Chronic endothelial dopamine receptor stimulation improves endothelial function and hemodynamics in autosomal dominant polycystic kidney disease.

Altered polycystin-mediated endothelial flow mechanosensitivity contributes to the development of hypertension and cardiovascular complications in patients with autosomal dominant polycystic kidney disease (ADPKD). Stimulation of endothelial type 5 dopamine receptors (DR5) can acutely compensate for the endothelial consequences of polycystin deficiency, but the chronic impact of this approach must be evaluated in ADPKD. Nineteen patients with ADPKD on standard of care therapy were randomized to receive a 2-month treatment with the DR agonist rotigotine using transdermal patches, nine at 2 mg/24hours and ten at 4 mg/24hours or while ten were untreated. Rotigotine at the dose of 4 mg/24hours significantly increased nitric oxide release (nitrite levels from 10±30 to 46±34 nmol/L) and radial artery endothelium-dependent flow-mediated dilatation (from 16.4±6.3 to 22.5±7.3%) in response to hand skin heating. Systemic hemodynamics were not significantly modified but aplanation tonometry showed that rotigotine at 4 mg/24hours reduced aortic augmentation index and pulse pressure without affecting carotid-to femoral pulse wave velocity. Plasma creatinine and urea, urinary cyclic AMP, which contributes to cyst growth in ADPKD and copeptin, a surrogate marker of vasopressin, were not affected by rotigotine. In mice with a specific deletion of polycystin-1 in endothelial cells, chronic infusion of the peripheral DR5 agonist fenoldopam also improved mesenteric artery flow-mediated dilatation and reduced blood pressure. Thus, our study demonstrates that in patients with ADPKD, chronic administration of rotigotine improves conduit artery endothelial function through the restoration of flow-induced nitric oxide release as well as hemodynamics suggesting that endothelial DR5 activation may represent a promising pharmacological approach to prevent cardiovascular complications of ADPKD.

Ezh2 emerges as an epigenetic checkpoint regulator during monocyte differentiation limiting cardiac dysfunction post-MI.

Epigenetic regulation of histone H3K27 methylation has recently emerged as a key step during alternative immunoregulatory M2-like macrophage polarization; known to impact cardiac repair after Myocardial Infarction (MI). We hypothesized that EZH2, responsible for H3K27 methylation, could act as an epigenetic checkpoint regulator during this process. We demonstrate for the first time an ectopic EZH2, and putative, cytoplasmic inactive localization of the epigenetic enzyme, during monocyte differentiation into M2 macrophages in vitro as well as in immunomodulatory cardiac macrophages in vivo in the post-MI acute inflammatory phase. Moreover, we show that pharmacological EZH2 inhibition, with GSK-343, resolves H3K27 methylation of bivalent gene promoters, thus enhancing their expression to promote human monocyte repair functions. In line with this protective effect, GSK-343 treatment accelerated cardiac inflammatory resolution preventing infarct expansion and subsequent cardiac dysfunction in female mice post-MI in vivo. In conclusion, our study reveals that pharmacological epigenetic modulation of cardiac-infiltrating immune cells may hold promise to limit adverse cardiac remodeling after MI.

A Supraceliac Aortic Cross Clamping Model to Explore Remote Lung Injury and the Endothelial Glycocalyx.

