A New Frontier in Cystic Fibrosis Pathophysiology: How and When Clock Genes Can Affect the Inflammatory/Immune Response in a Genetic Disease Model.

Cystic fibrosis (CF) is a monogenic syndrome caused by variants in the CF Transmembrane Conductance Regulator (CFTR) gene, affecting various organ and systems, in particular the lung, pancreas, sweat glands, liver, gastrointestinal tract, vas deferens, and vascular system. While for some organs, e.g., the pancreas, a strict genotype-phenotype occurs, others, such as the lung, display a different pathophysiologic outcome in the presence of the same mutational asset, arguing for genetic and environmental modifiers influencing severity and clinical trajectory. CFTR variants trigger a pathophysiological cascade of events responsible for chronic inflammatory responses, many aspects of which, especially related to immunity, are not ascertained yet. Although clock genes expression and function are known modulators of the innate and adaptive immunity, their involvement in CF has been only observed in relation to sleep abnormalities. The aim of this review is to present current evidence on the clock genes role in immune-inflammatory responses at the lung level. While information on this topic is known in other chronic airway diseases (chronic obstructive pulmonary disease and asthma), CF lung disease (CFLD) is lacking in this knowledge. We will present the bidirectional effect between clock genes and inflammatory factors that could possibly be implicated in the CFLD. It must be stressed that besides sleep disturbance and its mechanisms, there are not studies directly addressing the exact nature of clock genes' involvement in inflammation and immunity in CF, pointing out the directions of new and deepened studies in this monogenic affection. Importantly, clock genes have been found to be druggable by means of genetic tools or pharmacological agents, and this could have therapeutic implications in CFLD.

Pro- and Anti-Inflammatory Prostaglandins and Cytokines in Humans: A Mini Review.

Inflammation has been described for two millennia, but cellular aspects and the paradigm involving different mediators have been identified in the recent century. Two main groups of molecules, the prostaglandins (PG) and the cytokines, have been discovered and play a major role in inflammatory processes. The activation of prostaglandins PGE2, PGD2 and PGI2 results in prominent symptoms during cardiovascular and rheumatoid diseases. The balance between pro- and anti-inflammatory compounds is nowadays a challenge for more targeted therapeutic approaches. The first cytokine was described more than a century ago and is now a part of different families of cytokines (38 interleukins), including the IL-1 and IL-6 families and TNF and TGFß families. Cytokines can perform a dual role, being growth promotors or inhibitors and having pro- and anti-inflammatory properties. The complex interactions between cytokines, vascular cells and immune cells are responsible for dramatic conditions and lead to the concept of cytokine storm observed during sepsis, multi-organ failure and, recently, in some cases of COVID-19 infection. Cytokines such as interferon and hematopoietic growth factor have been used as therapy. Alternatively, the inhibition of cytokine functions has been largely developed using anti-interleukin or anti-TNF monoclonal antibodies in the treatment of sepsis or chronic inflammation.

Endothelium-dependent contraction: The non-classical action of endothelial prostacyclin, its underlying mechanisms, and implications.

Although commonly thought to produce prostacyclin (prostaglandin I2 ; PGI2 ) that evokes vasodilatation and protects vessels from the development of diseases, the endothelial cyclooxygenase (COX)-mediated metabolism has also been found to release substance(s) called endothelium-derived contracting factor(s) (EDCF) that causes endothelium-dependent contraction and implicates in endothelial dysfunction of disease conditions. Various mechanisms have been proposed for the process; however, the major endothelial COX metabolite PGI2 , which has been classically considered to activate the I prostanoid receptor (IP) that mediates vasodilatation and opposes the effects of thromboxane (Tx) A2 produced by COX in platelets, emerges as a major EDCF in health and disease conditions. Our recent studies from genetically altered mice further suggest that vasomotor reactions to PGI2 are collectively modulated by IP, the vasoconstrictor Tx-prostanoid receptor (TP; the prototype receptor of TxA2 ) and E prostanoid receptor-3 (EP3; a vasoconstrictor receptor of PGE2 ) although with differences in potency and efficacy; a contraction to PGI2 reflects activities of TP and/or EP3 outweighing that of the concurrently activated IP. Here, we discuss the history of endothelium-dependent contraction, evidences that support the above hypothesis, proposed mechanisms for the varied reactions to endothelial PGI2 synthesis as well as the relation of its dilator activity to the effect of another NO-independent vasodilator mechanism, the endothelium-derived hyperpolarizing factor. Also, we address the possible pathological and therapeutic implications as well as questions remaining to be resolved or limitations of our above findings obtained from genetically altered mouse models.

