Inflammasome activation links enteric Salmonella Typhimurium infection to a rapid, cytokine-dependent increase in intestinal mucin release.

The host restricts Salmonella enterica serovar Typhimurium infection of the gut via inflammasome-dependent sloughing of infected epithelial cells. Here we determined that concurrent caspase 1/11-dependent release of the goblet cell-derived mucin, Muc2, into the intestinal lumen also controls Salmonella burdens in infected mice. The increased release of mucins from goblet cells in the cecum and nearby proximal colon, and the subsequent thickening of the protective mucus barrier layer in the distal colon, were all dependent on the cytokines interleukin (IL)-18 and IL-22, as deficiencies in either cytokine resulted in reduced mucin secretion. Supplementation of IL-18 into IL-22 deficient mice restored mucin secretion, indicating that IL-22 acted upstream of IL-18 secretion during infection. In contrast, IL-18 and IL-22 independent signaling through Nlrp6 underlies only a modest, infection-induced increase in mucin secretion from goblet cells in the distal colon. These findings reveal that inflammasome signaling orchestrates multiple levels of protection centered on the intestinal epithelium, including pyroptosis and expulsion of infected enterocytes, as well as the release of mucins by goblet cells in the cecum and along the length of the colon. Our studies underscore the pivotal, multi-faceted role of inflammasome signaling in promoting host defense at the intestinal mucosal surface.

Toll-like receptor 7 protects against intestinal inflammation and restricts the development of colonic tissue-resident memory CD8+ T cells.

Introduction: The maintenance of intestinal homeostasis depends on a complex interaction between the immune system, intestinal epithelial barrier, and microbiota. Alteration in one of these components could lead to the development of inflammatory bowel diseases (IBD). Variants within the autophagy gene ATG16L1 have been implicated in susceptibility and severity of Crohn's disease (CD). Individuals carrying the risk ATG16L1 T300A variant have higher caspase 3-dependent degradation of ATG16L1 resulting in impaired autophagy and increased cellular stress. ATG16L1-deficiency induces enhanced IL-1ß secretion in dendritic cells in response to bacterial infection. Infection of ATG16L1-deficient mice with a persistent strain of murine norovirus renders these mice highly susceptible to dextran sulfate sodium colitis. Moreover, persistent norovirus infection leads to intestinal virus specific CD8+ T cells responses. Both Toll-like receptor 7 (TLR7), which recognizes single-stranded RNA viruses, and ATG16L1, which facilitates the delivery of viral nucleic acids to the autolysosome endosome, are required for anti-viral immune responses. Results and discussion: However, the role of the enteric virome in IBD is still poorly understood. Here, we investigate the role of TLR7 and ATG16L1 in intestinal homeostasis and inflammation. At steady state, Tlr7-/- mice have a significant increase in large intestinal lamina propria (LP) granzyme B+ tissue-resident memory CD8+ T (TRM) cells compared to WT mice, reminiscent of persistent norovirus infection. Deletion of Atg16l1 in myeloid (Atg16l1ΔLyz2 ) or dendritic cells (Atg16l1ΔCd11c ) leads to a similar increase of LP TRM. Furthermore, Tlr7-/- and Atg16l1ΔCd11c mice were more susceptible to dextran sulfate sodium colitis with an increase in disease activity index, histoscore, and increased secretion of IFN-γ and TNF-α. Treatment of Atg16l1ΔCd11c mice with the TLR7 agonist Imiquimod attenuated colonic inflammation in these mice. Our data demonstrate that ATG16L1-deficiency in myeloid and dendritic cells leads to an increase in LP TRM and consequently to increased susceptibility to colitis by impairing the recognition of enteric viruses by TLR7. Conclusion: In conclusion, the convergence of ATG16L1 and TLR7 signaling pathways plays an important role in the immune response to intestinal viruses. Our data suggest that activation of the TLR7 signaling pathway could be an attractive therapeutic target for CD patients with ATG16L1 risk variants.

Pan-immune-inflammation value as a prognostic biomarker for colon cancer and its variation by primary tumor location.

