Reactive oxygen species-responsive nanocarrier ameliorates murine colitis by intervening colonic innate and adaptive immune responses

Nanomedicine: The new trend and future of precision medicine for inflammatory bowel disease

ABSTRACT

Nanomedicine is an interdisciplinary area that utilizes nanoscience and technology in the realm of medicine. Rapid advances in science and technology have propelled the medical sector into a new era. The most commonly used nanotechnology in the field of medicine is nanoparticles. Due to their unique physicochemical properties, nanoparticles offer significant benefits of precision medicine for diseases such as inflammatory bowel disease that cannot be effectively treated by existing approaches. Nanomedicine has emerged as a highly active research field, with extensive scientific and technological studies being carried out, as well as growing international competition in the commercialization of this field. The accumulation of expertise in the key technologies relating to nanomedicine would provide strategic advantages in the development of cutting-edge medical techniques. This review presented a comprehensive analysis of the primary uses of nanoparticles in medicine, including recent advances in their application for the diagnosis and treatment of inflammatory bowel disease. Furthermore, we discussed the challenges and possibilities associated with the application of nanoparticles in clinical settings.

Bioresponsive and transformable coacervate actuated by intestinal peristalsis for targeted treatment of intestinal bleeding and inflammation

Developing an oral in situ-forming hydrogel that targets the inflamed intestine to suppress bleeding ulcers and alleviate intestinal inflammation is crucial for effectively treating ulcerative colitis (UC). Here, inspired by sandcastle worm adhesives, we proposed a water-immiscible coacervate (EMNs-gel) with a programmed coacervate-to-hydrogel transition at inflammatory sites composed of dopa-rich silk fibroin matrix containing embedded inflammation-responsive core-shell nanoparticles. Driven by intestinal peristalsis, the EMNs-gel can be actuated forward and immediately transform into a hydrogel once contacting with the inflamed intestine to yield strong tissue adhesion, resulting from matrix metalloproteinases (MMPs)-triggered release of Fe3+ from embedded nanoparticles and rearrangement of polymer network of EMNs-gel on inflamed intestine surfaces. Extensive in vitro experiments and in vivo UC models confirmed the preferential hydrogelation behavior of EMNs-gel to inflamed intestine surfaces, achieving highly effective hemostasis, and displaying an extended residence time ( > 48 h). This innovative EMNs-gel provides a non-invasive solution that accurately suppresses severe bleeding and improves intestinal homeostasis in UC, showcasing great potential for clinical applications.

Luteolin ameliorates ulcerative colitis in mice via reducing the depletion of NCR+ILC3 through Notch signaling pathway

The disorder of group 3 innate lymphoid cells (ILC3) subgroup, such as the predominance of NCR-ILC3 but the depletion of NCR+ILC3, is unfavorable to damaged intestinal barrier repair, which leads to the prolongations and obstinacy of ulcerative colitis (UC). Our previous studies had shown that luteolin promoted NCR-ILC3 differentitating into NCR+ILC3 to improving the depletion of NCR+ILC3 in UC mice, while the mechanism is unclear. This article aimed to explore the underlying mechanism of luteolin enhancing the proportion NCR+ILC3. UC mice model was established with 2% DSS and Notch signaling was blocked, then luteolin was used to intervene. The results showed that the effect of luteolin on ameliorating disease symptoms in UC mice, including inhibiting the weight loss, reducing the pathological damage of colon mucosa, etc., was diminished with blocking Notch signaling pathway. In addition, luteolin increased the proportion of NCR+ILC3, NCR+MNK3 and IL-22+ILC3, decreased intestinal permeability, promoted mucin secretion, and promoted ZO-1 and Occludin expression, the above effect of luteolin was neutralized by Notch inhibitor LY-411575. Luteolin activated the abnormally blocked Notch signaling pathway in UC mice. And molecular docking predicted the affinity of luteolin for RBPJ to be -7.5 kcal·mol-1 in mouse, respectively; the affinity of luteolin for Notch1 and RBPJ was respectively scored to be -6.4 kcal·mol-1 and -7.7 kcal·mol-1 homo sapiens. These results proved that luteolin is positive for enhancing the proportion of NCR+ILC3 via Notch signaling, and it provides a basis for targeting NCR+ILC3 for restoring intestinal barrier function to alleviating ulcerative colitis.

