Regulated host-microbe interactions are a critical aspect of lifelong health. Colonic goblet cells protect from microorganisms via the generation of a mucus barrier structure. Bacteria-sensing sentinel goblet cells provide secondary protection by orchestrating mucus secretion when microbes breach the mucus barrier. Mucus deficiencies in germ-free mice implicate a role for the microbiota in programming barrier generation, but its natural ontogeny remains undefined. We now investigate the mucus barrier and sentinel goblet cell development in relation to postnatal colonization. Combined in vivo and ex vivo analyses demonstrate rapid and sequential microbiota-dependent development of these primary and secondary goblet cell protective functions, with dynamic changes in mucus processing dependent on innate immune signaling via MyD88 and development of functional sentinel goblet cells dependent on the NADPH/dual oxidase family member Duox2. Our findings identify new mechanisms of microbiota-goblet cell regulatory interaction and highlight the critical importance of the pre-weaning period for the normal development of protective systems that are key legislators of host-microbiota interaction.

Trimethylamine (TMA) metabolism comprises choline-containing compounds' metabolization, TMA production and trimethylamine N-oxide (TMAO) generation. However, the presence of numerous compounds in the carnitine and phosphatidylcholine (PC) pool compositions complicates profiling work significantly. This study is aimed at developing an efficient method for profiling TMA metabolic pathways, including quantifying known compounds and semi-quantifying the differential metabolites in the carnitine and PC pool compositions. Pseudo-targeted metabolomics is applicable for characterization. Firstly, multivariate statistics were performed to identify valuable metabolites (variable importance in the projection ＞1) from quality control biological samples. Given that TMA metabolism involved in host-gut microbiota interaction, co-metabolites were defined as the intersections of valuable metabolites from different biological samples (serum, liver, and intestinal contents) and further screened. Finally, alterations in TMA metabolism were observed in dextran sulfate sodium-induced colitis, with semi-quantitative analysis for excavated co-metabolites including 11 PCs, 6 lyso-phosphatidylcholines, and 2 acylcarnitines and quantitative analysis for 10 known metabolites. The findings revealed increased TMA production and accumulation of choline-containing compounds in the gut during ulcerative colitis exacerbation. Correspondingly, the circulating level of TMAO was elevated in the colitis group. A comprehensive understanding of TMA metabolism can contribute to disease differential diagnoses and potential mechanism studies.

Saccharomyces boulardii is a probiotic that can alleviate inflammation in the gut. In this study, a novel surface display system was developed by employing two different single-chain variable fragments (scFvs) against human tumor necrosis factor α as model anti-inflammatory proteins. We first optimized the expression levels of the scFvs by selecting strong constitutive promoters, of which expression cassettes were integrated into the S. boulardii chromosome using the CRISPR/Cas9-based genome editing system. As the signal peptide and anchoring motif are key factors affecting the display efficiency of target proteins, we next sought to find their optimal combination for the development of an efficient surface display system in S. boulardii. Among various combinations of signal peptide and anchoring motif, the engineered S. boulardii, which displayed scFvs using the SED1 signal peptide and DAN4 glycophosphatidylinositol domain (derived from Saccharomyces cerevisiae) as the signal peptide and anchoring motif, respectively, exhibited the highest display efficiency. Finally, the anti-inflammatory effects of the engineered S. boulardii strains displaying a high yield of scFvs, including a low disease activity index score, prevention of colon shortening, and reduction in pro-inflammatory cytokines, were validated using a colitis mouse model. Therefore, we believe that our approach has potential applications in the development of engineered S. boulardii displaying other valuable proteins.

Inflammatory bowel disease (IBD) is a chronic and relapsing disease of the gastrointestinal tract. At present, antioxidant therapy is a promising strategy for IBD treatment. Since low-molecular-weight antioxidants (e.g., 2,2,6,6-tetramethylpiperidin-N-oxyl (TEMPO)) have a short in vivo half-life and inadequate cellular uptake, researchers have focused on loading antioxidants into nanostructures for improving their antioxidant and anti-inflammatory activities. As we know, in situ self-assembly with the formation of nanostructures under intracellular specific stimuli is a convenient delivery strategy to enhance the accumulation and retention of molecules at target sites in vivo. Herein, we developed an in situ self-assembled TEMPO probe TPP-FFYp-O to improve the antioxidant and anti-inflammatory effects of TEMPO in IBD. Compared to the control probe TPP-O without a self-assembly moiety, TPP-FFYp-O could successfully self-assemble into nanoparticles (NPs) under alkaline phosphatase (ALP)-guided dephosphorylation, with significantly enhanced antioxidant capacity in vitro. Cell experiments confirmed that intracellular formation of NPs by TPP-FFYp-O could improve the antioxidant and anti-inflammatory abilities of TEMPO and alleviate cellular damage. Moreover, TPP-FFYp-O exhibited good biocompatibility in vivo and significantly relieved pathological injury and inflammatory factors in the colon tissues of an IBD model compared to TPP-O. We envision that the in situ self-assembly platform can be used to load various active molecules for more applications in the future.

Anxiety symptoms are commonly observed in individuals with inflammatory bowel disease (IBD), but the mechanistic link between IBD and comorbid anxiety remains incompletely understood. Our previous study revealed that vagal gut-brain signaling contributes to driving comorbid anxiety-like behaviors in dextran sulfate sodium (DSS)-induced colitis mice, but how vagus nerve senses and transmits information to the brain in response to changes in the colonic microenvironment following DSS treatment remain elusive. Here, we identify a critical contribution of pro-inflammatory CD86+ macrophages to activate gut-innervating vagal afferents and ultimately drive anxiety-like behaviors in DSS-treated mice. An increased number of F4/80+ macrophages accumulated closely with gut-innervating vagal afferent fibers following DSS treatment. Depletion of macrophages alleviated DSS-induced anxiety-like behaviors, whereas peripheral delivery of lipopolysaccharide-activated M1 macrophages promoted anxiety-like behaviors, which were prevented by bilateral vagal afferent ablation. Moreover, differential expression levels of anxiety-like behaviors were positively correlated with neuronal activity changes in the nucleus tractus solitarius, locus coeruleus, and basolateral amygdala. Finally, treatment with either anti-α4β7 integrin antagonist vedolizumab or neutralizing anti-interleukin-1β monoclonal antibody effectively alleviated DSS-induced anxiety-like behaviors. Collectively, these findings unravel a mechanism of macrophage-to-vagus nerve communication via cytokine signaling responsible for comorbid anxiety associated with experimental colitis and suggest that pro-inflammatory CD86+ macrophages may represent a potential therapeutic target for psychological comorbidities in patients with IBD.

