A Human Stem Cell Model of Fabry Disease Implicates LIMP-2 Accumulation in Cardiomyocyte Pathology

GLA deficiency causes cardiac hypertrophy via enhanced autophagy

Fabry disease is a monogenic disease characterized by a deficiency or loss of α-galactosidase A (GLA). Cardiomyopathy is the leading cause of death in Fabry patients; however, a lack of understanding of the pathological mechanism impedes the development of effective therapies. Here, we used a Gla knockout (KO) mouse model and investigated its impact on cardiomyopathy. We found that globotriaosylceramide (Gb3) increased the uptake and accumulation of fatty acids in KO hearts by increasing the expression levels of CD36 and ACC2. The augmented fatty acid metabolism further increased autophagy activity, leading to age-related late-onset cardiac hypertrophy. Additionally, increased autophagy facilitates disturbances in fatty acid metabolism. The inhibition of autophagy by supplementation with 3-methyladenine (3-MA) or the overexpression of GLA by the cardiomyocyte-specific adeno-associated virus for 2 months could rebalance abnormal fatty acid metabolism and ameliorate cardiac hypertrophy and dysfunction in KO hearts, suggesting a central role of autophagy in GLA deficiency-related cardiomyopathy.

Inhibition of ceramide synthesis improves the outcome of ischemia/reperfusion injury in cardiomyocytes derived from human induced pluripotent stem cell

BACKGROUND

Ceramides are bioactive sphingolipids that have physiological effects on inflammation, apoptosis, and mitochondrial dysfunction. They may play a critical role in the harm of ischemia/reperfusion (IR). Ceramides and IR injury are not well-studied, and there is a lack of human data.

METHODS AND RESULTS

Current studies aimed to investigate the role of ceramide buildup in cardiomyocytes (CMs) death using CMs derived from human induced pluripotent stem cell (hiPSC) as a model for simulating IR injury in vitro. In our model, serum- and glucose-free media was used to expose hiPSC-derived CMs to hypoxia (3% O2) for 6 h (hrs), followed by reoxygenation (20% O2) for 16 h. In contrast to normoxia (control) or hypoxia (ischemia), our data showed that following IR, there was an increase in the formation of mitochondrial superoxide and the mRNA levels of genes regulating ceramide synthesis, such as CerS2 and CerS4 in CMs. Further, there was a considerable rise in the levels of total ceramide, long-chain (C16:0, C18:0, and C18:1), and very long-chain (C22:0 and C24:1) ceramide species in CMs following reperfusion in comparison to control or ischemic CMs. Interestingly, compared to CMs exposed to IR without inhibitor, our data showed that inhibition of ceramide formation with fumonisin B1 (FB1) significantly lowered ceramide levels, reduced apoptosis, improved mitochondrial function, and enhanced survival of CMs exposed to IR. Furthermore, we used a transgenic mouse model, in which the CerS2 gene was overexpressed in the CMs of α-MHC-CerS2 mice, to validate the basic idea that ceramide contributes to heart disease in vivo. Our results showed that the heart tissues of α-MHC-CerS2 mice had significant levels of long-chain and very long-chain ceramides, which causes increased apoptosis, proinflammatory cytokines, interstitial inflammatory cell infiltration, and collagen deposition.

CONCLUSIONS

Results from both in vitro and in vivo experiments show that ceramides have a significant role in either mediating or inducing damage to CMs. Additionally, in vitro findings show that ceramide reduction improves the outcome of IR injury by lowering intracellular Ca2+ [Ca2+]i concentration and improves mitochondrial function changes during IR.

Adipocyte-derived glutathione promotes obesity-related breast cancer by regulating the SCARB2-ARF1-mTORC1 complex

Obesity is a major risk factor for poor breast cancer outcomes, but the impact of obesity-induced tumor microenvironment (TME) metabolites on breast cancer growth and metastasis remains unclear. Here, we performed TME metabolomic analysis in high-fat diet (HFD) mouse models and found that glutathione (GSH) levels were elevated in the TME of obesity-accelerated breast cancer. The deletion of glutamate-cysteine ligase catalytic subunit (GCLC), the rate-limiting enzyme in GSH biosynthesis, in adipocytes but not tumor cells reduced obesity-related tumor progression. Mechanistically, we identified that GSH entered tumor cells and directly bound to lysosomal integral membrane protein-2 (scavenger receptor class B, member 2 [SCARB2]), interfering with the interaction between its N and C termini. This, in turn, recruited mTORC1 to lysosomes through ARF1, leading to the activation of mTOR signaling. Overall, we demonstrated that GSH links obesity and breast cancer progression by acting as an activator of mTOR signaling. Targeting the GSH/SCARB2/mTOR axis could benefit breast cancer patients with obesity.

Anderson-Fabry Disease: An Overview of Current Diagnosis, Arrhythmic Risk Stratification, and Therapeutic Strategies

Anderson-Fabry disease (AFD) is a rare X-linked lysosomal storage disorder characterized by the accumulation of globotriaosylceramide, leading to multi-organ involvement and significant morbidity. Cardiovascular manifestations, particularly arrhythmias, are common and pose a considerable risk to affected individuals. This overview examines current approaches to arrhythmic risk stratification in AFD, focusing on the identification, assessment, and management of cardiac arrhythmias associated with the disease. We explore advancements in diagnostic techniques, including echocardiography, cardiac MRI, and ambulatory ECG monitoring, to enhance the detection of arrhythmogenic substrate. Furthermore, we discuss the role of genetic and biochemical markers in predicting arrhythmic risk and the implications for personalized treatment strategies. Current therapeutic interventions, including enzyme replacement therapy and antiarrhythmic medications, are reviewed in the context of their efficacy and limitations. Finally, we highlight ongoing research and future directions with the aim of improving arrhythmic risk assessment and management in AFD. This overview underscores the need for a multidisciplinary approach to optimize care and outcomes for patients with AFD.

Ventricular arrhythmias and primary prevention of sudden cardiac death in Anderson-Fabry disease

The Anderson-Fabry disease (AFD) is a X-linked lysosomal storage disorder due to the deficiency in the α-galactosidase A enzyme. Cardiovascular mortality is a major cause of death in patients with AFD and sudden cardiac death (SCD) is one of the main causes of death. The storage of glycosphingolipid along with ionic channel impairment, inflammation and fibrosis are involved in the arrhythmogenesis. Some risk factors have been associated with ventricular tachycardia (VT)/ventricular fibrillation (VF) and SCD. Left ventricular hypertrophy (LVH), cardiac fibrosis, non-sustained VTs seem to be the most important. Older age and male gender might be associated with higher risk of ventricular arrhythmias and SCD. Currently, the implantable cardioverter-defibrillator (ICD) is recommended in patients with AFD who have survived a cardiac arrest secondary to VT/VF or who experienced sustained VT causing syncope or hemodynamic compromise, and have a life expectancy >1 year. ICD implantation is also recommended in patients considered to be at high risk (e.g., patients with severe LVH or fibrosis). The present review sought to summarize the risk of ventricular arrythmias in AFD, the indications for ICD, focusing on pathophysiology and analyzing the role of possible predictors of arrhythmias in preventing SCD, especially as primary prevention.

Human in vitro models for Fabry disease: new paths for unravelling disease mechanisms and therapies

Fabry disease is a multi-organ disease, caused by mutations in the GLA gene and leading to a progressive accumulation of glycosphingolipids due to enzymatic absence or malfunction of the encoded alpha-galactosidase A. Since pathomechanisms are not yet fully understood and available treatments are not efficient for all mutation types and tissues, further research is highly needed. This research involves many different model types, with significant effort towards the establishment of an in vivo model. However, these models did not replicate the variety of symptoms observed in patients. As an alternative strategy, patient-derived somatic cells as well as patient-independent cell lines were used to model specific aspects of the disease in vitro. Fabry disease patients present different phenotypes according to the mutation and the level of residual enzyme activity, pointing to the necessity of personalized disease modeling. With the advent of induced pluripotent stem cells, the derivation of a multitude of disease-affected cell types became possible, even in a patient-specific and mutation-specific manner. Only recently, three-dimensional Fabry disease models were established that even more closely resemble the native tissue of investigated organs and will bring research closer to the in vivo situation. This review provides an overview of human in vitro models and their achievements in unravelling the Fabry disease pathomechanism as well as in elucidating current and future treatment strategies.

