Previous studies have shown that anxiety was associated with low levels of many cytokines in sera, such as CCL11, CCL2, CCL5, and IL-6; and lower peripheral levels of CXCL5 was observed in people with psychiatric disorders, such as schizophrenia and recurrent depressive disorder with suicidal ideation (Polacchini et al., 2018). Here, CCL2 is linked to depressive disorder.