Comparative study of coronary artery bypass graft materials: reduced contraction and ADMA levels in internal mammary artery versus saphenous vein.

BACKGROUND: Vasospasm and atherosclerosis due to low endothelial capacity are the most important causes of coronary artery bypass graft failure observed in internal mammary artery (IMA) and saphenous vein (SV). Vasospasm can be mimicked in in-vitro studies by inducing vasoconstriction of graft materials. In the present study, we aimed to compare the vascular contraction induced by several spasmogens including prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2α), phenylephrine (PE), leukotriene C4 (LTC4), LTD4, potassium chloride (KCl), and arachidonic acid between IMA and SV preparations. Furthermore, endothelial capacity, nitrite and asymmetric dimethylarginine (ADMA) levels were compared between two grafts. METHODS: By using organ bath, contractile responses induced by different spasmogens were compared between IMA and SV preparations derived from patients underwent coronary artery bypass surgery (N.=35). The endothelial capacity was determined by acetylcholine-induced (ACh) relaxation in PE-precontracted vessels. Nitrite and ADMA levels were measured in organ culture supernatant of IMA and SV preparations. RESULTS: Contractile responses induced by PGE2, PGF2α, PE, LTC4, LTD4, KCl and arachidonic acid were significantly lower in IMA preparations versus SV preparations. ACh-induced relaxation was significantly more prominent in IMA than SV preparations. Nitrite levels were greater and ADMA levels were lower in IMA versus SV preparations. CONCLUSIONS: IMA has reduced capacity to constrict to several vasoconstrictor agents. Furthermore, IMA has greater endothelial capacity associated with higher nitrite levels and lower ADMA levels. Our results support the greater patency rate observed in IMA versus SV preparations.

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.

Mechanism of thromboxane receptor-induced vasoconstriction in human saphenous vein.

Saphenous vein (SV) is one of the most widely used graft material in patients undergoing coronary artery bypass graft surgery (CABG). Thromboxane A2 (TXA2) is implicated in graft failure by inducing vasoconstriction and platelet aggregation. The aim of this study is to investigate the mechanism involved in TXA2-induced vasoconstriction in human SV. The role of different inhibitors and blockers on U46619 (TXA2-mimetic)-induced vasoconstriction is investigated by using an isolated organ bath system. Relaxation responses to several mediators are evaluated in SV pre-contracted with U46619 and compared with those pre-contracted with phenylephrine. Our results demonstrate that U46619-induced contraction is completely blocked by myosin light chain kinase inhibitor ML-9 or TP receptor antagonist BAY u3405. Furthermore, U46619-induced contraction is partially inhibited by phospholipase C inhibitor U73122, protein kinase C inhibitor calphostin C, Rho-kinase inhibitor Y-27632, L-type calcium channel blocker nifedipine, store-operated channel inhibitor SKF96365 or removal of extracellular calcium. Relaxation responses to NO donor (sodium nitroprusside), guanylate cyclase (GC) stimulator (riociguat), phosphodiesterase (PDE) inhibitors (sildenafil, IBMX), adenylate cyclase (AC) activator (forskolin) and acetylcholine (ACh) are markedly reduced when U46619 is used as a pre-contraction agent. Our results demonstrate that influx of extracellular Ca2+ (through L-type calcium channels and store-operated calcium channels) and intracellular Ca2+ release together with Ca2+ sensitization (through Rho-kinase activation) are necessary components for TXA2-induced vasoconstriction in SV. Moreover, more pronounced decrease in vasorelaxation induced by several mediators (SNP, riociguat, sildenafil, IBMX, forskolin, and ACh) in the presence of U46619 when compared with phenylephrine suggests that there is a crosstalk between the TP receptor signaling pathway and PDE, AC, GC enzymes. We believe that the investigation of mechanism of the TXA2-induced vasoconstriction in SV will provide additional information for the prevention of SV graft failure.

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.

Hypoactivity of rat detrusor muscle in a model of cystitis: exacerbation by non-selective COX inhibitors and amelioration by a selective DP1 receptor antagonist.