Under insulin-resistant conditions, such as obesity, pancreatic β cells adaptively proliferate and secrete more insulin to prevent blood glucose elevation. We previously reported hepatic ERK activation during obesity development to stimulate a neuronal relay system, consisting of afferent splanchnic nerves from the liver and efferent vagal nerves to the pancreas, thereby triggering adaptive β cell proliferation. However, the mechanism linking obesity with the interorgan system originating in hepatic ERK activation remains unclear. Herein, we clarified that colonic inflammation promotes β cell proliferation through this interorgan system from the liver to the pancreas. First, dextran sodium sulfate (DSS) treatment induced colonic inflammation and hepatic ERK activation as well as β cell proliferation, all of which were suppressed by blockades of the neuronal relay system by several approaches. In addition, treatment with anti-lymphocyte Peyer's patch adhesion molecule-1 (anti-LPAM1) antibody suppressed β cell proliferation induced by DSS treatment. Importantly, high-fat diet (HFD) feeding also elicited colonic inflammation, and its inhibition by anti-LPAM1 antibody administration suppressed hepatic ERK activation and β cell proliferation induced by HFD. Thus, colonic inflammation triggers adaptive β cell proliferation via the interorgan mechanism originating in hepatic ERK activation. The present study revealed a potentially novel role of the gastrointestinal tract in the maintenance of β cell regulation.

Intestinal barrier damage is frequently caused by antibiotic therapy, potentially leading to bacterial translocation and toxin leakage, which triggers inflammation and increases the risk of various diseases. In this study, Tamarind seed polysaccharides (TSP) with different molecular weights were administered to mice during the recovery phase from clindamycin-induced intestinal barrier damage. The results indicated that TSP restored the shortened colon length, reduced the enlarged cecum index, and decreased the elevated level of inflammatory infiltration. Biochemical testing revealed that TSP decreased the levels of intestinal permeability biomarkers and inflammatory factors that were elevated by clindamycin treatment. Transcriptomics and non-targeted metabolomics analyses respectively uncovered changes in colon gene expression and fecal metabolites. The joint analysis of these omics data identified critical pathways, including arachidonic acid metabolism, retinol metabolism, and steroid hormone biosynthesis. These findings suggest that TSP could be a promising dietary supplement for protecting the intestinal barrier and alleviating inflammation.

The aim of this study was to investigate the therapeutic effect of API on UC via the regulation of PAMP-MRGPRX2-mediated mast cells (MCs) degranulation.

The pro-inflammatory positive feedback loop mediated by Mas-related G-protein-coupled receptor X2 (MRGPRX2) and its endogenous ligand, PAMP-12, is associated with ulcerative colitis (UC) progression. However, the therapeutic strategies that target MRGPRX2 in the treatment of UC are less reported. Apigenin (API), a natural flavonoid, can relieve inflammation.

A dextran sodium sulfate (DSS)-induced mouse UC model was used to elucidate the therapeutic effects of API. Animal behavior assessment, serological assays, and histological analysis were performed in wild-type (WT) and MC MrgprB2-conditional knockout (CKO) mouse model. mRNA sequencing analysis, PCR, ELISA, and western blotting were performed in vitro and in vivo to elucidate the mechanism underlying the effect of API by a PAMP-12 triggered MC degranulation model.

MC degranulation via MrgprB2 was critical for the persistence of inflammation in colitis. API attenuated colonic tissue damage, splenomegaly, and myeloperoxidase (MPO) activity in the colonic tissues. It also ameliorated colonic crypt structure damage and inflammatory cell infiltration. Moreover, API suppressed MCs degranulation, and the level of carboxypeptidases A3 (CPA3), in DSS-induced colitis, thereby blocking the pro-inflammatory positive feedback loop induced by PAMP-MrgprB2. Lastly, API effectively inhibited PAMP-12-triggered mast cell degranulation by regulating Akt1/XBP-1S/CHOP/TXNIP and NF-κB/IL-1β signaling pathways.

API alleviates inflammatory symptoms in UC by suppressing PAMP-MRGPRX2/B2 mediated MC sustained degranulation feedback loop.

Crohn's disease (CD) and ulcerative colitis (UC) are the two major entities of inflammatory bowel disease (IBD). These disorders are known for their relapsing disease course and severe gastrointestinal symptoms including pain, diarrhoea and bloody stool. Accumulating evidence suggests that IBD is not only restricted to the gastrointestinal tract and that disease processes are able to reach distant organs including the brain. In fact, up to 35 % of IBD patients also suffer from neuropsychiatric disorders such as generalized anxiety disorder and major depressive disorder. Emerging research in this area indicates that in many cases these neuropsychiatric disorders are a secondary condition as a consequence of the disturbed communication between the gut and the brain via the microbiota-gut-brain axis. In this review, we summarise the current knowledge on IBD-associated neuropsychiatric disorders. We examine the role of different pathways of the microbiota-gut-brain axis in the development of CNS disorders highlighting altered neural, immunological, humoral and microbial communication. Finally, we discuss emerging therapies targeting the microbiota-gut-brain axis to alleviate IBD and neuropsychiatric symptoms including faecal microbiota transplantation, psychobiotics, microbial metabolites and vagus nerve stimulation.

Forsythiaside A (FA), the primary compound found in Forsythia suspensa (Thunb.) Vahl, has demonstrated various pharmacological effects, but its impact on ulcerative colitis (UC) is underexplored. Our study examined the distribution of FA in different parts of the gastrointestinal tracts and its therapeutic effects on UC, along with the underlying mechanisms. The levels of FA in gastrointestinal tracts and plasma were analyzed by high-performance liquid chromatography; mice were given dextran sulfate sodium in drinking water to develop the UC model. The UC mice were treated with FA (15, 30, and 60 mg/kg) for 10 days. FA showed relatively high concentration retention in the colon within 4 h. The treatment of FA improved body weight loss, diarrhea, rectal bleeding, colon shortening, and histological damage in UC mice. It also increased the expression of the tight junction protein and decreased inflammatory cytokines in the colon. The microbiota analysis using 16S rRNA sequencing revealed that FA could alleviate gut dysbiosis in colitis mice. Of importance, we found FA resulted in a reduction of neutrophil extracellular traps formation (NETosis) and inhibited peptidyl arginine deiminase 4 (PAD4) in colon tissue of colitis mice. In cultured neutrophils, FA pretreatment led to a suppression of PAD4 expression and NETosis induced by PMA. These findings suggest that FA can be retained in the colon and may alleviate UC by inhibiting NETs formation, indicating its potential for preventing or treating UC.

