title: Toll-like receptor TLR2 and TLR9 ligation triggers neutrophil activation in granulomatosis with polyangiitis.
abstract: OBJECTIVE
  The aim of the study was to characterize the expression of TLR2, TLR4 and TLR9 in PMNs of patients with granulomatosis with polyangiitis (GPA) and to elucidate the role of these receptors in GPA with respect to neutrophil activation.
  
  
  METHODS
  The expression of TLR2, TLR4 and TLR9 was determined on ex vivo PMNs in whole blood samples of GPA patients (n = 35) and healthy controls (HCs) (n = 24). Isolated PMNs were stimulated in vitro with TLR agonists and assessed for degranulation, membrane proteinase 3 (mPR3) expression, soluble l-selectin shedding and cytokine production (IL-8) in five GPA patients and five HCs. The priming effects of TLR2 and TLR9 ligation were assessed by measurement of serine protease activity after stimulation with PR3-ANCA.
  
  
  RESULTS
  There were no significant differences in the ex vivo expression of TLRs on PMNs in HCs and GPA patients. Stimulation of TLR4 and TLR9 induced MPO release, stimulation with TLR2, TLR4 and TLR9 ligands elicited IL-8 production and stimulation of TLR2 and TLR9 led to an upregulation in mPR3 expression on PMNs with no significant differences between GPA and HC after 1 or 24 h stimulation. Priming of PMNs with TLR2 and TLR9 ligands induced degranulation after subsequent stimulation with PR3-ANCA, which was comparable to priming with TNF-α.
  
  
  CONCLUSIONS
  Expression of TLR2, TLR4 and TLR9 in PMNs and the TLR-induced activation of PMNs was comparable in GPA and HC. mPR3 upregulation by TLR2 and TLR9 stimulation and the priming effect of TLR ligands on PMNs may have a potential implication for triggering disease activity during infection in GPA.
authors: Department of Rheumatology and Immunology, University Hospital Schleswig-Holstein, Campus Luebeck and Klinikum Bad Bramstedt, Oskar-Alexander-Straße 26, 24576 Bad Bramstedt, Germany. hollejulia@hotmail.com
authors: Julia U
authors: JU
authors: Holle
authors: Mirca
authors: M
authors: Windmöller
authors: Christina
authors: C
authors: Lange
authors: Wolfgang L
authors: WL
authors: Gross
authors: Karen
authors: K
authors: Herlyn
authors: Elena
authors: E
authors: Csernok
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000378:metabolism* / Q000503:physiopathology; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D008297:Male; D053513:Matrix Metalloproteinase 16 / Q000378:metabolism; D008875:Middle Aged; D018375:Neutrophil Activation / Q000502:physiology*; D009504:Neutrophils / Q000378:metabolism*; D009195:Peroxidase / Q000378:metabolism; D051195:Toll-Like Receptor 2 / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000378:metabolism; D051217:Toll-Like Receptor 9 / Q000378:metabolism*; D015854:Up-Regulation; D055815:Young Adult
chemical_list: D016209:Interleukin-8; C507102:MMP16 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051217:Toll-Like Receptor 9; D009195:Peroxidase; D053513:Matrix Metalloproteinase 16
keywords: ANCA-associated vasculitis; PMN; Toll-like receptor; granulomatosis with polyangiitis; innate immunity