Yves Castier

p47phox-Dependent NADPH Oxidase Regulates Flow-Induced Vascular Remodeling

Chronic alterations in blood flow elicit an adaptive response that tends to normalize shear stress, involving nitric oxide (NO) and matrix metalloproteinases (MMPs). To evaluate the role of NADPH oxidase in this process, we developed a new model of mouse arteriovenous fistula (AVF) connecting the right common carotid artery (RCCA) with the jugular vein, which does not affect blood pressure. Mice deficient for gp91phox and p47phox subunits of NADPH and wild-type controls were used. AVF greatly increased RCCA blood flow (0.78±0.12 to 4.71±0.78 mL/min; P<0.01), producing an abrupt rise in shear stress (35±1 to 261±17 dynes/cm2; P<0.01) within 24 hours. RCCA diameter (460±14 &mgr;m) gradually enlarged 1 and 3 weeks after AVF (534±14 &mgr;m and 627±19 &mgr;m; P<0.01), reducing shear stress (173±13 and 106±10 dynes/cm2, respectively). In gp91phox−/− mice, changes in RCCA caliber and shear stress matched controls. However, p47phox−/− mouse RCCAs enlarged only marginally, such that shear stress remained high (199±8 dynes/cm2 at 3 weeks). Likewise, remodeling was minimal in endothelial NO synthase (eNOS)−/− mice. In both control and gp91phox−/− animals, reactive oxygen species (ROS) production and MMP induction was enhanced by AVF, whereas in p47phox−/− and eNOS−/− mice such response was negligible. Similarly, nitrotyrosine staining, indicating peroxynitrite formation, was more pronounced in control and gp91phox−/− mice than in p47phox−/− and eNOS−/− mice. Hence, shear stress induces vascular NADPH oxidase comprising p47phox but not gp91phox. Generated ROS interact with NO to produce peroxynitrite, which in turn activates MMPs, facilitating vessel remodeling. Our study provides the first evidence that ROS play a fundamental role in flow-induced vascular enlargement.

Survival benefit of lung transplantation for patients with idiopathic pulmonary fibrosis

OBJECTIVE Although lung transplantation is viewed as an acceptable option for patients with end-stage idiopathic pulmonary fibrosis, the survival benefit of this approach is still debated. This study examined whether there was a survival benefit of lung transplantation in a cohort of patients referred to our transplant center with a diagnosis of idiopathic pulmonary fibrosis according to American Thoracic Society criteria. METHODS Forty-six patients accepted for lung transplantation during a 12-year period with a diagnosis of idiopathic pulmonary fibrosis form the basis of this study. Survival benefit offered by lung transplantation was assessed using Cox proportional-hazards modeling, with patients on a waiting list as the control group. RESULTS Twenty-eight patients underwent lung transplantation (27 single and 1 double), 16 patients died while waiting, and 2 patients remained on the active waiting list. Diagnosis of idiopathic pulmonary fibrosis was made on histologic examination of the explanted lung or lung biopsy before lung transplantation. There was a pattern of usual interstitial pneumonia in 31 cases (67%). The 15 remaining patients fulfilled all American Thoracic Society criteria for idiopathic pulmonary fibrosis. The median waiting time for organs was 51 days. Survival after lung transplantation was 79.4% at 1 year, 63.5% at 2 years, and 39% at 5 years. The multivariable analysis showed that lung transplantation reduced the risk of death by 75% (95% confidence interval, 8%-86%; P =.03) after adjustment on potential confounding variables. CONCLUSIONS Lung transplantation is effective in improving the survival of selected patients affected by idiopathic pulmonary fibrosis.

