Th17 pathway is activated in early inflamed acne lesions

The mechanisms of inflammation in acne are not well understood. This study performed in two separate patient populations focused on the activation of adaptive and innate immunity in early inflamed acne. Biopsies were collected from lesional and non-lesional skin of acne patients. Psoriasis patients and healthy volunteers were included in the study for comparison (not included in the records). Using Affymetrix Genechips, we observed significant elevation of the signature cytokines of the Th17 lineage in acne lesions compared to non-lesional skin. The increased expression of IL-17 was confirmed with real-time qPCR (RT-PCR) in two separate patient populations. Cytokines involved in Th17 lineage differentiation (IL-1beta, IL-6, TGF-beta; IL23p19) were remarkably induced at the RNA level. In addition, pro-inflammatory cytokines (IL-8, TNF-), Th1 markers (IL12p40, CXCR3, T-bet, IFN-gamma), T regulatory cell markers (Foxp3, IL-10, TGF-) and antimicrobial peptides (S100A7, S100A9, LNC2, hBD2, hBD3, hCAP18) were induced. Importantly, immunohistochemistry revealed significantly increased numbers of IL-17A positive T cells and CD83 dendritic cells in the acne lesions. In summary our results demonstrate the presence of IL17A positive T cells and the activation of Th17-related cytokines in acne lesions, indicating that the Th17 pathway may play a pivotal role in the disease process, offering new targets of therapy.

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Kelhälä HL, Palatsi R, Fyhrquist N, Lehtimäki S, Väyrynen JP, Kallioinen M, Kubin ME, Greco D, Tasanen K, Alenius H, Bertino B, Carlavan I, Mehul B, Déret S, Reiniche P, Martel P, Marty C, Blume-Peytavi U, Voegel JJ, Lauerma A