Modified Prebiotic-Based "Shield" Armed Probiotics with Enhanced Resistance of Gastrointestinal Stresses and Prolonged Intestinal Retention for Synergistic Alleviation of Colitis

PPARγ/NF-κB axis contributes to cold-induced resolution of experimental colitis and preservation of intestinal barrier

BACKGROUND

Environmental stress is a significant contributor to the development of inflammatory bowel disease (IBD). The involvement of temperature stimulation in the development of IBD remains uncertain. Our preliminary statistical data suggest that the prevalence of IBD is slightly lower in colder regions compared to non-cold regions. The observation indicates that temperature changes may play a key role in the occurrence and progression of IBD. Here, we hypothesized that cold stress has a protective effect on IBD.

METHODS

The cold exposure model for mice was placed in a constant temperature and humidity chamber, maintained at a temperature of 4 °C. Colitis models were induced in the mice using TNBS or DSS. To promote the detection methods more clinically, fluorescence confocal endoscopy was used to observe the mucosal microcirculation status of the colon in the live model. Changes in the colonic wall of the mice were detected using 9.4 T Magnetic Resonance Imaging (MRI) imaging and in vivo fluorescence imaging. Hematoxylin and eosin (H&E) and Immunofluorescence (IF) staining confirmed the pathological alterations in the colons of sacrificed mice. Molecular changes at the protein level were assessed through Western blotting and Enzyme-Linked Immunosorbent Assay (ELISA) assays. RNA sequencing (RNA-seq) and metabolomics (n = 18) were jointly analyzed to investigate the biological changes in the colon of mice treated by cold exposure.

RESULTS

Cold exposure decreased the pathologic and disease activity index scores in a mouse model. Endomicroscopy revealed that cold exposure preserved colonic mucosal microcirculation, and 9.4 T MRI imaging revealed alleviation of intestinal wall thickness. In addition, the expression of the TLR4 and PP65 proteins was downregulated and epithelial cell junctions were strengthened after cold exposure. Intriguingly, we found that cold exposure reversed the decrease in ZO-1 and occludin protein levels in dextran sulfate sodium (DSS)- and trinitrobenzenesulfonic acid-induced colitis mouse models. Multi-omics analysis revealed the biological landscape of DSS-induced colitis under cold exposure and identified that the peroxisome proliferator-activated receptor (PPAR) signaling pathway mediates the effects of cold on colitis. Subsequent administration of rosiglitazone (PPAR agonist) enhanced the protective effect of cold exposure on colitis, whereas GW9662 (PPAR antagonist) administration mitigated these protective effects. Overall, cold exposure ameliorated the progression of mouse colitis through the PPARγ/NF-κB signaling axis and preserved the intestinal mucosal barrier.

CONCLUSION

Our study provides a mechanistic link between intestinal inflammation and cold exposure, providing a theoretical framework for understanding the differences in the prevalence of IBD between the colder regions and non-cold regions, and offering new insights into IBD therapy.

Melanin Nanoparticle-Modified Probiotics for Targeted Synergistic Therapy of Ulcerative Colitis

Ulcerative colitis (UC) is a recurrent chronic mucosal inflammation disease whose most significant pathological characteristics are intestinal inflammation and damaged mucosal barrier induced by reactive oxygen/nitrogen species, abnormal immune microenvironment, and intestinal microecological imbalance. Oral probiotics are a living therapy for intestinal diseases, but their clinical application is hindered by poor bacterial biological activity and insufficient intestinal retention. Here, we developed a targeted oral formulation, functionalized probiotic Lf@MPB, with Lactobacillus fermentum (Lf) as the core and modified melanin nanoparticles (MNPs) on its surface through a click reaction of tricarboxyphenylboronic acid for synergistic therapy of UC. In vitro experiments showed that Lf@MPB not only possessed strong free radical scavenging ability, reduced cellular mitochondrial polarization, and inhibited apoptosis but also significantly enhanced the viability of Lf probiotics in simulated gastrointestinal fluid. Fluorescence imaging in vivo revealed the high accumulation of Lf@MPB at the site of intestinal inflammation in dextran sulfate sodium-induced UC mice. Moreover, in vivo results demonstrated that Lf@MPB effectively alleviated oxidative stress and inflammatory response and restored the intestinal barrier. In addition, 16S rRNA gene sequencing verified that Lf@MPB could increase the abundance and diversity of intestinal microbial communities and optimize microbial composition to inhibit the progression of UC. This work combines effective antioxidant and anti-inflammatory strategies with the oral administration of functionalized probiotics to provide a promising alternative for UC treatment.

