Effects of the Peroxisome Proliferator-Activated Receptor-γ Agonist Pioglitazone on Peripheral Vessel Function and Clinical Parameters in Nondiabetic Patients: A Double-Center, Randomized Controlled Pilot Trial.

OBJECTIVE: Despite the advanced therapy with statins, antithrombotics, and antihypertensive agents, the medical treatment of atherosclerotic disease is less than optimal. Therefore, additional therapeutic antiatherosclerotic options are desirable. This pilot study was performed to assess the potential antiatherogenic effect of the peroxisome proliferator-activated receptor-γ agonist pioglitazone in nondiabetic patients. METHODS: A total of 54 nondiabetic patients were observed in a prospective, double-blind, placebo-controlled study. Patients were randomized to pioglitazone or placebo. The following efficacy parameters were determined by serial analyses: artery pulse wave analysis and carotid-femoral pulse wave velocity (PWV), static and dynamic retinal vessel function, and the common carotid intima-media thickness (IMT). The main secondary endpoint was the change in different biochemical markers. RESULTS: After 9 months, no relevant differences could be determined in the two treatment groups in PWV (pioglitazone 14.3 ± 4.4 m/s vs. placebo 14.2 ± 4.2 m/s), retinal arterial diameter (pioglitazone 112.1 ± 23.3 µm vs. placebo 117.9 ± 21.5 µm) or IMT (pioglitazone 0.85 ± 0.30 mm vs. placebo 0.79 ± 0.15 mm). Additionally, there were no differences in the change in biochemical markers like cholesteryl ester transfer protein, low-density lipoprotein cholesterol, high-sensitivity C-reactive protein or white blood cell count. CONCLUSIONS: Treatment with a peroxisome proliferator-activated receptor-γ agonist in nondiabetic patients did not improve the function of large and small peripheral vessels (PPP Trial, clinicaltrialsregister.eu: 2006-000186-11).

Effects of the PPARγ agonist pioglitazone on coronary atherosclerotic plaque composition and plaque progression in non-diabetic patients: a double-center, randomized controlled VH-IVUS pilot-trial.

Despite the advanced therapy with statins, antithrombotics and antihypertensive agents, the medical treatment of coronary artery disease is less than optimal. Therefore, additional therapeutic anti-atherosclerotic options are desirable. This VH-IVUS study (intravascular ultrasonography with virtual histology) was performed to assess the potential anti-atherogenic effect of the PPARγ agonist pioglitazone in non-diabetic patients. A total of 86 non-culprit atherosclerotic lesions in 54 patients with acute coronary syndrome were observed in a 9-month prospective, double-blind, and placebo-controlled IVUS study. Patients were randomized to receive either 30 mg pioglitazone (Pio) or placebo (Plac). As primary efficacy parameter, the change of relative plaque content of necrotic core was determined by serial VH-IVUS analyses. Main secondary endpoint was the change of total plaque volume. In contrast to placebo, in the pioglitazone-treated group, the relative plaque content of necrotic core decreased significantly (Pio -1.3 ± 6.9% vs. Plac +2.6 ± 6.5%, p < 0.01). In comparison to the placebo group, the plaques in pioglitazone-treated patients showed significantly greater reduction of the total plaque volume (Pio -16.1 ± 26.4 mm3 vs. Plac -1.8 ± 30.9 mm3, p = 0.02). Treatment with a PPARγ agonist in non-diabetic patients results in a coronary artery plaque stabilization on top of usual medical care.

Pharmacological postconditioning by bolus injection of phosphodiesterase-5 inhibitors vardenafil and sildenafil.

