Prognostic Significance of Pulmonary Multifocal Neuroendocrine Proliferation With Typical Carcinoid

BACKGROUND

The clinical significance of multifocal pulmonary neuroendocrine proliferation (MNEP), including tumorlets and pulmonary neuroendocrine cell hyperplasia, in association with typical carcinoid (TC), is still debated.

METHODS

We evaluated a retrospective series of TC with long-term follow-up data prospectively collected from 2 institutions and compared the outcome between TC alone and MNEP plus TC. Several baseline covariates were imbalanced between the MNEP plus TC and TC groups; therefore, we conducted 1:1 propensity score matching and inverse probability of treatment weighting in the full sample. In the matched group, the association of clinical, respiratory, and work-related factors with the group was determined through univariable and multivariable conditional logistic regression analysis.

RESULTS

A total of 234 TC patients underwent surgery: 41 MNEP plus TC (17.5%) and 193 TC alone (82.5%). In the MNEP plus TC group, older age (P < .001), peripheral tumors (P = .0032), smaller tumor size (P = .011), and lymph node spread (P = .02) were observed compared with the TC group. Relapses occurred in 8 patients in the MNEP plus TC group (19.5%) and 7 in the TC group (3.6%). After matching, in 36 pairs of patients, a significantly higher 5-year progression-free rate was observed for the TC group (P < .01). Similar results were observed using inverse probability of treatment weighting in the full sample. The odds of being in the MNEP plus TC group was higher for those with work-related exposure to inhalant agents (P = .008), asthma or bronchitis (P = .002), emphysema, fibrosis, and inflammatory status (P = .032), or micronodules on the chest computed tomography scan and respiratory insufficiency (P = .036).

CONCLUSIONS

The association with MNEP seems to represent a clinically and prognostic relevant factor in TC. Hence, careful preoperative workup, systematic pathologic evaluation, including nontumorous lung parenchyma, and long-term postoperative follow-up should be recommended in these patients.

Soluble Adhesion Molecules During Ex Vivo Lung Perfusion Are Associated With Posttransplant Primary Graft Dysfunction

Ex vivo lung perfusion (EVLP) enables assessment of marginal donor lungs for transplantation. We aimed to discover biomarkers in EVLP perfusate that could predict development of primary graft dysfunction (PGD). From September 2008 to August 2013, 100 clinical EVLPs were performed. Eleven patients developed PGD grade 3 within 72 h after transplant. The non-PGD group consisted of 34 patients without PGD grade 3. Nonbilateral lung transplants or transplant after extracorporeal life support were excluded from analyses. Soluble intercellular adhesion molecule 1 (sICAM-1), soluble VCAM-1 (sVCAM-1), and soluble E selectin (sE-selectin) levels, as markers of endothelial activation, were measured in the perfusate of EVLP by enzyme-linked immunosorbent assay and were correlated with clinical outcome. Levels of sICAM-1 at 1 h and sVCAM-1 at 1 and 4 h were significantly higher in the PGD group compared with the non-PGD group. The sE selectin levels were not statistically different between the study groups. Higher levels of sVCAM-1 at 1 and 4 h were statistically significantly associated with PGD either alone or after adjustment for other PGD risk factors. These adhesion molecules may help identify donor lungs at higher risk of PGD during EVLP.

Successful Lung Transplantation From Hepatitis C Positive Donor to Seronegative Recipient

Lung transplantation using RNA+ hepatitis C (HCV+) donors to seronegative recipients is not currently performed due to the very high risk of transmission. Previous reports have shown poor survival when this practice was applied. The emergence of new direct-acting antiviral drugs (DAA) suggests a high chance of sustained virologic response in immunocompetent patients. We report here successful transplantation of lungs from HCV+ donor to HCV- recipient. The recipient was an HCV- patient with chronic lung allograft dysfunction. Viral transmission occurred early posttransplant but excellent clinical outcomes were observed including elimination of HCV after 12 weeks of treatment using DAAs.

Ex Vivo Perfusion Treatment of Infection in Human Donor Lungs

Ex vivo lung perfusion (EVLP) is a platform to treat infected donor lungs with antibiotic therapy before lung transplantation. Human donor lungs that were rejected for transplantation because of clinical concern regarding infection were randomly assigned to two groups. In the antibiotic group (n = 8), lungs underwent EVLP for 12 h with high-dose antibiotics (ciprofloxacin 400 mg or azithromycin 500 mg, vancomycin 15 mg/kg, and meropenem 2 g). In the control group (n = 7), lungs underwent EVLP for 12 h without antibiotics. A quantitative decrease in bacterial counts in bronchoalveolar lavage (BAL) was found in all antibiotic-treated cases but in only two control cases. Perfusate endotoxin levels at 12 h were significantly lower in the antibiotic group compared with the control group. EVLP with broad-spectrum antibiotic therapy significantly improved pulmonary oxygenation and compliance and reduced pulmonary vascular resistance. Perfusate endotoxin levels at 12 h were strongly correlated with levels of perfusates tumor necrosis factor α, IL-1β and macrophage inflammatory proteins 1α and 1β at 12 h. In conclusion, EVLP treatment of infected donor lungs with broad-spectrum antibiotics significantly reduced BAL bacterial counts and endotoxin levels and improved donor lung function.

Lung transplantation with donation after circulatory determination of death donors and the impact of ex vivo lung perfusion

The growing demand for suitable lungs for transplantation drives the quest for alternative strategies to expand the donor pool. The aim of this study is to evaluate the outcomes of lung transplantation (LTx) with donation after circulatory determination of death (DCDD) and the impact of selective ex vivo lung perfusion (EVLP). From 2007 to 2013, 673 LTx were performed, with 62 (9.2%) of them using DCDDs (seven bridged cases). Cases bridged with mechanical ventilation/extracorporeal life support were excluded. From 55 DCDDs, 28 (51%) underwent EVLP. Outcomes for LTx using DCDDs and donation after neurological determination of death (DNDD) donors were similar, with 1 and 5-year survivals of 85% and 54% versus 86% and 62%, respectively (p = 0.43). Although comparison of survival curves between DCDD + EVLP versus DCDD-no EVLP showed no significant difference, DCDD + EVLP cases presented shorter hospital stay (median 18 vs. 23 days, p = 0.047) and a trend toward shorter length of mechanical ventilation (2 vs. 3 days, p = 0.059). DCDDs represent a valuable source of lungs for transplantation, providing similar results to DNDDs. EVLP seems an important technique in the armamentarium to safely increase lung utilization from DCDDs; however, further studies are necessary to better define the role of EVLP in this context.

Survival in sensitized lung transplant recipients with perioperative desensitization

Donor-specific HLA antibodies (DSA) have an adverse effect on short-term and long-term lung transplant outcomes. We implemented a perioperative strategy to treat DSA-positive recipients, leading to equivalent rejection and graft survival outcomes. Pretransplant DSA were identified to HLA-A, B, C, DR and DQ antigens. DSA-positive patients were transplanted if panel reactive antibody (PRA) ≥30% or medically urgent and desensitized with perioperative plasma exchange, intravenous immune globulin, antithymocyte globulin (ATG), and mycophenolic acid (MPA). PRA-positive/DSA-negative recipients received MPA. Unsensitized patients received routine cyclosporine, azathioprine and prednisone without ATG. From 2008-2011, 340 lung-only first transplants were performed: 53 DSA-positive, 93 PRA-positive/DSA-negative and 194 unsensitized. Thirty-day survival was 96 %/99%/96% in the three groups, respectively. One-year graft survival was 89%/88%/86% (p = 0.47). DSA-positive and PRA-positive/DSA-negative patients were less likely to experience any ≥ grade 2 acute rejection (9% and 9% vs. 18% unsensitized p = 0.04). Maximum predicted forced expiratory volume (1 s) (81%/74%/76%, p = NS) and predicted forced vital capacity (81%/77%/78%, respectively, p = NS) were equivalent between groups. With the application of this perioperative treatment protocol, lung transplantation can be safely performed in DSA/PRA-positive patients, with similar outcomes to unsensitized recipients.

