Prostaglandin E2 stimulates COX-2 expression via mitogen-activated protein kinase p38 but not ERK in human follicular dendritic cell-like cells.
ABSTRACT: BACKGROUND:Prostaglandin E2 (PGE2) is an endogenous lipid mediator of inflammation. Its production is regulated by the rate-limiting upstream enzyme cyclooxygenase-2 (COX-2). We have recently demonstrated that the major cell type expressing COX-2 in the germinal center is follicular dendritic cell (FDC). In this study, to elucidate the molecular mechanism of PGE2 in COX-2 production, we asked whether mitogen-activated protein kinases ERK and p38 might regulate COX-2 expression. RESULTS:FDC-like cells were used to analyze the phosphorylation kinetics of ERK and p38 and the impact of genetic knockdown. PGE2 stimulation gave rise to a rapid increase of p38 but not ERK phosphorylation. In contrast, IL-1? induced phosphorylation of both MAPKs. Knockdown of p38 resulted in a marked suppression of COX-2 expression induced by either PGE2 or IL-1?. ERK knockdown did not significantly affect the effect of PGE2 and IL-1? on COX-2 induction. The differential results of p38 and ERK siRNA transfection were reproduced in the production of prostaglandins and in experiments performed with pharmacologic inhibitors. CONCLUSIONS:Our data indicate that p38 is essentially required for PGE2 to induce COX-2 expression in FDC-like cells. The current study helps to expand our understanding of the biological function of FDC at the molecular level and provides a potential rationale for the pharmacologic or genetic approaches to regulate p38 MAPK in the treatment of various inflammatory disorders.
Project description:Immune dysfunction is hallmark of patients with non-small cell lung carcinoma (NSCLC). The molecular mechanism involved in COX-2- and PGE2-mediated production of immunosuppressive cytokine IL-10 is not well-understood. Our study addresses the involvement of T cell downstream signalling intermediates, cytokines (IL-10 and IFN-?) and their transcription factors (T-bet and GATA-3) in COX-2-mediated regulation of lymphocyte functions in NSCLC patients. In comparison to healthy individual, a marked decrease in lymphocyte proliferation to anti-CD3 MAb was observed in NSCLC patients by thymidine incorporation assay. Using flow cytometry, decrease in intracellular calcium release with increase in reactive oxygen species was observed in lymphocytes of NSCLC patients. These patients showed increased IL-10 and PGE2 with reduced IFN-? production by ELISA. Results demonstrated defect in regulation of transcription factors T-bet and GATA-3 as analysed by Western blotting (WB), immunoprecipitation and EMSA. Overexpression of p-p38, p-ERK and COX-2 were observed with diminished p-JNK by WB. IL-10/IFN-? levels were found to be differentially regulated via p38 and ERK mitogen-activated protein kinase (MAPK) pathways in cooperation with COX-2. Inhibition of these pathways using selective inhibitors lead to increased lymphocyte proliferative response to anti-CD3 MAb and IFN-? production with decrease in IL-10 production. Studies showed involvement of ERK, p38 and COX-2 pathways in high IL-10 production, driven by lung tumour derived PGE2. The selective COX-2 inhibitor rofecoxib showed ability to alter the cytokine balance by affecting regulation of T-bet and GATA-3 transcription factors.
Project description:Cancer-promoting inflammation is an important event in cancer development. Canine urothelial carcinoma (cUC) overexpresses prostaglandin E2 (PGE2) and has a unique sensitivity to cyclooxygenase 2 (COX2)-inhibiting therapy. In addition, majority of cUC harbour BRAFV595E mutation. However, mechanisms underlying aberrant PGE2 production in BRAFV595E cUC patients remain unclear. Drug screening revealed that inhibition of RAF/MEK/ERK pathway, p38 and JNK pathway reduced PGE2 production in cUC cells. By pharmacological inhibition of the multiple components in the pathway, activation of the ERK MAPK pathway was shown to mediate overexpression of COX2 and production of PGE2 in BRAFV595E cUC cells. In silico gain-of-function analysis of the BRAF mutation also implicated involvement of mutation in the process. The positive association between ERK activation and COX2 expression was further validated in the clinical patients. Moreover, it was also suggested that p38 and JNK regulates PGE2 production independently of ERK pathway, possibly through COX2-dependent and COX1-/COX2- independent manner, respectively. In conclusion, this study demonstrated that activation of ERK induces production of PGE2 in BRAFV595E cUC cells, which is also independently regulated by p38 and JNK. With its unique vulnerability to COX-targeted therapy, BRAFV595E cUC may serve as a valuable model to study the tumour-promoting inflammation.
