• chemokines;
  • dimethylfumarate;
  • psoriasis

Background The effectiveness of systemic treatment of psoriasis with fumaric acid esters has been proven, but their mode of action at the cellular and molecular level has not yet been fully elucidated.

Objectives To study the effect of dimethylfumarate (DMF) on the production of the chemokines CXCL1, CXCL8, CXCL9, CXCL10 and CXCL11, formerly known as GROα, interleukin-8, Mig, IP-10 and IP-9/I-TAC, respectively, in human keratinocytes and peripheral blood mononuclear cells (PBMC).

Methods Cultured keratinocytes were stimulated with interferon (IFN) -γ to produce CXCL9, CXCL10 and CXCL11 and with phorbol myristate acetate to produce CXCL1 and CXCL8 in the absence and presence of DMF (5, 15 and 45 μmol L−1). PBMC were stimulated with either IFN-γ to produce CXCL9 and CXCL10 or lipopolysaccharide to produce CXCL8, in the absence and presence of DMF (5, 15 and 45 μmol L−1). RNA preparations from isolated keratinocytes were analysed by Northern blotting; protein production by keratinocytes and PBMC was monitored by an enzyme-linked immunosorbent assay.

Results Northern blot analysis on isolated keratinocyte RNA preparations showed a dose-dependent inhibition of CXCL1, CXCL8, CXCL9, CXCL10 and CXCL11 transcription by DMF. At 45 μmol L−1 the inhibition was almost complete. In addition, keratinocytes and PBMC showed in the presence of DMF a dose-dependent inhibition of CXCL8, CXCL9 and CXCL10 protein production.

Conclusions These results show the ability of DMF to inhibit the production of chemokines that may be critically involved in the development and perpetuation of psoriatic lesions. This might explain, at least in part, the beneficial effects of treatment with fumaric acid esters in psoriasis patients.