Increased oxidative stress contributes to cardiomyocyte dysfunction and death in patients with Fabry disease cardiomyopathy

Long-Term Clinical-Pathologic Results of Enzyme Replacement Therapy in Prehypertrophic Fabry Disease Cardiomyopathy

BACKGROUND

The limited ability of enzyme replacement therapy (ERT) in removing globotriaosylceramide from cardiomyocytes is recognized for advanced Fabry disease cardiomyopathy (FDCM). Prehypertrophic FDCM is believed to be cured or stabilized by ERT. However, no pathologic confirmation is available. We report here on the long-term clinical-pathologic impact of ERT on prehypertrophic FDCM.

METHODS AND RESULTS

Fifteen patients with Fabry disease with left ventricular maximal wall thickness ≤10.5 mm at cardiac magnetic resonance required endomyocardial biopsy because of angina and ventricular arrhythmias. Endomyocardial biopsy showed coronary small-vessel disease in the angina cohort, and vacuoles in smooth muscle cells and cardiomyocytes ≈20% of the cell surface containing myelin bodies at electron microscopy. Patients received α-agalsidase in 8 cases, and β-agalsidase in 7 cases. Both groups experienced symptom improvement except 1 patients treated with α-agalsidase and 1 treated with β-agalsidase. After ERT administration ranging from 4 to 20 years, all patients had control cardiac magnetic resonance and left ventricular endomyocardial biopsy because of persistence of symptoms or patient inquiry on disease resolution. In 13 asymptomatic patients with FDCM, left ventricular maximal wall thickness and left ventricular mass, cardiomyocyte diameter, vacuole surface/cell surface ratio, and vessels remained unchanged or minimally increased (left ventricular mass increased by <2%) even after 20 years of observation, and storage material was still present at electron microscopy. In 2 symptomatic patients, FDCM progressed, with larger and more engulfed by globotriaosylceramide myocytes being associated with myocardial virus-negative lymphocytic inflammation.

CONCLUSIONS

ERT stabilizes storage deposits and myocyte dimensions in 87% of patients with prehypertrophic FDCM. Globotriaosylceramide is never completely removed even after long-term treatment. Immune-mediated myocardial inflammation can overlap, limiting ERT activity.

Inflammation and Exosomes in Fabry Disease Pathogenesis

Fabry Disease (FD) is one of the most prevalent lysosomal storage disorders, resulting from mutations in the GLA gene located on the X chromosome. This genetic mutation triggers glo-botriaosylceramide (Gb-3) buildup within lysosomes, ultimately impairing cellular functions. Given the role of lysosomes in immune cell physiology, FD has been suggested to have a profound impact on immunological responses. During the past years, research has been focusing on this topic, and pooled evidence strengthens the hypothesis that Gb-3 accumulation potentiates the production of pro-inflammatory mediators, revealing the existence of an acute inflammatory process in FD that possibly develops to a chronic state due to stimulus persistency. In parallel, extracellular vesicles (EVs) have gained attention due to their function as intercellular communicators. Considering EVs' capacity to convey cargo from parent to distant cells, they emerge as potential inflammatory intermediaries capable of transporting cytokines and other immunomodulatory molecules. In this review, we revisit the evidence underlying the association between FD and altered immune responses and explore the potential of EVs to function as inflammatory vehicles.

Updated Evaluation of Agalsidase Alfa Enzyme Replacement Therapy for Patients with Fabry Disease: Insights from Real-World Data

The clinical use of agalsidase alfa as enzyme replacement therapy (ERT) for Fabry disease (FD) has spread since 2001, and a large body of evidence of its effectiveness has been collected. This review presents the clinical and laboratory results achieved with agalsidase alfa, which has been published in the literature. Agalsidase alfa infusion slows down or stops the progression of renal damage, expressed by reduction or stabilization of the annual decline of the glomerular filtration rate; yearly decrease of glomerular filtration rate (slope) sometimes is reduced until its stabilization. ERT prevents or reduces the occurrence of hypertrophic cardiomyopathy or slows the increase over time if it is already present. Moreover, regarding neurological manifestations, ERT improves neuropathic pain and quality of life, and recent data indicated that it may also prevent the burden of cerebrovascular disease. In addition to ERT's clinical benefits, crucial topics like the most appropriate time to start therapy and the role of anti-drug antibodies (ADA) are analyzed. Treatment with agalsidase alfa in patients with FD substantially improves their outcomes and enhances their quality of life in patients with FD.

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.

Infertility in Fabry's Disease: role of hypoxia and inflammation in determining testicular damage

Introduction

Fabry's disease (FD) is a genetic X-linked systemic and progressive rare disease characterized by the accumulation of globotriaosylceramide (GB3) into the lysosomes of many tissues. FD is due to loss-of-function mutations of α-galactosidase, a key-enzyme for lysosomal catabolism of glycosphingolipids, which accumulate as glycolipid bodies (GB). In homozygous males the progressive deposition of GB3 into the cells leads to clinical symptoms in CNS, skin, kidney, etc. In testis GB accumulation causes infertility and alterations of spermatogenesis. However, the precise damaging mechanism is still unknown. Our hypothesis is that GB accumulation reduces blood vessel lumen and increases the distance of vessels from both stromal cells and seminiferous parenchyma; this, in turn, impairs oxygen and nutrients diffusion leading to subcellular degradation of seminiferous epithelium and sterility.

Methods

To test this hypothesis, we have studied a 42-year-old patient presenting a severe FD and infertility, with reduced number of spermatozoa, but preserved sexual activity. Testicular biopsies were analyzed by optical (OM) and transmission electron microscopy (TEM). Activation and cellular localization of HIF-1α and NFκB was analyzed by immunofluorescence (IF) and RT-PCR on homogeneous tissue fractions after laser capture microdissection (LCMD).

Results

OM and TEM showed that GB were abundant in vessel wall cells and in interstitial cells. By contrast, GB were absent in seminiferous epithelium, Sertoli's and Leydig's cells. However, seminiferous tubular epithelium and Sertoli's cells showed reduced diameter, thickening of basement membrane and tunica propria, and swollen or degenerated spermatogonia. IF showed an accumulation of HIF-1α in stromal cells but not in seminiferous tubules. On the contrary, NFκB fluorescence was evident in tubules, but very low in interstitial cells. Finally, RT-PCR analysis on LCMD fractions showed the expression of pro-inflammatory genes connected to the HIF-1α/NFκB inflammatory-like pathway.

