Caspase-11 Activation in Response to Bacterial Secretion Systems that Access the Host Cytosol
Figure 3
Caspase-11 activation is independent of ASC and NLRC4.
(A) Unprimed B6, Casp1−/−Casp11−/−, or Asc−/−Nlrc4−/− BMDMs were infected with WT L. pneumophila (WT Lp), ΔdotA Lp, ΔflaA Lp, or PBS (mock infection) for 20 hours, and levels of IL-1α and IL-1β in the supernatants were measured by ELISA. Graphs show the mean ± SEM of triplicate wells. (B) Unprimed B6, Casp1−/−Casp11−/−, or Asc−/−Nlrc4−/− BMDMs were infected with WT Lp, ΔdotA Lp, ΔflaA Lp, or PBS (mock infection) for 20 hours or treated with LPS+ATP for 1 hour. Levels of processed caspase-1 (casp-1 p10) and caspase-11 (casp-11 p26) in the supernatants, and pro-caspase-1, pro-caspase-11, and β-actin (loading control) in the cell lysates were determined by immunoblot analysis. (C) 8–12 week old B6 and Asc−/− mice were infected intranasally with either 1×106 ΔflaA Lp or PBS. Bronchoalveolar lavage fluid (BALF) was collected 24 hours post-infection, and levels of IL-1α and IL-1β were measured by ELISA. Graphs show the mean ± SEM of 9 mice per group. Dashed line represents the limit of detection. Data are representative of three independent experiments (A,B) or are displayed as the pooled results of two independent experiments (C). *** is p<0.001 by two-way ANOVA with Bonferroni post-test. ** is p<0.01 by unpaired t-test. NS is not significant.