TGF-beta upregulates interleukin 6 production by rat glomerular epithelial cells in vitro.
BACKGROUND
Glomerular epithelial cells (GECs) play an important role in maintaining normal glomerular permselectivity in vivo. Recent in-vitro studies have suggested that GECs are able to secrete substances which may modulate glomerular injury. Interleukin 6 (IL-6) has been shown to be a potent mediator of glomerular injury. It is also known that IL-6 could be produced by various cells.


METHODS
IL-6 production by rat GECs in culture was examined in this study. IL-6 bioactivity in conditioned medium collected from cultured GECs (GEC-CM) was measured using IL-6 dependent murine hybridoma cell line, namely B9 cells. IL-6 gene expression by GECs was analysed by reverse transcriptase polymerase chain reaction (RT-PCR). Effects of recombinant IL-6 on the proliferation of GECs and type IV collagen secretion by GECs were evaluated to examine the possible role of GECs derived IL-6.


RESULTS
GEC-CM stimulated B9 cells growth in a dose dependent fashion. The mitogenic activity was inhibitable by anti-murine IL-6 antibody. De-novo synthesis of IL-6 was suggested by the demonstration of IL-6 mRNA by GECs using the RT-PCR. Secretion of IL-6 by GECs was increased by transforming growth factor beta but not by IL-1 beta. Recombinant murine IL-6 stimulated GECs growth and their type IV collagen secretion.


CONCLUSIONS
These results indicate that rat GECs could produce IL-6 which may modulate glomerular inflammation and that IL-6 may function as an autocrine factor for GECs.
Osawa
H
H
Second Department of Internal Medicine, Hirosaki University School of Medicine.
Yamabe
H
H
Inuma
H
H
Miyata
M
M
Sasaki
T
T
Kaizuka
M
M
Tamura
N
N
Tsunoda
S
S
Fujita
Y
Y
Kanazawa
T
T
D000818:Animals; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D007678:Kidney Glomerulus / Q000187:drug effects* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects
D015850:Interleukin-6; D012333:RNA, Messenger; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D003094:Collagen