BACKGROUND: We hypothesized that supraceliac aortic cross clamping could induce lung injury mediated by an inflammatory ischemia-reperfusion (IR) trigger. We aimed to characterize glycocalyx (GCX), a component of endothelial membrane, participating to remote lung injury. METHODS: Rats underwent supraceliac aortic cross clamping for 40 min and were sacrificed at 0, 3, 6, and 24 hr of reperfusion (n = 10/group). Each group was compared to sham (n = 6/group). GCX products (syndecan-1 [Sdc-1] and heparan sulfate [HS]), tumor necrosis factor-alpha (TNF-α), and interleukin-1ß (IL-1ß) were measured in plasma (enzyme-linked immunosorbent assay[ELISA]). Lungs were harvested for measurements of TNF-α, IL-1ß (polymerase chain reaction) and Sdc-1 (western blotting [WB]). Histologic lung injury scoring and pulmonary gravimetry were analyzed in a blinded manner. RESULTS: Plasmatic Sdc-1, HS, TNF-α, and IL-1ß reached peak levels at 3 hr. Levels were significantly higher in clamping groups than sham at 6 hr for Sdc-1, at 0 and 3 hr for HS, at 3 and 6 hr for TNF-α, and at 3 hr for IL-1ß. Lung TNF-α and Interleukin-1ß reached peak levels at 6 hr. Levels were significantly higher than sham at 6 and 24 hr for TNF-α and at 6 hr for IL-1ß. Lung Sdc-1 was lowest at 3 hr. Sdc-1 was not significantly different compared to sham at the different reperfusion times. At 3 hr, it was 0.27 ± 0.03 vs. 0.33 ± 0.02 (sham) (P = 0.09). Histopathologic scores at 6 and 24 hr were higher in clamping groups than sham. At 6 and 24 hr, it was higher for hemorrhage, polynuclear neutrophil (PNN) infiltration and intravascular leukocytes. Pulmonary edema was higher by gravimetry at 0 and 6 hr. CONCLUSIONS: Supra celiac aortic clamping causes early lung injury in relation with a systemic inflammatory response associated with altered GCX structure.

Transient heart rate reduction improves acute decompensated heart failure-induced left ventricular and coronary dysfunction.

AIMS: Acute decompensated heart failure (ADHF), a live-threatening complication of heart failure (HF), associates a further decrease of the already by HF-impaired cardiac function with an increase in heart rate. We evaluated, using a new model of ADHF, whether heart rate reduction (HRR) opposes the acute decompensation-related aggravation of cardiovascular dysfunction. METHODS AND RESULTS: Cardiac output (echocardiography), cardiac tissue perfusion (magnetic resonance imaging), pulmonary wet weight, and in vitro coronary artery relaxation (Mulvany) were assessed 1 and 14 days after acute decompensation induced by salt-loading (1.8 g/kg, PO) in rats with well-established HF due to coronary ligation. HRR was induced by administration of the If current inhibitor S38844, 12 mg/kg PO twice daily for 2.5 days initiated 12 h or 6 days after salt-loading (early or delayed treatment, respectively). After 24 h, salt-loading resulted in acute decompensation, characterized by a reduction in cardiac output (HF: 130 ± 5 mL/min, ADHF: 105 ±  8 mL/min; P < 0.01), associated with a decreased myocardial perfusion (HF: 6.41 ± 0.53 mL/min/g, ADHF: 4.20 ± 0.11 mL/min/g; P < 0.01), a slight increase in pulmonary weight (HF: 1.68 ± 0.09 g, ADHF: 1.81 ± 0.15 g), and impaired coronary relaxation (HF: 55 ± 1% of pre-contraction at acetylcholine 4.5 10-5  M, ADHF: 27 ± 7 %; P < 0.01). Fourteen days after salt-loading, cardiac output only partially recovered (117 ± 5 mL/min; P < 0.05), while myocardial tissue perfusion (4.51 ± 0.44 mL/min; P < 0.01) and coronary relaxation (28 ± 4%; P < 0.01) remained impaired, but pulmonary weight further increased (2.06 ± 0.15 g, P < 0.05). Compared with untreated ADHF, HRR induced by S38844 improved cardiac output (125 ± 1 mL/min; P < 0.05), myocardial tissue perfusion (6.46 ± 0.42 mL/min/g; P < 0.01), and coronary relaxation (79 ± 2%; P < 0.01) as soon as 12 h after S38844 administration. These effects persisted beyond S38844 administration, illustrated by the improvements in cardiac output (130 ± 6 mL/min; P < 0.05), myocardial tissue perfusion (6.38 ± 0.48 mL/min/g; P < 0.01), and coronary relaxation (71 ± 4%; P < 0.01) at Day 14. S38844 did not modify pulmonary weight at Day 1 (1.78 ± 0.04 g) but tended to decrease pulmonary weight at Day 14 (1.80 ± 0.18 g). While delayed HRR induced by S38844 never improved cardiac function, early HRR rendered less prone to a second acute decompensation. CONCLUSIONS: In a model mimicking human ADHF, early, but not delayed, transient HRR induced by the If current inhibitor S38844 opposes acute decompensation by preventing the decompensated-related aggravation of cardiovascular dysfunction as well as the development of pulmonary congestion, and these protective effects persist beyond the transient treatment. Whether early transient HRR induced by If current inhibitors or other bradycardic agents, i.e. beta-blockers, exerts beneficial effects in human ADHF warrants further investigation.

