Moreover, interferon-gamma knockout mice exhibited anxiogenic behavior.37 The function of the hypothalamic–pituitary–adrenal (HPA) axis, which has been confirmed to be another plausible mechanism involved in the process of anxiety, is also influenced by cytokines.38 A previous study demonstrated that interferon and tumor necrosis factor alpha (TNF-α) may contribute to altered diurnal HPA axis activity.39 Here, TNF is linked to Anxiety.