Project description:Host NOD-like receptor family pyrin domain-containing 6 (NLRP6) regulates innate immune responses and gastrointestinal homeostasis. Its protective role in intestinal colitis and tumorigenesis is dependent on the host microbiome. Host innate immunity and microbial diversity also play a role in the severity of allogeneic immune-mediated gastrointestinal graft-versus-host disease (GVHD), the principal toxicity after allogeneic haematopoietic cell transplantation. Here, we examined the role of host NLRP6 in multiple murine models of allogeneic bone marrow transplantation. In contrast to its role in intestinal colitis, host NLRP6 aggravated gastrointestinal GVHD. The impact of host NLRP6 deficiency in mitigating GVHD was observed regardless of co-housing, antibiotic treatment or colonizing littermate germ-free wild-type and NLRP6-deficient hosts with faecal microbial transplantation from specific pathogen-free wild-type and Nlrp6-/- animals. Chimaera studies were performed to assess the role of NLRP6 expression on host haematopoietic and non-haematopoietic cells. The allogeneic [B6Ly5.2 → Nlrp6-/-] animals demonstrated significantly improved survival compared to the allogeneic [B6Ly5.2 → B6] animals, but did not alter the therapeutic graft-versus-tumour effects after haematopoietic cell transplantation. Our results unveil an unexpected, pathogenic role for host NLRP6 in gastrointestinal GVHD that is independent of variations in the intestinal microbiome and in contrast to its well-appreciated microbiome-dependent protective role in intestinal colitis and tumorigenesis.
Project description:Microbial transformation of bile acids affects intestinal immune homeostasis but its impact on inflammatory pathologies remains largely unknown. Using a mouse model of graft-versus-host disease (GVHD), we found that T cell-driven inflammation decreased the abundance of microbiome-encoded bile salt hydrolase (BSH) genes and reduced the levels of unconjugated and microbe-derived bile acids. Several microbe-derived bile acids attenuated farnesoid X receptor (FXR) activation, suggesting that loss of these metabolites during inflammation may increase FXR activity and exacerbate the course of disease. Indeed, mortality increased with pharmacological activation of FXR and decreased with its genetic ablation in donor T cells during mouse GVHD. Furthermore, patients with GVHD after allogeneic hematopoietic cell transplantation showed similar loss of BSH and the associated reduction in unconjugated and microbe-derived bile acids. Additionally, the FXR antagonist ursodeoxycholic acid reduced the proliferation of human T cells and was associated with a lower risk of GVHD-related mortality in patients. We propose that dysbiosis and loss of microbe-derived bile acids during inflammation may be an important mechanism to amplify T cell-mediated diseases.
Project description:Dermatologists are ideally suited to manage the various cutaneous sequelae of graft-versus-host disease (GVHD) outlined in part I of this review. However, the complexity of the patient with GVHD, including comorbidities, potential drug interactions related to polypharmacy, and the lack of evidence-based treatment guidelines, are significant challenges to optimizing patient care. In this section, we will provide an outline for the role of the dermatologist in a multispecialty approach to caring for patients with GVHD.
Project description:Microbial transformation of bile acids affects intestinal immune homoeostasis but its impact on inflammatory pathologies remains largely unknown. Using a mouse model of graft-versus-host disease (GVHD), we found that T cell-driven inflammation decreased the abundance of microbiome-encoded bile salt hydrolase (BSH) genes and reduced the levels of unconjugated and microbe-derived bile acids. Several microbe-derived bile acids attenuated farnesoid X receptor (FXR) activation, suggesting that loss of these metabolites during inflammation may increase FXR activity and exacerbate the course of disease. Indeed, mortality increased with pharmacological activation of FXR and decreased with its genetic ablation in donor T cells during mouse GVHD. Furthermore, patients with GVHD after allogeneic hematopoietic cell transplantation showed similar loss of BSH and the associated reduction in unconjugated and microbe-derived bile acids. In addition, the FXR antagonist ursodeoxycholic acid reduced the proliferation of human T cells and was associated with a lower risk of GVHD-related mortality in patients. We propose that dysbiosis and loss of microbe-derived bile acids during inflammation may be an important mechanism to amplify T cell-mediated diseases.