Conclusion

Our study demonstrates that infertility in FD may be caused by reduced oxygen and nutrients due to GB accumulation in blood vessels cells. Reduced oxygen and nutrients alter HIF-1α/NFκB expression and localization while activating HIF-1α/NFκB driven-inflammation-like response damaging seminiferous tubular epithelium and Sertoli's cells.

Hypertrophic obstructive cardiomyopathy caused by Fabry disease: implications for surgical myectomy

Hypertrophic obstructive cardiomyopathy can be the phenotype of storage disorders as Fabry disease cardiomyopathy. In this instance, its recognition through GLA gene analysis and preventive administration of enzyme replacement therapy may reduce heart failure risk of surgical septal myectomy (SSM). A 59-year-old man was referred for SSM as dyspnoea and low threshold muscle fatigue associated to severe left ventricular outflow obstruction (gradient of 100 mmHg) due to both interventricular septal hypertrophy and mitral leaflet systolic anterior motion were not controlled by metoprolol 100 mg bid. Electrocardiogram showed sinus rhythm and a complete left bundle branch block. Cardiac magnetic resonance imaging showed a preserved left ventricular (LV) contractility (ejection fraction 70%) but failed to reveal reduced T1 mapping and fibrosis of postero-lateral LV wall suggesting Fabry disease cardiomyopathy. Cardiac catheterization and coronary angiography documented increased LV end-diastolic pressure but normal coronary arteries. SSM was followed by acute renal and heart failure with left ventricular ejection fraction declining to 35%. Histology of SSM showed regularly arranged severely enlarged cardiomyocytes containing extensive vacuoles that were intensely positive to immunofluorescence with anti-Gb3 antibodies and appeared at electron microscopy to consist of myelin bodies suggesting the diagnosis of FD. This entity was confirmed by low blood levels of alpha-galactosidase A (0.8 nmol/mL/h; NV > 1), high values of Lyso-Gb3 (5.85 nmol/L; NV < 2.3), and the presence of the pathogenic mutation c.644A>G in the exon 5 of GLA gene. This study emphasizes the importance of a genetic screening for FD before SSM be considered for hypertrophic obstructive cardiomyopathy.

Endothelial Cell Dysfunction and Hypoxia as Potential Mediators of Pain in Fabry Disease: A Human-Murine Translational Approach

Fabry disease (FD) is caused by α-galactosidase A (AGAL) enzyme deficiency, leading to globotriaosylceramide accumulation (Gb3) in several cell types. Pain is one of the pathophysiologically incompletely understood symptoms in FD patients. Previous data suggest an involvement of hypoxia and mitochondriopathy in FD pain development at dorsal root ganglion (DRG) level. Using immunofluorescence and quantitative real-time polymerase chain reaction (qRT PCR), we investigated patient-derived endothelial cells (EC) and DRG tissue of the GLA knockout (KO) mouse model of FD. We address the question of whether hypoxia and mitochondriopathy contribute to FD pain pathophysiology. In EC of FD patients (P1 with pain and, P2 without pain), we found dysregulated protein expression of hypoxia-inducible factors (HIF) 1a and HIF2 compared to the control EC (p < 0.01). The protein expression of the HIF downstream target vascular endothelial growth factor A (VEGFA, p < 0.01) was reduced and tube formation was hampered in the P1 EC compared to the healthy EC (p < 0.05). Tube formation ability was rescued by applying transforming growth factor beta (TGFβ) inhibitor SB-431542. Additionally, we found dysregulated mitochondrial fusion/fission characteristics in the P1 and P2 EC (p < 0.01) and depolarized mitochondrial membrane potential in P2 compared to control EC (p < 0.05). Complementary to human data, we found upregulated hypoxia-associated genes in the DRG of old GLA KO mice compared to WT DRG (p < 0.01). At protein level, nuclear HIF1a was higher in the DRG neurons of old GLA KO mice compared to WT mice (p < 0.01). Further, the HIF1a downstream target CA9 was upregulated in the DRG of old GLA KO mice compared to WT DRG (p < 0.01). Similar to human EC, we found a reduction in the vascular characteristics in GLA KO DRG compared to WT (p < 0.05). We demonstrate increased hypoxia, impaired vascular properties, and mitochondrial dysfunction in human FD EC and complementarily at the GLA KO mouse DRG level. Our data support the hypothesis that hypoxia and mitochondriopathy in FD EC and GLA KO DRG may contribute to FD pain development.

Consensus recommendations for the treatment and management of patients with Fabry disease on migalastat: a modified Delphi study

Objective

Fabry disease is a progressive disorder caused by deficiency of the α-galactosidase A enzyme (α-Gal A), leading to multisystemic organ damage with heterogenous clinical presentation. The addition of the oral chaperone therapy migalastat to the available treatment options for Fabry disease is not yet universally reflected in all treatment guidelines. These consensus recommendations are intended to provide guidance for the treatment and monitoring of patients with Fabry disease receiving migalastat.

Methods

A modified Delphi process was conducted to determine consensus on treatment decisions and monitoring of patients with Fabry disease receiving migalastat. The multidisciplinary panel comprised 14 expert physicians across nine specialties and two patients with Fabry disease. Two rounds of Delphi surveys were completed and recommendations on the use of biomarkers, multidisciplinary monitoring, and treatment decisions were generated based on statements that reached consensus.

Results

The expert panel reached consensus agreement on 49 of 54 statements, including 16 that reached consensus in round 1. Statements that reached consensus agreement are summarized in recommendations for migalastat treatment and monitoring, including baseline and follow-up assessments and frequency. All patients with Fabry disease and an amenable mutation may initiate migalastat treatment if they have evidence of Fabry-related symptoms and/or organ involvement. Treatment decisions should include holistic assessment of the patient, considering clinical symptoms and organ involvement as well as patient-reported outcomes and patient preference. The reliability of α-Gal A and globotriaosylsphingosine as pharmacodynamic response biomarkers remains unclear.

Conclusion

These recommendations build on previously published guidelines to highlight the importance of holistic, multidisciplinary monitoring for patients with Fabry disease receiving migalastat, in addition to shared decision-making regarding treatments and monitoring throughout the patient journey. GRAPHICAL ABSTRACT.

The Role of MicroRNA in the Myocarditis: a Small Actor for a Great Role

PURPOSE OF REVIEW

Myocarditis is an inflammation of the myocardium secondary to a variety of agents such as infectious pathogens, toxins, drugs, and autoimmune disorders. In our review, we provide an overview of miRNA biogenesis and their role in the etiology and pathogenesis of myocarditis, evaluating future directions for myocarditis management.