Glycosphingolipids in Cardiovascular Disease: Insights from Molecular Mechanisms and Heart Failure Models

This review explores the crucial role of glycosphingolipids (GSLs) in the context of cardiovascular diseases (CVDs), focusing on their biosynthesis, metabolic pathways, and implications for clinical outcomes. GSLs are pivotal in regulating a myriad of cellular functions that are essential for heart health and disease progression. Highlighting findings from both human cohorts and animal models, this review emphasizes the potential of GSLs as biomarkers and therapeutic targets. We advocate for more detailed mechanistic studies to deepen our understanding of GSL functions in cardiovascular health, which could lead to innovative strategies for diagnosis, treatment, and personalized medicine in cardiovascular care.

Clinical characteristics and induced pluripotent stem cells (iPSCs) disease model of Fabry disease caused by a novel GLA mutation

BACKGROUND

Fabry disease (FD) is a rare X-linked inherited disease caused by mutations in the galactosidase alpha (GLA) gene. We established a cohort of FD patients and performed whole-exome sequencing to identify some novel mutations.

AIM

The aim of this study is to investigate the etiology of the novel mutation (c.72G > A, p. Trp24*)in the GLA gene in affected patients by using induced pluripotent stem cells (iPSCs) as a valuable tool.

METHODS

We explored the clinical implications of this proband and examined the deleteriousness and conservation of the mutation site through bioinformatics analysis. Simultaneously, we collected the peripheral blood mononuclear cells of the affected patient, then reprogrammed them into iPSCs and assessed their enzymatic activity to confirm the function of lysosomal enzyme α-galactosidase A (α-Gal A).

RESULTS

Clinical examination of the patient demonstrated a classical FD, such as neuropathic pain, gastrointestinal disorders, deficiency of α-Gal A activity and accumulation of Lyso-Gb-3. The novel mutation located on the N-terminal region, leading to a truncation of the protein and remaining only 24 amino acids. The α-Gal A activity of the patient-specific iPSC (iPS-FD) was significantly lower (60%) than that of normal iPSCs derived from healthy donors (iPS-B1).

CONCLUSION

This work not only elucidated the etiology of novel mutations in affected patients but also highlighted the utility of iPSCs as a valuable tool for clarifying the molecular mechanisms and providing new insights into the therapy of FD.

Arrhythmogenesis in Fabry Disease

PURPOSE OF REVIEW

Fabry Disease (FD) is a rare lysosomal storage disorder characterised by multiorgan accumulation of glycosphingolipid due to deficiency in the enzyme α-galactosidase A. Cardiac sphingolipid accumulation triggers various types of arrhythmias, predominantly ventricular arrhythmia, bradyarrhythmia, and atrial fibrillation. Arrhythmia is likely the primary contributor to FD mortality with sudden cardiac death, the most frequent cardiac mode of death. Traditionally FD was seen as a storage cardiomyopathy triggering left ventricular hypertrophy, diastolic dysfunction, and ultimately, systolic dysfunction in advanced disease. The purpose of this review is to outline the current evidence exploring novel mechanisms underlying the arrhythmia substrate.

RECENT FINDINGS

There is growing evidence that FD cardiomyopathy is a primary arrhythmic disease with each stage of cardiomyopathy (accumulation, hypertrophy, inflammation, and fibrosis) contributing to the arrhythmia substrate via various intracellular, extracellular, and environmental mechanisms. It is therefore important to understand how these mechanisms contribute to an individual's risk of arrhythmia in FD. In this review, we outline the epidemiology of arrhythmia, pathophysiology of arrhythmogenesis, risk stratification, and cardiac therapy in FD. We explore how advances in conventional cardiac investigations performed in FD patients including 12-lead electrocardiography, transthoracic echocardiography, and cardiac magnetic resonance imaging have enabled early detection of pro-arrhythmic substrate. This has allowed for appropriate risk stratification of FD patients. This paves the way for future work exploring the development of therapeutic initiatives and risk prediction models to reduce the burden of arrhythmia.

Anderson-Fabry disease management: role of the cardiologist

Anderson-Fabry disease (AFD) is a lysosomal storage disorder characterized by glycolipid accumulation in cardiac cells, associated with a peculiar form of hypertrophic cardiomyopathy (HCM). Up to 1% of patients with a diagnosis of HCM indeed have AFD. With the availability of targeted therapies for sarcomeric HCM and its genocopies, a timely differential diagnosis is essential. Specifically, the therapeutic landscape for AFD is rapidly evolving and offers increasingly effective, disease-modifying treatment options. However, diagnosing AFD may be difficult, particularly in the non-classic phenotype with prominent or isolated cardiac involvement and no systemic red flags. For many AFD patients, the clinical journey from initial clinical manifestations to diagnosis and appropriate treatment remains challenging, due to late recognition or utter neglect. Consequently, late initiation of treatment results in an exacerbation of cardiac involvement, representing the main cause of morbidity and mortality, irrespective of gender. Optimal management of AFD patients requires a dedicated multidisciplinary team, in which the cardiologist plays a decisive role, ranging from the differential diagnosis to the prevention of complications and the evaluation of timing for disease-specific therapies. The present review aims to redefine the role of cardiologists across the main decision nodes in contemporary AFD clinical care and drug discovery.

Small fibre neuropathy in Fabry disease: a human-derived neuronal in vitro disease model and pilot data

Acral burning pain triggered by fever, thermal hyposensitivity and skin denervation are hallmarks of small fibre neuropathy in Fabry disease, a life-threatening X-linked lysosomal storage disorder. Variants in the gene encoding alpha-galactosidase A may lead to impaired enzyme activity with cellular accumulation of globotriaosylceramide. To study the underlying pathomechanism of Fabry-associated small fibre neuropathy, we generated a neuronal in vitro disease model using patient-derived induced pluripotent stem cells from three Fabry patients and one healthy control. We further generated an isogenic control line via gene editing. We subjected induced pluripotent stem cells to targeted peripheral neuronal differentiation and observed intra-lysosomal globotriaosylceramide accumulations in somas and neurites of Fabry sensory neurons using super-resolution microscopy. At functional level, patch-clamp analysis revealed a hyperpolarizing shift of voltage-gated sodium channel steady-state inactivation kinetics in isogenic control neurons compared with healthy control neurons (P < 0.001). Moreover, we demonstrate a drastic increase in Fabry sensory neuron calcium levels at 39°C mimicking clinical fever (P < 0.001). This pathophysiological phenotype was accompanied by thinning of neurite calibres in sensory neurons differentiated from induced pluripotent stem cells derived from Fabry patients compared with healthy control cells (P < 0.001). Linear-nonlinear cascade models fit to spiking responses revealed that Fabry cell lines exhibit altered single neuron encoding properties relative to control. We further observed mitochondrial aggregation at sphingolipid accumulations within Fabry sensory neurites utilizing a click chemistry approach together with mitochondrial dysmorphism compared with healthy control cells. We pioneer pilot insights into the cellular mechanisms contributing to pain, thermal hyposensitivity and denervation in Fabry small fibre neuropathy and pave the way for further mechanistic in vitro studies in Fabry disease and the development of novel treatment approaches.

Fabry Disease: Cardiac Implications and Molecular Mechanisms

PURPOSE OF REVIEW

This review explores the interplay among metabolic dysfunction, oxidative stress, inflammation, and fibrosis in Fabry disease, focusing on their potential implications for cardiac involvement. We aim to discuss the biochemical processes that operate in parallel to sphingolipid accumulation and contribute to disease pathogenesis, emphasizing the importance of a comprehensive understanding of these processes.

