Joint and bone disease in mucopolysaccharidoses VI and VII: identification of new therapeutic targets and biomarkers using animal models

Combining angiotensin receptor blockade and enzyme replacement therapy for vascular disease in mucopolysaccharidosis type I

Vascular involvement in the genetic disorder mucopolysaccharidosis type I (MPS I) has features of atherosclerotic disease near branch points of arterial vasculature, such as intimal thickening with disruption of the internal elastic lamina, and proliferation of macrophages and myofibroblasts. Inflammatory pathways are implicated in the pathogenesis of vascular disease in MPS I animal models, evidenced by cytokines like CD18 and TGF-β within arterial plaques. The angiotensin II-mediated inflammatory pathway is well studied in human atherosclerotic coronary artery disease. Recent work indicates treatment with the angiotensin receptor blocker losartan may improve vascular MPS I disease in mouse models. Here, we combined losartan with the standard therapy for MPS I, enzyme replacement therapy (ERT), to measure effects on cytokines in serum and aortic vasculature. Each treatment group (losartan, ERT, and their combination) equally normalized levels of cytokines that were largely differential between normal and mutant mice. Some cytokines, notably CD30 ligand, Eotaxin-2, LIX, IL-13, IL-15, GM-CSF, MCP-5, MIG, and CCL3 showed elevations in mice treated with ERT above normal or mutant levels; these elevations were reduced or absent in mice that received losartan or combination therapy. The observations suggest that losartan may impact inflammatory cascades due to MPS I and may also blunt inflammation in combination with ERT.

Evaluation of etanercept (a tumor necrosis factor alpha inhibitor) as an effective treatment for joint disease in mucopolysaccharidosis type I. A case report with whole-body magnetic resonance imaging

Summary

A 12-year-old girl with mucopolysaccharidosis (MPS) type I (Gurler-Scheie syndrome, Q70X/del C683 of the IDUA gene in the compound heterozygous state) regularly received enzyme replacement therapy (laronidase) since the preclinical stage (6 months old) due to positive family history, and started etanercept treatment due to progression of joint pain and decreasing capability to walk. The patient had a significant reduction of pain in the joints and an expansion of daily physical activity without adverse events. A decrease in bone marrow edema without foci progression compared to baseline assessment was observed in the whole-body MRI.During the treatment (baseline/6 months/12 months) the following was observed: childhood health assessment questionnaire (CHAQ) index of 1.88/2.13/1.63 points; patient's pediatric quality of life inventory (PedsQL) of 37/30/31 points; parental PedsQL of 26/27/34 points; and patient's pain visual-analog scale (VAS) of 75/45/40, with no VAS recorded for the mother. Juvenile arthritis functional assessment report (JAFAR) scores of 35/34/8 points were observed. A significant reduction in the taking of NSAIDs was observed. In the second half of the year, the nasal breathing became normal, and remission in chronic rhinitis and adenoiditis was achieved (no infection episodes) without otitis episodes.

Conclusion

Etanercept in mucopolysaccharidosis type 1 is safe and well tolerated. The reduction of joint pain and increased walking capacity were observed. A decreased number of respiratory infection episodes and nasal breathing improvement were noted during the treatment. The observation shows the role of inflammation in the different aspects of MPS. Further investigations on immune system dysregulation in patients with MPS I are needed. Additional studies on the efficacy and safety of anti-rheumatic biological drugs in patients with MPSI are required.

Molecular Mechanisms in Pathophysiology of Mucopolysaccharidosis and Prospects for Innovative Therapy

Mucopolysaccharidoses (MPSs) are a group of inborn errors of the metabolism caused by a deficiency in the lysosomal enzymes required to break down molecules called glycosaminoglycans (GAGs). These GAGs accumulate over time in various tissues and disrupt multiple biological systems, including catabolism of other substances, autophagy, and mitochondrial function. These pathological changes ultimately increase oxidative stress and activate innate immunity and inflammation. We have described the pathophysiology of MPS and activated inflammation in this paper, starting with accumulating the primary storage materials, GAGs. At the initial stage of GAG accumulation, affected tissues/cells are reversibly affected but progress irreversibly to: (1) disruption of substrate degradation with pathogenic changes in lysosomal function, (2) cellular dysfunction, secondary/tertiary accumulation (toxins such as GM2 or GM3 ganglioside, etc.), and inflammatory process, and (3) progressive tissue/organ damage and cell death (e.g., skeletal dysplasia, CNS impairment, etc.). For current and future treatment, several potential treatments for MPS that can penetrate the blood-brain barrier and bone have been proposed and/or are in clinical trials, including targeting peptides and molecular Trojan horses such as monoclonal antibodies attached to enzymes via receptor-mediated transport. Gene therapy trials with AAV, ex vivo LV, and Sleeping Beauty transposon system for MPS are proposed and/or underway as innovative therapeutic options. In addition, possible immunomodulatory reagents that can suppress MPS symptoms have been summarized in this review.

Enhanced Efficiency of the Basal and Induced Apoptosis Process in Mucopolysaccharidosis IVA and IVB Human Fibroblasts

Morquio disease, also called mucopolysaccharidosis IV (MPS IV), belongs to the group of lysosomal storage diseases (LSD). Due to deficiencies in the activities of galactose-6-sulfate sulfatase (in type A) or β-galactosidase (in type B), arising from mutations in GALNS or GLB1, respectively, keratan sulfate (one of glycosaminoglycans, GAGs) cannot be degraded efficiently and accumulates in lysosomes. This primary defect leads to many cellular dysfunctions which then cause specific disease symptoms. Recent works have indicated that different secondary effects of GAG accumulation might significantly contribute to the pathomechanisms of MPS. Apoptosis is among the cellular processes that were discovered to be affected in MPS cells on the basis of transcriptomic studies and some cell biology experiments. However, Morquio disease is the MPS type which is the least studied in light of apoptosis dysregulation, while RNA-seq analyses suggested considerable changes in the expression of genes involved in apoptosis in MPS IVA and IVB fibroblasts. Here we demonstrate that cytochrome c release from mitochondria is more efficient in MPS IVA and IVB fibroblasts relative to control cells, both under the standard cultivation conditions and after treatment with staurosporine, an apoptosis inducer. This indication of apoptosis stimulation was corroborated by measurements of the levels of caspases 9, 3, 6, and 7, as well as PARP, cleaved at specific sites, in Morquio disease and control fibroblasts. The more detailed analyses of the transcriptomic data revealed which genes related to apoptosis are down- and up-regulated in MPS IVA and IVB fibroblasts. We conclude that apoptosis is stimulated in Morquio disease under both standard cell culture conditions and after induction with staurosporine which may contribute to the pathomechanism of this disorder. Dysregulation of apoptosis in other MPS types is discussed.

Femoral Structure and Biomechanical Characteristics in Sanfilippo Syndrome Type-B Mice

Sanfilippo syndrome Type-B, also known as mucopolysaccharidosis IIIB (MPS IIIB), accounts for approximately one-third of all Sanfilippo syndrome patients and is characterized by a similar natural history as Type-A. Patients suffer from developmental regression, bone malformation, organomegaly, GI distress, and profound neurological deficits. Despite human trials of enzyme replacement therapy (ERT) (SBC-103, AX250) in MPS IIIB, there is currently no FDA approved treatment and a few palliative options. The major concerns of ERT and gene therapy for the treatment of bone malformation are the inadequate biodistribution of the missing enzyme, N-acetyl-α-glucosaminidase (NAGLU), and that the skeleton is a poorly hit target tissue in ERT and gene therapy. Each of the four known human types of MPS III (A, B, C, and D) is usually regarded as having mild bone manifestations, yet it remains poorly characterized. This study aimed to determine bone mineral content (BMC), volumetric bone mineral density (vBMD), and biomechanical properties in femurs MPS IIIB C57BL/6 mice compared to phenotypic control C57BL/6 mice. Significant differences were observed in MPS IIIB mice within various cortical and cancellous bone parameters for both males and females (p < 0.05). Here, we establish some osteogenic manifestations of MPS IIIB within the mouse model by radiographic and biomechanical tests, which are also differentially affected by age and sex. This suggests that some skeletal features of the MPS IIIB mouse model may be used as biomarkers of peripheral disease correction for preclinical treatment of MPS IIIB.

