Background: Previous studies have shown the expression of histamine H4 receptor (H4R) on CD4+ T cells, especially human CD4+ Th2-polarized T cells.
Objective: This study aimed to investigate the role of H4R on these effector T cells in psoriasis.
Methods: We enrolled three patients each with active psoriasis, inactive psoriasis, scalp seborrheic dermatitis, and three normal controls, and compared the basal expression of H4R mRNA in their peripheral blood CD4+ T cells. Then, we identified H4R expression in dermal CD4+ T cells. Furthermore, we investigated H4R expression after stimulating separated peripheral blood CD4+ T cells with several inflammatory cytokines.
Results: The results showed higher H4R expression in the active psoriasis group compared to the inactive psoriasis group. It was interesting that interleukin (IL)-23, which is a representative cytokine contributing to Th17 cell differentiation, stimulated H4R expression significantly. After adding a selective H4R antagonist (JNJ-7777120) while the CD4+ T cells were polarized into Th17 cells, we observed a tendency toward suppressed IL-17 secretion.
Conclusions: Histamine stimulation influences the IL-17 pathway in psoriasis via the fourth histamine receptor subtype, H4R, on CD4+ T cells. The immunomodulatory roles of H4R suggest its potency as a new therapeutic target for obstinate psoriasis.
Keywords: CD4(+) T cell; Histamine; Histamine 4 receptor; Psoriasis; T(h)17 cell.
Copyright © 2017 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.