RECENT FINDINGS

Beyond sphingolipid accumulation, emerging studies have revealed that mitochondrial dysfunction, oxidative stress, and chronic inflammation could be significant contributors to Fabry disease and cardiac involvement. These factors promote cardiac remodeling and fibrosis and may predispose Fabry patients to conduction disturbances, ventricular arrhythmias, and heart failure. While current treatments, such as enzyme replacement therapy and pharmacological chaperones, address disease progression and symptoms, their effectiveness is limited. Our review uncovers the potential relationships among metabolic disturbances, oxidative stress, inflammation, and fibrosis in Fabry disease-related cardiac complications. Current findings suggest that beyond sphingolipid accumulation, other mechanisms may significantly contribute to disease pathogenesis. This prompts the exploration of innovative therapeutic strategies and underscores the importance of a holistic approach to understanding and managing Fabry disease.

How can we use stem cell-derived cardiomyocytes to understand the involvement of energetic metabolism in alterations of cardiac function?

Mutations in the mitochondrial-DNA or mitochondria related nuclear-encoded-DNA lead to various multisystemic disorders collectively termed mitochondrial diseases. One in three cases of mitochondrial disease affects the heart muscle, which is called mitochondrial cardiomyopathy (MCM) and is associated with hypertrophic, dilated, and noncompact cardiomyopathy. The heart is an organ with high energy demand, and mitochondria occupy 30%-40% of its cardiomyocyte-cell volume. Mitochondrial dysfunction leads to energy depletion and has detrimental effects on cardiac performance. However, disease development and progression in the context of mitochondrial and nuclear DNA mutations, remains incompletely understood. The system of induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CM) is an excellent platform to study MCM since the unique genetic identity to their donors enables a robust recapitulation of the predicted phenotypes in a dish on a patient-specific level. Here, we focus on recent insights into MCM studied by patient-specific iPSC-CM and further discuss research gaps and advances in metabolic maturation of iPSC-CM, which is crucial for the study of mitochondrial dysfunction and to develop novel therapeutic strategies.

Electrocardiogram analysis in Anderson-Fabry disease: a valuable tool for progressive phenotypic expression tracking

Background

Electrocardiogram (ECG) has proven to be useful for early detection of cardiac involvement in Anderson-Fabry disease (AFD); however, little evidence is available on the association between ECG alterations and the progression of the disease.

Aim and Methods

To perform a cross sectional comparison of ECG abnormalities throughout different left ventricular hypertrophy (LVH) severity subgroups, providing ECG patterns specific of the progressive AFD stages. 189 AFD patients from a multicenter cohort underwent comprehensive ECG analysis, echocardiography, and clinical evaluation.

Results

The study cohort (39% males, median age 47 years, 68% classical AFD) was divided into 4 groups according to different degree of left ventricular (LV) thickness: group A ≤ 9 mm (n = 52, 28%); group B 10-14 mm (n = 76, 40%); group C 15-19 mm (n = 46, 24%); group D ≥ 20 mm (n = 15, 8%). The most frequent conduction delay was right bundle branch block (RBBB), incomplete in groups B and C (20%,22%) and complete RBBB in group D (54%, p < 0.001); none of the patients had left bundle branch block (LBBB). Left anterior fascicular block, LVH criteria, negative T waves, ST depression were more common in the advanced stages of the disease (p < 0.001). Summarizing our results, we suggested ECG patterns representative of the different AFD stages as assessed by the increases in LV thickness over time (Central Figure). Patients from group A showed mostly a normal ECG (77%) or minor anomalies like LVH criteria (8%) and delta wave/slurred QR onset + borderline PR (8%). Differently, patients from groups B and C exhibited more heterogeneous ECG patterns: LVH (17%; 7% respectively); LVH + LV strain (9%; 17%); incomplete RBBB + repolarization abnormalities (8%; 9%), more frequently associated with LVH criteria in group C than B (8%; 15%). Finally, patients from group D showed very peculiar ECG patterns, represented by complete RBBB + LVH and repolarization abnormalities (40%), sometimes associated with QRS fragmentation (13%).

Conclusions

ECG is a sensitive tool for early identification and long-term monitoring of cardiac involvement in patients with AFD, providing "instantaneous pictures" along the natural history of AFD. Whether ECG changes may be associated with clinical events remains to be determined.

Anderson-Fabry disease cardiomyopathy: an update on epidemiology, diagnostic approach, management and monitoring strategies

Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder caused by deficient activity of the enzyme alpha-galactosidase. While AFD is recognized as a progressive multi-system disorder, infiltrative cardiomyopathy causing a number of cardiovascular manifestations is recognized as an important complication of this disease. AFD affects both men and women, although the clinical presentation typically varies by sex, with men presenting at a younger age with more neurologic and renal phenotype and women developing a later onset variant with more cardiovascular manifestations. AFD is an important cause of increased myocardial wall thickness, and advances in imaging, in particular cardiac magnetic resonance imaging and T1 mapping techniques, have improved the ability to identify this disease non-invasively. Diagnosis is confirmed by the presence of low alpha-galactosidase activity and identification of a mutation in the GLA gene. Enzyme replacement therapy remains the mainstay of disease modifying therapy, with two formulations currently approved. In addition, newer treatments such as oral chaperone therapy are now available for select patients, with a number of other investigational therapies in development. The availability of these therapies has significantly improved outcomes for AFD patients. Improved survival and the availability of multiple agents has presented new clinical dilemmas regarding disease monitoring and surveillance using clinical, imaging and laboratory biomarkers, in addition to improved approaches to managing cardiovascular risk factors and AFD complications. This review will provide an update on clinical recognition and diagnostic approaches including differentiation from other causes of increased ventricular wall thickness, in addition to modern strategies for management and follow-up.

Functional genomics in stroke: current and future applications of iPSCs and gene editing to dissect the function of risk variants

Stroke is an important disease with unmet clinical need. To uncover novel paths for treatment, it is of critical importance to develop relevant laboratory models that may help to shed light on the pathophysiological mechanisms of stroke. Induced pluripotent stem cells (iPSCs) technology has enormous potential to advance our knowledge into stroke by creating novel human models for research and therapeutic testing. iPSCs models generated from patients with specific stroke types and specific genetic predisposition in combination with other state of art technologies including genome editing, multi-omics, 3D system, libraries screening, offer the opportunity to investigate disease-related pathways and identify potential novel therapeutic targets that can then be tested in these models. Thus, iPSCs offer an unprecedented opportunity to make rapid progress in the field of stroke and vascular dementia research leading to clinical translation. This review paper summarizes some of the key areas in which patient-derived iPSCs technology has been applied to disease modelling and discusses the ongoing challenges and the future directions for the application of this technology in the field of stroke research.

Fabry Disease and Central Nervous System Involvement: From Big to Small, from Brain to Synapse

Fabry disease (FD) is an X-linked lysosomal storage disorder (LSD) secondary to mutations in the GLA gene that causes dysfunctional activity of lysosomal hydrolase α-galactosidase A and results in the accumulation of globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3). The endothelial accumulation of these substrates results in injury to multiple organs, mainly the kidney, heart, brain and peripheral nervous system. The literature on FD and central nervous system involvement is scarce when focusing on alterations beyond cerebrovascular disease and is nearly absent in regard to synaptic dysfunction. In spite of that, reports have provided evidence for the CNS’ clinical implications in FD, including Parkinson’s disease, neuropsychiatric disorders and executive dysfunction. We aim to review these topics based on the current available scientific literature.

Biochemical Mechanisms beyond Glycosphingolipid Accumulation in Fabry Disease: Might They Provide Additional Therapeutic Treatments?

