Expression profile of human gingival fibroblasts induced by interleukin-1beta reveals central role of nuclear factor-kappa B in stabilizing human gingival fibroblasts during inflammation.
BACKGROUND
Interleukin (IL)-1beta is a key cytokine in the pathogenesis of periodontitis, and it induces inflammatory mediators in periodontal diseases. We developed immortalized human gingival fibroblasts (HGFs), investigated the effects of IL-1beta on the gene expression using expression arrays containing approximately 40,000 genes, and tested the role of nuclear factor-kappa B (NF-kappaB) in maintaining an activated HGF population.


METHODS
Total RNA was isolated from IL-1beta-induced and mock-induced control cells. Gene expression analyses were performed using expression arrays and confirmed by quantitative real-time polymerase chain reaction. Western blot analysis to show inhibitor of kappa B-alpha (IkappaBalpha) phosphorylation and immunostaining of cells for NF-kappaB nuclear translocation were performed. Apoptosis was confirmed by assay of poly ADP-ribose polymerase (PARP) cleavage.


RESULTS
A total of 382 probe sets corresponding to 254 genes were differentially expressed in IL-1beta-induced cells (P <0.001). A total of 215 genes were upregulated, and 39 genes were downregulated. Most notable NF-kappaB pathway members (NFkappaB1, NFkappaB2, IkappaBalpha, IkappaBepsilon, IkappaBzeta, REL, RELB, and TA-NFKBH) were upregulated. IkappaBalpha was phosphorylated, and NF-kappaB accumulated in the nucleus. An IL-1beta-induced set of 27 genes was downregulated by an NF-kappaB inhibitor, leading to a decreased number of viable cells and suggesting an antiapoptotic role for NF-kappaB.


CONCLUSIONS
IL-1beta leads to a large number of significant expression changes consistent with a pathologic role in periodontitis, including enhancement of inflammatory cytokines, chemokines, transcription factors, matrix metalloproteinases, adhesion molecules, and especially NF-kappaB-dependent antiapoptotic genes. NF-kappaB activation blocks apoptosis, thereby stabilizing the HGF population in inflammation.
Vardar-Sengul
Saynur
S
Department of Pathology and Laboratory Medicine, University of California, Irvine, Irvine, CA, USA.
Arora
Shilpi
S
Baylas
Haluk
H
Mercola
Dan
D
D021581:Active Transport, Cell Nucleus; D017209:Apoptosis / Q000235:genetics; D002461:Cell Line, Transformed; D015536:Down-Regulation; D005347:Fibroblasts / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D005881:Gingiva / Q000166:cytology / Q000378:metabolism; D005891:Gingivitis / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D053583:Interleukin-1beta / Q000494:pharmacology / Q000502:physiology*; D020935:MAP Kinase Signaling System / Q000235:genetics; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D015854:Up-Regulation
D020672:I-kappa B Proteins; D053583:Interleukin-1beta; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D000072000:NF-KappaB Inhibitor alpha