Hepatocyte growth factor (HGF)‎, HGF activator (HGFA)‎ and C-MET expression in rheumatoid synovial tissues in relation to disease activit

Abstract EN

Objectives : We examined the localization and mRNA expression of HGF, HGFA and c-Met in synovial tissues (ST) in rheumatoid arthritis (RA) in relation to disease activity to characterize its biologic function in that disease.

Methodology : Immunohistochemical staining and RT-PCR for HGF, HGFA and c-Met were performed on ST specimens from 34 RA-patients and 20 osteoarthritis (OA) controls.

Synovial fluid (SF) samples were taken from all RA and OA for measuring HGF with ELISA technique.

Results : Immunohistochemical staining of RAST revealed that HGFA and c-Met were strongly expressed in fibroblasts, macrophages, endothelial cells and less so on synovial lining cells.

But HGF was expressed faintly in macrophages and fibroblasts.

While, in OAST, HGFA and c-Met were detected in the same cells as RAST but in a different distribution.

HGF was localized in vascular endothelial cells.

RT-PCR showed HGF, HGFA and c-Met mRNA in all RAST and all OAST.

HGF levels in SF samples were higher in RA patients (range 5.6-39.2 ng/ml and mean 26.3±1.2 ng/ml) than OA controls (range 4.2-37.5 ng / ml and mean 11.2±2.4 ng / ml).

The differences were statistically significant (p < 0.001).

A non-significant correlation was found between HGF-SF levels and disease activity score (DAS) (p > 0.5).

Conclusions : HGFA, HGF and c-Met mRNA are expressed in ST in RA and OA.

Lack of correlation between HGF-SF levels and DAS indicated that HGF played a regulatory role in the immunopathogenesis of RA.