Various studies have confirmed that prostaglandins (PG) alter the bladder motor activity and micturition reflex in both human and animals. However, no sufficient data is reported about the effect of cyclooxygenase (COX) inhibitors neither in normal bladder physiology nor in pathological conditions. This study aims to compare the potential effects of some COX inhibitors with varying COX-1/COX-2 selectivities (indomethacin, ketoprofen, and diclofenac) with that of the selective COX-2 inhibitor (DFU) on bladder function. The role played by some PGs and their receptors in controlling detrusor muscle function in normal condition and in cystitis is also studied. Organ bath experiments were performed using isolated rat detrusor muscle. Direct and neurogenic contractions were induced using ACh and electric stimulation (EFS), respectively. A model of hemorrhagic cystitis was induced by single injection of cyclophosphamide (300 mg/kg) in rats, and confirmed by histophathological examination. Results are expressed as mean ± SEM of 5-9 rats. Alprostadil and iloprost (1 nM- 10 µM) concentration-dependently potentiated ACh (100 µM)- and EFS (4 Hz)-induced contraction, with maximum potentiation of 40.01 ± 5.29 and 27.59 ± 6.64%, respectively, in case of ACh contractions. In contrast, ONO-AE1-259 (selective EP2 agonist, 1 nM-10 µM) inhibited muscle contraction. SC51322 (EP1-antagonist, 10 µM) and RO1138452 (IP antagonist, 10 µM) inhibited both direct and neurogenic responses. Hemorrhagic cystitis reduced both ACh and EFS responses as well as the potentiatory effect of iloprost and the inhibitory effect of RO1138452 on ACh contractions. ONO-AE3-237 (DP1 antagonist, 1 µM) significantly potentiated contractions in cystitis but showed no effect in normal bladder. A significant inhibition of contractile response was observed in presence of indomethacin, ketoprofen, and diclofenac at all tested concentrations (20, 50, and 100 µM). Highest effect was induced by diclofenac. The effect of these COX inhibitors on EFS contractions was intensified in case of cystitis, indomethacin being the most potent. Atropine (1 nM) significantly reduced indomethacin effect on ACh contraction only in normal rats. On the other hand, DFU (10-6 M) significantly potentiated the contractile effect of ACh in case of cystitis although it showed no effect in normal rats. EP1 receptors seem to play an important role in rat bladder contractility. DP1 receptors as COX-2, on the other hand, gain an important role only in case of cystitis. The use of non-selective COX inhibitors in cystitis may be associated with bladder hypoactivity; selective COX-2 inhibitors may be a safer option.

Prostanoid EP2 Receptors Are Up-Regulated in Human Pulmonary Arterial Hypertension: A Key Anti-Proliferative Target for Treprostinil in Smooth Muscle Cells.

Prostacyclins are extensively used to treat pulmonary arterial hypertension (PAH), a life-threatening disease involving the progressive thickening of small pulmonary arteries. Although these agents are considered to act therapeutically via the prostanoid IP receptor, treprostinil is the only prostacyclin mimetic that potently binds to the prostanoid EP2 receptor, the role of which is unknown in PAH. We hypothesised that EP2 receptors contribute to the anti-proliferative effects of treprostinil in human pulmonary arterial smooth muscle cells (PASMCs), contrasting with selexipag, a non-prostanoid selective IP agonist. Human PASMCs from PAH patients were used to assess prostanoid receptor expression, cell proliferation, and cyclic adenosine monophosphate (cAMP) levels following the addition of agonists, antagonists or EP2 receptor small interfering RNAs (siRNAs). Immunohistochemical staining was performed in lung sections from control and PAH patients. We demonstrate using selective IP (RO1138452) and EP2 (PF-04418948) antagonists that the anti-proliferative actions of treprostinil depend largely on EP2 receptors rather than IP receptors, unlike MRE-269 (selexipag-active metabolite). Likewise, EP2 receptor knockdown selectively reduced the functional responses to treprostinil but not MRE-269. Furthermore, EP2 receptor levels were enhanced in human PASMCs and in lung sections from PAH patients compared to controls. Thus, EP2 receptors represent a novel therapeutic target for treprostinil, highlighting key pharmacological differences between prostacyclin mimetics used in PAH.