BACKGROUND: A growing body of research indicates significant differences between left-sided colon cancers (LCC) and right-sided colon cancers (RCC). Pan-immune-inflammation value (PIV) is a systemic immune response marker that can predict the prognosis of patients with colon cancer. However, the specific distinction between PIV of LCC and RCC remains unclear. AIM: To investigate the prognostic and clinical significance of PIV in LCC and RCC patients. METHODS: This multicenter retrospective cohort study included 1510 patients with colon cancer, comprising 801 with LCC and 709 with RCC. We used generalized lifting regression analysis to evaluate the relative impact of PIV on disease-free survival (DFS) in these patients. Kaplan-Meier analysis, as well as univariate and multivariate analyses, were used to examine the risk factors for DFS. The correlation between PIV and the clinical characteristics was statistically analyzed in these patients. RESULTS: A total of 1510 patients {872 female patients (58%); median age 63 years [interquartile ranges (IQR): 54-71]; patients with LCC 801 (53%); median follow-up 44.17 months (IQR 29.67-62.32)} were identified. PIV was significantly higher in patients with RCC [median (IQR): 214.34 (121.78-386.72) vs 175.87 (111.92-286.84), P < 0.001]. After propensity score matching, no difference in PIV was observed between patients with LCC and RCC [median (IQR): 182.42 (111.88-297.65) vs 189.45 (109.44-316.02); P = 0.987]. PIV thresholds for DFS were 227.84 in LCC and 145.99 in RCC. High PIV (> 227.84) was associated with worse DFS in LCC [PIV-high: Adjusted hazard ratio (aHR) = 2.39; 95% confidence interval: 1.70-3.38; P < 0.001] but not in RCC (PIV-high: aHR = 0.72; 95% confidence interval: 0.48-1.08; P = 0.114). CONCLUSION: These findings suggest that PIV may predict recurrence in patients with LCC but not RCC, underscoring the importance of tumor location when using PIV as a colon cancer biomarker.

Immunomodulatory effect of Dicrocoelium dendriticum ova on DSS-induced experimental colitis in C57BL/6 mouse.

Inflammatory bowel disease (IBD) significantly diminishes an individual's quality of life and increases the risk of colorectal cancer. Recent clinical and experimental findings suggest that infection with parasitic helminths may suppress the development of certain inflammatory conditions. The objective of this study was to evaluate the immunoregulatory effects of Dicrocoelium eggs on experimentally induced colitis in C57BL/6 mice using dextran sulfate sodium (DSS). C57BL/6 mice received 3.5% DSS orally for 7 days to induce colitis, during which they were treated intraperitoneally with Dicrocoelium eggs. The severity of colitis was assessed through parameters such as body weight, stool consistency or bleeding, disease activity index (DAI), colon lengths, macroscopic scores, histopathological findings, colon gene expression levels, and serum cytokine levels. Our results indicated that Dicrocoelium eggs administration significantly reduced the severity of colitis and disease activity. Histopathological scores improved, correlating with downregulation of IFN-γ and upregulation of IL-4 expression. This findings suggest the therapeutic potential of Dicrocoelium eggs in treating colitis. Immunotherapy involving Dicrocoelium eggs primarily induces a Th2 response and modulates IFN-γ, contributing to reduced inflammation in colitis. Thus, this approach could be a promising therapeutic strategy for alleviating inflammation in IBD.

Clostridium sporogenes-derived metabolites protect mice against colonic inflammation.

Gut microbiota-derived metabolites play a pivotal role in the maintenance of intestinal immune homeostasis. Here, we demonstrate that the human commensal Clostridium sporogenes possesses a specific metabolic fingerprint, consisting predominantly of the tryptophan catabolite indole-3-propionic acid (IPA), the branched-chain acids (BCFAs) isobutyrate and isovalerate and the short-chain fatty acids (SCFAs) acetate and propionate. Mono-colonization of germ-free mice with C. sporogenes (CS mice) affected colonic mucosal immune cell phenotypes, including up-regulation of Il22 gene expression, and increased abundance of transcriptionally active colonic tuft cells and Foxp3+ regulatory T cells (Tregs). In DSS-induced colitis, conventional mice suffered severe inflammation accompanied by loss of colonic crypts. These symptoms were absent in CS mice. In conventional, but not CS mice, bulk RNAseq analysis of the colon revealed an increase in inflammatory and Th17-related gene signatures. C. sporogenes-derived IPA reduced IL-17A protein expression by suppressing mTOR activity and by altering ribosome-related pathways in Th17 cells. Additionally, BCFAs and SCFAs generated by C. sporogenes enhanced the activity of Tregs and increased the production of IL-22, which led to protection from colitis. Collectively, we identified C. sporogenes as a therapeutically relevant probiotic bacterium that might be employed in patients with inflammatory bowel disease (IBD).

