Fabry disease: where are we now?

Targeting strategies with lipid vectors for nucleic acid supplementation therapy in Fabry disease: a systematic review

Fabry disease (FD) results from a lack of activity of the lysosomal enzyme α-Galactosidase A (α-Gal A), leading to the accumulation of glycosphingolipids in several different cell types. Protein supplementation by pDNA or mRNA delivery presents a promising strategy to tackle the underlying genetic defect in FD. Protein-coding nucleic acids in FD can be either delivered to the most affected sites by the disease, including heart, kidney and brain, or to specialized organs that can act as a production factory of the enzyme, such as the liver. Lipid-based systems are currently at the top of the ranking of non-viral nucleic acid delivery systems, and their versatility allows the linking to the surface of a wide range of molecules to control their biodistribution after intravenous administration. This systematic review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement guidelines and provides an overview and discussion of the targeting ligands that have been employed so far to actively vectorize intravenously administered non-viral vectors based on lipid carriers to clinically relevant organs in the treatment of FD, for protein-coding nucleic acid (pDNA and mRNA) supplementation. Among the thirty-two studies included, the majority focus on targeting the liver and brain. The targeting of the heart has been reported to a lesser degree, whereas no articles addressing kidney-targeting have been recorded. Although a great effort has been made to develop organ-specific nucleic acid delivery systems, the design of active-targeted carriers with high quality, good clinical translation, and large-scale manufacturing capacity is still challenging.

Be aware of childhood stroke: Proceedings from EPNS Webinar

Childhood arterial ischaemic stroke (AIS) is a significant health concern with increasing incidence. This review aims to provide an overview of the current understanding of childhood AIS. The incidence of childhood AIS is on the rise especially in developing countries, likely due to improved awareness and diagnostic capabilities. Aetiology of childhood AIS is multifactorial, with both modifiable risk factors and genetic predisposition playing important roles. Identifying and addressing these risk factors, such as infection, sickle cell disease, and congenital heart defects, is essential in prevention and management. Identifying underlying conditions through genetic testing is important for appropriate management and long-term prognosis. Clinically, distinguishing stroke from stroke mimics can be challenging. Awareness of important stroke mimics, including migraines, seizures, and metabolic disorders, is crucial to avoid misdiagnosis and ensure appropriate treatment. The diagnostic approach to childhood AIS involves a comprehensive "chain of care," including initial assessment, neuroimaging, and laboratory investigations. National guidelines play a pivotal role in standardizing and streamlining the diagnostic process, ensuring prompt and accurate management. Early intervention is critical in the management of childhood AIS. Due to the critical time window, the question if mechanical thrombectomy is feasible and beneficial should be addressed as fast as possible. Early initiation of antiplatelet or anticoagulation therapy and, in select cases, thrombolysis can help restore blood flow and minimize long-term neurological damage. Additionally, rehabilitation should start as soon as possible to optimize recovery and improve functional outcomes. In conclusion, childhood AIS is a growing concern. Understanding the increasing incidence, age distribution, risk factors, clinical presentation, diagnostic approach, and management strategies is crucial for optimized management of these patients.

Is just enzyme replacement therapy enough for Fabry disease treatment? Have we missed a trick?

BACKGROUND AND AIM

In Fabry disease (FD), primary factors such as glycosphingolipid deposition that initiate kidney damage and secondary factors that advance kidney damage to fibrosis are different. Periostin is a molecule of proven importance in renal inflammation and fibrosis. It was previously shown that periostin plays an essential role in the process leading to renal fibrosis and its expression is increased in many kidney diseases. In the present study, we aimed to reveal the relationship between periostin and Fabry nephropathy.

MATERIAL-METHOD

This cross-sectional study included 18 FD patients (10 males, 8 females) with enzyme replacement therapy (ERT) indications and 22 healthy control patients of similar age and gender. At the time of diagnosis, plasma alpha-galactosidase A (α-gal-A) and globotriaosylsphingosine (lyso-Gb3), proteinuria, and kidney function tests of all FD patients before ERT were scanned from the hospital system. Periostin was studied from serum samples collected and stored before ERT. Parameters related to serum periostin levels in Fabry disease were investigated.

