Paula Rozenfeld

Polyphenoloxidase activity from strawberry fruit (Fragaria ananassa, Duch., cv Selva): characterisation and partial purification

In this work, polyphenoloxidase (PPO) from Selva strawberry fruit (Fragaria × ananassa, Duch) was extracted, characterised and partially purified. The activity of PPO was analysed in crude extracts obtained from either fresh fruits or acetone powder. The presence of NaCl and Triton X-100 in the extraction buffer caused a marked increase in enzyme extractability. The enzyme showed an apparent Km value of 11.2 mM with pyrocatechol as substrate. The maximum enzyme activity was observed at 50 °C and pH 5.3–6.0 without SDS and pH 7.2 in the presence of SDS. The presence of SDS increased PPO activity at pH 7.2 but diminished it at pH 6.0. The enzyme showed high thermal stability and maintained activities equal to or greater than 50% of its maximum activity in the 2.6–9.3 pH range. One polyphenoloxidase isoenzyme was detected in crude extracts of all ripening stages, showing an isoelectric point of 7.3. The specific activity of PPO decreased continuously through fruit ripening. Maximum specific activities were found at the ‘small green’ and ‘large green’ ripening stages. A total enzyme extract was partially purified by means of (NH4)2SO4 precipitation and cationic exchange chromatography in an FPLC system. The purification grade achieved was near 25. The partially purified enzyme showed an isoelectric point equal to 7.3 and a molecular mass of 135 ± 4 kDa for the native protein. © 2000 Society of Chemical Industry

Fabry disease peripheral blood immune cells release inflammatory cytokines: Role of globotriaosylceramide

Fabry disease is an X-linked lysosomal disorder (LD) due to deficiency of the enzyme α-galactosidase A (αGal), which leads to the accumulation of neutral glycosphingolipids, mainly globotriaosylceramide (Gb3). Several mechanisms contribute to the diverse physiopathological alterations observed in this disease, and it has been suggested that an underlying proinflammatory state could play a significant role. The aim of this study is to investigate the presence of a proinflammatory state in the different subsets of peripheral blood mononuclear cells (PBMC) and to understand the mechanisms that contribute to its onset and perpetuation. We have shown that cultured PBMC from Fabry patients present a higher proinflammatory cytokine expression and production. Moreover, we determined that among PBMC, dendritic cells and monocytes present a basal proinflammatory cytokine production profile, which is further exacerbated with an inflammatory stimulus. Finally we established that normal, monocyte-derived dendritic cells and macrophages display the same proinflammatory profile when cultured in the presence of Gb3 and an inhibitor of αGal. Furthermore, this effect can be abolished using a TLR4 blocking antibody, indicating that TLR4 is necessary in the process. In summary, our results demonstrate the presence of a proinflammatory state involving two key subsets of innate immunity, and provide direct evidence of Gb3 having a proinflammatory role, likely mediated by TLR4, a finding that could help in the understanding of the underlying causes of the inflammatory pathogenesis of Fabry disease.

Leukocyte perturbation associated with Fabry disease

SummaryFabry disease is an X-linked lysosomal storage disorder of glycosphingolipid catabolism due to the deficient activity of the enzyme alpha-galactosidase A. The non-degraded substrate, mainly globotriaosylceramide (Galα1-4Galβ1-4Glcβ1-1Cer; Gb3) accumulates progressively in the lysosome of various cells. The aim of this work was to analyse changes in leukocyte subpopulations and surface markers and to determine whether Gb3 is increased in leukocytes of patients with untreated and treated Fabry disease. Blood samples obtained from 22 male Fabry patients (11 untreated and 11 on enzyme replacement therapy) and 22 normal controls were subjected to flow cytometric analysis of Gb3 intracellular content, leukocyte subpopulations and cell markers. Based on the fluorescence intensity of bound monoclonal antibody, and relative to normal control leukocytes, Gb3 appeared significantly increased in lymphocytes (but not in monocytes or granulocytes) from patients with Fabry disease. A significantly higher percentage of lymphocytes and CD19+ cells and a reduced proportion of monocytes, CD8+ cells and myeloid dendritic cells were detected in samples from Fabry patients compared with normal controls. CD1d expression was significantly lower and MHC class II surface expression was significantly higher in monocytes from Fabry patients than in normal controls. As previously observed for other adhesion molecules, the expression of CD31 (PECAM) was higher in leukocytes from Fabry patients. In conclusion, the differences recorded in this study reveal a leukocyte perturbation associated with the disease state in Fabry patients, whereas some abnormalities are less marked in treated patients.