Differential properties of E prostanoid receptor-3 and thromboxane prostanoid receptor in activation by prostacyclin to evoke vasoconstrictor response in the mouse renal vasculature.

Vasomotor reactions of prostacyclin (prostaglandin I2 ; PGI2 ) can be collectively modulated by thromboxane prostanoid receptor (TP), E-prostanoid receptor-3 (EP3), and the vasodilator I prostanoid receptor (IP). This study aimed to determine the direct effect of PGI2 on renal arteries and/or the whole renal vasculature and how each of these receptors is involved. Experiments were performed on vessels or perfused kidneys of wild-type mice and/or mice with deficiency in TP (TP-/- ) and/or EP3. Here we show that PGI2 did not evoke relaxation, but instead resulted in contraction of main renal arteries (from ~0.001-0.01 µM) or reduction of flow in perfused kidneys (from ~1 µM); either of them was reversed into a dilator response in TP-/- /EP3-/- counterparts. Also, we found that in renal arteries although it has a lesser effect than TP-/- on the maximal contraction to PGI2 (10 µM), EP3-/- but not TP-/- resulted in relaxation to the prostanoid at 0.01-1 µM. Meanwhile, TP-/- only significantly reduced the contractile activity evoked by PGI2 at ≥0.1 µM. These results demonstrate that PGI2 may evoke an overall vasoconstrictor response in the mouse renal vasculature, reflecting activities of TP and EP3 outweighing that of the vasodilator IP. Also, our results suggest that EP3, on which PGI2 can have a potency similar to that on IP, plays a major role in the vasoconstrictor effect of the prostanoid of low concentrations (≤1 µM), while TP, on which PGI2 has a lower potency but higher efficacy, accounts for a larger part of its maximal contractile activity.

The first report of prostacyclin and its physiological roles in insects.

Prostaglandins (PGs) mediate physiological processes of insects as well as mammals. Prostaglandin I2 (PGI2) is a relatively well-known eicosanoid with potent hormone-like actions on various tissues of vertebrates, however, its presence and biosynthetic pathway have not been described in insects. This study demonstrated that fat bodies of the lepidopteran species, Spodoptera exigua, contained ~ 3.6 pg/g PGI2. To identify its biosynthetic pathway, a PGI2 synthase gene of S. exigua (Se-PGIS) was predicted from a transcriptome of S. exigua; 25.6% homology with human PGIS was demonstrated. Furthermore, a predicted three-dimensional structure of Se-PGIS was demonstrated to be 38.3% similar to the human PGIS ortholog, including catalytic residues. Se-PGIS was expressed in all developmental stages of S. exigua and most abundant larval and adult stages; immune challenging of larvae significantly up-regulated these expression levels. The inducible expression of Se-PGIS expression was followed by a greater than four-fold increase in the concentration of PGI2 in fat bodies 10 h after immune challenge. RNA interference (RNAi) against Se-PGIS was performed by injecting double-stranded RNA (dsRNA). Under these RNAi conditions, cellular immune responses (e.g., hemocyte-spreading behavior, nodulation, phenoloxidase activity) were not affected by bacterial challenge. The addition of PGI2 to larvae treated with an eicosanoid biosynthesis inhibitor did not rescue the immunosuppression. Interestingly, PGI2 injection significantly suppressed nodule formation in response to bacterial challenge. In addition to the negative effect of PGI2 against immunity, the Se-PGIS-RNAi treatment significantly interfered with immature development and severely impaired oocyte development in female adults; the addition of PGI2 to RNAi-treated females significantly recovered oocyte development. Se-PGIS RNAi treatment also impaired male fertility by reducing fecundity after mating with untreated females. These results suggest that PGI2 acts as a negative regulator of immune responses initiated by other factors and mediates S. exigua development and reproduction.

Umbilical vein infusion of prostaglandin I2 increases ductus venosus shunting of oxygen-rich blood but does not increase cerebral oxygen delivery in the fetal sheep.

