MyD88 mediates the protective effects of probiotics against the arteriolar thrombosis and leukocyte recruitment associated with experimental colitis

Colonization of microbiota derived from Macaca fascicularis, Bama miniature pigs, beagle dogs, and C57BL/6J mice alleviates DSS-induced colitis in germ-free mice

Fecal microbiota transplantation (FMT) is an innovative and promising treatment for inflammatory bowel disease (IBD), which is related to the capability of FMT to supply functional microorganisms to improve recipient gut health. Numerous studies have highlighted considerable variability in the efficacy of FMT interventions for IBD. Several factors, including the composition of the donor microorganisms, significantly affect the efficacy of FMT in the treatment of IBD. Consequently, identifying the functional microorganisms in the donor is crucial for enhancing the efficacy of FMT. To explore potential common anti-inflammatory bacteria with therapeutic implications for IBD, germ-free (GF) BALB/c mice were pre-colonized with fecal microbiota obtained from diverse donors, including Macaca fascicularis (MCC_FMT), Bama miniature pigs (BP_FMT), beagle dogs (BD_FMT), and C57BL/6 J mice (Mice_FMT). Subsequently, mice were treated with dextran sodium sulfate (DSS). As expected, the symptoms of colitis were alleviated by MCC_FMT, BP_FMT, BD_FMT, and Mice_FMT, as demonstrated by the prevention of an elevated disease activity index in mice. Additionally, the utilization of distinct donors protected the intestinal barrier and contributed to the regulation of cytokine homeostasis. Metagenomic sequencing data showed that the microbial community structure and dominant species were significantly different among the four groups, which may be linked to variations in the anti-inflammatory efficacy observed in the respective groups. Notably, Lactobacillus reuteri and Flavonifractor plautii were consistently present in all four groups. L. reuteri exhibited a significant negative correlation with IL-1β, and animal studies further confirmed its efficacy in alleviating IBD, suggesting the presence of common functional bacteria across different donors that exert anti-inflammatory effects. This study provides essential foundational data for the potential clinical applications of FMT.IMPORTANCEDespite variations in efficacy observed among donors, numerous studies have underscored the potential of fecal microbiota transplantation (FMT) for managing inflammatory bowel disease (IBD), indicating the presence of shared anti-IBD bacterial species. In the present study, the collective anti-inflammatory efficacy observed across all four donor groups prompted the identification of two common bacterial species using metagenomics. A significant negative correlation between Lactobacillus reuteri and IL-1β was revealed. Furthermore, mice gavaged with L. reuteri successfully managed the colitis challenge induced by dextran sodium sulfate (DSS), suggesting that L. reuteri may act as an efficacious bacterium mediating shared anti-inflammatory effects among variable donors. This finding highlights the utilization of variable donors to screen FMT core bacteria, which may be a novel strategy for developing FMT applications.

Blocking MyD88 signaling with MyD88 inhibitor prevents colitis-associated colorectal cancer development by maintaining colonic microbiota homeostasis

Certain intestinal microbiota alterations appear to positively correlate with tumorigenesis of CAC due to the disruption of the balance between the host and microorganisms. It is proven that blocking MyD88 signaling can prevent colitis-associated colorectal cancer (CAC) development in mice. We are aim to reveal the role of MyD88 signaling of maintaining colonic microbiota homeostasis for preventing CAC development. We here analyzed the landscape of gut microbiome in the mice model of AOM/DSS-induced CAC with MyD88 inhibitor treatment. PCoA revealed significant reduction in Lactobacillus load and increase in Escherichia load in the mucosal microbial composition of mice with CAC, compared with normal controls (NCs). Inhibitor-treatment led to almost undetectable Proteobacteria (Escherichia) and the retention of the dominance of Firmicutes and Bacteroidota (Muribaculaceae) in the mucosa. RNA sequencing analysis identified genes were up-regulated (Hp, SAA3 and IL-1F9) and down-regulated (CYP3A44, SLC30A10, GPNMB and OTC) in Inhibitor-treated mice (vs. CAC). Meanwhile, Inhibitor-treated mice had higher percentage of MUC2-positive area in colon sections (vs. CAC, which was less than NCs) by IF staining and decreased Escherichia in the mucus layer (vs. CAC) by FISH. And intestinal microbiota from mice with MyD88 inhibitor treatment could lessen the outcome of CAC by fecal microbiota transplantation. The development of CAC was involved in the increasing and ectopic Escherichia in the decreasing colonic mucus layer. MyD88 signaling blockade may maintain the host-microbiota homeostasis by up-regulating MUC2 production, increasing probiotics and their protective effects, and inhibiting the reproduction of Escherichia.

