Figure 7. B. burgdorferi RNA sensing through TLR7 contributes to IDO production.

Human PBMCs were incubated for 12 h with live B. burgdorferi (Bb) B515 at a MOI of 10; DOTAP-complexed B515 RNA (1 µg/ml) and B515 whole-cell lysate (1 µg/ml) added without DOTAP; or a TLR2-specific agonist (Pam₂CSK₄). Where indicated, a TLR7-specific inhibitor (IRS661) or a control ODN was added 1 h before stimulation. PBMC lysates were resolved by 12.5% SDS-PAGE for Western immunoblotting with rabbit anti-human IDO1. Densitometric values of protein expression were normalized to GAPDH and quantitated by use of ImageJ software. Columns represent the mean ± sd of results from 3 donors assessed in triplicate in independent experiments. Representative Western blot images from a single donor are shown. Statistical analysis was performed by use of a one-way ANOVA with Tukey-Kramer’s post-test. ***P < 0.001; *P < 0.05, relative to PBMCs incubated with medium alone.