IL6 and infection: They are activated by infection-related metabolites, such as lipopolysaccharide (LPS) and interferon-γ (INF-γ), inducing M1 Mφs to secrete high levels of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), cyclooxygenase-21, interleukin-6 (IL-6), and IL-12, which induce the inflammatory response.