human mesenchymal stem cells elevate cd4+cd25+cd127low/- regulatory t cells of asthmatic patients via heme oxygenase-1.

up-regulation of cd4+cd25+cd127low/- regulatory t cells (tregs) is a new target in the treatment of asthma. human bone marrow mesenchymal stem cells can up-regulate cd4+cd25+cd127low/- regulatory t cells in vitro,  meanwhile, heme oxygenase-1 (ho-1) plays an important role in the development and maintenance of cd4+cd25+ regulatory t cells. however the mechanism has not yet been adequately understood. hence, we wondered what effect of heme oxygenase-1 made on regulation of cd4+cd25+cd127low/-  regulatory t cells mediated by mesenchymal stem cells. peripheral blood mononuclear cells isolated from asthmatic patients and healthy controls were co-cultured with human bone marrow mesenchymal stem cells which were pretreated with hemin (the revulsive of heme oxygenase-1), protoporphyrin ⅸ zinc (the inhibitor of heme oxygenase-1) and saline. the expression of heme oxygenase-1 in mscs was enhanced by hemin and inhibited by protoporphyrin  zinc in vitro. overexpression of heme oxygenase-1 elevated the proportion of cd4+cd25+cd127low/- regulatory t cells in cd4+ t cells, meanwhile, inhibition of heme oxygenase-1 decreased the proportion of cd4+cd25+cd127low/- regulatory t cells in cd4+ t cells as compared with mesenchymal stem cells alone. taken together, these data demonstrated that heme oxygenase-1 contributed to the up-regulation of cd4+cd25+cd127low/- regulatory t cells mediated by mesenchymal stem cells in asthma.