A recently proposed therapeutic approach for lysosomal storage disorders (LSDs) relies upon the ability of transcription factor EB (TFEB) to stimulate autophagy and induce lysosomal exocytosis ...leading to cellular clearance. This approach is particularly attractive in glycogen storage disease type II a severe metabolic myopathy, Pompe disease (PD) as the currently available therapy, replacement of the missing enzyme acid alpha‐glucosidase, fails to reverse skeletal muscle pathology. PD, a paradigm for LSDs, is characterized by both lysosomal abnormality and dysfunctional autophagy. Here, we show that TFEB is a viable therapeutic target in PD: overexpression of TFEB in a new muscle cell culture system and in mouse models of the disease reduced glycogen load and lysosomal size, improved autophagosome processing, and alleviated excessive accumulation of autophagic vacuoles. Unexpectedly, the exocytosed vesicles were labelled with lysosomal and autophagosomal membrane markers, suggesting that TFEB induces exocytosis of autophagolysosomes. Furthermore, the effects of TFEB were almost abrogated in the setting of genetically suppressed autophagy, supporting the role of autophagy in TFEB‐mediated cellular clearance.
New Pompe disease models allow testing of novel therapeutic approach for lysosomal storage disorders. The transcription factor EB promotes clearing of muscles from excessive oxygen and autophagic debris, by inducing exocytosis of autophagolysosomes.
Pompe disease is an autosomal recessive disorder caused by a deficiency of acid-α-glucosidase (GAA), an enzyme responsible for hydrolyzing lysosomal glycogen. A lack of GAA leads to accumulation of ...glycogen in the lysosomes of cardiac, skeletal, and smooth muscle cells, as well as in the central and peripheral nervous system. Enzyme replacement therapy has been the standard of care for 15 years and slows disease progression, particularly in the heart, and improves survival. However, there are limitations of ERT success, which gene therapy can overcome.
Gene therapy offers several advantages including prolonged and consistent GAA expression and correction of skeletal muscle as well as the critical CNS pathology. We provide a systematic review of the preclinical and clinical outcomes of adeno-associated viral mediated gene therapy and alternative gene therapy strategies, highlighting what has been successful.
Although the preclinical and clinical studies so far have been promising, barriers exist that need to be addressed in gene therapy for Pompe disease. New strategies including novel capsids for better targeting, optimized DNA vectors, and adjuctive therapies will allow for a lower dose, and ameliorate the immune response.
Pompe's disease van der Ploeg, Ans T, Dr; Reuser, Arnold JJ, PhD
The Lancet (British edition),
2008-Oct-11, Volume:
372, Issue:
9646
Journal Article
Peer reviewed
Summary Pompe's disease, glycogen-storage disease type II, and acid maltase deficiency are alternative names for the same metabolic disorder. It is a pan-ethnic autosomal recessive trait ...characterised by acid α-glucosidase deficiency leading to lysosomal glycogen storage. Pompe's disease is also regarded as a muscular disorder, but the generalised storage of glycogen causes more than mobility and respiratory problems. The clinical spectrum is continuous and broad. First symptoms can present in infants, children, and adults. Cardiac hypertrophy is a key feature of classic infantile Pompe's disease. For a long time, there was no means to stop disease progression, but the approval of enzyme replacement therapy has substantially changed the prospects for patients. With this new development, the disease is now among the small but increasing number of lysosomal storage disorders, for which treatment has become a reality. This review is meant to raise general awareness, to present and discuss the latest insights in disease pathophysiology, and to draw attention to new developments about diagnosis and care. We also discuss the developments that led to the approval of enzyme replacement therapy with recombinant human α-glucosidase from Chinese hamster ovary cells (alglucosidase alfa) by the US Food and Drug Administration and European Medicines Agency in 2006, and review clinical practice.
Enzyme replacement therapy (ERT) for Pompe disease using recombinant acid alpha-glucosidase (rhGAA) has resulted in increased survival although the clinical response is variable. Cross-reactive ...immunological material (CRIM)-negative status has been recognized as a poor prognostic factor. CRIM-negative patients make no GAA protein and develop sustained high antibody titers to ERT that render the treatment ineffective. Antibody titers are generally low for the majority of CRIM-positive patients and there is typically a better clinical outcome. Because immunomodulation has been found to be most effective in CRIM-negative patients prior to, or shortly after, initiation of ERT, knowledge of CRIM status is important before ERT is begun. We have analyzed 243 patients with infantile Pompe disease using a Western blot method for determining CRIM status and using cultured skin fibroblasts. Sixty-one out of 243 (25.1%) patients tested from various ethnic backgrounds were found to be CRIM-negative. We then correlated the CRIM results with GAA gene mutations where available (52 CRIM-negative and 88 CRIM-positive patients). We found that, in most cases, CRIM status can be predicted from GAA mutations, potentially circumventing the need for invasive skin biopsy and time wasted in culturing cells in the future. Continued studies in this area will help to increase the power of GAA gene mutations in predicting CRIM status as well as possibly identifying CRIM-positive patients who are at risk for developing high antibody titers.
