Failure of resting echocardiography and cardiac catheterization to identify pulmonary hypertension in two patients with type I Gaucher disease

Macrophage-derived soluble CD163 level in young patients with Gaucher disease: relation to phenotypes, disease severity and complications

OBJECTIVES

Bone and lung involvement are two major causes of morbidity in Gaucher disease (GD). The soluble form of CD163 (sCD163) is a valuable diagnostic biomarker for monitoring diseases with increased macrophage activation. We determined sCD163 levels in 30 children and adolescence with GD compared with 30 healthy controls and assessed the relation to phenotypes, disease severity and complications.

METHODS

Thirty GD patients (10 had type 1 and 20 had type 3) were studied stressing on skeletal, pulmonary or neurological manifestations, enzyme replacement therapy (ERT), hematological profile, plasma chitotriosidase activity, D-dimer and sCD163. Liver and spleen volumes and bone mineral density (BMD) were assessed.

RESULTS

sCD163 levels were markedly elevated in patients compared with controls. D-dimer, chitotriosidase activity and sCD163 levels were significantly increased in type 3 GD patients compared with type 1. sCD163 was significantly elevated in GD patients with dysphagia, developmental delay, pulmonary hypertension risk or abnormal BMD (osteopenia/osteoporosis) than those without. GD patients receiving ERT every 2weeks had lower levels than those under ERT for more than 2weeks. sCD163 was positively correlated with age, disease duration, severity score index, D-dimer and chitotriosidase activity. The cutoff value of sCD163 at 9400ng/mL could differentiate GD patients with and without pulmonary hypertension risk with a sensitivity of 90% and specificity of 95%.

CONCLUSIONS

sCD163 is a biomarker for the clinical assessment of macrophage proliferation and activity that would help in risk prediction of bone and lung involvement and monitoring treatment response.

Echocardiographic Assessment of Left Ventricular Function in Type 1 Gaucher's Disease

There is predominate opinion among physicians managing type 1 Gauchers' disease (GD) that cardiac involvement is not an issue in these patients. In order to follow this hypothesis, we prospectively investigated 15 adult imiglucerase-treated type 1 GD patients by echocardiography, Doppler, and tissue Doppler echocardiography. This was a case-controlled study with 18 matched healthy volunteers. The obtained data was correlated with the levels of NT-proBNP (brain natriuretic peptide). None of the GD patients had clinical signs of heart disease. In 3 of the 15 patients, we observed echocardiographic signs of aortic and mitral valve calcification. The left ventricular systolic function was within normal limits. Compared to the control group, there was no statistically significant difference observed in the most sensitive indices of left ventricular diastolic function, parameter E_m (P = .095), and E/E_m ratio (P = .097), as demonstrated by tissue Doppler echocardiography. However, there was a positive correlation between the E/E_m ratio and NT-proBNP plasma levels (P = .009). In conclusion, the prospective echocardiographic study of type 1 GD patients did not validate any left ventricular dysfunction. But, the E/E_m ratio showed a strong statistical correlation with the most sensitive indicators of heart failure, NT-proBNP. Research on larger groups of patients and the usage of even more sensitive methods as strain-rate imaging will be necessary to confirm eventual myocardial involvement in GD patients.

Delivery of lysosomal enzymes for therapeutic use: glucocerebrosidase as an example

Enzyme therapies for lysosomal storage diseases have developed over the past decade into the standard-of-care for affected patients. Such therapy for Gaucher disease has been the prototype, using natural source or recombinant forms of human acid beta-glucosidase (GCase). In Gaucher disease, macrophages are the repository for the pathological lipid and the target for delivery of GCase. The macrophage mannose receptor provides a Trojan horse for intracellular delivery of intravenously administered GCase (man-GCase) with mannosyl-terminated oligosaccharide chains. Passage through several hostile compartments (e.g., plasma) leads to inefficient delivery of man-GCase to macrophage lysosomes. However, regular infusions of man-GCase re-establishes health in affected patients. Similar results are being obtained in several other lysosomal storage diseases. Evolving gene and chaperone approaches provide alternative treatment strategies.

Therapeutic goals in the treatment of Gaucher disease

Gaucher disease, the most common lysosomal storage disorder, is a heterogeneous multisystem condition. Patients with non-neuronopathic (type 1) Gaucher disease may suffer from hepatomegaly, splenomegaly, thrombocytopenia, bleeding tendencies, anemia, hypermetabolism, skeletal pathology, growth retardation, pulmonary disease, and decreased quality of life. Enzyme replacement therapy (ERT) with mannose-terminated glucocerebrosidase reverses or ameliorates many of the manifestations of type 1 Gaucher disease. However, the variable disease pattern and severity, and the uncertain manner of progression, render the decision to initiate ERT difficult. Thus, implementation of treatment and evaluation of the therapeutic response must be tailored to the individual patient. To obtain an evidence-based consensus on contemporary therapeutic goals, an international panel of physicians with extensive clinical experience in Gaucher disease met to review the extant literature on its treatment. The panel adopted an integrated system-based approach to arrive at a comprehensive guide to individualized management. Here we establish goals of treatment in Gaucher disease and propose a comprehensive schedule of monitoring of all relevant aspects to confirm the achievement, maintenance, and continuity of the therapeutic response.

Pulmonary hypertension in type 1 Gaucher's disease: genetic and epigenetic determinants of phenotype and response to therapy

Type 1 Gaucher's disease (GD) is recognized for striking but unexplained phenotypic diversity. Rarely, severe pulmonary hypertension (PH) may occur in GD but its clinical spectrum, determinants or its response to enzyme replacement therapy (ERT)+/-vasodilators is not known. One hundred and thirty-four consecutive patients with Type 1 GD were screened to estimate right ventricular systolic pressure (RVSP) by Doppler echocardiography. Ninety-four patients were on ERT and 40 were untreated. Eight additional GD patients were studied that represented consecutive tertiary referrals with severe PH. Angiotensin converting enzyme (ACE) gene polymorphisms and acid beta-glucosidase gene (GBA) mutations were determined by DNA analysis. Mild, asymptomatic PH (RVSP>35<50 mmHg) was prevalent in Type 1 GD: 30% in untreated patients and 7.4% among patients receiving ERT (P<0.001). Splenectomy was strongly associated with severe, life-threatening PH: all patients with severe PH (RVSP 50-130 mmHg) were asplenic compared to only 31% of patients with RVSP<50 mmHg (Odds ratio [OR] 28.8, 95% CI 1.6-531.6, P<0.001). Other characteristics of patients presenting with severe PH were poor compliance to ERT (4/9 patients) or no ERT (5/9 patients), a family history of a sib with GD and PH (2/2 patients), an excess of ACE I allele (OR 2.3, 95% CI 1.1-4.9, P=0.034) and an excess of non-N370S GBA mutation (OR 6.0, 95% CI 1.1-33, P=0.003). Severe PH was ameliorated by ERT+/-vasodilators during 4.6+/-4.0 yr (range 1-12 yr) follow-up; three patients were initially considered for lung transplantation but improved such that they are no longer active transplant candidates. Our study reveals a remarkable predisposition for PH in type 1 GD. Progression to severe, life-threatening PH occurs in the presence of additional genetic factors (non-N370S GBA mutation, positive family history, and ACE I gene polymorphism) and epigenetic modifiers (i.e., asplenia and female sex). Splenectomy should be avoided and in high-risk patients, ERT+/-vasodilators/coumadin should be initiated.