Silver Nanoparticles Impair Retinoic Acid-Inducible Gene I-Mediated Mitochondrial Antiviral Immunity by Blocking the Autophagic Flux in Lung Epithelial Cells.

Silver nanoparticles (AgNPs) are microbicidal agents which could be potentially used as an alternative to antivirals to treat human infectious diseases, especially influenza virus infections where antivirals have generally proven unsuccessful. However, concerns about the use of AgNPs on humans arise from their potential toxicity, although mechanisms are not well-understood. We show here, in the context of an influenza virus infection of lung epithelial cells, that AgNPs down-regulated influenza induced CCL-5 and -IFN-ß release (two cytokines important in antiviral immunity) through RIG-I inhibition, while enhancing IL-8 production, a cytokine important for mobilizing host antibacterial responses. AgNPs activity was independent of coating and was not observed with gold nanoparticles. Down-stream analysis indicated that AgNPs disorganized the mitochondrial network and prevented the antiviral IRF-7 transcription factor influx into the nucleus. Importantly, we showed that the modulation of RIG-I-IRF-7 pathway was concomitant with inhibition of either classical or alternative autophagy (ATG-5- and Rab-9 dependent, respectively), depending on the epithelial cell type used. Altogether, this demonstration of a AgNPs-mediated functional dichotomy (down-regulation of IFN-dependent antiviral responses and up-regulation of IL-8-dependent antibacterial responses) may have practical implications for their use in the clinic.

Omega-3 polyunsaturated fatty acids reduce vascular tone and inflammation in human saphenous vein.

Dietary intake of omega-3 polyunsaturated fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), has been reported to have beneficial cardiovascular effects. However, little is known about the effect of EPA and DHA on human vascular tone. Therefore, the aim of this study is to evaluate the effect of EPA and DHA on vascular tone of the human saphenous vein (SV) obtained from patients undergoing coronary bypass operation under normal and inflammatory conditions. Moreover, we aimed to investigate the effect of EPA and DHA on the release of inflammatory mediators from SV. Pretreatment of SV with EPA and DHA (100µM, 18h) decreased the contractile response of SV to norepinephrine (NE) under normal and inflammatory conditions. Moreover, EPA and DHA pretreatment diminished increased Monocyte Chemoattractant Protein-1 (MCP-1) and Tumor Necrosis Factor-alpha (TNF-α) release from SV under inflammatory conditions. In conclusion, our results suggest that EPA and DHA pretreatment may be beneficial to counteract graft vasospasm and vascular inflammation in SV which are important factors in graft failure development. Therefore, dietary intake of EPA and DHA may have potential clinical applications in improving coronary bypass graft patency.

Decreased vasorelaxation induced by iloprost during acute inflammation in human internal mammary artery.

Cyclooxygenase-2 (COX-2) induction in human internal mammary arteries (IMA) under inflammatory conditions has been associated with attenuated norepinephrine (NE)-induced vasoconstriction. This effect was associated with increased prostaglandin (PG) E2 and prostacyclin (PGI2) releases. The present study was designed to assess the role of these PG and their receptors (EP and IP, respectively) on the vascular reactivity during acute inflammation. Isolated IMA were cultured in the absence (Control conditions) or presence (Inflammatory conditions) of both interleukin-1 beta (IL-1ß) and lipopolysaccharide (LPS). The vasorelaxation and the increased content of cyclic adenosine monophosphate (cAMP) induced by iloprost, a PGI2 analogue, were significantly reduced under inflammatory conditions and restored in preparations cultured with the IP antagonist (CAY10441). Decreased cAMP levels under inflammatory conditions are due to at least increased phosphodiesterase (PDE) 4B expression. On the other hand, PGE2, thromboxane analogues and EP agonists-induced vasoconstrictions were not affected under inflammatory conditions. No vasorelaxation was observed with PGD2, PGE2 or the EP2/4 agonists in pre-contracted IMA. Finally, using RT-qPCR and immunohistochemistry, the COX-2, IP receptor and PGI2 synthase (PGIS) were detected. A significant increase of COX-2 and moderate increase of IP mRNA expression was observed under inflammatory conditions, whereas PGIS mRNA level was not affected. This study demonstrates that PGI2/IP receptor signalling and PGI2-induced relaxation are impaired in human IMA during acute inflammation, whereas the responses induced by other prostanoids are not affected. These results could explain some of the mechanisms of vascular dysfunction reported in inflammatory conditions.

