Abnormal intestinal permeability and microbiota in patients with autoimmune hepatitis

Background: Autoimmune hepatitis (AIH) is a chronic, progressive, and immunologically mediated inflammatory liver disorder. The etiology of AIH still remains unknown. The aim of this study was to investigate the changes in intestinal permeability, bacterial translocation, and intestinal microbiome in patients with AIH and to evaluate the correlations of those changes with the stages of the disease. Methods: 24 patients with autoimmune hepatitis and 8 healthy volunteers were recruited for this study. We assessed (1) the integrity of tight junctions within the gut by immunohistochemical analysis of zona occludens-1 and occludin expression in duodenal biopsy specimens; (2) changes in the enteric microbiome by 16S rDNA quantitative PCR; and (3) the presence of bacterial translocation by the level of lipopolysaccharide (LPS) using ELISA. Results: Increased intestinal permeability, derangement of the microbiome and bacterial translocation occurred in AIH, which correlated with the severity of the disease. Conclusions: Autoimmune hepatitis is associated with leaky gut and intestinal microbiome dysbiosis. The impaired intestinal barrier may play an important role in the pathogenesis of AIH.     

The intestinal microbiome in type 1 diabetes

Few concepts in recent years have garnered more disease research attention than that of the intestinal (i.e. ‘gut’) microbiome. This emerging interest has included investigations of the microbiome's role in the pathogenesis of a variety of autoimmune disorders, including type 1 diabetes (T1D). Indeed, a growing number of recent studies of patients with T1D or at varying levels of risk for this disease, as well as in animal models of the disorder, lend increasing support to the notion that alterations in the microbiome precede T1D onset. Herein, we review these investigations, examining the mechanisms by which the microbiome may influence T1D development and explore how multi‐disciplinary analysis of the microbiome and the host immune response may provide novel biomarkers and therapeutic options for prevention of T1D.     

Chinese liver fluke Clonorchis sinensis infection changes the gut microbiome and increases probiotic Lactobacillus in mice

Chinese liver fluke Clonorchis sinensis changes the host’s immune system. Recently, it has been reported that helminths including C. sinensis can ameliorate immune-related diseases such as allergy. In addition, recent studies showed that helminth infection can alleviate immune-mediated disorders by altering the gut microbiome. However, changes in the gut microbiome due to C. sinensis have not been reported yet. In this study, changes in the gut microbiome of C57BL/6 mice infected with C. sinensis metacercariae were evaluated over time. Stool was analyzed by 16S rRNA amplicon analysis using high-throughput sequencing technology. There was no apparent difference in species richness and diversity between the infected and control groups. However, the composition of the microbiome was different between the infected and control groups at 20 days and 30 days post-infection, and the difference disappeared at 50 days post-infection. In particular, this microbiome alteration was associated with a change in the relative abundance of genus Lactobacillus and the probiotic Lactobacillus species that are known to have an immune-modulation role in immune-mediated diseases.

     

Antibiotic Exposure and Reduced Short Chain Fatty Acid Production after Hematopoietic Stem Cell Transplant

Human studies have shown loss of diversity of the gut microbiome following hematopoietic stem cell transplantation (HSCT) in association with significant gut injury caused by the preparative regimen. Prolonged antibiotic use worsens loss of microbiome diversity and increases risk of complications such as graft-versus-host disease (GVHD). Our data support the hypothesis that loss of intestinal commensals that produce short-chain fatty acids (SCFAs) may increase dysbiosis. Here, we report an extensive longitudinal examination of changes in the luminal SCFAs in children undergoing allogeneic HSCT, and the relationship of those changes to the microbiota and antibiotic exposure. We found significant and progressive alterations in butyrate, and in additional SCFAs in stool in the first 14 days after transplant, a finding not observed in published mouse studies. SCFA levels were lower in children receiving antibiotics with activity against anaerobic organisms. Moreover, day 14 post-HSCT butyrate and propionate levels are lower in children who went on to develop GVHD, although our disease population was small. These data provide insight into the mechanism of prior observations that loss of diversity and increased antibiotic use are associated with GVHD following HSCT. Our findings offer potential modifiable targets to reduce risk of GVHD and improve survival after HSCT.     

