TNF and metabolic dysfunction-associated steatotic liver disease: During the development of NAFLD, intestinal bacteria can activate the TLR4 pathway and affect the expression of TNF-α; conversely, short-chain fatty acids produced by certain intestinal bacteria can inhibit the secretion of inflammatory cytokines, such as interleukin (IL) 2 (IL-2), IL-6, and tumor necrosis factor α (TNF-α), by suppressing the activation of the nuclear transcription factor κB (NF-κB) pathway.