TNF and abscess: During the progression of UC, activated macrophages produce pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α), interleukin (IL)-1 β, IL-6, and IL-12 which attract neutrophils to the colonic mucosa, and directly contribute to crypt abscess and ulcerative lesions by producing reactive oxygen species and proteolytic enzymes [7,8].