Microparticles From Human Atherosclerotic Plaques Promote Endothelial ICAM-1–Dependent Monocyte Adhesion and Transendothelial Migration

Rationale and Objective: Membrane-shed submicron microparticles (MPs) released following cell activation or apoptosis accumulate in atherosclerotic plaques, where they stimulate endothelial proliferation and neovessel formation. The aim of the study was to assess whether or not MPs isolated from human atherosclerotic plaques contribute to increased endothelial adhesion molecules expression and monocyte recruitment. Method and Results: Human umbilical vein and coronary artery endothelial cells were exposed to MPs isolated from endarterectomy specimens (n=62) and characterized by externalized phosphatidylserine. Endothelial exposure to plaque, but not circulating, MPs increased ICAM-1 levels in a concentration-dependant manner (3.4-fold increase) without affecting ICAM-1 mRNA levels. Plaque MPs harbored ICAM-1 and transferred this adhesion molecule to endothelial cell membrane in a phosphatidylserine-dependent manner. MP-borne ICAM-1 was functionally integrated into cell membrane as demonstrated by the increased ERK1/2 phosphorylation following ICAM-1 ligation. Plaque MPs stimulated endothelial monocyte adhesion both in culture and in isolated perfused mouse carotid. This effect was also observed under flow condition and was prevented by anti–LFA-1 and anti–ICAM-1 neutralizing antibodies. MPs isolated from symptomatic plaques were more potent in stimulating monocyte adhesion than MPs from asymptomatic patients. Plaque MPs did not affect the release of interleukin-6, interleukin-8, or MCP-1, nor the expression of VCAM-1 and E-selectin. Conclusion: These results demonstrate that MPs isolated from human atherosclerotic plaques transfer ICAM-1 to endothelial cells to recruit inflammatory cells and suggest that plaque MPs promote atherosclerotic plaque progression.

CD40 ligand+ microparticles from human atherosclerotic plaques stimulate endothelial proliferation and angiogenesis a potential mechanism for intraplaque neovascularization

OBJECTIVES Our goal was to demonstrate that microparticles (MPs) are the endogenous signal leading to neovessel formation through CD40 ligation in human atherosclerotic plaques. BACKGROUND Vulnerable atherosclerotic plaques prone to rupture are characterized by an increased number of vasa vasorum and frequent intraplaque hemorrhage. Although inflammatory cytokines, growth factors, or CD40/CD40 ligand (CD40L) are possible candidates, the mechanism of atherosclerotic plaque neovascularization remains unknown. Atherosclerotic plaques contain large amounts of membrane-shed submicron MPs released after cell activation or apoptosis. METHODS Microparticles were isolated from endarterectomy specimens surgically obtained from 26 patients and characterized by phosphatidylserine exposure and specific markers of cellular origin. RESULTS Plaque MPs increased both endothelial proliferation assessed by (3)H-thymidine incorporation and cell number and stimulated in vivo angiogenesis in Matrigel (BD Biosciences, San Diego, California) assays performed in wild-type and BalbC/Nude mice, whereas circulating MPs had no effect. Microparticles from symptomatic patients expressed more CD40L and were more potent in inducing endothelial proliferation, when compared with asymptomatic plaque MPs. Most of CD40L+ MPs (93%) isolated from human plaques were of macrophage origin. Microparticle-induced endothelial proliferation was impaired by CD40L or CD40-neutralizing antibodies and abolished after endothelial CD40-ribonucleic acid silencing. In addition, the proangiogenic effect of plaque MPs was abolished in Matrigel assays performed in the presence of CD40L-neutralizing antibodies or in CD40-deficient mice. CONCLUSIONS These results demonstrate that MPs isolated from human atherosclerotic lesions express CD40L, stimulate endothelial cell proliferation after CD40 ligation, and promote in vivo angiogenesis. Therefore, MPs could represent a major determinant of intraplaque neovascularization and plaque vulnerability.

