Exploring the Pathophysiologic Cascade Leading to Osteoclastogenic Activation in Gaucher Disease Monocytes Generated via CRISPR/Cas9 Technology.

Gaucher disease (GD) is caused by biallelic pathogenic variants in the acid ß-glucosidase gene (GBA1), leading to a deficiency in the ß-glucocerebrosidase (GCase) enzyme activity resulting in the intracellular accumulation of sphingolipids. Skeletal alterations are one of the most disabling features in GD patients. Although both defective bone formation and increased bone resorption due to osteoblast and osteoclast dysfunction contribute to GD bone pathology, the molecular bases are not fully understood, and bone disease is not completely resolved with currently available specific therapies. For this reason, using editing technology, our group has developed a reliable, isogenic, and easy-to-handle cellular model of GD monocytes (GBAKO-THP1) to facilitate GD pathophysiology studies and high-throughput drug screenings. In this work, we further characterized the model showing an increase in proinflammatory cytokines (Interleukin-1ß and Tumor Necrosis Factor-α) release and activation of osteoclastogenesis. Furthermore, our data suggest that GD monocytes would display an increased osteoclastogenic potential, independent of their interaction with the GD microenvironment or other GD cells. Both proinflammatory cytokine production and osteoclastogenesis were restored at least, in part, by treating cells with the recombinant human GCase, a substrate synthase inhibitor, a pharmacological chaperone, and an anti-inflammatory compound. Besides confirming that this model would be suitable to perform high-throughput screening of therapeutic molecules that act via different mechanisms and on different phenotypic features, our data provided insights into the pathogenic cascade, leading to osteoclastogenesis exacerbation and its contribution to bone pathology in GD.

Pathology and pathogenic pathways in fabry nephropathy.

BACKGROUND: The pathophysiology of renal damage in Fabry nephropathy involves a complex biological mechanism. The intracellular deposition globotriaosylceramide (Gb3) is just the first step of the mechanism. The glycolipid deposition occurs in all renal cells (endothelial, epithelial and mesangial cells). It stimulates many biological processes, including cytokine release, epithelial-mesenchymal transdifferentiation, oxidative stress and the remodelling of vascular walls, resulting in subtle initial inflammation and eventually tissue fibrosis. It has been hypothesized that the processes activated by Gb3 deposition can subsequently progress independently of cellular deposition and that even Gb3 clearance by specific therapy cannot retard or stop these pathways. AIM: This review aims to gather the reported evidence of these cellular alterations and the resulting histological changes. Our approach is similar to a routine study of kidney biopsy. RESULTS: In the first part of the review, "histology" section, we describe the structures involved (glomeruli, vessels, tubules and interstitium) from a histological point of view. While in the second part, "pathogenesis" section, we present some interpretations about the implicated pathways based on the up-to-date available evidence.

Pathogenesis of Fabry nephropathy: The pathways leading to fibrosis.

BACKGROUND: Kidney is one of the main target organs in Fabry disease, a lysosomal X-linked genetic disorder. Renal involvement is characterized by proteinuria and progressive chronic kidney disease leading to end-stage renal disease. Pathogenic mechanisms in the progression of renal damage in Fabry disease are not thoroughly known yet. The lysosomal Gb3 deposition is the first step of complex pathological pathways resulting in renal sclerosis/fibrosis. Our hypothesis is that Fabry disease associated cellular alterations in tubular cells induce the production of TGF-ß1, which mediate transdifferentiation of renal cells into myofibroblasts resulting in fibrosis of renal tissue. OBJECTIVES: The aim of this work is to study the mechanisms leading to fibrosis in kidney from human Fabry patients. METHODS: Fifteen renal biopsies from naïve Fabry patients were included. Histological and immunohistochemical analysis was carried out. RESULTS: Positive staining for TGF-ß1 was found in tubular epithelial cells in biopsies from Fabry patients. Apoptosis was determined by active caspase 3 staining in tubular and mesangial glomerular cells. Due to TGF-ß1 is the main profibrotic cytokine and induces accumulation of myofibroblasts, we performed a study for its marker α-smooth muscle actin (α-SMA). This study revealed expression of α-SMA on pericytes surrounding peritubular capillaries, smooth muscle cells of blood vessels, mesangial cells and periglomerular zone. TGF-ß1 is produced mainly by tubular cells in Fabry kidney biopsies probably inducing cellular trans-differentiation of renal cells into myofibroblasts. A positive staining for a marker of myofibroblasts was present, affirming the presence of those profibrotic cells. CONCLUSIONS: These results show for the first time that TGF-ß1 is expressed in human renal tissue from Fabry patients, and that this profibrotic cytokine is mainly produced by proximal tubular cells. In addition both, peritubular interstitium and glomeruli, presented cells positive for myofibroblasts markers.

