Upregulation of Intestinal Barrier Function in Mice with DSS-Induced Colitis by a Defined Bacterial Consortium Is Associated with Expansion of IL-17A Producing Gamma Delta T Cells

Improvement of the inflammation-damaged intestinal barrier and modulation of the gut microbiota in ulcerative colitis after FMT in the SHIME® model

BACKGROUND

Fecal microbiota transplantation (FMT) seems to be a promising approach in ulcerative colitis (UC) management with the aim of repopulating a patient's dysbiotic microbiota with beneficial bacteria and restore its metabolic activity to its healthy characteristics. Metabolites present after FMT may improve the function and integrity of the intestinal barrier, reduce inflammation, and thus induce remission in an UC patient. In this study we evaluated whether the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) model may be a suitable non-invasive alternative for studying and modifying the dysbiotic microbiota in UC by FMT application.

METHODS

SHIME® model was used to investigate microbial and metabolic changes in the gut microbiota of UC patient induced by FMT application. FMT-modified metabolites from SHIME® were applied to an in vitro model of the intestinal barrier (differentiated Caco-2 and HT-29-MTX-E12 cell lines) compromised by pro-inflammatory cytokines to study the effect of FMT on the intestinal barrier.

RESULTS

Qualitative and quantitative microbial analyses showed that FMT increased the diversity and variability of the microbiota in UC patient associated with a significant increase in total bacteria, Bacteroidota and Lactobacillus, as well as an increase in butyrate levels. In addition, an increase in the relative abundance of some important species such as Faecalibacterium prausnitzii and Bifidobacterium longum was observed, and there was also an enrichment of the microbiota with new species such as Blautia obeum, Roseburia faecis, Bifidobacterium adolescentis, Fusicatenibacter saccharivorans and Eubacterium rectale. Furthermore, microbial metabolites modulated by FMT from the SHIME® model prevented intestinal barrier damage and inhibited interleukin 8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1) secretion when cell barriers were pretreated with FMT medium for 24 h. In summary, this study confirmed that a single dose of FMT beneficially modulated the composition and metabolic activity of the UC microbiota in the SHIME® model.

CONCLUSIONS

FMT favorably modulates the gut microbiota of UC patient cultured in the SHIME® model. FMT-modulated SHIME-derived microbial metabolites improve intact and inflamed intestinal barrier properties in vitro. Repeated applications are necessary to maintain the beneficial effect of FMT in SHIME® model.

Gut Microbiota Regulates the Homeostasis of Dendritic Epidermal T Cells

Dendritic epidermal T cells (DETCs) are a γδ T cell subset residing in the skin epidermis. Although they have been known for decades, the fate of DETCs has largely remained enigmatic. Recent studies have highlighted the relationship between the gut microbiome and γδ T cells in various epithelial and non-epithelial tissues, such as the small intestine, lung, liver, gingiva, and testis. While the skin microbiota has been shown to impact skin γδ T cells, a direct relationship between the gut microbiota and DETCs remains unexplored. In this study, we investigated whether DETCs are regulated by the gut microbiota in the steady-state skin epidermis. We examined the occurrence of DETCs in Balb/c mice, which have a skin epidermis barely populated with DETCs, compared to C57BL/6 mice, under different housing conditions. Our findings reveal that local skin inflammation markedly increases DETC numbers in the ear epidermis of Balb/c mice and that DETCs are activated by environmental factors. Furthermore, an investigation of the gut microbiota under different housing conditions revealed distinct microbial compositions and functional profiles. Taken together, these results suggest a strong connection between DETCs and gut microbiota.

Gut microbiota mediated T cells regulation and autoimmune diseases

Gut microbiota regulates the immune system, the development and progression of autoimmune diseases (AIDs) and overall health. Recent studies have played a crucial part in understanding the specific role of different gut bacterial strains and their metabolites in different AIDs. Microbial signatures in AIDs are revealed by advanced sequencing and metabolomics studies. Microbes such as Faecalibacterium prausnitzii, Akkermansia muciniphila, Anaerostipes caccae, Bacteroides sp., Roseburia sp., Blautia sp., Blautia faecis, Clostridium lavalense, Christensenellaceae sp., Coprococcus sp., Firmicutes sp., Ruminococcaceae sp., Lachnospiraceae sp., Megamonas sp., Monoglobus sp., Streptococcus pneumoniae and Bifidobacterium sp. help maintain immune homeostasis; whereas, Prevotella copri, Ruminococcus gnavus, Lactobacillus salivarius, Enterococcus gallinarum, Elizabeth menigoseptica, Collinsella sp., Escherichia sp., Fusobacterium sp., Enterobacter ludwigii, Enterobacteriaceae sp., Proteobacteria, Porphyromonas gingivalis, Porphyromonas nigrescens, Dorea sp., and Clostridium sp. cause immuno-pathogenesis. A complex web of interactions is revealed by understanding the influence of gut microbiota on immune cells and various T cell subsets such as CD4+ T cells, CD8+ T cells, natural killer T cells, γδ T cells, etc. Certain AIDs, including rheumatoid arthritis, diabetes mellitus, atopic asthma, inflammatory bowel disease and non-alcoholic fatty liver disease exhibit a state of dysbiosis, characterized by alterations in microbial diversity and relative abundance of specific taxa. This review summarizes recent developments in understanding the role of certain microbiota composition in specific AIDs, and the factors affecting specific regulatory T cells through certain microbial metabolites and also focuses the potential application and therapeutic significance of gut microbiota-based interventions as novel adjunctive therapies for AIDs. Further research to determine the precise association of each gut bacterial strain in specific diseases is required.

Environmental and inflammatory factors influencing concurrent gut and lung inflammation

BACKGROUND

Crohn's disease and chronic obstructive pulmonary disease (COPD) are chronic inflammatory diseases that affect the gut and lung respectively and can occur comorbidly.

