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Prostaglandin E receptor EP4, a G-protein-coupled receptor, is involved in disorders such as cancer and autoimmune disease. Here, we report the crystal structure of human EP4 in complex with its antagonist ONO-AE3-208 and an inhibitory antibody at 3.2 Å resolution. The structure reveals that the extracellular surface is occluded by the extracellular loops and that the antagonist lies at the interface with the lipid bilayer, proximal to the highly conserved Arg316 residue in the seventh transmembrane domain. Functional and docking studies demonstrate that the natural agonist PGE2binds in a similar manner. This structural information also provides insight into the ligand entry pathway from the membrane bilayer to the EP4 binding pocket. Furthermore, the structure reveals that the antibody allosterically affects the ligand binding of EP4. These results should facilitate the design of new therapeutic drugs targeting both orthosteric and allosteric sites in this receptor family.

Macrolide antibiotics are broadly used for the treatment of various microbial infections. However, they are also known to have multiple biologic effects, such as alteration of inflammatory factors and matrix metalloproteinases (MMPs). Because of controversial results in clinical trials, the effects of macrolides on cardiovascular diseases are still to be elucidated. It has been reported that MMP activity is upregulated in various cardiovascular diseases, such as myocarditis, cardiac transplant rejection and myocardial infarction. However, little is known about the effects of macrolides on cardiovascular diseases. We have reported that clarithromycin suppressed the development of myocarditis, cardiac rejection and myocardial ischemia using animal models. In this article, we reviewed the roles of MMPs in cardiovascular diseases and the effects of macrolides on the prevention of adverse tissue remodeling.

Telmisartan is an angiotensin II receptor blocker, which acts as a partial agonist of peroxisome proliferator activator receptor- (PPAR-). Because PPAR- initiates a variety of antiinflammatory responses, the effect on myocardial ischemia is to be elucidated.

Prostaglandins (PG) and their specific receptors for E type PG (EP) play an important role in inflammatory diseases. Although myocarditis results in inflammation of the heart, roles of PG and EP in its pathophysiology is still controversial. To clarify the role of PG and EP on the progression of myocarditis, we used an experimental autoimmune myocarditis model. A selective EP4 (EP4RAG) agonist was administered into both early (Day 0 to 21) and late (Day 14 to 21) -treated groups and the animals were killed on Day 21. We found that improved cardiac function was detected in the EP4RAG-treated groups in comparison to the untreated group. The infiltration area ratio in the early-treated (16.6% ± 4.6%) group was lower than those in the untreated group (32.1% ± 3.5%) (P< 0.05). The fibrosis area ratios in the early-treated (19.2% ± 6.3%) and the late-treated groups (24.4% ± 5.1%) were lower than those in the untreated group (37.4% ± 2.6%), respectively (P< 0.05). Moreover, we found that EP4RAG decreased T-cell proliferation and monocyte chemoattractant protein-1 production in vitro. We concluded that a selective EP4 agonist inactivates T-cells, which turns out to moderate the progression of experimental autoimmune myocarditis. Therefore, EP4 can be an effective target for myocarditis treatment.

Background:MMP activity is upregulated in the heart after myocardial ischemia reperfusion, and its activation contributes to the changes in left ventricular (LV) dysfunction. A major macrolide antibiotic, clarithromycin has many biological functions including MMP regulation. However, little is known about the effect of clarithromycin in myocardial reperfusion injury via MMPs. Our objective was to clarify the role of MMPs regulated by clarithromycin in the progression of myocardial reperfusion injury.Methods:We administered clarithromycin to rats with ischemia–reperfusion injury twice a day for 7 days before and 14 days after reperfusion.Results:Clarithromycin resulted in a significant reduction of the infarction area:area at risk ratio and preserved fractional shortening ratio after 14 days of reperfusion. Immunohistochemical analysis revealed that macrophages were the primary cellular source of MMPs. Fewer macrophages were detected in the ischemic area of the hearts following ischemia reperfusion in the clarithromycin-treated group compared with the vehicle-treated group. Although ischemia–reperfusion injury resulted in LV fibrosis with increasing MMP activities, clarithromycin significantly reduced these changes.Conclusion:Clarithromycin is effective for attenuating myocardial ischemia–reperfusion injury by suppressing MMPs.

