Elevated RAP1A expression correlates with the severity of acute GVHD after umbilical cord blood transplantation

BackgroundAcute graft-versus-host disease (aGVHD) is a complication of allogeneic hematopoietic stem cell transplantation. Ras-related protein 1A (RAP1A) has been recently identified as a novel oncoprotein in several human malignancies. However, its specific role in aGVHD remains unclear.ObjectiveTo study the role of RAP1A in the pathogenesis of aGVHD.Material and methodsStudy participants included six patients with grade 2–4 aGVHD, 13 patients with grade 1 aGVHD, 11 patients without aGVHD, and 12 healthy people. The expression level of RAP1A in whole cells was detected by western blot and qRT-PCR. The proportions of CD4⁺CD25⁺FoxP3⁺ Treg cells (T regulatory cells) and the expression of RAP1A in Treg cells in peripheral blood mononuclear cells (PBMCs) were detected by flow cytometry and the levels of related cytokines in the serum was detected by cytometric bead array.ResultsWe found the level of RAP1A was higher in patients than in healthy individuals. A negative correlation was noted between RAP1A and the number of Treg cells. In addition, the level of IL-10 in patients with grade 2–4 aGVHD was significantly lower than that in healthy donors, however, the level of TNF-ɑ in patients with grade 2–4 aGVHD was higher. Furthermore, we found a negative correlation between levels of IL-10 and RAP1A, and a positive correlation between TNF-ɑ and RAP1A.ConclusionThe expression of RAP1A in patients with aGVHD was significantly increased, and shows potential as a target for the prevention and treatment of aGVHD.