Ferritinemia during type 1 Gaucher disease: mechanisms and progression under treatment.

BACKGROUND: Earlier results highlighted hyperferritinemia during type-1 Gaucher disease (GD), but its potential mechanisms and long-term progression remained unexamined. METHODS: We analyzed the clinical, biological and iron characteristics of type-1 GD patients, before and after starting enzyme-replacement therapy (ERT). Iron parameters under ERT were subjected to linear-regression analyses. RESULTS: Serum ferritin (median 739 [46-2371] µg/L) was determined for 54 patients (21 (39%) males; median age 32 [range 12-73] years) before ERT; it exceeded 300 µg/L in 47 (87%), while the other iron parameters always remained normal: transferrin saturation coefficient (26 [16-42]), serum iron at 13 [6-22] mmol/L and transferrin at 2.4 [2,3] g/L. Four patients had mild elevation of liver transaminases, with C-reactive protein >20mg/l in two. The absence of hemolysis was accompanied by a median bilirubin of 9 µmol/L and lactate dehydrogenase at 250 IU/L; diabetes and lipid anomalies were not observed. Clinical, biological and iron parameters at GD diagnosis were comparable for the 12 and 42 patients with ferritinemia ≤400 and >400 µg/L, respectively. Ferritinemia was measured at least once for 46 patients after ERT onset (median treatment duration 90 [3-204] months). At study closure, median serum ferritin was 187.5 [11-1560] µg/L, exceeding 300 µg/L in 15 (33%) patients, while the other iron parameters were normal. Among the latter, only the mean±SD ferritinemia slope decreased significantly under ERT (-1.9±0.3%/month; p<0.001). CONCLUSION: Hyperferritinemia is a specific GD characteristic and serum ferritin monitoring could be informative during follow-up.

Impact of imiglucerase on the serum glycosylated-ferritin level in Gaucher disease.

Gaucher disease (GD) is a lysosomal storage disorder, caused by deficient activity of the enzyme glucocerebrosidase, which can be treated by enzyme-replacement therapy (ERT). No prognostic marker can predict long-term complications of GD but several markers are used in therapeutic monitoring: chitotriosidase, total serum ferritin (TSF), angiotensin-converting enzyme (ACE) and tartrate-resistant acid phosphatase (TRAP). They all increase with disease progression and generally decrease under ERT. This study was undertaken to investigate ferritin glycoforms, i.e., glycosylated ferritin (GF) and non-glycosylated ferritin (NGF) concentrations, as potential markers for the follow-up of GD therapy. GF and NGF determinations for GD patients followed in a single center between 1996 and 2007 were analyzed using two approaches: (1) the serum levels of 12 untreated patients were compared with those of 10 patients after 48 months on ERT; (2) the evolution of serum levels under ERT in 15 patients were analyzed using linear/logarithmic mixed models. TSF and NGF levels did not differed significantly between untreated patients and those on ERT (TSF: 524.5 (range 221.0-2045.0) µg/L vs. 410.5 (range 115.0-1587.0) µg/L, respectively, p=0.72; NGF: 340.0 (range 182.8-1717.8) µg/L vs. 199.9 (range 77.1-649.8) µg/L, p=0.09). The percent GF was significantly lower in untreated patients than in those on ERT (27.0% (range 8.0-51.0) vs. 43.5% (range 22.0-80.0) respectively; p=0.02). The percent GF increased significantly during ERT (slope=0.156% [95% confidence interval (CI), 0.03; 0.29] per month, p=0.01) regardless of whether NGF and TSF significantly decreased during ERT (slope=-1.4% per month [95%CI, -1.9%; -1.0%], p<0.0001; slope=-1.1% [95%CI, -1.6%; -0.6%] per month, p<0.0007, respectively). Thus, GF is low in untreated GD patients. GF and NGF changed significantly under ERT and might be of clinical value for GD management under treatment.

A prospective study of bone marrow hematopoietic and mesenchymal stem cells in type 1 Gaucher disease patients.

