ASC and caspase-1-dependent role in murine Lyme arthritis. (A) Macroscopic score of the knees in wild-type (WT), NLRP3, ASC, and caspase-1 knockout mice. After 4 hours and 24 hours of intra-articular (i.a.) injection of 1 × 10^7 live B. burgdorferi, at least 10 knees per group. Data are mean ± SEM from 10 knees in each group; **P <0.01; ***P <0.0001; Mann-Whitney U test, two-tailed. (B) Scored cell influx 1 day after i.a. injection of B. burgdorferi. Data are mean ± SEM from 10 knees in each group; *P <0.05; Mann-Whitney U test, two-tailed. (C) Murine Lyme arthritis in WT, NLRP3, ASC, and caspase-1 knockout mice. Histology (H&E staining) 1 day after i.a. injection of B. burgdorferi in knee joints. 200× magnification; P, patella; F, femur; JC, joint cavity; SL, synovial lining. Scale bar represents 100 μM. ASC, apoptosis-associated speck-like protein containing a caspase recruitment domain (CARD); NLRP3, nucleotide oligomerization domain (NOD)-like receptor P3.