Signals elicited at the intestinal epithelium upon chitosan feeding contribute to immunomodulatory activity and biocompatibility of the polysaccharide

Therapeutic potential of natural arginase modulators: mechanisms, challenges, and future directions

Arginase (Arg) plays a pivotal role in numerous pathological processes, with its dysregulated expression being intricately associated with tumor progression and immune evasion. This review comprehensively examines the diversity, mechanisms, and clinical potential of natural Arg modulators, encompassing polyphenols, flavonoids, and terpenoids. These bioactive compounds exert their modulatory effects on Arg activity through multiple mechanisms, including direct enzyme interaction, regulation of signaling pathways, and modulation of cellular metabolism. The therapeutic potential of these metabolites spans across various medical domains, notably in cardiovascular diseases, oncology, neurological disorders, and inflammatory conditions. Specifically, polyphenol metabolites such as resveratrol and curcumin have demonstrated significant benefits in cardiovascular health and neuroprotection, while flavonoids including rutin and quercetin have shown promising effects on intracellular inflammatory factors and tumor cell proliferation. Similarly, terpenoids like perillyl alcohol and triptolide have been found to influence cell polarization processes. However, despite their substantial therapeutic potential demonstrated in experimental studies, the development of natural Arg modulators faces several significant challenges. These include complexities in drug design attributed to the intricate structure and multiple isoforms of Arg, difficulties in elucidating precise mechanisms due to Arg's multifaceted roles in various metabolic pathways, and limitations in current drug delivery systems. To overcome these challenges, future research should focus on continuous optimization of experimental design paradigms, enhancement of experimental models and data quality, thorough evaluation of therapeutic efficacy, and strategic integration of natural Arg modulators with precision medicine approaches.

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.

Evaluation of Rouxiella badensis Subsp Acadiensis (Canan SV-53) as a Potential Probiotic Bacterium

The advent of omic platforms revealed the significant benefits of probiotics in the prevention of many infectious diseases. This led to a growing interest in novel strains of probiotics endowed with health characteristics related to microbiome and immune modulation. Therefore, autochthonous bacteria in plant ecosystems might offer a good source for novel next-generation probiotics. The main objective of this study was to analyze the effect of Rouxiella badensis acadiensis Canan (R. acadiensis) a bacterium isolated from the blueberry biota, on the mammalian intestinal ecosystem and its potential as a probiotic microorganism. R. acadiensis, reinforced the intestinal epithelial barrier avoiding bacterial translocation from the gut to deep tissues, even after feeding BALB/c mice for a prolonged period of time. Moreover, diet supplementation with R. acadiensis led to increases in the number of Paneth cells, well as an increase in the antimicrobial peptide α defensin. The anti-bacterial effect of R. acadiensis against Staphylococcus aureus and Salmonella enterica serovar Typhimurium was also reported. Importantly, R. acadiensis-fed animals showed better survival in an in vivo Salmonella enterica serovar Typhimurium challenge compared with those that received a conventional diet. These results demonstrated that R. acadiensis possesses characteristics of a probiotic strain by contributing to the reinforcement and maintenance of intestinal homeostasis.

Chitosan nanoparticles attenuate intestinal damage and inflammatory responses in LPS-challenged weaned piglets via prevention of IκB degradation

Chitosan nanoparticles (CNP), widely applied as oral drug/gene/vaccine carrier, were found to have anti-inflammatory properties. In this study, the effects of CNP on lipopolysaccharide (LPS)-induced intestinal damage in weaned piglets and the related mechanisms were investigated. Twenty-four weaned piglets (Duroc × Landrace × Yorkshire, 21 ± 2 day of age, initial mass: 8.58 ± 0.59 kg) were randomly assigned into four groups: control, LPS, CNP and CNP + LPS. The control and LPS groups were fed a corn-soybean meal-based control diet, whereas the CNP and CNP + LPS groups were fed a control diet supplemented with 400 mg/kg CNP. After 28 days of feeding, piglets in LPS and CNP + LPS groups were injected with LPS (100 μg/kg); meanwhile, the piglets in control and CNP groups were injected with sterile saline. After 4 h from the LPS challenge, pigs were sacrificed to collect the intestinal samples for analysis. The results showed that CNP could attenuate the intestinal damages and inflammatory response stimulated by LPS treatment. LPS induced dramatically higher levels of CD177⁺ neutrophils invasion in jejunum mucosa (p < 0.01), which accompanied by increased secretion of marks of inflammation (p < 0.01) compared with the control, whereas CNP administration obviously inhibited LPS-induced CD177⁺ neutrophils invasion (p < 0.01) and secretion of marks of inflammation, such as interleukin-8 (p < 0.05), intercellular adhesion molecule-1 (p < 0.05) secretion in jejunum mucosa compared with LPS group. Moreover, CNP was shown to inhibit IκB-α degradation in cytoplasm, which resulted in reduced nuclear translocation of NF-κB p65 in LPS-challenged piglets. These findings suggest that CNP attenuates intestinal damage and inflammatory responses in LPS-challenged weaned piglets by impairing the NF-κB signalling pathway.

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.

