Enhanced thrombospondin-1 causes dysfunction of vascular endothelial cells derived from Fabry disease-induced pluripotent stem cells

Cracking the code of the cardiovascular enigma: hPSC-derived endothelial cells unveil the secrets of endothelial dysfunction

Endothelial dysfunction is a central contributor to the development of most cardiovascular diseases and is characterised by the reduced synthesis or bioavailability of the vasodilator nitric oxide together with other abnormalities such as inflammation, senescence, and oxidative stress. The use of patient-specific and genome-edited human pluripotent stem cell-derived endothelial cells (hPSC-ECs) has shed novel insights into the role of endothelial dysfunction in cardiovascular diseases with strong genetic components such as genetic cardiomyopathies and pulmonary arterial hypertension. However, their utility in studying complex multifactorial diseases such as atherosclerosis, metabolic syndrome and heart failure poses notable challenges. In this review, we provide an overview of the different methods used to generate and characterise hPSC-ECs before comprehensively assessing their effectiveness in cardiovascular disease modelling and high-throughput drug screening. Furthermore, we explore current obstacles that will need to be overcome to unleash the full potential of hPSC-ECs in facilitating patient-specific precision medicine. Addressing these challenges holds great promise in advancing our understanding of intricate cardiovascular diseases and in tailoring personalised therapeutic strategies.

Cardiomyocyte Globotriaosylceramide Accumulation in Adult Male Patients with Fabry Disease and IVS4 + 919G>A GLA Mutation is Progressive with Age and Correlates with Left Ventricular Hypertrophy and Reduced Left Ventricular Ejection Fraction

Background

While cardiovascular complications are the most common cause of mortality in Fabry disease, the relationship between globotriaosylceramide (GL-3) accumulation, the hallmark of Fabry cardiomyopathy, and cardiac hypertrophy has not been fully elucidated.

Methods

We developed unbiased stereology protocols to quantify the ultrastrcture of Fabry cardiomyopathy. Endomyocardial biopsies from 10 adult male enzyme replacement therapy naïve Fabry patients with IVS4 + 919G>A GLA mutation were studied. The findings were correlated with cardiac MRI and clinical data.

Results

Ultrastructural parameters showed significant relationships with key imaging and clinical and functional variables. Average cardiomyocyte volume and GL-3 volume per cardiomyocyte were progressively increased with age. Eighty-four percent of left ventricular mass index (LVMI) variability was explained by cardiomyocyte nuclear volume, age and plasma globotriaosylsphingosine with cardiomyocyte nuclear volume being the only independent predictor of LVMI. Septal thickness was directly and left ventricular ejection fraction (LVEF) was inversely correlated with cardiomyocyte GL-3 accumulation. Sixty-five percent of left ventricular ejection fraction (LVEF) variability was explained by cardiomyocyte GL3 volume, serum α-galactosidase-A activity and age with cardiomyocyte GL3 volume being the only independent predictor of LVEF. Residual α-galactosidase-A activity was directly correlated with myocardial microvasculature density.

Conclusions

The unbiased stereological methods introduced in this study unraveled novel relationships between cardiomyocyte structure and important imaging and clinical parameters. These novel tools can help better understand Fabry cardiomyopathy pathophysiology.

Induced pluripotent stem cells modulate the Wnt pathway in the bleomycin-induced model of idiopathic pulmonary fibrosis

BACKGROUND

The Wnt signaling pathway has been implicated in the pathogenesis of fibrotic disorders and malignancies. Hence, we aimed to assess the potential of the induced pluripotent stem cells (IPS) in modulating the expression of the cardinal genes of the Wnt pathway in a mouse model of idiopathic pulmonary fibrosis (IPF).

METHODS

C57Bl/6 mice were randomly divided into three groups of Control, Bleomycin (BLM), and BLM + IPS; the BLM mice received intratracheal instillation of bleomycin, BLM + IPS mice received tail vein injection of IPS cells 48 h post instillation of the BLM; The Control group received Phosphate-buffered saline instead. After 3 weeks, the mice were sacrificed and Histologic assessments including hydroxy proline assay, Hematoxylin and Eosin, and Masson-trichrome staining were performed. The expression of the genes for Wnt, β-Catenin, Lef, Dkk1, and Bmp4 was assessed utilizing specific primers and SYBR green master mix.

