Background: Psoriasis is one of the most common, immune-mediated, chronic inflammatory skin diseases. Proinflammatory cytokines play an important pathogenetic role at a local level.
Objective: To assess whether the proinflammatory cytokines IL-1β, IL-6, IL-17, IL-22 and TNF-α are released systemically during psoriasis.
Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from 30 patients with psoriasis and 30 healthy volunteers. Cytokine production was assessed in supernatants using an enzyme immunoassay after stimulation of PBMCs with microbial stimuli. In addition, flow cytometry was used to determine the subsets of monocytes involved and the intracellular TNF-α production in monocytes.
Results: IL-17 levels were significantly higher in the supernatants of PBMCs from psoriatic patients after stimulation with phytohemagglutinin. TNF-α production was also significantly higher in cells from psoriatic patients after stimulation with all stimuli, as compared with health volunteers. Similar changes were not found for the other cytokines. A statistically significant difference was observed between patients and controls for inflammatory CD14(+)/CD16(+) monocytes (p<0.0001) and patrolling CD14-/CD16(+) monocytes.
Conclusion: Hyper-production of TNF-α is documented in psoriasis. These results support the concept that there is a systemic, proinflammatory component in psoriasis.
Keywords: IL-17; IL-1β; IL-22; IL-6; TNF-α; monocytes; psoriasis.