Fabry disease is a rare X-linked disease characterized by deficient expression and activity of alpha-galactosidase A (α-GalA) with consequent lysosomal accumulation of glycosphingolipid in various organs. Currently, enzyme replacement therapy is the cornerstone of the treatment of all Fabry patients, although in the long-term it fails to completely halt the disease's progression. This suggests on one hand that the adverse outcomes cannot be justified only by the lysosomal accumulation of glycosphingolipids and on the other that additional therapies targeted at specific secondary mechanisms might contribute to halt the progression of cardiac, cerebrovascular, and renal disease that occur in Fabry patients. Several studies reported how secondary biochemical processes beyond Gb3 and lyso-Gb3 accumulation-such as oxidative stress, compromised energy metabolism, altered membrane lipid, disturbed cellular trafficking, and impaired autophagy-might exacerbate Fabry disease adverse outcomes. This review aims to summarize the current knowledge of these pathogenetic intracellular mechanisms in Fabry disease, which might suggest novel additional strategies for its treatment.

Deep next-generation proteomics and network analysis reveal systemic and tissue-specific patterns in Fabry disease

Fabry disease (FD) is an X-linked lysosomal rare disease due to a deficiency of α-galactosidase A activity. The accumulation of glycosphingolipids mainly affects the kidney, heart, and central nervous system, considerably reducing life expectancy. Although the accumulation of undegraded substrate is considered the primary cause of FD, it is established that secondary dysfunctions at the cellular, tissue, and organ levels ultimately give rise to the clinical phenotype. To parse this biological complexity, a large-scale deep plasma targeted proteomic profiling has been performed. We analyzed the plasma protein profiles of FD deeply phenotyped patients (n = 55) compared to controls (n = 30) using next-generation plasma proteomics including 1463 proteins. Systems biology and machine learning approaches have been used. The analysis enabled the identification of proteomic profiles that unambiguously separated FD patients from controls (615 differentially expressed proteins, 476 upregulated, and 139 downregulated) and 365 proteins are newly reported. We observed functional remodeling of several processes, such as cytokine-mediated pathways, extracellular matrix, and vacuolar/lysosomal proteome. Using network strategies, we probed patient-specific tissue metabolic remodeling and described a robust predictive consensus protein signature including 17 proteins CD200, SPINT1, CD34, FGFR2, GRN, ERBB4, AXL, ADAM15, PTPRM, IL13RA1, NBL1, NOTCH1, VASN, ROR1, AMBP, CCN3, and HAVCR2. Our findings highlight the pro-inflammatory cytokines' involvement in FD pathogenesis along with extracellular matrix remodeling. The study shows a tissue-wide metabolic remodeling connection to plasma proteomics in FD. These results will facilitate further studies to understand the molecular mechanisms in FD to pave the way for better diagnostics and therapeutics.

Genome Editing Tools for Lysosomal Storage Disorders

Genome editing has multiple applications in the biomedical field. They can be used to modify genomes at specific locations, being able to either delete, reduce, or even enhance gene transcription and protein expression. Here, we summarize applications of genome editing used in the field of lysosomal disorders. We focus on the development of cell lines for study of disease pathogenesis, drug discovery, and pathogenicity of specific variants. Furthermore, we highlight the main studies that use gene editing as a gene therapy platform for these disorders, both in preclinical and clinical studies. We conclude that gene editing has been able to change quickly the scenario of these disorders, allowing the development of new therapies and improving the knowledge on disease pathogenesis. Should they confirm their hype, the first gene editing-based products for lysosomal disorders could be available in the next years.

Characterization of cellular phenotypes in neurons derived from induced pluripotent stem cells of male patients with Fabry disease

Fabry disease (FD) is an X-linked inherited lysosomal metabolism disorder in which globotriaosylceramide (Gb3) accumulates in various organs resulting from a deficiency in alpha-galactosidase A. The clinical features of FD include progressive impairments of the renal, cardiac, and peripheral nervous systems. In addition, patients with FD often develop neuropsychiatric symptoms, such as depression and dementia, which are believed to be induced by the cellular injury of cerebrovascular and partially neuronal cells due to Gb3 accumulation. Although the analysis of autopsy brain tissue from patients with FD showed no accumulation of Gb3, abnormal deposits of Gb3 were found in the neurons of several brain areas, including the hippocampus. Therefore, in this study, we generated induced pluripotent stem cells (iPSCs) from patients with FD and differentiated them into neuronal cells to investigate pathological and biological changes in the neurons of FD. Neural stem cells (NSCs) and neurons were successfully differentiated from the iPSCs we generated; however, cellular damage and morphological changes were not found in these cells. Immunostaining revealed no Gb3 accumulation in NSCs and neurons. Transmission electron microscopy did not reveal any zebra body-like structures or inclusion bodies, which are characteristic of FD. These results indicated that neuronal cells derived from FD-iPSCs exhibited normal morphology and no Gb3 accumulation. It is likely that more in vivo environment-like cultures are needed for iPSC-derived neurons to reproduce disease-specific features.

Generation of GLA-knockout human embryonic stem cell lines to model peripheral neuropathy in Fabry disease

Fabry disease is an X-linked glycolipid storage disorder caused by mutations in the GLA gene which result in a deficiency in the lysosomal enzyme alpha galactosidase A (AGA). As a result, the glycolipid substrate Gb3 accumulates in critical tissues and organs producing a progressive debilitating disease. In Fabry disease up to 80% of patients experience life-long neuropathic pain that is difficult to treat and greatly affects their quality of life. The molecular mechanisms by which deficiency of AGA leads to neuropathic pain are not well understood, due in part to a lack of in vitro models that can be used to study the underlying pathology at the cellular level. Using CRISPR-Cas9 gene editing, we generated two clones with mutations in the GLA gene from a human embryonic stem cell line. Our clonal cell lines maintained normal stem cell morphology and markers for pluripotency, and showed the phenotypic characteristics of Fabry disease including absent AGA activity and intracellular accumulation of Gb3. Mutations in the predicted locations in exon 1 of the GLA gene were confirmed. Using established techniques for dual-SMAD inhibition/WNT activation, we were able to show that our AGA-deficient clones, as well as wild-type controls, could be differentiated to peripheral-type sensory neurons that express pain receptors. This genetically and physiologically relevant human model system offers a new and promising tool for investigating the cellular mechanisms of peripheral neuropathy in Fabry disease and may assist in the development of new therapeutic strategies to help lessen the burden of this disease.

Models to study basic and applied aspects of lysosomal storage disorders

The lack of available treatments and fatal outcome in most lysosomal storage disorders (LSDs) have spurred research on pathological mechanisms and novel therapies in recent years. In this effort, experimental methodology in cellular and animal models have been developed, with aims to address major challenges in many LSDs such as patient-to-patient variability and brain condition. These techniques and models have advanced knowledge not only of LSDs but also for other lysosomal disorders and have provided fundamental insights into the biological roles of lysosomes. They can also serve to assess the efficacy of classical therapies and modern drug delivery systems. Here, we summarize the techniques and models used in LSD research, which include both established and recently developed in vitro methods, with general utility or specifically addressing lysosomal features. We also review animal models of LSDs together with cutting-edge technology that may reduce the need for animals in the study of these devastating diseases.

Fabry disease: Mechanism and therapeutics strategies

Fabry disease is a monogenic disease characterized by a deficiency or loss of the α-galactosidase A (GLA). The resulting impairment in lysosomal GLA enzymatic activity leads to the pathogenic accumulation of enzymatic substrate and, consequently, the progressive appearance of clinical symptoms in target organs, including the heart, kidney, and brain. However, the mechanisms involved in Fabry disease-mediated organ damage are largely ambiguous and poorly understood, which hinders the development of therapeutic strategies for the treatment of this disorder. Although currently available clinical approaches have shown some efficiency in the treatment of Fabry disease, they all exhibit limitations that need to be overcome. In this review, we first introduce current mechanistic knowledge of Fabry disease and discuss potential therapeutic strategies for its treatment. We then systemically summarize and discuss advances in research on therapeutic approaches, including enzyme replacement therapy (ERT), gene therapy, and chaperone therapy, as well as strategies targeting subcellular compartments, such as lysosomes, the endoplasmic reticulum, and the nucleus. Finally, the future development of potential therapeutic strategies is discussed based on the results of mechanistic studies and the limitations associated with these therapeutic approaches.