METHODS

Using the SHIP-1-/- model of Crohn's-like ileitis and chronic lung inflammation, the two diseases were co-investigated.

RESULTS

Contrary to prior literature, Crohn's-like ileitis was not fully penetrant in SHIP-1-/- mice, and housing in a specific pathogen-free facility was completely protective. Indeed, ileal tissue from SHIP-1-/- mice without overt ileitis was similar to control ilea. However, SHIP-1-/- mice with ileitis exhibited increased granulocytes in ileal tissue together with T cell lymphopenia and they lacked low abundance Bifidobacteria, suggesting this bacterium protects against ileitis. Lung disease, as defined by inflammation in lung washes, emphysema, and lung consolidation, was present in SHIP-1-/- mice regardless of ileitis phenotype; however, there was a shift in the nature of lung inflammation in animals with ileitis, with increased G-CSF and neutrophils, in addition to type 2 cytokines and eosinophils. Deficiency of G-CSF, which protects against lung disease, protected against the development of ileitis in SHIP-1-/- mice.

CONCLUSIONS

These studies have defined environmental, immune, and inflammatory factors that predispose to ileitis, and have identified that comorbid lung disease correlates with a granulocyte signature.

Combining Metagenomics, Network Pharmacology and RNA-Seq Strategies to Reveal the Therapeutic Effects and Mechanisms of Qingchang Wenzhong Decoction on Inflammatory Bowel Disease in Mice

Background

Inflammatory bowel disease (IBD) is a chronic and recurrent inflammatory disease that lacks effective treatments. Qingchang Wenzhong Decoction (QCWZD) is a clinically effective herbal prescription that has been proven to attenuate intestinal inflammation in IBD. However, its molecular mechanism of action has not been clearly elucidated.

Purpose

We aimed to probe the mechanism of QCWZD for the treatment of IBD.

Methods

The dextran sulfate sodium (DSS)-induced mouse model of IBD was used to identify the molecular targets involved in the mechanism of action of QCWZD. Metagenomics sequencing was utilized to analyze the differences in gut microbiota and the functional consequences of these changes. Network pharmacology combined with RNA sequencing (RNA-seq) were employed to predict the molecular targets and mechanism of action of QCWZD, and were validated through in vivo experiments.

Results

Our results demonstrated that QCWZD treatment alleviated intestinal inflammation and accelerated intestinal mucosal healing that involved restoration of microbial homeostasis. This hypothesis was supported by the results of bacterial metagenomics sequencing that showed attenuation of gut dysbiosis by QCWZD treatment, especially the depletion of the pathogenic bacterial genus Bacteroides, while increasing the beneficial microorganism Akkermansia muciniphila that led to altered bacterial gene functions, such as metabolic regulation. Network pharmacology and RNA-seq analyses showed that Th17 cell differentiation plays an important role in QCWZD-based treatment of IBD. This was confirmed by in vivo experiments showing a marked decrease in the percentage of CD3+CD4+IL-17+ (Th17) cells. Furthermore, our results also showed that the key factors associated with Th17 cell differentiation (IL-17, NF-κB, TNF-α and IL-6) in the colon were significantly reduced in QCWZD-treated colitis mice.

Conclusion

QCWZD exerted beneficial effects in the treatment of IBD by modulating microbial homeostasis while inhibiting Th17 cell differentiation and its associated pathways, providing a novel and promising therapeutic strategy for the treatment of IBD.

Mechanism of Action and Therapeutic Implications of Nrf2/HO-1 in Inflammatory Bowel Disease

Oxidative stress (OS) is a key factor in the generation of various pathophysiological conditions. Nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) is a major transcriptional regulator of antioxidant reactions. Heme oxygenase-1 (HO-1), a gene regulated by Nrf2, is one of the most critical cytoprotective molecules. In recent years, Nrf2/HO-1 has received widespread attention as a major regulatory pathway for intracellular defense against oxidative stress. It is considered as a potential target for the treatment of inflammatory bowel disease (IBD). This review highlights the mechanism of action and therapeutic significance of Nrf2/HO-1 in IBD and IBD complications (intestinal fibrosis and colorectal cancer (CRC)), as well as the potential of phytochemicals targeting Nrf2/HO-1 in the treatment of IBD. The results suggest that the therapeutic effects of Nrf2/HO-1 on IBD mainly involve the following aspects: (1) Controlling of oxidative stress to reduce intestinal inflammation and injury; (2) Regulation of intestinal flora to repair the intestinal mucosal barrier; and (3) Prevention of ferroptosis in intestinal epithelial cells. However, due to the complex role of Nrf2/HO-1, a more nuanced understanding of the exact mechanisms involved in Nrf2/HO-1 is the way forward for the treatment of IBD in the future.

SENP2 restrains the generation of pathogenic Th17 cells in mouse models of colitis

The molecular mechanisms contributing to the regulation of Th17-mediated inflammation remain underexplored. We here report a SUMO-specific protease (SENP)2-mediated pathway induced in pathogenic Th17 cells that restricts the pathogenesis of inflammatory colitis. SENP2 regulates the maturation of small ubiquitin-like modifiers (SUMO) and recycles SUMO from the substrate proteins. We find higher levels of SENP2 in pathogenic Th17 cells. By deleting Senp2 in T-cell lineages in mice, we demonstrate that the lack of Senp2 exacerbates the severity of experimental colitis, which is linked to elevated levels of GM-CSF+IL-17A+ pathogenic Th17 cells and more severe dysbiosis of the intestinal microbiome. Adoptive transfer experiments demonstrate the cell-autonomous effect of Senp2 in restraining Th17 differentiation and colitis. The enzymatic activity of SENP2 is important for deSUMOylation of Smad4, which reduces Smad4 nuclear entry and Rorc expression. Our findings reveal a SENP2-mediated regulatory axis in the pathogenicity of Th17 cells.

