Interleukin-6 and interleukin-6 receptor are expressed by cultured glomerular epithelial cells

Scand J Immunol. 1994 Aug;40(2):181-6. doi: 10.1111/j.1365-3083.1994.tb03448.x.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Northern
  • Cell Division / immunology
  • Cells, Cultured
  • Epithelial Cells
  • Epithelium / immunology
  • Humans
  • Interleukin-6 / biosynthesis
  • Interleukin-6 / physiology*
  • Kidney Glomerulus / cytology
  • Kidney Glomerulus / immunology*
  • Lipopolysaccharides / pharmacology
  • Monokines / physiology
  • Receptors, Interleukin / biosynthesis*
  • Receptors, Interleukin-6

Substances

  • Interleukin-6
  • Lipopolysaccharides
  • Monokines
  • Receptors, Interleukin
  • Receptors, Interleukin-6