TNF and inflammatory bowel disease: Rag-/-/SCID: Recombination activating genes knockout model/severe combined immunodeficiency; TNF: Tumor necrosis factor; UC: Ulcerative colitis; TLR: Toll-like receptors; Treg cells: Regulatory T cells; CD40LTG: CD40 ligand transgene; IFNγ: Interferon-gamma; IBD: Inflammatory bowel disease.