Unexpected macrophage-independent dyserythropoiesis in Gaucher disease

Gaucher disease is a rare inherited disease caused by a deficiency in glucocerebrosidase leading to lipid accumulation in cells of mononuclear-macrophage lineage known as Gaucher cells. Visceral enlargement, bone involvement, mild anemia and thrombocytopenia are the major manifestations of Gaucher disease. We have previously demonstrated that the red blood cells from patients exhibit abnormal properties, which indicates a new role in Gaucher disease pathophysiology. To investigate whether erythroid progenitors are affected, we examined the in vitro erythropoiesis from the peripheral CD34⁺ cells of patients and controls. CD34- cells were differentiated into macrophages and co-cultivated with erythroblasts. We showed an accelerated differentiation of erythroid progenitors without maturation arrest from patients compared to controls. This abnormal differentiation persisted in the patients when the same experiments were performed without macrophages, which strongly suggested that dyserythropoiesis in Gaucher disease is secondary to an inherent defect in the erythroid progenitors. The accelerated differentiation was associated with reduced cell proliferation. As a result, less mature erythroid cells were generated in vitro in the Gaucher disease cultures compared to the control. We then compared the biological characteristics of untreated patients according to their anemic status. Compared to the non-anemic group, the anemic patients exhibit higher plasma levels of growth differentiation factor-15, a marker of ineffective erythropoiesis, but they had no indicators of hemolysis and similar reticulocyte counts. Taken together, these results demonstrated an unsuspected dyserythropoiesis that was independent of the macrophages and could participate, at least in part, to the basis of anemia in Gaucher disease.