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

Lentiviral Gene Therapy for Mucopolysaccharidosis II with Tagged Iduronate 2-Sulfatase Prevents Life-Threatening Pathology in Peripheral Tissues But Fails to Correct Cartilage

Deficiency of iduronate 2-sulfatase (IDS) causes Mucopolysaccharidosis type II (MPS II), a lysosomal storage disorder characterized by systemic accumulation of glycosaminoglycans (GAGs), leading to a devastating cognitive decline and life-threatening respiratory and cardiac complications. We previously found that hematopoietic stem and progenitor cell-mediated lentiviral gene therapy (HSPC-LVGT) employing tagged IDS with insulin-like growth factor 2 (IGF2) or ApoE2, but not receptor-associated protein minimal peptide (RAP12x2), efficiently prevented brain pathology in a murine model of MPS II. In this study, we report on the effects of HSPC-LVGT on peripheral pathology and we analyzed IDS biodistribution. We found that HSPC-LVGT with all vectors completely corrected GAG accumulation and lysosomal pathology in liver, spleen, kidney, tracheal mucosa, and heart valves. Full correction of tunica media of the great heart vessels was achieved only with IDS.IGF2co gene therapy, while the other vectors provided near complete (IDS.ApoE2co) or no (IDSco and IDS.RAP12x2co) correction. In contrast, tracheal, epiphyseal, and articular cartilage remained largely uncorrected by all vectors tested. These efficacies were closely matched by IDS protein levels following HSPC-LVGT. Our results demonstrate the capability of HSPC-LVGT to correct pathology in tissues of high clinical relevance, including those of the heart and respiratory system, while challenges remain for the correction of cartilage pathology.

Biomarkers of Glycosaminoglycans (GAG) accumulation in patients with mucopolysaccharidosis type VI-LeukoGAG, Corneal Opacification (COM) and Carotid Intima Media Thickening (CIMT)

Mucopolysaccharidosis type VI (MPS VI) is an autosomal recessive lysosomal storage disorder characterized by deficient activity of arylsulfatase B enzyme (ASB) resulting in cellular accumulation of dermatan sulfate (DS) and chondroitin sulfate (CS) that leads to cell injury. Urinary glycosaminoglycans (GAG) are often used as a biomarker in MPS diseases for diagnosis and to monitor treatment efficacy. This study evaluated leukocyte GAGs (leukoGAG) and skin GAGs as alternate biomarkers representing intracellular GAG changes in patients with MPS VI and treated with enzyme replacement therapy (ERT). In addition, we evaluated corneal opacification measurements (COM) and carotid intima media thickness (CIMT) as indicators of GAG accumulation and tissue injury. The study was performed in a serial two-step design in a single center. A quantitative method to measure leukoGAG levels in leukocytes was developed in Study 1 to compare the GAG levels between MPS VI patients and a control group and to assess correlations between leukoGAG and urineGAG. Study 2 validated the leukoGAG measurement, assessed the effect of ERT infusion on leukoGAG and ASB activity in leukocytes, identified correlations between leukoGAG and other biomarkers, and assessed differences in GAG accumulation between MPS VI patients and control subjects. In Study 1, leukoCS and leukoDS levels were significantly higher in the MPS VI group than the control group (leukoCS: 37.9 ± 10.2 and 2.9 ± 1.5 μg/μg protein, respectively, p = 0.005; leukoDS: 0.26 ± 0.2 and 0.0 ± 0.0 μg/μg protein, respectively, p = 0.028) with positive correlations between leukoCS and urine CS and leukoDS and urineDS. In Study 2, leukoCS (32.0 ± 11.8 vs 6.9 ± 3.1 μg/mg protein, p = 0.005) and leukoDS (0.4 ± 0.1 and 0.2 ± 0.1 μg/mg protein, p = 0.020) were significantly higher compared with control subjects. Thus, these results highlight the potential of leukoGAG as a new biomarker representing intracellular GAG accumulation in MPS VI patients and may be valuable for patient management.

Intravenous Enzyme Replacement Therapy in Mucopolysaccharidoses: Clinical Effectiveness and Limitations

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

Abnormally increased carotid intima media-thickness and elasticity in patients with Morquio A disease

Background

Cardiovascular disease frequently causes morbidity and mortality in mucopolysaccharidoses (MPS); however, cardiovascular anatomy and dysfunction in MPS IVA (Morquio A disease) is not well described. Consequently, the study aimed to compare carotid artery structure and elasticity of MPS IVA patients with other MPS patients and healthy control subjects, and quantitate frequency of MPS IVA cardiac structural and functional abnormalities.

