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Pharmacological chaperones (PCs) are small compounds able to rescue the activity of mutated lysosomal enzymes when used at subinhibitory concentrations. Nitrogen-containing glycomimetics such as aza- or iminosugars are known to behave as PCs for lysosomal storage disorders (LSDs). As part of our research into lysosomal sphingolipidoses inhibitors and looking in particular for new β-galactosidase inhibitors, we report the synthesis of a series of alkylated azasugars with a relative “all-cis” configuration at the hydroxy/amine-substituted stereocenters. The novel compounds were synthesized from a common carbohydrate-derived piperidinone intermediate 8, through reductive amination or alkylation of the derived alcohol. In addition, the reaction of ketone 8 with several lithium acetylides allowed the stereoselective synthesis of new azasugars alkylated at C-3. The activity of the new compounds towards lysosomal β-galactosidase was negligible, showing that the presence of an alkyl chain in this position is detrimental to inhibitory activity. Interestingly, 9, 10, and 12 behave as good inhibitors of lysosomal β-glucosidase (GCase) (IC50 = 12, 6.4, and 60 µM, respectively). When tested on cell lines bearing the Gaucher mutation, they did not impart any enzyme rescue. However, altogether, the data included in this work give interesting hints for the design of novel inhibitors.

Table 1 Lysosomal storage disease causing cardiac disease Disease group and subtypes General manifestations Cardiac manifestations Glycogen storage diseases (lysosomal) Autosomal recessive Massive LVH and RVH, cardiac failure (only in the infantile form) Myopathy, hypotonia, hepatomegaly, macroglossia cardiopulmonary failure, Short PR, broad QRS; endomyocardial fibrosis Type IIb (Danon disease, LAMP-2 deficiency) X-linked Hypertrophic cardiomyopathy, isolated cardiac variants, short PR, progressive conduction system disease Myopathy, mental retardation Mucopolysaccharidoses IH (Hurler) Autosomal recessive Valvular involvement (thickening, regurgitation, stenosis); endomyocardial infiltration; interstitial infiltration-fibrosis; hypertrophy; systolic dysfunction-dilated cardiomyopathy (less frequent); coronary artery infiltration-stenosis; aortic stenosis (abdominal); arterial hypertension IS (Scheie) X-linked - MPS II (Hunter) II (Hunter) Dysmorphic features, organomegaly, decreased joint mobility, bone deformities, loss of motor skills, mental retardation, corneal clouding, recurrent otitis or pneumonia, hearing loss III (Sanfilippo) IV (Morquio) VI (Maroteaux-Lamy) VII (Sly) IX (Natowicz) Sphingolipidoses Gaucher disease (β-glucocerebrodiase) Autosomal recessive Pulmonary hypertension, cor pulmonale; pericardial effusion (rare); valvular involvement (rare) Chronic non-neuronopathic (type I) Gaucher cells-lipid laden macrophages Acute (type II) Hepatosplenomegaly, anaemia, thrombocytopenia, bone involvement Chronic neuronopathic (type III) Neurodegeneration (neuronopathic forms) Niemann Pick disease (acid sphingomyelinase) Autosomal recessive Endomyocardial fibrosis (very rare) Type A Early onset, neurological involvement, hypotonia, psychomotor retardation (type A), hepatosplenomegaly, pancytopenia, pulmonary involvement Type B Anderson-Fabry disease (α-galactosidase A) X-linked Cardiac hypertrophy; short PR, progressive conduction system dysfunction, arrhythmias; valvular involvement; coronary involvement (decreased coronary reserve) Multiorgan involvement LVH, left ventricular hypertrophy; RVH, right ventricular hypertrophy. [...]many studies have shown that affected women experience symptoms similar to hemizygous males, albeit in a milder form with a delayed onset and slower progression compared to men; similarly, the frequency of end-stage renal disease is much lower and the median cumulative survival greater (70 years vs 50 years) in women. 1 Disease expression in female patients is attributed to random X chromosome inactivation and the incapacity of cells expressing the wild-type allele to cross-correct the metabolic defect. 5 Pathogenesis of cardiac disease in AFD Cross-sectional data in patients of different ages suggest that disease evolution in the heart is characterised initially by myocardial hypertrophy; as the disease progresses interstitial abnormalities and replacement myocardial fibrosis become important.

