Gene expression changes in atopic dermatitis after treatment with nb-UVB

Background: Atopic dermatitis (AD) is a common inflammatory skin disease with broad impact on quality of life and on the health care system. The pathophysiology is not fully understood, but it is likely multifactorial involving immune dysfunction, altered skin barrier and environmental factors. Narrow band ultraviolet B (nb-UVB) treatment leads to normalization of the tissue and clinical improvement. However, knowledge of early changes in AD skin in response to nb-UVB is lacking and could provide important clues to decipher the disease mechanisms and potential new treatment targets. Objective: To map the early transcriptional changes in the skin in response to nb-UVB treatment. Results: When examining the early response after only three local UVB-treatments, gene expression analysis revealed 30 down- and 47 up-regulated transcripts. Among these only a small proportion were related to the inflammatory response. Interestingly, two cytokines of the interleukin (IL)-1 family were differentially expressed: the proinflammatory cytokine IL-36γ was reduced after treatment, while the anti-inflammatory cytokine IL-37 increased in skin after treatment with nb-UVB. Conclusion: Local nb-UVB induced an early decrease of the pro-inflammatory cytokine IL-36γ and an increase of the anti-inflammatory IL-37. This likely represents one of the first changes in inflammatory signaling induced by nb-UVB in atopic eczema. Adult patients (n = 16) with mild to moderate AD were included in the study. We performed skin biopsies of patients with AD before and after three treatments of local nb-UVB. The biopsies were analyzed for differences in gene expression with microarrays (Affymetrix, Clariom S). 1 & 4: untreated lesional skin; 2: untreated non-lesional skin; 3: nb-UVB x 3, 5: 6-8 weeks of treatment, lesional skin; 6: 6-8 weeks of treatment, non-lesional skin The biopsies were analyzed for differences in gene expression with microarrays (Affymetrix, Clariom S).