Keynote review: Intestinal Peyer's patch M cells and oral vaccine targeting

Understanding lymphatic drug delivery through chylomicron blockade: A retrospective and prospective analysis

Scientists have developed and employed various models to investigate intestinal lymphatic uptake. One approach involves using specific blocking agents to influence the chylomicron-mediated lymphatic absorption of drugs. Currently utilized models include pluronic L-81, puromycin, vinca alkaloids, colchicine, and cycloheximide. This review offers a thorough analysis of the diverse models utilized, evaluating existing reports while delineating the gaps in current research. It also explores pharmacokinetic related aspects of intestinal lymphatic uptake pathway and its blockage through the discussed models. Pluronic L-81 has a reversible effect, minimal toxicity, and unique mode of action. Yet, it lacks clinical reports on chylomicron pathway blockage, likely due to low concentrations used. Puromycin and vinca alkaloids, though documented for toxicity, lack information on their application in drug intestinal lymphatic uptake. Other vinca alkaloids show promise in affecting triglyceride profiles and represent possible agents to test as blockers. Colchicine and cycloheximide, widely used in pharmaceutical development, have demonstrated efficacy, with cycloheximide preferred for lower toxicity. However, further investigation into effective and toxic doses of colchicine in humans is needed to understand its clinical impact. The review additionally followed the complete journey of oral lymphatic targeting drugs from intake to excretion, provided a pharmacokinetic equation considering the intestinal lymphatic pathway for assessing bioavailability. Moreover, the possible application of urinary data as a non-invasive way to measure the uptake of drugs through intestinal lymphatics was illustrated, and the likelihood of drug interactions when specific blockers are employed in human subjects was underscored.

A novel pectin polysaccharide from vinegar-baked Radix Bupleuri absorbed by microfold cells in the form of nanoparticles

Polysaccharides of vinegar-baked Radix Bupleuri (VBCP) have been reported to exhibit liver-targeting and immunomodulatory activities through oral administration, but the absorption behavior and mechanism of VBCPs have not been extensively studied. In this study, a novel HG type pectin polysaccharide, VBCP1-4, with a high molecular weight of 2.94 × 106 Da, was separated from VBCP. VBCP1-4 backbone was contained 1,4-α-D-GalpA, 1,4-α-D-GalpA6OMe, 1,3,4-α-D-GalpA and 1,2,4-α-D-Rhap. The branches were mainly contained 1,5-α-L-Araf, 1,3,5-α-L-Araf, t-α-L-Araf and t-α-D-Galp, which linked to the 3 position of 1,3,4-α-D-GalpA and the 4 position of 1,2,4-α-D-Rhap. VBCP1-4 could self-assemble to nanoparticles in water, with CMC values of 106.41 μg/mL, particle sizes of 178.20 ± 2.82 nm and zeta potentials of -23.19 ± 1.44 mV. The pharmacokinetic study of VBCP1-4, which detected by marking with FITC, revealed that it could be partially absorbed into the body through Peyer's patches of the ileum. In vitro absorption study demonstrated that VBCP1-4 was difficult to be absorbed by Caco-2 cell monolayer, but could be absorbed by M cells in a time and concentration dependent manner. The absorption mechanism was elucidated that VBCP1-4 entered M cells through clathrin-mediated endocytosis in the form of nanoparticles. These findings provide valuable insights into the absorption behavior of VBCP and contribute to its further development.

Saccharomyces cerevisiae oral immunization in mice using multi-antigen of the African swine fever virus elicits a robust immune response

African swine fever virus (ASFV) is one of the most complex viruses. ASFV is a serious threat to the global swine industry because no commercial vaccines against this virus are currently available except in Vietnam. Moreover, ASFV is highly stable in the environment and can survive in water, feed, and aerosols for a long time. ASFV is transmitted through the digestive and respiratory tract. Mucosal immunity is the first line of defense against ASFV. Saccharomyces cerevisiae (SC), which has been certified by the U.S. Food and Drug Administration and has a generally recognized as safe status in the food industry, was used for oral immunization in this study. ASFV antigens were effectively expressed in recombinant SC strains with high DNA copy numbers and stable growth though surface display technology and chromosome engineering (δ-integration). The recombinant SC strains containing eight ASFV antigens-KP177R, E183L, E199L, CP204L, E248R, EP402R, B602L, and B646L- induced strong humoral and mucosal immune responses in mice. There was no antigenic competition, and these antigens induced Th1 and Th2 cellular immune responses. Therefore, the oral immunization strategy using recombinant SC strains containing multiple ASFV antigens demonstrate potential for future testing in swine, including challenge studies to evaluate its efficacy as a vaccine against ASFV.

Recent Progress in the Oral Delivery of Therapeutic Peptides and Proteins: Overview of Pharmaceutical Strategies to Overcome Absorption Hurdles

Purpose

Proteins and peptides have secured a place as excellent therapeutic moieties on account of their high selectivity and efficacy. However due to oral absorption limitations, current formulations are mostly delivered parenterally. Oral delivery of peptides and proteins (PPs) can be considered the need of the hour due to the immense benefits of this route. This review aims to critically examine and summarize the innovations and mechanisms involved in oral delivery of peptide and protein drugs.

Methods

Comprehensive literature search was undertaken, spanning the early development to the current state of the art, using online search tools (PubMed, Google Scholar, ScienceDirect and Scopus).

Results

Research in oral delivery of proteins and peptides has a rich history and the development of biologics has encouraged additional research effort in recent decades. Enzyme hydrolysis and inadequate permeation into intestinal mucosa are the major causes that result in limited oral absorption of biologics. Pharmaceutical and technological strategies including use of absorption enhancers, enzyme inhibition, chemical modification (PEGylation, pro-drug approach, peptidomimetics, glycosylation), particulate delivery (polymeric nanoparticles, liposomes, micelles, microspheres), site-specific delivery in the gastrointestinal tract (GIT), membrane transporters, novel approaches (self-nanoemulsifying drug delivery systems, Eligen technology, Peptelligence, self-assembling bubble carrier approach, luminal unfolding microneedle injector, microneedles) and lymphatic targeting, are discussed. Limitations of these strategies and possible innovations for improving oral bioavailability of protein and peptide drugs are discussed.

Conclusion

This review underlines the application of oral route for peptide and protein delivery, which can direct the formulation scientist for better exploitation of this route.

Utility of human induced pluripotent stem cell-derived small intestinal epithelial cells for pharmacokinetic, toxicological, and immunological studies

The small intestine, which plays a crucial role in the absorption and metabolism of drugs and foods, serves as a target organ for drug-induced toxicity and immune interactions with functional foods and intestinal bacteria. Current alternative models of the human small intestine, such as Caco-2 cells and experimental animals, have limitations due to variations in the expression levels of metabolic enzymes, transporters, and receptors. This study presents investigations into the utility of human induced pluripotent stem cell-derived small intestinal epithelial cells (hiSIECs) for pharmacokinetic, toxicological, and immunological studies, respectively. While hiSIECs displayed small intestinal epithelial cell characteristics and barrier function, they demonstrated pharmacokinetic properties such as cytochrome P450 3A4/5 activity equivalent to human primary enterocytes and stable P-glycoprotein activity. These cells also demonstrated potential for assessing two forms of intestinal toxicity caused by anticancer drugs and gamma-secretase inhibitors, displaying immune responses mediated by toll-like and fatty acid receptors while serving as an inflammatory gut model through the addition of tumor necrosis factor alpha and interferon gamma. Overall, hiSIECs hold promise as an in vitro model for assessing pharmacokinetics, toxicity, and effects on the intestinal immunity of pharmaceuticals, functional foods, supplements, and intestinal bacteria.

