Oxidative Stress in Mucopolysaccharidoses: Pharmacological Implications

Cellular Organelle-Related Transcriptomic Profile Abnormalities in Neuronopathic Types of Mucopolysaccharidosis: A Comparison with Other Neurodegenerative Diseases

Mucopolysaccharidoses (MPS) are a group of diseases caused by mutations in genes encoding lysosomal enzymes that catalyze reactions of glycosaminoglycan (GAG) degradation. As a result, GAGs accumulate in lysosomes, impairing the proper functioning of entire cells and tissues. There are 14 types/subtypes of MPS, which are differentiated by the kind(s) of accumulated GAG(s) and the type of a non-functional lysosomal enzyme. Some of these types (severe forms of MPS types I and II, MPS III, and MPS VII) are characterized by extensive central nervous system disorders. The aim of this work was to identify, using transcriptomic methods, organelle-related genes whose expression levels are changed in neuronopathic types of MPS compared to healthy cells while remaining unchanged in non-neuronopathic types of MPS. The study was conducted with fibroblast lines derived from patients with neuronopathic and non-neuronopathic types of MPS and control (healthy) fibroblasts. Transcriptomic analysis has identified genes related to cellular organelles whose expression is altered. Then, using fluorescence and electron microscopy, we assessed the morphology of selected structures. Our analyses indicated that the genes whose expression is affected in neuronopathic MPS are often associated with the structures or functions of the cell nucleus, endoplasmic reticulum, or Golgi apparatus. Electron microscopic studies confirmed disruptions in the structures of these organelles. Special attention was paid to up-regulated genes, such as PDIA3 and MFGE8, and down-regulated genes, such as ARL6IP6, ABHD5, PDE4DIP, YIPF5, and CLDN11. Of particular interest is also the GM130 (GOLGA2) gene, which encodes golgin A2, which revealed an increased expression in neuronopathic MPS types. We propose to consider the levels of mRNAs of these genes as candidates for biomarkers of neurodegeneration in MPS. These genes may also become potential targets for therapies under development for neurological disorders associated with MPS and candidates for markers of the effectiveness of these therapies. Although fibroblasts rather than nerve cells were used in this study, it is worth noting that potential genetic markers characteristic solely of neurons would be impractical in testing patients, contrary to somatic cells that can be relatively easily obtained from assessed persons.

Oxidative stress affects the beginning of the growth of cancer cells through a variety of routes

Oxidative stress is a physiological condition that occurs when there is an imbalance between the production of reactive oxygen species (ROS) and the cell's antioxidant defense system. ROS are highly reactive molecules that can cause damage to cellular structures such as DNA, proteins, and lipids. the regulation of ROS levels and the antioxidant defense system is crucial for cancer prevention and treatment. Strategies to enhance antioxidant defenses or induce oxidative stress selectively in cancer cells are being developed as potential therapeutic approaches. targeting oxidative stress in cancer treatment is an active area of research with several potential therapeutic approaches being investigated. Developing selective and effective therapies that target oxidative stress in cancer cells while sparing normal cells will be crucial for improving cancer treatment outcomes.

The Potential of Cylindromatosis (CYLD) as a Therapeutic Target in Oxidative Stress-Associated Pathologies: A Comprehensive Evaluation

Oxidative stress (OS) arises as a consequence of an imbalance between the formation of reactive oxygen species (ROS) and the capacity of antioxidant defense mechanisms to neutralize them. Excessive ROS production can lead to the damage of critical biomolecules, such as lipids, proteins, and DNA, ultimately contributing to the onset and progression of a multitude of diseases, including atherosclerosis, chronic obstructive pulmonary disease, Alzheimer's disease, and cancer. Cylindromatosis (CYLD), initially identified as a gene linked to familial cylindromatosis, has a well-established and increasingly well-characterized function in tumor inhibition and anti-inflammatory processes. Nevertheless, burgeoning evidence suggests that CYLD, as a conserved deubiquitination enzyme, also plays a pivotal role in various key signaling pathways and is implicated in the pathogenesis of numerous diseases driven by oxidative stress. In this review, we systematically examine the current research on the function and pathogenesis of CYLD in diseases instigated by oxidative stress. Therapeutic interventions targeting CYLD may hold significant promise for the treatment and management of oxidative stress-induced human diseases.