Neohesperidin Attenuates DSS-Induced Ulcerative Colitis by Inhibiting Inflammation, Reducing Intestinal Barrier Damage, and Modulating Intestinal Flora Composition.

Flavonoid natural products are emerging as a promising approach for treating Ulcerative Colitis (UC) due to their natural origin and minimal toxicity. This study investigates the effects of Neohesperidin (NEO), a natural flavonoid, on Dextran Sodium Sulfate (DSS)-induced UC in mice, focusing on the underlying molecular mechanisms. Early intervention with NEO (25 and 50 mg/kg) mitigated colon shortening, restored damaged barrier proteins, and significantly reduced the inflammatory cytokine levels. Moreover, NEO inhibited the MAPK/NF-κB signaling pathway and enhanced the levels of intestinal barrier proteins (Claudin-3 and ZO-1). Additionally, NEO increased beneficial intestinal probiotics (S24-7 and Lactobacillaceae) while reducing harmful bacteria (Erysipelotrichi, Enterobacteriaceae). Fecal microbial transplantation (FMT) results demonstrated that NEO (50 mg/kg) markedly improved UC symptoms. In conclusion, early NEO intervention may alleviate DSS-induced UC by inhibiting inflammatory responses, preserving intestinal barrier integrity and modulating gut microbiota.

Inverse Correlation of Th2-Specific Cytokines with Hepatic Egg Burden in S. mansoni-Infected Hamsters.

Schistosomiasis, a parasitic disease caused by Schistosoma spp., affects more than 250 million people worldwide. S. mansoni in particular affects the gastrointestinal tract and, through its eggs, induces a Th2 immune response leading to granuloma formation. The relationship between egg load and immune response is poorly understood. We investigated whether the quantity of parasitic eggs influences the immune response in S. mansoni-infected hamsters. The hepatic and intestinal egg load was assessed, and cytokine expression as well as the expression of three major egg-derived proteins were analyzed in monosex- and bisex-infected animals by qRT-PCR. Statistical correlations between egg load or egg-derived factors Ipse/alpha-1, kappa-5, and omega-1, and the immune response were analyzed in liver and colon tissue. Surprisingly, no correlation of the Th1 cytokines with the hepatic egg load was observed, while the Th2 cytokines Il4, Il5, and Il13 showed an inverse correlation in the liver but not in the colon. A longer embryogenesis of the parasitic eggs in the liver could explain this correlation. This conclusion is supported by the lack of any correlation with immune response in the colon, as the intestinal passage of the eggs is limited to a few days.

FMT rescues mice from DSS-induced colitis in a STING-dependent manner.

Fecal microbiota transplantation (FMT) is currently a promising therapy for inflammatory bowel disease (IBD). However, clinical studies have shown that there is an obvious individual difference in the efficacy of FMT. Therefore, it is a pressing issue to identify the factors that influence the efficacy of FMT and find ways to screen the most suitable patients for this therapy. In this work, we targeted the stimulator of interferon genes (STING), a DNA-sensing protein that regulates host-defense. By comparing the differential efficacy of FMT in mice with different expression level of STING, it is revealed that FMT therapy provides treatment for DSS-induced colitis in a STING-dependent manner. Mechanistically, FMT exerts a regulatory effect on the differentiation of intestinal Th17 cells and macrophages, splenic Th1 and Th2 cells, as well as Th1 cells of the mesenteric lymph nodes via STING, down-regulating the colonic M1/M2 and splenic Th1/Th2 cell ratios, thereby improving the imbalanced immune homeostasis in the inflamed intestine. Meanwhile, based on the 16SrDNA sequencing of mice fecal samples, STING was found to facilitate the donor strain colonization in recipients' gut, mainly Lactobacillales, thereby reshaping the gut microbiota disturbed by colitis. Consequently, we proposed that STING, as a key target of FMT therapy, is potentially a biomarker for screening the most suitable individuals for FMT to optimize treatment regimens and enhance clinical benefit.

