Figure 2: C. burnetii inhibits the caspase-11-mediated non-canonical activation of the NLRP3 inflammasome induced by L. pneumophila.
From: Inhibition of inflammasome activation by Coxiella burnetii type IV secretion system effector IcaA
Bone marrow-derived macrophages (BMDMs) were left noninfected (NI) or were infected with C. burnetii (Cb, MOI 30) for 24 h and further infected with wild-type L. pneumophila (WT Lp, MOI 10) or flaA− (MOI 10) for 9 h. Co-infected BMDMs are indicated (Cb+WT Lp or Cb+flaA−). (a) Immunoblot showing levels of processed p20 subunit of caspase-1 (caspase-1 p20), unprocessed caspase-1 (pro-caspase-1), p17 subunit of mature IL-1β (IL-1β p17) and pro-IL-1β, as determined in supernatant (SN) and cell extract (CE). (b,c) Flow analysis of FLICA staining in BL/6 BMDM noninfected (grey curve), infected with Cb (green curve), infected with L. pneumophila (blue curve) or co-infected (red curve). (d) Quantification of FLICA-positive cells in (b,c). (e) IL-1β secretion in infected BMDMs was determined by ELISA. BMDMs infected with live C. burnetii (live Cb) or with PFA-fixed were used. (f) Caspase-1 cleavage and IL-1β secretion were evaluated by immunoblot as in (a). Data in (d,e) are expressed as average±s.e.m. of triplicate wells and significance was calculated with ANOVA. *P<0.05. Data are representative of three (a,f) and two (b–e) independent experiments.