Experimental evidence of shikonin as a novel intervention for anti-inflammatory effects

Shikonin is a natural product with antioxidant and anti-inflammatory activities. The biological activity of shikonin is still not fully understood, as well as its association with innate immunity and immune and inflammatory bowel disease (IBD) in humans. In this study, the toxicity of shikonin on Raw264.7 cells was assayed by MTT, and polarization of inflammatory macrophages was determined by flow cytometry. The results showed that shikonin can inhibit the polarization of macrophages towards M1 type and significantly inhibited the production of NO in the concentration range of 0.5-1 μM. In addition, after treatment with shikonin, the production of IL-1β and TNF-α was significantly decreased. After shikonin administration, the body weight loss and decrease of colon length were significantly suppressed in DSS-treated colitis C57BL/6 mice. The pro-inflammatory cytokines TNF-α and IL-1β in colonic homogenate were significantly decreased. Shikonin treatment resulted in a notable improvement in the histopathological manifestations in DSS-treated animals at 25/50 mg/kg. Meanwhile, we found that shikonin can regulate differentiation of T helper 17 cell (Th17)/regulatory T cell (Treg), thereby regulating the balance of Th17/Treg cells and exerting an anti-inflammatory effect in IBD animal models. In conclusion, we found that shikonin protects against DSS-induced acute colitis by, among other things, reducing immune cell infiltration, polarizing macrophages, and regulating Th17/Treg differentiation, as well as by downregulating the release of inflammatory cytokines. These findings showed that shikonin can improve inflammation by affecting macrophage polarization. Our experimental data provide experimental evidence and theory basis for research on anti-inflammatory effects for the shikonin as health or functional food.

Whole intestinal microbiota transplantation is more effective than fecal microbiota transplantation in reducing the susceptibility of DSS-induced germ-free mice colitis

Fecal microbiota transplantation (FMT) is an emerging and effective therapy for the treatment of inflammatory bowel disease (IBD). Previous studies have reported that compared with FMT, whole intestinal microbiota transplantation (WIMT) can more precisely replicate the community structure and reduce the inflammatory response of the host. However, it remains unclear whether WIMT is more effective in alleviating IBD. To examine the efficacy of WIMT and FMT in the intervention of IBD, GF (Germ-free) BALB/c mice were pre-colonized with whole intestinal microbiota or fecal microbiota before being treated with dextran sodium sulfate (DSS). As expected, the symptoms of colitis were alleviated by both WIMT and FMT, as demonstrated by the prevention of body weight loss and decreased the Disease activity index and histological scores in mice. However, WIMT's anti-inflammatory effect was superior to that of FMT. In addition, the inflammatory markers myeloperoxidase (MPO) and eosinophil peroxidase were dramatically downregulated by WIMT and FMT. Furthermore, the use of two different types of donors facilitated the regulation of cytokine homeostasis in colitis mice; the level of the pro-inflammatory cytokine IL-1β in the WIMT group was significantly lower than that in the FMT group, while the level of the anti-inflammatory factor IL-10 was significantly higher than that in the FMT group. Both groups showed enhanced expression of occludin to protect the intestinal barrier in comparison with the DSS group, and the WIMT group demonstrated considerably increased levels of ZO-1. The sequencing results showed that the WIMT group was highly enriched in Bifidobacterium, whereas the FMT group was significantly enriched in Lactobacillus and Ochrobactrum. Correlation analysis revealed that Bifidobacterium was negatively correlated with TNF-α, whereas Ochrobactrum was positively correlated with MPO and negatively correlated with IL-10, which might be related to different efficacies. Functional prediction using PICRUSt2 revealed that the FMT group was considerably enriched in the L-arginine biosynthesis I and L-arginine biosynthesis IV pathway, whereas the WIMT group was enriched in the L-lysine fermentation to acetate and butanoate pathway. In conclusion, the symptoms of colitis were subsided to varying degrees by the two different types of donors, with the WIMT group being more effective than the FMT group. This study provides new information on clinical interventions for IBD.

