Eltrombopag in paediatric immune thrombocytopenia: Iron metabolism modulation in mesenchymal stromal cells.

Immune thrombocytopenia (ITP) is an autoimmune disease caused by platelet destruction mediated by auto-antibody production. It is characterized by a compromised immune system and alteration of the inflammatory response. Mesenchymal stromal cells (MSCs) play an important role in modulating immune and inflammatory processes, exerting immune-suppressing and anti-inflammatory properties. In ITP-MSCs the activity and survival are strongly impaired. Eltrombopag (ELT) is a thrombopoietin receptor agonist approved in chronic ITP for stimulating platelet production. It has immunomodulating properties by stimulating T and B regulatory cell activity and by promoting a macrophage switch from the pro-inflammatory to the anti-inflammatory phenotype. ELT also exhibits iron-chelating properties. Iron is a crucial element involved in several physiologic processes, but its intracellular accumulation determines cell damages. Therefore, for the first time we analysed the effect of ELT on ITP-MSCs demonstrating its ability to restore survival and activity of MSCs directly and to promote their survival and proliferation indirectly, by iron metabolism modulation.