An Overview of Molecular Mechanisms in Fabry Disease

Fabry disease (FD) (OMIM #301500) is a rare genetic lysosomal storage disorder (LSD). LSDs are characterized by inappropriate lipid accumulation in lysosomes due to specific enzyme deficiencies. In FD, the defective enzyme is α-galactosidase A (α-Gal A), which is due to a mutation in the GLA gene on the X chromosome. The enzyme deficiency leads to a continuous deposition of neutral glycosphingolipids (globotriaosylceramide) in the lysosomes of numerous tissues and organs, including endothelial cells, smooth muscle cells, corneal epithelial cells, renal glomeruli and tubules, cardiac muscle and ganglion cells of the nervous system. This condition leads to progressive organ failure and premature death. The increasing understanding of FD, and LSD in general, has led in recent years to the introduction of enzyme replacement therapy (ERT), which aims to slow, if not halt, the progression of the metabolic disorder. In this review, we provide an overview of the main features of FD, focusing on its molecular mechanism and the role of biomarkers.

An expert consensus on practical clinical recommendations and guidance for patients with classic Fabry disease

Fabry disease is an X-linked inherited lysosomal disorder that causes accumulation of glycosphingolipids in body fluids and tissues, leading to progressive organ damage and reduced life expectancy. It can affect both males and females and can be classified into classic or later-onset phenotypes. In classic Fabry disease, α-galactosidase A (α-Gal A) activity is absent or severely reduced and disease manifestations have an early onset that can affect multiple organs. In contrast, in later-onset Fabry disease, patients have residual α-Gal A activity and clinical features are primarily confined to the heart. Individualized therapeutic goals in Fabry disease are required due to varying phenotypes and patient characteristics, and the wide spectrum of disease severity. An international group of expert physicians convened to discuss and develop practical clinical recommendations for disease- and organ-specific therapeutic goals in Fabry disease, based on expert consensus and evidence identified through a structured literature review. Biomarkers reflecting involvement of various organs in adult patients with classic Fabry disease are discussed and consensus recommendations for disease- and organ-specific therapeutic goals are provided. These consensus recommendations should support the establishment of individualized approaches to the management of patients with classic Fabry disease by considering identification, diagnosis, and initiation of disease-specific therapies before significant organ involvement, as well as routine monitoring, to reduce morbidity, optimize patient care, and improve patient health-related quality of life.

The Heart in Fabry Disease: Mechanisms Beyond Storage and Forthcoming Therapies

In patients with Fabry disease (FD), cardiovascular involvement is the main cause of death and reduction of quality of life. Left ventricular hypertrophy mimicking hypertrophic cardiomyopathy is the main feature of FD cardiac involvement although glycolipid storage occurs in all cardiac cellular types. Accumulation of lysosomal globotriasylceramide represents the main mechanism of cardiac damage in early stages, but secondary pathways of cellular and tissue damage, triggered by lysosomal storage, and including altered energy production, inflammation and cell death, contribute to cardiac damage and disease progression. These mechanisms appear prominent in more advanced stages, hampering and reducing the efficacy of FD-specific treatments. Therefore, additional cardiovascular therapies are important to manage cardiovascular symptoms and reduce cardiovascular events. Although new therapies targeting lysosomal storage are in development, a better definition and comprehension of the complex pathophysiology of cardiac damage in FD, may lead to identify new therapeutic targets beyond storage and new therapeutic strategies.

Fabry disease with acute myocardial infarction, left ventricular thrombosis, and pericardial effusion: A case report

RATIONALE

Fabry disease (FD) is a rare, X-linked lysosomal deposition disease characterized by multi-system symptoms. The accumulation of globotriaosylceramide in various organs, such as the kidneys and heart, as well as the nervous system, has been speculated to be the mechanism involved in tissue damage, including vascular impairment with thrombotic events.

PATIENT CONCERNS

Here, we describe a 72-year-old male patient diagnosed with FD, who first presented with acute myocardial infarction, left ventricular thrombosis, and pericardial effusion, accompanied by cardiac hypertrophy.

DIAGNOSES

A physical examination showed that he was hemodynamically stable and an electrocardiogram showed ventricular tachycardia (Fig. 1A). The single obvious abnormality was an ST segment depression with a preterminal negative T wave in leads I and aVL (Fig. 1B). Coronary angiography revealed regular findings (Fig. 2). Echocardiogram conducted at our hospital revealed hypertrophy, ejection fraction 40%, pericardial effusion (Fig. 3). Speckle tracking two-dimensional echocardiography strain analysis technology confirmed left ventricular thrombosis, and also revealed decreased movement of the inferior and posterior walls, the basal segment of the posterior wall was locally fibrotic (Fig. 4A and B). Further, myocardial contrast echocardiography confirmed left ventricular thrombosis (Fig. 4C). Cardiovascular magnetic resonance imaging indicated biventricular uneven hypertrophy, which was considered metabolic cardiomyopathy, with diffuse fibrosis of biventricular walls, apical thrombosis, and ischemic cardiomyopathy in the basal segment of the left ventricular lateral wall and left ventricular anterior wall (Fig. 5). Serum alpha-galactosidase concentration was 0.7 nmol/h/mgPr (normal range, 29.0-64.4 nmol/h/mgPr). Subsequent genetic testing revealed that he was hemizygous for a previously reported missense mutation (c.902G>A) inexon 6 of the GLA gene,[1] which induce p.R301Q (p.Arg301Gln), confirming a diagnosis of FD (Fig. 6).

INTERVENTIONS

Orally administered drugs included rivaroxaban, sacubitril valsartan, beta blockers, dapagliflozin, and mineralocorticoid receptor antagonist. Cardiac resynchronization therapy with an implanted defibrillator was implemented to prevent sudden death.

OUTCOMES

At present, he is still in follow-up and there have been no adverse events.

CONCLUSION

Our case suggests that clinicians should consider the possibility of FD in patients with acute myocardial infarction and cardiomyopathy. A detailed analysis of subtle historical clues would help promote earlier diagnosis of FD.

Mass spectrometry-based proteomics in neurodegenerative lysosomal storage disorders

The major function of the lysosome is to degrade unwanted materials such as lipids, proteins, and nucleic acids; therefore, deficits of the lysosomal system can result in improper degradation and trafficking of these biomolecules. Diseases associated with lysosomal failure can be lethal and are termed lysosomal storage disorders (LSDs), which affect 1 in 5000 live births collectively. LSDs are inherited metabolic diseases caused by mutations in single lysosomal and non-lysosomal proteins and resulting in the subsequent accumulation of macromolecules within. Most LSD patients present with neurodegenerative clinical symptoms, as well as damage in other organs. The discovery of new biomarkers is necessary to understand and monitor these diseases and to track therapeutic progress. Over the past ten years, mass spectrometry (MS)-based proteomics has flourished in the biomarker studies in many diseases, including neurodegenerative, and more specifically, LSDs. In this review, biomarkers of disease pathophysiology and monitoring of LSDs revealed by MS-based proteomics are discussed, including examples from Niemann-Pick disease type C, Fabry disease, neuronal ceroid-lipofuscinoses, mucopolysaccharidosis, Krabbe disease, mucolipidosis, and Gaucher disease.

Delineating the neuropathology of lysosomal storage diseases using patient-derived induced pluripotent stem cells

Lysosomal storage diseases (LSD) are inherited metabolic diseases caused due to deficiency of lysosomal enzymes, essential for the normal development of the brain and other organs. Approximately two-thirds of the patients suffering from LSD exhibit neurological deficits and impose an escalating challenge to the medical and scientific field. The advent of iPSC technology has aided researchers in efficiently generating functional neuronal and non-neuronal cells through directed differentiation protocols, as well as in decoding the cellular, subcellular and molecular defects associated with LSDs using two-dimensional cultures and cerebral organoid models. This review highlights the information assembled from patient-derived iPSCs on neurodevelopmental and neuropathological defects identified in LSDs. Multiple studies have identified neural progenitor cell migration and differentiation defects, substrate accumulation, axon growth and myelination defects, impaired calcium homeostasis and altered electrophysiological properties, using patient-derived iPSCs. In addition, these studies have also uncovered defective lysosomes, mitochondria, endoplasmic reticulum, Golgi complex, autophagy and vesicle trafficking and signaling pathways, oxidative stress, neuroinflammation, blood brain barrier dysfunction, neurodegeneration, gliosis, altered transcriptomes in LSDs. The review also discusses the therapeutic applications such as drug discovery, repurposing of drugs, synergistic effects of drugs, targeted molecular therapies, gene therapy, and transplantation applications of mutation corrected lines identified using patient-derived iPSCs for different LSDs.

