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Pulmonary arterial hypertension (PAH) is commonly associated with chronic hypoxemia in disorders such as chronic obstructive pulmonary disease (COPD). Prostacyclin analogs are widely used in the management of PAH patients; however, clinical efficacy and long-term tolerability of some prostacyclin analogs may be compromised by concomitant activation of the E-prostanoid 3 (EP3) receptor. Here, we found that EP3 expression is upregulated in pulmonary arterial smooth muscle cells (PASMCs) and human distal pulmonary arteries (PAs) in response to hypoxia. Either pharmacological inhibition of EP3 or Ep3 deletion attenuated both hypoxia and monocrotaline-induced pulmonary hypertension and restrained extracellular matrix accumulation in PAs in rodent models. In a murine PAH model, Ep3 deletion in SMCs, but not endothelial cells, retarded PA medial thickness. Knockdown of EP3α and EP3β, but not EP3γ, isoforms diminished hypoxia-induced TGF-β1 activation. Expression of either EP3α or EP3β in EP3-deficient PASMCs restored TGF-β1 activation in response to hypoxia. EP3α/β activation in PASMCs increased RhoA-dependent membrane type 1 extracellular matrix metalloproteinase (MMP) translocation to the cell surface, subsequently activating pro-MMP-2 and promoting TGF-β1 signaling. Activation or disruption of EP3 did not influence PASMC proliferation. Together, our results indicate that EP3 activation facilitates hypoxia-induced vascular remodeling and pulmonary hypertension in mice and suggest EP3 inhibition as a potential therapeutic strategy for pulmonary hypertension., Introduction Pulmonary arterial hypertension (PAH), a rare but often fatal disease characterized by an average pulmonary arterial (PA) pressure of greater than 25 mmHg, contributes to unacceptably high morbidity and [...]

Selective cyclooxygenase-2 (COX-2) inhibitors (coxibs) increase the incidence of cardiovascular and cerebrovascular events. Complete disruption of the murine gene encoding COX-2 (Ptgs2) leads to renal developmental problems, as well as female reproductive anomalies and patent ductus arteriosus of variable penetrance in newborns, thus rendering this genetic approach difficult to compare with coxib administration. Here, we created hypomorphic Ptgs2 (COX-[2.sup.Neo/Neo]) mice in which COX-2 expression is suppressed to an extent similar to that achieved with coxibs, but not eliminated, in an attempt to circumvent these difficulties. In LPS-challenged macrophages and cytokine-stimulated endothelial cells obtained from COX-[2.sup.Neo/Neo] mice, COX-2 expression was reduced 70-90%, and these mice developed a mild renal phenotype compared with COX-2 mice possessing an active site mutation (COX-[2.sup.Y383F/Y385F]), with minimal signs of renal dysfunction as measured by FITC-inulin clearance and blood urea nitrogen. These COX-2 knockdown mice displayed an increased propensity for thrombogenesis compared with their wild-type (COX-[2.sup.+/+]) littermates observed by intravital microscopy in cremaster muscle arterioles upon ferric chloride challenge. Measurement of urinary prostanoid metabolites indicated that COX-[2.sub.Neo/Neo] mice produced 50% less prostacyclin but similar levels of PG[E.sub.2] and thromboxane compared with COX-[2.sup.+/+] mice in the absence of any blood pressure and ex vivo platelet aggregation abnormalities. COX-[2.sup.Neo/Neo] mice, therefore, provide a genetic surrogate of coxib therapy with disrupted prostacyclin biosynthesis that predisposes to induced arterial thrombosis. prostaglandin synthase; thrombosis; prostacyclin; macrophage; induced mutant mice; kidney

Author(s): Ying Yu [1]; Jinjin Fan [1]; Xin-Sheng Chen [1, 5]; Dairong Wang [1]; Andres J Klein-Szanto [2]; Robert L Campbell [3]; Garret A FitzGerald [1]; Colin D Funk (corresponding [...]

We investigated the mechanisms by which inhibitors of prostaglandin G/H synthase-2 (PGHS-2; known colloquially as COX-2) increase the incidence of myocardial infarction and stroke. These inhibitors are believed to exert [...]