Prostaglandin E2(PGE2) is a pathogenesis of inflammatory diseases; PGE2plays a key role in association of anti-inflammation and immune suppression. EP4, which is a PGE2receptor, is known to suppress the production of inflammatory cytokines and chemokines in vitro. Although it has been reported that EP4 agonists prolonged cardiac allograft survival, little has been elucidated the immunologic mechanism.

Objective: Amplification of inflammatory response in the non-infarct area plays an important role in the pathogenesis of ventricular remodeling after myocardial ischemia. Activation of nuclear factor-kappa B (NF-κB) is involved in this amplification through a positive feedback loop of pro- inflammatory cytokines. We investigated the efficacy of IKK blockade with IMD-0560, a novel inhibitor of IKK, in a rat myocardial ischemia model. Methods/results: Left coronary artery occlusion (28 days) was carried out in Sprague–Dawley rats. Daily intraperitoneal injections of IMD-0560 (5 mg/kg) were done after the operation. Treatment with IMD-0560 significantly improved cardiac function as indicated by the preservation of fractional shortening and lower serum brain natriuretic peptide level. Histological analysis showed that IMD-0560 treatment suppressed thinning in the infarcted area compared with vehicle-treated hearts. Moreover, in situzymography showed matrix metalloprotease-9 activity was inhibited in the infarct area. Conclusion: We revealed that the IKK blockade is potent for the suppression of chronic ventricular remodeling after myocardial ischemia.

Glucose incorporation is regulated mainly by GLUT4 in skeletal muscles. Here we report that treatment of L6 myotubes with scriptide, a hydroxamic acid-based histone deacetylase (HDAC) inhibitor, stimulated 2-deoxyglucose uptake. The effect appeared only after 24 hr, resulting in 2.4-fold glucose uptake at treatment day 6. Scriptide acted synergistically with insulin, indicating it stimulated a distinct pathway from the insulin signaling pathway. It was not observed in undifferentiated myoblasts or 3T3-L1 adipocytes, suggesting a muscle-specific effect of scriptide. A five-carbon chain and hydroxamic acid, essential for histone deacetylase inhibition, were indispensable for this effect, and trichostatin A stimulated glucose uptake as well. Scriptide increased the cellular content of GLUT4, and induced GLUT4 translocation, but GLUT4 mRNA level did not change, indicating scriptide functions posttranslationally. Our results indicated a novel function for HDAC inhibitors of increasing GLUT4 content and its translocation in muscle cells, resulting in stimulation of glucose uptake.

Pro-inflammatory pathways participate in the pathogenesis of atherosclerosis. However, the role of endogenous anti-inflammatory pathways in atheroma has received much less attention. Therefore, using cDNA microarrays, we screened for genes regulated by prostaglandin E(2) (PGE(2)), a potential endogenous anti-inflammatory mediator, in lipopolysaccharide (LPS)-treated human macrophages (MPhi). PGE(2) (50 nm) attenuated LPS-induced mRNA and protein expression of chemokines including monocyte chemoattractant protein-1, interleukin-8, macrophage inflammatory protein-1alpha and -1beta, and interferon-inducible protein-10. PGE(2) also inhibited the tumor necrosis factor-alpha-, interferon-gamma-, and interleukin-1beta-mediated expression of these chemokines. In contrast to the case of MPhi, PGE(2) did not suppress chemokine expression in human endothelial and smooth muscle cells (SMC) treated with LPS and pro-inflammatory cytokines. To assess the potential paracrine effect of endogenous PGE(2) on macrophage-derived chemokine production, we co-cultured MPhi with SMC in the presence of LPS. In these co-cultures, cyclooxygenase-2-dependent PGE(2) production exceeded that in the mono-cultures, and MIP-1beta declined significantly compared with MPhi cultured without SMC. We further documented prominent expression of the PGE(2) receptor EP4 in MPhi in both culture and human atheroma. Moreover, a selective EP4 antagonist completely reversed PGE(2)-mediated suppression of chemokine production. Thus, endogenous PGE(2) may modulate inflammation during atherogenesis and other inflammatory diseases by suppressing macrophage-derived chemokine production via the EP4 receptor.