Growth patterns in patients with mucopolysaccharidosis VII

Objective

This study assessed growth patterns in patients with mucopolysaccharidosis (MPS) VII before enzyme replacement therapy.

Methods

Height, weight, and body mass index (BMI) measurements and Z-scores from patients from three clinical studies were compared with those from CDC healthy population growth charts. Relationships with age/sex and history of non-immune hydrops fetalis (NIHF) were assessed by linear regression and ANOVA, respectively.

Results

Among 20 enrolled patients with MPS VII, height Z-scores were near normal until 1 year of age but declined thereafter, particularly among males. There was no consistent pattern in weight Z-score. BMI Z-scores were above normal and increased slightly with age among males and were slightly below normal among females. Male patients with a history of NIHF had greater declines in height and weight Z-scores over time versus males without history of NIHF. There was no clear effect of NIHF history on height and weight Z-scores in female patients.

Conclusions

In patients with MPS VII, declines in height Z-score began early in life, particularly among males, while changes in BMI varied by sex. Patients with MPS VII and a history of NIHF had greater declines in height Z-score with age than did patients without a history of NIHF.Clinical trial registration: This retrospective analysis included patients enrolled in an open-label phase 2 study (UX003-CL203; ClinicalTrials.gov, NCT02418455), a randomized, placebo-controlled, blind-start phase 3 study (UX003-CL301; ClinicalTrials.gov, NCT02230566), or its open-label, long-term extension (UX003-CL202; ClinicalTrials.gov, NCT02432144). Requests for individual de-identified participant data and the clinical study report from this study are available to researchers providing a methodologically sound proposal that is in accordance with the Ultragenyx data sharing commitment. To gain access, data requestors will need to sign a data access and use agreement. Data will be shared via secured portal. The study protocol and statistical analysis plan for this study are available on the relevant clinical trial registry websites with the tabulated results.

Inflammatory process and oxidative/nitrative stress: in vivo study in mucopolysaccharidosis type IV A patients under long-term enzyme replacement therapy

Mucopolysaccharidosis type IV A (MPS IVA) is an inborn error of the metabolism (IEM) caused by a deficiency of the enzyme N-acetylgalactosamine 6-sulfate sulfatase (GALNS). Since 2014, enzyme replacement therapy (ERT) is the recommended treatment for these patients. It is known that the inflammatory response is closely related to antioxidant defenses and oxidative stress, and literature shows involvement of oxidative stress in the pathogenesis of IEM. The aim of this study is to investigate the mechanisms of oxidative/nitrative stress and inflammation in patients with MPS IVA under long-term ERT. In the present work we investigate parameters of oxidative/nitrative stress in plasma and urine of MPS IVA patients under long-term ERT and controls, such as plasmatic nitrate/nitrite levels using the LDH Method, urinary di-tyrosine levels by fluorometric method, plasmatic content of sulfhydryl groups, urinary oxidized guanine species by ELISA kit and the plasmatic total antioxidant status. We next evaluated the plasmatic pro and anti-inflammatory cytokines concentration (IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, TNF-α) and the expression of factors and enzymes Nrf-2, NF-κβ and HO-1, main mediators between inflammation and oxidative stress. In concern to the oxidative/nitrative stress parameters, there was no significant difference between the groups MPS IVA patients under long-term ERT and controls, showing that there is no overproducing of RNS, no protein damage, no DNA/RNA oxidative damage and no modification in the non-enzymatic antioxidant capacity of a tissue to prevent the damage associated to free radical processes in these patients. It was also verified no significant difference between the MPS IVA patients under long-term ERT and controls groups regarding the production of proinflammatory cytokines. About anti-inflammatory cytokines, IL 10 was shown to be elevated in MPS IVA patients under long-term ERT in comparison to the control group. We next evaluated the genic expression of Nrf-2, NF-κβ and HO-1and there was no significant difference between the MPS IVA patients under long-term ERT and control groups. In conclusion, MPS IVA patients under long term ERT are not in an inflammatory state and there is no alteration in genic expression in the genes analyzed which are involved in oxidative stress and inflammatory pathways. It is,however, important to consider that absence of imbalance of antioxidant defenses in MPS IVA patients under long term ERT is so far preliminary it is supported by methodologies that are not highly sensitive nor very accurate. Further experiments in future using state-of-the-art methodologies will corroborate these findings. Nevertheless, our results demonstrated the protective effect of the treatment in relation to the parameters studied and the importance of starting treatment in the early stages of the disease.

Mucopolysaccharidosis Type VI with Recurrent Chest Infection

Mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome) is a progressive multi-systemic autosomal recessive disease resulting from a deficiency of arylsulfatase B (N-acetylgalactosamine-4-sulfatase). Here we report the case of a three-year-old male child born full-term via normal vaginal delivery. He had frequent admissions due to a chest infection that started at two months of age. At the age of 23 months, he was admitted after complaining of shortness of breath (SOB) due to asthma and aspiration pneumonia; additionally, dysmorphic features were noticed (single palmar crease, short round toes, coarse facial features such as a flat nose, big lips). A genetic study showed mucopolysaccharidosis VI (MPS VI). At three years of age, he was complaining of cough and SOB. Examination showed wheezing all over the chest, normal first and second heart sounds (S1 and S2), a murmur with no clicks, hepatosplenomegaly, and a palpable left kidney. However, the central nervous system (CNS) and eye examinations were normal. Echocardiography revealed a thickened bicuspid aortic valve, mild aortic regurgitation, and mitral regurgitation. Therefore, the patient presented with different clinical symptoms of MPS VI. It is important to increase the physicians' awareness about MPS by focusing on increasing the probability of MPS as a differential diagnosis whenever patients present with abnormal appearance, limb deformities, and recurrent unexplained infections; hence, making early diagnosis and treatment decisions, leading to a slowing down of the progression of the disease and enhancing the patient's quality of life.

Proteomics identifies novel biomarkers of synovial joint disease in a canine model of mucopolysaccharidosis I

Mucopolysaccharidosis I is a lysosomal storage disorder characterized by deficient alpha-L-iduronidase activity, leading to abnormal accumulation of glycosaminoglycans in cells and tissues. Synovial joint disease is prevalent and significantly reduces patient quality of life. There is a critical need for improved understanding of joint disease pathophysiology in MPS I, including specific biomarkers to predict and monitor joint disease progression, and response to treatment. The objective of this study was to leverage the naturally-occurring MPS I canine model and undertake an unbiased proteomic screen to identify systemic biomarkers predictive of local joint disease in MPS I. Synovial fluid and serum samples were collected from MPS I and healthy dogs at 12 months-of-age, and protein abundance characterized using liquid chromatography tandem mass spectrometry. Stifle joints were evaluated postmortem using magnetic resonance imaging (MRI) and histology. Proteomics identified 40 proteins for which abundance was significantly correlated between serum and synovial fluid, including markers of inflammatory joint disease and lysosomal dysfunction. Elevated expression of three biomarker candidates, matrix metalloproteinase 19, inter-alpha-trypsin inhibitor heavy-chain 3 and alpha-1-microglobulin, was confirmed in MPS I cartilage, and serum abundance of these molecules was found to correlate with MRI and histological degenerative grades. The candidate biomarkers identified have the potential to improve patient care by facilitating minimally-invasive, specific assessment of joint disease progression and response to therapeutic intervention.

Mucopolysaccharidosis: What Pediatric Rheumatologists and Orthopedics Need to Know

Mucopolysaccharidosis (MPS) is a group of disorders caused by the reduced or absent activity of enzymes involved in the glycosaminoglycans (GAGs) degradation; the consequence is the progressive accumulation of the substrate (dermatan, heparan, keratan or chondroitin sulfate) in the lysosomes of cells belonging to several tissues. The rarity, the broad spectrum of manifestations, the lack of strict genotype-phenotype association, and the progressive nature of MPS make diagnosing this group of conditions challenging. Musculoskeletal involvement represents a common and prominent feature of MPS. Joint and bone abnormalities might be the main clue for diagnosing MPS, especially in attenuated phenotypes; therefore, it is essential to increase the awareness of these conditions among the pediatric rheumatology and orthopedic communities since early diagnosis and treatment are crucial to reduce the disease burden of these patients. Nowadays, enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT) are available for some MPS types. We describe the musculoskeletal characteristics of MPS patients through a literature review of MPS cases misdiagnosed as having rheumatologic or orthopedic conditions.