Activation of the 5-lipoxygenase (5-LO) pathway leads to the biosynthesis of proinflammatory leukotriene lipid mediators. Genetic studies have associated 5-LO and its accessory protein, 5-LO-activating protein, with cardiovascular disease, myocardial infarction and stroke. Here we show that 5-LO-positive macrophages localize to the adventitia of diseased mouse and human arteries in areas of neoangiogenesis and that these cells constitute a main component of aortic aneurysms induced by an atherogenic diet containing cholate in mice deficient in apolipoprotein E. 5-LO deficiency markedly attenuates the formation of these aneurysms and is associated with reduced matrix metalloproteinase-2 activity and diminished plasma macrophage inflammatory protein-1[alpha] (MIP-1[alpha]; also called CCL3), but only minimally affects the formation of lipid-rich lesions. The leukotriene LTD[sub.4] strongly stimulates expression of MIP-1[alpha] in macrophages and MIP-2 (also called CXCL2) in endothelial cells. These data link the 5-LO pathway to hyperlipidemia-dependent inflammation of the arterial wall and to pathogenesis of aortic aneurysms through a potential chemokine intermediary route., Author(s): Lei Zhao [1]; Michael P W Moos [2]; Rolf Grabner [2]; Frederique Pedrono [1, 3]; Jinjin Fan [1]; Brigitte Kaiser [2]; Nicole John [2]; Sandra Schmidt [2]; Rainer Spanbroek [...]

Cysteinyl leukotrienes (CysLTs) exert potent proinflammatory actions and contribute to many of the symptoms of asthma. Using a model of allergic sensitization and airway challenge with Aspergillus fumigatus (Af), we have found that Th2-type inflammation and airway hyperresponsiveness (AHR) to methacholine (MCh) were associated with increased LTD4 responsiveness in mice. To explore the importance of increased CysLT signaling in airway smooth muscle function, we generated transgenic mice that overexpress the human CysLT1 receptor (hCysL[T.sub.1]R) via the [alpha]-actin promoter. These receptors were expressed abundantly and induced intracellular calcium mobilization in airway smooth muscle cells from transgenic mice. Force generation in tracheal ring preparations ex vivo and airway reactivity in vivo in response to LT[D.sub.4] were greatly amplified in hCysL[T.sub.1]R-overexpressing mice, indicating that the enhanced signaling induces coordinated functional changes of the intact airway smooth muscle. The increase of AHR imposed by overexpression of the hCysL[T.sub.1]R was greater in transgenic BALB/c mice than in transgenic B6 x SJL mice. In addition, sensitization- and challenge-induced increases in airway responsiveness were significantly greater in transgenic mice than that of nontransgenic mice compared with their respective nonsensitized controls. The amplified AHR in sensitized transgenic mice was not due to an enhanced airway inflammation and was not associated with similar enhancement in MCh responsiveness. These results indicate that a selective hCysL[T.sub.1]R-induced contractile mechanism synergizes with allergic AHR. We speculate that hCysL[T.sub.1]R signaling contributes to a hypercontractile state of the airway smooth muscle. asthma; allergic airway inflammation

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is highly expressed in macrophages from thioglycollate-elicited peritonitis. Cytokines and other factors known to control macrophage differentiation and function were evaluated to determine their potential effects on PPAR-gamma expression. Interleukin-4 is shown to induce the expression of PPAR-gamma and 12-15-lipoxygenase mediates interleukin-4-dependent transcription of the CD36 gene in macrophages.

The responsiveness of wild-type (WT) and 5-lipooxygenase (5-LO) -/- mice to ovalbumin sensitization and airway inflammation was analyzed to characterize the role of 5-LO in airway responsiveness. The ovalbumin sensitization of mice resulted in the production of specific IgE and increased nonspecific ariway reactivity to methacholine. Furthermore, 5-LO-deficient mice responded to ovalbumin with a diminished immunoglobulin response.

The role of interleukin-4 (IL-4) in parasitic worm expulsion during mastocytosis was analyzed in the intestinal smooth muscles and mast cells of BALB/c mice, mast cell-deficient W/Wv mice and lypoxygenase-deficient mice. Analysis of intestinal longitudinal muscles isolated from mice subjected toIL-4 treatment enhanced intestinal response to nerve stimulation. However, the stimulatory effects of IL-4 treatment was attenuated in mast cell-deficient mice and W/Wv mice which failed to express c-kit.