Differential Influence of IL-9 and IL-17 on Actin Cytoskeleton Regulates the Migration Potential of Human Keratinocytes.

T cells mediate skin immune surveillance by secreting specific cytokines and regulate numerous functions of keratinocytes, including migration during homeostasis and disease pathogenesis. Keratinocyte migration is mediated mainly by proteolytic cleavage of the extracellular matrix and/or by cytoskeleton reorganization. However, the cross-talk between T cell cytokines and actomyosin machinery of human primary keratinocytes (HPKs), which is required for cytoskeleton reorganization and subsequent migration, remains poorly examined. In this study, we describe that IL-9 profoundly reduced the actin stress fibers, inhibited contractility, and reduced the cortical stiffness of HPKs, which resulted in inhibition of the migration potential of HPKs in an adhesion- and MMP-independent manner. Similarly, IL-9 inhibited the IFN-γ-induced migration of HPKs by inhibiting the actomyosin machinery (actin stress fibers, contractility, and stiffness). IL-17A increased the actin stress fibers, promoted cellular contractility, and increased proteolytic collagen degradation, resulting in increased migration potential of HPKs. However, IL-9 inhibited the IL-17A-mediated HPKs migration. Mechanistically, IL-9 inhibited the IFN-γ- and IL-17A-induced phosphorylation of myosin L chain in HPKs, which is a major regulator of the actomyosin cytoskeleton. Finally, in addition to HPKs, IL-9 inhibited the migration of A-431 cells (epidermoid carcinoma cells) induced either by IFN-γ or IL-17A. In conclusion, our data demonstrate the influence of T cell cytokines in differentially regulating the actomyosin cytoskeleton and migration potential of human keratinocytes, which may have critical roles in skin homeostasis and pathogenesis of inflammatory diseases as well as skin malignancies.