MRC1 and bacterial infectious disease: In brief, compared with PEEK, PEEK-PDA and PEEK-PDA-Sr groups, PEEK-PDA-Sr/AMP exhibits higher CD206 expression and lower CD86 expression at 4 weeks after the surgery, indicating that co-modified PEEK with Sr/AMP could cause an M2 macrophage transition and create an anti-inflammatory milieu under conditions of bacterial infection (Figures 9B,C).