Distinct expression patterns of alveolar "alarmins" in subtypes of chronic lung allograft dysfunction

The long-term success of lung transplantation is limited by chronic lung allograft dysfunction (CLAD). The purpose of this study was to investigate the alveolar alarmin profiles in CLAD subtypes, restrictive allograft syndrome (RAS) and bronchiolitis obliterans syndrome (BOS). Bronchoalveolar lavage (BAL) samples were collected from 53 recipients who underwent double lung or heart-lung transplantation, including patients with RAS (n = 10), BOS (n = 18) and No CLAD (n = 25). Protein levels of alarmins such as S100A8, S100A9, S100A8/A9, S100A12, S100P, high-mobility group box 1 (HMGB1) and soluble receptor for advanced glycation end products (sRAGE) in BAL fluid were measured. RAS and BOS showed higher expressions of S100A8, S100A8/A9 and S100A12 compared with No CLAD (p < 0.0001, p < 0.0001, p < 0.0001 in RAS vs. No CLAD, p = 0.0006, p = 0.0044, p = 0.0086 in BOS vs. No CLAD, respectively). Moreover, RAS showed greater up-regulation of S100A9, S100A8/A9, S100A12, S100P and HMGB1 compared with BOS (p = 0.0094, p = 0.038, p = 0.041, p = 0.035 and p = 0.010, respectively). sRAGE did not show significant difference among the three groups (p = 0.174). Our results demonstrate distinct expression patterns of alveolar alarmins in RAS and BOS, suggesting that RAS and BOS may represent biologically different subtypes. Further refinements in biologic profiling will lead to a better understanding of CLAD.

Impact of cytokine expression in the pre-implanted donor lung on the development of chronic lung allograft dysfunction subtypes

The long-term success of lung transplantation continues to be challenged by the development of chronic lung allograft dysfunction (CLAD). The purpose of this study was to investigate the relationship between cytokine expression levels in pre-implanted donor lungs and the posttransplant development of CLAD and its subtypes, bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). Of 109 patients who underwent bilateral lung or heart-lung transplantation and survived for more than 3 months, 50 BOS, 21 RAS and 38 patients with No CLAD were identified by pulmonary function test results. Using donor lung tissue biopsies sampled from each patient, expression levels of IL-6, IL-1β, IL-8, IL-10, interferon-γ and tumor necrosis factor-α mRNA were measured. IL-6 expression levels were significantly higher in pre-implanted lungs of patients that ultimately developed BOS compared to RAS and No CLAD (p = 0.025 and 0.011, respectively). Cox regression analysis demonstrated an association between high IL-6 expression levels and BOS development (hazard ratio = 4.98; 95% confidence interval = 2.42-10.2, p < 0.001). In conclusion, high IL-6 mRNA expression levels in pre-implanted donor lungs were associated with the development of BOS, not RAS. This association further supports the contention that early graft injury impacts on both late graft function and early graft function.

Pilot study exploring lung allograft surfactant protein A (SP-A) expression in association with lung transplant outcome

Primary graft failure and chronic lung allograft dysfunction (CLAD) limit lung transplant long-term outcomes. Various lung diseases have been correlated with surfactant protein (SP) expression and polymorphisms. We sought to investigate the role of SP expression in lung allografts prior to implantation, in relation to posttransplant outcomes. The expression of SP-(A, B, C, D) mRNA was assayed in 42 allografts. Posttransplant assessments include pulmonary function tests, bronchoscopy, broncho-alveolar lavage fluid (BALF) and biopsies to determine allograft rejection. BALF was assayed for SP-A, SP-D in addition to cytokines IL-8, IL-12 and IL-2. The diagnosis of CLAD was evaluated 6 months after transplantation. Lung allografts with low SP-A mRNA expression prior to implantation reduced survival (Log-rank p < 0.0001). No association was noted for the other SPs. Allografts with low SP-A mRNA had greater IL-2 (p = 0.03) and IL-12 (p < 0.0001) in the BALF and a greater incidence of rejection episodes (p = 0.003). Levels of SP-A mRNA expression were associated with the SP-A2 polymorphisms (p = 0.015). Specifically, genotype 1A1A(0) was associated with lower SP-A mRNA expression (p < 0.05). Lung allografts with low levels of SP-A mRNA expression are associated with reduced survival. Lung allograft SP-A mRNA expression appears to be associated with SP-A gene polymorphisms.

Normothermic ex vivo perfusion prevents lung injury compared to extended cold preservation for transplantation

Treatment of injured donor lungs ex vivo to accelerate organ recovery and ameliorate reperfusion injury could have a major impact in lung transplantation. We have recently demonstrated a feasible technique for prolonged (12 h) normothermic ex vivo lung perfusion (EVLP). This study was performed to examine the impact of prolonged EVLP on ischemic injury. Pig donor lungs were cold preserved in Perfadex for 12 h and subsequently divided into two groups: cold static preservation (CSP) or EVLP at 37 degrees C with Steen solution for a further 12 h (total 24 h preservation). Lungs were then transplanted and reperfused for 4 h. EVLP preservation resulted in significantly better lung oxygenation (PaO(2) 531 +/- 43 vs. 244 +/- 49 mmHg, p < 0.01) and lower edema formation rates after transplantation. Alveolar epithelial cell tight junction integrity, evaluated by zona occludens-1 protein staining, was disrupted in the cell membranes after prolonged CSP but not after EVLP. The maintenance of integrity of barrier function during EVLP translates into significant attenuation of reperfusion injury and improved graft performance after transplantation. Integrity of functional metabolic pathways during normothermic perfusion was confirmed by effective gene transfer and GFP protein synthesis by lung alveolar cells. In conclusion, EVLP prevents ongoing injury associated with prolonged ischemia and accelerates lung recovery.

Gender differences in pulmonary regenerative response to naphthalene-induced bronchiolar epithelial cell injury

OBJECTIVES

Accumulating evidence suggests that gender affects the incidence and severity of several pulmonary diseases. Previous studies on mice have shown gender differences in susceptibility to naphthalene-induced lung injury, where Clara cell damage was found to occur earlier and to be more extensive in females than in males. However, very little is known about whether there are any gender differences in subsequent lung repair responses. The aim of this study was to investigate whether gender plays an important role in pulmonary regenerative response to naphthalene-induced Clara cell ablation.

MATERIALS AND METHODS

Adult male and female mice were injected with a low, medium, or high dose of naphthalene, and lung tissue regeneration was examined by immunohistochemical staining for cell proliferation marker (Ki-67) and mitosis marker (phosphohistone-3).

RESULTS

Histopathological analysis showed that naphthalene-induced Clara cell necrosis was more prominent in the lungs of female mice as compared to male mice. Cell proliferation and mitosis in both the distal bronchiolar airway epithelium and peribronchiolar interstitium of female mice was significantly greater than that of male mice after treatment with the low and medium doses. However, after treatment with high dose of naphthalene, lung regeneration was delayed in female mice, while male mice mounted a timely regenerative response.

CONCLUSIONS

These findings show that there are clear gender differences in naphthalene-induced lung injury and repair.

MMP-dependent migration of extrapulmonary myofibroblast progenitors contributing to posttransplant airway fibrosis in the lung

Myofibroblasts play a central role in fibroproliferative airway remodeling in obliterative bronchiolitis (OB) after lung transplantation. The purpose of the study is to elucidate the mechanisms whereby matrix metalloproteinases (MMPs) contribute to myofibroblast-mediated allograft airway fibrosis. In an intrapulmonary tracheal transplant model of OB, broad-spectrum MMP inhibitors, SC080 and MMI270 reduced the number of myofibroblasts at day 28 without changing differentiation, proliferation or apoptosis of myofibroblasts or fibroblasts. Next, myofibroblasts in allograft airway fibrosis were demonstrated to be almost exclusively of extrapulmonary origin by analyzing RT1A(n) positive myofibroblasts in an animal model combining orthotopic lung transplantation (from Lewis (RT1A(l)) to F1 (Brown-Norway (RT1A(n)) x Lewis)) and intrapulmonary tracheal transplantation (from a Wister-Furth rat (RT1A(u)) into the transplanted Lewis-derived lung). Using peripheral blood mononuclear cells (PBMCs) that can differentiate into alpha-SMA positive myofibroblasts in vitro, we demonstrated their contribution to the myofibroblast population of allograft airway fibrosis in vivo using a fluorescence-labeling cell tracking system. Moreover, PBMC-derived fibroblast-like cells expressed high levels of MMP-9 and MMP-12 and their migration was inhibited by MMP inhibitors in a wound healing assay. In conclusion, MMP-dependent migration of PBMC-derived myofibroblast precursors is an important contributing mechanism to the development of allograft airway fibrosis.

Impact of human donor lung gene expression profiles on survival after lung transplantation: a case-control study

Primary graft dysfunction (PGD) continues to be a major cause of early death after lung transplantation. Moreover, there remains a lack of accurate pretransplant molecular markers for predicting PGD. To identify distinctive donor lung gene expression signatures associated with PGD, we profiled human donor lungs using microarray technology prior to implantation. The genomic profiles of 10 donor lung samples from patients who subsequently developed clinically defined severe PGD were compared with 16 case-matched donor lung samples from those who had a favorable outcome without PGD (development set, n = 26). Selected PCR validated predictive genes were tested by quantitative reverse transcription-polymerase chain reaction in an independent test set (n = 81). Our microarray analyses of the development set identified four significantly upregulated genes (ATP11B, FGFR2, EGLN1 and MCPH1) in the PGD samples. These genes were also significantly upregulated in donor samples of the test set of patients with poor outcomes when compared to those of patients with good outcomes after lung transplantation. This type of biological donor lung assessment shows significant promise for development of a more accurate diagnostic strategy to assess donor lungs prior to implantation.

