Most orally administered drugs fail to reach the intracerebral regions because of the intestinal epithelial barrier (IEB) and the blood–brain barrier (BBB), which are located between the gut and the ...brain. Herein, an oral prodrug delivery system that can overcome both the IEB and the BBB noninvasively is developed for treating gliomas. The prodrug is prepared by conjugating an anticancer drug on β‐glucans using a disulfide‐containing linker. Following oral administration in glioma‐bearing mice, the as‐prepared prodrug can specifically target intestinal M cells, transpass the IEB, and be phagocytosed/hitchhiked by local macrophages (Mϕ). The Mϕ‐hitchhiked prodrug is transported to the circulatory system via the lymphatic system, crossing the BBB. The tumor‐overexpressed glutathione then cleaves the disulfide bond within the prodrug, releasing the active drug, improving its therapeutic efficacy. These findings reveal that the developed prodrug may serve as a gut‐to‐brain oral drug delivery platform for the well‐targeted treatment of gliomas.
Following oral administration, a prodrug transpasses the intestinal epithelial barrier via M cells, and then undergoes endocytosis by resident macrophages. The macrophage‐hitchhiked prodrug is transported to the circulatory system via the lymphatic system, crossing the blood–brain barrier, ultimately penetrating a brain tumor. The tumor‐overexpressed glutathione cleaves the disulfide bond within the prodrug, releasing the active drug, facilitating antitumor efficacy.
Targeted oral delivery of a drug via the intestinal lymphatic system (ILS) has the advantages of protecting against hepatic first‐pass metabolism of the drug and improving its pharmacokinetic ...performance. It is also a promising route for the oral delivery of vaccines and therapeutic agents to induce mucosal immune responses and treat lymphatic diseases, respectively. This article describes the anatomical structures and physiological characteristics of the ILS, with an emphasis on enterocytes and microfold (M) cells, which are the main gateways for the transport of particulate delivery vehicles across the intestinal epithelium into the lymphatics. A comprehensive overview of recent advances in the rational engineering of particulate vehicles, along with the challenges and opportunities that they present for improving ILS drug delivery, is provided, and the mechanisms by which such vehicles target and transport through enterocytes or M cells are discussed. The use of naturally sourced materials, such as yeast microcapsules and their derived polymeric β‐glucans, as novel ILS‐targeting delivery vehicles is also reviewed. Such use is the focus of an emerging field of research. Their potential use in the oral delivery of nucleic acids, such as mRNA vaccines, is proposed.
The rational engineering of effective vehicles for lymphatic delivery of drugs, through targeting enterocytes or M cells, prevents their first‐pass metabolism by the liver, markedly increasing the bioavailability of oral drugs. By achieving increased bioavailability, high drug concentrations are attainable at the lesions of interest with beneficial therapeutic effects, making intestinal lymphatic transport a unique modality of drug delivery.
Obesity is a potential risk factor for cognitive deficits in the elder humans. Using a high-fat diet (HFD)–induced obese mouse model, we investigated the impacts of HFD on obesity, metabolic and ...stress hormones, learning performance, and hippocampal synaptic plasticity. Both male and female C57BL/6J mice fed with HFD (3 weeks to 9–12 months) gained significantly more weights than the sex-specific control groups. Compared with the obese female mice, the obese males had similar energy intake but developed more weight gains. The obese male mice developed hyperglycemia, hyperinsulinemia, hypercholesterolemia, and hyperleptinemia, but not hypertriglyceridemia. The obese females had less hyperinsulinemia and hypercholesterolemia than the obese males, and no hyperglycemia and hypertriglyceridemia. In the contextual fear conditioning and step-down passive avoidance tasks, the obese male, but not female, mice showed poorer learning performance than their normal counterparts. These learning deficits were not due to sensorimotor impairment as verified by the open-field and hot-plate tests. Although, basal synaptic transmission characteristics (input–output transfer and paired-pulse facilitation (PPF) ratio) were not significantly different between normal and HFD groups, the magnitudes of synaptic plasticity (long-term potentiation (LTP) and long-term depression (LTD)) were lower at the Schaffer collateral-CA1 synapses of the hippocampal slices isolated from the obese male, but not female, mice, as compared with their sex-specific controls. Our results suggest that male mice are more vulnerable than the females to the impacts of HFD on weight gains, metabolic alterations and deficits of learning, and hippocampal synaptic plasticity.
