Palmoplantar pustular psoriasis (PPPP) is characterized by activation of the IL-17A pathway

J Dermatol Sci. 2017 Jan;85(1):20-26. doi: 10.1016/j.jdermsci.2016.09.019. Epub 2016 Sep 29.


Background: Palmoplantar pustular psoriasis (PPPP) is a variant of psoriasis, which has significant negative impact on quality of life. The cellular and molecular inflammatory pathways involved in PPPP have not been well studied.

Objective: Study the expression of cytokines and chemokines involved in the IL-17/IL-23 axis in palmoplantar pustular psoriasis and other difficult to treat psoriasis areas (palms, scalp, elbows and lower legs).

Methods: Skin biopsies were performed on a total of 80 patients with PPPP, non-pustular palmoplantar psoriasis (NPPPP), or psoriasis located on elbows, knees and scalp as well as 10 healthy subjects. RT-PCR, immunohistochemistry and flow cytometry on cells extracted from skin biopsies were used to compare PPPP to other forms of psoriasis.

Results: There was a significant (p<0.05) increase in the expression of IL-1β, IL-6, LL-37, IL-19, IL-17A, CXCL1 and CXCL2 in PPPP as compared to NPPPP. However, there was no significant difference in expression of IL-23 in PPPP as compared to NPPPP and other forms of psoriasis. The proportion of IL-22+ but not IL-17A+ mast cells was higher in PPPP as compared to NPPPP (p<0.05).

Conclusion: These results suggest that the IL-17A pathway may play a more important role in PPPP than in NPPPP.

Keywords: IL-17; IL-23; Palmoplantar psoriasis; Palmoplantar pustular psoriasis; Psoriasis; Skin biopsies.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Biopsy
  • Cytokines / metabolism*
  • Elbow
  • Female
  • Flow Cytometry
  • Humans
  • Immunohistochemistry
  • Interleukin-17 / metabolism*
  • Interleukin-23 Subunit p19 / metabolism*
  • Leg
  • Male
  • Mast Cells / metabolism
  • Middle Aged
  • Peptidoglycan
  • Psoriasis / metabolism*
  • Quality of Life
  • Reverse Transcriptase Polymerase Chain Reaction
  • Scalp
  • Signal Transduction
  • Skin / cytology
  • Skin / metabolism
  • Skin / pathology
  • Torso
  • Young Adult


  • Cytokines
  • IL17A protein, human
  • IL23A protein, human
  • Interleukin-17
  • Interleukin-23 Subunit p19
  • Peptidoglycan
  • pneumococcal purpura-producing principle