Down-Regulatory Role of Cholecystokinin on Psoriatic Epidermal Inflammation

The document reports on a study investigating the role of cholecystokinin (CCK) in psoriatic epidermal inflammation. CCK, a peptide hormone known for its functions in the gastrointestinal and central nervous systems, also has immunomodulatory activities. The study observed decreased CCK expression in psoriatic skin lesions and aimed to understand its effects on epidermal inflammation. In a mouse model, psoriasis-like inflammation was induced with imiquimod, and the effects of intraperitoneal (i.p.) injection of sulfated CCK octapeptide (CCK8S) were measured. The results showed that CCK8S significantly inhibited the increase in ear thickness, epidermal hyperplasia, parakeratosis, and immune cell infiltration caused by imiquimod. Additionally, CCK8S treatment partially inhibited the elevated expression levels of IL-17A, IL-22, and keratin 16 induced by imiquimod. The study concluded that CCK has a suppressive effect on psoriatic epidermal inflammation, potentially by inhibiting Th17/Th22 cell cytokine production, and that reduced CCK expression is associated with continuous psoriatic alterations, suggesting a new pathophysiological role for CCK in regulating epidermal inflammation.