The major challenge in COVID‐19 vaccine effectiveness is immune escape by SARS‐CoV‐2 variants. To overcome this, an Omicron‐specific messenger RNA (mRNA) vaccine was designed. The extracellular ...domain of the spike of the Omicron variant was fused with a modified GCN4 trimerization domain with low immunogenicity (TSomi). After immunization with TSomi mRNA in hamsters, animals were challenged with SARS‐CoV‐2 virus. The raised nonneutralizing antibodies or cytokine secretion responses can recognize both Wuhan S and Omicron S. However, the raised antibodies neutralized SARS‐CoV‐2 Omicron virus infection but failed to generate Wuhan virus neutralizing antibodies. Surprisingly, TSomi mRNA immunization protected animals from Wuhan virus challenge. These data indicated that non‐neutralizing antibodies or cellular immunity may play a more important role in vaccine‐induced protection than previously believed. Next‐generation COVID‐19 vaccines using the Omicron S antigen may provide sufficient protection against ancestral or current SARS‐CoV‐2 variants.
The oral absorption of a therapeutic peptide (such as exenatide; EXT) that can improve glycemic control in the treatment of type 2 diabetes is limited by multiple barriers of the intestinal ...epithelium. This work presents an oil‐structured nanoemulsion system that consists of a phase‐changeable fatty acid that allows EXT (EXT@PC/NEMs) to be delivered orally and absorbed efficiently in the small intestine. To construct an appropriate vehicle to encapsulate EXT, an oil‐in‐water single emulsion is generated at 37 °C, which is well above the melting point of the fatty acid but below the denaturation temperature of the peptide drug. The as‐prepared EXT@PC/NEMs are physically stable when stored at 4 °C, as they form a solid core, which prevents drug leakage. Upon their oral delivery at body temperature, the deformable liquid EXT@PC/NEMs may undergo effective cellular uptake, enhancing their permeability across the intestinal epithelium. The orally administered PC/NEMs significantly improve the bioavailability of EXT via intestinal lymphatic transport, ultimately accumulating in the pancreas, suggesting the possibility of orally delivering labile peptide drugs. The delivered EXT may act on pancreatic β‐ and α‐cells to stimulate insulin release and suppress glucagon secretion, respectively, reducing the blood glucose level, eventually having antidiabetic effects.
Phase‐changeable nanoemulsions are used to encapsulate a peptide drug during emulsification at 37 °C and are physically stable when stored at 4 °C. Upon oral ingestion at body temperature, the deformable liquid nanoemulsions undergo effective cellular uptake, enhancing their permeability across the intestinal epithelium, ultimately accumulating in the pancreas via lymphatic transport to exert their beneficial antidiabetic effects.
The ongoing COVID-19 pandemic has caused more than 193,825 deaths during the past few months. A quick-to-be-identified cure for the disease will be a therapeutic medicine that has prior use ...experiences in patients in order to resolve the current pandemic situation before it could become worsening. Artificial intelligence (AI) technology is hereby applied to identify the marketed drugs with potential for treating COVID-19.
An AI platform was established to identify potential old drugs with anti-coronavirus activities by using two different learning databases; one consisted of the compounds reported or proven active against SARS-CoV, SARS-CoV-2, human immunodeficiency virus, influenza virus, and the other one containing the known 3C-like protease inhibitors. All AI predicted drugs were then tested for activities against a feline coronavirus in in vitro cell-based assay. These assay results were feedbacks to the AI system for relearning and thus to generate a modified AI model to search for old drugs again.
