Glycosaminoglycans can be associated with oxidative damage in mucopolysaccharidosis II patients submitted to enzyme replacement therapy

Glycosaminoglycan-induced proinflammatory cytokine levels as disease marker in mucopolysaccharidosis

Recently, it has been shown disturbances in oxidant/antioxidant system and increases in some inflammatory markers in animal studies and in some Mucopolysaccharidoses (MPSs) patients. In this study, we aimed to determine the oxidative stress/antioxidant parameters and pro-inflammatory cytokine levels in the serum of MPS patients, in order to evaluate the possible role of inflammation in these patient groups regarding to accumulated metabolites. MPS I (n = 3), MPS II (n = 8), MPS III (n = 4), MPS IVA (n = 3), MPS VI (n = 3), and VII (n = 1) patients and 20 age-matched healthy subjects were included into the study. There was no statistically significant change in activities of SOD, Catalase, GSH-Px and lipid peroxidation levels in erythrocytes between the MPS patients and healthy controls. While IL-1alpha (p = 0.054), IL-6 (p = 0.008) levels, and chitotriosidase activity (p = 0.003) elevated in MPS3 patients, IL1α (p = 0.006), IL-1β (p = 0.006), IL-6 (p = 0.006), IFNγ (p = 0.006), and NFκB (p = 0.006) levels increased in MPS-6 patients. Elevated levels of IL-6, IL1α and chitotriosidase activity demonstrated macrophage activation in MPSIII untreated with enzyme replacement. Our study showed for the first time that high levels of IL1α, IL-6, IL1β and NFκB were present in MPSVI patients, demonstrating the induction of inflammation by dermatan sulphate. The low level of paraoxonase in MPSVI patients may be a good marker for cardiac involvement. Overall, this study provides important insights into the relationship between lysosomal storage of glycosaminoglycan and inflammation in MPS patients. It highlights possible pathways for the increased release of inflammatory molecules and suggests new targets for the development of treatments.

Evaluation of oxidative stress and mitochondrial function in a type II mucopolysaccharidosis cellular model: in vitro effects of genistein and coenzyme Q10

Mucopolysaccharidosis type II (MPS II or Hunter Syndrome) is a lysosomal disease caused by deficient degradation of glycosaminoglycans (GAGs) heparan sulfate and dermatan sulfate due to the deficiency of the enzyme iduronate-2-sulfatase. The main treatment for MPS II is the administration of the recombinant form of the enzyme, in a process known as enzyme replacement therapy (ERT). Oxidative damage can contribute to the pathophysiology of MPS II and treatment with ERT can reduce the effects of oxidative stress. For a better understanding of pathophysiology of MPS II, we evaluated biomarkers of mitochondrial dysfunction, DNA (Deoxyribonucleic acid) damage, antioxidant defenses, reactive species production and lysosomal size in IDS-deficient HEK 293 cells and investigate the in vitro effect of genistein and coenzyme Q10 (CoQ) on these biomarkers. An increase in the production of reactive species was demonstrated, as well as an increase in the activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT). Also, an increase in lysosomal volume and oxidative damage to DNA were verified. There was no evidence of a change in mitochondrial function in this cell model. In the HEK 293 (human embryonic kidney 293) knockout (KO) HP10 cell model we found that genistein at concentrations of 25 and 50 μm decreased in vitro the production of reactive species and the activity of the SOD enzyme, showing an antioxidant protective effect. Still, in these cells we verified that the coenzyme Q10 in the concentrations of 5 and 10 μm decreased in vitro the activity of the SOD enzyme and in the concentration of 10 μm decreased in vitro the DNA damage, also demonstrating antioxidant protection. In conclusion, MPS II knockout cells demonstrated oxidative stress and DNA damage and genistein, as well as coenzyme Q10, have been shown to have an important protective effect in vitro against these oxidative damages.