Allograft airway fibrosis in the pulmonary milieu: a disorder of tissue remodeling

Obliterative bronchiolitis (OB) is thought to be a form of chronic allograft rejection. However, immunosuppressive therapy is not effective once fibrosis has developed. We hypothesize that disordered tissue remodeling is a mechanism for the pathogenesis of OB. We examined allograft airway fibrosis in an intrapulmonary tracheal transplant model of OB. Allograft airways were completely obliterated at day 21 by fibrotic tissue; however, tissue remodeling continued thereafter, as demonstrated by the change of collagen deposition density, shift from type I to type III collagen, shift from fibroblasts to myofibroblasts and shift of expression profiles and activities of matrix metalloproteinases (MMPs). We then used a broad-spectrum MMP inhibitor, SC080, to attempt to manipulate tissue remodeling. Administration of the MMP inhibitor from day 0 to day 28 reduced airway obliteration, without inhibiting T-cell activation. MMP inhibition from day 14 to day 28 showed similar effects on airway obliteration. MMP inhibition from day 21 to day 35 did not reverse the airway obliteration, but significantly reduced the collagen deposition, type III collagen and myofibroblasts in the lumen. We conclude that tissue remodeling plays a critical role in the development and maintenance of fibrosis after transplantation.

mTOR inhibition induces endothelial progenitor cell death

Immunosuppressants are necessary to prevent graft rejection after solid organ transplantation. However, they are also known to have significant side effects, including endothelial toxicity. Endothelial progenitor cells originate in the bone marrow and are recognized by their angiogenic and endothelial reparative properties. The effects of the immunosuppressants cyclosporine A (CyA), tacrolimus and rapamycin were analyzed on endothelial progenitor-like cells. Rapamycin induced rapid cell death, even at concentrations much lower than those used clinically, in peripheral blood mononuclear cells (PBMC) cultured to favor outgrowth of endothelial progenitors. Cyclosporine A and tacrolimus had no significant effects at clinical concentrations. The effect of rapamycin was specific to endothelial progenitor cells, in particular to the early stages of differentiation, as a lesser effect was observed in late outgrowth endothelial progenitors, mature aortic endothelial cells, and macrophages derived from the same PBMCs. The mechanism of cell death appeared to be apoptosis; however, its induction was probably multifactorial and did not depend on caspase or cathepsin activation. In conclusion, rapamycin induces endothelial progenitor cell death, possibly because it blocks survival signals given by growth factors critically required by these cells.

The effect of reflux and bile acid aspiration on the lung allograft and its surfactant and innate immunity molecules SP-A and SP-D

Gastro-esophageal reflux and related pulmonary bile acid aspiration were prospectively investigated as possible contributors to postlung transplant bronchiolitis obliterans syndrome (BOS). We also studied the impact of aspiration on pulmonary surfactant collectin proteins SP-A and SP-D and on surfactant phospholipids--all important components of innate immunity in the lung. Proximal and distal esophageal 24-h pH testing and broncho-alveolar lavage fluid (BALF) bile acid assays were performed prospectively at 3-month posttransplant in 50 patients. BALF was also assayed for SP-A, SP-D and phospholipids expressed as ratio to total lipids: phosphatidylcholine; dipalmitoylphosphatidylcholine; phosphatidylglycerol (PG); phosphatidylinositol; sphingomyelin (SM) and lysophosphatidylcholine. Actuarial freedom from BOS was assessed. Freedom from BOS was reduced in patients with abnormal (proximal and/or distal) esophageal pH findings or BALF bile acids (Log-rank Mantel-Cox p < 0.05). Abnormal pH findings were observed in 72% (8 of 11) of patients with bile acids detected within the BALF. BALF with high levels of bile acids also had significantly lower SP-A, SP-D, dipalmitoylphosphatidylcholine; PG and higher SM levels (Mann-Whitney, p < 0.05). Duodeno-gastro-esophageal reflux and consequent aspiration is a risk factor for the development of BOS postlung transplant. Bile acid aspiration is associated with impaired lung allograft innate immunity manifest by reduced surfactant collectins and altered phospholipids.

Pre-implantation multiple cytokine mRNA expression analysis of donor lung grafts predicts survival after lung transplantation in humans

While current donor selection with clinical findings is generally effective, the imprecise nature of the assessment forces clinicians to remain on the conservative side. A reliable biological marker would assist donor selection and would improve donor organ utilization. We collected biopsies from 169 donor lungs before implantation. Expression levels of IL-6, IL-8, IL-10, TNF-alpha, IFN-gamma and IL-1beta were measured by quantitative real-time RT-PCR (qRT-PCR). Seventeen cases died within 30 days after transplantation. No donor factor was significantly associated with 30-day mortality. Univariate analysis of the 84 cases for development of the prediction model showed that IL-6, IL-8, TNF-alpha and IL-1beta were risk factors for mortality and IL-10 and IFN-gamma were protective factors. We analyzed the cytokine expression ratios of risk to protective cytokines. A stepwise logistic regression for 30-day mortality demonstrated that a model containing the ratio of IL-6/IL-10 was the most predictive (p = 0.0013). When applied to the remaining 85 cases for validation, the test of model fit was significant (p = 0.039). Using the cytokine ratio, we were able to define three risk groups with striking differences in survival (p = 0.0003). Multi-cytokine analysis of the donor lung graft with qRT-PCR shows significant promise as a strategy to biologically evaluate the donor lung prior to implantation.

Impact of lung transplant operation on bronchiolitis obliterans syndrome in patients with chronic obstructive pulmonary disease

Previous studies suggest that bilateral (BLT) compared with single lung transplantation (SLT) for patients with chronic obstructive pulmonary disease (COPD) results in improved long-term survival. The effect of transplant operation on bronchiolitis obliterans syndrome (BOS) is unknown. A retrospective study of all lung transplant recipients with pre-transplant diagnoses of COPD at the University of Toronto and at Duke University was performed. Data collected were age, gender, date and type of transplant, acute rejection, survival, presence and time of BOS. 221 (bilateral n = 101, single n = 120) patients met our criteria. Patients with BLT were younger (53.0 vs. 55.3 years; p = 0.034), more likely to be male (56.3% vs. 42.4%; p = 0.039) and more likely to be transplanted at the University of Toronto (79.6% vs. 16.1%; p < 0.001). Freedom from BOS was similar at 1 year post-transplant. However, BLT recipients were more commonly free from BOS 3 years (57.4% vs. 50.7%) and 5 years (44.5% vs. 17.9%) post-transplant (p = 0.024). Survival of BLT was better than SLT recipients at 3 and 5 years post-transplant (BLT vs. SLT: 67.5% vs. 61.1% and 60.7% vs. 34.1%, respectively; p = 0.018). Similar trends on survival were observed after development of BOS. BLT results in lower rates of BOS in patients with COPD that are eligible for both SLT and BLT.

Transbronchial administration of adenoviral-mediated interleukin-10 gene to the donor improves function in a pig lung transplant model

Interleukin-10 (IL-10) gene transfection of donor lungs prior to transplantation is an attractive strategy to reduce ischemia-reperfusion induced lung injury. However, experimental data with gene therapy in large animal models of lung transplantation are generally lacking. We have developed a simple clinically applicable technique for adenoviral-mediated gene delivery of human IL-10 to the lung of large animals that provides homogenous gene expression after 12-24 h of transfection. Using this technique of gene delivery, we have studied the dynamics of adenoviral gene delivery to the lung in the setting of lung transplantation. Although there is a persistent inflammatory response to the adenoviral vector, we achieved significant expression of human IL-10 in lung tissue before lung retrieval to obviate the deleterious impact of the adenoviral vector on the donor lung. The administration of adenoviral-mediated human IL-10 to the donor lung reduced ischemia-reperfusion injury and improved graft function after lung transplantation in this pig lung transplantation model. Transfection of adenoviral-mediated human IL-10 to the donor lung prevented the release of inflammatory cytokines such as IL-6 in lung tissue and plasma. We have demonstrated that IL-10 gene therapy has significant potential to prevent or treat the inflammatory response associated with ischemia-reperfusion injury in lung transplantation. In the future, IL-10 gene therapy could also be used for immunomodulation or tolerance induction.