Induction of osteoclastogenesis in an in vitro model of Gaucher disease is mediated by T cells via TNF-α

Gaucher disease is a lysosomal storage disorder caused by deficiency of glucocerebrosidase enzymatic activity leading to accumulation of its substrate glucocerebrosidase mainly in macrophages. Skeletal disorder of Gaucher disease is the major cause of morbidity and is highly refractory to enzyme replacement therapy. However, pathological mechanisms of bone alterations in Gaucher disease are still poorly understood. We hypothesized that cellular alteration in Gaucher disease produces a proinflammatory milieu leading to bone destruction through enhancement of monocyte differentiation to osteoclasts and osteoclasts resorption activity. Against this background we decided to investigate in an in vitro chemical model of Gaucher disease, the capacity of secreted soluble mediators to induce osteoclastogenesis, and the mechanism responsible for this phenomena. We demonstrated that soluble factors produced by CBE-treated PBMC induced differentiation of osteoclasts precursors into mature and active osteoclasts that express chitotriosidase and secrete proinflammatory cytokines. We also showed a role of TNF-α in promoting osteoclastogenesis in Gaucher disease chemical model. To analyze the biological relevance of T cells in osteoclastogenesis of Gaucher disease, we investigated this process in T cell-depleted PBMC cultures. The findings suggest that T cells play a role in osteoclast formation in Gaucher disease. In conclusion, our data suggests that in vitro GCASE deficiency, along with concomitant glucosylceramide accumulation, generates a state of osteoclastogenesis mediated in part by pro-resorptive cytokines, especially TNF-α. Moreover, T cells are involved in osteoclastogenesis in Gaucher disease chemical model.

Uncoupling of osteoblast-osteoclast regulation in a chemical murine model of Gaucher disease

Gaucher disease (GD) is caused by mutations in the GBA gene that confer a deficient level of activity of glucocerebrosidase (GCase). This deficiency leads to accumulation of the glycolipid glucocerebroside in the lysosomes of cells of monocyte/macrophage system. Type I GD is the mildest form and is characterized by the absence of neuronopathic affection. Bone compromise in Gaucher disease patients is the most disabling aspect of the disease. However, pathophysiological aspects of skeletal alterations are still poorly understood. The homeostasis of bone tissue is maintained by the balanced processes of bone resorption by osteoclasts and formation by osteoblasts. We decided to test whether bone resorption and/or bone formation could be altered by the use of a chemical in vitro murine model of Gaucher disease. We used two sources of cells from monocyte/macrophages lineage isolated from normal mice, splenocytes (S) and peritoneal macrophages (PM), and were exposed to CBE, the inhibitor of GCase (S-CBE and PM-CBE, respectively). Addition of both conditioned media (CM) from S-CBE and PM-CBE induced the differentiation of osteoclasts precursors from bone marrow to mature and functional osteoclasts. TNF-α could be one of the factors responsible for this effect. On the other hand, addition of CM to an osteoblast cell culture resulted in a reduction in expression of alkaline phosphatase and mineralization process. In conclusion, these results suggest implication of changes in both bone formation and bone resorption and are consistent with the idea that both sides of the homeostatic balance are affected in GD.

Two-dimensional speckle tracking echocardiography for early detection of myocardial damage in young patients with Fabry disease.

Fabry disease (FD) is characterized by left ventricular hypertrophy (LVH). Conventional echocardiography is not sensitive enough to perform the preclinical diagnosis To assess whether longitudinal myocardial strain of the left ventricle (LV), using speckle tracking, is useful to detect early myocardial involvement in FD. Forty‐four patients with FD who were diagnosed with genetic testing were prospectively included and were compared to a sex‐matched control group. They were divided into three groups: 22 with LVH (Group I), 22 without LVH (Group II), and 22 healthy volunteers (Group III). LV longitudinal strain was measured from the apical views. An ANOVA test was used for multiple comparisons for variables with a normal distribution, and a Kruskal–Wallis test was used for variables with non‐Gaussian distribution. Longitudinal LV strain was different in the three groups: it was ≥−15% in at least one segment in all Group I patients, in 50% of patients of Group II and in no patient of Group III. Seventy percent of the segments with abnormal strain in Group II were located in the basal regions (32/46). These findings show that the presence of at least one strain value ≥−15% demonstrates subclinical myocardial dysfunction in patients with preclinical FD. Longitudinal myocardial LV strain measured with speckle tracking is a useful tool to detect early myocardial involvement in young patients with FD. This information allows the detection and treatment of myocardial dysfunction at an early stage, which is of high clinical importance.

