Importantly, esculetin significantly increased CD4+Foxp3+ Treg frequency in both draining lymph nodes and spleens of psoriasis-like mice compared with vehicle group (Lymph node: 8.25 vs. 6.32 in low-dose, and 9.61 vs. 6.32 in high-dose, both p < 0.01; Spleen: 5.07 in low-dose and 5.80 in high-dose vs. 3.01, both p < 0.01). Here, CD4 is linked to psoriasis.