Postconditioning enables cardioprotection against ischemia/reperfusion injury either by application of short, repetitive ischemic periods or by pharmacological intervention prior to reperfusion. Pharmacological postconditioning has been described for phosphodiesterase-5 inhibitors when the substances were applied as a permanent infusion. For clinical purposes, application of a bolus is more convenient. In a rat heart in situ model of ischemia reperfusion vardenafil or sildenafil were applied as a bolus prior to reperfusion. Cardioprotective effects were found over a broad dosage range. In accordance with current hypotheses on pharmacological postconditioning signaling, the protective effect was mediated by extracellular signal-regulated kinase and protein kinase C pathway. Interestingly, the extent of protection was independent of the concentration applied for both substances. Full protection comparable to ischemic postconditioning was reached with half-maximal human equivalence dose. In contrast, mean arterial pressure dropped upon bolus application in a dose-dependent manner. Taken together, the current study extends previous findings obtained in a permanent infusion model to bolus application. This is an important step toward clinical application of pharmacological postconditioning with sildenafil and vardenafil, especially because the beneficial effects were proven for concentrations with reduced hemodynamic side effects compared to the dosage applied for erectile dysfunction treatment.

Uncoupled eNOS annihilates neuregulin-1ß-induced cardioprotection: a novel mechanism in pharmacological postconditioning in myocardial infarction.

Myocardial infarct size can be limited by pharmacological postconditioning (pPC) with cardioprotective agents. Cardioprotective effects of neuregulin-1ß (NRG) via activation of protein kinase B (Akt) and downstream pathways like endothelial nitric oxide synthase (eNOS) have been postulated based on results from cell culture experiments. The purpose of this study was to investigate if eNOS may be involved in pPC with NRG. NRG application in an ex vivo mouse model (C57Bl6) of ischemia-reperfusion injury was analyzed. Unexpectedly, the infarct size increased when NRG was infused starting 5 min prior to reperfusion, even though protective Akt and GSK3ß phosphorylation were enhanced. In eNOS deficient mice, however, NRG significantly reduced the infarct size. Co-infusion of NRG and L-arginine (Arg) lead to a reduction in infarct size in wild type animals. Electron paramagnetic resonance measurements revealed that NRG treatment prior to reperfusion leads to an enhanced release of reactive oxygen species compared to controls and this effect is blunted by co-infusion of Arg. This study documents the cardioprotective mechanisms of NRG signaling to be mediated by GSK3ß inactivation. This is the first study to show that this protection fails in situations with dysfunctional eNOS. In eNOS deficient mice NRG exerts its protective effect via the GSK3ß pathway, suggesting that the eNOS can limit cardioprotection. As dysfunctional eNOS has been described in cardiovascular risk factors like diabetes, hypertension, and hypercholesterolemia these findings can help to explain lack of postconditioning performance in models of cardiovascular co-morbidities.

Inhibition of anti-apoptotic signals by Wortmannin induces apoptosis in the remote myocardium after LAD ligation: evidence for a protein kinase C-δ-dependent pathway.

It has been shown that, in the remote myocardium after infarction (MI), protein kinase C (PKC) inhibition reduces apoptosis both by blocking proapoptotic pathways and by activating antiapoptotic signals including the Akt pathway. However, it was open if vice versa, blockade of antiapoptotic pathways may influence proapoptotic signals. To clarify this, the present study tested the effects of the PI3-kinase blocker Wortmannin on proapoptotic signals and on apoptosis execution in the remote myocardium after infarction. Rats were subjected to MI by LAD ligation in situ. Some were pre-treated with Wortmannin alone or in combination with the PKC inhibitor Chelerythrine. After 24 h, pro- and anti-apoptotic signals (caspase-3, PKC isoforms, p38-MAPK, p42/44-MAPK, Akt, Bad), and marker of apoptosis execution (TUNEL) were quantified in the myocardium remote from the infarction. Wortmannin treatment increased apoptosis in the remote myocardium both at baseline and after MI, together with an activation of the PKC-δ/p38-MAPK-pathway. PKC-ε and p42/44-MAPK were unaffected. Combined treatment with Wortmannin and Chelerythrine fully reversed the pro-apoptotic effects of Wortmannin both at baseline and after MI. The PKC-δ-p38-MAPK-pathway as a strong signal for apoptosis in the non-infarcted myocardium can be influenced by targeting the anti-apoptotic PI3-kinase pathway. This gives evidence of a bi-directional crosstalk of pro- and anti-apoptotic signals after infarction.

Cardioprotection by ischemic postconditioning is abrogated in hypertrophied myocardium of spontaneously hypertensive rats.