KEY POINTS: The ductus venosus (DV) is a dynamic fetal shunt that allows substrate-rich blood from the umbilical vein to bypass the hepatic circulation. In vitro studies suggest a direct role of prostaglandin I2 (PGI2 ) in the regulation of DV tone; however, the extent of this regulation has not been determined in utero. 4D flow and T2 oximetry magnetic resonance imaging can be combined to determine blood flow and oxygen delivery within the fetal circulation. PGI2 increases DV shunting of substrate-rich blood but this does not increase cerebral oxygen delivery. ABSTRACT: During fetal development, the maintenance of adequate oxygen and nutrient supply to vital organs is regulated through specialized fetal shunts. One of these shunts, the ductus venosus (DV), allows oxygen-rich blood to preferentially stream from the placenta toward the heart and brain. Herein, we combine magnetic resonance imaging (MRI) techniques that measure blood flow (4D flow) and oxygen saturation (T2 oximetry) in the fetal circuit to determine whether umbilical vein infusion of prostaglandin I2 (PGI2 , regulator of DV tone ex utero) directly dilates the DV and thus increases the preferential streaming of oxygen-rich blood toward the brain. At 114-115 days gestational age (dGA; term = 150 days), fetal sheep (n = 6) underwent surgery to implant vascular catheters in the fetal femoral artery, femoral vein, amniotic cavity and umbilical vein. Fetal MRI scans were performed at 119-124 dGA. 4D flow and T2 oximetry were performed to measure blood flow and oxygen saturation across the fetal circulation in both a basal state and whilst the fetus was receiving a continuous infusion of PGI2 . The proportion of oxygenated blood that passed through the DV from the umbilical vein was increased by PGI2 . Cerebral oxygen delivery was unchanged in the PGI2 state. This may be a result of decreased flow from the right to left side of the heart as blood flow through the foramen ovale was decreased by PGI2 . We have shown that although PGI2 acts on the DV to increase the proportion of oxygen-rich blood that bypasses the liver, this does not increase cerebral oxygen delivery in the fetal sheep.

Prostaglandin I2 mediates weak vasodilatation in human placental microvessels.

Human placental vessels (HPVs) play important roles in the exchange of metabolites and oxygen in maternal-fetal circulation. Endothelial-derived prostacyclin (prostaglandin I2, PGI2) is a critical endothelial vasodilator in the body. However, the physiological and pharmacological functions of endothelial PGI2 in the human placenta are still unclear. Human, sheep, and rat blood vessels were used in this study. Unlike non-placental vessels (non-PVs), the PGI2 synthesis inhibitor tranylcypromine (TCP) did not modify 5-hydroxytryptamine (5-HT)-induced vascular contraction, indicating that endothelial-derived PGI2 was weak in PVs. Vascular responses to exogenous PGI2 showed slight relaxation followed by a significant contraction at a higher concentration in HPV, which was inhibited by the thromboxane-prostanoid (TP) receptors antagonist SQ-29,548. Testing PVs and non-PVs from sheep also showed similar functional results. More TP receptors than PGI2 (IP) receptors were observed in HPVs. The whole-cell K+ current density of HPVs was significantly weaker than that of non-PVs. This study demonstrated the specific characteristics of the placental endogenous endothelial PGI2 system and the patterns of placental vascular physiological/pharmacological response to exogenous PGI2, showing that placental endothelial PGI2 does not markedly contribute to vascular dilation in the human placenta, in notable contrast to non-PVs. The results provide crucial information for understanding the endothelial roles of HPVs, which may be helpful for further investigations of potential targets in the treatment of diseases such as preeclampsia.

The functional link between microsomal prostaglandin E synthase-1 (mPGES-1) and peroxisome proliferator-activated receptor γ (PPARγ) in the onset of inflammation.

Many years have elapsed since the discovery of anti-inflammatories as effective therapeutics for the treatment of inflammatory-related diseases, but we are still uncovering their various mechanisms of action. Recent biochemical and pharmacological studies have shown that in different tissues and cell types lipid mediators from thearachidonic acid cascade, play a crucial role in the initiation and resolution of inflammation by shifting from pro-inflammatory prostaglandin (PG)E2 to anti-inflammatory PGD2 and PGJ2. Considering that until now very little is known about the biological effects evoked by microsomal prostaglandin E synthase-1 (mPGES-1) and contextually by peroxisome proliferator-activated receptor γ (PPARγ) modulation (key enzymes involved in PGE2 and PGD2/PGJ2metabolism), in this opinion paper we sought to define the coordinate functional regulation between these two enzymes at the "crossroads of phlogistic pathway" involved in the induction and resolution of inflammation.

Interaction between PGI2 and ET-1 pathways in vascular smooth muscle from Group-III pulmonary hypertension patients.