Cracking the intestinal lymphatic system window utilizing oral delivery vehicles for precise therapy

Oral administration is preferred over other drug delivery methods due to its safety, high patient compliance, ease of ingestion without discomfort, and tolerance of a wide range of medications. However, oral drug delivery is limited by the poor oral bioavailability of many drugs, caused by extreme conditions and absorption challenges in the gastrointestinal tract. This review thoroughly discusses the targeted drug vehicles to the intestinal lymphatic system (ILS). It explores the structure and physiological barriers of the ILS, highlighting its significance in dietary lipid and medication absorption and transport. The review presents various approaches to targeting the ILS using spatially precise vehicles, aiming to enhance bioavailability, achieve targeted delivery, and reduce first-pass metabolism with serve in clinic. Furthermore, the review outlines several methods for leveraging these vehicles to open the ILS window, paving the way for potential clinical applications in cancer treatment and oral vaccine delivery. By focusing on targeted drug vehicles to the ILS, this article emphasizes the critical role of these strategies in improving therapeutic efficacy and patient outcomes. Overall, this article emphasizes the critical role of targeted drug vehicles to the ILS and the potential impact of these strategies on improving therapeutic efficacy and patient outcomes.

Nanoparticle oral absorption and its clinical translational potential

Oral administration of pharmaceuticals is the most preferred route of administration for patients, but it is challenging to effectively deliver active ingredients (APIs) that i) have extremely high or low solubility in intestinal fluids, ii) are large in size, iii) are subject to digestive and/or metabolic enzymes present in the gastrointestinal tract (GIT), brush border, and liver, and iv) are P-glycoprotein substrates. Over the past decades, efforts to increase the oral bioavailability of APIs have led to the development of nanoparticles (NPs) with non-specific uptake pathways (M cells, mucosal, and tight junctions) and target-specific uptake pathways (FcRn, vitamin B12, and bile acids). However, voluminous findings from preclinical models of different species rarely meet practical standards when translated to humans, and API concentrations in NPs are not within the adequate therapeutic window. Various NP oral delivery approaches studied so far show varying bioavailability impacted by a range of factors, such as species, GIT physiology, age, and disease state. This may cause difficulty in obtaining similar oral delivery efficacy when research results in animal models are translated into humans. This review describes the selection of parameters to be considered for translational potential when designing and developing oral NPs.

An updated review on oral protein-based antigen vaccines efficiency and delivery approaches: a special attention to infectious diseases

Various infectious agents affect human health via the oral entrance. The majority of pathogens lack approved vaccines. Oral vaccination is a convenient, safe and cost-effective approach with the potential of provoking mucosal and systemic immunity and maintaining individual satisfaction. However, vaccines should overcome the intricate environment of the gastrointestinal tract (GIT). Oral protein-based antigen vaccines (OPAVs) are easier to administer than injectable vaccines and do not require trained healthcare professionals. Additionally, the risk of needle-related injuries, pain, and discomfort is eliminated. However, OPAVs stability at environmental and GIT conditions should be considered to enhance their stability and facilitate their transport and storage. These vaccines elicit the local immunity, protecting GIT, genital tract and respiratory epithelial surfaces, where numerous pathogens penetrate the body. OPAVs can also be manipulated (such as using specific incorporated ligand and receptors) to elicit targeted immune response. However, low bioavailability of OPAVs necessitates development of proper protein carriers and formulations to enhance their stability and efficacy. There are several strategies to improve their efficacy or protective effects, such as incorporation of adjuvants, enzyme inhibitors, mucoadhesive or penetrating devices and permeation enhancers. Hence, efficient delivery of OPAVs into GIT require proper delivery systems mainly including smart target systems, probiotics, muco-adhesive carriers, lipid- and plant-based delivery systems and nano- and microparticles.

The emerging roles of long noncoding RNAs in lymphatic vascular development and disease

Recent advances in RNA sequencing technologies helped uncover what was once uncharted territory in the human genome-the complex and versatile world of long noncoding RNAs (lncRNAs). Previously thought of as merely transcriptional "noise", lncRNAs have now emerged as essential regulators of gene expression networks controlling development, homeostasis and disease progression. The regulatory functions of lncRNAs are broad and diverse, and the underlying molecular mechanisms are highly variable, acting at the transcriptional, post-transcriptional, translational, and post-translational levels. In recent years, evidence has accumulated to support the important role of lncRNAs in the development and functioning of the lymphatic vasculature and associated pathological processes such as tumor-induced lymphangiogenesis and cancer metastasis. In this review, we summarize the current knowledge on the role of lncRNAs in regulating the key genes and pathways involved in lymphatic vascular development and disease. Furthermore, we discuss the potential of lncRNAs as novel therapeutic targets and outline possible strategies for the development of lncRNA-based therapeutics to treat diseases of the lymphatic system.

Challenges and opportunities in delivering oral peptides and proteins

INTRODUCTION

Rapid advances in bioengineering enable the use of complex proteins as therapeutic agents to treat diseases. Compared with conventional small molecule drugs, proteins have multiple advantages, including high bioactivity and specificity with low toxicity. Developing oral dosage forms with active proteins is a route to improve patient compliance and significantly reduce production costs. However, the gastrointestinal environment remains a challenge to this delivery path due to enzymatic degradation, low permeability, and weak absorption, leading to reduced delivery efficiency and poor clinical outcomes.

AREAS COVERED

This review describes the barriers to oral delivery of peptides and complex proteins, current oral delivery strategies utilized and the opportunities and challenges ahead to try and circumvent these barriers. Oral protein drugs on the market and clinical trials provide insights and approaches for advancing delivery strategies.

EXPERT OPINION

Although most current studies on oral protein delivery rely on in vitro and in vivo animal data, the safety and limitations of the approach in humans remain uncertain. The shortage of clinical data limits the development of new or alternative strategies. Therefore, designing appropriate oral delivery strategies remains a significant challenge and requires new ideas, innovative design strategies and novel model systems.

The inhibitory effect of oral administration of lentinan on DSS-induced inflammation is exerted by the migration of T cells activated in the ileum to the colon

Oral administration of lentinan ameliorated dextran sulfate sodium (DSS)-induced colitis through Dectin-1 receptor on intestinal epithelial cells. However, it is unclear where lentinan affects in the intestine to prevent the inflammation. We found that the administration of lentinan has induced migration of CD4+ cells from the ileum to the colon by using Kikume Green-Red (KikGR) mice in this study. This result suggests that the oral lentinan treatment could accelerate the migration of Th cells in lymphocyte from ileum into the colon during lentinan intake. Then, C57BL/6 mice were administered 2% DSS to induce colitis. The mice were administered lentinan daily via oral or rectal route before DSS administration. Its rectal administration also suppressed DSS-induced colitis, but its suppressive effects were lower compared to when orally administered, indicating that the biological responses to lentinan in the small intestine contributed to the anti-inflammatory effects. In normal mice (without DSS treatment), the expression of Il12b was significantly increased in the ileum by the oral administration of lentinan, but not by rectal one. On the other hand, no change was observed in the colon by either administration method. In addition, Tbx21 was significantly increased in the ileum. These suggested that IL-12 was increased in the ileum and Th1 cells differentiated in dependence on it. Therefore, Th1 predominant condition in the ileum could influence immunity in the colon and improve the colitis.