Survival after bilateral versus single lung transplantation for patients with chronic obstructive pulmonary disease: a retrospective analysis of registry data

BACKGROUND Both single and bilateral lung transplantation are recognised options for patients who have end-stage chronic obstructive pulmonary disease (COPD); however, which procedure leads to longer survival remains unclear. We aimed to compare survival after each procedure by analysing data from the registry of the International Society for Heart and Lung Transplantation. METHODS We analysed data for 9883 patients with COPD, 3525 (35.7%) of whom underwent bilateral lung transplantation, and 6358 (64.3%) single lung transplantation, between 1987 and 2006. We accounted for possible selection bias with analysis of covariance, propensity-score risk adjustment, and propensity-based matching. FINDINGS Median survival after either type of lung transplantation for patients with COPD was 5.0 years (95% CI 4.8-5.2). Survival for patients who had lung transplantation before 1998 was 4.5 years (4.3-4.8), compared with 5.3 years (5.0-5.5) for those who had it after 1998 (p<0.0001). The proportion of patients who had bilateral lung transplantation increased from 101/467 (21.6%) in 1993 to 345/614 (56.2%) in 2006. Median survival time after bilateral lung transplantation was longer than that after single lung transplantation: 6.41 years (6.02-6.88) versus 4.59 years (4.41-4.76) (p<0.0001). Pretransplant characteristics of patients who had single and bilateral lung transplantation differed, but whichever method was used to adjust for baseline differences, bilateral lung transplantation was associated with longer survival than was single lung transplantation; the hazard ratio ranged from 0.83 (0.78-0.92) for analysis of covariance to 0.89 (0.80-0.97) for propensity-based matching. However, bilateral lung transplantation had little benefit compared with single lung transplantation for patients who were 60 years and older (HR 0.95; 0.81-1.13). INTERPRETATION Bilateral lung transplantation leads to longer survival than single lung transplantation in patients with COPD, especially those who are younger than 60 years.

Survival after bilateral versus single-lung transplantation for idiopathic pulmonary fibrosis.

