Chitosan enhances transcellular permeability in human and rat intestine epithelium

Enhanced alleviation of the selenite-grafted soluble and nondigestive Chinese Yam polysaccharides on nonylphenol-induced cytotoxicity and barrier damage in intestinal epithelial cells

This study explored the in vitro alleviation of the soluble and non-digestible Chinese yam polysaccharides (YP) with covalent selenite-grafting on the nonylphenol-induced cytotoxicity and barrier damage in rat intestinal epithelial (IEC-6) cells. Two grafted products YPSe-I and particularly YPSe-II possessed much higher Se contents than YP (0.803 and 1.486 versus 0.037 g/kg), could alleviate the cytotoxicity of nonylphenol by causing higher cell viability but lower lactate dehydrogenase release and ROS production, and were capable of repairing the induced barrier damage through increasing transepithelial electrical resistance, reducing paracellular permeability, promoting the production and distribution of cytoskeleton F-actin, and up-regulating the expression levels of three tight junction proteins namely zonula occludens-1, occludin, and claudin-1. Meanwhile, the expression levels of two proteins namely p-p38 and p-JNK in the cells, which are crucial to the activation of the MAPK signaling pathway, were up-regulated by nonylphenol but down-regulated by YPSe-I and YPSe-II. The results consistently confirmed that YP and YPSe-II exhibited the respective lowest and highest activities in the cells to alleviate the nonylphenol-induced cytotoxicity and barrier damage, declaring that both YP selenization and higher selenite-grafting extent were the critical factors controlling the measured activities of YPSe-I and YPSe-II. Collectively, this selenite-grafting of YP endowed the selenized products with higher activity in the cells to reduce nonylphenol-induced cytotoxicity, especially to alleviate the induced barrier damage by inactivating the MAPK signaling pathway.

Covalent Grafting of Inorganic Selenium to the Water-Soluble and Nondigestive Chinese Yam Polysaccharides Causes Greater Protection of IEC-6 Cells with Acrylamide Injury

Acrylamide, a harmful substance generated during the normal thermal treatment of foods, has been shown to adversely affect human health, particularly the vital intestinal barrier function. Meanwhile, natural polysaccharides are recognized to exert an important biofunction in the intestine by protecting barrier integrity. In this study, the non-starch, water-soluble, and nondigestive yam polysaccharide (YP) was extracted from fresh Chinese yam, while two selenylated derivatives with different extents of selenylation were prepared via the HNO3-Na2SeO3 reaction system, and designated as YPSe-I and YPSe-II, respectively. Their protective activities and the associated molecular mechanisms of these substances against acrylamide-induced damage in rat intestinal epithelial (IEC-6) cells were thereby investigated. The experimental results demonstrated that the selenium contents of YPSe-I and YPSe-II were 0.80 and 1.48 g/kg, respectively, whereas that of the original YP was merely 0.04 g/kg. In IEC-6 cells, in comparison with YP, both YPSe-I and YPSe-II showed higher efficacy than YP in alleviating acrylamide-induced cell toxicity through promoting cell viability, suppressing the release of lactate dehydrogenase, and decreasing the generation of intracellular reactive oxygen species. Both YPSe-I and YPSe-II could also manifest higher effectiveness than YP in maintaining cell barrier integrity against the acrylamide-induced barrier disruption. The mentioned barrier protection was achieved by increasing transepithelial electrical resistance, reducing paracellular permeability, facilitating the distribution and expression of F-actin between the cells, and up-regulating the production of three tight junctions, namely ZO-1, occludin, and claudin-1. Additionally, acrylamide was observed to trigger the activation of the MAPK signaling pathway, thereby leading to cell barrier dysfunction. In contrast, YPSe-I and particularly YPSe-II were capable of down-regulating two MAPK-related proteins, namely p-p38 and p-JNK, and thereby inhibiting the acrylamide-induced activation of the MAPK signaling pathway. Moreover, YPSe-II in the cells was consistently shown to provide greater barrier protection than YPSe-I. In conclusion, chemical selenylation of YP could cause higher activity in mitigating acrylamide-induced cytotoxicity and intestinal barrier dysfunction, while the efficacy of activity enhancement was positively affected by the selenylation extent.

