Nanogels with covalently bound and releasable trehalose for autophagy stimulation in atherosclerosis.

Atherosclerosis, cholesterol-driven plaque formation in arteries, is a complex multicellular disease which is a leading cause of vascular diseases. During the progression of atherosclerosis, the autophagic function is impaired, resulting in lipid accumulation-mediated foam cell formation. The stimulation of autophagy is crucial for the recovery of cellular recycling process. One of the potential autophagy inducers is trehalose, a naturally occurring non-reducing disaccharide. However, trehalose has poor bioavailability due to its hydrophilic nature which results in poor penetration through cell membranes. To enhance its bioavailability, we developed trehalose-releasing nanogels (TNG) for the treatment of atherosclerosis. The nanogels were fabricated through copolymerization of 6-O-acryloyl-trehalose with the selected acrylamide-type monomers affording a high trehalose conjugation (~ 58%, w/w). TNG showed a relatively small hydrodynamic diameter (dH, 67 nm) and a uniform spherical shape and were characterized by negative ζ potential (-18 mV). Thanks to the trehalose-rich content, TNG demonstrated excellent colloidal stability in biological media containing serum and were non-hemolytic to red blood cells. In vitro study confirmed that TNG could stimulate autophagy in foam cells and enhance lipid efflux and in vivo study in ApoE-/- mice indicated a significant reduction in atherosclerotic plaques, while increasing autophagic markers. In conclusion, TNG hold great promise as a trehalose delivery system to restore impaired autophagy-mediated lipid efflux in atherosclerosis and subsequently reduce atherosclerotic plaques.

Trehalose-Bearing Carriers to Target Impaired Autophagy and Protein Aggregation Diseases.

In recent years, trehalose, a natural disaccharide, has attracted growing attention because of the discovery of its potential to induce autophagy. Trehalose has also been demonstrated to preserve the protein's structural integrity and to limit the aggregation of pathologically misfolded proteins. Both of these properties have made trehalose a promising therapeutic candidate to target autophagy-related disorders and protein aggregation diseases. Unfortunately, trehalose has poor bioavailability due to its hydrophilic nature and susceptibility to enzymatic degradation. Recently, trehalose-bearing carriers, in which trehalose is incorporated either by chemical conjugation or physical entrapment, have emerged as an alternative option to free trehalose to improve its efficacy, particularly for the treatment of neurodegenerative diseases, atherosclerosis, nonalcoholic fatty liver disease (NAFLD), and cancers. In the current Perspective, we discuss all existing literature in this emerging field and try to identify key challenges for researchers intending to develop trehalose-bearing carriers to stimulate autophagy or inhibit protein aggregation.

A Simple Synthesis of Reduction-Responsive Acrylamide-Type Nanogels for miRNA Delivery.

MicroRNAs (miRNAs) have great therapeutic potential; however, their delivery still faces huge challenges, especially given the short half-life of naked miRNAs due to rapid hydrolysis or inactivation by abundant nucleases in the systemic circulation. Therefore, the search for reliable miRNA delivery systems is crucial. Nanogels are one of the more effective nanocarriers because they are biocompatible and have a high drug-loading capacity. In this study, acrylamide-based nanogels containing cationic groups and redox-sensitive crosslinkers were developed for cellular delivery of anti-miR21 (a-miR21). To achieve this, post-polymerization loading of a-miR21 oligonucleotides into nanogels was performed by utilizing the electrostatic interaction between positively charged nanogels and negatively charged oligonucleotides. Different molar ratios of the amine groups (N) on the cationic nanogel and phosphate groups (P) on the miRNA were investigated. An N/P ratio of 2 allowed high miRNA loading capacity (MLC, 6.7% w/w) and miRNA loading efficiency (MLE, 99.7% w/w). Successful miRNA loading was confirmed by dynamic light scattering (DLS) and electrophoretic light scattering (ELS) measurements. miRNA-loaded nanogels (NG/miRNA) formed stable dispersions in biological media and showed an enhanced miRNA release profile in the presence of glutathione (GSH). Moreover, the addition of heparin to dissociate the miRNA from the cationic nanogels resulted in the complete release of miRNA. Lastly, a cell uptake study indicated that NG/miRNA could be easily taken up by cancer cells.

The tetraspanin transmembrane protein CD53 mediates dyslipidemia and integrates inflammatory and metabolic signaling in hepatocytes.