RECENT FINDINGS

Advances in genetic manipulation techniques allowed to demonstrate the important role of RNA fragments, especially microRNAs (miRNAs), in cardiovascular pathogenesis. miRNAs are small non-coding RNA molecules that regulate the post-transcriptional gene expression. Advances in molecular techniques allowed to identify miRNA's role in pathogenesis of myocarditis. miRNAs are related to viral infection, inflammation, fibrosis, and apoptosis of cardiomyocytes, making them not only promising diagnostic markers but also prognostics and therapeutic targets in myocarditis. Of course, further real-world studies will be needed to assess the diagnostic accuracy and applicability of miRNA in the myocarditis diagnosis.

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.

Fabry disease - a genetically conditioned extremely rare disease with a very unusual course

Fabry disease (FD) is a rare lysosomal storage disease. FD is caused by the presence of a deleterious mutation in the GLA gene encoding the enzyme alpha galactosidase A (αGAL A) on the X chromosome. The accumulation of Gb3 and lyso-GL-3 in nerve fiber cells, endothelium, vascular muscle cells, mesangial cells, podocytes, renal tubular epithelial cells and cardiomyocytes is the most important pathogenetic factor. The rate of disease progression depends on residual conserved enzymatic activity. In this article we present an example of a 25-year-old patient with FD with an initial asymptomatic course. The first manifestation of FD developed in the third decade of life. These include high blood pressure, urinary changes and grade V renal failure, requiring renal replacement therapy. The diagnosis was made very late, when renal failure and cerebro-cardiac complications occurred, including stroke and dangerous cardiac tamponade.

Ion Channel Impairment and Myofilament Ca2+ Sensitization: Two Parallel Mechanisms Underlying Arrhythmogenesis in Hypertrophic Cardiomyopathy

Life-threatening ventricular arrhythmias are the main clinical burden in patients with hypertrophic cardiomyopathy (HCM), and frequently occur in young patients with mild structural disease. While massive hypertrophy, fibrosis and microvascular ischemia are the main mechanisms underlying sustained reentry-based ventricular arrhythmias in advanced HCM, cardiomyocyte-based functional arrhythmogenic mechanisms are likely prevalent at earlier stages of the disease. In this review, we will describe studies conducted in human surgical samples from HCM patients, transgenic animal models and human cultured cell lines derived from induced pluripotent stem cells. Current pieces of evidence concur to attribute the increased risk of ventricular arrhythmias in early HCM to different cellular mechanisms. The increase of late sodium current and L-type calcium current is an early observation in HCM, which follows post-translation channel modifications and increases the occurrence of early and delayed afterdepolarizations. Increased myofilament Ca²⁺ sensitivity, commonly observed in HCM, may promote afterdepolarizations and reentry arrhythmias with direct mechanisms. Decrease of K⁺-currents due to transcriptional regulation occurs in the advanced disease and contributes to reducing the repolarization-reserve and increasing the early afterdepolarizations (EADs). The presented evidence supports the idea that patients with early-stage HCM should be considered and managed as subjects with an acquired channelopathy rather than with a structural cardiac disease.

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.

Biomarkers in Fabry Disease. Implications for Clinical Diagnosis and Follow-up

Fabry disease (FD) is a lysosomal storage disorder caused by deficient alpha-galactosidase A activity in the lysosome due to mutations in the GLA gene, resulting in gradual accumulation of globotriaosylceramide and other derivatives in different tissues. Substrate accumulation promotes different pathogenic mechanisms in which several mediators could be implicated, inducing multiorgan lesions, mainly in the kidney, heart and nervous system, resulting in clinical manifestations of the disease. Enzyme replacement therapy was shown to delay disease progression, mainly if initiated early. However, a diagnosis in the early stages represents a clinical challenge, especially in patients with a non-classic phenotype, which prompts the search for biomarkers that help detect and predict the evolution of the disease. We have reviewed the mediators involved in different pathogenic mechanisms that were studied as potential biomarkers and can be easily incorporated into clinical practice. Some accumulation biomarkers seem to be useful to detect non-classic forms of the disease and could even improve diagnosis of female patients. The combination of such biomarkers with some response biomarkers, may be useful for early detection of organ injury. The incorporation of some biomarkers into clinical practice may increase the capacity of detection compared to that currently obtained with the established diagnostic markers and provide more information on the progression and prognosis of the disease.

Chloroquine may induce endothelial injury through lysosomal dysfunction and oxidative stress

COVID-19 is a pandemic with no end in sight. There is only one approved antiviral agent but global stocks are deemed insufficient. Despite in vitro antiviral activity, clinical trials of chloroquine and hydroxychloroquine were disappointing, and they may even impair outcomes. Chloroquine causes zebroid deposits reminiscent of Fabry disease (α-galactosidase A deficiency) and endothelial cells are key targets of COVID-19. We have explored the effect of chloroquine on cultured endothelial cells and its modulation by recombinant α-galactosidase A (agalsidase). Following dose-response studies, 0.5 μg/mL chloroquine was added to cultured human endothelial cells. Neutral red and Lysotracker were used to assess lysosomes. Cytotoxicity was evaluated by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) - MTT assay and cell stress by assessing reactive oxygen species (ROS) and nitric oxide (NO). In endothelial cells, chloroquine induced dose-dependent cytotoxicity at in vitro test concentrations for COVID-19 therapy. At a sublethal concentration, chloroquine significantly induced the accumulation of acid organelles (P < 0.05), increased ROS levels, and decreased NO production (P < 0.05). These adverse effects of chloroquine on endothelial cell biology were decreased by agalsidase-β (P < 0.05). Chloroquine-induced endothelial cell cytotoxicity and stress is attenuated by agalsidase-β treatment. This suggests that endothelial cell injury may contribute to the failure of chloroquine as therapy for COVID-19 and may be at least in part related to causing dysfunction of the lysosomal enzyme α-galactosidase A.

