The lysosomal β-glucocerebrosidase strikes mitochondria: implications for Parkinson's therapeutics

Parkinson's disease (PD) is a neurodegenerative disorder primarily known for typical motor features that arise due to the loss of dopaminergic neurons in the substantia nigra. However, the precise molecular etiology of the disease is still unclear. Several cellular pathways have been linked to PD, including the autophagy-lysosome pathway (ALP), α-synuclein (α-syn) aggregation, and mitochondrial function. Interestingly, the mechanistic link between GBA1, the gene that encodes for lysosomal β-glucocerebrosidase (GCase), and PD lies in the interplay between GCase functions in the lysosome and mitochondria. GCase mutations alter mitochondria-lysosome contact sites. In the lysosome, reduced GCase activity leads to glycosphingolipid buildup, disrupting lysosomal function and autophagy, thereby triggering α-syn accumulation. Additionally, α-syn aggregates reduce GCase activity, creating a self-perpetuating cycle of lysosomal dysfunction and α-syn accumulation. GCase can also be imported into the mitochondria, where it promotes the integrity and function of mitochondrial complex I. Thus, GCase mutations that impair its normal function increase oxidative stress in mitochondria, the compartment where dopamine is oxidized. In turn, the accumulation of oxidized dopamine-adducts further impairs GCase activity, creating a second cycle of GCase dysfunction. The oxidative state triggered by GCase dysfunction can also induce mitochondrial DNA damage which, in turn, can cause dopaminergic cell death. In this review, we highlight the pivotal role of GCase in PD pathogenesis and discuss promising examples of GCase-based therapeutics such as gene and enzyme replacement therapies, small molecule chaperones, and substrate reduction therapies, among others, as potential therapeutic interventions.

Understanding the phenotypic variability in Niemann-Pick disease type C (NPC): a need for precision medicine

Niemann-Pick type C (NPC) disease is a lysosomal storage disease (LSD) characterized by the buildup of endo-lysosomal cholesterol and glycosphingolipids due to loss of function mutations in the NPC1 and NPC2 genes. NPC patients can present with a broad phenotypic spectrum, with differences at the age of onset, rate of progression, severity, organs involved, effects on the central nervous system, and even response to pharmacological treatments. This article reviews the phenotypic variation of NPC and discusses its possible causes, such as the remaining function of the defective protein, modifier genes, sex, environmental cues, and splicing factors, among others. We propose that these factors should be considered when designing or repurposing treatments for this disease. Despite its seeming complexity, this proposition is not far-fetched, considering the expanding interest in precision medicine and easier access to multi-omics technologies.

A Mouse Systems Genetics Approach Reveals Common and Uncommon Genetic Modifiers of Hepatic Lysosomal Enzyme Activities and Glycosphingolipids

Identification of genetic modulators of lysosomal enzyme activities and glycosphingolipids (GSLs) may facilitate the development of therapeutics for diseases in which they participate, including Lysosomal Storage Disorders (LSDs). To this end, we used a systems genetics approach: we measured 11 hepatic lysosomal enzymes and many of their natural substrates (GSLs), followed by modifier gene mapping by GWAS and transcriptomics associations in a panel of inbred strains. Unexpectedly, most GSLs showed no association between their levels and the enzyme activity that catabolizes them. Genomic mapping identified 30 shared predicted modifier genes between the enzymes and GSLs, which are clustered in three pathways and are associated with other diseases. Surprisingly, they are regulated by ten common transcription factors, and their majority by miRNA-340p. In conclusion, we have identified novel regulators of GSL metabolism, which may serve as therapeutic targets for LSDs and may suggest the involvement of GSL metabolism in other pathologies.