RESULTS

Histologic assessments revealed that the fibrotic lesions and inflammation were significantly alleviated in the BLM + IPS group. Besides, the gene expression analyses demonstrated the upregulation of Wnt, β-Catenin, and LEF along with the significant downregulation of the Bmp4 and DKK1 in response to bleomycin treatment; subsequently, it was found that the treatment of the IPF mice with IPS cells results in the downregulation of the Wnt, β-Catenin, and Lef, as well as upregulation of the Dkk1, but not the Bmp4 gene (P values < 0.05).

CONCLUSION

The current study highlights the therapeutic potential of the IPS cells on the IPF mouse model in terms of regulating the aberrant expression of the factors contributing to the Wnt signaling pathway.

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.

Establishment of a TNFRSF11B knock-out human induced pluripotent stem cell line (KSCBi002-B-2) via CRISPR/Cas9 system

A TNFRSF11B (TNF Receptor Superfamily Member 11b) gene encodes a soluble decoy receptor, osteoprotegerin (OPG), which has a key role in repressing osteoclast differentiation. In this report, we generated a biallelic knock-out hiPSC line for the TNFRSF11B gene via CRISPR/Cas9. When TNFRSF11B Knock-out hiPSCs were differentiated into mesenchymal progenitor cells (MPCs), the expression level of OPG was significantly decreased compared to normal hiPSC-derived MPCs. This knock-out hiPSCs will provide a chance to study Paget disease of bone 5 (juvenile Paget disease).

From bedside to the bench: patient-specific hiPSC-EC models uncover endothelial dysfunction in genetic cardiomyopathies

Genetic cardiomyopathies are a group of inherited disorders in which myocardial structure and function are damaged. Many of these pathologies are rare and present with heterogenous phenotypes, thus personalized models are required to completely uncover their pathological mechanisms and develop valuable therapeutic strategies. Both cardiomyocytes and fibroblasts, differentiated from patient-specific human induced pluripotent stem cells, represent the most studied human cardiac cell models in the context of genetic cardiomyopathies. While endothelial dysfunction has been recognized as a possible pathogenetic mechanism, human induced pluripotent stem cell-derived endothelial cells are less studied, despite they constitute a suitable model to specifically dissect the role of the dysfunctional endothelium in the development and progression of these pathologies. In this review, we summarize the main studies in which human induced pluripotent stem cell-derived endothelial cells are used to investigate endothelial dysfunction in genetic-based cardiomyopathies to highlight new potential targets exploitable for therapeutic intervention, and we discuss novel perspectives that encourage research in this direction.

Regulation of self-renewal in ovarian cancer stem cells by fructose via chaperone-mediated autophagy

The chaperone-mediated autophagy (CMA) pathway is deregulated in different types of cancers; however, its role in cancer stem cells (CSCs) is unknown yet. Development of ovarian cancer, the most lethal gynecological type of cancer, involves the metastasis of CSCs to the abdominal cavity. This study aims to determine the role of CMA in ovarian CSCs. We found that the transcription factor EB (TFEB) and trehalose, a disaccharide that induces TFEB activation, enhance the expression of octamer-binding transcription factor 4 (OCT4) stem cell and lysosomal-associated membrane protein 2A (LAMP2A) CMA markers. However, trehalose did not increase the level of the LC3II macroautophagy marker in ovarian CSCs. In A2780 and SKOV3 ovarian CSCs, LAMP2A and heat shock protein 70 (HSC70) exhibited higher expression levels than in normal adherent cells. Our results showed that the silencing of the LAMP2A gene resulted in reduced sphere formation and enhanced GLUT5 expression in ovarian CSCs. Moreover, the treatment with fructose reduced sphere formation and enhanced the expression levels of LAMP2A, SOX2, and OCT4 in ovarian CSCs. The KEGG functional analysis revealed that differentially expressed genes were enriched in the ferroptosis pathway in A2780-spheroid (SP) cells after treatment with fructose. In A2780-SP and SKOV3-SP cells, the level of SLC7A11 decreased whereas FTH increased after treatment with fructose. Taken together, our results suggest that CMA is mediated in CSCs via fructose metabolism.