Contribution of vesicle trafficking dysregulation to the pathomechanism of mucopolysaccharidosis

Although mucopolysaccharidoses (MPS) are monogenic diseases, caused by mutations in genes coding for enzymes involved in degradation of glycosaminoglycans (GAGs), recent studies suggested that changes in expressions of various genes might cause secondary and tertiary cellular dysfunctions modulating the course of these diseases. In this report, we demonstrate that vesicle trafficking regulation is affected in fibroblasts derived from patients suffering from 11 different types of MPS due to changes in levels of crucial proteins (estimated by automated Western-blotting) involved in this process, including caveolin, clathrin, huntingtin (Htt), APPL1, EEA1, GOPC, Rab5, and Rab7. Microscopic studies confirmed these results, while investigations of tissue samples derived from the MPS I mouse model indicated differences between various organs in this matter. Moreover, transcriptomic analyses provided a global picture for changes in expressions of genes related to vesicle trafficking in MPS cells. We conclude that vesicle trafficking is dysregulated in MPS cells and changes in this process might contribute to the molecular mechanisms of this disease. Most probably, primary GAG storage might cause a cellular stress response leading to dysregulation of expression of many genes which, in turn, results in changes in cellular processes like vesicle trafficking. This can significantly modulate the course of the disease due to enhancing accumulation of GAGs and altering crucial cellular processes. This hypothesis has been supported by normalization of levels of clathrin in MPS cells treated with either an active form of the deficient GAG-degrading enzyme or a compound (5,7-dihydroxy-3-(4-hydroxyphenyl)-4H-1-benzopyran-4-one) indirectly reducing the efficiency of GAG synthesis.

Redox Imbalance in Neurological Disorders in Adults and Children

Oxygen is a central molecule for numerous metabolic and cytophysiological processes, and, indeed, its imbalance can lead to numerous pathological consequences. In the human body, the brain is an aerobic organ and for this reason, it is very sensitive to oxygen equilibrium. The consequences of oxygen imbalance are especially devastating when occurring in this organ. Indeed, oxygen imbalance can lead to hypoxia, hyperoxia, protein misfolding, mitochondria dysfunction, alterations in heme metabolism and neuroinflammation. Consequently, these dysfunctions can cause numerous neurological alterations, both in the pediatric life and in the adult ages. These disorders share numerous common pathways, most of which are consequent to redox imbalance. In this review, we will focus on the dysfunctions present in neurodegenerative disorders (specifically Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis) and pediatric neurological disorders (X-adrenoleukodystrophies, spinal muscular atrophy, mucopolysaccharidoses and Pelizaeus-Merzbacher Disease), highlighting their underlining dysfunction in redox and identifying potential therapeutic strategies.

Mechanism of Aspirin oxidative stress regulating interleukin-induced apoptosis in nucleus pulposus cells in a rat model of intervertebral disc degeneration

Background

Intervertebral disc degeneration (IDD) is an important cause of low back pain. Increase of reactive oxygen species (ROS), overexpression of inflammatory factors, and loss of extracellular matrix are important factors in the pathological changes of IDD. The present study aimed to investigate the mechanism of action of Aspirin regulating oxidative stress in IDD, so as to propose new treatment.

Methods

Nucleus pulposus cells (NPCs) were isolated from the caudal intervertebral discs of Sprague Dawley (SD) rats under sterile conditions. The expression of ROS and inflammatory factors was detected sequentially, and the degree of degeneration of nucleus pulposus cells was observed by real-time fluorescence quantitative polymerase chain reaction (PCR) and cell immunofluorescence staining. In vivo, the caudal disc puncture model was used to induce degeneration, and a local injection of 10 or 100 µg/mL Aspirin was performed. The rats were sacrificed 1 week later, and the disc specimens of the tail vertebrae were collected for imaging, histomorphology, and immunohistochemical analysis.

Results

In vitro experiments showed that lipopolysaccharide (LPS) could significantly induce oxidative stress in NPCs and stimulate NPCs to secrete a large amount of ROS and inflammatory factors, which eventually leads to the reduction of collagen type II and polyglycoprotein gene expression in NPCs and the high expression of matrix metalloproteinase (MMP). Consequently, NPCs degeneration occurs.

Conclusions

Our results clarified the important role of oxidative stress in IDD and proved that LPS can be used as a drug to alleviate oxidative stress and intervene in the IDD process.

