Differential regulation of cyclooxygenase-2 and inducible nitric oxide synthase by 4-hydroxynonenal in human osteoarthritic chondrocytes through ATF-2/CREB-1 transactivation and concomitant inhibition of NF-κB signaling cascade (original) (raw)
Related papers
Arthritis Research & Therapy, 2006
4-Hydroxynonenal (HNE), a lipid peroxidation end product, is produced abundantly in osteoarthritic (OA) articular tissues, but its role in bone metabolism is ill-defined. In this study, we tested the hypothesis that alterations in OA osteoblast metabolism are attributed, in part, to increased levels of HNE. Our data showed that HNE/protein adduct levels were higher in OA osteoblasts compared to normal and when OA osteoblasts were treated with H 2 O 2 . Investigating osteoblast markers, we found that HNE increased osteocalcin and type I collagen synthesis but inhibited alkaline phosphatase activity. We next examined the effects of HNE on the signaling pathways controlling cyclooxygenase-2 (COX-2) and interleukin-6 (IL-6) expression in view of their putative role in OA pathophysiology. HNE dose-dependently decreased basal and tumour necrosis factor-α (TNF-α)-induced IL-6 expression while inducing COX-2 expression and prostaglandin E 2 (PGE 2 ) release. In a similar pattern, HNE induces changes in osteoblast markers as well as PGE 2 and IL-6 release in normal osteoblasts. Upon examination of signaling pathways involved in PGE 2 and IL-6 production, we found that HNE-induced PGE 2 release was abrogated by SB202190, a p38 mitogen-activated protein kinase (MAPK) inhibitor. Overexpression of p38 MAPK enhanced HNE-induced PGE 2 release. In this connection, HNE markedly increased the phosphorylation of p38 MAPK, JNK2, and transcription factors (CREB-1, ATF-2) with a concomitant increase in the DNAbinding activity of CRE/ATF. Transfection experiments with a human COX-2 promoter construct revealed that the CRE element (-58/-53 bp) was essential for HNE-induced COX-2 promoter activity. However, HNE inhibited the phosphorylation of IκBα and subsequently the DNA-binding activity of nuclear factor-κB. Overexpression of IKKα increased TNF-α-induced IL-6 production. This induction was inhibited when TNF-α was combined with HNE. These findings suggest that HNE may exert multiple effects on human OA osteoblasts by selective activation of signal transduction pathways and alteration of osteoblastic phenotype expression and pro-inflammatory mediator production.
Regulation of NF-κB-induced inflammatory signaling by lipid peroxidation-derived aldehydes
Oxidative medicine and cellular longevity, 2013
Oxidative stress plays a critical role in the pathophysiology of a wide range of diseases including cancer. This view has broadened significantly with the recent discoveries that reactive oxygen species initiated lipid peroxidation leads to the formation of potentially toxic lipid aldehyde species such as 4-hydroxy-trans-2-nonenal (HNE), acrolein, and malondialdehyde which activate various signaling intermediates that regulate cellular activity and dysfunction via a process called redox signaling. The lipid aldehyde species formed during synchronized enzymatic pathways result in the posttranslational modification of proteins and DNA leading to cytotoxicity and genotoxicty. Among the lipid aldehyde species, HNE has been widely accepted as a most toxic and abundant lipid aldehyde generated during lipid peroxidation. HNE and its glutathione conjugates have been shown to regulate redox-sensitive transcription factors such as NF-κB and AP-1 via signaling through various protein kinase ca...
Journal of Biological Chemistry, 1996
Glomerular mesangial cells produce reactive oxygen intermediates when stimulated by interleukin-1 (IL-1) or tumor necrosis factor. Recent observations suggest that reactive oxygen intermediates may play a role in IL-1 and tumor necrosis factor signaling and may upregulate gene expression. We therefore evaluated the effects of antioxidants on IL-1-induced cyclooxygenase-2 (Cox-2) and inducible nitric-oxide synthase (iNOS) expression in rat mesangial cells. The oxidant scavenger, pyrrolidine dithiocarbamate (PDTC), inhibited iNOS expression at the transcriptional level, since PDTC abolished iNOS mRNA accumulation. In contrast, PDTC inhibited Cox-2 expression at the post-transcriptional level, since PDTC did not affect IL-1-induced Cox-2 mRNA levels but inhibited Cox-2 protein expression and prostaglandin E 2 production. Another antioxidant, rotenone, which inhibits reactive oxygen intermediate production by inhibiting the mitochondrial electron transport system, did not inhibit IL-1-induced iNOS and Cox-2 mRNA expression but inhibited iNOS and Cox-2 protein expression, suggesting a post-transcriptional target for the inhibition of iNOS and Cox-2 expression induced by IL-1. These results suggest that not only transcriptional regulation but also post-transcriptional mechanisms are involved in redox-sensitive inhibition of cytokine induced Cox-2 and iNOS expression. These results suggest a novel approach for intervention in cytokine-mediated inflammatory processes.