Oral lymphatic delivery of alpha-galactosylceramide and ovalbumin evokes anti-cancer immunization

We developed an orally delivered nanoemulsion that induces cancer immunization. It consists of tumor antigen-loaded nano-vesicles carrying the potent invariant natural killer T-cell (iNKT) activator α-galactosylceramide (α-GalCer), to trigger cancer immunity by effectively activating both innate and adaptive immunity. It was validated that adding bile salts to the system boosted intestinal lymphatic transport as well as the oral bioavailability of ovalbumin (OVA) via the chylomicron pathway. To increase intestinal permeability further and amplify the antitumor responses, an ionic complex of cationic lipid 1,2-dioleyl-3-trimethylammonium propane (DTP) with sodium deoxycholate (DA) (DDP) and α-GalCer were anchored onto the outer oil layer to form OVA-NE#3. As expected, OVA-NE#3 exhibited tremendously improved intestinal cell permeability as well as enhanced delivery to mesenteric lymph nodes (MLNs). Subsequent activation of dendritic cells and iNKTs, in MLNs were also observed. Tumor growth in OVA-expressing mice with melanoma was more strongly suppressed (by 71%) after oral administration of OVA-NE#3 than in untreated controls, confirming the strong immune response induced by the system. The serum levels of OVA-specific IgG1 and IgG2a were 3.52- and 6.14-fold higher than in controls. Treating OVA-NE#3 increased the numbers of tumor-infiltrating lymphocytes, including cytotoxic T-cell and M1-like macrophage. Antigen- and α-GalCer-associated enrichment of dendritic cells and iNKTs in tumor tissues also increased after OVA-NE#3 treatment. These observations indicate that our system induces both cellular and humoral immunity by targeting the oral lymphatic system. It may offer a promising oral anti-cancer vaccination strategy that involves the induction of systemic anti-cancer immunization.

Phosphatidylserine-mediated oral tolerance

Phosphatidylserine (PS) is an anionic phospholipid exposed on the surface of apoptotic cells. The exposure of PS typically recruits and signals phagocytes to engulf and silently clear these dying cells to maintain tolerance via immunological ignorance. However, recent and emerging evidence has demonstrated that PS converts an "immunogen" into a "tolerogen", and PS exposure on the surface of cells or vesicles actively promotes a tolerogenic environment. This tolerogenic property depends on the biophysical characteristics of PS-containing vesicles, including PS density on the particle surface to effectively engage tolerogenic receptors, such as TIM-4, which is exclusively expressed on the surface of antigen-presenting cells. We harnessed the cellular and molecular mechanistic insight of PS-mediated immune regulation to design an effective oral tolerance approach. This immunotherapy has been shown to prevent/reduce immune response against life-saving protein-based therapies, food allergens, autoantigens, and the antigenic viral capsid peptide commonly used in gene therapy, suggesting a broad spectrum of potential clinical applications. Given the good safety profile of PS together with the ease of administration, oral tolerance achieved with PS-based nanoparticles has a very promising therapeutic impact.

Blood glucose levels and the risk of HPV multiple infections in high-grade squamous intraepithelial lesions: A retrospective cross-sectional study of Chinese patients

Besides the controversy of the association of high glycemic index and glycemic load with precancerous cervical lesions, only a few studies have examined the impact of fasting blood glucose levels on human papillomavirus (HPV) multiple infections. In the present study, we appraised the relationship between blood glucose levels and multiple HPV infections in a population of HPV-positive women with cervical high-grade squamous intraepithelial lesions (HSIL). The present study was designed as a cross-sectional correlative analysis. A total of 560 participants with a pathologically confirmed HSIL with HPV infection were included from a hospital in China during January 1, 2018, and December 31, 2019. The target variables and the outcome variables were the glucose levels at the baseline and HPV multiplicity, respectively. The odds ratio and 95% confidence intervals were calculated to estimate the risk of multiple infections via logistic regression analysis. The average age of the 560 participants was 44.63 ± 10.61 years; the nonlinear relationship was detected between the glucose levels and multiplicity of HPV, with an inflection point at 5.4. After adjusting for the full range of variables, the effect sizes and confidence intervals for the left and right sides of the inflection points were found to be 0.379 (0.196-0.732) and 5.083 (1.592-16.229), respectively. In this cross-sectional study, both high and low blood glucose levels increased the risk of multiple HPV infections, demonstrating a U-shaped relationship between the blood glucose levels and multiple HPV infections.

Human dendritic cell targeting peptide can be targeted to porcine dendritic cells to improve antigen capture efficiency to stimulate stronger immune response

Dendritic cells (DCs) play a key role in the natural recognition of pathogens and subsequent activation of adaptive immune responses due to their potent antigen-presenting ability. Dendritic cell-targeting peptide (DCpep) is strongly targeted to DCs, which often express antigens, to enhance the efficacy of vaccines. Our previous study showed that recombinant Lactobacillus expressing human DCpep could significantly induce stronger immune responses than recombinant Lactobacillus without DCpep, but the mechanism remains unclear. In this study, the mechanism by which DCpep enhances the immune response against recombinant Lactobacillus was explored. Fluorescence-labeled human DCpep was synthesized to evaluate the binding ability of human DCpep to porcine monocyte-derived dendritic cells (Mo-DCs) and DCs of the small intestine. The effects of Mo-DC function induced by recombinant Lactobacillus expressing human DCpep fused with the porcine epidemic diarrhea virus (PEDV) core neutralizing epitope (COE) antigen were also investigated. The results showed that human DCpep bind to porcine DCs, but not to porcine small intestinal epithelial cells. Human DCpep can also improve the capture efficiency of recombinant Lactobacillus by Mo-DCs, promote the maturation of dendritic cells, secrete more cytokines, and enhance the ability of porcine DCs to activate T-cell proliferation. Taken together, these results promote advanced understanding of the mechanism by which DCpep enhances immune responses. We found that some DCpeps are conserved between humans and pigs, which provides a theoretical basis for the development of a DC-targeted vaccine.

