Immune-Mediated Inflammation May Contribute to the Pathogenesis of Cardiovascular Disease in Mucopolysaccharidosis Type I

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.

Decreased Levels of Chaperones in Mucopolysaccharidoses and Their Elevation as a Putative Auxiliary Therapeutic Approach

Mucopolysaccharidoses (MPS) are rare genetic disorders belonging to the lysosomal storage diseases. They are caused by mutations in genes encoding lysosomal enzymes responsible for degrading glycosaminoglycans (GAGs). As a result, GAGs accumulate in lysosomes, leading to impairment of cells, organs and, consequently, the entire body. Many of the therapies proposed thus far require the participation of chaperone proteins, regardless of whether they are therapies in common use (enzyme replacement therapy) or remain in the experimental phase (gene therapy, STOP-codon-readthrough therapy). Chaperones, which include heat shock proteins, are responsible for the correct folding of other proteins to the most energetically favorable conformation. Without their appropriate levels and activities, the correct folding of the lysosomal enzyme, whether supplied from outside or synthesized in the cell, would be impossible. However, the baseline level of nonspecific chaperone proteins in MPS has never been studied. Therefore, the purpose of this work was to determine the basal levels of nonspecific chaperone proteins of the Hsp family in MPS cells and to study the effect of normalizing GAG concentrations on these levels. Results of experiments with fibroblasts taken from patients with MPS types I, II, IIIA, IIIB, IIIC, IID, IVA, IVB, VI, VII, and IX, as well as from the brains of MPS I mice (Idua^-/-), indicated significantly reduced levels of the two chaperones, Hsp70 and Hsp40. Interestingly, the reduction in GAG levels in the aforementioned cells did not lead to normalization of the levels of these chaperones but caused only a slight increase in the levels of Hsp40. An additional transcriptomic analysis of MPS cells indicated that the expression of other genes involved in protein folding processes and the cell response to endoplasmic reticulum stress, resulting from the appearance of abnormally folded proteins, was also modulated. To summarize, reduced levels of chaperones may be an additional cause of the low activity or inactivity of lysosomal enzymes in MPS. Moreover, this may point to causes of treatment failure where the correct structure of the enzyme supplied or synthesized in the cell is crucial to lower GAG levels.

Drug Repositioning Applied to Cardiovascular Disease in Mucopolysaccharidosis

Mucopolysaccharidoses (MPS) are genetic metabolic diseases characterized by defects in the activity of lysosomal hydrolases. In MPS, secondary cell disturbance affects pathways related to cardiovascular disorders. Hence, the study aimed to identify MPS-related drugs targeting cardiovascular disease and select a list of drugs for repositioning. We obtained a list of differentially expressed genes and pathways. To identify drug perturbation-driven gene expression and drug pathways interactions, we used the CMAP and LINCS databases. For molecular docking, we used the DockThor web server. Our results suggest that pirfenidone and colchicine are promising drugs to treat cardiovascular disease in MPS patients. We also provide a brief description of good practices for the repositioning analysis. Furthermore, the list of drugs and related MPS-enriched genes could be helpful to new treatments and considered for pathophysiological studies.

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).

Multimodal ocular imaging of known and novel corneal stromal disorders in dogs

Background

Imaging features obtained with Fourier-domain optical coherence tomography (FD-OCT) and in vivo confocal microscopy (IVCM) for corneal stromal disorders have been sparsely reported in dogs. This case report is a compilation of imaging features for three cases of different stromal disorders of the canine cornea which have not yet been reported elsewhere.

Case presentation

Lipid deposition in case 1 appeared as needle-shaped hyperreflective lines along the collagen lamellae, which correlated histologically with lipid clefts. In case 2, glycosaminoglycan accumulation by mucopolysaccharidosis type 1 caused diffuse stromal hyperreflectivity and depletion of keratocytes on IVCM and was associated with secondary corneal degeneration presumed to be calcium deposition. In case 3, posterior corneal stromal opacities in the absence of ocular inflammation were identified. Hyperreflective particles were scattered in the middle and posterior corneal stroma on FD-OCT. With IVCM, hyperreflective deposits were identified within keratocytes and the number of enlarged keratocytes containing hyperreflective deposits increased towards the posterior stroma. The bilateral, non-inflammatory nature and unique appearance with IVCM is most consistent with a posterior stromal dystrophy reminiscent of pre-Descemet corneal dystrophy described in humans.