Project description:Bone marrow-derived mesenchymal stem cells (MSCs) have been identified as one possible strategy for the treatment of chronic obstructive pulmonary disease (COPD). Our previous studies have demonstrated that MSC administration has therapeutic potential in airway inflammation and emphysema via a paracrine mechanism. We proposed that MSCs reverse the inflammatory process and restore impaired lung function through their interaction with macrophages. In our study, the rats were exposed to cigarette smoke (CS), followed by the administration of MSCs into the lungs for 5 weeks. Here we show that MSC administration alleviated airway inflammation and emphysema through the down-regulation of cyclooxygenase-2 (COX-2) and COX-2-mediated prostaglandin E2 (PGE2) production, possibly through the effect on alveolar macrophages. In vitro co-culture experiments provided evidence that MSCs down-regulated COX-2/PGE2 in macrophages through inhibition of the activation-associated phosphorylation of p38 MAPK and ERK. Our data suggest that MSCs may relieve airway inflammation and emphysema in CS-exposed rat models, through the inhibition of COX-2/PGE2 in alveolar macrophages, mediated in part by the p38 MAPK and ERK pathways. This study provides a compelling mechanism for MSC treatment in COPD, in addition to its paracrine mechanism.
Project description:Microbial stimuli and atmospheric particulate matter (PM) interact to amplify the release of inflammatory and immune-modulating cytokines. The basis of this interaction, however, is not known. Cultured human lung fibroblasts (HLF) were used to determine whether various protein kinase pathways were involved in the release of IL-6 following combined exposure to the PM-derived metal, Ni, and M. fermentans-derived macrophage-activating lipopeptide 2 (MALP-2), a toll-like receptor 2 agonist. Synergistic release of IL-6 by MALP-2 and NiSO4 was obvious after 8h of co-stimulation and correlated with a late phase accumulation of IL-6 mRNA. Ni and MALP-2, alone or together, all led to rapid and transient phosphorylations of ERK(1/2) and JNK/SAPK of similar magnitude. p38 phosphorylation, however, was observed only after prolonged treatment of cells with both stimuli together. A constitutive level of PI3K-dependent Akt phosphorylation remained unchanged by Ni and/or MALP-2 exposure. IL-6 induced by Ni/MALP-2 co-exposure was partially dependent on activity of HIF-1alpha and COX-2 as shown by targeted knockdown using siRNA. IL-6 release in response to Ni/MALP-2 was partially sensitive to pharmacological inhibition of ERK(1/2), p38, and PI3K signaling. The protein kinase inhibitors had minimal or no effects on Ni/MALP-2-induced accumulation of HIF-1alpha protein, however, COX-2 expression and, more markedly PGE(2) production, were suppressed by LY294002, SB203580, and U0126. Thus, Ni/MALP-2 interactions involve multiple protein kinase pathways (ERK(1/2), p38, and PI3K) that modulate events downstream from the early accumulation of HIF-1alpha to promote IL-6 gene expression directly or secondarily, through COX-2-derived autocrine products like PGE(2).
Project description:Phyllanthus amarus has been used widely in various traditional medicines to treat swelling, sores, jaundice, inflammatory diseases, kidney disorders, diabetes and viral hepatitis, while its pharmacological and biochemical mechanisms underlying its anti-inflammatory properties have not been well investigated. The present study was carried out to investigate the effects of 80% ethanolic extract of P. amarus on pro-inflammatory mediators release in nuclear factor-kappa B (NF-?B), mitogen activated protein kinase (MAPK) and phosphatidylinositol 3-kinase/Akt (PI3K-Akt) signaling activation in lipopolysaccharide (LPS)-induced U937 human macrophages.The release of prostaglandin E2 (PGE2) and pro-inflammatory cytokines, tumor necrosis factor (TNF)-? and interleukin (IL)-1? in a culture supernatant was determined by ELISA. Determination of cyclooxygenase-2 (COX-2) protein and the activation of MAPKs molecules (JNK, ERK and p38 MAPK), NF-?B and Akt in LPS-induced U937 human macrophages were investigated by immunoblot technique. The relative gene expression levels of COX-2 and pro-inflammatory cytokines were measured by using qRT-PCR. The major metabolites of P. amarus were qualitatively and quantitatively analyzed in the extract by using validated reversed-phase high performance liquid chromatography (HPLC) methods.P. amarus extract significantly inhibited the production of pro-inflammatory mediators (TNF-?, IL-1?, PGE2) and COX-2 protein expression in LPS-induced U937 human macrophages. P. amarus-pretreatment also significantly downregulated the increased mRNA transcription of pro-inflammatory markers (TNF-?, IL-1?, and COX-2) in respective LPS-induced U937 macrophages. It downregulated the phosphorylation of NF-?B (p65), I?B?, and IKK?/? and restored the degradation of I?B?, and attenuated the expression of Akt, JNK, ERK, and p38 MAPKs phosphorylation in a dose-dependent manner. P. amarus extract also downregulated the expression of upstream signaling molecules, TLR4 and MyD88, which play major role in activation of NF-?B, MAPK and PI3K-Akt signaling pathways. The quantitative amounts of lignans, phyllanthin, hypophyllahtin and niranthin, and polyphenols, gallic acid, geraniin, corilagin, and ellagic acid in the extract were determined by HPLC analysis.The study revealed that P. amarus targeted the NF-?B, MAPK and PI3K-Akt signaling pathways to exert its anti- inflammatory effects by downregulating the prospective inflammatory signaling mediators.