PURPOSE: This study examines if ischemic postconditioning is preserved in hypertrophied myocardium of spontaneously hypertensive rats (SHR). METHODS: Infarct sizes, hemodynamic, morphometric, and biochemical parameters were obtained from normotensive controls [Wistar-Kyoto (WKY) rats] and compared with SHRs. In open-chest rats, the infarct size was determined after 30 minutes of regional ischemia. Postconditioning was performed by 3 cycles of ischemia/reperfusion with 30 seconds each or 6 cycles of ischemia/reperfusion with 10 seconds each immediately after the infarction. RESULTS: Infarct size was comparable between control rats and SHRs. In WKY rats, postconditioning reduced the infarct size significantly. However, in SHRs, the postconditioning effect was completely lost for both postconditioning protocols. Even shortening of the ischemic period to 20 minutes did not restore the infarct sparing effect in SHRs. The phosphorylation of glycogen synthase kinase 3ß increased 2.1-fold by ischemic postconditioning in WKY rats; however, this increase was completely absent in SHRs with both postconditioning protocols. CONCLUSIONS: Myocardial hypertrophy inhibits the protection by postconditioning in an experimental animal model. Future studies have to clarify whether this result can be extrapolated to patients with arterial hypertension and myocardial hypertrophy.

Dexrazoxane prevents the development of the impaired cardiac phenotype in caveolin-1-disrupted mice.

: Caveolin-1-deficient (cav1) mice display a severely diseased cardiac phenotype with systolic and diastolic heart failure. Accumulating evidence supports a causative role of uncoupled endothelial nitric oxide synthase in the development of these abnormalities. Interestingly, a similar molecular mechanism was proposed for anthracycline-induced cardiomyopathy. Currently, dexrazoxane is approved for the prevention of anthracycline-induced cardiomyopathy. Given the molecular similarities between the anthracycline-induced cardiomyopathy and the cardiomyopathy in cav1 mice, we questioned whether dexrazoxane may also prevent the evolution of the cardiac pathologies in cav1 mice. We evaluated dexrazoxane treatment for 6 weeks in cav1 mice and wild-type controls. This study provides the first evidence for a reduced reactive oxygen species formation in the vessels of dexrazoxane-treated cav1 mice. This reduced oxidative stress resulted in a markedly reduced rate of apoptosis, which finally was translated into a significantly improved heart function in dexrazoxane-treated cav1 mice. These hemodynamic improvements were accompanied by significantly lowered proatrial natriuretic peptide levels. Notably, these protective properties of dexrazoxane were not evident in wild-type animals. Taken together, these novel findings indicate that dexrazoxane significantly reduces vascular reactive oxygen species formation cav1. Because this is paralleled by an improved cardiac performance in cav1 mice, our data suggest dexrazoxane as a novel therapeutic strategy in this specific cardiomyopathy.

Postconditioning with levosimendan reduces the infarct size involving the PI3K pathway and KATP-channel activation but is independent of PDE-III inhibition.

Reperfusion injury is strongly involved in the loss of functional heart tissue in patients after acute myocardial infarction. Various signal transduction pathways to reduce infarct size during reperfusion have been characterized. However, so far in the clinical setting no standard therapies are applied due to the lack of suitable drugs. Levosimendan, a calcium sensitizer, has been shown to improve survival in cardiogenic shock after infarction. Focus of the present study was to address the question, whether a bolus application of levosimendan prior to reperfusion is able to reduce the infarct size. A well-characterized model, the in vivo rat model, was used and levosimendan applied 5 min prior to reperfusion after 30-min occlusion of the left coronary artery followed by a 30-min reperfusion period. This pharmacological postconditioning was compared to the ischemic postconditioning with three times occlusion/reperfusion periods of 30 s each. To further address the question if in this in vivo model the phosphatidylinositol 3-kinase (PI3K) pathway may be involved, the PDE-III inhibiting property of levosimendan was compared to the PDE-III inhibitor enoximone. Ischemic postconditioning significantly reduced the infarct size from 48 +/- 2 to 32 +/- 1% of the area at risk (P < 0.05). Similarly, levosimendan decreased infarct size down to 29 +/- 3%. The combination of ischemic postconditioning and pharmacological postconditioning using levosimendan did not result in a further reduction of the infarct size. Both, the mitochondrial KATP-channel blocker 5-hydroxydecanoate (5-HD) and the PI3K inhibitor wortmannin abolished the protection afforded by levosimendan completely, while the inhibitors alone did not influence the infarct size in control hearts. Pharmacological postconditioning with enoximone did not result in any infarct size reduction. Postconditioning with levosimendan significantly increased the phosphorylation of protein kinase B (Akt) and glycogen synthase kinase-3beta (GSK-3beta) at 5 min of reperfusion, an effect which could be blocked completely by the additional administration of wortmannin. In conclusion, levosimendan applied prior to reperfusion in acute myocardial infarction significantly reduces the infarct size in an in vivo rat model. This protection involves the PI3K pathway and the activation of mitochondrial KATP-channels, but is independent of PDE-III inhibition. This finding may open new possibilities for the treatment of patients with acute myocardial infarction using levosimendan, which is an already established therapy in cardiogenic shock. Whether the reduction of mortality in cardiogenic shock by levosimendan may in part be based on this postconditioning effect remains to be elucidated in clinical setting.