Formononetin ameliorates dextran sulfate sodium-induced colitis via enhancing antioxidant capacity, promoting tight junction protein expression and reshaping M1/M2 macrophage polarization balance.

Ulcerative colitis (UC) is a complex, refractory inflammatory bowel disease characterized impared intestinal mucosal barrier and imbalanced M1/M2 macrophage polarization mediating its progression. Formononetin (FN), a bioactive isoflavone with established anti-inflammatory and immunomodulatory properties, shows promise in mitigating UC, yet its therapeutic and underlying mechanisms remain unclear. In this study, colitis was induced in mice by administering 2.5% (w/v) dextran sulfate sodium (DSS) solution for 7 days. Oral (25, 50, and 100 mg/kg) FN for 10 days significantly ameliorated colitis symptoms in a dose-dependent manner, by mitigating body weight loss, reducing disease activity index (DAI), colonic weight, and colonic weight index, while enhancing survival rates and colonic length. Histological analysis revealed FN remarkably suppressed inflammatory damage in colonic tissues. Furthermore, FN modulated the expression of pro- and anti-inflammatory cytokines and enhanced antioxidant capacity. Notably, FN treatment significantly enhanced the expression of tight junction (TJ) proteins (claudin-1, ZO-1, occludin) at both protein and mRNA levels in the colon tissues, suggesting improved intestinal barrier function. Crucially, FN inhibited macrophage infiltration in colonic tissues and rebalanced M1/M2 macrophage polarization. While, macrophage depletion largely abrogated FN's protective effects against colitis, indicating a crucial role for macrophages in mediating FN's therapeutic response. Overall, FN effectively alleviated colitis primarily via modulating inflammatory cytokine expression, enhancing antioxidant capacity, upregulating TJs proteins expression, and remodeling M1/M2 macrophage polarization equilibrium. These findings suggest that FN could be the next candidate to unlocking UC's treatment challenge.

Demethylzeylasteral alleviates inflammation and colitis via dual suppression of NF-κB and STAT3/5 by targeting IKKα/ß and JAK2.

BACKGROUND: Ulcerative colitis (UC) is a common inflammatory bowel disease and a risk factor of colorectal cancer. Demethylzeylasteral (DZT), a bioactive component mainly isolated from Tripterygium wilfordii, has been shown to inhibit inflammation and cancer. However, its anti-UC function and molecular mechanisms have not been well characterized. This study aims to explore the therapeutic effect and functional targets of demethylzeylasteral against UC. METHODS: RT-qPCR, Western blot and ELISA were used to detect the generation of pro-inflammatory cytokines and chemokines in murine macrophage cells. Luciferase reporter gene, Western blot, pull-down, CETSA, DARTS, and virtual docking were employed to detect the anti-inflammatory targets and molecular mechanisms of demethylzeylasteral. The anti-inflammatory and anti-colitis effects of demethylzeylasteral were further determined in DSS-challenged mice. RESULTS: In vitro, demethylzeylasteral inhibited NO and PGE2 production by suppressing the mRNA and protein expression of iNOS and COX-2, and suppressed the mRNA expression of TNF-α, IL-1ß, IL-6, MCP-1, CXCL9, and CXCL10 in RAW264.7 macrophages stimulated by LPS/IFNγ. Furthermore, demethylzeylasteral was not only capable of inhibiting IKKα/ß-NF-κB activation, but also able to block JAKs-STAT3/5 activation in LPS/INFγ-incubated RAW264.7 cells or DSS-exposed colon tissues of mice. Mechanistically, demethylzeylasteral was found to directly bind to IKKα/ß and JAK2 kinases, leading to inactivation of pro-inflammatory signaling cascades and reduced generation of cytokines and chemokines. In vivo, oral administration of demethylzeylasteral significantly attenuated DSS-induced colitis, which was mainly manifested as mitigated symptoms of colitis, colonic mucosal barrier damage, and colonic inflammation. CONCLUSION: We demonstrated that demethylzeylasteral alleviated UC pathology by blocking NF-κB and STAT3/5 pathways via targeting IKKα/ß and JAK2 kinases, raising the possibility that demethylzeylasteral could act as a candidate for the treatment of UC.

Differential immunological responses in lamb rumen and colon to alfalfa hay and wheat straw in a concentrate-rich diet: insights into microbe-host interactions.

