Hepatocyte growth factor (HGF), also known as
scatter factor, is a broad-spectrum and multifunctional
cytokine required for the development, growth and regeneration of various organs and tissues. The expression of HGF in human gingival fibroblasts is induced by inflammatory
cytokines such as
interleukin 1. Thus, although it is possible that content of HGF in gingival crevicular fluid (GCF) in
periodontitis is increased, this has not so far been reported because the volume of GCF is too small to determine HGF by the available
enzyme-linked
immunosorbent assay (ELISA). A recently developed, highly sensitive ELISA for HGF, with a detection limit of 1 pg/ml sample, has now enabled HGF to be measured in GCF.The mean HGF content in GCF from sites with clinically healthy gingiva, defined by the absence of overt signs of gingival
inflammation and a probing depth (PD) <3 mm, was 1.7 ng/ml, and that of
periodontitis, defined by obvious
alveolar bone loss detected by radiographic examination and a PD> or =3 mm, was 3.23 ng/ml. Although treating the
periodontitis did not significantly decrease the HGF concentration despite significantly improved clinical scores such as PD and Gingival Index, the total amount of HGF in GCF did decrease significantly
after treatment. HGF was expressed by gingival fibroblasts and inflammatory cells as determined by in situ hybridization.
HGF-activator (HGFA), which converts inactive
pro-HGF to active mature HGF, was detected in gingival epithelial cells by immunostaining. The expression of HGFA was also confirmed in gingival tissue by reverse transcription-polymerase chain reaction (RT-PCR). These findings indicate that HGF is synthesized and activated in gingiva that is clinically healthy or associated with
periodontitis.