Nitric oxide synthases are crucially involved in the development of the severe cardiomyopathy of caveolin-1 knockout mice.

Targeted ablation of caveolin-1 (cav-1) results in a severe cardiomyopathy. How the loss of cav-1 mediates these abnormalities is currently under investigation. Mounting evidence indicates that cav-1 acts as a negative regulator of endothelial nitric oxide synthase resulting in a constitutive hyperactivation of the nitric oxide (NO)-pathway in cav-1 knockout mice (cav-1 ko). In this context we hypothesized that disturbed NO signalling is implicated in these changes. To explore this question cav-1 ko were compared with knockout counterparts experiencing 2 month postnatal NO synthase inhibition by N(G)-nitro-l-arginine methyl ester (l-NAME) treatment. Chronic l-NAME treatment resulted in significant improvements in heart function and exercise capacity in cav-1 ko. Furthermore, we found evidence for an enhanced radical stress in hearts of cav-1 ko which was markedly reduced by l-NAME treatment. Collectively, these findings suggest that NO synthases play a crucial role in the evolution of heart failure evident in cav-1 ko.

Endothelial Nitric Oxide Synthase-Induced Hypertrophy and Vascular Dysfunction Contribute to the Left Ventricular Dysfunction in Caveolin-1-/- Mice.

BACKGROUND: Caveolin-1 (Cav1)-/- mice display impaired development of left ventricular pressure and increased left ventricular wall thickness but no dilated ventricle; these are typical findings in patients with heart failure with preserved ejection fraction (HfpEF). Aiming to clarify if dysfunctional endothelial nitric oxide synthase (eNOS) influences cardiomyocyte contractility, cardiac conduction system, or afterload/vascular resistance, we studied Cav1-/-/eNOS-/- mice. METHODS: Cardiac function was assessed in vivo by pressure-volume-catheterization of the left ventricle, echocardiography and electrocardiography. In addition, isolated tissue experiments were performed to evaluate cardiomyocyte contractility (atria) and vessel morphology and function (aorta). Histology, immunoblotting and quantitative polymerase chain reaction were applied to characterise radical formation and oxidative stress in the heart. RESULTS: Cardiac hypertrophy was completely reversed in Cav1-/-/eNOS-/- mice. The impaired pump function in Cav1-/- mice was significantly improved in Cav1-/-/eNOS-/- mice, but no complete alignment with eNOS-/- controls was achieved, indicating an additional eNOS-independent mechanism contributing to HFpEF in Cav1-/- mice. It is unlikely that frequently occurring arrhythmias contributed to HFpEF in Cav1-/- mice. In contrast, numerous eNOS-dependent and eNOS-independent vascular abnomalities could explain the cardiac phenotypes of Cav1-/- mice. CONCLUSIONS: Synergistic effects between eNOS-related cardiac hypertrophy and vascular hypercontractility appear to underlie the left ventricular dysfunction in Cav1-/-mice. These findings provide insights relevant to the poorly understood pathophysiology of HFpEF.