Mechanisms of Mitochondrial Dysfunction in Lysosomal Storage Disorders: A Review

Mitochondrial dysfunction is emerging as an important contributory factor to the pathophysiology of lysosomal storage disorders (LSDs). The cause of mitochondrial dysfunction in LSDs appears to be multifactorial, although impaired mitophagy and oxidative stress appear to be common inhibitory mechanisms shared amongst these heterogeneous disorders. Once impaired, dysfunctional mitochondria may impact upon the function of the lysosome by the generation of reactive oxygen species as well as depriving the lysosome of ATP which is required by the V-ATPase proton pump to maintain the acidity of the lumen. Given the reported evidence of mitochondrial dysfunction in LSDs together with the important symbiotic relationship between these two organelles, therapeutic strategies targeting both lysosome and mitochondrial dysfunction may be an important consideration in the treatment of LSDs. In this review we examine the putative mechanisms that may be responsible for mitochondrial dysfunction in reported LSDs which will be supplemented with morphological and clinical information.

Oxidative stress biomarkers in Fabry disease: is there a room for them?

BACKGROUND

Fabry disease (FD) is an X-linked lysosomal storage disorder, caused by deficient activity of the alpha-galactosidase A enzyme leading to progressive and multisystemic accumulation of globotriaosylceramide. Recent data point toward oxidative stress signalling which could play an important role in both pathophysiology and disease progression.

METHODS

We have examined oxidative stress biomarkers [Advanced Oxidation Protein Products (AOPP), Ferric Reducing Antioxidant Power (FRAP), thiolic groups] in blood samples from 60 patients and 77 healthy controls.

RESULTS

AOPP levels were higher in patients than in controls (p < 0.00001) and patients presented decreased levels of antioxidant defences (FRAP and thiols) with respect to controls (p < 0.00001). In a small group of eight treatment-naïve subjects with FD-related mutations, we found altered levels of oxidative stress parameters and incipient signs of organ damage despite normal lyso-Gb3 levels.

CONCLUSIONS

Oxidative stress occurs in FD in both treated and naïve patients, highlighting the need of further research in oxidative stress-targeted therapies. Furthermore, we found that oxidative stress biomarkers may represent early markers of disease in treatment-naïve patients with a potential role in helping interpretation of FD-related mutations and time to treatment decision.

Tp-e interval and Tp-e/QT ratio and their association with left ventricular diastolic dysfunction in Fabry disease without left ventricular hypertrophy

INTRODUCTION

In the early stage of the Fabry disease, diastolic dysfunction can occur before left ventricular hypertrophy (LVH). Cardiovascular complications, most of which are seen as malignant arrhythmias and heart failure, are the leading causes of death in these patients. The aim of the present study was to assess repolarization parameters of Fabry patients in early stage (without LVH) and to show the relationship between these parameters and left ventricular diastolic dysfunction.

METHODS

This cross-sectional single center study was carried out with newly diagnosed 23 Fabry patients and 20 healthy individuals, between April 2016 and September 2019. Diagnosis of Fabry disease was based on a measurement of enzyme activity in leukocytes and was confirmed by genetic analysis. Basic, demographic and clinical features were reviewed. The risk of ventricular arrhythmia was evaluated by calculating the electrocardiographic, the Tp-e and QT interval, corrected QT (QTc), Tp-e/QT and Tp-e/QTc ratios. Left ventricular systolic and diastolic dysfunctions were evaluated using echocardiography.

RESULTS

Tp-e interval (86.9 ± 6.2 vs. 73.8 ± 6.3 ms; p < 0.001), Tp-e/QT ratio (0.23 ± 0.008 vs. 0.21 ± 0.01; p < 0.001) and Tp-e/QTc ratio (0.21 ± 0.007vs. 0.18 ± 0.017; p < 0.001) were significantly higher in Fabry patients than the control group. There was a significant positive correlation between Tp-e interval and E/e' ratio (r = 0.626, p = 0.003) and Tp-e/QTc ratio and E/e' ratio (r = 0.578, p = 0.008) in Fabry patients.

CONCLUSION

Our study showed that the Tp-e interval, Tp-e/QT ratio, and Tp-e/QTc ratio, which are evaluated electrocardiographically in patients with pre-hypertrophic Fabry patients, are prolonged compared to normal healthy individuals. The most significant finding was the positive correlation found between repolarization parameters and LV diastolic dysfunction. These results may be indicative of an early subclinical cardiac involvement in Fabry patients, considering the diastolic dysfunction severity.

Metabolic Alterations in Inherited Cardiomyopathies

The normal function of the heart relies on a series of complex metabolic processes orchestrating the proper generation and use of energy. In this context, mitochondria serve a crucial role as a platform for energy transduction by supplying ATP to the varying demand of cardiomyocytes, involving an intricate network of pathways regulating the metabolic flux of substrates. The failure of these processes results in structural and functional deficiencies of the cardiac muscle, including inherited cardiomyopathies. These genetic diseases are characterized by cardiac structural and functional anomalies in the absence of abnormal conditions that can explain the observed myocardial abnormality, and are frequently associated with heart failure. Since their original description, major advances have been achieved in the genetic and phenotype knowledge, highlighting the involvement of metabolic abnormalities in their pathogenesis. This review provides a brief overview of the role of mitochondria in the energy metabolism in the heart and focuses on metabolic abnormalities, mitochondrial dysfunction, and storage diseases associated with inherited cardiomyopathies.

Globotriaosylceramide-induced reduction of KCa1.1 channel activity and activation of the Notch1 signaling pathway in skin fibroblasts of male Fabry patients with pain

BACKGROUND

Fabry disease (FD) is an X-linked lysosomal storage disorder that leads to cellular globotriaosylceramide (Gb3) accumulation due to mutations in the gene encoding α-galactosidase A. Trigger-induced acral burning pain is an early FD symptom of unknown pathophysiology. We aimed at investigating the potential role of skin fibroblasts in nociceptor sensitization.

PATIENTS AND METHODS

We enrolled 40 adult FD patients and ten healthy controls, who underwent a 6-mm skin punch biopsy at the lower leg. Dermal fibroblasts were cultivated and analyzed for Gb3 load. Fibroblast electrical activity was assessed using patch-clamp analysis at baseline and upon incubation with agalsidase-α for 24 h. We investigated gene expression of CC motif chemokine ligand 2 (CCL2), Ca²⁺activated K⁺-channel 1.1 (K_Ca1.1), interferone-γ (IFN-γ), transforming growth factor-β1 (TGF-β1), and transmembrane receptor notch homolog 1 (Notch1) using quantitative real-time-PCR, and protein levels of K_Ca1.1 by ELISA. Gene expression was determined at baseline and after fibroblast stimulation with tumor necrosis factor-α (TNF), modeling inflammation as a common pain trigger in FD.

