Tissue and Serum Inflammatory Cytokine Levels in Korean Psoriasis Patients: A Comparison between Plaque and Guttate Psoriasis

BACKGROUND The phenotypic heterogeneity of psoriasis could be explained by the alternate activation of either T-helper (Th)-1- or Th-17-related cytokines. However, evidence directly supporting this hypothesis is scarce. OBJECTIVE To characterize the expression of Th-1- and Th-17-related cytokines according to the morphological psoriasis phenotype: guttate vs. plaque. METHODS In this study, we enrolled 68 patients exhibiting either guttate or plaque psoriasis, and 10 healthy controls. To avoid age-related bias, age matching was performed for each group. Circulating levels of interferon (IFN)-γ, interleukin (IL)-1RA, IL-2, IL-12p40, IL-17A, IL-22, and IL-23 were measured with an enzyme-linked immunosorbent assay (ELISA). Psoriasis-affected tissue was obtained through biopsy sampling from the eight patients who exhibited the most typical morphology. Levels of IL-1RA, IL-12p40, IL-17, IL-22, and IL-23 in the psoriasis tissue samples were measured with western blot analysis. RESULTS ELISAs of the serum samples showed higher levels of inflammatory cytokines such as IL-1RA, IL-2, IL-23, and IFN-γ in patients with psoriasis than in healthy controls. However, the inflammatory cytokine levels did not differ significantly between guttate and plaque psoriasis patients. Western blot analysis of psoriatic tissue revealed higher protein levels of Th-1- and Th-17-related cytokines in patients than in healthy controls. The levels of IL-12p40 and IL-23 were unexpectedly higher in plaque tissue than in guttate tissue. CONCLUSION The morphological phenotype of psoriasis does not appear to be determined by a specific activation of either the Th-1 or Th-17 pathway. Rather, the cytokine profile influences disease activity and is altered according to the status of the lesion (early or chronic).