Pulmonary hypertension (PH) is characterized by an elevation of mean pulmonary artery pressure and it is classified into five groups. Among these groups, PH Group-III is defined as PH due to lung disease or hypoxia. Prostacyclin (PGI2) analogues (iloprost, treprostinil) and endothelin-1 (ET-1) receptor antagonists (ERA) (used alone or in combination) are therapies used for treating PH. The mechanisms underlying the positive/negative effects of combination treatment are not well documented, and in this study, we tested the hypothesis that the combination of a PGI2 analogue (iloprost, treprostinil) and an ERA may be more effective than either drug alone to treat vasculopathies observed in PH Group-III patients. Using Western blotting, ETA and ETB receptor expression were determined in human pulmonary artery (HPA) preparations derived from control and PH Group-III patients, and the physiologic impact of altered expression ratios was assessed by measuring ET-1 induced contraction of ex vivo HPA and human pulmonary veins (HPV) in an isolated organ bath system. In addition, the effects of single agent or combination treatments with a PGI2 analogue and an ERA on ET-1 release and HPA smooth muscle cells (hPASMCs) proliferation were determined by ELISA and MTT techniques, respectively. Our results indicate that the increased ETA/ETB receptor expression ratio in HPA derived from PH Group-III patients is primarily governed by a greatly depressed ETB receptor expression. However, contractions induced by ET-1 are not impacted in HPA and HPV derived from PH Group-III patients as compared to controls. Also, we found that the combination of an ETA receptor antagonist (BQ123) with iloprost provides greater inhibition of hPASMCs proliferation (-48±14% control; -32±06% PH) than either agent alone. Of note, while the ETB receptor antagonist (BQ788) increases ET-1 production from PH Group-III patients' preparations (HPA, parenchyma), even under these more proliferative conditions, iloprost and treprostinil are still effective to inhibit hPASMCs proliferation (-22/-24%). Our findings may provide new insights for the treatment of PH Group-III by combining a PGI2 analogue and a selective ETA receptor antagonist.

Lactoferrin Induces the Synthesis of Vitamin B6 and Protects HUVEC Functions by Activating PDXP and the PI3K/AKT/ERK1/2 Pathway.

As a nutritional active protein in foods, multiple studies of the biological activities of lactoferrin had been undertaken, including antioxidant, antiviral, anti-inflammatory, antitumor, antibiosis, and antiparasitic effects, while the mechanism related with its protection of cardiovascular system remained elusive. In the present work, the effect of lactoferrin on the viability of HUVECs (human umbilical vein endothelial cells) was detected to select the proper doses. Moreover, transcriptomics detection and data analysis were performed to screen out the special genes and the related pathways. Meanwhile, the regulation of lactoferrin in the functional factors thromboxane A2 (TXA2) and prostacyclin (PGI2) was detected. Then, the small interfering RNA (SiRNA) fragment of the selected gene pyridoxal phosphatase (PDXP) was transfected into HUVECs to validate its role in protecting HUVECs function. Results showed that lactoferrin inhibited the expression of TXA2 and activated expression of PGI2, as well as activated expression of PDXP, which significantly up-regulated the synthesis of vitamin B6 (VB6) and the phosphoinositide 3-kinase (PI3K)/ serine/threonine-protein kinase (AKT)/ extracellular regulated protein kinases (ERK) 1/2 pathway. For the first time, we revealed that lactoferrin could induce the synthesis of VB6 and protect HUVECs function through activating PDXP gene and the related pathway.

Positive influence of aqua exercise and burdock extract intake on fitness factors and vascular regulation substances in elderly.

Health issues in elderly individuals are often complex and tend to lead to chronic diseases; such issues can be due to a decline in fitness resulting from lack of physical activity. Aqua exercise and burdock are positive effects on cardiovascular disease and vascular health. This study investigated the changes due to aqua exercise and burdock extract intake in senior fitness, prostaglandin I2 (PGI2), and thromboxane A2 (TXA2) in elderly women. Forty elderly women (65-80 years) volunteered for this study. After baseline measurements, participants were randomized into control (n = 8), aqua exercise (n = 11), aqua exercise and burdock extract intake combination (n = 11), and burdock extract intake groups (n = 10). The variables of senior fitness tests, PGI2 and TXA2 were measured in all participants before and after the 12-week study. Blood collections were carried out at the beginning- and the end of aqua exercise training. Muscular strength, endurance, flexibility, and cardiorespiratory endurance of aqua exercise and burdock extract intake group at post-test significantly increased compared to pre-test (p<0.05). There were no significant differences in PGI2 and TXA2 between pre- and post-training programs. In conclusion, our findings indicated that the aqua exercise and burdock extract intake improves senior fitness factors in elderly Korean women. Also, the program participation led to a balance between PGI2 and TXA2. Additionally, burdock extract intake may be useful in vascular health by playing a secondary role in disease prevention and health promotion.