Expression and significant roles of the lncRNA NEAT1/miR-493-5p/Rab27A axis in ulcerative colitis

BACKGROUND

Long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) have been reported to play regulatory roles in ulcerative colitis (UC). In this study, we aimed to determine the specific roles and action mechanism of the nuclear paraspeckle assembly transcript 1 (NEAT1) in UC.

METHODS

Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to determine the lncRNA NEAT1 and miR-493-5p expression levels in patients with UC and healthy volunteers. We determine the forecast linkage points of NEAT1 and miR-493-5p using Starbase and those of miR-493-5p and Rab27A using TargetScan, and further verified them using a double luciferase gene reporter kit. RT-qPCR and Western blot analysis were used to determine the lncRNA NEAT1, miR-493-5p, and Rab27A expression levels in lipopolysaccharide (LPS)-induced Caco-2 cells. Flow cytometry and cell counting kit-8 were used to assess Caco-2 cell viability. Tumor necrosis factor-α, interleukin (IL)-6, IL-8, and IL-1β levels were determined via an enzyme-linked immunosorbent assay.

RESULTS

Expression levels of NEAT1 were upregulated and those of miR-493-5p were downregualted in 10 ng/mL LPS-treated Caco-2 cells and patients with UC. Dual-luciferase gene reporter assay revealed that miR-493-5p is linked to NEAT1, and Rab27A is a downstream target of miR-493-5p. Overexpression of miR-493-5p inhibited the apoptosis and inflammation in LPS-treated Caco-2 cells. Moreover, downregulation of lncRNA NEAT1 expression also inhibited the apoptosis and inflammation in LPS-treated Caco-2 cells, which was reversed by Rab27A plasmid cotransfection.

CONCLUSION

Our results revealed that NEAT1 participates in UC progression by inhibiting miR-493-5p expression.

Inulin diet uncovers complex diet-microbiota-immune cell interactions remodeling the gut epithelium

BACKGROUND

The continuous proliferation of intestinal stem cells followed by their tightly regulated differentiation to epithelial cells is essential for the maintenance of the gut epithelial barrier and its functions. How these processes are tuned by diet and gut microbiome is an important, but poorly understood question. Dietary soluble fibers, such as inulin, are known for their ability to impact the gut bacterial community and gut epithelium, and their consumption has been usually associated with health improvement in mice and humans. In this study, we tested the hypothesis that inulin consumption modifies the composition of colonic bacteria and this impacts intestinal stem cells functions, thus affecting the epithelial structure.

METHODS

Mice were fed with a diet containing 5% of the insoluble fiber cellulose or the same diet enriched with an additional 10% of inulin. Using a combination of histochemistry, host cell transcriptomics, 16S microbiome analysis, germ-free, gnotobiotic, and genetically modified mouse models, we analyzed the impact of inulin intake on the colonic epithelium, intestinal bacteria, and the local immune compartment.

RESULTS

We show that the consumption of inulin diet alters the colon epithelium by increasing the proliferation of intestinal stem cells, leading to deeper crypts and longer colons. This effect was dependent on the inulin-altered gut microbiota, as no modulations were observed in animals deprived of microbiota, nor in mice fed cellulose-enriched diets. We also describe the pivotal role of γδ T lymphocytes and IL-22 in this microenvironment, as the inulin diet failed to induce epithelium remodeling in mice lacking this T cell population or cytokine, highlighting their importance in the diet-microbiota-epithelium-immune system crosstalk.

CONCLUSION

This study indicates that the intake of inulin affects the activity of intestinal stem cells and drives a homeostatic remodeling of the colon epithelium, an effect that requires the gut microbiota, γδ T cells, and the presence of IL-22. Our study indicates complex cross kingdom and cross cell type interactions involved in the adaptation of the colon epithelium to the luminal environment in steady state. Video Abstract.

Protective role of circRNA CCND1 in ulcerative colitis via miR-142-5p/NCOA3 axis

BACKGROUND

Increasing research indicates that circular RNAs (circRNAs) play critical roles in the development of ulcerative colitis (UC). This study aimed to determine the role of circRNA CCND1 in UC bio-progression, which has been shown to be downregulated in UC tissues.

METHODS

Reverse transcription quantitative polymerase chain reaction was used to determine the levels of circRNA CCND1, miR-142-5p, and nuclear receptor coactivator-3 (NCOA3) in UC tissues and in lipopolysaccharide (LPS)-induced Caco-2 cells. Target sites of circRNA CCND1 and miR-142-5p were predicted using StarBase, and TargetScan to forecast potential linkage points of NCOA3 and miR-142-5p, which were confirmed by a double luciferase reporter-gene assay. Cell Counting Kit 8 and flow cytometry assays were performed to assess Caco-2 cell viability and apoptosis. TNF-α, IL-1β, IL-6, and IL-8 were detected using Enzyme-Linked Immunosorbent Assay kits.

RESULTS

CircRNA CCND1 was downregulated in UC clinical samples and LPS-induced Caco-2 cells. In addition, circRNA CCND1 overexpression suppressed LPS-induced apoptosis and inflammatory responses in Caco-2 cells. Dual-luciferase reporter-gene assays showed that miR-142-5p could be linked to circRNA CCND1. Moreover, miR-142-5p was found to be highly expressed in UC, and its silencing inhibited LPS-stimulated Caco-2 cell apoptosis and inflammatory responses. Importantly, NCOA3 was found downstream of miR-142-5p. Overexpression of miR-142-5p reversed the inhibitory effect of circRNA CCND1-plasmid on LPS-stimulated Caco-2 cells, and the effects of miR-142-5p inhibitor were reversed by si-NCOA3.

CONCLUSION

CircRNA CCND1 is involved in UC development by dampening miR-142-5p function, and may represent a novel approach for treating UC patients.

