CCL22 and vitiligo: Klarquist et al.196attributed sparse Tregs in vitiligo skin to reduced expression of CCL22‐induced Treg homing failure. Zhang et al.195ascribed Treg incapability to a diminution of functional modulator HO‐1, and applying HO‐1 agonist restored immunoregulatory Treg function probably by increasing IL‐10 and latency‐associated peptide expression.195