Whereas intestinal epithelial barrier dysfunction is implicated in inflammatory bowel disease (IBD), the underlying mechanisms remain elusive. Tumor necrosis factor α stimulated gene 6 (TSG-6) is a secretory protein with anti-inflammatory properties. Our previous research demonstrated TSG-6 can relieve intestinal inflammation and mucosal damage. However, the underlying mechanism and targets remain unclear. This research sought to explore how TSG-6 regulates the intestinal epithelial barrier and its mechanistic role in experimental colitis.

IBD mouse model was generated using dextran sodium sulfate (DSS), with or without intraperitoneal injection of TSG-6(100 µg/kg or 200 µg/kg). The effects of TSG-6 on colonic inflammation and intestinal barrier function were investigated. Label-free quantitative proteomic analysis was performed on intestinal samples to explore the mechanism and therapeutic target of TSG-6. Molecular interactions were determined by co-immunoprecipitation (Co-IP) and immunofluorescence colocalization.

TSG-6 treatment significantly attenuated DSS-induced colitis symptoms and inflammatory cell infiltration. Microarray analysis revealed that TSG-6 decreased pro-inflammatory cytokine levels in colon tissue. TSG-6 restored the intestinal epithelial barrier through the promotion of intestinal epithelial cells (IECs) proliferation and mitigation of tight junctions (TJs) damage. Mechanistically, TSG-6 promoted tuft cells differentiation and increased interleukin-25 (IL-25) levels by directly binding to Pou class 2 homeobox 3(Pou2f3) and up-regulating its expression in the gut.

This study demonstrated TSG-6 as a positive regulator of tuft cells differentiation by interacting with Pou2f3, and the effectiveness of exogenous TSG-6 treatment on maintaining intestinal barrier integrity showed a promising potential for its clinical application.

IBD is a chronic inflammatory condition driven by complex genetic and immune interactions, yet preclinical models often fail to fully recapitulate all aspects of the human disease. A systematic comparison of commonly used IBD models is essential to identify conserved molecular mechanisms and improve translational relevance.

We performed a multimodel transcriptomic analysis of 13 widely used IBD mouse models to uncover coregulatory gene networks conserved between preclinical colitis/ileitis and human IBD and to define model-specific and conserved cellular, subcellular and molecular signatures.

We employed comparative transcriptomic analyses with curated and a priori statistical correlative methods between mouse models versus IBD patient datasets at both bulk and single-cell levels.

We identify IBD-related pathways, ontologies and cellular compositions that are translatable between mouse models and patient cohorts. We further describe a conserved core inflammatory signature of IBD-associated genes governing T-cell homing, innate immunity and epithelial barrier that translates into the new mouse gut Molecular Inflammation Score (mMIS). Moreover, specific mouse IBD models have distinct signatures for B-cell, T-cell and enteric neurons. We discover that transcriptomic relatedness of models is a function of the mode of induction, not the canonical immunotype (Th1/Th2/Th17). Moreover, the model compendium database is made available as a web explorer (http://trr241.hosting.rrze.uni-erlangen.de/SEPIA/).

This integrated multimodel approach provides a framework for systematically assessing the molecular landscape of intestinal inflammation. Our findings reveal conserved inflammatory circuits, refine model selection, offering a valuable resource for the IBD research community.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease with limited therapeutic options, particularly for moderate-to-severe cases. The present study evaluated the therapeutic potential of Sishen Pill (SSP) through Activating Transcription Factor 3 (ATF3).

Colonic biopsy samples were collected from 11 UC patients and 6 healthy controls (HCs). A murine colitis model was established using dextran sodium sulfate (DSS) and treated with SSP. The therapeutic efficacy of SSP was evaluated by measuring body weight, colonic length, and inflammatory markers in wild-type (WT) mice. Transcriptomic analysis revealed differentially expressed genes in colonic tissues following Atf3 knockout. Western blotting, immunofluorescence, immunohistochemical, and Luminex assays were conducted to assess the effect of SSP on Neutrophil Extracellular Traps (NETs) formation and ATF3 signaling.

ATF3 expression was significantly reduced in the inflamed mucosa of UC patients, correlating with disease severity. UC tissues also exhibited increased spontaneous NETs formation. In DSS-induced colitis mice, ATF3 expression was similarly reduced, whereas SSP treatment upregulated ATF3, mitigated weight loss, reduced colonic shortening, alleviated histopathological damage, and lowered inflammatory cytokine levels. Atf3 knockout mice (Atf3-/-) displayed more severe DSS-induced colitis with enhanced immune response as compared to control littermates (Atf3+/+). Transcriptomic analyses revealed that SSP downregulated key genes involved in NETs formation pathways, tumor necrosis factor (TNF) and cytokine-cytokine receptor signaling. Experimental validation confirmed that SSP reduced the levels of NETs-related proteins [Myeloperoxidase (MPO), Peptidylarginine Deiminase 4 (PAD4), Lymphocyte Antigen 6 Complex, G (Ly6G), Neutrophil Elastase (NE), Citrullinated Histone H3 (CitH3)] in the colorectal tissue of colitis mice. It also down-regulated TNF pathway-related proteins [Phosphorylated Extracellular Signal-Regulated Kinase (p-ERK), Matrix Metalloproteinase 9 (MMP9)]. Furthermore, SSP intervention reduced pro-inflammatory factors [interleukin (IL)-6, IL1β, Granulocyte Colony-Stimulating Factor (G-CSF) and TNF-α] and decreased CXCL1/CXCR2 axis factors, including CXCL1 protein levels and diminished CXCR2+MPO+ positive expressed cells. Importantly, these beneficial effects of SSP were ATF3-dependent, as SSP did not exert its effects in Atf3-/- mice.

SSP ameliorates colitic mice through multiple mechanisms, including the inhibition of NETs formation, attenuation of inflammatory responses, and suppression of CXCL1/CXCR2-mediated inflammation, all via modulation of ATF3 expression. These findings support the potential of SSP as a promising adjunctive therapy for UC and underscore the therapeutic potential of targeting ATF3 in future treatment strategies.

Abnormalities in inflammation resolution function are intimately linked to chronic inflammation, and proresolution therapies may offer novel opportunities for IBD treatment. Developmental endothelial locus 1 (DEL-1), a natural modulator of tissue immunity and inflammation resolution, has not been studied in IBD.

We aimed to investigate the expression and functions of DEL-1 in IBD.

Assessment of DEL-1 expression in patients, murine models, and cellular levels. To explore the effects of DEL-1 in the acute and recovery phases of inflammation, overexpression plasmids, adeno-associated viruses for DEL-1 knockdown, and DEL-1-Fc fusion proteins were administered to cells and mice. Additionally, the potential mechanism of DEL-1 in IBD was demonstrated using flow cytometry, RNA-Seq, ChIP, dual-luciferase reporter assays and 16S rRNA.