Immune cells and their related genes provide a new perspective on the common pathogenesis of ankylosing spondylitis and inflammatory bowel diseases

Background

The close relationship between ankylosing spondylitis (AS) and inflammatory bowel diseases (IBD) has been supported by many aspects, including but not limited to clinical manifestations, epidemiology and pathogenesis. Some evidence suggests that immune cells actively participated in the pathogenesis of both diseases. However, information on which cells are primarily involved in this process and how these cells mobilize, migrate and interact is still limited.

Methods

Datasets were downloaded from Gene Expression Omnibus (GEO) database. Common differentially expressed genes (coDEGs) were identified by package “limma”. The protein-protein interaction (PPI) network and Weighted Gene Co-Expression Network Analysis (WGCNA) were used to analyze the interactions between coDEGs. KEGG pathway enrichment analysis and inverse cumulative distribution function were applied to identify common differential pathways, while Gene Set Enrichment Analysis (GSEA) was used to confirm the significance. Correlation analysis between coDEGs and immune cells led to the identification of critical immune-cell-related coDEGs. The diagnostic models were established based on least absolute shrinkage and selection operator (LASSO) regression, while receiver operating characteristic (ROC) analysis was used to identify the ability of the model. Validation datasets were imported to demonstrate the significant association of coDEGs with specific immune cells and the capabilities of the diagnostic model.

Results

In total, 67 genes were up-regulated and 185 genes were down-regulated in both diseases. Four down-regulated pathways and four up-regulated pathways were considered important. Up-regulated coDEGs were firmly associated with neutrophils, while down-regulated genes were significantly associated with CD8+ T−cells and CD4+ T−cells in both AS and IBD datasets. Five up-regulated and six down-regulated key immue-cell-related coDEGs were identified. Diagnostic models based on key immue-cell-related coDEGs were established and tested. Validation datasets confirmed the significance of the correlation between coDEGs and specific immune cells.

Conclusion

This study provides fresh insights into the co-pathogenesis of AS and IBD. It is proposed that neutrophils and T cells may be actively involved in this process, however, in opposite ways. The immue-cell-related coDEGs, revealed in this study, may be relevant to their regulation, although relevant research is still lacking.

Role of a mixed probiotic product, VSL#3, in the prevention and treatment of colorectal cancer

Colorectal cancer (CRC) is a multifactorial disease. The incidence of this type of cancer in younger patients has increased in recent years, and more strategies are needed to prevent and delay the progression of CRC. Probiotics play an adjunctive role in the prevention and treatment of CRC and can not only prevent the onset and delay the progression of disease but also reduce the side effects after the application of anti-cancer drugs. The anti-cancer effect of individual probiotics has been extensively studied, and the exact curative effect of various probiotics has been found, but the anti-cancer effect of mixed probiotics is still not well summarized. In this review, we discuss the positive effects of mixed probiotics on CRC and the related mechanisms of action, especially VSL#3 (VSL Pharmaceuticals, Inc., Gaithersburg, MD, USA), thus providing new ideas for the treatment of CRC. Moreover, we suggest the need to search for more therapeutic possibilities, especially via the research and application of synbiotics and postbiotics.

Regulating the Imbalance of Gut Microbiota by Smilax china L. Polyphenols to Alleviate Dextran Sulfate Sodium-induced Inflammatory Bowel Diseases

