Latiglutenase Protects the Mucosa and Attenuates Symptom Severity in Patients With Celiac Disease Exposed to a Gluten Challenge.

BACKGROUND & AIMS: Gluten ingestion in patients with celiac disease can lead to gastrointestinal symptoms and small intestinal mucosal injury. METHODS: This gluten challenge phase 2 trial was double blind and placebo controlled, and it assessed the efficacy and safety of a 1200-mg dose of IMGX003 in patients with celiac disease exposed to 2 g of gluten per day for 6 weeks. The change in the ratio of villus height to crypt depth was the primary endpoint. Secondary endpoints included density of intraepithelial lymphocytes and symptom severity. These endpoints were evaluated by analysis of covariance. Additional endpoints included serology and gluten-immunogenic peptides in urine. RESULTS: Fifty patients were randomized, and 43 patients completed the study (IMGX003, n = 21; placebo, n = 22). The mean change in the ratio of villus height to crypt depth (primary endpoint) for IMGX003 vs placebo was -0.04 vs -0.35 (P = .057). The mean change in the density of intraepithelial lymphocytes (secondary endpoint) for IMGX003 vs placebo was 9.8 vs 24.8 cells/mm epithelium (P = .018). The mean change (worsening) in symptom severity in relative units (secondary endpoint) for IMGX003 vs placebo was 0.22 vs 1.63 (abdominal pain, P = .231), 0.96 vs 3.29 (bloating, P = .204), and 0.02 vs 3.20 (tiredness, P = .113). The 3 × 2-week trend line significance values for these symptoms, respectively, were P = .014, .030, and .002. CONCLUSIONS: IMGX003 reduced gluten-induced intestinal mucosal damage and symptom severity. (ClinicalTrials.gov, Number: NCT03585478).

Administration of Human Derived Upper gut Commensal Prevotella histicola delays the onset of type 1 diabetes in NOD mice.

BACKGROUND: Type 1 diabetes (T1D) is an autoimmune disease that is increasing in prevalence worldwide. One of the contributing factors to the pathogenesis of T1D is the composition of the intestinal microbiota, as has been demonstrated. in T1D patients, with some studies demonstrating a deficiency in their levels of Prevotella. We have isolated a strain of Prevotella histicola from a duodenal biopsy that has anti-inflammatory properties, and in addition, alters the development of autoimmune diseases in mouse models. Therefore, our hypothesis is that the oral administration of P. histicola might delay the development of T1D in the non-obese diabetic (NOD) mice. To assess this, we used the following materials and methods. Female NOD mice (ages 5-8 weeks) were administered every other day P. histicola that was cultured in-house. Blood glucose levels were measured every other week. Mice were sacrificed at various time points for histopathological analysis of the pancreas. Modulation of immune response by the commensal was tested by analyzing regulatory T-cells and NKp46+ cells using flow cytometry and intestinal cytokine mRNA transcript levels using quantitative RT-PCR. For microbial composition, 16 s rRNA gene analysis was conducted on stool samples collected at various time points. RESULTS: Administration of P. histicola in NOD mice delayed the onset of T1D. Beta diversity in the fecal microbiomes demonstrated that the microbial composition of the mice administered P. histicola was different from those that were not treated. Treatment with P. histicola led to a significant increase in regulatory T cells with a concomitant decrease in NKp46+ cells in the pancreatic lymph nodes as compared to the untreated group after 5 weeks of treatment. CONCLUSIONS: These observations suggest that P. histicola treatment delayed onset of diabetes by increasing the levels of regulatory T cells in the pancreatic lymph nodes. This preliminary work supports the rationale that enteral exposure to a non pathogenic commensal P. histicola be tested as a future therapy for T1D.

Compositional change of gut microbiome and osteocalcin expressing endothelial progenitor cells in patients with coronary artery disease.

