Comparative Analysis of Human and Porcine Corneal Mechanics and Structure after Glycosaminoglycan Degradation.

High myopia (HM) is a leading cause of irreversible vision loss in working-age adults. Its pathogenesis is characterized by alterations in the microstructure and composition of collagen fibers, and genetic factors make a substantial contribution. In this study, we identify carbohydrate sulfotransferase 5 (CHST5) as a candidate gene for HM in humans and mice, with its mutations disrupting collagen fiber organization. The c.444C>A (p.S148R) variant in CHST5, a gene critical for sulfating corneal keratan sulfate (KS), completely co-segregates with HM in a Chinese family. Screening of CHST5 variants in 320 HM patients identifies two additional ones. We further find that Chst5 is expressed primarily in the cornea and sclera of mouse ocular tissues, and that the mutant protein CHST5S148R loses its Golgi localization. Homozygous mutant Chst5S126R mice exhibit HM phenotypes, including myopic refractive error (RE), significantly thinner sclera and cornea, notable microstructural changes in scleral and corneal collagen fibers, and shorter corneal KS chains. Our findings suggest that CHST5 NM_024533.5 c.444C>A (p.S148R) causes loss of proper protein localization, likely impairing its sulfotransferase function. This defect disrupts the organization of corneal and scleral collagen fibers and ultimately contributes to the development and progression of HM.

Keratan sulfate (KS) is an acidic linear polysaccharide belonging to the glycosaminoglycan family. The repeating disaccharide unit of KS consists of the sequence -4)-βGlcNAc(1→3)-βGal(1→, with varying sulfation patterns at the primary hydroxy groups. L4 is a subclass of KS in which both primary hydroxy groups are sulfated. Herein, we report an efficient synthesis of KS L4 hexa- and octasaccharides as biotin conjugates through coupling reactions employing partially protected glycosyl acceptors.

Mucus covers and protects colonic epithelial cells. Mucus is mainly composed of heavily O-glycosylated proteins called mucins, and disruption of normal mucin glycosylation occurs in ulcerative colitis (UC). Mucin-2 (MUC2) is the major colonic mucin, and MUC2 O-glycans are often extended with sulfated polyLacNAc, also known as keratan sulfate (KS). The GlcNAc residues in KS are added by B3GNT family members. B3GNT7 is highly expressed in the colon, and B3GNT7 expression is dramatically reduced in UC. However, the function of B3GNT7 in colonic physiology is unexplored. Here we show that B3gnt7 is a key player in colonic physiology through its function in controlling the structure of mucus glycans. We found that B3GNT7 prefers to extend a sulfated acceptor substrate and is required for production of polyLacNAc-modified mucus in a human goblet cell model. In vivo, B3GNT7 regulates Muc2, Muc13, and Muc17 O-glycosylation. Intestinal B3GNT7 deficiency increases susceptibility to colitis and enteric infection in mice, showing that B3GNT7-dependent glycosylation confers protective properties to colonic mucus. Taken together, these results demonstrate that B3GNT7 has a function distinct from other B3GNT family members and is critical for maintaining colonic homeostasis.

Mucopolysaccharidosis Type IV is a multisystem lysosomal storage disease characterized by severe skeletal dysplasia resulting from impaired degradation of the glycosaminoglycans keratan sulfate and chondroitin-6-sulfate. The condition is classified into Types A and B based on the underlying enzyme deficiency. Low bone mineral density (BMD) is a feature of the skeletal phenotype, contributing to increased fracture risk. Extraskeletal manifestations include, among others, cardiovascular disease due to valvular stenosis and regurgitation, myocardial remodeling, coronary artery disease, and vascular stiffness, all associated with glycosaminoglycan accumulation. We report two adult patients with mucopolysaccharidosis Type IVB treated with the osteoanabolic agent teriparatide for an apparently low BMD. The first patient presented with a non-healing femoral fracture requiring BMD improvement prior to surgical fixation. This patient was treated with teriparatide for 2 years, which resulted in significant BMD gain, enabling successful surgical fixation. The second patient received teriparatide for only 6 months and showed stable BMD. Notably, both patients developed serious cardiac problems during teriparatide treatment: the first patient experienced rapidly progressive aortic stenosis, while the second patient developed dyspnea and polyuria due to worsening dynamic left ventricular outflow tract obstruction, which had previously been asymptomatic. Both patients required invasive cardiac interventions, which carry high risk in mucopolysaccharidosis due to unique anatomical and anesthetic challenges. The temporal association between teriparatide treatment and the onset of cardiac problems in both patients is noteworthy and raises the possibility of a treatment-related effect. Therefore, we recommend cautious use of teriparatide in patients with mucopolysaccharidosis Type IV.