Conclusions

In vivo multimodal corneal imaging facilitated instantaneous microstructural analysis and may be valuable in the differential diagnosis of corneal stromal disorders in veterinary clinical practice. The non-specific nature of imaging findings occurs in some conditions such as mucopolysaccharidosis, thus in vivo corneal imaging should be complemented with other gold standard methods of definitive diagnosis.

A modified density gradient proteomic-based method to analyze endolysosomal proteins in cardiac tissue

The importance of lysosomes in cardiac physiology and pathology is well established, and evidence for roles in calcium signaling is emerging. We describe a label-free proteomics method suitable for small cardiac tissue biopsies based on density-separated fractionation, which allows study of endolysosomal (EL) proteins. Density gradient fractions corresponding to tissue lysate; sarcoplasmic reticulum (SR), mitochondria (Mito) (1.3 g/mL); and EL with negligible contamination from SR or Mito (1.04 g/mL) were analyzed using Western blot, enzyme activity assay, and liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis (adapted discontinuous Percoll and sucrose differential density gradient). Kyoto Encyclopedia of Genes and Genomes, Reactome, Panther, and Gene Ontology pathway analysis showed good coverage of RAB proteins and lysosomal cathepsins (including cardiac-specific cathepsin D) in the purified EL fraction. Significant EL proteins recovered included catalytic activity proteins. We thus present a comprehensive protocol and data set of guinea pig atrial EL organelle proteomics using techniques also applicable for non-cardiac tissue.

Network Analysis Reveals Proteins Associated with Aortic Dilatation in Mucopolysaccharidoses

Mucopolysaccharidoses are caused by a deficiency of enzymes involved in the degradation of glycosaminoglycans. Heart diseases are a significant cause of morbidity and mortality in MPS patients, even in conditions in which enzyme replacement therapy is available. In this sense, cardiovascular manifestations, such as heart hypertrophy, cardiac function reduction, increased left ventricular chamber, and aortic dilatation, are among the most frequent. However, the downstream events which influence the heart dilatation process are unclear. Here, we employed systems biology tools together with transcriptomic data to investigate new elements that may be involved in aortic dilatation in Mucopolysaccharidoses syndrome. We identified candidate genes involved in biological processes related to inflammatory responses, deposition of collagen, and lipid accumulation in the cardiovascular system that may be involved in aortic dilatation in the Mucopolysaccharidoses I and VII. Furthermore, we investigated the molecular mechanisms of losartan treatment in Mucopolysaccharidoses I mice to underscore how this drug acts to prevent aortic dilation. Our data indicate that the association between the TGF-b signaling pathway, Fos, and Col1a1 proteins can play an essential role in aortic dilation's pathophysiology and its subsequent improvement by losartan treatment.

Proteasome Composition and Activity Changes in Cultured Fibroblasts Derived From Mucopolysaccharidoses Patients and Their Modulation by Genistein

In this study, we have asked whether proteasome composition and function are affected in cells derived from patients suffering from all types of mucopolysaccharidosis (MPS), an inherited metabolic disease caused by accumulation of undegraded glycosaminoglycans (GAGs). Moreover, we have tested if genistein, a small molecule proposed previously as a potential therapeutic agent in MPS, can modulate proteasomes, which might shed a new light on the molecular mechanisms of action of this isoflavone as a potential drug for macromolecule storage diseases. Significant changes in expression of various proteasome-linked genes have been detected during transcriptomic (RNA-seq) analyses in vast majority of MPS types. These results were corroborated by demonstration of increased proteasomal activities in MPS cells. However, GAGs were not able to stimulate the 26S proteasome in vitro, suggesting that the observed activation in cells is indirect rather than arising from direct GAG-proteasome interactions. Genistein significantly reduced proteasomal activities in fibroblasts derived from patients suffering from all MPS types, while its effects on in vitro 26S proteasome activity were negligible. Unexpectedly, levels of many proteasomal subunits were increased in genistein-treated MPS cells. On the other hand, this ostensible discrepancy between results of experiments designed for estimation of effects of genistein on proteasome activities and abundance of proteasomal subunits can be explained by demonstration that in the presence of this isoflavone, levels of ubiquitinated proteins were decreased. The genistein-mediated reduction of proteasomal activities might have beneficial effects in cells of MPS patients due to potential increasing of residual activities of defective lysosomal enzymes which would otherwise be subjected to efficient ubiquitination and proteasomal degradation as misfolded proteins. These results indicate another activity of genistein (apart from previously demonstrated reduction of GAG synthesis efficiency, stimulation of lysosomal biogenesis, and activation of the autophagy process) which can be beneficial in the use of this small molecule in treatment of MPS.