Tetraspanins are transmembrane signaling and proinflammatory proteins. Prior work demonstrates that the tetraspanin, CD53/TSPAN25/MOX44, mediates B-cell development and lymphocyte migration to lymph nodes and is implicated in various inflammatory diseases. However, CD53 is also expressed in highly metabolic tissues, including adipose and liver; yet its function outside the lymphoid compartment is not defined. Here, we show that CD53 demarcates the nutritional and inflammatory status of hepatocytes. High-fat exposure and inflammatory stimuli induced CD53 in vivo in liver and isolated primary hepatocytes. In contrast, restricting hepatocyte glucose flux through hepatocyte glucose transporter 8 deletion or through trehalose treatment blocked CD53 induction in fat- and fructose-exposed contexts. Furthermore, germline CD53 deletion in vivo blocked Western diet-induced dyslipidemia and hepatic inflammatory transcriptomic activation. Surprisingly, metabolic protection in CD53 KO mice was more pronounced in the presence of an inciting inflammatory event. CD53 deletion attenuated tumor necrosis factor alpha-induced and fatty acid + lipopolysaccharide-induced cytokine gene expression and hepatocyte triglyceride accumulation in isolated murine hepatocytes. In vivo, CD53 deletion in nonalcoholic steatohepatitis diet-fed mice blocked peripheral adipose accumulation and adipose inflammation, insulin tolerance, and liver lipid accumulation. We then defined a stabilized and trehalase-resistant trehalose polymer that blocks hepatocyte CD53 expression in basal and over-fed contexts. The data suggest that CD53 integrates inflammatory and metabolic signals in response to hepatocyte nutritional status and that CD53 blockade may provide a means by which to attenuate pathophysiology in diseases that integrate overnutrition and inflammation, such as nonalcoholic steatohepatitis and type 2 diabetes.

pH and Reduction Dual-Responsive Nanogels as Smart Nanocarriers to Resist Doxorubicin Aggregation.

The use of smart nanocarriers that can modulate therapeutic release aided by biological cues can prevent undesirable cytotoxicity caused by the premature release of cytotoxic drugs during nanocarrier circulation. In this report, degradable nanocarriers based on pH/reduction dual-responsive nanogels were synthesized to encapsulate doxorubicin hydrochloride (DOX) and specifically boost the release of DOX in conditions characteristic of the cancer microenvironment. Nanogels containing anionic monomer 2-carboxyethyl acrylate (CEA) and N,N'-bis(acryloyl)cystamine (CBA) as a degradable crosslinker have been successfully synthesized via photoinitiated free radical polymerization. The loading process was conducted after polymerization by taking advantage of the electrostatic interaction between the negatively charged nanogels and the positively charged DOX. In this case, a high drug loading capacity (DLC) of up to 27.89% was achieved. The entrapment of DOX into a nanogel network could prevent DOX from aggregating in biological media at DOX concentrations up to ~160 µg/mL. Anionic nanogels had an average hydrodynamic diameter (dH) of around 90 nm with a negative zeta (ζ) potential of around -25 mV, making them suitable for targeting cancer tissue via the enhanced permeation effect. DOX-loaded nanogels formed a stable dispersion in different biological media, including serum-enriched cell media. In the presence of glutathione (GSH) and reduced pH, drug release was enhanced, which proves dual responsivity. An in vitro study using the HCT 116 colon cancer cell line demonstrated the enhanced cytotoxic effect of the NG-CBA/DOX-1 nanogel compared to free DOX. Taken together, pH/reduction dual-responsive nanogels show promise as drug delivery systems for anticancer therapy.

Trehalose-releasing nanogels: A step toward a trehalose delivery vehicle for autophagy stimulation.

Trehalose has been widely studied as a treatment for a variety of human disorders due to its ability to stimulate autophagy. Trehalose, however, is poorly adsorbed and is hydrolyzed in the intestinal mucosa, and oral delivery requires relatively high doses to induce autophagy. The parenteral injection of trehalose-releasing nanogels proposed in this study offers an alternative mode of delivery. This study aimed to develop stable colloidal dispersions of trehalose-rich nanogels that could sustainably release trehalose under physiologically relevant conditions. The nanogel design was based on the covalent incorporation of 6-O-acryloyl-trehalose within a polymer network. A series of nine trehalose-rich nanogels with highly conjugated trehalose (up to 59 % w/w) were synthesized and shown to sustainably release trehalose at a rate that is not dose dependent. The nanogels were optimized to keep colloidal stability in serum-enriched cell culture media. The stable nanogels were not cytotoxic to primary HUVECs. Two selected nanogels with opposite surface charges were subjected to extended in vitro characterization that included a cellular uptake study and a hemocompatibility assay. Both nanogels were efficiently taken up by HUVECs during a short incubation. They also proved not to be hemolytic to human RBCs in concentrations up to 2.0 mg/mL. Finally, an in vivo autophagy stimulation study employing transgenic zebrafish and Drosophila larvae demonstrated that prolonged exposure to a cationic trehalose-releasing nanogel can induce autophagic activity in in vivo systems without any detectable toxicity.

