The influence of ions on the lubricative abilities of mucin and the role of sialic acids

Reduced sialylation of airway mucin impairs mucus transport by altering the biophysical properties of mucin

Mucus stasis is a pathologic hallmark of muco-obstructive diseases, including cystic fibrosis (CF). Mucins, the principal component of mucus, are extensively modified with hydroxyl (O)-linked glycans, which are largely terminated by sialic acid. Sialic acid is a negatively charged monosaccharide and contributes to the biochemical/biophysical properties of mucins. Reports suggest that mucin sialylation may be altered in CF; however, the consequences of reduced sialylation on mucus clearance have not been fully determined. Here, we investigated the consequences of reduced sialylation on the charge state and conformation of the most prominent airway mucin, MUC5B, and defined the functional consequences of reduced sialylation on mucociliary transport (MCT). Reduced sialylation contributed to a lower charged MUC5B form and decreased polymer expansion. The inhibition of total mucin sialylation de novo impaired MCT in primary human bronchial epithelial cells and rat airways, and specific α-2,3 sialylation blockade was sufficient to recapitulate these findings. Finally, we show that ST3 beta-galactoside alpha-2,3-sialyltransferase (ST3Gal1) expression is downregulated in CF and partially restored by correcting CFTR via Elexacaftor/Tezacaftor/Ivacaftor treatment. Overall, this study demonstrates the importance of mucin sialylation in mucus clearance and identifies decreased sialylation by ST3Gal1 as a possible therapeutic target in CF and potentially other muco-obstructive diseases.

Mucoadhesive phenylboronic acid-grafted carboxymethyl cellulose hydrogels containing glutathione for treatment of corneal epithelial cells exposed to benzalkonium chloride

Benzalkonium chloride (BAK) is the most commonly-used preservative in topical ophthalmic medications that may cause ocular surface inflammation associated with oxidative stress and dry eye syndrome. Glutathione (GSH) is an antioxidant in human tears and able to decrease the proinflammatory cytokine release from cells and reactive oxygen species (ROS) formation. Carboxymethyl cellulose (CMC), a hydrophilic polymer, is one of most commonly used artificial tears and can promote the corneal epithelial cell adhesion, migration and re-epithelialization. However, most of commercial artificial tears provide only temporary relief of irritation symptoms and show the short-term treatment effects. In the study, 3-aminophenylboronic acid was grafted to CMC for increase of mucoadhesive properties that might increase the precorneal retention time and maintain the effective therapeutic concentration on the ocular surface. CMC was modified with different degree of substitution (DS) and characterized by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Phenylboronic acid (PBA)-grafted CMC hydrogels have interconnected porous structure and shear thinning behavior. Modification of CMC with high DS (H-PBA-CMC) shows the strong bioadhesive force. The optimal concentration of GSH to treat corneal epithelial cells (CECs) was evaluated by cell viability assay. H-PBA-CMC hydrogels could sustained release GSH and decrease the ROS level. H-PBA-CMC hydrogels containing GSH shows the therapeutic effects in BAK-damaged CECs via improvement of inflammation, apoptosis and cell viability. After topical administration of developed hydrogels, there was no ocular irritation in rabbits. These results suggested that PBA-grafted CMC hydrogels containing GSH might have potential applications for treatment of dry eye disease.

Reduced Sialylation of Airway Mucin Impairs Mucus Transport by Altering the Biophysical Properties of Mucin

Mucus stasis is a pathologic hallmark of muco-obstructive diseases, including cystic fibrosis (CF). Mucins, the principal component of mucus, are extensively modified with hydroxyl (O)-linked glycans, which are largely terminated by sialic acid. Sialic acid is a negatively charged monosaccharide and contributes to the biochemical/biophysical properties of mucins. Reports suggest that mucin sialylation may be altered in CF; however, the consequences of reduced sialylation on mucus clearance have not been fully determined. Here, we investigated the consequences of reduced sialylation on the charge state and conformation of the most prominent airway mucin, MUC5B, and defined the functional consequences of reduced sialylation on mucociliary transport (MCT). Reduced sialylation contributed to a lower charged MUC5B form and decreased polymer expansion. The inhibition of total mucin sialylation de novo impaired MCT in primary human bronchial epithelial cells and rat airways, and specific α-2,3 sialylation blockade was sufficient to recapitulate these findings. Finally, we show that ST3 beta-galactoside alpha-2,3-sialyltransferase (ST3Gal1) expression is downregulated in CF and partially restored by correcting CFTR via Elexacaftor/Tezacaftor/Ivacaftor treatment. Overall, this study demonstrates the importance of mucin sialylation in mucus clearance and identifies decreased sialylation by ST3Gal1 as a possible therapeutic target in CF and potentially other muco-obstructive diseases.