Fasudil alleviates the vascular endothelial dysfunction and several phenotypes of Fabry disease

Fabry disease (FD), a lysosomal storage disorder, is caused by defective α-galactosidase (GLA) activity, which results in the accumulation of globotriaosylceramide (Gb3) in endothelial cells and leads to life-threatening complications such as left ventricular hypertrophy (LVH), renal failure, and stroke. Enzyme replacement therapy (ERT) results in Gb3 clearance; however, because of a short half-life in the body and the high immunogenicity of FD patients, ERT has a limited therapeutic effect, particularly in patients with late-onset disease or progressive complications. Because vascular endothelial cells (VECs) derived from FD-induced pluripotent stem cells display increased thrombospondin-1 (TSP1) expression and enhanced SMAD2 signaling, we screened for chemical compounds that could downregulate TSP1 and SMAD2 signaling. Fasudil reduced the levels of p-SMAD2 and TSP1 in FD-VECs and increased the expression of angiogenic factors. Furthermore, fasudil downregulated the endothelial-to-mesenchymal transition (EndMT) and mitochondrial function of FD-VECs. Oral administration of fasudil to FD mice alleviated several FD phenotypes, including LVH, renal fibrosis, anhidrosis, and heat insensitivity. Our findings demonstrate that fasudil is a novel candidate for FD therapy.

CRISPR/Cas9-mediated A4GALT suppression rescues Fabry disease phenotypes in a kidney organoid model

The objective of this study was to investigate whether CRISPR/Cas9-mediated suppression of A4GALT could rescue phenotype of Fabry disease nephropathy (FDN) using human induced pluripotent stem cells (hiPSCs) derived kidney organoid system. We generated FDN patient-derived hiPSC (CMC-Fb-002) and FD-specific hiPSCs (GLA-KO) by knock-out (KO) of GLA in wild-type (WT) hiPSCs using CRISPR/Cas9. We then performed A4GALT KO in both CMC-Fb-002 and GLA-KO to make Fb-002-A4GALT-KO and GLA/A4GALT-KO, respectively. Using these hiPSCs, we generated kidney organoids and compared alpha-galactosidase-A enzyme (α-GalA) activity, globotriaosylceramide (Gb-3) deposition, and zebra body formation under electron microscopy (EM). We also compared mRNA expression levels using RNA-seq and qPCR. Generated hiPSCs showed typical pluripotency markers without chromosomal disruption. Expression levels of GLA in CMC-Fb-002 and GLA-KO and expression levels of A4GALT in Fb-002-A4GALT-KO and GLA/A4GALT-KO were successfully decreased compared to those in WT-hiPSCs, respectively. Generated kidney organoids using these hiPSCs expressed typical nephron markers. In CMC-Fb-002 and GLA-KO organoids, α-GalA activity was significantly decreased along with increased deposition of Gb-3 in comparison with WT organoids. Intralysosomal inclusion body was also detected under EM. However, these disease phenotypes were rescued by KO of A4GALT in both GLA/A4GALT-KO and Fb-002-A4GALT-KO kidney organoids. RNA-seq showed increased expression levels of genes related to FDN progression in both GLA-mutant organoids compared to those in WT. Such increases were rescued in GLA/A4GALT-KO or Fb-002-A4GALT-KO organoids. CRISPR/Cas9 mediated suppression of A4GALT could rescue FDN phenotype. Hence, it can be proposed as a therapeutic approach to treat FDN.

CRISPR-Cas9-Mediated Correction of SLC12A3 Gene Mutation Rescues the Gitelman's Disease Phenotype in a Patient-Derived Kidney Organoid System

