FIGURE 8.

Schematic of TLR2 regulation of NGF. Alarmins activate TLR2 (blue)–TLRx (pink), where TLRx is TLR1, -2, or -6. TLR activation induces the NF-κB signaling cascade, promoting NGF synthesis. NGF is translated as proNGF and is cleaved intracellularly to mNGF and then secreted from the cell. Additionally, TLR2 activation results in increased IL-1β gene expression, which may result in increased IL-1β protein that could create a feedback loop, indicated by the dotted line, to further increase NGF. IKK, inhibitor of κ B kinase.