Neuroinflammation in aucher disease, neuronal ceroid lipofuscinosis, and commonalities with Parkinson’s disease

Upregulation of peroxisome proliferator-activated receptor γ with resorcinol alleviates reactive oxygen species generation and lipid accumulation in neuropathic lysosomal storage diseases

Neuropathic lysosomal storage diseases (NLSDs), including ceroid lipofuscinosis neuronal 3 (CLN3) disease and Gaucher disease type 2 (GD2), are typically present in adolescents; however, there are no approved therapies. CLN3 disease is the most common of the 13 types of neuronal ceroid lipofuscinosis, and Gaucher disease is the most common type of lysosomal storage disease. These NLSDs share oxidative stress and lysosomal dysfunction with Parkinson's disease. In this study, we used patient-derived cells (PDCs) and resorcinol to develop a therapeutic agent based on peroxisome proliferator-activated receptor γ (PPARγ) activation. PPARγ is a major regulator of autophagy and reactive oxygen species (ROS). Resorcinol, a polyphenolic compound, has been reported to exhibit PPARγ agonistic potential. Protein levels were analyzed by immunoblotting and immunofluorescence microscopy. Changes in cellular metabolism, including ROS levels, lipid droplet content, and lysosomal activity, were measured by flow cytometry. Resorcinol reduced ROS levels by suppressing hypoxia-inducible factor 1α levels in CLN3-PDCs. Resorcinol upregulated autophagy and reduced lipid accumulation in CLN3-PDCs; however, these effects were abolished by autophagy inhibitors. Resorcinol increased nuclear PPARγ levels in CLN3-PDCs, and PPARγ antagonists abolished the therapeutic effects of resorcinol. Moreover, Resorcinol upregulated nuclear PPARγ levels and lysosomal activity in GD2-PDCs, and reduced lipid accumulation and ROS levels. In summary, resorcinol alleviated the shared pathogenesis of CLN3 disease and GD2 through PPARγ upregulation. These findings suggest that resorcinol is a potential therapeutic candidate for alleviating NLSD progression.

Integrative human and murine multi-omics: Highlighting shared biomarkers in the neuronal ceroid lipofuscinoses

Neuronal ceroid lipofuscinosis (NCL) is a group of neurodegenerative disorders whose molecular mechanisms remain largely unknown. Omics approaches are among the methods that generate new information on modifying factors and molecular signatures. Moreover, omics data integration can address the need to progressively expand knowledge around the disease and pinpoint specific proteins to promote as candidate biomarkers. In this work, we integrated a total of 62 proteomic and transcriptomic datasets originating from humans and mice, employing a new approach able to define dysregulated processes across species, stages and NCL forms. Moreover, we selected a pool of differentially expressed proteins and genes as species- and form-related biomarkers of disease status/progression and evaluated local and spatial differences in most affected brain regions. Our results offer promising targets for potential new therapeutic strategies and reinforce the hypothesis of a connection between NCLs and other forms of dementia, particularly Alzheimer's disease.

Characterizing Common Phenotypes Across the Childhood Dementia Disorders: A Cross-sectional Study From Two Australian Centers

BACKGROUND

Childhood dementias are a group of rare pediatric conditions characterized by progressive neurocognitive decline. Quantifying and characterising phenotypes to identify similarities between specific conditions is critical to inform opportunities to optimize care and advance research.

METHODS

This cross-sectional study recruited primary caregivers of children (<18 years) living with a dementia syndrome from neurology and metabolic clinics in Sydney and Adelaide, Australia. Sociodemographic and clinical data were collated. Behavior, eating, sleep, pain, and neurological disability were assessed using validated tools, including Strengths and Difficulties, Child Eating Behaviour, and Children's Sleep Habits questionnaires and visual analog of pain and modified Rankin scales. Data were analyzed with descriptive statistics.

RESULTS

Among 45 children with 23 different dementia syndromes, the modified Rankin Scale demonstrated at least moderate neurological disability and functional dependence in 82% (37/45). Families reported delays in receiving an accurate diagnosis following initial symptoms (mean: 1.6 ± 1.4 years, range: 0-5 years). The most prevalent phenotypes included communication, comprehension, or recall difficulties (87%, 39/45); disturbances in sleep (80%, 36/45); appetite changes (74%, 29/39); mobility issues (53%, 24/45); and hyperactive behavior (53%, 21/40). Behavioral problems had a "high" or "very high" impact on everyday family life in 73% (24/33).

CONCLUSIONS

Childhood dementia disorders share substantial behavioral, motor, sensory, and socioemotional symptoms, resulting in high care needs, despite their vast heterogeneity in age of onset and progression. Considering their unifying characteristics under one collective term is an opportunity to improve treatment, provide quality care, and accelerate research.