Effects of Habitat River Microbiome on the Symbiotic Microbiota and Multi-Organ Gene Expression of Captive-Bred Chinese Giant Salamander

The reintroduction of captive-bred individuals is a primary approach to rebuild the wild populations of the Chinese giant salamander (Andrias davidianus), the largest extant amphibian species. However, the complexity of the wild habitat (e.g., diverse microorganisms and potential pathogens) potentially threatens the survival of reintroduced individuals. In this study, fresh (i.e., containing environmental microbiota) or sterilized river sediments (120°C sterilized treatment) were added to the artificial habitats to treat the larvae of the Chinese giant salamander (control group—Cnt: 20 individuals, treatment group 1 with fresh river sediments—T1: 20 individuals, and treatment group 2 with sterilized river sediments—T2: 20 individuals). The main objective of this study was to test whether this procedure could provoke their wild adaptability from the perspective of commensal microbiotas (skin, oral cavity, stomach, and gut) and larvae transcriptomes (skin, spleen, liver, and brain). Our results indicated that the presence of habitat sediments (whether fresh or sterilized) reshaped the oral bacterial community composition. Specifically, Firmicutes decreased dramatically from ~70% to ~20–25% (mainly contributed by Lactobacillaceae), while Proteobacteria increased from ~6% to ~31–36% (mainly contributed by Gammaproteobacteria). Consequently, the proportion of antifungal operational taxonomic units (OTUs) increased, and the function of oral microbiota likely shifted from growth-promoting to pathogen defense. Interestingly, the skin microbiota, rather than the colonization of habitat microbiota, was the major source of the pre-treated oral microbiota. From the host perspective, the transcriptomes of all four organs were changed for treated individuals. Specifically, the proteolysis and apoptosis in the skin were promoted, and the transcription of immune genes was activated in the skin, spleen, and liver. Importantly, more robust immune activation was detected in individuals treated with sterilized sediments. These results suggested that the pathogen defense of captive-bred individuals was improved after being treated, which may benefit their survival in the wild. Taken together, our results suggested that the pre-exposure of captive-bred Chinese giant salamander individuals to habitat sediments could be considered and added into the reintroduction processes to help them better adapt to wild conditions.

Advances and Applications of Metal-Organic Framework Nanomaterials as Oral Delivery Carriers: A Review

Oral administration is a commonly used, safe, and patient-compliant method of drug delivery. However, due to the multiple absorption barriers in the gastrointestinal tract (GIT), the oral bioavailability of many drugs is low, resulting in a limited range of applications for oral drug delivery. Nanodrug delivery systems have unique advantages in overcoming the multiple barriers to oral absorption and improving the oral bioavailability of encapsulated drugs. Metal-organic frameworks (MOFs) are composed of metal ions and organic linkers assembled by coordination chemistry. Unlike other nanomaterials, nanoscale metal-organic frameworks (nano-MOFs, NMOFs) are increasingly popular for drug delivery systems (DDSs) due to their tunable pore size and easily modified surfaces. This paper summarizes the literature on MOFs in pharmaceutics included in SCI for the past ten years. Then, the GIT structure and oral drug delivery systems are reviewed, and the advantages, challenges, and solution strategies possessed by oral drug delivery systems are discussed. Importantly, two major classes of MOFs suitable for oral drug delivery systems are summarized, and various representative MOFs as oral drug carriers are evaluated in the context of oral drug delivery systems. Finally, the challenges faced by DDSs in the development of MOFs, such as biostability, biosafety, and toxicity, are examined.

Artemisia argyi extract alleviates inflammation in a DSS-induced colitis mouse model and enhances immunomodulatory effects in lymphoid tissues

Background

The incidence of inflammatory bowel disease (IBD), an inflammatory disorder of the gastrointestinal system has increased. IBD, characterized by aberrant immune responses against antigens, is thought to be caused by the invasion of enterobacteria. The pathogenesis of IBD is complicated, hence novel effective therapeutic agents are warranted. Therefore, this study evaluates the potential of Artemisia argyi, a medicinal herb, in alleviating IBD.

Methods

The effectiveness of the A. argyi ethanol extract was verified both in vitro and in vivo. Inflammation was induced in RAW 264.7 cells by 1 μg/mL of lipopolysaccharide (LPS) and by 3% dextran sodium sulfate (DSS) in a DSS-induced colitis mouse model. During the ten-day colitis induction, 200 mg/kg of A. argyi ethanol extract was orally administered to the treatment group. Levels of inflammation-related proteins and genes were analyzed in the colon, serum, and lymphoid tissues, i.e., Peyer’s patches (PPs) and spleen. The chemical constituent of the A. argyi ethanol extract was identified using an ultra-high performance liquid chromatography mass spectrometry (UPLC-MS/MS) analysis.

Results

A. argyi ethanol extract treatment ameliorated IBD symptoms and reduced the expression of inflammation-related proteins and genes in the colon and serum samples. Furthermore, A. argyi treatment induced the activation of anti-oxidative associated proteins, such as nuclear factor-erythroid factor 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1); and the treatment have also inhibited nuclear factor-κB (NF-κB), a central mediator of inflammatory responses. A. argyi enhanced the immunomodulatory effects in the PPs and spleen, which may stem from interleukin-10 (IL-10) upregulation. Chemical analysis identified a total of 28 chemical compounds, several of which have been reported to exert anti-inflammatory effects.

Conclusions

The effectiveness of the A. argyi ethanol extract in alleviating IBD was demonstrated; application of the extract successfully mitigated IBD symptoms, and enhanced immunomodulatory responses in lymphoid tissues. These findings suggest A. argyi as a promising herbal medicine for IBD treatment.

Adhesion of enteropathogenic, enterotoxigenic and commensal Escherichia coli to the Major Zymogen Granule Membrane Glycoprotein 2

Pathogenic bacteria, such as enteropathogenic Escherichia coli (EPEC) and enterotoxigenic E. coli (ETEC), cause diarrhea in mammals. In particular, E. coli colonizes and infects the gastrointestinal tract via type 1 fimbriae (T1F). Here, the major zymogen granule membrane glycoprotein 2 (GP2) acts as a host cell receptor. GP2 is also secreted by the pancreas and various mucous glands, interacting with luminal type 1 fimbriae-positive E. coli. It is unknown whether GP2 isoforms demonstrate specific E. coli pathotype binding. In this study, we investigated interactions of human, porcine, and bovine EPEC and ETEC, as well as commensal E. coli isolates with human, porcine, and bovine GP2. We first defined pathotype- and host-associated FimH variants. Second, we could prove that GP2 isoforms bound to FimH variants to various degrees. However, the GP2-FimH interactions did not seem to be influenced by the host specificity of E. coli. In contrast, soluble GP2 affected ETEC infection and phagocytosis rates of macrophages. Preincubation of the ETEC pathotype with GP2 reduced the infection of cell lines. Furthermore, preincubation of E. coli with GP2 improved the phagocytosis rate of macrophages. Our findings suggest that GP2 plays a role in the defense against E. coli infection and in the corresponding host immune response.

IMPORTANCE Infection by pathogenic bacteria, such as certain Escherichia coli pathotypes, results in diarrhea in mammals. Pathogens, including zoonotic agents, can infect different hosts or show host specificity. There are Escherichia coli strains which are frequently transmitted between humans and animals, whereas other Escherichia coli strains tend to colonize only one host. This host specificity is still not fully understood. We show that glycoprotein 2 is a selective receptor for particular Escherichia coli strains or variants of the adhesin FimH but not a selector for a species-specific Escherichia coli group. We demonstrate that GP2 is involved in the regulation of colonization and infection and thus represents a molecule of interest for the prevention or treatment of disease.