The impact of a concentrate-rich (CR) diet on the gut microbiome and epithelium homeostasis is well documented. However, it has not been systematically studied whether and how host-microbial interaction contributes to the immune homeostasis in the rumen and colon of lambs fed alfalfa hay and wheat straw, alone or combined, in a CR diet. In all, 63 lambs (initial body weight, 16.69 ± 1.50 kg) were randomly allotted to three dietary groups, each consisting of three pens with seven lambs per pen. Over 14 weeks, the lambs were fed diets as follows: 60% concentrate supplemented with either 40% wheat straw (WG), 20% alfalfa hay combined with 20% wheat straw (MG), or 40% alfalfa hay (AG). The present findings showed that lambs in the AG group had greater (P < 0.05) IgG and lower (P = 0.067) tumor necrosis factor-alpha concentrations relative to those in the MG and WG groups. The 16S rRNA analysis highlighted that various bacterial phyla and genera in the rumen and colon preferentially degrade fiber and starch derived from alfalfa hay and wheat straw. The weighted gene co-expression network analysis revealed that the bacterial genera from the Firmicutes are broadly associated with genes involved in various signaling pathways, underscoring the potential role of Firmicutes as key drivers of host-microbial interactions under the present feeding conditions. These findings shed light on the fact that the rumen and colon immune homeostasis is distinctively influenced by diets of alfalfa hay, wheat straw, or their combination in a CR diet. Further studies should examine the prolonged effects of replacing wheat straw with alfalfa hay in a concentrate-rich diet formulated to provide equivalent neutral detergent fiber levels. This could reveal how various forage fibers influence host-microbial interactions and gut health.IMPORTANCEIn contemporary feedlots, a growing trend is to feed animals a concentrate-rich (CR) diet that could disrupt the synchronized interplay between microbes and host metabolism, leading to altered metabolic functions. Wheat straw and alfalfa hay have different levels of protein and neutral detergent fiber, each with varying rates of digestion. It is unclear how including alfalfa hay and wheat straw, alone or combined in a CR diet, influences the host-microbial consortia and immune homeostasis. Herein, we showed that rumen and colon showed differential immune responses to the alfalfa hay, wheat straw, or both. Bacterial genera preferentially degrade fiber and starch derived from alfalfa hay, wheat straw, or both. Bacterial genera from Firmicutes phylum play a pivotal role in driving the host-microbial interactions, as indicated by their extensive association with genes across various signaling pathways.

NPSR1 promotes chronic colitis through regulating CD4+ T cell effector function in inflammatory bowel disease.

BACKGROUND: Neuropeptide S receptor 1 (NPSR1) has been implicated in the the onset of inflammatory bowel disease (IBD), though its exact mechanism remains unclear. This study investigates the role of NPSR1 in regulating CD4+ T cell effector function in IBD. METHODS: Peripheral blood and colonic mucosal biopsies from IBD patients, as well as dextran sodium sulfate (DSS)-induced mouse colitis models, were analyzed to assess the effects of NPSR1 on colitis and CD4+ T cell-mediated immune responses. NPSR1 knockdown was conducted both in vitro and in vivo to elucidate underlying mechanisms. Expression of NPSR1 and CD4+ T cell-related factors was measured using quantitative real-time PCR, immunoblotting, cytometric bead array, immunofluorescence, and immunohistochemistry. CD4 + T cell effector functions were evaluated through flow cytometry, EdU incorporation assay, Annexin V-FITC/PI staining, and transwell assay. RESULTS: NPSR1 expression was elevated in the intestinal tissues from IBD patients. Its downregulation provided protection in DSS-induced mouse colitis models. NPSR1 correlated positively with CD4 + T cell-mediated inflammation, and its knockdown reduced CD4+ T cell-mediated immune responses and inhibited CD4+ T cell differentiation. Additionally, NPSR1 knockdown decreased CD4+ T cell proliferation, increased apoptosis, and enhanced CCL2-induced migration in vitro, while significantly reducing Th1 cell chemotaxis in vivo. CONCLUSIONS: This study demonstrates that NPSR1 promotes chronic colitis by regulating CD4 + T cell effector functions in IBD, offering potential new therapeutic strategies for IBD treatment.