Genetic Background Matters: Population-Based Studies in Model Organisms for Translational Research

We are all similar but a bit different. These differences are partially due to variations in our genomes and are related to the heterogeneity of symptoms and responses to treatments that patients exhibit. Most animal studies are performed in one single strain with one manipulation. However, due to the lack of variability, therapies are not always reproducible when treatments are translated to humans. Panels of already sequenced organisms are valuable tools for mimicking human phenotypic heterogeneities and gene mapping. This review summarizes the current knowledge of mouse, fly, and yeast panels with insightful applications for translational research.

Identification of genetic modifiers of murine hepatic β-glucocerebrosidase activity

The acid β-glucocerebrosidase (GCase) enzyme cleaves glucosylceramide into glucose and ceramide. Loss of function variants in the gene encoding for GCase can lead to Gaucher disease and Parkinson's disease. Therapeutic strategies aimed at increasing GCase activity by targeting a modulating factor are attractive and poorly explored. To identify genetic modifiers, we measured hepatic GCase activity in 27 inbred mouse strains. A genome-wide association study (GWAS) using GCase activity as a trait identified several candidate modifier genes, including Dmrtc2 and Arhgef1 (p=2.1x10⁻⁷), and Grik5 (p=2.1x10⁻⁷). Bayesian integration of the gene mapping with transcriptomics was used to build integrative networks. The analysis uncovered additional candidate GCase regulators, highlighting modules of the acute phase response (p=1.01x10⁻⁸), acute inflammatory response (p=1.01x10⁻⁸), fatty acid beta-oxidation (p=7.43x10⁻⁵), among others. Our study revealed previously unknown candidate modulators of GCase activity, which may facilitate the design of therapies for diseases with GCase dysfunction.

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Hepatic GCase activity significantly differs among mouse strains.

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Genome-wide association study revealed putative modifier genes of GCase activity.

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Bayesian integration of multi-omics identified a regulatory network of GCase activity.

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This study may facilitate the design of therapies for diseases with GCase dysfunction.

NPC1 as a Modulator of Disease Severity and Viral Entry of SARSCoV- 2

The COVID-19 plague is hitting mankind. Several viruses, including SARS-CoV-1, MERS-CoV, EBOV, and SARS-CoV-2, use the endocytic machinery to enter the cell. Genomic variants in NPC1, which encodes for the endo-lysosomal Niemann-Pick type C1 protein, restricts the host-range of viruses in bats and susceptibility to infections in humans. Lack of NPC1 and its pharmacological suppression inhibits many viral infections including SARS-CoV-1 and Type I Feline Coronavirus Infection. Antiviral effects of NPC1-inhibiting drugs for COVID-19 treatment should be explored.

Integrin Alpha E (CD103) Limits Virus-Induced IFN-I Production in Conventional Dendritic Cells

Early and strong production of IFN-I by dendritic cells is important to control vesicular stomatitis virus (VSV), however mechanisms which explain this cell-type specific innate immune activation remain to be defined. Here, using a genome wide association study (GWAS), we identified Integrin alpha-E (Itgae, CD103) as a new regulator of antiviral IFN-I production in a mouse model of vesicular stomatitis virus (VSV) infection. CD103 was specifically expressed by splenic conventional dendritic cells (cDCs) and limited IFN-I production in these cells during VSV infection. Mechanistically, CD103 suppressed AKT phosphorylation and mTOR activation in DCs. Deficiency in CD103 accelerated early IFN-I in cDCs and prevented death in VSV infected animals. In conclusion, CD103 participates in regulation of cDC specific IFN-I induction and thereby influences immune activation after VSV infection.