DEL-1 levels were significantly reduced in IBD patients, colitis mice and macrophages, while the levels increased with inflammation to resolve. Transfection with DEL-1 overexpression plasmid or DEL-1-Fc intervention reduces levels of inflammatory cytokines in both phases and upregulates reparative gene levels in the recovery phase. DEL-1 knockdown inhibits inflammation resolution of colitis. Mechanistically, we demonstrated that DEL-1 inhibits Cmpk2-dependent mtDNA synthesis, thereby inhibiting the cGAS-STING pathway to ameliorate intestinal inflammation. Moreover, DEL-1 promotes reparative macrophage transition in the repair model of colitis. Spi1 was identified as a transcription factor that regulates Cmpk2 and the reparative gene Il10. Intervention with overexpression plasmid of Spi1 or Cmpk2 or the STING agonist DMXAA reverses the effects of DEL-1. In parallel, DEL-1 also inhibits neutrophil recruitment, repairs the intestinal barrier, and improves intestinal microbiota dysbiosis.

We report the first demonstration that DEL-1 significantly ameliorates colonic inflammation in colitis mice. Our findings elucidate a novel mechanism wherein DEL-1 exerts its protective effects by suppressing the Cmpk2-cGAS-STING pathway and promoting reparative macrophage transition. These results collectively position DEL-1 as a promising therapeutic avenue for IBD.

The interplay between diet, host genetics, microbiota, and immune system has a key role in the pathogenesis of inflammatory bowel disease (IBD). Although the causal pathophysiological mechanisms remain unknown, numerous dietary nutrients have been shown to regulate gut mucosal immune function, being effective in influencing innate or adaptive immunity. Here, we proved that transient receptor potential melastatin 8 (TRPM8), a non-selective cation channel, mediates LPS- evoked Ca2+ influx in macrophages leading to their activation. Additionally, we showed that TRPM8 is selectively blocked by the dietary flavonoid luteolin, which induced a pro-tolerogenic phenotype in pro-inflammatory macrophages. Accordingly, genetic deletion of Trpm8 in macrophages caused a deficit in the activation of pro-inflammatory metabolic and transcriptional reprogramming, leading to reduced production of key pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α. The TRPM8 anti-inflammatory effect was found to be dependent on lactate which in turn induces IL-10 gene expression. Adoptive transfer of TRPM8-deficient bone marrow in wild-type mice improved intestinal inflammation in a model of colitis. Accordingly, oral administration of luteolin protected mice against colitis through an impairment in the innate immune response. Our study reveals the potential of targeting TRPM8 through specific nutrient interventions to regulate immune function in sub-clinical scenarios or to treat inflammatory diseases, primarily driven by chronic immune responses, such as IBD.

Ulcerative colitis is a chronic non-specific inflammatory disease of the intestine that significantly impacts patient quality of life. This study introduces a OF/CC/SM hydrogel containing oxidized fucoidan (OF), carboxymethyl chitosan (CC), and silk sericin-stabilized mesalazine (SM), designed for rectal administration to target mesalazine delivery specifically to the colon. The OF/CC/SM hydrogel demonstrated good biocompatibility (cell compatibility > 99 %), injectability, and adhesion strength, ensuring effective mesalazine retention and release. In vitro assays confirmed the hydrogel's antioxidant and anti-inflammatory properties, which were further validated in vivo using a mouse model of ulcerative colitis. Rectal administration of OF/CC/SM hydrogel significantly relieved weight loss, lowered disease activity index scores, and prevented intestinal shortening associated with dextran sulfate sodium (DSS) treatment. The hydrogel decreased the expression of proinflammatory cytokines (e.g., tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β)), while normalized the level of biomarkers (e.g., inducible nitric oxide synthase (iNOS), myeloperoxidase (MPO), catalase (CAT), and malondialdehyde (MDA)). Additionally, the OF/CC/SM hydrogel modulated the gut microbiota, increasing beneficial bacteria while decreasing potentially harmful species. Histopathological analysis revealed a reduction in inflammatory infiltration and improved mucosal architecture. Additionally, in vivo imaging studies confirmed sustained presence of OF/CC/SM hydrogel in the intestines following rectal administration, highlighting its potential for enhanced therapeutic efficacy in treating ulcerative colitis.

Inflammatory bowel disease (IBD) remains a pressing global health challenge, necessitating novel therapeutic strategies. Succinate, a metabolite known for its role in type 2 immunity and tuft cell activation in the small intestine, presents its potential in IBD management. However, its impact on colonic inflammation has not been explored. Here, we demonstrate that succinate administration induces a type 2 immune response, significantly alleviating dextran sulfate sodium (DSS)-induced colonic inflammation. Succinate enhances antibacterial capacity, reduces intestinal permeability, and reshapes the colonic cytokine milieu. Mechanistically, succinate promotes myeloid cell expansion in peripheral blood, mesenteric lymph nodes, and the colonic lamina propria. The protective effects of succinate were abolished in Ccr2-/- mice, confirming the role of monocyte recruitment, but persisted in Rag1-/- mice, indicating independence from adaptive immunity. Adoptive transfer of monocytes from succinate-treated donors mitigated intestinal inflammation in recipient mice. Transcriptomic analysis revealed heightened expression of Il1b and Il6, and higher lactate production in monocytes upon lipopolysaccharide (LPS) stimulation, highlighting a reprogrammed pro-inflammatory trained immunity phenotype. Finally, we identify the IL-4Rα/Hif-1α axis is critical for succinate-mediated protection. These findings reveal the ability of succinate to reprogram monocytes into protective intestinal macrophages via induction of type 2 response, restoring homeostasis through enhanced barrier function and immune modulation. Our study positions thus uncover succinate as a promising therapeutic candidate for IBD.

Structural variations (SVs) have significant effects on microbial phenotypes. The underlying mechanism of functional changes caused by gut microbial SVs in the development of ulcerative colitis (UC) need further investigation.

We performed long-read (Oxford Nanopore Technology-based) and short-read (Illumina-based) metagenomic sequencing on stool samples from 93 patients with UC and 100 healthy controls (HCs) and analyzed microbial SVs. A total of 648 Escherichia coli strains from fecal samples of patients with UC (UC-strains) and HCs (HC-strains) were isolated. SV-associated scrK gene deletion was verified via whole-genome sequencing or targeted polymerase chain reaction. Then, representative UC-strains, HC-strains, and scrK-knockout E coli were used for the in vitro and in vivo experiments to investigate the effects of specific SVs in E coli on fructose utilization ability and colitis.