Project description:The mechanism underlying pulmonary inflammation in thermal inhalation injury remains elusive. Cystic fibrosis, also hallmarked with pulmonary inflammation, is caused by mutations in CFTR, the expression of which is temperature-sensitive. We investigated whether CFTR is involved in heat-induced pulmonary inflammation. We applied heat-treatment in 16HBE14o- cells with CFTR knockdown or overexpression and heat-inhalation in rats in vivo. Heat-treatment caused significant reduction in CFTR and, reciprocally, increase in COX-2 at early stages both in vitro and in vivo. Activation of ERK/JNK, NF-?B and COX-2/PGE2 were detected in heat-treated cells, which were mimicked by knockdown, and reversed by overexpression of CFTR or VX-809, a reported CFTR mutation corrector. JNK/ERK inhibition reversed heat-/CFTR-knockdown-induced NF-?B activation, whereas NF-?B inhibitor showed no effect on JNK/ERK. IL-8 was augmented by heat-treatment or CFTR-knockdown, which was abolished by inhibition of NF-?B, JNK/ERK or COX-2. Moreover, in vitro or in vivo treatment with curcumin, a natural phenolic compound, significantly enhanced CFTR expression and reversed the heat-induced increases in COX-2/PGE2/IL-8, neutrophil infiltration and tissue damage in the airway. These results have revealed a CFTR-regulated MAPK/NF-?B pathway leading to COX-2/PGE2/IL-8 activation in thermal inhalation injury, and demonstrated therapeutic potential of curcumin for alleviating heat-induced pulmonary inflammation.
Project description:BACKGROUND:Yan Hou Qing (YHQ) is a Chinese medicinal formula designed to alleviate sore throat symptoms, but underlying mechanism of YHQ treatment for pharyngitis is poorly defined up to now. METHODS:In this study, the modulation of YHQ on pharyngitis is investigated in ammonia-induced acute pharyngitis rat models. After treatment with YHQ or dexamethasone respectively for five consecutive days, all rats were sacrificed for biomolecular and histopathologic study. Protein expressions of MAPKs, NF-?B, COX-2 and 5-LOX in pharyngitis tissue were evaluated by western blot analysis and the levels of TNF-?, IL-6, prostaglandin (PG) E2, leukotrienes (LT)-B4 and LT-D4 in pharyngeal tissue were measured via ELISA assay. Evans blue (EB) dye exudation test was performed parallelly to assess the integrity of pharyngeal tissue. RESULTS:Compared with normal control group, EB dye exudation, and inflammatory cytokines in the model group were significantly increased, and the pharynx tissue was obviously infiltrated by inflammatory cells. YHQ treatment improved the inflammatory infiltrate in pharyngeal tissue, and reduced EB dye exudation in AP rat models. The up-regulated TNF-? and IL-6 in pharyngeal tissue of AP were significantly reduced by YHQ through inhibition of phosphorylation of p38, Erk and NF-?B. YHQ treatment also reversed the increased level of PGE2 through down-regulation of COX-2. CONCLUSIONS:YHQ formula attenuated the pharyngitis related symptoms via suppression of COX-2 and phosphorylation of p38, Erk and NF-?B (p65).