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.

Transcriptomic Changes Related to Cellular Processes with Particular Emphasis on Cell Activation in Lysosomal Storage Diseases from the Group of Mucopolysaccharidoses

Although mucopolysaccharidoses (MPS), inherited metabolic diseases from the group of lysosomal storage diseases (LSD), are monogenic disorders, recent studies indicated that their molecular mechanisms are complicated. Storage of glycosaminoglycans (GAGs), arising from a deficiency in one of the enzymes involved in the degradation of these compounds, is the primary cause of each MPS type. However, dysfunctions of various cellular organelles and disturbance of cellular processes have been reported which contribute considerably to pathomechanisms of the disease. Here, we present a complex transcriptomic analysis in which all types and subtypes of MPS were investigated, with special emphasis on genes related to cell activation processes. Complex changes in expression of these genes were found in fibroblasts of all MPS types, with number of transcripts revealing higher or lower levels (relative to control fibroblasts) between 19 and over 50, depending on MPS type. Genes in which expression was significantly affected in most MPS types code for proteins involved in following processes, classified according to Gene Ontology knowledge database: cell activation, cell growth, cell recognition, and cell division. Levels of some transcripts (including CD9, CLU, MME and others) were especially significantly changed (over five times relative to controls). Our results are discussed in the light of molecular pathomechanisms of MPS, indicating that secondary and/or tertiary changes, relative to GAG storage, might significantly modulate cellular dysfunctions and contribute to molecular mechanisms of the disease. This may influence the efficacy of various therapies and suggests why various treatments are not fully effective in improving the complex symptoms of MPS.

Underestimated Aspect of Mucopolysaccharidosis Pathogenesis: Global Changes in Cellular Processes Revealed by Transcriptomic Studies

Mucopolysaccharidoses (MPS), a group of inherited metabolic disorders caused by deficiency in enzymes involved in degradation of glycosaminoglycans (GAGs), are examples (and models) of monogenic diseases. Accumulation of undegraded GAGs in lysosomes was supposed to be the major cause of MPS symptoms; however, their complexity and variability between particular types of the disease can be hardly explained by such a simple storage mechanism. Here we show that transcriptomic (RNA-seq) analysis of the material derived from fibroblasts of patients suffering from all types and subtypes of MPS, supported by RT-qPCR results, revealed surprisingly large changes in expression of genes involved in various cellular processes, indicating complex mechanisms of MPS. Although each MPS type and subtype was characterized by specific changes in gene expression profile, there were genes with significantly changed expression relative to wild-type cells that could be classified as common for various MPS types, suggesting similar disturbances in cellular processes. Therefore, both common features of all MPS types, and differences between them, might be potentially explained on the basis of changes in certain cellular processes arising from disturbed regulations of genes’ expression. These results may shed a new light on the mechanisms of genetic diseases, indicating how a single mutation can result in complex pathomechanism, due to perturbations in the network of cellular reactions. Moreover, they should be considered in studies on development of novel therapies, suggesting also why currently available treatment methods fail to correct all/most symptoms of MPS. We propose a hypothesis that disturbances in some cellular processes cannot be corrected by simple reduction of GAG levels; thus, combined therapies are necessary which may require improvement of these processes.

Metabolomics profiling reveals profound metabolic impairments in mice and patients with Sandhoff disease

Sandhoff disease (SD) results from mutations in the HEXB gene, subsequent deficiency of N-acetyl-β-hexosaminidase (Hex) and accumulation of GM2 gangliosides. SD leads to progressive neurodegeneration and early death. However, there is a lack of established SD biomarkers, while the pathogenesis etiology remains to be elucidated. To identify potential biomarkers and unveil the pathogenic mechanisms, metabolomics analysis with reverse phase liquid chromatography (RPLC) was conducted. A total of 177, 112 and 119 metabolites were found to be significantly dysregulated in mouse liver, mouse brain and human hippocampus samples, respectively (p < .05, ID score > 0.5). Principal component analysis (PCA) analysis of the metabolites showed clear separation of metabolomics profiles between normal and diseased individuals. Among these metabolites, dipeptides, amino acids and derivatives were elevated, indicating a robust protein catabolism. Through pathway enrichment analysis, we also found alterations in metabolites associated with neurotransmission, lipid metabolism, oxidative stress and inflammation. In addition, N-acetylgalactosamine 4-sulphate, key component of glycosaminoglycans (GAG) was significantly elevated, which was also confirmed by biochemical assays. Collectively, these results indicated major shifts of energy utilization and profound metabolic impairments, contributing to the pathogenesis mechanisms of SD. Global metabolomics profiling may provide an innovative tool for better understanding the disease mechanisms, and identifying potential diagnostic biomarkers for SD.