Fabry Disease: Treatment and diagnosis

Fabry disease is an X‐linked lysosomal disorder that results from a deficiency of the lysosomal enzyme α‐galactosidase A leading to accumulation of glycolipids, mainly globotriaosylceramide in the cells from different tissues. Classical Fabry disease affects various organs. Clinical manifestations start at early age and include angiokeratoma, acroparesthesia, hypohydrosis, heat/exercise intolerance, gastrointestinal pain, diarrhea, and fever. The main complications of Fabry disease are more prominent after the age of 30 when kidney, heart, and/or cerebrovascular disorders appear. Most of the heterozygous females are symptomatic. Enzyme replacement therapy (ERT) is the only specific treatment for Fabry disease. The beneficial effect of ERT on different organs/systems has been extensively evaluated. Quality of life of patients receiving ERT is improved. Enzyme replacement stabilizes or slows the decline in renal function and reduces left ventricular hypertrophy. Fabry disease may be underdiagnosed because of nonspecific and multiorgan symptoms. Different screening strategies have been carried out in different at‐risk populations in order to detect undiagnosed Fabry patients. An increasing knowledge about Fabry disease within the medical community increases the chances of patients to receive a timely diagnosis and, consequently, to access the appropriate therapy.

A successful approach for the detection of Fabry patients in Argentina

Fabry disease is an X‐linked lysosomal disorder caused by the deficiency of the lysosomal enzyme α‐galactosidase A (α‐Gal A). In males, the laboratory diagnosis is based on the demonstration of decreased levels of α‐Gal A activity, while in females, the disease is diagnosed by the identification of a mutation in α‐Gal A gene. Fabry disease in Argentina is underdiagnosed. To date, no comprehensive screening study of Fabry disease in our country has been reported. The present study aimed at developing a targeted screening for the detection of Fabry patients from Argentina based on the set of typical signs and symptoms. We received 121 blood samples from probable Fabry patients for enzymatic and genetic assay. We diagnosed six Fabry patients from six unrelated families, representing a yield of detection of 4.96%. The mutations detected in five of the families analysed were missense mutations: p.Leu243Trp, p.Asp155His, p.Leu415Pro, p.Cys94Tyr and p.Leu191Pro. After the detection of a Fabry patient, his/her relatives were also screened. In the course of these family studies, other 64 Fabry patients, 29 males and 35 females, were detected. To our knowledge, this is the first comprehensive screening of Fabry disease in Argentina. We detected 70 patients in a period of 2.5 years. The development of targeted protocols and the constitution of interdisciplinary groups for the identification of patients with Fabry disease are recommended to obtain a higher yield in the process.

Treatment of Fabry Disease: Current and Emerging Strategies

Fabry disease is an X-linked lysosomal storage disorder (LSD) due to deficiency of the enzyme α-galactosidase A (GLA). Absent or reduced enzyme activity leads to impaired catabolism of neutral glycosphingolipids, particularly globotriaosylceramide (Gb3), resulting in intracellular deposition of such lipids. Clinical manifestations in hemizygote males include angiokeratoma, hypohydrosis, acroparesthesia, abdominal pain, proteinuria, renal insufficiency, left ventricular hypertrophy and cerebrovascular accidents. Heterozygote women may present with mild to severe signs and symptoms. Since year 2001, enzyme replacement therapy (ERT) is the only specific treatment for Fabry disease. The beneficial effect of ERT on different organs/systems has been extensively evaluated, and an improvement in renal function, cardiac mass and quality of life has been reported. Different treatment approaches are currently on development. One of them implies the use of the active-site-specific chaperone 1-deoxygalactonojirimycin that acts facilitating folding of mutant GLA in the endoplasmic reticulum and increasing its lysosomal residual activity. Reduction of Gb3 deposits has been shown in lymphoblasts from Fabry patients with missense mutations and transgenic mouse model expressing a missense mutation GLA. Gene therapy has been also developed as a potential option for treatment of Fabry disease. This review will discuss these novel therapeutic options along with their advantages and limitations.

An easy and sensitive method for determination of globotriaosylceramide (Gb3) from urinary sediment: Utility for Fabry disease diagnosis and treatment monitoring

BACKGROUND Fabry disease is an X-linked disorder that results from the deficiency of the lysosomal enzyme alpha-galactosidase A. The defect leads to the accumulation of globotriaosylceramide (Gb3). The detection of Gb3 accumulated in different tissues may help in the diagnosis and enzyme replacement therapy monitoring. For this reason, we developed a simple method available to clinical laboratories to measure this analyte. METHODS Gb3 excretion was determined by the incubation of urine sediment glycolipids from Fabry patients with agalsidase alpha and subsequent determination of galactose produced. RESULTS The amount of urinary Gb3 in Fabry hemizygotes was significantly higher (p = 0.00001) than the amount in normal controls. Patients undergoing enzyme replacement therapy with agalsidase alpha showed a significantly lower content of Gb3 in urine sediment. This method showed a good recovery and comparability with a previously validated method. CONCLUSIONS We developed an easy method for quantification of Gb3 in urine samples from Fabry patients, by the use of the specific recombinant enzyme for this glycolipid, that does not require complex infrastructure. Urinary Gb3 as measured by this enzymatic method could be useful for the diagnosis and monitoring of treatment in Fabry patients.