Human kidney organoids reveal the role of glutathione in Fabry disease

Fabry disease is an X-linked lysosomal storage disease caused by a mutation in the galactosidase alpha (GLA) gene. Despite advances in therapeutic technologies, the lack of humanized experimental models of Fabry disease has limited the development of new therapies to cure the disease. Herein, we modeled Fabry disease using human inducible pluripotent stem cell (iPSC)-derived kidney organoids and the CRISPR-Cas9 genome-editing system. GLA-mutant human kidney organoids revealed deformed podocytes and tubular cells with accumulation of globotriaosylceramide (Gb3). Ultrastructural analysis showed abundant electron-dense granular deposits and electron-dense lamellate lipid-like deposits that formed concentric bodies (zebra bodies) in the cytoplasm of podocytes and tubules. The oxidative stress level was increased in GLA-mutant kidney organoids, and the increase was accompanied by apoptosis. Enzyme replacement treatment (ERT) with recombinant human α-Gal A decreased the Gb3 accumulation and oxidative stress, which resulted in amelioration of the deformed cellular structure of the GLA-mutant kidney organoids. Transcription profile analyses showed decreased glutathione (GSH) metabolism in GLA-mutant kidney organoids. GSH replacement treatment decreased oxidative stress and attenuated the structural deformity of the GLA-mutant kidney organoids. GSH treatment also increased the expression of podocyte and tubular markers and decreased apoptosis. In conclusion, GLA-mutant kidney organoids derived from human iPSCs are valuable tools for studying the mechanisms and developing novel therapeutic alternatives for Fabry disease.

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.

Diagnosis of Mucopolysaccharidoses

The mucopolysaccharidoses (MPSs) include 11 different conditions caused by specific enzyme deficiencies in the degradation pathway of glycosaminoglycans (GAGs). Although most MPS types present increased levels of GAGs in tissues, including blood and urine, diagnosis is challenging as specific enzyme assays are needed for the correct diagnosis. Enzyme assays are usually performed in blood, with some samples (as leukocytes) providing a final diagnosis, while others (such as dried blood spots) still being considered as screening methods. The identification of variants in the specific genes that encode each MPS-related enzyme is helpful for diagnosis confirmation (when needed), carrier detection, genetic counseling, prenatal diagnosis (preferably in combination with enzyme assays) and phenotype prediction. Although the usual diagnostic flow in high-risk patients starts with the measurement of urinary GAGs, it continues with specific enzyme assays and is completed with mutation identification; there is a growing trend to have genotype-based investigations performed at the beginning of the investigation. In such cases, confirmation of pathogenicity of the variants identified should be confirmed by measurement of enzyme activity and/or identification and/or quantification of GAG species. As there is a growing number of countries performing newborn screening for MPS diseases, the investigation of a low enzyme activity by the measurement of GAG species concentration and identification of gene mutations in the same DBS sample is recommended before the suspicion of MPS is taken to the family. With specific therapies already available for most MPS patients, and with clinical trials in progress for many conditions, the specific diagnosis of MPS as early as possible is becoming increasingly necessary. In this review, we describe traditional and the most up to date diagnostic methods for mucopolysaccharidoses.

The pathophysiological role of mitochondrial oxidative stress in lung diseases

Mitochondria are critically involved in reactive oxygen species (ROS)-dependent lung diseases, such as lung fibrosis, asbestos, chronic airway diseases and lung cancer. Mitochondrial DNA (mtDNA) encodes mitochondrial proteins and is more sensitive to oxidants than nuclear DNA. Damage to mtDNA causes mitochondrial dysfunction, including electron transport chain impairment and mitochondrial membrane potential loss. Furthermore, damaged mtDNA also acts as a damage-associated molecular pattern (DAMP) that drives inflammatory and immune responses. In this review, crosstalk among alveolar epithelial cells, alveolar macrophages and mitochondria is examined. ROS-related transcription factors and downstream cell signaling pathways are also discussed. We conclude that targeting oxidative stress with antioxidant agents, such as thiol molecules, polyphenols and superoxide dismutase (SOD), and promoting mitochondrial biogenesis should be considered as novel strategies for treating lung diseases that currently have no effective treatment options.

Urinary metabolic phenotyping of mucopolysaccharidosis type I combining untargeted and targeted strategies with data modeling

BACKGROUND

Application of metabolic phenotyping could expand the pathophysiological knowledge of mucopolysaccharidoses (MPS) and may reveal the comprehensive metabolic impairments in MPS. However, few studies applied this approach to MPS.

METHODS

We applied targeted and untargeted metabolic profiling in urine samples obtained from a French cohort comprising 19 MPS I and 15 MPS I treated patients along with 66 controls. For that purpose, we used ultra-high-performance liquid chromatography combined with ion mobility and high-resolution mass spectrometry following a protocol designed for large-scale metabolomics studies regarding robustness and reproducibility. Furthermore, 24 amino acids have been quantified using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Keratan sulfate, Heparan sulfate and Dermatan sulfate concentrations have also been measured using an LC-MS/MS method. Univariate and multivariate data analyses have been used to select discriminant metabolites. The mummichog algorithm has been used for pathway analysis.