Subclinical Myocardial Impairment Occurred in Septal and Anterior LV Wall Segments After Anthracycline-Embedded Chemotherapy and did not Worsen During Adjuvant Trastuzumab Treatment in Breast Cancer Patients.

In a previous study of breast cancer patients, we found changes in cardiac function and size during the early stages of adjuvant trastuzumab (Herceptin(®)) therapy. Here we present a subgroup analysis of this patient cohort. This subgroup received a anthracycline-embedded chemotherapy followed by at least 3 months up to 6 months of adjuvant Herceptin(®) therapy. Twenty-seven female breast cancer patients with Her-2/-neu overexpression were studied using conventional echocardiography and 2D speckle tracking. These methods were done before anthracycline-embedded chemotherapy, before adjuvant trastuzumab therapy, and both 3 and 6 months after the start of the therapy (T3, T6). The LV-EF (Simpson biplane) decreased significantly from before the chemotherapy to after the chemotherapy and further decreased after 3 months of trastuzumab therapy (66.2 ± 1.5 vs. 58.7 ± 1.2 vs. 55.6 ± 1.3 vs. 55.9 ± 1.5 %; p < 0.05). The stroke volume index remained constant after chemotherapy (22.0 ± 0.8 vs. 22.6 ± 1.3 ml/m(2); p = 0.9), but increased significantly during trastuzumab therapy (26.7 ± 1.1 and 27.3 ± 1.0 ml/m(2); p < 0.01). Global longitudinal strain exclusively decreased during chemotherapy (-21.0 ± 0.5 vs. -18.9 ± 0.5 %, p < 0.001). Regional longitudinal strain decreased significantly after chemotherapy in septal, anteroseptal, anterolateral, and apex segments. Mitral valve regurgitation increased during the whole treatment, but especially during trastuzumab. Right ventricular function decreased exclusively during chemotherapy. Anthracycline-embedded chemotherapy in patients with breast cancer led to a decrease in LV function, especially of the septal and anterior segments, and did not worsen during adjuvant trastuzumab treatment.

In situ postconditioning with neuregulin-1ß is mediated by a PI3K/Akt-dependent pathway.

BACKGROUND: The myocardial infarct size can be reduced by pharmacological postconditioning using cardioprotective agents. Neuregulin-1ß is a potential candidate, but previous studies in an isolated heart model of ischemia and reperfusion displayed controversial results. An in situ model of ischemia/reperfusion was used to clarify whether the remote application of neuregulin-1ß can reduce the reperfusion injury. A second aim was to evaluate, if the effects are specific for reperfused tissue or if this is a general antiapoptotic effect. In addition, the contributing molecular mechanisms were investigated. METHODS: In an open chest model, mouse hearts were subjected to a regional ischemia (45-minute) using ligature of the left anterior descending artery. Neuregulin-1ß (80 ng/kg) was given using an intraperitoneal bolus injection 5 minutes before reopening of the ligature followed by a 30-minute reperfusion. RESULTS: Remote application of recombinant neuregulin-1ß protected the heart from reperfusion injury without influencing hemodynamics. This beneficial effect specifically targets reperfusion injury. In contrast, nonreperfused needle trauma was not reduced by neuregulin-1ß when applied remotely. Pharmacological blocking experiments and enzyme activation analysis using Western blot analysis revealed a crucial involvement of the antiapoptotic reperfusion injury salvage kinase cascade. In contrast, contribution of the survivor activating factor enhancement pathways to this early cardioprotection was not observed. CONCLUSIONS: Remote application of neuregulin-1ß protects hearts from early reperfusion injury by activation of the reperfusion injury salvage kinase pathway without relevant effects on intracardiac pressures in myocardial infarction. Besides its potential pharmacological application, neuregulin-1ß might act as an endogenously produced mediator in remote postconditioning.

Echocardiography signs of early cardiac impairment in patients with breast cancer and trastuzumab therapy.