RESULTS

In FD patients, serum periostin was negatively correlated with age of first symptom and GFR; and positively correlated with proteinuria and lyso-Gb3. In regression analysis, we found that serum periostin was the only independent determinant of proteinuria in patients with Fabry disease. The serum periostin levels were significantly lower in patients with low proteinuria, and the serum periostin levels were correlated with proteinuria.

DISCUSSION

Periostin may be a valuable marker of Fabry nephropathy and proteinuria. Periostin seems to be one of the molecules that may have an important role in the management of the fibrotic process in Fabry nephropathy. We think that the role of periostin among these mechanisms is worth investigating. In addition to standard ERTs, periostin-reducing therapies may contribute to better kidney survival in Fabry disease. Progressive fibrosis processes caused by periostin in patients with Fabry disease are still a hidden issue waiting to be clarified. Progressive fibrosis processes caused by periostin in Fabry patients are still a hidden issue waiting to be clarified.

Lysosomal Dysfunction: Connecting the Dots in the Landscape of Human Diseases

Lysosomes are the main organelles responsible for the degradation of macromolecules in eukaryotic cells. Beyond their fundamental role in degradation, lysosomes are involved in different physiological processes such as autophagy, nutrient sensing, and intracellular signaling. In some circumstances, lysosomal abnormalities underlie several human pathologies with different etiologies known as known as lysosomal storage disorders (LSDs). These disorders can result from deficiencies in primary lysosomal enzymes, dysfunction of lysosomal enzyme activators, alterations in modifiers that impact lysosomal function, or changes in membrane-associated proteins, among other factors. The clinical phenotype observed in affected patients hinges on the type and location of the accumulating substrate, influenced by genetic mutations and residual enzyme activity. In this context, the scientific community is dedicated to exploring potential therapeutic approaches, striving not only to extend lifespan but also to enhance the overall quality of life for individuals afflicted with LSDs. This review provides insights into lysosomal dysfunction from a molecular perspective, particularly in the context of human diseases, and highlights recent advancements and breakthroughs in this field.

Prevalence of Fabry disease in patients with chronic kidney disease: A systematic review and meta-analysis

Fabry disease (FD) is an X-linked lysosomal storage disease caused by pathogenic variants in the GLA gene. It has a wide range of clinical manifestations, typically related to the specific underlying GLA variant. One of the main features of FD is kidney involvement; therefore, several studies have addressed the prevalence of FD in all types of patients with chronic kidney disease. We performed a systematic review and meta-analysis of screening studies in chronic kidney disease patients, including those on dialysis, had undergone a kidney transplantation, and those who did not receive kidney replacement therapy, and assessed the prevalence of pathogenic variants in these cohorts. Fifty-five studies were included, involving a total of 84,062 individuals. Of these, 251 cases were positive for FD; a third of the reported GLA variants were of a benign phenotype (37.8%), followed by classical phenotype (31.7%), late onset (15.5%), and of uncertain significance (14.7%). The overall prevalence among dialysis patients was 0.10% (CI95%, 0.06-0.15), 0.28% (CI95%, 0.06-0.15) among patients with kidney transplantation, and 0.17% (CI95%, 0.11-0.39) among those without kidney replacement therapy. Although the overall prevalence of FD is low in patients with kidney involvement, screening, especially in patients who have not yet undergone kidney replacement therapy, is important, in order to provide timely and effective treatment interventions, including disease modifying therapies. The prevalence of kidney involvement in females with Fabry Disease is lower but this should not lead to inadequate follow up. Further research is also needed on the impact of genetic variants of uncertain significance to elucidate their role in Fabry disease.

Thiol/disulfide homeostasis as a new oxidative stress marker in patients with Fabry disease

This is the first study to show both dynamic thiol-disulfide balance and oxidative stress levels in patients with Fabry disease (FD). This prospective study consists of 30 FD patients and 30 healthy controls. Thiol and disulfide values of the study groups were evaluated using a new, cost-effective and fully automatic colorimetric method. A total of 60 subjects were included in the study. A statistically significant difference was found between the patient and control groups for native and total thiol levels (p < 0.001). In addition, disulfide levels were significantly higher in FD patients compared with the control group (p < 0.003). Native thiol levels showed significantly negative correlation with lysosomal globotriaosylceramide, total oxidant status (TOS), and oxidative stress index (OSI) levels. In addition, a positive correlation was found between disulfide/natural thiol and disulfide/total thiol ratios and TOS, OSI, and blood urea nitrogen. We found total antioxidant status levels were lower in the patient group compared to the control group, while TOS and OSI levels were higher and were statistically significant. This study highlights for the first time a novel, cost-effective and fully automated measurement of thiol-disulfide levels in patients with FD. Determination of thiol levels can make important contributions to understand the etiopathogenesis and follow-up of the disease in FD patients.

