D-dopachrome tautomerase activates COX2/PGE2 pathway of astrocytes to mediate inflammation following spinal cord injury.

BACKGROUND: Astrocytes are the predominant glial cell type in the central nervous system (CNS) that can secrete various cytokines and chemokines mediating neuropathology in response to danger signals. D-dopachrome tautomerase (D-DT), a newly described cytokine and a close homolog of macrophage migration inhibitory factor (MIF) protein, has been revealed to share an overlapping function with MIF in some ways. However, its cellular distribution pattern and mediated astrocyte neuropathological function in the CNS remain unclear. METHODS: A contusion model of the rat spinal cord was established. The protein levels of D-DT and PGE2 synthesis-related proteinase were assayed by Western blot and immunohistochemistry. Primary astrocytes were stimulated by different concentrations of D-DT in the presence or absence of various inhibitors to examine relevant signal pathways. The post-injury locomotor functions were assessed using the Basso, Beattie, and Bresnahan (BBB) locomotor scale. RESULTS: D-DT was inducibly expressed within astrocytes and neurons, rather than in microglia following spinal cord contusion. D-DT was able to activate the COX2/PGE2 signal pathway of astrocytes through CD74 receptor, and the intracellular activation of mitogen-activated protein kinases (MAPKs) was involved in the regulation of D-DT action. The selective inhibitor of D-DT was efficient in attenuating D-DT-induced astrocyte production of PGE2 following spinal cord injury, which contributed to the improvement of locomotor functions. CONCLUSION: Collectively, these data reveal a novel inflammatory activator of astrocytes following spinal cord injury, which might be beneficial for the development of anti-inflammation drug in neuropathological CNS.

Novel Role of Macrophage Migration Inhibitory Factor in Upstream Control of the Unfolded Protein Response After Ethanol Feeding in Mice.

BACKGROUND: Macrophage migration inhibitory factor (MIF), a pluripotent immune regulator, is an emerging mediator in alcohol-related liver disease (ALD). MIF is associated with ALD progression through its chemokine- and cytokine-like activities. METHODS: Mechanistic studies into the role of MIF in ethanol (EtOH)-induced liver injury were performed in Mif-/- mice and in C57BL/6J mice treated with a small-molecule MIF antagonist, MIF098, after Gao-Binge (acute-on-chronic) EtOH feeding, an EtOH feeding protocol associated with hepatic neutrophilia and induction of the unfolded protein response (UPR). RESULTS: The MIF axis, for example, MIF and MIF receptors invariant polypeptide of major histocompatibility complex, class II antigen-associated (CD74), CXCR2, CXCR4, and CXCR7, was enhanced in the livers of alcoholic hepatitis (AH) patients as compared to healthy controls. Mif-/- mice were protected from hepatocellular injury after Gao-Binge feeding, independent of neutrophilia and inflammation, but were associated with the UPR. Interestingly, the UPR signature in AH patients and in mice following Gao-Binge feeding was biased toward cell death with increased expression of pro-cell death CCAAT-enhancer-binding protein homologous protein (CHOP) and decreased prosurvival GRP78. The UPR and liver injury 6 hours after binge were prevented both in Mif-/- mice and in MIF098-treated mice. However, both MIF interventions led to increased liver injury and exacerbated the hepatic UPR 9 hours after binge. Induction of upstream UPR signaling and expression of CHOP protein by thapsigargin in alpha mouse liver 12 hepatocytes were blunted by coexposure to MIF098, directly connecting MIF to UPR in hepatocytes. CONCLUSIONS: The current study revealed that, in addition to its cytokine/chemokine functions, MIF is an upstream regulator of UPR in response to EtOH feeding in mice. Importantly, both MIF and UPR can either protect or contribute to liver injury, dependent upon the stage or severity of EtOH-induced liver injury.

The involvement of prostaglandin E2 in interleukin-1ß evoked anorexia is strain dependent.

