Suppression of Heme Oxygenase-1 by Prostaglandin E2-Protein Kinase A-A-Kinase Anchoring Protein Signaling Is Central for Augmented Cyclooxygenase-2 Expression in Lipopolysaccharide-Stimulated RAW 264.7 Macrophages

Purpose

Prostaglandin (PG) E₂ is an immunomodulatory lipid mediator generated mainly via the cyclooxygenase-2 (COX-2) pathway from arachidonic acid at sites of infection and inflammation. A positive feedback loop of PGE₂ on COX-2 expression is critical for homeostasis during toll-like receptor (TLR)-mediated inflammatory processes. The mechanism of PGE₂-regulated COX-2 expression remains poorly understood. The low-molecular-weight stress protein heme oxygenase-1 (HO-1) contributes to the anti-inflammatory, anti-oxidant and anti-apoptotic response against environmental stress.

Methods

We explored the involvement of HO-1 on PGE₂ regulation of LPS-induced COX-2 expression in RAW 264.7 macrophages.

Results

LPS-induced COX-2 expression in RAW 264.7 macrophages was enhanced by exogenous PGE₂ or cyclic AMP (cAMP) analogue and was suppressed by a COX inhibitor (indomethacin), a protein kinase A (PKA) inhibitor (KT5720), and A kinase anchoring protein (AKAP) disruptors (Ht31 and RIAD). This result suggests that the stimulatory effects of endogenous and exogenous PGE₂ on COX-2 expression are mediated by a cAMP-PKA-AKAP-dependent pathway. The induction of HO-1 was observed in LPS-stimulated RAW 264.7 macrophages. This induction was suppressed by exogenous PGE₂ and enhanced by blockage of the endogenous PGE₂ effect by the PKA inhibitor or AKAP disruptors. In addition, HO-1 induction by the HO activator copper protoporphyrin suppressed LPS-induced COX-2 expression, which was restored by the addition of exogenous PGE₂. The induction of HO-1 inhibited LPS-induced NF-κB p-65 nuclear expression and translocation.

Conclusions

AKAP plays an important role in PGE₂ regulation of COX-2 expression, and the suppression of HO-1 by PGE₂-cAMP-PKA-AKAP signaling helps potentiate the LPS-induced COX-2 expression through a positive feedback loop in RAW 264.7 macrophages.     

Expression of cyclooxygenase-1/-2, microsomal prostaglandin-E synthase-1 and E-prostanoid receptor 2 and regulation of inflammatory mediators by PGE2 in the amoeboid microglia in hypoxic postnatal rats and murine BV-2 cells

This study aimed to investigate the effect of hypoxia on the expression of cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), microsomal prostaglandin-E synthase (mPGES-1), E-prostanoid receptor 2 (EP2) in microglia; and the roles of EP2-cyclic adenosine monophosphate (cAMP) signaling pathway in the prostaglandin E₂ (PGE₂) regulation of inflammatory mediators released by hypoxic BV-2 cells. Immunoexpression of COX-1, COX-2, mPGES-1 and EP2 was localized in the amoeboid microglial cells (AMC), a nascent brain macrophage in the developing brain, as confirmed by double labeling with OX-42 and lectin, specific markers of microglia. AMC emitted a more intense immunofluorescence in hypoxic rats when compared with the matching controls. In postnatal rats subjected to hypoxia, mRNA and protein expression levels of COX-1, COX-2 and mPGES-1 along with tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric-oxide synthase (iNOS) and PGE₂ product in the callosal tissue were significantly increased. The results were shared in the BV-2 cells except for COX-1 mRNA and protein whose levels remained unaltered. Interestingly, treatment with EP2 antagonist AH-6809 resulted in suppression of hypoxia induced EP2, IL-1β and iNOS mRNA and protein expression, TNF-α protein expression and intracellular cAMP level in BV-2 cells. It is suggested that PGE₂ may regulate above inflammatory mediators in the activated microglia via EP2-cAMP signaling pathway in hypoxic conditions.     

