CCL4 and susceptibility to pneumonia measurement: In addition, animals subjected to CLP that developed secondary S. aureus pneumonia showed markedly reduced BALF or serum inflammatory mediator production, such as IL-1β, IL-6, IL-17A, TNF-α, and MIP-1β/CCL4, whereas upregulated anti-inflammatory mediator (IL-10) production relative to the sham operation group, and pneumonia occurred at 24 h following infection (Figure 2(f)).