Enhancing the water dispersibility and intestinal targeting of pterostilbene using tannic acid-whey protein conjugates

In this study, three types of whey protein isolate (WPI)-tannic acid (TA) covalent conjugates (WPI-TA) were synthesized via alkaline treatment, free radical-induced method, and laccase induction. These conjugates were subsequently utilized in the antisolvent precipitation method to encapsulate pterostilbene (Pte). The structural and functional properties of these conjugates as carriers for intestinal-targeted Pte delivery were thoroughly evaluated. SDS-PAGE, total phenolic content measurement, grafting efficiency, and FT-IR analysis confirmed the successful formation of three distinct covalent conjugates. Among them, the laccase-induced WPI-TA conjugates exhibited the highest TA grafting efficiency. The particle size of this conjugate was measured at 115.25 nm with a PDI of 0.31. Upon encapsulation of Pte, this conjugate exhibited superior thermal stability, enhanced antioxidant properties, and sustained release within the gastrointestinal tract. The water solubility of Pte in these nanoparticles was found to be 361.19 times higher than that of free Pte, presenting a promising strategy for targeted intestinal delivery of Pte.

Multifunctional MnGA Nanozymes for the Treatment of Ulcerative Colitis by Reducing Intestinal Inflammation and Regulating the Intestinal Flora

In ulcerative colitis (UC), the formation of an inflammatory environment is due to the combined effects of excess production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), overproduction of proinflammatory cytokines, and disruption of immune system function. There are many kinds of traditional drugs for the clinical treatment of UC, but long-term drug use can cause toxic side effects and drug resistance and can also reduce patient compliance and other drawbacks. Hence, in light of the clinical challenges associated with UC, including the limitations of existing treatments, intense adverse reactions and the development of resistance to medications, no novel therapeutic agents that offer effective relief and maintain a high level of biosafety are urgently needed. Although many anti-inflammatory nanomedicines have been developed by researchers, the development of efficient and nontoxic nanomedicines is still a major challenge in clinical medicine. Using the natural product gallic acid and the metal compound manganese chloride, a highly effective and nontoxic multifunctional nanoenzyme was developed for the treatment of UC. Nanozymes can effectively eliminate ROS and RNS to reduce the inflammation of intestinal epithelial cells caused by oxidation, facilitate the restoration of the intestinal epithelial barrier through the upregulation of tight junction protein expression, and balance the intestinal microbiota to maintain the stability of the intestinal environment. Using a rodent model designed to mimic UC, we monitored body weight, colon length, the spleen index, and the degree of tissue damage and demonstrated that manganese gallate (MnGA) nanoparticles can reduce intestinal inflammation by clearing ROS and active nitrogen. Intestinal flora sequencing revealed that MnGA nanoparticles could regulate the intestinal flora, promote the growth of beneficial bacteria and decrease the levels of detrimental bacteria within the intestinal tract in a mouse model of UC. Thus, MnGA nanoparticles can maintain the balance of the intestinal flora. This study demonstrated that MnGA nanoparticles are excellent antioxidant and effective anti-inflammatory agents, have good biosafety, and can effectively treat UC.