Role of chitosan in intestinal integrity: TLR4 and IFNAR signaling in the induction of E-cadherin and CD103 in mice

Chitin and its derivative chitosan (Q) are abundant structural elements in nature. Q has modulatory and anti-inflammatory effects and also regulates the expression of adhesion molecules. The interaction between cells expressing the αEβ7 integrin and E-cadherin facilitates tolerogenic signal transmission and localization of lymphocytes at the frontline for interaction with luminal antigens. In this study we evaluated the ability of orally administered Q to stimulate E-cadherin and CD103 expression in vitro and in vivo. Our findings show that Q promoted epithelial cell migration, accelerated wound healing and increased E-cadherin expression in IEC-18 cells and isolated intestinal epithelial cells (IECs) after Q feeding. The upregulation of E-cadherin was dependent on TLR4 and IFNAR signaling, triggering CD103 expression in lymphocytes. Q reinforced the E-cadherin-αEβ7 axis, crucial for intestinal barrier integrity and contributed to the localization of lymphocytes on the epithelium.

The Barrier-Enhancing Function of Soluble Yam (Dioscorea opposita Thunb.) Polysaccharides in Rat Intestinal Epithelial Cells, as Affected by the Covalent Se Conjugation

The non-starch yam polysaccharides (YP) are the bioactive substances of edible yam, while Se is an essential nutrient for the human body. Whether a covalent conjugation of Se to YP might cause bioactivity change for the resultant selenylated YP in the intestine is still insufficiently studied, including the critical intestinal barrier function. In this study, two selenylated YP products, namely, YPSe-I and YPSe-II, with corresponding Se contents of 795 and 1480 mg/kg, were obtained by the reaction of YP and Na2SeO3 in the presence of HNO3 and then assessed for their bioactivities to a cell model (i.e., rat intestinal epithelial IEC-6 cells). The results showed that YP, YPSe-I, and YPSe-II at 5–80 μg/mL dosages could promote cell growth with treatment times of 12–24 h. The three samples also could improve barrier integrity via increasing cell monolayer resistance and anti-bacterial activity against E. coli or by reducing paracellular permeability and bacterial translocation. Additionally, the three samples enhanced F-actin distribution and promoted the expression of the three tight junction proteins, namely, zonula occluden-1, occludin, and claudin-1. Meanwhile, the expression levels of ROCK and RhoA, two critical proteins in the ROCK/RhoA singling pathway, were down-regulated by these samples. Collectively, YPSe-I and, especially, YPSe-II were more potent than YP in enhancing the assessed bioactivities. It is thus concluded that this chemical selenylation of YP brought about enhanced activity in the cells to promote barrier integrity, while a higher selenylation extent of the selenylated YP induced much activity enhancement. Collectively, the results highlighted the important role of the non-metal nutrient Se in the modified polysaccharides.

An overview of oral insulin delivery strategies (OIDS)

Despite tremendous efforts, the world continues its fight against the common chronic disease-diabetes. Diabetes is caused by elevated glucose levels in the blood, which can lead to several complications like glaucoma, cataract, kidney failure, diabetic ketoacidosis, heart attack, and stroke. According to recent statistics, China, India, and the US rank at the top three positions with regards to the number of patients affected by diabetes. Ever since its discovery, insulin is one of the major therapeutic molecules that is used to control the disease in the diabetic population, worldwide. The most common route of insulin administration has been the subcutaneous route. However, the limitations associated with this route have motivated global efforts to explore alternative strategies to deliver insulin, including pulmonary, transdermal, nasal, rectal, buccal, and oral routes. Oral insulin delivery is the most convenient and patient-centered route. However, the oral route is also associated with numerous drawbacks that present significant challenges to the scientific fraternity. The human physiological system acts as a formidable barrier to insulin, limiting its bioavailability. The present review covers the major barriers against oral insulin delivery and explains formulation strategies that have been adopted to overcome these barriers. The review focuses on oral insulin delivery strategies (OIDS) for increasing the bioavailability of oral insulin, including nanoparticles, microparticles, nano-in-microparticles, hydrogels, tablets, capsules, intestinal patches, and use of ionic liquids. It also highlights some of the notable recent advancements and clinical trials in oral insulin delivery. This formulation based OIDS may significantly improve patient compliance in the treatment of diabetes.

Reviewing the biological activity of chitosan in the mucosa: Focus on intestinal immunity

Chitosan is a polymer derived from the partial deacetylation of chitin with particular characteristics, such as mucoadhesiveness, tolerability, biocompatibility and biodegradability. Biomedical uses of chitosan cover a wide spectrum of applications as dietary fiber, immunoadjuvant and regulator of the intestinal microbiota or delivery agent. Chemical modification of chitosan is feasible because its reactive amino and hydroxyl groups can be modified by a diverse array of ligands, functional groups and molecules. This gives rise to numerous derivatives that allow different formulation types influencing their activity. Considering the multiple events resulting from the interaction with mucosal tissues, chitosan is a singular candidate for strategies targeting immune stimulation (i.e., tolerance induction, vaccination). Its role as a prebiotic and probiotic carrier represents an effective option to manage intestinal dysbiosis. In the intestinal scenario where the exposure of the immune system to a wide variety of antigens is permanent, chitosan increases IgA levels and favors a tolerogenic environment, thus becoming a key ally for host homeostasis.

