Psoriasis is a chronic skin
inflammation caused by a dysfunctional immune system, which causes systemic
inflammation in various organs and tissues. Due to the risk of systemic
inflammation and recurrence of
psoriasis, it is important to identify the critical targets in the pathogenesis of
psoriasis and develop targeted
therapeutics. Dimerized
translationally controlled tumor protein (dTCTP) promotes immune cell activation as a pro-inflammatory
cytokine and plays a role in developing allergic diseases such as
asthma and
rhinitis. Here, we sought to explore whether dTCTP and its inhibition contributed to the development and control of
imiquimod (IMQ)-induced
psoriasis. Topical application of IMQ inflamed the skin of the back and ear, increased inflammatory
cytokines, and decreased regulatory T cell markers. Interestingly, TCTP was significantly increased in inflamed skin and immune cells such as T cells, B cells, and macrophages after IMQ treatment and was secreted into the serum to undergo dimerization. Extracellular dTCTP treatment selectively suppressed regulatory T (Treg) cells, not other effector T helper (Th) cells, and increased M1 macrophages. Moreover, dTCTP-binding
peptide 2 (
dTBP2), a dTCTP inhibitor
peptide, effectively attenuated the systemic inflammatory responses, including Th17 cell response, and alleviated psoriatic skin
inflammation.
dTBP2 blocked dTCTP-mediated Treg suppression and stimulated the expression of Treg cell markers in the spleen and inflammatory skin lesions. These results suggest that dTCTP dysregulated immune balance through Treg suppression in psoriatic
inflammation and that functional inhibition of dTCTP by
dTBP2 maintained immune homeostasis and attenuated inflammatory
skin diseases by expanding Treg cells.