Proceedings of the National Academy of Sciences, 1994
The inflammatory cytokine interleukin 1 beta (IL-1 beta) induces both cyclooxygenase (COX) and nitric oxide synthase (NOS) with increases in the release of prostaglandin (PG) and nitric oxide (NO) by mesangial cells. Recently, activation of the COX enzyme by NO has been described. However, the effects of COX products (PGs) on the NO pathway have not been fully clarified. Thus we determined the effect of COX inhibition and exogenous PGs on NO production and NOS induction in rat mesangial cells. A COX inhibitor, indomethacin, enhanced IL-1 beta-induced steady-state level of the inducible NOS (iNOS) mRNA and nitrite production. The effect of indomethacin was dose dependently reversed by the replacement of endogenous PGE2 with exogenous PGE2, which is the predominant product of the COX pathway in rat mesangial cells. In contrast to PGE2, a stable analog of PGI2, carba prostacyclin, enhanced IL-1 beta-induced iNOS mRNA levels and nitrite production. Forskolin, an activator of the adenyla...
Naunyn-Schmiedeberg's Archives of Pharmacology, 2001
Stimulation of J774 macrophages with lipopolysaccharide (LPS) leads to the release of large amounts of prostaglandins (PGs) generated by the inducible isoform of cyclooxygenase (COX-2). Nitric oxide (NO), a pleiotropic free radical, has been demonstrated to modulate the release of a broad range of inflammatory mediators, amongst these PGs. In the present study we investigated the molecular mechanism by which NO affects cyclooxygenase pathway. Incubation of J774 cells with LPS caused an increase of prostaglandin E 2 production and COX-2 protein expression which was prevented in a concentration-dependent fashion by pre-incubating cells with sodium nitroprusside (SNP) and S-nitroso-gluthatione (GSNO), two NO-generating agents. Electrophoretic mobility shift assay indicated that both NO-generating agents blocked LPS-induced activation of nuclear factor-κB (NF-κB) by increasing IκB-α protein expression and blocking nuclear translocation of NF-κB subunits p50 and p65. SNP and GSNO also inhibited nuclear factor-interleukin-6 (NF-IL6) activation. These results show for the first time that SNP and GSNO down-regulate LPS-induced COX-2 expression by inhibiting NF-κB and NF-IL6 activation and suggest a negative feed-back mechanism that may be important for limiting excessive or prolonged PGs production in pathological events.
Naunyn Schmied Arch Pharmacol, 2001
Stimulation of J774 macrophages with lipopolysaccharide (LPS) leads to the release of large amounts of prostaglandins (PGs) generated by the inducible isoform of cyclooxygenase (COX-2). Nitric oxide (NO), a pleiotropic free radical, has been demonstrated to modulate the release of a broad range of inflammatory mediators, amongst these PGs. In the present study we investigated the molecular mechanism by which NO affects cyclooxygenase pathway. Incubation of J774 cells with LPS caused an increase of prostaglandin E 2 production and COX-2 protein expression which was prevented in a concentration-dependent fashion by pre-incubating cells with sodium nitroprusside (SNP) and S-nitroso-gluthatione (GSNO), two NO-generating agents. Electrophoretic mobility shift assay indicated that both NO-generating agents blocked LPS-induced activation of nuclear factor-κB (NF-κB) by increasing IκB-α protein expression and blocking nuclear translocation of NF-κB subunits p50 and p65. SNP and GSNO also inhibited nuclear factor-interleukin-6 (NF-IL6) activation. These results show for the first time that SNP and GSNO down-regulate LPS-induced COX-2 expression by inhibiting NF-κB and NF-IL6 activation and suggest a negative feed-back mechanism that may be important for limiting excessive or prolonged PGs production in pathological events.