DJ-X-013 reduces LPS-induced inflammation, modulates Th17/ myeloid-derived suppressor cells, and alters NF-κB expression to ameliorate experimental colitis.

SCOPE: Inflammatory bowel disease (IBD) is a chronic intestinal inflammatory condition of unknown etiology, although recent evidence suggests that it is caused by an excessive immune response to mucosal antigens. We determined the anti-inflammatory properties of novel compound DJ-X-013 in vitro in lipopolysaccharide (LPS)-induced macrophages and in an in vivo dextran sodium sulfate (DSS)-induced model of colitis. METHODS AND RESULTS: To evaluate the anti-inflammatory properties of DJ-X-013, we used LPS-activated RAW 264.7 macrophages in vitro and a DSS-induced experimental model of colitis in vivo. We examine cellular morphology, and tissue architecture by histology, flow cytometry, RT-qPCR, multiplex, and immunoblot analysis to perform cellular and molecular studies. DJ-X-013 treatment altered cell morphology and expression of inflammatory cytokines in LPS-activated macrophages as compared to cells treated with LPS alone. DJ-X-013 also impeded the migration of RAW 264.7 macrophages by modulating cytoskeletal organization and suppressed the expression of NF-κB and inflammatory markers as compared to LPS alone. DJ-X-013 treatment improved body weight, and colon length and attenuated inflammation in the colon of DSS-induced colitis. Intriguingly, DSS-challenged mice treated with DJ-X-013 induced the numbers of myeloid-derived suppressor cells (MDSCs), dendritic cells (DCs), and natural killer T cells (NKT) in the colon lamina propria (LP) relative to DSS. DJ-X-013 also reduced the influx of neutrophils, TNF-α producing macrophages, restricted the number of Th17 cells, and suppressed inflammatory cytokines and NF-κB in the LP relative to DSS. CONCLUSION: DJ-X-013 is proposed to be a therapeutic strategy for ameliorating inflammation and experimental colitis.

Gut microbiota dysbiosis deteriorates immunoregulatory effects of tryptophan via colonic indole and LBP/HTR2B-mediated macrophage function.

Tryptophan (Trp) has been shown to regulate immune function by modulating gut serotonin (5-HT) metabolism and signaling. However, the mechanisms underlying the microbial modulation of gut 5-HT signaling in gut inflammation with gut microbiota dysbiosis require further investigation. Here, we investigated the effects of Trp supplementation on the composition and metabolism of the gut microbiome and 5-HT signaling-related gut immune function using a dextran sodium sulfate (DSS)-induced colitis mouse model coupled with antibiotic exposure. The results showed that antibiotic treatment before but not during DSS treatment decreased the immunoregulatory effects of Trp and aggravated gut inflammation and body weight loss in mice. Metagenomic analysis revealed that the fecal microbiota transplantation of Trp-enriched gut microbiota to recipient mice subject to antibiotic pre-exposure and DSS treatment alleviated inflammation by increasing the relative abundances of Lactobacillus and Parabacteroides and the microbial production of indole coupled with the activation of the 5-HT receptor 2B (HTR2B) in the colon. Transcriptomic analysis showed that HTR2B agonist administration strengthened the beneficial effects of Trp in DSS-induced colitis mice with antibiotic exposure by reducing gut lipopolysaccharide-binding protein (LBP) production, IκB-α/nuclear factor-κB signaling, and M1 macrophage polarization. Indole treatment reduced LBP production and M1 macrophage polarization both in mice with DSS-induced colitis and in lipopolysaccharide-treated mouse macrophages; however, the HTR2B antagonist reversed the effects of indole. Our findings provide the basis for developing new dietary and therapeutic interventions to improve gut microbiota dysbiosis-associated inflammatory gut disorders and diseases.

l-Theanine Alleviates Ulcerative Colitis by Regulating Colon Immunity via the Gut Microbiota in an MHC-II-Dependent Manner.

