To begin to determine the mechanisms underlying the substance P-mediated increase in local MPO levels in S. aureus infected bone tissue, we assessed the early localized protein expression of the leukocyte-attracting chemokines, CCL2, CCL4, CCL7, CXCL1, CXCL2, and CXCL5, in the absence and presence of aprepitant treatment in our murine model of osteomyelitis. This evidence concerns the gene CXCL5 and osteomyelitis.