The Challenges to Advancing Induced Pluripotent Stem Cell-Dependent Cell Replacement Therapy

Induced pluripotent stem cells (iPSC) represent a potentially exciting regenerative-medicine cell therapy for several chronic conditions such as macular degeneration, soft tissue and orthopedic conditions, cardiopulmonary disease, cancer, neurodegenerative disorders and metabolic disorders. The field of iPSC therapeutics currently exists at an early stage of development. There are several important stakeholders that include academia, industry, regulatory agencies, financial institutions and patients who are committed to advance the field. Yet, unlike more established therapeutic modalities like small and large molecules, iPSC therapies pose significant unique challenges with respect to safety, potency, genetic stability, immunogenicity, tumorgenicity, cell reproducibility, scalability and engraftment. The aim of this review article is to highlight the unique technical challenges that need to be addressed before iPSC technology can be fully realized as a cell replacement therapy. Additionally, this manuscript offers some potential solutions and identifies areas of focus that should be considered in order for the iPSC field to achieve its promise. The scope of this article covers the following areas: (1) the impact of different iPSC reprogramming methods on immunogenicity and tumorigenicity; (2) the effect of genetic instability on cell reproducibility and differentiation; (3) the role of growth factors and post-translational modification on differentiation and cell scalability; (4) the potential use of gene editing in improving iPSC differentiation; (5) the advantages and disadvantages between autologous and allogeneic cell therapy; (6) the regulatory considerations in developing a viable and reproducible cell product; and (7) the impact of local tissue inflammation on cell engraftment and cell viability.

The involvement of Purkinje cells in progressive myoclonic epilepsy: Focus on neuronal ceroid lipofuscinosis

The progressive myoclonic epilepsies (PMEs) are a group of rare neurodegenerative diseases characterized by myoclonus, epileptic seizures, and progressive neurological deterioration with cerebellar involvement. They include storage diseases like Gaucher disease, Lafora disease, and forms of neuronal ceroid lipofuscinosis (NCL). To date, 13 NCLs have been reported (CLN1-CLN8, CLN10-CLN14), associated with mutations in different genes. These forms, which affect both children and adults, are characterized by seizures, cognitive and motor impairments, and in most cases visual loss. In NCLs, as in other PMEs, central nervous system (CNS) neurodegeneration is widespread and involves different subpopulations of neurons. One of the most affected regions is the cerebellar cortex, where motor and non-motor information is processed and transmitted to deep cerebellar nuclei through the axons of Purkinje cells (PCs). PCs, being GABAergic, have an inhibitory effect on their target neurons, and provide the only inhibitory output of the cerebellum. Degeneration of PCs has been linked to motor impairments and epileptic seizures. Seizures occur when some insult upsets the normal balance in the CNS between excitatory and inhibitory impulses, causing hyperexcitability. Here we review the role of PCs in epilepsy onset and progression following their PME-related loss. In particular, we focus on the involvement of PCs in seizure phenotype in NCLs, highlighting findings from case reports and studies of animal models in which epilepsy can be linked to PC loss.

SCA34 caused by ELOVL4 L168F mutation is a lysosomal lipid storage disease sharing pathology features with neuronal ceroid lipofuscinosis and peroxisomal disorders

Spinocerebellar ataxia 34 (SCA34) is a late-onset progressive ataxia caused by a mutation in ELOVL4, a gene involved in the biosynthesis of very long-chain fatty acids (VLCFAs). We performed post-mortem neuropathological examinations on four SCA34 patients with the ELOVL4 L168F mutation and compared the findings to age-matched controls. Specific gross findings of SCA34 were limited to pontocerebellar atrophy. On light microscopy, pontine base showed neuronal loss and storage of an autofluorescent lipopigment positive on oil red O, PAS and Hale's colloidal iron and negative on Alcian blue and Luxol fast blue (LFB). Among the swollen neurons were abundant CD68+ /CD163+ /IBA1- macrophages laden with a material with similar histochemical profile as in neurons except for the lack of autofluorescence and oil red O positivity and the presence of needle-like birefringent inclusions. Normal resting IBA1 + microglia were generally absent from pontine base nuclei but present in normal numbers elsewhere in the pons. In dentate nucleus neurons, atrophy was milder than in the pontine base and the coarser storage material was LFB-positive, closely resembling lipofuscin. On electron microscopy, dentate nucleus neurons showed neuronal storage of tridimensionally organized trilaminar spicules within otherwise normal lipofuscin, while in the more affected pontine base neurons, lipofuscin was almost completely replaced by the storage material. Storage macrophages were tightly packed with stacks of unorganized trilaminar spicules, reminiscent of the storage material seen in peroxisomal disorders and thought to represent VLCFAs incorporated in complex polar lipids. In summary, we provide histochemical and ultrastructural evidence that SCA34 is a lipid storage disease, the first among the currently known SCAs, and that the storage lipid is accumulating within neuronal lipofuscin. Our findings suggest that the storage lipid is similar to the one accumulating in non-neuronal cells in peroxisomal disorders and provide the first ultrastructural description of this type of material within neurons.

