Fig. 6.

A hypothesis of a positive feedback loop between the expression of IL-17C and the activation of macrophages. The expression of IL-17C in macrophages was identified [23, 26] and further supported in this study. And the direct proinflammatory effect of IL-17C on macrophages was also identified [22, 26, 34]. Taken together, macrophages activated by wear particles and bacterial components secrete IL-17C, and IL-17C in turn enhances the activation of macrophages in an autocrine manner [34], thus forming a positive feedback loop