title: The role of hyaluronan degradation products as innate alloimmune agonists.
abstract: Dendritic cells (DCs) play a key role in initiating alloimmunity yet the substances that activate them during the host response to transplantation remain elusive. In this study we examined the potential roles of endogenous innate immune agonists in activating dendritic cell-dependent alloimmunity. Using a murine in vitro culture system, we show that 135 KDa fragments of the extracellular matrix glycosaminoglycan hyaluronan induce dendritic cell maturation and initiate alloimmunity. Priming of alloimmunity by hyaluronan-activated DCs was dependent on signaling via TIR-associated protein, a Toll-like receptor (TLR) adaptor downstream of TLRs 2 and 4. However, this effect was independent of alternate TLR adaptors, MyD88 or Trif. Using an in vivo murine transplant model, we show that hyaluronan accumulated during skin transplant rejection. Examination of human lung transplant recipients demonstrated that increased levels of intragraft hyaluronan were associated with bronchiolitis obliterans syndrome. In conclusion, our study suggests that fragments of hyaluronan can act as innate immune agonists that activate alloimmunity.
authors.affiliation: Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, New Haven CT, Connecticut, USA.
authors.forename: B M
authors.initials: BM
authors.lastname: Tesar
authors.forename: D
authors.initials: D
authors.lastname: Jiang
authors.forename: J
authors.initials: J
authors.lastname: Liang
authors.forename: S M
authors.initials: SM
authors.lastname: Palmer
authors.forename: P W
authors.initials: PW
authors.lastname: Noble
authors.forename: D R
authors.initials: DR
authors.lastname: Goldstein
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology*; D006820:Hyaluronic Acid / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D007249:Inflammation / Q000503:physiopathology; D007519:Isoantigens / Q000276:immunology*; D016040:Lung Transplantation / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D009844:Oligosaccharides / Q000276:immunology* / Q000494:pharmacology; D016038:Skin Transplantation / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000276:immunology; D051200:Toll-Like Receptor 8 / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D007519:Isoantigens; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D009844:Oligosaccharides; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D051200:Toll-Like Receptor 8; D014409:Tumor Necrosis Factor-alpha; D006820:Hyaluronic Acid