Interleukin 17A (IL-17A) is the founding member of the family of cytokines that includes Interleukin 17B through Interleukin 17F. It is a potent proinflammatory cytokine that plays a key role in defense against pathogens. IL-17A and IL-17F signal as homodimers or heterodimers through the same receptor, and activate NF-kB, MAPK, and C/EBP pathways. IL-17A increases the frequency and the average size of colony-forming units-fibroblast derived from bone marrow, as well as the proliferation of bone marrow-derived MSCs. IL-17A suppresses osteogenic differentiation and bone formation of bone marrow-derived MSCs. The action of IL-17A on hematopoiesis is deeply reliant on the microenvironment and the induction of other regulators.
