| 1. |
- Blacher, E., et al.
(författare)
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Potential roles of gut microbiome and metabolites in modulating ALS in mice
- 2019
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 572:7770
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Tidskriftsartikel (refereegranskat)abstract
- Amyotrophic lateral sclerosis (ALS) is a complex neurodegenerative disorder, in which the clinical manifestations may be influenced by genetic and unknown environmental factors. Here we show that ALS-prone Sod1 transgenic (Sod1-Tg) mice have a pre-symptomatic, vivarium-dependent dysbiosis and altered metabolite configuration, coupled with an exacerbated disease under germ-free conditions or after treatment with broad-spectrum antibiotics. We correlate eleven distinct commensal bacteria at our vivarium with the severity of ALS in mice, and by their individual supplementation into antibiotic-treated Sod1-Tg mice we demonstrate that Akkermansia muciniphila (AM) ameliorates whereas Ruminococcus torques and Parabacteroides distasonis exacerbate the symptoms of ALS. Furthermore, Sod1-Tg mice that are administered AM are found to accumulate AM-associated nicotinamide in the central nervous system, and systemic supplementation of nicotinamide improves motor symptoms and gene expression patterns in the spinal cord of Sod1-Tg mice. In humans, we identify distinct microbiome and metabolite configurations-including reduced levels of nicotinamide systemically and in the cerebrospinal fluid-in a small preliminary study that compares patients with ALS with household controls. We suggest that environmentally driven microbiome-brain interactions may modulate ALS in mice, and we call for similar investigations in the human form of the disease.
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| 2. |
- Bock, K, et al.
(författare)
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Specificity of binding of a strain of uropathogenic Escherichia coli to Gal alpha 1----4Gal-containing glycosphingolipids.
- 1985
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Ingår i: The Journal of biological chemistry. - 0021-9258. ; 260:14, s. 8545-51
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Tidskriftsartikel (refereegranskat)abstract
- A strain of Escherichia coli originally isolated from urine of a patient with acute pyelonephritis was studied in detail for binding to glycosphingolipids. Bacteria labeled metabolically with [14C]glucose were layered over a glycolipid chromatogram and bound bacteria were detected by autoradiography. The detection was down to a few ng of glycolipid (pmol level) under these assay conditions. At a test level of 500 ng all glycolipids (more than a dozen molecular species analyzed) with Gal alpha 1----4Gal as an internal or terminal part bound the bacteria strongly while glycolipids known to lack this sequence were negative. Conformational analysis using hard sphere calculations including the exo-anomeric effect showed a bend in the saccharide chain at this disaccharide with a largely hydrophobic surface of the convex side, probably being part of the binding epitope. Mixtures of glycolipids isolated from a human ureter scraping and from urinary sediments bound bacteria in the 2- to 7-sugar interval. Thus, this infectious strain of E. coli recognizes glycolipids being present in epithelial cells lining the urinary tract.
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| 3. |
- Hickey, C. A., et al.
(författare)
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Colitogenic Bacteroides thetaiotaomicron Antigens Access Host Immune Cells in a Sulfatase-Dependent Manner via Outer Membrane Vesicles
- 2015
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Ingår i: Cell Host & Microbe. - : Elsevier BV. - 1931-3128. ; 17:5, s. 672-680
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Tidskriftsartikel (refereegranskat)abstract
- Microbes interact with the host immune system via several potential mechanisms. One essential step for each mechanismis themethod by which intestinal microbes or their antigens access specific host immune cells. Using genetically susceptible mice (dnKO) that develop spontaneous, fulminant colitis, triggered by Bacteroides thetaiotaomicron (B. theta), we investigated the mechanism of intestinal microbial access under conditions that stimulate colonic inflammation. B. theta antigens localized to host immune cells through outer membrane vesicles (OMVs) that harbor bacterial sulfatase activity. We deleted the anaerobic sulfatase maturating enzyme (anSME) from B. theta, which is required for post-translational activation of all B. theta sulfatase enzymes. This bacterial mutant strain did not stimulate colitis in dnKO mice. Lastly, access of B. theta OMVs to host immune cells was sulfatase dependent. These data demonstrate that bacterial OMVs and associated enzymes promote inflammatoryimmune stimulation in genetically susceptible hosts.