Evolutionary Insights Into Microbiota Transplantation in Inflammatory Bowel Disease

The intestinal microbiome plays an essential role in human health and disease status. So far, microbiota transplantation is considered a potential therapeutic approach for treating some chronic diseases, including inflammatory bowel disease (IBD). The diversity of gut microbiota is critical for maintaining resilience, and therefore, transplantation with numerous genetically diverse gut microbiota with metabolic flexibility and functional redundancy can effectively improve gut health than a single probiotic strain supplement. Studies have shown that natural fecal microbiota transplantation or washing microbiota transplantation can alleviate colitis and improve intestinal dysbiosis in IBD patients. However, unexpected adverse reactions caused by the complex and unclear composition of the flora limit its wider application. The evolving strain isolation technology and modifiable pre-existing strains are driving the development of microbiota transplantation. This review summarized the updating clinical and preclinical data of IBD treatments from fecal microbiota transplantation to washing microbiota transplantation, and then to artificial consortium transplantation. In addition, the factors considered for strain combination were reviewed. Furthermore, four types of artificial consortium transplant products were collected to analyze their combination and possible compatibility principles. The perspective on individualized microbiota transplantation was also discussed ultimately.

Caecal microbiota composition of experimental inbred MHC-B lines infected with IBV differs according to genetics and vaccination

Interactions between the gut microbiota and the immune system may be involved in vaccine and infection responses. In the present study, we studied the interactions between caecal microbiota composition and parameters describing the immune response in six experimental inbred chicken lines harboring different MHC haplotypes. Animals were challenge-infected with the infectious bronchitis virus (IBV), and half of them were previously vaccinated against this pathogen. We explored to what extent the gut microbiota composition and the genetic line could be related to the immune response, evaluated through flow cytometry. To do so, we characterized the caecal bacterial communities with a 16S rRNA gene amplicon sequencing approach performed one week after the IBV infectious challenge. We observed significant effects of both the vaccination and the genetic line on the microbiota after the challenge infection with IBV, with a lower bacterial richness in vaccinated chickens. We also observed dissimilar caecal community profiles among the different lines, and between the vaccinated and non-vaccinated animals. The effect of vaccination was similar in all the lines, with a reduced abundance of OTU from the Ruminococcacea UCG-014 and Faecalibacterium genera, and an increased abundance of OTU from the Eisenbergiella genus. The main association between the caecal microbiota and the immune phenotypes involved TCR_ϒδ expression on TCR_ϒδ⁺ T cells. This phenotype was negatively associated with OTU from the Escherichia-Shigella genus that were also less abundant in the lines with the highest responses to the vaccine. We proved that the caecal microbiota composition is associated with the IBV vaccine response level in inbred chicken lines, and that the TCR_ϒδ⁺ T cells (judged by TCR_ϒδ expression) may be an important component involved in this interaction, especially with bacteria from the Escherichia-Shigella genus. We hypothesized that bacteria from the Escherichia-Shigella genus increased the systemic level of bacterial lipid antigens, which subsequently mitigated poultry γδ T cells.

The role of γδ T cells in the interaction between commensal and pathogenic bacteria in the intestinal mucosa

The intestinal mucosa is an important structure involved in resistance to pathogen infection. It is mainly composed of four barriers, which have different but interrelated functions. Pathogenic bacteria can damage these intestinal mucosal barriers. Here, we mainly review the mechanisms of pathogen damage to biological barriers. Most γδ T cells are located on the surface of the intestinal mucosa, with the ability to migrate and engage in crosstalk with microorganisms. Commensal bacteria are involved in the activation and migration of γδ T cells to monitor the invasion of pathogens. Pathogen invasion alters the migration pattern of γδ T cells. γδ T cells accelerate pathogen clearance and limit opportunistic invasion of commensal bacteria. By discussing these interactions among γδ T cells, commensal bacteria and pathogenic bacteria, we suggest that γδ T cells may link the interactions between commensal bacteria and pathogenic bacteria.

Gut barrier disruption and chronic disease

The intestinal barrier protects the host against gut microbes, food antigens, and toxins present in the gastrointestinal tract. However, gut barrier integrity can be affected by intrinsic and extrinsic factors, including genetic predisposition, the Western diet, antibiotics, alcohol, circadian rhythm disruption, psychological stress, and aging. Chronic disruption of the gut barrier can lead to translocation of microbial components into the body, producing systemic, low-grade inflammation. While the association between gut barrier integrity and inflammation in intestinal diseases is well established, we review here recent studies indicating that the gut barrier and microbiota dysbiosis may contribute to the development of metabolic, autoimmune, and aging-related disorders. Emerging interventions to improve gut barrier integrity and microbiota composition are also described.

Elucidating the Calcium-Binding Site, Absorption Activities, and Thermal Stability of Egg White Peptide-Calcium Chelate

With the current study, we aimed to determine the characteristics and calcium absorption capacity of egg white peptide-calcium complex (EWP-Ca) and determine the effect of sterilization on EWP-Ca to study the possibility of EWP-Ca as a new potential calcium supplement. The results of SEM and EDS showed a high calcium chelating ability between EWP and calcium, and the structure of EWP-Ca was clustered spherical particles due its combination with calcium. The FTIR and Raman spectrum results showed that EWP could chelate with calcium by carboxyl, phosphate, and amino groups, and peptide bonds may also participate in peptide-calcium binding. Moreover, the calcium absorption of EWP-Ca measured by the intestinal everted sac model in rats was 32.38 ± 6.83 μg/mL, significantly higher than the sample with CaCl2, and the mixture of EWP and Ca (p < 0.05) revealed appropriate calcium absorption capacity. The fluorescence spectra and CD spectra showed that sterilization caused a decrease in the content of α-helix and β-sheet and a significant increase in β-turn (p < 0.05). Sterilization changed the EWP-Ca structure and decreased its stability; the calcium-binding capacity of EWP-Ca after sterilization was decreased to 41.19% (p < 0.05). Overall, these findings showed that EWP could bind with calcium, form a peptide-calcium chelate, and serve as novel carriers for calcium supplements.

