MYD88 and Arthritis: While the TLR/MyD88 signaling pathway is the main pathway contributing to B. burgdorferi lipoprotein mediated inflammation in vitro, arthritis and carditis still develop in vivo in the absence of TLR2 or MyD88 expression (Wooten et al., 2002; Liu et al., 2004; Behera et al., 2006b).