title: Interleukin-6 (IL-6) gene expression and secretion by cytokine-stimulated human retinal pigment epithelial cells.
abstract: Retinal and choroidal inflammatory lesions are important causes of visual loss, but the mechanisms regulating intraocular inflammation remain poorly understood. By virtue of its position at the blood-retina barrier, the retinal pigment epithelium (RPE) cells may be critical to the initiation and propagation of ocular inflammation. Previously we showed that cytokine-stimulated RPE cells produce interleukin-8, a well-defined chemotactic factor for neutrophils and lymphocytes. In this study, we found that human RPE cells stimulated by human recombinant interleukin-1-beta (rIL-1 beta) or tumor necrosis factor-alpha (rTNF-alpha) produce interleukin-6 (IL-6). Using a plasmacytoma proliferation assay, significant levels of IL-6 were found in media of RPE cells stimulated with either rIL-1 beta or rTNF-alpha for 4 hr. Progressive accumulation of IL-6 in media overlying stimulated RPE cells occurred over the subsequent 20 hr. IL-1 beta was a significantly more potent stimulator of RPE IL-6 production than TNF-alpha, RPE IL-6 production in response to each of these cytokines was also dose-dependent over a range of 20 pg to 20 ng ml-1. Specific anti IL-6 antibody, but not control immunoglobulin, neutralized RPE-derived IL-6 activity in the plasmacytoma proliferation assays. RPE IL-6 mRNA levels were detectable 1 hr after cytokine stimulation, plateaued within 8 hr in 24-hr assays, and demonstrated dose-dependent kinetics in 6 hr assays. Lipopolysaccharide failed to induce RPE IL-6 mRNA expression or RPE IL-6 production.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Ophthalmology (Kellogg Eye Center), University of Michigan, Ann Arbor 48109.
authors.forename: V M
authors.initials: VM
authors.lastname: Elner
authors.forename: W
authors.initials: W
authors.lastname: Scales
authors.forename: S G
authors.initials: SG
authors.lastname: Elner
authors.forename: J
authors.initials: J
authors.lastname: Danforth
authors.forename: S L
authors.initials: SL
authors.lastname: Kunkel
authors.forename: R M
authors.initials: RM
authors.lastname: Strieter
mesh_terms: D001483:Base Sequence; D015152:Blotting, Northern; D002478:Cells, Cultured; D015870:Gene Expression; D006801:Humans; D007375:Interleukin-1 / Q000502:physiology; D015850:Interleukin-6 / Q000235:genetics* / Q000378:metabolism*; D008070:Lipopolysaccharides; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
chemical_list: D007375:Interleukin-1; D015850:Interleukin-6; D008070:Lipopolysaccharides; D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D012313:RNA