Research Article

Enterococcus faecium TIR-Domain Genes Are Part of a Gene Cluster Which Promotes Bacterial Survival in Blood

Figure 7

Effect of TirEs and Hp1 on IL-8 release. (a) Presence of tirE1-hp1-tirE2 does not affect IL-8 release. Upon infection of macrophage-like cells (differentiated Thp1 cells) with E1162 and E1162Δtir at MOI 300, MOI 100, and MOI 10, IL-8 was measured in the cellular supernatant at 2 h, 4 h, and 6 h after infection, through IL-8 ELISA. Data are pooled from 3 independent experiments, each in duplicates. (b) Interference of TirE1 and TirE2 with TLR2 signaling. IL-8 release was measured as a response of HEK293 cells stably expressing TLR2 towards stimulation with the lipoproteins Malp2, Pam2Cys, and Pam3Cys. The cells were left untreated (nonstimulated) or were added Malp2, Pam2Cys, or Pam3Cys. One hour before stimulation with agonists, the TLR2-expressing HEK293 cells were added SSL3 (well-known inhibitor of TLR2 signaling), TirE1, TirE2, or a combination of TirE1, Hp1, and TirE2 to a final concentration of 10 µg/ml. IL-8 was quantified in IL-8 ELISA, using TMB as the substrate and measuring the absorbance at 450 nm. Data are shown in triplicates, representative of 3 independent experiments. , inhibited vs uninhibited: , , , , , and ; Abs: absorption.