Lack of Annexin A6 Exacerbates Liver Dysfunction and Reduces Lifespan of Niemann-Pick Type C Protein-Deficient Mice

Niemann-Pick type C (NPC) disease is a lysosomal storage disorder characterized by cholesterol accumulation caused by loss-of-function mutations in the Npc1 gene. NPC disease primarily affects the brain, causing neuronal damage and affecting motor coordination. In addition, considerable liver malfunction in NPC disease is common. Recently, we found that the depletion of annexin A6 (ANXA6), which is most abundant in the liver and involved in cholesterol transport, ameliorated cholesterol accumulation in Npc1 mutant cells. To evaluate the potential contribution of ANXA6 in the progression of NPC disease, double-knockout mice (Npc1^-/-/Anxa6^-/-) were generated and examined for lifespan, neurologic and hepatic functions, as well as liver histology and ultrastructure. Interestingly, lack of ANXA6 in NPC1-deficient animals did not prevent the cerebellar degeneration phenotype, but further deteriorated their compromised hepatic functions and reduced their lifespan. Moreover, livers of Npc1^-/-/Anxa6^-/- mice contained a significantly elevated number of foam cells congesting the sinusoidal space, a feature commonly associated with inflammation. We hypothesize that ANXA6 deficiency in Npc1^-/- mice not only does not reverse neurologic and motor dysfunction, but further worsens overall liver function, exacerbating hepatic failure in NPC disease.

c-Abl Inhibition Activates TFEB and Promotes Cellular Clearance in a Lysosomal Disorder

The transcription factor EB (TFEB) has emerged as a master regulator of lysosomal biogenesis, exocytosis, and autophagy, promoting the clearance of substrates stored in cells. c-Abl is a tyrosine kinase that participates in cellular signaling in physiological and pathophysiological conditions. In this study, we explored the connection between c-Abl and TFEB. Here, we show that under pharmacological and genetic c-Abl inhibition, TFEB translocates into the nucleus promoting the expression of its target genes independently of its well-known regulator, mammalian target of rapamycin complex 1. Active c-Abl induces TFEB phosphorylation on tyrosine and the inhibition of this kinase promotes lysosomal biogenesis, autophagy, and exocytosis. c-Abl inhibition in Niemann-Pick type C (NPC) models, a neurodegenerative disease characterized by cholesterol accumulation in lysosomes, promotes a cholesterol-lowering effect in a TFEB-dependent manner. Thus, c-Abl is a TFEB regulator that mediates its tyrosine phosphorylation, and the inhibition of c-Abl activates TFEB promoting cholesterol clearance in NPC models.

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c-Abl is a TFEB regulator that mediates its tyr phosphorylation

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c-Abl inhibition promotes TFEB activity independently of mTORC1

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c-Abl inhibition reduces cholesterol accumulation in NPC1 models

Finding pathogenic commonalities between Niemann-Pick type C and other lysosomal storage disorders: Opportunities for shared therapeutic interventions

Lysosomal storage disorders (LSDs) are diseases characterized by the accumulation of macromolecules in the late endocytic system and are caused by inherited defects in genes that encode mainly lysosomal enzymes or transmembrane lysosomal proteins. Niemann-Pick type C disease (NPCD), a LSD characterized by liver damage and progressive neurodegeneration that leads to early death, is caused by mutations in the genes encoding the NPC1 or NPC2 proteins. Both proteins are involved in the transport of cholesterol from the late endosomal compartment to the rest of the cell. Loss of function of these proteins causes primary cholesterol accumulation, and secondary accumulation of other lipids, such as sphingolipids, in lysosomes. Despite years of studying the genetic and molecular bases of NPCD and related-lysosomal disorders, the pathogenic mechanisms involved in these diseases are not fully understood. In this review we will summarize the pathogenic mechanisms described for NPCD and we will discuss their relevance for other LSDs with neurological components such as Niemann- Pick type A and Gaucher diseases. We will particularly focus on the activation of signaling pathways that may be common to these three pathologies with emphasis on how the intra-lysosomal accumulation of lipids leads to pathology, specifically to neurological impairments. We will show that although the primary lipid storage defect is different in these three LSDs, there is a similar secondary accumulation of metabolites and activation of signaling pathways that can lead to common pathogenic mechanisms. This analysis might help to delineate common pathological mechanisms and therapeutic targets for lysosomal storage diseases.

