M. Kaizuka et al., Thrombin stimulates synthesis of type IV collagen and tissue inhibitor of metalloproteinases-1 by cultured human mesangial cells, J AM S NEPH, 10(7), 1999, pp. 1516-1523
Glomerular accumulation of extracellular matrix (ECM) is the common patholo
gic feature following glomerular injury, and the alteration in the synthesi
s and degradation of ECM may be involved in the glomerular accumulation of
ECM. Glomerular fibrin formation occurs in various forms of human and exper
imental glomerulonephritis, and it may play an important role in progressiv
e glomerular injury. Thrombin, a multifunctional serine proteinase that is
generated at the site of vascular injury, has central functions in hemostas
is and it also shows various biologic effects. In this study, it is hypothe
sized that thrombin may alter the production and the degradation of type IV
collagen, which is an important component of ECM in the glomeruli. Human m
esangial cells (HMC) were cultured, and the levels of type IV collagen, tis
sue inhibitor of metalloproteinase-l (TIMP-1), and matrix metalloproteinase
-2 (MMP-2) in the culture supernatants were measured by enzyme immunoassay
using specific antibodies. MMP-2 activity was also evaluated by zymography
using polyacrylamide/ sodium dodecyl sulfate gel-containing gelatin. Thromb
in increased the production of type IV collagen and TIMP-1 in a dose- and t
ime-dependent manner, but it did not increase MMP-2. Thrombin also stimulat
ed the gene expressions of the type TV collagen and TIMP-1 in HMC in a dose
- and time-dependent manner. Thrombin treated with diisopropylfluorophospha
te, a serine proteinase inhibitor, did not show any of these effects. Hirud
in, a natural thrombin inhibitor, and anti-transforming growth factor-beta-
neutralizing antibody inhibited the stimulating effect of thrombin. These f
indings suggest that thrombin may contribute to the excessive accumulation
of ECM and progression of glomerulosclerosis through an increase of type IV
collagen production and a decreased matrix degradation presumably via a tr
ansforming growth factor-beta-dependent mechanism.