Administration of a Probiotic Mixture Ameliorates Cisplatin-Induced Mucositis and Pica by Regulating 5-HT in Rats

Probiotic-based therapies have been shown to be beneficial for chemotherapy-induced mucositis. Previous research has demonstrated that a probiotic mixture (Bifidobacterium brevis, Lactobacillus acidophilus, Lactobacillus casei, and Streptococcus thermophilus) can ameliorate chemotherapy-induced mucositis and dysbiosis in rats, but the underlying mechanism has not been completely elucidated. We aimed to determine the inhibitory effects of the probiotic mixture on cisplatin-induced mucositis and pica and the underlying mechanism, focusing on the levels of 5-hydroxytryptamine (5-HT, serotonin) regulated by the gut microbiota. A rat model of mucositis and pica was established by daily intraperitoneal injection of cisplatin (6 mg/kg) for 3 days. In the probiotic+cisplatin group, predaily intragastric injection of the probiotic mixture (1 × 109 CFU/kg BW) was administrated for 1 week before cisplatin injection. This was then followed by further daily probiotic injections for 6 days. Histopathology, pro-/anti-inflammatory cytokines, oxidative status, and 5-HT levels were assessed on days 3 and 6. The structure of the gut microbiota was analyzed by 16S rRNA gene sequencing and quantitative PCR. Additionally, 5-HT levels in enterochromaffin (EC) cells (RIN-14B cell line) treated with cisplatin and/or various probiotic bacteria were also determined. The probiotic mixture significantly attenuated kaolin consumption, inflammation, oxidative stress, and the increase in 5-HT concentrations in rats with cisplatin-induced intestinal mucositis and pica. Cisplatin markedly increased the relative abundances of Enterobacteriaceae_other, Blautia, Clostridiaceae_other, and members of Clostridium clusters IV and XIVa. These levels were significantly restored by the probiotic mixture. Importantly, most of the genera increased by cisplatin were significantly positively correlated with colonic 5-HT. Furthermore, in vitro, the probiotic mixture had direct inhibitory effects on the 5-HT secretion by EC cells. The probiotic mixture protects against cisplatin-induced intestine injury, exhibiting both anti-inflammatory and antiemetic properties. These results were closely related to the reestablishment of intestinal microbiota ecology and normalization of the dysbiosis-driven 5-HT overproduction.

Circadian disruption-induced metabolic syndrome in mice is ameliorated by oat β-glucan mediated by gut microbiota

Circadian disruption-induced metabolic syndrome (CDIMS) involves body weight gain, changes in blood profile and gut microbiota. In this study, CDIMS was induced by shifted light dark cycle (SLDC) in C57BL/6J mice. Dietary intervention by oral administration of oat β-glucan (a polymeric prebiotic) alleviated CDIMS when compared to chicory inulin/fructan (an oligomeric prebiotic) and melatonin (a chronobiotic). Oat β-glucan reversed the increase in body weight, liver weight-to-body weight ratio and plasma leptin concentration as well as restored glucose tolerance. In altering gut microbiota, oat β-glucan increased the species richness, reversed the populations of 7 bacterial genera and increased butyrate producers including Ruminococcaceae and Lachnospiraceae which enhance gut barrier protection and regulate glucose homeostasis. Correlation analysis demonstrated the linking of the alleviation of CDIMS by prebiotics and melatonin with different microbial metabolic pathways involved in energy metabolism, biosynthesis of metabolites, metabolism of cofactors and vitamins and endocrine synthesis.

Monocyte-dependent co-stimulation of cytokine induction in human γδ T cells by TLR8 RNA ligands

Human Vγ9Vδ2 T cells recognize pyrophosphates produced by microbes and transformed cells and play a role in anti-infective immunity and tumor surveillance. Toll-like receptors (TLR) are pattern recognition receptors in innate immune cells which sense microbial structures including nucleic acids. Given that γδ T cells are in clinical development for application in cellular cancer immunotherapy and TLR ligands have potent adjuvant activity, we investigated the co-stimulatory role of selected TLR ligands in γδ T-cell activation. Here we have used recently described RNA ligands for TLR7 and TLR8 together with Vγ9Vδ2 T-cell specific pyrophosphate antigens to analyze the rapid cytokine induction in Vδ2 T cells as well as the accessory cell requirements. While TLR8- as well as TLR7/8-specific RNA did not induce IFN-γ in Vδ2 T cells on their own, they provided strong co-stimulation for Vδ2 T cells within peripheral blood mononuclear cells in the presence of additional T-cell receptor activation. In contrast, TLR7 ligands were ineffective. Purified γδ T cells did not directly respond to TLR8 co-stimulation but required the presence of monocytes. Further experiments revealed a critical role of IL-1β and IL-18, and to a slightly lesser extent of IL-12p70, in the co-stimulation of Vδ2 T cells by TLR8 and TLR7/8 RNA ligands. Results of intracellular cytokine expression were validated by ELISA analysis of cytokines in cell culture supernatants. The cell context-dependent adjuvant activity of TLR8 and TLR7/8 RNA ligands described here might be important for the future optimization of γδ T-cell based cancer immunotherapy.

Egg white peptides ameliorate dextran sulfate sodium-induced acute colitis symptoms by inhibiting the production of pro-inflammatory cytokines and modulation of gut microbiota composition

Egg white peptides (EWPs) can be effectively used to alleviate and treat inflammatory diseases due to their anti-oxidation, anti-inflammation, and microbiota regulation capabilities. A dextran sodium sulfate (DSS)-induced colitis model was used to clarify the regulatory effects of EWPs on colitis. Forty-three peptide sequences were identified from EWPs using LC-MS/MS. The results demonstrated that EWPs decreased the levels of pro-inflammatory cytokines and the extent of crypt damage in a dose-dependent manner. 16S rRNA gene sequencing results indicated that 200 mg/kg EWPs significantly increased the relative abundance of beneficial bacteria Lactobacillus and Candidatus_Saccharimonas, and reduced the relative abundance of pathogenic bacteria Ruminiclostridium and Akkermansia. In addition, the degree of correlation between pro-inflammatory cytokines and microbiota was as follows: interleukin (IL)-1β > IL-8 > IL-6 > tumor necrosis factor-α To summarize, EWPs contributed to the alleviation of colitis symptoms and the intestinal injury through anti-inflammatory effects, repair of intestinal mucosa, and modulation of gut microbiota.