CRISPR/Cas9 Editing for Gaucher Disease Modelling.

Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder caused by mutations in the acid ß-glucosidase gene (GBA1). Besides causing GD, GBA1 mutations constitute the main genetic risk factor for developing Parkinson's disease. The molecular basis of neurological manifestations in GD remain elusive. However, neuroinflammation has been proposed as a key player in this process. We exploited CRISPR/Cas9 technology to edit GBA1 in the human monocytic THP-1 cell line to develop an isogenic GD model of monocytes and in glioblastoma U87 cell lines to generate an isogenic GD model of glial cells. Both edited (GBA1 mutant) cell lines presented low levels of mutant acid ß-glucosidase expression, less than 1% of residual activity and massive accumulation of substrate. Moreover, U87 GBA1 mutant cells showed that the mutant enzyme was retained in the ER and subjected to proteasomal degradation, triggering unfolded protein response (UPR). U87 GBA1 mutant cells displayed an increased production of interleukin-1ß, both with and without inflammosome activation, α-syn accumulation and a higher rate of cell death in comparison with wild-type cells. In conclusion, we developed reliable, isogenic, and easy-to-handle cellular models of GD obtained from commercially accessible cells to be employed in GD pathophysiology studies and high-throughput drug screenings.

A Comprehensive Study of Bone Manifestations in Adult Gaucher Disease Type 1 Patients in Argentina.

Gaucher disease (GD) is the most prevalent lysosomal storage disease, and bone involvement is the most disabling condition. The aim of the present study was to evaluate bone involvement in adult patients with GD, using an observational cross-sectional study. Patients were evaluated using X-rays, bone densitometry (BMD), trabecular bone score (TBS), magnetic resonance imaging (MRI), and biochemical bone markers. Thirty-two type 1GD patients were included (mean age: 40 ± 16 years). Patients had received velaglucerase for 2.7 ± 1.4 years; 19/32 had been treated previously with imiglucerase. Ninety-four percent of subjects met therapeutic goals for hematological parameters, and eight were splenectomized (SPX). Nineteen patients had irreversible bone lesions (IL), i.e., avascular necrosis, bone infarction, and/or vertebral fractures. MRI showed marrow infiltration in 71% of patients. Patients with IL had higher bone marrow burden than those without (p = 0.001). All SPX patients had IL, a higher prevalence of bone marrow edema (p = 0.02), and lower TBS (p = 0.03) than non-SPX patients. Only 18.7% of patients had abnormal BMD, with no correlation with fractures (FX). TBS values were < 1350 in 53% of patients and tended to be lower in those with FX (p = 0.06). Patients with P1NP in the lower quartile had lower TBS (p = 0.03) than those with P1NP in the higher quartiles. TBS correlated moderately but not significantly with P1NP (r = 0.32) and BMB (r = - 0.44). A high prevalence of IL was documented. Bone quality was more affected than BMD in fracture patients. Low bone formation, active bone marrow infiltration, and splenectomy might be implicated in IL.

Prevalence of Fabry Disease in Young Patients with Stroke in Argentina.