Expression and function of TLR4- induced B1R bradykinin receptor on cardiac fibroblasts.

Cardiac fibroblasts (CF) are key cells for maintaining extracellular matrix (ECM) protein homeostasis in the heart, and for cardiac repair through CF-to-cardiac myofibroblast (CMF) differentiation. Additionally, CF play an important role in the inflammatory process after cardiac injury, and they express Toll like receptor 4 (TLR4), B1 and B2 bradykinin receptors (B1R and B2R) which are important in the inflammatory response. B1R and B2R are induced by proinflammatory cytokines and their activation by bradykinin (BK: B2R agonist) or des-arg-kallidin (DAKD: B1R agonist), induces NO and PGI2 production which is key for reducing collagen I levels. However, whether TLR4 activation regulates bradykinin receptor expression remains unknown. CF were isolated from human, neonatal rat and adult mouse heart. B1R mRNA expression was evaluated by qRT-PCR, whereas B1R, collagen, COX-2 and iNOS protein levels were evaluated by Western Blot. NO and PGI2 were evaluated by commercial kits. We report here that in CF, TLR4 activation increased B1R mRNA and protein levels, as well as COX-2 and iNOS levels. B1R mRNA levels were also induced by interleukin-1α via its cognate receptor IL-1R1. In LPS-pretreated CF the DAKD treatment induced higher responses with respect to those observed in non LPS-pretreated CF, increasing PGI2 secretion and NO production; and reducing collagen I protein levels in CF. In conclusion, no significant response to DAKD was observed (due to very low expression of B1R in CF) - but pre-activation of TLR4 in CF, conditions that significantly enhanced B1R expression, led to an additional response of DAKD.

Beraprost Sodium, a Stable Analogue of PGI2, Inhibits the Renin-Angiotensin System in the Renal Tissues of Rats with Chronic Renal Failure.

BACKGROUND/AIMS: Chronic renal failure (CRF) is a prolonged kidney condition characterized by decreased kidney function that can eventually develop into total kidney failure. The renin-angiotensin system (RAS) helps to regulate the balance between human bodily fluids and electrolytes. The aim of the present study was to investigate the effects of a prostacyclin analogue (beraprost sodium [BPS]) on the expression of key factors associated with local RAS activities in the renal tissues of rats with CRF. METHODS: After a CRF rat model was successfully established, the levels of BUN, SCr, phosphorus, and calcium were detected by an automatic biochemistry analyzer. Furthermore, the activities of malondialdehyde (MDA) and superoxide dismutase (SOD) in rat renal tissues were measured using a colorimetric method, while the activity of angiotensin-converting enzyme (ACE) was determined by ultraviolet (UV) spectrophotometry. In situ hybridization was employed to determine the expression of angiotensin II type 1 receptor (AT). Finally, the positive expression rates of cells expressing important apoptotic proteins (Bax and Bcl-2) were determined, and the protein and mRNA levels of phosphatidylinositol 3-kinase (AKT) and key factors involved in the RAS (AT1, AT2, angiotensin ACE and angiotensinogen [AGT]) were evaluated by RT-qPCR and western blot analysis. RESULTS: Initial observations revealed that treatment with BPS decreased the levels of BUN, SCr and phosphorus but increased calcium levels in the renal tissues of CRF rats. Additionally, BPS reduced the levels of MDA while increasing the levels of SOD, ACE activity, and AT1 expression in the renal tissues of CRF rats. BPS inhibited glomerular hypertension and hyperfiltration; increased the mRNA and protein levels of AKT and AT2; and decreased the mRNA and protein levels of AT1, AGT, and ACE in the renal tissues of CRF rats. CONCLUSION: The results of this study demonstrate that BPS, a PGI2 analogue, inhibits the expression of key factors involved in the local RAS, resulting in a delay in the occurrence and development of CRF. The key findings of the present study ultimately highlight the potential of this PGI2 analogue as a promising therapeutic strategy for treating CRF.

Prostaglandin I2 Signaling and Inhibition of Group 2 Innate Lymphoid Cell Responses.

