Hunter syndrome: Long-term idursulfase treatment does not protect patients against DNA oxidation and cytogenetic damage

Beneficial in vitro effect of N-acetylcysteine and coenzyme Q10 on DNA damage in neurodegenerative Niemann-Pick type C 1 disease: preliminary results

Niemann-Pick type C1 (NP-C1) is a lysosomal storage disease (LSD) caused by mutations in NPC1 gene that lead to defective synthesis of the respective lysosomal transporter protein and cholesterol accumulation in late endosomes/lysosomes (LE/L) compartments, as well as glycosphingolipids GM2 and GM3 in the central nervous system (CNS). Clinical presentation varies according to the age of onset and includes visceral and neurological symptoms, such as hepatosplenomegaly and psychiatric disorders. Studies have been associating the pathophysiology of NP-C1 with oxidative damage to lipids and proteins, as well as evaluating the benefits of adjuvant therapy with antioxidants for this disease. In this work, we evaluated the DNA damage in fibroblasts culture from patients with NP-C1 treated with miglustat, as well as the in vitro effect of the antioxidant compounds N-acetylcysteine (NAC) and Coenzyme Q10 (CoQ10), using the alkaline comet assay. Our preliminary results demonstrate that NP-C1 patients have increased DNA damage compared to healthy individuals and that the treatments with antioxidants can mitigate it. DNA damage may be due to an increase in reactive species since it has been described that NP-C1 patients have increased peripheral markers of damage to other biomolecules. Our study suggests that NP-C1 patients could benefit from the use of adjuvant therapy with NAC and CoQ10, which should be better evaluated in a future clinical trial.

Evidence of redox imbalance and mitochondrial dysfunction in Niemann-Pick type C 1 patients: the in vitro effect of combined therapy with antioxidants and β-cyclodextrin nanoparticles

Niemann-Pick C disease (NPC) is an autosomal recessive genetic disorder resulting from mutation in one of two cholesterol transport genes: NPC1 or NPC2, causing accumulation of unesterified cholesterol, together with glycosphingolipids, within the endosomal/lysosomal compartment of cells. The result is a severe disease in both multiple peripheral organs and the central nervous system, causing neurodegeneration and early death. However, the pathophysiological mechanisms of NPC1 remain poorly understood. Recent studies have shown that the primary lysosomal defect found in fibroblasts from NPC1 patients is accompanied by a deregulation of mitochondrial organization and function. There is currently no cure for NPC1, but recently the potential of β-cyclodextrin (β-CD) for the treatment of the disease was discovered, which resulted in the redistribution of cholesterol from subcellular compartments to the circulation and increased longevity in an animal model of NPC1. Considering the above, the present work evaluated the in vitro therapeutic potential of β-CD to reduce cholesterol in fibroblasts from NPC1 patients. β-CD was used in its free and nanoparticulate form. We also evaluated the β-CD potential to restore mitochondrial functions, as well as the beneficial combined effects of treatment with antioxidants N-Acetylcysteine (NAC) and Coenzyme Q10 (CoQ10). Besides, we evaluated oxidative and nitrative stress parameters in NPC1 patients. We showed that oxidative and nitrative stress could contribute to the pathophysiology of NPC1, as the levels of lipoperoxidation and the nitrite and nitrate levels were increased in these patients when compared to healthy individuals, as well as DNA damage. The nanoparticles containing β-CD reduced the cholesterol accumulated in the NPC1 fibroblasts. This result was potentiated by the concomitant use of the nanoparticles with the antioxidants NAC and CoQ10 compared to those presented by healthy individuals cells ́. In addition, treatments combining β-CD nanoparticles and antioxidants could reduce mitochondrial oxidative stress, demonstrating advantages compared to free β-CD. The results obtained are promising regarding the combined use of β-CD loaded nanoparticles and antioxidants in the treatment of NPC1 disease.

iPS-derived neural stem cells for disease modeling and evaluation of therapeutics for mucopolysaccharidosis type II

Mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, is a rare, lysosomal disorder caused by mutations in a gene encoding iduronate-2-sulfatase (IDS). IDS deficiency results in an accumulation of glycosaminoglycans (GAGs) and secondary accumulations of other lipids in lysosomes. Symptoms of MPS II include a variety of soft and hard tissue problems, developmental delay, and deterioration of multiple organs. Enzyme replacement therapy is an approved treatment for MPS II, but fails to improve neuronal symptoms. Cell-based neuronal models of MPS II disease are needed for compound screening and drug development for the treatment of the neuronal symptoms in MPS II. In this study, three induced pluripotent stem cell (iPSC) lines were generated from three MPS II patient-derived dermal fibroblast cell lines that were differentiated into neural stem cells and neurons. The disease phenotypes were measured using immunofluorescence staining and Nile red dye staining. In addition, the therapeutic effects of recombinant human IDS enzyme, delta-tocopherol (DT), and hydroxypropyl-beta-cyclodextrin (HPBCD) were determined in the MPS II disease cells. Finally, the neural stem cells from two of the MPS II iPSC lines exhibited typical disease features including a deficiency of IDS activity, abnormal glycosaminoglycan storage, and secondary lipid accumulation. Enzyme replacement therapy partially rescued the disease phenotypes in these cells. DT showed a significant effect in reducing the secondary accumulation of lipids in the MPS II neural stem cells. In contrast, HPBCD displayed limited or no effect in these cells. Our data indicate that these MPS II cells can be used as a cell-based disease model to study disease pathogenesis, evaluate drug efficacy, and screen compounds for drug development.

Oxidative Stress in Mucopolysaccharidoses: Pharmacological Implications

Although mucopolysaccharidoses (MPS) are caused by mutations in genes coding for enzymes responsible for degradation of glycosaminoglycans, storage of these compounds is crucial but is not the only pathomechanism of these severe, inherited metabolic diseases. Among various factors and processes influencing the course of MPS, oxidative stress appears to be a major one. Oxidative imbalance, occurring in MPS and resulting in increased levels of reactive oxidative species, causes damage of various biomolecules, leading to worsening of symptoms, especially in the central nervous system (but not restricted to this system). A few therapeutic options are available for some types of MPS, including enzyme replacement therapy and hematopoietic stem cell transplantation, however, none of them are fully effective in reducing all symptoms. A possibility that molecules with antioxidative activities might be useful accompanying drugs, administered together with other therapies, is discussed in light of the potential efficacy of MPS treatment.

Intravenous Enzyme Replacement Therapy in Mucopolysaccharidoses: Clinical Effectiveness and Limitations

The aim of this review is to summarize the evidence on efficacy, effectiveness and safety of intravenous enzyme replacement therapy (ERT) available for mucopolysaccharidoses (MPSs) I, II, IVA, VI and VII, gained in phase III clinical trials and in observational post-approval studies. Post-marketing data are sometimes conflicting or controversial, possibly depending on disease severity, differently involved organs, age at starting treatment, and development of anti-drug antibodies (ADAs). There is general agreement that ERT is effective in reducing urinary glycosaminoglycans and liver and spleen volume, while heart and joints outcomes are variable in different studies. Effectiveness on cardiac valves, trachea and bronchi, hearing and eyes is definitely poor, probably due to limited penetration in the specific tissues. ERT does not cross the blood-brain barrier, with the consequence that the central nervous system is not cured by intravenously injected ERT. All patients develop ADAs but their role in ERT tolerance and effectiveness has not been well defined yet. Lack of reliable biomarkers contributes to the uncertainties about effectiveness. The data obtained from affected siblings strongly indicates the need of neonatal screening for treatable MPSs. Currently, other treatments are under evaluation and will surely help improve the prognosis of MPS patients.

The molecular origins and pathophysiological consequences of micronuclei: New insights into an age-old problem

Micronuclei (MN), the small nucleus-like bodies separated from the primary nucleus, can exist in cells with numerical and/or structural chromosomal aberrations in apparently normal tissues and more so in tumors in humans. While MN have been observed for over 100 years, they were merely and constantly considered as passive indicators of chromosome instability (CIN) for a long time. Relatively little is known about the molecular origins and biological consequences of MN. Rapid technological advances are helping to close these gaps. Very recent studies provide exciting evidence that MN act as key platform for chromothripsis and a trigger of innate immune response, suggesting that MN could affect cellular functions by both genetic and nongenetic means. These previously unappreciated findings have reawakened widespread interests in MN. In this review, the diverse mechanisms leading to MN generation and the complex fate profiles of MN are discussed, together with the evidence for their contribution to CIN, inflammation, senescence and cell death. Moreover, we put this knowledge together into a speculative perspective on how MN may be responsible for cancer development and how their presence may influence the choice of treatment. We suggest that the heterogeneous responses to MN may function physiological to ensure the arrestment, elimination and immune clearance of damaged cells, but pathologically, may enable the survival and oncogenic transformation of cells bearing CIN. These insights not only underscore the complexity of MN biology, but also raise a host of new questions and provide fertile ground for future research.