Functional Ginger-Derived Extracellular Vesicles-Coated ZIF-8 Containing TNF-α siRNA for Ulcerative Colitis Therapy by Modulating Gut Microbiota

Tumor necrosis factor-α (TNF-α) plays a causal role in the pathogenesis of ulcerative colitis (UC), and anti-TNF-α siRNA shows great promise in UC therapy. However, delivering siRNA with site-targeted stability and therapeutic efficacy is still challenging due to the complex and dynamic intestinal microenvironment. Here, based on the functional plant-derived ginger extracellular vesicles (EVs) and porous ZIF-8 nanoparticles, we propose a novel TNF-α siRNA delivery strategy (EVs@ZIF-8@siRNA) for UC targeted therapy. Ginger EVs show strong colon and macrophage targeting, as well as robust resistance to acidic degradation in the stomach. Moreover, 6-shogaol in ginger-derived EVs displays anti-inflammatory effects, which enhance the treatment efficiency by cooperation with TNF-α siRNA. In vitro experiments reveal that ZIF-8 nanoparticles have high TNF-α siRNA loading capacity and promote siRNA escape from cellular lysosomes. In vivo experiments show that the TNF-α level is reduced more significantly in colonic tissue than other nontargeted inflammation related factors, showing a good targeting of this composite nanoparticle. Furthermore, gut microbiota sequencing results demonstrate that the nanoparticles can promote intestinal barrier repair by regulating the intestinal microbial balance and restoring the intestinal health of UC mice. Therefore, the developed EVs@ZIF-8@siRNA nanoparticles may represent a novel colon-targeted oral drug, providing a promising therapeutic strategy for UC therapy.

Recent advances in bacteria-based platforms for inflammatory bowel diseases treatment

Inflammatory bowel disease (IBD) is a recurring chronic inflammatory disease. Current treatment strategies are aimed at alleviating clinical symptoms and are associated with gastrointestinal or systemic adverse effects. New delivery strategies are needed for the treatment of IBD. Bacteria are promising biocarriers, which can produce drugs in situ and sense the gut in real time. Herein, we focus on recent studies of engineered bacteria used for IBD treatment and introduce the application of engineered bacteria in the diagnosis. On this basis, the current dilemmas and future developments of bacterial delivery systems are discussed.

Design strategies, advances and future perspectives of colon-targeted delivery systems for the treatment of inflammatory bowel disease

Inflammatory bowel diseases (IBD) significantly contribute to high mortality globally and negatively affect patients' qualifications of life. The gastrointestinal tract has unique anatomical characteristics and physiological environment limitations. Moreover, certain natural or synthetic anti-inflammatory drugs are associated with poor targeting, low drug accumulation at the lesion site, and other side effects, hindering them from exerting their therapeutic effects. Colon-targeted drug delivery systems represent attractive alternatives as novel carriers for IBD treatment. This review mainly discusses the treatment status of IBD, obstacles to drug delivery, design strategies of colon-targeted delivery systems, and perspectives on the existing complementary therapies. Moreover, based on recent reports, we summarized the therapeutic mechanism of colon-targeted drug delivery. Finally, we addressed the challenges and future directions to facilitate the exploitation of advanced nanomedicine for IBD therapy.

Enzyme/ROS dual-sensitive nanoplatform with on-demand Celastrol release capacity for enhanced ulcerative colitis therapy by ROS scavenging, microbiota rebalancing, inflammation alleviating

BACKGROUND

The oral administration of drugs for treating ulcerative colitis (UC) is hindered by several factors, including inadequate gastrointestinal stability, insufficient accumulation in colonic lesions, and uncontrolled drug release.

METHODS

A multiple sensitive nano-delivery system comprising β-cyclodextrin (CD) and 4-(hydroxymethyl)phenylboronic acid (PAPE) with enzyme/reactive oxygen species (ROS) sensitivity was developed to load celastrol (Cel) as a comprehensive treatment for UC.

RESULTS

Owing to the positive charge in the site of inflamed colonic mucosa, the negatively charged nanomedicine (Cel/NPs) could efficiently accumulate. Expectedly, Cel/NPs showed excellent localization ability to colon in vitro and in vivo tests. The elevated concentration of ROS and intestinal enzymes in the colon microenvironment quickly break the CD, resulting in Cel release partially to rebalance microbiota and recover the intestinal barrier. The accompanying cellular internalization of residual Cel/NPs, along with the high concentration of cellular ROS to trigger Cel burst release, could decrease the expression of inflammatory cytokines, inhibit colonic cell apoptosis, promote the macrophage polarization, scavenge ROS, and regulate the TLR4/NF-κB signaling pathway, which certified that Cel/NPs possessed a notably anti-UC therapy outcome.