The influence of lung volume reduction surgery on exercise in patients with COPD

Although the influence of lung volume reduction surgery (LVRS) on incremental- and constant-power exercise is important in the evaluation of this procedure for patients with chronic obstructive pulmonary disease (COPD), it is rarely reported even in large randomised controlled trials. This report describes 39 patients with severe COPD ((mean +/- SE) forced expiratory volume in one second 32 +/- 2% pred, functional residual capacity 195 +/- 6% pred) who participated in a randomised controlled trial of LVRS and who completed incremental exercise tests at 6 months as well as endurance tests (constant power of 25 +/- 1 W) at 3, 9 and 12 months. Peak oxygen uptake (V'O2,pk) was similar between the treatment (n = 19) and control groups (n = 20) at baseline. After LVRS, the treatment group had a significantly greater V'O2,pk (mean difference (95% CI) 1.28 (0.07-2.50) mL x kg x min(-1)) and power (13 (6-20) W). The treatment group achieved a significantly greater minute ventilation (7.1 (2.9-11.3) L x min(-1)) with a greater tidal volume (0.16 (0.04-0.28) L). Baseline endurance was similar between groups. After surgery, there were significant between-group differences in endurance time, which were maintained at 12 months (7.3 (3.9-10.8) min). Lung volume reduction surgery is associated with an increase in exercise capacity and endurance, as compared with conventional medical treatment.

Influence of lung volume reduction surgery (LVRS) on health related quality of life in patients with chronic obstructive pulmonary disease

BACKGROUND

The clinical value of LVRS has been questioned in the absence of trials comparing it with pulmonary rehabilitation, the prevailing standard of care in COPD. Patients with heterogeneous emphysema are more likely to benefit from volume reduction than those with homogeneous disease. Disease specific quality of life is a responsive interpretable outcome that enables health professionals to identify the magnitude of the effect of an intervention across several domains.

METHODS

Non-smoking patients aged <75 years with severe COPD (FEV(1) <40% predicted, FEV(1)/FVC <0.7), hyperinflation, and evidence of heterogeneity were randomised to surgical or control groups after pulmonary rehabilitation and monitored at 3 month intervals for 12 months with no crossover between the groups. The primary outcome was disease specific quality of life as measured by the Chronic Respiratory Questionnaire (CRQ). Treatment failure was defined as death or functional decline (fall of 1 unit in any two domains of the CRQ). Secondary outcomes included pulmonary function and exercise capacity.

RESULTS

LVRS resulted in significant between group differences in each domain of the CRQ at 12 months (change of 0.5 represents a small but important difference): dyspnoea 1.9 (95% confidence interval (CI) 1.3 to 2.6; p<0.0001); emotional function 1.5 (95% CI 0.9 to 2.1; p<0.0001); fatigue 2.0 (95% CI 1.4 to 2.6; p<0.0001); mastery 1.8 (95% CI 1.2 to 2.5; p<0.0001). In the control group one of 27 patients died and 16 experienced functional decline over 12 months. In the surgical group four of 28 patients died and three experienced functional decline (hazard ratio = 3.1 (95% CI 1.3 to 7.6; p=0.01). Between group improvements (p<0.05) in lung volumes, flow rates, and exercise were sustained at 12 months (RV -47% predicted (95% CI -71 to -23; p=0.0002); FEV(1) 0.3 l (95% CI 0.1 to 0. 5; p=0.0003); submaximal exercise 7.3 min (95% CI 3.9 to 10.8; p<0.0001); 6 minute walk 66 metres (95% CI 32 to 101; p=0.0002).

CONCLUSIONS

In COPD patients with heterogeneous emphysema, LVRS resulted in important benefits in disease specific quality of life compared with medical management, which were sustained at 12 months after treatment.

Management of lung transplant recipients with bronchogenic carcinoma in the native lung

Experience with lung transplantation for bronchogenic carcinoma is limited. In our experience, 3 of 6 patients died of recurrent carcinoma within 5 to 35 months after transplantation. Hence, we currently do not support lung transplantation for patients with pre-transplant diagnosis of bronchogenic carcinoma, with the exception of bronchioloalveolar carcinoma (BAC) confined to the lung. Patients with BAC should be staged thoroughly with chest and abdominal computerized tomography, brain magnetic resonance imaging, and bone scan repeated every 3 months while on the waiting list, and should undergo mediastinoscopy at the time of transplantation, with a plan for a backup recipient if metastatic lymph nodes are detected. Proposal for lung transplantation for patients with bronchogenic carcinoma, with the exception of BAC, probably should be performed in the setting of a clinical trial developed with input from the lung transplant community.

Large artery stiffness: structural and genetic aspects

1. Large artery stiffness is a principal determinant of pulse pressure and both are related to cardiovascular mortality independently of other major risk factors. A clearer understanding of the structural and genetic processes that contribute to large artery properties may provide novel approaches to therapy. 2. Age, atherosclerosis and gender are three important factors that contribute to large artery stiffening. Each influences the artery elastic matrix and its relationship to medial smooth muscle cells. Genetic and hormonal modulation of the extracellular matrix proteins and their regulators, including matrix metalloproteinases (MMPs), may account for some interindividual differences. 3. In a study of 213 healthy individuals and 105 patients with coronary artery disease (CAD), we examined whether stromelysin-1 (MMP-3) genotype, determined by the 5A/6A promoter polymorphism, influences large artery stiffening. In healthy individuals, the 5A/5A genotype was linked with stiffer large arteries and higher systolic blood pressure compared with other genotypes. 4. Genetic variation in the extracellular matrix protein fibrillin-1, using a pentanucleotide repeat polymorphism, was assessed as a potential determinant of large artery stiffness in patients with CAD. The 2-3 genotype was associated with stiffer large arteries, higher pulse pressure and more severe CAD than other genotypes. 5. Females experience a greater increase in large artery stiffness with age than males, with a time-course suggestive of sex steroid modulation. The mechanisms mediating such gender differences have not been established, but the known regulatory role of sex steroids with respect to MMPs likely contributes. 6. The demonstration that genetic and hormonal modulation of extracellular matrix components and MMPs contributes to age, atherosclerotic and gender-related differences in large artery mechanical properties suggests these proteins may be important targets for therapy.

Women exhibit a greater age-related increase in proximal aortic stiffness than men

BACKGROUND

Large artery mechanical properties are a major determinant of pulse pressure and cardiovascular outcome. Sex differences in these properties may underlie the variation in cardiovascular risk profile between men and women, in relation to age.

OBJECTIVE

To investigate sex differences in the age-related stiffening of large arteries.

DESIGN

Cross-sectional.

METHODS

One hundred and twenty healthy men and women were recruited and divided equally into tertiles by age: young (mean +/- SD, 23 +/- 5 years), middle-age (47 +/- 3 years) and older (62 +/- 7 years). Lipids, mean arterial pressure and heart rate were matched within each tertile. Carotid tonometry and Doppler velocimetry were used to measure indices of large artery stiffness.

RESULTS

There was no sex difference in systemic arterial compliance (SAC) in the young group (mean +/- SEM, 0.61 +/- 0.05 arbitrary compliance units (ACU) in women compared with 0.67 +/- 0.04 ACU in men), but in the older population women had lower SAC than men (0.27 +/- 0.03 ACU compared with 0.57 +/- 0.04 ACU respectively; P < 0.001). Measures independent of aortic geometry (distensibility index and aortic impedance) indicated that stiffness was lower in young women than in men (P < 0.05), but the reverse was true in the older population (P < 0.01). This paralleled the brachial and carotid pulse pressures, which were lower in young (P < 0.01) and higher in older women compared with those in men (P < 0.05). Follicle stimulating hormone concentrations correlated strongly (r values 0.39-0.65) with all indices of central, but not peripheral, arterial function, whereas concentrations of luteinizing hormone, progesterone and oestradiol correlated less strongly.

CONCLUSIONS

In men and women matched for mean pressures, the age-related stiffening of large arteries is more pronounced in women, which is consistent with changes in female hormonal status.

Prostaglandin E1 protects lung transplants from ischemia-reperfusion injury: a shift from pro- to anti-inflammatory cytokines

INTRODUCTION

Prostaglandin E1 (PGE1) has been demonstrated to reduce ischemia-reperfusion (IR) injury following lung transplantation. However, the cytoprotective mechanisms remain largely unknown. The purpose of this study was to determine whether the mechanism through which PGE1 improves IR injury is related to the level of apoptosis or the release of inflammatory cytokines.

METHODS

In a rat single-lung-transplant model, animals were randomly allocated into four groups of five animals each. Group 1 received normal saline (NS) in the preservation solution and during the 2-hr reperfusion period. Group 2 received NS in the preservation solution and PGE1 during the reperfusion period. Group 3 received PGE1 in the preservation solution and NS during the reperfusion period. Group 4 received PGE1 in the preservation solution and during the reperfusion period.

