The vast recruitment of immune cells to the peritoneal cavity and significant increase in type 2 cytokines (including IL-4 and IL-5), immune-modulating cytokines (such as IL-6 and G-CSF), and angiogenic factors (such as VEGF) suggest that IL-33 actively contributes to a pathological inflammatory microenvironment similar to that observed in patients with endometriosis. This evidence concerns the gene VEGFA and endometriosis.