RESULTS

Total Gb3 load was higher in FD fibroblasts than in control fibroblasts (p < .01). Upon increase of intracellular Ca²⁺ concentrations, we detected differential electrical activity of K_Ca1.1 in fibroblasts obtained from patients with FD. Gene expression (p < .05) and protein levels of K_Ca1.1 (p < .05) were higher in fibroblasts from FD patients compared to control fibroblasts, whereas electric channel activity was lower in FD fibroblasts. After incubation with agalsidase-α, we observed an over-proportionate increase of K_Ca1.1 activity in FD fibroblasts reaching 7-fold the currents of control cells (p < .01). Gene expression studies revealed higher mRNA levels of CCL2, INF-γ, and Notch1 in FD fibroblasts compared to controls at baseline and after TNF incubation (p < .05 each), while TGF-β1 was higher in FD fibroblasts only after incubation with TNF (p < .05).

CONCLUSIONS

Gb3 deposition in skin fibroblasts may impair K_Ca1.1 activity and activate the Notch1 signaling pathway. The resulting increase in pro-inflammatory mediator expression may contribute to cutaneous nociceptor sensitization as a potential mechanism of FD-associated pain.

Inhibition of Mitochondrial Complex I Impairs Release of α-Galactosidase by Jurkat Cells

Fabry disease (FD) is caused by mutations in the GLA gene that encodes lysosomal α-galactosidase-A (α-gal-A). A number of pathogenic mechanisms have been proposed and these include loss of mitochondrial respiratory chain activity. For FD, gene therapy is beginning to be applied as a treatment. In view of the loss of mitochondrial function reported in FD, we have considered here the impact of loss of mitochondrial respiratory chain activity on the ability of a GLA lentiviral vector to increase cellular α-gal-A activity and participate in cross correction. Jurkat cells were used in this study and were exposed to increasing viral copies. Intracellular and extracellular enzyme activities were then determined; this in the presence or absence of the mitochondrial complex I inhibitor, rotenone. The ability of cells to take up released enzyme was also evaluated. Increasing transgene copies was associated with increasing intracellular α-gal-A activity but this was associated with an increase in Km. Release of enzyme and cellular uptake was also demonstrated. However, in the presence of rotenone, enzyme release was inhibited by 37%. Excessive enzyme generation may result in a protein with inferior kinetic properties and a background of compromised mitochondrial function may impair the cross correction process.

Hypertrophic Cardiomyopathy: A Vicious Cycle Triggered by Sarcomere Mutations and Secondary Disease Hits

Significance: Hypertrophic cardiomyopathy (HCM) is a cardiac genetic disease characterized by left ventricular hypertrophy, diastolic dysfunction, and myocardial disarray. Disease onset occurs between 20 and 50 years of age, thus affecting patients in the prime of their life. HCM is caused by mutations in sarcomere proteins, the contractile building blocks of the heart. Despite increased knowledge of causal mutations, the exact path from genetic defect leading to cardiomyopathy is complex and involves additional disease hits. Recent Advances: Laboratory-based studies indicate that HCM development not only depends on the primary sarcomere impairment caused by the mutation but also on secondary disease-related alterations in the heart. Here we propose a vicious mutation-induced disease cycle, in which a mutation-induced energy depletion alters cellular metabolism with increased mitochondrial work, which triggers secondary disease modifiers that will worsen disease and ultimately lead to end-stage HCM. Critical Issues: Evidence shows excessive cellular reactive oxygen species (ROS) in HCM patients and HCM animal models. Oxidative stress markers are increased in the heart (oxidized proteins, DNA, and lipids) and serum of HCM patients. In addition, increased mitochondrial ROS production and changes in endogenous antioxidants are reported in HCM. Mutant sarcomeric protein may drive excessive levels of cardiac ROS via changes in cardiac efficiency and metabolism, mitochondrial activation and/or dysfunction, impaired protein quality control, and microvascular dysfunction. Future Directions: Interventions restoring metabolism, mitochondrial function, and improved ROS balance may be promising therapeutic approaches. We discuss the effects of current HCM pharmacological therapies and potential future therapies to prevent and reverse HCM. Antioxid. Redox Signal. 31, 318-358.

Energetic drain driving hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common form of hereditary cardiomyopathy and is mainly caused by mutations of genes encoding cardiac sarcomeric proteins. HCM is characterized by hypertrophy of the left ventricle, frequently involving the septum, that is not explained solely by loading conditions. HCM has a heterogeneous clinical profile, but diastolic dysfunction and ventricular arrhythmias represent two dominant features of the disease. Preclinical evidence indicates that the enhanced Calcium (Ca²⁺ ) sensitivity of the myofilaments plays a key role in the pathophysiology of HCM. Notably, this is not always a direct consequence of sarcomeric mutations, but can also result from secondary mutation-driven alterations. Here, we review experimental and clinical evidence indicating that increased myofilament Ca²⁺ sensitivity lies upstream of numerous cellular derangements which potentially contribute to the progression of HCM toward heart failure and sudden cardiac death.

Voluntary wheel running activates Akt/AMPK/eNOS signaling cascades without improving profound endothelial dysfunction in mice deficient in α-galactosidase A

Fabry disease is caused by loss of activity of the lysosomal hydrolase α-galactosidase A (GLA). Premature life-threatening complications in Fabry patients arise from cardiovascular disease, including stroke and myocardial infarction. Exercise training has been shown to improve endothelial dysfunction in various settings including coronary artery disease. However, the effects of exercise training on endothelial dysfunction in Fabry disease have not been investigated. Gla knockout mice were single-housed in a cage equipped with a voluntary wheel (EX) or no wheel (SED) for 12 weeks. Exercised mice ran 10 km/day on average during the voluntary running intervention (VR) period. Despite significantly higher food intake in EX than SED, body weights of EX and SED remained stable during the VR period. After the completion of VR, citrate synthase activity in gastrocnemius muscle was significantly higher in EX than SED. VR resulted in greater phosphorylation of Akt (S473) and AMPK (T172) in the aorta of EX compared to SED measured by western blot. Furthermore, VR significantly enhanced eNOS protein expression and phosphorylation at S1177 by 20% and 50% in the aorta of EX when compared with SED. Similarly, plasma nitrate and nitrite levels were 77% higher in EX than SED. In contrast, measures of anti- and pro-oxidative enzymes (superoxide dismutase and p67phox subunit of NADPH oxidase) and overall oxidative stress (plasma oxidized glutathione) were not different between groups. Although the aortic endothelial relaxation to acetylcholine was slightly increased in EX, it did not reach statistical significance. This study provides the first evidence that VR improves Akt/AMPK/eNOS signaling cascades, but not endothelial function in the aorta of aged Gla deficient mice.