Microchamber microfluidics combined with thermogellable glycomicrogels - Platform for single cells study in an artificial cellular microenvironment.

Microfluidic technology is a powerful tool to precisely establish artificial microenvironments and has been used to generate numerous biomimetic devices. Here, we present a combined microenvironment platform, which consists of microchamber microfluidics filled with thermoresponsive glycomicrogels, and enables live-cell immobilization and continuous observation. Poly(N-isopropylacrylamide) microgels containing trehalose has been selected from our previous study to possess adequate physicochemical characteristics and provide potential multivalent interactions with cell surfaces. We show that the designed microplatform enables small population of cells to be trapped in individual parallel microchambers and further immobilized in an artificial extracellular matrix. We applied our platform to long-term imaging experiments and studied HeLa cell growth dynamics under continuous, diffusion-dominated medium exchange. The mathematical modeling revealed that regardless of the initial number of cells, the growth dynamic follows the exponential growth pattern over the analyzed timespan (one week). These results confirm that the presented microsystem facilitates the long-term cell culture in a cellular-mimicking microenvironment without reaching environmental constraints.

A Mini-Review on Chitosan-Based Hydrogels with Potential for Sustainable Agricultural Applications.

Agriculture is an important sector of the economy, but this industry consumes significant amounts of water, which is a precious and limited natural resource. Irrigation techniques and efforts to mitigate water usage influence the growth, survival, and yield of crops. However, superabsorbent polymers in combination with fertilizers can be employed to obtain sustained release of nutrients and improved water retention capacity of the soil. Despite significant recent progress in this area involving synthetic polyacrylate hydrogels, there are no industrially applicable solutions exhibiting similar performance using natural biopolymers or synthetic polymers enriched with natural components. This review focuses on biodegradable chitosan-based hydrogels (both natural and semi-synthetic), and discusses their potential agricultural and horticultural applications. The methods for synthesizing hydrogels via physical or chemical crosslinking, and the resulting functional properties of recently reported hydrogels, such as water retention and release of active ingredients, are presented herein.

Trehalose-Rich, Degradable Hydrogels Designed for Trehalose Release under Physiologically Relevant Conditions.

Trehalose, a natural disaccharide, is primarily known for its ability to protect proteins from inactivation and denaturation caused by a variety of stress conditions. Furthermore, over the past few years, it has emerged as a promising therapeutic candidate for treatment of neurodegenerative diseases. Herein, we examine the attachment of trehalose to polymers for release under selected physiologically relevant conditions. The proposed strategies are evaluated specifically using hydrogels undergoing simultaneous degradation during trehalose release. These materials are fabricated via copolymerization of the appropriate acrylamide-type monomers with polymerizable trehalose esters or benzylidene acetals. This provides trehalose release in a slightly alkaline (i.e., pH 7.4) or mildly acidic (i.e., pH 5.0) environment, respectively. Using this method materials containing up to 51.7 wt% of trehalose are obtained. The presented results provide a solid basis for future studies on polymeric materials intended for trehalose release in biological systems.

Selected nucleos(t)ide-based prescribed drugs and their multi-target activity.

Nucleos(t)ide analogues play pivotal roles as antiviral, cytotoxic or immunosuppressive agents. Here, we review recent reports of nucleoside analogues that exhibit broad-spectrum activity towards multiple life-threatening RNA and DNA viruses. We also present a discussion about nucleoside antimetabolites-approved antineoplastic agents-that have recently been shown to have antiviral and/or antibacterial activity. The approved drugs and drug combinations, as well as recently identified candidates for investigation and/or experimentation, are discussed. Several examples of repurposed drugs that have already been approved for use are presented. This strategy can be crucial for the first-line treatment of acute infections or coinfections and for the management of drug-resistant strains.

Antiviral Activity of Uridine Derivatives of 2-Deoxy Sugars against Tick-Borne Encephalitis Virus.