RESULTS

The studied groups yielded distinct biochemical phenotypes using multivariate data analysis. Univariate statistics also revealed metabolites that differentiated the groups. Specifically, metabolites related to the amino acid metabolism. Pathway analysis revealed that several major amino acid pathways were dysregulated in MPS. Comparison of targeted and untargeted metabolomics data with in silico results yielded arginine, proline and glutathione metabolisms being the most affected.

CONCLUSION

This study is one of the first metabolic phenotyping studies of MPS I. The findings might help to generate new hypotheses about MPS pathophysiology and to develop further targeted studies of a smaller number of potentially key metabolites.

Oxidative and nitrative stress and pro-inflammatory cytokines in Mucopolysaccharidosis type II patients: effect of long-term enzyme replacement therapy and relation with glycosaminoglycan accumulation

Mucopolysaccharidosis type II (MPS II) is a lysosomal storage disease caused by a deficient activity of iduronate-2-sulfatase, leading to abnormal accumulation of glycosaminoglycans (GAG). The main treatment for MPS II is enzyme replacement therapy (ERT). Previous studies described potential benefits of six months of ERT against oxidative stress in patients. Thus, the aim of this study was to investigate oxidative, nitrative and inflammatory biomarkers in MPS II patients submitted to long term ERT. It were analyzed urine and blood samples from patients on ERT (mean time: 5.2years) and healthy controls. Patients presented increased levels of lipid peroxidation, assessed by urinary 15-F2t-isoprostane and plasmatic thiobarbituric acid-reactive substances. Concerning to protein damage, urinary di-tyrosine (di-Tyr) was increased in patients; however, sulfhydryl and carbonyl groups in plasma were not altered. It were also verified increased levels of urinary nitrate+nitrite and plasmatic nitric oxide (NO) in MPS II patients. Pro-inflammatory cytokines IL-1β and TNF-α were increased in treated patients. GAG levels were correlated to di-Tyr and nitrate+nitrite. Furthermore, IL-1β was positively correlated with TNF-α and NO. Contrastingly, we did not observed alterations in erythrocyte superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase activities, in reduced glutathione content and in the plasmatic antioxidant capacity. Although some parameters were still altered in MPS II patients, these results may suggest a protective role of long-term ERT against oxidative stress, especially upon oxidative damage to protein and enzymatic and non-enzymatic defenses. Moreover, the redox imbalance observed in treated patients seems to be GAG- and pro-inflammatory cytokine-related.

Oxidative stress and inflammation in mucopolysaccharidosis type IVA patients treated with enzyme replacement therapy

Mucopolysaccharidosis type IVA (MPS IVA) is an inborn error of glycosaminoglycan (GAG) catabolism due to the deficient activity of N-acetylgalactosamine-6-sulfate sulfatase that leads to accumulation of the keratan sulfate and chondroitin 6-sulfate in body fluids and in lysosomes. The pathophysiology of this lysosomal storage disorder is not completely understood. The aim of this study was to investigate oxidative stress parameters, pro-inflammatory cytokine and GAG levels in MPS IVA patients. We analyzed urine and blood samples from patients under ERT (n=17) and healthy age-matched controls (n=10-15). Patients presented a reduction of antioxidant defense levels, assessed by a decrease in glutathione content and by an increase in superoxide dismutase activity in erythrocytes. Concerning lipid and protein damage, it was verified increased urine isoprostanes and di-tyrosine levels and decreased plasma sulfhydryl groups in MPS IVA patients compared to controls. MPS IVA patients showed higher DNA damage than control group and this damage had an oxidative origin in both pyrimidine and purine bases. Interleukin 6 was increased in patients and presented an inverse correlation with GSH levels, showing a possible link between inflammation and oxidative stress in MPS IVA disease. The data presented suggest that pro-inflammatory and pro-oxidant states occur in MPS IVA patients even under ERT. Taking these results into account, supplementation of antioxidants in combination with ERT can be a tentative therapeutic approach with the purpose of improving the patient's quality of life. To the best of our knowledge, this is the first study relating MPS IVA patients with oxidative stress.