ABSTRACTMucopolysaccharidosis type IVA (MPSIVA) is a lysosomal storage disease (LSD) caused by deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS), which causes the accumulation of keratan sulphate (KS) and chondroitin sulphate (CS). Patients with MPSIVA typically present with severe skeletal and joint disorders, which are not addressed by conventional therapies. Currently, no animal model accurately replicates the human disease, hindering the development of novel therapeutic interventions. To overcome this limitation, we established, by CRISPR-Cas9 technology, a Galns−/− mouse model that expresses a non-functional enzyme and accumulates CS and KS in the urine, plasma and distinct tissues, and glycosaminoglycans in the spleen. The mice exhibit shortened long bones, trabecular bone alterations and skeletal abnormalities in the growth plate. Additionally, we observed increased levels of inflammatory and oxidative markers in visceral organs and plasma. Our newly developed model of MPSIVA demonstrates clear and quantifiable signs of skeletal alterations, providing novel means of assessment of the safety and efficacy of innovative therapies, including hematopoietic stem and progenitor cell gene therapy, which has recently been shown to provide a beneficial effect on skeletal alterations in Hurler syndrome.

Keratan sulfate revisited: UPLC-MS/MS-based quantitative profiling reveals structural heterogeneity and deficiency in ocular pathologies.

Synthesis of and characterization of differentially sulfated disaccharide repeating units of keratan sulfate.

Targeted AAV6 gene therapy restores corneal endothelial function in three hereditary corneal dystrophies

221P Gynaecological sarcomas: Clinical outcomes of rare molecular subgroups

223P Ultra-rare sarcomas in India: A 5-year single-institution clinicopathological landscape (2021–2025)

222P A hybrid text-knowledge graph retrieval-augmented generation system for clinical decision support in soft tissue sarcoma

Mucopolysaccharidosis IVA (MPS IVA) is caused by the accumulation of undegraded glycosaminoglycans due to the deficiency of the N-acetylgalactosamine-6-sulfate sulfatase (GALNS) enzyme. MPS IVA manifests as progressive systemic skeletal dysplasia. Gene therapy (GT) is potentially a one-time treatment in which the enzyme is continuously produced, circulated, and delivered to target tissues. However, immune responses to gene products can diminish therapeutic efficacy. We hypothesized that oral delivery of tolerogenic peptides induces immune tolerance to human GALNS (hGALNS) in MPS IVA mice, enhancing therapeutic efficacy. Neonatal mice deficient in mouse GALNS (mGALNS) were treated orally with three T-cell/B-cell epitope peptides or hGALNS protein on alternate days from day 3 after birth to day 20 before intravenous injection with AAV9 vectors encoding human GALNS on day 30. The results are encouraging, with anti-hGALNS antibodies undetectable in the plasma of orally administered peptide groups. hGALNS enzyme activities in plasma and tissues were higher in the orally treated groups than in the non-tolerized control group. Keratan sulfate levels in plasma, liver, and bone were normalized. Complete correction for heart vacuolization was achieved in peptide-treated groups, and partial correction for bone pathology was observed in all GT-treated groups. Overall, oral tolerance induction using immunodominant peptides promises to significantly enhance the efficacy of AAV-GT for MPS IVA.

