TLR2 and MyD88 drive Borrelia-induced IL-1β production. (A) 0.5 × 10^6 Bone marrow-derived macrophages (BMDMs) from wild-type (WT), TLR2-/-, MyD88-/-, NOD1-/-, NOD2-/-, and RICK-/- mice were stimulated for 24 hours with either medium (Med), or 5 × 10^6 spirochetes per mL live B. burgdorferi (black bars). IL-1β protein levels in supernatant expressed in picograms per mL after BMDM exposure for 24 hours to B. burgdorferi. BMDMs are isolated from at least five animals per group, protein measurements were performed in duplicate. (B) IL-2 protein levels in nanograms per mL after BMDM stimulation with medium (Med), or 5 × 10^6 B. burgdorferi per mL for 24 hours, using cells from different knockout mice. (C) 3 × 10^6 BMDMs from five WT C57Bl/6, TLR2-/-, MyD88-/-, NOD1-/-, NOD2-/-, or RICK-/- mice were incubated for 24 hours with or without 1 × 10^6 B. burgdorferi with adenosine triphosphate (ATP) (3 mM) for 30 minutes. Cleaved caspase-1 was detected by Western blotting using antibodies to detect the inactive caspase-1 (p45) or active caspase-1 (p20). The control conditions were already published in an earlier article by our group . Borrelia and ATP by itself are unable to induce caspase-1 activation, the combination of the two are crucial for inducing cleavage. MyD88, myeloid differentiation factor 88; NOD, nucleotide-binding oligomerization domain; RICK, serine-threonine protein kinase with a caspase activation and recruitment domain; TLR, Toll-like receptor.
Oosting et al. Arthritis Research & Therapy 2012 14:R247 doi:10.1186/ar4090