The aim of this study is to explore the possibility of modeling Gitelman's disease (GIT) with human-induced pluripotent stem cell (hiPSC)-derived kidney organoids and to test whether gene correction using CRISPR/Cas9 can rescue the disease phenotype of GIT. To model GIT, we used the hiPSC line CMCi002 (CMC-GIT-001), generated using PBMCs from GIT patients with SLC12A3 gene mutation. Using the CRISPR-Cas9 system, we corrected CMC-GIT-001 mutations and hence generated CMC-GIT-001^corr. Both hiPSCs were differentiated into kidney organoids, and we analyzed the GIT phenotype. The number of matured kidney organoids from the CMC-GIT-001^corr group was significantly higher, 3.3-fold, than that of the CMC-GIT-001 group (12.2 ± 0.7/cm² vs. 3.7 ± 0.2/cm², p < 0.05). In qRT-PCR, performed using harvested kidney organoids, relative sodium chloride cotransporter (NCCT) mRNA levels (normalized to each iPSC) were increased in the CMC-GIT-001^corr group compared with the CMC-GIT-001 group (4.1 ± 0.8 vs. 2.5 ± 0.2, p < 0.05). Consistently, immunoblot analysis revealed increased levels of NCCT protein, in addition to other tubular proteins markers, such as LTL and ECAD, in the CMC-GIT-001^corr group compared to the CMC-GIT-001 group. Furthermore, we found that increased immunoreactivity of NCCT in the CMC-GIT-001^corr group was colocalized with ECAD (a distal tubule marker) using confocal microscopy. Kidney organoids from GIT patient-derived iPSC recapitulated the Gitelman's disease phenotype, and correction of SLC12A3 mutation utilizing CRISPR-Cas9 technology provided therapeutic insight.

Generation of a CRISPR/Cas9-corrected-hiPSC line (DDLABi001-A) from Fabry disease (FD)-derived iPSCs having α-galactosidase (GLA) gene mutation (c.803_806del)

Fabry disease (FD) is a lysosomal storage disorder caused by mutations in GLA gene. Here, GLA mutation (1268fs*1 (c.803_806del)) of FD iPSCs was corrected using the CRISPR-Cas9 gene editing system. The corrected (cor) FD-iPSCs retained normal morphology, karyotype, expression of pluripotency-associated markers, trilineage differentiation potential, and GLA activity. Thus, FD(cor)-iPSCs can be used as valuable tools to study the mechanism how GLA mutation^1268fs*1 induces various pathophysiologic phenotypes in FD patients.

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.

Spatially Resolved Transcriptomes of Mammalian Kidneys Illustrate the Molecular Complexity and Interactions of Functional Nephron Segments

Available transcriptomes of the mammalian kidney provide limited information on the spatial interplay between different functional nephron structures due to the required dissociation of tissue with traditional transcriptome-based methodologies. A deeper understanding of the complexity of functional nephron structures requires a non-dissociative transcriptomics approach, such as spatial transcriptomics sequencing (ST-seq). We hypothesize that the application of ST-seq in normal mammalian kidneys will give transcriptomic insights within and across species of physiology at the functional structure level and cellular communication at the cell level. Here, we applied ST-seq in six mice and four human kidneys that were histologically absent of any overt pathology. We defined the location of specific nephron structures in the captured ST-seq datasets using three lines of evidence: pathologist's annotation, marker gene expression, and integration with public single-cell and/or single-nucleus RNA-sequencing datasets. We compared the mouse and human cortical kidney regions. In the human ST-seq datasets, we further investigated the cellular communication within glomeruli and regions of proximal tubules–peritubular capillaries by screening for co-expression of ligand–receptor gene pairs. Gene expression signatures of distinct nephron structures and microvascular regions were spatially resolved within the mouse and human ST-seq datasets. We identified 7,370 differentially expressed genes (p_adj < 0.05) distinguishing species, suggesting changes in energy production and metabolism in mouse cortical regions relative to human kidneys. Hundreds of potential ligand–receptor interactions were identified within glomeruli and regions of proximal tubules–peritubular capillaries, including known and novel interactions relevant to kidney physiology. Our application of ST-seq to normal human and murine kidneys confirms current knowledge and localization of transcripts within the kidney. Furthermore, the generated ST-seq datasets provide a valuable resource for the kidney community that can be used to inform future research into this complex organ.

