Fabienne Tamion

Improvement of Endothelial Function by Chronic Angiotensin-Converting Enzyme Inhibition in Heart Failure Role of Nitric Oxide, Prostanoids, Oxidant Stress, and Bradykinin

BACKGROUND-Chronic heart failure (CHF) impairs the endothelium-dependent, flow-mediated dilation (FMD) of small arteries. However, whether chronic angiotensin-converting enzyme (ACE) inhibition affects the impairment of FMD in CHF is unknown. We investigated the effects of long-term ACE inhibition on the FMD of peripheral arteries in rats with CHF and the mechanism(s) involved. METHODS AND RESULTS-FMD was assessed in isolated, perfused gracilis muscle arteries from sham-operated, and untreated or ACE inhibitor-treated (perindopril 2 mg. kg(-1). day(-1) for 10 weeks) rats with CHF (coronary artery ligation). The role of nitric oxide (NO), prostaglandins, and free radicals was assessed by pretreating the vessels with the NO synthase inhibitor N(W)-nitro-L-arginine, the cyclooxygenase inhibitor diclofenac, or the free radical scavenger N-2-mercaptopropionyl-glycine (MPG). Endothelial NO synthase mRNA expression was determined by reverse transcriptase polymerase chain reaction. In animals with hemodynamic and echographic signs of CHF, FMD was converted into vasoconstriction, and this was prevented by ACE inhibition. FMD of arteries from sham-operated or ACE inhibitor-treated CHF rats was abolished by N(W)-nitro-L-arginine. In untreated CHF rats, FMD was increased by diclofenac and MPG. In contrast, in arteries from ACE inhibitor-treated rats, neither diclofenac nor MPG affected FMD. In parallel, ACE inhibition prevented the reduction of endothelial NO synthase mRNA by CHF. CONCLUSIONS-In CHF, ACE inhibition normalized NO-dependent dilatation and suppressed the production of vasoconstrictor prostanoid(s), resulting in improved FMD. The improvement of FMD might contribute to the beneficial effects of ACE inhibition during CHF.

Protective Effects of Preconditioning in Cultured Rat Endothelial Cells Effects on Neutrophil Adhesion and Expression of ICAM-1 After Anoxia and Reoxygenation

BACKGROUNDnPreconditioning with brief periods of ischemia protects the coronary endothelium against acute and chronic reperfusion injury, but the mechanisms of this endothelial protection remain unknown. We hypothesized that preconditioning protects endothelial cells through a decreased production of endothelial adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1), leading to a lesser adhesion of neutrophils to the endothelium.nnnMETHODS AND RESULTSnCultured rat aortic endothelial cells were subjected to 6-hour anoxia followed by various durations of reoxygenation. Preconditioning was induced by 1-hour anoxia and 1-hour reoxygenation. ICAM-1 gene expression was measured by polymerase chain reaction, and the percentage of cells expressing ICAM-1 was assessed by confocal laser fluorescence microscopy. Anoxia/reoxygenation increased expression of ICAM-1, with a peak occurring after 6 hours of reoxygenation for mRNA and 9 hours for protein. Preconditioning prevented the increase in ICAM-1. Similar reductions were observed with the free radical scavenger N-2 mercaptopropionyl glycine (MPG). The inhibitory effect of preconditioning on ICAM-1 expression was abolished by an inhibitor of protein kinase C, an inhibitor of nitric oxide synthesis, and by MPG but was not affected by an adenosine receptor antagonist. Finally, both preconditioning and MPG partially prevented the increased adhesion of human neutrophils to reoxygenated endothelial cells.nnnCONCLUSIONSnPreconditioning prevented reoxygenation-induced, free radical-mediated expression of ICAM-1 by a mechanism involving activation of protein kinase C and production of nitric oxide and free radicals, and this is associated with a lesser adhesion of neutrophils to endothelial cells. Such prevention of neutrophil adhesion may contribute to the protective effect of preconditioning against reperfusion-induced endothelial injury.

Bordetella bronchoseptica Pneumonia with Shock in an Immunocompetent Patient

Bordetella bronchoseptica is a rarely reported cause of human infection, but is a common respiratory tract commensal of mammals. Human infection with B. bronchoseptica is almost always associated with severe underlying disease and contact with an appropriate animal reservoir. We report a case of pneumonia with shock caused by B. bronchoseptica in an immunocompetent patient.