The microbiome in autoimmune diseases

The microbiome is represented by microorganisms which live in a symbiotic way with the mammalian. Microorganisms have the ability to influence different physiological aspects such as the immune system, metabolism and behaviour. In recent years, several studies have highlighted the role of the microbiome in the pathogenesis of autoimmune diseases. Notably, in systemic lupus erythematosus an alteration of the intestinal flora (lower Firmicutes/Bacteroidetes ratio) has been described. Conversely, changes to the gut commensal and periodontal disease have been proposed as important factors in the pathogenesis of rheumatoid arthritis. At the same time, other autoimmune diseases (i.e. systemic sclerosis, Sjögren’s syndrome and anti-phospholipid syndrome) also share modifications of the microbiome in the intestinal tract and oral flora. Herein, we describe the role of the microbiome in the maintenance homeostasis of the immune system and then the alterations of the microorganisms that occur in systemic autoimmune diseases. Finally, we will consider the use of probiotics and faecal transplantation as novel therapeutic targets.     

Pros and cons: Is faecal microbiota transplantation a safe and efficient treatment option for gut dysbiosis?

Faecal Microbiota Transplantation (FMT) is well established as an effective treatment for Clostridioides difficile infection (CDI), restoring gut microbiome diversity and function. The utility of FMT is currently being explored in relation to other immune-mediated pathologies, such as allergic disease, inflammatory bowel diseases and autoimmune diseases. Clinical trials in these areas are ongoing, and the altered gut microbiota (dysbiosis) that is often observed in these pathologies provides a rationale for the application of FMT to restore the microbiome. However, there is controversy on the risk-benefit ratio as it relates to the use of FMTs in pathologies other than CDI. In this Pro and Con article, we present the arguments for and against the use of FMT in immune-mediated pathologies, such as allergic disease. We further identify research gaps and recommend how these may be addressed in future studies.     

A polysaccharide from the human commensal Bacteroides fragilis protects against CNS demyelinating disease

The intestinal microbiome may have a critical roll in susceptibility or resistance to immune-mediated diseases. Alterations of the gut microflora after oral antibiotic treatment can regulate encephalomyelitis (EAE), an animal model for human multiple sclerosis (MS). We now show that a zwitterionic capsular polysaccharide A (PSA) of Bacteroides fragilis can protect against central nervous system demyelinating disease. Oral administration with purified PSA protected mice against EAE prophylactic and therapeutically. PSA treatment enhanced CD103 expressing dendritic cells (DCs) that accumulated in the cervical lymph nodes. Exposure of naïve DCs to PSA induced the conversion of naïve CD4⁺ T cells into interleukin (IL)-10-producing FoxP3⁺Treg cells. Protection against EAE was completely abrogated in IL-10-deficient mice. Our results show an important role for a molecule from human commensal bacteria in protecting against EAE and suggest the possibility for protection in MS.     

Depressive symptoms in inflammatory bowel disease: an extraintestinal manifestation of inflammation?

Depressive symptoms are reported by more than 20% of people with inflammatory bowel disease (IBD), while sleep difficulties and fatigue are even more common. Co-morbid depressive symptoms predict a poor IBD course, including increased risk of relapse and surgery, which is inconsistently improved by psychological treatments. Rather than being distinct systems, there is compelling evidence for bidirectional communication between gut and brain, driven by neural, metabolic, endocrine and inflammatory mediators. An emerging concept is that depressive symptoms may be mechanistically linked to excess inflammation and dysregulation of the gut–brain axis. Given the close link between the intestinal microbiota and host immune responses, patients prone to shifts in their intestinal microbiome, including smokers, those with poor diet and early life stress, may be exposed to exaggerated immune responses. Excess inflammation is associated with brain changes (depressive symptoms, fatigue, sleep difficulties) and worsening gastrointestinal symptoms, which are exacerbated by psychological distress. Equally, treatments both for depressive symptoms and IBD provide opportunities to break this cycle by reducing the causes and effects of inflammation. As well as addressing potential risk factors such as smoking and diet, treatments to alter the microbiome may reduce depressive symptoms. Observational evidence suggests that anti-inflammatory treatments for IBD may improve co-morbid depressive symptoms correlating with reduction in inflammation. With a growing range of treatments targeting inflammation centrally, peripherally and in the gut, IBD provides a unique model to understand the interplay between brain and gut in the pathogenesis of depressive symptoms, both in IBD and in the whole population.     