RESULTS

The two groups that received PGE1 during the reperfusion period had a significantly higher partial pressure of oxygen (PaO2), lower wet-dry weight ratio, and lower peak airway pressure at the end of the reperfusion period than did the two groups that received NS. In the two groups that received PGE1 during the reperfusion period, we observed significantly higher levels of interleukin (IL)-10 in the transplanted lung tissue and plasma and significantly lower levels of tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, and IL-12 in lung tissue. The levels of IL-4 and macrophage inflammatory protein-2 (MIP-2) were not significantly different between groups. The number of apoptotic cells and the expression of Bcl-2 were not significantly different between groups.

CONCLUSIONS

PGE1 does not decrease the amount of apoptosis after reperfusion and does not significantly upregulate Bcl-2. We have demonstrated that PGE1 administered during the reperfusion period reduces IR injury and improves lung function through a mechanism that is likely mediated by a shift between pro- and anti-inflammatory cytokine release.

Carotid pressure is a better predictor of coronary artery disease severity than brachial pressure

The mechanisms relating pulse pressure to cardiovascular outcome may include surrogacy for coronary disease severity. Although pulse pressure is typically measured at the brachial artery, central pulse pressure and its principal determinant, large-artery stiffness, may relate more closely to disease severity. This study aimed to determine the relationships between large-artery stiffness and carotid and brachial blood pressures and coronary artery disease severity. One hundred fourteen male patients with coronary artery disease (age 60+/-8 years, mean+/-SD) and 57 age-matched healthy male controls (age 59+/-9 years) were recruited. Patients were classified into 2 groups based on the magnitude of their maximum coronary stenosis: moderate (50% to 89%) and severe (>/=90%). Large-artery stiffness was assessed as systemic arterial compliance and carotid-femoral pulse wave velocity. Mean pressure was not different between the 3 groups. Systemic compliance and carotid pulse pressure were significantly different between all 3 groups, with compliance lowest and pressure highest in the severe group (P<0.05). Pulse wave velocity was higher in patients with severe stenosis than in those with moderate stenosis (P<0.01) and those in the control group (P<0.001). Brachial pulse pressure was higher in patients than in controls (P<0.05), but there was no difference between the 2 disease groups. In separate multivariate analyses, carotid pressures and systemic arterial compliance were determinants of coronary artery disease severity, independent of age, smoking status, body mass index, mean arterial pressure, heart rate, cholesterol levels (total, LDL, and HDL), triglycerides, and beta-antagonist and lipid-lowering therapy (P<0.001), whereas brachial pressures and pulse wave velocity were not. In conclusion, central blood pressures and systemic arterial compliance are more sensitive markers of coronary artery disease severity than brachial pressures.

Aerobic exercise training does not modify large-artery compliance in isolated systolic hypertension

The present study characterized large-artery properties in patients with isolated systolic hypertension (ISH) and determined the efficacy of exercise training in modifying these properties. Twenty patients (10 male and 10 female) with stage I ISH and 20 age- and gender-matched control subjects were recruited, and large-artery properties were assessed noninvasively. Ten ISH patients (5 male and 5 female) were enrolled in a randomized crossover study comparing 8 weeks of moderate intensity cycling with 8 weeks of sedentary activity. Brachial and carotid systolic, diastolic, mean, and pulse pressures were higher in the ISH group than in the control group. Systemic arterial compliance (0.43+/-0.04 versus 0.29+/-0.02 arbitrary compliance units for the control versus ISH groups, respectively; P=0.01) was lower, and carotid-to-femoral pulse-wave velocity (9.67+/-0.36 versus 11.43+/-0.51 m. s(-1) for the control versus ISH groups, respectively; P=0.007), input impedance (2.39+/-0.19 versus 3.27+/-0.34 mm Hg. s. cm(-1) for the control versus ISH groups, respectively; P=0.04), and characteristic impedance (1.67+/-0.17 versus 2.34+/-0.27 mm Hg. s. cm(-1) for the control versus ISH groups, respectively; P=0.05) were higher in the ISH group than in the control group. Training increased maximal oxygen consumption by 13+/-5% (P=0.04) and maximum workload by 8+/-4% (P=0.05); however, there was no effect on arterial mechanical properties, blood lipids, or left ventricular mass or function. These results suggest that the large-artery stiffening associated with ISH is resistant to modification through short-term aerobic training.

Signaling functions of L-selectin in neutrophils: alterations in the cytoskeleton and colocalization with CD18

Ligation and clustering of L-selectin by Ab ("cross-linking") or physiologic ligands results in activation of diverse responses that favor enhanced microvascular sequestration and emigration of neutrophils. The earliest responses include a rise in intracellular calcium, enhanced tyrosine phosphorylation, and activation of extracellular signal-regulated kinases. Additionally, cross-linking of L-selectin induces sustained shape change and activation of beta2 integrins, leading to neutrophil arrest under conditions of shear flow. In this report, we examined several possible mechanisms whereby transmembrane signals from L-selectin might contribute to an increase in the microvascular retention of neutrophils and enhanced efficiency of emigration. In human peripheral blood neutrophils, cross-linking of L-selectin induced alterations in cellular biophysical properties, including a decrease in cell deformability associated with F-actin assembly and redistribution, as well as enhanced adhesion of microspheres bound to beta2 integrins. L-selectin and the beta2 integrin became spatially colocalized as determined by confocal immunofluorescence microscopy and fluorescence resonance energy transfer. We conclude that intracellular signals from L-selectin may enhance the microvascular sequestration of neutrophils at sites of inflammation through a combination of cytoskeletal alterations leading to cell stiffening and an increase in adhesiveness mediated through alterations in beta2 integrins.

Muscular strength training is associated with low arterial compliance and high pulse pressure

Aerobic exercise training increases arterial compliance and reduces systolic blood pressure, but the effects of muscular strength training on arterial mechanical properties are unknown. We compared blood pressure, whole body arterial compliance, aortic impedance, aortic stiffness (measured by beta-index and carotid pulse pressure divided by normalized systolic expansion [Ep]), pulse wave velocity, and left ventricular parameters in 19 muscular strength-trained athletes (mean+/-SD age, 26+/-4 years) and 19 sedentary controls (26+/-5 years). Subjects were healthy, non-steroid-using, nonsmoking males, and athletes had been engaged in a strength-training program with no aerobic component for a minimum of 12 months. There was no difference in maximum oxygen consumption between groups, but handgrip strength (mean+/-SEM, 44+/-2 versus 56+/-2 kg; P<0.01) and left ventricular mass (168+/-8 versus 190+/-8 g; P<0.05) were greater in athletes. Arterial stiffness was higher in athletes, as evidenced by lower whole body arterial compliance (0.40+/-0.04 versus 0.54+/-0.04 arbitrary compliance units; P=0.01), higher aortic characteristic impedance (1.55+/-0.13 versus 1.18+/-0.08 mm Hg. s. cm-1; P<0.05), beta-index (4.6+/-0.2 versus 3.8+/-0.4; P<0. 05), and ln Ep (10.86+/-0.06 versus 10.60+/-0.08; P<0.01). Femoral-dorsalis pedis pulse wave velocity was also higher in the athletes, but carotid-femoral pulse wave velocity was not different. Furthermore, both carotid (56+/-3 versus 44+/-2 mm Hg; P<0.001) and brachial (60+/-3 versus 50+/-2 mm Hg; P<0.01) pulse pressures were higher in the athletes, but mean arterial pressure and resting heart rate did not differ between groups. These data indicate that both the proximal aorta and the leg arteries are stiffer in strength-trained individuals and contribute to a higher cardiac afterload.

Withdrawal of hormonal therapy for 4 weeks decreases arterial compliance in postmenopausal women

BACKGROUND

We demonstrated in a previous cross-sectional study that arterial compliance is elevated in postmenopausal women taking estrogen-containing hormonal therapy, which may partially account for the reduction in cardiovascular risk observed.

OBJECTIVE

To investigate the effects of withdrawal and recommencement of hormonal therapy, each for 4 weeks, on arterial compliance.

METHODS

Seventeen postmenopausal women [aged 56 +/- 4 years (mean +/- SD)] taking long-term hormonal therapy (+HT group) were studied at baseline, 4 weeks after withdrawal of hormonal therapy and again 4 weeks after recommencement. Systemic arterial compliance (SAC), pulse wave velocity (PWV) in the aorto-femoral and femoral-dorsalis pedis regions, and hemodynamic variables were measured at baseline, and at the end of each study intervention. As a time-control, seventeen postmenopausal women (aged 63 +/- 7 years) not taking hormonal therapy (-HT group) were also investigated.

