Laurent Boyer

Prognostic impact of sleep-disordered breathing and its treatment with nocturnal ventilation for chronic heart failure.

To determine whether severity patterns or nocturnal ventilation to treat sleep‐disordered breathing (SDB) during chronic heart failure (CHF) is associated with adverse outcomes. Although SDB is frequent during CHF, the relationships between SDB and CHF outcomes are unknown.

Activation of Lung p53 by Nutlin-3a Prevents and Reverses Experimental Pulmonary Hypertension

Background— Induction of cellular senescence through activation of the p53 tumor suppressor protein is a new option for treating proliferative disorders. Nutlins prevent the ubiquitin ligase MDM2 (murine double minute 2), a negative p53 regulator, from interacting with p53. We hypothesized that cell senescence induced by Nutlin-3a exerted therapeutic effects in pulmonary hypertension (PH) by limiting the proliferation of pulmonary artery smooth muscle cells (PA-SMCs). Methods and Results— Nutlin-3a treatment of cultured human PA-SMCs resulted in cell growth arrest with the induction of senescence but not apoptosis; increased phosphorylated p53 protein levels; and expression of p53 target genes including p21, Bax, BTG2, and MDM2. Daily intraperitoneal Nutlin-3a treatment for 3 weeks dose-dependently reduced PH, right ventricular hypertrophy, and distal pulmonary artery muscularization in mice exposed to chronic hypoxia or SU5416/hypoxia. Nutlin-3a treatment also partially reversed PH in chronically hypoxic or transgenic mice overexpressing the serotonin-transporter in SMCs (SM22-5HTT+ mice). In these mouse models of PH, Nutlin-3a markedly increased senescent p21-stained PA-SMCs; lung p53, p21, and MDM2 protein levels; and p21, Bax, PUMA, BTG2, and MDM2 mRNA levels; but induced only minor changes in control mice without PH. Marked MDM2 immunostaining was seen in both mouse and human remodeled pulmonary vessels, supporting the use of Nutlins as a PH-targeted therapy. PH prevention or reversal by Nutlin-3a required lung p53 stabilization and increased p21 expression, as indicated by the absence of Nutlin-3a effects in hypoxia-exposed p53−/− and p21−/− mice. Conclusions— Nutlin-3a may hold promise as a prosenescence treatment targeting PA-SMCs in PH.

The Cyclooxygenase-2–Prostaglandin E2 Pathway Maintains Senescence of Chronic Obstructive Pulmonary Disease Fibroblasts

RATIONALEnChronic 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.nnnOBJECTIVESnThe 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.nnnMETHODSnFibroblasts 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.nnnMEASUREMENTS AND MAIN RESULTSnLung 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-β 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.nnnCONCLUSIONSnPGE2 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.

Heme Oxygenase-1 Prevents Airway Mucus Hypersecretion Induced by Cigarette Smoke in Rodents and Humans

We investigated the role of heme oxygenase-1 (HO-1), a powerful anti-inflammatory and anti-oxidant enzyme, in modulating cigarette smoke (CS)-induced mucus secretion. In both rats and mice, 5-day CS exposure increased HO-1 expression and activity, mucus secretion, MUCIN 5AC (MUC5AC) gene and protein expression, and local inflammation, along with up-regulation of dual oxidase 1 gene expression and both the activity and phosphorylation of the epidermal growth factor receptor, which is involved in MUC5AC induction. Pharmacological induction of HO-1 prevented these actions and inhibition of HO-1 expression by a specific siRNA potentiated them. In French participants to the European Community Respiratory Health Survey II (n = 210, 30 to 53 years of age, 50% males) exposed to CS, a significant increase in the percentage of participants with chronic sputum was observed in those harboring at least one allele with a long (GT)(n) in the HO-1 promoter gene (>33 repeats), which is associated with a low level of HO-1 protein expression, compared with those with a short number of (GT)n repeats (21.7% versus 8.6%, P = 0.047). No such results were observed in those who had never smoked (n = 297). We conclude that HO-1 has a significant protective effect against airway mucus hypersecretion in animals and humans exposed to CS.