Adult-onset renal thrombotic microangiopathy and pulmonary arterial hypertension in cobalamin C deficiency

An 18-year-old man presented in January, 2015, with 48 h of worsening dyspnoea and 1 month of lower limb oedema. He had had language retardation diagnosed at age 3 years, attributed to an emotional shock after the death of his brother, but he had had no specifi c investigations. On admission he was apyrexial with blood pressure 210/100 mm Hg and bilateral basal crackles on auscultation of the chest. Urine dipstick showed microscopic haematuria and proteinuria. Investigations (appendix) showed haemolytic anaemia and mild thrombocytopenia, and renal failure with nephrotic syndrome and haematuria. 3 days after admission, because of progressive renal failure and dyspnoea, and concerns about renal thrombotic microangiopathy (TMA), he was transferred to the medical intensive care unit (ICU) of our hospital. CT scan showed normal kidney morphology and pulmonary oedema. Echocardiography showed raised systolic pulmonary artery pressure with left ventricular hypertrophy without systolic dysfunction. The eye fundus was normal. We started intravenous methylprednisolone, plasma exchange, and haemodialysis in view of features of rapidly progressive glomerulonephritis. Autoimmune investigations were negative. Renal histology done 48 h after admission to ICU showed major stenosing fi broproliferative myxoid lesions in the interlobular arteries, consistent with renal TMA. The glomeruli had an ischaemic appearance with thickened, ribbon-like glomerular basement membranes; there was no proliferation, intracapillary thrombosis, or glomerular endothelial lesion. Immunofl uorescence showed granular glomerular deposits of IgM, without IgG or C3. We ruled out thrombotic thrombocytopenic purpura (TTP) because ADAMTS 13 activity was greater than 10%, and Shiga-toxin related haemolytic uraemic syndrome on PCR for Shiga-like toxin. We could identify no obvious cause of secondary renal TMA so considered the possibility of complement-mediated haemolytic and uraemic syndrome. The patient’s brother had died at the same age, from pulmonary veno-occlusive disease associated with hypertrophic cardiomyopathy. 1 year previously he had been diagnosed with end-stage kidney disease of unknown origin; he had had no history of cognitive impairment. Autopsy showed pulmonary capillary haemangiomatosis and renal lesions, similar to those of his brother. No specifi c biochemical or genetic analysis had been done, and the diagnosis was inconclusive. Workup for cobalamin C (cblC) defi ciency in our patient showed raised concentrations of plasma homocysteine, methylmalonic acid, and propionylcarnitine. We started high-dose intramuscular hydroxycobalamin, and oral betaine and folinic acid. Haemolysis improved within 1 week and he was transferred to the nephrology department on day 10 where his haemodialysis was continued every other day. Right heart catheterisation on day 12 showed mild postcapillary pulmonary hypertension. CT showed no sign of pulmonary veno-occlusive disease. He was discharged 1 month after admission to ICU, with total plasma homocysteine 33 μmol/L (target <70 μmol/L). 5 months later he stopped dialysis with serum creatinine stable around 147 μmol/L. Brain MRI was normal. Genetic analyses confi rmed a compound heterozygosity in MMACHC, with c.271dupA and c.82-12_82-9delTTTC sequence variants, inherited from the patient’s mother and father, respectively. CblC defi ciency, the most common inherited disease of vitamin B12 metabolism, is related to variants in MMACHC. Signs are abnormal concentrations of downstream metabolites of the cobalamin pathway (appendix) with normal vitamin B12. The most frequent and severe presentation occurs in neonates. Pulmonary artery hypertension (PAH) and renal TMA have been described in early-onset cblC defi ciency, whereas isolated neuropsychiatric symptoms prevail in adult-onset forms. A case of adult-onset renal TMA had similar renal outcomes to our patient. The family history and coexistence of a specifi c glomerulopathy in our patient suggest that PAH, renal TMA, and the glomerular lesions are consequences of the variants in MMACHC. This association has been reported in a series of children aged 1–14 years. The glomerular lesions in our case are similar to those described in a 16-year-old with renal failure and a biochemical profi le characteristic of cblC defi ciency, with membrano proliferative lesions with intramembranous granular deposits. How specifi c sequence variants in MMACHC might cause renal and pulmonary vasculopathy is unclear. Hyperhomocysteinaemia alone cannot be the cause because PAH and TMA are usually absent in disorders with very high homocysteine concentrations, such as cystathionine synthase defi ciency. We speculate that endothelial dysfunction, triggered by intracellular and systemic consequences of MMACHC variants, could promote thrombosis, vasoconstriction, and vascular smooth muscle cell proliferation. The c.271dupA variant is the most frequent genetic abnormality described in cblC defi ciency, especially in neonates. The c.82-12_82-9delTTTC variant has been described in only three patients who presented late, possibly because of splicing defects resulting from this intronic deletion. Adult-onset renal thrombotic microangiopathy and pulmonary arterial hypertension in cobalamin C defi ciency

Nitric oxide synthase inhibition and the induction of cytochrome P-450 affect heme oxygenase-1 messenger RNA expression after partial hepatectomy and acute inflammation in rats.