Complex Polysaccharide-Based Nanocomposites for Oral Insulin Delivery

Polyelectrolyte nanocomposites rarely reach a stable state and aggregation often occurs. Here, we report the synthesis of nanocomposites for the oral delivery of insulin composed of alginate, dextran sulfate, poly-(ethylene glycol) 4000, poloxamer 188, chitosan, and bovine serum albumin. The nanocomposites were obtained by Ca²⁺-induced gelation of alginate followed by an electrostatic-interaction process among the polyelectrolytes. Chitosan seemed to be essential for the final size of the nanocomposites and there was an optimal content that led to the synthesis of nanocomposites of 400–600 nm hydrodynamic size. The enhanced stability of the synthesized nanocomposites was assessed with LUMiSizer after synthesis. Nanocomposite stability over time and under variations of ionic strength and pH were assessed with dynamic light scattering. The rounded shapes of nanocomposites were confirmed by scanning electron microscopy. After loading with insulin, analysis by HPLC revealed complete drug release under physiologically simulated conditions.

Surface-modified mucoadhesive microparticles as a controlled release system for oral delivery of insulin

To overcome barriers and improve oral bioavailability of insulin delivery has been a mirage to formulation scientists due to instability of the insulin after oral administration. Microparticle (MP) composed of chitosan and snail mucin was prepared via double emulsion method for oral delivery of insulin. Microparticles were characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy and scanning electron microscopy. The encapsulation efficiency (EE) of the insulin-loaded MPs were evaluated. Insulin release behavior was evaluated in acidic and phosphate buffer (pH 1.2 and 7.4) at 37 °C. Bioactivities of insulin-loaded MPs were evaluated in a diabetic animal model after oral administration. The insulin-loaded MPs showed irregular shape with a zeta potential (>29 mV). The encapsulation efficiency and drug loading were >75 and 28 %, respectively. The in vitro release shows >80 % release of insulin over 12 h in a sustained manner. The insulin-MPs significantly reduced blood glucose levels (>50 %) compared to positive control and the effect lasted for over 8 h. This study suggests that insulin-MPs as prepared would be potential carriers for oral delivery of insulin.

Interaction Between Chitosan and Mucin: Fundamentals and Applications

The term chitosan (CS) refers to a family of aminopolysaccharides derived from chitin. Among other properties, CS is nontoxic, mucoadhesive and can be used for load and transport drugs. Given these and other physicochemical and biological properties, CS is an optimal biopolymer for the development of transmucosal drug delivery systems, as well as for the treatment of pathologies related to mucosal dysfunctions. Mucins are glycoprotein macromolecules that are the major components of mucus overlaying epithelia. CS interacts with mucin and adsorbs on and changes the rheology of mucus. However, CS and mucins denote families of polymers/macromolecules with highly variable chemical structure, properties, and behavior. To date, their interactions at the molecular level have not been completely unraveled. Also, the properties of complexes composed of CS and mucin vary as a function of the sources and preparation of the polymers. As a consequence, the mucoadhesion and drug delivery properties of such complexes vary as well. The breadth of this review is on the molecular interactions between CS and mucin. In particular, in vitro and ex vivo characterization methods to investigate both the interactions at play during the formation of CS-mucin complexes, and the advances on the use of CS for transmucosal drug delivery are addressed.

Chitosan oligosaccharides alleviate PM2.5-induced lung inflammation in rats

Air pollution of particulate matter (PM), especially PM_2.5, has become a major public health problem in China. Exploration of therapeutic and preventive measures against PM_2.5 toxicity is of practical significance. The aim of this study was to examine the inhibitory effects of chitosan oligosaccharides (COS) on PM_2.5-induced lung inflammation in rats. Forty SPF (specific pathogen-free) male Wistar rats weighing 200-220 g were randomly divided into four groups: control group, COS group, PM_2.5 group, and PM_2.5+COS group. COS was pre-administered to rats by gavage at a single dose of 500 mg/kg 2 h before intratracheal instillation of PM_2.5 at a single dose of 1.2 mg/kg daily for 3 consecutive days. Normal saline (NS) was used as negative control. Twenty-four hours after the last instillation of PM_2.5, rats were sacrificed and subjected to bronchoalveolar lavage (BAL). The BAL fluids (BALF) were collected for measurement of levels of total proteins, lactate dehydrogenase (LDH), interleukin-1 (IL-1β), IL-8, and tumor necrosis factor-ɑ (TNF-ɑ) using colorimetric or ELISA kits. Levels of total proteins, LDH activities, and pro-inflammatory mediators including IL-1β, IL-8, and TNF-ɑ in BALF of rats in PM_2.5 group significantly increased in comparison with those of the control group. Pre-treatment of rats with COS markedly blocked PM_2.5-induced increase in LDH, IL-8, and TNF-ɑ levels in BALF. In conclusion, PM_2.5 exposure induces rat lung inflammation, which could be ameliorated by the pre-treatment of COS.