Dose-dependent effects of enzyme replacement therapy on skeletal disease progression in mucopolysaccharidosis VII dogs

Mucopolysaccharidosis (MPS) VII is an inherited lysosomal storage disorder characterized by deficient activity of the enzyme β-glucuronidase. Skeletal abnormalities are common in patients and result in diminished quality of life. Enzyme replacement therapy (ERT) for MPS VII using recombinant human β-glucuronidase (vestronidase alfa) was recently approved for use in patients; however, to date there have been no studies evaluating therapeutic efficacy in a large animal model of MPS VII. The objective of this study was to establish the effects of intravenous ERT, administered at either the standard clinical dose (4 mg/kg) or a high dose (20 mg/kg), on skeletal disease progression in MPS VII using the naturally occurring canine model. Untreated MPS VII animals exhibited progressive synovial joint and vertebral bone disease and were no longer ambulatory by age 6 months. Standard-dose ERT-treated animals exhibited modest attenuation of joint disease, but by age 6 months were no longer ambulatory. High-dose ERT-treated animals exhibited marked attenuation of joint disease, and all were still ambulatory by age 6 months. Vertebral bone disease was recalcitrant to ERT irrespective of dose. Overall, our findings indicate that ERT administered at higher doses results in significantly improved skeletal disease outcomes in MPS VII dogs.

Circulatory C-type natriuretic peptide reduces mucopolysaccharidosis-associated craniofacial hypoplasia in vivo

Skeletal alterations in the head and neck region, such as midfacial hypoplasia, foramen magnum stenosis and spinal canal stenosis, are commonly observed in patients with mucopolysaccharidosis (MPS). However, enzyme replacement therapy (ERT), one of the major treatment approaches for MPS, shows limited efficacy for skeletal conditions. In this study, we analysed the craniofacial morphology of mice with MPS type VII, and investigated the underlying mechanisms promoting jaw deformities in these animals. Furthermore, we investigated the effects of C-type natriuretic peptide (CNP), a potent endochondral ossification promoter, on growth impairment of the craniofacial region in MPS VII mice when administered alone or in combination with ERT. MPS VII mice exhibited midfacial hypoplasia caused by impaired endochondral ossification, and histological analysis revealed increased number of swelling cells in the resting zone of the spheno-occipital synchondrosis (SOS), an important growth centre for craniomaxillofacial skeletogenesis. We crossed MPS VII mice with transgenic mice in which CNP was expressed in the liver under the control of the human serum amyloid-P component promoter, resulting in elevated levels of circulatory CNP. The maxillofacial morphological abnormalities associated with MPS VII were ameliorated by CNP expression, and further prevented by a combination of CNP and ERT. Histological analysis showed that ERT decreased the swelling cell number, and CNP treatment increased the width of the proliferative and hypertrophic zones of the SOS. Furthermore, the foramen magnum and spinal stenoses observed in MPS VII mice were significantly alleviated by CNP and ERT combination. These results demonstrate the therapeutic potential of CNP, which can be used to enhance ERT outcome for MPS VII-associated head and neck abnormalities.

MPSI Manifestations and Treatment Outcome: Skeletal Focus

Mucopolysaccharidosis type I (MPSI) (OMIM #252800) is an autosomal recessive disorder caused by pathogenic variants in the IDUA gene encoding for the lysosomal alpha-L-iduronidase enzyme. The deficiency of this enzyme causes systemic accumulation of glycosaminoglycans (GAGs). Although disease manifestations are typically not apparent at birth, they can present early in life, are progressive, and include a wide spectrum of phenotypic findings. Among these, the storage of GAGs within the lysosomes disrupts cell function and metabolism in the cartilage, thus impairing normal bone development and ossification. Skeletal manifestations of MPSI are often refractory to treatment and severely affect patients’ quality of life. This review discusses the pathological and molecular processes leading to impaired endochondral ossification in MPSI patients and the limitations of current therapeutic approaches. Understanding the underlying mechanisms responsible for the skeletal phenotype in MPSI patients is crucial, as it could lead to the development of new therapeutic strategies targeting the skeletal abnormalities of MPSI in the early stages of the disease.

Comparison of growth dynamics in different types of MPS: an attempt to explain the causes

Background

Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by deficient activity of enzymes responsible for the catabolism of glycosaminoglycans (GAGs), resulting in progressive damage to various tissues and organs. Affected individuals present with skeletal deformities, bone growth impairment, joint stiffness and frequently mental retardation.

Results

The objective of the study was to summarise over 30 years of observations of the growth dynamics in patients with different types of MPS, performed at the Children’s Memorial Health Institute (CMHI, Warsaw, Poland). A retrospective analysis of anthropometric data collected from 1989 to 2020 was performed for 195 patients with MPS I, MPS II, MPS III, MPS IVA and MPS VI. Mean values for birth body length were statistically significantly greater than in the general population. The mean z-scores for other MPS groups showed that until the 24th month of life, the growth pattern for all patients was similar, and the average z-scores for body height were greater than in reference charts. Afterwards, growth patterns began to differentiate for MPS groups.

Conclusions

The long-term follow up showed that the growth pattern in patients with all types of mucopolysaccharidoses significantly deviates from the general population. Patients with MPS IVA had the most severe growth impairments compared to other patients in the study group. Neuropathic MPS I and II demonstrated severe growth impairments compared to other patients in this study. Patients with MPS III showed the mildest growth impairments compared to other MPS patients and reached the 3rd percentile last.

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).

Roles of Chondroitin Sulfate Proteoglycans as Regulators of Skeletal Development

The extracellular matrix (ECM) is critically important for most cellular processes including differentiation, morphogenesis, growth, survival and regeneration. The interplay between cells and the ECM often involves bidirectional signaling between ECM components and small molecules, i.e., growth factors, morphogens, hormones, etc., that regulate critical life processes. The ECM provides biochemical and contextual information by binding, storing, and releasing the bioactive signaling molecules, and/or mechanical information that signals from the cell membrane integrins through the cytoskeleton to the nucleus, thereby influencing cell phenotypes. Using these dynamic, reciprocal processes, cells can also remodel and reshape the ECM by degrading and re-assembling it, thereby sculpting their environments. In this review, we summarize the role of chondroitin sulfate proteoglycans as regulators of cell and tissue development using the skeletal growth plate model, with an emphasis on use of naturally occurring, or created mutants to decipher the role of proteoglycan components in signaling paradigms.

A novel approach in diagnosing multiple dentigerous cysts using CBCT illustration indicative of Mucopolysaccharidosis VI - a case report

Mucopolysaccharidosis VI is a genetic disorder affecting multiple organs with sundry clinical presentations. The main etiological factor reflects the disturbances in mucopolysaccharide metabolism leading to deposition of acid mucopolysaccharide in various tissues. The pathognomonic features of the disease include a large head, short neck, corneal opacity, open mouth associated with an enlarged tongue, enlargement of the skull, and long anteroposterior dimension with unerupted dentition, dentigerous cyst-like follicles, condylar defects, and gingival hyperplasia. An 18-year-old boy with Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI) is described in this article, emphasizing the oral manifestations and radiographic illustration of lesions in the jaws. It also emphasizes the essential role of cone-beam computed tomography to identify and analyze multicentric pathologies in the jaws.