RESULTS

SAC significantly decreased from 0.47 +/- 0.06 to 0.40 +/- 0.05 arbitrary compliance units (mean +/- SEM; P < 0.05) after 4 weeks withdrawal from hormonal therapy. PWV in the femoral-dorsalis pedis region was elevated significantly by the withdrawal of hormonal therapy (8.4 +/- 0.4 to 9.4 +/- 0.5 m/s; P < 0.05), but PWV in the aortofemoral region did not change. After therapy had been recommenced for 4 weeks, SAC and PWV in the femoral-dorsalis pedis region were restored to baseline values. The -HT group showed no difference in SAC or PWV, and mean arterial pressure did not change in either group throughout the study period.

CONCLUSION

These data suggest that hormonal modulation of distal arterial vascular tone may account for short-term changes in arterial compliance associated with estrogen-containing hormonal therapy.

Lung transplantation for chronic obstructive pulmonary disease

Emphysema is the fifth leading cause of death in North America. It is now the most common indication for lung transplantation worldwide. Since 1986, evolution in operative techniques and improvements in organ preservation and post-operative immunosuppression have resulted in impressive long-term survival results. Significant problems remain in terms of inadequate organ supply and chronic rejection; many more candidates could be transplanted if not for these two major limitations. However, other options are now available for the surgical management of patients with end-stage emphysema. The decision making surrounding transplantation for emphysema has been radically altered by the advent of lung volume reduction surgery. This review will highlight new data that pertains to recipient and donor selection, choice of transplant procedure, either single or bilateral, and the role of lung volume reduction surgery. At the University of Toronto we generally favour bilateral lung transplantation for superior functional results and possibly enhanced long-term survival. We have been particularly interested in combining lung transplantation with synchronous lung volume reduction surgery and the rationale and results of this procedure are reviewed.

Major histocompatibility complex expression and lung ischemia-reperfusion in rats

BACKGROUND

Clinical studies in kidney and liver transplantation have suggested that poor early function is associated with increased graft loss due to rejection. Ischemia-reperfusion injury may contribute to rejection by enhancing graft immunogenicity.

METHODS

A rat model of unilateral in situ pulmonary ischemia-reperfusion was used to examine class II major histocompatibility complex (MHC) antigen expression. The effects of deflation during ischemia (which augments subsequent injury) as well as concurrent allostimulation were also examined. Major histocompatibility complex expression was examined 9 days after ischemia using the binding of radiolabeled anti-class II antibody and immunohistochemistry.

RESULTS

Four hours of ischemia in full inflation or 2 hours of atelectatic ischemia both led to severe lung injury. Ischemia-reperfusion injury led to greater MHC expression in the ischemic lung compared with the nonischemic side. Allostimulation with mononuclear cells did not increase MHC expression in the nonischemic lung but did enhance the increase found in the ischemic lung. This was not due to a graft-versus-host response because allostimulation with F1 cells also led to a significant increase.

CONCLUSIONS

Severe ischemic lung injury leads to significant increases in MHC expression, detectable after 9 days of reperfusion. Deflation during ischemia, which augments lung injury, also augments increased MHC expression. Concurrent allostimulation with foreign mononuclear cells appears to potentiate increased MHC expression after ischemia. Increases in graft MHC expression may enhance immunogenicity and increase the rejection response.

Validation of a telemetry system for long-term measurement of blood pressure

We have used an implanted telemetry system to continuously monitor blood pressure (BP) in three dogs for durations ranging from 28 to 75 wk after implantation. Measurements of BP obtained by telemetry were compared every 3-12 wk, with measurements of BP recorded with a manometer-tipped catheter that was inserted into a femoral artery. Over a wide range of both physiological and pharmacologically manipulated pressures (40-200 mmHg), the values of BP obtained by the two methods were highly correlated (all r > 0.966; all P < or = 0.0001). However, the mean differences between the values obtained by the two systems were different from zero (range +29.6 to -1.5 mmHg; P < or = 0.0001), indicating an offset in the BP values recorded from the implanted system. Furthermore, this offset was dependent on the absolute level of the BP. The findings indicate that, for a period of at least 28 wk and up to 75 wk after implantation, the telemetry system accurately measures acute changes in BP and can reliably measure absolute BP provided that the system is properly validated.

Intracellular pH regulation during spreading of human neutrophils

The regulation of the intracelluar pH (pHi) during spreading of human neutrophils was studied by a combination of fluorescence imaging and video microscopy. Spreading on adhesive substrates caused a rapid and sustained cytosolic alkalinization. This pHi increase was prevented by the omission of external Na+, suggesting that it results from the activation of Na+/H+ exchange. Spreading-induced alkalinization was also precluded by the compound HOE 694 at concentrations that selectively block the NHE-1 isoform of the Na+H+ antiporter. Inhibition of Na+/H+ exchange by either procedure unmasked a sizable cytosolic acidification upon spreading, indicative of intracellular acid production. The excess acid generation was caused, at least in part, by the activation of the respiratory burst, since the acidification closely correlated with superoxide production, measured in single spreading neutrophils with dihydrorhodamine-123, and little acid production was observed in the presence of diphenylene iodonium, a blocker of the NADPH oxidase. Moreover, neutrophils from chronic granulomatous disease patients, which do not produce superoxide, failed to acidify. Comparable pHi changes were observed when beta 2 integrins were selectively activated during spreading on surfaces coated with anti-CD18 antibodies. When integrin engagement was precluded by pretreatment with soluble anti-CD18 antibody, the pHi changes associated with spreading on fibrinogen were markedly reduced. Inhibition of microfilament assembly with cytochalasin D precluded spreading and concomitantly abolished superoxide production and the associated pHi changes, indicating that cytoskeletal reorganization and/or an increase in the number of adherence receptors engaged are required for the responses. Neutrophils spread normally when the oxidase was blocked or when pHi was clamped near physiological values with nigericin. Spreading, however, was strongly inhibited when pHi was clamped at acidic values. Our results indicate that neutrophils release superoxide upon spreading, generating a burst of intracellular acid production. The concomitant activation of the Na+/H+ antiport not only prevents the deleterious effects of the acid released by the NADPH oxidase, but induces a net cytosolic alkalinization. Since several functions of neutrophils are inhibited at an acidic pHi, the coordinated activation of pHi regulatory mechanisms along with the oxidase is essential for sustained microbicidal activity.

Na+/H+ exchange activity during phagocytosis in human neutrophils: role of Fcgamma receptors and tyrosine kinases

In neutrophils, binding and phagocytosis facilitate subsequent intracellular killing of microorganisms. Activity of Na+/H+ exchangers (NHEs) participates in these events, especially in regulation of intracellular pH (pHi) by compensating for the H+ load generated by the respiratory burst. Despite the importance of these functions, comparatively little is known regarding the nature and regulation of NHE(s) in neutrophils. The purpose of this study was to identify which NHE(s) are expressed in neutrophils and to elucidate the mechanisms regulating their activity during phagocytosis. Exposure of cells to the phagocytic stimulus opsonized zymosan (OpZ) induced a transient cytosolic acidification followed by a prolonged alkalinization. The latter was inhibited in Na+-free medium and by amiloride analogues and therefore was due to activation of Na+/H+ exchange. Reverse transcriptase PCR and cDNA sequencing demonstrated that mRNA for the NHE-1 but not for NHE-2, 3, or 4 isoforms of the exchanger was expressed. Immunoblotting of purified plasma membranes with isoform-specific antibodies confirmed the presence of NHE-1 protein in neutrophils. Since phagocytosis involves Fcgamma (FcgammaR) and complement receptors such as CR3 (a beta2 integrin) which are linked to pathways involving alterations in intracellular [Ca2+]i and tyrosine phosphorylation, we studied these pathways in relation to activation of NHE-1. Cross-linking of surface bound antibodies (mAb) directed against FcgammaRs (FcgammaRII > FcgammaRIII) but not beta2 integrins induced an amiloride-sensitive cytosolic alkalinization. However, anti-beta2 integrin mAb diminished OpZ-induced alkalinization suggesting that NHE-1 activation involved cooperation between integrins and FcgammaRs. The tyrosine kinase inhibitors genistein and herbimycin blocked cytosolic alkalinization after OpZ or FcgammaR cross-linking suggesting that tyrosine phosphorylation was involved in NHE-I activation. An increase in [Ca2+]i was not required for NHE-1 activation because neither removal of extracellular Ca2+ nor buffering of changes in [Ca2+]i inhibited alkalinization after OpZ or Fc-gammaR cross-linking. In summary, Fc-gammaRs and beta2 integrins cooperate in activation of NHE-1 in neutrophils during phagocytosis by a signaling pathway involving tyrosine phosphorylation.

Intracellular signaling in neutrophil priming and activation

In order for neutrophils to function effectively in host defense, they have evolved specific attributes including the ability to migrate to the site of inflammation and release an array of toxic products including proteolytic enzymes, reactive oxygen species, and cationic proteins. While these compounds are intended for killing invading pathogens, if released inappropriately, they may also contribute to tissue damage. Such inflammatory tissue injury may be important in the pathogenesis of a variety of clinical disorders including arthritis, ischemia-reperfusion tissue injury, the systemic inflammatory response syndrome (SIRS), and the acute respiratory distress syndrome (ARDS). Despite the importance of neutrophil function in host defense and dysfunction in disease states, much remains unknown about the intracellular signaling pathways regulating neutrophil activity. This review will focus on the signaling molecules regulating leukocyte 'effector' functions including receptors, GTP-binding proteins, phospholipases, polyphosphoinositide metabolism, and protein kinases and phosphatases.

Current techniques in cell and molecular biology

Recent advances in the field of molecular biology have revolutionized our understanding of the functioning of living organisms and facilitated the development of robust tools for both diagnosis and treatment of diseases. With particular reference to the field of critical care medicine, development of molecular biology techniques have aided in the following: (1) rapid and highly specific detection of pathogenic infectious agents (eg, Mycobacterium tuberculosis, Pneumocystis carinii, cytomegalovirus, Legionella); (2) development of assays for measurement of circulating cytokines such as tumor necrosis factor (TNF) and interleukin (IL)-1 that has helped our understanding of the pathogenesis of the sepsis syndrome; (3) administration of antibodies or soluble receptors to attempt to prevent untoward effects of cytokines such as TNF or IL-1; and (4) the administration of recombinant deoxyribonucleic acid (DNA) or proteins to patients in an attempt to alter the course of a disease such as antioxidant enzymes (superoxide dismutase). The rapidity of progress in this field has been staggering, which necessitates frequent updating of our knowledge for clinicians to put these molecular tools to their best use. This brief review attempts to explain the basic principles of commonly used techniques in molecular biology including recombinant DNA, polymerase chain reaction, DNA libraries, gene therapy, and protein biochemistry in a manner that is understandable to those without an in-depth knowledge of the field.

Signaling functions of L-selectin. Enhancement of tyrosine phosphorylation and activation of MAP kinase

L-selectin is a leukocyte cell surface glycoprotein involved in carbohydrate-specific ligand binding which mediates rolling of leukocytes along endothelial surfaces. In addition to its role in adhesion, an intracellular signaling role for L-selectin has recently been recognized. In particular, cross-linking L-selectin leads to increased cytosolic Ca2+ levels and potentiation of the oxidative burst. As several cell surface glycoproteins have been shown to be linked to tyrosine kinases, we examined the hypothesis that L-selectin may be linked to pathways involving tyrosine phosphorylation in human neutrophils. Ligation of L-selectin by three different antibodies recognizing separate epitopes led to increased tyrosine phosphorylation of several cellular proteins as judged by anti-phosphotyrosine immunoblots of whole cell lysates with prominent bands at 40-42, 55-60, 70-72, and 105-120 kDa. The 42-kDa band comigrated with mitogen-activated protein (MAP) kinase as determined by immunoblotting with anti-MAP kinase antibody. This effect was specific for L-selectin, because antibodies against CD18, CD45, and CD10 did not increase tyrosine phosphorylation. Phosphorylation was not due to Fc binding, since F(ab')2 fragments of the anti-L-selectin antibodies were similarly effective, and the response was unaffected by Fc receptor blockade. Cross-linking of L-selectin was not required for enhanced tyrosine phosphorylation, because monovalent Fab fragments also increased tyrosine phosphorylation. The response to L-selectin antibodies was not inhibited by cytochalasin, suggesting that reorganization of the actin cytoskeleton was not required for this response. Sulfatides, sulfated glycolipids which may be natural ligands for L-selectin, also induced a rapid, dose-dependent increase in tyrosine phosphorylation. In addition, sulfatides, but not control glycolipids, resulted in enhanced tyrosine phosphorylation of MAP kinase. Both sulfatides and anti-L-selectin antibodies increased kinase activity of MAP kinase as determined by gel renaturation assay. The tyrosine kinase inhibitor, genistein, blocked the transient increase in intracellular Ca2+ and the oxidative burst induced by sulfatides, suggesting that this tyrosine phosphorylation is functionally important. We conclude that L-selectin is able to transmit intracellular signals, including increased tyrosine phosphorylation and activation of MAP kinase in neutrophils. We speculate that these events may contribute to the activation of neutrophils during adhesion.

Puromycin aminonucleoside inhibits mesangial cell-induced contraction of collagen gels by stimulating production of reactive oxygen species

Glomerular epithelial cell injury is thought to be the primary reason for the development of proteinuria in puromycin aminonucleoside nephrosis (PAN), the rat model of nephrotic syndrome. By comparison mesangial cells are considered resistant to the effects of puromycin. The purpose of the present study was to investigate whether puromycin in non cytotoxic concentrations caused mesangial cell dysfunction, with particular reference to cell-extracellular matrix interactions. Mesangial cells, when embedded in collagen gels, contact after exposure to minimal essential medium (MEM) containing fetal bovine serum (FBS). This contractility, measured by determining changes in area of the collagen gel, is inhibited by puromycin in a dose dependent manner from 2.5 micrograms/ml to 160 micrograms/ml. At these concentrations there is no alteration of cell viability as measured by the tetrazolium salt (MTT) method and trypan blue exclusion. Immunocytochemistry with rhodamine phalloidin reveals that actin filaments are not disrupted. The antioxidants, superoxide dismutase (SOD) and catalase as well as diphenylene iodonium (DPI), a flavoprotein inhibitor, not only counteracted the effect of puromycin on gel contraction, but also enhanced gel contraction when added to mesangial cells on their own. Aminotriazole, an inhibitor of endogenous catalase, inhibited mesangial cell-induced gel contraction in a dose dependent manner (5 mM to 40 mM), and this effect was completely reversed by addition of catalase. Mesangial cells preloaded with dihydrorhodamine and exposed to puromycin (5 micrograms/ml to 160 micrograms/ml) exhibited a dose dependent increase in rhodamine 123 fluorescence, indicating production of reactive oxygen species (ROS). This effect was blocked by the addition of DPI.(ABSTRACT TRUNCATED AT 250 WORDS)

In situ ischemia and hypoxia enhance alveolar macrophage tissue factor expression

Alveolar and interstitial fibrin deposition is a prominent pathologic feature in many acute lung injury syndromes. Previous studies have suggested that ischemic lung preservation has a stimulatory effect on donor alveolar macrophages (Mphis) during transplantation. An animal model of lung preservation was developed to examine the hypothesis that ischemia enhances Mphi procoagulant activity (PCA) as a potential mechanism contributing to lung reperfusion injury. Histologic examination of ischemic lungs reperfused ex vivo revealed evidence of alveolar fibrin deposition. Mphis lavaged from lungs stored for at least 8 h at 21 degrees C exhibited increased PCA. The use of factor-deficient human plasma characterized this Mphi procoagulant as tissue factor (TF). Since increased PCA correlated with decreased airspace pO2 at the end of preservation, the effect of various O2 concentrations on PCA induction in vivo and in vitro was examined. Lung inflation during ischemia with decreasing O2 concentrations confirmed that hypoxia was associated with a rise in Mphi PCA in situ. However, in vitro exposure of Mphis to hypoxia did not increase Mphi PCA, suggesting that hypoxia alone was not responsible for induction of this procoagulant effect. Northern blot analysis demonstrated an increase in TF mRNA levels from in situ but not in vitro Mphis, thereby confirming transcriptional TF induction in this group. In addition, enhanced PCA was observed when Mphis were suspended in the bronchoalveolar lavage supernatant from the ischemic lungs stored at 21 degrees C. This suggests that in situ lung ischemia and hypoxia may produce soluble factors that either directly or indirectly stimulate Mphi TF expression. These factors may contribute to Mphi-mediated ischemic lung injury.

Antimicrobial prophylaxis in surgery. Committee on Antimicrobial Agents, Canadian Infectious Disease Society

OBJECTIVE

To provide guidelines for antimicrobial prophylaxis on the basis of the type of surgical procedure.

OPTIONS

Standard drug regimens for prophylaxis of infection in a variety of surgical procedures were considered, including a first-generation cephalosporin; an aminoglycoside in combination with metronidazole, clindamycin or erythromycin; a second-generation cephalosporin; and trimethoprim-sulfamethoxazole.

OUTCOMES

In order of importance: efficacy, side effects and cost.