Predominant donor CD103+CD8+ T cell infiltration into the gut epithelium during acute GvHD: a role of gut lymph nodes

The existence of donor effector cell subsets responsible foreither gut or skin graft-versus-host disease (GvHD) is stillundetermined. We examined the trafficking and role of donorCD8⁺ intra-epithelial lymphocytes (IELs) in the gut and skinepithelia concerning Eβ7 integrin (CD103) expression, usinga rat acute lethal GvHD model. Most CD103⁺ donor cells wereCD8⁺ and showed a proliferative activity in the target epithelia.On the other hand, activated donor T cells in the host lymphoidtissues did not express CD103, indicating the presence of CD8⁺IEL precursors in the lymphoid tissues that may up-regulateCD103 only after migrating to the target organs. At the latestage of GvHD, while >80% of the donor CD8⁺ IELs were CD103⁺in the gut epithelium, both CD4⁺ and CD103⁺CD8⁺ T cells evenlyaccumulated in the skin epidermis. The CD103 expression by donorCD8⁺ IELs especially in the gut was also correlated with theclinical GvHD manifestations. Furthermore, the selective removalof gut lymph nodes (LNs) but not skin LNs suppressed the infiltrationof CD103⁺ donor IELs in the gut and alleviated intestinal GvHD.In conclusion, CD103⁺CD8⁺ donor T cells predominantly infiltrateinto the gut epithelium and are responsible for the manifestationsof intestinal GvHD. This pathology is at least partly dependenton the gut LNs.     

The gut microbiome: a clinically significant player in transplantation?

The intestinal microbiome is critical to digestion, metabolism and protection from pathogenic organisms. Dysbiosis, or alteration of this microbiome, can result in Clostridium difficile infection and may play a role in other conditions. Patients undergoing solid organ transplantation (e.g., kidney, lung, liver, small bowel) and hematopoietic stem cell transplantation have a shift in the gut microbiome with a decrease in predominant organisms, a loss of bacterial diversity and emergence of a new dominant population. This translates into increased morbidity and mortality with risk of infection and rejection. We discuss the changes seen in the microbiome and its possible consequences. It may be important to develop strategies to restore the normal microbiome in such patients.     

Gutsy sensations modulate intestinal disease

Pain is a hallmark symptom associated with intestinal inflammation. Two related articles published in Cell by Zhang et al. and by Yang et al. now report how sensory neurons in the gut, the most heavily innervated organ in the human body, flag bacterial pathogens to shape the composition of the gut microbiome and to trigger immunoregulatory mechanisms.     

How the evolving epidemics of opioid misuse and HIV infection may be changing the risk of oral sexually transmitted infection risk through microbiome modulation

Abstract

The epidemiology of sexually transmitted infections (STI) is constantly evolving, and the mechanisms of infection risk in the oral cavity (OC) are poorly characterized. Evidence indicates that microbial community (microbiota) compositions vary widely between the OC, genitalia and the intestinal and rectal mucosa, and microbiome-associated STI susceptibility may also similarly vary. The opioid misuse epidemic is at an epidemic scale, with >11 million US residents misusing in the past 30?days. Opioids can substantially influence HIV progression, microbiota composition and immune function, and these three factors are all mutually influential via direct and indirect pathways. While many of these pathways have been explored independently, the supporting data are mostly derived from studies of gut and vaginal microbiotas and non-STI infectious agents. Our purpose is to describe what is known about the combination of these pathways, how they may influence microbiome composition, and how resultant oral STI susceptibility may change. A better understanding of how opioid misuse influences oral microbiomes and STI risk may inform better mechanisms for oral STI screening and intervention. Further, the principles of interaction described may well be applied to other aspects of disease risk of other health conditions which may be impacted by the opioid epidemic.     