Cardiopulmonary bypass increases endothelial dysfunction after pulmonary ischaemia-reperfusion in an animal model.

OBJECTIVES: Endothelial dysfunction during ischaemia-reperfusion (IR) is a major cause of primary graft dysfunction during lung transplantation. The routine use of cardiopulmonary bypass (CPB) during lung transplantation remains controversial. However, the contribution of CPB to pulmonary endothelial dysfunction remains unclear. The objective was to investigate the impact of CPB on endothelial dysfunction in a lung IR rat model. METHODS: Rats were allocated to 4 groups: (i) Sham, (ii) IR, (iii) CPB and (iv) IR-CPB. The primary outcome was the study of pulmonary vascular reactivity by wire myograph. We also assessed glycocalyx degradation by enzyme-linked immunosorbent assay and electron microscopy and both systemic and pulmonary inflammation by enzyme-linked immunosorbent assay and immunohistochemistry. Rats were exposed to 45 min of CPB and IR. We used a CPB model allowing femoro-femoral support with left pulmonary hilum ischaemia for IR. RESULTS: Pulmonary endothelium-dependent relaxation to acetylcholine was markedly reduced in the IR-CPB group (10.7 ± 9.1%) compared to the IR group (50.5 ± 5.2%, P < 0.001), the CPB group (54.1 ± 4.7%, P < 0.001) and the sham group (80.8 ± 6.7%, P < 0.001), suggesting that the association of pulmonary IR and CPB increases endothelial dysfunction. In IR-CPB, IR and CPB groups, vasorelaxation was completely abolished when inhibiting nitric oxide synthase, suggesting that this relaxation process was mainly mediated by nitric oxide. We observed higher syndecan-1 plasma levels in the IR-CPB group in comparison with the other groups, reflecting an increased degradation of glycocalyx. We also observed higher systemic inflammation in the IR-CPB group as shown by the increased plasma levels of IL-1ß, IL-10. CONCLUSIONS: CPB significantly increased the IR-mediated effects on pulmonary endothelial dysfunction. Therefore, the use of CPB during lung transplantation could be deleterious, by increasing endothelial dysfunction.

Lymphatic and Immune Cell Cross-Talk Regulates Cardiac Recovery After Experimental Myocardial Infarction.