RATIONALE: Group 2 innate lymphoid cells (ILC2s) robustly produce IL-5 and IL-13, cytokines central to the asthma phenotype; however, the effect of prostaglandin (PG) I2 on ILC2 function is unknown. OBJECTIVES: To determine the effect of PGI2 on mouse and human ILC2 cytokine expression in vitro and the effect of endogenous PGI2 and the PGI2 analog cicaprost on lung ILC2s in vivo. METHODS: Flow-sorted bone marrow ILC2s of wild-type (WT) and PGI2 receptor-deficient (IP(-/-)) mice were cultured with IL-33 and treated with the PGI2 analog cicaprost. WT and IP(-/-) mice were challenged intranasally with Alternaria alternata extract for 4 consecutive days to induce ILC2 responses, and these were quantified. Prior to A. alternata extract, challenged WT mice were treated with cicaprost. Human flow-sorted peripheral blood ILC2s were cultured with IL-33 and IL-2 and treated with the PGI2 analog cicaprost. MEASUREMENT AND MAIN RESULTS: We demonstrate that PGI2 inhibits IL-5 and IL-13 protein expression by IL-33-stimulated ILC2s purified from mouse bone marrow in a manner that was dependent on signaling through the PGI2 receptor IP. In a mouse model of 4 consecutive days of airway challenge with an extract of A. alternata, a fungal aeroallergen associated with severe asthma exacerbations, endogenous PGI2 signaling significantly inhibited lung IL-5 and IL-13 protein expression, and reduced the number of lung IL-5- and IL-13-expressing ILC2s, as well as the mean fluorescence intensity of IL-5 and IL-13 staining. In addition, exogenous administration of a PGI2 analog inhibited Alternaria extract-induced lung IL-5 and IL-13 protein expression, and reduced the number of lung IL-5- and IL-13-expressing ILC2s and the mean fluorescence intensity of IL-5 and IL-13 staining. Finally, a PGI2 analog inhibited IL-5 and IL-13 expression by human ILC2s that were stimulated with IL-2 and IL-33. CONCLUSIONS: These results suggest that PGI2 may be a potential therapy to reduce the ILC2 response to protease-containing aeroallergens, such as Alternaria.

Effects of astaxanthin on blood coagulation, fibrinolysis and platelet aggregation in hyperlipidemic rats.

CONTEXT: Astaxanthin (ASTX) is a xanthophyll carotenoid that reduces hemostasis in hyperlipidemic organisms. Its antihemostatic mechanisms remain unclear. OBJECTIVE: The effects of ASTX on coagulation, the fibrinolytic system and platelet aggregation were investigated in hyperlipidemic rats. MATERIALS AND METHODS: Different doses of ASTX (5, 10 and 30 mg/kg/day, p.o.) were administered for four weeks to high-fat diet-induced hyperlipidemic rats. Serum lipid and lipoprotein levels were measured with an automatic biochemical analyzer. The prothrombin time (PT), activated partial thromboplastin time (APTT) and maximum platelet aggregation rate (MAR) were determined by a coagulation analyzer. The activities of the tissue-type plasminogen activator (t-PA), type-1 plasminogen activator inhibitor (PAI-1) and endothelial nitric oxide synthase (eNOS), as well as the levels of thromboxane B(2) [TXB(2)], 6-keto prostaglandin F(1α) [6-keto-PGF(1α)] and platelet granule membrane protein (GMP-140), were measured with enzyme-linked immunosorbent assay kits. Gene and protein expression levels were analyzed by reverse transcriptase polymerase chain reaction and Western blot, respectively. RESULTS: ASTX (30 mg/kg) treatment in hyperlipidemic rats reduced serum TG (0.58 ± 0.14 versus 1.12 ± 0.24 mmol/L), serum TC (1.77 ± 0.22 versus 2.24 ± 0.21 mmol/L), serum LDL-C (1.13 ± 0.32 versus 2.04 ± 0.48 mmol/L), serum MDA (69%), plasma MAR (55%), serum TXB2/6-keto-PGF1α (34%) and serum GMP-140 levels (25%), plasma PAI-1 activity (48%) and downregulated the mRNA (33%) and protein (23%) expression of aorta eNOS, the mRNA (79%) and protein (72%) expression levels of aorta PAI-1. However, ASTX (30 mg/kg/d) treatment increased serum SOD activity (2.1 fold), serum GPx activity (1.8 fold), plasma PT (1.3 fold), plasma APTT (1.7 fold), serum NO (1.4-fold), serum 6-keto-PGF1α (1.3 fold). CONCLUSIONS: ASTX reduced blood coagulation and platelet aggregation and promoted fibrinolytic activity in hyperlipidemic rats. These activities were closely correlated with ASTX, maintaining the balance of t-PA/PAI-1, NO/ROS and TXA2/PGI2 in vivo.

In silico modelling of prostacyclin and other lipid mediators to nuclear receptors reveal novel thyroid hormone receptor antagonist properties.