BACKGROUND: Fabry disease (FD) is an underdiagnosed cause of stroke in young adults, but the frequency of this association is largely unknown. We estimated the prevalence of FD in a nationwide cohort of young adults who had stroke and transient ischemic attack (TIA) in Argentina. METHODS: This was a prospective, multicenter study of stroke and FD in young adults (18-55 years) conducted in Argentina between 2011 and 2015. Patients were enrolled if they had had a TIA or an ischemic or hemorrhagic stroke within the previous 180 days. FD was diagnosed by measuring α-galactosidase A activity (males) and through genetic studies (females). RESULTS: We enrolled 311 patients (54% men, mean age: 41 years). Ischemic events occurred in 89% of patients (80% infarcts, 9% TIA) and hemorrhagic strokes in 11%. One female (.3% of the total group, 1% of the cryptogenic ischemic strokes) had the pathogenic mutation c.888G>A/p.Met296Ile /Exon 6 on the GAL gene. Her only other manifestation of FD was angiokeratoma. Eighteen females had nonpathogenic intronic variations: c.-10C>T, c.-12G>A, or both. Two patients had the nonpathogenic mutation D313Y, while a third had the likely benign mutation S126G. CONCLUSIONS: FD was identified in 1 patient (.3%) in this first Latin American study. The patient presented with a late-onset oligo-symptomatic form of the disease. A large number of nonpathogenic mutations were present in our cohort, and it is essential that they not be mistaken for pathogenic mutations to avoid unnecessary enzyme replacement treatment.

Contribution of inflammatory pathways to Fabry disease pathogenesis.

Lysosomal storage diseases are usually considered to be pathologies in which the passive deposition of unwanted materials leads to functional changes in lysosomes. Lysosomal deposition of unmetabolized glycolipid substrates stimulates the activation of pathogenic cascades, including immunological processes, and particularly the activation of inflammation. In lysosomal storage diseases, the inflammatory response is continuously being activated because the stimulus cannot be eliminated. Consequently, inflammation becomes a chronic process. Lysosomes play a role in many steps of the immune response. Leukocyte perturbation and over-expression of immune molecules have been reported in Fabry disease. Innate immunity is activated by signals originating from dendritic cells via interactions between toll-like receptors and globotriaosylceramide (Gb3) and/or globotriaosylsphingosine (lyso-Gb3). Evidence indicates that these glycolipids can activate toll-like receptors, thus triggering inflammation and fibrosis cascades. In the kidney, Gb3 deposition is associated with the increased release of transforming growth factor beta and with epithelial-to-mesenchymal cell transition, leading to the over-expression of pro-fibrotic molecules and to renal fibrosis. Interstitial fibrosis is also a typical feature of heart involvement in Fabry disease. Endomyocardial biopsies show infiltration of lymphocytes and macrophages, suggesting a role for inflammation in causing tissue damage. Inflammation is present in all tissues and may be associated with other potentially pathologic processes such as apoptosis, impaired autophagy, and increases in pro-oxidative molecules, which could all contribute synergistically to tissue damage. In Fabry disease, the activation of chronic inflammation over time leads to organ damage. Therefore, enzyme replacement therapy must be started early, before this process becomes irreversible.

Osteocyte Alterations Induce Osteoclastogenesis in an In Vitro Model of Gaucher Disease.

Gaucher disease (GD) is caused by mutations in the glucosylceramidase ß (GBA 1) gene that confer a deficient level of activity of glucocerebrosidase (GCase). This deficiency leads to the accumulation of the glycolipid glucocerebroside in the lysosomes of cells, mainly in the monocyte/macrophage lineage. Its mildest form is Type I GD, characterized by non-neuronopathic involvement. Bone compromise is the most disabling aspect of the Gaucher disease. However, the pathophysiological aspects of skeletal alterations are not yet fully understood. The bone tissue homeostasis is maintained by a balance between resorption of old bone by osteoclasts and new bone formation by osteoblasts. A central player in this balance is the osteocyte as it controls both processes. We studied the involvement of osteocytes in an in vitro chemical model of Gaucher disease. The osteocyte cell line MLO-Y4 was exposed to conduritol-ß-epoxide (CBE), an inhibitor of GCase, for a period of 7, 14 and 21 days. Conditioned media from CBE-treated osteocytes was found to induce osteoclast differentiation. GCase inhibition caused alterations in Cx43 expression and distribution pattern and an increase in osteocyte apoptosis. Osteoclast differentiation involved osteocyte apoptotic bodies, receptor activator of nuclear factor κ-B ligand (RANKL) and soluble factors. Thus, our results indicate that osteocytes may have a role to play in the bone pathophysiology of GD.

Apical left ventricular hypertrophy and mid-ventricular obstruction in fabry disease.

We report the case of a rare cardiac presentation of Fabry disease. Although concentric left ventricular hypertrophy is a major cardiac finding in Fabry disease, there is no case report of dynamic obstruction at mid-left ventricular level. We describe a 59-year-old-woman suffering from a severe form of Fabry disease, mimicking an apical hypertrophic cardiomyopathy with mid-ventricular obstruction. Differentiation of Fabry disease from hypertrophic cardiomyopathy is crucial given the therapeutic and prognostic differences. Fabry disease should always be suspected in an adult, independently of the pattern of left ventricular hypertrophy.