OBJECTIVE: Lymphatics play an essential pathophysiological role in promoting fluid and immune cell tissue clearance. Conversely, immune cells may influence lymphatic function and remodeling. Recently, cardiac lymphangiogenesis has been proposed as a therapeutic target to prevent heart failure after myocardial infarction (MI). We investigated the effects of gene therapy to modulate cardiac lymphangiogenesis post-MI in rodents. Second, we determined the impact of cardiac-infiltrating T cells on lymphatic remodeling in the heart. Approach and Results: Comparing adenoviral versus adeno-associated viral gene delivery in mice, we found that only sustained VEGF (vascular endothelial growth factor)-CC156S therapy, achieved by adeno-associated viral vectors, increased cardiac lymphangiogenesis, and led to reduced cardiac inflammation and dysfunction by 3 weeks post-MI. Conversely, inhibition of VEGF-C/-D signaling, through adeno-associated viral delivery of soluble VEGFR3 (vascular endothelial growth factor receptor 3), limited infarct lymphangiogenesis. Unexpectedly, this treatment improved cardiac function post-MI in both mice and rats, linked to reduced infarct thinning due to acute suppression of T-cell infiltration. Finally, using pharmacological, genetic, and antibody-mediated prevention of cardiac T-cell recruitment in mice, we discovered that both CD4+ and CD8+ T cells potently suppress, in part through interferon-γ, cardiac lymphangiogenesis post-MI. CONCLUSIONS: We show that resolution of cardiac inflammation after MI may be accelerated by therapeutic lymphangiogenesis based on adeno-associated viral gene delivery of VEGF-CC156S. Conversely, our work uncovers a major negative role of cardiac-recruited T cells on lymphatic remodeling. Our results give new insight into the interconnection between immune cells and lymphatics in orchestration of cardiac repair after injury.

A 30-Minute Supraceliac Aortic Clamping in the Rat Causes Death Due to an Inflammatory Response and Pulmonary Lesions.

BACKGROUND: The treatment of thoracoabdominal aortic aneurysms through an open approach has general and pulmonary consequences of multiple etiologies. Our assumption was that the supraceliac aortic clamping needed for this operation causes a systemic inflammatory response associated with a pulmonary attack. METHODS: We developed a model of 30-min supraceliac aortic clamping in Wistar rats weighing 300 g. After 90 min of reperfusion, the rats were sacrificed. The effects on the digestive tract wall were analyzed by measurement of the mucosal thickness/total thickness ratio. The effects on the mesenteric endothelial function were determined by an ex situ measurement of the arterial pressure/volume curves (third branch). The systemic consequences of the procedure were analyzed by dosing tumor necrosis factor alpha (TNFα), interleukin (IL)1ß, and IL10 in the blood. The pulmonary consequences were analyzed by the measurement of macrophages, polymorphonuclear neutrophils (PNs), T lymphocyte infiltration, pulmonary apoptosis (TUNEL) and active caspase 3. The experimental scheme included 20 rats with ischemia-reperfusion (IR) and 20 control rats. An analysis of survival was carried out on 20 other rats (10 IR and 10 controls). RESULTS: The results were expressed as average ± standard error of the mean. The statistical tests were Student's t-test and Mann-Whitney test. This visceral IR model decreased the ratio of the thickness of the intestinal mucosa compared with that of the control rats (0.77 ± 0.008 vs. 0.82 ± 0.009 [P < 0.001]). This local effect was not accompanied by any mesenteric endothelial dysfunction (P = 0.91). On a systemic level, IR increased TNFα (37.9 ± 1.5 vs. 28.2 ± 0.6 pg/mL; P < 0.0001), IL1ß (67.1 ± 9.8 vs. 22.5 ± 5.6 pg/mL; P < 0.001), and IL10 (753.3 ± 96 vs. 3.7 ± 1.7 pg/mL; P < 0.0001). As regards the lungs, IR increased the parenchymal cellular infiltration by macrophages (6.8 ± 0.8 vs. 4.5 ± 0.4 cells per field; P < 0.05) and PNs (7.4 ± 0.5 vs. 6.2 ± 03 cells per field; P < 0.05). There was no increase in the pulmonary cellular apoptosis measured by TUNEL (P = 0.77) or in the caspase 3 activity (P = 0.59). The mortality of the visceral IR rats was 100% at 36 hr vs. 0% in the animals without IR. CONCLUSIONS: This work showed that the inflammatory response to visceral IR had systemic and pulmonary effects which always results in the death in the rat.

Role of Toll-like receptors 2 and 4 in mediating endothelial dysfunction and arterial remodeling in primary arterial antiphospholipid syndrome.