Innate Immunity in Mucopolysaccharide Diseases

Mucopolysaccharidoses are rare paediatric lysosomal storage disorders, characterised by accumulation of glycosaminoglycans within lysosomes. This is caused by deficiencies in lysosomal enzymes involved in degradation of these molecules. Dependent on disease, progressive build-up of sugars may lead to musculoskeletal abnormalities and multi-organ failure, and in others, to cognitive decline, which is still a challenge for current therapies. The worsening of neuropathology, observed in patients following recovery from flu-like infections, suggests that inflammation is highly implicated in disease progression. This review provides an overview of the pathological features associated with the mucopolysaccharidoses and summarises current knowledge regarding the inflammatory responses observed in the central nervous system and periphery. We propose a model whereby progressive accumulation of glycosaminoglycans elicits an innate immune response, initiated by the Toll-like receptor 4 pathway, but also precipitated by secondary storage components. Its activation induces cells of the immune system to release pro-inflammatory cytokines, such as TNF-α and IL-1, which induce progression through chronic neuroinflammation. While TNF-α is mostly associated with bone and joint disease in mucopolysaccharidoses, increasing evidence implicates IL-1 as a main effector of innate immunity in the central nervous system. The (NOD)-like receptor protein 3 inflammasome is therefore implicated in chronic neuroinflammation and should be investigated further to identify novel anti-inflammatory treatments.

Bone Biomarkers in Mucopolysaccharidoses

The accumulation of glycosaminoglycans (GAGs) in bone and cartilage leads to progressive damage in cartilage that, in turn, reduces bone growth by the destruction of the growth plate, incomplete ossification, and growth imbalance. The mechanisms of pathophysiology related to bone metabolism in mucopolysaccharidoses (MPS) include impaired chondrocyte function and the failure of endochondral ossification, which leads to the release of inflammatory cytokines via the activation of Toll-like receptors by GAGs. Although improvements in the daily living of patients with MPS have been achieved with enzyme replacement, treatment for the bone disorder is limited. There is an increasing need to identify biomarkers related to bone and cartilage to evaluate the progressive status and to monitor the treatment of MPS. Recently, new analysis methods, such as proteomic analysis, have identified new biomarkers in MPS. This review summarizes advances in clinical bone metabolism and bone biomarkers.

MPS I: Early diagnosis, bone disease and treatment, where are we now?

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disorder characterized by α-L-iduronidase deficiency. Patients present with a broad spectrum of disease severity ranging from the most severe phenotype (Hurler) with devastating neurocognitive decline, bone disease and early death to intermediate (Hurler-Scheie) and more attenuated (Scheie) phenotypes, with a normal life expectancy. The most severely affected patients are preferably treated with hematopoietic stem cell transplantation, which halts the neurocognitive decline. Patients with more attenuated phenotypes are treated with enzyme replacement therapy. There are several challenges to be met in the treatment of MPS I patients. First, to optimize outcome, early recognition of the disease and clinical phenotype is needed to guide decisions on therapeutic strategies. Second, there is thus far no effective treatment available for MPS I bone disease. The pathophysiological mechanisms behind bone disease are largely unknown, limiting the development of effective therapeutic strategies. This article is a state of the art that comprehensively discusses three of the most urgent open issues in MPS I: early diagnosis of MPS I patients, pathophysiology of MPS I bone disease, and emerging therapeutic strategies for MPS I bone 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.

Enzyme replacement therapy interruption in mucopolysaccharidosis type IVA patients and its impact in different clinical outcomes

Mucopolysaccharidosis type IVA (MPS IVA) is an autosomal recessive lysosomal storage disorder caused by mutations in the GALNS gene, which leads to deficient activity of N-acetylglucosamine-6-sulfate sulfatase. MPS IVA patients usually present skeletal dysplasia, coarse features, short stature, airway obstruction, cervical spinal cord compression, dental abnormalities, and cardiac valvular alterations. Enzyme replacement therapy (ERT) with elosulfase alfa is the only disease-specific treatment available for MPS IVA patients and has been shown to improve important clinical and biochemical parameters; however, little is known about the effects of ERT interruption on these patients. In this article, we report the impact of different periods of treatment interruption on clinical outcomes of 18 MPS IVA patients. All MPS IVA patients included in this case series were treated and followed up in Latin American centers and had been receiving elosulfase alfa intravenously for at least 8 months before ERT was interrupted. Different clinical parameters and assessments were evaluated at variable timepoints following therapy interruption. Altogether, our report indicates that some beneficial ERT effects in MPS IVA patients may last after different periods of treatment interruption, as cardiac and respiratory function improvements. However, worsening of important disease parameters after ERT interruption, such as the increase in uGAGs, pain, joint and skeletal aspects, and surgery indications suggests that treatment discontinuation should be avoided in order to maintain the disease as stable as possible, aiming to optimize these patients' life expectancy and quality of life.

Biomarkers for prediction of skeletal disease progression in mucopolysaccharidosis type I

BACKGROUND

Orthopedic disease progresses in mucopolysaccharidosis type I (MPS I), even with approved therapies and remains a major factor in persistent suffering and disability. Novel therapies and accurate predictors of response are needed. The primary objective of this study was to identify surrogate biomarkers of future change in orthopedic disease.

METHODS

As part of a 9-year observational study of MPS I, range-of-motion (ROM), height, pelvic radiographs were measured annually. Biomarkers in year 1 were compared to healthy controls. Linear regression tested for associations of change in biomarkers over the first year with change in long-term outcomes.

RESULTS

MPS I participants (N = 19) were age 5 to 16 years and on average 6.9 ± 2.9 years post treatment initiation. Healthy controls (N = 51) were age 9 to 17 years. Plasma IL-1β, TNF-α, osteocalcin, pyridinolines, and deoxypyridinolines were higher in MPS than controls. Within MPS, progression of hip dysplasia was present in 46% to 77%. A 1 pg/mL increase in IL-6 was associated with -22°/year change in ROM (-28 to -15; P < .001), a 20 nmol/mmol creatinine/year increase in urine PYD was associated with a -0.024 Z-score/year change in height Z-score (-0.043 to -0.005; P = .016), and a 20 nmol/mmol creatinine/year increase in urine PYD was associated with a -2.0%/year change in hip dysplasia measured by Reimers migration index (-3.8 to -0.1; P = .037).

CONCLUSIONS

Inflammatory cytokines are high in MPS I. IL-6 and PYD were associated with progression in joint contracture, short stature, and hip dysplasia over time. Once validated, these biomarkers may prove useful for predicting response to treatment of skeletal disease in MPS I.

Hip disease in Mucopolysaccharidoses and Mucolipidoses: A review of mechanisms, interventions and future perspectives

The hips are frequently involved in inheritable diseases which affect the bones. The clinical and radiological presentation of these diseases may be very similar to common hip disorders as developmental dysplasia of the hip, osteoarthritis and avascular necrosis, so the diagnosis may be easily overlooked and treatment may be suboptimal. Mucopolysaccharidosis (MPS) and Mucolipidosis (ML II and III) are lysosomal storage disorders with multisystemic involvement. Characteristic skeletal abnormalities, known as dysostosis multiplex, are common in MPS and ML and originate from intra-lysosomal storage of glycosaminoglycans in cells of the cartilage, bones and ligaments. The hip joint is severely affected in MPS and ML. Hip pathology results in limitations in mobility and pain from young age, and negatively affects quality of life. In order to better understand the underlying process that causes hip disease in MPS and ML, this review first describes the normal physiological (embryonic) hip joint development, including the interplay between the acetabulum and the femoral head. In the second part the factors contributing to altered hip morphology and function in MPS and ML are discussed, such as abnormal development of the pelvic- and femoral bones (which results in altered biomechanical forces) and inflammation. In the last part of this review therapeutic options and future perspectives are addressed.

Home treatment of type VI mucopolysaccharidosis (Maroteaux-Lamy syndrome) an alternative at this time of COVID-19 pandemic: A case in Peru

We report a patient with mucopolysaccharidosis type VI, on long-term enzyme replacement home therapy. Results support the efficacy and safety benefits, with additional advantage of home therapy to minimize the risk of community-transmitted infections.