Gaucher disease (GD) is an autosomal recessive disorder characterized by lysosomal glucocerebrosidase (GBA) deficiency leading to hematological and skeletal manifestations. Mechanisms underlying these symptoms have not yet been elucidated. In vivo, bone marrow (BM) mesenchymal stem cells (MSCs) have important role in the regulation of bone mass and in the support of hematopoiesis, thus representing potential candidate that could contribute to the disease. GBA deficiency may also directly impair hematopoietic stem/progenitors cells (HSPCs) intrinsic function and induce hematological defect. In order to evaluate the role of BM stem cells in GD pathophysiology, we prospectively analyzed BM-MSCs and HSPCs properties in a series of 10 patients with type 1 GD. GBA activity was decreased in all tested cell subtypes. GD-MSCs had an impaired growth potential, morphological and cell cycle abnormalities, decreased capacities to differentiate into osteoblasts. Moreover, GD-MSCs secreted soluble factors that stimulated osteoclasts resorbing activities. In vitro and in vivo primitive and mature hematopoiesis were similar between patients and controls. However, GD-MSCs had a lower hematopoietic supportive capacity than those from healthy donors. These data suggest that BM microenvironment is altered in GD and that MSCs are key components of the manifestations observed in GD.

Bone marrow microenvironment in an in vitro model of Gaucher disease: consequences of glucocerebrosidase deficiency.

Gaucher disease (GD) is a lysosomal storage disorder due to glucocerebrosidase (GBA) deficiency. Mechanisms leading to the emergence of hematological and skeletal manifestations observed in GD are poorly explained. Bone marrow (BM) mesenchymal stem cells (MSCs) are multipotent progenitors that participate in the regulation of bone mass. MSCs should thus represent a cell population involved in the development or progression of bone disease in GD. In a chemical model of GD obtained with Conduritol ß epoxide (CBE), a specific inhibitor of GBA activity, we functionally characterized BM MSCs and specifically analyzed their capacity to differentiate into osteoblasts. GBA deficiency obtained with CBE treatment, leads to a dramatic impairment of MSCs proliferation and to morphological abnormalities. Although the capacity of MSCs to differentiate into osteoblasts was not modified, the levels of several soluble factors that regulate bone metabolism were increased in MSCs treated with CBE, compared with untreated MSCs. Moreover, addition of conditioned media from CBE-treated MSCs on monocyte-derived osteoclasts cultured on bone matrix leads to an increase of resorption areas. These data suggested that, in GD, MSCs represents a stem cell population that is likely to be involved in bone pathogenesis.

The French Gaucher's disease registry: clinical characteristics, complications and treatment of 562 patients.

BACKGROUND: Clinical features, complications and treatments of Gaucher's disease (GD), a rare autosomal-recessive disorder due to a confirmed lysosomal enzyme (glucocerebrosidase) deficiency, are described. METHODS: All patients with known GD, living in France, with ≥ 1 consultations (1980-2010), were included in the French GD registry, yielding the following 4 groups: the entire cohort, with clinical description; and its subgroups: patients with ≥ 1 follow-up visits, to investigate complications; recently followed (2009-2010) patients; and patients treated during 2009-2010, to examine complications before and during treatment. Data are expressed as medians (range) for continuous variables and numbers (%) for categorical variables. RESULTS: Among the 562 registry patients, 265 (49.6%) were females; 454 (85.0%) had type 1, 22 (4.1%) type 2, 37 (6.9%) perinatal-lethal type and 21 (3.9%) type 3. Median ages at first GD symptoms and diagnosis, respectively, were 15 (0-77) and 22 (0-84) years for all types. The first symptom diagnosing GD was splenomegaly and/or thrombocytopenia (37.6% and 26.3%, respectively). Bone-marrow aspiration and/or biopsy yielded the diagnosis for 54.7% of the patients, with enzyme deficiency confirming GD for all patients. Birth incidence rate was estimated at 1/50,000 and prevalence at 1/136,000. For the 378 followed patients, median follow-up was 16.2 (0.1-67.6) years. Major clinical complications were bone events (BE; avascular necrosis, bone infarct or pathological fracture) for 109 patients, splenectomy for 104, and Parkinson's disease for 14; 38 patients died (neurological complications for 15 type-2 and 3 type-3 patients, GD complications for 11 type-1 and another disease for 9 type-1 patients). Forty-six had monoclonal gammopathy. Among 283 recently followed patients, 36 were untreated and 247 had been treated during 2009-2010; 216 patients received treatment in December 2010 (126 with imiglucerase, 45 velaglucerase, 24 taliglucerase, 21 miglustat). BE occurred before (130 in 67 patients) and under treatment (60 in 41 patients) with respective estimated frequencies (95% CI) of first BE at 10 years of 20.3% (14.1%-26.5%) and 19.8% (13.5%-26.1%). CONCLUSION: This registry enabled the epidemiological description of GD in France and showed that BE occur even during treatment.