A phospholipase A2with an arachidonoyl residue preference was purified about 11 700‐fold from human platelet soluble fraction to near homogeneity. The purified phospholipase A2exhibited a molecular mass of about 90 kDa on SDS polycrylamide gel electrophoresis and hydrolyzed phospholipids with a arachidonoyl residue more effectively than those with a linoleoyl residue. The catalytic activity of the purified enzyme detected with phosphatidylcholine as a substrate increased sharply between 3 × 10−7and 10−6M free calcium ion. Thus, the 90‐kDa phospholipase A2is considered to be a novel enzyme, distinct from the 14‐kDa one previously purified from human platelets. The 90‐kDa phospholipase A2may participate mainly in arachidonate metabolism of platelets.

Isoprene oligomerization was effected with a catalyst system Ni(OR)(η3-C3H5)PPh(NEt2)2(R=n-C11H23, n-C15H31) to give a linear trimer fraction above 70% yield. The major component of the trimer fraction is (E)-7,11-dimethyl-3-methylene-1,6,10-dodecatriene (trans-β-farnesene) (1). The minor constituents of the fraction are (E)-2,6-dimethyl-10-methylene-1,6,11-dodecatriene. As slightly higher boiling point fractions, two cyclic trimers 1,5,9-trimethyl-1,5,9-cyclododecatriene and 1,5,10-trimethyl-1,5,9-cyclododecatriene were detected. Factors that influence the reaction path leading to 1were discussed. Sesqui- and diterpenoids, including farnesyl acetate, farnesylacetone and isophytol were synthesised starting from 1. A regioselective tail to tail coupling of 1was achieved with a palladium catalyst to give the dimer C30H48which, upon catalytic hydrogenation, gave perhydrosqualene in 85% yield.

Four monoclonal antibodies (HP-1, HP-2, HP-3 and HP-4) with differing reactivities were raised against human synovial fluid phospholipase A2. None of them bound to exocrine phospholipases A2, such as those from pancreas or snake venom. However, antibodies HP-1 and HP-3 showed cross-reactivity with rabbit and rat platelet secretory phospholipases A2, which share common enzymatic and structural features with the human synovial enzyme. Antibodies HP-1, HP-2 and HP-3 inhibited the activity of human synovial phospholipase A2. The antibodies were used to develop a rapid immunoaffinity column chromatographic procedure for enzyme purification. In some preparations, the recovery of total activity after immunoaffinity column chromatography was more than 100% suggesting the existence of endogenous inhibitory factors of phospholipase A2in human synovial fluid.

A phospholipase A 2with an arachidonoyl residue preference was purified about 11 700-fold from human platelet soluble fraction to near homogeneity. The purified phospholipase A 2exhibited a molecular mass of about 90 kDa on SDS polycrylamide gel electrophoresis and hydrolyzed phospholipids with a arachidonoyl residue more effectively than those with a linoleoyl residue. The catalytic activity of the purified enzyme detected with phosphatidylcholine as a substrate increased sharply between 3 × 10 −7and 10 −6M free calcium ion. Thus, the 90-kDa phospholipase A 2is considered to be a novel enzyme, distinct from the 14-kDa one previously purified from human platelets. The 90-kDa phospholipase A 2may participate mainly in arachidonate metabolism of platelets.