Rare diseases in Chile: challenges and recommendations in universal health coverage context

Rare diseases (RDs) are a large number of diverse conditions with low individual prevalence, but collectively may affect up to 3.5-5.9% of the population. They have psychosocial and economic impact on patients and societies, and are a significant problem for healthcare systems, especially for countries with limited resources. In Chile, financial protection exists for 20 known RDs through different programs that cover diagnosis and treatments. Although beneficial for a number of conditions, most RD patients are left without a proper legal structure that guarantees a financial coverage, and in a vulnerable situation. In this review, we present and analyze the main challenges of the Chilean healthcare system and legislation on RDs, and other ambits of the RD ecosystem, including patient advocacy groups and research. Finally, we propose a set of policy recommendations that includes creating a patient registry, eliciting social preferences on health and financial coverage, improving access to clinical genetic services and therapies, promoting research on RDs and establishing a Latin-American cooperation network, all aimed at promoting equitable quality healthcare access for people living with RDs.

Role of proteases in dysfunctional placental vascular remodelling in preeclampsia

Preeclampsia is a syndrome characterised by vascular dysfunction, impaired angiogenesis, and hypertension during pregnancy. Even when the precise pathophysiology of preeclampsia remains elusive, impaired vascular remodelling and placental angiogenesis in the placental villi and defective trophoblast invasion of the uterus are proposed as crucial mechanisms in this syndrome. Reduced trophoblast invasion leads to reduced uteroplacental blood flow and oxygen availability and increased oxidative stress. These phenomena trigger the release of soluble factors into the maternal and foetoplacental circulation that are responsible of the clinical features of preeclampsia. New blood vessels generation as well as vascular remodelling are mechanisms that require expression and activity of different proteases, including matrix metalloproteases, a-disintegrin and metalloproteases, and a-disintegrin and metalloprotease with thrombospondin motifs. These proteases exert proteolysis of the extracellular matrix. Additionally, cathepsins, a family of proteolytic enzymes, are primarily located in lysosomes but are also released by cells to the extracellular space. This review focuses on the role that these proteases play in the regulation of the uterine trophoblast invasion and the placental vascular remodelling associated with preeclampsia.

Is Parkinson's disease a lysosomal disorder?

Common forms of Parkinson's disease have long been described as idiopathic, with no single penetrant genetic factor capable of influencing disease aetiology. Recent genetic studies indicate a clear association of variants within several lysosomal genes as risk factors for idiopathic Parkinson's disease. The emergence of novel variants suggest that the aetiology of idiopathic Parkinson's disease may be explained by the interaction of several partially penetrant mutations that, while seemingly complex, all appear to converge on cellular clearance pathways. These newly evolving data are consistent with mechanistic studies linking α-synuclein toxicity to lysosomal abnormalities, and indicate that idiopathic Parkinson's disease resembles features of Mendelian lysosomal storage disorders at a genetic and biochemical level. These findings offer novel pathways to exploit for the development of disease-altering therapies for idiopathic Parkinson's disease that target specific components of the lysosomal system.

Modeling diseases in multiple mouse strains for precision medicine studies

The genetic basis of the phenotypic variability observed in patients can be studied in mice by generating disease models through genetic or chemical interventions in many genetic backgrounds where the clinical phenotypes can be assessed and used for genome-wide association studies (GWAS). This is particularly relevant for rare disorders, where patients sharing identical mutations can present with a wide variety of symptoms, but there are not enough number of patients to ensure statistical power of GWAS. Inbred strains are homozygous for each loci, and their single nucleotide polymorphisms catalogs are known and freely available, facilitating the bioinformatics and reducing the costs of the study, since it is not required to genotype every mouse. This kind of approach can be applied to pharmacogenomics studies as well.