From experiments in mice in which the prostaglandin E2 (PGE2) synthesizing enzyme mPGES-1 was genetically deleted, as well as from experiments in which PGE2 was injected directly into the brain, PGE2 has been implicated as a mediator of inflammatory induced anorexia. Here we aimed at examining which PGE2 receptor (EP1-4) that was critical for the anorexic response to peripherally injected interleukin-1ß (IL-1ß). However, deletion of neither EP receptor in mice, either globally (for EP1, EP2, and EP3) or selectively in the nervous system (EP4), had any effect on the IL-1ß induced anorexia. Because these mice were all on a C57BL/6 background, whereas previous observations demonstrating a role for induced PGE2 in IL-1ß evoked anorexia had been carried out on mice on a DBA/1 background, we examined the anorexic response to IL-1ß in mice with deletion of mPGES-1 on a C57BL/6 background and a DBA/1 background, respectively. We confirmed previous findings that mPGES-1 knock-out mice on a DBA/1 background displayed attenuated anorexia to IL-1ß; however, mice on a C57BL/6 background showed the same profound anorexia as wild type mice when carrying deletion of mPGES-1, while displaying almost normal food intake after pretreatment with a cyclooxygenase-2 inhibitor. We conclude that the involvement of induced PGE2 in IL-1ß evoked anorexia is strain dependent and we suggest that different routes that probably involve distinct prostanoids exist by which inflammatory stimuli may evoke an anorexic response and that these routes may be of different importance in different strains of mice.

Artesunate inhibits type I interferon-induced production of macrophage migration inhibitory factor in patients with systemic lupus erythematosus.

OBJECTIVE: Macrophage migration inhibitory factor (MIF) is a key regulator of both atherosclerosis and systemic lupus erythematosus (SLE), yet factors leading to its overproduction remain unclear. To explore regulation of MIF in SLE, we studied effects and potential mechanisms of type I interferon (IFN) and artesunate (ART), an antimalarial agent extracted from Chinese herbs, on levels of MIF. METHODS: Serum and peripheral blood cells from SLE patients and healthy controls were measured for MIF levels by ELISA and type I IFN-inducible gene expressions by real-time PCR, respectively, and assessed for associations by Spearman correlation. ART was added to human umbilical vein endothelial cell (HUVEC) cultures with or without prior IFNα-1b stimulation and to SLE peripheral blood mononuclear cell (PBMC) cultures. Protein levels of STATs and phosphorylated (p-) STATs in HUVECs were determined by Western blotting. RESULTS: Serum MIF levels were elevated in SLE patients and positively associated with disease activity (r = 0.86, p < 0.0001), accumulated damage (r = 0.34, p < 0.05), and IFN scores in SLE PBMCs (r = 0.74, p = 0.0002). The addition of IFNα-1b promoted MIF production in a time- and dose-dependent manner in HUVEC cultures. ART could inhibit expressions of IFN-inducible genes (LY6E and ISG15) in both HUVEC and SLE PBMC cultures, and suppress MIF production and over-expression of p-STAT1, but not p-STAT3 or STAT5, induced by IFNα-1b stimulation. IFNγ-induced expression of p-STAT1 in HUVECs was not inhibited by ART. CONCLUSION: MIF could be regulated by type I IFN in SLE patients. ART counteracts the effect of IFNα to inhibit MIF production by blocking STAT1 phosphorylation and thus may have therapeutic potential for SLE-associated atherosclerosis.

Targeting MIF in Cancer: Therapeutic Strategies, Current Developments, and Future Opportunities.

Strong evidence has been presented linking chronic inflammation to the onset and pathogenesis of cancer. The multifunctional pro-inflammatory protein macrophage migration inhibitory factor (MIF) occupies a central role in the inflammatory pathway and has been implicated in the tumorigenesis, angiogenesis, and metastasis of many cancer phenotypes. This review highlights the current state of the art, which presents MIF, and the second member of the MIF structural superfamily, D-DT (MIF2), as significant mediators in the inflammatory-cancer axis. Although the mechanism by which MIF asserts its biological activity has yet to be fully understood, it has become clear in recent years that for certain phenotypes of cancer, MIF represents a valid therapeutic target. Current research efforts have focused on small molecule approaches that target MIF's unique tautomerase active site and neutralization of MIF with anti-MIF antibodies. These approaches have yielded promising results in a number of preclinical murine cancer models and have helped to increase our understanding of MIF biological activity. More recently, MIF's involvement in a number of key protein-protein interactions, such as with CD74 and HSP90, has been highlighted and provides a novel platform for the development of anti-MIF chemotherapeutic strategies in the future.

Expression profile of macrophage migration-inhibitory factor in human gingiva and reconstituted human gingival epithelia stimulated by Porphyromonas gingivalis lipopolysaccharide.