Inhibition of MicroRNA-23 Contributes to the Isoflurane-Mediated Cardioprotection Against Oxidative Stress

Isoflurane is one of the most frequently used volatile anesthetics in clinical practice for inhalational anesthesia. It is widely studied that isoflurane mediates cardioprotection during multiple pathological processes. However, the precise mechanisms have not been fully elucidated. Neonatal cardiomyocytes were isolated and cultured, followed by treatments with isoflurane at 0, 50, 100 or 200 µM. Rat cardiomyoblast cell line, H9c2, was treated with H₂O₂. Expression of miR-23 was measured by qRT-PCR. The cell survival rate of H9c2 in response to H₂O₂ treatments was evaluated by MTT assay. The ROS and GSH/GSSG levels were measured using Superoxide Detection Kit and GSH/GSSG Ratio Detection Assay Kit. In this study, we report an isoflurane-miR-23-antioxidant axis in cardiomyocyte. We observed that miR-23 was suppressed by isoflurane treatments at 50, 100 or 200 µM. Moreover, cardiomyocyte with isoflurane exposure was insensitive to H₂O₂ treatment in vitro. Inhibition of miR-23 protected cardiomyocyte against oxidative stress induced by H₂O₂ treatments at 30, 60, 90 or 120 µM. In addition, overexpression of miR-23 induced ROS generation over twofolds and rendered cardiomyocyte sensitive to H₂O₂ treatments. We demonstrate that miR-23 inhibited intracellular GSH, an antioxidant against oxidative stress. Our results reveal that with isoflurane exposure, overexpression of miR-23 rendered cardiomyocyte sensitive to H₂O₂ treatments at 20, 30, 40, 50 µM. Pretreatments with GSH in miR-23 overexpressing cells rescued the cell death under oxidative stress. In summary, our results illustrate that the isoflurane-mediated protection of cardiomyocytes under oxidative stress is through inhibition of miR-23. This study provides an aspect for the miRNAs-modulated cardiomyocyte sensitivity to oxidative stress, contributing to the development of therapeutic agents.

Characterization of small fiber pathology in a mouse model of Fabry disease

Fabry disease (FD) is a life-threatening X-linked lysosomal storage disorder caused by α-galactosidase A (α-GAL) deficiency. Small fiber pathology and pain are major FD symptoms of unknown pathophysiology. α-GAL deficient mice (GLA KO) age-dependently accumulate globotriaosylceramide (Gb3) in dorsal root ganglion (DRG) neurons paralleled by endoplasmic stress and apoptosis as contributors to skin denervation. Old GLA KO mice show increased TRPV1 protein in DRG neurons and heat hypersensitivity upon i.pl. capsaicin. In turn, GLA KO mice are protected from heat and mechanical hypersensitivity in neuropathic and inflammatory pain models based on reduced neuronal I_h and Na_v1.7 currents. We show that in vitro α-GAL silencing increases intracellular Gb3 accumulation paralleled by loss of Na_v1.7 currents, which is reversed by incubation with agalsidase-α and lucerastat. We provide first evidence of a direct Gb3 effect on neuronal integrity and ion channel function as potential mechanism underlying pain and small fiber pathology in FD.

Fabry disease is a life-threatening disorder that runs in families and affects many parts of the body. Symptoms begin in early childhood, often with episodes of burning pain in the hands and feet. As patients with Fabry disease grow older, sensory nerve fibers in their skin start to break down. As a result, affected individuals may often struggle to detect heat or cold against their skin.

Mutations in a gene called alpha-galactosidase A cause Fabry disease. These mutations prevent the alpha-galactosidase A (alpha-GAL) enzyme from working properly. This enzyme breaks down fatty substances in the cells, in particular a molecule named globotriaosylceramide (Gb3). In patients with Fabry disease, Gb3 accumulates inside cells and is thought to cause pain, reduced temperature sensitivity, and loss of nerve fibers in the skin. But how it does this is still unclear.

To find out more, Hofmann et al. studied mutant mice with a disrupted alpha-GAL gene, which consequently lack enzyme activity. Like patients, the mice accumulate Gb3 inside their sensory nerve cells as they age. This build-up of Gb3 damages the cells and reduces the function of ion channels (passages for charged ions to enter and leave a cell) in their membranes. This may contribute to the loss of nerve fibers and the reduced cold-warm sensitivity in Fabry patients.

However, one particular ion channel is more abundant in elderly mutant mice than in normal animals. This channel, called TRPV1, responds to high temperatures and also to capsaicin, the chemical that makes chilli peppers hot. Hofmann et al. propose that the accumulation Gb3 may be linked to the excessive activation of TRPV1 in the sensory nerve cells of patients with Fabry disease. This may in turn contribute to the heat-induced pain.

By providing insights into the mechanisms underlying some of the symptoms of Fabry disease, these findings will assist researchers to develop new treatments. They will also be useful for clinicians who manage patients with the disorder. Further studies should investigate the exact cellular mechanisms linking Gb3 accumulation with changes in cellular activity.

Generation of Fabry cardiomyopathy model for drug screening using induced pluripotent stem cell-derived cardiomyocytes from a female Fabry patient

BACKGROUND

Fabry disease is an X-linked disease caused by mutations in α-galactosidase A (GLA); these mutations result in the accumulation of its substrates, mainly globotriaosylceramide (Gb3). The accumulation of glycosphingolipids induces pathogenic changes in various organs, including the heart, and Fabry cardiomyopathy is the most frequent cause of death in patients with Fabry disease. Existing therapies to treat Fabry disease have limited efficacy, and new approaches to improve the prognosis of patients with Fabry cardiomyopathy are required.

METHODS AND RESULTS

We generated induced pluripotent stem cell (iPSC) lines from a female patient and her son. Each iPSC clone from the female patient showed either deficient or normal GLA activity, which could be used as a Fabry disease model or its isogenic control, respectively. Erosion of the inactivated X chromosome developed heterogeneously among clones, and mono-allelic expression of the GLA gene was maintained for a substantial period in a subset of iPSC clones. Gb3 accumulation was observed in iPSC-derived cardiomyocytes (iPS-CMs) from GLA activity-deficient iPSCs by mass-spectrometry and immunofluorescent staining. The expression of ANP was increased, but the cell surface area was decreased in iPS-CMs from the Fabry model, suggesting that cardiomyopathic change is ongoing at the molecular level in Fabry iPS-CMs. We also established an algorithm for selecting proper Gb3 staining that could be used for high-content analysis-based drug screening.

