IL-17 and IL-22 link the inflammatory response to the immature differentiation and epithelial regeneration by acting directly on keratinocytes (KCs) to promote cell stemness in psoriasis, a recent study found. Researchers applied flow cytometry on KCs from lesional and non-lesional epidermis to characterize the phenotype in the germinative compartment in psoriasis and observed an overall increase in the stemness markers CD29 (2.4 fold), CD44 (2.9 fold), CD49f (2.8 fold), and p63 (1.4 fold). They found:
- There was a reduced percentage of cells positive for the early differentiation marker, cytokeratin 10 (K10), and a greater fraction of CD29+ and involucrin+ cells in the psoriasis KCs than in non-lesional KCs.
- The upregulation of stemness markers was more pronounced in the K10+ cells.
- Furthermore, the psoriasis cells were smaller, indicating increased proliferation.
- Treatment with IL-17 and IL-22 induced a similar expression pattern of an upregulation of p63, CD44, and CD29 in normal KCs and increased the colony-forming efficiency and long-term proliferative capacity, reflecting increased stem cell-like characteristics in the KC population.
Ekman A-K, Eding CB, Rundquist I, Enerbäck C. IL-17 and IL-22 promote keratinocyte stemness in the germinative compartment in psoriasis. [Published online ahead of print January 23, 2019]. J Invest Dermatol. doi:10.1016/j.jid.2019.01.014.