title: Proteome Analysis of Rheumatoid Arthritis Gut Mucosa.
abstract: Rheumatoid arthritis (RA) is an inflammatory joint disease leading to cartilage damage and ultimately impaired joint function. To gain new insight into the systemic immune manifestations of RA, we characterized the colon mucosa proteome from 11 RA-patients and 10 healthy controls. The biopsies were extracted by colonoscopy and analyzed by label-free quantitative proteomics, enabling the quantitation of 5366 proteins. The abundance of dihydrofolate reductase (DHFR) was statistically significantly increased in RA-patient biopsies compared with controls and correlated with the administered dosage of methotrexate (MTX), the most frequently prescribed immunosuppressive drug for RA. Additionally, our data suggest that treatment with Leflunomide, a common alternative to MTX, increases DHFR. The findings were supported by immunohistochemistry with confocal microscopy, which furthermore demonstrated that DHFR was located in the cytosol of the intestinal epithelial and interstitial cells. Finally, we identified 223 citrullinated peptides from 121 proteins. Three of the peptides were unique to RA. The list of citrullinated proteins was enriched in extracellular and membrane proteins and included known targets of anticitrullinated protein antibodies (ACPAs). Our findings support that the colon mucosa could trigger the production of ACPAs, which could contribute to the onset of RA. The MS data have been deposited to ProteomeXchange with identifiers PXD001608 and PXD003082.
authors.affiliation: Departments of Pathology, Boston Children's Hospital and Harvard Medical School , Boston, Massachusetts 02115, United States.
authors.forename: Tue Bjerg
authors.initials: TB
authors.lastname: Bennike
authors.affiliation: Department of Rheumatology, Odense University Hospital , Odense DK-5000, Denmark.|University Research Clinic for Innovative Patient Pathways, Aarhus University , Aarhus DK- 8000, Denmark.
authors.forename: Torkell
authors.initials: T
authors.lastname: Ellingsen
authors.affiliation: University Research Clinic for Innovative Patient Pathways, Aarhus University , Aarhus DK- 8000, Denmark.|Diagnostic Center, Section of Gastroenterology, Regional Hospital Silkeborg , Silkeborg DK-8600, Denmark.
authors.forename: Henning
authors.initials: H
authors.lastname: Glerup
authors.affiliation: University Research Clinic for Innovative Patient Pathways, Aarhus University , Aarhus DK- 8000, Denmark.|Diagnostic Center, Section of Gastroenterology, Regional Hospital Silkeborg , Silkeborg DK-8600, Denmark.
authors.forename: Ole Kristian
authors.initials: OK
authors.lastname: Bonderup
authors.affiliation: Department of Health Science and Technology, Aalborg University , Aalborg DK-9220, Denmark.
authors.forename: Thomas Gelsing
authors.initials: TG
authors.lastname: Carlsen
authors.affiliation: Department of Health Science and Technology, Aalborg University , Aalborg DK-9220, Denmark.|Department of Rheumatology and Center for Clinical Research, North Denmark Regional Hospital , Hjoerring DK-9800, Denmark.
authors.forename: Michael Kruse
authors.initials: MK
authors.lastname: Meyer
authors.affiliation: Department of Clinical Medicine, Aalborg University , Aalborg DK-9220, Denmark.|Department of Haematology, Aalborg University Hospital , Aalborg DK-9000, Denmark.
authors.forename: Martin
authors.initials: M
authors.lastname: Bøgsted
authors.affiliation: Department of Biomedicine, Aarhus University , Aarhus DK-8000, Denmark.
authors.forename: Gunna
authors.initials: G
authors.lastname: Christiansen
authors.affiliation: Department of Health Science and Technology, Aalborg University , Aalborg DK-9220, Denmark.
authors.forename: Svend
authors.initials: S
authors.lastname: Birkelund
authors.affiliation: Institute of Regional Health Research-Center Soenderjylland, University of Southern Denmark , Odense DK-5230, Denmark.|Molecular Diagnostic and Clinical Research Unit, Hospital of Southern Jutland , Aabenraa DK-6200, Denmark.
authors.forename: Vibeke
authors.initials: V
authors.lastname: Andersen
authors.affiliation: Department of Health Science and Technology, Aalborg University , Aalborg DK-9220, Denmark.
authors.forename: Allan
authors.initials: A
authors.lastname: Stensballe
mesh_terms: D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000009:adverse effects*; D001172:Arthritis, Rheumatoid / Q000235:genetics* / Q000276:immunology / Q000473:pathology; D001323:Autoantibodies / Q000096:biosynthesis*; D016022:Case-Control Studies; D002956:Citrulline / Q000378:metabolism; D003106:Colon / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects / Q000276:immunology* / Q000473:pathology; D007555:Isoxazoles / Q000009:adverse effects; D000077339:Leflunomide; D008297:Male; D008727:Methotrexate / Q000009:adverse effects; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D020543:Proteome / Q000235:genetics* / Q000276:immunology; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics* / Q000276:immunology
chemical_list: D018501:Antirheumatic Agents; D001323:Autoantibodies; D007555:Isoxazoles; D010456:Peptides, Cyclic; D020543:Proteome; C487763:cyclic citrullinated peptide; D002956:Citrulline; D013762:Tetrahydrofolate Dehydrogenase; D000077339:Leflunomide; D008727:Methotrexate
keywords: ACPA; DHFR; anticitrullinated protein antibody; citrullination; colon mucosa; dihydrofolate reductase; leflunomide; methotrexate; proteomics; rheumatoid arthritis