Systemic Human ILC Precursors Provide a Substrate for Tissue ILC Differentiation.

Innate lymphoid cells (ILCs) represent innate versions of T helper and cytotoxic T cells that differentiate from committed ILC precursors (ILCPs). How ILCPs give rise to mature tissue-resident ILCs remains unclear. Here, we identify circulating and tissue ILCPs in humans that fail to express the transcription factors and cytokine outputs of mature ILCs but have these signature loci in an epigenetically poised configuration. Human ILCPs robustly generate all ILC subsets in vitro and in vivo. While human ILCPs express low levels of retinoic acid receptor (RAR)-related orphan receptor C (RORC) transcripts, these cells are found in RORC-deficient patients and retain potential for EOMES+ natural killer (NK) cells, interferon gamma-positive (IFN-γ+) ILC1s, interleukin (IL)-13+ ILC2s, and for IL-22+, but not for IL-17A+ ILC3s. Our results support a model of tissue ILC differentiation ("ILC-poiesis"), whereby diverse ILC subsets are generated in situ from systemically distributed ILCPs in response to local environmental signals.

Reverse Regulatory Pathway (H2S / PGE2 / MMP) in Human Aortic Aneurysm and Saphenous Vein Varicosity.

Hydrogen sulfide (H2S) is a mediator with demonstrated protective effects for the cardiovascular system. On the other hand, prostaglandin (PG)E2 is involved in vascular wall remodeling by regulating matrix metalloproteinase (MMP) activities. We tested the hypothesis that endogenous H2S may modulate PGE2, MMP-1 activity and endogenous tissue inhibitors of MMPs (TIMP-1/-2). This regulatory pathway could be involved in thinning of abdominal aortic aneurysm (AAA) and thickening of saphenous vein (SV) varicosities. The expression of the enzyme responsible for H2S synthesis, cystathionine-γ-lyase (CSE) and its activity, were significantly higher in varicose vein as compared to SV. On the contrary, the endogenous H2S level and CSE expression were lower in AAA as compared to healthy aorta (HA). Endogenous H2S was responsible for inhibition of PGE2 synthesis mostly in varicose veins and HA. A similar effect was observed with exogenous H2S and consequently decreasing active MMP-1/TIMP ratios in SV and varicose veins. In contrast, in AAA, higher levels of PGE2 and active MMP-1/TIMP ratios were found versus HA. These findings suggest that differences in H2S content in AAA and varicose veins modulate endogenous PGE2 production and consequently the MMP/TIMP ratio. This mechanism may be crucial in vascular wall remodeling observed in different vascular pathologies (aneurysm, varicosities, atherosclerosis and pulmonary hypertension).

Human perivascular adipose tissue dysfunction as a cause of vascular disease: Focus on vascular tone and wall remodeling.

Obesity is one of the major risk factors for the development of cardiovascular diseases. It is characterized by excessive or abnormal accumulation of adipose tissue, including depots which surround the blood vessels named perivascular adipose tissue (PVAT). PVAT plays endocrine and paracrine roles by producing large numbers of metabolically vasoactive adipokines. The present review outlines our current understanding of the beneficial roles of PVAT in vascular tone and remodeling in healthy subjects supported by clinical studies, highlighting different factors or mechanisms that could mediate protective effects of PVAT on vascular function. Most studies in humans show that adiponectin is the best candidate for the advantageous effect of PVAT. However, in pathological conditions especially obesity-related cardiovascular diseases, the beneficial effects of PVAT on vascular functions are impaired and transform into detrimental roles. This change is defined as PVAT dysfunction. In the current review, the contribution of PVAT dysfunction to obesity-related cardiovascular diseases has been discussed with a focus on possible mechanisms including an imbalance between beneficial and detrimental adipokines (commonly described as decreased levels of adiponectin and increased levels of leptin or tumor necrosis factor-alpha (TNFα)), increased quantity of adipose tissue, inflammation, cell proliferation and endothelial dysfunction. Finally, novel pharmacotherapeutic targets for the treatment of cardiovascular and metabolic disorders are addressed.

