In inflammatory
gingival diseases,
cytokines have been demonstrated to play critical roles by coordinating the stimulation of immunological and connective tissue cells. The activities of these cells, degrading and remodeling extracellular matrices, constitute the major pathological and repair processes. Thus, elucidating cellular and molecular events occurring in inflamed connective tissues is crucial for the understanding and treatment of
inflammation. In order to test a hypothesis that proinflammatory
cytokines affect metabolism of major extracellular matrix molecules, we studied metabolism of
proteoglycans (PGs) by human gingival fibroblasts (HGF) under the influence of
interleukin-4 (IL-4) as a model of
gingivitis. HGF in cell culture were metabolically radiolabeled using [3H]
glucosamine and [35S]
sulfate in the presence or absence of
IL-4, and the labeled PGs were analyzed by chromatographic techniques. The incorporation of 35S into PGs increased with
IL-4 both in media and cell layer. At 100 ng/ml of
IL-4, the increment of 35S incorporation over control culture was 16-39% (p<0.001) in media and 12-35% (p=0.01) in cell layer. The 35S-labeled macromolecules were PGs containing
heparan sulfate (HS) and
chondroitin sulfate (CS) chains. From the molecular weight and
glycosaminoglycan composition analyses,
versican and
perlecan-type and
biglycan and
decorin-type were very likely to be the major PG constituents both in media and cell layer.
IL-4 stimulated synthesis of
versican and
perlecan-type more potently than
biglycan and
decorin-type. With
IL-4 treatment, the ratio of CSPG/
HSPG decreased in media and increased in cell layer. This ratio suggested that
syndecan family HSPGs were also present in HGF. In conclusion,
IL-4 stimulated accumulation of CS/HSPGs in human gingival fibroblasts.