TNF and major depressive disorder: For example, some rodent research reports (Su et al., 2017; Han et al., 2018; Zhao J. et al., 2019; Ruilian et al., 2021) showed that central and peripheral concentrations of inflammatory factors, especially IL-1 β, IL-6, and TNF-α, increased after the depression model was established by chronic unpredictable mild stress (CUMS).