An immuno-blocking agent targeting IL-1β and IL-17A reduces the lesion of DSS-induced ulcerative colitis in mice

In recent decades when biological agents have flourished, a part of patients suffering from inflammatory bowel disease (IBD) have received the treatment of tumor necrosis factor inhibitors or IL-1 antibodies. This study aims to investigate the anti-colitis effects of bispecific antibody (FL-BsAb1/17) targeting IL-1β and IL-17A comparing with TNF-α soluble receptor medicine etanercept. IBD model in mice was established by drinking 3% DSS (dextran sulfate sodium salt). On the first day of drinking DSS, treatments with etanercept (5 mg/kg) or different doses of FL-BsAb1/17 (1 mg/kg, 5 mg/kg, and 10 mg/kg) were started by intraperitoneal injection every other day. The results demonstrated that FL-BsAb1/17 treatment was more effective than etanercept at the same dose (5 mg/kg) in relieving the typical symptom of ulcerative colitis induced by DSS (such as the severity score and intestinal shortening), and down-regulating the expression of inflammatory factors (IL-17A, IL-6, IL-12, IL-22, IL-1β, IL-23, TNF-α) in the serum and colon. FL-BsAb1/17 could also reduce the degree of intestinal fibrosis. The same dose of FL-BsAb1/17 (5 mg/kg) performed better than etanercept in down-regulating MDA and up-regulating SOD (superoxide dismutase), CAT (catalase), and T-AOC (total antioxidant capacity) in serum. Both FL-BsAb1/17 and etanercept could reduce the transcription of Bax and increase the transcription of Bcl-2 and slow down apoptosis in colitis colon tissue. We conclude that the blocking of IL-1β and IL-17A can inhibit DSS-induced ulcerative colitis and FL-BsAb1/17 may have potential to become a new dual-target candidate for colitis treatment.

The Anti-Inflammatory Effect and Mucosal Barrier Protection of Clostridium butyricum RH2 in Ceftriaxone-Induced Intestinal Dysbacteriosis

This study aimed at determining the beneficial effect of Clostridium butyricum (CB) RH2 on ceftriaxone-induced dysbacteriosis. To this purpose, BALB/c mice were exposed to ceftriaxone (400 mg/ml) or not (control) for 7 days, and administered a daily oral gavage of low-, and high-dose CB RH2 (10⁸ and 10¹⁰ CFU/ml, respectively) for 2 weeks. CB RH2 altered the diversity of gut microbiota, changed the composition of gut microbiota in phylum and genus level, decreased the F/B ratio, and decreased the pro-inflammatory bacteria (Deferribacteres, Oscillibacter, Desulfovibrio, Mucispirillum and Parabacteroides) in ceftriaxone-treated mice. Additionally, CB RH2 improved colonic architecture and intestinal integrity by improving the mucous layer and the tight junction barrier. Furthermore, CB RH2 also mitigated intestinal inflammation through decreasing proinflammatory factors (TNF-α and COX-2) and increasing anti-inflammatory factors (IL-10). CB RH2 had direct effects on the expansion of CD4⁺ T cells in Peyer’s patches (PPs) in vitro, which in turn affected their immune response upon challenge with ceftriaxone. All these data suggested that CB RH2 possessed the ability to modulate the intestinal mucosal and systemic immune system in limiting intestinal alterations to relieve ceftriaxone-induced dysbacteriosis.

In respond to commensal bacteria: γδT cells play a pleiotropic role in tumor immunity

γδT cells are a mixture of innate programming and acquired adaptability that bridge the adaptive and innate immune systems. γδT cells are mainly classified as tissue-resident Vδ1 or circulating Vδ2 γδT cells. In the tumor microenvironment, tumor immunity is influenced by the increased quantity and phenotype plasticity of γδT cells. Commensal bacteria are ubiquitous in the human body, and they have been confirmed to exist in various tumor tissues. With the participation of commensal bacteria, γδT cells maintain homeostasis and are activated to affect the development and progression of tumors. Here, we summarize the relationship between γδT cells and commensal bacteria, the potential protumor and antitumor effects underlying γδT cells, and the new developments in γδT cell-based tumor therapy which is expected to open new opportunities for tumor immunotherapy.

Inhibition of the activation of γδT17 cells through PPARγ-PTEN/Akt/GSK3β/NFAT pathway contributes to the anti-colitis effect of madecassic acid

Type-17 immune response, mediated mainly by IL-17, plays a critical role in ulcerative colitis. Previously, we showed that madecassic acid (MA), the main active ingredient of Centella asiatica herbs for anti-colitis effect, ameliorated dextran sulfate sodium (DSS)-induced mouse colitis through reducing the level of IL-17. Here, we explore the effect of MA on the activation of γδT17 cells, an alternative source of IL-17 in colitis. In DSS-induced colitis mice, oral administration of MA decreased the number of γδT17 cells and attenuated the inflammation in the colon, and the anti-colitis effect of MA was significantly counteracted by redundant γδT17 cells, suggesting that the decrease in γδT17 cells is important for the anti-colitis effect of MA. In vitro, MA could inhibit the activation but not the proliferation of γδT17 cells at concentrations without evident cytotoxicity. Antibody microarray profiling showed that the inhibition of MA on the activation of γδT17 cells involved PPARγ–PTEN/Akt/GSK3β/NFAT signals. In γδT17 cells, MA could reduce the nuclear localization of NFATc1 through inhibiting Akt phosphorylation to promote GSK3β activation. Moreover, it was confirmed that MA inhibited the Akt/GSK3β/NFATc1 pathway and the activation of γδT17 cells through activating PPARγ to increase PTEN expression and phosphorylation. The correlation between activation of PPARγ, decrease in γδT17 cell number, and amelioration of colitis by MA was validated in mice with DSS-induced colitis. In summary, these findings reveal that MA inhibits the activation of γδT17 cells through PPARγ–PTEN/Akt/GSK3β/NFAT pathway, which contributes to the amelioration of colitis.

