CXCL8 and bacterial infectious disease: A decrease in the expression of pro-inflammatory cytokines (IL-8, IL-18, TNF-α, and IFN-γ) and an increase in IL-10 (anti-inflammatory) was observed; in this way, a balance of the inflammatory response to bacterial infection is achieved, suggesting that the use of B. subtilis as an additive in a broiler diet has a similar effect to that produced with antibiotic growth promoter.