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| 4. |
- Schütte, André, et al.
(författare)
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Microbial-induced meprin β cleavage in MUC2 mucin and a functional CFTR channel are required to release anchored small intestinal mucus
- 2014
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 111:34, s. 12396-12401
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Tidskriftsartikel (refereegranskat)abstract
- The mucus that covers and protects the epithelium of the intestine is built around its major structural component, the gel-forming MUC2 mucin. The gel-forming mucins have traditionally been assumed to be secreted as nonattached. The colon has a two-layered mucus system where the inner mucus is attached to the epithelium, whereas the small intestine normally has a nonattached mucus. However, the mucus of the small intestine of meprin β-deficient mice was now found to be attached. Meprin β is an endogenous zinc-dependent metalloprotease now shown to cleave the N-terminal region of the MUC2 mucin at two specific sites. When recombinant meprin β was added to the attached mucus of meprin β-deficient mice, the mucus was detached from the epithelium. Similar to meprin β-deficient mice, germ-free mice have attached mucus as they did not shed the membrane-anchored meprin β into the luminal mucus. The ileal mucus of cystic fibrosis (CF) mice with a nonfunctional cystic fibrosis transmembrane conductance regulator (CFTR) channel was recently shown to be attached to the epithelium. Addition of recombinant meprin β to CF mucus did not release the mucus, but further addition of bicarbonate rendered the CF mucus normal, suggesting that MUC2 unfolding exposed the meprin β cleavage sites. Mucus is thus secreted attached to the goblet cells and requires an enzyme, meprin β in the small intestine, to be detached and released into the intestinal lumen. This process regulates mucus properties, can be triggered by bacterial contact, and is nonfunctional in CF due to poor mucin unfolding.
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| 5. |
- Sheikh, A., et al.
(författare)
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Enterotoxigenic Escherichia coli Degrades the Host MUC2 Mucin Barrier To Facilitate Critical Pathogen-Enterocyte Interactions in Human Small Intestine
- 2022
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Ingår i: Infection and Immunity. - : American Society for Microbiology. - 0019-9567 .- 1098-5522. ; 90:2
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Tidskriftsartikel (refereegranskat)abstract
- Enterotoxigenic Escherichia coli (ETEC) isolates are genetically diverse pathological variants of E. coli defined by the production of heat-labile (LT) and/or heat-stable (ST) toxins. ETEC strains are estimated to cause hundreds of millions of cases of diarrheal illness annually. However, it is not clear that all strains are equally equipped to cause disease, and asymptomatic colonization with ETEC is common in low- to middle-income regions lacking basic sanitation and clean water where ETEC are ubiquitous. Recent molecular epidemiology studies have revealed a significant association between strains that produce EatA, a secreted autotransporter protein, and the development of symptomatic infection. Here, we demonstrate that LT stimulates production of MUC2 mucin by goblet cells in human small intestine, enhancing the protective barrier between pathogens and enterocytes. In contrast, using explants of human small intestine as well as small intestinal enteroids, we show that EatA counters this host defense by engaging and degrading the MUC2 mucin barrier to promote bacterial access to target enterocytes and ultimately toxin delivery, suggesting that EatA plays a crucial role in the molecular pathogenesis of ETEC. These findings may inform novel approaches to prevention of acute diarrheal illness as well as the sequelae associated with ETEC and other pathogens that rely on EatA and similar proteases for efficient interaction with their human hosts. © 2022 American Society for Microbiology. All rights reserved.
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| 6. |
- Axelsson, Magnus A. B., et al.
(författare)
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Deglycosylation by gaseous hydrogen fluoride of mucus glycoproteins immobilized on nylon membranes and in microtiter wells.
- 1998
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Ingår i: Glycoconjugate journal. - 0282-0080. ; 15:8, s. 749-55
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Tidskriftsartikel (refereegranskat)abstract
- Strongly reacting antibodies specific for defined mucin gene products are often directed against the mucin protein backbone of the heavily glycosylated serine/threonine rich regions. A prerequisite for the use of such antibodies is often the complete removal of the oligosaccharides from the protein. This paper describes an efficient one-step deglycosylation method using gaseous hydrogen fluoride on nylon blotting membranes and microtiter wells.