Background. Mesenteric lymphadenopathy is a rare manifestation of Gaucher disease (GD) in children and can be accompanied by protein losing enteropathy (PLE). PLE is a difficult-to-treat complication of GD. To date, only a few pediatric GD cases with PLE and massive mesenteric lymphadenopathies have been reported. Case. Here, we report a girl with chronic neuronopathic GD, whose disease course was complicated by massive mesenteric lymphadenopathies with resultant protein losing enteropathy despite a regular and appropriate enzyme replacement therapy of 60 IU/kg/biweekly until the development of mesenteric lymphadenopathies and 120 IU/kg/biweekly thereafter. Conclusions. PLE is a devastating and life threatening complication of GD developing despite long term use of high dose ERT. Clinicians should be alert for this complication particularly in GD patients presenting with progressive abdominal distension, edema, ascites and diarrhea or in patients who have already developed mesenteric lymphadenopathies. Timely diagnosis may allow early intervention with previously suggested surgical or medical treatment options. Although there is no specific and effective treatment, surgical and aggressive medical interventions in addition to ERT were reported to relieve diarrhea and halt progression of mesenteric lymphadenopathies.

Mucopolysaccharidosis type II (MPS II, Hunter syndrome) was first described by Dr. Charles Hunter in 1917. Since then, about one hundred years have passed and Hunter syndrome, although at first neglected for a few decades and afterwards mistaken for a long time for the similar disorder Hurler syndrome, has been clearly distinguished as a specific disease since 1978, when the distinct genetic causes of the two disorders were finally identified. MPS II is a rare genetic disorder, recently described as presenting an incidence rate ranging from 0.38 to 1.09 per 100,000 live male births, and it is the only X-linked-inherited mucopolysaccharidosis. The complex disease is due to a deficit of the lysosomal hydrolase iduronate 2-sulphatase, which is a crucial enzyme in the stepwise degradation of heparan and dermatan sulphate. This contributes to a heavy clinical phenotype involving most organ-systems, including the brain, in at least two-thirds of cases. In this review, we will summarize the history of the disease during this century through clinical and laboratory evaluations that allowed its definition, its correct diagnosis, a partial comprehension of its pathogenesis, and the proposition of therapeutic protocols. We will also highlight the main open issues related to the possible inclusion of MPS II in newborn screenings, the comprehension of brain pathogenesis, and treatment of the neurological compartment.

Sphingolipids are a specialized group of lipids essential to the composition of the plasma membrane of many cell types; however, they are primarily localized within the nervous system. The amphipathic properties of sphingolipids enable their participation in a variety of intricate metabolic pathways. Sphingoid bases are the building blocks for all sphingolipid derivatives, comprising a complex class of lipids. The biosynthesis and catabolism of these lipids play an integral role in small- and large-scale body functions, including participation in membrane domains and signalling; cell proliferation, death, migration, and invasiveness; inflammation; and central nervous system development. Recently, sphingolipids have become the focus of several fields of research in the medical and biological sciences, as these bioactive lipids have been identified as potent signalling and messenger molecules. Sphingolipids are now being exploited as therapeutic targets for several pathologies. Here we present a comprehensive review of the structure and metabolism of sphingolipids and their many functional roles within the cell. In addition, we highlight the role of sphingolipids in several pathologies, including inflammatory disease, cystic fibrosis, cancer, Alzheimer’s and Parkinson’s disease, and lysosomal storage disorders.

Long known as digestive organelles, lysosomes have now emerged as multifaceted centers responsible for degradation, nutrient sensing, and immunity. Growing evidence also implicates role of lysosome-related mechanisms in pathologic process. In this review, we discuss physiological function of lysosomes and, more importantly, how the homeostasis of lysosomes is disrupted in several diseases, including atherosclerosis, neurodegenerative diseases, autoimmune disorders, pancreatitis, lysosomal storage disorders, and malignant tumors. In atherosclerosis and Gaucher disease, dysfunction of lysosomes changes cytokine secretion from macrophages, partially through inflammasome activation. In neurodegenerative diseases, defect autophagy facilitates accumulation of toxic protein and dysfunctional organelles leading to neuron death. Lysosomal dysfunction has been demonstrated in pathology of pancreatitis. Abnormal autophagy activation or inhibition has been revealed in autoimmune disorders. In tumor microenvironment, malignant phenotypes, including tumorigenesis, growth regulation, invasion, drug resistance, and radiotherapy resistance, of tumor cells and behaviors of tumor-associated macrophages, fibroblasts, dendritic cells, and T cells are also mediated by lysosomes. Based on these findings, a series of therapeutic methods targeting lysosomal proteins and processes have been developed from bench to bedside. In a word, present researches corroborate lysosomes to be pivotal organelles for understanding pathology of atherosclerosis, neurodegenerative diseases, autoimmune disorders, pancreatitis, and lysosomal storage disorders, and malignant tumors and developing novel therapeutic strategies.