Objective To evaluate whether B-cell depletion before enzyme replacement therapy (ERT) initiation can block acid alpha-glucosidase (GAA) antibody responses and improve clinical outcomes. Study design ...Six subjects with Pompe disease (including 4 cross-reacting immunologic material–negative infants) aged 2-8 months received rituximab and sirolimus or mycophenolate before ERT. Four subjects continued to receive sirolimus, rituximab every 12 weeks, and intravenous immunoglobulin monthly for the duration of ERT. Sirolimus trough levels, IgG, CD3, CD4, CD8, CD19, CD20, N-terminal pro-brain natriuretic peptide, creatine kinase, creatine kinase-MB, C-reactive protein, platelets, alkaline phosphatase, gamma-glutamyl transferase, aspartate aminotransferase, and alanine aminotransferase were measured regularly. Results Immunomodulation achieved B-cell depletion without adverse effects. After 17-36 months of rituximab, sirolimus and ERT, all subjects lacked antibodies against GAA, 4 continued to gain motor milestones, yet 2 progressed to require invasive ventilation. The absence of infusion-associated reactions allowed the use of accelerated infusion rates. Conclusion B-cell depletion and T-cell immunomodulation in infants naïve to ERT was accomplished safely and eliminated immune responses against GAA, thereby optimizing clinical outcome; however, this approach did not necessarily influence sustained independent ventilation. Importantly, study outcomes support the initiation of immunomodulation before starting ERT, because the study regimen allowed for prompt initiation of treatment.
This study evaluated the inhibitory effects of plant-based extracts (grape seed, green tea, and white tea) and their constituent flavan-3-ol monomers (catechins) on α-amylase and α-glucosidase ...activity, two key glucosidases required for starch digestion in humans. To evaluate the relative potency of extracts and catechins, their concentrations required for 50 and 90% inhibition of enzyme activity were determined and compared to the widely used pharmacological glucosidase inhibitor, acarbose. Maximum enzyme inhibition was used to assess relative inhibitory efficacy. Results showed that grape seed extract strongly inhibited both α-amylase and α-glucosidase activity, with equal and much higher potency, respectively, than acarbose. Whereas tea extracts and catechin 3-gallates were less effective inhibitors of α-amylase, they were potent inhibitors of α-glucosidase. Nongallated catechins were ineffective. The data show that plant extracts containing catechin 3-gallates, in particular epigallocatechin gallate, are potent inhibitors of α-glucosidase activity and suggest that procyanidins in grape seed extract strongly inhibit α-amylase activity.
Pompe disease is a lysosomal storage disorder (LSD) caused by mutations in the gene that encodes acid α-glucosidase (GAA). Recently, small molecule pharmacological chaperones have been shown to ...increase protein stability and cellular levels for mutant lysosomal enzymes and have emerged as a new therapeutic strategy for the treatment of LSDs. In this study, we characterized the pharmacological chaperone 1-deoxynojirimycin (DNJ) on 76 different mutant forms of GAA identified in Pompe disease. DNJ significantly increased enzyme activity and protein levels for 16 different GAA mutants in patient-derived fibroblasts and in transiently transfected COS-7 cells. Additionally, DNJ increased the processing of these GAA mutants to their mature lysosomal forms, suggesting facilitated trafficking through the secretory pathway. Immunofluorescence microscopy studies showed increased colocalization of GAA with the lysosomal marker LAMP2 after incubation with DNJ, confirming increased lysosomal trafficking. Lastly, a GAA structural model was constructed based on the related eukaryotic glucosidase maltase-glucoamylase. The mutated residues identified in responsive forms of GAA are located throughout most of the structural domains, with half of these residues located in two short regions within the catalytic domain. Taken together, these data support further evaluation of DNJ as a potential treatment for Pompe disease in patients that express responsive forms of GAA. Hum Mutat 30:1-10, 2009.