Failures of Endochondral Ossification in the Mucopolysaccharidoses

PURPOSE OF REVIEW

The mucopolysaccharidoses (MPS) are a group of inherited lysosomal storage disorders characterized by abnormal accumulation of glycosaminoglycans (GAGs) in cells and tissues. MPS patients frequently exhibit failures of endochondral ossification during postnatal growth leading to skeletal deformity and short stature. In this review, we outline the current understanding of the cellular and molecular mechanisms underlying failures of endochondral ossification in MPS and discuss associated treatment challenges and opportunities.

RECENT FINDINGS

Studies in MPS patients and animal models have demonstrated that skeletal cells and tissues exhibit significantly elevated GAG storage from early in postnatal life and that this is associated with impaired cartilage-to-bone conversion in primary and secondary ossification centers, and growth plate dysfunction. Recent studies have begun to elucidate the underlying cellular and molecular mechanisms, including impaired chondrocyte proliferation and hypertrophy, diminished growth factor signaling, disrupted cell cycle progression, impaired autophagy, and increased cell stress and apoptosis. Current treatments such as hematopoietic stem cell transplantation and enzyme replacement therapy fail to normalize endochondral ossification in MPS. Emerging treatments including gene therapy and small molecule-based approaches hold significant promise in this regard. Failures of endochondral ossification contribute to skeletal deformity and short stature in MPS patients, increasing mortality and reducing quality of life. Early intervention is crucial for effective treatment, and there is a critical need for new approaches that normalize endochondral ossification by directly targeting affected cells and signaling pathways.

Morquio B Disease. Disease Characteristics and Treatment Options of a Distinct GLB1-Related Dysostosis Multiplex

Morquio B disease (MBD) is an autosomal recessive GLB1-gene-related lysosomal storage disease, presenting with a peculiar type of dysostosis multiplex which is also observed in GALNS-related Morquio A disease. MBD may present as pure skeletal phenotype (pure MBD) or in combination with the neuronopathic manifestations seen in type 2 (juvenile) or type 3 (late onset) GM1 gangliosidosis (MBD plus). The main skeletal features are progressive growth impairment, kyphoscoliosis, coxa/genua valga, joint laxity, platyspondyly and odontoid hypoplasia. The main neuronopathic features are dystonia, ataxia, and intellectual/developmental/speech delay. Spinal cord compression occurs as a complication of spinal dysostosis. Chronic pain is reported, along with mobility issues and challenges with daily living and self-care activities, as the most common health concern. The most commonly reported orthopedic surgeries are hip and knee replacements. Keratan sulphate-derived oligosaccharides are characteristic biomarkers. Residual β-galactosidase activities measured against synthetic substrates do not correlate with the phenotype. W273 L and T500A are the most frequently observed GLB1 variants in MBD, W273L being invariably associated with pure MBD. Cytokines play a role in joint destruction and pain, providing a promising treatment target. In the future, patients may benefit from small molecule therapies, and gene and enzyme replacement therapies, which are currently being developed for GM1 gangliosidosis.

Mucopolysaccharidosis Type I: A Review of the Natural History and Molecular Pathology

Mucopolysaccharidosis type I (MPS I) is a rare autosomal recessive inherited disease, caused by deficiency of the enzyme α-L-iduronidase, resulting in accumulation of the glycosaminoglycans (GAGs) dermatan and heparan sulfate in organs and tissues. If untreated, patients with the severe phenotype die within the first decade of life. Early diagnosis is crucial to prevent the development of fatal disease manifestations, prominently cardiac and respiratory disease, as well as cognitive impairment. However, the initial symptoms are nonspecific and impede early diagnosis. This review discusses common phenotypic manifestations in the order in which they develop. Similarities and differences in the three animal models for MPS I are highlighted. Earliest symptoms, which present during the first 6 months of life, include hernias, coarse facial features, recurrent rhinitis and/or upper airway obstructions in the absence of infection, and thoracolumbar kyphosis. During the next 6 months, loss of hearing, corneal clouding, and further musculoskeletal dysplasias develop. Finally, late manifestations including lower airway obstructions and cognitive decline emerge. Cardiac symptoms are common in MPS I and can develop in infancy. The underlying pathogenesis is in the intra- and extracellular accumulation of partially degraded GAGs and infiltration of cells with enlarged lysosomes causing tissue expansion and bone deformities. These interfere with the proper arrangement of collagen fibrils, disrupt nerve fibers, and cause devastating secondary pathophysiological cascades including inflammation, oxidative stress, and other disruptions to intracellular and extracellular homeostasis. A greater understanding of the natural history of MPS I will allow early diagnosis and timely management of the disease facilitating better treatment outcomes.

Odiparcil, a potential glycosaminoglycans clearance therapy in mucopolysaccharidosis VI-Evidence from in vitro and in vivo models

Mucopolysaccharidoses are a class of lysosomal storage diseases, characterized by enzymatic deficiency in the degradation of specific glycosaminoglycans (GAG). Pathological accumulation of excess GAG leads to multiple clinical symptoms with systemic character, most severely affecting bones, muscles and connective tissues. Current therapies include periodic intravenous infusion of supplementary recombinant enzyme (Enzyme Replacement Therapy–ERT) or bone marrow transplantation. However, ERT has limited efficacy due to poor penetration in some organs and tissues. Here, we investigated the potential of the β-D-xyloside derivative odiparcil as an oral GAG clearance therapy for Maroteaux–Lamy syndrome (Mucopolysaccharidosis type VI, MPS VI). In vitro, in bovine aortic endothelial cells, odiparcil stimulated the secretion of sulphated GAG into culture media, mainly of chondroitin sulphate (CS) /dermatan sulphate (DS) type. Efficacy of odiparcil in reducing intracellular GAG content was investigated in skin fibroblasts from MPS VI patients where odiparcil was shown to reduce efficiently the accumulation of intracellular CS with an EC₅₀ in the range of 1 μM. In vivo, in wild type rats, after oral administrations, odiparcil was well distributed, achieving μM concentrations in MPS VI disease-relevant tissues and organs (bone, cartilage, heart and cornea). In MPS VI Arylsulphatase B deficient mice (Arsb^-), after chronic oral administration, odiparcil consistently stimulated the urinary excretion of sulphated GAG throughout the treatment period and significantly reduced tissue GAG accumulation in liver and kidney. Furthermore, odiparcil diminished the pathological cartilage thickening observed in trachea and femoral growth plates of MPS VI mice. The therapeutic efficacy of odiparcil was similar in models of early (treatment starting in juvenile, 4 weeks old mice) or established disease (treatment starting in adult, 3 months old mice). Our data demonstrate that odiparcil effectively diverts the synthesis of cellular glycosaminoglycans into secreted soluble species and this effect can be used for reducing cellular and tissue GAG accumulation in MPS VI models. Therefore, our data reveal the potential of odiparcil as an oral GAG clearance therapy for MPS VI patients.

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.

Large animal models contribute to the development of therapies for central and peripheral nervous system dysfunction in patients with lysosomal storage diseases

Lysosomal storage diseases (LSDs) are a group of 70 monogenic disorders characterized by the lysosomal accumulation of a substrate. As a group, LSDs affect ~1 in 5000 live births; however, each individual storage disease is rare, limiting the ability to perform natural history studies or to perform clinical trials. Perhaps in no other biomedical field have naturally occurring large animal (canine, feline, ovine, caprine, and bovine) models been so essential for understanding the fundamentals of disease pathogenesis and for developing safe and effective therapies. These models were critical for the development of hematopoietic stem cell transplantation in α- and β- mannosidosis, fucosidosis, and the mucopolysaccharidoses; enzyme replacement therapy for fucosidosis, the mucopolysaccharidoses, and neuronal ceroid lipofuscinosis; and small molecule therapy in Niemann-Pick type C disease. However, their most notable contributions to the biomedical field are in the development of gene therapy for LSDs. Adeno-associated viral vectors to treat nervous system disease have been evaluated in the large animal models of α-mannosidosis, globoid cell leukodystrophy, GM1 and GM2 gangliosidosis, the mucopolysaccharidoses, and neuronal ceroid lipofuscinosis. This review article will summarize the large animal models available for study as well as their contributions to the development of central and peripheral nervous system dysfunction in LSDs.