Inborn errors of metabolism: Lessons from iPSC models

The possibility of reprogramming human somatic cells to pluripotency has opened unprecedented opportunities for creating genuinely human experimental models of disease. Inborn errors of metabolism (IEMs) constitute a greatly heterogeneous class of diseases that appear, in principle, especially suited to be modeled by iPSC-based technology. Indeed, dozens of IEMs have already been modeled to some extent using patient-specific iPSCs. Here, we review the advantages and disadvantages of iPSC-based disease modeling in the context of IEMs, as well as particular challenges associated to this approach, together with solutions researchers have proposed to tackle them. We have structured this review around six lessons that we have learnt from those previous modeling efforts, and that we believe should be carefully considered by researchers wishing to embark in future iPSC-based models of IEMs.

Pathogenesis and Molecular Mechanisms of Anderson-Fabry Disease and Possible New Molecular Addressed Therapeutic Strategies

Anderson-Fabry disease (AFD) is a rare disease with an incidenceof approximately 1:117,000 male births. Lysosomal accumulation of globotriaosylceramide (Gb3) is the element characterizing Fabry disease due to a hereditary deficiency α-galactosidase A (GLA) enzyme. The accumulation of Gb3 causes lysosomal dysfunction that compromises cell signaling pathways. Deposition of sphingolipids occurs in the autonomic nervous system, dorsal root ganglia, kidney epithelial cells, vascular system cells, and myocardial cells, resulting in organ failure. This manuscript will review the molecular pathogenetic pathways involved in Anderson-Fabry disease and in its organ damage. Some studies reported that inhibition of mitochondrial function and energy metabolism plays a significant role in AFD cardiomyopathy and in kidney disease of AFD patients. Furthermore, mitochondrial dysfunction has been reported as linked to the dysregulation of the autophagy-lysosomal pathway which inhibits the mechanistic target of rapamycin kinase (mTOR) mediated control of mitochondrial metabolism in AFD cells. Cerebrovascular complications due to AFD are caused by cerebral micro vessel stenosis. These are caused by wall thickening resulting from the intramural accumulation of glycolipids, luminal occlusion or thrombosis. Other pathogenetic mechanisms involved in organ damage linked to Gb3 accumulation are endocytosis and lysosomal degradation of endothelial calcium-activated intermediate-conductance potassium ion channel 3.1 (KCa3.1) via a clathrin-dependent process. This process represents a crucial event in endothelial dysfunction. Several studies have identified the deacylated form of Gb3, globotriaosylsphingosine (Lyso-Gb3), as the main catabolite that increases in plasma and urine in patients with AFD. The mean concentrations of Gb3 in all organs and plasma of Galactosidase A knockout mice were significantly higher than those of wild-type mice. The distributions of Gb3 isoforms vary from organ to organ. Various Gb3 isoforms were observed mainly in the kidneys, and kidney-specific Gb3 isoforms were hydroxylated. Furthermore, the action of Gb3 on the KCa3.1 channel suggests a possible contribution of this interaction to the Fabry disease process, as this channel is expressed in various cells, including endothelial cells, fibroblasts, smooth muscle cells in proliferation, microglia, and lymphocytes. These molecular pathways could be considered a potential therapeutic target to correct the enzyme in addition to the traditional enzyme replacement therapies (ERT) or drug chaperone therapy.

Parsing Fabry Disease Metabolic Plasticity Using Metabolomics

Background: Fabry disease (FD) is an X-linked lysosomal disease due to a deficiency in the activity of the lysosomal α-galactosidase A (GalA), a key enzyme in the glycosphingolipid degradation pathway. FD is a complex disease with a poor genotype–phenotype correlation. FD could involve kidney, heart or central nervous system impairment that significantly decreases life expectancy. The advent of omics technologies offers the possibility of a global, integrated and systemic approach well-suited for the exploration of this complex disease. Materials and Methods: Sixty-six plasmas of FD patients from the French Fabry cohort (FFABRY) and 60 control plasmas were analyzed using liquid chromatography and mass spectrometry-based targeted metabolomics (188 metabolites) along with the determination of LysoGb3 concentration and GalA enzymatic activity. Conventional univariate analyses as well as systems biology and machine learning methods were used. Results: The analysis allowed for the identification of discriminating metabolic profiles that unambiguously separate FD patients from control subjects. The analysis identified 86 metabolites that are differentially expressed, including 62 Glycerophospholipids, 8 Acylcarnitines, 6 Sphingomyelins, 5 Aminoacids and 5 Biogenic Amines. Thirteen consensus metabolites were identified through network-based analysis, including 1 biogenic amine, 2 lysophosphatidylcholines and 10 glycerophospholipids. A predictive model using these metabolites showed an AUC-ROC of 0.992 (CI: 0.965–1.000). Conclusion: These results highlight deep metabolic remodeling in FD and confirm the potential of omics-based approaches in lysosomal diseases to reveal clinical and biological associations to generate pathophysiological hypotheses.

Application of Patient-Specific iPSCs for Modelling and Treatment of X-Linked Cardiomyopathies

Inherited cardiomyopathies are among the major causes of heart failure and associated with significant mortality and morbidity. Currently, over 70 genes have been linked to the etiology of various forms of cardiomyopathy, some of which are X-linked. Due to the lack of appropriate cell and animal models, it has been difficult to model these X-linked cardiomyopathies. With the advancement of induced pluripotent stem cell (iPSC) technology, the ability to generate iPSC lines from patients with X-linked cardiomyopathy has facilitated in vitro modelling and drug testing for the condition. Nonetheless, due to the mosaicism of the X-chromosome inactivation, disease phenotypes of X-linked cardiomyopathy in heterozygous females are also usually more heterogeneous, with a broad spectrum of presentation. Recent advancements in iPSC procedures have enabled the isolation of cells with different lyonisation to generate isogenic disease and control cell lines. In this review, we will summarise the current strategies and examples of using an iPSC-based model to study different types of X-linked cardiomyopathy. The potential application of isogenic iPSC lines derived from a female patient with heterozygous Danon disease and drug screening will be demonstrated by our preliminary data. The limitations of an iPSC-derived cardiomyocyte-based platform will also be addressed.

ECG-based score estimates the probability to detect Fabry Disease cardiac involvement

OBJECTIVES

To elaborate an ECG-based nomogram estimating the probability to detect cardiac involvement by cardiac magnetic resonance (CMR) in Fabry Disease (FD).

METHODS

119 FD patients and 26 healthy controls underwent ECG and CMR. Test (n = 88, 60%) and validation cohorts (n = 57, 40%) were randomly derived. Cardiac involvement was defined as the presence of low myocardial T1 value, a CMR-surrogate of myocardial glycosphingolipid storage. ECG changes associated with low T1 value were identified in the test cohort, included in the nomogram and then tested in the validation cohort.

RESULTS

Sokolow-Lyon index (AUC = 0.769), ratio between P-wave and PR-segment durations (Pwave/PRsegment) (AUC = 0.778), QRS duration (AUC = 0.703), QT (AUC = 0.769) duration were independently associated with the presence of low T1 on CMR at multivariate analysis. An ECG-based nomogram including these four parameters was accurate in identifying patients with CMR evidence of glycosphingolipid storage (c-index of the derived-nomogram = 0.90 in the test group; 0.81 in the validation group).

