TNF and systemic inflammatory response syndrome: Infiltrating macrophages with high plasticity can be polarized into classically activated macrophages (M1 macrophages) stimulated by LPS and release proinflammatory cytokines (such as tumor necrosis factor-alpha (Tnf-α), interleukin-1beta (Il-1β), and interleukin-6 (Il-6)), which markedly aggravate SIRS caused by AP [15].