Context Patients with end-stage lung disease caused by idiopathic pulmonary fibrosis often have bilateral lung transplantation, but the benefits of this procedure over single-lung transplantation are unclear. Contribution In this comparison of outcomes for patients who received 1 or 2 lungs, overall survival did not differ but causes of death did. Bilateral transplantation seemed to increase mortality in the first year and decrease mortality thereafter. Caution Unmeasured variables associated with transplantation might have contributed to the studys findings. Implication Single and bilateral lung transplantation carry different short- and long-term benefits and harms for patients with idiopathic pulmonary fibrosis. The Editors Idiopathic pulmonary fibrosis (IPF) often progresses to end-stage lung disease and is the second most common reason for lung transplantation (1, 2), accounting for more than 25% of lung transplantation procedures (2). The procedure can involve single or bilateral lung transplantation (13). Single-lung transplantation was considered the procedure of choice after the first report of successful transplantation for patients with IPF by the Toronto Group (4, 5). However, patients with IPF are having bilateral lung transplantation with greater frequency, and the procedure now accounts for almost 50% of all lung transplantations in patients with IPF (2). The reason for this progressive shift toward bilateral transplantation is unclear. Because no randomized, controlled studies have addressed this issue, current evidence comes from observational studies and yields conflicting results (69). Using data from the United Network for Organ Sharing (UNOS), we aimed to compare survival rates after single and bilateral lung transplantation for patients with IPF by using multivariate model risk adjustment, propensity score risk adjustment, and propensity-based matching techniques to account for confounding factors. Methods Patients The UNOS supplied all data as a standard analysis and research file, based on Organ Procurement and Transplantation Network data as of February 2009, and included coded transplant-center identifiers. The registry contains data on all patients who had lung transplantation in the United States since the registrys inception in 1987. Before May 2005, recipients were allocated organs on the basis of wait-list times. Since May 2005, priority on the waiting list has been determined by the Lung Allocation Score, which ranks patients according to the difference between survival benefit and survival on the waiting list (10). All adult patients were eligible for the study if they had cadaveric single or bilateral lung transplantation for IPF (code 1604 of the UNOS data set) and the date of transplantation, date of last follow-up, and vital status at last follow-up were known. We collected data on donor, surgery, and recipient characteristics at the time of transplantation from the UNOS registry. We excluded variables for which data were sparse or those that described clinically uncommon or rare characteristics, and we calculated several variables from those that were available (such as donor and recipient body mass indexes and mismatches of sex and blood type). The Appendix Table lists the variables we included in the analyses. Appendix Table. Variables Tested for Association With Survival After Lung Transplantation Outcomes The primary outcome was recipient survival. We assessed cause of death of the lung recipient as a secondary end point. Statistical Analysis We adjusted for confounding factors by using multivariate model risk adjustment, propensity-score risk adjustment, and matching on the propensity score. Multivariate model risk adjustment is a conventional modeling approach that incorporates all known confounders, including interactions, into a regression model. Controlling for these confounders produces a risk-adjusted treatment effect and removes overt bias due to these factors. We used Cox proportional hazards regression models to compare mortality rates between the single and bilateral lung transplantation groups, adjusted for covariates. We used purposeful selection of covariates, as described by Hosmer and Lemeshow (11), to select the multivariate model. The first step was the inclusion of all variables significant at the 20% level in the bivariate analysis, as well as all variables known to be clinically relevant (12). The second step was to remove, one by one, variables that did not significantly contribute to the multivariate model on the basis of the Wald test P value and the change in the coefficient of the remaining variables. We assessed the scale of the continuous covariates by using residual analysis (13). We only considered first-order interactions with surgical procedure. We took transplant center effects into account by including centers in the multivariate analyses as a random effect with a Gaussian distribution. Residual plots supported a linear relation between all continuous covariates and the log hazard for death. No significant interaction was retained in the final model; interactions between age at transplantation and procedure and between systolic pulmonary artery pressure and procedure were not significant. The final model included recipient variables (age, body mass index, functional status, and mean pulmonary artery pressure), donor variables (body mass index and cytomegalovirus status), and procedure-related variables (transplantation year, surgical procedure, lung transplantation center, and lung transplantation center volume). In our analyses of cause of death, we used the cumulative incidence estimator and the proportional subdistribution hazard model described by Fine and Gray (14) to account for competing causes. Propensity scores estimate the probability that a patient with specific pretreatment characteristics will receive a treatment, in this case bilateral rather than single-lung transplantation (15, 16). Within propensity score strata, covariates in both groups tend to be similarly distributed. We computed propensity scores by using logistic regression, in which surgical procedure was the dependent variable and the variables listed in the Appendix Table were independent variables. We judged the success of the propensity score modeling by assessing balance on baseline characteristics within deciles of propensity score or after matching propensity scores for patients in the single and bilateral lung transplantation groups, and found balanced distribution of variables within deciles. We used Cox proportional hazards regression to estimate the effect of bilateral lung transplantation on survival, adjusting for the propensity score (on the linear predictor scale) and surgical procedure. In another analysis, we took only data with propensity score overlap into account and adjusted the estimates on the deciles of the propensity score. We used a 1:1 matching algorithm without replacement to match patients, with calipers defined to have a maximum width of 0.25 SD of the logit of the estimated propensity score. We used marginal Cox models, accounting for correlation within matched pairs, to compare the single and bilateral lung transplantation groups in terms of adjusted survival (17). We used several statistical methods to assess whether the effect of surgical procedure was constant over time (proportional hazards assumption), including residual plots (as described by Grambsch and Therneau [18]) and fitting of additive regression models (as described by Aalen [19]). For variables involved in the multivariate model risk adjustment and propensity score analysis, we imputed missing data by using the multiple imputations by chained equation method (20), which resulted in 20 imputed data sets. We independently analyzed each of the 20 data sets. We averaged estimates of the variables to give a single mean estimate and adjusted SEs according to the Rubin rules (2022). The Appendix lists the steps of the imputation procedure. All analyses were performed by using R, version 2.5 (R Foundation for Statistical Computing, Vienna, Austria), and Stata, version 10.2 (StataCorp, College Station, Texas), for Windows XP. Propensity-score matching was done by using the Matching package for R. Role of the Funding Source This study received no funding. The authors had full access to all data in the study and had final responsibility for the decision to submit for publication. Results The UNOS database included data for 33252 patients registered on a waiting list for lung transplantation in the United States during the study period; 18333 (55.1%) had lung transplantation. Of these, 3411 (18.6%) had received a diagnosis of IPF at the time of transplantation. We excluded 11 patients who received grafts from nonheart-beating donors, 25 patients who were younger than 18 years at the time of transplantation, and 48 patients whose survival time was unknown. The final analysis included the remaining 3327 patients who had lung transplantation in 88 U.S. centers (median, 120 lung transplantations per center [25th to 75th percentile, 22 to 323 transplantations per center]). The number of patients who had lung transplantation for IPF increased over time, from 59 in 1992 to 409 in 2008; 2146 (64.5%) had single-lung transplantation and 1181 (35.5%) had bilateral lung transplantation. The proportion of patients who had bilateral lung transplantation also increased over time, from 6 of 59 total procedures (10.2%) in 1992 to 223 of 409 procedures (54.5%) in 2008 (Appendix Figure 1). Appendix Figure 2 shows the proportion of bilateral lung transplantation by transplant-ation center volumes for IPF and all indications and suggests that high-volume centers were more likely than low-volume centers to perform bilateral lung transplantation. Appendix Figure 1. Rates of single and bilateral lung transplantation over time in patients with idiopathic pulmonary fibrosis. Data are from the United