Cardiovascular Histopathology of a 11-Year Old with Mucopolysaccharidosis VII Demonstrates Fibrosis, Macrophage Infiltration, and Arterial Luminal Stenosis

Mucopolysaccharidosis type VII (MPS VII) is caused by β-glucuronidase deficiency, resulting in lysosomal accumulation of glycosaminoglycans (GAGs) and multisystemic disease. We present cardiovascular gross and histopathology findings from a 11-year-old MPS VII male, who expired after developing ventricular fibrillation following anesthesia induction. Gross anatomic observations were made at autopsy; postmortem formalin-fixed paraffin-embedded samples of the carotid artery, aorta, myocardium, and valves were sectioned and stained with hematoxylin-eosin, Verhoeff-Van Gieson, CD68, and trichrome stains. Gross heart findings include an enlarged, dilated heart, mitral valve prolapse with thick, shortened chordae tendinae, and thickened aortic valve cusps. The aorta contained raised intimal plaques mimicking conventional atherosclerosis. Cardiac myocytes included hypertrophic nuclei, subendocardial fibrosis, and increased interfascicular collagen. Coronary lumens were 40-70% stenosed by fibrointimal hyperplasia containing storage material-laden cells, CD68⁺ macrophages, and fragmented elastin laminae. Similar findings were visualized in aortic intimal plaques. We confirm that arterial plaques, elastin fragmentation, and activated CD68⁺ macrophage infiltration occur in human MPS VII, consistent with previously observed findings in murine and canine MPS VII. We also confirm ultrasonographically observed carotid intimal-medial thickening is an in vivo correlate of histopathologic vascular fibrointimal hyperplasia. MPS VII patients should be regularly monitored for cardiac disease, with methods such as Holter monitors and stress testing; MPS VII-directed treatments should effectively address cardiovascular disease.

Overview of immune abnormalities in lysosomal storage disorders

The critical relevance of the lysosomal compartment for normal cellular function can be proved by numbering the clinical phenotypes that arise in lysosomal storage disorders (LSDs), a group of around 70 different monogenic autosomal or X-linked syndromes, caused by specific lysosomal enzyme deficiencies: all LSDs are characterized by progressive accumulation of heterogeneous biologic materials in the lysosomes of various parts of the body such as viscera, skeleton, skin, heart, and central nervous system. At least a fraction of LSDs has been associated with mixed abnormalities involving the immune system, while some patients with LSDs may result more prone to autoimmune phenomena. A large production of proinflammatory cytokines has been observed in Gaucher and Fabry diseases, and wide different autoantibody production has been also reported in both. Many immune-mediated reactions are crucial to the pathogenesis of different inflammatory signs in mucopolysaccharidoses, and subverted heparan sulphate catabolism might dysregulate cellular homeostasis in the brain of these patients. Furthermore, an inappropriate activation of microglia is implicated in the neurodegenerative foci of Niemann-Pick disease, in which abnormal signalling pathways are activated by impaired sphingolipid metabolism. In addition, not the simple impaired catabolism of gangliosides per se, but also the production of anti-ganglioside autoantibodies contributes to the neurological disease of gangliosidoses. Even if the exact relationship between the modification of lysosomal activities and modulation of the immune system remains obscure, there is emerging evidence of different impaired immunity responses in a variety of LSDs: in this review we investigate and summarize the immune abnormalities and/or clinical data about immune system irregularities which have been described in a subset of LSDs.

Dysregulated IL-1β Secretion in Autoinflammatory Diseases: A Matter of Stress?

