CXCL8 and ulcer disease: Continuous mechanical stimulation to the oral mucosa, causing trauma to the mucosa, and the inflammatory reaction, is initiated locally and a variety of inflammatory mediators are secreted, such as interleukin-1β (IL-1β), IL-6, interleukin-8 (IL-8), tumor necrosis factor-α (TNF-α) and transforming growth factor β (TGF-β); the injured mucosa further atrophy and cause ulcer development due to long-term inflammation [3].