Vascular complications of transfemoral aortic valve implantation with the Edwards SAPIEN prosthesis: incidence and impact on outcome.

AIMS Vascular complications remain the main limitation of transfemoral aortic valve implantation. Based on a single-centre experience, we aim to detail the type, management and impact of those vascular complications. METHODS AND RESULTS From October 2006 to January 2009, 54 transfemoral aortic valve implantations were performed using the Edwards SAPIEN prosthesis. Nine patients (16.7%) developed vascular complications. Five patients (9.3%) had ruptures which necessitated a surgical bypass. Four patients (7.4%) had dissection necessitating repair using stenting in all four patients and associated bypass in two of them. Vascular complications led to death in one patient (1.9%), reintervention in one (1.9%), and transfusions in seven (13%). Five vascular complications occurred in the first 20 patients (25%), and only four in the last 34 (12%). CONCLUSIONS Vascular complications of transfemoral aortic valve implantation are frequent and seem to be influenced by experience. They are associated with a high need for transfusion and could lead to major events such as death or reintervention. These findings highlight the importance of a multidisciplinary approach for patient selection and management of the procedure.

Determinants of the Survival Benefit of Lung Transplantation in Patients with Chronic Obstructive Pulmonary Disease

RATIONALE Although chronic obstructive pulmonary disease is the first indication for lung transplantation, the benefit of the procedure in terms of survival remains debated. OBJECTIVES To estimate the determinants of the survival benefit of lung transplantation in patients with chronic obstructive pulmonary disease. METHODS Using information from the United Network for Organ Sharing database on 8,182 patients, we developed an approach based on numerical simulations to estimate the survival effect of lung transplantation. MEASUREMENTS AND MAIN RESULTS The main outcome measure was the difference between median survival with transplantation and that without transplantation measured from time of transplant list registration. Survival benefit was greater with double than with single lung transplantation (mean difference, 307 d [95% confidence interval, 217-523]). With double lung transplantation, 44.6% of patients would gain 1 year or more, 29.4% would gain or lose less than 1 year, and 26% would lose 1 year or more. Major determinants of the survival effect of transplantation were systolic pulmonary artery pressure, FEV(1), body mass index, exercise capacity, functional status, and the need for continuous mechanical ventilation or oxygen. For instance, 79% of patients with an FEV(1) less than 16% of the predicted value would gain 1 year or more with double lung transplantation as compared with only 11% of patients with an FEV(1) of more than 25%. CONCLUSIONS We identified several factors associated with the survival benefit of lung transplantation. External validation of our models is required before translating these results into clinical practice.

