IDO1 and osteomyelitis: To further evaluate the changes of macrophage at infection site in bone marrow, the mRNA expression levels of CD86, IL-1β, IL-6, and COX2, marker genes of the classically activated macrophages (M1), and ARG1, IDO1, YM1, and CCR7, marker genes of the alternatively activated macrophages (M2; Parisi et al., 2018), were evaluated in the bone marrow from S. aureus osteomyelitis mice.