Prostacyclin (PGI2) is a key mediator involved in cardiovascular homeostasis, acting predominantly on two receptor types; cell surface IP receptor and cytosolic peroxisome proliferator activated receptor (PPAR) ß/δ. Having a very short half-life, direct methods to determine its long term effects on cells is difficult, and little is known of its interactions with nuclear receptors. Here we used computational chemistry methods to investigate the potential for PGI2, beraprost (IP receptor agonist), and GW0742 (PPARß/δ agonist), to bind to nuclear receptors, confirmed with pharmacological methods. In silico screening predicted that PGI2, beraprost, and GW0742 have the potential to bind to different nuclear receptors, in particular thyroid hormone ß receptor (TRß) and thyroid hormone α receptor (TRα). Docking analysis predicts a binding profile to residues thought to have allosteric control on the TR ligand binding site. Luciferase reporter assays confirmed that beraprost and GW0742 display TRß and TRα antagonistic properties; beraprost IC50 6.3 × 10(-5)mol/L and GW0742 IC50 4.9 × 10(-6) mol/L. Changes to triiodothyronine (T3) induced vasodilation of rat mesenteric arteries measured on the wire myograph were measured in the presence of the TR antagonist MLS000389544 (10(-5) mol/L), beraprost (10(-5) mol/L) and GW0742 (10(-5) mol/L); all significantly inhibited T3 induced vasodilation compared to controls. We have shown that both beraprost and GW0742 exhibit TRß and TRα antagonist behaviour, and suggests that PGI2 has the ability to affect the long term function of cells through binding to and inactivating thyroid hormone receptors.

Prostacyclin-synthase expression in head and neck carcinoma patients and its prognostic value in the response to radiotherapy.

Prostacyclin (PGI2 ) plays a role in cancer progression but the mechanism is currently poorly understood. Additionally, no data are available about the prognostic value of the PGI2 pathway in head and neck squamous cell carcinoma (HNSCC) therapy. We evaluated the expression of the PGI2 pathway in HNSCC patients. PGI2 production and PGI synthase (PGIS) expression, in terms of mRNA (RT-PCR) and protein (immunoblotting), were lower in tumour samples than in non-tumoural mucosa, whereas, as expected, COX-2 expression was increased in HNSCC tumour samples. Using local control of the tumour after radiotherapy or chemoradiotherapy as a dependent variable, patients were classified into two categories of PGIS transcript levels. The high-PGIS group had a significantly lower frequency of local and distant failure than the low-PGIS group, and the 5-year cancer-specific survival was higher [90.2% (95% CI 81.0-99.4%) versus 60.5% (95% CI 44.4-76.6%)]. None of the four HNSCC cell lines analysed expressed PGIS and therefore they did not produce PGI2 . However, HNSCC-conditioned media enhanced PGI2 production in endothelial cells (ECs). The stable analogue of PGI2 , carbaprostacyclin (cPGI2 ), exerted little effect on HNSCC cell line migration, and no effect on cell cycle distribution or proliferation rate after radiation injury was observed. Nevertheless, cPGI2 promoted EP-4-dependent in vitro angiogenesis. Von Willebrand factor expression (EC marker) and capillary density were significantly higher in the group of patients with high expression of PGIS. Our results indicate that PGIS expression was associated with radiotherapy efficiency. Although we do not provide direct evidence of a relationship between tumour vascularization and radiotherapy efficiency, our results suggest that the effect of PGI2 is related to its ability to promote vascularization. These results also support the concept that co-adjuvant therapy with PGIS enhancers, such as retinoids, could have therapeutic value for HNSCC treatment.

Evidence for the Use of Epoprostenol to Treat Raynaud's Phenomenon With or Without Digital Ulcers.

OBJECTIVE: To review the evidence for using intravenous (IV) epoprostenol to treat Raynaud's phenomenon (RP). DATA SOURCES: The databases MEDLINE (1946 to March 2016), PubMed, and International Pharmaceutical Abstracts were searched using the terms epoprostenol, Flolan, Raynaud's disease, and CREST syndrome. Further literature sources were identified by reviewing article citations. STUDY SELECTION AND DATA EXTRACTION: All English-language, clinical trials and case series evaluating IV epoprostenol for the management or treatment of RP were included. Lower-quality evidence were incorporated due to limited information. DATA SYNTHESIS: Seven small uncontrolled studies/case series, 1 small placebo controlled study, and 1 larger randomized trial were identified and included. There was no consistent measurement of efficacy utilized, but improvements in hand temperature, RP attack duration and frequency were commonly associated with IV epoprostenol treatment (5 trials). There were conflicting data regarding effect sustainability, with 5 trials showing long-term effects and 3 showing immediate effects. Fewer ischemic ulcers developed during treatment with IV epoprostenol in 1 trial compared to conventional treatment. Ulcer healing ocurred in 2 trials. Common adverse effects included hypotension, headache, flushing, gastrointestinal symptoms, and jaw pain. CONCLUSIONS: Available evidence supports the use of IV epoprostenol for treatment of severe RP in patients refractory or intolerant to standard therapies. The dose, titration schedule, and duration of IV epoprostenol utilized in studies varied, but a conservative approach to initiation should be considered. Patients who do not respond to intermittent infusions and have severe digital ischemia may require more aggressive regimens.

