Figure 6. The proposed cytokine signalling pathways for macrophages and contracting skeletal muscle.

While it is well known that transcription of IL-6 and other pro-inflammatory cytokines such as TNF-α and IL-β is principally regulated by the TLR receptor signalling cascade that results in nuclear translocation and activation of NFκB, evidence in contracting skeletal muscle suggests that contraction leads to increased cytosolic Ca²⁺ and activation of p38 MAPK and/or calcineurin, which leads to activation of transcription factors depending upon these upstream events. From Pedersen & Febbraio (2008) with permission from the American Physiological Society.