Fabry disease and sleep disorders: a systematic review

Background

Fabry disease (FD) is an X-chromosome-linked disorder characterized by a reduced or complete absence of the enzyme α-galactosidase, resulting in the accumulation of lysosomal globotriaosylceramide. Despite the presence of these deposits in multiple organs, the problem of sleep disorders within this population has very rarely been documented.

Objective

This study aimed to investigate the types and prevalence of sleep disorders among patients with FD.

Methods

Screening of the following medical databases using key terms was performed on 10 February 2023: PubMed, Scopus, and Embase. A total of 136 records were identified. The quality assessment of the studies was conducted by using tools from the National Institutes of Health (NIH) and critical appraisal tools from the Joanna Briggs Institute (JBI).

Results

The study included nine studies on sleep disorders in patients with FD. The overall quality of the majority of these studies was assessed as either poor or fair. Among 330 patients, there was a slightly higher representation of female patients (56%). Sleep problems manifested 4-5 years after the onset of FD and sometimes even after 10-11 years. Genotypes of disease associated with sleep problems were rarely described. Within the FD population, the most commonly reported conditions were excessive daytime sleepiness (EDS) as well as obstructive and central sleep apnea (OSA, CSA). However, EDS occurred more frequently in FD patients, while the prevalence of OSA and CSA was within the ranges observed in the general population. The studies included indicated a lack of association between organ impairment by primary disease and EDS and OSA. The effectiveness of enzyme replacement therapy (ERT) in treating sleep disorders was not demonstrated.

Conclusion

The findings of this report revealed the presence of many sleep-related disorders within the FD population. However, very few studies on this subject are available, and their limited results make it difficult to truly assess the real extent of the prevalence of sleep disturbances among these individuals. There is a need to conduct further studies on this topic, involving a larger group of patients. It is important to note that there are no guidelines available for the treatment of sleep disorders in patients with FD.

Zebra-Sphinx: Modeling Sphingolipidoses in Zebrafish

Sphingolipidoses are inborn errors of metabolism due to the pathogenic mutation of genes that encode for lysosomal enzymes, transporters, or enzyme cofactors that participate in the sphingolipid catabolism. They represent a subgroup of lysosomal storage diseases characterized by the gradual lysosomal accumulation of the substrate(s) of the defective proteins. The clinical presentation of patients affected by sphingolipid storage disorders ranges from a mild progression for some juvenile- or adult-onset forms to severe/fatal infantile forms. Despite significant therapeutic achievements, novel strategies are required at basic, clinical, and translational levels to improve patient outcomes. On these bases, the development of in vivo models is crucial for a better understanding of the pathogenesis of sphingolipidoses and for the development of efficacious therapeutic strategies. The teleost zebrafish (Danio rerio) has emerged as a useful platform to model several human genetic diseases owing to the high grade of genome conservation between human and zebrafish, combined with precise genome editing and the ease of manipulation. In addition, lipidomic studies have allowed the identification in zebrafish of all of the main classes of lipids present in mammals, supporting the possibility to model diseases of the lipidic metabolism in this animal species with the advantage of using mammalian lipid databases for data processing. This review highlights the use of zebrafish as an innovative model system to gain novel insights into the pathogenesis of sphingolipidoses, with possible implications for the identification of more efficacious therapeutic approaches.

Could immune cells be associated with nephropathy in Fabry disease patients?

BACKGROUND

In Fabry Disease (FD), although the primary factor initiating kidney damage is glycosphingolipid accumulation, secondary conditions such as increased inflammation and fibrosis may cause this damage to progress. These processes may be induced by immune cells. Therefore, we aimed to investigate the peripheral lymphocyte subgroup analysis of the patients with FD and compare these results with healthy individuals. In addition, we performed T, B, NK, and plasma cell analyses in kidney biopsy materials and compared these kidney biopsy results with the biopsy results of patients whose kidney functions were impaired after 4 years of regular ERT.

