Relationship between intestinal microbiota and ulcerative colitis: Mechanisms and clinical application of probiotics and fecal microbiota transplantation

Development and Organization of the Secondary and Tertiary Lymphoid Organs: Influence of Microbial and Food Antigens

Background:

Secondary lymphoid organs (SLO) are distributed in many districts of the body and, especially, lymph nodes, spleen and gut-associated lymphoid tissue are the main cellular sites. On the other hand, tertiary lymphoid organs (TLO) are formed in response to inflammatory, infectious, autoimmune and neoplastic events. </P><P> Developmental Studies: In the present review, emphasis will be placed on the developmental differences of SLO and TLO between small intestine and colon and on the role played by various chemokines and cell receptors. Undoubtedly, microbiota is indispensable for the formation of SLO and its absence leads to their poor formation, thus indicating its strict interaction with immune and non immune host cells. Furthermore, food antigens (for example, tryptophan derivatives, flavonoids and byphenils) bind the aryl hydrocarbon receptor on innate lymphoid cells (ILCs), thus promoting the development of postnatal lymphoid tissues. Also retinoic acid, a metabolite of vitamin A, contributes to SLO development during embryogenesis. Vitamin A deficiency seems to account for reduction of ILCs and scarce formation of solitary lymphoid tissue. </P><P> Translational Studies: The role of lymphoid organs with special reference to intestinal TLO in the course of experimental and human disease will also be discussed. </P><P> Future Perspectives: Finally, a new methodology, the so-called “gut-in-a dish”, which has facilitated the in vitro interaction study between microbe and intestinal immune cells, will be described.

The Efficacy of Probiotics, Prebiotic Inulin-Type Fructans, and Synbiotics in Human Ulcerative Colitis: A Systematic Review and Meta-Analysis

Studies of probiotics, fructan-type prebiotics, and synbiotics in patients with ulcerative colitis (UC) show significant heterogeneity in methodology and results. Here, we study the efficacy of such interventions and the reasons for the heterogeneity of their results. Eligible random controlled trials were collected from the PUBMED and SCOPUS databases. A total of 18 placebo-controlled and active treatment-controlled (i.e., mesalazine) studies were selected with a Jadad score ≥ 3, including 1491 patients with UC. Data for prebiotics and synbiotics were sparse and consequently these studies were excluded from the meta-analysis. The UC remission efficacy of probiotics was measured in terms of relative risk (RR) and odds ratio (OR). Significant effects were observed in patients with active UC whenever probiotics containing bifidobacteria were used, or when adopting the US Food and Drug Administration (FDA)-recommended scales (UC Disease Activity Index and Disease Activity Index). By the FDA recommended scales, the RR was 1.55 (CI95%: 1.13–2.15, p-value = 0.007, I² = 29%); for bifidobacteria-containing probiotics, the RR was 1.73 (CI95%: 1.23–2.43, p-value = 0.002, I² = 35%). No significant effects were observed on the maintenance of remission for placebo-controlled or mesalazine-controlled studies. We conclude that a validated scale is necessary to determine the state of patients with UC. However, probiotics containing bifidobacteria are promising for the treatment of active UC.

Probiotics combined with aminosalicylic acid affiliates remission of ulcerative colitis: a meta-analysis of randomized controlled trial

We conducted a meta-analysis to evaluate the effect of probiotic combined with aminosalicylic on induction remission maintenance treatment of ulcerative colitis (UC). We conducted systematic searches in several Chinese and English databases from inception to June 2018, screening randomized controlled trials about effect of probiotics combined with aminosalicylic acid on UC. The evaluation indicator was the rate of remission. The relative risk (RR) and 95% confidence interval (CI) were calculated. A total of 27 studies with 1942 patients were included. The results indicated that the remission rate was significantly higher in the group using probiotics combined with aminosalicylic acid than that in the group using aminosalicylic acid alone (RR = 1.40, 95% CI: 1.27–1.53, P=0.000). The subgroup analysis indicated that probiotics combined with aminosalicylic acid can significantly elevate the remission rate in both mild to moderate (RR = 1.33, 95% CI: 1.16–1.54, P=0.000) and active stage (RR = 1.40, 95% CI: 1.27–1.64, P=0.000) UC. In different number of bacterium, drug types and treatment periods, the combination with probiotics can significantly increase the remission rate UC. The funnel plot shows slight publication bias. Probiotics in conjunction with aminosalicylic can obviously increase the clinical remission rate of activity UC than drug alone. There was no significant difference between combined with mesalazine group and salicylazosulfapyridine group.

Lactobacillus acidophilus suppresses intestinal inflammation by inhibiting endoplasmic reticulum stress

BACKGROUND AND AIM

Nuclear factor kappa B (NF-κB) activation and endoplasmic reticulum (ER) stress signaling play significant roles in the pathogenesis of inflammatory bowel disease (IBD). Thus, we evaluated whether new therapeutic probiotics have anti-colitic effects, and we investigated their mechanisms related to NF-κB and ER-stress pathways.

METHODS

Luciferase, nitric oxide, and cytokine assays using HT-29 or RAW264.7 cells were conducted. Mouse colitis was induced using dextran sulfate sodium and confirmed by disease activity index and histology. Macrophages and T-cell subsets in isolated peritoneal cavity cells and splenocytes were analyzed by flow cytometry. Gene and cytokine expression profiles were determined using reverse-transcription polymerase chain reaction.

RESULTS

Lactobacillus acidophilus (LA1) and Pediococcus pentosaceus inhibited nitric oxide production in RAW264.7 cells, but only LA1 inhibited Tnfa and induced Il10 expression. LA1 increased the lifespan of dextran sulfate sodium-treated mice and attenuated the severity of colitis by inducing M2 macrophages in peritoneal cavity cells and Th2 and Treg cells in splenocytes. The restoration of goblet cells in the colon was accompanied by the induction of Il10 expression and the suppression of pro-inflammatory cytokines. Additionally, we found that LA1 exerts an anti-colitic effect by improving ER stress in HT-29 cells as well as in vivo.

CONCLUSIONS

We showed that LA1 significantly interferes with ER stress and suppresses NF-κB activation. Our findings suggest that LA1 can be used as a potent immunomodulator in IBD treatment, and the regulation of ER stress may have significant implications in treating IBD.

The Role of the CXCL12/CXCR4/ACKR3 Axis in Autoimmune Diseases

Chemokine receptors are members of the G protein-coupled receptor superfamily. These receptors are intimately involved in cell movement, and thus play a critical role in several physiological and pathological situations that require the precise regulation of cell positioning. CXCR4 is one of the most studied chemokine receptors and is involved in many functions beyond leukocyte recruitment. During embryogenesis, it plays essential roles in vascular development, hematopoiesis, cardiogenesis, and nervous system organization. It has been also implicated in tumor progression and autoimmune diseases and, together with CD4, is one of the co-receptors used by the HIV-1 virus to infect immune cells. In contrast to other chemokine receptors that are characterized by ligand promiscuity, CXCR4 has a unique ligand-stromal cell-derived factor-1 (SDF1, CXCL12). However, this ligand also binds ACKR3, an atypical chemokine receptor that modulates CXCR4 functions and is overexpressed in multiple cancer types. The CXCL12/CXCR4/ACKR3 axis constitutes a potential therapeutic target for a wide variety of inflammatory diseases, not only by interfering with cell migration but also by modulating immune responses. Thus far, only one antagonist directed against the ligand-binding site of CXCR4, AMD3100, has demonstrated clinical relevance. Here, we review the role of this ligand and its receptors in different autoimmune diseases.

A holistic view of gallic acid-induced attenuation in colitis based on microbiome-metabolomics analysis

GA enema can treat UC by influencing microbiota-mediated metabolism.

Serum folic acid, PCT, CRP and ESR detection as biomarker in differentiation ulcerative colitis activity

Objective: To investigate the serum concentration of folic acid, procalcitonin (PCT), C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) as biomarkers in the differentiation of the severity of ulcerative colitis (UC). Methods: Fifty one patients who had been diagnosed with UC were recruited from January 2014 to August 2017. Twenty-two of these patients had severe diseases while the remaining twenty-nine patients had mild/moderate disease, according to the Truelove-Witts classification criteria. In the same study, 26 healthy subjects which served as the healthy controls were included alongside the UC patient group. The serum folic acid, PCT, CRP and ESR were examined and compared among the healthy control, mild/moderate and severe UC groups. Results: The serum PCT, CRP and ESR in the control group were significantly lower than those of mild/moderate and severe UC groups with statistical significance (p<0.001). However, the serum folic acid in the control group was significant higher than that of mild/ moderate and severe UC groups (p<0.001). The serum folic acid (p=0.015), PCT (p<0.001) and ESR (p<0.001) were significantly different between the severe and mild/moderate groups. However, the serum CRP was not statistically significant between the mild/moderate and severe UC groups (p=0.06). Using serum folic acid, PCT, CRP and ESR as biomarkers in the differentiation of mild/moderate and severe UC, the serum PCT had good diagnostic accuracy for detecting severe UC with the diagnostic sensitivity and specificity of 85.71% (63.66~96.95%), 82.76% (64.23~94.15%), respectively under the cut off value of 0.045. The correlation between serum CRP, ESR and PCT were examined by Pearson correlation test and line regression analysis. However, there was no correlation between each of them with the exception of folic acid and ESR (r=-0.334, p=0.017). Conclusion: Serum folic acid, PCT, CRP and ESR are significantly elevated in patients with active UC thereby presenting novel and potentially promising biomarkers for the diagnosis and differentiation of mild/moderate and sever UC.