Oral nanomedicine for modulating immunity, intestinal barrier functions, and gut microbiome

The gastrointestinal tract (GIT) affects not only local diseases in the GIT but also various systemic diseases. Factors that can affect the health and disease of both GIT and the human body include 1) the mucosal immune system composed of the gut-associated lymphoid tissues and the lamina propria, 2) the intestinal barrier composed of mucus and intestinal epithelium, and 3) the gut microbiota. Selective delivery of drugs, including antigens, immune-modulators, intestinal barrier enhancers, and gut-microbiome manipulators, has shown promising results for oral vaccines, immune tolerance, treatment of inflammatory bowel diseases, and other systemic diseases, including cancer. However, physicochemical and biological barriers of the GIT present significant challenges for successful translation. With the advances of novel nanomaterials, oral nanomedicine has emerged as an attractive option to not only overcome these barriers but also to selectively deliver drugs to the target sites in GIT. In this review, we discuss the GIT factors and physicochemical and biological barriers in the GIT. Furthermore, we present the recent progress of oral nanomedicine for oral vaccines, immune tolerance, and anti-inflammation therapies. We also discuss recent advances in oral nanomedicine designed to fortify the intestinal barrier functions and modulate the gut microbiota and microbial metabolites. Finally, we opine about the future directions of oral nano-immunotherapy.

Engineering Nano- and Microparticles as Oral Delivery Vehicles to Promote Intestinal Lymphatic Drug Transport

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.

Spatial gene expression maps of the intestinal lymphoid follicle and associated epithelium identify zonated expression programs

The intestine is lined with isolated lymphoid follicles (ILFs) that facilitate sampling of luminal antigens to elicit immune responses. Technical challenges related to the scarcity and small sizes of ILFs and their follicle-associated epithelium (FAE) impeded the characterization of their spatial gene expression programs. Here, we combined RNA sequencing of laser capture microdissected tissues with single-molecule transcript imaging to obtain a spatial gene expression map of the ILF and its associated FAE in the mouse small intestine. We identified zonated expression programs in both follicles and FAEs, with a decrease in enterocyte antimicrobial and absorption programs and a partial induction of expression programs normally observed at the villus tip. We further identified Lepr+ subepithelial telocytes at the FAE top, which are distinct from villus tip Lgr5+ telocytes. Our analysis exposes the epithelial and mesenchymal cell states associated with ILFs.

Dual-Antigen COVID-19 Vaccine Subcutaneous Prime Delivery With Oral Boosts Protects NHP Against SARS-CoV-2 Challenge

We have developed a dual-antigen COVID-19 vaccine incorporating genes for a modified SARS-CoV-2 spike protein (S-Fusion) and the viral nucleocapsid (N) protein with an Enhanced T-cell Stimulation Domain (N-ETSD) to increase the potential for MHC class II responses. The vaccine antigens are delivered by a human adenovirus serotype 5 platform, hAd5 [E1-, E2b-, E3-], previously demonstrated to be effective in the presence of Ad immunity. Vaccination of rhesus macaques with the hAd5 S-Fusion + N-ETSD vaccine by subcutaneous prime injection followed by two oral boosts elicited neutralizing anti-S IgG and T helper cell 1-biased T-cell responses to both S and N that protected the upper and lower respiratory tracts from high titer (1 x 106 TCID50) SARS-CoV-2 challenge. Notably, viral replication was inhibited within 24 hours of challenge in both lung and nasal passages, becoming undetectable within 7 days post-challenge.

Metabolic regulation mechanism of fucoidan via intestinal microecology in diseases

The intestinal microecology is an extremely complex ecosystem consisting of gut microbiota, intestinal mucosa and the intestinal immune system. The intestinal microecology performs several important functions and is considered to be an essential 'organ' because it plays an important role in regulating human metabolism. Fucoidan contains a large amount of fucose and galactose residues, as well as various other neutral and acidic monosaccharides. Fucoidan particularly effects tumors, inflammatory bowel disease, diabetes and obesity by repairing intestinal mucosal damage and improving the intestinal microecological environment. It has been proposed that fucoidan could be used as a prebiotic agent for pharmaceutical and functional foods. In this review, we elucidate the potential mechanisms of the metabolic regulation of fucoidan with respect to the intestinal microecology of diseases. © 2021 Society of Chemical Industry.

Oral delivery of proteins and peptides: Challenges, status quo and future perspectives

Proteins and peptides (PPs) have gradually become more attractive therapeutic molecules than small molecular drugs due to their high selectivity and efficacy, but fewer side effects. Owing to the poor stability and limited permeability through gastrointestinal (GI) tract and epithelia, the therapeutic PPs are usually administered by parenteral route. Given the big demand for oral administration in clinical use, a variety of researches focused on developing new technologies to overcome GI barriers of PPs, such as enteric coating, enzyme inhibitors, permeation enhancers, nanoparticles, as well as intestinal microdevices. Some new technologies have been developed under clinical trials and even on the market. This review summarizes the history, the physiological barriers and the overcoming approaches, current clinical and preclinical technologies, and future prospects of oral delivery of PPs.

An update on oral drug delivery via intestinal lymphatic transport

Orally administered drug entities have to survive the harsh gastrointestinal environment, penetrate the enteric epithelia and circumvent hepatic metabolism before reaching the systemic circulation. Whereas the gastrointestinal stability can be well maintained by taking proper measures, hepatic metabolism presents as a formidable barrier to drugs suffering from first-pass metabolism. The pharmaceutical academia and industries are seeking alternative pathways for drug transport to circumvent problems associated with the portal pathway. Intestinal lymphatic transport is emerging as a promising pathway to this end. In this review, we intend to provide an updated overview on the rationale, strategies, factors and applications involved in intestinal lymphatic transport. There are mainly two pathways for peroral lymphatic transport-the chylomicron and the microfold cell pathways. The underlying mechanisms are being unraveled gradually and nowadays witness increasing research input and applications.

Self-assembled aggregations in Coptidis Rhizoma decoction dynamically regulate intestinal tissue permeability through Peyer's patch-associated immunity

Objective

To investigate the dynamic regulation of self-assembled aggregations (SAA) in Coptidis Rhizoma decoction on the permeability of intestinal tissue and the mechanism underlying.

Methods

The effects of SAA on berberine (Ber) absorption were respectively analyzed in an in situ intestinal perfusion model and in an Ussing Chamber jejunum model with or without Peyer's patches (PPs). The expression levels of ZO-1, Occludin and Claudin-1 were detected by immunofluorescence to evaluate the tight junction (TJ) between intestinal epithelium cells. The expression levels of T-box-containing protein expressed in T cells, signal transducers and activators of tranion-6, retinoic acid receptor-related orphan receptor γt and forkhead box P3 in PPs were detected by the reverse transcription-polymerase chain reaction and the secretions of interferon-γ (IFN-γ), interleukin-4 (IL-4), interleukin-17 (IL-17) and transforming growth factor-β (TGF-β) in PPs were evaluated by immunohistochemistry, to reflect the differentiation of T lymphocyte in PPs to helper T (Th) cell 1, Th2, Th17 and regulatory T (Treg) cell. To confirm the correlation between SAA in Coptidis Rhizoma decoction, PPs-associated immunity and intestinal epithelium permeability, SAA were administrated on an Ussing Chamber jejunum model with immunosuppressed PPs and evaluated its influences on intestinal tissue permeability and TJ proteins expression.

Results

SAA in Coptidis Rhizoma decoction could dose-dependently promote Ber absorption in jejunum segment, with the participation of PPs. The dose-dependent and dynamical regulations of SAA on permeability of intestinal tissue and TJ proteins expression level between intestinal epithelium cells occurred along with the dynamically changed T lymphocyte differentiation and immune effectors secretion in PPs. The administration of SAA on immunosuppressed PPs exhibited dose-dependent PPs activation, inducing dynamic promotion on intestinal tissue permeability and inhibition on TJ proteins expression.