Smilax china L. is used not only as a kind of traditional Chinese herbal medicinal ingredients with various pharmacological properties, but also as food in certain parts of China. However, it is by far still unclear whether Smilax china L. polyphenols (SCP), as important bioactive constituents in Smilax china L., have effects on inflammatory bowel diseases (IBD). This study investigated the impact of SCP on the dextran sulfate sodium (DSS)-induced IBD and gut microbiota in mice. SCP treatments ameliorated typical symptoms of IBD as what was reflected through suppressing body weight loss, colonic shortening, intestinal barrier damage, and increasing intestinal disease activity index. SCP treatments simultaneously decreased the release of proinflammatory cytokines and oxidative stress, as well as promoted the release of anti-inflammatory factors. Furthermore, SCP ameliorated the ecological imbalance of gut microbiota and regulated the key bacteria associated with IBD (including Akkermansiaceae, Ruminococcaceae, Acidaminococcaceae, Muribaculaceae, and Anaeroplasmataceae). In general, SCP may improve DSS-induced IBD in mice by regulating inflammatory factors, inhibiting oxidative stress, reducing intestinal tissue damage, and regulating the ecological imbalance of intestinal microbiota. Thus, SCP might serve as a potential therapeutic agent against the inflammation-driven diseases.

Human Fecal Microbiota Transplantation Reduces the Susceptibility to Dextran Sulfate Sodium-Induced Germ-Free Mouse Colitis

In clinical practice, fecal microbiota transplantation (FMT) has been used to treat inflammatory bowel disease (IBD), and has shown certain effects. However, the selection of FMT donors and the mechanism underlying the effect of FMT intervention in IBD require further exploration. In this study, dextran sodium sulfate (DSS)-induced colitis mice were used to determine the differences in the protection of colitis symptoms, inflammation, and intestinal barrier, by FMT from two donors. Intriguingly, pre-administration of healthy bacterial fluid significantly relieved the symptoms of colitis compared to the ulcerative colitis (UC) bacteria. In addition, healthy donor (HD) bacteria significantly reduced the levels of inflammatory markers Myeloperoxidase (MPO) and Eosinophil peroxidase (EPO), and various pro-inflammatory factors, in colitis mice, and increased the secretion of the anti-inflammatory factor IL-10. Metagenomic sequencing indicated higher species diversity and higher abundance of anti-inflammatory bacteria in the HD intervention group, including Alistipes putredinis, Akkermansia muciniphila, Bifidobacterium adolescentis, short-chain fatty acids (SCFAs)-producing bacterium Christensenella minuta, and secondary bile acids (SBAs)-producing bacterium Clostridium leptum. In the UC intervention group, the SCFA-producing bacterium Bacteroides stercoris, IBD-related bacterium Ruminococcus gnavus, Enterococcus faecalis, and the conditional pathogen Bacteroides caccae, were more abundant. Metabolomics analysis showed that the two types of FMT significantly modulated the metabolism of DSS-induced mice. Moreover, compared with the UC intervention group, indoleacetic acid and unsaturated fatty acids (DHA, DPA, and EPA) with anti-inflammatory effects were significantly enriched in the HD intervention group. In summary, these results indicate that FMT can alleviate the symptoms of colitis, and the effect of HD intervention is better than that of UC intervention. This study offers new insights into the mechanisms of FMT clinical intervention in IBD.

Colonization with Altered Schaedler Flora Impacts Leukocyte Adhesion in Mesenteric Ischemia-Reperfusion Injury

The microbiota impacts mesenteric ischemia-reperfusion injury, aggravating the interaction of leukocytes with endothelial cells in mesenteric venules. The role of defined gut microbiomes in this life-threatening pathology is unknown. To investigate how a defined model microbiome affects the adhesion of leukocytes in mesenteric ischemia-reperfusion, we took advantage of gnotobiotic isolator technology and transferred altered Schaedler flora (ASF) from C3H/HeNTac to germ-free C57BL/6J mice. We were able to detect all eight bacterial taxa of ASF in fecal samples of colonized C57BL/6J mice by PCR. Applying qRT-PCR for quantification of species-specific 16S rDNA sequences of ASF bacteria, we found a major shift in the abundance of ASF 500, which was greater in C57BL/6J mice relative to the C3H/HeNTac founder breeding pair. Using high-speed epifluorescence intravital microscopy to visualize the venules of the small bowel mesentery, we found that gnotobiotic ASF-colonized mice showed reduced leukocyte adherence, both pre- and post-ischemia. Relative to germ-free mice, the counts of adhering leukocytes were increased pre-ischemia but did not significantly increase in ASF-colonized mice in the post-ischemic state. Collectively, our results suggest a protective role of the minimal microbial consortium ASF in mesenteric ischemia-reperfusion injury.