Tick-borne encephalitis virus (TBEV) is a causative agent of tick-borne encephalitis (TBE), one of the most important human infections involving the central nervous system. Although effective vaccines are available on the market, they are recommended only in endemic areas. Despite many attempts, there are still no specific antiviral therapies for TBEV treatment. Previously, we synthesized a series of uridine derivatives of 2-deoxy sugars and proved that some compounds show antiviral activity against viruses from the Flaviviridae and Orthomyxoviridae families targeting the late steps of the N-glycosylation process, affecting the maturation of viral proteins. In this study, we evaluated a series of uridine derivatives of 2-deoxy sugars for their antiviral properties against two strains of the tick-borne encephalitis virus; the highly virulent TBEV strain Hypr and the less virulent strain Neudoerfl. Four compounds (2, 4, 10, and 11) showed significant anti-TBEV activity with IC50 values ranging from 1.4 to 10.2 µM and low cytotoxicity. The obtained results indicate that glycosylation inhibitors, which may interact with glycosylated membrane TBEV E and prM proteins, might be promising candidates for future antiviral therapies against TBEV.

Anti-Hepatitis C Virus Activity of Uridine Derivatives of 2-Deoxy Sugars.

Hepatitis C virus (HCV), the etiological agent of the most common and dangerous diseases of the liver, is a major health problem worldwide. Despite many attempts, there is still no vaccine available. Although many drugs have been approved for use mostly in combination regimen, their high costs make them out of reach in less developed regions. Previously, we have synthesized a series of compounds belonging to uridine derivatives of 2-deoxy sugars and have proved that some of them possess antiviral activity against influenza A virus associated with N-glycosylation inhibition. Here, we analyze the antiviral properties of these compounds against HCV. Using cell culture-derived HCV (HCVcc), HCV pseudoparticles (HCVpp), and replicon cell lines, we have shown high anti-HCV activity of two compounds. Our results indicated that compounds 2 and 4 significantly reduced HCVcc propagation with IC50 values in low µM range. Further experiments using the HCVpp system confirmed that both compounds significantly impaired the infectivity of produced HCVpp due to the inhibition of the correct maturation of viral glycoproteins. Overall, our results suggest that inhibiting the glycosylation process might be a good target for new therapeutics not only against HCV, but other important viral pathogens which contain envelopes with highly glycosylated proteins.

Biological Evaluation of Uridine Derivatives of 2-Deoxy Sugars as Potential Antiviral Compounds against Influenza A Virus.

Influenza virus infection is a major cause of morbidity and mortality worldwide. Due to the limited ability of currently available treatments, there is an urgent need for new anti-influenza drugs with broad spectrum protection. We have previously shown that two 2-deoxy sugar derivatives of uridine (designated IW3 and IW7) targeting the glycan processing steps during maturation of viral glycoproteins show good anti-influenza virus activity and may be a promising alternative approach for the development of new anti-influenza therapy. In this study, a number of IW3 and IW7 analogues with different structural modifications in 2-deoxy sugar or uridine parts were synthesized and evaluated for their ability to inhibit influenza A virus infection in vitro. Using the cytopathic effect (CPE) inhibition assay and viral plaque reduction assay in vitro, we showed that compounds 2, 3, and 4 exerted the most inhibitory effect on influenza virus A/ostrich/Denmark/725/96 (H5N2) infection in Madin-Darby canine kidney (MDCK) cells, with 50% inhibitory concentrations (IC50) for virus growth ranging from 82 to 100 (µM) without significant toxicity for the cells. The most active compound (2) showed activity of 82 µM with a selectivity index value of 5.27 against type A (H5N2) virus. Additionally, compound 2 reduced the formation of HA glycoprotein in a dose-dependent manner. Moreover, an analysis of physicochemical properties of studied compounds demonstrated a significant linear correlation between lipophilicity and antiviral activity. Therefore, inhibition of influenza A virus infection by conjugates of uridine and 2-deoxy sugars is a new promising approach for the development of new derivatives with anti-influenza activities.

New N-substituted hydrazones, derivatives of uridyl aldehyde.

N-substituted isomeric hydrazones of uridyl aldehyde have been synthesized. The occurrence of the dominant E isomers with respect to the azomethine group was confirmed by means of NMR spectroscopy. Synthesized hydrazones feature an acetonide moiety as a protection of two hydroxyl groups on the ribose part. The attempt to remove the protecting group resulted in an azo-hydrazone tautomeric mixture. The described compounds may be valuable chiral ligands for metal chelation. Assessment of manganese(II) ion affinity to one selected hydrazone was performed.

