Interleukin 6 production by human proximal tubular epithelial cells in vitro: analysis of the effects of interleukin-1 alpha (IL-1 alpha) and other cytokines.
Proximal tubular epithelial cells (PTEC) from human renal tissue obtained from biopsy or nephrectomy were grown in monoculture and evaluated in vitro at passage 2-4 for interleukin 6 (IL-6) production in response to medium alone or to interleukin 1 alpha (IL-1 alpha), tumour necrosis factor alpha (TNF alpha), interleukin 2 (IL-2), interferon gamma (INF gamma) or lipopolysaccharide (LPS). IL-6 bioactivity was quantitated using the IL-6-dependent murine hybridoma cell line (B9) and expressed as IL-6 units/ml/10(5) PTEC. PTEC cell lines exposed to medium alone produced intermediate amounts of IL-6 with substantial variability between cell lines. Introduction of IL-1 alpha resulted in a dose- and time-dependent increase in IL-6 production by PTEC that was maximal at 1 ng/ml IL-1 alpha at 24 h. All PTEC cell lines showed an increased IL-6 production on exposure to IL-1 alpha varying from 1.3- to 24-fold increase over baseline production. This response was completely blocked by anti-rIL-1 alpha. No significant IL-6 production by PTEC could be induced by TNF alpha, IL-2, IFN gamma, or LPS over a broad dosage range. Cycloheximide inhibited IL-6 production without irreversible cell toxicity, indicating de-novo synthesis. IL-6 produced by PTEC had a molecular weight of 26-29 kDa as demonstrated by Western blot analysis. Using PCR analysis we could demonstrate upregulation by IL-1 alpha of IL-6 mRNA in a dose-response fashion, indicating that IL-1 alpha regulates IL-6 production at a pretranslational value of protein synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)
Boswell
R N
RN
Department of Nephrology, University Hospital, Leiden, The Netherlands.
Yard
B A
BA
Schrama
E
E
van Es
L A
LA
Daha
M R
MR
van der Woude
F J
FJ
D000199:Actins / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics; D001483:Base Sequence; D015153:Blotting, Western; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D018076:DNA, Complementary / Q000096:biosynthesis; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology*; D007376:Interleukin-2 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000199:Actins; D018076:DNA, Complementary; D007375:Interleukin-1; D007376:Interleukin-2; D015850:Interleukin-6; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D003513:Cycloheximide