In a mouse model of systemic lupus erythematosus associated with depressive symptoms, intravenous infusion of paeoniflorin (20 mg/kg, 6 h) can inhibit despair-like behaviors by reducing the expression of toll-like receptor-4 (TLR-4), myeloid differentiation primary response 88 (MyD88), phospho-NF-κB p65, and phospho-IκBα, and reducing the production of pro-inflammatory cytokines (Wang et al., 2018c) (Figure 6), suggesting that paeoniflorin could be developed as a novel drug to improve depressive symptoms in patients with systemic lupus erythematosus. This evidence concerns the gene TLR4 and systemic lupus erythematosus.