E coli in UC with the highest fold change had SV-affected functional differences on fructose metabolism to that of HCs. The fructose utilization gene deletion was common in UC-strains, ostensibly reducing fructose utilization in vitro and leading to fructose-dependent aggravation of colitis in murine models. UC-strains and HC-strains induced comparable colitis under low fructose. However, high fructose exacerbated colitis severity exclusively in UC-strain-colonized mice, with elevated intestinal fructose residues, significant microbiome/metabolome changes, increased inflammation, and gut barrier disruption. These changes were mechanistically dependent on the deletion of the fructose utilization gene scrK.

SV-caused difference in fructose utilization and proinflammatory properties in E coli from patients with UC influence the development of UC, emphasizing the importance of fine-scale metagenomic studies in disease.

Exochorda racemosa is a member of the genus Exochorda in the Rosaceae family. Its tender leaves and buds are favored as a unique wild vegetable by people in central China.

This study systematically evaluated the pharmacological safety and anti-inflammatory efficacy of E. racemosa extracts, with concurrent identification and characterization of their primary bioactive components.

The chemical composition of E. racemosa extract (ERE) was analyzed using HPLC and LC-MS techniques. The safety and in vivo anti-inflammatory effects of ERE were evaluated using the maximum tolerated dose (MTD) in ICR mice and a dextran sodium sulfate-induced ulcerative colitis model in C57BL/6 J mice.

HPLC and LC-MS analyses revealed that ERE contained abundant flavonoid active ingredients. MTD study confirmed that ERE exhibited good safety. The symptoms of persistent weight loss, DAI, and shortened colon length in UC mice were suppressed by ERE. Pathological damage in colon tissues was attenuated by ERE, with a considerable reduction in histopathological scores and a substantial increase in the number of goblet cells. The levels of IL-6, IL-1β, and TNF-α in serum were significantly decreased following ERE treatment. Moreover, nitric oxide (NO) levels and myeloperoxidase (MPO) activity in colon tissues decreased, whereas glutathione (GSH) levels and superoxide dismutase (SOD) activity in colon tissues increased after ERE treatment. Furthermore, ERE could regulate the intestinal microbial composition and maintain intestinal flora homeostasis, thereby inhibiting inflammatory responses.

ERE exhibited a favorable safety profile and alleviated UC through multiple mechanisms. It is expected to serve as a promising low-toxicity natural product for adjuvant treatment in UC.

Inflammatory bowel disease is a long-standing inflammatory disorder that influences the intestinal tract. The intent of this research is to explore whether the relative abundance of Akkermansia muciniphila is related to the IL6/STAT3 pathway and the fundamental molecular mechanisms of A. muciniphila on a trinitrobenzene sulfonic acid (TNBS)-induced enteritis mouse model, including the expression of inflammatory cytokines and proteins in the IL6/STAT3 signaling pathway.

The association between the A. muciniphila and IL6/STAT3 was investigated by using mucosal biopsies and fecal samples. TNBS-induced colitis mouse models were performed to elucidate the underlying mechanisms. The alteration of intestinal microbiota was organized by 16s rRNA sequencing.

In Crohn's disease patients, the level of STAT3 and IL-6 presented a negative relationship with A. muciniphila. The expression of IL-6, p-STAT3, and STAT3 was downregulated in A.m+TNBS group, indicating A. muciniphila may inhibit the IL6/STAT3 pathway in TNBS-induced enteritis in vivo. To investigate the potential defensive role of A. muciniphila supplementation in vivo with TNBS-induced enteritis, 16S rRNA sequencing was performed to analyze changes in the intestinal microbiota composition. The results revealed a marked increase in microbial diversity and abundance within the A. muciniphila-treated group, suggesting a beneficial modulation of the gut microbiome associated with the supplementation.

Our findings declared that A. muciniphila supplementation alleviates gastrointestinal inflammation through IL-6/STAT3 signaling pathway. This protective effect was mediated by the downregulation of the IL-6 and STAT3, highlighting a potential mechanism by which A. muciniphila modulates inflammatory responses. This work disclosed that A. muciniphila demonstrates a defensive influence against TNBS-induced enteritis in vivo, proposing it qualified as a unique therapeutic focusing on modulating IL-6, STAT3, or p-STAT3 in the treatment of colitis.

Oral administration of probiotics holds promise for alleviating ulcerative colitis (UC), yet their efficacy is inevitably compromised by the hostile gastrointestinal (GI) environment. Here, we devised a strategy by coating β-glucan (GN) prebiotic onto the surface of Lactobacillus plantarum (Lp) probiotic at the single-cell level (Lp@CGN) based on bioorthogonal chemistry in a layer-by-layer manner. This achieved to form a firm, dense, and multifunctional GN-based "armor" with advances of superior protective properties, colon-targeted degradation, and prebiotic benefits. Under the protection of the prebiotic-based "armor", Lp@CGN exhibited a notable 276-fold increase in the survival rate compared to naïve Lp after exposure to whole GI conditions. Upon reaching the colon, the "armor" was metabolized into short-chain fatty acids (SCFAs) by gut microbiota, facilitating the timely release of Lp within colon, thereby achieving a synergistic treatment effect due to sustained SCFAs generation and Lp liberation. As a result, oral administration of Lp@CGN efficiently realized the alleviation of UC in both preventative and therapeutic models through restoring intestinal mucosal barriers, positively regulating inflammatory cytokines, renovating the dysbiosis of gut microbiota, and promoting SCFAs production. In sum, our strategy marks the reconstruction of probiotics with chemical tools, offering useful insights into powering probiotics for disease treatment.

Aesculus wilsonii Rehd.'s dried mature seeds are the source of escin, a significant triterpenoid saponin. Aesculus wilsonii Rehd was first mentioned in the Compendium of Materia Medica, according to the Chinese Pharmacopoeia. It possesses the effectiveness of anti-inflammatory as well as treating gastrointestinal disorders. Escin Ia is the primary active component of escin, exhibiting significant antioxidant and anti-inflammatory properties. An increasing number of studies have demonstrated that escin exhibits a broad spectrum of pharmacological activities beneficial for the protection against gastrointestinal diseases.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) that can be managed through pharmacological treatment; however, it features a high recurrence rate as well as propensity for complications. Therefore, reducing the rate of recurrence and improving the recurrence symptoms should be the primary focus of clinical prevention and treatment. Therefore, this research aims to study the effects of escin Ia on inflammation as well as oxidative stress in mice with chronic UC and to explain the molecular mechanisms underlying its potential to improve recurrent symptoms in UC mice.