Conclusion

SAA can improve the Ber absorption in small intestine, through the PPs-associated immunity induced dynamic regulation on intestinal tissue permeability and TJ proteins expression. These findings might enlighten the research of traditional Chinese medicine decoction.

Recent advances in nano/microparticle-based oral vaccines

Background

Vaccines are often recognized as one of the most cost-effective public health interventions in controlling infectious diseases. Most pathogens infiltrate the body from mucosal sites, primarily from the oral and pulmonary region and reach the systemic circulation where disease manifestation starts. Traditional needle-based vaccines are usually not capable of inducing immunity at the mucosal sites where pathogen infiltrates start, but induces systemic immunity. In contrast to needle-based vaccines, mucosally administered vaccines induce immunity at both the mucosal sites and systemically. The oral route of immunization is the most convenient way to administer the vaccines. However, due to the complicated and hostile gastrointestinal structure and environment, vaccines need to overcome major hurdles while retaining their stability and immunogenicity.

Area covered

This review will briefly discuss different barriers to oral vaccine development. It gives a brief overview of different types of nano/microparticle-based oral vaccines and discusses how physicochemical characteristics of the particles influence overall immunity after oral immunization.

Expert opinion

Formulation strategies using novel lipid and polymer-based nano/microparticle platforms retain stability and antigenicity of vaccines against the harsh gastrointestinal condition. The physicochemical properties of particles can be uniquely tailored to prolong the release of antigens, and attached ligands (M-cells and APC-ligands) can precisely target uptake by immune cells. These represent viable strategies for efficient delivery of oral vaccines.

Nano and Microparticles as Potential Oral Vaccine Carriers and Adjuvants Against Infectious Diseases

Mucosal surfaces are the first site of infection for most infectious diseases and oral vaccination can provide protection as the first line of defense. Unlike systemic administration, oral immunization can stimulate cellular and humoral immune responses at both systemic and mucosal levels to induce broad-spectrum and long-lasting immunity. Therefore, to design a successful vaccine, it is essential to stimulate the mucosal as well as systemic immune responses. Successful oral vaccines need to overcome the harsh gastrointestinal environment such as the extremely low pH, proteolytic enzymes, bile salts as well as low permeability and the low immunogenicity of vaccines. In recent years, several delivery systems and adjuvants have been developed for improving oral vaccine delivery and immunogenicity. Formulation of vaccines with nanoparticles and microparticles have been shown to improve antigen stability, availability and adjuvanticity as well as immunostimulatory capacity, target delivery and specific release. This review discusses how nanoparticles (NPs) and microparticles (MPs) as oral carriers with adjuvant characteristics can be beneficial in oral vaccine development.

Gastrointestinal lipolysis and trans-epithelial transport of SMEDDS via oral route

Self-microemulsifying drug delivery systems (SMEDDSs) have recently returned to the limelight of academia and industry due to their enormous potential in oral delivery of biomacromolecules. However, information on gastrointestinal lipolysis and trans-epithelial transport of SMEDDS is rare. Aggregation-caused quenching (ACQ) fluorescent probes are utilized to visualize the in vivo behaviors of SMEDDSs, because the released probes during lipolysis are quenched upon contacting water. Two SMEDDSs composed of medium chain triglyceride and different ratios of Tween-80 and PEG-400 are set as models, meanwhile Neoral® was used as a control. The SMEDDS droplets reside in the digestive tract for as long as 24 h and obey first order kinetic law of lipolysis. The increased chain length of the triglyceride decreases the lipolysis of the SMEDDSs. Ex vivo imaging of main tissues and histological examination confirm the trans-epithelial transportation of the SMEDDS droplets. Approximately 2%-4% of the given SMEDDSs are transported via the lymph route following epithelial uptake, while liver is the main termination. Caco-2 cell lines confirm the cellular uptake and trans-epithelial transport. In conclusion, a fraction of SMEDDSs can survive the lipolysis in the gastrointestinal tract, permeate across the epithelia, translocate via the lymph, and accumulate mainly in the liver.

Advances in Oral Drug Delivery

The oral route is the most common route for drug administration. It is the most preferred route, due to its advantages, such as non-invasiveness, patient compliance and convenience of drug administration. Various factors govern oral drug absorption including drug solubility, mucosal permeability, and stability in the gastrointestinal tract environment. Attempts to overcome these factors have focused on understanding the physicochemical, biochemical, metabolic and biological barriers which limit the overall drug bioavailability. Different pharmaceutical technologies and drug delivery systems including nanocarriers, micelles, cyclodextrins and lipid-based carriers have been explored to enhance oral drug absorption. To this end, this review will discuss the physiological, and pharmaceutical barriers influencing drug bioavailability for the oral route of administration, as well as the conventional and novel drug delivery strategies. The challenges and development aspects of pediatric formulations will also be addressed.

An ex vivo investigation of the intestinal uptake and translocation of nanoparticles targeted to Peyer's patches microfold cells

Diverse nanoparticulate systems have been engineered as vehicles towards enhancing the bioavailability of orally administrated vaccines. Substantial evidence suggests that targeting microfold cells (M cells) within Peyer's patches (PPs) is a prerequisite for vaccine-loaded nanocarriers to induce an effective antigen-specific immune response. Improved understanding of the contribution of M cells to sampling luminal nanoparticles into the underlying gut associated lymphoid tissues would accelerate the development of oral vaccine formulations. Herein, a novel clearing-based whole tissue mount/imaging technique was developed to enable the specific distribution of nanoparticles within ex vivo murine PPs to be quantitatively determined at the cellular level. This revealed that 200 nm nanoparticles modified with M cell targeting ligands (lectin Ulex europaeus agglutinin-1, UEA-1) were translocated into subepithelial domes 7.6 and 16.3 times greater than the non-targeted ones at 60 min and 120 min, respectively. This approach provides a new methodology to quantitatively investigate the transcytotic activity of M cells for particulate formulations, which may aid in the design of improved oral vaccines.

Enhancement of atorvastatin oral bioavailability via encapsulation in polymeric nanoparticles

Despite the fact that atrovastatin (At) is being one of the bestselling statins used to prevent complicated cardiovascular diseases, its low oral bioavailability decreases its clinical relevance. Herein, incorporation of At into ethylcellulose nanoparticles (At-NPs) was executed to test if it would enhance its oral bioavailability. The emulsification-evaporation method was used to prepare the At-NPs. The prepared nanoparticles were characterized by measuring the particle size, zeta potential as well as using FTIR, DSC, and XRD examination. The entrapment efficiency, drug content, and the in vitro release behavior of At-NPs were also examined. The in vivo oral bioavailability of the selected At-NPs formula was tested after being given orally to New Zealand rabbits. The nanoparticles obtained had a high drug content and a distinct spherical shape but with varying sizes. No physical or chemical interactions were detected between At and the nanoparticles as confirmed by FTIR, DSC, and XRD. The in vitro release study of At from the prepared At-NPs has shown nanoparticles size-dependent release behavior. The in vivo oral absorption testing confirmed the bioavailability of the prepared At-NPs to be as follows: (C_max = 940 ng/ml and AUC_0-12 = 8759 ng.h/ml) > Lipitor® (C_max = 635 ng/ml and AUC_0-12 = 4367 ng.h/ml) > At (C_max = 515 ng/ml and AUC_0-12 = 2517 ng.h/ml). These results revealed that the oral formula of At-NPs increases the bioavailability of At 3.87 times. This makes ethylcellulose nanoparticles an esteemed candidate nano-vehicle for At, increasing its bioavailability and thus improving its clinical relevance.

