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The Murine Model of Mucopolysaccharidosis IIIB Develops Cardiopathies over Time Leading to Heart Failure.

Schiattarella GG, Cerulo G, De Pasquale V, Cocchiaro P, Paciello O, Avallone L, Belfiore MP, Iacobellis F, Di Napoli D, Magliulo F, Perrino C, Trimarco B, Esposito G, Di Natale P, Pavone LM - PLoS ONE (2015)

Bottom Line: Mucopolysaccharidosis (MPS) IIIB is a lysosomal disease due to the deficiency of the enzyme α-N-acetylglucosaminidase (NAGLU) required for heparan sulfate (HS) degradation.The disease is characterized by mild somatic features and severe neurological disorders.Overall, our findings demonstrate that NAGLU(-/-) mice develop heart disease, valvular abnormalities and cardiac failure associated with an impaired lysosomal autophagic flux.

View Article: PubMed Central - PubMed

Affiliation: Department of Advanced Biomedical Sciences, University of Naples Federico II, Naples, Italy.

ABSTRACT
Mucopolysaccharidosis (MPS) IIIB is a lysosomal disease due to the deficiency of the enzyme α-N-acetylglucosaminidase (NAGLU) required for heparan sulfate (HS) degradation. The disease is characterized by mild somatic features and severe neurological disorders. Very little is known on the cardiac dysfunctions in MPS IIIB. In this study, we used the murine model of MPS IIIB (NAGLU knockout mice, NAGLU(-/-)) in order to investigate the cardiac involvement in the disease. Echocardiographic analysis showed a marked increase in left ventricular (LV) mass, reduced cardiac function and valvular defects in NAGLU(-/-) mice as compared to wild-type (WT) littermates. The NAGLU(-/-) mice exhibited a significant increase in aortic and mitral annulus dimension with a progressive elongation and thickening of anterior mitral valve leaflet. A severe mitral regurgitation with reduction in mitral inflow E-wave-to-A-wave ratio was observed in 32-week-old NAGLU(-/-) mice. Compared to WT mice, NAGLU(-/-) mice exhibited a significantly lower survival with increased mortality observed in particular after 25 weeks of age. Histopathological analysis revealed a significant increase of myocardial fiber vacuolization, accumulation of HS in the myocardial vacuoles, recruitment of inflammatory cells and collagen deposition within the myocardium, and an increase of LV fibrosis in NAGLU(-/-) mice compared to WT mice. Biochemical analysis of heart samples from affected mice showed increased expression levels of cardiac failure hallmarks such as calcium/calmodulin-dependent protein kinase II, connexin43, α-smooth muscle actin, α-actinin, atrial and brain natriuretic peptides, and myosin heavy polypeptide 7. Furthermore, heart samples from NAGLU(-/-) mice showed enhanced expression of the lysosome-associated membrane protein-2 (LAMP2), and the autophagic markers Beclin1 and LC3 isoform II (LC3-II). Overall, our findings demonstrate that NAGLU(-/-) mice develop heart disease, valvular abnormalities and cardiac failure associated with an impaired lysosomal autophagic flux.

No MeSH data available.


Related in: MedlinePlus

Histological analysis of myocardial vacuolization.Representative H&E, Toluidine blue and Alcian blue-PAS staining of LV tissues form heart of 32-week-old WT and NAGLU-/- mice (100x magnification) shows vacuolization and deposition of HS into vacuoles. Arrows indicate vacuoles within myocardial fibers in the H&E (upper panel) and toluidine blue (middle panel), and HS accumulation in the Alcian blue-PAS staining (lower panel). Scale bars: 20 μm.
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pone.0131662.g003: Histological analysis of myocardial vacuolization.Representative H&E, Toluidine blue and Alcian blue-PAS staining of LV tissues form heart of 32-week-old WT and NAGLU-/- mice (100x magnification) shows vacuolization and deposition of HS into vacuoles. Arrows indicate vacuoles within myocardial fibers in the H&E (upper panel) and toluidine blue (middle panel), and HS accumulation in the Alcian blue-PAS staining (lower panel). Scale bars: 20 μm.

Mentions: In order to further investigate the features of cardiac disease in the MPS IIIB mouse model, a histopathological analysis of the myocardium of NAGLU-/- mice was performed. This analysis revealed a significant increase in myocardial fiber vacuolization compared to WT mice, as shown by H&E staining (Fig 3). Lysosomal storage and cellular vacuolization was also qualitatively evaluated by bright-field microscopy on plastic embedded semithin section stained by toluidine blue revealing at higher resolution the presence of vacuoles within the myocardial fibers of MPS IIIB mice (Fig 3). Furthermore, Alcian blue-PAS staining shows the accumulation of HS in the myocardial vacuoles of NAGLU-/- mice as indicated by areas of blue color (Fig 3). The only GAG accumulated in NAGLU-/- mouse tissues is represented by HS due to the specific enzymatic defect that characterizes MPS IIIB disease from other MPS syndromes in which accumulation of GAGs is mixed [1, 11]. Thus, the storage of HS may represent the main cause of valve defects and myocardial dysfunction in MPS IIIB mice.


