The possible explanation of the synergistic elevation of both TNF-α and IL-8 levels is that the endometrial cells respond to infection by activation of TLRs (Ajevar et al., 2014) and thereafter stimulate the release of pro-inflammatory cytokines as TNF-α, chemokines as IL-8 and prostaglandins (Fischer et al., 2010; Loyi et al., 2013). The gene discussed is CXCL8; the disease is infection.