Lactobacillus rhamnosus reduces CD8+T cell mediated inflammation in patients with rheumatoid arthritis

BackgroundThe T cells, components of adaptive immunity participate in immune pathology of the autoimmune inflammatory disorder called rheumatoid arthritis (RA). The presence of TLRs on the surface of the CD8⁺ T cells and their ability to recognize bacterial moieties adds to the inflammatory burden in case of RA. It has been reported that the gut microbiome is necessary for the crucial shift in the balance between proinflammatory and anti-inflammatory cytokines. The altered gut microbiome and the presence of TLRs emphasizes on the microbiome driven inflammatory responses in case of RA.MethodsEighty-nine RA patients participated in this study. Clinical variations like disease duration, number of actively inflamed joints, number and type of bone deformities, CRP, RF, Anti-CCP, ESR, DAS 28 score were recorded for each patient. Co-culture of CD8⁺T cells and bacteria has been performed with proper culture condition. TLRs and inflammatory mediators’ expression level were checked by both qPCR and flow cytometry analysis.ResultsWe observed in the suppression of pro-inflammatory molecules like Granzyme B and IFNƳ and expression of TLR2 in CD8 + T cells upon treatment with Lactobacillus rhamnosus (L. rhamnosus). Moreover, L. rhamnosus activated CD8⁺T cells such that they could induce FOXP3 expression in CD4⁺T cells thereby skewing T cell population towards a regulatory phenotype. On the contrary, TLR4 engagement on CD8⁺T cell by Escherichia coli (E.coli) increased in inflammatory responses following ERK activation.ConclusionsThus, we conclude that L. rhamnosus can effectively suppress CD8⁺T cell mediated inflammation by a simultaneous decrease of Th1 cells that may potentiate better treatment modalities for RA.     

The Effect of Formula-based Nutritional Treatment on Colitis in a Murine Model

BackgroundExclusive enteral nutrition (EEN) induces remission in pediatric Crohn''s disease (CD). The exact mechanism of EEN therapy in CD is unknown, but alteration of the intestinal microflora after EEN is thought to affect mucosal healing. To determine the link between EEN therapy and therapeutic efficacy in CD, we established a murine model of dextran sulfate sodium (DSS)-induced colitis and applied EEN therapy.MethodsEight-week-old C57BL/6 mice were administered DSS for 4 days to induce colitis, and either normal chow (NC) or EEN was administered for the following 4 days. The mice were grouped according to the feeding pattern after DSS administration: DSS/NC and DSS/EEN groups. The clinical course was confirmed via daily observation of the weight and stool. Fecal samples were collected and 16sRNA sequencing was used. The mice were sacrificed to confirm colonic histopathology.ResultsWeight reduction and increase in disease activity were observed as the day progressed for 4 days after DSS administration. There was significant weight recovery and improvement in disease activity in the EEN group compared to that in the NC group. Verrucomicrobia and Proteobacteria abundances tended to increase and Bacteroidetes abundance decreased in the EEN group. In the EEN group, significant changes in the β-diversity of the microbiota were observed. In the analysis of microbiome species, abundances of Akkermansia muciniphila, Clostridium cocleatum, mucin-degrading bacteria, Flintibacter butyricus, and Parabacteroides goldsteinii, which are beneficial microbiota, were significantly increased in the EEN group compared to those in the NC group. More abundant mucins were confirmed in the colonic histopathology of the EEN group. These microbial and histopathological differences suggested that EEN might improve colitis symptoms in a murine colitis model by promoting mucin recycling and subsequently inducing the healing effect of the gut barrier.ConclusionEEN showed clinical efficacy in a murine model of colitis. Based on the increase in mucin-degrading bacteria and the pathological increase in mucin production after EEN administration, it can be observed that mucin plays an important role in the therapeutic effect of EEN.     

