Figure 4. IFN-γ-Dependent Nitric Oxide Suppreses Brucella-induced inflammasome activation.

WT mice (n=3–4/group) were treated with either anti-IFN-γ or an isotype control, then infected in the rear footpads with 1×10⁵ B. melitensis 16M. Mice were euthanized at day 2 post-infection along with naïve animals and RNA was isolated from ankle joints and relative iNOS transcript was measured A). Error bars depict S.D. of the mean. * P<0.05 compared to IgG-treated mice. In a separate experiment, WT mice received anti-IFN-γ while other WT mice along with NOS2^−/− mice received IgG. Mice were infected in the rear footpads with 1×10⁵ B. melitensis 16M B-D). Joint swelling was monitored B) and mice were euthanized at day 7 post-infection and joint CFUs and IL-1β were enumerated C-D). Data are from 4–5 mice/group. Means with the same letter at the same timepoint are not statistically different from each other as determined by ANOVA followed by Tukey’s test. Error bars depict S.D. of the mean. WT bone marrow derived macrophages were infected with B. melitensis 16M at an MOI of 100 for 6 hours E-G). Media containing increasing doses of SNAP was added after washing of the cells and addition of gentamicin containing media. 24 hours post-infection intracellular Brucella burdens were enumerated and IL-1β levels in cell supernatants were determined E-F). Cell supernatants and cell lysates were also subjected to Western blot G). Data is representative of 2 independent experiments with 3–5 wells/group. Means with the same letter are not statistically different from each other as determined by ANOVA followed by Tukey’s test. Error bars depict S.D. of the mean.