Interleukin-6 and interleukin-6 receptor are expressed by cultured glomerular epithelial cells.
Interleukin-6 (IL-6) has been extensively studied in mesangial cells but little is known about the expression of this cytokine and its receptor in glomerular epithelial cells (GEC). IL-6 was detected in the culture supernatants of human GEC and its production was enhanced in time and dose dependent manner by lipopolysaccharide (LPS), interleukin-1 beta (IL-1 beta) and tumour necrosis alpha (TNF-alpha). Quiescent, serum-starved GEC did not express clearly IL-6 mRNA. Stimulation of cells with LPS, TNF-alpha or IL-1 beta resulted in an increase of detectable IL-6 mRNA. Interestingly, it was found that IL-6 induced its own mRNA attesting that this cytokine was secreted in autocrine fashion by GEC. GEC expressed IL-6 receptor (IL-6R) as demonstrated directly by the existence of IL-6R mRNA detected by northern blotting. Stimulation of GEC by pro-inflammatory mediators such as LPS increased the expression of IL-6R mRNA. The soluble form of IL-6 receptor (sIL-6R) was not detectable in the culture supernatants harvested from untreated or cytokine-treated cells. We investigated further, whether IL-6 may influence growth of cultured GEC. Incubation of GEC with recombinant (r) IL-6 resulted in a dose dependent increase in 3H thymidine incorporation indicating that IL-6 acts as an autocrine growth factor for GEC. We conclude that GEC are a potent source of IL-6, the local excessive expression of IL-6 and its receptor may play a substantive role in the regulation of processes which appear critical to the initiation of progressive glomerular disease such as cell proliferation.
Moutabarrik
A
A
Department of Nephrology, Faculte de Medecine de Casablanca, Morocco.
Nakanishi
I
I
Ishibashi
M
M
D015152:Blotting, Northern; D002455:Cell Division / Q000276:immunology; D002478:Cells, Cultured; D004847:Epithelial Cells; D004848:Epithelium / Q000276:immunology; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis / Q000502:physiology*; D007678:Kidney Glomerulus / Q000166:cytology / Q000276:immunology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D015846:Monokines / Q000502:physiology; D018123:Receptors, Interleukin / Q000096:biosynthesis*; D019947:Receptors, Interleukin-6
D015850:Interleukin-6; D008070:Lipopolysaccharides; D015846:Monokines; D018123:Receptors, Interleukin; D019947:Receptors, Interleukin-6