Osteogenic endothelial progenitor cells (EPCs) contribute to impaired endothelial repair and promote coronary artery disease (CAD) and vascular calcification. Immature EPCs expressing osteocalcin (OCN) has been linked to unstable CAD; however, phenotypic regulation of OCN-expressing EPCs is not understood. We hypothesized that gut-microbiome derived pro-inflammatory substance, trimethylamine N-oxide (TMAO) might be associated with mobilization of OCN-expressing EPCs. This study aimed to investigate the association between dysbiosis, TMAO, and circulating mature and immature OCN-expressing EPCs levels in patients with and without CAD. We included 202 patients (CAD N = 88; no CAD N = 114) who underwent assessment of EPCs using flow cytometry and gut microbiome composition. Mature and immature EPCs co-staining for OCN were identified using cell surface markers as CD34+/CD133-/kinase insert domain receptor (KDR)+ and CD34-/CD133+/KDR+ cells, respectively. The number of observed operational taxonomy units (OTU), index of microbial richness, was used to identify patients with dysbiosis. The number of immature OCN-expressing EPCs were higher in patients with CAD or dysbiosis than patients without. TMAO levels were not associated with circulating levels of OCN-expressing EPCs. The relative abundance of Ruminococcus gnavus was moderately correlated with circulating levels of immature OCN-expressing EPCs, especially in diabetic patients. Gut dysbiosis was associated with increased levels of TMAO, immature OCN-expressing EPCs, and CAD. The relative abundance of Ruminococcus gnavus was correlated with immature OCN-expressing EPCs, suggesting that the harmful effects of immature OCN-expressing EPCs on CAD and potentially vascular calcification might be mediated by gut microbiome-derived systemic inflammation.

Human gut-derived commensal suppresses generation of T-cell response to gliadin in humanized mice by modulating gut microbiota.

The human intestinal tract is colonized by a large number of diverse microorganisms that play various important physiologic functions. In inflammatory gut diseases including celiac disease (CeD), a dysbiotic state of microbiome has been observed. Interestingly, this perturbed microbiome is normalized towards eubiosis in patients showing recovery after treatment. The treatment has been observed to increase the abundance of beneficial microbes in comparison to non-treated patients. In this study, we investigated the effect of Prevotella histicola or Prevotella melaninogenica, isolated from the duodenum of a treated CeD patient, on the induction and maintenance of oral tolerance to gliadin, a CeD associated subgroup of gluten proteins, in NOD.DQ8.ABo transgenic mice. Conventionally raised mice on a gluten free diet were orally gavaged with bacteria before and after injection with pepsin trypsin digested gliadin (PTD-gliadin). P. histicola suppressed the cellular response to gliadin, whereas P. melaninogenica failed to suppress an immune response against gliadin. Interestingly, tolerance to gliadin in NOD.DQ8.ABo mice may be associated with gut microbiota as mice gavaged with P melaninogenica harbored a different microbial diversity as compared to P. histicola treated mice. This study provides experimental evidence that gut microbes like P. histicola from treated patients can suppress the immune response against gliadin epitopes.

IL-15, gluten and HLA-DQ8 drive tissue destruction in coeliac disease.

Coeliac disease is a complex, polygenic inflammatory enteropathy caused by exposure to dietary gluten that occurs in a subset of genetically susceptible individuals who express either the HLA-DQ8 or HLA-DQ2 haplotypes1,2. The need to develop non-dietary treatments is now widely recognized3, but no pathophysiologically relevant gluten- and HLA-dependent preclinical model exists. Furthermore, although studies in humans have led to major advances in our understanding of the pathogenesis of coeliac disease4, the respective roles of disease-predisposing HLA molecules, and of adaptive and innate immunity in the development of tissue damage, have not been directly demonstrated. Here we describe a mouse model that reproduces the overexpression of interleukin-15 (IL-15) in the gut epithelium and lamina propria that is characteristic of active coeliac disease, expresses the predisposing HLA-DQ8 molecule, and develops villous atrophy after ingestion of gluten. Overexpression of IL-15 in both the epithelium and the lamina propria is required for the development of villous atrophy, which demonstrates the location-dependent central role of IL-15 in the pathogenesis of coeliac disease. In addition, CD4+ T cells and HLA-DQ8 have a crucial role in the licensing of cytotoxic T cells to mediate intestinal epithelial cell lysis. We also demonstrate a role for the cytokine interferon-γ (IFNγ) and the enzyme transglutaminase 2 (TG2) in tissue destruction. By reflecting the complex interaction between gluten, genetics and IL-15-driven tissue inflammation, this mouse model provides the opportunity to both increase our understanding of coeliac disease, and develop new therapeutic strategies.

