title: Dysbiosis and zonulin upregulation alter gut epithelial and vascular barriers in patients with ankylosing spondylitis.
abstract: BACKGROUND
  Dysbiosis has been recently demonstrated in patients with ankylosing spondylitis (AS) but its implications in the modulation of intestinal immune responses have never been studied. The aim of this study was to investigate the role of ileal bacteria in modulating local and systemic immune responses in AS.
  
  
  METHODS
  Ileal biopsies were obtained from 50 HLA-B27+patients with AS and 20 normal subjects. Silver stain was used to visualise bacteria. Ileal expression of tight and adherens junction proteins was investigated by TaqMan real-time (RT)-PCR and immunohistochemistry. Serum levels of lipopolysaccharide (LPS), LPS-binding protein (LPS-BP), intestinal fatty acid-BP (iFABP) and zonulin were assayed by ELISA. Monocyte immunological functions were studied in in vitro experiments. In addition the effects of antibiotics on tight junctions in human leukocyte antigen (HLA)-B27 transgenic (TG) rats were assessed.
  
  
  RESULTS
  Adherent and invasive bacteria were observed in the gut of patients with AS with the bacterial scores significantly correlated with gut inflammation. Impairment of the gut vascular barrier (GVB) was also present in AS, accompanied by significant upregulation of zonulin, and associated with high serum levels of LPS, LPS-BP, iFABP and zonulin. In in vitro studies zonulin altered endothelial tight junctions while its epithelial release was modulated by isolated AS ileal bacteria. AS circulating monocytes displayed an anergic phenotype partially restored by ex vivo stimulation with LPS+sCD14 and their stimulation with recombinant zonulin induced a clear M2 phenotype. Antibiotics restored tight junction function in HLA-B27 TG rats.
  
  
  CONCLUSIONS
  Bacterial ileitis, increased zonulin expression and damaged intestinal mucosal barrier and GVB, characterises the gut of patients with AS and are associated with increased blood levels of zonulin, and bacterial products. Bacterial products and zonulin influence monocyte behaviour.
authors.affiliation: Dipartimento Biomedico di Medicina Interna e Specialistica, Sezione di Reumatologia, University of Palermo, Palermo, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Ciccia
authors.affiliation: Dipartimento Biomedico di Medicina Interna e Specialistica, Sezione di Reumatologia, University of Palermo, Palermo, Italy.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Guggino
authors.affiliation: UOC di Anatomia Patologica, Ospedali riuniti villa Sofia-Cervello, Palermo, Italy.
authors.forename: Aroldo
authors.initials: A
authors.lastname: Rizzo
authors.affiliation: Dipartimento di Biopatologia e Biotecnologie Mediche, Università di Palermo, Palermo, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Alessandro
authors.affiliation: Istituto di Clinica Medica Generale, Ematologia ed Immunologia Clinica, Università Politecnica delle Marche, Ancona, Italy.
authors.forename: Michele Maria
authors.identifier: http://orcid.org/0000-0001-9132-7401
authors.initials: MM
authors.lastname: Luchetti
authors.affiliation: Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Milling
authors.affiliation: Dipartimento di Biopatologia e Biotecnologie Mediche, Università di Palermo, Palermo, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Saieva
authors.affiliation: Unit for Molecular Immunology and Inflammation, VIB Inflammation Research Center, Ghent University, Belgium.|Department of Rheumatology, Ghent University, Ghent University Hospital, Ghent, Belgium.
authors.forename: Heleen
authors.initials: H
authors.lastname: Cypers
authors.affiliation: UOC di Anatomia Patologica, Ospedali riuniti villa Sofia-Cervello, Palermo, Italy.
authors.forename: Tommaso
authors.initials: T
authors.lastname: Stampone
authors.affiliation: Division of Rheumatology, Department of Biotechnological and Applied Clinical Science, School of Medicine, University of L'Aquila, L'Aquila, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Di Benedetto
authors.affiliation: Dipartimento di Biopatologia e Biotecnologie Mediche, Università di Palermo, Palermo, Italy.
authors.forename: Armando
authors.initials: A
authors.lastname: Gabrielli
authors.affiliation: Division of Pediatric Gastroenterology and Nutrition, MassGeneral Hospital for Children, Center for Celiac Research and Treatment, Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Alessio
authors.initials: A
authors.lastname: Fasano
authors.affiliation: Unit for Molecular Immunology and Inflammation, VIB Inflammation Research Center, Ghent University, Belgium.|Department of Rheumatology, Ghent University, Ghent University Hospital, Ghent, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Elewaut
authors.affiliation: Dipartimento Biomedico di Medicina Interna e Specialistica, Sezione di Reumatologia, University of Palermo, Palermo, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Triolo
mesh_terms: D000208:Acute Disease; D000209:Acute-Phase Proteins; D022005:Adherens Junctions / Q000235:genetics; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015703:Antigens, CD / Q000235:genetics; D001419:Bacteria / Q000302:isolation & purification; D018938:Caco-2 Cells; D015820:Cadherins / Q000235:genetics; D002352:Carrier Proteins / Q000097:blood / Q000235:genetics; D016022:Case-Control Studies; D002772:Cholera Toxin / Q000097:blood* / Q000235:genetics; D002908:Chronic Disease; D064806:Dysbiosis / Q000276:immunology* / Q000382:microbiology; D004727:Endothelium / Q000378:metabolism*; D050556:Fatty Acid-Binding Proteins / Q000097:blood; D015870:Gene Expression; D015796:HLA-B27 Antigen / Q000235:genetics; D006242:Haptoglobins; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D007079:Ileitis / Q000097:blood / Q000276:immunology*; D007082:Ileum / Q000276:immunology / Q000382:microbiology; D016209:Interleukin-8; D007413:Intestinal Mucosa / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology; D062745:Junctional Adhesion Molecule A / Q000235:genetics; D008070:Lipopolysaccharides / Q000097:blood; D008562:Membrane Glycoproteins / Q000097:blood; D008565:Membrane Proteins / Q000235:genetics; D009000:Monocytes / Q000276:immunology; D010539:Permeability; D011498:Protein Precursors; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D055647:Rats, Transgenic; D013167:Spondylitis, Ankylosing / Q000276:immunology*; D019108:Tight Junctions / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation; D000099231:Lipopolysaccharide-Binding Protein; D000099152:Cadherin 5
chemical_list: D000209:Acute-Phase Proteins; D000900:Anti-Bacterial Agents; D015703:Antigens, CD; D015820:Cadherins; D002352:Carrier Proteins; D002772:Cholera Toxin; D050556:Fatty Acid-Binding Proteins; D015796:HLA-B27 Antigen; D006242:Haptoglobins; D016209:Interleukin-8; D062745:Junctional Adhesion Molecule A; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D011498:Protein Precursors; D012333:RNA, Messenger; D000099231:Lipopolysaccharide-Binding Protein; D000099152:Cadherin 5; C486771:PLVAP protein, human; C408043:zonulin
keywords: Ankylosing Spondylitis; Infections; Inflammation