Effect of immunosuppressive treatment on biomarkers in adult atopic dermatitis patients

Abstract

Background: Biomarkers to objectively measure disease severity and predict therapeutic responses are needed in atopic dermatitis (AD). Objective: Primary aim: To identify biomarkers reflecting therapeutic response in patients with AD treated systemically. Secondary aims: (i) To identify a biomarker pattern predicting responsiveness to systemic treatment. (ii) To identify differences in expression of biomarker in filaggrin gene (FLG) mutation carriers vs. non-FLG mutations carriers. Methods: Thirty-eight severe AD patients treated with methotrexate or azathioprine participated. Serum levels of a proliferation-inducing ligand, B-cell activating factor of the TNF family, thymus and activation-regulated chemokine (chemokine (C-C motif) ligand 17) (TARC (CCl-17)), interleukin-1 receptor antagonist (IL-1RA), interleukin-1 bèta, IL-4, IL-6, IL-7, IL-8, IL-9, IL-10, IL-12, IL-13, IL-18, IL-31, interferon gamma, tumour necrosis factor alpha, vascular endothelial growth factor (VEGF), monokine induced by interferon gamma (chemokine (C-X-C motif) ligand 9), interferon gamma-induced protein 10 (C-X-C motif chemokine Ligand 10), monocyte chemoattractant protein-1 (chemokine (C-C Motif) ligand 2), macrophage inflammatory protein-1 beta (chemokine (C-C motif) ligand 4), regulated on activation, normal T cell expressed and secreted (chemokine (C-C motif) ligand 5), Cutaneous T-cell-attracting chemokine (chemokine (C-C motif) ligand 27) (CTACK (CCL-27)), thymic stromal lymphopoietin, IL-5, interleukin-1 alpha and granulocyte-colony stimulating factor were analysed by ELISA and Luminex. The primary outcomes were differences in mean absolute change of SCORing Atopic Dermatitis (SCORAD) between groups after 12 weeks compared with baseline. Responders to treatment were defined by a SCORAD reduction in ≥50%. Buccal mucosa swabs were collected to determine FLG genotype status. Results: Thymus and activation-regulated chemokine, CTACK, IL-13 and VEGF showed a significant decrease after treatment with methotrexate or azathioprine. However, no decrease in individual cytokine levels was significantly correlated with a change in any of the outcome parameters. In addition, baseline biomarker levels were not significantly different between responders and non-responders, and FLG and non-FLG mutants showed similar biomarker profiles. Conclusion: Thymus and activation-regulated chemokine and CTACK were confirmed as potential biomarkers. VEGF and IL-13 have a potential value as well. Biomarkers could not be used to discriminate at baseline between responders and non-responders, or FLG genotype status.