Nod2 influences microbial resilience and susceptibility to colitis following antibiotic exposure

Inflammatory bowel disease (IBD) etiology involves genetic susceptibility, environmental triggers, and the gut microbiome. Antibiotic exposure is associated with IBD, both in early life and adulthood. Here, we investigated whether Nod2-deficiency influenced response of the gut microbiota to antibiotics and subsequent colitis susceptibility. Wild-type and Nod2^−/− littermate mice were treated with amoxicillin as adults or neonates, and fecal samples were collected for 16S rRNA sequencing. Five weeks after antibiotic exposure, dextran sulfate sodium (DSS) colitis was induced. Antibiotic treatment altered the microbiota of adult WT and Nod2^−/− mice, but recovery was delayed in Nod2^−/− mice. Neonatal antibiotic treatment significantly changed the microbiota at weaning in WT and Nod2^−/− littermates; however, Nod2^−/− mice maintained reduced microbial diversity 14 days after cessation of antibiotics. Although treatment of adult mice did not influence susceptibility to colitis, neonatally treated Nod2^−/− mice developed a more severe colitis. Moreover, the colitis phenotype was transferable through fecal transplantation into germ-free Nod2^−/− recipients, and was associated with changes in intestinal T cells and the cytokine milieu following inflammation. These data demonstrate that neonatal antibiotic exposure has long-lasting influence on the microbiota and mucosal immunity, and may explain how NOD2 contributes to the risk of intestinal inflammation.     

Effect of Trichinella spiralis intervention on TNBS-induced experimental colitis in mice

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn’s disease (CD), are chronic autoimmune diseases with a high recurrence rate. Epidemiological data have shown that the incidence of IBD increases annually because of improved sanitary conditions and reduced parasitic infection rates. In this experiment, experimental colitis was induced in mice by administering 2,4,6-trinitrobenzene sulfonic acid (TNBS) 28?days after they were infected with Trichinella spiralis to confirm that T. spiralis infection could alleviate the severity of TNBS-induced colitis.Thirty-six male BALB/c mice aged 6–8 weeks were randomly divided into four groups: control group (with 50% ethanol, Control), T. spiralis-infected group (TS-Control), TNBS-induced colitis model group (Colitis), and T. spiralis-pre-infected and TNBS-induced colitis group (TS-Colitis). The mice were sacrificed 3, 7, and 14?days after the model was established. Changes in various colitis indicators to investigate the effect of T. spiralis infection on TNBS-induced murine CD model.Results showed that the weight, DAI score, and macroscopic and microscopic colon damage in the TS-Colitis significantly decreased compared with those in the Colitis. ELISA revealed that the IFN-γ expression decreased and the IL-4 expression increased in the TS-Colitis compared with those in the Colitis. Western Blotting results revealed that the NF-κB expression increased in the Colitis and higher than those in the TS-Colitis. And Flow cytometry results revealed that the percentage of CD4+CD25+Foxp3+ Treg cells significantly increased in the TS-Colitis.T. spiralis-infected mice induced Th2 immune responses and balanced Th1 immune responses stimulated by TNBS to ameliorate intestinal inflammation.     

Cellular and molecular mechanisms underlying NOD2 risk-associated polymorphisms in Crohn's disease

The discovery that polymorphisms in the NOD2 (nucleotide-binding oligomerization domain containing 2) gene are associated with a greatly increased risk for the development of Crohn's disease has provided a means to achieve a deeper understanding of the dysregulation of mucosal immune responses to the commensal intestinal organisms that is thought to underlie this disease. NOD2 is a NOD-like receptor (NLR) family member that senses and responds to bacterial wall peptides; thus, the most widely held view of the relation of the NOD2 polymorphisms with Crohn's disease is that these polymorphisms lead to deficient immune responses to gut bacteria, and these, in turn, lead to quantitative or qualitative changes in the bacterial population in the gut lumen or lamina propria that cause inflammation at this site. Initially, this view was based mainly on the observation that defective NOD2 function can result in reduced α-defensin production by intestinal Paneth cells and that such impairment leads to loss of host defense against gut bacteria. In this review, we reconsider this possibility and marshal evidence that it is not in fact likely to be a prime element of Crohn's disease causation. More recently, evidence has been accumulating that the NOD2 dysfunction leads to Crohn's inflammation by inducing changes in the gut microbiome that influence immune effector or regulatory function. We review the strengths and weaknesses of this emerging hypothesis. Finally, we consider the possibility that NOD2 dysfunction can lead to inflammation because of a second and somewhat overlooked aspect of its function, that as an immunoregulator of innate immune responses. In particular, we review the body of evidence that NOD2 stimulation activates a cross-tolerance response that downregulates and thus prevents excessive TLR responses that cause Crohn's inflammation.     

