ABSTRACT
Proper activation of Toll-like receptor (TLR)-mediated signaling and production of proinflammatory cytokines are critical for the initiation of innate immunity, while the specific mechanism maintaining inflammatory homeostasis remains mostly unknown. Here, we show that Ets2 is upregulated following LPS and VSV stimulation. Ets2 knockdown or knockout leads to increased IL-6, TNF-α, and IFN-ß production in macrophages. Consistently, Ets2-deficient mice show exacerbated inflammatory cytokine production and are more susceptible to CLP-induced sepsis. Mechanistically, Ets2 inhibits the LPS- and VSV-induced activation of ERK1/2, JNK, p38, and p65. Ets2 also binds to the promoter of IL-6 to inhibit transcription. Collectively, the results of the present study show the negative regulatory role of Ets2 in LPS- and VSV-induced inflammation through the suppression of MAPK/NF-κB signaling, direct binding to the IL-6 promoter and inhibition of transcription.
Subject(s)
Cytokines/biosynthesis , Immunity, Innate/immunology , Inflammation/immunology , Macrophages/immunology , Proto-Oncogene Protein c-ets-2/immunology , Signal Transduction/immunology , Animals , Extracellular Signal-Regulated MAP Kinases/immunology , Extracellular Signal-Regulated MAP Kinases/metabolism , Inflammation/metabolism , Interleukin-6/immunology , Interleukin-6/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , NF-kappa B/immunology , NF-kappa B/metabolism , Promoter Regions, GeneticABSTRACT
Heme oxygenase (HO)-1 is a cytoprotective molecule that is induced during the response to injury. An increase in HO-1 is an acute indicator of inflammation, and early induction of HO-1 has been suggested to correlate with severity of injury. While a great deal is known about the induction of HO-1 by inflammatory mediators and bacterial lipopolysaccharide (LPS), much less is known about the effects of anti-inflammatory mediators on HO-1 expression. Transforming growth factor (TGF)-ß is known to play a critical role in suppressing the immune response, and the TGF-ß1 isoform is expressed in inflammatory cells. Thus, we wanted to investigate whether TGF-ß1 could inhibit the expression of HO-1 during exposure to an inflammatory stimulus in macrophages. Here we demonstrate that TGF-ß1 is able to downregulate LPS-induced HO-1 in mouse macrophages, and this reduction in HO-1 occurred through signaling of TGF-ß1 via its type I receptor, and activation of Smad2. This TGF-ß1 response is dependent on an intact Ets-binding site (EBS) located 93 base pairs upstream from the mouse HO-1 transcription start site. This EBS is known to be important for Ets-2 transactivation of HO-1 by LPS stimulation, and we show that TGF-ß1 is able to suppress LPS-induced Ets-2 mRNA and protein levels in macrophages. Moreover, silencing of Smad2 is able to prevent the suppression of both HO-1 and Ets-2 by TGF-ß1 during exposure to LPS. These data suggest that the return of HO-1 to basal levels during the resolution of an inflammatory response may involve its downregulation by anti-inflammatory mediators.
Subject(s)
Heme Oxygenase-1/metabolism , Macrophages/metabolism , Proto-Oncogene Protein c-ets-2/metabolism , Smad2 Protein/metabolism , Transforming Growth Factor beta1/metabolism , Animals , Blotting, Northern , Blotting, Western , Down-Regulation , Endotoxins/immunology , Endotoxins/toxicity , Enzyme Activation/physiology , Gene Silencing , Heme Oxygenase-1/immunology , Inflammation/immunology , Inflammation/metabolism , Macrophages/immunology , Mice , Proto-Oncogene Protein c-ets-2/immunology , Signal Transduction/immunology , Smad2 Protein/immunology , Transcriptional Activation , Transfection , Transforming Growth Factor beta1/immunologyABSTRACT
Adlay ( Coix lachryma-jobi L. var. ma-yuen Stapf) is a grass crop and was reported to possess anti-inflammatory activity and an antiproliferative effect in cancer cell lines. The purpose of this study was to evaluate the effects of the ethyl acetate fraction of an adlay bran ethanolic extract (ABE-Ea) on colon carcinogenesis in an animal model and investigate its mechanism. Male F344 rats received 1,2-dimethylhydrazine (DMH) and consumed different doses of ABE-Ea. The medium-dose group (17.28 mg of ABE-Ea/day) exhibited the best suppressive effect on colon carcinogenesis and prevented preneoplastic mucin-depleted foci (MDF) formation. Moreover, RAS and Ets2 oncogenes were significantly down-regulated in this group compared to the negative control group, whereas Wee1, a gene involved in the cell cycle, was up-regulated. Cyclooxygenase-2 (COX-2) protein expression was significantly suppressed in all colons receiving the ABE-Ea, indicating that ABE-Ea delayed carcinogenesis by suppressing chronic inflammation. ABE-Ea included considerable a proportion of phenolic compounds, and ferulic acid was the major phenolic acid (5206 microg/g ABE-Ea) on the basis of HPLC analysis. Results from this study suggest that ABE-Ea suppressed DMH-indued preneoplastic lesions of the colon in F344 rats and that ferulic acid may be one of the active compounds.
