Glucosamine exposure reduces proteoglycan synthesis in primary human endothelial cells in vitro.
OBJECTIVE
Glucosamine (GlcN) supplements are promoted for medical reasons, for example, for patients with arthritis and other joint-related diseases. Oral intake of GlcN is followed by uptake in the intestine, transport in the circulation and thereafter delivery to chondrocytes. Here, it is postulated to have an effect on synthesis and turnover of extracellular matrix constituents expressed by these cells. Following uptake in the intestine, serum levels are transiently increased, and the endothelium is exposed to increased levels of GlcN. We investigated the possible effects of GlcN on synthesis of proteoglycans (PGs), an important matrix component, in primary human endothelial cells.


METHODS
Primary human endothelial cells were cultured in vitro in medium with 5 mM glucose and 0-10 mM GlcN. PGs were recovered and analysed by western blotting, or by SDS-PAGE, gel chromatography or ion-exchange chromatography of (35)S-PGs after (35)S-sulphate labelling of the cells.


RESULTS
The synthesis and secretion of (35)S-PGs from cultured endothelial cells were reduced in a dose- and time-dependent manner after exposure to GlcN. PGs are substituted with sulphated glycosaminoglycan (GAG) chains, vital for PG function. The reduction in (35)S-PGs was not related to an effect on GAG chain length, number or sulphation, but rather to the total expression of PGs.


CONCLUSIONS
Exposure of endothelial cells to GlcN leads to a general decrease in (35)S-PG synthesis. These results suggest that exposure to high levels of GlcN can lead to decreased matrix synthesis, contrary to what has been claimed by supporters of such supplements.
Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.|Section of Nephrology, Department of Transplant Medicine, Oslo University Hospital, Rikshospitalet, Oslo, Norway; t.m.reine@medisin.uio.no.
Trine M
TM
Reine
Section of Nephrology, Department of Transplant Medicine, Oslo University Hospital, Rikshospitalet, Oslo, Norway.|Metabolic and Renal Research Group, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway.
Trond Geir
TG
Jenssen
Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
Svein Olav
SO
Kolset
arthritis; endothelial cells; glucosamine; glycosaminoglycan; proteoglycan
Ann Rheum Dis. 2016 Jan;75(1):37-44
25589511
Sci STKE. 2005 Nov 29;2005(312):re13
16317114
Arthritis Res Ther. 2012 Jan 30;14(1):201
22293240
Osteoarthritis Cartilage. 2000 Jul;8(4):258-65
10903879
Ann Rheum Dis. 2006 Feb;65(2):222-6
16079170
J Pain Palliat Care Pharmacother. 2008;22(1):39-43
28792807
Glycobiology. 2009 Jun;19(6):564-7
19254962
Arthritis Rheum. 2008 Oct;58(10):3183-91
18821708
Osteoarthritis Cartilage. 2009 Aug;17(8):1014-21
19364543
N Engl J Med. 2006 Feb 23;354(8):795-808
16495392
J Biol Chem. 1998 Aug 7;273(32):20658-68
9685425
Osteoarthritis Cartilage. 2010 Mar;18(3):297-302
19912983
Osteoarthritis Cartilage. 2003 Jun;11(6):424-32
12801482
J Agric Food Chem. 2015 Dec 30;63(51):10903-13
26592089
Am J Physiol Endocrinol Metab. 2008 Jul;295(1):E17-28
18445751
Nat Rev Mol Cell Biol. 2014 Dec;15(12):786-801
25415508
J Biol Chem. 2011 Jan 28;286(4):2636-47
21075844
Biochem J. 1998 Oct 1;335 ( Pt 1):59-66
9742213
Sports Health. 2009 Nov;1(6):461-8
23015907
J Clin Invest. 1973 Nov;52(11):2745-56
4355998
Osteoarthritis Cartilage. 2007 Jul;15(7):773-9
17320421
Osteoarthritis Cartilage. 2014 Feb;22(2):259-63
24333294
Cancer Res. 1973 Mar;33(3):482-92
4347714
J Lipid Res. 2002 Jan;43(1):149-57
11792734
Annu Rev Biochem. 1991;60:443-75
1883201
Trends Endocrinol Metab. 2008 Dec;19(10):380-9
18929495
Arch Physiol Biochem. 2008 Apr;114(2):120-6
18484279
Biochemistry. 1976 Sep 7;15(18):3932-42
9127
J Biol Chem. 2004 Aug 20;279(34):35313-9
15199059
Eur J Nutr. 2006 Oct;45(7):369-75
16810465
PLoS One. 2015 Dec 22;10(12):e0145584
26694746
Life Sci. 2016 May 1;152:21-9
27012765
JAMA. 2000 Mar 15;283(11):1469-75
10732937