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A molecular biologic study of extracellular matrix components during the development of glomerulosclerosis in murine
C Munaut1, E C Bergijk, J J Baelde
1Department of Biology, University of Liège, Belgium.
Background:
We studied the development of glomerulosclerosis in murine chronic graft-versus-host disease, a model for human systemic lupus erythematosus.
Experimental Design:
The disease was induced in (C57BL10 x DBA/2)F1 hybrids by injection of DBA/2 lymphocytes leading to deposition of auto-antibodies in the glomeruli, and a lupus type of nephritis morphologically. We have determined the levels of mRNA coding for laminin (B1 and B2), a 67 kilodalton laminin binding protein, and types I and IV collagen, in control and graft-versus host disease mice at various times after disease induction.
Results:
Laminin and collagen mRNAs were increased in whole kidneys 4 weeks after induction of the disease. At week 10, all animals displayed dramatic stimulation of alpha 1(I), alpha 1(IV), laminin B1, and B2 mRNAs. The 67 kilodalton laminin binding protein mRNA was also doubled from week 4 to 16. In isolated glomeruli, the mRNA level coding for laminin B2 was already significantly increased from week 8. This enhancement of laminin synthesis corresponds to the mesangial expansion and to the development of laminin-containing spike formations of the glomerular basement membrane at week 8.
Conclusions:
The expansion of the mesangial matrix in murine chronic graft-versus-host disease is caused at least in part, by an increased production of extracellular matrix components by glomerular cells. These results demonstrate that the increase of specific extracellular matrix components mRNAs precedes light microscopic changes. Quantitative evaluation of the mRNA levels coding for extracellular matrix proteins may reveal a useful method for the early detection of the development of glomerular sclerosis at the stage preceding the onset of anatomo-clinical changes.