Adapalene

The following drugs were used for in vitro experiments in the THP-1 cell line: 9-cis-retinoic acid (9CRA 0.1, 0.5, 1 and 5 µM; Sigma, St. Louis, US); 13-cis-retinoic acid (13CRA 0.01, 0.05, 0.1, 0.5, 1 and 5 µM; Sigma); All-trans-retinoic acid (ATRA 0.5, 1, 5 and 10 µM; Sigma) and naphthenic acid derivate (Adapalene 0.01, 0.05, 0.1 µM; Tocris Bioscience, Ellisville, US). For drug treatment of in vitro differentiated macrophages (8×10⁵ cells/well in 12-well plates) 13CRA was added at: 2.5, 5 and 7 µM final concentrations. Chemical compounds were dissolved in DMSO (Sigma) as 10 mM stock solutions for ATRA, 9CRA and 13CRA; and 1 mM for Adapalene and stored at −80°C. The compounds were further diluted in DMSO such that the final concentration of DMSO in the medium was always 0.5% (vol/vol). Treatments lasted for 24 h and were performed in triplicates.

Peripheral blood mononuclear cells [PBMC] were isolated from buffy coats obtained from healthy blood bank donors, using Ficoll density gradient centrifugation. PBMC of two individual donors were cultured in a 1:1 ratio for 48 h. Subsequently, anti-TNF [infliximab] or control IgG [Sigma Aldrich, Zwijndrecht, The Netherlands] was added, to a final concentration of 10 µg/ml. Where appropriate, additional compounds were added at the concentrations indicated. Albendazole [#A4673], mebendazole [#46404], docetaxel [#01885], paclitaxel [#T7402], budesonide [#PHR1178], fenbendazole [#35032], pyrythione zinc [#H6377], ciclopirox olamine [#C0415], pyrimethamine [#46706], quinacrine [#Q3251], mycophenolic acid [#M3536], adapalene [#A7486], amitryptiline [#A8404], duloxetine [#SML0474], triamterene [#T4143], and colchicine [#C9754] were all obtained from Sigma Aldrich. AMPK activator A769662 was obtained from SelleckChem [#S2697, Munich, Germany] and Compound C from Calbiochem [#171260–1, San Diego, CA]. Cultures were incubated for another 4–5 days and analysed by flow cytometry.
For analysis of effects on isolated macrophages, mixed lymphocyte reactions (MLR) were cultured for 48 h. CD14-expressing cells were isolated using magnetic cell sorting [CD14-microbeads, Miltenyi, Bergisch Gladbach, Germany] and cultured for an additional 72 h in the presence of anti-TNF and/or Albendazole.