Role of γδT cells in liver diseases and its relationship with intestinal microbiota

γδT cells are unconventional T lymphocytes that bridge innate and adaptive immunity. Based on the composition of T cell receptor and the cytokines produced, γδT cells can be divided into diverse subsets that may be present at different locations, including the liver, epithelial layer of the gut, the dermis and so on. Many of these cells perform specific functions in liver diseases, such as viral hepatitis, autoimmune liver diseases, non-alcoholic fatty liver disease, liver cirrhosis and liver cancers. In this review, we discuss the distribution, subsets, functions of γδT cells and the relationship between the microbiota and γδT cells in common hepatic diseases. As γδT cells have been used to cure hematological and solid tumors, we are interested in γδT cell-based immunotherapies to treat liver diseases.

Idebenone Protects against Acute Murine Colitis via Antioxidant and Anti-Inflammatory Mechanisms

Oxidative stress is a key player of the inflammatory cascade responsible for the initiation of ulcerative colitis (UC). Although the short chain quinone idebenone is considered a potent antioxidant and a mitochondrial electron donor, emerging evidence suggests that idebenone also displays anti-inflammatory activity. This study evaluated the impact of idebenone in the widely used dextran sodium sulphate (DSS)-induced mouse model of acute colitis. Acute colitis was induced in C57BL/6J mice via continuous exposure to 2.5% DSS over 7 days. Idebenone was co-administered orally at a dose of 200 mg/kg body weight. Idebenone significantly prevented body weight loss and improved the disease activity index (DAI), colon length, and histopathological score. Consistent with its reported antioxidant function, idebenone significantly reduced the colonic levels of malondialdehyde (MDA) and nitric oxide (NO), and increased the expression of the redox factor NAD(P)H (nicotinamide adenine dinucleotide phosphate) dehydrogenase quinone-1 (NQO-1) in DSS-exposed mice. Immunohistochemistry revealed a significantly increased expression of tight junction proteins, which protect and maintain paracellular intestinal permeability. In support of an anti-inflammatory activity, idebenone significantly attenuated the elevated levels of pro-inflammatory cytokines in colon tissue. These results suggest that idebenone could represent a promising therapeutic strategy to interfere with disease pathology in UC by simultaneously inducing antioxidative and anti-inflammatory pathways.

Protective effects of oxymatrine against DSS-induced acute intestinal inflammation in mice via blocking the RhoA/ROCK signaling pathway

Oxymatrine (OMT) is an important quinoxaline alkaloid that has a wide range of pharmacological effects and has been shown to alleviate ulcerative colitis due to its profound anti-inflammatory effects. The RhoA/ROCK (Rho kinase) signaling pathway has been shown to be related to the pathogenesis of several autoimmune diseases; however, the specific mechanisms of RhoA/ROCK signaling in inflammatory bowel disease (IBD) remain elusive. Therefore, we sought to determine whether OMT could ameliorate acute intestinal inflammation by targeting the RhoA/ROCK signaling pathway. The potential therapeutic effect of OMT on acute intestinal inflammation and its impact on the RhoA/ROCK signaling pathway were assessed in six groups of mice treated with low, medium and high doses of OMT (25, 50 and 100 mg/kg, respectively), and an inhibitor of ROCK, Y-27632, as a positive control, after initiating dextran sodium sulfate (DSS)-induced acute intestinal inflammation. The model group and normal group were injected intraperitoneally with equal doses of PBS. Our results showed that OMT treatment could protect the integrity of the epithelial barrier, relieve oxidative stress, inhibit the expression of inflammatory mediators and pro-inflammatory cytokines, restrain the differentiation of Th17 cells and promote the differentiation of Treg cells via inhibition of the RhoA/ROCK pathway, thus providing therapeutic benefits for ulcerative colitis (UC). Therefore, inhibiting the RhoA/ROCK pathway might be a new approach that can be used in UC therapy, which deserves to be investigated further.

Bacillus licheniformis Zhengchangsheng® attenuates DSS-induced colitis and modulates the gut microbiota in mice

Human inflammatory bowel disease (IBD) and experimental colitis models in mice are associated with shifts in gut microbiota composition, and several probiotics are widely used to improve gastrointestinal health. Here, we investigated whether the probiotic Bacillus licheniformis Zhengchangsheng® (BL) ameliorates dextran sulphate sodium (DSS)-induced colitis through alteration of the gut microbiota. Experimental colitis was induced in BALB/C mice by dissolving 3% DSS in their drinking water for 7 days, which were gavaged with 0.2 ml phosphate-buffered saline or BL (3×107 cfu/ml) once a day. Administration of BL attenuated several effects of DSS-induced colitis, including weight loss, increased disease activity index, and disrupted intestinal barrier integrity. In addition, BL mitigated the reduction in faecal microbiota richness in DSS treated mice. Interestingly, BL was found to reduce the elevated circulating endotoxin level in mice with colitis by modulating the microbial composition of the microbiota, and this was highly associated with a proportional decrease in gut Bacteroidetes. Our results demonstrate that BL can attenuate DSS-induced colitis and provide valuable insight into microbiota interactions during IBD.

Differential effects of psychotropic drugs on microbiome composition and gastrointestinal function

RATIONALE

Growing evidence supports a role for the microbiota in regulating gut-brain interactions and, thus, psychiatric disorders. Despite substantial scientific efforts to delineate the mechanism of action of psychotropic medications at a central nervous system (CNS) level, there remains a critical lack of understanding on how these drugs might affect the microbiota and gut physiology.