Probiotic lactobacilli as a promising strategy to ameliorate disorders associated with intestinal inflammation induced by a non-steroidal anti-inflammatory drug

Damage to the small intestine caused by non-steroidal anti-inflammatory drugs (NSAIDs) occurs more frequently than in the upper gastrointestinal tract, is more difficult to diagnose and no effective treatments exist. Hence, we investigated whether probiotics can control the onset of this severe condition in a murine model of intestinal inflammation induced by the NSAID, indomethacin. Probiotic supplementation to mice reduce the body weight loss, anemia, shortening of the small intestine, cell infiltration into the intestinal tissue and the loss of Paneth and Goblet cells associated with intestinal inflammation. Furthermore, a high antimicrobial activity in the intestinal fluids of mice fed with probiotics compared to animals on a conventional diet was elicited against several pathogens. Interestingly, probiotics dampened the oxidative stress and several local and systemic markers of an inflammatory process, as well as increased the secretion of IL-10 by regulatory T cells. Even more importantly, probiotics induced important changes in the large intestine microbiota characterized by an increase in anaerobes and lactobacilli, and a significant decrease in total enterobacteria. We conclude that oral probiotic supplementation in NSAID-induced inflammation increases intestinal antimicrobial activity and reinforces the intestinal epithelial barrier in order to avoid pathogens and commensal invasion and maintain intestinal homeostasis.

Chitosan enhances nanoparticle delivery from the reproductive tract to target draining lymphoid organs

To prime adaptive immune responses from the female reproductive tract (FRT), particulate antigens must be transported to draining lymph nodes (dLNs) since there are no local organized lymphoid structures equivalent to those found in the respiratory or gastrointestinal tracts. However, little is known about how to safely and effectively navigate successive barriers to transport such as crossing the epithelium and gaining access to migratory cells and lymphatic drainage that provide entry into dLNs. Here, we demonstrate that intravaginal pre-treatment with chitosan significantly facilitates translocation of nanoparticles (NPs) across the multilayered vaginal epithelium to target dLNs. In addition, chitosan pre-treatment was found to enhance NP associations with immunogenic antigen presenting cells in the vaginal submucosa. These observations indicate that chitosan may have great potential as an adjuvant for both local and systemic protective immunity against viral infections in the FRT.

Immunomodulatory properties of shellfish derivatives associated with human health

Some vital components of marine shellfish are documented as an important source for both nutritional and pharmacological applications.

Chitin, a key factor in immune regulation: lesson from infection with fungi and chitin bearing parasites

The probability of infection with fungi, as well as parasitic nematodes or arthropods may increase in overcrowded population of animals and human. The widespread overuse of drugs and immunosuppressants for veterinary or medical treatment create an opportunity for many pathogenic species. The aim of the review is to present the common molecular characteristics of such pathogens as fungi and nematodes and other chitin bearing animals, which may both activate and downregulate the immune response of the host. Although these pathogens are evolutionary distinct and distant, they may provoke similar immune mechanisms. The role of chitin in these phenomena will be reviewed, highlighting the immune reactions that may be induced in mammals by this natural polymer.

Endotoxins affect diverse biological activity of chitosans in matters of hemocompatibility and cytocompatibility

Chitosan is used in several pharmaceutical and medical applications, owing to its good cytocompatibility and hemocompatibility. However, there are conflicting reports regarding the biological activities of chitosan with some studies reporting anti-inflammatory properties while others report pro-inflammatory properties. In this regards we analyzed the endotoxin content in five different chitosans and examined these chitosans with their different deacetylation degrees for their hemocompatibility and cytocompatibility. Therefore, we incubated primary human endothelial cells or whole blood with different chitosan concentrations and studied the protein and mRNA expression of different inflammatory markers or cytokines. Our data indicate a correlation of the endotoxin content and cytokine up-regulation in whole blood for Poly-Morpho-Nuclear (PMN)-Elastase, soluble terminal complement complex SC5b-9, complement component C5/C5a, granulocyte colony-stimulating factor, Interleukin-8 (IL), IL-10, IL-13, IL-17E, Il-32α and monocyte chemotactic protein-1. In contrast, the incubation of low endotoxin containing chitosans with primary endothelial cells resulted in increased expression of E-selectin, intercellular adhesion molecule-1, vascular cell adhesion protein-1, IL-1β, IL-6 and IL-8 in endothelial cells. We suggest that the endotoxin content in chitosan plays a major role in the biological activity of chitosan. Therefore, we strongly recommend analysis of the endotoxin concentration in chitosan, before further determining if it has pro- or anti-inflammatory properties or if it is applicable for pharmaceutical and medical fields.