Mucopolysaccharidoses: Cellular Consequences of Glycosaminoglycans Accumulation and Potential Targets

Mucopolysaccharidoses (MPSs) constitute a heterogeneous group of lysosomal storage disorders characterized by the lysosomal accumulation of glycosaminoglycans (GAGs). Although lysosomal dysfunction is mainly affected, several cellular organelles such as mitochondria, endoplasmic reticulum, Golgi apparatus, and their related process are also impaired, leading to the activation of pathophysiological cascades. While supplying missing enzymes is the mainstream for the treatment of MPS, including enzyme replacement therapy (ERT), hematopoietic stem cell transplantation (HSCT), or gene therapy (GT), the use of modulators available to restore affected organelles for recovering cell homeostasis may be a simultaneous approach. This review summarizes the current knowledge about the cellular consequences of the lysosomal GAGs accumulation and discusses the use of potential modulators that can reestablish normal cell function beyond ERT-, HSCT-, or GT-based alternatives.

Sanfilippo Syndrome: Optimizing Care with a Multidisciplinary Approach

Sanfilippo syndrome, or mucopolysaccharidosis type III (MPS III), is a disease grouping five genetic disorders, four of them occurring in humans and one known to date only in a mouse model. In every subtype of MPS III (designed A, B, C, D or E), a lack or drastically decreased activity of an enzyme involved in the degradation of heparan sulfate (HS) (a compound from the group of glycosaminoglycans (GAGs)) arises from a genetic defect. This leads to primary accumulation of HS, and secondary storage of other compounds, combined with changes in expressions of hundreds of genes and many defects in organelles and various biochemical processes in the cell. As a result, dysfunctions of tissues and organs occur, leading to severe symptoms in patients. Although changes in somatic organs are considerable, the central nervous system is especially severely affected, and neurological, cognitive and behavioral disorders are the most significant changes, making the disease enormously burdensome for patients and their families. In the light of the current lack of any registered therapy for Sanfilippo syndrome (despite various attempts of many research groups to develop effective treatment, still no specific drug or procedure is available for MPS III), optimizing care with a multidisciplinary approach is crucial for managing this disease and making quality of patients’ life passable. This includes efforts to make/organize (i) accurate diagnosis as early as possible (which is not easy due to various possible misdiagnosis events caused by similarity of MPS III symptoms to those of other diseases and variability of patients), (ii) optimized symptomatic treatment (which is challenging because of complexity of symptoms and often untypical responses of MPS III patients to various drugs), and (iii) psychological care (for both patients and family members and/or caregivers). In this review article, we focus on these approaches, summarizing and discussing them.

Cell cycle disturbances in mucopolysaccharidoses: Transcriptomic and experimental studies on cellular models

Mucopolysaccharidoses (MPS) are a group of lysosomal storage diseases caused by defects in genes coding for proteins involved in degradation of glycosaminoglycans (GAGs). These complex carbohydrates accumulate in cells causing their serious dysfunctions. Apart from the physical GAG storage, secondary and tertiary changes may contribute significantly to the pathomechanism of the disease. Among processes which were not systematically investigated in MPS cells to date there is the cell cycle. Here, we studied perturbances in this crucial cellular process in majority of MPS types. Transcriptomic analyses indicated that expression of many genes coding for proteins involved in the cell cycle is dysregulated in all tested MPS cells. Importantly, levels of transcripts of particular genes were changed in the same manner (i.e. either up- or down-regulated) in most or all types of the disease, indicating a common mechanism of the dysregulation. Flow cytometric studies demonstrated that the cell cycle is disturbed in all MPS types, with increased fractions of cells in the G₀/G₁ phase in most types and decreased fractions of cells in the G₂/M phase in all types. We found that increased levels of cyclin D1 and disturbed timing of its appearance during the cell cycle may contribute to the mechanism of dysregulation of this process in MPS. Reduction of GAG levels by either a specific enzyme or genistein-mediated inhibition of synthesis of these compounds improved, but not fully corrected, the cell cycle in MPS fibroblasts. Therefore, it is suggested that combination of the therapeutic approaches devoted to reduction of GAG levels with cyclin D1 inhibitors might be considered in further works on developing effective treatment procedures for MPS.

The Inflammation in the Cytopathology of Patients With Mucopolysaccharidoses- Immunomodulatory Drugs as an Approach to Therapy

Mucopolysaccharidoses (MPS) are a group of lysosomal storage diseases (LSDs), characterized by the accumulation of glycosaminoglycans (GAGs). GAG storage-induced inflammatory processes are a driver of cytopathology in MPS and pharmacological immunomodulation can bring improvements in brain, cartilage and bone pathology in rodent models. This manuscript reviews current knowledge with regard to inflammation in MPS patients and provides hypotheses for the therapeutic use of immunomodulators in MPS. Thus, we aim to set the foundation for a rational repurposing of the discussed molecules to minimize the clinical unmet needs still remaining despite enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT).