Intestinal Bacterial Antigens Research Articles

Importance of Gut Microbiota in Patients with Inflammatory Bowel Disease.

Inflammatory bowel diseases (IBDs), such as Crohn's disease (CD) and ulcerative colitis (UC), are chronic diseases of the digestive system with a multifactorial and not fully understood etiology. There is research suggesting that they may be initiated by genetic, immunological, and lifestyle factors. In turn, all of these factors play an important role in the modulation of intestinal microflora, and a significant proportion of IBD patients struggle with intestinal dysbiosis, which leads to the conclusion that intestinal microflora disorders may significantly increase the risk of developing IBD. Additionally, in IBD patients, Toll-like receptors (TLRs) produced by intestinal epithelial cells and dendritic cells treat intestinal bacterial antigens as pathogens, which causes a disruption of the immune response, resulting in the development of an inflammatory process. This may result in the occurrence of intestinal dysbiosis, which IBD patients are significantly vulnerable to. In this study, we reviewed scientific studies (in particular, systematic reviews with meta-analyses, being studies with the highest level of evidence) regarding the microflora of patients with IBD vs. the microflora in healthy people, and the use of various strains in IBD therapy.

Escherichiacoli-Specific CD4+ T Cells Have Public T-Cell Receptors and Low Interleukin 10 Production in Crohn's Disease.

Background & AimsCrohn’s disease (CD) likely represents decreased immune tolerance to intestinal bacterial antigens. Most CD patients have high titers of antibodies to intestinal commensal proteins, including the outer membrane porin C (OmpC) of Escherichia coli.MethodsBy using major histocompatibility complex II tetramers, we identified an HLA-DRB1∗15:01-restricted peptide epitope of OmpC recognized by CD4+ T cells in peripheral blood mononuclear cells from HLA-DRB1∗15:01+ healthy control (HC) and CD patients.ResultsThe precursor frequency of these cells in CD correlated with anti-OmpC IgA titers, but did not differ from that of HCs. In both cohorts, they showed a CD161+, integrin α4β7+ phenotype ex vivo by flow cytometry, distinct from the C-X-C Motif Chemokine Receptor 3 phenotype of autologous influenza hemagglutinin (Flu) peptide-specific T cells. The T-cell receptor α and β chains of in vitro–expanded OmpC-specific T-cell clones often contained public amino acid sequences that were identical in cells from different patients. Expanded T-cell clones from CD subjects produced significantly less interleukin (IL)10 (P < .0001) than those from HCs, and a trend toward decreased production of the T helper 2 cell–associated IL4, IL5, and IL13 by CD clones also was seen.ConclusionsBoth HCs and CD patients have detectable OmpC-specific T cells in circulation, with similar immunophenotypes and often identical T-cell–receptor sequences. However, expanded clones from patients with CD produce less of the immunoregulatory cytokine IL10, showing a selective defect in the regulatory function of intestinal microbial antigen-specific T cells in patients with CD.

Importance of the intestinal microbiota in ocular inflammatory diseases: A review.

The purpose of this article is to review the literature on relationships between the intestinal microbiota and ocular inflammatory disease, specifically non-infectious uveitis and age-related macular degeneration. The importance of the intestinal microbiota in uveitis pathogenesis has been shown by multiple groups demonstrating that alterations in the microbiota induced by certain oral antibiotics results in reduced uveitis severity, and another group demonstrating that a commensal intestinal bacterial antigen activates retina-specific autoreactive T cells, potentially indicating a commensal trigger for uveitis. Additionally, commensal intestinal bacterial metabolite short chain fatty acids can be utilized to suppress autoimmune uveitis. Age-related macular degeneration is associated with intestinal dysbiosis, which is partially influenced by genetic risk alleles and AREDS supplementation. Strategies for therapeutically targeting the intestinal microbiota might involve several approaches, including the use of antibiotics, dietary changes, drugs that supplement beneficial bacterial metabolites or target causative bacterial strains, dietary strategies or faecal microbial transplantation. In summary, the intestinal microbiota are at the cross-roads of genetic and environmental factors that can promote ocular conditions such as non-infectious uveitis and age-related macular degeneration, partially via its dynamic influence on mucosal and systemic immunity. The intestinal microbiome thus represents a salient potential target for therapeutic modulation to treat these potentially blinding conditions.

Is it bowel-associated dermatosis-arthritis syndrome induced by small intestinal bacteria overgrowth?

IntroductionBowel-associated dermatosis-arthritis syndrome is rare systemic diseases characterized by a prodrome of fever, chills, and influenza-like symptoms with subsequent skin eruptions, myalgias, and polyarthralgias. It is reported to be occurred in Intestinal bypass surgery and inflammatory bowel disease.Case descriptionHerein, we described a 29-years-old man with Bowel-associated dermatosis-arthritis syndrome. He had no history of gastrointestinal surgery and inflammatory bowel disease. Distribution of the gut bacterial flora showed small intestinal bacterial overgrowth.Discussion and EvaluationIt is rarely form as Non-intestinal bypass road and non-inflammatory bowel disease was induced by small intestinal bacteria overgrowth.ConclusionsWe concluded that Immuno-inflammatory response to overgrowth of intestinal bacterial antigen induce the clinical symptoms of bowel-associated dermatosis-arthritis syndrome.

Circulating T cells specific for an intestinal bacterial antigen peptide show a distinctive phenotype and potentially proinflammatory gene expression pattern in Crohn’s disease.

Abstract Background Crohn’s disease (CD) may be an inappropriate immune reaction to normally well-tolerated intestinal bacterial antigens. Indeed, many CD patients possess abnormally high titers of antibodies specific for intestinal bacterial proteins, such as the outer membrane protein C (OmpC) of E. coli. Methods Using MHC-II tetramer-guided epitope-mapping, we identified a specific peptide of OmpC recognized by peripheral T cells from HLA-DR1501+ individuals. HLA-DR1501 tetramers loaded with this OmpC peptide or a known antigenic peptide from influenza virus (Flu) were then used to compare OmpC versus Flu-specific T cells from HLA-DR1501+ healthy and CD donors via flow cytometry and multiplex qPCR. Results OmpC-specific T cells more frequently expressed the Th17 marker CD161 (49% v 26%; p=1.1e-18) and the gut-homing integrin α4β7 (43% v 10%; p=1.8e-13) than autologous Flu-specific T cells. Conversely, the Th1 marker CXCR3 was more commonly seen on Flu than OmpC-specific T cells (72% v 61%; p = 0.005). No differences in the frequency or immunophenotype of OmpC-specific T cells were found between healthy and CD patients. However in patients with CD, multiplex PCR of sorted OmpC-specific T cells revealed significantly higher expression of the costimulatory molecule CD226 (p=0.03) compared to healthy controls, with a concomitant trend towards decreased expression of the coinhibitory receptor TIGIT (p=0.1) in CD patients. Conclusions OmpC-specific T cells with a gut-tropic, Th17-like phenotype can be found in the peripheral blood, and may have an imbalance in CD226 and TIGIT expression to favor inflammation in CD.

Natural killer T cells play a necessary role in modulating of immune-mediated liver injury by gut microbiota.

Gut microbiota are implicated in many liver diseases. Concanavalin A (ConA)-induced hepatitis is a well-characterized murine model of fulminant immunological hepatic injury. Oral administration of pathogenic bacteria or gentamycin to the mice before ConA injection, liver injury and lymphocyte distribution in liver and intestine were assessed. Our data show that administration of pathogenic bacteria exacerbated the liver damage. There was more downregulation of activation-induced natural killer T (NKT) cells in the liver of pathogenic bacteria-treated ConA groups. Also, there was a negative correlation between the numbers of hepatic NKT cells and liver injury in our experiments. Moreover, intestinal dendritic cells (DCs) were increased in pathogenic bacteria–treated ConA groups. The activation of DCs in Peyer's patches and the liver was similar to the intestine. However, depletion of gut gram-negative bacteria alleviated ConA-induced liver injury, through suppressed hepatic NKT cells activation and DCs homing in liver and intestine. In vitro experiments revealed that DCs promoted NKT cell cytotoxicity against hepatocyte following stimulation with pathogenic bacteria. Our study suggests that increased intestinal pathogenic bacteria facilitate immune-mediated liver injury, which may be due to the activation of NKT cells that mediated by intestinal bacterial antigens activated DCs.

IL-7 promotes long-term in vitro survival of unique long-lived memory subset generated from mucosal effector memory CD4+ T cells in chronic colitis mice

Colitogenic memory CD4+ T cells are important in the pathogenesis of inflammatory bowel disease (IBD). Although memory stem cells with high survival and self-renewal capacity were recently identified in both mice and humans, it is unclear whether a similar subset is present in chronic colitis mice. We sought to identify and purify a long-lived subset of colitogenic memory CD4+ T cells, which may be targets for treatment of IBD. A long-lived subset of colitogenic memory CD4+ T cells was purified using a long-term culture system. The characteristics of these cells were assessed. Interleukin (IL)-7 promoted the in vitro survival for >8 weeks of lamina propria (LP) CD4+ T cells from colitic SCID mice previously injected with CD4+CD45RBhigh T cells. These cells were in a quiescent state and divided a maximum of 5 times in 4 weeks. LP CD4+ T cells expressed higher levels of Bcl-2, integrin-α4β7, CXCR3 and CD25 after than before culture, as well as secreting high concentrations of IL-2 and low concentrations of IFN-γ and IL-17 in response to intestinal bacterial antigens. LP CD4+ T cells from colitic mice cultured with IL-7 for 8 weeks induced more severe colitis than LP CD4+ T cells cultured for 4 weeks. We developed a novel culture system to purify a long-lived, highly pathogenic memory subset from activated LP CD4+ T cells. IL-7 promoted long-term in vitro survival of this subset in a quiescent state. This subset will be a novel, effective target for the treatment of IBD.