MATERIALS AND METHODS

18 FD and 16 healthy individuals were included in the study. T-B lymphocyte and NK-cell populations were determined. We performed kidney biopsies (KBx) on 13 patients with FD prior to ERT. Of these, 4 patients had rebiopsy after 4 years of regular ERT. Immunohistochemical staining was performed to define immune cell infiltration.

RESULTS

There was no statistically significant difference in terms of total, helper and cytotoxic T-lymphocyte and CD3^-CD16⁺CD56⁺ natural killer (NK)-cell count (p = 0.20; p = 0.12; p = 0.76; p = 0.75, respectively).According to KBx findings prior to ERT, all patients had interstitial fibrosis (IF), podocyte vacuoles (PV), and podocyte inclusion (PI), CD3, CD4, CD8, CD16, and CD56 positivity at different levels. None of the patients had CD19, CD20, and CD138 positivity at the first biopsies. When we compared the first and the second KBx results of the two progressors, we also demonstrated that CD3⁺4⁺T-cells infiltration remained the same, whereas CD8⁺T cells, CD16⁺ and 56⁺NK-cells infiltration were significantly decreased. In contrast, CD20⁺B cells and CD138⁺plasma cell infiltration were significantly increased despite 4 years of ERT (15 fold and sixfold, respectively). The CD20⁺B and CD138⁺ plasma cells and IF were positively correlated with proteinuria.

CONCLUSIONS

The progression of FD nephropathy and proteinuria is increased despite a long-term ERT. Immune cells, primarily B and plasma cells, might cause these unwanted consequences.

Clinical features and enzyme replacement therapy in 10 children with Fabry disease

OBJECTIVE

To summarize the clinical features, diagnosis and enzyme replacement therapy(ERT) of Fabry disease (FD) in children.

METHODS

The clinical data, laboratory tests, genetic variations and treatment of 10 FD children diagnosed in Shandong Provincial Hospital from September 2020 to June 2022 were retrospectively analyzed.

RESULTS

Among the 10 cases from 6 families, 7 patients were boys of 4 to 13 years of age, and 3 were girls of 12 to 15 years of age. There were 7 symptomatic patients, including 6 boys and 1 girl. All 7 patients presented with acral neuralgia. Five patients had little or no sweating. Five patients presented with cutaneous angiokeratoma. Two patients had abdominal pain. One patient developed joint symptoms. Four patients had corneal opacity. One patient had hearing loss; one patient had short stature. One patient had mild proteinuria and 1 patient had dysplasia of the right kidney with decreased eGFR (55.28 ml/min.1.73 m²). The left ventricular mass index was slightly elevated in 1 patient. Three patients had mild obstructive ventilatory dysfunction; a small amount of effusion in the intestinal space of the lower abdomen or mild fatty liver was found in 2 patients. Partial empty sella turcica in 1 patient. A total of 6 GLA gene variants were detected in 10 children, among which C.1059_1061delGAT (p.met353del) was a newly discovered mutation. Five children received ERT, of which 4 were treated with agalsidase beta and 1 was treated with agalsidase alpha. Only 1 patient had anaphylaxis. Lyso-GL-3 levels decreased significantly in the first 3 months of ERT initiation and remained relatively stable thereafter in 3 patients. The Lyso-GL-3 level was decreased, but renal impairment continued to progress in 1 patient treated with agalsidase alpha.

CONCLUSION

The clinical manifestations of FD in childhood are diverse, and it is necessary to make a definite diagnosis by combining family history, enzyme activity, biomarkers, gene testing and other indicators. Pedigree screening and high-risk population screening are helpful for early identification, early diagnosis and early treatment. No serious adverse reactions were found during the short-term treatment with agalsidase alpha and beta.

Chronic Kidney Disease: Strategies to Retard Progression

Chronic kidney disease (CKD), defined as the presence of irreversible structural or functional kidney damages, increases the risk of poor outcomes due to its association with multiple complications, including altered mineral metabolism, anemia, metabolic acidosis, and increased cardiovascular events. The mainstay of treatments for CKD lies in the prevention of the development and progression of CKD as well as its complications. Due to the heterogeneous origins and the uncertainty in the pathogenesis of CKD, efficacious therapies for CKD remain challenging. In this review, we focus on the following four themes: first, a summary of the known factors that contribute to CKD development and progression, with an emphasis on avoiding acute kidney injury (AKI); second, an etiology-based treatment strategy for retarding CKD, including the approaches for the common and under-recognized ones; and third, the recommended approaches for ameliorating CKD complications, and the final section discusses the novel agents for counteracting CKD progression.