OBJECTIVE: Recent studies in breast cancer patients and Trastuzumab therapy (Herceptin) showed a development of a toxic cardiomyopathy as a severe complication. The aim of this study was to discover early changes in cardiac function and morphology. METHODS: We studied 42 female patients with Her-2/-neu over-expression in breast cancer by echocardiography before, 3, and 6 months after start of the adjuvant Herceptin therapy. All values were mean value ± standard deviation. RESULTS: After 3 or 6 months of a trastuzumab therapy we discovered significant increases in the diastolic and systolic left ventricle volume indices (LV-DVI 32.4 ± 8.5 vs. 38.5 ± 8.7 vs. 40.3 ± 10.3 ml/m², p < 0.001 and LV-SVI 12.6 ± 4.0 vs. 15.7 ± 4.7 vs. 17.2 ± 6.8 ml/m², p < 0.001), an increase of the end-diastolic and end-systolic LV diameter (LVEDD 46.8 ± 4.2 vs. 48.0 ± 4.7 vs. 49.7 ± 4.5 ml/m², p < 0.01; LVESD 28.3 ± 4.2 vs. 31.0 ± 4.7 vs. 32.3 ± 4.9 mm, p < 0.001), a reduced systolic ventricle function determined by the tissue Doppler imaging (TDI) velocity (9.2 ± 2.5 vs. 8.0 ± 1,7 vs. 7.7 ± 1.5 cm/s, p < 0.001), fractional shortening (39,6 ± 7.5 vs. 35.4 ± 7.4 vs. 35.2 ± 7.0%, p < 0.01), and the LV-EF Simpson biplane [62.0 ± 5.1 vs. 60.1 ± 6.3 (p = ns) vs. 58.4 ± 7.9%, p < 0.01] compared to pretreatment values. There was also an increase of the left atrial volume index (21.4 ± 6.2 vs. 26.2 ± 7.9 vs. 29.7 ± 8.8 ml/m², p < 0.001), a decrease of the median TDI atrial velocities (11.9 ± 2.4 vs. 10.5 ± 2.8 vs. 10.1 ± 2.1 cm/s, p < 0.01), an increase of the peak early diastolic filling velocities (73.1 ± 15.4 vs. 83.1 ± 16.4 vs. 82.2 ± 19.4 cm/s, p < 0.05), and an increase of the median mitral valve insufficiency degree (0.64 ± 0.65 vs. 1.03 ± 0.76 vs. 1.11 ± 0.73°, p < 0.001). We could not detect a significant increase in diastolic dysfunction. Also right heart diameters and function did not change significantly. Most patients stayed in an asymptomatic stage of cardiac disease. CONCLUSION: The blockade of Her2/-neu receptors with trastuzumab in patients with breast cancer led to measurable alterations of left ventricular volume, left atrial volume, and systolic function as early as 3 months after start of treatment.

Isolated rupture of the right upper pulmonary vein: a blunt cardiac trauma case.

A 37-year-old woman who sustained blunt chest trauma as a result of a car accident was found unconscious at the accident site with signs of circulatory compromise. Computed tomographic trauma screening excluded thoracic, intracranial, and intra-abdominal bleeding, or other pathologic findings, except a small circumferential hemopericardium. Echocardiography revealed a hemopericardium that was partially clotted and the beginning of compression of the right ventricle. Because of progressive hemodynamic compromise, the decision was made for operative exploration. After a median sternotomy, the resultant excessive bleeding necessitated extracorporeal circulation. Careful inspection revealed isolated rupture of the upper right pulmonary vein, which was successfully repaired.

Broken heart syndrome: Tako Tsubo cardiomyopathy associated with an overdose of the serotonin-norepinephrine reuptake inhibitor Venlafaxine.

OBJECTIVE: To describe a case of Tako Tsubo cardiomyopathy [TTC] in a patient after an overdose of the serotonin-norepinephrine reuptake inhibitor [SNRI] Venlafaxine. METHODS: We present a case study including clinical and laboratory data. Current relevant literature is reviewed and summarized in regard to Tako Tsubo syndrome and SNRI. RESULTS: A 43year-old woman was admitted with acute angina pectoris after accidentally taking an overdose on Venlafaxine in order to treat major depression. Because of the ECG-T-wave-inversions in the precordial leads, the slightly increased Troponin/Creatine kinase levels and the apical systolic dysfunction of the left ventricle in echocardiogram a cardiac catheterization was performed. Coronary artery disease could be excluded by coronary angiography. The followed laevocardiography and cardiac MRI scan showed apical akinesis and basal hypercontractibility typical for apical ballooning (Tako Tsubo cardiomyopathy). Urine analysis revealed elevated normetanephrine level potentially caused by Venlafaxine. Six weeks after the first admission the echocardiogram showed a complete recovery to normal left ventricular function. CONCLUSIONS: To our knowledge this is the first reported case of an overdose of Venlafaxine (SNRI) associated Tako Tsubo cardiomyopathy.

