The incidence of movement disorder increases with age and contrasts with subtle and limited neuroimaging abnormalities in argininosuccinic aciduria

Argininosuccinate lyase (ASL) is integral to the urea cycle detoxifying neurotoxic ammonia and the nitric oxide (NO) biosynthesis cycle. Inherited ASL deficiency causes argininosuccinic aciduria (ASA), a rare disease with hyperammonemia and NO deficiency. Patients present with developmental delay, epilepsy and movement disorder, associated with NO-mediated downregulation of central catecholamine biosynthesis. A neurodegenerative phenotype has been proposed in ASA. To better characterise this neurodegenerative phenotype in ASA, we conducted a retrospective study in six paediatric and adult metabolic centres in the UK in 2022. We identified 60 patients and specifically looked for neurodegeneration-related symptoms: movement disorder such as ataxia, tremor and dystonia, hypotonia/fatigue and abnormal behaviour. We analysed neuroimaging with diffusion tensor imaging (DTI) magnetic resonance imaging (MRI) in an individual with ASA with movement disorders. We assessed conventional and DTI MRI alongside single photon emission computer tomography (SPECT) with dopamine analogue radionuclide 123 I-ioflupane, in Asl-deficient mice treated by hASL mRNA with normalised ureagenesis. Movement disorders in ASA appear in the second and third decades of life, becoming more prevalent with ageing and independent from the age of onset of hyperammonemia. Neuroimaging can show abnormal DTI features affecting both grey and white matter, preferentially basal ganglia. ASA mouse model with normalised ureagenesis did not recapitulate these DTI findings and showed normal 123 I-ioflupane SPECT and cerebral dopamine metabolomics. Altogether these findings support the pathophysiology of a late-onset movement disorder with cell-autonomous functional central catecholamine dysregulation but without or limited neurodegeneration of dopaminergic neurons, making these symptoms amenable to targeted therapy.

Polyphenol treatments increase elastin and collagen deposition by human dermal fibroblasts; Implications to improve skin health

BACKGROUND

Skin aging is marked by progressive loss in elastin and collagen that causes wrinkling and sagging of skin. Tropoelastin (TE) is the precursor monomer of elastin secreted by cells that cross-links extracellularly to create functional elastic fibers. Cells maintain the capacity to make TE during the aging process. However, the process of extracellular tropoelastin cross-linking diminishes with age. Others have shown that TE production by cells increases with UV exposure.

OBJECTIVE

We hypothesize that polyphenols may help coacervate cell secreted TE due to its elastin binding property and increase insoluble elastin in human dermal fibroblasts (HDFs). Increase in TE production by short term UV exposure may further improve elastin deposition by polyphenols.

METHODS

We treated HDFs with polyphenols viz epigallocatechin gallate (EGCG) and pentagalloyl glucose (PGG) either with or without intermittent (UVA, 12 min three times a week) exposure for 3, 7, and 14 days.

RESULTS

Polyphenols increased insoluble elastin deposition several folds as compared to control untreated cells. Furthermore, short UVA light exposure led to several-fold increased TE production in HDFs. Still, UVA exposure alone was unable to increase insoluble elastic fibers. When polyphenols were introduced with UVA exposure, insoluble elastin deposition was further enhanced in HDFs (30-45-fold increase). Polyphenol treatments with UVA exposure also led to increased collagen deposition in cell cultures. Polyphenols also prevented cell oxidation during UVA exposure.

CONCLUSIONS

Polyphenols in combination with short exposure to UVA light increase extracellular matrix deposition of elastin and collagen and may improve skin properties.

Reversal of Vascular Calcification and Aneurysms in a Rat Model Using Dual Targeted Therapy with EDTA- and PGG-Loaded Nanoparticles

Degeneration of elastic lamina and vascular calcification are common features of vascular pathology such as aortic aneurysms. We tested whether dual therapy with targeted nanoparticles (NPs) can remove mineral deposits (by delivery of a chelating agent, ethylene diamine tetraacetic acid (EDTA)) and restore elastic lamina (by delivery of a polyphenol, pentagalloyl glucose (PGG)) to reverse moderate aneurysm development. EDTA followed by PGG NP delivery led to reduction in macrophage recruitment, matrix metalloproteinase (MMP) activity, elastin degradation and calcification in the aorta as compared to delivery of control blank NPs. Such dual therapy restored vascular elastic lamina and improved vascular function as observed by improvement in circumferential strain. Therefore, dual targeted therapy may be an attractive option to remove mineral deposits and restore healthy arterial structures in moderately developed aneurysms.