TNF and colitis: In dextran sulfate sodium (DSS)- and trinitrobenzene sulfonic acid (TNBS)-induced colitis models, ob/ob mice produce significantly low levels of proinflammatory cytokines, such as interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), IL-1β, and IL-6, which coincide with reduced STAT3 phosphorylation and cyclooxygenase-2 (COX-2) expression (Siegmund et al., 2002).