Cell cycle progression is disrupted in murine MPS VII growth plate leading to reduced chondrocyte proliferation and transition to hypertrophy

Endochondral bone growth is abnormal in 6 of the 11 types of mucopolysaccharidoses (MPS) disorders; resulting in short stature, reduced size of the thoracic cavity and compromised manual dexterity. Current therapies for MPS have had a limited effect on bone growth and to improve these therapies or develop adjunct approaches requires an understanding of the underlying basis of abnormal bone growth in MPS. The MPS VII mouse model replicates the reduction in long bone and vertebral length observed in human MPS. Using this model we have shown that the growth plate is elongated but contains fewer chondrocytes in the proliferative and hypertrophic zones. Endochondral bone growth is in part regulated by entry and exit from the cell cycle by growth plate chondrocytes. More MPS VII chondrocytes were positive for Ki67, a marker for active phases of the cell cycle, suggesting that more MPS VII chondrocytes were in the cell cycle. The number of cells positive for phosphorylated histone H3 was significantly reduced in MPS VII chondrocytes, suggesting fewer MPS VII chondrocytes progressed to mitotic division. While MPS VII HZ chondrocytes continued to express cyclin D1 and more cells were positive for E2F1 and phos pRb than normal, fewer MPS VII HZ chondrocytes were positive for p57^kip2 a marker of terminal differentiation, suggesting fewer MPS VII chondrocytes were able to exit the cell cycle. In addition, multiple markers typical of PZ to HZ transition were not downregulated in MPS VII, in particular Sox9, Pthrpr and Wnt5a. These findings are consistent with MPS VII growth plates elongating at a slower rate than normal due to a delay in progression through the cell cycle, in particular the transition between G1 and S phases, leading to both reduced cell division and transition to the hypertrophic phenotype.

Safety Study of Sodium Pentosan Polysulfate for Adult Patients with Mucopolysaccharidosis Type II

Current therapies for the mucopolysaccharidoses (MPS) do not effectively address skeletal and neurological manifestations. Pentosan polysulfate (PPS) is an alternative treatment strategy that has been shown to improve bone architecture, mobility, and neuroinflammation in MPS animals. The aims of this study were to a) primarily establish the safety of weekly PPS injections in attenuated MPS II, b) assess the efficacy of treatment on MPS pathology, and c) define appropriate clinical endpoints and biomarkers for future clinical trials. Subcutaneous injections were administered to three male Japanese patients for 12 weeks. Enzyme replacement therapy was continued in two of the patients while they received PPS and halted for two months in one patient before starting PPS. During treatment, one patient experienced an elevation of alanine transaminase, and another patient experienced convulsions; however, these incidences were non-cumulative and unrelated to PPS administration, respectively. Overall, the drug was well-tolerated in all patients, and no serious drug-related adverse events were noted. Generally, PPS treatment led to an increase in several parameters of shoulder range of motion and decrease of the inflammatory cytokines, MIF and TNF-α, which are potential clinical endpoints and biomarkers, respectively. Changes in urine and serum glycosaminoglycans were inconclusive. Overall, this study demonstrates the safety of using PPS in adults with MPS II and suggests the efficacy of PPS on MPS pathology with the identification of potential clinical endpoints and biomarkers.

Respiratory complications of metabolic disease in the paediatric population: A review of presentation, diagnosis and therapeutic options

Inborn errors of metabolism (IEMs) whilst individually rare, as a group constitute a field which is increasingly demands on pulmonologists. With the advent of new therapies such as enzyme replacement and gene therapy, early diagnosis and treatment of these conditions can impact on long term outcome, making their timely recognition and appropriate investigation increasingly important. Conversely, with improved treatment, survival of these patients is increasing, with the emergence of previously unknown respiratory phenotypes. It is thus important that pulmonologists are aware of and appropriately monitor and manage these complications. This review aims to highlight the respiratory manifestations which can occur. It isdivided into conditions resulting primarily in obstructive airway and lung disease, restrictive lung disease such as interstitial lung disease or pulmonary alveolar proteinosis and pulmonary hypertension, whilst acknowledging that some diseases have the potential to cause all three. The review focuses on general phenotypes of IEMs, their known respiratory complications and the basic metabolic investigations which should be performed where an IEM is suspected.

Therapeutic Options for Mucopolysaccharidoses: Current and Emerging Treatments

Mucopolysaccharidoses (MPS) are inborn errors of metabolism produced by a deficiency of one of the enzymes involved in the degradation of glycosaminoglycans (GAGs). Although taken separately, each type is rare. As a group, MPS are relatively frequent, with an overall estimated incidence of around 1 in 20,000-25,000 births. Development of therapeutic options for MPS, including hematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy (ERT), has modified the natural history of many MPS types. In spite of the improvement in some tissues and organs, significant challenges remain unsolved, including blood-brain barrier (BBB) penetration and treatment of lesions in avascular cartilage, heart valves, and corneas. Newer approaches, such as intrathecal ERT, ERT with fusion proteins to cross the BBB, gene therapy, substrate reduction therapy (SRT), chaperone therapy, and some combination of these strategies may provide better outcomes for MPS patients in the near future. As early diagnosis and early treatment are imperative to improve therapeutic efficacy, the inclusion of MPS in newborn screening programs should enhance the potential impact of treatment in reducing the morbidity associated with MPS diseases. In this review, we evaluate available treatments, including ERT and HSCT, and future treatments, such as gene therapy, SRT, and chaperone therapy, and describe the advantages and disadvantages. We also assess the current clinical endpoints and biomarkers used in clinical trials.

Proteomic approaches in the discovery of potential urinary biomarkers of mucopolysaccharidosis type II

Mucopolysaccharindosis type II (MPS II) is a rare lysosomal storage disorder caused by deficient or absent activity of the iduronate-2-sulfatase (IDS) enzyme, which leads to pathological accumulation of the glycosaminoglycans(GAGs). The absence of early diagnosis can result in irreversible developmental, neurological, and physiological damage. The lack of clear understanding of the etiology of physiological dysfunction in MPS II has been a major obstacle to the development of new treatment. Therefore, a reliable biomarker for early diagnosis and exploration of pathogenic mechanism are of great importance. Proteomics provides powerful tool for protein expression alterations and study of complicated pathological process. This study was performed to identify the differential protein profile in urine of MPS II patients using two-dimensional gel electrophoresis(2D-PAGE)combining with MALDI-TOF/TOF and a total of 15 differentially expressed proteins were identified. Content of alpha1-antitrypsin, Gm2 activator and lipocalin-type prostaglandin D synthase was measured by ELISA method. The value of urinary α1-AT/Cr in MPS II group was 0.79 ± 0.10 mg/mmol, significantly higher than 0.42 ± 0.05 mg/mmol in healthy control group; whereas the value of GM2A/Cr and L-PGDS/Cr in MPS II group was 1.30 ± 0.12 μg/mmol and 9.86 ± 1.16 ng/mmol respectively, which was significantly lower than 2.19 ± 0.19 μg/mmol and 13.98 ± 1.48 ng/mmol in healthy control group. The proteins can be considered as accessory diagnostic biomarkers for MPS II. This approach helped to discover early diagnostic markers and provided a better understanding of the pathogenic mechanism of MPS II.