Longitudinal and noninvasive assessment of emphysema evolution in a murine model using proton MRI

Ultrashort echo time (550 μs) MR imaging was implemented to track the emphysema development in mice lung challenged with elastase. Two parameters, namely, signal intensity and T u20092* , were used to monitor the disease evolution. Nine mice were imaged before and at 24 h as well as at 3 and 8 weeks after elastase instillation. Five mice instilled with saline served as controls. At week 8, the mean normalized signal intensity ± SD was 0.89 ± 0.20 for healthy controls and 0.64 ± 0.10 for animals with emphysema. Similarly, a reduced value of T u20092* (1.27 ± 0.35 ms vs 0.96 ± 0.18 ms) was found in the emphysema group. The mean signal intensity drop and the reduction of T u20092* were prominent at 3 weeks following elastase instillation and stabilized between 3 and 8 weeks. The results indicated an excellent agreement between MR findings and histological morphometry (signal intensity, r = −0.78, P = 0.004; T u20092* , r = −0.78, P = 0.001). This result shows that proton MRI allows structural changes at alveolar level to be monitored longitudinally. This technique, applied routinely in preclinical trials will represent a valuable tool for assessment of drug therapy efficacy. Magn Reson Med, 2012.

Daily administration of the TP receptor antagonist terutroban improved endothelial function in high-cardiovascular-risk patients with atherosclerosis

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECTn• Terutroban is a selective TP receptor antagonist, i.e. a specific antagonist of the thromboxane A(2) and prostaglandin endoperoxide receptors, shown to improve endothelial function after a single administration in patients with coronary artery disease.nnnWHAT THIS STUDY ADDSn• This randomized, double-blind, placebo-controlled trial demonstrates that repeated-dose terutroban for 15 days improves endothelial function and inhibits thromboxane A(2) -induced platelet aggregation in high-cardiovascular-risk patients taking 300 mg of aspirin per day. Terutroban may prove useful for preventing cardiovascular events in such patients.nnnAIMSnThe specific TP receptor antagonist terutroban improves endothelial function after a single dose in patients with coronary artery disease. Our aim was to evaluate the effects and dose dependency of repeated-dose terutroban on endothelial function and platelet aggregation in high-cardiovascular-risk patients with carotid atherosclerosis.nnnMETHODSnWe randomly allocated 48 patients taking 300 mg aspirin per day to placebo or to one of three terutroban dosages (2.5, 5 or 10 mg) for 15 days in a double-blind study. Flow-mediated vasodilatation was evaluated before and 2 h after the first oral dose on day 0 and 2 h after the last oral dose on day 14.nnnRESULTSnOn day 0 and day 14, all three terutroban dosages improved flow-mediated vasodilatation and abolished platelet aggregation induced by the TP receptor agonist U46619, without changing the aggregation response to ADP or collagen.nnnCONCLUSIONnTerutroban, by chronically improving endothelium-dependent vasodilatation and inhibiting platelet aggregation, may prove useful for preventing cardiovascular events in high-risk patients.

Xanthine oxidoreductase is a critical mediator of cigarette smoke-induced endothelial cell DNA damage and apoptosis

Cigarette smoke (CS) exposure is unquestionably the most frequent cause of emphysema in the United States. Accelerated pulmonary endothelial cell (EC) apoptosis is an early determinant of lung destruction in emphysema. One of the pathogenic causes of emphysema is an alveolar oxidant and antioxidant imbalance. The enzyme xanthine oxidoreductase (XOR) has been shown to be a source of reactive oxygen species (ROS) in a multitude of diseases (S. Sakao et al., FASEB J.21, 3640-3652; 2007). The contribution of XOR to CS-induced apoptosis is not well defined. Here we demonstrate that C57/bl6 mice exposed to CS have increased pulmonary XOR activity and protein levels compared to filtered-air-exposed controls. In addition, we demonstrate that primary pulmonary human lung microvascular endothelial cells exposed to cigarette smoke extract undergo increased rates of caspase-dependent apoptosis that are reliant on XOR activity, ROS production, and p53 function/expression. We also demonstrate that exogenous XOR is sufficient to increase p53 expression and induce apoptosis, suggesting that XOR is an upstream mediator of p53 in CS-induced EC apoptosis. Furthermore, we show that XOR activation results in DNA double-strand breaks that activate the enzyme ataxia telangiectasia mutated, which phosphorylates histone H2AX and upregulates p53. In conclusion, CS increases XOR expression, and the enzyme is both sufficient and necessary for p53 induction and CS-induced EC apoptosis.