Thermoresponsive microgels containing trehalose as soft matrices for 3D cell culture.

A series of thermoresponsive glycomicrogels with trehalose in the cross-links or with trehalose in the cross-links and as pending moieties was synthesized. These materials were obtained by surfactant-free precipitation copolymerization of N-isopropylacrylamide and various amounts of trehalose monomers. The resultant particles showed a spherical shape and a submicrometer hydrodynamic size with a narrow size distribution. At 25 °C, glycomicrogels in solutions with physiological ionic strength formed stable colloids, which further gelled upon heating to physiological temperature forming a macroscopic hydrogel with an interconnected porous structure. These extremely soft matrices with dynamic storage modulus in the range of 9-70 Pa were examined in 3D culture systems for HeLa cell culture in comparison to traditional 2D mode. They showed relatively low syneresis over time, especially when glycomicrogels with a high content of hydrophilic trehalose were used as building blocks. An incorporated pending trehalose composed of two α,α'-1,1'-linked d-glucose moieties was used with the intention of providing multivalent interactions with glucose transporters (GLUTs) expressed on the cell surface. A better cell viability was observed when a soft hydrogel with the highest content of trehalose and the lowest syneresis was used as a matrix compared to a 2D control assay.

New monomeric and dimeric uridinyl derivatives as inhibitors of chitin synthase.

This study described the synthesis and in vitro evaluation of eight new derivatives of uridine as antifungal agents and inhibitors of chitin synthase. Dimeric uridinyl derivatives synthesized by us did not exhibit significant activity. One of the studied monomeric derivative, 5'-(N-succinyl)-5'-amino-5'-deoxyuridine methyl ester (compound 7) showed activities against several fungal strains (MIC range 0.06-1.00 mg/mL) and inhibited chitin synthase from Saccharomyces cerevisiae (IC50=0.8mM). Moreover compound 7 exhibited synergistic interaction with caspofungin against Candida albicans (FIC index=0.28).

Synthesis and biological evaluation of 5'-glycyl derivatives of uridine as inhibitors of 1,4-ß-galactosyltransferase.

New 5'-glycyl derivatives of uridine containing fragments of varying lipophilicity were synthesized as analogues of natural peptidyl antibiotics. One of the studied compounds, 5'-O-(N-succinylglycyl)-2',3'-O-isopropylideneuridine (A4), showed moderate inhibition against 1,4-ß-galactosyltransferase. However, additional studies showed that the observed inhibitory effect was due to binding to bovine serum albumin, which was used in assays as a stabilizer.

Anti-influenza A virus activity of uridine derivatives of 2-deoxy sugars.

Influenza viruses are important pathogens that cause respiratory infections in humans and animals. Apart from vaccinations, antiviral drugs play a significant role in controlling spread of the disease. Influenza A virus contains two membrane glycoproteins on the external part of viral envelope: hemagglutinin (HA) and neuraminidase (NA), which are crucial for productive infection in target cells. In the present work, two derivatives of tunicamycin - uridine derivatives of 2-deoxy sugars (designated IW3 and IW7), which target the glycan processing steps during maturation of viral glycoproteins, were assayed for their ability to inhibit influenza A virus infection in vitro. Using the cytopathic effect (CPE) inhibition assay and viral plaque reduction assay we showed, that both IW3 and IW7 inhibitors exerted significant inhibitory effect on influenza A virus infection in MDCK cells without significant toxicity for the cells. Moreover, tested compounds selectively suppressed viral protein expression in a dose-dependent manner, suggesting that the mechanism of their antiviral activity may be similar to this shown previously for other viruses. We have also excluded the possibility that both inhibitors act at the replication step of virus life cycle. Using real-time PCR assay it was shown that IW3 and IW7 did not change the level of viral RNA in infected MDCK cells after a single round of infection. Therefore, inhibition of influenza A virus infection by uridine derivatives of 2-deoxy sugars, acting as glycosylation inhibitors, is a promising alternative approach for the development of new anti-influenza A therapy.

Synthesis and preliminary biological evaluations of 5'-substituted derivatives of uridine as glycosyltransferase inhibitors.

New derivatives of uridine which contain a b-ketoenol motif were synthesized, characterized and biologically tested. Synthesized compounds 1-4 showed no activity against bovine milk ß-1,4-galactosyltransferase I at concentrations up to 2.0 mM and were not active against Candida albicans and Aspergilus fumigatus up to the maximum tested concentration of 1,000 µg/mL.