Galactose in human metabolism, glycosylation and congenital metabolic diseases: Time for a closer look

Galactose is an essential carbohydrate for cellular metabolism, as it contributes to energy production and storage in several human tissues while also being a precursor for glycosylation. Galactosylated glycoconjugates, such as glycoproteins, keratan sulfate-containing proteoglycans and glycolipids, exert a plethora of biological functions, including structural support, cellular adhesion, intracellular signaling and many more. The biological relevance of galactose is further entailed by the number of pathogenic conditions consequent to defects in galactosylation and galactose homeostasis. The growing number of rare congenital disorders involving galactose along with its recent therapeutical applications are drawing increasing attention to galactose metabolism. In this review, we aim to draw a comprehensive overview of the biological functions of galactose in human cells, including its metabolism and its role in glycosylation, and to provide a systematic description of all known congenital metabolic disorders resulting from alterations of its homeostasis.

Altered pupillary light responses are associated with the severity of autonomic symptoms in patients with Fabry disease

Symptoms of autonomic dysfunction are common in Fabry disease. In this study we aimed to evaluate alterations in the pupillary response to white light stimulation in patients with Fabry disease and their association with the severity of autonomic symptoms. Fourteen consecutive patients with Fabry disease and 14 healthy control participants were enrolled in this cross-sectional study. The Mainz Severity Score Index (MSSI) was used to measure the severity of Fabry disease and the Composite Autonomic Symptom Scale 31 (COMPASS 31) questionnaire was used to evaluate the severity of autonomic symptoms. The pupil light responses were assessed with an infrared dynamic pupillometry unit. There were significant reductions in the amplitude (P = 0.048) and duration (P = 0.048) of pupil contraction, and the latency of pupil dilation (P = 0.048) in patients with Fabry disease compared to control subjects. The total weighted COMPASS 31 score correlated with MSSI (r = 0.592; P = 0.026) and the duration of pupil dilation (ρ = 0.561; P = 0.037). The pupillomotor weighted sub-score of the COMPASS 31 correlated inversely with the duration of pupil contraction (r = − 0.600; P = 0.023) and latency of pupil dilation (ρ = − 0.541; P = 0.046), and directly with the duration of pupil dilation (ρ = 0.877; P < 0.001) and MSSI (r = 0.533; P = 0.049). In conclusion, abnormal pupillary function is demonstrated in patients with Fabry disease, which is associated with the severity of autonomic symptoms.

The Interaction of Innate and Adaptive Immunity and Stabilization of Mast Cell Activation in Management of Infusion Related Reactions in Patients with Fabry Disease

Fabry disease (FD) is an X-linked lysosomal disorder caused by mutations in GLA gene resulting in lack of or faulty α-galactosidase A (α-GalA) enzyme. Enzyme replacement therapy (ERT) with recombinant human α-GalA enzyme (agalsidase) is the standard treatment option for FD. Infusion-related reactions (IRRs), with symptoms ranging from rigors, to fever, pain, vomiting, angioedema and diarrhea, are often seen due to immune response against the exogenous enzyme. To elucidate the mechanisms causing the IRRs in FD, eight patients who developed IRRs were investigated. All, except one, tested negative for agalsidase-specific IgE and had normal tryptase levels. Circulating dendritic cells were drastically reduced during IRRs, suggesting possible sequestration to the sites of inflammation. An increase in NK cells and a decrease in T cells were also observed. Cytokines IL-4, IL-8 and TNF-α showed a significant increase, indicating nonspecific degranulation of mast cells. All IRRs were managed successfully using a combination of standard premedications and mast cell stabilizers without any interruption of therapy. Taken together, the results indicate crosstalk between immune cells resulting in IgE-independent mast-cell-specific allergic inflammation. Mast cell stabilizers could be used to control IRRs and for safe reintroduction of agalsidase in patients previously treated with ERT.