A mouse model of colitis produced via dextran sodium sulfate (DSS) was developed for in vivo studies. A model of inflammation was created in vitro using caco-2 cells that were generated by lipopolysaccharide (LPS). Through the observation of colitis symptoms and histological morphology in mice, the protective effect of escin Ia against colitis was ascertained. The enzyme-linked immunosorbent assay (ELISA) and biochemical kits were then harnessed to measure the levels of oxidative stress markers as well as inflammatory factors. Additionally, to identify the possible target and molecular mechanism of escin Ia, qRT-PCR and western blotting, immunofluorescence, molecular docking, and molecular dynamics modeling were employed.

We demonstrated that escin Ia remarkably improved the colitis symptoms as well as histological features of DSS-treated mice, lowered the levels of proinflammatory cytokines as well as oxidative stress biomarkers, and subsequently restored the permeability of the intestinal mucosa. Additionally, high expression of LOXL2 significantly reduced the protective effects of escin Ia in both inflamed mice and Caco-2 cells. Furthermore, escin Ia exhibited a strong binding affinity and notable stability with LOXL2.

Escin Ia inhibits inflammation and oxidative stress through the LOXL2/MMP-9 pathway, thereby restoring intestinal mucosal barrier function. Improved recurrent symptoms in mice with enteritis.

Inspired by the survival strategies of pyomelanin-producing microbes, we synthesize pyomelanin nanoparticles (PMNPs) from homogentisic acid- γ-lactone via auto-oxidation and investigate their biomedical potential. PMNPs possess distinct physicochemical properties, including reactive oxygen species scavenging and microenvironment-responsive self-disassembly. Under intestinal conditions, PMNPs self-disassemble and penetrate the nanoscale pores of the mucin layer. In an inflammatory bowel disease model, orally administered PMNPs withstand gastric acidity and, in their solubilized form, interact with macrophages and epithelial cells. They significantly reduce reactive oxygen species levels, exert anti-inflammatory effects, and restore gut microbiota composition. Compared to conventional nanoparticles and 5-aminosalicylic acid, PMNPs exhibit greater therapeutic efficacy. Clinical symptoms and intestinal inflammation are alleviated, and the gut microbiota is restored to near-normal levels. These findings underscore the therapeutic potential of PMNPs for inflammatory bowel disease treatment and suggest broader biomedical applications.

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract, established as a risk factor for colorectal cancer (CRC) development. Long-standing inflammation appears to play a central role in colitis-associated colorectal cancer (CAC). However, the molecular mechanism underlying CAC progression is still elusive. Previous evidence showed that levels of branched glycosylation regulate T-cell-mediated immune response associated with IBD severity. Here, we revealed that colonic T cells from IBD patients are dynamically regulated by branched N-glycosylation and associated with the risk of CAC development.

We performed in silico analysis for glycome and immune profile of a publicly available human dataset of CAC patients. Additionally, in a well-characterized cohort of CAC patients, we evaluated the N-glycosylation profile of infiltrated colonic immune cells at different stages of carcinogenesis (colitis, dysplasia and cancer). In vivo studies were conducted in Mgat5 KO mice, using AOM/DSS model to induce CAC. Tumor development and colonic T cells glycoprofile were characterized during CAC development.

The combined analysis of human IBD and CAC clinical samples, together with glycoengineered mouse model susceptible to CAC, revealed a gradual and dynamic increase of branched N-glycans in T cells from colitis to dysplasia and cancer. This glycosylation switch was shown to impose inhibitory properties in T cells, precluding an effective antitumor immune response. Mechanistically, we demonstrated that the deletion of branched N-glycans in Mgat5 knockout mice led to CAC suppression due to increased infiltration of CD8+and γδ T cells, contributing to an effective antitumor immune response. From the clinical standpoint, we demonstrated that branched N-glycosylation levels detected in inflamed lesions from IBD patients predicted CAC progression with a sensitivity of 83.3% and specificity of 67.9% when assessed together with age at diagnosis.

Overall, we here disclosed a new mechanism underlying CAC development, identifying a potential clinical biomarker plausible to improve the efficacy of cancer surveillance programs through the early identification of high-risk IBD patients, for preventive clinical and therapeutic strategies.

Inflammatory bowel diseases (IBD) affect both enteric neurons and enteric glia, with tumor necrosis factor-alpha (TNF-α) playing a role as an inflammatory mediator.

Analyze the effects of the anti-TNF monoclonal antibody on the myenteric plexus in an experimental model of colitis.

C57BL/6 mice received 3% dextran sodium sulfate (DSS) in drinking water for 7 days in both the DSS and DSS + ADA groups. The Sham group received water. The DSS + ADA group received ADA anti-TNF-α on day 2 of DSS intake. The ADA group was given water throughout the period and received an anti-TNF-α injection on day 2. The study evaluated the number of neurons per ganglion, and the area of the neuronal nitric oxide synthase (nNOS), choline acetyltransferase (ChAT), pan-neuronal marker (PGP9.5), and tumor necrosis factor receptor 2 (TNFR2) immunoreactive (-ir). Double labeling of PGP9.5 with an enteric glial marker (GFAP) was also performed.

DSS successfully induced experimental colitis (EC). TNFR2 was detected in the myenteric neurons in all groups. EC affected the enteric neurons, showing a decrease in the number of TNFR2-ir, ChAT-ir, nNOS-ir, and PGP9.5-ir neurons, whereas enteric glial cells increased in both the DSS and DSS + ADA groups. The DSS + ADA group showed number of nNOS-ir, ChAT-ir, and PGP9.5-ir neurons per ganglion similar to Sham group. EC also affected the neuronal profile, resulting in smaller areas in the DSS and DSS + ADA groups.

Myenteric neurons are immunoreactive to the TNFR2. DSS altered the myenteric plexus, and anti-TNF monoclonal antibody treatment proved effective against EC due to preventing the pathology from developing.

Thalidomide (THA) is renowned for its potent anti-inflammatory properties. This study aimed to elucidate its underlying mechanisms in the context of Crohn's disease (CD) development. Mouse colitis models were established by dextran sulfate sodium (DSS) treatment. Fecal microbiota and metabolites were analyzed by metagenomic sequencing and mass spectrometry, respectively. Antibiotic-treated mice served as models for microbiota depletion and transplantation. The expression of forkhead box P3+ (FOXP3+) regulatory T cells (Tregs) was measured by flow cytometry and immunohistochemical assay in colitis model and patient cohort. THA inhibited colitis in DSS-treated mice by altering the gut microbiota profile, with an increased abundance of probiotics Bacteroides fragilis, while pathogenic bacteria were depleted. In addition, THA increased beneficial metabolites bile acids and significantly restored gut barrier function. Transcriptomic profiling revealed that THA inhibited interleukin-17 (IL-17), IL-1β and cell cycle signaling. Fecal microbiota transplantation from THA-treated mice to microbiota-depleted mice partly recapitulated the effects of THA. Specifically, increased level of gut commensal B. fragilis was observed, correlated with elevated levels of the microbial metabolite 3alpha-hydroxy-7-oxo-5beta-cholanic acid (7-ketolithocholic acid, 7-KA) following THA treatment. This microbial metabolite may stable FOXP3 expression by targeting the receptor FMR1 autosomal homolog 1 (FXR1) to inhibit autophagy. An interaction between FOXP3 and FXR1 was identified, with binding regions localized to the FOXP3 domain (aa238-335) and the FXR1 domain (aa82-222), respectively. Conclusively, THA modulates the gut microbiota and metabolite profiles towards a more beneficial composition, enhances gut barrier function, promotes the differentiation of FOXP3+ Tregs and curbs pro-inflammatory pathways.

