KdPT alleviates imiquimod-induced psoriasis-like skin lesion in mice via inhibiting proliferation and inflammation response

Psoriasis is a complex chronic skin inflammatory disease characterized by abnormal proliferation, differentiation of keratinocytes and infiltration of lymphocytes and neutrophils. The tripeptide KdPT, structurally derived from the C-terminal amino acid of alpha-melanocyte-stimulating hormone, has shown a significant anti-inflammatory effect on mild-to-moderate active ulcerative colitis in previous reports. In this research, we investigated whether KdPT could consistently ameliorate disease in a mouse model of imiquimod (IMQ)-induced psoriasis by inhibiting proliferation and inflammation response. We demonstrated that KdPT in vitro significantly inhibited the proliferation of human keratinocytes and endothelial cells, and also downgraded the expression of inflammatory factors in LPS-induced RAW264.7, including IL-6, TNF-alpha and NO. In vivo, KdPT attenuates the severity of IMQ-induced psoriasis-like phenotype in mice. Such an effect was achieved by downregulating the expression of the inflammatory cytokines interleukin (IL)-6, TNF-alpha, and the proliferation marker Ki67. These results suggested that KdPT might be useful in the treatment for psoriasis.