After a few runs of AI learning and prediction processes, the AI system identified 80 marketed drugs with potential. Among them, 8 drugs (bedaquiline, brequinar, celecoxib, clofazimine, conivaptan, gemcitabine, tolcapone, and vismodegib) showed in vitro activities against the proliferation of a feline infectious peritonitis (FIP) virus in Fcwf-4 cells. In addition, 5 other drugs (boceprevir, chloroquine, homoharringtonine, tilorone, and salinomycin) were also found active during the exercises of AI approaches.
Having taken advantages of AI, we identified old drugs with activities against FIP coronavirus. Further studies are underway to demonstrate their activities against SARS-CoV-2 in vitro and in vivo at clinically achievable concentrations and doses. With prior use experiences in patients, these old drugs if proven active against SARS-CoV-2 can readily be applied for fighting COVID-19 pandemic.
A major obstacle to nanodrugs-mediated cancer therapy is their rapid uptake by the reticuloendothelial system that decreases the systemic exposure of the nanodrugs to tumors and also increases ...toxicities. Intralipid has been shown to reduce nano-oxaliplatin-mediated toxicity while improving bioavailability. Here, we have found that Intralipid reduces the cytotoxicity of paclitaxel for human monocytic cells, but not for breast, lung, or pancreatic cancer cells. Intralipid also promotes the polarization of macrophages to the anti-cancer M1-like phenotype. Using a xenograft breast cancer mouse model, we have found that Intralipid pre-treatment significantly increases the amount of paclitaxel reaching the tumor and promotes tumor apoptosis. The combination of Intralipid with half the standard clinical dose of Abraxane reduces the tumor growth rate as effectively as the standard clinical dose. Our findings suggest that pre-treatment of Intralipid has the potential to be a powerful agent to enhance the tumor cytotoxic effects of Abraxane and to reduce its off-target toxicities.
Machine learning is a well-known approach for virtual screening. Recently, deep learning, a machine learning algorithm in artificial neural networks, has been applied to the advancement of precision ...medicine and drug discovery. In this study, we performed comparative studies between deep neural networks (DNN) and other ligand-based virtual screening (LBVS) methods to demonstrate that DNN and random forest (RF) were superior in hit prediction efficiency. By using DNN, several triple-negative breast cancer (TNBC) inhibitors were identified as potent hits from a screening of an in-house database of 165,000 compounds. In broadening the application of this method, we harnessed the predictive properties of trained model in the discovery of G protein-coupled receptor (GPCR) agonist, by which computational structure-based design of molecules could be greatly hindered by lack of structural information. Notably, a potent (~ 500 nM) mu-opioid receptor (MOR) agonist was identified as a hit from a small-size training set of 63 compounds. Our results show that DNN could be an efficient module in hit prediction and provide experimental evidence that machine learning could identify potent hits in silico from a limited training set.
The oral route is considered to be the most convenient and comfortable means of drug administration for patients. Nevertheless, oral administration of hydrophilic macromolecules such as ...peptide/protein drugs is encountered with many difficulties. To overcome these difficulties, a pH‐sensitive nanoparticle (NP) carrier system, self‐assembled by chitosan (CS) and poly‐γ‐glutamic acid (γ‐PGA), is developed for paracellular transports of insulin. Oral administration of insulin‐loaded NPs shows a significant hypoglycemic action in diabetic rats and the corresponding relative bioavailability of insulin is approximately 15%. These findings suggest that the developed NP system is a promising carrier for improved transmucosal delivery of insulin in the small intestine. Besides insulin, this NP carrier system is expected to serve as a platform for oral delivery of hydrophilic macromolecules such as pharmaceutically active peptides/proteins, glycosaminoglycans, and oligonucleotides. Studies on the detailed mechanism of tight‐junction opening by CS or its derivatives are in progress, which is of paramount importance and needs to be established to aid further development in the use of NPs for oral delivery of hydrophilic macromolecules.
pH‐Sensitive nanoparticles composed of chitosan and poly‐γ‐glutamic acid are developed for the oral delivery of insulin. NPs infiltrate the mucus layer and disintegrate due to their pH sensitivity and release the loaded insulin near the surface of epithelial cells.
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