CONCLUSION

We propose a practical ECG-based nomogram accurately estimating the probability to detect low T1 values by CMR in FD patients. The application of this tool in clinical practice could improve early detection of FD cardiac involvement.

Recognition of pre-hypertrophic cardiac involvement in Fabry Disease based on automated electrocardiographic measures

BACKGROUND

Various electrocardiographic (ECG) indices have been shown to be useful for early recognition and staging of cardiac involvement in Fabry Disease (FD). However, many of them lack acceptable sensitivity and specificity. We assessed the value of automated ECG measures to discriminate between pre-hypertrophic FD and healthy individuals.

METHODS AND RESULTS

Normal ECGs from 1496 healthy individuals (57.4% male, age 37.4 ± 13 years) were compared to those of 142 FD patients without LVH (37.3% male, age 41.5 ± 18 years). All ECGs were analyzed centrally and a total of 429 automated ECG measures per individual were included for step-wise analysis. The Cramer V statistic was first used to pick out those parameters which were helpful in discriminating between the two groups and a final selection was made by using two models, namely the FLD (Fisher Linear Discrimination) and the Logistic model, to optimise diagnostic performance for the detection of cardiac involvement in FD patients vs. specificity in healthy individuals. The three-step statistical analysis identified 9 ECG parameters as most significant for the discrimination between the groups. The combined discriminant score yielded 64% sensitivity and 97% specificity for correct classification of FD patients in the test sample with a logistic area under curve of the ROC analysis of 0.97.

CONCLUSION

The combination of automated ECG measures identified via a stepwise statistical approach may be useful for detection of FD patients in the pre-hypertrophic stage. These data are promising for screening purposes in the very early stages of FD cardiomyopathy and warrant prospective confirmation.

Current and experimental therapeutics for Fabry disease

Fabry (or Anderson‐Fabry) is a rare pan‐ethnic disease affecting males and females. Fabry is an X‐linked lysosomal storage disease, affecting glycosphingolipid metabolism, that is caused by mutations of the GLA gene that codes for α‐galactosidase A. Fabry disease (FD) can be classified into a severe, classical phenotype, most often seen in men with no residual enzyme activity, that usually appear before 18 years and a usually milder, nonclassical (later‐onset) phenotype that usually appear above 18 years. Affected patients show multifactorial complications, including renal failure, cardiovascular problems, and neuropathy. In this review, we briefly report the clinical trials so far performed with the available therapies, and then we focus on the in vitro and the in vivo experimental models of the disease, to highlight the relevance in improving the existing therapeutics and understand the mechanism of this rare disorder. Current available in vivo and in vitro models can assist in better comprehension of the pathogenesis and underlying mechanisms of FD, thus the existing therapeutic approaches can be optimized, and new options can be developed.

Cardiac Thyrotropin-releasing Hormone Inhibition Improves Ventricular Function and Reduces Hypertrophy and Fibrosis After Myocardial Infarction in Rats

BACKGROUND

Cardiac thyrotropin-releasing hormone (TRH) is a tripeptide with still unknown functions. We demonstrated that the left ventricle (LV) TRH system is hyperactivated in spontaneously hypertensive rats and its inhibition prevented cardiac hypertrophy and fibrosis. Therefore, we evaluated whether in vivo cardiac TRH inhibition could improve myocardial function and attenuate ventricular remodeling in a rat model of myocardial infarction (MI).

METHODS AND RESULTS

In Wistar rats, MI was induced by a permanent left anterior descending coronary artery ligation. A coronary injection of a specific small interfering RNA against TRH was applied simultaneously. The control group received a scrambled small interfering RNA. Cardiac remodeling variables were evaluated one week later. In MI rats, TRH inhibition decreased LV end-diastolic (1.049 ± 0.102 mL vs 1.339 ± 0.102 mL, P < .05), and end-systolic volumes (0.282 ± 0.043 mL vs 0.515 ± 0.037 mL, P < .001), and increased LV ejection fraction (71.89 ± 2.80% vs 65.69 ± 2.85%, P < .05). Although both MI groups presented similar infarct size, small interfering RNA against TRH treatment attenuated the cardiac hypertrophy index and myocardial interstitial collagen deposition in the peri-infarct myocardium. These effects were accompanied by attenuation in the rise of transforming growth factor-β, collagen I, and collagen III, as well as the fetal genes (atrial natriuretic peptide, B-type natriuretic peptide, and beta myosin heavy chain) expression in the peri-infarct region. In addition, the expression of Hif1α and vascular endothelial growth factor significantly increased compared with all groups.

CONCLUSIONS

Cardiac TRH inhibition improves LV systolic function and attenuates ventricular remodeling after MI. These novel findings support the idea that TRH inhibition may serve as a new therapeutic strategy against the progression of heart failure.

Multi-omics integration identifies key upstream regulators of pathomechanisms in hypertrophic cardiomyopathy due to truncating MYBPC3 mutations

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is the most common genetic disease of the cardiac muscle, frequently caused by mutations in MYBPC3. However, little is known about the upstream pathways and key regulators causing the disease. Therefore, we employed a multi-omics approach to study the pathomechanisms underlying HCM comparing patient hearts harboring MYBPC3 mutations to control hearts.

RESULTS

Using H3K27ac ChIP-seq and RNA-seq we obtained 9310 differentially acetylated regions and 2033 differentially expressed genes, respectively, between 13 HCM and 10 control hearts. We obtained 441 differentially expressed proteins between 11 HCM and 8 control hearts using proteomics. By integrating multi-omics datasets, we identified a set of DNA regions and genes that differentiate HCM from control hearts and 53 protein-coding genes as the major contributors. This comprehensive analysis consistently points toward altered extracellular matrix formation, muscle contraction, and metabolism. Therefore, we studied enriched transcription factor (TF) binding motifs and identified 9 motif-encoded TFs, including KLF15, ETV4, AR, CLOCK, ETS2, GATA5, MEIS1, RXRA, and ZFX. Selected candidates were examined in stem cell-derived cardiomyocytes with and without mutated MYBPC3. Furthermore, we observed an abundance of acetylation signals and transcripts derived from cardiomyocytes compared to non-myocyte populations.

CONCLUSIONS

By integrating histone acetylome, transcriptome, and proteome profiles, we identified major effector genes and protein networks that drive the pathological changes in HCM with mutated MYBPC3. Our work identifies 38 highly affected protein-coding genes as potential plasma HCM biomarkers and 9 TFs as potential upstream regulators of these pathomechanisms that may serve as possible therapeutic targets.

Pol-miR-150 regulates anti-bacterial and viral infection in Japanese flounder (Paralichthys olivaceus) via the lysosomal protein LMP2L

MiR-150 is a microRNA (miRNA) present in a number of teleost species, but its target and regulation mechanism are unknown. Similarly, lysosome membrane protein 2-like (LMP2L) is a gene identified in fish but with unknown function. In this study, we examined the regulation mechanism and function of flounder miR-150 (named pol-miR-150) and its target gene LMP2L (named PoLMP2L) in association with bacterial and viral infection. We found that pol-miR-150 expression was not only modulated by the bacterial pathogen Streptococcus iniae but also by the viral pathogen megalocytivirus. Pol-miR-150 targeted PoLMP2L by binding to the 3'-untranslated region (3'-UTR) of PoLMP2L and inhibited PoLMP2L expression in vitro and in vivo. PoLMP2L is a member of the CD36 superfamily of scavenger receptors and homologous to but phylogenetically distinct from lysosomal integral membrane protein type 2 (LIMP2). PoLMP2L was localized mainly in the lysosomes and expressed in multiple organs of flounder. In vivo knockdown and overexpression of PoLMP2L enhanced and suppressed, respectively, S. iniae dissemination in flounder tissues, whereas in vivo knockdown and overexpression of pol-miR-150 produced the opposite effects on S. iniae dissemination. In addition, pol-miR-150 knockdown also significantly inhibited the replication of megalocytivirus. The results of this study revealed the regulation mechanism and immune functions of fish miR-150 and LMP2L, and indicated that LMP2L and miR-150 play an important role in the antimicrobial immunity of fish.