Early assessment of pulmonary inflammation by 19F MRI in vivo.

BACKGROUND: Emulsified perfluorocarbons (PFCs) are preferentially phagocytized by monocytes/macrophages and are readily detected by (19)F MRI. This study tests the hypothesis that (19)F MRI can be used to quantitate pulmonary inflammation by tracking of infiltrating PFC-loaded monocytes. METHODS AND RESULTS: Pneumonia was induced in mice by intratracheal instillation of lipopolysaccharides (LPS) followed by intravenous injection of PFCs. Whereas regular (1)H MRI provided no evidence of lung injury 24 hours after LPS, the concurrent (19)F images clearly show PFC accumulation in both pulmonary lobes. Imaging at 48 hours after LPS revealed signals in (1)H images at the same location as the 24-hour (19)F signals. Thus, progressive pneumonia was first predicted by (19)F MRI early after PFC administration. Without LPS, at no time were (19)F signals observed within the lung. Histology and fluorescence-activated cell sorting (FACS) combined with (19)F MRI confirmed the presence of infiltrating PFC-loaded monocytes/macrophages after LPS challenge. Additional experiments with graded doses of LPS demonstrated that (19)F signal intensity strongly correlated with both LPS dose and pathological markers of lung inflammation. In separate studies, dexamethasone and CGS21680 (adenosine 2A receptor agonist) were used to demonstrate the ability of (19)F MRI to monitor anti-inflammatory therapies. CONCLUSIONS: PFCs serve as a contrast agent for the prognostic and quantitative assessment of pulmonary inflammation by in vivo (19)F MRI, which is characterized by a high degree of specificity due to the lack of any (19)F background. Because PFCs are biochemically inert, this approach may also be suitable for human applications.

Chronic NOS inhibition prevents adverse lung remodeling and pulmonary arterial hypertension in caveolin-1 knockout mice.

Recently generated caveolin-1 deficient mice (cav-1 ko) suffer from severe lung fibrosis with marked pulmonary hypertension and arterial hypoxemia and may therefore serve as an useful animal model of this devastating human disorder. Accumulating evidence strongly supports the negative regulatory influence of caveolin-1 on endothelial nitric oxide synthase resulting in a constitutive hyperactivation of the nitric oxide (NO) pathway in cav-1 ko. We therefore hypothesized that a disturbed NO signaling is implicated in the evolution of the adverse lung phenotype of cav-1 ko. For this purpose, cav-1 ko of 2 months age were compared with knockout counterparts experiencing 2-month postnatal NO synthase inhibition by NG-nitro-l-arginine methyl ester (L-NAME) treatment. Chronic l-NAME administration prevented adverse lung remodeling in cav-1 ko. Furthermore, l-NAME donation led to a normalized oxygen saturation (91.5+/-1.8% vs. 98.5+/-2.3%, P<0.01, n=10-12), a marked decrease in right ventricular hypertrophy (LV/RV ratio: 4.0+/-0.3 vs. 2.7+/-0.3, P<0.01, n=10-12) and reductions of the elevated pulmonary artery pressure (40.2+/-3.1 mmHg vs. 26.3+/-4.6 mmHg, P<0.01, n=6). Collectively, these improvements resulted in an enhanced exercise capacity of l-NAME-treated cav-1 ko. Finally, we found evidence for enhanced oxidative stress in untreated cav-1 ko which was substantially reduced by chronic l-NAME administration to cav-1 ko. In view of these data, we speculate that a perturbation of NO signaling, together with enhanced O2(-) production originating from NO synthases, may play a pivotal role in the pathogenesis of the adverse pulmonary phenotype seen in cav-1 ko.