OBJECTIVE: To assess the role of Toll-like receptors (TLRs) in antiphospholipid antibody (aPL)-mediated vascular abnormalities in patients with primary arterial antiphospholipid syndrome (APS). METHODS: Forty-eight subjects participated in the study. Arterial function and structure and TLR pathway activation were determined in patients with primary arterial APS and matched controls. The pathogenic effects of aPL isolated from patients were assessed in wild-type (WT) and TLR-knockout mice. RESULTS: APS patients had endothelial dysfunction, arterial stiffening, and hypertrophy, as evidenced by decreased brachial artery endothelium-dependent flow-mediated dilation (FMD) and increased aortic pulse wave velocity and carotid intima-media thickness (IMT), as compared with controls. Plasma samples from APS patients revealed decreased nitric oxide (NO) availability and a pro-oxidative, proinflammatory, and prothrombotic state illustrated by a decrease in nitrite and an increase in lipid peroxidation, tumor necrosis factor α levels, and tissue factor (TF) levels. Furthermore, TLR pathway activation was found in APS patients with increased TLR-2 and TLR-4 messenger RNA expression and increased protein levels of the activated TLR transduction protein interleukin-1 receptor-associated kinase 1 in peripheral blood mononuclear cells. Moreover, agonist-stimulated cell-surface expression of TLR-2 and TLR-4 in circulating monocytes was higher in APS patients than in controls. These changes were positively associated with IMT and negatively associated with FMD. Finally, aPL injection decreased mesenteric endothelium-dependent relaxation and increased TF expression in WT mice but not in TLR-2- or TLR-4-knockout mice. CONCLUSION: This translational study supports the notion that TLR-2 and TLR-4 play a role in mediating vascular abnormalities in patients with primary arterial APS. TLRs thus constitute a promising pharmacologic target for preventing cardiovascular complications in APS.

Gene deletion of protein tyrosine phosphatase 1B protects against sepsis-induced cardiovascular dysfunction and mortality.

OBJECTIVE: Cardiovascular dysfunction is a major cause of mortality in patients with sepsis. Recently, we showed that gene deletion or pharmacological inhibition of protein tyrosine phosphatase 1B (PTP1B) improves endothelial dysfunction and reduces the severity of experimental heart failure. However, the cardiovascular effect of PTP1B invalidation in sepsis is unknown. Thus, we explored the beneficial therapeutic effect of PTP1B gene deletion on lipopolysaccharide (LPS)-induced cardiovascular dysfunction, inflammation, and mortality. APPROACH AND RESULTS: PTP1B(-/-) or wild-type mice received LPS (15 mg/kg) or vehicle followed by subcutaneous fluid resuscitation (saline, 30 mL/kg). α-1-dependent constriction and endothelium-dependent dilatation, assessed on isolated perfused mesenteric arteries, were impaired 8 hours after LPS and significantly improved in PTP1B(-/-) mice. This was associated with reduced vascular expression of interleukin1-ß, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, cyclooxygenase-2, and inducible nitric oxide synthase mRNA. PTP1B gene deletion also limited LPS-induced cardiac dysfunction assessed by echocardiography, left ventricular pressure-volume curves, and in isolated perfused hearts. PTP1B(-/-) mice also displayed reduced LPS-induced cardiac expression of tumor necrosis factor-α, interleukin1-ß, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and Gp91phox, as well as of several markers of cellular infiltration. PTP1B deficiency also reduced cardiac P38 and extracellular signal-regulated protein kinase 1 and 2 phosphorylation and increased phospholamban phosphorylation. Finally, PTP1B(-/-) mice displayed a markedly reduced LPS-induced mortality, an effect also observed using a pharmacological PTP1B inhibitor. PTP1B deletion also improved survival in a cecal ligation puncture model of sepsis. CONCLUSIONS: PTP1B gene deletion protects against septic shock-induced cardiovascular dysfunction and mortality, and this may be the result of the profound reduction of cardiovascular inflammation. PTP1B is an attractive target for the treatment of sepsis.