Aging-related systemic manifestations in COPD patients and cigarette smokers.

Rationale Chronic obstructive pulmonary disease (COPD) is often associated with age-related systemic abnormalities that adversely affect the prognosis. Whether these manifestations are linked to the lung alterations or are independent complications of smoking remains unclear. Objectives To look for aging-related systemic manifestations and telomere shortening in COPD patients and smokers with minor lung destruction responsible for a decline in the diffusing capacity for carbon monoxide (DLCO) corrected for alveolar volume (KCO). Methods Cross-sectional study in 301 individuals (100 with COPD, 100 smokers without COPD, and 101 nonsmokers without COPD). Measurements and Main Results Compared to control smokers, patients with COPD had higher aortic pulse-wave velocity (PWV), lower bone mineral density (BMD) and appendicular skeletal muscle mass index (ASMMI), and shorter telomere length (TL). Insulin resistance (HOMA-IR) and glomerular filtration rate (GFR) were similar between control smokers and COPD patients. Smokers did not differ from nonsmokers for any of these parameters. However, smokers with normal spirometry but low KCO had lower ASMMI values compared to those with normal KCO. Moreover, female smokers with low KCO, had lower BMD and shorter TL compared to those with normal KCO. Conclusions Aging-related abnormalities in patients with COPD are also found in smokers with minor lung dysfunction manifesting as a KCO decrease. Decreased KCO might be useful, particularly among women, for identifying smokers at high risk for aging-related systemic manifestations and telomere shortening.

Telomere Dysfunction and Cell Senescence in Chronic Lung Diseases: Therapeutic Potential.

Cellular senescence--defined as a stable cell-cycle arrest combined with stereotyped phenotypic changes--might play a causal role in various lung diseases, including chronic obstructive pulmonary disease (COPD), which is predicted to become the third leading cause of death worldwide by 2020. COPD is characterized by slowly progressive airflow obstruction and emphysema due to destruction of the lung parenchyma and is often complicated by pulmonary hypertension (PH). No curative treatment is available. Senescent cells, which accumulate with age, are increased in lungs from patients with COPD and express a robust senescence-associated secretory phenotype (SASP), which is proinflammatory. The aim of this review is to show how senescent cells can drive the lung alterations seen in COPD, which mechanisms may be involved, and whether therapeutic interventions may slow or delay the in vitro cell-senescence process and in vivo lung alterations.

Macrophage migration inhibitory factor is a novel determinant of cigarette smoke-induced lung damage.

Cigarette smoke (CS) is the most common cause of chronic obstructive pulmonary diseases (COPD), including emphysema. CS exposure impacts all cell types within the airways and lung parenchyma, causing alveolar tissue destruction through four mechanisms: (1) oxidative stress; (2) inflammation; (3) protease-induced degradation of the extracellular matrix; and (4) enhanced alveolar epithelial and endothelial cell (EC) apoptosis. Studies in human pulmonary ECs demonstrate that macrophage migration inhibitory factor (MIF) antagonizes CS-induced apoptosis. Here, we used human microvascular ECs, an animal model of emphysema (mice challenged with chronic CS), and patient serum samples to address both the capacity of CS to alter MIF expression and the effects of MIF on disease severity. We demonstrate significantly reduced serum MIF levels in patients with COPD. In the murine model, chronic CS exposure resulted in decreased MIF mRNA and protein expression in the intact lung. MIF deficiency (Mif(-/-)) potentiated the toxicity of CS exposure in vivo via increased apoptosis of ECs, resulting in enhanced CS-induced tissue remodeling. This was linked to MIFs capacity to protect against double-stranded DNA damage and suppress p53 expression. Taken together, MIF appears to antagonize CS-induced toxicity in the lung and resultant emphysematous tissue remodeling by suppressing EC DNA damage and controlling p53-mediated apoptosis, highlighting a critical role of MIF in EC homeostasis within the lung.