Positive feedback regulation of COX-2 expression by prostaglandin metabolites

Objectives: Previous studies in cell lines and tissues derived from mice lacking genes encoding cyclooxygenase (COX)-1 or –2 have demonstrated compensatory regulation between the two isoenzymes. To determine whether this compensation was driven by a mechanism that controls prostaglandin (PG) levels, we investigated the effects of PG availability on the regulation of COX and cytosolic phospholipase A₂ (cPLA₂), an upstream enzyme in the PG pathway.Materials and methods: Mouse lung fibroblast cells were treated with various concentrations of PG metabolites including prostaglandin E₂ (PGE₂), 15-deoxy-^12,14-prostaglandin J₂ (15d-PGJ₂), 6-keto PGF₁ and PGF₂ Cells were harvested for protein and mRNA analyses; culture supernatant was collected for prostaglandin assays.Results: We observed 8- and 20-fold increase in basal COX-2 protein expression levels when cells were exposed to PGE₂ and 15d-PGJ₂, respectively. In the presence of IL-1, PGE₂, 15d-PGJ₂, 6-keto PGF₁ and PGF₂ each enhanced COX-2 protein expression between 5- to 20-fold. Corresponding with the induction of COX-2 protein expression, the latter three PGs induced PGE₂ synthesis in a dose-dependent manner. Only PGE₂ and 15d-PGJ₂ induced COX-2 mRNA expression, although to a lower extent than protein induction. None of the PG metabolites tested showed significant effects on the level of COX-1 or cPLA₂ protein expression, except for PGF₂, which increased IL-1-induced cPLA₂ protein expression slightly.Conclusion: Our results demonstrate that there is positive feedback regulation of COX-2 expression by PG metabolites, but not COX-1, indicating that PG levels per se do not play an important role in the compensatory regulation between the two COX isoenzymes, but may play an important role in mediating increased COX-2 expression and activity.Received 16 August 2004; returned for revision 9 September 2004; accepted by A. Falus 20 December 2004     

Effect of Hypoxia on the Muscle Fiber Switching Signal Pathways CnA/NFATc1 and Myostatin in Mouse Myocytes

This study investigated the effects of a CoCl₂-simulated hypoxic environment on the muscle fiber switching signaling pathways calcineurin A/nuclear factor of activated T cells cytoplasmic 1 (CnA/NFATc1) and myostatin. In this study, C2C12 muscle cells were cultured in vitro under CoCl₂-simulated chemical hypoxic conditions, the expression levels of CnA and myostatin were detected through qRT-PCR and Western blot analyses, and a positioning study of NFATc1 was carried out by immunofluorescence labeling. Results showed that CoCl₂ treatment significantly increased the expression levels of CnA and myostatin. Moreover, the position of NFATc1 expression changed; actually, its expression in the nucleus considerably increased. Furthermore, CoCl₂-induced hypoxia inhibited the differentiation of C2C12 cells and reduced the expression levels of many slow- and fast-twitch muscles marker genes, but immunofluorescence staining results showed that the proportion of MyHC I type muscle fiber increased after CoCl₂ treatment. The hypoxic environment simulated by CoCl₂ can activate the signaling pathways CnA/NFATc1 and myostatin and increases the proportion of MyHC I type muscle fibers.     

<Emphasis Type="Italic">Toxoplasma gondii</Emphasis> induces prostaglandin E<Subscript>2</Subscript> synthesis in macrophages via signal pathways for calcium-dependent arachidonic acid production and PKC-dependent induction of cyclooxygenase-2

In this study, the intracellular signaling pathway of PGE₂ synthesis in macrophages (RAW264.7) induced by Toxoplasma gondii was investigated. The T. gondii-induced PGE₂ production in macrophages increased in a time-dependent manner, as PGE₂ induction began at 4 h, peaked at 12 h, and then plateaued at a high level. COX-2 mRNA in macrophages was detectable as early as 4 h after treatment; the maximal expression was observed at 8 h. The earliest induction of COX-2 protein occurred at 4 h and peaked at 16 h; meanwhile, COX-1 mRNA level and protein production remained unchanged throughout. Indomethacin and nimesulide inhibited tachyzoite-induced PGE₂ production and COX-2 mRNA expression in macrophages but they had no significant effect on COX-2 protein expression. EGTA, TFP and BAPTA/AM inhibited both arachidonic acid (AA) and PGE₂ production without effecting COX-2 protein expression, but verapamil inhibited neither AA nor PGE₂ production. H7 was found to inhibit PGE₂ production, and COX-2 mRNA expression and protein expression by tachyzoite or LPS stimulated macrophages in a dose-dependent manner. Our results demonstrate that T. gondii induces PGE₂ biosynthesis in RAW264.7 macrophages by regulating AA production through a calcium-dependent pathway and induction of COX-2 expression by a PKC-dependent pathway.     