BACKGROUND AND OBJECTIVE: Macrophage migration-inhibitory factor (MIF) plays crucial roles in the recruitment and activation of macrophages as well as in helping to kill bacteria. This study investigated the expression profile of MIF in human gingiva under different periodontal conditions and its expression patterns induced by Porphyromonas gingivalis lipopolysaccharide (LPS) in gingival epithelia. MATERIAL AND METHODS: Gingival tissue samples were collected from deep pockets and clinically healthy sites of 22 nonsmoking subjects with chronic periodontitis. The expression of MIF mRNA and protein was evaluated using real-time PCR and immunohistochemistry, respectively. The in vitro study analyzed the effects of P. gingivalis LPS on the expression of MIF in a reconstituted human gingival epithelia (RHGE) model. RESULTS: In gingival epithelia, MIF protein was diffusely expressed from the basal layer to the granular and spinous layers; whereas, in the underlying connective tissues, MIF was observed around the dilated blood vessels in the deep-pocket tissues. A significantly lower level of expression of MIF mRNA and an increased level of expression of MIF protein were found in deep-pocket tissues compared with clinically healthy tissues. Expression of MIF mRNA in the RHGE model was significantly down-regulated by P. gingivalis LPS. CONCLUSION: The present study suggests that MIF expression may be related to periodontal conditions and that its expression profile could be modulated by P. gingivalis LPS. MIF may play a role in periodontal pathogenesis.

Targeted lipidomics reveals mPGES-1-PGE2 as a therapeutic target for multiple sclerosis.

The arachidonic acid (AA) cascade produces eicosanoids, such as prostaglandins (PGs), that regulate physiological and pathological functions. Although various nonsteroidal anti-inflammatory drugs have been developed, blocking upstream components (cyclooxygenase-1 and -2) of the AA cascade leads to severe side effects, including gastrointestinal ulcers and cardiovascular events, respectively, due to the complexity of the AA cascade. Here, using an AA cascade-targeted lipidomics approach, we report that microsomal PGE synthase 1 (mPGES-1) plays a key role in experimental autoimmune encephalomyelitis (EAE). Eicosanoids (mainly PGD(2)) are produced constitutively in the spinal cord of naive mice. However, in EAE lesions, the PGE(2) pathway is favored and the PGD(2), PGI(2), and 5-lipoxygenase pathways are attenuated. Furthermore, mPGES-1(-/-) mice showed less severe symptoms of EAE and lower production of IL-17 and IFN-gamma than mPGES-1(+/+) mice. Expression of PGE(2) receptors (EP1, EP2, and EP4) was elevated in EAE lesions and correlated with clinical symptoms. Immunohistochemistry on central nervous systems of EAE mice and multiple sclerosis (MS) patients revealed overt expression of mPGES-1 protein in microglia/macrophages. Thus, the mPGES-1-PGE(2)-EPs axis of the AA cascade may exacerbate EAE pathology. Our findings have important implications for the design of therapies for MS.

Effects of flavonoids on prostaglandin E2 production and on COX-2 and mPGES-1 expressions in activated macrophages.

Prostaglandin E2 (PGE2) has a central role in inflammation and both cyclooxygenase-2 (COX-2) and prostaglandin E synthases are critical enzymes in its synthesis. In inflammation, bacterial products and cytokines enhance the expression of COX-2 and inducible microsomal prostaglandin E synthase-1 (mPGES-1) which are functionally coupled to result in increased PGE2 formation in macrophages and tissue cells. In the present study, we systematically investigated the effects of 26 naturally occurring flavonoids on PGE2 production and on COX-2 and mPGES-1 expression in activated macrophages. Twelve flavonoids, i.e., flavone, luteolin-7-glucoside, kaempferol, isorhamnetin, morin, quercetin, naringenin, taxifolin, pelargonidin, daidzein, genistein, and genistin effectively inhibited lipopolysaccharide (LPS)-induced PGE2 production. Four flavonoids (flavone, isorhamnetin, daidzein, and genistein) inhibited significantly LPS-induced COX-2 expression, while mPGES-1 expression was downregulated by kaempferol and isorhamnetin. The present study characterizes the effects of flavonoids on PGE2 production and on COX-2 and mPGES-1 expression in activated macrophages. The results add to our knowledge of the anti-inflammatory actions of flavonoids and introduce kaempferol and isorhamnetin as compounds capable of downregulating the expression of mPGES-1.

Thrombosis preventive potential of chicory coffee consumption: a clinical study.

The protective effects of plant polyphenol intake on cardiovascular morbidity and mortality are widely acknowledged. Caffeine-free chicory coffee is a rich source of plant phenolics, including caffeic acid, which inhibits in vitro platelet aggregation, and also phenylpyruvate tautomerase enzymatic activity of the proinflammatory cytokine, macrophage migration inhibitory factor (MIF). To assess whether chicory coffee consumption might confer cardiovascular benefits a clinical intervention study was performed with 27 healthy volunteers, who consumed 300 mL chicory coffee every day for 1 week. The dietary intervention produced variable effects on platelet aggregation, depending on the inducer used for the aggregation test. Whole blood and plasma viscosity were both significantly decreased, along with serum MIF levels, after 1 week of chicory coffee consumption. Moreover, significant improvements were seen in red blood cell deformability. No changes in hematocrit, fibrinogen level or red blood cell counts were detected. The full spectrum of these effects is unlikely to be attributable to a single compound present in chicory coffee, nevertheless, the phenolics, including caffeic acid, are expected to play a substantial role. In conclusion, our study offers an encouraging starting-point to delineate the antithrombotic and antiinflammatory effects of phenolic compounds found in chicory coffee.

In search of pulmonary hypertension treatments: Effect of 17ß-estradiol on PGI2 pathway in human pulmonary artery.

INTRODUCTION: Prostacyclin (PGI2) is synthetized by PGI2 synthase (PGIS) and induces vasorelaxation via activation of cyclic AMP (cAMP) generating IP-receptor. Several components of the PGI2 signaling pathway are reduced in patients with pulmonary hypertension (PH). AIM: To study the effect of 17ß-estradiol (E2) on the PGI2 signaling pathway in human pulmonary arteries (HPA) and in their smooth muscle cells (hPASMC) derived from Group-3 PH and non-PH patients. METHODS: Following E2-treatments of isolated HPA and cultured hPASMC, we measured: 6-keto-Prostaglandin F1α (PGI2 stable metabolite) by ELISA, PGIS and IP protein levels by Western blot and HPA vasorelaxations with an organ bath system. RESULTS: Incubation with E2 (24/48 h, doses ≥ 10 nM) significantly increased the expression of PGIS in hPASMC derived from both PH (65-98%) and non-PH (21-33%) patients, whereas incubation with E2 (2 h, 0.1 and 1 µM) increased 6-keto-PGF1α production in HPA from Group-3 PH patients only, and did not affect 6-keto-PGF1α production in hPASMC from either non-PH or Group-3 PH patients. Increases in IP receptor expression were observed following 10 mM E2-treatment of hPASMC from non-PH (33% after 48 h) and Group-3 PH (23% after 24 h) patient lungs. Finally, preincubation with 100 nM E2 significantly increased arachidonic acid-induced vasorelaxation of HPA from non-PH patient lungs but not of HPA from Group-3 PH patient lungs. CONCLUSION: E2-treatment may help to restore the PGI2-pathway in Group-3 PH.

Effect of sulfur mustard on melanogenesis in vitro.

The chemical warfare agent sulfur mustard (SM) affects all cells in the epidermis including melanocytes which are responsible for melanin synthesis. After exposure to SM, pigment abnormalities like hypo- and hyperpigmentation can occur. The underlying molecular pathomechanisms of SM exposure on human melanogenesis have not been elucidated so far. In our study, we investigated the effect of SM on human melanocytes and melanogenesis. Normal human epidermal melanocytes (NHEM) were used as in vitro model and they were exposed to different concentrations of SM (4.5 µM-100 µM). Melanin production was analyzed by absorption measurements at 405 nm. In addition, quantitative real-time PCR (qPCR) and Western blot experiments were performed to determine the expression of essential melanogenesis-related proteins including tyrosinase (TYR), tyrosinase-related protein (TRP) 1 and 2 and microphthalmia transcription factor (MITF). Our findings demonstrated that exposure to low SM concentrations increased melanin synthesis accompanied with an increase in protein expression. In contrast, high SM concentrations led to decreased melanin content and a downregulation in expression of all investigated melanogenesis-associated proteins. We concluded that low SM concentrations may cause hyperpigmentation while high SM concentrations decreased melanin content which may explain hypopigmented skin areas in SM exposed patients.

Tosylcyclonovobiocic acids promote cleavage of the hsp90-associated cochaperone p23.

The cochaperone p23 is required for the chaperoning cycle of hsp90 and to enhance the maturation of several client proteins. Tosylcyclonovobiocic acids (4TCNA and 7TCNA) are potent analogs of novobiocin and induce cell cycle arrest, apoptosis and degradation of hsp90 client proteins in a panel of cancer cells. In this study, Western blotting shows that 4TCNA and 7TCNA triggered processing of the hsp90 cochaperone p23 in a dose-dependent manner. Small interfering RNA (siRNA)-mediated reduction of p23 expression in MCF-7 breast cancer cells did not block 4TCNA-induced caspase activation as assessed by the cleavage of PARP. This result indicates that 4TCNA-mediated cell death is a p23-independent process. In HT29 colon cancer cells, 4TCNA and 7TCNA up-regulated GRP78 and GRP94 supporting involvement of ER stress in apoptosis.

Evidence that PAR2-triggered prostaglandin E2 (PGE2) formation involves the ERK-cytosolic phospholipase A2-COX-1-microsomal PGE synthase-1 cascade in human lung epithelial cells.

We investigated possible involvement of three isozymes of prostaglandin E synthase (PGES), microsomal PGES-1 (mPGES-1), mPGES-2 and cytosolic PGES (cPGES) in COX-2-dependent prostaglandin E(2) (PGE(2)) formation following proteinase-activated receptor-2 (PAR2) stimulation in human lung epithelial cells. PAR2 stimulation up-regulated mPGES-1 as well as COX-2, but not mPGES-2 or cPGES, leading to PGE(2) formation. The PAR2-triggered up-regulation of mPGES-1 was suppressed by inhibitors of COX-1, cytosolic phospholipase A(2) (cPLA(2)) and MEK, but not COX-2. Finally, a selective inhibitor of mPGES-1 strongly suppressed the PAR2-evoked PGE(2) formation. PAR2 thus appears to trigger specific up-regulation of mPGES-1 that is dependent on prostanoids formed via the MEK/ERK/cPLA(2)/COX-1 pathway, being critical for PGE(2) formation.

Role of macrophage migration inhibitory factor in head and neck cancer and novel therapeutic targets: A systematic review.

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine involved in systemic, autoimmune, and inflammatory diseases, such as obesity, rheumatoid arthritis, and systemic lupus erythematosus. For the 2 past decades, MIF has been reported to participate in carcinogenesis, disease prognosis, tumor cell proliferation, invasion, and tumor-induced angiogenesis in many cancers. The purpose of this article is to review published experimental and clinical data for MIF and its involvement in upper aerodigestive tract cancers. Based on the current literature, we propose a biomolecular model describing the mechanisms underlying the involvement of MIF in the initiation, progression, apoptosis, and proliferation of head and neck tumor cells. In reference to this model, potential therapeutic approaches based on the use of MIF antagonists and neutralizing antibodies are described. It is concluded that MIF is a promising target for future therapeutic strategies, both with and without chemoradiation strategies.

Inducible prostaglandin E synthase is overexpressed in non-small cell lung cancer.

An inducible microsomal form of human prostaglandin E synthase (mPGES) was recently identified. This enzyme converts the cyclooxygenase (COX) product, prostaglandin (PG) H2, to PGE2, a prostanoid that has been implicated in carcinogenesis. Increased amounts of PGE2 are detected in many types of cancer, but the underlying mechanism is not fully understood. Hence, we compared amounts of mPGES in 19 paired samples (tumor and adjacent normal tissue) of non-small cell lung cancer (NSCLC). By immunoblot analysis, mPGES was overexpressed in about 80% of NSCLCs. Immunohistochemistry localized the expression of mPGES to neoplastic epithelial cells. COX-2 was also commonly up-regulated in these tumors; marked differences in the extent of up-regulation of mPGES and COX-2 were observed in individual tumors. Cell culture was used to define the underlying mechanism(s) that accounts for up-regulation of mPGES in NSCLC. As reported previously for COX-2, levels of mPGES mRNA and protein were increased in NSCLC cell lines containing mutant Ras as compared with a nontumorigenic bronchial epithelial cell line. Nuclear run-offs revealed increased rates of mPGES transcription in the transformed cell lines. Overexpression of Ras caused a severalfold increase in mPGES promoter activity in nontransformed cells. Tumor necrosis factor-alpha induced mPGES and COX-2 in NSCLC cell lines but had no effect on the expression of either enzyme in a nontumorigenic bronchial epithelial cell line. Consistent with prior observations for COX-2, these data suggest that both cellular transformation and cytokines contribute to the up-regulation of mPGES in NSCLC.