Lysosomal functions of progranulin and implications for treatment of frontotemporal dementia

Loss-of-function heterozygous mutations in GRN, the gene encoding progranulin (PGRN), were identified in patients with frontotemporal lobar degeneration (FTLD) almost two decades ago and are generally linked to reduced PGRN protein expression levels. Although initial characterization of PGRN function primarily focused on its role in extracellular signaling as a secreted protein, more recent studies revealed critical roles of PGRN in regulating lysosome function, including proteolysis and lipid degradation, consistent with its lysosomal localization. Emerging from these studies is the notion that PGRN regulates glucocerebrosidase activity via direct chaperone activities and via interaction with prosaposin (i.e., a key regulator of lysosomal sphingolipid-metabolizing enzymes), as well as with the anionic phospholipid bis(monoacylglycero)phosphate. This emerging lysosomal biology of PGRN identified novel and promising opportunities in therapeutic discovery as well as biomarker development.

Childhood Dementia: A Collective Clinical Approach to Advance Therapeutic Development and Care

Childhood dementias are a group of over 100 rare and ultra-rare pediatric conditions that are clinically characterized by chronic global neurocognitive decline. This decline is associated with a progressive loss of skills and shortened life expectancy. With an estimated incidence of one in 2800 births and less than 5% of the conditions having disease-modifying therapies, the impact is profound for patients and their families. Traditional research, care, and advocacy efforts have focused on individual disorders, or groups classified by molecular pathogenesis, and this has established robust foundations for further progress and collaboration. This review describes the shared and disease-specific clinical changes contributing to childhood dementia and considers these as potential indicators of underlying pathophysiologic processes. Like adult neurodegenerative syndromes, the heterogeneous phenotypes extend beyond cognitive decline and may involve changes in eating, motor function, pain, sleep, and behavior, mediated by physiological changes in neural networks. Importantly, these physiological phenotypes are associated with significant carer stress, anxiety, and challenges in care. These phenotypes are also pertinent for the development of therapeutics and optimization of best practice management. A collective approach to childhood dementia is anticipated to identify relevant biomarkers of prognosis or therapeutic efficacy, streamline the path from preclinical studies to clinical trials, increase opportunities for the development of multiple therapeutics, and refine clinical care.

A multifaceted evaluation of microgliosis and differential cellular dysregulation of mammalian target of rapamycin signaling in neuronopathic Gaucher disease

Neuronopathic Gaucher disease (nGD) is an inherited neurodegenerative disease caused by mutations in GBA1 gene and is associated with premature death. Neuroinflammation plays a critical role in disease pathogenesis which is characterized by microgliosis, reactive astrocytosis, and neuron loss, although molecular mechanisms leading to neuroinflammation are not well-understood. In this report, we developed a convenient tool to quantify microglia proliferation and activation independently and uncovered abnormal proliferation of microglia (∼2-fold) in an adult genetic nGD model. The nGD-associated pattern of inflammatory mediators pertinent to microglia phenotypes was determined, showing a unique signature favoring pro-inflammatory chemokines and cytokines. Moreover, highly polarized (up or down) dysregulations of mTORC1 signaling with varying lysosome dysfunctions (numbers and volume) were observed among three major cell types of nGD brain. Specifically, hyperactive mTORC1 signaling was detected in all disease-associated microglia (Iba1^high) with concurrent increase in lysosome function. Conversely, the reduction of neurons presenting high mTORC1 activity was implicated (including Purkinje-like cells) which was accompanied by inconsistent changes of lysosome function in nGD mice. Undetectable levels of mTORC1 activity and low Lamp1 puncta were noticed in astrocytes of both diseased and normal mice, suggesting a minor involvement of mTORC1 pathway and lysosome function in disease-associated astrocytes. These findings highlight the differences and complexity of molecular mechanisms that are involved within various cell types of the brain. The quantifiable parameters established and nGD-associated pattern of neuroinflammatory mediators identified would facilitate the efficacy evaluation on microgliosis and further discovery of novel therapeutic target(s) in treating neuronopathic Gaucher disease.