Identification of dual active sites in Caenorhabditis elegans GANA-1 protein: an ortholog of the human α-GAL a and α-NAGA enzymes

Fabry disease (FD) is caused by a defective α-galactosidase A (α-GAL A) enzyme responsible for breaking down globotriaosylceramide (Gb₃). To develop affordable therapeutics, more effort is needed to obtain insights into the underlying mechanism of FD and understanding human α-GAL A structure and function in related animal models. We adopted C. elegans as a model to elucidate the sequence and 3D structure of its GANA-1 enzyme and compared it to human α-GAL A. We constructed GANA-1 3D structure by homology modelling and validated the quality of the predicted GANA-1 structure, followed by computational docking of human ligands. The GANA-1 protein shared sequence similarities up to 42.1% with the human α-GAL A in silico and had dual active sites. GANA-1 homology modelling showed that 11 out of 13 amino acids in the first active site of GANA-1 protein overlapped with the human α-GAL A active site, indicating the prospect for substrate cross-reaction. Computational molecular docking using human ligands like Gb₃ (first pocket)_, 4-nitrophenyl-α-D-galactopyranoside (second pocket), α-galactose (second pocket), and N-acetyl-D-galactosamine (second pocket) showed negative binding energy. This revealed that the ligands were able to bind within both GANA-1 active sites, mimicking the human α-GAL A and α-NAGA enzymes. We identified human compounds with adequate docking scores, predicting robust interactions with the GANA-1 active site. Our data suggested that the C. elegans GANA-1 enzyme may possess structural and functional similarities to human α-GAL A, including an intrinsic capability to metabolize Gb₃ deposits.Communicated by Ramaswamy H. Sarma.

Kidney Decellularized Extracellular Matrix Enhanced the Vascularization and Maturation of Human Kidney Organoids

Kidney organoids derived from human pluripotent stem cells (hPSCs) have extensive potential for disease modelling and regenerative medicine. However, the limited vascularization and immaturity of kidney organoids have been still remained to overcome. Extracellular matrix (ECM) can provide mechanical support and a biochemical microenvironment for cell growth and differentiation. Here in vitro methods using a kidney decellularized extracellular matrix (dECM) hydrogel to culture hPSC-derived kidney organoids, which have extensive vascular network and their own endothelial cells, are reported. Single-cell transcriptomics reveal that the vascularized kidney organoids cultured using the kidney dECM have more mature patterns of glomerular development and higher similarity to human kidney than those cultured without the kidney dECM. Differentiation of α-galactosidase A (GLA)-knock-out hPSCs generated using CRISPR/Cas9 into kidney organoids by the culture method using kidney dECM efficiently recapitulate Fabry nephropathy with vasculopathy. Transplantation of kidney organoids with kidney dECM into kidney of mouse accelerates the recruitment of endothelial cells from the host mouse kidney and maintains vascular integrity with the more organized slit diaphragm-like structures than those without kidney dECM. The kidney dECM methodology for inducing extensive vascularization and maturation of kidney organoids can be applied to studies for kidney development, disease modeling, and regenerative medicine.

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.

LRP-1 Matricellular Receptor Involvement in Triple Negative Breast Cancer Tumor Angiogenesis

Background: LRP-1 is a multifunctional scavenger receptor belonging to the LDLR family. Due to its capacity to control pericellular levels of various growth factors and proteases, LRP-1 plays a crucial role in membrane proteome dynamics, which appears decisive for tumor progression. Methods: LRP-1 involvement in a TNBC model was assessed using an RNA interference strategy in MDA-MB-231 cells. In vivo, tumorigenic and angiogenic effects of LRP-1-repressed cells were evaluated using an orthotopic xenograft model and two angiogenic assays (Matrigel^® plugs, CAM). DCE-MRI, FMT, and IHC were used to complete a tumor longitudinal follow-up and obtain morphological and functional vascular information. In vitro, HUVECs’ angiogenic potential was evaluated using a tumor secretome, subjected to a proteomic analysis to highlight LRP-1-dependant signaling pathways. Results: LRP-1 repression in MDA-MB-231 tumors led to a 60% growth delay because of, inter alia, morphological and functional vascular differences, confirmed by angiogenic models. In vitro, the LRP-1-repressed cells secretome restrained HUVECs’ angiogenic capabilities. A proteomics analysis revealed that LRP-1 supports tumor growth and angiogenesis by regulating TGF-β signaling and plasminogen/plasmin system. Conclusions: LRP-1, by its wide spectrum of interactions, emerges as an important matricellular player in the control of cancer-signaling events such as angiogenesis, by supporting tumor vascular morphology and functionality.