Biomarkers in patients with mucopolysaccharidosis type II and IV

Glycosaminoglycans (GAGs), dermatan sulfate (DS), heparan sulfate (HS), and keratan sulfate (KS), are the primary biomarkers in patients with mucopolysaccharidoses (MPS); however, little is known about other biomarkers. To explore potential biomarkers and their correlation with GAGs, blood samples were collected from 46 MPS II patients, 34 MPS IVA patients, and 5 MPS IVB patients. We evaluated the levels of 8 pro-inflammatory factors (EGF, IL-1β, IL-6, MIP-1α, TNF-α, MMP-1, MMP-2, and MMP-9), collagen type II, and DS, HS (HS0S, HSNS), and KS (mono-sulfated, di-sulfated) in blood. Eight biomarkers measured were significantly elevated in untreated MPS II patients, compared with those in normal controls: EGF, IL-1β, IL-6, HS0S, HSNS, DS, mono-sulfated KS, and di-sulfated KS. The same eight biomarkers remained elevated in ERT-treated patients. However, only three biomarkers remained elevated in post-HSCT MPS II patients: EGF, mono-sulfated KS, and di-sulfated KS. Post-HSCT patients with MPS II showed that IL-1β and IL-6 were normalized as HS and DS levels decreased. Eight biomarkers were significantly elevated in untreated MPS IVA patients: EGF, IL-1β, IL-6, MIP-1α, MMP-9, HSNS, mono-sulfated KS, and di-sulfated KS, and four biomarkers were elevated in MPS IVA patients under ERT: IL-6, TNF-α, mono-sulfated KS, and di-sulfated KS. There was no reduction of KS in the ERT-treated MPS IVA patient, compared with untreated patients. Two biomarkers were significantly elevated in untreated MPS IVB patients: IL-6 and TNF-α. Reversely, collagen type II level was significantly decreased in untreated and ERT-treated MPS II patients and untreated MPS IVA patients. In conclusion, selected pro-inflammatory factors can be potential biomarkers in patients with MPS II and IV as well as GAGs levels.

Recommendations for the management of MPS VI: systematic evidence- and consensus-based guidance

Introduction

Mucopolysaccharidosis (MPS) VI or Maroteaux-Lamy syndrome (253200) is an autosomal recessive lysosomal storage disorder caused by deficiency in N-acetylgalactosamine-4-sulfatase (arylsulfatase B). The heterogeneity and progressive nature of MPS VI necessitates a multidisciplinary team approach and there is a need for robust guidance to achieve optimal management. This programme was convened to develop evidence-based, expert-agreed recommendations for the general principles of management, routine monitoring requirements and the use of medical and surgical interventions in patients with MPS VI.

Methods

26 international healthcare professionals from various disciplines, all with expertise in managing MPS VI, and three patient advocates formed the Steering Committee group (SC) and contributed to the development of this guidance. Members from six Patient Advocacy Groups (PAGs) acted as advisors and attended interviews to ensure representation of the patient perspective. A modified-Delphi methodology was used to demonstrate consensus among a wider group of healthcare professionals with expertise and experience managing patients with MPS VI and the manuscript has been evaluated against the validated Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument by three independent reviewers.

Results

A total of 93 guidance statements were developed covering five domains: (1) general management principles; (2) recommended routine monitoring and assessments; (3) enzyme replacement therapy (ERT) and hematopoietic stem cell transplantation (HSCT); (4) interventions to support respiratory and sleep disorders; (5) anaesthetics and surgical interventions. Consensus was reached on all statements after two rounds of voting. The greatest challenges faced by patients as relayed by consultation with PAGs were deficits in endurance, dexterity, hearing, vision and respiratory function. The overall guideline AGREE II assessment score obtained for the development of the guidance was 5.3/7 (where 1 represents the lowest quality and 7 represents the highest quality of guidance).

Conclusion

This manuscript provides evidence- and consensus-based recommendations for the management of patients with MPS VI and is for use by healthcare professionals that manage the holistic care of patients with the intention to improve clinical- and patient-reported outcomes and enhance patient quality of life. It is recognised that the guidance provided represents a point in time and further research is required to address current knowledge and evidence gaps.

Electronic supplementary material

The online version of this article (10.1186/s13023-019-1080-y) contains supplementary material, which is available to authorized users.

FGF signaling deregulation is associated with early developmental skeletal defects in animal models for mucopolysaccharidosis type II (MPSII)

Skeletal abnormalities represent a major clinical burden in patients affected by the lysosomal storage disorder mucopolysaccharidosis type II (MPSII, OMIM #309900). While extensive research has emphasized the detrimental role of stored glycosaminoglycans (GAGs) in the bone marrow (BM), a limited understanding of primary cellular mechanisms underlying bone defects in MPSII has hampered the development of bone-targeted therapeutic strategies beyond enzyme replacement therapy (ERT). We here investigated the involvement of key signaling pathways related to the loss of iduronate-2-sulfatase activity in two different MPSII animal models, D. rerio and M. musculus. We found that FGF pathway activity is impaired during early stages of bone development in IDS knockout mice and in a newly generated Ids mutant fish. In both models the FGF signaling deregulation anticipated a slow but progressive defect in bone differentiation, regardless of any extensive GAGs storage. We also show that MPSII patient fibroblasts harboring different mutations spanning the IDS gene exhibit perturbed FGF signaling-related markers expression. Our work opens a new venue to discover possible druggable novel key targets in MPSII.

Recent trends in mucopolysaccharidosis research

Mucopolysaccharidosis (MPS) is a group of inherited conditions involving metabolic dysfunction. Lysosomal enzyme deficiency leads to the accumulation of glycosaminoglycan (GAG) resulting in systemic symptoms, and is categorized into seven types caused by deficiency in one of eleven different enzymes. The pathophysiological mechanism of these diseases has been investigated, indicating impaired autophagy in neuronal damage initiation, association of activated microglia and astrocytes with the neuroinflammatory processes, and involvement of tauopathy. A new inherited error of metabolism resulting in a multisystem disorder with features of the MPS was also identified. Additionally, new therapeutic methods are being developed that could improve conventional therapies, such as new recombinant enzymes that can penetrate the blood brain barrier, hematopoietic stem cell transplantation with reduced intensity conditioning, gene therapy using a viral vector system or gene editing, and substrate reduction therapy. In this review, we discuss the recent developments in MPS research and provide a framework for developing strategies.

Clinical presentation and diagnosis of mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are estimated to affect1 in 25,000 live births although specific rates vary between the ethnic origin and country. MPS are a group of lysosomal storage disorders, which cause the buildup of GAG(s) due to insufficient or absent GAG-degrading enzymes. With seven types of MPS disorders and eleven subtypes, the MPS family presents unique challenges for early clinical diagnosis due to the molecular and clinical heterogeneity between groups and patients. Novel methods of early identification, particularly newborn screening through mass spectrometry, can change the flow of diagnosis, allowing enzyme and GAG quantification before the presentation of clinical symptoms improving outcomes. Genetic testing of patients and their families can also be conducted preemptively. This testing enables families to make informed decisions about family planning, leading to prenatal diagnosis. In this review, we discuss the clinical symptoms of each MPS type as they initially appear in patients, biochemical and molecular diagnostic methods, and the future of newborn screening for this group of disorders.

Recommendations for Evaluation and Management of Pain in Patients With Mucopolysaccharidosis in Latin America

The mucopolysaccharidosis (MPS) constitutes a heterogeneous group of rare genetic disorders caused by enzymatic deficiencies that lead to the accumulation of glycosaminoglycans. Several types of MPS are described, historically numbered from I to IX. Clinical observations strongly suggest the presence of chronic pain in patients with all types of MPS. There are few data in the literature on the evaluation and management of pain in these patients, a fact that can compromise the quality of life even more. Professionals with extensive experience in the care for patients with MPS held a meeting in April 2017 to discuss and propose recommendations for the evaluation and management of pain in patients with MPS in Latin America. This article summarizes the content of the discussions and presents the recommendations produced at the meeting. Patients with MPS present joint, bone, and muscle pain, as well as entrapment syndromes (spinal, optic nerve, carpal tunnel). The panel suggests the use of the following instruments for pain assessment: Face, Legs, Activity, Cry and Consolability Scale for children of up to four years of age and patients unable to communicate their pain; Child Health Assessment Questionnaire Scale; Facial Pain Scale and Numerical Pain Scale for patients of five to <18 years of age; Brief Pain Inventory and Short Form Health Survey 36 scales for patients aged 18 years or older. Based on the scores verified in these scales, the panel proposes pharmacological interventions for pain relief in this population of patients.