Positive feedback effect of PGE2 on cyclooxygenase-2 expression is mediated by inhibition of Akt phosphorylation in human follicular dendritic cell-like cells

Prostaglandins (PGs) are bioactive lipid mediators generated from the phospholipids of cell membrane in response to various inflammatory signals. To understand the potential role of PGs in PG production itself during immune inflammatory responses, we examined the effect of PGE₂, PGF_2α, and beraprost on COX-2 expression using follicular dendritic cell (FDC)-like HK cells isolated from human tonsils. Those three PGs specifically augmented COX-2 protein expression in a dose-dependent manner after 4 or 8 h of treatment. The enhancing effect was also reflected in the actual production of PGs and the viable cell recovery of germinal center B-cells. To investigate the underlying molecular mechanism, we examined the impact of PI3K inhibitors on PG-induced COX-2 expression. Interestingly, COX-2 induction by PGE₂ and beraprost, but not PGF_2α, was enhanced by wortmannin and LY294002. In line with this result, Akt phosphorylation was inhibited by PGE₂ and beraprost but not by PGF_2α. The distinct effect of PGE₂ and beraprost from PGF_2α was reproduced in Akt-knockdowned HK cells. Our current findings imply that PGE₂ and PGI₂ stimulate COX-2 expression in FDC by inhibiting Akt phosphorylation. Additional studies are warranted to determine the potential role of Akt as a therapeutic target in patients with inflammatory disorders.     

Comparative Study of Normal and Rheumatoid Arthritis Fibroblast-Like Synoviocytes Proliferation under Cyclic Mechanical Stretch: Role of Prostaglandin E2

Fibroblast-like synoviocytes (FLSs) are one of the main contributors of prostaglandin E₂ (PGE₂) in the hyperplastic synovium of rheumatoid arthritis (RA) patients. cyclooxygenase-2 (COX-2)/PGE₂ pathway is involved in the proliferation of several cell types. We have previously shown that mechanical stretch affects COX-2 and PGE₂ production in human RA FLSs; however, its role in cell proliferation remains to be elucidated. In this study, a comparison is drawn between human RA and normal FLSs to understand the role of mechanical stretch and PGE₂ on the proliferation of FLSs. The results showed that physiological level (6%, 1 Hz) of cyclic mechanical stretch significantly decreased the proliferation of RA FLSs but not normal FLSs, while the induction of apoptosis was not observed by stretch in either RA or normal FLSs. IL-1β (5 ng/ml)-induced COX-2/PGE₂ levels are downregulated by stretch in RA FLSs only. Further investigation showed that high concentration (100 and 500 ng/ml) of PGE₂ significantly induced cell proliferation only in RA FLSs, and this induction failed to be suppressed by stretch. In conclusion, this study demonstrated that elevated levels of PGE₂ in the synovial cavity are involved in the proliferation of RA FLSs, and cyclic mechanical stretch regulates the RA synovial hyperplasia.     

Cyclooxygenase-2 mediates the delayed cardioprotection induced by hydrogen sulfide preconditioning in isolated rat cardiomyocytes

We previously reported that hydrogen sulfide (H₂S) preconditioning (SP) produces cardioprotection in isolated rat cardiomyocytes. The present study was designed to determine the involvement of cyclooxygenase-2 (COX-2) in the SP-induced delayed cardioprotection. Isolated cardiac myocytes were treated with NaHS (100 μM, a H₂S donor) for 30 min and then cultured for 20 h followed by ischemia/reperfusion insults. SP significantly increased cell viability, percentage of rod-shaped cells, and myocyte contractility after 10 min of reperfusion. Given 30 min before and during lethal ischemia, two selective COX-2 inhibitors, NS-398 and celebrex, abrogated SP-induced cardioprotective effects. Moreover, SP upregulated the expression of COX-2 and increased PGE₂ production in the cardiac myocytes. These effects were significantly attenuated by glibenclamide, an ATP-sensitive K⁺ channel (K_ATP) blocker, and chelerythrine, a selective protein kinase C (PKC) inhibitor, suggesting that activation of both K_ATP and PKC is required for the stimulation of COX-2. Additionally, NG-nitro-l-arginine methyl ester, a nitric oxide synthase inhibitor, failed to regulate COX-2 protein expression but inhibited SP-enhanced COX-2 activity and PGE₂ production. In conclusion, we provided the first evidence that SP may produce delayed cardioprotection via K_ATP/PKC dependent induction of COX-2 expression and via nitric oxide-induced COX-2 activation.     