CONCLUSIONS

We provide a promising strategy for addressing UC symptoms via an enzyme/ROS-sensitive oral platform capable of releasing drugs on demand.

Oral microsphere formulation of M2 macrophage-mimetic Janus nanomotor for targeted therapy of ulcerative colitis

Oral medication for ulcerative colitis (UC) is often hindered by challenges such as inadequate accumulation, limited penetration of mucus barriers, and the intricate task of mitigating excessive ROS and inflammatory cytokines. Here, we present a strategy involving sodium alginate microspheres (SAMs) incorporating M2 macrophage membrane (M2M)-coated Janus nanomotors (denominated as Motor@M2M) for targeted treatment of UC. SAM provides a protective barrier, ensuring that Motor@M2M withstands the harsh gastric milieu and exhibits controlled release. M2M enhances the targeting precision of nanomotors to inflammatory tissues and acts as a decoy for the neutralization of inflammatory cytokines. Catalytic decomposition of H2O2 by MnO2 in the oxidative microenvironment generates O2 bubbles, propelling Motor@M2M across the mucus barrier into inflamed colon tissues. Upon oral administration, Motor@M2M@SAM notably ameliorated UC severity, including inflammation mitigation, ROS scavenging, macrophage reprogramming, and restoration of the intestinal barrier and microbiota. Consequently, our investigation introduces a promising oral microsphere formulation of macrophage-biomimetic nanorobots, providing a promising approach for UC treatment.

A Spatially Stable Crystal-Particle Gel to Trap Patchouli Oil for Efficient Colonic Drug Delivery

Patchouli oil has exhibited remarkable efficacy in the treatment of colitis. However, its volatility and potential irritancy are often drawbacks when extensively used in clinical applications. Oil gel is a semisolid and thermoreversible system that has received extensive interest for its solubility enhancement, inhibition of bioactive component recrystallization, and the facilitation of controlled bioactive release. Therefore, we present a strategy to develop an oil gel formulation that addresses this multifaceted problem. Notably, a patchouli oil gel formulation was designed to solidify and trap patchouli oil into a spatially stable crystal-particle structure and colonic released delivery, which has an advantage of the stable structure and viscosity. The patchouli oil gel treatment of zebrafish with colitis improved goblet cells and decreased macrophages. Additionally, patchouli oil gel showed superior advantages for restoring the tissue barrier. Furthermore, our investigative efforts unveiled patchouli oil's influence on TRP channels, providing evidence for its potential role in mechanisms of anti-inflammatory action. While the journey continues, these preliminary revelations provide a robust foundation for considering the adoption of patchouli oil gel as a pragmatic intervention for managing colitis.

Inhibiting the cGAS-STING Pathway in Ulcerative Colitis with Programmable Micelles

Ulcerative colitis is a chronic condition in which a dysregulated immune response contributes to the acute intestinal inflammation of the colon. Current clinical therapies often exhibit limited efficacy and undesirable side effects. Here, programmable nanomicelles were designed for colitis treatment and loaded with RU.521, an inhibitor of the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway. STING-inhibiting micelles (SIMs) comprise hyaluronic acid-stearic acid conjugates and include a reactive oxygen species (ROS)-responsive thioketal linker. SIMs were designed to selectively accumulate at the site of inflammation and trigger drug release in the presence of ROS. Our in vitro studies in macrophages and in vivo studies in a murine model of colitis demonstrated that SIMs leverage HA-CD44 binding to target sites of inflammation. Oral delivery of SIMs to mice in both preventive and delayed therapeutic models ameliorated colitis's severity by reducing STING expression, suppressing the secretion of proinflammatory cytokines, enabling bodyweight recovery, protecting mice from colon shortening, and restoring colonic epithelium. In vivo end points combined with metabolomics identified key metabolites with a therapeutic role in reducing intestinal and mucosal inflammation. Our findings highlight the significance of programmable delivery platforms that downregulate inflammatory pathways at the intestinal mucosa for managing inflammatory bowel diseases.