OBJECTIVESna) To evaluate in vivo, in rat liver, heme oxygenase-1 (HO-1) messenger RNA (mRNA) expression level and the regulation of 3,5-cyclic guanosine monophosphate (cGMP) production during hepatic regeneration, localized inflammation, and systemic inflammation; and b) to investigate the effect of the induction of cytochrome P-450 and nitric oxide synthase (NOS) inhibition on HO-1 mRNA level and cGMP production in the liver.nnnDESIGNnExperimental, comparative study.nnnSETTINGnBiochemical and molecular biology laboratory.nnnSUBJECTSnSix-wk-old male Sprague-Dawley rats (n = 60).nnnINTERVENTIONSnWe randomly divided the rats into four groups: a) saline controls; b) animals receiving lipopolysaccharide (600 microg/kg) for systemic inflammation; c) animals receiving turpentine oil (5 mL/kg) for localized inflammation obtained by sterile abscess; and d) partially hepatectomized animals (two-thirds removal of the parenchyma) for hepatic regeneration.nnnMEASUREMENTS AND MAIN RESULTSnHepatic regeneration induced HO-1 mRNA expression, as shown by quantitative reverse transcription-polymerase chain reaction analysis. The time course of liver HO-1 mRNA induction after partial hepatectomy and localized and systemic inflammation showed a similar and gradual increase, with a maximum at 6 hrs and a return to a minimal level 48 hrs after treatments. Liver HO-1 mRNA was overexpressed during localized vs. systemic inflammation. This overexpression was not correlated with either serum IL-6 or corticosterone concentrations, but is related to increased cGMP production. The administration of phenobarbital, a cytochrome P-450 inducer and of nitro-L-arginine methyl ester, a NOS inhibitor, prevented cGMP production and abolished the overexpression of HO-1 mRNA.nnnCONCLUSIONSnThe results of this study indicate that HO-1 mRNA is induced during hepatic regeneration with a similar time course to that observed during acute inflammation. In addition, we demonstrated that: a) HO-1 mRNA is overexpressed during localized vs. systemic inflammation; b) this overexpression is not correlated with IL-6 or corticosterone concentrations but is related to intrahepatic cGMP production; c) induction of cytochromes P-450 and/or inhibition of NOS both reduce liver cGMP production and HO-1 mRNA expression. These results suggest that in rat liver, a cGMP-transducing pathway may control HO-1 mRNA expression. Thus, there may be a role for HO-1 mRNA in the modulation of the hepatic stress response.

Early Detection of Gut Ischemia-Reperfusion Injury During Aortic Abdominal Aneurysmectomy: A Pilot, Observational Study

OBJECTIVEnD-lactate is the enantiomer of L-lactate, which is measured routinely in clinical practice to assess cell hypoxia. D-lactate has been proposed as a specific marker of gut ischemia-reperfusion (IR), particularly during surgery for ruptured abdominal aortic aneurysms. The aim of this study was to compare the use of D-lactate measurement and colonic tonometry (taken as a reference method) for gut IR detection during elective infrarenal aortic aneurysm (IrAA) surgery.nnnDESIGNnProspective, monocenter, observational study.nnnSETTINGnVascular surgery unit, university hospital.nnnPARTICIPANTSnCandidates for elective IrAA surgery.nnnINTERVENTIONSnPatients without (controls) and with gut IR (defined as ΔCO2>2.6 kPa) were compared retrospectively.nnnMEASUREMENT AND MAIN RESULTSnD-lactate levels were compared with colonic perfusion levels (ΔCO2), as assessed by colonic tonometry, at 7 time points during surgery and until 24 hours after surgery. D-lactate also was measured in mesenteric vein blood before and after gut reperfusion. Plasma TNF-α level was measured at the same time points to assess systemic inflammatory response. Eighteen patients requiring elective IrAA surgery were included. The ΔCO2 and TNF-α level varied significantly over time. There was a significant ΔCO2 peak at the end of clamping (2.6±1.8 kPa, p = 0.006) and a significant peak in TNF-α level after 1 hour of reperfusion (183±53 ng/L, p = 0.05). D-lactate levels were undetectable in systemic and mesenteric blood in all the patients throughout the study period. Gut IR patients (n = 6) experienced a longer overall duration of intraoperative hypotensive episodes and received more catecholamines than the controls (n = 12).nnnCONCLUSIONSnCompared with colonic tonometry, D-lactate was not a reliable biomarker of gut IR during elective IrAA surgery.

