Alpha2-macroglobulin reduces paracrine- and autocrine-stimulated matrix synthesis of cultured rat hepatic stellate cells.
BACKGROUND
Transforming growth factor beta1 (TGF-beta1) is considered to represent a major fibrogenic mediator in the liver. The aim of the present study was to investigate whether alpha2-macroglobulin (alpha2M) might reduce paracrine- and autocrine-stimulated matrix synthesis of cultured rat hepatic stellate cells (HSCs) by scavenging TGF-beta.


RESULTS
Using native agarose electrophoresis, we demonstrated that alpha2M binds [125I]-TGF-beta1 within minutes. Preincubation of transiently acidified supernatants of cultured Kupffer cells, secondary cultured (activated) HSC and platelet lysate with, respectively, 500 and 2000 microg mL-1 alpha2M significantly reduced the concentration of active TGF-beta1 in these media. As a consequence of TGF-beta scavenging by alpha2M, paracrine-stimulated proteoglycan synthesis of primary cultured HSCs was reduced significantly. Furthermore, addition of 200 microg mL-1 alpha2M to passaged (activated) HSCs resulted in (a) a reduction in autocrine-stimulated extracellular matrix synthesis (proteoglycan -52%, fibronectin -55%) and (b) increased cell proliferation. A similar reduction in matrix synthesis was observed after the addition of 5 micromol L-1 TGF-beta1 antisense oligonucleotide to activated HSCs.


CONCLUSIONS
We conclude that alpha2M reduces paracrine-and autocrine-stimulated extracellular matrix synthesis of cultured HSCs by scavenging TGF-beta. These mechanisms might restrict liver fibrogenesis.
Schüftan
G G
GG
Department of Anaesthesiology, University of Cologne, Germany.
Bachem
M G
MG
D000818:Animals; D001792:Blood Platelets / Q000502:physiology*; D002455:Cell Division; D002469:Cell Separation; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis*; D005353:Fibronectins / Q000096:biosynthesis; D005786:Gene Expression Regulation; D007728:Kupffer Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D011509:Proteoglycans / Q000096:biosynthesis; D051381:Rats; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000494:pharmacology / Q000502:physiology*
D017077:Culture Media, Conditioned; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D020319:Oligodeoxyribonucleotides, Antisense; D011509:Proteoglycans; D016212:Transforming Growth Factor beta; D000511:alpha-Macroglobulins