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.

Pathology and pathogenic pathways in fabry nephropathy

BACKGROUND

The pathophysiology of renal damage in Fabry nephropathy involves a complex biological mechanism. The intracellular deposition globotriaosylceramide (Gb3) is just the first step of the mechanism. The glycolipid deposition occurs in all renal cells (endothelial, epithelial and mesangial cells). It stimulates many biological processes, including cytokine release, epithelial-mesenchymal transdifferentiation, oxidative stress and the remodelling of vascular walls, resulting in subtle initial inflammation and eventually tissue fibrosis. It has been hypothesized that the processes activated by Gb3 deposition can subsequently progress independently of cellular deposition and that even Gb3 clearance by specific therapy cannot retard or stop these pathways.

AIM

This review aims to gather the reported evidence of these cellular alterations and the resulting histological changes. Our approach is similar to a routine study of kidney biopsy.

RESULTS

In the first part of the review, "histology" section, we describe the structures involved (glomeruli, vessels, tubules and interstitium) from a histological point of view. While in the second part, "pathogenesis" section, we present some interpretations about the implicated pathways based on the up-to-date available evidence.

Genome editing of hPSCs: Recent progress in hPSC-based disease modeling for understanding disease mechanisms

Generation of proper models for studying human genetic diseases has been hindered until recently by the scarcity of primary cell samples from genetic disease patients and inefficient genetic modification tools. However, recent advances in clustered, regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology and human induced pluripotent stem cells (hiPSCs) have provided an opportunity to explore the function of pathogenic variants and obtain gene-corrected cells for autologous cell therapy. In this chapter, we address recent applications of CRISPR/Cas9 to hiPSCs in genetic diseases, including neurodegenerative, cardiovascular, and rare diseases.

Genome editing in lysosomal disorders

Lysosomal disorders are a group of heterogenous diseases caused by mutations in genes that encode for lysosomal proteins. With exception of some cases, these disorders still lack both knowledge of disease pathogenesis and specific therapies. In this sense, genome editing arises as a technique that allows both the creation of specific cell lines, animal models and gene therapy protocols for these disorders. Here we explain the main applications of genome editing for lysosomal diseases, with examples based on the literature. The ability to rewrite the genome will be of extreme importance to study and potentially treat these rare disorders.

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.

Treatment switch in Fabry disease- a matter of dose?

BACKGROUND

Patients with Fabry disease (FD) on reduced dose of agalsidase-beta or after switch to agalsidase-alfa show a decline in chronic kidney disease epidemiology collaboration-based estimated glomerular filtration rate (eGFR) and a worsened plasma lyso-Gb3 decrease. Hence, the most effective dose is still a matter of debate.

METHODS

In this prospective observational study, we assessed end-organ damage and clinical symptoms in 78 patients who had received agalsidase-beta (1.0 mg/kg) for >1 year, which were assigned to continue this treatment (agalsidase-beta, regular-dose group, n=17); received a reduced dose of agalsidase-beta and subsequent switch to agalsidase-alfa (0.2 mg/kg) or a direct switch to 0.2 mg/kg agalsidase-alfa (switch group, n=22); or were re-switched to agalsidase-beta after receiving agalsidase-alfa for 12 months (re-switch group, n=39) with a follow-up of 88±25 months.

RESULTS

No differences for clinical events were observed for all groups. Patients within the re-switch group started with the worst eGFR values at baseline (p=0.0217). Overall, eGFR values remained stable in the regular-dose group (p=0.1052) and decreased significantly in the re-switch and switch groups (p<0.0001 and p=0.0052, respectively). However, in all groups males presented with an annual loss of eGFR by -2.9, -2.5 and -3.9 mL/min/1.73 m² (regular-dose, re-switch, switch groups, all p<0.05). In females, eGFR decreased significantly only in the re-switch group by -2.9 mL/min/1.73 m² per year (p<0.01). Lyso-Gb3 decreased in the re-switch group after a change back to agalsidase-beta (p<0.05).

CONCLUSIONS

Our data suggest that a re-switch to high dosage of agalsidase results in a better biochemical response, but not in a significant renal amelioration especially in classical males.