1076 Colitogenic Effector Memory CD4+ T Cells Develop TH1/TH17 Mediated Interstitial Pneumonia Independent to Intestinal Bacterial Antigens

G A A b st ra ct s vs 9.8±1.8, d14. IL6: 19.0±10.2 vs 38.9±7.7, p=0.08, d1; 23.2±11.4 vs 88.0±37.2, p=0.06, d7; 67.4±25.0 vs 28.0±7.8, d14. TNFα: 2.4±0.4 vs 3.5±0.4, p=0.06, d1; 3.9±0.7 vs 25.3±9.7, p=0.02, d7; 4.7±1.0 vs 3.1±0.5, d14). Conclusions: Anti-TNFα Tx suppressed inflammation and fibrosis when given early in the course of PG-PS enterocolitis (d1 or d7), but not late in the course (d14). Procollagen mRNAs may increase with late onset treatment (d14), although fibrosis was not increased histologically. Our data is consistent with improved outcomes with anti-TNFα therapy in patients with newly diagnosed disease.

CD4+CD25+ cell depletion from the normal CD4+ T cell pool prevents tolerance toward the intestinal flora and leads to chronic colitis in immunodeficient mice

CD4+CD25+ regulatory T cells have been shown to prevent immune-mediated colitis in mice; however, it is unclear whether the absence of CD4+CD25+ in the normal CD4+ T cell pool is responsible for the development of chronic colitis. Using the T cell-deficient Tgepsilon26 mouse model, we show that CD4+CD25- cells but not CD4+CD25+ cells induce a severe intestinal inflammation. Transfer of CD4+CD25+ cells, together with CD4+CD25- cells, ameliorated intestinal inflammation, and reconstitution with the whole mesenteric lymph node cell pool did not induce colitis in recipients. Transferred CD4+CD25- cells were found mainly in the mesenteric lymph nodes, where they showed an activated TH1-like phenotype. In the absence of regulatory CD4+CD25+ T cells, recipient CD4 cells secreted IFN-gamma in response to stimulation with intestinal bacterial antigen that was prevented in vivo and in vitro by regulatory CD4+CD25+ cells. These studies suggest that CD4+CD25- cells have a strong colitogenic effect in the Tgepsilon26 colitis model and that CD4+CD25+ cells may be the main regulators that prevent or downregulate the proinflammatory effect of colitogenic T cells in the Tgepsilon26 mouse model.

Inflammatory Bowel Disease: Autoimmune or Immune‐mediated Pathogenesis?

The pathogenesis of Crohn's disease (CD) and ulcerative colitis (UC), the two main forms of inflammatory bowel disease (IBD), is still unclear, but both autoimmune and immune-mediated phenomena are involved. Autoimmune phenomena include the presence of serum and mucosal autoantibodies against intestinal epithelial cells in either form of IBD, and against human tropomyosin fraction five selectively in UC. In addition, perinuclear antineutrophil cytoplasmic antibodies (pANCA) are common in UC, whereas antibodies against Saccharomyces cerevisiae (ASCA) are frequently found in CD. Immune-mediate phenomena include a variety of abnormalities of humoral and cell-mediated immunity, and a generalized enhanced reactivity against intestinal bacterial antigens in both CD and UC. It is currently believed that loss of tolerance against the indigenous enteric flora is the central event in IBD pathogenesis. Various complementary factors probably contribute to the loss of tolerance to commensal bacteria in IBD. They include defects in regulatory T-cell function, excessive stimulation of mucosal dendritic cells, infections or variants of proteins critically involved in bacterial antigen recognition, such as the products of CD-associated NOD2/CARD15 mutations.

The dominant immune response to intestinal bacterial antigens is ignorance, rather than tolerance

The dominant immune response to intestinal bacterial antigens is ignorance, rather than tolerance

Memory/effector T cells in TCR transgenic mice develop via recognition of enteric antigens by a second, endogenous TCR.

The majority of clonotypic CD4(+) T cells in the intestinal lamina propria of DO11.10 TCR transgenic mice have an activated/memory phenotype and produce effector cytokines despite the absence of prior exposure to ovalbumin (OVA), the transgene-specific antigen. A small number of splenic T cells have a similar phenotype. Clonotypic T cells from Peyer's patch are intermediate in both phenotype and effector cytokine production. Flow cytometric analysis of cells isolated from thymectomized, OVA-naive DO11.10 mice treated with continuous administration of BrdU indicated that a significant fraction of clonotype-positive T cells in the lamina propria and Peyer's patch were in the cell cycle, with significantly fewer cycling cells in the spleen. Most of the cycling cells from each anatomic site expressed low levels of CD45RB. Effector cytokine expression was enriched in the CD45RB(low) populations. These memory/effector cell populations were eliminated in DO11.10/SCID and DO11.10/RAG-2(-/-) mice, suggesting that recognition of non-OVA antigens through a second, non-clonotypic TCR was driving differentiation of memory/effector cells in naive BALB/c DO11.10 mice. Clonotypic CD4(+) T cells isolated from DO11.10, but not from DO11.10/SCID or DO11.10/RAG-2(-/-) mice, were stimulated to enter the cell cycle by antigen-presenting cells pulsed with an intestinal bacterial antigen extract. These data provide direct evidence that enteric bacterial antigens can activate transgenic T cells through a second, non-clonotypic TCR, and support the notion that the development and turnover of memory/effector cells in vivo is driven by the intestinal flora.

Age-associated changes in the proliferative response of rat intestinal intraepithelial leukocytes to bacterial antigens

Background & Aims : Intraepithelial leukocytes (IELs) residing in the intestinal epithelium are thought to recognize bacterial antigens and play an important role in providing protection against the invasion of microorganisms through the intestinal wall. This report studies the effect of various bacterial antigens on the proliferation of cultured IELs. Methods : Bacterial antigens, mycobacterial heat shock protein (hsp) 60 or 70, staphylococcal enteroxin A (SEA), or purified protein derivative (PPD) from Mycobacterium tuberculosis were added to mixed cultures of IELs and irradiated syngeneic or allogeneic spleen cells, and the proliferative response was evaluated. Monoclonal antibodies to CD4, CD8, and major histocompatibility complex class I or class II molecules were added to assess the role of these proteins in the proliferative response. Results : The proliferation of IELs isolated from mature rats in mixed culture was significantly enhanced by the addition of PPD, hsp 60, hsp 70, or SEA. The proliferation of mixed cultures of IELs isolated from young rats was enhanced only by the addition of SEA. In mixed cultures of mature rat IELs and syngeneic spleen cells containing PPD, proliferating populations were of the CD4 −CD8 + and CD4 +CD8 + phenotypes. Addition of anti-CD4 monoclonal antibody suppressed the proliferative response to PPD to control levels. Conclusions : IELs isolated from mature rats contain mycobacterial antigen-specific T cells, and these cells may be selected by long-term exposure to common intestinal bacterial antigens such as hsp. These cells may contain populations that recognize bacterial antigens in a CD4-dependent manner.

Influence of Intake of Skim Milk from Cows Immunized with Intestinal Bacterial Antigens on Onset of Renal Disease in (NZB × NZW)F1 Mice Fed Ad Libitum or Restricted in Energy Intake

Autoimmune disease-prone (NZB x NZW)F1 (B/W) female mice are a model of human lupus erythematosus. Immune milk, obtained from cows immunized with various intestinal bacterial antigens, was given to B/W mice as a component of diets beginning at 8 wk of age. Diets were fed ad libitum or restricted to 60% of ad libitum energy intake. Controls were fed commercial skim milk. In B/W mice fed ad libitum, the titers of anti-single-stranded DNA antibodies were significantly lower in immune milk-fed mice at 4 and 6 mo of age. Onset of proteinuria was delayed and life span was significantly prolonged by immune milk feeding. Surface phenotypes of the T cells and levels of the responsiveness of lymphocytes to mitogens were not changed by immune milk feeding. The B/W mice restricted to 60% of ad libitum energy intake, which preserved immune responsiveness, had not developed proteinuria by 14 mo of age, irrespective of immune milk feeding or control milk feeding. However, at 10 mo of age, the level of plasma antibodies against intestinal bacteria was significantly higher in energy-restricted mice fed control milk than in those fed immune milk or in mice fed ad libitum.

Arthritis associated with intestinal-bypass procedure for morbid obesity. Complement activation and characterization of circulating cryoproteins.

Five patients were studied after intestinal-bypass operations for morbid obesity to determine if the arthritis observed in three of these patients was associated with circulating cryoproteins. Only serum from the three patients with acute arthritis contained cryoprotein complexes. The complexes comprised IgG, IgM, IgA, complement components C3, C4, C5 and IgG antibody against Escherichia coli and Bacillus fragilis. The C3-activator fragment of the properdin complex was identified in fresh serum samples obtained from two of the three patients with circulating cryoprotein complexes and arthritis. These observations suggest that systemically absorbed intestinal bacterial antigens may lead to (or contribute to) the formation of circulating cryoprotein complexes. Circulating cryoprotein complexes activated both the classical and alternate complement pathways and may be important in the pathogenesis of the arthritis associated with the intestinal-bypass procedure for morbid obesity.