Cardiac Involvement in Fabry Disease: JACC Review Topic of the Week

Fabry disease (FD) is a rare X-linked inherited lysosomal storage disorder caused by deficient α-galactosidase A activity that leads to an accumulation of globotriasylceramide (Gb3) in affected tissues, including the heart. Cardiovascular involvement usually manifests as left ventricular hypertrophy, myocardial fibrosis, heart failure, and arrhythmias, which limit quality of life and represent the most common causes of death. Following the introduction of enzyme replacement therapy, early diagnosis and treatment have become essential to slow disease progression and prevent major cardiac complications. Recent advances in the understanding of FD pathophysiology suggest that in addition to Gb3 accumulation, other mechanisms contribute to the development of Fabry cardiomyopathy. Progress in imaging techniques have improved diagnosis and staging of FD-related cardiac disease, suggesting a central role for myocardial inflammation and setting the stage for further research. In addition, with the recent approval of oral chaperone therapy and new treatment developments, the FD-specific treatment landscape is rapidly evolving.

The Cardiovascular Phenotype in Fabry Disease: New Findings in the Research Field

Fabry disease (FD) is a lysosomal storage disorder, depending on defects in alpha-galactosidase A (GAL) activity. At the clinical level, FD shows a high phenotype variability. Among them, cardiovascular dysfunction is often recurrent or, in some cases, is the sole symptom (cardiac variant) representing the leading cause of death in Fabry patients. The existing therapies, besides specific symptomatic treatments, are mainly based on the restoration of GAL activity. Indeed, mutations of the galactosidase alpha gene (GLA) cause a reduction or lack of GAL activity leading to globotriaosylceramide (Gb3) accumulation in several organs. However, several other mechanisms are involved in FD’s development and progression that could become useful targets for therapeutics. This review discusses FD’s cardiovascular phenotype and the last findings on molecular mechanisms that accelerate cardiac cell damage.

Ion channels and pain in Fabry disease

Fabry disease (FD) is a progressive, X-linked inherited disorder of glycosphingolipid metabolism due to deficient or absent lysosomal α-galactosidase A (α-Gal A) activity which results in progressive accumulation of globotriaosylceramide (Gb3) and related metabolites. One prominent feature of Fabry disease is neuropathic pain. Accumulation of Gb3 has been documented in dorsal root ganglia (DRG) as well as other neurons, and has lately been associated with the mechanism of pain though the pathophysiology is still unclear. Small fiber (SF) neuropathy in FD differs from other entities in several aspects related to the perception of pain, alteration of fibers as well as drug therapies used in the practice with patients, with therapies far from satisfying. In order to develop better treatments, more information on the underlying mechanisms of pain is needed. Research in neuropathy has gained momentum from the development of preclinical models where different aspects of pain can be modelled and further analyzed. This review aims at describing the different in vitro and FD animal models that have been used so far, as well as some of the insights gained from their use. We focus especially in recent findings associated with ion channel alterations -that apart from the vascular alterations-, could provide targets for improved therapies in pain.

Lessons from iPSC research: Insights on peripheral nerve disease

With the publication of their breakthrough discovery describing the induction of pluripotent stem cells (iPSCs) from mouse and human fibroblasts, Takahashi and Yamanaka have changed the scientific landscape. The possibility of deriving human pluripotent stem cells from almost any somatic cell has provided the unprecedented opportunity to study specific hereditary diseases in human cells. In the context of diseases affecting peripheral nerves, iPSC platforms are now being increasingly utilized to investigate the underlying pathology as well as regenerative strategies. Peripheral neuropathies result in peripheral nerve damage, leading to - among other things - the degeneration of affected nerve fibers accompanied by severe sensory, motor and autonomic symptoms, often including intense pain. The generation of iPSCs from hereditary forms of peripheral neuropathies and their directed differentiation into cell types most affected by the disease can be instrumental to better understanding the pathological mechanisms underlying these disorders and to investigating cell replacement strategies for repair. In this minireview, we highlight studies that have used iPSCs to investigate the therapeutic potential of iPSC-derived Schwann cell-like cells for nerve regeneration, as well as studies using patient iPSC derivatives to investigate their contribution to disease pathology.

Dynamic changes in the epigenomic landscape regulate human organogenesis and link to developmental disorders

How the genome activates or silences transcriptional programmes governs organ formation. Little is known in human embryos undermining our ability to benchmark the fidelity of stem cell differentiation or cell programming, or interpret the pathogenicity of noncoding variation. Here, we study histone modifications across thirteen tissues during human organogenesis. We integrate the data with transcription to build an overview of how the human genome differentially regulates alternative organ fates including by repression. Promoters from nearly 20,000 genes partition into discrete states. Key developmental gene sets are actively repressed outside of the appropriate organ without obvious bivalency. Candidate enhancers, functional in zebrafish, allow imputation of tissue-specific and shared patterns of transcription factor binding. Overlaying more than 700 noncoding mutations from patients with developmental disorders allows correlation to unanticipated target genes. Taken together, the data provide a comprehensive genomic framework for investigating normal and abnormal human development.

A Proteomics-Based Analysis Reveals Predictive Biological Patterns in Fabry Disease

Background: Fabry disease (FD) is an X-linked progressive lysosomal disease (LD) due to glycosphingolipid metabolism impairment. Currently, plasmatic globotriaosylsphingosine (LysoGb3) is used for disease diagnosis and monitoring. However, this biomarker is inconstantly increased in mild forms and in some female patients. Materials and Methods: We applied a targeted proteomic approach to explore disease-related biological patterns that might explain the disease pathophysiology. Forty proteins, involved mainly in inflammatory and angiogenesis processes, were assessed in 69 plasma samples retrieved from the French Fabry cohort (FFABRY) and from 83 healthy subjects. For predictive performance assessment, we also included other LD samples (Gaucher, Pompe and Niemann Pick C). Results: The study yielded four discriminant proteins that include three angiogenesis proteins (fibroblast growth factor 2 (FGF2), vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor C (VEGFC)) and one cytokine interleukin 7 (IL-7). A clear elevation of FGF2 and IL-7 concentrations was observed in FD compared to other LD samples. No correlation was observed between these proteins and globotriaosylsphingosine (LysoGb3). A significant correlation exists between IL-7 and residual enzyme activity in a non-classical phenotype. This highlights the orthogonal biological information yielded by these proteins that might help in stratifying Fabry patients. Conclusion: This work highlights the potential of using proteomics approaches in exploring FD and enhancing FD diagnosis and therapeutic monitoring performances.

Altered Sphingolipids Metabolism Damaged Mitochondrial Functions: Lessons Learned From Gaucher and Fabry Diseases

Sphingolipids represent a class of bioactive lipids that modulate the biophysical properties of biological membranes and play a critical role in cell signal transduction. Multiple studies have demonstrated that sphingolipids control crucial cellular functions such as the cell cycle, senescence, autophagy, apoptosis, cell migration, and inflammation. Sphingolipid metabolism is highly compartmentalized within the subcellular locations. However, the majority of steps of sphingolipids metabolism occur in lysosomes. Altered sphingolipid metabolism with an accumulation of undigested substrates in lysosomes due to lysosomal enzyme deficiency is linked to lysosomal storage disorders (LSD). Trapping of sphingolipids and their metabolites in the lysosomes inhibits lipid recycling, which has a direct effect on the lipid composition of cellular membranes, including the inner mitochondrial membrane. Additionally, lysosomes are not only the house of digestive enzymes, but are also responsible for trafficking organelles, sensing nutrients, and repairing mitochondria. However, lysosomal abnormalities lead to alteration of autophagy and disturb the energy balance and mitochondrial function. In this review, an overview of mitochondrial function in cells with altered sphingolipid metabolism will be discussed focusing on the two most common sphingolipid disorders, Gaucher and Fabry diseases. The review highlights the status of mitochondrial energy metabolism and the regulation of mitochondria-autophagy-lysosome crosstalk.