Methods

Prospective, multi-center echocardiogram and carotid ultrasound evaluations of 12 Morquio A patients were compared with other MPS and healthy control subjects. Average differences between groups were adjusted for age, sex, and height with robust variance estimation for confidence intervals and P-values.

Results

Morquio A patients demonstrated significantly higher (P < 0.001) adjusted carotid intima-media thickness (cIMT), mean (SD) of 0.56 mm (0.03) compared to control subjects, 0.44 mm (0.04). The Morquio A cohort had significantly greater adjusted carotid elasticity (carotid cross-sectional compliance + 43%, P < 0.001; carotid incremental elastic modulus − 33%, P = 0.003) than control subjects and other MPS patients. Aortic root dilatation was noted in 56% of the Morquio A cohort, which also had highly prevalent mitral (73%) and aortic (82%) valve thickening, though hemodynamically significant valve dysfunction was less frequent (9%).

Conclusions

Increased carotid elasticity in Morquio A patients is an unexpected contrast to the reduced elasticity observed in other MPS. These Morquio A cIMT findings corroborate MPS IVA arterial post-mortem reports and are consistent with cIMT of other MPS. Aortic root dilatation in Morquio A indicates arterial elastin dysfunction, but their carotid hyperelasticity indicates other vascular intima/media components, such as proteoglycans, may also influence artery function. Studying MPS I and IVA model systems may uniquely illuminate the function of glycosaminoglycan-bearing proteoglycans in arterial health.

LncRNA TUG1 contributes to cardiac hypertrophy via regulating miR-29b-3p

Cardiac hypertrophy with maladjusted cardiac remodeling is the leading cause of heart failure. In the past decades, long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have been proved to exert multiple functions in cellular biological behaviors; however, their role in cardiac hypertrophy remains largely unclear. Presently, we first obtained hypertrophic H9c2 cells by treating with angiotensin II (Ang II) and uncovered upregulation of lncRNA taurine upregulated gene 1 (TUG1) in such H9c2 cells. Then, we demonstrated that silencing TUG1 attenuated Ang II-induced cardiac hypertrophy. Besides, a strong interactivity of TUG1 with miR-29b-3p at the putative sites was validated, suggesting that TUG1 was an endogenous sponge of miR-29b-3p in H9c2 cells. Additionally, the expression of miR-29b-3p was strikingly reduced by TUG1 upregulation and also inhibited under Ang II treatment, whereas it was restored after silencing TUG1 in hypertrophic cells. Also, we proved miR-29b-3p as a negative regulator in cardiac hypertrophy. Finally, miR-29b-3p inhibition abolished the anti-hypertrophy effect of TUG1 depletion in Ang II-treated H9c2 cells. Collectively, our findings confirmed that TUG1 functioned as a positive modulator of cardiac hypertrophy via sponging miR-29b-3p, indicating that TUG1 might serve as a potential target for the treatment of cardiac hypertrophy and even heart failure.

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

Background

Cardiovascular disease, a progressive manifestation of α-L-iduronidase deficiency or mucopolysaccharidosis type I, continues in patients both untreated and treated with hematopoietic stem cell transplantation or intravenous enzyme replacement. Few studies have examined the effects of α-L-iduronidase deficiency and subsequent glycosaminoglycan storage upon arterial gene expression to understand the pathogenesis of cardiovascular disease.

Methods

Gene expression in carotid artery, ascending, and descending aortas from four non-tolerized, non-enzyme treated 19 month-old mucopolysaccharidosis type I dogs was compared with expression in corresponding vascular segments from three normal, age-matched dogs. Data were analyzed using R and whole genome network correlation analysis, a bias-free method of categorizing expression level and significance into discrete modules. Genes were further categorized based on module-trait relationships. Expression of clusterin, a protein implicated in other etiologies of cardiovascular disease, was assessed in canine and murine mucopolysaccharidosis type I aortas via Western blot and in situ immunohistochemistry.

Results

Gene families with more than two-fold, significant increased expression involved lysosomal function, proteasome function, and immune regulation. Significantly downregulated genes were related to cellular adhesion, cytoskeletal elements, and calcium regulation. Clusterin gene overexpression (9-fold) and protein overexpression (1.3 to 1.62-fold) was confirmed and located specifically in arterial plaques of mucopolysaccharidosis-affected dogs and mice.

Conclusions

Overexpression of lysosomal and proteasomal-related genes are expected responses to cellular stress induced by lysosomal storage in mucopolysaccharidosis type I. Upregulation of immunity-related genes implicates the potential involvement of glycosaminoglycan-induced inflammation in the pathogenesis of mucopolysaccharidosis-related arterial disease, for which clusterin represents a potential biomarker.