The progression of inflammatory bowel disease (IBD) is closely connected with intestinal flora dysbiosis. Sakuranetin (SAK) is a natural compound with anti-inflammatory and antibiosis activities. We investigated the properties and mechanisms of SAK on IBD-like colitis.

Mice with dextran sulfate sodium (DSS)-induced colitis were accomplished to assess the effects of SAK on colitis, as well as intestinal mucosal immune imbalance and intestinal barrier dysfunction. 16S rDNA was used to characterize the intestinal flora, and the short-chain fatty acid (SCFA) content in faeces was calculated using GS‒MS. Faecal microbiota transplantation (FMT) and a pseudosterile model (antibiotic cocktail, ABX) were used to evaluate whether the effects of SAK on colitis were dependent on the gut flora. Pathohistological and biochemical tests were used to estimate the safety of SAK.

SAK significantly ameliorated DSS-induced colitis in mice, verified by decreased weight loss, less colon shortening, and lower disease activity, histology and colonoscopy scores. Moreover, SAK alleviated gut dysbiosis and elevated the abundance of SCFA-producing bacteria in DSS-treated mice. Meanwhile, SAK increased faecal SCFA levels and activated GPR41/43 signalling. SAK also improved Treg/Th17 homeostasis and intestinal barrier function. In addition, ABX and FMT experiments confirmed that the ability of SAK to alleviate colitis was mediated through the gut flora. Finally, a safety experiment revealed that SAK had no significant adverse effects on major organ or liver/kidney function.

SAK may improve the intestinal immune balance and barrier function by regulating intestinal flora dysbiosis and increasing SCFA production, thereby protecting against colitis.

5-aminosalicylic acid (5-ASA) is widely used in the treatment of ulcerative colitis (UC), but its anti-inflammatory mechanism is complex and has not been fully understood. DSS model was used to test the effect of 5-ASA. Tight junction and Ki-67 were detected by western blot, immunofluorescence, and immunohistochemistry or qPCR. 16S rRNA gene sequencing of gut microbiota and subsequent bioinformatics and statistical analysis were performed to identify the specific bacteria which were associated with the treatment effect of 5-ASA. GC-MS was performed to test short-chain fatty acids (SCFAs). Antibiotic-treated mice were used to demonstrate the key role of endogenous gut microbiota. Here, we found that 5-ASA alleviated dextran sulfate sodium (DSS)-induced colitis in mice. Moreover, 5-ASA significantly repaired the intestinal barrier. At the molecular level, 5-ASA markedly raised the expression of tight junction proteins including JAM-A and occludin and cell proliferation marker Ki-67 in mice. In addition, bacterial 16S rRNA gene sequencing and bioinformatics analysis showed that 5-ASA significantly modulated the DSS-induced gut bacterial dysbiosis. In detail, it stimulated the growth of protective bacteria belonging to Faecalibaculum and Dubosiella, which were negatively correlated with colitis parameters, and blocked the expansion of pro-inflammatory bacteria such as Escherichia-Shigella and Oscillibacter, which were positively correlated with colitis in mice. Meanwhile, 5-ASA increased the cecal acetate level. Most notably, 5-ASA was no longer able to treat colitis and reverse gut barrier dysfunction in antibiotic-treated mice that lacked endogenous gut microbiota. Our data suggested that the anti-inflammatory activity of 5-ASA required the inherent intestinal flora, and the gut microbiota was a potential and effective target for the treatment of ulcerative colitis.

Ulcerative colitis (UC) is a chronic inflammatory disease characterized by loss of immune tolerance to luminal antigens and progressive intestinal tissue injury. Thus, the re-establishment of immune tolerance is crucial for suppressing aberrant immune responses and UC progression.

This study aimed to investigate the mechanisms underlying the action of CDD-2103 and its bioactive compounds in mediating immune regulation in mouse models of colitis.

Two experimental colitis models, chronic 2,4,6-trinitrobenzene sulfonic acid (TNBS)- and T-cell transfer-induced Rag1-/- mice, were used to determine the effects of CDD-2103 on colitis progression. Single-cell transcriptome analysis was used to profile the immune landscape and its interactions after CDD-2103 treatment. Liquid chromatography-mass spectrometry (LC-MS) was used to analyze the major components interacting with lymphoid cells. A primary cell co-culture system was used to confirm the effects of bioactive component.

CDD-2103 dose-dependently suppresses the progression of colitis induced by chemicals or T cell transplantation in Rag1-/- mice. The effect of CDD-2103 is primarily attributable to an increase in the de novo generation of regulatory T cells (Tregs) in the lamina propria (LP). Single-cell transcriptomic analysis revealed that CDD-2103 treatment increased the number of tolerogenic dendritic cells (DCs). Mechanistically, CDD-2103 promoted tolerogenic DCs accumulation and function by upregulating several genes in the electron transport chain related to oxidative phosphorylation, leading to increased differentiation of Tregs. Further LC-MS analysis identified several compounds in CDD-2103, particularly those distributed within the mesenteric lymph nodes of mice. Subsequent studies revealed that palmatine and berberine promoted tolerogenic bone marrow-derived dendritic cells (BMDC)-mediated Treg differentiation.

Overall, our study demonstrated that the clinically beneficial effect of CDD-2103 in the treatment of UC is based on the induction of immune tolerance. In addition, this study supports berberine and palmatine as potential chemical entities in CDD-2103 that modulate immune tolerance.