The Murine Model of Mucopolysaccharidosis IIIB Develops Cardiopathies over Time Leading to Heart Failure.

Schiattarella GG, Cerulo G, De Pasquale V, Cocchiaro P, Paciello O, Avallone L, Belfiore MP, Iacobellis F, Di Napoli D, Magliulo F, Perrino C, Trimarco B, Esposito G, Di Natale P, Pavone LM - PLoS ONE (2015)

Histological analysis of myocardial vacuolization.Representative H&E, Toluidine blue and Alcian blue-PAS staining of LV tissues form heart of 32-week-old WT and NAGLU-/- mice (100x magnification) shows vacuolization and deposition of HS into vacuoles. Arrows indicate vacuoles within myocardial fibers in the H&E (upper panel) and toluidine blue (middle panel), and HS accumulation in the Alcian blue-PAS staining (lower panel). Scale bars: 20 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493027&req=5

pone.0131662.g003: Histological analysis of myocardial vacuolization.Representative H&E, Toluidine blue and Alcian blue-PAS staining of LV tissues form heart of 32-week-old WT and NAGLU-/- mice (100x magnification) shows vacuolization and deposition of HS into vacuoles. Arrows indicate vacuoles within myocardial fibers in the H&E (upper panel) and toluidine blue (middle panel), and HS accumulation in the Alcian blue-PAS staining (lower panel). Scale bars: 20 μm.
Mentions: In order to further investigate the features of cardiac disease in the MPS IIIB mouse model, a histopathological analysis of the myocardium of NAGLU-/- mice was performed. This analysis revealed a significant increase in myocardial fiber vacuolization compared to WT mice, as shown by H&E staining (Fig 3). Lysosomal storage and cellular vacuolization was also qualitatively evaluated by bright-field microscopy on plastic embedded semithin section stained by toluidine blue revealing at higher resolution the presence of vacuoles within the myocardial fibers of MPS IIIB mice (Fig 3). Furthermore, Alcian blue-PAS staining shows the accumulation of HS in the myocardial vacuoles of NAGLU-/- mice as indicated by areas of blue color (Fig 3). The only GAG accumulated in NAGLU-/- mouse tissues is represented by HS due to the specific enzymatic defect that characterizes MPS IIIB disease from other MPS syndromes in which accumulation of GAGs is mixed [1, 11]. Thus, the storage of HS may represent the main cause of valve defects and myocardial dysfunction in MPS IIIB mice.

Bottom Line: Mucopolysaccharidosis (MPS) IIIB is a lysosomal disease due to the deficiency of the enzyme α-N-acetylglucosaminidase (NAGLU) required for heparan sulfate (HS) degradation.The disease is characterized by mild somatic features and severe neurological disorders.Overall, our findings demonstrate that NAGLU(-/-) mice develop heart disease, valvular abnormalities and cardiac failure associated with an impaired lysosomal autophagic flux.

View Article: PubMed Central - PubMed

Affiliation: Department of Advanced Biomedical Sciences, University of Naples Federico II, Naples, Italy.

ABSTRACT
Mucopolysaccharidosis (MPS) IIIB is a lysosomal disease due to the deficiency of the enzyme α-N-acetylglucosaminidase (NAGLU) required for heparan sulfate (HS) degradation. The disease is characterized by mild somatic features and severe neurological disorders. Very little is known on the cardiac dysfunctions in MPS IIIB. In this study, we used the murine model of MPS IIIB (NAGLU knockout mice, NAGLU(-/-)) in order to investigate the cardiac involvement in the disease. Echocardiographic analysis showed a marked increase in left ventricular (LV) mass, reduced cardiac function and valvular defects in NAGLU(-/-) mice as compared to wild-type (WT) littermates. The NAGLU(-/-) mice exhibited a significant increase in aortic and mitral annulus dimension with a progressive elongation and thickening of anterior mitral valve leaflet. A severe mitral regurgitation with reduction in mitral inflow E-wave-to-A-wave ratio was observed in 32-week-old NAGLU(-/-) mice. Compared to WT mice, NAGLU(-/-) mice exhibited a significantly lower survival with increased mortality observed in particular after 25 weeks of age. Histopathological analysis revealed a significant increase of myocardial fiber vacuolization, accumulation of HS in the myocardial vacuoles, recruitment of inflammatory cells and collagen deposition within the myocardium, and an increase of LV fibrosis in NAGLU(-/-) mice compared to WT mice. Biochemical analysis of heart samples from affected mice showed increased expression levels of cardiac failure hallmarks such as calcium/calmodulin-dependent protein kinase II, connexin43, α-smooth muscle actin, α-actinin, atrial and brain natriuretic peptides, and myosin heavy polypeptide 7. Furthermore, heart samples from NAGLU(-/-) mice showed enhanced expression of the lysosome-associated membrane protein-2 (LAMP2), and the autophagic markers Beclin1 and LC3 isoform II (LC3-II). Overall, our findings demonstrate that NAGLU(-/-) mice develop heart disease, valvular abnormalities and cardiac failure associated with an impaired lysosomal autophagic flux.

No MeSH data available.


Related in: MedlinePlus