In vitro evidence for differential involvement of CTGF, TGFbeta, and PDGF-BB in mesangial response to injury.
BACKGROUND
Connective tissue growth factor (CTGF) is a profibrotic growth factor, which is upregulated in wound healing and renal fibrosis, including anti-Thy-1.1 nephritis. The kinetics of CTGF mRNA expression in anti-Thy-1.1 nephritis suggested that CTGF regulation might contribute to glomerular response to injury downstream of transforming growth factor-beta (TGFbeta). In anti-Thy-1.1 nephritis the initial damage is followed by mesangial repair and limited sclerosis, which involves mesangial cell (MC) activation (alpha-smooth-muscle actin (alphaSMA) expression), proliferation, migration, and extracellular matrix production. The present in vitro study addresses the possible role of CTGF in these different aspects of mesangial response to injury, and how CTGF activity might relate to effects of TGFbeta and platelet-derived growth factor-BB (PDGF-BB).


RESULTS
Immunostaining and ELISA showed that alphaSMA expression and transformation of MC into myofibroblast-like cells was induced by TGFbeta, but not affected by PDGF-BB, CTGF, or neutralizing anti-CTGF antibodies. [(3)H]thymidine incorporation and Ki67 staining demonstrated that, unlike PDGF-BB, neither CTGF nor TGFbeta induced the proliferation of MC. In contrast, both CTGF and TGFbeta induced MC migration, as evidenced by approximation of wound edges in scrape-wounded, non-proliferating rat MC monolayers. In addition, fibronectin expression was upregulated by both CTGF and TGFbeta, as measured by dot-blot analysis. Anti-CTGF completely blocked the effect of added CTGF. Moreover, anti-CTGF significantly reduced TGFbeta-induced increase in fibronectin.


CONCLUSIONS
It thus appears that CTGF is specifically involved in a subset of the adaptive changes of MC involved in mesangial repair and sclerosis, which makes it an interesting candidate target for future intervention strategies.
Blom
I E
IE
Department of Pathology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
van Dijk
A J
AJ
Wieten
L
L
Duran
K
K
Ito
Y
Y
Kleij
L
L
deNichilo
M
M
Rabelink
T J
TJ
Weening
J J
JJ
Aten
J
J
Goldschmeding
R
R
D000199:Actins / Q000235:genetics; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D000077214:Becaplermin; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D055513:Connective Tissue Growth Factor; D005353:Fibronectins / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D005920:Glomerular Mesangium / Q000166:cytology / Q000293:injuries* / Q000502:physiology*; D006133:Growth Substances / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins; D019394:Ki-67 Antigen / Q000032:analysis; D007700:Kinetics; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000235:genetics*
D000199:Actins; D000906:Antibodies; C526317:CCN2 protein, human; C526316:CCN2 protein, rat; D005353:Fibronectins; D006133:Growth Substances; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D019394:Ki-67 Antigen; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D055513:Connective Tissue Growth Factor; D000077214:Becaplermin; D013936:Thymidine