Decreased PGE2 content reduces MMP-1 activity and consequently increases collagen density in human varicose vein.

UNLABELLED: Varicose veins are elongated and dilated saphenous veins. Despite the high prevalence of this disease, its pathogenesis remains unclear. AIMS: In this study, we investigated the control of matrix metalloproteinases (MMPs) expression by prostaglandin (PG)E2 during the vascular wall remodeling of human varicose veins. METHODS AND RESULTS: Varicose (small (SDv) and large diameter (LDv)) and healthy saphenous veins (SV) were obtained after surgery. Microsomal and cytosolic PGE-synthases (mPGES and cPGES) protein and mRNA responsible for PGE2 metabolism were analyzed in all veins. cPGES protein was absent while its mRNA was weakly expressed. mPGES-2 expression was similar in the different saphenous veins. mPGES-1 mRNA and protein were detected in healthy veins and a significant decrease was found in LDv. Additionally, 15-hydroxyprostaglandin dehydrogenase (15-PGDH), responsible for PGE2 degradation, was over-expressed in varicose veins. These variations in mPGES-1 and 15-PGDH density account for the decreased PGE2 level observed in varicose veins. Furthermore, a significant decrease in PGE2 receptor (EP4) levels was also found in SDv and LDv. Active MMP-1 and total MMP-2 concentrations were significantly decreased in varicose veins while the tissue inhibitors of metalloproteinases (TIMP -1 and -2), were significantly increased, probably explaining the increased collagen content found in LDv. Finally, the MMP/TIMP ratio is restored by exogenous PGE2 in varicose veins and reduced in presence of an EP4 receptor antagonist in healthy veins. CONCLUSIONS: In conclusion, PGE2 could be responsible for the vascular wall thickening in human varicose veins. This mechanism could be protective, strengthening the vascular wall in order to counteract venous stasis.

A comparative study of PGI2 mimetics used clinically on the vasorelaxation of human pulmonary arteries and veins, role of the DP-receptor.

Prostacyclin (PGI2) and its mimetics (iloprost, treprostinil, beraprost and MRE-269) are potent vasodilators (via IP-receptor activation) and a major therapeutic intervention for pulmonary hypertension (PH). These PGI2 mimetics have anti-proliferative and potent vasodilator effects on pulmonary vessels. We compared the relaxant effects induced by these recognized IP-agonists in isolated human pulmonary arteries (HPA) and veins (HPV). In addition, using selective antagonists, the possible activation of other prostanoid relaxant receptors (DP, EP4) was investigated. Iloprost and treprostinil were the more potent relaxant agonists when both vessels were analyzed. HPA were significantly more sensitive to iloprost than to treprostinil, pEC50 values: 7.94±0.06 (n=23) and 6.73±0.08 (n=33), respectively. In contrast, in HPV these agonists were equipotent. The relaxations induced by treprostinil were completely or partially inhibited by IP-antagonists in HPA or HPV, respectively. The effects of the IP-agonists were not significantly modified by the EP4 antagonist. Finally, DP-antagonists inhibited the relaxations induced by treprostinil in HPV, suggesting that the DP-receptor plays a role in treprostinil-induced relaxation in the HPV. These data suggest that iloprost and treprostinil should be the most effective clinically available agonists to decrease pulmonary vascular resistance and to prevent oedema formation (by similar decrease in HPA and HPV resistance) in PH patients.

The cyclooxygenase-2-prostaglandin E2 pathway maintains senescence of chronic obstructive pulmonary disease fibroblasts.