Survival Benefit of Lung Transplant for Cystic Fibrosis since Lung Allocation Score Implementation

RATIONALE The survival benefit of lung transplantation (LT) in adult patients with cystic fibrosis (CF) is debated. OBJECTIVES We sought to assess the survival benefit of LT in adult patients with CF. METHODS We used data from the United Network for Organ Sharing Registry to identify adult patients with CF on a wait list for LT in the United States between 2005 and 2009. Survival times while on the wait list and after LT were modeled by use of a Cox model that incorporated transplantation status as a time-dependent covariate. Evolution in lung allocation score (LAS) while on the wait list was used as a surrogate for disease severity. We fitted a model for the joint distribution of survival and longitudinal disease process (LAS over time). MEASUREMENTS AND MAIN RESULTS A total of 704 adult patients with CF were registered on a wait list during the study period. The cumulative incidence of LT was 39.3% (95% confidence interval, 35.6-42.9%) at 3 months and 64.7% (61.0-68.4%) at 12 months, whereas the incidence of death while on the wait list at the same times was 8.5% (6.4-10.6%) and 12.9% (10.3-15.5%), respectively. Survival after LT was 96.5% (94.7-98.2%) at 3 months; 88.4% (85.1-91.8%) at 12 months; and 67.8% (59.9-76.8%) at 3 years. LT conferred a 69% reduction in the instantaneous risk of death (51-80%). The interaction between LAS and LT was significant: the higher the LAS, the greater the survival benefit of LT (P < 0.001). CONCLUSIONS LT confers a survival benefit for adult patients with CF.

Carotid artery revascularization through a radiated field.

OBJECTIVE Extracranial carotid stenosis is a complication of external head and neck irradiation. The safety and durability of carotid artery revascularization through a radiated field has been debated. We describe the immediate and long-term results in a series of 27 consecutive patients who received treatment over 12 years. METHODS From May 1990 to May 2002, 27 consecutive patients underwent 30 primary carotid artery revascularization procedures. All patients had received previous radiation therapy within a mean interval of 10 years (range, 1-26 years), with average radiation dose of 62 Gy (range, 50-70 Gy). Moderate to severe scarring of the skin or radiation fibrosis was present in three fourths of patients. Thirteen patients (48%) had undergone radical neck dissection, and 2 patients had a permanent tracheotomy. The indications for carotid surgery included high-grade (>70%) symptomatic stenosis in 18 patients (60%) and high-grade asymptomatic stenosis in 12 patients (40%). General anesthesia with systematic shunting was used in 18 patients (60%), and regional anesthesia with selective shunting was used in 12 patients (40%). Operations included standard carotid endarterectomy (n = 20), with patch angioplasty (n = 12) or direct closure (n = 8); carotid interposition bypass grafting (n = 7); and subclavian to carotid bypass grafting (n = 3). Primary closure of the surgical wound was performed in all procedures without any special muscular or skin flaps. All patients were followed up for a mean of 40 months (range, 3-99 months). RESULTS There was one (3.3%) perioperative death, from massive intracerebral hemorrhage; and 1 patient had a transient ischemic attack. In-hospital complications included neck hematoma in 2 patients, which required surgical drainage in 1 patient. There was neither delayed wound healing nor infection. Twelve patients died during follow-up, of causes not related to treatment. None of the surviving patients had further stroke, and all remained asymptomatic. Follow-up duplex scans showed asymptomatic recurrent stenosis greater than 60% in 3 patients, 2 of whom with stenosis greater than 80% underwent repeat operation. Risk for recurrent stenosis greater than 60% at 18 months was 16.6%. Recurrent stenosis occurred in 2 of these patients after saphenous vein bypass, and in 1 patient after endarterectomy with vein patch angioplasty. CONCLUSION The clinical results and sustained freedom from symptoms and stroke over 40-month follow-up suggests that carotid revascularization through a radiated field is a safe and durable procedure in patients at high surgical risk, despite a marked incidence of recurrent stenosis.