Pediococcus pentosaceus LI05 alleviates DSS-induced colitis by modulating immunological profiles, the gut microbiota and short-chain fatty acid levels in a mouse model

The gut microbiota is considered a key factor in pathogenesis and progression of inflammatory bowel disease (IBD). The bacterium Pediococcus pentosaceus LI05 alleviated host inflammation by maintaining the gut epithelial integrity, modulating the host immunity, gut microbiota and metabolism, but its effect on IBD remains unclear. The present study aimed to investigate the role and mechanisms of P. pentosaceus LI05. Mice were administered P. pentosaceus LI05 or phosphate-buffered saline once daily by oral gavage for 14 days, and colitis was induced by providing mice 2% DSS-containing drinking water for 7 days. P. pentosaceus LI05 ameliorated colitis in mice and reduced the body weight loss, disease activity index (DAI) scores, colon length shortening, intestinal permeability and the proinflammatory cytokine levels. Furthermore, a significantly altered gut microbiota composition with increased diversity and short-chain fatty acid (SCFA) production was observed in mice treated with P. pentosaceus LI05. Several genera, including Akkermansia and Faecalibacterium, were differentially enriched in the P. pentosaceus LI05-treated mice and were negatively correlated with colitis indices and positively correlated with gut barrier markers and SCFA levels. The P. pentosaceus LI05 treatment alleviated intestinal inflammation by maintaining the intestinal epithelial integrity and modulating the immunological profiles, gut microbiome and metabolite composition. Based on our findings, P. pentosaceus LI05 might be applied as potential preparation to ameliorate colitis.

Administration of Akkermansia muciniphila Ameliorates Dextran Sulfate Sodium-Induced Ulcerative Colitis in Mice

Inflammatory bowel diseases (IBDs) develop as a result of complex interactions among genes, innate immunity and environmental factors, which are related to the gut microbiota. Multiple clinical and animal data have shown that Akkermansia muciniphila is associated with a healthy mucosa. However, its precise role in colitis is currently unknown. Our study aimed to determine its protective effects and underlying mechanisms in a dextran sulfate sodium (DSS)-induced colitis mouse model. Twenty-four C57BL/6 male mice were administered A. muciniphila Muc^T or phosphate-buffered saline (PBS) once daily by oral gavage for 14 days. Colitis was induced by drinking 2% DSS from days 0 to 6, followed by 2 days of drinking normal water. Mice were weighed daily and then sacrificed on day 8. We found that A. muciniphila improved DSS-induced colitis, which was evidenced by reduced weight loss, colon length shortening and histopathology scores and enhanced barrier function. Serum and tissue levels of inflammatory cytokines and chemokines (TNF-α, IL1α, IL6, IL12A, MIP-1A, G-CSF, and KC) decreased as a result of A. muciniphila administration. Analysis of 16S rDNA sequences showed that A. muciniphila induced significant gut microbiota alterations. Furthermore, correlation analysis indicated that pro-inflammatory cytokines and other injury factors were negatively associated with Verrucomicrobia, Akkermansia, Ruminococcaceae, and Rikenellaceae, which were prominently abundant in A. muciniphila-treated mice. We confirmed that A. muciniphila treatment could ameliorate mucosal inflammation either via microbe-host interactions, which protect the gut barrier function and reduce the levels of inflammatory cytokines, or by improving the microbial community. Our findings suggest that A. muciniphila may be a potential probiotic agent for ameliorating colitis.

Lactobacillus brevis Alleviates DSS-Induced Colitis by Reprograming Intestinal Microbiota and Influencing Serum Metabolome in Murine Model

The aim of this study was to examine the effects of Lactobacillus brevis on the microbial community and serum metabolome in colitis induced by dextran sulfate sodium (DSS). ICR mice were randomly distributed into three treatment groups: (i) L. brevis treatment alone (control), (ii) DSS administration alone, and (iii) treatment with L. brevis and DSS. Our results demonstrate that L. brevis treatment significantly alleviated DSS-induced body weight loss and colon inflammation. In addition, LC-MS analysis of serum metabolites revealed that L. brevis treatment increased the serum level of metabolites against inflammatory responses or oxidative stressors caused by DSS in the murine model. By detecting colonic microbiota, L. brevis increased colonic microbial diversity after challenging with DSS, and increased the relative abundance of Alloprevotella at genus, but Bacteroidales was reduced (P < 0.05). These result indicated that L. brevis could lower the severity of colitis induced by DSS via improving reprogramming the serum metabolome and intestinal microbiota. These findings suggest that the probiotic L. brevis may prevent tissue damage from colitis.