RATIONALE: Chronic obstructive pulmonary disease (COPD) is associated with lung fibroblast senescence, a process characterized by the irreversible loss of replicative capacity associated with the secretion of inflammatory mediators. However, the mechanisms of this phenomenon remain poorly defined. OBJECTIVES: The aim of this study was to analyze the role of prostaglandin E2 (PGE2), a prostaglandin known to be increased in COPD lung fibroblasts, in inducing senescence and related inflammation in vitro in lung fibroblasts and in vivo in mice. METHODS: Fibroblasts were isolated from patients with COPD and from smoker and nonsmoker control subjects. Senescence markers and inflammatory mediators were investigated in fibroblasts and in mice. MEASUREMENTS AND MAIN RESULTS: Lung fibroblasts from patients with COPD exhibited higher expression of PGE2 receptors EP2 and EP4 as compared with nonsmoker and smoker control subjects. Compared with both nonsmoker and smoker control subjects, during long-term culture, COPD fibroblasts displayed increased senescent markers (increased senescence associated-ß galactosidase activity, p16, and p53 expression and lower proliferative capacity), and an increased PGE2, IL-6, IL-8, growth-regulated oncogene (GRO), CX3CL1, and matrix metalloproteinase-2 protein and cyclooxygenase-2 and mPGES-1 mRNA expression. Using in vitro pharmacologic approaches and in vivo experiments in wild-type and p53(-/-) mice we demonstrated that PGE2 produced by senescent COPD fibroblasts is responsible for the increased senescence and related inflammation. PGE2 acts either in a paracrine or autocrine fashion by a pathway involving EP2 and EP4 prostaglandin receptors, cyclooxygenase-2-dependent reactive oxygen species production and signaling, and consecutive p53 activation. CONCLUSIONS: PGE2 is a critical component of an amplifying and self-perpetuating circle inducing senescence and inflammation in COPD fibroblasts. Modulating the described PGE2 signaling pathway could provide a new basis to dampen senescence and senescence-associated inflammation in COPD.

Absence of inflammatory conditions in human varicose saphenous veins.

INTRODUCTION: Varicose veins affect one-third of the adult population in western countries, but their pathogenesis is incompletely characterized. One of the most controversial issues is the role of inflammation. It is well known that inflammation involves an increased expression/activity of inflammatory mediators. OBJECTIVE: The aim of this study was to investigate the presence or absence of mediators of inflammation in varicose as compared to healthy veins. METHODS AND RESULTS: Using immunohistofluorescence on varicose and healthy veins, we investigated the presence of inflammatory cells. They were not detectable. Venous wall C-reactive protein (CRP), fibrinogen (EIA) and pentraxin-3 (Western blot) content were measured. CRP was significantly lower in varicose veins, but no difference was found for fibrinogen or pentraxin-3 between varicose and healthy veins. No difference was observed for enzymes involved in inflammation and responsible for arachidonic acid metabolism such as the acute phase reactant secreted phospholipase A2-IIA and cyclooxygenase-2, as determined in varicose and healthy veins by Western blot and real-time qRT-PCR. CONCLUSIONS: Our experiments demonstrate no increase in the presence of mediators of inflammation in varicose as compared to healthy veins, suggesting that inflammation may not be an important contributor to the pathogenesis of varicose veins.

Prostaglandin E2 induced contraction of human intercostal arteries is mediated by the EP3 receptor.

Arterial vascularization of the spinal cord may be mechanically or functionally altered during thoraco-abdominal surgery/intravascular procedures. Increased arterial pressure has been shown to restore spinal perfusion and function probably by increasing the blood flow through the intercostal arteries. The regulation of human intercostal artery (HICA) vascular tone is not well documented. Prostaglandin (PG)E(2) concentration is increased during inflammatory conditions and has been shown to regulate vascular tone in many preparations. In this context, the pharmacological response of HICA to PGE(2) and the characterization of the PGE(2) receptor subtypes (EP(1), EP(2), EP(3) or EP(4)) involved are of importance and that is the aim of this study. Rings of HICA were prepared from 29 patients and suspended in organ baths for isometric recording of tension. Cumulative concentration-response curves were performed in these preparations with various EP receptor agonists in the absence or presence of different receptor antagonists or inhibitors. PGE(2) induced the contraction of HICA (E(max)=7.28 ± 0.16 g; pEC(50) value=0.79 ± 0.18; n=17); contractions were also observed with the EP(3) receptor agonists, sulprostone, 17-phenyl-PGE(2), misoprostol or ONO-AE-248. In conclusion, PGE(2) induced vasoconstriction of HICA via EP(3) receptor subtypes and this result was confirmed by the use of selective EP receptor antagonists (L-826266, ONO-8713, SC-51322) and by a strong detection of EP(3) mRNA. These observations suggest that in the context of perioperative inflammation, increased PGE(2) concentrations could trigger vasoconstriction of HICA and possibly alter spinal vascularization.

