Additionally, many studies found increased levels of cytokines secreted by macrophages in PF samples collected from patients with endometriosis, such as interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-β, which resulted in a peritoneal inflammatory environment (17). This evidence concerns the gene CXCL8 and endometriosis.