title: Molecular size hyaluronan differently modulates toll-like receptor-4 in LPS-induced inflammation in mouse chondrocytes.
abstract: Hyaluronan (HA) action depends upon its molecular size. Low molecular weight HA elicits pro-inflammatory responses by modulating the toll-like receptor-4 (TLR-4) or by activating the nuclear factor kappa B (NF-kB). In contrast, high molecular weight HA manifests an anti-inflammatory effect via CD receptors and by inhibiting NF-kB activation. Lipopolysaccharide (LPS) -mediated activation of TLR-4 complex induces the myeloid differentiation primary-response protein (MyD88) and the tumor necrosis factor receptor-associated factor-6 (TRAF-6), and ends with the liberation of NF-kB/Rel family members. The aim of this study was to investigate the influence of HA at different MWs (low, medium, high) on TLR-4 modulation in LPS-induced inflammatory response in mouse chondrocyte cultures. Messenger RNA and related protein levels were measured for TLR-4, MyD88, and TRAF-6 in both untreated and LPS-treated chondrocytes, with and without the addition of HA (two doses for each MW). NF-kB activation, TNF-alpha and IL-1beta levels, matrix metalloprotease-13 (MMP-13), and inducible nitric oxide synthase (iNOS) gene expression were also evaluated. LPS increased all the parameters studied as well as NF-kB activation. Low MW HA upregulated TLR-4 expression, increased MyD88 and TRAF-6 and the inflammation mediators in untreated chondrocytes, and it enhanced the LPS effect in LPS-treated cells. Medium and high MW HA exerted no activity in untreated cells and only the latter reduced the LPS effects. Specific TLR-4 blocking antibody was utilised to confirm TLR-4 as the target of HA action. These findings suggest that the regulatory effect exerted by HA (at any MW) on NF-kB activation may depend upon the interaction between HA and TLR-4 and HA may thereby modulate pro-inflammatory activity via its different state of aggregation.
authors.affiliation: Department of Biochemical, Physiological and Nutritional Sciences, University of Messina, Italy. gcampo@unime.it
authors.forename: Giuseppe M
authors.initials: GM
authors.lastname: Campo
authors.forename: Angela
authors.initials: A
authors.lastname: Avenoso
authors.forename: Salvatore
authors.initials: S
authors.lastname: Campo
authors.forename: Angela
authors.initials: A
authors.lastname: D'Ascola
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Nastasi
authors.forename: Alberto
authors.initials: A
authors.lastname: Calatroni
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism* / Q000473:pathology; D006820:Hyaluronic Acid / Q000737:chemistry* / Q000494:pharmacology*; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism*; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology* / Q000494:pharmacology; D053509:Matrix Metalloproteinase 13 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008970:Molecular Weight; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D048029:TNF Receptor-Associated Factor 6 / Q000235:genetics / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
chemical_list: D000906:Antibodies; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D012333:RNA, Messenger; D048029:TNF Receptor-Associated Factor 6; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D006820:Hyaluronic Acid; D052247:Nitric Oxide Synthase Type II; D053509:Matrix Metalloproteinase 13