Omega-3 polyunsaturated fatty acids delay the progression of endotoxic shock-induced myocardial dysfunction.

Septic shock has a high mortality rate, partially related to myocardial dysfunction. Polyunsaturated fatty acids (omega-3 PUFAs) possess anti-inflammatory and antioxidant properties, but whether omega-3 PUFAs exert beneficial effects on myocardial function is unknown. We investigated, in a rat model of endotoxic shock, the effects of omega-3 PUFAs pretreatment on cardiac hemodynamics, function, and oxidative stress as well as intestinal barrier. Endotoxic shock was induced by lipopolysaccharide (LPS; 20 mg/kg IP) administered to rats pretreated or not with omega-3 PUFAs (Omegaven®; 0.5 g/kg IP, 90 min before injection of LPS). Two or 5 h after LPS, left ventricular function and arterial pressure were measured, followed by assessment left ventricular total glutathione as well as tumor necrosis factor alpha expression, occuldin expression, and proteasome activities. LPS reduced mean arterial blood pressure to the same extent 2 and 5 h after its administration, but cardiac output was more markedly decreased after 5 h. Omega-3 PUFAs pretreatment did not significantly modify the effect of LPS on mean arterial pressure and total peripheral resistance, but prevented the decrease in cardiac output 2 h after LPS. LPS increased oxidized glutathione after 2 h, and this increase was significantly attenuated by omega-3 PUFAs. Simultaneously, omega-3 PUFAs increased myocardial hemeoxygenase-1 (HO-1) mRNA expression. Finally, omega-3 PUFAs prevented the reduction of intestinal occludin expression. Omega-3 PUFAs pre-treatment improves myocardial dysfunction during endotoxemia and increases myocardial HO-1 expression. Moreover, the preservation of the intestinal occludin induced by omega-3 PUFAs precedes myocardial protection, suggesting the involvement of the intestinal barrier in the myocardial improvement observed with omega-3 PUFAs parenteral supplementation.

Myocardial dysfunction in early state of endotoxemia role of heme-oxygenase-1.

BACKGROUND: The triggers and cellular mechanisms of cardiac dysfunction have not been clearly established during the early period following challenge with lipopolysaccharides (LPS) (<1 h post-LPS). The aim of the study was to evaluate the myocardial depression during early stage of endotoxemia, the relationship between oxidative stress production and cardiac dysfunction in a rat model of endotoxic shock, and its inhibition by heme-oxygenase-1 (HO-1) overexpression. MATERIALS AND METHODS: LPS-induced myocardial deformation was assessed by tissue Doppler imaging and invasive hemodynamic measurements in rats 2 h after LPS challenge. Myocardial samples were processed for the measurements of tumor necrosis factor alpha (TNFalpha), nitric oxidase synthase II (NOSII), HO-1 gene expression, reactive oxygen species (ROS) production, and reduced glutathione/oxidized glutathione (GSH/GSSH) ratio. RESULTS: Myocardial systolic and diastolic deformation was evident as determined by tissue Doppler imaging but left ventricular conventional echocardiographic parameters did not show significant alterations. Myocardial deformation was significantly associated with reactive oxygen species and TNFalpha overproduction. Pretreatment with hemin to induce HO-1 resulted in decreased oxidative stress and TNFalpha production, and prevented LPS-induced alterations in myocardium. CONCLUSIONS: These preliminary results suggest myocardial alteration at a very early stage after LPS challenge associated with oxidative stress response. Manipulation of the HO-1 pathway may represent a future therapeutic strategy to counteract oxidative stress of endotoxemia and perhaps may limit future myocardial deformation.

Toll-like receptors 4 contribute to endothelial injury and inflammation in hemorrhagic shock in mice.