The role of tubular cells in the pathogenesis of Fabry nephropathy.

The pathophysiology of Fabry nephropathy (FN) is induced by galactosidase A deficiency with a chronic exposure of glycolipids to every lineage of renal cells. Tissue damage is attributed to the activation of molecular pathways, resulting in tissue fibrosis and chronic kidney disease. Podocytes have been the primary focus in clinical pathophysiological research because of the striking accumulation of large glycolipid deposits observable in histology. Yet, the tubular interstitium makes up a large portion of the whole organ, and therefore, its role must be further considered in pathogenic processes. In this review, we would like to propose Fabry tubulopathy and its ensuing functional effects as the first pathological signs and contributing factors to the development of FN. We will summarize and discuss the current literature regarding the role of tubular cells in Fabry kidney pathophysiology. Starting from clinical and histological evidence, we will highlight the data from animal models and cell cultures outlining the pathophysiological pathways associated with tubular interstitial injury causing renal fibrosis in Fabry nephropathy.

Agalsidase alfa long-term effect on left ventricular hypertrophy in Fabry disease.

INTRODUCTION: Fabry disease (FD) is an X-linked lysosomal storage disorder affecting glycosphingolipid metabolism. Most FD patients have cardiac involvement, mainly manifested as left ventricular hypertrophy (LVH), leading to early death due to complications (arrhythmias, valvular disease, vascular involvement). Early initiation of enzyme replacement therapy (ERT) before fibrosis development has been associated with better cardiac outcomes in terms of left ventricular mass index (LVMI) and functional parameters. METHODS: A retrospective observational study was conducted in patients with FD treated with agalsidase alfa for at least 2 years. The primary objectives were: [a] to assess the annual rate of change in LVMI; [b] to define the overall incidence of stability, regression or progression of LVMI. RESULTS: Forty-nine patients were included in the final analysis, with a median follow-up of 7 years. The overall change in LVMI was 0.38 g/m2.73/year, without significant influence of baseline LVH, gender, age at ERT initiation, LV ejection fraction, body mass index, renal disease, and classical cardiovascular risk factors. Long-term ERT with agalsidase alfa was associated with stabilization of LVMI in 98% of patients with FD and was independent of the same covariables. CONCLUSION: Our results are in line with previous literature of comparable FD populations and probably represent the first study of its kind in Argentina. We here highlight the importance of cardiac morphometric stability as a positive outcome of ERT.

Introducción: La enfermedad de Fabry (EF) es una enfermedad de almacenamiento lisosomal ligada al cromosoma X que afecta el metabolismo de glicoesfingolípidos. La mayoría de pacientes EF tienen afectación cardíaca, manifestada principalmente como hipertrofia ventricular izquierda (HVI), que conduce a muerte prematura secundaria a complicaciones (arritmias, valvulopatías, afectación vascular). El tratamiento de reemplazo enzimático (TRE) precoz, iniciado antes del desarrollo de la fibrosis, se relaciona con mejores resultados cardíacos en términos del índice de masa ventricular izquierda (IMVI) y parámetros funcionales. Métodos: Se realizó un estudio retrospectivo observacional en que se incluyeron pacientes con EF tratados con agalsidasa alfa por al menos 2 años. Los objetivos primarios fueron: [a] evaluar el cambio anual del IMVI; [b] definir la incidencia global de estabilidad, regresión o progresión del IMVI. Resultados: Se incluyeron 49 pacientes, con seguimiento (mediana) de 7 años. El cambio global en el IMVI fue 0.38 g/m2.73/año, sin influencia significativa de HVI basal, sexo, edad de inicio de TRE, fracción de eyección del VI, índice de masa corporal, insuficiencia renal y factores de riesgo cardiovascular clásicos. La TRE a largo plazo con agalsidasa alfa se relacionó con la estabilización del IMVI en el 98% de los pacientes con EF, independientemente de las mismas covariables. Conclusión: Nuestros resultados están en línea con la bibliografía previa de poblaciones comparables y, probablemente, representan el primer estudio de este tipo en Argentina. Se destaca la importancia de la estabilidad morfométrica cardíaca como resultado positivo de la TRE.