Progress in the design and development of "fast-dissolving" electrospun nanofibers based drug delivery systems - A systematic review

Electrospinning has emerged as most viable approach for the fabrication of nanofibers with several beneficial features that are essential to various applications ranging from environment to biomedicine. The electrospun nanofiber based drug delivery systems have shown tremendous advancements over the controlled and sustained release complemented from their high surface area, tunable porosity, mechanical endurance, offer compatible environment for drug encapsulation, biocompatibility, high drug loading and tailorable release characteristics. The dosage formulation of poorly water-soluble drugs often faces several challenges including complete dissolution with maximum therapeutic efficiency over a short period of time especially through oral administration. In this context, challenges associated with the dosage formulation of poorly-water soluble drugs can be addressed through combining the beneficial features of electrospun nanofibers. This review describes major developments progressed in the preparation of electrospun nanofibers based "fast dissolving" drug delivery systems by employing variety of polymers, drug molecules and encapsulation approaches with primary focus on oral delivery. Furthermore, the review also highlights current scientific challenges and provide an outlook with regard to future prospectus.

Oral delivery of insulin with intelligent glucose-responsive switch for blood glucose regulation

BACKGROUND

The traditional treatment for diabetes usually requires frequent insulin injections to maintain normoglycemia, which is painful and difficult to achieve blood glucose control.

RESULTS

To solve these problems, a non-invasive and painless oral delivery nanoparticle system with bioadhesive ability was developed by amphipathic 2-nitroimidazole-L-cysteine-alginate (NI-CYS-ALG) conjugates. Moreover, in order to enhance blood glucose regulation, an intelligent glucose-responsive switch in this nanoparticle system was achieved by loading with insulin and glucose oxidase (GOx) which could supply a stimulus-sensitive turnover strategy. In vitro tests illustrated that the insulin release behavior was switched "ON" in response to hyperglycemic state by GOx catalysis and "OFF" by normal glucose levels. Moreover, in vivo tests on type I diabetic rats, this system displayed a significant hypoglycemic effect, avoiding hyperglycemia and maintaining a normal range for up to 14 h after oral administration.

CONCLUSION

The stimulus-sensitive turnover strategy with bioadhesive oral delivery mode indicates a potential for the development of synthetic GR-NPs for diabetes therapy, which may provide a rational design of proteins, low molecular drugs, as well as nucleic acids, for intelligent releasing via the oral route.

Could the Induction of Trained Immunity by β-Glucan Serve as a Defense Against COVID-19?

As the SARS-CoV-2 virus wreaks havoc on the populations, health care infrastructures and economies of nations around the world, finding ways to protect health care workers and bolster immune responses in the general population while we await an effective vaccine will be the difference between life and death for many people. Recent studies show that innate immune populations may possess a form of memory, termed Trained Immunity (TRIM), where innate immune cells undergo metabolic, mitochondrial, and epigenetic reprogramming following exposure to an initial stimulus that results in a memory phenotype of enhanced immune responses when exposed to a secondary, heterologous, stimulus. Throughout the literature, it has been shown that the induction of TRIM using such inducers as the BCG vaccine and β-glucan can provide protection through altered immune responses against a range of viral infections. Here we hypothesize a potential role for β-glucan in decreasing worldwide morbidity and mortality due to COVID-19, and posit several ideas as to how TRIM may actually shape the observed epidemiological phenomena related to COVID-19. We also evaluate the potential effects of β-glucan in relation to the immune dysregulation and cytokine storm observed in COVID-19. Ultimately, we hypothesize that the use of oral β-glucan in a prophylactic setting could be an effective way to boost immune responses and abrogate symptoms in COVID-19, though clinical trials are necessary to confirm the efficacy of this treatment and to further examine differential effects of β-glucan's from various sources.

Oral delivery of protein-based therapeutics: Gastroprotective strategies, physiological barriers and in vitro permeability prediction

The number of biological molecules emerging as therapeutics is growing exponentially due to their higher specificity and tolerability profiles compared to small molecules. Despite this, their traditionally parenteral delivery often results in poor patient compliance and incomplete treatment. Current research is focussed on developing effective oral delivery strategies to facilitate administration of these biomolecules, however no universal method exists to simultaneously provide gastric protection as well as enhance transport across the gastrointestinal epithelium. Furthermore, for efficient formulation development it is imperative that we can reliably analyse permeability of biomolecules through the gastrointestinal tract, highlighting the importance of the continual development and ongoing evaluation of in vitro predictive permeability tools. Here, we review the physiological obstacles associated with peptide and protein delivery throughout the gastrointestinal tract. Furthermore, we highlight methods utilised to circumvent these barriers and promote improved intestinal permeability. Lastly, we explore in vitro models employed to predict epithelial transport. Key findings highlight the need to carefully understand gastrointestinal physiology, allowing specific engineering of oral delivery systems for biomolecules. Significant importance is placed upon understanding enzymatic degradation susceptibility as well as uptake mechanisms for particulate and protein-based therapeutics for the development of successful oral protein delivery platforms.

The construction of in vitro nasal cavity-mimic M-cell model, design of M cell-targeting nanoparticles and evaluation of mucosal vaccination by nasal administration

In order to better evaluate the transport effect of nanoparticles through the nasal mucosa, an in vitro nasal cavity-mimic model was designed based on M cells. The differentiation of M cells was induced by co-culture of Calu-3 and Raji cells in invert model. The ZO-1 protein staining and the transport of fluorescein sodium and dexamethasone showed that the inverted co-culture model formed a dense monolayer and possessed the transport ability. The differentiation of M cells was observed by up-regulated expression of Sialyl Lewis A antigen (SLAA) and integrin β1, and down-regulated activity of alkaline phosphatase. After targeting M cells with iRGD peptide (cRGDKGPDC), the transport of nanoparticles increased. In vivo, the co-administration of iRGD could result in the increase of nanoparticles transported to the brain through the nasal cavity after intranasal administration. In the evaluation of immune effect in vivo, the nasal administration of OVA-PLGA/iRGD led to more release of IgG, IFN-γ, IL-2 and secretory IgA (sIgA) compared with OVA@PLGA group. Collectively, the study constructed in vitro M cell model, and proved the enhanced effect of targeting towards M cell with iRGD on improving nasal immunity.

