The effect of different molecular weight hyaluronan on macrophage physiology.
OBJECTIVE
Hyaluronan, a linear glycosaminoglycan, is an abundant component of extracellular matrix. In its native form, the high-molar-mass hyaluronan polymers have an array of structural and regulatory, mainly anti-inflammatory and anti-angiogenic, functions. In contradiction, the biological effects of fragmented low molecular weight hyaluronan are suggested to be pro-angiogenic and pro-inflammatory.


METHODS
The effects of highly purified pharmacological grade hyaluronan of defined molecular weights 11, 52, 87, 250 and 970 kilodaltons were tested on mouse macrophage cell lines RAW 264.7 and MHS. The surface expression of CD44 and Toll-like receptor 2, surface receptors for hyaluronan, was determined by flow cytometry. Activation of macrophages was determined based on nitric oxide and tumour necrosis factor alpha production, inducible nitric oxide synthase expression, and the activation of the nuclear factor kappa B transcriptional factor.


RESULTS
Both macrophage cell lines expressed CD44 and Toll-like receptor 2, which were significantly increased by the pre-treatment of macrophages with bacterial lipopolysaccharide. Hyaluronan of any molecular weight did not activate production of nitric oxide or tumour necrosis factor alpha in any mouse macrophage cell lines. Correspondingly, hyaluronan of any tested molecular weight did not stimulate nuclear factor kappa B activation. Similarly, hyaluronan of any molecular weight neither exerted stimulatory nor inhibitory effects on macrophages pre-treated by lipopolysaccharide.


CONCLUSIONS
Interestingly, the data does not support the current view of low molecular weight hyaluronan as a pro-inflammatory mediator for macrophages. Further studies are necessary to clarify the effects of different molecular weight hyaluronan on phagocytes.
Krejcova
Daniela
D
Academy of Sciences of the Czech Republic, Brno, Czech Republic.
Pekarova
Michaela
M
Safrankova
Barbora
B
Kubala
Lukas
L
D000818:Animals; D002460:Cell Line; D005434:Flow Cytometry; D018960:Hyaluronan Receptors / Q000378:metabolism; D006820:Hyaluronic Acid / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000633:toxicity; D008262:Macrophage Activation / Q000187:drug effects / Q000502:physiology; D008264:Macrophages / Q000737:chemistry* / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008970:Molecular Weight; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D051195:Toll-Like Receptor 2 / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
C476399:Cd44 protein, mouse; D018960:Hyaluronan Receptors; D008070:Lipopolysaccharides; D016328:NF-kappa B; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D006820:Hyaluronic Acid; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse