TNF and Abnormal autonomic nervous system physiology: In addition to autonomic dysregulation, depression is associated with elevated circulating levels of inflammatory immune markers such as interleukin (IL)-6, tumor necrosis factor (TNF)-α and C-reactive protein (CRP) (Dowlati et al., 2010; Howren, Lamkin, & Suls, 2009; Osimo et al., 2020).