Cardiac pathology in mucopolysaccharidosis I mice: Losartan modifies ERK1/2 activation during cardiac remodeling.

Mucopolysaccharidosis type I (MPS I) is a lysosomal storage disorder caused by mutations in the IDUA gene, that codifies the alpha-L-iduronidase enzyme, which deficiency leads to storage of glycosaminoglycans, with multiple clinical manifestations. One of the leading causes of death in MPS I patients are cardiac complications such as cardiac valve thickening, conduction abnormalities, myocardial dysfunction, and cardiac hypertrophy. The mechanism leading to cardiac dysfunction in MPS I is not entirely understood. In a previous study, we have demonstrated that losartan and propranolol improved the cardiac function in MPS I mice. Thus, we aimed to investigate whether the pathways influenced by these drugs may modulate the cardiac remodeling process in MPS I mice. According to our previous observation, losartan and propranolol restore the heart function, without altering valve thickness. MPS I mice presented reduced activation of AKT and ERK1/2, increased activity of cathepsins, but no alteration in metalloproteinase activity was observed. Animals treated with losartan showed a reduction in cathepsin activity and restored ERK1/2 activation. While both losartan and propranolol improved heart function, no mechanistic evidence was found for propranolol so far. Our results suggest that losartan or propranolol could be used to ameliorate the cardiac disease in MPS I and could be considered as adjuvant treatment candidates for therapy optimization.

Treatment with pentosan polysulphate in patients with MPS I: results from an open label, randomized, monocentric phase II study.

Current treatment options for MPS I have limited effects on some organs, including the skeletal system. In MPS animal models pentosan polysulphate (PPS) reduces the concentrations of glycosaminoglycans (GAGs) in tissues and body fluids and improves cartilaginous and osseous pathologies. The goals of this study were to investigate primarily the safety and secondary the clinical effects, concerning mobility and pain, of PPS treatment in MPS I patients. Four MPS I-Hurler-Scheie/-Scheie patients aged 35.6 ± 6.4 years with one male were included in the study. All patients were on enzyme replacement therapy since 9.45 ± 3.75 years. PPS was applied subcutaneously in two patients with 1 mg/kg and in two patients with 2 mg/kg, weekly for 12 weeks and then biweekly for 12 weeks. The 24-week treatment with PPS was well tolerated by all patients. Urinary GAG concentrations were reduced from 4.13 ± 1.17 at baseline to 2.69 ± 0.36 mg/mmol creatinine after 24-week treatment with 1 mg/kg PPS, and from 6.71 ± 0.62 to 2.65 ± 0.09 mg/mmol creatinine with 2 mg/kg PPS. An improvement in range of motion was noted in three out of four patients. The pain intensity score was reduced from 4.5 ± 1.77 at baseline to 1.8 ± 0.47 after 24-week treatment with 1 mg/kg PPS; patients with 2 mg/kg PPS already had minimal pain at the start of the study. In conclusion, PPS treatment in a small number of adult MPS I patients was well tolerated and resulted in a significant reduction of urinary GAG excretion and in an improvement of joint mobility and pain.

Efficacy of recombinant human alpha-L-iduronidase (laronidase) on restricted range of motion of upper extremities in mucopolysaccharidosis type I patients.

The aims of the study were to assess the effectiveness of enzyme replacement therapy (ERT) with laronidase on the range of motion (ROM) of upper extremities and influence on activities of daily living (ADLs) of patients with mucopolysaccharidosis type I (MPS I). The ROM of 17 patients with MPS I was followed from the first year of life until the introduction of ERT and after 52-208 weeks of treatment. In all patients (group 1, n = 10), passive ROM was assessed. In patients with Hurler/Scheie or Scheie phenotype (group 2, n = 7) both passive and active ROM, as well as daily life activities, were evaluated. Passive and active ROM was measured by a goniometer, while a health assessment questionnaire was used to assess activities of daily living. The data since the first months of life until the beginning of treatment were obtained by retrospective review of patients' charts. Restriction in ROM of the upper extremities of patients with MPS I was observed from the first year of life. These limitations intensified and became more severe with the patients' age, making patients' self-care more difficult or even impossible. Introduction of ERT led to slower progression of symptoms, especially in the passive range of motion in all patients. Additionally, patients with normal mental development, or only slightly delayed (group 2), who underwent active physical rehabilitation (including mobilisation of nerve system, passive techniques for joint mobility, active gymnastics for muscle power, as well as massage and the training of families for therapy at home) showed improvement in active movement followed by enhanced self-care.