Inflammatory bowel diseases (IBDs) are characterized by unrestrained innate and adaptive immune responses and compromised intestinal epithelial barrier integrity. Regulatory T (Treg) cells are crucial for maintaining self-tolerance and immune homeostasis in intestinal tissues. Prostaglandin E2 (PGE2), a bioactive lipid compound derived from arachidonic acid, can modulate T cell functions in a receptor subtype-specific manner. However, whether PGE2 regulates Treg cell function and contributes to IBD pathogenesis remains unclear. Here, we found that the PGE2 receptor subtype 2 (EP2) is highly expressed in Treg cells. Treg cell-specific deletion of EP2 resulted in increased Treg cell numbers, and enhanced granzyme B(GzmB) expression and immunosuppressive capacity of Treg cells in mice. Adoptive transfer of EP2-deficient Treg cells attenuated naïve CD4+ T cell transfer-induced colitis in Rag1-/- mice. Mice with EP2-deficient Treg cells were protected from 2,4,6-trinitrobenzene sulfonic acid (TNBS)- and dextran sodium sulfate (DSS)-induced colitis. Pharmacological blockage of EP2 with PF-04418948 markedly alleviated DSS-induced colitis in mice in a Treg-dependent manner. Mechanistically, activation of EP2 suppressed Treg cell function, at least in part, through reduction of GzmB expression via PKA-mediated inhibition of NF-κB signaling. Thus, we identified the PGE2/EP2 axis as a key negative modulator of Treg cell function, suggesting EP2 inhibition as a potential therapeutic strategy for IBD treatment.

Regulatory T cells (Tregs) play a critical role in maintaining tissue immune homeostasis, but they are relatively insufficient at inflammatory intestinal sites in patients with inflammatory bowel disease (IBD). However, what controls Treg homing to the intestine in IBD is unknown.

α1,3 Fucosyltransferase VII (FUT7) expression in Tregs from patients with active IBD was detected by RNA sequencing. To determine whether FUT7 controls Treg intestinal homing in IBD, Treg-specific Fut7 conditional knockout (CKO) mice were constructed and used in an IBD model induced by dextran sulfate sodium. To investigate whether up-regulating FUT7 expression in Tregs plays a therapeutic role in IBD, the nanocarrier CD4-LDP-Fut7, which specifically targets Tregs to express Fut7, was constructed and used in the IBD model. In addition, whether Fut7 regulates other Treg functions was explored by mass cytometry.

Compared with healthy controls, patients with active IBD had significantly decreased FUT7 expression in Tregs. In the IBD model, CKO mice had a lower frequency of colonic Tregs among CD4+ T cells and a lower ratio of colonic to splenic Tregs from the same mouse than their littermate controls did, indicating that Fut7 deficiency impaired the ability of Tregs to home to the intestine. Consistently, CKO mice had severe colitis, and CD4-LDP-Fut7 alleviated it in the IBD model. Mass cytometry analysis revealed that Fut7 down-regulated PD1 expression in Tregs via competition with Fut8 for the substrate GDP-fucose, thereby increasing the immunosuppressive capacity of Tregs.

FUT7 enhances Treg intestinal homing and immunosuppression. Thus, up-regulating FUT7 expression in Tregs could be a novel therapeutic strategy for IBD.

Crohn's disease (CD) is characterized by immune cell dysregulation, with macrophages playing an indisputable role. Macrophages can exhibit opposing polarization under different conditions, resulting in pro- or anti-inflammatory effects. The aryl hydrocarbon receptor (AhR), a ligand-dependent transcription factor, is implicated in intestinal inflammation by regulating both innate and adaptive immune responses. However, the regulatory mechanism between AhR and macrophages in colitis has not been thoroughly investigated.

Macrophage polarization in the colonic tissue of active CD patients was assessed. Following colitis induction in mice by 2,4,6-trinitro-benzenesulfonic acid (TNBS), an intraperitoneal injection of the natural AhR agonist 6-formylindolo[3,2-b]carbazole (FICZ) was administered. The severity of colitis was estimated, and macrophage polarization was detected. In an in vitro setting, bone marrow-derived macrophages (BMDMs) were polarized to the M2 phenotype in the presence or absence of FICZ. Interferon regulatory factor 4 (IRF4) siRNA was applied to knockdown IRF4 expression. M2-specific markers were quantified using quantitative real-time PCR (qRT-PCR), enzyme-linked immunosorbent assay (ELISA) and flow cytometry.

Compared with healthy controls, active CD patients exhibited a lower presence of M2 macrophages in colonic tissue. Experimentally, FICZ was found to protect mice against TNBS-induced colitis, as evidenced by reduced diarrhea, bloody stool, and weight loss. This effect was associated with an increase in M2 macrophages and the release of IL-10 in the intestine. In BMDMs, FICZ promoted the expressions of M2-specific markers, including Ym1, Fizz1, IL-10, and CD206. Furthermore, FICZ upregulated IRF4 expression. After IRF4 silencing with siRNA, the enhancement of macrophage M2 polarization by FICZ was significantly impaired.

Activation of AhR appears to have a beneficial effect on intestinal inflammation by promoting macrophage M2 polarization. This effect is partially mediated by the upregulation of IRF4 expression and may lead to new insight into the pathogenesis of CD.

Tolerogenic antigen-presenting cells (APCs) are promising as therapeutics for suppressing T cell activation in autoimmune diseases. However, the isolation and ex vivo manipulation of autologous APCs is costly, and the process is customized for each patient. Here we show that tolerogenic APCs can be generated in vivo by delivering, via lipid nanoparticles, messenger RNA coding for the inhibitory protein programmed death ligand 1. We optimized a lipid-nanoparticle formulation to minimize its immunogenicity by reducing the molar ratio of nitrogen atoms on the ionizable lipid and the phosphate groups on the encapsulated mRNA. In mouse models of rheumatoid arthritis and ulcerative colitis, subcutaneous delivery of nanoparticles encapsulating mRNA encoding programmed death ligand 1 reduced the fraction of activated T cells, promoted the induction of regulatory T cells and effectively prevented disease progression. The method may allow for the engineering of APCs that target specific autoantigens or that integrate additional inhibitory molecules.

Piezo1, which maintains the integrity and function of the intestinal epithelial barrier, is essential for colonic epithelial homeostasis. However, whether and how Piezo1 regulates colon stem cell fate remains unclear. Here, we show that Piezo1 inhibition promotes colon stem cell proliferation. Mechanistically, stearoyl-CoA 9-desaturase 1 (SCD1) is downstream of Piezo1 to affect colon stem cell stemness by acting on the Wnt-β-catenin pathway. For mice, the altered colon stem cell stemness after Piezo1 knockdown and activation was accompanied by a reprogrammed fatty acid (FA) metabolism in colon crypts. Notably, we found that GsMTX4 protects injured colon stem cell stemness in mouse and human colitis organoids. Our results elucidated the role of Piezo1 in regulating normal and postinjury colon stem cell fates through SCD1-Wnt-β-catenin and the SCD1-mediated FA desaturation process. These results provide fresh perspectives on the mechanical factors regulating colon stem cell fate and therapeutic strategies for related intestinal diseases.