Research advancements and perspectives of inflammatory bowel disease: A comprehensive review

Inflammatory bowel disease (IBD) is a chronic inflammatory disease with increasing incidence, such as Crohn's disease and ulcerative colitis. The accurate etiology and pathogenesis of IBD remain unclear, and it is generally believed that it is related to genetic susceptibility, gut microbiota, environmental factors, immunological abnormalities, and potentially other factors. Currently, the mainstream therapeutic drugs are amino salicylic acid agents, corticosteroids, immunomodulators, and biological agents, but the remission rates do not surpass 30-60% of patients in a real-life setting. As a consequence, there are many studies focusing on emerging drugs and bioactive ingredients that have higher efficacy and long-term safety for achieving complete deep healing. This article begins with a review of the latest, systematic, and credible summaries of the pathogenesis of IBD. In addition, we provide a summary of the current treatments and drugs for IBD. Finally, we focus on the therapeutic effects of emerging drugs such as microRNAs and lncRNAs, nanoparticles-mediated drugs and natural products on IBD and their mechanisms of action.

Marine sponge-derived alkaloid ameliorates DSS-induced IBD via inhibiting IL-6 expression through modulating JAK2-STAT3-SOCS3 pathway

Cyanogramide (AC14), a novel alkaloid, isolated from the fermentation broth of the marine-derived Actinoalloteichus cyanogriseus. However, the exact role of AC14 in inflammatory bowel disease (IBD) is poorly understood. Our results demonstrated that AC14 exhibited significant inhibition of IL-6 release in THP-1 cells and a "Caco-2/THP-1" coculture system after stimulation with LPS for 24 h. However, no significant effect on TNF-α production was observed. Furthermore, in 2.5 % DSS-induced colitis mice, AC14 treatment led to improvement in body weight, colon length, and intestine mucosal barrier integrity. AC14 also suppressed serum IL-6 production and modulated dysregulated microbiota in the mice. Mechanistically, AC14 was found to inhibit the phosphorylation of Janus kinase (JAK) 2 and signal transducers and activators of transcription (STAT) 3, while simultaneously elevating the expression of suppressor of cytokine signaling (SOCS) 3, both in vivo and in vitro. These findings suggest that AC14 exerts its suppressive effects on IL-6 production in DSS-induced IBD mice through the JAK2-STAT3-SOCS3 signaling pathway. Our study highlights the potential of AC14 as a therapeutic agent for the treatment of IBD.

Nanotechnology-enabled M2 macrophage polarization and ferroptosis inhibition for targeted inflammatory bowel disease treatment

Transforming macrophages into the anti-inflammatory M2 phenotype could markedly strengthen inflammatory bowel disease (IBD) treatment, which is considered as a promising strategy. However, the high ferroptosis sensitivity of M2 macrophages, which decreases their activity, is a major stumbling block to this strategy. Therefore, promoting M2 polarization while simultaneously inhibiting ferroptosis to tackle this challenge is indispensable. Herein, a calcium‑carbonate (CaCO3) mineralized liposome encapsulating a ferroptosis inhibitor (Fer-1) was developed (CaCO3@Lipo@Fer-1, CLF). The CaCO3 mineralized coating shields the liposomes to prevent the release of Fer-1 in circulation, while releasing Ca2+ in the acidic-inflammatory environment. This released Ca2+ promotes M2 polarization through the CaSR/AKT/β-catenin pathway. The subsequently released Fer-1 effectively upregulates GSH and GPX4, scavenges reactive oxygen species, and inhibits ferroptosis in M2 macrophages. In vivo, CLF improved the targeting efficiency of IBD lesions (about 4.17-fold) through the epithelial enhanced permeability and retention (eEPR) effect and enhanced IBD therapy by increasing the M2/M1 macrophage ratio and inhibiting ferroptosis. We demonstrate that the synergistic regulation of macrophage polarization and ferroptosis sensitivity by this mineralized nanoinhibitor is a viable strategy for IBD therapy.

