title: Increased TLR2 expression on blood monocytes in irritable bowel syndrome patients.
abstract: OBJECTIVE
  The understanding of the mechanisms for increased immune activation in subgroups of patients with irritable bowel syndrome (IBS) is incomplete. We hypothesized that monocytes are more activated in patients with IBS than in the healthy population. We therefore examined activation phenotype and cytokine secretion of blood monocytes.
  
  
  METHODS
  Blood samples from 74 patients with IBS and 30 controls were obtained. The activation phenotype of CD11cCD14 monocytes and cytokine secretion in serum and in peripheral blood mononuclear cells cultured with or without lipopolysaccharide was determined. Gastrointestinal and psychological symptom severity and quality of life were assessed using validated questionnaires.
  
  
  RESULTS
  Monocytes from patients demonstrated an increased expression of toll-like receptor (TLR) 2, whereas the expression on monocytes of TLR4, HLA-DR, CD40, CD80 and CD86 was comparable in patients and controls. The expression of activation markers on monocytes did not correlate with gastrointestinal or extracolonic symptom severity, but the expressions of TLR2, HLA-DR and CD86 were associated with less severe psychological symptoms and better social and physical well-being. Cytokine secretion in serum and peripheral blood mononuclear cell cultures was comparable in patients and controls. A subgroup of patients (15%) who had TLR2 and HLA-DR expression intensity above the level seen in controls reported less severe psychosocial symptoms.
  
  
  CONCLUSIONS
  Patients with IBS have increased expression of TLR2 on monocytes and the activation level on monocytes correlates with less severe psychological symptoms and better quality of life. Thus, our data implicate less importance of psychosocial factors and increased importance of immunological parameters for symptom generation in a subgroup of patients with IBS.
authors.affiliation: Department of Internal Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. lena.ohman@microbio.gu.se
authors.forename: Lena
authors.initials: L
authors.lastname: Ohman
authors.forename: Ann-Charlotte
authors.initials: AC
authors.lastname: Lindmark
authors.forename: Stefan
authors.initials: S
authors.lastname: Isaksson
authors.forename: Iris
authors.initials: I
authors.lastname: Posserud
authors.forename: Hans
authors.initials: H
authors.lastname: Strid
authors.forename: Henrik
authors.initials: H
authors.lastname: Sjövall
authors.forename: Magnus
authors.initials: M
authors.lastname: Simrén
mesh_terms: D000293:Adolescent; D000328:Adult; D051940:B7-2 Antigen / Q000097:blood; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D002478:Cells, Cultured; D016207:Cytokines / Q000097:blood; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006684:HLA-DR Antigens / Q000097:blood; D006801:Humans; D016130:Immunophenotyping; D043183:Irritable Bowel Syndrome / Q000276:immunology*; D008070:Lipopolysaccharides / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000276:immunology*; D011788:Quality of Life; D051195:Toll-Like Receptor 2 / Q000097:blood*; D055815:Young Adult
chemical_list: D051940:B7-2 Antigen; D015415:Biomarkers; C497964:CD86 protein, human; D016207:Cytokines; D006684:HLA-DR Antigens; D008070:Lipopolysaccharides; D051195:Toll-Like Receptor 2