Alterations to the gut microbiota are associated with ulcerative colitis (UC), whereas restoration of normobiosis can effectively alleviate UC. l-Theanine has been shown to reshape the gut microbiota and regulate gut immunity. To investigate the mechanisms by which l-theanine alleviates UC, we used l-theanine and l-theanine fecal microbiota solution to treat UC mice. In this study, we used l-theanine and l-theanine fecal microbiota solution to treat UC mice to explore the mechanism by which l-theanine alleviates UC. By reducing inflammation in the colon, we demonstrated that l-theanine alleviates symptoms of UC. Meanwhile, l-theanine can improve the abundance of microbiota related to short-chain fatty acid, bile acid, and tryptophan production. Single-cell sequencing results indicated that l-theanine-mediated suppression of UC was associated with immune cell changes, especially regarding macrophages and T and B cells, and validated the immune cell responses to the gut microbiota. Further, flow cytometry results showed that the ability of dendritic cells, macrophages, and monocytes to present microbiota antigens to colonic T cells in an MHC-II-dependent manner was reduced after treating normal mouse fecal donors with l-theanine. These results demonstrate that l-theanine modulates colon adaptive and innate immunity by regulating the gut microbiota in an MHC-II-dependent manner, thereby alleviating UC.

Impaired Epithelial CD200L Tolerance Signaling in Irritable Bowel Syndrome Cases With Diarrhea May Be Associated With Recurrent Miscarriages.

PROBLEM: There is a higher incidence of irritable bowel syndrome with miscarriages, and recurrent miscarriages of otherwise normal embryos have been linked to subnormal expression of the immune checkpoint inhibitor CD200L. We sought to determine if alterations in the expression of the CD200 immune checkpoint inhibitor occur in colonic tissue in IBS-D patients. METHOD OF STUDY: Quantitative immunohistochemical staining of biopsies from proximal and distal colon or rectum for the inhibitory CD200L and CD200S molecules was done. CD56 cells were also enumerated as they play a role in recurrent miscarriages and may express CD200S. RESULTS: CD200L was decreased and CD200S was unchanged in epithelium but not stroma of 3 IBS-D cases. One case had an increase in both CD200L and CD200S. CD56 cells were also stained for CD200S. Degranulation was assessed by the percentage of extracellular CD200S that was increased as epithelial CD200L decreased. CONCLUSIONS: This pilot study was promising and warrants a larger sample to determine if a correlation between uterine implantation site CD200L and CD200S expression in normal and failing implantation sites is needed. Colonic epithelial CD200L may then provide useful information about the pathogenesis of the spontaneous miscarriage in individual cases.

Electroacupuncture at Zusanli regulates the pathological phenotype of inflammatory bowel disease by modulating the NLRP3 inflammasome pathway.

BACKGROUND: This study sought to explore the effect of electroacupuncture (EA) intervention at Zusanli (ST36) acupoint on modulating the NLRP3 inflammasome pathway for treating inflammatory bowel disease (IBD). METHODS: C57BL/6 mice were administrated with 3% dextran sulfate sodium (DSS) to construct the IBD model. DSS mice were then administrated with EA (10 Hz, 1.5 mA) at ST36 for 7 days or intragastric administration of sulfasalazine (SASP) each day during the entire course. The control group animals were administered with distilled water. Then, partial least squares discriminant analysis revealed differences in the relative content of metabolites. The pathological changes of colon and spleen tissues were observed by H&E and immunohistochemistry (IHC) staining. qPCR determined the mRNA expression levels, while ELISA and western blot analysis determined the protein expression. RESULTS: Compared with the control groups, DSS-induced decreases of body weight were reversed after EA stimulation at ST36 or SASP treatment. The DAI of DSS mice was significantly higher relative to the control groups, whereas the DAI of DSS mice were decreased after EA stimulation at ST36 or SASP treatment. The intestinal weight/length ratio increased significantly in DSS groups; however, EA at ST36 significantly improved the macroscopic/microscopic characteristics and the weight and length of the colon. EA reversed inflammation and leukocyte infiltration and normalized the elevated levels of IL-1ß, IL-18, and NLRP3. Furthermore, EA improved the expression levels of ZO-1, occludin, and claudin 1, exhibiting normalization of the colon's tight junctions. CONCLUSIONS: EA at Zusanli acupoint of colon tissue significantly improved the pathological phenotype, showing a therapeutic effect on IBD.

Role of gut microbiota in Crohn's disease pathogenesis: Insights from fecal microbiota transplantation in mouse model.