CONCLUSIONS

We generated a Fabry cardiomyopathy model and a drug screening system by using iPS-CMs from a female Fabry patient. Drug screening using our system may help discover new drugs that would improve the prognosis of patients with Fabry cardiomyopathy.

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.

Serum Bilirubin Levels and Promoter Variations in HMOX1 and UGT1A1 Genes in Patients with Fabry Disease

The aim of our study was to assess the possible relationships among heme oxygenase (HMOX), bilirubin UDP-glucuronosyl transferase (UGT1A1) promoter gene variations, serum bilirubin levels, and Fabry disease (FD). The study included 56 patients with FD (M : F ratio = 0.65) and 185 healthy individuals. Complete standard laboratory and clinical work-up was performed on all subjects, together with the determination of total peroxyl radical-scavenging capacity. The (GT)n and (TA)n dinucleotide variations in the HMOX1 and UGT1A1 gene promoters, respectively, were determined by DNA fragment analysis. Compared to controls, patients with FD had substantially lower serum bilirubin levels (12.0 versus 8.85 μmol/L, p = 0.003) and also total antioxidant capacity (p < 0.05), which showed a close positive relationship with serum bilirubin levels (p = 0.067) and the use of enzyme replacement therapy (p = 0.036). There was no association between HMOX1 gene promoter polymorphism and manifestation of FD. However, the presence of the TA₇ allele UGT1A1 gene promoter, responsible for higher systemic bilirubin levels, was associated with a twofold lower risk of manifestation of FD (OR = 0.51, 95% CI = 0.27-0.97, p = 0.038). Markedly lower serum bilirubin levels in FD patients seem to be due to bilirubin consumption during increased oxidative stress, although UGT1A1 promoter gene polymorphism may modify the manifestation of FD as well.

The pathophysiology of Fabry disease

Fabry disease is a lysosomal condition with systemic clinical expression, caused by the tissue deposit of globotriaosylceramide, due to a deficit in its degradation. As with most lysosomal diseases, the presence of a mutation in a gene does not explain the pathophysiological disorders shown by patients. We conducted a comprehensive review of the pathogenic mechanisms that occur in Fabry disease.

Regulation of Chemokine Function: The Roles of GAG-Binding and Post-Translational Nitration

The primary function of chemokines is to direct the migration of leukocytes to the site of injury during inflammation. The effects of chemokines are modulated by several means, including binding to G-protein coupled receptors (GPCRs), binding to glycosaminoglycans (GAGs), and through post-translational modifications (PTMs). GAGs, present on cell surfaces, bind chemokines released in response to injury. Chemokines bind leukocytes via their GPCRs, which directs migration and contributes to local inflammation. Studies have shown that GAGs or GAG-binding peptides can be used to interfere with chemokine binding and reduce leukocyte recruitment. Post-translational modifications of chemokines, such as nitration, which occurs due to the production of reactive species during oxidative stress, can also alter their biological activity. This review describes the regulation of chemokine function by GAG-binding ability and by post-translational nitration. These are both aspects of chemokine biology that could be targeted if the therapeutic potential of chemokines, like CXCL8, to modulate inflammation is to be realised.

Evolution of cardiac pathology in classic Fabry disease: Progressive cardiomyocyte enlargement leads to increased cell death and fibrosis, and correlates with severity of ventricular hypertrophy‬‬‬‬‬‬‬‬

BACKGROUND

Fabry disease, an X-linked lysosomal storage disease, results from deficient α-galactosidase A (α-GalA) activity and the systemic accumulation of α-galactosyl-terminated glycosphingolipids. Two major phenotypes, "Classic" and "Later-Onset", lead to renal failure, and/or cardiac disease, and early demise. To date, the evolution and progression of the cardiac pathology and resultant clinical manifestations in family members of phenotype have not been well characterized.

METHODS AND RESULTS

In a Classic family with nine affected members (GLA mutation c.983delG), cardiac imaging, angiography, and cardiac biopsies were performed in four males and two heterozygous females. Tissues were examined histologically, ultrastructurally, and myocardial necrosis and apoptosis were evaluated by in situ ligation with hairpin probes. Increasing cardiac pathology correlated with ECG and cardiac magnetic resonance findings. Young affected males with "pre-hypertrophy" had 18-20μm cardiomyocyte diameters, <30% vacuolar areas in myocytes, and normal levels of necrosis and apoptosis. Patients with "moderate hypertrophy" (maximal wall thickness (MWT) ≤16mm) had 30-35μm cardiomyocyte diameters, ~45% vacuolar areas, and moderate levels of necrosis and apoptosis. In contrast, the oldest male with severe hypertrophy (MWT=21mm) had 38-40μm cell diameters, >60% vacuolar areas, and marked necrosis and apoptosis.

CONCLUSION

Progressive gender-specific cardiac pathology and clinical manifestations were documented in affected Classic family members. Increasing cardiomyocyte diameter was correlated with disease severity, age, and gender. Fibrosis was presumably caused by cell death of enlarged, substrate-engorged cardiomyocytes. These results support early enzyme therapy in Classic males to prevent/minimize irreversible cardiac damage.

Tetrahydrobiopterin deficiency in the pathogenesis of Fabry disease

Fabry disease is caused by deficient activity of α-galactosidase A and subsequent accumulation of glycosphingolipids (mainly globotriaosylceramide, Gb3), leading to multisystem organ dysfunction. Oxidative stress and nitric oxide synthase (NOS) uncoupling are thought to contribute to Fabry cardiovascular diseases. We hypothesized that decreased tetrahydrobiopterin (BH4) plays a role in the pathogenesis of Fabry disease. We found that BH4 was decreased in the heart and kidney but not in the liver and aorta of Fabry mice. BH4 was also decreased in the plasma of female Fabry patients, which was not corrected by enzyme replacement therapy (ERT). Gb3 levels were inversely correlated with BH4 levels in animal tissues and cultured patient cells. To investigate the role of BH4 deficiency in disease phenotypes, 12-month-old Fabry mice were treated with gene transfer-mediated ERT or substrate reduction therapy (SRT) for 6 months. In the Fabry mice receiving SRT but not ERT, BH4 deficiency was restored, concomitant with ameliorated cardiac and renal hypertrophy. Additionally, glutathione levels were decreased in Fabry mouse tissues in a sex-dependent manner. Renal BH4 levels were closely correlated with glutathione levels and inversely correlated with cardiac and kidney weight. In conclusion, this study showed that BH4 deficiency occurs in Fabry disease and may contribute to the pathogenesis of the disease through oxidative stress associated with a reduced antioxidant capacity of cells and NOS uncoupling. This study also suggested dissimilar efficacy of ERT and SRT in correcting pre-existing pathologies in Fabry disease.

