IL1B and infection: We observed that a number of NF-κB inducible genes were significantly elevated at 4 weeks post-infection (but not at 2 weeks) by qRT-PCR in B6 miR-146a−/− joints, compared to WT, including cytokines IL-1β and IL-6, as well as neutrophil chemokines Cxcl1 and Cxcl2 (Figure 4A).