The unique case of the Niemann-Pick type C cholesterol storage disorder

Niemann-Pick type C disease (NPC) is a neurovisceral lysosomal cholesterol storage disorder that arises from loss-of-f unction mutations in either the NPCI or NPC2 genes. Both genes code for proteins involved in lysosomal cholesterol efflux. NPC is often diagnosed in early childhood, with patients typically displaying cerebellar ataxia, difficulties in Unfortunately, to date, there is no curative treatment for this devastating and fatal disorder, although several symptomatic manifestations of NPC are treatable. In this review, we discuss the cell biology of the disease, clinical aspects, diagnostic approaches, and current and potential therapeutic strategies against NPC.

RIPK3 as a potential therapeutic target for Gaucher's disease

Gaucher's disease (GD), an inherited metabolic disorder caused by mutations in the glucocerebrosidase gene (GBA), is the most common lysosomal storage disease. Heterozygous mutations in GBA are a major risk factor for Parkinson's disease. GD is divided into three clinical subtypes based on the absence (type 1) or presence (types 2 and 3) of neurological signs. Type 1 GD was the first lysosomal storage disease (LSD) for which enzyme therapy became available, and although infusions of recombinant glucocerebrosidase (GCase) ameliorate the systemic effects of GD, the lack of efficacy for the neurological manifestations, along with the considerable expense and inconvenience of enzyme therapy for patients, renders the search for alternative or complementary therapies paramount. Glucosylceramide and glucosylsphingosine accumulation in the brain leads to massive neuronal loss in patients with neuronopathic GD (nGD) and in nGD mouse models. However, the mode of neuronal death is not known. Here, we show that modulating the receptor-interacting protein kinase-3 (Ripk3) pathway markedly improves neurological and systemic disease in a mouse model of GD. Notably, Ripk3 deficiency substantially improved the clinical course of GD mice, with increased survival and motor coordination and salutary effects on cerebral as well as hepatic injury.

Lysosomal storage disorders: old diseases, present and future challenges

Lysosomal storage diseases (LSDs), which are inborn errors of metabolism, encompass around 50 different inherited syndromes. Together, they have an incidence of 1/7000 newborns. LSDs are caused by deficiencies in lysosomal enzymes or transporters, resulting in intra-lysosomal buildup of under graded metabolites. Common features of LSDs include bone disease, organomegaly and central and peripheral nervous system degeneration. These diseases were first described in the 1880s. Despite more than an hundred years of study of the genetic and molecular bases of LSDs, little is known about the events that lead from intra-lysosomal accumulation to the distinctive cell dysfunction and pathology that is characteristic of each disease. This review focuses on the main historical discoveries in LSD biology, from the original descriptions of their phenotypes, to animal models, including therapeutic strategies and challenges to treat this family of devastating diseases.

Neuronal and epithelial cell rescue resolves chronic systemic inflammation in the lipid storage disorder Niemann-Pick C

Chronic systemic inflammation is thought to be a major contributor to metabolic and neurodegenerative diseases. Since inflammatory components are shared among different disorders, targeting inflammation is an attractive option for mitigating disease. To test the significance of inflammation in the lipid storage disorder (LSD) Niemann-Pick C (NPC), we deleted the macrophage inflammatory gene Mip1a/Ccl3 from NPC diseased mice. Deletion of Ccl3 had been reported to delay neuronal loss in Sandhoff LSD mice by inhibiting macrophage infiltration. For NPC mice, in contrast, deleting Ccl3 did not retard neurodegeneration and worsened the clinical outcome. Depletion of visceral tissue macrophages also did not alter central nervous system (CNS) pathology and instead increased liver injury, suggesting a limited macrophage infiltration response into the CNS and a beneficial role of macrophage activity in visceral tissue. Prevention of neuron loss or liver injury, even at late stages in the disease, was achieved through specific rescue of NPC disease in neurons or in liver epithelial cells, respectively. Local epithelial cell correction was also sufficient to reduce the macrophage-associated pathology in lung tissue. These results demonstrate that elevated inflammation and macrophage activity does not necessarily contribute to neurodegeneration and tissue injury, and LSD defects in immune cells may not preclude an appropriate inflammatory response. We conclude that inflammation remains secondary to neuronal and epithelial cell dysfunction and does not irreversibly contribute to the pathogenic cascade in NPC disease. Without further exploration of possible beneficial roles of inflammatory mediators, targeting inflammation may not be therapeutically effective at ameliorating disease severity.