An inulin-type fructan CP-A from Codonopsis pilosula attenuates experimental colitis in mice by promoting autophagy-mediated inactivation of NLRP3 inflammasome

Inulin-type fructan CP-A, a predominant polysaccharide in Codonopsis pilosula, demonstrates regulatory effects on immune activity and anti-inflammation. The efficacy of CP-A in treating ulcerative colitis (UC) is, however, not well-established. This study employed an in vitro lipopolysaccharide (LPS)-induced colonic epithelial cell model (NCM460) and an in vivo dextran sulfate sodium (DSS)-induced colitis mouse model to explore CP-A's protective effects against experimental colitis and its underlying mechanisms. We monitored the clinical symptoms in mice using various parameters: body weight, disease activity index (DAI), colon length, spleen weight, and histopathological scores. Additionally, molecular markers were assessed through enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence (IF), immunohistochemistry (IHC), and Western blotting assays. Results showed that CP-A significantly reduced reactive oxygen species (ROS), tumor necrosis factor-alpha (TNF-α), and interleukins (IL-6, IL-1β, IL-18) in LPS-induced cells while increasing IL-4 and IL-10 levels and enhancing the expression of Claudin-1, ZO-1, and occludin proteins in NCM460 cells. Correspondingly, in vivo findings revealed that CP-A administration markedly improved DAI, reduced colon shortening, and decreased the production of myeloperoxidase (MPO), malondialdehyde (MDA), ROS, IL-1β, IL-18, and NOD-like receptor protein 3 (NLRP3) inflammasome-associated genes/proteins in UC mice. CP-A treatment also elevated glutathione (GSH) and superoxide dismutase (SOD) levels, stimulated autophagy (LC3B, P62, Beclin-1, and ATG5), and reinforced Claudin-1 and ZO-1 expression, thereby aiding in intestinal epithelial barrier repair in colitis mice. Notably, the inhibition of autophagy via chloroquine (CQ) diminished CP-A's protective impact against colitis in vivo. These findings elucidate that CP-A's therapeutic effect on experimental colitis possibly involves mitigating intestinal inflammation through autophagy-mediated NLRP3 inflammasome inactivation. Consequently, inulin-type fructan CP-A emerges as a promising drug candidate for UC treatment.

pH Sensitive Quercetin Nanoparticles Ameliorate DSS-Induced Colitis in Mice by Colon-Specific Delivery

SCOPE

Ulcerative colitis (UC) is a classic inflammatory bowel disease (IBD) that represents a serious threat to human health. As a natural flavonoid with multiple biological activities, quercetin (QCT) suffers from low bioavailability through limitations in chemical stability. Here, the study investigates the regulatory effects of quercetin nanoparticles (QCT NPs) on dextran sulfate sodium (DSS) induced colitis mice.

METHODS AND RESULTS

Chitosan is modified to obtain N-succinyl chitosan (NSC) with superior water solubility. Nanoparticles composed of sodium alginate (SA) and NSC can encapsulate QCT after cross-linking, forming QCT NPs. In vitro drug release assays demonstrate the pH sensitivity of QCT NPs. Compared with free quercetin, QCT NPs have better therapeutic efficacy in modulating gut microbiota and its metabolites short chain fatty acid (SCFAs) to relieve DSS-induced colitis in mice, thereby alleviating colon inflammatory infiltration, increasing goblet cells density and mucus protein, ameliorating TNF-α, IL-1β, IL-6, IL-10, and Myeloperoxidase (MPO) levels, and recovering intestinal barrier integrity.

CONCLUSION

pH sensitive QCT nanoparticles can reduce inflammatory reaction, improve gut microbiota, and repair intestinal barrier by targeting colon, thus improving DSS induced colitis in mice, providing reference for the treatment of colitis.

