TNF and immune system disorder: It is well acknowledged that immune dysfunction is a key part during the onset of IBD and in IBD patients, the immune capacity is often compromised because of the application of immune-modifying treatment such as corticosteroids, immunomodulators and biologic agents [e.g., monoclonal antibodies for TNF-α, interleukin 12/23, integrin α4β7, and small molecules such as Janus kinase (JAK) inhibitors].