OBJECTIVE: Hemorrhagic shock followed by resuscitation (HS/R) promotes organ injury by priming cells of the innate immune system for inflammatory response. Toll-like receptors (TLRs) play an important role in signal transduction in shock/resuscitation conditions. Because proinflammatory mediators are a critical event in mesenteric endothelial injury induced by HS/R, we assessed the role of TLR4 or TLR2 in this setting. DESIGN: Laboratory investigation. SETTING: Research laboratory at Rouen University Medical School. SUBJECTS: Male wild-type, TLR4(-/-) and TLR2(-/-) mice with the same C57BL/6 background. INTERVENTIONS: Mice were submitted to 30 minutes hemorrhagic shock followed by 1 hour resuscitation, after which mesenteric endothelial dysfunction, microvascular injury, and TNF[alpha] production were assessed. MEASUREMENTS AND MAIN RESULTS: HS/R markedly decreased nitric oxide-mediated mesenteric relaxations induced by acetylcholine, assessed ex vivo on a myograph. By contrast, in TLR4-deficient mice, HS/R did not impair the nitric oxide-mediated responses to acetylcholine. No protection was observed in TLR2-deficient mice. TLR4-deficient mice also displayed a significant reduction in fluid resuscitation and TNF[alpha] systemic production. CONCLUSIONS: TLR4 contributes to mesenteric endothelial dysfunction after hemorrhagic shock. This early TLR4-induced vascular injury may be an important trigger of the systemic inflammatory response occurring in this disease.

Intestinal preconditioning prevents inflammatory response by modulating heme oxygenase-1 expression in endotoxic shock model.

Gut mucosal injury observed during ischemia-reperfusion is believed to trigger a systemic inflammatory response leading to multiple organ failure. It should be interesting to demonstrate this relationship between gut and multiple organ failure in a sepsis model. Intestinal preconditioning (PC) can be used as a tool to assess the effect of intestinal ischemia in inflammatory response after LPS challenge. The aim of this study was to investigate the protective effect of PC against LPS-induced systemic inflammatory and intestinal heme oxygenase-1 (HO-1) expression. ES was performed with LPS (10 mg/kg iv) with or without PC, which was done before LPS. Rats were first subjected to sham surgery or PC with four cycles of 1 min ischemia and 4 min of reperfusion 24 h before LPS challenge or saline administration. PC significantly reduced fluid requirements, lung edema, intestinal lactate production, and intestinal injury. Inflammatory mRNA expressions for intestine and lung ICAM and TNF were significantly reduced after PC, and these effects were significantly abolished by zinc-protoporphyrin (a specific HO-1 activity inhibitor) and mimicked by bilirubin administration. Intestinal PC selectively increased HO-1 mRNA expression in intestine, but we have observed no expression in lungs. These findings demonstrate that intestinal injury is a important event for inflammatory response and multiple organ injury after LPS challenge. Intestinal HO-1 expression attenuates LPS-induced multiple organ failure by modulating intestine injury and its consequences on inflammatory response. Identification of the exact mechanisms responsible for intestine HO-1 induction may lead to the development of new pharmacological interventions.

Protective effects of heme-oxygenase expression against endotoxic shock: inhibition of tumor necrosis factor-alpha and augmentation of interleukin-10.