Responsively Degradable Nanoarmor-Assisted Super Resistance and Stable Colonization of Probiotics for Enhanced Inflammation-Targeted Delivery

Manipulation of the gut microbiota using oral microecological preparations has shown great promise in treating various inflammatory disorders. However, delivering these preparations while maintaining their disease-site specificity, stability, and therapeutic efficacy is highly challenging due to the dynamic changes associated with pathological microenvironments in the gastrointestinal tract. Herein, a superior armored probiotic with an inflammation-targeting capacity is developed to enhance the efficacy and timely action of bacterial therapy against inflammatory bowel disease (IBD). The coating strategy exhibits suitability for diverse probiotic strains and has negligible influence on bacterial viability. This study demonstrates that these armored probiotics have ultraresistance to extreme intraluminal conditions and stable mucoadhesive capacity. Notably, the HA-functionalized nanoarmor equips the probiotics with inflamed-site targetability through multiple interactions, thus enhancing their efficacy in IBD therapy. Moreover, timely "awakening" of ingested probiotics through the responsive transferrin-directed degradation of the nanoarmor at the site of inflammation is highly beneficial for bacterial therapy, which requires the bacterial cells to be fully functional. Given its easy preparation and favorable biocompatibility, the developed single-cell coating approach provides an effective strategy for the advanced delivery of probiotics for biomedical applications at the cellular level.

The emerging tumor microbe microenvironment: From delineation to multidisciplinary approach-based interventions

Intratumoral microbiota has become research hotspots, and emerges as a non-negligent new component of tumor microenvironments (TME), due to its powerful influence on tumor initiation, metastasis, immunosurveillance and prognosis despite in low-biomass. The accumulations of microbes, and their related components and metabolites within tumor tissues, endow TME with additional pluralistic features which are distinct from the conventional one. Therefore, it's definitely necessary to comprehensively delineate the sophisticated landscapes of tumor microbe microenvironment, as well as their functions and related underlying mechanisms. Herein, in this review, we focused on the fields of tumor microbe microenvironment, including the heterogeneity of intratumor microbiota in different types of tumors, the controversial roles of intratumoral microbiota, the basic features of tumor microbe microenvironment (i.e., pathogen-associated molecular patterns (PAMPs), typical microbial metabolites, autophagy, inflammation, multi-faceted immunomodulation and chemoresistance), as well as the multidisciplinary approach-based intervention of tumor microbiome for cancer therapy by applying wild-type or engineered live microbes, microbiota metabolites, antibiotics, synthetic biology and rationally designed biomaterials. We hope our work will provide valuable insight to deeply understand the interplay of cancer-immune-microbial, and facilitate the development of microbes-based tumor-specific treatments.

The single-cell modification strategies for probiotics delivery in inflammatory bowel disease: A review

Oral probiotic therapy has become an increasingly attractive method for treating various diseases, including intestinal barrier dysfunction, inflammatory bowel disease (IBD), and colorectal cancer due to its safety and convenience. However, only a few probiotics after oral gavage can survive the acidic and bile salt conditions of the gastrointestinal tract and colonize the colon to have a nutritional effect on the host. To address these challenges, encapsulation technology has been applied to protect probiotics from harsh gastrointestinal conditions, improve gut adhesion, and reduce immunogenicity. In addition, some of the functional polysaccharides are used to endow probiotics with exogenous functions as prebiotics. In this review, we systematically introduced the advancements of emerging single-cell modification strategies for probiotics in IBD applications. Additionally, we discussed the limitations and perspectives of single-cell modification strategies for probiotics. This review contributed to the development of probiotic delivery systems with higher therapeutic efficacy against colitis.