OBJECTIVES

We investigated the antimicrobial activity of psychotropics against two bacterial strain residents in the human gut, Lactobacillus rhamnosus and Escherichia coli. In addition, we examined the impact of chronic treatment with these drugs on microbiota and intestinal parameters in the rat.

RESULTS

In vitro fluoxetine and escitalopram showed differential antimicrobial effects. Lithium, valproate and aripiprazole administration significantly increased microbial species richness and diversity, while the other treatments were not significantly different from controls. At the genus level, several species belonging to Clostridium, Peptoclostridium, Intestinibacter and Christenellaceae were increased following treatment with lithium, valproate and aripiprazole when compared to the control group. Animals treated with escitalopram, venlafaxine, fluoxetine and aripiprazole exhibited an increased permeability in the ileum.

CONCLUSIONS

These data show that psychotropic medications differentially influence the composition of gut microbiota in vivo and that fluoxetine and escitalopram have specific antimicrobial activity in vitro. Interestingly, drugs that significantly altered gut microbial composition did not increase intestinal permeability, suggesting that the two factors are not causally linked. Overall, unravelling the impact of psychotropics on gastrointestinal and microbiota measures offers the potential to provide critical insight into the mechanism of action and side effects of these medications.

Research progress of P2X7 receptor in inflammatory bowel disease

Inflammatory bowel disease is a chronic nonspecific inflammatory disease of the intestine. Its pathogenesis is not yet fully understood. It may be related to heredity, environmental triggers, infection, immune dysfunction and other factors. Purinergic receptor (P2X7R) ligand-gated ion channel is closely related to inflammation and widely expressed in intestinal cells. Previous studies have shown that ATP/P2X7R signal is involved in the pathogenesis of intestinal inflammation, but its specific mechanism needs further study. This article reviews the research progress of P2X7 receptor in inflammatory bowel disease.

Microbial network disturbances in relapsing refractory Crohn's disease

Inflammatory bowel diseases (IBD) can be broadly divided into Crohn's disease (CD) and ulcerative colitis (UC) from their clinical phenotypes. Over 150 host susceptibility genes have been described, although most overlap between CD, UC and their subtypes, and they do not adequately account for the overall incidence or the highly variable severity of disease. Replicating key findings between two long-term IBD cohorts, we have defined distinct networks of taxa associations within intestinal biopsies of CD and UC patients. Disturbances in an association network containing taxa of the Lachnospiraceae and Ruminococcaceae families, typically producing short chain fatty acids, characterize frequently relapsing disease and poor responses to treatment with anti-TNF-α therapeutic antibodies. Alterations of taxa within this network also characterize risk of later disease recurrence of patients in remission after the active inflamed segment of CD has been surgically removed.

IL-8 antagonist, CXCL8(3-72)K11R/G31P coupled with probiotic exhibit variably enhanced therapeutic potential in ameliorating ulcerative colitis

Inflammatory bowel disease (IBD) remains a major health challenge due in part to unsafe and limited treatment options, hence there is the need for alternatives. CXCL8/interleukin 8 (IL-8) is elevated in inflammation, and binds preferentially to G protein-couple receptors (GPCRs) CXCR1/2 of the CXC chemokine family to initiate cascades of downstream inflammatory signals. A mutant CXCL8 protein, CXCL8(3-72)K11R/G31P (G31P), competitively and selectively binds to CXCR1/2, making CXCL8 redundant. We explore the therapeutic potential of G31P in dextran sulfate sodium (DSS) induced ulcerative colitis (UC), and the corresponding effect if G31P treatment is augmented with Lactobacillus acidophilus (LACT). The treatment options administered significantly reduced TNF-α, IFN-γ, IL-1β, IL-6, and IL-8, but maintained elevated levels of IL-10. CD68 and F4/80 expressions were down-regulated and showed restricted infiltration to inflamed colon, while IL-17F levels were insignificantly different from the DSS treated mice. Also, we observed up-regulation of IL-17A in G31P + LACT but not G31P treated mice if compared with Control group. The treatments ameliorated colonic fibrosis by reducing VEGF, TGF-β, MMP-2 and MMP-9. In addition, we observed elevated levels of E-cadherin, and marginal up-regulation of occludin, suggesting the role of the treatments in regulating tight intestinal junction and adherence proteins. Mechanism-wise, G31P interferes with AKT and ERK signaling pathways. Our study suggests that G31P confers protection in IBD, particularly UC, and when G31P treatment is augmented with Lactobacillus acidophilus, the protection is variably enhanced.

IL-17 in neonatal health and disease

Over the last few years, scientific interest in the cytokine IL-17A has intensified as its role in human health and disease has been elucidated. Discovered almost a quarter century ago, IL-17A is known to have poor biologic activity when acting alone, but attains robust actions when working synergistically with potent mediators of proinflammatory immune responses, such as IL-6 and IL-8. IL-17A is produced by specialized innate immune cells that protect host barriers from the outside world. Like sentries, these innate immune cells can "sound the alarm" through increased production of IL-17A, causing activation and recruitment of primed neutrophils and monocytes when pathogens escape initial host defenses. In this way, IL-17A promulgates mechanisms responsible for pathogen death and clearance. However, when IL-17A pathways are triggered during fetal development, due to chorioamnionitis or in utero inflammatory conditions, IL-17A can instigate and/or exacerbate fetal inflammatory responses that increase neonatal morbidities and mortality associated with common neonatal conditions such as sepsis, bronchopulmonary dysplasia (BPD), patent ductus arteriosus (PDA), and necrotizing enterocolitis (NEC). This review details the ontogeny of IL-17A in the fetus and newborn, discusses how derangements in its production can lead to pathology, and describes known and evolving therapies that may attenuate IL-17A-mediated human conditions.