Specific regulation of lipocalin-type prostaglandin D synthase in mouse heart by estrogen receptor beta.

Estrogens have important physiological roles in the cardiovascular system. We use DNA microarray technology to study the molecular mechanism of estrogen action in the heart and to identify novel estrogen-regulated genes. In this investigation we identify genes that are regulated by chronic estrogen treatment of mouse heart. We present our detailed characterization of one of these genes, lipocalin-type prostaglandin D synthase (L-PGDS). Northern and Western blot analysis revealed that L-PGDS was induced both by acute and chronic estrogen treatment. Northern blot analysis, using estrogen receptor (ER)-disrupted mice, suggests that L-PGDS is specifically induced by ERbeta in vivo. In further support of ERbeta-selective regulation, we identify a functional estrogen-responsive element in the L-PGDS promoter, the activity of which is up-regulated by ERbeta, but not by ERalpha. We demonstrate that a one-nucleotide change (A to C) in the L-PGDS estrogen-responsive element affects receptor selectivity.

l-tyrosine induces melanocyte differentiation in novel pink-eyed dilution castaneus mouse mutant showing age-related pigmentation.

BACKGROUND: The mouse pink-eyed dilution (oculocutaneous albinism II; p/Oca2(p)) locus is known to control tyrosinase activity, melanin content, and melanosome development in melanocytes. Pink-eyed dilution castaneus (p(cas)/Oca2(p-cas)) is a novel mutant allele on mouse chromosome 7 that arose spontaneously in Indonesian wild mice, Mus musculus castaneus. Mice homozygous for Oca2(p-cas) usually exhibit pink eyes and beige-colored coat on nonagouti C57BL/6 (B6) background. Recently, a novel spontaneous mutation occurred in the progeny between this mutant and B6 mice. The eyes of this novel mutant progressively become black from pink and the coat becomes dark gray from beige with aging. OBJECTIVE: The aim of this study is to clarify whatever differences exist in melanocyte proliferation and differentiation between the ordinary (pink-eyed) and novel (black-eyed) mutant using serum-free primary culture system. METHODS: The characteristics of melanocyte proliferation and differentiation were investigated by serum-free primary culture system using melanocyte-proliferation medium (MDMD). RESULTS: The proliferation of melanoblasts in MDMD did not differ between the two mice. However, when the epidermal cell suspensions were cultured with MDMD supplemented with l-tyrosine (Tyr), the differentiation of black-eyed melanocytes was greatly induced in a concentration-dependent manner compared with pink-eyed melanocytes. Immunocytochemistry demonstrated that the expression of tyrosinase and tyrosinase-related protein-1 (Tyrp1) was greatly induced or stimulated both in pink-eyed and black-eyed melanocytes, whereas the expression of microphthalmia-associated transcription factor (Mitf) was stimulated only in black-eyed melanocytes. CONCLUSION: These results suggest that the age-related coat darkening in black-eyed mutant may be caused by the increased ability of melanocyte differentiation dependent on l-Tyr through the upregulation of tyrosinase, Tyrp1, and Mitf. This mutant mouse may be useful for animal model to clarify the mechanisms of age-related pigmentation in human skin, such as melasma and solar lentigines.

Endogenous prostaglandin D2 synthesis reduces an increase in plasminogen activator inhibitor-1 following interleukin stimulation in bovine endothelial cells.