Fabry disease: A fundamental genetic modifier of cardiac function

Fabry disease (FD) is an inherited X-linked metabolic storage disorder triggered by abnormalities in the GLA gene at Xq22, which leads to a deficiency in α-galactosidase A and massive accumulation of intralysosomal glycosphingolipids. Cardiac complications are very common in FD and are the main cause of late morbidity, as well as early mortality in both hemizygous men and heterozygous women. There is a need for a multidisciplinary approach to evaluation and management of FD patients as there is a wide range of presentation of FD, which varies with mutation and other organ involvement/dysfunction. An overview of common cardiac involvement and clinical characteristics in FD including: left ventricular hypertrophy (LVH), conduction abnormalities and arrhythmias, coronary artery disease and valvular infiltrative myopathy are provided in this review. Current therapeutic approaches such as enzyme replacement therapy as well as the emergence of novel therapeutic options such as gene therapy to optimize disease outcomes in FD patients will be highlighted in this paper.

Fabry Disease: A Disorder of Childhood Onset

BACKGROUND

Fabry disease, an X-linked disorder of glycosphingolipids, markedly increases the risk of systemic vasculopathy, ischemic stroke, small-fiber peripheral neuropathy, cardiac dysfunction, and chronic kidney disease.

METHODS

We performed an extensive PubMed search on the topic of Fabry disease and drew from our cumulative 43 years of experience.

RESULTS

Most of these complications are nonspecific in nature and clinically indistinguishable from similar abnormalities that occur in the context of more common disorders in the general population. This disease is caused by variants of the GLA gene, and its incidence may have been underestimated. However, one must also guard against overdiagnosis of Fabry disease and unjustified enzyme replacement therapy, because some of the gene variants are benign. Specific therapy for Fabry disease has been developed in the last few years, but its clinical effect has been modest. Novel therapeutic agents are being developed. Standard "nonspecific" medical and surgical therapy is necessary and effective in slowing deterioration or compensating for organ failure in patients with Fabry disease.

CONCLUSIONS

Fabry disease is a treatable and modifiable genetic risk factor for a myriad of clinical organ complications. Fabry disease may be frequently overlooked but on occasion overdiagnosed.

[Association of Inorganics Accumulation with the Activation of NF-κB Signaling Pathway and the iNOS Expression of Lung Tissue in Xuanwei Lung Cancer Patients]

背景与目的

室内空气污染不仅会诱发哮喘，也会导致慢性阻塞性肺疾病(chronic obstructive pulmonary disease, COPD)，甚至促进肺癌发生。随着宣威肺癌的病因学研究，发现室内空气污染最终造成肺部无机颗粒物的沉积，这些物质可以造成肺泡细胞损伤、信号通路激活，最终促进肿瘤的发生。本研究旨在探讨宣威肺癌患者肺部中无机杂质的赋存以及核转录因子(nuclear factor κB, NF-κB) -诱导型一氧化氮合成酶(inducible nitric oxide synthase, iNOS)信号通路的激活情况。

方法

选取48例2013年12月-2014年11月在昆明医科大学第三附属医院行手术治疗的宣威肺癌患者与其他地区的肺癌患者作为研究对象，用透射电镜(transmission electron microscope, TME)对患者术后标本进行超微结构的观察，探究无机颗粒物的赋存情况；对患者的血清行细胞因子检测；对术后的标本行免疫组化以及蛋白质印迹(Western blot)，了解NF-κB-p65蛋白以及iNOS蛋白的表达；对肺癌组织中和尿液中的8-OHdG赋存进行检测。

结果

在宣威肺癌患者癌旁组织的肺泡Ⅱ型细胞、巨噬细胞中可见到大量纳米级无机物赋存；对无机物进行元素分析，含有硅(Silicon, Si)成分；宣威地区患者血清中白介素(interleukin, IL) -1β(31.50±19.16) pg/mL较其他地区肺癌患者(11.33±6.94) pg/mL高，差异有统计学意义(P < 0.01)；宣威肺癌与其他地区肺癌患者的术后病理组织中癌组织有NF-κB-p65和iNOS表达，较非宣威地区明显升高；癌旁和正常组织之间未见明显差异；宣威肺癌组织和尿液8-OHdG较非宣威地区肺癌患者高，肺癌患者尿液中的8-OhdG(40.124±8.597) ng/mgCr与其他地区患者(25.673±7.986) ng/mgCr相比，差异有统计学意义(P < 0.05)。

结论

肺部无机物的赋存以及NF-κB-iNOS信号通路的激活可能促进了宣威肺癌的发生。

Electrocardiographic Changes and Arrhythmia in Fabry Disease

Fabry disease is an X-chromosome-linked lysosomal storage disease characterized by a deficient activity or, in most males, absence of the enzyme α-galactosidase A (a-Gal A) leading to systemic, primary lysosomal accumulation of globotriaosylceramide (Gb3) (1). Recent literature refers to an overall birth prevalence of 1:40,000–170,000; however, such data do not allow an estimation on an actual patient number suffering from Fabry disease (2). Multisystem morbidity commonly develops in childhood and, with progression of the disease, life-threatening complications often occur in adulthood, including renal failure, cardiovascular dysfunction, neuropathy, and stroke (3–6). Life expectancy is reduced by an average of 15 years in female patients and 20 years in male patients (7, 8). The pathognomonic Gb3 accumulation has been repeatedly observed over the past decades by many groups in vascular endothelial and smooth muscle cells, cardiomyocytes, cardiac conduction tissue, and valvular fibroblasts (3). Although incompletely described, it is likely that inflammatory and neurohormonal mechanisms are involved in subsequent cellular and vascular dysfunction, leading to tissue ischemia, hypertrophy, and fibrosis (9). Furthermore, recently published works on cardiomyocyte dysfunction and conduction tissue involvement have suggested that cardiac dysfunction may reflect increased myocardial nitric oxide production with oxidative damage of cardiomyocyte myofilaments and DNA, causing cell dysfunction and death, and accelerated conduction with prolonged refractoriness and electric instability (10, 11).