Curcumin induces mild anemia in a DSS-induced colitis mouse model maintained on an iron-sufficient diet

Anemia is frequently encountered in patients with inflammatory bowel disease (IBD), decreasing the quality of life and significantly worsening the prognosis of the disease. The pathogenesis of anemia in IBD is multifactorial and results mainly from intestinal blood loss in inflamed mucosa and impaired dietary iron absorption. Multiple studies have proposed the use of the polyphenolic compound curcumin to counteract IBD pathogenesis since it has significant preventive and therapeutic properties as an anti-inflammatory agent and very low toxicity, even at high dosages. However, curcumin has been shown to possess properties consistent with those of an iron-chelator, such as the ability to modulate proteins of iron metabolism and decrease spleen and liver iron content. Thus, this property may further contribute to the development and severity of anemia of inflammation and iron deficiency in IBD. Herein, we evaluate the effects of curcumin on systemic iron balance in the dextran sodium sulfate (DSS) model of colitis in C57Bl/6 and BALB/c mouse strains that were fed an iron-sufficient diet. In these conditions, curcumin supplementation caused mild anemia, lowered iron stores, worsened colitis and significantly decreased overall survival, independent of the mouse strain. These findings suggest that curcumin usage as an anti-inflammatory supplement should be accompanied by monitoring of erythroid parameters to avoid exacerbation of iron deficiency anemia in IBD.

Probiotic mixture VSL#3 reduces colonic inflammation and improves intestinal barrier function in Muc2 mucin-deficient mice

MUC2 mucin is the major glycoprotein in colonic mucus that separates intestinal microbiota from underlying host cells and serves as a food source for some eubacteria. MUC2 deficiency results in impaired epithelial barrier function, imbalance in gut microbiota, and spontaneous colitis. Probiotics have been shown to have a protective effect against colitis. In this study we used Muc2 mucin-deficient (Muc2^-/-) and Muc2^+/+ littermates to test whether the probiotic mixture VSL#3 requires an intact mucin barrier to exert its beneficial effect. VSL#3 alone reduced basal colonic proinflammatory cytokine levels and improved epithelial barrier function in Muc2^-/- animals. Similarly, in dextran sulfate sodium-induced colitis, VSL#3 dampened the proinflammatory chemokines KC, monocyte chemoattractant protein-1, and macrophage inflammatory protein-2 and upregulated the tissue regeneration growth factors transforming growth factor-β, fibroblast growth factor-1, and vascular endothelial growth factor-A, which accelerated resolution of colitis symptoms in Muc2^-/- animals. Importantly, improved colonic health in VSL#3-treated animals was associated with attenuated reactive oxygen species production by peritoneal macrophages, restoration of antimicrobial peptide gene expression in the small intestine, and increased abundance of bacterial commensals in the gut. The beneficial effects of VSL#3 in Muc2^-/- animals were mediated by acetate, an important short-chain fatty acid produced by gut bacteria. These studies provide evidence for the first time that VSL#3 can enhance epithelial barrier function by dampening the proinflammatory cytokine and chemokine response, accelerating restitution, and altering commensal microbiota in the absence of a functional mucus barrier.

NEW & NOTEWORTHY

It is unclear whether probiotics require an intact mucin barrier to first colonize and/or exert their protective functions. In this study we used mucin-deficient (Muc2^-/-) mice to interrogate if the multispecies probiotic mixture VSL#3 could enhance epithelial barrier function. In the absence of a mucus bilayer, VSL#3 dampened proinflammatory and chemokine production, accelerated restitution, and markedly improved gut permeability mediated by the short-chain fatty acid acetate in the colon.