OBJECTIVE: We examined the role of prostaglandin D2 (PGD2) in the formation of plasminogen activator inhibitor (PAI)-1 following interleukin-1beta (IL-1) stimulation in bovine endothelial cells (EC) transfected with lipocaline-type PGD2 synthase (L-PGDS) genes. DESIGN AND METHODS: EC were isolated from bovine thoracic aorta and incubated with 20 U/ml IL-1 and various concentrations of authentic PGD2. The isolated EC were also transfected with L-PGDS genes by electroporation. The L-PGDS-transfected EC were used to investigate the role of endogenous PGD2 in IL-1 stimulated PAI-1 biosynthesis. We also used an anti-PGD2 antibody to examine whether an intracrine mechanism was involved in PAI-1 production. PGD2 and PAI-1 levels were determined by radio- and enzyme-immunoassay, respectively. PAI-1 mRNA was assessed by reverse transcription-polymerase chain reaction. RESULT: IL-1 stimulated PAI-1 production by EC was dose-dependently inhibited by authentic PGD2 at concentrations greater than 10-6 mol/l. L-PGDS gene-transfected EC produced more PGD2 than EC transfected with the reporter gene alone. IL-1 induced increases in PAI-1 production in EC transfected with reporter genes alone. However, this effect was significantly attenuated in the case of IL-1 stimulation of EC transfected with L-PGDS genes, and accompanied by an apparent suppression of PAI-1 mRNA expression. The effects of PGD2 on PAI-I formation were reversed to the basal levels by the inhibition of synthesis of endogenous PGD2. Neutralization of extracellular PGD2 by anti-PGD2 antibody influenced neither PAI-1 mRNA expression nor PAI-1 biosynthesis. CONCLUSION: EC transfected with L-PGDS genes increased PGD2 synthesis. This was associated with attenuation of both PAI-1 formation and PAI-1 mRNA expression. It is suggested that endogenous PGD2 decreases PAI-1 synthesis and PAI-1 mRNA expression, probably through an intracrine mechanism.

[New insights on the molecular mechanisms of type-1 angiotensin II receptor blockers and their contribution to atherosclerotic plaque stabilization]. / Recenti vedute sul meccanismo molecolare d'azione dei bloccanti recettoriali dell'angiotensina II di tipo 1 e sul loro contributo alla stabilizzazione della placca aterosclerotica.

Clinical trials have demonstrated that agents inhibiting the angiotensin II pathway confer benefit beyond the reduction of blood pressure alone. However, the molecular mechanism underlying this effect has yet to be investigated. Recently, we have demonstrated enhanced expression of inducible COX and PGE synthase (COX-2/mPGES-1) in human symptomatic plaques, and provided evidence that it is associated with plaque rupture induced by metalloproteinases (MMPs), proteolytic enzymes of matrix structural components. In a recent study, we hypothesized that angiotensin II could promote plaque instability through induction of the COX-2/mPGES-1 pathway. We analyzed atherosclerotic plaques from symptomatic patients who were randomized to treatment with irbesartan (300 mg/die) or chlortalidone (50 mg/die) for 4 months before endarterectomy. We found that plaques from the irbesartan group had reduced inflammatory infiltration, less immunoreactivity for COX-2/mPGES-1 and MMPs, reduced gelatinolytic activity and increased collagen content. It is worth noting that COX-2/mPGES-1 inhibition was observed after incubation in vitro with irbesartan but not with the selective AT2 blockade PD123,319. These findings suggest that AT1 receptor blockers could represent a novel form of therapy for plaque stabilization in patients with atherosclerotic disease.

Biocompatibility of new calcium aluminate cement: tissue reaction and expression of inflammatory mediators and cytokines.

INTRODUCTION: The aim of this study was to evaluate the biocompatibility of a new calcium aluminate cement (EndoBinder) in subcutaneous tissue of rats in comparison with mineral trioxide aggregate and calcium hydroxide hard-setting cement. METHODS: Polyethylene tubes (1.5 × 10 mm) containing the dental cements were implanted into dorsal subcutaneous tissue of 30 rats. After experimental periods of 7, 30, and 90 days, biopsies were performed for tissue response analysis under optical light microscope. The mRNA extraction was performed for molecular evaluation of the inflammatory process in the peri-implant tissue, which was submitted to quantitative real-time polymerase chain reaction analysis for inflammatory mediators and cytokines TNF-α, Ptges2, Il-1ß, Il-4, and Il-10. RESULTS: On the basis of the score used to grade the tissue reaction (0-3), EndoBinder (0) presented no inflammatory reaction after the 90-day period, a similar result to mineral trioxide aggregate and calcium hydroxide. The thickness of inflammatory capsules (µm) also presented significant decrease during the course of periods (P < .05). As regards expression of inflammatory mediators, Ptges2 and Il-10 were detected only at 7 and 30 days, with no statistically significant difference among the experimental groups (P > .05). CONCLUSIONS: EndoBinder induced limited inflammatory reaction. It was considered biocompatible when tested in subcutaneous tissue of rats.