IL-1β Stimulates the Expression of Prostaglandin Receptor EP4 in Human Chondrocytes by Increasing Production of Prostaglandin E2

Prostaglandin (PG) E₂, which exerts its actions via the PG receptors EP1–4, is produced from arachidonic acid by cyclooxygenase (COX)-1 and COX-2. The aim of this study was to investigate the mechanisms by which interleukin (IL)-1β induces the expression of PG receptors in cultured human chondrocytes and to explore the role of PGE₂ in this process. The cells were cultured with 0, 10, or 100 U/mL IL-1β with or without 1 μM celecoxib, a specific inhibitor of COX-2, for up to 28 days. Expression of the genes encoding COX-1, COX-2, and EP1–4 was quantified using real-time PCR, and expression of the corresponding proteins was examined using immunohistochemical staining. PGE₂ production was determined using ELISA. IL-1β treatment caused a marked dose- and time-dependent increase in the levels of PGE₂, COX-2, and EP4 as compared with the untreated control. It did not affect the expression of COX-1, and it decreased the expression of EP1 and EP2. EP3 expression was not detected in either the absence or the presence of IL-1β. When celecoxib was also present, IL-1β failed to stimulate PGE₂ production and EP4 expression, but its stimulatory effect on COX-2 expression and its inhibitory effect on EP1 and EP2 expression were unchanged. IL-1β increases the production of PGE₂, COX-2, and the PG receptor EP4 in cultured human chondrocytes. The increase in EP4 expression appears to be a result of the increased PGE₂ production.     

Downregulation of inflammatory mediators and pro-inflammatory cytokines by alkaloids of jeevaneeya rasayana in adjuvant-induced arthritis

Jeevaneeya rasayana is an ayurvedic polyherbal formulation, with antirheumatic potential. The present study investigates the therapeutic efficacy of isolated total alkaloid fraction of Jeevaneeya Rasayana (AJR) in treating rheumatoid arthritis in a rat model of Adjuvant-induced arthritis (AIA). Paw swelling, inflammatory mediators such as cyclooxygenase-2 (COX-2), matrix metalloproteinase-9 (MMP-9), level of prostaglandin E₂ (PGE₂), expression of cytokines and serum nitric oxide (NO) level were analyzed in experimental rats after an experimental period of 21 days. Arthritic induction significantly increased paw edema, and up regulated the inflammatory mediators and cytokines. Administration of AJR significantly reversed the paw edema, reduced the level of PGE₂, serum NO and decreased the COX-2 activity in the paw tissue. AJR treatment also downregulated mRNA expression of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and MMP-9 in paw tissue. HPTLC analysis revealed the presence of 5 different alkaloid compounds in AJR. These findings suggest that the AJR have the therapeutic potential against adjuvant-induced arthritis.     

Compressive Force Induces Osteoclast Differentiation via Prostaglandin E2 Production in MC3T3-E1 Cells

In orthodontic tooth movement, prostaglandin E₂ (PGE₂) released from osteoblasts can alter the normal process of bone remodeling. We previously showed that compressive force (CF) controls bone formation by stimulating the production of PGE₂ and Ep2 and/or Ep4 receptors in osteoblasts. The present study was undertaken to examine the effect of CF on the production of PGE₂, cyclooxygenase-2 (COX-2), macrophage colony-stimulating factor (M-CSF), receptor activator of NF-κB ligand (RANKL), and osteoprotegerin (OPG) using osteoblastic MC3T3-E1 cells and to examine the indirect effect of CF on osteoclast differentiation using RAW264.7 cells as osteoclast precursors. MC3T3-E1 cells were cultured with or without continuous CF (1.0 or 3.0 g/cm²) for 24 hr, and PGE₂ production was determined using ELISA. The expression of COX-2, M-CSF, RANKL, and OPG genes and proteins was determined using real-time PCR and ELISA, respectively. Osteoclast differentiation was estimated using tartrate-resistant acid phosphatase (TRAP) staining of RAW 264.7 cells cultured for 10 days with conditioned medium from CF-treated MC3T3-E1 cells and soluble RANKL. As CF increased, PGE₂ production and the expression of COX-2, M-CSF, and RANKL increased, whereas OPG expression decreased. The number of TRAP-positive cells increased as CF increased. Celecoxib, a specific inhibitor of COX-2, blocked the stimulatory effect of CF on TRAP staining and the production of PGE₂, M-CSF, RANKL, and OPG. These results suggest that CF induces osteoclast differentiation by increasing M-CSF production and decreasing OPG production via PGE₂ in osteoblasts.     

