A cytometric study of the red blood cells in Gaucher disease reveals their abnormal shape that may be involved in increased erythrophagocytosis

Abstract

Background: Gaucher disease is a sphingolipidosis caused by a deficiency of the enzyme glucocerebrosidase. Macrophages transform into pathogenic Gaucher cells following the phagocytosis of red blood cells (RBCs) and subsequent accumulation of glucosylceramide. Enhanced erythrophagocytosis is one feature of the disease indicating abnormal macrophage-RBC interactions. We hypothesized that the erythrophagocytosis observed in Gaucher disease may be at least partly due to abnormalities in the RBCs themselves.Methods: To investigate this hypothesis, we used flow cytometry FSC/SSC to study RBCs sampled from seven patients with Gaucher disease in terms of their shape and the expression of markers of senescence and phagocytosis. Cells from two of the seven patients were evaluated before and 9 months after the start of enzyme-replacement therapy.Results: Untreated patients were found to have abnormal flow-cytometry profiles suggesting an alteration of Gaucher RBC morphology. Scanning electron microscopy confirmed this finding by revealing many abnormally shaped RBCs. Whereas there was no evidence of desialylation of membrane glycoconjugates or phosphatidylserine exposure, RBC viability (calcein-AM test) and CD47 expression were reduced. These anomalies found in RBCs sampled from two patients before treatment, were no longer present after a 9 month-long enzyme-replacement therapy.Conclusions: We report on previously overlooked alterations of Gaucher RBCs that may facilitate erythrophagocytosis in untreated patients. Their potential role in the anemia, the excess of aggregation and rheological anomalies associated with Gaucher disease must now be addressed. RBC anomalies may

Abnormal properties of red blood cells suggest a role in the pathophysiology of Gaucher disease

“…17 Here, we confirm that a significant proportion of RBCs from GD patients with an intact spleen and not under ERT have abnormal shapes. Schistocytes probably result from RBC fragmentation passing through microvessels lined with mesh of fibrin strands.…”

“…We observed significantly greater proportion of abnormal RBC shapes in GD patients (2.90% Ϯ 1%) compared with CTR samples, with presence of dacryocytes ("tear drop" cells), elliptocytes, echinocytes, and schistocytes (supplemental Figure 1, available on the Blood Web site; see the Supplemental Materials link at the top of the online article). This confirms a previous observation, 17 and suggests that GD RBCs may have membrane or cytoskeleton (or both) abnormal properties with potential functional consequences.…”

“…Thus, RBCs could be the primary dysfunctional cells, leading to formation of Gaucher cells in the spleen. It may also be the case in the bone marrow where erythrophagocytosis is frequently reported, 17 and possibly in other organs containing resident macrophages. After they are formed, GlcCer-laden macrophages (Gaucher cells) that display abnormal properties 44,45 may induce further organ dysfunction depending on their specific environment.…”

Physiologically aged red blood cells undergo erythrophagocytosis in vivo but not in vitro

“…13,28,[35][36][37] RBC from subjects with such diseases have been used for EPC studies. 28 Although the results using damaged RBC provided some insight into the process of EPC in vitro, the use of physiologically aged RBC to elucidate the normal mechanism of EPC is a prerequisite to understand phagocytosis of sRBC and the role of this process in pathology.…”

Atypical cytomorphology of Gaucher cells is frequently seen in bone marrow smears from untreated patients with Gaucher disease type 1

“…The erythrocytes of untreated GD patients have been found by Bratosin et al to have an altered morphology and reduced viability which may promote erythrophagocytosis [36]. According to them, the alterations in erythrocyte morphology and viability disappeared after 9 months of ERT.…”