Mechanism of surface charge triggered intestinal epithelial tight junction opening upon chitosan nanoparticles for insulin oral delivery

Intestinal epithelium is a major barrier limiting the absorption of oral insulin owing to the presence of intercellular tight junctions (TJs). Previous studies proved that carboxymethyl chitosan/chitosan-nanoparticles (CMCS/CS-NPs) exhibited surface charge depending promotion of intestinal absorption. This study further confirmed the better performances of insulin:CMCS/CS-NPs(-) in enhancing epithelial permeation, increasing bioavailability and extending blood duration of insulin than insulin:CMCS/CS-NPs(+). Immunohistochemistry sections found that TJs on jejunum epithelium completely disappeared in insulin:CMCS/CS-NPs(-) group, partially existed in insulin:CMCS/CS-NPs(+) group and appeared no change in control. Surface charges of CMCS/CS-NPs triggered intestinal epithelial TJs opening through different mechanisms. Although a down-regulation of TJs protein claudin-4 was detected in both nanoparticles groups, for phosphorylated claudin-4, the activating form, whose down-regulation occurred only in insulin:CMCS/CS-NPs(-) group. Counting upon synergetic effects of Ca²⁺ deprivation from adherens junctions and claudin-4 dephosphorylation and degradation, CMCS/CS-NPs(-) triggered more extensive disintegration of TJs and stronger paracellular permeability than the positive.

In vivo dual-delivery of glucagon like peptide-1 (GLP-1) and dipeptidyl peptidase-4 (DPP4) inhibitor through composites prepared by microfluidics for diabetes therapy

Oral delivery of proteins is still a challenge in the pharmaceutical field. Nanoparticles are among the most promising carrier systems for the oral delivery of proteins by increasing their oral bioavailability. However, most of the existent data regarding nanosystems for oral protein delivery is from in vitro studies, lacking in vivo experiments to evaluate the efficacy of these systems. Herein, a multifunctional composite system, tailored by droplet microfluidics, was used for dual delivery of glucagon like peptide-1 (GLP-1) and dipeptidyl peptidase-4 inhibitor (iDPP4) in vivo. Oral delivery of GLP-1 with nano- or micro-systems has been studied before, but the simultaneous nanodelivery of GLP-1 with iDPP4 is a novel strategy presented here. The type 2 diabetes mellitus (T2DM) rat model, induced through the combined administration of streptozotocin and nicotinamide, a non-obese model of T2DM, was used. The combination of both drugs resulted in an increase in the hypoglycemic effects in a sustained, but prolonged manner, where the iDPP4 improved the therapeutic efficacy of GLP-1. Four hours after the oral administration of the system, blood glucose levels were decreased by 44%, and were constant for another 4 h, representing half of the glucose area under the curve when compared to the control. An enhancement of the plasmatic insulin levels was also observed 6 h after the oral administration of the dual-drug composite system and, although no statistically significant differences existed, the amount of pancreatic insulin was also higher. These are promising results for the oral delivery of GLP-1 to be pursued further in a chronic diabetic model study.

Locked nucleic acid modified bi-specific aptamer-targeted nanoparticles carrying survivin antagonist towards effective colon cancer therapy

EpCAM and nucleolin translocate into the cytoplasm and nucleus that facilitates enhanced uptake of nanocarrier to specifically target cancer cells.