Project description:Nitric oxide and prostaglandin E2 (PGE2play pivotal roles in both the pathogenesis of osteoarthritis and catabolic processes in articular cartilage. These mediators are influenced by both IL-1beta and mechanical loading, and involve alterations in the inducible nitric oxide synthase (iNOS) and cyclo-oxygenase (COX)-2 enzymes. To identify the specific interactions that are activated by both types of stimuli, we examined the effects of dynamic compression on levels of expression of iNOS and COX-2 and involvement of the p38 mitogen-activated protein kinase (MAPK) pathway.Chondrocyte/agarose constructs were cultured under free-swelling conditions with or without IL-1beta and/or SB203580 (inhibitor of p38 MAPK) for up to 48 hours. Using a fully characterized bioreactor system, constructs were subjected to dynamic compression for 6, 12 and 48 hours under similar treatments. The activation or inhibition of p38 MAPK by IL-1beta and/or SB203580 was analyzed by western blotting. iNOS, COX-2, aggrecan and collagen type II signals were assessed utilizing real-time quantitative PCR coupled with molecular beacons. Release of nitrite and PGE2 was quantified using biochemical assays. Two-way analysis of variance and the post hoc Bonferroni-corrected t-test were used to examine data.IL-1beta activated the phosphorylation of p38 MAPK and this effect was abolished by SB203580. IL-1beta induced a transient increase in iNOS expression and stimulated the production of nitrite release. Stimulation by either dynamic compression or SB203580 in isolation reduced the IL-1beta induced iNOS expression and nitrite production. However, co-stimulation with both dynamic compression and SB203580 inhibited the expression levels of iNOS and production of nitrite induced by the cytokine. IL-1beta induced a transient increase in COX-2 expression and stimulated the cumulative production of PGE2 release. These effects were inhibited by dynamic compression or SB203580. Co-stimulation with both dynamic compression and SB203580 restored cytokine-induced inhibition of aggrecan expression. This is in contrast to collagen type II, in which we observed no response with the cytokine and/or SB203580.These data suggest that dynamic compression directly influences the expression levels of iNOS and COX-2. These molecules are current targets for pharmacological intervention, raising the possibility for integrated pharmacological and biophysical therapies for the treatment of cartilage joint disorders.
Project description:Cyclooxygenase-2 (COX-2) and interleukin-8 (IL-8) are two important inflammatory mediators in ovulation. Ghrelin may modulate inflammatory signaling via growth hormone secretagogue receptors. We investigated the role of ghrelin in KGN human ovarian granulosa cells using protein kinase C (PKC) activator phorbol 12, 13-didecanoate (PDD) and synthetic ghrelin analog growth hormone releasing peptide-2 (GHRP-2). GHRP-2 attenuated PDD-induced expression of protein and mRNA, the promoter activity of COX-2 and IL-8 genes, and the secretion of prostaglandin E2 (PGE?) and IL-8. GHRP-2 promoted the degradation of PDD-induced COX-2 and IL-8 proteins with the involvement of proteasomal and lysosomal pathways. PDD-mediated COX-2 production acts via the p38, c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-?B) pathways; PDD-mediated IL-8 production acts via the p38, JNK and ERK pathways. GHRP-2 reduced the PDD-induced phosphorylation of p38 and JNK and activator protein 1 (AP-1) reporter activation and PDD-induced NF-?B nuclear translocation and reporter activation. The inhibitors of mitogen-activated protein kinase phosphatase-1 (MKP-1) and protein phosphatase 2 (PP2A) reduced the inhibitory effect of GHRP-2 on PDD-induced COX-2 and IL-8 expression. Our findings demonstrate an anti-inflammatory role for ghrelin (GHRP-2) in PKC-mediated inflammation of granulosa cells, at least in part, due to its inhibitory effect on PKC-induced activation of p38, JNK and NF-?B, possibly by targeting to MKP-1 and PP2A.
Project description:BACKGROUND: Recent studies have revealed that cyclooxygenase-2 (COX-2) expression is down-regulated in aspirin-induced asthma (AIA). Various signal pathways (MAPKs, NF-?B and C/EBP) are involved in COX-2 regulation. OBJECTIVE: To investigate the regulation of COX-2 expression through MAP-kinase pathway activation and nuclear factor translocation in aspirin-induced asthma (AIA). METHODS: Fibroblasts were isolated from specimens of nasal mucosa (NM, N?=?5) and nasal polyps (NP, N?=?5). After IL-1? (1 ng/ml) incubation, COX-2 and phosphorylated forms of ERK, JNK and p38 MAPK were measured by Western blot. MAPK's role in IL-1?-induced COX-2 expression was assessed by treating cells with ERK (PD98059), JNK (SP600125) and p38 MAPK (SB203580) inhibitors (0.1-10 µM) prior to IL-1? exposure. NF-?B and C/EBP nuclear translocation was measured by Western blot and TransAM® after IL-1? (10 ng/ml) exposure. RESULTS: No differences were observed in the MAPK phosphorylation time-course between NM and NP-AIA fibroblasts. The p38 MAPK inhibitor at 10 µM significantly reduced IL-1?-induced COX-2 expression in NM fibroblasts (85%). In NP-AIA fibroblasts the COX-2 inhibition (65%) at 1 and 10 µM was not statistically significant compared to non-treated cells. ERK and JNK inhibitors had no significant effect in either the NM or NP-AIA cultures. The effect of IL-1? on NF-?B and C/EBP subunits' nuclear translocation was similar between NM and NP-AIA fibroblasts. CONCLUSIONS: These results suggest that p38 MAPK is the only MAPK involved in IL-1?-induced COX-2 expression. NM and NP-AIA fibroblasts have similar MAPK phosphorylation dynamics and nuclear factor translocation (NF-?B and C/EBP). COX-2 downregulation observed in AIA patients appears not to be caused by differences in MAPK dynamics or transcription factor translocation.