Pathogenic pathways of renal damage in Fabry nephropathy: interplay between immune cell infiltration, apoptosis and fibrosis.

BACKGROUND: Fabry nephropathy is a consequence of the deposition of globotriaosylceramide, caused by deficient GLA enzyme activity in all types of kidney cells. These deposits are perceived as damage signals leading to activation of inflammation resulting in renal fibrosis. There are few studies related to immunophenotype characterization of the renal infiltrate in kidneys in patients with Fabry disease and its relationship to mechanisms of fibrosis. This work aims to quantify TGF-ß1 and active caspase 3 expression and to analyze the profile of cells in inflammatory infiltration in kidney biopsies from Fabry naïve-patients, and to investigate correlations with clinical parameters. METHODS: Renal biopsies from 15 treatment-naïve Fabry patients were included in this study. Immunostaining was performed to analyze active caspase 3, TGF-ß1, TNF-α, CD3, CD20, CD68 and CD163. Clinical data were retrospectively gathered at time of kidney biopsy. RESULTS: Our results suggest the production of TNFα and TGFß1 by tubular cells, in Fabry patients. Active caspase 3 staining revealed that tubular cells are in apoptosis, and apoptotic levels correlated with clinical signs of chronic kidney disease, proteinuria, and inversely with glomerular filtration rate. The cell infiltrates consisted of macrophages, T and B cells. CD163 macrophages were found in biopsy specimens and their number correlates with TGFß1 and active caspase 3 tubular expression. CONCLUSIONS: These results suggest that CD163+ cells could be relevant mediators of fibrosis in Fabry nephropathy, playing a role in the induction of TGFß1 and apoptotic cell death by tubular cells. These cells may represent a new player in the pathogenic mechanisms of Fabry nephropathy.

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.

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.

[Guidelines for diagnosis, monitoring and treatment of Fabry disease]. / Guía para el diagnóstico, seguimiento y tratamiento de la enfermedad de Fabry.

Fabry disease is an X-linked hereditary lysosomal storage disorder caused by deficiency of the enzyme alpha-galactosidase A. Knowledge about this disease, and its medical management, has made remarkable progress in the last decade, including the development of its specific treatment. This guide was developed by medical professionals from various specialties involved in the care of patients with Fabry disease. The discussion and analysis of the available scientific evidence, coupled with the experience of each of the participants, has allowed us to develop the concepts included in this guide in order to provide a useful tool for all professionals who care for patients with Fabry disease.

Opportunities and challenges for newborn screening and early diagnosis of rare diseases in Latin America.

Rare diseases (RDs) cause considerable death and disability in Latin America. Still, there is no consensus on their definition across the region. Patients with RDs face a diagnostic odyssey to find a correct diagnosis, which may last many years and creates a burden for caregivers, healthcare systems, and society. These diagnostic delays have repercussions on the health and economic burden created by RDs and continue to represent an unmet medical need. This review analyzes barriers to the widespread adoption of newborn screening (NBS) programs and early diagnostic methods for RDs in Latin America and provides recommendations to achieve this critical objective. Increasing the adoption of NBS programs and promoting early diagnosis of RDs are the first steps to improving health outcomes for patients living with RDs. A coordinated, multistakeholder effort from leaders of patient organizations, government, industry, medical societies, academia, and healthcare services is required to increase the adoption of NBS programs. Patients' best interests should remain the guiding principle for decisions regarding NBS implementation and early diagnosis for RDs.

Higher apoptotic state in Fabry disease peripheral blood mononuclear cells.: effect of globotriaosylceramide.

Fabry disease is an X-linked lysosomal storage disorder (LSD) due to deficiency of the enzyme α-galactosidase A, resulting in intracellular deposition of globotriaosylceramide (Gb3). Accumulation of Gb3 is probably related to tissue and organ dysfunctions. Diverse pathological mechanisms are elicited in LSDs, giving together the phenotypic expression of each disease. The purpose of the present study is to investigate if apoptosis could play a role in Fabry disease pathogenesis and to understand the mechanisms involved in the proapoptotic state. We have demonstrated that Fabry disease peripheral blood mononuclear cells display a higher apoptotic state, which is reduced by enzyme replacement therapy (ERT), and is mediated, at least in part, by activation of the intrinsic pathway of caspases. We could rule out the implication of "unfolded protein response-ER stress" in this apoptotic process. To further confirm the suggestion that Gb3 is associated to apoptotic cell death, we treated normal cells with Gb3 at concentrations found in Fabry patients. Addition of Gb3 resulted in a dose-dependent induction of apoptosis involving the intrinsic pathway. In summary, PBMC from Fabry patients display a higher apoptotic state, which could be mainly related to elevated Gb3.