•The anti-diabetic effects of Chamaerops humilis methanol extract (CHME) and five identified compounds named: tricin-7-rutinoside (1), tricin (2), dihydrotricin (3), (salcolin A) (4a), (salcolin B) ...(4b), and (-)-(5s, 6s)-5,6-dihydro-3,8,10-trihydroxy-5-(4-hydroxy-3-methoxyphenyl)-6-hydroxymethyl-2,4-dimethoxy 7H benzo e xanthen-7-one (5) were evaluated in-vivo and in-vitro.•The beneficial activities of CHME were attributed to its phenolic content.•CHME extract exhibited an antidiabetic effect by controlling hyperglycaemia and reducing the inflammatory response including TNF-α, IL6, and MMP-1, were downregulated by CHME treatment.•Molecular docking simulations indicated that compounds 1, 2, and 3 had higher binding energies compared to the reference drug acarbose when tested against α-glucosidase and α-amylase.
Five compounds were isolated from the aerial parts of Chamaerops humilis L. and characterized as tricin-7-rutinoside (1), tricin (2), dihydrotricin (3) diasteroisomer of tricin 4′-O(erythro-β-guaiacyl glyceryl) ether (salcolin A)(4a), tricin-4′-O-(threo-β-guaiacyl glyceryl) ether (salcolin B) (4b) and (-)-(5s, 6s)-5,6-dihydro-3,8,10-trihydroxy-5-(4-hydroxy-3-methoxyphenyl)-6-hydroxymethyl-2,4-dimethoxy 7H benzo e xanthen-7-one (5). Their structures were elucidated by comparing their spectral data with those reported in the literature. To the best of our knowledge, compounds (3-5) were reported here for the first time from Chamaerops humilis. The methanolic extract of Chamaerops humilis (CHME) and the five isolated compounds were studied for its anti-diabetic effect using in vitro α-glucosidase and α-amylase inhibitory assay that showed a significant activity. The toxicological study indicated that CHME was safe up to 5000 mg/kg bw. Two doses were selected for the in vivo study (800 and 1600 mg/kg bw) and orally administered to high fat diet/streptozotocin-induced diabetic rats for 10 consecutive days. The results revealed that the CHME improved the blood glucose levels in a dose dependent manner, the dose 1600 mg/kg showed the best results dependently along the period of the experiment. CHME and the five isolated compounds were evaluated in silico for their anti-diabetic effect. The anti-inflammatory effect of CHME (1600 mg/kg bw) was proved by significant downregulation of expression for interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and matrix metalloproteinase-1 (MMP-1) genes. In conclusion, CHME and its constituents may be a potential hypoglycemic agent working through the anti-inflammatory and enzyme inhibitory pathways. The docking studies demonstrated that compounds Tricin7-rutinoside and Salcolin isomers had promising binding energies of -9.10 kcal/mol and -8.70 kcal/mol, respectively, against α-amylase. These binding energies were superior to that of acarbose, which had a binding energy of -7.60 kcal/mol. In addition, docking analysis provided promising results for the inhibition of α-glucosidase by Tricin7-rutinoside and Dihydrotricin with binding affinity -7.9 kcal/mol and -7.9 kcal/mol, respectively while the binding affinity of acarbose is -6.40 kcal/mol. Overall, the methanolic extract from Chamaerops humilis exhibited good in silico of α-amylase and α-glucosidase enzyme inhibition potential. These findings suggest that these compounds may have potential as anti-diabetic agents, with further research needed to verify their efficacy and safety.
•Pronase and Viscozyme treatment changed the ratio of soluble to insoluble-bound phenolics.•Viscozyme was more effective than Pronase in releasing phenolic compounds.•Procyanidin dimer B was ...extracted with Viscozyme but not upon Pronase treatment.•Phenolics served as inhibitors of alpha-glucosidase and lipase.•Phenolics may act in prevention and/or management of diabetes and obesity.
Phenolics in food and agricultural processing by-products exist in the soluble and insoluble-bound forms. The ability of selected enzymes in improving the extraction of insoluble-bound phenolics from the starting material (experiment I) or the residues containing insoluble-bound phenolics (experiment II) were evaluated. Pronase and Viscozyme improved the extraction of insoluble-bound phenolics as evaluated by total phenolic content, antioxidant potential as determined by ABTS and DPPH assays, and hydroxyl radical scavenging capacity, reducing power as well as evaluation of inhibition of alpha-glucosidase and lipase activities. Viscozyme released higher amounts of gallic acid, catechin, and prodelphinidin dimer A compared to Pronase treatment. Furthermore, p-coumaric and caffeic acids, as well as procyanidin dimer B, were extracted with Viscozyme but not with Pronase treatment. Solubility plays an important role in the bioavailability of phenolic compounds, hence this study may assist in better exploitation of phenolics from winemaking by-products as functional food ingredients and/or supplements.
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