Orally-administered nanomedicine systems targeting colon inflammation for the treatment of inflammatory bowel disease: latest advances

Inflammatory bowel disease (IBD) is a chronic and idiopathic condition that results in inflammation of the gastrointestinal tract, leading to conditions such as ulcerative colitis and Crohn's disease. Commonly used treatments for IBD include anti-inflammatory drugs, immunosuppressants, and antibiotics. Fecal microbiota transplantation is also being explored as a potential treatment method; however, these drugs may lead to systemic side effects. Oral administration is preferred for IBD treatment, but accurately locating the inflamed area in the colon is challenging due to multiple physiological barriers. Nanoparticle drug delivery systems possess unique physicochemical properties that enable precise delivery to the target site for IBD treatment, exploiting the increased permeability and retention effect of inflamed intestines. The first part of this review comprehensively introduces the pathophysiological environment of IBD, covering the gastrointestinal pH, various enzymes in the pathway, transport time, intestinal mucus, intestinal epithelium, intestinal immune cells, and intestinal microbiota. The second part focuses on the latest advances in the mechanism and strategies of targeted delivery using oral nanoparticle drug delivery systems for colitis-related fields. Finally, we present challenges and potential directions for future IBD treatment with the assistance of nanotechnology.

Dual-Targeted Nanoparticle-in-Microparticle System for Ulcerative Colitis Therapy

Conventional oral therapy for ulcerative colitis (UC) is associated with premature release or degradation of drugs in the harsh gastrointestinal environment, resulting in reduced therapeutic effectiveness. Consequently, the present study aims to develop a dual-targeted delivery system with a nanoparticle-in-microparticle (nano-in-micro) structure. The prepared Asiatic Acid-loaded delivery system (AA/CDM-BT-ALG) has pH-sensitive properties. Cellular uptake evaluation confirms that nanoparticles exhibit targeted absorption by macrophages and Caco-2 cells through mannose (Man) receptor and biotin-mediated endocytosis, respectively. Therefore, this mechanism effectively enhances intracellular drug concentration. Additionally, the biodistribution study conducted on the gastrointestinal tract of mice indicates that the colon of the microspheres group shows higher fluorescence intensity with longer duration than the other groups. This finding indicates that the microspheres exhibit selective accumulation in areas of colon inflammation. In vivo experiments in colitis mice showed that AA/CDM-BT-ALG significantly alleviates the histopathological characteristics of the colon, reduced neutrophil, and macrophage infiltration, and decreases pro-inflammatory cytokine expression. Furthermore, the effect of AA/CDM-BT-ALG on colitis is validated to be closely related to the TLR4/MyD88/NF-κB signaling pathway. The present findings suggest that the development of a dual-targeted delivery system is accomplished effectively, with the potential to serve as a drug-controlled release system for treating UC.

Orally Administrated Olsalazine-Loaded Multilayer Pectin/Chitosan/Alginate Composite Microspheres for Ulcerative Colitis Treatment

The pathogenesis of inflammatory bowel diseases (IBDs) including ulcerative colitis (UC) and Crohn's disease is extremely cloudy. Maintaining the level of remission lesions in colitis is the default treatment attitude at present. Epithelial barrier restoration is considered as the same important strategy as colonic targeted drug delivery in UC treatment. In this paper, we developed a multilayer natural polysaccharide microsphere (pectin/chitosan/alginate) with pH and enzyme dual sensitivity to reduce the loss of medication in the upper digestive tract and preferentially adhere to exposed epithelial cells in colonic tissues by electrostatic forces for efficiently targeted UC treatment. Olsalazine as an inflammatory drug was efficiently loaded in the chitosan layer and realized a colonic pH-responsive drug release. Furthermore, the multilayer microspheres exhibited excellent capability in suppressing harmful flora and a bio-adhesion effect to extend the duration of local medicine. In the in vivo anti-colitis study, the downregulated levels of pro-inflammatory factors and the increase of tight junction protein indicated the excellent anti-inflammation effect of the olsalazine-loaded microspheres. In summary, these results showed that the multilayer natural polysaccharide microspheres could be a powerful candidate in the targeted drug delivery system for UC therapy.