TLR4 and depressive disorder: After 6 weeks of fluoxetine therapy in patients with diabetes and depression, the expression of aortic TLR4 gene and protein were significantly reduced, which reduced the levels of pro-inflammatory cytokines TNF-α and IL-1, demonstrating an improvement in metabolic, vascular, and inflammatory abnormalities in diabetes with comorbid depression (Habib et al., 2015).