Myocardial Dysfunction in Early State of Endotoxemia Role of Heme-Oxygenase-1

BACKGROUNDnThe 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.nnnMATERIALS AND METHODSnLPS-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.nnnRESULTSnMyocardial 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.nnnCONCLUSIONSnThese 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.

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; 20xa0mg/kg IP) administered to rats pretreated or not with omega-3 PUFAs (Omegaven®; 0.5xa0g/kg IP, 90xa0min before injection of LPS). Two or 5xa0h 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 5xa0h after its administration, but cardiac output was more markedly decreased after 5xa0h. 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 2xa0h after LPS. LPS increased oxidized glutathione after 2xa0h, 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.

Albumin Limits Mesenteric Endothelial Dysfunction and Inflammatory Response in Cardiopulmonary Bypass

The aim of this study was to investigate the potential anti-inflammatory and endothelial protective properties of albumin during cardiopulmonary bypass (CPB) in an experimental porcine model. Two groups underwent CPB for 90 min (n = 7 in each group), and a baseline (BL) control group did not undergo CPB (n = 7). Priming consisted of a gelatin solution (4% gelofusine, CPBG group) or colloid solution (5% albumin, CPBA group). Mesenteric arterial segments were isolated and exposed in vitro to phenylephrine (with or without nitric oxide synthase inhibition) to assess contractility, and exposed to acetylcholine and sodium nitroprusside to assess relaxation. Plasma tumor necrosis factor (TNF)-α levels, intestinal and pulmonary TNF-α and heme oxygenase (HO)-1 mRNA expression, and organ injury were studied. Upon sacrifice, TNF-α levels were significantly higher in the CPBG group than in the CPBA and BL groups. The contractile response was significantly higher in the CPBG group, whereas the response to acetylcholine was significantly lower in the CPBG group than in the other groups. HO-1 mRNA expression was significantly higher in intestine samples in the CPBA group than in the CPBG and BL groups. HO-1 mRNA expression was significantly higher in lung samples in the CPBA group than in the CPBG group. Leukocyte infiltration was significantly higher in intestine and lung samples in the CPBG group than in the CPBA and BL groups. Albumin priming reduced CPB-induced mesenteric vascular dysfunction and prevented the development of a systemic inflammatory response by modeling HO-1 expression in target organs.

Modulation of mesenteric vasoreactivity and inflammatory response by protein undernutrition in cardiopulmonary bypass

OBJECTIVEnCardiopulmonary bypass (CPB) is responsible for an inflammatory response that can lead to postoperative organ dysfunction. Undernutrition increases the risk of organ failure. We investigated the effect of undernutrition on the inflammatory response and mesenteric vascular reactivity induced by CPB in rats.nnnMETHODSnCPB was performed in Wistar rats given normal nutrition or protein undernutrition. Mesenteric artery contractility was determined in the presence of increasing concentrations of phenylephrine with or without nitric oxide synthase blockade. Relaxation was assessed in the presence of acetylcholine or sodium nitroprusside. The inflammatory response was evaluated by the measurement of systemic tumor necrosis factor-α at cannulation and after 150 min and by a histologic study of pulmonary and gut leukocyte infiltration.nnnRESULTSnCPB and protein undernutrition induced hypercontractility to phenylephrine and early relaxation defects in the mesenteric arteries. CPB caused endothelial dysfunction with early impairment of endothelium-dependent relaxation. Protein undernutrition led to an impaired relaxation of the mesenteric arteries, which was in part endothelium independent. Concomitantly, a significant inflammatory response was observed.nnnCONCLUSIONnCPB and undernutrition induce mesenteric hypercontractility to α1-adrenergics and impair vascular relaxation, without any additive effect of CPB on undernutrition. Undernutrition causes inflammation and a lack of vascular relaxation, probably involving smooth muscle contractile mechanisms.