Nano-vesicles based on phospholipid-like amphiphilic polyphosphazenes to orally deliver ovalbumin antigen for evoking anti-tumor immune response

Aimed at evoking an adequate anti-tumor immune response via oral administration route, this study constructed functionally and structurally mimicking-bacteria-membrane (MBM) nano-vesicle (RGD-PEOP) to orally deliver ovalbumin (OVA) antigen. In terms of simulating bacterial membrane structure, we creatively designed this nano-vesicle to have phospholipid-like octadecylphosphoethanolamine groups in vesicle membrane to improve OVA loading by means of specific interactions including salt bridge and hydrogen bond interaction. For simulating bacterial membrane function, the RGD peptide was modified onto the nano-vesicle surface, and the resulting vector displayed a good transport ability with a 3.4-fold higher than free OVA. In vitro and in vivo assay showed that the expression of co-stimulatory molecules and MHC class II complexes was significantly enhanced by MBM nano-vesicle. IFN-γ and IL-4 levels also increased several folds in the MBM nano-vesicle group. Consequently, MBM nano-vesicle achieved the highest in vivo inhibition rate of 69% against E.G7-OVA tumors among all the oral groups. These results suggest that this MBM nano-vesicle may be a promising vector to orally deliver OVA antigen for cancer immunotherapy. STATEMENT OF SIGNIFICANCE: Developing an effective non-bacterial carrier for oral cancer immunotherapy remains challenging. This work constructed a mimicking-bacteria-membrane nano-vesicle based on phospholipid-like amphiphilic polyphosphazenes for oral delivery of ovalbumin antigen. With the considerable capability to load ovalbumin antigen and target M cells, the nano-vesicle produced remarkable tumor suppression in vivo by evoking anti-tumor immune response.

β-glucan as a new tool in vaccine development

Vaccination constitutes one of the major breakthroughs in human medicine. At the same time, development of more immunogenic vaccine alternatives to using aluminium-based adjuvants is one of the most important phases of vaccination development. Among different sources of carbohydrate polymers, including plants, microbes and synthetic sources tested, glucans were found to be the most promising vaccine adjuvant, as they alone stimulate various immune reactions including antibody production without any negative side effects. The use of glucan particles as a delivery system is a viable option based on the documented efficient antigen loading and receptor-targeted uptake in antigen-presenting cells. In addition to particles, soluble glucans can be used as novel hydrogels or as direct immunocyte-targeting delivery systems employing novel complexes with oligodeoxynucleotides. This review focuses on recent advances in glucan-based vaccine development from glucan-based conjugates to a glucan-based delivery and adjuvant platform.

Using 3D gastrointestinal tract in vitro models with microfold cells and mucus secreting ability to assess the hazard of copper oxide nanomaterials

BACKGROUND

Copper oxide nanomaterials (CuO NMs) are exploited in many products including inks, cosmetics, textiles, wood preservatives and food contact materials. Their incorporation into these products may enhance oral exposure in consumer, environmental and occupational settings. Undifferentiated and differentiated monocultures of Caco-2 cells are commonly used to assess NM toxicity to the intestine in vitro. However, the integration of other cell types into Caco-2 in vitro models increases their physiological relevance. Therefore, the aim of this study is to evaluate the toxicity of CuO NMs and copper sulphate (CuSO4) to intestinal microfold (M) cell (Caco-2/Raji B) and mucus secreting (Caco-2/HT29-MTX) co-culture in vitro models via assessment of their impact on barrier integrity, viability and interleukin (IL)-8 secretion. The translocation of CuO NMs and CuSO4 across the intestinal barrier was also investigated in vitro.

RESULTS

CuO NMs and CuSO4 impaired the function of the intestinal barrier in the co-culture models [as indicated by a reduction in transepithelial electrical resistance (TEER) and Zonular occludens (ZO-1) staining intensity]. Cu translocation was observed in both models but was greatest in the Caco-2/Raji B co-culture. CuO NMs and CuSO4 stimulated an increase in IL-8 secretion, which was greatest in the Caco-2/HT29-MTX co-culture model. CuO NMs and CuSO4 did not stimulate a loss of cell viability, when assessed using light microscopy, nuclei counts and scanning electron microscopy. CuO NMs demonstrated a relatively similar level of toxicity to CuO4 in both Caco-2/Raji B and Caco-2/HT29-MTX co- culture models.

CONCLUSIONS

The Caco-2/Raji B co-culture model was more sensitive to CuO NM and CuSO4 toxicity than the Caco-2/HT29-MTX co-culture model. However, both co-culture models were less sensitive to CuO NM and CuSO4 toxicity than simple monocultures of undifferentiated and differentiated Caco-2 cells, which are more routinely used to investigate NM toxicity to the intestine. Obtained data can therefore feed into the design of future studies which assess the toxicity of substances (e.g. NMs) and pathogens to the intestine (e.g. by informing model and endpoint selection). However, more testing with a wider panel of NMs would be beneficial in order to help select which in vitro models and endpoints to prioritise when screening the safety of ingested NMs. Comparisons with in vivo findings will also be essential to identify the most suitable in vitro model to screen the safety of ingested NMs.

Challenges and Recent Progress in Oral Drug Delivery Systems for Biopharmaceuticals

Routes of drug administration and the corresponding physicochemical characteristics of a given route play significant roles in therapeutic efficacy and short term/long term biological effects. Each delivery method has favorable aspects and limitations, each requiring a specific delivery vehicles design. Among various routes, oral delivery has been recognized as the most attractive method, mainly due to its potential for solid formulations with long shelf life, sustained delivery, ease of administration and intensified immune response. At the same time, a few challenges exist in oral delivery, which have been the main research focus in the field in the past few years. The present work concisely reviews different administration routes as well as the advantages and disadvantages of each method, highlighting why oral delivery is currently the most promising approach. Subsequently, the present work discusses the main obstacles for oral systems and explains the most recent solutions proposed to deal with each issue.

Alternative Methods of Vaccine Delivery: An Overview of Edible and Intradermal Vaccines

Vaccines are recognized worldwide as one of the most important tools for combating infectious diseases. Despite the tremendous value conferred by currently available vaccines toward public health, the implementation of additional vaccine platforms is also of key importance. In fact, currently available vaccines possess shortcomings, such as inefficient triggering of a cell-mediated immune response and the lack of protective mucosal immunity. In this regard, recent work has been focused on vaccine delivery systems, as an alternative to injectable vaccines, to increase antigen stability and improve overall immunogenicity. In particular, novel strategies based on edible or intradermal vaccine formulations have been demonstrated to trigger both a systemic and mucosal immune response. These novel vaccination delivery systems offer several advantages over the injectable preparations including self-administration, reduced cost, stability, and elimination of a cold chain. In this review, the latest findings and accomplishments regarding edible and intradermal vaccines are described in the context of the system used for immunogen expression, their molecular features and capacity to induce a protective systemic and mucosal response.

Role of intestinal microecology in the regulation of energy metabolism by dietary polyphenols and their metabolites

Background

Polyphenols are a class of plant secondary metabolites with a variety of physiological functions. Polyphenols and their intestinal metabolites could greatly affect host energy metabolism via multiple mechanisms.

Objective

The objective of this review was to elaborate the role of intestinal microecology in the regulatory effects of dietary polyphenols and their metabolites on energy metabolism.

Methods

In this review, we illustrated the potential mechanisms of energy metabolism regulated by the crosstalk between polyphenols and intestinal microecology including intestinal microbiota, intestinal epithelial cells, and mucosal immune system.

Results

Polyphenols can selectively regulate the growth of susceptible microorganisms (eg. reducing the ratio of Firmicutes to Bacteroides, promoting the growth of beneficial bacteria and inhibiting pathogenic bacteria) as well as alter bacterial enzyme activity. Moreover, polyphenols can influence the absorption and secretion of intestinal epithelial cells, and alter the intestinal mucosal immune system.

Conclusion

The intestinal microecology play a crucial role for the regulation of energy metabolism by dietary polyphenols.