Npc1 deficiency in the C57BL/6J genetic background enhances Niemann-Pick disease type C spleen pathology

Niemann-Pick type C (NPC) disease is an autosomal recessive neurovisceral lipid storage disorder. The affected genes are NPC1 and NPC2. Mutations in either gene lead to intracellular cholesterol accumulation. There are three forms of the disease, which are categorized based on the onset and severity of the disease: the infantile form, in which the liver and spleen are severely affected, the juvenile form, in which the liver and brain are affected, and the adult form, which affects the brain. In mice, a spontaneous mutation in the Npc1 gene originated in the BALB/c inbred strain mimics the juvenile form of the disease. To study the influence of genetic background on the expression of NPC disease in mice, we transferred the Npc1 mutation from the BALB/c to C57BL/6J inbred background. We found that C57BL/6J-Npc1(-/-) mice present with a much more aggressive form of the disease, including a shorter lifespan than BALB/c-Npc1(-/-) mice. Surprisingly, there was no difference in the amount of cholesterol in the brains of Npc1(-/-) mice of either mouse strain. However, Npc1(-/-) mice with the C57BL/6J genetic background showed striking spleen damage with a marked buildup of cholesterol and phospholipids at an early age, which correlated with large foamy cell clusters. In addition, C57BL/6J Npc1(-/-) mice presented red cell abnormalities and abundant ghost erythrocytes that correlated with a lower hemoglobin concentration. We also found abnormalities in white cells, such as cytoplasmic granulation and neutrophil hypersegmentation that included lymphopenia and atypias. In conclusion, Npc1 deficiency in the C57BL6/J background is associated with spleen, erythrocyte, and immune system abnormalities that lead to a reduced lifespan.

Childhood bullous pemphigoid. Clinical and immunologic features, treatment, and prognosis

A 2 1/2-month-old female infant presented with multiple tense bullae on the hands and feet. Analysis of biopsy specimens confirmed our clinical impression of childhood bullous pemphigoid. Confirmatory data included type IV collagen mapping of the basement membrane zone, a readily available technique that helps distinguish childhood bullous pemphigoid from childhood epidermolysis bullosa acquisita. To our knowledge, our patient is the youngest described with childhood bullous pemphigoid, and we use this opportunity to review the literature and examine the clinical and immunologic features, treatment, and prognosis of this rare childhood immunobullous disorder.

Aloe vera

We review the scientific literature regarding the aloe vera plant and its products. Aloe vera is known to contain several pharmacologically active ingredients, including a carboxypeptidase that inactivates bradykinin in vitro, salicylates, and a substance(s) that inhibits thromboxane formation in vivo. Scientific studies exist that support an antibacterial and antifungal effect for substance(s) in aloe vera. Studies and case reports provide support for the use of aloe vera in the treatment of radiation ulcers and stasis ulcers in man and burn and frostbite injuries in animals. The evidence for a potential beneficial effect associated with the use of aloe vera is sufficient to warrant the design and implementation of well-controlled clinical trials.

Rehabilitation of partial laryngectomy patients

Rehabilitation and function following three anatomically discrete forms of partial laryngectomy (hemilaryngectomy, subtotal supraglottic laryngectomy, and partial laryngopharyngectomy) were studied in 68 patients. Study parameters included posttreatment respiration, deglutition, taste, smell, and hearing function; articulation and voice analysis; and social, communicative, and vocational adjustment. The major portion of the study involved specific testing of posttreatment voice quality and articulation. Recorded word lists and sentences were evaluated by independent observers regarding breathiness, hoarseness, harshness, pitch, loudness, and intelligibility. These data were analyzed employing a Statistical Package for the Social Sciences (SPSS) through the Washington University computer facilities.