Genetics of Gallstone Disease and Their Clinical Significance: A Narrative Review

Gallstone (GS) disease is common and arises from a combination of genetic and environmental factors. Although genetic abnormalities specifically leading to cholesterol GSs are rare, there are clinically significant gene variants associated with cholesterol GSs. In contrast, most bilirubin GSs can be attributed to genetic defects. The pathogenesis of cholesterol and bilirubin GSs differs greatly. Cholesterol GSs are notably influenced by genetic variants within the ABC protein superfamily, including ABCG8, ABCG5, ABCB4, and ABCB11, as well as genes from the apolipoprotein family such as ApoB100 and ApoE (especially the E3/E3 and E3/E4 variants), and members of the MUC family. Conversely, bilirubin GSs are associated with genetic variants in highly expressed hepatic genes, notably UGT1A1, ABCC2 (MRP2), ABCC3 (MRP3), CFTR, and MUC, alongside genetic defects linked to hemolytic anemias and conditions impacting erythropoiesis. While genetic cases constitute a small portion of GS disease, recognizing genetic predisposition is essential for proper diagnosis, treatment, and genetic counseling.

Inhibition of water-diluted precipitate formation from egg whites by ultrasonic pretreatment: Insights from quantitative proteomics analysis

The formation of the egg white precipitate (EWP) during dilution poses challenges in food processing. In this paper, the effects of 90 W and 360 W ultrasonic intensities on the inhibition of EWP formation were investigated. The findings revealed that 360 W sonication effectively disrupted protein aggregates, decreasing the dry matter of EWP by 5.24 %, particle size by 57.86 %, and viscosity by 82.28 %. Furthermore, the ultrasonic pretreatment unfolded protein structures and increased the content of β-sheet structures. Combined with quantitative proteomics and intermolecular forces analysis, the mechanism by which ultrasonic pretreatment inhibited water-diluted EWP formation by altering protein interactions was proposed: ultrasonic pretreatment disrupted electrostatic interactions centered on lysozyme, as well as hydrogen-bonding interactions between ovomucin and water. In conclusion, our research provides valuable insights into the application of ultrasonic pretreatment as a means to control and improve the quality of egg white-based products.

In Vivo Cancer Microenvironment Responsive Glycan Receptor-Targeted Nanoparticles for Gemcitabine Delivery to Benzo[a]pyrene-Induced Lung Cancer Model

Targeted gemcitabine (GEB) loaded 5-N-acetyl-neuraminic acid (Neu5Ac) assembled chitosan nanoparticles (CA-NPs) were formulated by ionotropic gelation process and evaluated for physicochemical and morphological characterization, in vitro and in vivo studies in A-549 cells and lung cancer mice model, respectively. The mean diameter of GEB-CA-Neu5Ac-NPs determined by dynamic light scattering was 161.16 ± 7.70 nm with a polydispersity index (PDI) value of 0.303 ± 0.011 and its zeta potential and entrapment efficiency (%EE) were 40.3 ± 3.45 mv and 66.11 ± 1.94%, respectively. The in vitro cellular uptake studies showed that glycan receptor-targeted nanoparticles deliver significantly more amount (p < 0.001) of GEB into the A-549 lung cancerous cells than non-targeted nanoparticles. The cytotoxicity study using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay clearly demonstrated that GEB-CA-Neu5Ac-NPs have lower IC50 value (6.39 ± 3.78 µg/ml) than others groups that showed that the greater lung cancerous cells inhibition potential of targeted nanoparticles. The in vivo biodistribution of the GEB-loaded 5-N-acetyl-neuraminic acid conjugated chitosan nanoparticles was revealed that targeted nanoparticles showed higher accumulation and retention for an extended period of time due to the active targeting ability of Neu5Ac to glycan receptors. Histopathological examination showed significant recovery in the physiological architecture upon administration of targeted nanoparticles. The glycan receptor-targeted nanoparticles treated groups showed a significant decline in the number of metastatic lung epithelial cells, as compared to the untreated positive control group (p < 0.001) confirming higher anticancer efficacy of the GEB-CA-Neu5Ac-NPs.