Growth impairment in mucopolysaccharidoses

Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders that affect regulation of glycosaminoglycan (GAG) processing. In MPS, the lysosomes cannot efficiently break down GAGs, and the specific GAGs accumulated depend on the type of MPS. The level of impairment of breakdown varies between patients, making this one of the many factors that lead to a range of clinical presentations even in the same type of MPS. These clinical presentations usually involve skeletal dysplasia, in which the most common feature is bone growth impairment and successive short stature. Growth impairment occurs due to the deposition and retention of GAGs in bone and cartilage. The accumulation of GAGs in these tissues leads to progressive damage in cartilage that in turn reduces bone growth by destruction of the growth plate, incomplete ossification, and imbalance of growth. Imbalance of growth leads to various skeletal abnormalities including disproportionate dwarfism with short neck and trunk, prominent forehead, rigidity of joints, tracheal obstruction, kyphoscoliosis, pectus carinatum, platyspondyly, round-shaped vertebral bodies or beaking sign, underdeveloped acetabula, wide flared iliac, coxa valgus, flattered capital femoral epiphyses, and genu valgum. If left untreated, skeletal abnormalities including growth impairment result in a significant impact on these patients' quality of life and activity of daily living, leading to high morbidity and severe handicap. This review focuses on growth impairment in untreated patients with MPS. We comprehensively describe the growth abnormalities through height, weight, growth velocity, and BMI in each type of MPS and compare the status of growth with healthy age-matched controls. The timing, the degree, and the difference in growth impairment of each MPS are highlighted to understand the natural course of growth and to evaluate future therapeutic efficacy.

WITHDRAWN: Recommendations for evaluation and management of pain in patients with mucopolysaccharidosis in Latin America

The Publisher regrets that this article is an accidental duplication of an article that has already been published, https://doi.org/10.1016/j.jpainsymman.2018.03.023. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Lysosomal enzyme replacement therapies: Historical development, clinical outcomes, and future perspectives

Lysosomes and lysosomal enzymes play a central role in numerous cellular processes, including cellular nutrition, recycling, signaling, defense, and cell death. Genetic deficiencies of lysosomal components, most commonly enzymes, are known as "lysosomal storage disorders" or "lysosomal diseases" (LDs) and lead to lysosomal dysfunction. LDs broadly affect peripheral organs and the central nervous system (CNS), debilitating patients and frequently causing fatality. Among other approaches, enzyme replacement therapy (ERT) has advanced to the clinic and represents a beneficial strategy for 8 out of the 50-60 known LDs. However, despite its value, current ERT suffers from several shortcomings, including various side effects, development of "resistance", and suboptimal delivery throughout the body, particularly to the CNS, lowering the therapeutic outcome and precluding the use of this strategy for a majority of LDs. This review offers an overview of the biomedical causes of LDs, their socio-medical relevance, treatment modalities and caveats, experimental alternatives, and future treatment perspectives.

Pilot study of the safety and effect of adalimumab on pain, physical function, and musculoskeletal disease in mucopolysaccharidosis types I and II

Mucopolysaccharidosis I and II are lysosomal storage disorders that, despite treatment with hematopoietic cell transplantation (HCT) and/or enzyme replacement therapy (ERT), continue to cause significant skeletal abnormalities leading to pain, stiffness, physical dysfunction, and short stature. Tumor necrosis factor – alpha (TNF-α) is elevated in individuals with MPS I and II and associated with pain and physical dysfunction. Therefore, we evaluated the safety and effects of the TNF-α inhibitor adalimumab in patients with MPS I and II in a 32-week, randomized, double blind, placebo-controlled, crossover study of adalimumab at a dose of 20 mg (weight 15–<30 kg) or 40 mg (weight ≥ 30 kg) administered subcutaneously every other week or saline placebo for 16 weeks. Participants were evaluated at baseline, week 16, and week 32 with the Children's Health Questionnaire – Parent Form 50 (CHQ-PF50), the Pediatric Pain Questionnaire (PPQ), range-of-motion (ROM) measurements, anthropometry, six-minute walk test (6MWT), hand dynamometer, and laboratory evaluations for safety. The primary outcome was safety and primary efficacy outcome was bodily pain (BP) measured by the CHQ-PF50. Two subjects, one with MPS I and one with MPS II, completed the study. Adalimumab was well tolerated and there were no serious adverse events. Standardized BP scores for age and gender were higher (i.e. less pain) at the end of the treatment versus placebo phase for both subjects. Subject #1 became unblinded during treatment due to skin erythema. Behavior measured by both CHQ-PF50 and parental report improved during treatment compared to placebo in both subjects. ROM improved by > 5° in seven of eight joints in Subject #1 and five of eight joints in Subject #2 (range 7.0° to 52.8°). There was no change in the PPQ, 6MWT, or hand dynamometer. Data from this small pilot study suggest that treatment with adalimumab is safe, tolerable, and may improve ROM, physical function, and possibly pain, in children with MPS I or II. However, additional clinical trials are needed before this therapy should be recommended as part of clinical care.

Macrophages in oxidative stress and models to evaluate the antioxidant function of dietary natural compounds

Antioxidant testing of natural products has attracted increasing interest in recent years, mainly due to the fact that an antioxidant-rich diet might provide health benefits. Activated macrophages are a major source of reactive oxygen species, reactive nitrogen species, and peroxynitrite generated through the so-called respiratory burst. Constitutively released proinflammatory cytokine, especially tumor necrosis factor-α, triggers nuclear factor-κB, and activator protein-1 translocation leading to the over production of reactive oxygen species and reactive nitrogen species in macrophages. Activation of transcription factors in the long-lived tissue-resident macrophages and/or monocyte-derived macrophages, trigger epigenetic modifications leading to the pathogenesis of chronic diseases. Nutraceuticals including lipid raft structure disruption agent, cholesterol depletion agent, farnesyltransferase inhibitor, nuclear factor-κB blocker (α,β-unsaturated carbonyl compounds), glucocorticoid receptor agonist, and peroxisome proliferator-activated receptor-γ agonist have long been used to inactive macrophage. The inhibition effects on the formation of nitric oxide, superoxide, and nitrite peroxide may be responsible for the anti-inflammatory functionalities. Activated macrophage models could be used to identify the active components for functional diets development through a multiple targets strategy.

Pathogenesis and treatment of spine disease in the mucopolysaccharidoses

The mucopolysaccharidoses (MPS) are a family of lysosomal storage disorders characterized by deficient activity of enzymes that degrade glycosaminoglycans (GAGs). Skeletal disease is common in MPS patients, with the severity varying both within and between subtypes. Within the spectrum of skeletal disease, spinal manifestations are particularly prevalent. Developmental and degenerative abnormalities affecting the substructures of the spine can result in compression of the spinal cord and associated neural elements. Resulting neurological complications, including pain and paralysis, significantly reduce patient quality of life and life expectancy. Systemic therapies for MPS, such as hematopoietic stem cell transplantation and enzyme replacement therapy, have shown limited efficacy for improving spinal manifestations in patients and animal models. Therefore, there is a pressing need for new therapeutic approaches that specifically target this debilitating aspect of the disease. In this review, we examine how pathological abnormalities affecting the key substructures of the spine - the discs, vertebrae, odontoid process and dura - contribute to the progression of spinal deformity and symptomatic compression of neural elements. Specifically, we review current understanding of the underlying pathophysiology of spine disease in MPS, how the tissues of the spine respond to current clinical and experimental treatments, and discuss future strategies for improving the efficacy of these treatments.

Can Macrosomia or Large for Gestational Age Be Predictive of Mucopolysaccharidosis Type I, II and VI?

BACKGROUND

The objective of the study was to compare mean values for birth body length and weight between patients with mucopolysaccharidosis (MPS) and the general population.

METHODS

A retrospective analysis of birth anthropometric data was performed for patients (n = 103) with MPS I, II, and VI. Two-tailed t tests were used to compare mean values for body length and weight at birth between patients with MPS and the general population.

RESULTS

Mean values for birth body length and weight for all studied groups were greater than in the general population. For body length the differences were statistically significant. When considered individually, 53% of patients were large for gestational age (LGA) and 30% were macrosomic. The highest percentage of LGA was observed in MPS II males and MPS VI females (55% and 56%, respectively), while the highest percentage of macrosomia was observed in MPS VI males (36%).

CONCLUSION

At the time of birth, MPS patients were larger than those in the general population. High birth weight and/or LGA can be suggestive of MPS disease and should raise suspicion aiding early disease recognition.