PLOS ONE
In rheumatoid arthritis (RA), nitric oxide (NO) is implicated in inflammation, angiogenesis and tissue destruction. The enzyme inducible nitric oxide synthase (iNOS) is responsible for the localised overproduction of NO in the synovial joints affected by RA. The pro-and antiinflammatory cytokines stimulate the synovial macrophages and the fibroblast-like synoviocytes to express iNOS. Therefore, the cytokine signalling network underlying the regulation of iNOS is essential to understand the pathophysiology of the disease. By using information from the literature, we have constructed, for the first time, the cytokine signalling network involved in the regulation of iNOS expression. Using the differential expression patterns obtained by re-analysing the microarray data on the RA synovium and the synovial macrophages available in the Gene Expression Omnibus (GEO) database, we aimed to establish the role played by the network genes towards iNOS regulation in the RA synovium. Our analysis reveals that the network genes belonging to interferon (IFN) and interleukin-10 (IL-10) pathways are always up-regulated in the RA synovium whereas the genes which are part of the anti-inflammatory transforming growth factor-beta (TGF-β) signalling pathway are mostly down-regulated. We observed a consistent up-regulation of the transcription factor signal transducers and activators of transcription 1 (STAT1) in the RA synovium and the macrophages. Interestingly, we found a consistent up-regulation of the iNOS interacting protein ras-related C3 botulinum toxin substrate 2 (RAC2) in the RA synovium as well as the macrophages. Importantly, we have constructed a model to explain the impact of IFN and IL-10 pathways on Rac2-iNOS interaction leading to overproduction of NO and thereby causing chronic inflammation in the RA synovium. The interplay between STAT1 and RAC2 in the regulation of NO could have implications for the identification of therapeutic targets for RA.
Nitric oxide amplifies interleukin 1-induced cyclooxygenase-2 expression in rat mesangial cells
Journal of Clinical Investigation, 1996
Interleukin 1 and nitric oxide (NO) from infiltrating macrophages and activated mesangial cells may act in concert to sustain and promote glomerular damage. To evaluate if such synergy occurs, we evaluated the effect if IL-1  and NO on the formation of prostaglandin (PG) E 2 and cyclooxygenase (COX) expression. The NO donors, sodium nitroprusside and S-nitroso-N-acetylpenicillamine, alone did not increase basal PGE 2 formation. However, these compounds amplified IL-1 -induced PGE 2 production. Similarly, sodium nitroprusside and S-nitroso-N-acetylpenicillamine by themselves did not induce mRNA and protein for COX-2, the inducible isoform of COX; however, they both potentiated IL-1 -induced mRNA and protein expression of COX-2. The stimulatory effect of NO is likely to be mediated by cGMP since (a) an inhibitor of the soluble guanylate cyclase, methylene blue, reversed the stimulatory effect of NO donors on COX-2 mRNA expression; (b) the membrane-permeable cGMP analogue, 8-Br-cGMP, mimicked the stimulatory effect of NO donors on COX-2-mRNA expression; and (c) atrial natriuretic peptide, which increases cellular cGMP by activating the membrane-bound guanylate cyclase, also amplified IL-1 -induced COX-2 mRNA expression. These data indicate a novel interaction between NO and COX pathways.
Inflammation Research, 1997
This meeting, chaired by Professor Willoughby, was organised at short notice and yet pulled a full house and, at times standing room only, in the auditorium. This interest reflects the rapid expansion of work in the role of the cytokine-inducible enzymes for three chemical mediators, prostaglandins, nitric oxide, and bilirubin/carbon monoxide. The symposium, was organised to have two speakers presenting on each enzyme, with one presenting data on interactions to pull the symposium together. Cyclo-oxygenase-2 (COX-2) was introduced by Dr. Jane Mitchell of the National Heart and Lung Institute, London, who summarised the pathways of arachidonic acid release and cell processing for the production of eicosanoids, highlighting the selective nature of certain cells for the end product. COX-2 is expressed on cytokine-stimulation in the inflammatory locus, whilst little is expressed by the gastric mucosa making this a potentially important enzyme target for novel anti-inflammatory therapeutics devoid of gastrotoxicity. The difficulties of assessing the selectivity of nonsteroidal and anti-inflammatory drugs (NSAIDs) for COX-1 or-2 was illustrated by comparing the COX-2/COX-1 IC50 ratios for aspirin and ibuprofen in intact, broken and isolated enzyme from endothelial cells (COX-1) and LPS-stimulated J774 cells (COX-2). Aspirin elicited ratios of 166, 25 and 42 respectively, whereas ibuprofen elicited 15, 53 and 46. Such differences, as well as differences in cell types used, reveal complex interactions between the drugs and COX-2 within the whole cell which may involve varying degrees of substrate availability, membrane transport and intracellular kinetics. There appears some consensus that piroxicam, sulindac, aspirin, indomethacin and ibuprofen are largely COX-1 selective, whilst diclofenac and meloxicam err on the side of COX-2 with NS398, L-745,337 and the new generation inhibitors being highly selective for COX-2. Novel items of relevance in the clinic were noted, for example COX-2 expression in isolated tissues for transplant