Effect of cold storage on cholinergic responses induced by electrical field stimulation in human bronchi.

The aim of the present study was to examine the effects of cold storage on the responses induced by electrical field stimulation (EFS) in human bronchial preparations. Responses induced by EFS and acetylcholine were studied in human bronchial rings mounted in organ baths, either on the day of surgery or after storage at 4 degrees C in Krebs-Henseleit solution for 24 and 48 h, respectively. The responses induced by EFS were studied at different voltages (20, 40 and 60 V) and at a range of frequencies (2, 4, 8, 10, 30 and 60 Hz). EFS induced a triphasic response, consisting of a cholinergic contraction, followed by a relaxation and subsequently a slow sustained contraction. The amplitude of the EFS-induced response was enhanced with increasing voltages and increasing frequencies. None of the three EFS-induced phases were significantly altered by cold storage at 24h, whereas storage for 48 h significantly decreased the reactivity of the preparations. Likewise, the contractions induced by acetylcholine were unaltered after 24h, but significantly depressed after 48 h. These results suggest that the reactivity of human bronchial preparations to EFS is not altered when tissues are conserved for 24h, whereas prolonged storage should be avoided.

Vasoconstriction induced by activation of EP1 and EP3 receptors in human lung: effects of ONO-AE-248, ONO-DI-004, ONO-8711 or ONO-8713.

This study investigated the effects and selectivity of ONO-AE-248, ONO-DI-004, ONO-8711 and ONO-8713 on EP1 and EP3 receptors in human pulmonary vessels. The prostanoid receptors involved in the vasoconstriction of human pulmonary arteries (HPA) are TP and EP3 whereas in pulmonary veins (HPV), this response is associated with TP and EP1. The experiments were performed in presence of BAY u3405 (TP antagonist). ONO-DI-004 (EP1 agonist) and ONO-AE-248 (EP3 agonist), exhibited little or no activity in HPV whereas contractions were induced in HPA with ONO-AE-248. In HPV, the contractions produced with sulprostone (EP1,3 agonist) were blocked in a non competitive manner by both EP1 antagonists (ONO-8711, 30 microM; ONO-8713, 10 microM). The involvement of EP1 mediated contraction in HPV was also observed during the vasorelaxations induced with PGE1 and 5-cis-carba-PGI2. In pre-contracted HPV treated with AH6809 (30 microM; EP1 antagonist) the PGE1 vasorelaxations were potentiated, while unchanged in HPA. These results demonstrate the selectivity of ONO-AE-248 for the EP3 receptor in HPA, ONO-DI-004 was ineffective on the EP1 receptor present in HPV while ONO-8713 was the more potent EP1 antagonist used in this tissue.

The quest for new cysteinyl-leukotriene and lipoxin receptors: recent clues.

The metabolism of arachidonic acid via the 5-lipoxygenase enzymatic pathway leads to the formation of the cysteinyl-leukotrienes and lipoxins, which have been implicated in several inflammatory reactions. While these lipid mediators are responsible for a variety of effects, their actions occur through the activation of 3 specific types of cloned receptors (i.e., CysLT(1), CysLT(2), and ALX). Although receptor activation can explain several biological actions associated with the mediators, there is some evidence to suggest that not all responses fit the well-known characteristics of these cloned receptors. Other receptor subtypes may also exist. Interestingly, the indirect evidence for support of this observation is principally derived from work performed on either blood elements and/or vascular smooth muscle. Because the initiating events associated with inflammation are essentially of vascular origin, further work at the molecular level may be necessary to confirm the data, which do not fit the well-known CysLT and ALX receptor profiles.