Major cardiovascular adverse events in Fabry disease patients receiving agalsidase alfa.

Cardiovascular mortality (CVM) has become the major contributor to overall Fabry disease (FD) mortality in the enzyme replacement therapy (ERT) era. Our objectives were to describe causes and potential predictors of mortality in FD adult patients in Argentina, and to assess risk of major adverse cardiovascular events (MACE) in the ERT era. We retrospectively studied 93 consecutive patients treated with alphagalactosidase A (median follow up: 9.5 years from start of ERT). Mean age at ERT starting was 35 ± 16.3 years. Prevalence of cardiomyopathy and renal disease reached 47% and 41%, respectively. Eleven subjects (11.8%, 95% CI: 5-18%) died during follow up (1.24/100 patient-years). Mean overall survival was 71 years (95% CI: 66-75 years). Seven cases were considered as CVM; main causes were sudden death and stroke. Risk of MACE was 14% (95% CI: 6.9-21.1%; 1.47 events/100 patient-years from start of ERT). All but 2 subjects had at least one comorbid cardiovascular risk factor; however, 86% of patients remained free of MACE during follow-up. CVM remained low and our study was underpowered for detection of predictors of mortality, but it is worth noting that age at diagnosis and ERT starting, left ventricular mass index and renal disease trended to correlate with CVM. Prevalence of hypertension, diabetes and dyslipidemia were lower in FD patients when compared to population level data. As in the Argentinean general population, CVM was the leading cause of mortality among this cohort of consecutive FD patients treated with agalsidase alfa.

La mortalidad cardiovascular (MCV) se ha convertido en el principal contribuyente a la mortalidad general por enfermedad de Fabry (EF) en la era de la terapia de reemplazo enzimático (TRE). Nuestros objetivos fueron describir las causas y posibles predictores de mortalidad en pacientes adultos con EF en la Argentina, y evaluar el riesgo de eventos cardiovasculares mayores (MACE) en la actual era de TRE. Se estudiaron 93 pacientes consecutivos tratados con agalsidasa-alfa por una mediana de 9.5 años tras iniciar TRE. La edad al inicio de TRE fue 35 ± 16.3 años. La prevalencia de cardiomiopatía y enfermedad renal alcanzó 47% y 41%, respectivamente. Once sujetos (11.8%; IC95%: 5-18%) murieron durante el seguimiento (1.24/100 pacientes/año). La supervivencia global fue 71 años (IC95%: 66-75 años). Siete casos fueron considerados como MCV; las principales causas fueron muerte súbita e ictus. El riesgo de MACE fue 14% (IC95%: 6.9-21.1%; 1.47 eventos/100 pacientes/año desde la ERT). Todos menos 2 sujetos tenían al menos un factor de riesgo cardiovascular, pero el 86% permaneció libre de MACE. Los eventos de MCV fueron escasos. El estudio tuvo reducido poder estadístico para detectar predictores de mortalidad, pero la edad al diagnóstico y al iniciar la TRE, índice de masa ventricular izquierda y enfermedad renal tendieron a correlacionarse con MCV. La prevalencia de hipertensión, diabetes y dislipidemia fue menor en comparación con la población general. Como ocurre con la población general en Argentina, los eventos cardiovasculares fueron la principal causa de muerte en esta cohorte de pacientes consecutivos con EF tratados con agalsidasa-alfa.

Early diagnosis of Gaucher disease based on bone symptoms / Diagnóstico temprano de enfermedad de Gaucher mediante detección de manifestaciones óseas.