Bifidobacterium lactis Ameliorates the Risk of Food Allergy in Chinese Children by Affecting Relative Percentage of Treg and Th17 Cells

We aimed to explore the therapeutic effect of Bifidobacterium lactis on food allergy by investigating the percentage of Treg and Th17 cells in Chinese children and related molecular mechanisms. A total of 256 children with food allergy were evenly assigned into two groups: BG, the children received 10 ml B. lactis (1 × 10⁶/ml) daily, and CG, the children received the solution without B. lactis daily for three months. Allergic symptoms, serum IgE, and food antigen-specific IgE were measured. A mouse allergy model was established by using shrimp tropomyosin and treated with B. lactis. Relative mRNA levels of Treg- and Th17-associated cytokines were measured by using quantitative PCR. The percentage of Treg and Th17 cells in spleen were measured by using flow cytometry. After 3-month therapy, the allergic symptoms of the BG were remarkably reduced when compared with the CG (P < 0.05). Serum levels of IgE and food antigen-specific IgE were decreased too (P < 0.05). Similar results were also found in a mouse allergy model. After B. lactis treatment, the relative mRNA level of FoxP3 was significantly enhanced in the B. lactis therapy group when compared to positive controls. In addition, relative mRNA levels of FoxP3 and TGF-β associated with Treg cells were increased, whereas relative mRNA levels of IL-17A and IL-23 associated with Th17 were reduced. B. lactis treatment significantly increased the ratio of Treg and Th17 cells in a mouse allergy model (P < 0.05). B. lactis effectively alleviates allergic symptoms by increasing the ratio of Treg and Th17 cells.

A Bronze-Tomato Enriched Diet Affects the Intestinal Microbiome under Homeostatic and Inflammatory Conditions

Inflammatory bowel diseases (IBD) are debilitating chronic inflammatory disorders that develop as a result of a defective immune response toward intestinal bacteria. Intestinal dysbiosis is associated with the onset of IBD and has been reported to persist even in patients in deep remission. We investigated the possibility of a dietary-induced switch to the gut microbiota composition using Winnie mice as a model of spontaneous ulcerative colitis and chow enriched with 1% Bronze tomato. We used the near isogenic tomato line strategy to investigate the effects of a diet enriched in polyphenols administered to mild but established chronic intestinal inflammation. The Bronze-enriched chow administered for two weeks was not able to produce any macroscopic effect on the IBD symptoms, although, at molecular level there was a significant induction of anti-inflammatory genes and intracellular staining of T cells revealed a mild decrease in IL17A and IFNγ production. Analysis of the microbial composition revealed that two weeks of Bronze enriched diet was sufficient to perturb the microbial composition of Winnie and control mice, suggesting that polyphenol-enriched diets may create unfavorable conditions for distinct bacterial species. In conclusion, dietary regimes enriched in polyphenols may efficiently support IBD remission affecting the intestinal dysbiosis.

The Microbial Composition of Bacteroidetes Species in Ulcerative Colitis Is Effectively Improved by Combination Therapy With Fecal Microbiota Transplantation and Antibiotics

BACKGROUND

We previously reported that fresh fecal microbiota transplantation (FMT) after triple-antibiotic therapy (amoxicillin, fosfomycin, and metronidazole [AFM]; A-FMT) synergistically contributed to the recovery of phylum Bacteroidetes composition associated with the endoscopic severity and treatment efficacy of ulcerative colitis (UC). Here, we performed further microbial analyses using a higher-resolution method to identify the key bacterial species in UC and determine whether viable Bacteroidetes species from donor feces were successfully colonized by A-FMT.

METHODS

The taxonomic composition of Bacteroidetes in 25 healthy donors and 27 UC patients at baseline was compared at the species level using a heat-shock protein (hsp) 60-based microbiome method. Microbiota alterations before and after treatment of UC patients were also analyzed in 24 cases (n = 17 A-FMT; n = 3 mono-AFM; n = 4 mono-FMT).

RESULTS

We found species-level dysbiosis within the phylum Bacteroidetes in UC samples, which was associated with reduced species diversity, resulting from hyperproliferation and hypoproliferation of particular species. Moreover, in responders treated with A-FMT, diversity was significantly recovered at 4 weeks after a fresh round of FMT, after which high degrees of similarity in Bacteroidetes species composition among recipients and donors were observed.

CONCLUSIONS

A-FMT alleviated intestinal dysbiosis, which is caused by the loss of Bacteroidetes species diversity in patients with UC. Eradication of dysbiotic indigenous Bacteroidetes species by AFM pretreatment might promote the colonization of viable Bacteroidetes cells, thereby improving the intestinal microbiota dysbiosis induced by UC. Our findings serve as a basis for further investigations into the mechanisms of FMT.

Probiotics in Autoimmune and Inflammatory Disorders

Probiotics have been used to ameliorate gastrointestinal symptoms since ancient times. Over the past 40 years, probiotics have been shown to impact the immune system, both in vivo and in vitro. This interaction is linked to gut microbes, their polysaccharide antigens, and key metabolites produced by these bacteria. At least four metabolic pathways have been implicated in mechanistic studies of probiotics, based on mechanistic studies in animal models. Microbial⁻immune system crosstalk has been linked to: short-chain fatty acid production and signaling, tryptophan metabolism and the activation of aryl hydrocarbon receptors, nucleoside signaling in the gut, and activation of the intestinal histamine-2 receptor. Several randomized controlled trials have now shown that microbial modification by probiotics may improve gastrointestinal symptoms and multiorgan inflammation in rheumatoid arthritis, ulcerative colitis, and multiple sclerosis. Future work will need to carefully assess safety issues, selection of optimal strains and combinations, and attempts to prolong the duration of colonization of beneficial microbes.

Fecal microbiota transplant - a new frontier in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic multifactorial disease that affects the gastrointestinal tract and results from an aberrant immune response toward luminal antigens in genetically susceptible people. Most of the current therapies for IBD focus on the management of the inflammation by using corticosteroids, immune modulators, and more recently, monoclonal antibodies (biological therapy). Although these therapies provide benefit in most cases, there are still a significant number of patients who do not respond or become refractory over time, suggesting the need for alternative therapeutic options. In the last decade, it has been recognized that "dysbiosis," an imbalanced gut microbiota, is a key element in IBD suggesting microbiome-based therapies as an attractive approach. Recently, fecal microbiota transplant (FMT) has been successfully used for the treatment of Clostridium difficile infection, and it is now under investigation for the treatment of IBD. Clinical trials data are still poor but strongly support a future introduction of FMT in therapy to manage IBD microbiome. More studies are needed to assess the optimal route of administration and the frequency of FMT, the best matched donor for each patient as well as the risks associated with FMT in IBD.

Investigation of facilitative urea transporters in the human gastrointestinal tract

The symbiotic relationship between humans and their intestinal microbiome is supported by urea nitrogen salvaging. Previous studies have shown that colonic UT-B urea transporters play a significant role in this important physiological process. This current study investigated UT-A and UT-B urea transporter expression along the human gastrointestinal tract. Initial end-point PCR experiments determined that UT-A RNA was predominantly expressed in the small intestine, while UT-B RNA was expressed in stomach, small intestine, and colon. Using western blotting experiments, a strong 40-60 kDa UT-B signal was found to be abundant in both ileum and colon. Importantly, this signal was deglycosylated by PNGaseF enzyme treatment to a core protein of 30 kDa in both tissues. Further immunolocalization studies revealed UT-B transporter proteins were present at the apical membrane of the villi in the ileum, but predominantly at the basolateral membrane of the colonic surface epithelial cells. Finally, a blind scoring immunolocalization study suggested that there was no significant difference in UT-B abundance throughout the colon (NS, ANOVA, N = 5-21). In conclusion, this current study suggested UT-B to be the main human intestinal urea transporter. Intriguingly, these data suggested that the same UT-B isoform was present in all intestinal epithelial cells, but that the precise cellular location varied.