Fig. 5. IL-1β selects for bacterial protease inactivation.
(A) GAS isolates recovered 72 hours after intradermal infection (n = 5 samples of 8 isolates each) examined for switching by testing for expression of SpeB by casein hydrolysis assay (P < 0.0001 and P = 0.034). (B) GAS (n = 5 samples of 8 isolates each) recovered from infected macrophages (Mac), keratinocytes (Ker), and neutrophils (PMN) 4 hours after infection examined for SpeB expression by casein hydrolysis assay (P < 0.0001, P = 0.25, and P = 0.67). (C) BMM treated 1 hour with inflammasome-targeting drugs or mutant for the indicated inflammasome components infected with GAS 4 hours and the recovered CFU (n = 5 samples of 8 isolates each) examined for SpeB expression by casein hydrolysis assay (*P < 0.005). Data are means ± SEM and are representative of at least three experiments. Statistical significance was determined by Student’s t test.