Neonate Antigen Presenting Cells within Murine Intestinal Muscular Layer

The intestinal mucosa is exposed to a vast antigenic contact. Several antigen presenting cell (APCs) have been described within the gut associated lymphoid tissue (GALT) (Peyer’s patches, lamina propria, mesenteric lymph nodes, muscular layer); however, this has been done almost exclusively in adult organisms. As there is no characterization of intestinal muscular layer’s APCs during early neonate development we adapted the conventional technique used in adults, to the neonate intestine. We obtained the intestinal muscular layer from early neonates (days 0–3 upon birth) and from young mice (2 and 3 weeks after birth). A planar network of CD45⁺, MHC-II⁺, DEC-205⁺ cells with irregular, some with prominent dendritic morphology was found at birth under basal physiological conditions, whereas Langerin⁺ DCs appeared after two weeks. The variations seen in CD45⁺, MHC-II⁺ and DEC-205⁺ cells along the early neonatal development, could be related to the new challenges by intestinal antigen exposure from the newborn diet (breast milk, solid food), and to important environmental changes (start walking, exploring the surroundings, etc). Our study reveals the presence of APCs in intestinal muscular layer at birth, and their subsequent changes in physiological, non-induced conditions, contributing basic information about these cells in the neonate intestinal immune system.     

The association between early life antibiotic use and allergic disease in young children: recent insights and their implications

ABSTRACT

Introduction: Greater prescribing of antibiotics to infants has coincided with an epidemic of allergic disease. Through meta-analytic synthesis, accumulating evidence from prospective or database cohorts suggests a link between infant antibiotic treatment and the development of atopy. Stronger associations seen with multiple course and broad-spectrum antibiotic treatment add to biological plausibility. A major bias, confounding by indication, has been addressed in studies on antibiotic treatment of conditions which do not precede allergic disease.

Areas covered: Our review provides an up-to-date synthesis of the current literature on associations between infant antibiotic exposure and future allergic disease. We discuss methods that assist in reducing study bias and look at new insights from studies of the infant gut microbiome.

Expert commentary: Large-scale profiling of the gut microbiome provides a new tool for disentangling biases found in observational studies of infant antibiotic use. To date, microbial dysbiosis of the infant gut has been reported to predict allergic disease independent of antibiotic exposure up to 3 months after birth. However, these studies have not accounted for antibiotic treatment in later infancy. Continued study of the infant gut microbiome, mycobiome, or resistome will provide a closer link to antibiotic treatment or refute it as a cause of allergic disease.     

Direct cloning and tetramer staining to measure the frequency of intestinal gluten‐reactive T cells in celiac disease

Knowledge of the frequency of disease‐driving CD4⁺ T cells in lesions of chronic human inflammatory diseases is limited. In celiac disease (CD), intestinal gluten‐reactive CD4⁺ T cells, which recognize gluten peptides only in the context of the disease‐associated HLA‐DQ molecules, are key pathogenic players. By cloning CD4⁺ T cells directly from intestinal biopsies of CD patients, we found that 0.5–1.8% of CD4⁺ T cells were gluten reactive. About half of the gluten‐reactive T cells were specific for either the immuno‐dominant DQ2.5‐glia‐α1a or DQ2.5‐glia‐α2 epitopes, suggesting that direct visualization of gluten‐specific T cells could be possible. Assessed by flow cytometry, tetramer‐positive T cells were present in 10/10 untreated CD patients with a frequency of 0.1–1.2% of CD4⁺ T cells. Gluten‐specific T cells were also detectable in most treated CD patients (7/10). Moreover, the frequency of gluten‐specific T cells correlated with the degree of histological damage in the gut mucosa as scored by Marsh‐grading, and also with serum IgA anti‐transglutaminase 2 antibody levels. Tetramer staining of gluten‐reactive T cells in biopsy material is a useful tool for future studies of such cells in CD and could also potentially serve as a diagnostic supplement in selected cases.