The function of lysosomes relies on the ability of the lysosomal membrane to fuse with several target membranes in the cell. It is known that in lysosomal storage disorders (LSDs), lysosomal accumulation of several types of substrates is associated with lysosomal dysfunction and impairment of endocytic membrane traffic. By analysing cells from two severe neurodegenerative LSDs, we observed that cholesterol abnormally accumulates in the endolysosomal membrane of LSD cells, thereby reducing the ability of lysosomes to efficiently fuse with endocytic and autophagic vesicles. Furthermore, we discovered that soluble N‐ethylmaleimide‐sensitive factor attachment protein (SNAP) receptors (SNAREs), which are key components of the cellular membrane fusion machinery are aberrantly sequestered in cholesterol‐enriched regions of LSD endolysosomal membranes. This abnormal spatial organization locks SNAREs in complexes and impairs their sorting and recycling. Importantly, reducing membrane cholesterol levels in LSD cells restores normal SNARE function and efficient lysosomal fusion. Our results support a model by which cholesterol abnormalities determine lysosomal dysfunction and endocytic traffic jam in LSDs by impairing the membrane fusion machinery, thus suggesting new therapeutic targets for the treatment of these disorders. Lysosomal storage disorders involve lysosomal dysfunction and defective endocytic membrane trafficking. However, the underlying mechanism(s) remain largely unclear. In this study, Andrea Ballabio et al. reveal that cholesterol accumulates in the endolysosomal system of LSD cells and interferes with the activity of the lysosomal SNARE membrane fusion machinery

Several diseases are caused by inherited defects in lysosomes, the so-called lysosomal storage disorders (LSDs). In some of these LSDs, tissue macrophages transform into prominent storage cells, as is the case in Gaucher disease. Here, macrophages become the characteristic Gaucher cells filled with lysosomes laden with glucosylceramide, because of their impaired enzymatic degradation. Biomarkers of Gaucher cells were actively searched, particularly after the development of costly therapies based on enzyme supplementation and substrate reduction. Proteins selectively expressed by storage macrophages and secreted into the circulation were identified, among which glycoprotein non-metastatic protein B (GPNMB). This review focusses on the emerging potential of GPNMB as a biomarker of stressed macrophages in LSDs as well as in acquired pathologies accompanied by an excessive lysosomal substrate load in macrophages.

The recent advancements in the knowledge of lysosomal biology and function have translated into an improved understanding of the pathophysiology of mucopolysaccharidoses (MPSs). The concept that MPS manifestations are direct consequences of lysosomal engorgement with undegraded glycosaminoglycans (GAGs) has been challenged by new information on the multiple biological roles of GAGs and by a new vision of the lysosome as a signaling hub involved in many critical cellular functions. MPS pathophysiology is now seen as the result of a complex cascade of secondary events that lead to dysfunction of several cellular processes and pathways, such as abnormal composition of membranes and its impact on vesicle fusion and trafficking; secondary storage of substrates; impairment of autophagy; impaired mitochondrial function and oxidative stress; dysregulation of signaling pathways. The characterization of this cascade of secondary cellular events is critical to better understand the pathophysiology of MPS clinical manifestations. In addition, some of these pathways may represent novel therapeutic targets and allow for the development of new therapies for these disorders.

Lysosomal storage disorders (LSDs) are a group of monogenic diseases characterized by progressive accumulation of undegraded substrates into the lysosome, due to mutations in genes that encode for proteins involved in normal lysosomal function. In recent years, several approaches have been explored to find effective and successful therapies, including enzyme replacement therapy, substrate reduction therapy, pharmacological chaperones, hematopoietic stem cell transplantation, and gene therapy. In the case of gene therapy, genome editing technologies have opened new horizons to accelerate the development of novel treatment alternatives for LSD patients. In this review, we discuss the current therapies for this group of disorders and present a detailed description of major genome editing technologies, as well as the most recent advances in the treatment of LSDs. We will further highlight the challenges and current bioethical debates of genome editing.