Coronary artery disease is associated with an altered gut microbiome composition.

Alteration of gut microbiome composition has been linked to cardiovascular diseases. To identify specific bacterial communities associated with coronary artery diseases (CAD), we conducted a case-control study with 53 advanced CAD patients and 53 age-, sex-, race-, and BMI-matched controls. V3-V5 regions of the 16S rDNA from the fecal gut material were analyzed to compare the gut microbiome composition between CAD patients and controls. The alpha diversity, including Chao-1, Shannon-index, and the number of observed taxonomy units were significantly decreased in CAD patients indicating, decreased richness and evenness of gut microbiome. Among 23 different abundant taxa at the genus level, 12 taxa belonged to Lachnospiraceae family, which are known to produce butyrate. Further, we identified five taxa which showed more than two log-fold changes with maximum proportion >0.002, including Ruminococcus gnavus, Lachnospiraceae anaerosporobacter, Lachnospiraceae NK4B4 group, Lachnospiraceae UCG-004, and Ruminococcus gauvreauii. After adjustment for coronary risk factors (diabetes mellitus and dyslipidemia), decreased relative abundance of Lachnospiraceae NK4B4 group and Ruminococcus Gauvreauii and increased relative abundance of Ruminococcus gnavus were associated with the presence of advanced CAD. The observed differences in taxa between CAD patients and controls in this study may provide insight into the link between the gut microbiome and CAD.

Role of the intestinal microbiome in autoimmune diseases and its use in treatments.

The role of the intestinal microbiome in the pathogenesis of autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, and type 1 diabetes is being increasingly appreciated. Many studies have reported that the compositions of the intestinal microbiomes of patients with these autoimmune diseases are different from those of healthy individuals. Analyses of the intestinal microbiome of humans suggest that various factors affect the composition of the intestinal microbiome, including, but not limited to: geographical location, diet, sex, and age. However, patients with rheumatoid arthritis and type 1 diabetes show unique intestinal microbiome profile even after considering these confounding factors. This review will describe the known differences in the microbial composition for each of the aforementioned autoimmune diseases, how it impacts the immune system, and how these compositions may potentially be modulated by treatments with probiotics, prebiotics, and other microbiome altering therapies.

Microbiome, Immunomodulation, and the Neuronal System.

Vertebrates harbor both symbiotic and pathogenic bacteria on the body and various mucosal surfaces. Of these surfaces, the intestine has the most diverse composition. This composition is dependent upon various environmental and genetic factors, with diet exerting the maximum influence. Significant roles of the intestinal bacteria are to stimulate the development of a competent mucosal immune system and to maintain tolerance within the intestine. One manner in which this is achieved is by the establishment of epithelial integrity by microbiota found in healthy individuals (healthy microbiota); however, in the case of a disrupted intestinal microbiome (dysbiosis), which can be caused by various conditions, the epithelial integrity is compromised. This decreased epithelial integrity can then lead to luminal products crossing the barrier, generating a systemic proinflammatory response. In addition to epithelial integrity, healthy intestinal commensals metabolize indigestible dietary substrates and produce short-chain fatty acids, which are bacterial metabolites that are essential for colonic health and regulating the function of the intestinal immune system. Intestinal commensals are also capable of producing neuroactive molecules and neurotransmitters that can affect the function of the vagus nerve. The observations that intestinal dysbiosis is associated with different diseases of the nervous system, suggests that cross-talk occurs amongst the gut, the nervous system, and the immune system.