The regulation of prostate cancer cell adhesion to human bone marrow endothelial cell monolayers by androgen dihydrotestosterone and cytokines

A previous study from our laboratory suggested that prostate cancer metastasis to bone may be mediated, in part, by preferential adhesion to human bone marrow endothelial (HBME) cells. Tumor cell adhesion to endothelial cells may be modulated by the effect of cytokines on cell adhesion molecules (CAMs). Tumor necrosis factor-alpha (TNF-α) regulates VCAM expression on the endothelium and this effect is enhanced by dihydrotestosterone (DHT). Transforming growth factor-beta (TGF-β) stimulates the expression of α₂β₁integrin on PC-3 cells. The current study investigated the effects of the above cytokines and DHT (singularly and in various combinations) upon HBME and prostate cancer cell expression of VCAM, α₂ integrin subunit, and β₁ integrin subunit by flow cytometry. We also monitored the effects of the above treatments on PC-3 cell adhesion to HBME monolayers. The data demonstrate that none of the treatments significantly altered the expression of selected CAMs on HBME cell and neoplastic prostate cell lines. The treatment of HBME monolayers with various combinations of cytokines and DHT prior to performing adhesion assays with PC-3 demonstrates that treatments containing TGF-β reduced PC-3 cell adhesion to HBME monolayers by 32% or greater (P<0.05). The reduction in PC-3 cell adhesion to TGF-β-treated HBME monolayers was dose dependent. Interestingly, LNCaP cells but not PC-3 cells treated with TGF-β had a reduced ability to adhere to untreated HBME monolayers. These results suggest that TGF-β may reduce tumor cell adhesion to bone marrow microvascular endothelium, in vivo. The biological significance of this observation is discussed.     

Prostaglandin production via induction of cyclooxygenase-2 by human gingival fibroblasts stimulated with lipopolysaccharides

The purpose of the present study was to investigate the involvement of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) in PGE₂ production by human gingival fibroblasts stimulated with lipopolysaccharides (LPS) from periodondopathogenic bacteria. LPS were isolated fromPorphyromonas gingivalis (P. gingivalis), Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) andEschericia coli (E. coli) by the phenol-water procedure. The three LPS preparations produced PGE₂ up to 48 h in a time-dependent manner in human gingival fibroblasts.P. gingivalis-LPS was the most potent stimulator of PGE₂ production and, to a lesser extent,A. actinomycetemcomitans- andE. coli-LPS. Treatment of the cells with indomethacin, a non selective COX-1/COX-2 inhibitor and NS-398, a selective COX-2 inhibitor, completely depressed PGE₂ production. Treatment of dexamethasone, known to inhibit COX-2 expression, also significantly prevented PGE₂ production. Immunohistochemical staining of COX-2 protein demonstrated that expression of COX-2 protein was increased at 24 h afterP. gingivalis-LPS stimulation, while expression of COX-1 protein was not affected byP. gingivalis-LPS. In order to investigate the regulation of PGE₂ production,P. gingivalis-LPS-stimulated cells were treated with herbimycin A and genistein, both inhibitors of tyrosine kinases. Both the inhibitors significantly inhibited PGE₂ production. Herbimycin A treatment depressed expression of COX-2 protein. These data suggest that human gingival fibroblasts stimulated with LPS from periodontopathogenic bacteria mainly produce PGE₂ not by COX-1, but by COX-2, induction of which may be regulated by tyrosine kinase and that the produced PGE₂ may be involved in the pathogenesis of periodontal diseases.     