BACKGROUND: Heme-oxygenase (HO)-1 acts as an inducible defense against oxidative stress and could play an important role in inflammation models, providing protection against oxidative stress and systemic inflammatory response. The objective of this study was to improve the role of HO-1 on systemic inflammatory response in an endotoxic shock model. METHODS: Five groups of animals were used: control group; lipopolysaccharide (LPS) group, animals received LPS 5 mg/kg; hemin + LPS group, animals received pretreatment with hemin, used to induce HO-1 expression; Zn-PP group, animals received Zn-PP, a specific inhibitor of HO-1 activity and hemin group. At the end of the experiment, tissue and blood samples were isolated for the measurement of HO-1 mRNA expression, biochemical measurements, and cytokine measurements. RESULTS: HO-1 messenger RNA expression and protein were induced to a larger extent in LPS group in distal organs. Hemin pretreatment induced a significant decrease oxidative stress and tumor necrosis factor-alpha plasma levels with a significant increase of interleukin-10 plasma levels. Pulmonary injury was markedly limited after hemin. Onset of lethality in LPS group occurred at H6, and was delayed until H10 with hemin. Inhibition of HO-1 activity by Zn-PP administration abolished the beneficial effect of hemin-pretreatment. CONCLUSIONS: Early HO-1 expression may modulate systemic inflammatory response and limit end-organ injury in endotoxic shock model.

Triple ACE-ECE-NEP inhibition in heart failure: a comparison with ACE and dual ECE-NEP inhibition.

Mortality remains high in chronic heart failure (CHF) because under ACE inhibitor treatment other neurohumoral systems remain/become (de)activated, such as the endothelin and atrial natriuretic peptide pathways. Dual endothelin-converting enzyme-neutral endopeptidase (ECE-NEP) inhibition exerts beneficial effects in experimental CHF, but whether "triple" ACE-ECE-NEP inhibition is superior to ACE or ECE-NEP inhibition is unknown. We compared, in rats with CHF, ACE-ECE-NEP to ACE or ECE-NEP inhibition in terms of left ventricular (LV) hemodynamics and remodeling. Benazepril (2 mg/kg/d) or the ECE-NEP inhibitor CGS26303 (10 mg/kg/d) were administered alone or in combination (subcutaneously for 28 days starting 7 days after coronary ligation). ACE-ECE-NEP inhibition reduced blood pressure more markedly than ACE or ECE-NEP inhibition. All treatments increased cardiac output to the same extent, but ACE-ECE-NEP inhibition reduced LV diameter and LV end-diastolic pressure more markedly than ACE or ECE-NEP inhibition. The reduction of LV weight and collagen accumulation in the "viable" myocardium was most pronounced after ACE-ECE-NEP inhibition. These results, obtained in experimental CHF, illustrate a further improvement of LV hemodynamics and structure after ACE-ECE-NEP inhibition compared with either ACE or ECE-NEP inhibition, but whether this is associated with a further improvement of exercise tolerance and/or survival remains to be determined.

Sustained improvement of cardiac function and prevention of cardiac remodeling after long-term dual ECE-NEP inhibition in rats with congestive heart failure.

Acute inhibition of endothelin converting enzyme (ECE) and neutral endopeptidase (NEP) exerts beneficial hemodynamic effects in chronic heart failure (CHF). However, the long-term effects of dual ECE-NEP inhibition are unknown. We evaluated, in rats with CHF, the long-term effects of the dual ECE-NEP inhibitor CGS 26303 (10 mg.kg(-1).day(-1)) on systemic and left ventricular (LV) hemodynamics and LV remodeling, and compared them to those induced by the selective NEP inhibitor CGS 24592 (10 mg.kg(-1).day(-1)), both administered subcutaneously by mini-pump for 30 days starting 7 days after left coronary artery ligation. After 30 days, CGS 26303, but not CGS 24592, reduced systolic blood pressure, while both drugs never affected heart rate. Echocardiographic studies showed that only CGS 26303 diminished LV end-diastolic and systolic diameters and increased LV fractional shortening and cardiac output. Moreover, CGS 26303, but not CGS 24592, reduced LV end-diastolic pressure, while LV dP/dtmax/min was not affected. Both drugs reduced collagen accumulation in the 'viable' part of the LV, but only CGS 26303 reduced LV weight. Thus, long-term treatment with CGS 26303 decreases both preload and afterload, increases cardiac output, and diminishes LV hypertrophy, dilatation, and cardiac fibrosis, suggesting that dual ECE-NEP inhibition might be beneficial in human CHF.