count v9. Values for total intensity/mm2 were used to assess enzyme activity. A value of 45395360 was obtained at the control site and 5060956 at the treatment site with a p value of 0.12, which, although a positive result, fails to reach statistical significance. The interpretation of these results is complicated by the fact that FICZ is active at femtomolar concentrations, and a demonstration of a statistically significant effect on AHR induction via immunohistochemistry may be difficult.

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Published on: May 13, 2025 Pages: 4-7

Full Text PDF Full Text HTML DOI: 10.17352/2455-8605.000053
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