Anti-CD45 antibody enhances lipoxygenase pathway of human naïve mononuclear cells and cyclooxygenase pathway of neutrophils

Objective and Design: Anti-CD45 antibody exhibits multiple biological effects on human mononuclear cells (MNC) and polymorphonuclear neutrophils (PMN). We intended to determine whether anti-CD45 antibody could affect arachidonic acid metabolism and thereby, the interactions between human na?ve MNC and PMN. Materials and Methods: Human na?ve MNC and PMN were incubated with monoclonal anti-human CD45 IgG F(ab’)₂ antibody or non-specific IgG F(ab’)₂ for 30 min. The mRNA expression of cyclooxygenase type 1 (COX-1), type 2 (COX-2), 5-lipoxygenase (5-LOX) and leukotriene A₄ hydrolase (LTA₄ hydrolase) in both cells was detected by RT-PCR and quantified by densitometric determination. The presence of COX-1 and COX-2 molecules in the cells was detected by Western blot. The concentration of PGE₂ and LTB₄ in cultured supernatants was measured by EIA kits. Results: Anti-CD45 IgG F(ab’)₂ up-regulated LTA₄ hydrolase mRNA expression and LTB₄ production, but down-regulated COX-1 and COX-2 mRNA expression and PGE2 production, of na?ve MNC compared to non-specific IgG F(ab’)₂. In contrast, a reverse modulation by the specific antibody on PMN was observed including up-regulation of cyclooxygenase pathway and down-regulation of lipoxygenase pathway. Conclusions: A novel activity of anti-CD45 with reverse modulation on cyclooxygenase/lipoxygenase pathways was found such that the expression of COX-1 and COX-2 in PMN, and 5-LOX and LTA₄ hydrolase in MNC were enhanced. Received 4 May 2005; returned for revision 29 June 2005; returned for final revision 12 October 2005; accepted by M. Katori 16 November 2005     

Temporal expression of cyclooxygenase-2 in peritoneal macrophages of rats and effects of panax notoginseng saponins

Objective:  To explore the temporal expression pattern of cyclooxygenase (COX)-2 and effects of panax notogensing saponins (PNS) in peritoneal macrophages of rats. Materials and methods:  Phagocytosis function of peritoneal macrophages was measured by chicken red blood cell phagocytosis assay in vitro. Expression of COX-2 mRNA and protein, PGE₂ and PGD₂ production were determined with real-time PCR, Western blotting and radioimmunoassay, respectively. Results:  Phagocytosis function of macrophages increased significantly after stimulation and reached peak during 2–3h. Expression of COX-2 mRNA and its protein increased markedly after stimulation and reached the first peak at 2 h and 3h, respectively; and then decreased to reach a minimum at 24h. The second peak appeared at 36h. PNS (50, 100, 200 mg/kg) increased the phagocytosis function obviously at 2h, decreased the expression level of COX-2 and PGE₂ production at 2 h and elevated COX-2 expression and PGD₂ production at 36 h, respectively. Conclusion:  COX-2 expression in peritoneal macrophages has a double-hump feature after stimulation. PNS enhanced phagocytosis, inhibiting COX-2 expression at an early stage and elevating it at a later stage. Received 29 February 2008; returned for revision 27 March 2008; received from final revision 14 May 2008; accepted by G. Wallace 9 June 2008 The first two authors contributed equally to this work.     

白细胞介素-10抑制人肾系膜细胞环氧化酶-2表达及其催化的前列腺素E2释放的实验研究

目的:观察IL-10对IL-1β诱导的人系膜细胞(HMC)前列腺素E₂(PGE₂)释放及环氧化酶-2(cyclooxygenase-2,COX-2)基因和蛋白表达的影响。方法:应用放射免疫测定法检测HMC培养上清中PGE₂,应用RT-PCR和Westernblot分别检测COX-2mRNA和蛋白水平。结果:①IL-1β显著上调PGE₂释放及COX-2基因和蛋白的表达(P均＜0.01);②IL-10对基础状态下PGE₂释放及COX-2基因和蛋白表达无明显影响(P＞0.05);③IL-10可呈剂量依赖性地下调IL-1β诱导的PGE₂释放及COX-2mRNA和蛋白表达(P＜001)。结论:IL-10抑制IL-1β诱导的HMCPGE₂释放及COX-2表达,提示IL-10对HMC具有多方面抗炎作用。