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| 7. |
- Baker, N, et al.
(författare)
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Glycosphingolipid receptors for Pseudomonas aeruginosa.
- 1990
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Ingår i: Infection and immunity. - 0019-9567. ; 58:7, s. 2361-6
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Tidskriftsartikel (refereegranskat)abstract
- The binding of Pseudomonas aeruginosa to glycosphingolipids and to buccal and bronchial epithelial cells was analyzed. Three independently expressed specificities were found by bacterial binding to glycosphingolipids separated by thin-layer chromatography. All strains bound gangliotria- and gangliotetrasylceramide. All but one of the strains bound sialic acid-containing glycosphingolipids and lactosylceramide. The latter two specificities could be separated in that the lactosylceramide binding was retained and the sialic acid binding was suppressed when bovine serum albumin was used as a blocking agent in the thin-layer chromatography assay. The attachment to buccal epithelial cells, like the binding to sialylated compounds and lactosylceramide, was abolished by Formalin treatment of the bacteria, suggesting the importance of these specificities for cell adherence. In contrast, the binding to gangliotria- and gangliotetraosylceramide was retained by nonattaching Formalin-treated bacteria.
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| 8. |
- Birchenough, George M. H., et al.
(författare)
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Muc2-dependent microbial colonization of the jejunal mucus layer is diet sensitive and confers local resistance to enteric pathogen infection
- 2023
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Ingår i: Cell Reports. - Cambridge : Elsevier BV. - 2211-1247. ; 42:2
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Tidskriftsartikel (refereegranskat)abstract
- Intestinal mucus barriers normally prevent microbial infections but are sensitive to diet-dependent changes in the luminal environment. Here we demonstrate that mice fed a Western-style diet (WSD) suffer regiospe-cific failure of the mucus barrier in the small intestinal jejunum caused by diet-induced mucus aggregation. Mucus barrier disruption due to either WSD exposure or chromosomal Muc2 deletion results in collapse of the commensal jejunal microbiota, which in turn sensitizes mice to atypical jejunal colonization by the enteric pathogen Citrobacter rodentium. We illustrate the jejunal mucus layer as a microbial habitat, and link the re-giospecific mucus dependency of the microbiota to distinctive properties of the jejunal niche. Together, our data demonstrate a symbiotic mucus-microbiota relationship that normally prevents jejunal pathogen colo-nization, but is highly sensitive to disruption by exposure to a WSD.
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| 9. |
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| 10. |
- Björk, S, et al.
(författare)
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Structures of blood group glycosphingolipids of human small intestine. A relation between the expression of fucolipids of epithelial cells and the ABO, Le and Se phenotype of the donor.
- 1987
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Ingår i: The Journal of biological chemistry. - 0021-9258. ; 262:14, s. 6758-65
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Tidskriftsartikel (refereegranskat)abstract
- Small intestinal epithelial cells (enterocytes) were isolated from specimens obtained at operation from four human individuals with different blood group ABO, Lewis, and secretor phenotypes. The non-acid glycolipids were isolated and characterized by thin-layer chromatography, mass spectrometry, and proton NMR spectroscopy and for reactivity with monoclonal antibodies on thin-layer chromatograms. Monohexosylceramides and blood group ABH (type 1 chain) and Lewis glycolipids with 5-7 sugar residues were the major compounds present in all cases, and the expression of the major blood group glycolipids was in agreement with the ABO, Lewis, and secretor phenotype of the individual donors. Small amounts of more complex glycolipids with up to 10 sugar residues were identified by mass spectrometry in all cases. In addition, small amounts of lactotetraosylceramide, a blood group H-active triglycosylceramide with the structure of Fuc alpha 1-2Gal-Hex-Cer (where Fuc is fucose, Hex is hexose, and Cer is ceramide), and dihexosylceramides were identified in some cases. Globotriaosyl- and globotetraosylceramides were absent from the epithelial cells. Small amounts of Leb-active glycolipids in blood group OLe(a+b-), non-secretor and OLe(a-b-), secretor individuals as well as trace amounts of type 2 carbohydrate chain compounds in all individuals were detected by specific monoclonal antibodies.
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