Human intestinal epithelial cells express interleukin-10 through Toll-like receptor 4-mediated epithelial-macrophage crosstalk

In the intestine, interaction between epithelial cells and macrophages (MΦs) create a unique immunoregulatory microenvironment necessary to maintain local immune and tissue homeostasis. Human intestinal epithelial cells (IECs) have been shown to express interleukin (IL)-10, which keeps epithelial integrity. We have demonstrated that bacterial signaling through Toll-like receptor (TLR) 4 induces 15-deoxy-Δ-12,14-prostaglandin J2 (15d-PGJ2) synthesis in intestinal MΦs by cyclooxygenase (Cox)-2 expression. Here, we show that TLR4 signaling generates crosstalk between IECs and MΦs that enhances IL-10 expression in IECs. Direct stimulation of TLR4 leads to the expression of IL-10 in IECs, while the presence of MΦs in a Transwell system induces another peak in IL-10 expression in IECs at a later time point. The second peak of the IL-10 expression is two times greater than the first peak. This late induction of IL-10 depends on the nuclear receptor peroxisome proliferator-activated receptor (PPAR) γ that is accumulated in IECs by TLR4-mediated inhibition of the ubiquitin-proteasomal pathway. TLR4 signaling in MΦs in turn synthesizes 15d-PGJ2 through p38 and ERK activation and Cox-2 induction, which activates PPARγ in IECs. These results suggest that TLR4 signaling maintains IL-10 production in IECs by generating epithelial-MΦs crosstalk, which is an important mechanism in the maintenance of intestinal homeostasis mediated through host-bacterial interactions.

Immunoregulatory activities of Dendrobium huoshanense polysaccharides in mouse intestine, spleen and liver

To evaluate the immunomodulating responses in intestine, spleen and liver, 50-200mg/kg of DHP was orally administrated to mice without or with methotrexate. The proliferation of marrow cells, which was performed with the addition of the supernatant of small intestinal lymphocytes isolated from the mice administrated orally with DHP, showed that the intestinal immune response was significantly enhanced in all DHP-treated groups. For the immune response in spleen, all tested doses of DHP remarkably promoted the proliferation of splenic cells and increased the secretion of interferon-γ (IFN-γ). For the immune responses in liver, DHP not only significantly stimulated the proliferation of hepatic cells and the secretion of IFN-γ at all tested doses of DHP, but also significantly elevated the secretion interleukin-4 (IL-4) at the doses of 100 and 200mg/kg. Moreover, DHP could recover methotrexate-injured small intestinal immune function (100 and 200mg/kg) and promoted cell proliferation and IFN-γ production (200mg/kg) in spleen and liver of methotrexate-treated mice. These results suggested that DHP after oral administration possessed immunomodulating effects both in small intestine immune system and in systemic immune system, which were further proved by the mRNA expression of IFN-γ and IL-4.

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.

Chitooligosaccharide elicits acute inflammatory cytokine response through AP-1 pathway in human intestinal epithelial-like (Caco-2) cells

Chitooligosaccharides (COSs) are bioactive carbohydrate derivatives that have numerous health benefits, including stimulation of the immune system. The objectives of this study were to evaluate the effect of chitooligosaccharide (COS) on expression of a specific panel of cytokine genes involved in inflammation and to delineate the signal transduction pathway underlying the COS mediated inflammatory response. Human intestinal epithelial-like (Caco-2) cells were treated with COS (5000-10,000Da) and expression of a panel of eighty-four cytokine genes was analyzed by quantitative real-time PCR. COS induced up-regulation of a total of 11 genes including CCL20 and IL8 and concurrent down-regulation of 10 genes including pro-inflammatory mediators CCL15, CCL25 and IL1B. To further establish the signal transduction pathway of COS mediated response in Caco-2 cells, two major inflammatory signal transduction pathways (NF-κB and AP-1) were investigated. COS had inhibitory effect (P<0.01) on TNF-α induced NF-κB binding activity while stimulatory effect (P<0.001) on AP-1 binding activity. COS also inhibited the expression of RELA (P<0.01) and IKBKB (P<0.01) genes of NF-κB pathway while stimulate the expression of JUN (P<0.05) gene of AP-1 pathway. In conclusion, COS elicits an acute inflammatory cytokine response in Caco-2 cells and hence it has the potential to stimulate the immune system in the gut epithelium.

Zwitterionic chitosan derivative, a new biocompatible pharmaceutical excipient, prevents endotoxin-mediated cytokine release

Chitosan is a cationic polymer of natural origin and has been widely explored as a pharmaceutical excipient for a broad range of biomedical applications. While generally considered safe and biocompatible, chitosan has the ability to induce inflammatory reactions, which varies with the physical and chemical properties. We hypothesized that the previously reported zwitterionic chitosan (ZWC) derivative had relatively low pro-inflammatory potential because of the aqueous solubility and reduced amine content. To test this, we compared various chitosans with different aqueous solubilities or primary amine contents with respect to the intraperitoneal (i.p.) biocompatibility and the propensity to induce pro-inflammatory cytokine production from macrophages. ZWC was relatively well tolerated in ICR mice after i.p. administration and had no pro-inflammatory effect on naïve macrophages. Comparison with other chitosans indicates that these properties are mainly due to the aqueous solubility at neutral pH and relatively low molecular weight of ZWC. Interestingly, ZWC had a unique ability to suppress cytokine/chemokine production in macrophages challenged with lipopolysaccharide (LPS). This effect is likely due to the strong affinity of ZWC to LPS, which inactivates the pro-inflammatory function of LPS, and appears to be related to the reduced amine content. Our finding warrants further investigation of ZWC as a functional biomaterial.