The complete functional recovery of chitosan-treated biomimetic hyperplastic and normoplastic urothelial models

The urinary tract is exposed to a variety of possible injures that may lead to organ damage or loss, and thus, the establishment of valid in vitro urothelial models to study the mechanism of drug candidates is necessary. This study is the first to investigate the effect of chitosan on urothelia in vitro and to evaluate whether chitosan-treated urothelial models can regenerate in vitro and reestablish a functional urothelium. Biomimetic hyperplastic and normoplastic urothelial models were used to test the effect of chitosan (0.05%) on partially and highly differentiated urothelial cells (UCs) by monitoring their molecular, ultrastructural, and physiological changes for 3 weeks. Chitosan caused an immediate and complete loss of transepithelial resistance (TER), tight junction disruption, cytopathological changes of UCs, and consequently enhanced the permeability of partially and highly differentiated urothelial models. However, 3 weeks after chitosan treatment, TER was reestablished, tight junctions resealed, permeability decreased, and progressive differentiation stages of newly exposed superficial UCs expressing uroplakins and tight junction protein claudin-8 were found. The in vitro models regenerated and reestablished urothelia with a tight barrier. The biomimetic urothelial models represent appropriate in vitro models for studying urothelial drug candidates as well as evaluating drug permeabilities and their intracellular function. Understanding the possible intracellular function of chitosan could significantly advance approaches to treating urothelial-specific diseases.

Recent advances in chitosan-based nanoparticles for oral delivery of macromolecules

Chitosan (CS), a cationic polysaccharide, is widely regarded as a safe and efficient intestinal absorption enhancer of therapeutic macromolecules, owing to its inherent mucoadhesive feature and ability to modulate the integrity of epithelial tight junctions reversibly. By using CS-based nanoparticles, many studies have attempted to protect the loaded macromolecules against acidic denaturation and enzymatic degradation, prolong their intestinal residence time, and increase their absorption by the intestinal epithelium. Derivatives of CS such as quaternized CS, thiolated CS and carboxylated CS have also been examined to further enhance its effectiveness in oral absorption of macromolecular drugs. This review article describes the synthesis of these CS derivatives and their characteristics, as well as their potential transport mechanisms of macromolecular therapeutics across the intestinal biological membrane. Recent advances in using CS and its derivatives as carriers for oral delivery of hydrophilic macromolecules and their effects on drug transport are also reviewed.

Enhanced dissolution and oral bioavailability of tanshinone IIA base by solid dispersion system with low-molecular-weight chitosan

OBJECTIVES

The aim of this study is to improve the dissolution and oral bioavailability of tanshinone IIA (TAN).

METHODS

Solid dispersions of TAN with low-molecular-weight chitosan (LMC) were prepared and the in-vitro dissolution and in-vivo performance were evaluated.

KEY FINDINGS

At 1 h, the extent of dissolution of TAN from the LMC-TAN system (weight ratio 9 : 1) increased about 368.2% compared with the pure drug. Increasing the LMC content from 9 : 1 to 12 : 1 in this system did not significantly increase the rate and the extent of dissolution. Differential scanning calorimetry, X-ray diffraction and scanning electron microscopy demonstrated the formation of amorphous tanshinone IIA and the absence of crystallinity in the solid dispersion. Fourier transform infrared spectroscopy revealed that there was no interaction between drug and carrier. In-vivo test showed that LMC-TAN solid dispersion system presented significantly larger AUC0-t , which was 0.67 times that of physical mixtures and 1.17 times that of TAN. Additionally, the solid dispersion generated obviously higher Cmax and shortened Tmax compared with TAN and physical mixtures.

CONCLUSIONS

In conclusion, the LMC -based solid dispersions could achieve complete dissolution, accelerated absorption rate and superior oral bioavailability.

DNA-loaded chitosan oligosaccharide nanoparticles with enhanced permeability across Calu-3 cells

Chitosan oligosaccharide (oligoCS) is a low molecular weight chitosan and its potential for DNA delivery is described here. DNA-loaded oligoCS nanoparticles were prepared by ionic gelation using thiamine pyrophosphate (TPP) as cross-linker. The nanoparticles with oligoCS:DNA: TPP weight ratio of 50:1:25 were approximately 170 nm in diameter with a zeta potential of +40 mV, and were used in the permeability study. The cytotoxicity of oligoCS solutions and nanoparticles was evaluated by MTT assay. The concentrations that exhibited minimal cytotoxicity were employed to investigate their effect on trans-epithelial electrical resistance (TEER) and cellular uptake across the Calu-3 cell layer which was used as a nasal epithelial model. OligoCS nanoparticles were able to cause a significant and reversible decrease in TEER and promote efficient cellular uptake. In addition, the oligoCS nanoparticles were able to enhance paracellular permeability to a greater extent than oligoCS solutions at an equivalent concentration. However, the oligoCS nanoparticles were too large to cross the cell layers through the paracellular route. The transcellular pathway appeared to be the major mechanism of the transportation of oligoCS nanoparticles across the cell layers. OligoCS nanoparticles also allowed efficient DNA incorporation, thereby providing the possibility of controlled nucleic acids release and absorption across epithelial surface.