Infectious and sterile inflammation is induced by activation of innate immune cells. Triggering of toll-like receptors by pathogen-associated molecular pattern or damage-associated molecular pattern (PAMP or DAMP) molecules generates reactive oxygen species that in turn induce production and activation of pro-inflammatory cytokines such as IL-1β. Recent evidence indicates that cell stress due to common events, like starvation, enhanced metabolic demand, cold or heat, not only potentiates inflammation but may also directly trigger it in the absence of PAMPs or DAMPs. Stress-mediated inflammation is also a common feature of many hereditary disorders, due to the proteotoxic effects of mutant proteins. We propose that harmful mutant proteins can induce dysregulated IL-1β production and inflammation through different pathways depending on the cell type involved. When expressed in professional inflammatory cells, stress induced by the mutant protein activates in a cell-autonomous way the onset of inflammation and mediates its aberrant development, resulting in the explosive responses that hallmark autoinflammatory diseases. When expressed in non-immune cells, the mutant protein may cause the release of transcellular stress signals that trigger and propagate inflammation.

The Carotid Intima-Media Thickness and Arterial Stiffness of Pediatric Mucopolysaccharidosis Patients Are Increased Compared to Both Pediatric and Adult Controls

Treatments for mucopolysaccharidoses (MPSs) have increased longevity, but cardiovascular disease causes mortality in a significant percentage of survivors. Markers must be developed to predict MPS cardiac risk and monitor efficacy of investigational therapies.MPS patients underwent carotid artery ultrasonography from which carotid intima-media thickness (cIMT) and three measures of arterial stiffness were calculated: carotid artery distensibility (cCSD), compliance (cCSC), and incremental elastic modulus (cIEM). MPS carotid measurements were compared to corresponding data from pediatric and adult healthy cohorts. 33 MPS patients (17 MPS I, 9 MPS II, 4 MPS IIIA, and 3 MPS VI; mean age 12.5 ± 4.7 years), 560 pediatric controls (age 13.1 ± 4.0 years), and 554 adult controls (age 39.2 ± 2.2 years) were studied. Age and sex-adjusted aggregate MPS cIMT (0.56 ± 0.05 mm) was significantly greater than both pediatric (+0.12 mm; 95% CI +0.10 to +0.14 mm) and adult (+0.10 mm; 95% CI +0.06 to +0.14 mm) control cohorts; similar findings were observed for all MPS subtypes. Mean MPS cIMT approximated the 80th percentile of the adult cohort cIMT. MPS patients also demonstrated significantly increased adjusted arterial stiffness measurements, evidenced by reduced cCSD, cCSC, and increased cIEM, compared to pediatric and adult control cohorts. Regardless of treatment, MPS patients demonstrate increased cIMT and arterial stiffness compared to healthy pediatric and adult controls. These data suggest that relatively young MPS patients demonstrate a “structural vascular age” of at least 40 years old.

Pentosan Polysulfate: Oral Versus Subcutaneous Injection in Mucopolysaccharidosis Type I Dogs

Background

We previously demonstrated the therapeutic benefits of pentosan polysulfate (PPS) in a rat model of mucopolysaccharidosis (MPS) type VI. Reduction of inflammation, reduction of glycosaminoglycan (GAG) storage, and improvement in the skeletal phenotype were shown. Herein, we evaluate the long-term safety and therapeutic effects of PPS in a large animal model of a different MPS type, MPS I dogs. We focused on the arterial phenotype since this is one of the most consistent and clinically significant features of the model.

Methodology/Principal Findings

MPS I dogs were treated with daily oral or biweekly subcutaneous (subQ) PPS at a human equivalent dose of 1.6 mg/kg for 17 and 12 months, respectively. Safety parameters were assessed at 6 months and at the end of the study. Following treatment, cytokine and GAG levels were determined in fluids and tissues. Assessments of the aorta and carotid arteries also were performed. No drug-related increases in liver enzymes, coagulation factors, or other adverse effects were observed. Significantly reduced IL-8 and TNF-alpha were found in urine and cerebrospinal fluid (CSF). GAG reduction was observed in urine and tissues. Increases in the luminal openings and reduction of the intimal media thickening occurred in the carotids and aortas of PPS-treated animals, along with a reduction of storage vacuoles. These results were correlated with a reduction of GAG storage, reduction of clusterin 1 staining, and improved elastin integrity. No significant changes in the spines of the treated animals were observed.

Conclusions

PPS treatment led to reductions of pro-inflammatory cytokines and GAG storage in urine and tissues of MPS I dogs, which were most evident after subQ administration. SubQ administration also led to significant cytokine reductions in the CSF. Both treatment groups exhibited markedly reduced carotid and aortic inflammation, increased vessel integrity, and improved histopathology. We conclude that PPS may be a safe and useful therapy for MPS I, either as an adjunct or as a stand-alone treatment that reduces inflammation and GAG storage.