Construction and efficacy evaluation of chitosan-based nanoparticles for colon-targeted release of linoleic acid in rat pups

Long chain fatty acids in the colon play important roles in infant development. This study aimed to establish a colon-targeted long chain fatty acid release system in rat pups, with linoleic acid (LA) as the target model. LA-loaded chitosan nanoparticles (LA-CS NPs) synthesized via ionic crosslinkage showed spherical surface morphology and favorable encapsulation efficiency (84.96 %). In vivo distribution studies of LA-CS NPs demonstrated a significant increase in LA concentration in the colonic content after a 12-hour administration period. Additionally, oral administration of the delivery system (CS NPs: 18 μg/g/d, LA-CS NPs: 24 μg/g/d) exhibited no detrimental effects on the health of rat pups. In conclusion, this study presents a promising strategy for the targeted delivery of fatty acid to the colon in rat pups.

Exploring β-glucan as a micro-nano system for oral delivery targeted the colon

The critical role of oral colon-specific delivery systems (OCDDS) is important for delivering active agents to the colon and rectum specifically via the oral route. The use of micro/nanostructured OCDDS further improves drug stability, bioavailability, and retention time, leading to enhanced therapeutic effects. However, designing micro/nanoscale OCDDSs is challenging due to pH changes, enzymatic degradation, and systemic absorption and metabolism. Biodegradable natural polysaccharides are a promising solution to these problems, and β-glucan is one of the most promising natural polysaccharides due to its unique structural features, conformational flexibility, and specific processing properties. This review covers the diverse chemical structures of β-glucan, its benefits (biocompatibility, easy modification, and colon-specific degradation), and various β-glucan-based micro/nanosized OCDDSs, as well as their drawbacks. The potential of β-glucan offers exciting new opportunities for colon-specific drug delivery.

Triggerable Prodrug Nanocoating Enables On-Demand Activation of Microbial and Small-Molecular Therapeutics for Combination Treatment

The synergy of living microbial and small-molecular therapeutics has been widely explored for treating a variety of diseases, while current combination strategies often suffer from low bioavailability, heterogeneous spatiotemporal distribution, and premature drug release. Here, the use of a triggerable prodrug nanocoating is reported to enable the on-demand activation of microbial and small-molecular therapeutics for combination treatment. As a proof-of-concept study, a reactive oxygen species-responsive aromatic thioacetal linker is employed to prepare cationic chitosan-drug conjugates, which can form a nanocoating on the surface of living bacteria via electrostatic interaction. Following administration, the wrapped bacteria can be prevented from in vivo insults by the shielding effect of the nanocoating and be co-delivered with the conjugated drug in a spatiotemporally synchronous manner. Upon reaching the lesion site, the upgraded reactive oxygen species trigger in situ cleavage of the thioacetal linker, resulting in the release of the conjugated drug and a linker-derived therapeutic cinnamaldehyde. Meanwhile, a charge reversal achieved by the generation of negatively charged thiolated chitosan induces the dissociation of the nanocoating, leading to synchronous release of the living bacteria. The adequate activation of the combined therapeutics at the lesion site exhibits superior synergistic treatment efficacy, as demonstrated by an in vivo assessment using a mouse model of colitis. This work presents an appealing approach to combine living microbial and small-molecular therapeutics for advanced therapy of diseases.

Strategies for applying probiotics in the antibiotic management of Clostridioides difficile infection

The vital role of probiotics in the food field has been widely recognized, and at the same time, probiotics are gradually exhibiting surprising effects in the field of nutraceuticals, especially in regulating gut inflammation and the nutritional environment. As a dietary supplement in clinical nutrition, the coadministration of probiotics with antibiotics model has been applied to prevent intestinal infections caused by Clostridioides difficile. However, the mechanism behind this "bacteria-drug combination" model remains unclear. In particular, the selection of specific probiotic strains, the order of probiotics or antibiotics, and the time interval of coadministration are key issues that need to be further explored and clarified. Here, we focus on the issues mentioned above and give reasonable opinions, mainly including: (1) probiotics are safer and more effective when they intervene after antibiotics have been used; (2) the choice of the time interval between coadministration should be based on the metabolism of antibiotics in the host, differences in probiotic strains, the baseline ecological environment of the host's intestine, and the host immune level; in addition, the selection of the coadministration regime should also take into account factors such as the antibiotic sensitivity of probiotics and dosage of probiotics; and (3) by encapsulating probiotics, combining probiotics with prebiotics, and developing next-generation probiotics (NGPs) and postbiotic formulations, we can provide a more reasonable reference for this type of "bacteria-drug combination" model, and also provide targeted guidance for the application of probiotic dietary supplements in the antibiotic management of C. difficile infection.