Role of cyclooxygenase-1 and -2 in endothelium-dependent contraction of atherosclerotic mouse abdominal aortas.

The objective of this study was to determine the role of cyclooxygenase (COX)-1 or -2 in endothelium-dependent contraction under atherosclerotic conditions. Atherosclerosis was induced in apoE knockout (apoE(-/-)) mice and those with COX-1(-/-) (apoE(-/-)-COX-1(-/-)) by feeding with high fat and cholesterol food. Aortas (abdominal or the whole section) were isolated for functional and/or biochemical analyses. As in non-atherosclerotic conditions, the muscarinic receptor agonist acetylcholine (ACh) evoked an endothelium-dependent, COX-mediated contraction following NO synthase (NOS) inhibition in abdominal aortic rings from atherosclerotic apoE(-/-) mice. Interestingly, COX-1 inhibition not only abolished such a contraction in rings showing normal appearance, but also diminished that in rings with plaques. Accordingly, only a minor contraction (<30% that of apoE(-/-) counterparts) was evoked by ACh (following NOS inhibition) in abdominal aortic rings of atherosclerotic apoE(-/-)-COX-1(-/-) mice with plaques, and none was evoked in those showing normal appearance. Also, the contraction evoked by ACh in apoE(-/-)-COX-1(-/-) abdominal aortic rings with plaques was abolished by non-selective COX inhibition, thromboxane-prostanoid (TP) receptor antagonism, or endothelial denudation. Moreover, it was noted that ACh evoked a predominant production of the prostacyclin (PGI2, which mediates abdominal aortic contraction via TP receptors in mice) metabolite 6-keto-PGF1α, which was again sensitive to COX-1 inhibition or COX-1(-/-). Therefore, in atherosclerotic mouse abdominal aortas, COX-1 can still be the major isoform mediating endothelium-dependent contraction, which probably results largely from PGI2 synthesis as in non-atherosclerotic conditions. In contrast, COX-2 may have only a minor role in such response limited to areas of plaques under the same pathological condition.

Cyclooxygenase inhibition abrogates aeroallergen-induced immune tolerance by suppressing prostaglandin I2 receptor signaling.

BACKGROUND: The prevalence of allergic diseases has doubled in developed countries in the past several decades. Cyclooxygenase (COX)-inhibiting drugs augmented allergic diseases in mice by increasing allergic sensitization and memory immune responses. However, whether COX inhibition can promote allergic airway diseases by inhibiting immune tolerance is not known. OBJECTIVE: To determine the role of the COX pathway and prostaglandin I2 (PGI2) signaling through the PGI2 receptor (IP) in aeroallergen-induced immune tolerance. METHODS: Wild-type (WT) BALB/c mice and IP knockout mice were aerosolized with ovalbumin (OVA) to induce immune tolerance prior to immune sensitization with an intraperitoneal injection of OVA/alum. The COX inhibitor indomethacin or vehicle was administered in drinking water to inhibit enzyme activity during the sensitization phase. Two weeks after sensitization, the mice were challenged with OVA aerosols. Mouse bronchoalveolar lavage fluid was harvested for cell counts and TH2 cytokine measurements. RESULTS: WT mice treated with indomethacin had greater numbers of total cells, eosinophils, and lymphocytes, and increased IL-5 and IL-13 protein expression in BAL fluid compared to vehicle-treated mice. Similarly, IP knockout mice had augmented inflammation and TH2 cytokine responses compared to WT mice. In contrast, the PGI2 analog cicaprost attenuated the anti-tolerance effect of COX inhibition. CONCLUSION: COX inhibition abrogated immune tolerance by suppressing PGI2 IP signaling, suggesting that PGI2 signaling promotes immune tolerance and that clinical use of COX-inhibiting drugs may increase the risk of developing allergic diseases.