Figure 4: RvD1 and RvD2 reverse the inhibitory effect of IL-17 on Del-1 expression in a PI3K/Akt-dependent manner.

(a,b) HUVEC were stimulated for 2 h (to determine Del-1 mRNA expression; left panels) or 6 h (to determine Del-1 protein levels; right panels) in the absence or presence of IL-17 (5 ng ml⁻¹). Prior to IL-17 stimulation, the cells were pretreated for 30 min with 100 nM RvD1 (a) or RvD2 (b). In experiments using LY249002 (20 μM; PI3K inhibitor) or LY303511 (20 μM, inactive analogue), or MK2206 (Akt inhibitor; 10 μM), these compounds were added 1 h before RvD1 or RvD2. Del-1 mRNA expression was determined by qPCR. (c–e) Similar experiments as above with the exception that, in lieu of Akt inhibitor, HUVEC were treated with control or Akt-specific siRNA which effectively inhibited expression of Akt mRNA and protein (upper and lower panel, respectively, in c). Del-1 mRNA expression was determined by qPCR and results were normalized to those of GAPDH mRNA and expressed as fold change in transcript levels relative to those of medium only-treated cells, the average value of which was taken as 1. Del-1 protein levels in culture supernatants were determined by ELISA. Data are means±s.d. (n=5 sets of HUVEC cultures). *P<0.01 between indicated groups (ANOVA). NS, not significant.