This narrative review outlines the structure and essential functions of ocular proteoglycans (PGs) in visual processing as documented in the extensive literature on this subject matter. The eye, as one of the most complex sensory organs, relies on the coordinated activity of various tissues and cell types, with PGs playing a central role in facilitating communication and maintaining tissue function. These molecules stabilise ocular tissues; for example, SPACRCAN (IMPG2) and hyaluronan aggregates in the interphotoreceptor matrix protect photoreceptors from oxidative stress. Specialised heparan sulfate PGs, such as pikachurin, eyes-shut, and the neurexin family, stabilise synapses and ensure synaptic specificity and plasticity. Pikachurin is particularly important for the rapid transmission of visual signals at the bipolar ribbon synapse. A diverse array of chondroitin sulfate (aggrecan, versican, neurocan, brevican, phosphacan, NG2), keratan sulfate (SV2), and heparan sulfate (perlecan, agrin, collagen XVIII) PGs are differentially expressed in ocular tissues, contributing to tissue stability and homeostasis. In the cornea, sclera, and choroid, small leucine-rich repeat PGs (SLRPs) maintain three-dimensional structure, corneal transparency, and tissue function through interactions with cytokines and growth factors. The vitreous humour contains opticin and nyctalopin, which support the nutrition of avascular regions and facilitate bipolar ribbon synapse signalling. Ultimately, the effectiveness of the eye as a visual organ depends significantly on the functional roles of its constituent PGs.

Morquio syndrome A, also known as mucopolysaccharidosistype IVA(MPS IVA), is a lysosomal storage disorder resulting from mutationsin the gene responsible for N-acetylgalactosamine-6-sulfatase.The deficiency of this enzyme impairs the degradation of glycosaminoglycans,particularly chondroitin 6-sulfate and keratan sulfate. This researchuses a variety of computational techniques for analyzing the GALNSvariants mainly causing child death and to provide better healthcare.The variants were collected from research sources, such as PubMed,ResearchGate, and ScienceDirect, along with databases like HGMD, ClinVar,and UniProt. The analysis of the conservation, pathogenicity, andstability of the variations was conducted utilizing algorithms suchas ConSurf, PredictSNP, and iStable. Structural analysis was carriedout using the PDB databank and PyMOL software. Molecular docking wasused to study the interaction of native and variant GALNS proteinswith Ezetimibe. GROMACS was used to simulate the behavior of the GALNSprotein with variants and Ezetimibe binding in docked complexes forover 100 ns. A total of 345 SNP variants were retrieved, of whichD40H, C79R, and C79L variants were identified to be highly deleteriousafter conservation (75 SNPs), pathogenicity (5 SNPs), and biophysicaland stability (3 SNPs) analysis. During docking, the native proteindemonstrated a strong binding affinity of −8.54 kcal/mol forthe drug. The C79R variant displayed a binding affinity of −8.41kcal/mol, while the C79L and D40H variants showed affinities of −7.07and −7.92 kcal/mol, respectively. MD simulations of the nativeand variant structures showed similar ligand binding flexibility andstability, confirmed by RMSD, RMSF, H-bond, and gyration plots. Theincreased binding affinity and stability of both complexes suggestthat Ezetimibe has comparable therapeutic effects for both the nativeand variant forms. This work provides detailed structural and dynamicinsights into the GALNS protein, paving the way for further researchand new treatments for Morquio syndrome A.

O-Mannose (Man) glycans are branched specifically in the brain by a dedicated glycosyltransferase, N-acetylglucosaminyltransferase IX (GnT-IX, also known as MGAT5B). Such branching of O-Man glycans was reported to be involved in diseases, including demyelination and glioma, but the enzymatic mechanisms by which O-Man glycan is specifically recognized by GnT-IX and how branched O-Man glycans are subsequently elongated by other enzymes in the brain have remained unclear. To shed light on these issues, we here first compared the structural model of GnT-IX complexed with its O-Man substrate with the crystal structure of the homologous N-glycan branching enzyme GnT-V (also known as MGAT5). Several residues in GnT-IX were predicted to be critical to recognition of the O-Man substrate, and an enzyme assay revealed that R304 in GnT-IX is crucial for the specificity toward O-Man glycans. We further investigated the role of O-Man branching for subsequent elongation in the brain and found that the level of keratan sulfate (KS) in O-Man glycans was significantly reduced in GnT-IX-knockout (KO) mouse brain, suggesting that O-Man branching promotes KS biosynthesis. Mechanistically, our enzymatic assays of the KS biosynthetic enzymes demonstrated that B4GALT1, B4GALT4, and CHST1 exhibited significantly higher activity toward branched O-Man glycans than toward their linear counterparts. These results imply that branching of O-Man glycans by GnT-IX provides the scaffold for efficient subsequent glycan elongation. Our findings deepen our understanding of the complex biosynthetic pathway of O-Man glycans in the brain.

