TNF and depressive symptom measurement: Preclinical studies have confirmed a causal role of TNF-α and IL-1β in the onset of comorbid persistent pain hypersensitivity and depression-like behavior (Dellarole et al, 2014; Fiore and austin, 2016; Laumet et al., 2017, Maciel et al., 2013, Norman et al., 2010, Zhou et al., 2015).