BACKGROUND: Inflammatory bowel disease, particularly Crohn's disease (CD), has been associated with alterations in mesenteric adipose tissue (MAT) and the phenomenon termed "creeping fat". Histopathological evaluations showed that MAT and intestinal tissues were significantly altered in patients with CD, with these tissues characterized by inflammation and fibrosis. AIM: To evaluate the complex interplay among MAT, creeping fat, inflammation, and gut microbiota in CD. METHODS: Intestinal tissue and MAT were collected from 12 patients with CD. Histological manifestations and protein expression levels were analyzed to determine lesion characteristics. Fecal samples were collected from five recently treated CD patients and five control subjects and transplanted into mice. The intestinal and mesenteric lesions in these mice, as well as their systemic inflammatory status, were assessed and compared in mice transplanted with fecal samples from CD patients and control subjects. RESULTS: Pathological examination of MAT showed significant differences between CD-affected and unaffected colons, including significant differences in gut microbiota structure. Fetal microbiota transplantation (FMT) from clinically healthy donors into mice with 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced CD ameliorated CD symptoms, whereas FMT from CD patients into these mice exacerbated CD symptoms. Notably, FMT influenced intestinal permeability, barrier function, and levels of proinflammatory factors and adipokines. Furthermore, FMT from CD patients intensified fibrotic changes in the colon tissues of mice with TNBS-induced CD. CONCLUSION: Gut microbiota play a critical role in the histopathology of CD. Targeting MAT and creeping fat may therefore have potential in the treatment of patients with CD.

Morin alleviates DSS-induced ulcerative colitis in mice via inhibition of inflammation and modulation of intestinal microbiota.

Ulcerative colitis (UC) is a chronic inflammatory condition with recurrent and challenging symptoms. Effective treatments are lacking, making UC management a critical research area. Morin (MO), a flavonoid from the Moraceae family, shows potential as an anti-UC agent, but its mechanisms are not fully understood. Using a dextran sulfate sodium (DSS)-induced UC mouse model, we employed network pharmacology to predict MO's therapeutic effects. Assessments included changes in body weight, disease activity index (DAI), and colon length. Immunofluorescence, hematoxylin and eosin (H&E), and PAS staining evaluated colon damage. ELISA and western blot analyzed inflammatory factors, tight junction (TJ)-associated proteins (Claudin-3, Occludin, ZO-1), and Mitogen-Activated Protein Kinase (MAPK)/ Nuclear Factor kappa B (NF-κB) pathways. 16S rRNA sequencing assessed gut microbiota diversity, confirmed by MO's modulation via Fecal Microbial Transplantation (FMT). Early MO intervention reduced UC severity by improving weight, DAI scores, and colon length, increasing goblet cells, enhancing barrier function, and inhibiting MAPK/NF-κB pathways. MO enriched gut microbiota, favoring beneficial bacteria like Muribaculaceae and Erysipelotrichaceae while reducing harmful Erysipelotrichaceae and Muribaculaceae. This study highlights MO's potential in UC management through inflammation control, mucosal integrity maintenance, and gut flora modulation.

Proanthocyanidins and ß-Glucan Synergistically Regulate Intestinal Inflammation in Dextran Sulfate Sodium-Induced Colitis Mice.

Proanthocyanidins (PA) have been proven to have an anti-inflammation effect in multiple models by regulating oxidative stress. ß-glucan (BG) could alleviate colitis from the perspectives of intestinal permeability and gut microbiota. In the present study, the synergistic anti-inflammatory function of PA and BG was explored from multiple aspects including immune response, intestinal barrier, gut microbiota, and differential metabolites. The results showed that the supplementation of PA and BG improved the colitis symptoms including atrophy of the colon, body weight loss, and organ index increase. Additionally, inflammatory cytokine levels and oxidative stress status were significantly regulated with the intake of PA and BG. Moreover, PA and BG intervention improved intestinal permeability and promoted the expression of barrier proteins. The microbiome and metabolic profile of cecal contents showed that PA and BG supplementation increased the abundance of anti-inflammatory bacteria and decreased the abundance of pro-inflammatory bacteria. Furthermore, some beneficial metabolites involved in amino acid metabolism, carbohydrate metabolism, and biosynthesis of other secondary metabolite pathways were increased. Overall, these findings have demonstrated the regulation of the inflammatory response and remodel of metabolite profiles by PA and BG complexes, indicating that it may serve as a new strategy for inflammatory bowel disease treatment in the future.