Gaucher disease (GD) is caused by a genetic deficiency of the lysosomal enzyme glucocerebrosidase (GCase) leading to the accumulation of glucocerebroside in the liver, spleen, and bone marrow. The early diagnosis allows a prompt enzyme replacement therapy reversing cytopenias and visceromegaly and preventing irreversible bone lesions. Current diagnostic algorithms are based on well-recognized hematological manifestations. Although bone symptoms are present in 25-32% of the patients, they are not usually suspected as associated with Gaucher disease at clinical presentation. We designed an educational program aimed to give advice on the skeletal involvement in GD and a new diagnostic algorithm that considers bone symptoms to facilitate its early diagnosis (BIG project: Bone Involvement in Gaucher Disease). The study aims at describing the BIG project and the results of its application in our clinic in various cities in Argentina. Within the frame of this project, between March 2017 and December 2018, 38 dry blood spot samples from patients with bon e manifestations suspected of having GD were submitted to quantification of GCase activity. One sample did not meet the inclusion criteria. Deficient GCase activity was detected in three of the remaining 37 samples. The diagnosis of GD was confirmed in two girls who presented bone manifestations of 4 and 2 years of evolution, respectively, without hematological alterations. The third patient with low enzyme activity had normal leukocyte GCase. The two newly diagnosed cases of GD show the efficacy of our dual strategy aimed to facilitate the early diagnosis of this rare disease.

La enfermedad de Gaucher (EG) es causada p or una deficiencia genética de la glucocerebrosidasa (GCasa) que provoca acumulación de glucocerebrósido en hígado, bazo y médula ósea. La terapia temprana de reemplazo enzimático revierte citopenias, visceromegalias y previene lesiones óseas irreversibles, por lo cual el diagnóstico precoz es fundamental. Los algoritmos diagnósticos en uso apuntan a manifestaciones hematológicas clásicas. Los síntomas óseos están presentes en 25-32% de los pacientes pero no suelen despertar sospecha de EG. Diseñamos un programa educativo sobre la afecta ción ósea de la EG y un algoritmo focalizado en la presentación con manifestaciones óseas para facilitar su diagnóstico precoz (proyecto BIG: Bone Involvement in Gaucher Disease). El objetivo del trabajo es describir el proyecto BIG y los resultados de su aplicación en nuestra consulta. Entre marzo de 2017 y diciembre de 2018 se recibieron 38 muestras de sangre seca de pacientes con alguna manifestación ósea sospechosa de EG para cuantificar la actividad de GCasa. Una muestra no cumplía los criterios de inclusión y en 3 de las 37 restantes se observó actividad deficiente de GCasa. El diagnóstico de EG se confirmó por medición de GCasa en leucocitos en dos niñas con manifestaciones óseas de 4 y 2 años de evolución, respectivamente, sin citopenia ni visceromegalia clínicamente evidentes. En el otro paciente con baja actividad la medición en leucocitos fue normal. Los casos detectados muestran la efectividad de un programa educacional de difusión y la utilidad de un algoritmo de detección precoz basado en síntomas óseos que facilitaría el diagnóstico de EG.

Upregulation of ASIC1a channels in an in vitro model of Fabry disease.

Neuropathic pain is one of the key features of the classical phenotype of Fabry disease (FD). Acid sensing ion channels (ASICs) are H+-gated cation channels, which belong to the epithelial sodium channel/DeGenerin superfamily, sensitive to the diuretic drug Amiloride. Molecular cloning has identified several distinct ASIC subunits. In particular the ASIC1a subunit has been associated to pain and its upregulation has been documented in animal models of pain. We analyzed the expression of ASIC1a channels in cellular models that mimic the accumulation of glycosphingolipids in FD (FD-GLs) like Gb3, and LysoGb3. We used mouse primary neurons from brain cortex and hippocampus -supraspinal structures that accumulate FD-GLs-, as well as HEK293 cells. Incubation with Gb3, lysoGb3 and the inhibitor (1-deoxy-galactonojirymicin, DJG) of the enzyme α-galactosidase A (Gla) lead to the upregulation of ASIC1a channels. In addition, activation of ASIC1a results in the activation of the MAPK ERK pathway, a signaling pathway associated with pain. Moreover, accumulation of glycosphingolipids results in activation of ERK, an effect that was prevented by blocking ASIC1a channels with the specific blocker Psalmotoxin. Our results suggest that FD-GLs accumulation and triggering of the ERK pathway via ASIC channels might be involved in the mechanism responsible for pain in FD, thus providing a new therapeutic target for pain relief treatment.