Allogeneic Hematopoietic Cell Transplantation for Morquio A Syndrome: An International Retrospective Study.

This study reviews the roles of proton electrochemical gradients in ubiquitous mitochondrial energy production systems in cellular activation and functions in neurosensory signaling. Proton electrochemical gradients crucially shaped the evolution of life. The emergence of the proton-motive force in mitochondria was fundamental in energy production and central to the function of eukaryotic cells. Dysfunctional mitochondria, however, result in impaired formation of proton gradients and a wide spectrum of diseases. This is particularly prominent in tissues with high energetic demands, such as muscle and nervous tissues. Oxidant stress generated by dysfunctional proton conductance in the brain results in Alzheimer's and Parkinson's disease, muscular sclerosis, amyotrophic sclerosis, and Huntington's disease. In these disorders, oxidative stress, protein misfolding, and neuroinflammation lead to dysfunctional neuronal activity, neuronal damage, and death. Advancements in nanozyme-engineered synthetic enzymes offer a promising innovative approach to the treatment of these disorders. Nanozymes target proton conductance and the oxidant species they generate, scavenging oxygen free radicals and restoring redox balance, and offer neuronal protection and functional recovery of brain tissues. Neural injury and associated neurological diseases affect almost 1 billion people globally, so there is a clear need to develop effective methods that stimulate neural repair and regeneration. Glycosaminoglycans with proton capture and transport properties regulate intercellular signaling processes, synaptic functions, and cellular communication. Electroconductive hydrogels are showing impressive results in neural repair and regeneration. Glycosaminoglycans, particularly keratan sulfate, show useful electroconductive proton capture and transport properties, suggesting they may be worth evaluation in such procedures.

Corneal transplantation, the primary treatment for corneal blindness, faces challenges, including donor tissue scarcity and complications, necessitating innovative therapeutic approaches. This study investigates a bioink composed of Gelatin Methacryloyl (GelMA) and Carboxymethyl Chitosan (CMCh) for 3D bioprinting corneal scaffolds. GelMA provides light-activated crosslinking, while CMCh enhances printability. We optimized the rheological properties of bioink and 3D printing parameters to fabricate high-resolution scaffolds, followed by a comprehensive analysis of their physical-chemical attributes, thermal properties, morphology, degradation, swelling ratio, and mechanical properties. Comprehensive material characterization showed that incorporation of CMCh into GelMA enhanced thermal stability, and light transmittance up to 80% after 14 days. Biocompatibility was evaluated using goat corneal stromal cells, demonstrating proliferation and viability within the scaffolds via live/dead assay and MTT assay. Immunofluorescence and gene expression analyses confirmed the maintenance of the stromal keratocyte phenotype, indicated by increased expression of Keratan sulfate and Lumican over 14 days, with minimal α-SMA expression, preventing myofibroblast transformation. These results suggest that GelMA/CMCh hydrogels provide a suitable environment for corneal stromal keratocytes, supporting their potential use in tissue-engineered corneal substitutes.

Mucopolysaccharidosis (MPS IVA) is caused by pathogenic variations in the GALNS gene, leading to the accumulation of glycosaminoglycans in tissues and causing progressive skeletal lesions. While conventional lentiviral vectors (LVs) provide long-term stable expression, they do not deliver therapeutic levels to bone and cartilage. We hypothesized that engineering the LV envelope with a collagen type II-targeting peptide (WYRGRL) increases the binding affinity of the LVs for bone and cartilage. These modified vectors carrying the CBh and COL2A1 promoters delivered the GALNS gene to MPS IVA newborn mice via intravenous (IV) or intraarticular (IA) administration. The peptide-modified LVs exhibited markedly increased uptake in the liver when administered IV, but lower enzyme activity than that of the conventional vector. The modified WYRGRL-LV-COL2A1 vector elevated GALNS activity in other tissues, suggesting systemic benefits. When administered IA, the modified vectors showed potential for local treatment due to the WYRGRL peptide-mediated uptake. Additionally, there was a reduction in keratan sulfate glycosaminoglycan levels in plasma and tissues, indicating that this peptide can be a suitable candidate for disease modification. These findings pave the way for further preclinical and clinical studies, offering new possibilities for the development of targeted therapies for skeletal diseases.