Project description:Transcriptome sequencing was applied to 44 colon Graft vs Host Disease (GVHD) biopsies from 22 patients to determine differences in immunology and microbial profiles, along with general differences in somatic gene expressions by determining trends of mapped somatic alignments. Read analysis of somatic alignments were subjected to enrichment analysis of cellular pathways, expression comparisons amongst classes, and immune activity characterization based on outputs of deconvulation alogorithms. Unmapped alignments were mapped to microbiome reference assemblies to determine non-somatic profiles. Classes were determined based on healthy vs diseased patients, steriod refractory paired with onset biopsies, and a survival cohort as well. Distinct differences between classes have been noticed in all measures of interest.
Project description:In microbial electrolysis cells (MECs), microbial communities catalyze conversions between dissolved organic compounds, electrical energy, and energy carriers such as hydrogen and methane. Bacteria and archaea, which catalyze reactions on the anode and cathode of MECs, interact with phages; however, phage communities have previously not been examined in MECs. In this study, we used metagenomic sequencing to study prokaryotes and phages in nine MECs. A total of 852 prokaryotic draft genomes representing 278 species, and 1476 phage contigs representing 873 phage species were assembled. Among high quality prokaryotic genomes (>95% completion), 55% carried a prophage, and the three Desulfobacterota spp. that dominated the anode communities all carried prophages. Geobacter anodireducens, one of the bacteria dominating the anode communities, carried a CRISPR spacer showing evidence of a previous infection by a Peduoviridae phage present in the liquid of some MECs. Methanobacteriaceae spp. and an Acetobacterium sp., which dominated the cathodes, had several associations with Straboviridae spp. The results of this study show that phage communities in MECs are diverse and interact with functional microorganisms on both the anode and cathode.
Project description:Methods to assess the impact of goose fecal contamination are needed as the result of the increasing number of Canada geese (Branta canadensis) near North American inland waters. However, there is little information on goose fecal microbial communities, and such data are important for the development of host-specific source-tracking methods. To address this issue, 16S rRNA gene clone libraries for Canada goose fecal samples from Ontario, Canada, and Ohio were analyzed. Analyses of fecal clones from Ontario (447) and Ohio (302) showed that goose fecal communities are dominated by the classes "Clostridia" (represented by 33.7% of clones) and "Bacilli" (38.1% of clones) and the phylum "Bacteroidetes" (10.1% of clones). Sequences not previously found in other avian fecal communities were used to develop host-specific assays. Fecal DNA extracts from sewage plants (10 samples) and different species of birds (11 samples) and mammals (18 samples) were used to test for host specificity. Of all the assays tested, one assay showed specificity for Canada goose fecal DNA. The PCR assay was positive for Canada goose fecal DNA extracts collected from three locations in North America (Ohio, Oregon, and Ontario, Canada). Additionally, of 48 DNA extracts from Lake Ontario waters presumed to be impacted by waterfowl feces, 19 tested positive by the assay, although 10 were positive only after a nested PCR approach was used. Due to the level of host specificity and the presence of signals in environmental waters, the assay is proposed as a part of the toolbox to detect Canada goose contamination in waterfowl-contaminated waters.
Project description:Steroid-refractory intestinal acute graft-versus-host disease (aGVHD) is a frequently fatal condition with little known about mechanisms driving failed steroid responses in gut mucosa. To uncover novel molecular insights in steroid-refractory aGVHD, we compared gene expression profiles of rectosigmoid biopsies from patients at diagnosis of clinical stage 3-4 lower intestinal aGVHD (N=22), to repeat biopsies when the patients became steroid refractory (N=22), and normal controls (N=10). We also performed single gene analyses of factors associated with tolerance (programmed death ligand-1 [PDL1], indoleamine 2,3 dioxygenase [IDO1], and T cell immunoreceptor with Ig and ITIM domains [TIGIT]) and found that significantly higher expression levels of these aGVHD inhibitory genes (PDL1, IDO1, TIGIT) at aGVHD onset became decreased in the steroid-refractory state. We examined genes triggered by microbial ligands to stimulate gut repair, amphiregulin (AREG) and the aryl hydrocarbon receptor (AhR), and found that both AREG and AhR gene expression levels were increased at aGVHD onset and remained elevated in steroid-refractory aGVHD. We also identified higher expression levels of metallothioneines, metal-binding enzymes induced in stress responses, and M2 macrophage genes in steroid-refractory aGVHD. We observed no differences in T-cell subsets between onset and steroid-refractory aGVHD. Patients with a rapidly fatal course showed greater DNA damage and a distinct microbial signature at aGVHD onset, whereas patients with more prolonged survival exhibited a gene expression profile consistent with activation of Smoothened. Our results extend the paradigm beyond T cell-centric therapies for steroid-refractory GI aGVHD and highlight new mechanisms for therapeutic exploration.