EVIDENCE

A MEDLINE search of articles published between January 1980 and December 1991. For clinical trial data, greatest emphasis was placed on randomized, double-blind studies using appropriate controls.

VALUES

The Committee on Antimicrobial Agents of the Canadian Infectious Disease Society (CIDS) and two recognized experts (T.K.W. and O.D.R.) recommended antimicrobial regimens suitable for prophylaxis of infections in surgery. Whenever possible, recommendations were based on data from randomized controlled trials.

BENEFITS, HARMS AND COSTS

Implementation of the guidelines is expected to reduce the incidence of postoperative infections, the inappropriate use of antibiotics and costs to hospitals.

RECOMMENDATIONS

Antibiotic prophylaxis is recommended for operations with a high risk of postoperative wound infection or with a low risk of infection but significant consequences if infection occurs. These operations include clean-contaminated procedures and certain clean procedures. Drugs should be administered intravenously immediately before the operation. In colorectal operations oral administration also appears to be effective. A single dose is sufficient for most procedures. The regimen chosen depends on the pathogens usually associated with wound infection in a given operation, the serum half-life of the drugs, the antimicrobial susceptibility patterns in the local hospital and the cost of the drugs.

VALIDATION

The guidelines were compared with others in standard textbooks of surgery and peer-reviewed articles. The guidelines were prepared and revised by the Committee on Antimicrobial Agents of the CIDS. They were then reviewed and revised further by the Council of the CIDS.

SPONSOR

The CIDS was solely responsible for developing, funding and endorsing these guidelines.

The effect of heat shock on immediate post-preservation lung function

Exposure of animals to transient hyperthermia causes the induction of highly conserved proteins, heat shock proteins (HSPs), which are thought to by cytoprotective against a variety of injuries, including ischemia. We tested the hypothesis that heating donor animals prior to harvest would improve pulmonary preservation. Anaesthetized New Zealand White rabbits underwent radiant heating to 42.5-43.5 degrees C (rectal) 8 h prior to harvest of the lungs. The lungs were harvested without flush and stored for 18 h at 4 degrees C. The left lung were perfused ex vivo with fresh blood for 10 min. Blood gases, pulmonary artery (Ppa) and airway (P(aw) pressures, and wet/dry ratios (W/D) were measured. Control animals were treated identically except without heating. All heated animals had HSP72 at lung harvest and 18 h later, whereas no control had detectable levels of HSP72 at either time. In Experiment 1 (n = 12, VT 20 ml, F1O2 0.21, 30 bpm, PEEP 0.5 cm H2O), PO2 in the heated group was 57.6 +/- 7.3 mmHg (mean +/- SEM) vs. 51.6 +/- 5.7 in the controls (NS). In Experiment 2 (n = 8, VT 15 ml, F1O2 0.21, 35 bpm, PEEP 2 cm H2O), PO2 of the heated group was 63.5 +/- 6.5 vs. 83.1 +/- 9.5 in the controls (NS). Ppa after 10 min was not significantly different in the heated group in Experiment 1 (16.7 +/- 0.9 mmHg vs. 24.2 +/- 3.7 in controls) or in Experiment 2 (19.5 +/- 1.8 vs. 11.3 +/- 2.9 in controls). Wet/dry ratios were not different in either Experiment 1 (6.4 +/- 0.4 vs. 5.8 +/- 0.2 in controls) or Experiment 2 (5.0 +/- 0.2 vs. 5.0 +/- 0.5).(ABSTRACT TRUNCATED AT 250 WORDS)

A short course of FK506 can induce limited donor-specific graft acceptance

To examine the hypothesis that a short course of FK506 would induce permanent graft acceptance after lung transplantation, left lung allotransplantation was performed in 14 mongrel dogs. In group 1 (control; n = 3), no immunosuppressive agent was given. In group 2 (n = 7), FK506 (1.2 mg/kg intramuscularly) was given on posttransplantation days 0, 1, and 2. In group 3 (n = 4), FK506 was given at the same dose on posttransplantation days 0, 1, and 2 as well as on days 29 and 30. Allograft function was evaluated by temporarily occluding the right pulmonary artery. A mixed lymphocyte reaction study was performed preoperatively and monthly thereafter. Control lungs were all rejected within 8 days. Group 2 dogs showed improved survival, with a median survival of 49.5 days. One dog in group 2 lived more than 400 days after transplantation. The mixed lymphocyte reaction data suggests that some donor-specific unresponsiveness occurs, which lasts for only a limited time. Supplemental doses of FK506 did not significantly improve survival (median, 74 days). The whole blood level of FK506 was 17.7 +/- 3.98 ng/mL on day 15; however, on day 29 the FK506 level was almost undetectable. We conclude that a 3-day course of 1.2 mg/kg of FK506 can induce donor-specific graft acceptance, but this acceptance is not permanent.

Potentiation of the oxidative burst of human neutrophils. A signaling role for L-selectin

Production of reactive oxygen intermediates (ROI) by the NADPH oxidase of neutrophils is a major mechanism of bacterial killing and, in pathologic circumstances, tissue damage. Integrins and selectins participate in neutrophil adhesion but may also play a role in intracellular signaling. The role of L-selectin in ROI production and Ca2+ signaling in suspended neutrophils was examined using the DREG series of anti-L-selectin antibodies. NADPH oxidase activation was assessed in three ways: H2O2 production using either scopoletin or dihydrorhodamine and O2- production using cytochrome c. Alterations in [Ca2+]i were measured using Fura 2-AM and fluorescence spectrophotometry. Cross-linking of L-selectin with DREG and 2 degrees antibody did not trigger production of H2O2 by itself but significantly enhanced the subsequent response to two soluble activating agents; the formyl peptide formyl-Met-Leu-Phe (fMLP) and tumor necrosis factor (TNF). Potentiation of the oxidative burst was observed using F(ab')2 fragments but not with irrelevant antibodies and was observed whether 2 degrees antibody was added before or after fMLP. Cross-linking of L-selectin also triggered a rise in [Ca2+]i, due, in part, to release from intracellular stores. The intracellular Ca2+ chelator BAPTA blocked both the rise in [Ca2+]i and the potentiation of the oxidative burst in response to fMLP or TNF. We conclude that cross-linking of L-selectin induces intracellular signals, including release of Ca2+, which may contribute to potentiation of the oxidative burst.

Effect of methylprednisolone on angiogenesis in syngeneic rat tracheal grafts

Airway anastomotic complications remain a cause of morbidity after clinical lung transplantation. The use of corticosteroid therapy to control pulmonary rejection has raised concern over delayed airway healing. We therefore investigated the hypothesis that the effects of methylprednisolone (MP) impair the revascularization and epithelial regeneration of heterotopic syngeneic tracheal isografts. Lewis rat tracheal segments were wrapped in omentum and implanted in the abdomen of recipient rats. All recipients received cyclosporin A (CsA) (5 mg.kg-1.day-1) and were randomly allocated into three groups of 12 rats each according to the daily MP dose: group II, no MP; group III, 1 mg.kg-1.day-1; and group IV, 2 mg.kg-1.day-1. In each group, 6 animals were sacrificed after 7 and 14 days. Normal, untreated rats served as controls (group I). Epithelial regeneration was assessed histologically by a blinded subjective scoring system and by measurement of epithelial thickness. Tracheal revascularization was quantitated in terms of the number of blood vessels per square millimeter of tracheal wall and the vessel area was quantitated in terms of the percentage of the tracheal wall area. In animals treated with MP and CsA, the trachea exhibited significantly better regeneration after 14 days than it did in animals treated only with CsA. Epithelial regeneration was improved between 7 and 14 days in the groups treated with MP (group III, p = 0.01; group IV, p = 0.04). The epithelial thickness for all three study groups was significantly greater than that in the control group and returned toward normal after 14 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional and biochemical assessment of postpreservation lung viability in a rat model

We examined the relationship between DNA synthesis and postpreservation lung hemodynamics and gas exchange. Adult male Wistar rats (n = 168) were randomly allocated into seven groups (n = 24) according to the pulmonary vascular flush used [EuroCollins (EC), saline, or no flush] and to the temperature of flush and storage (4, 21, or 37 degrees C). In each group, lungs were stored for four different time periods (0-24 h). After storage, incorporation of [3H]-thymidine into DNA was measured in the right lung, and in 72 rats the left lung was reperfused for 1 h with venous blood in an ex vivo paracorporeal rat lung system. Autoradiography of EC lungs revealed that alveolar macrophages and epithelial cells were the two major cell types synthesizing DNA during ischemia. Gas exchange after preservation with EC was universally poor. In unflushed and saline-flushed lungs, a critical threshold for viability was detected beyond which DNA synthesis and lung effluent PO2 decreased more rapidly at higher storage temperatures. A positive correlation was found between the final lung effluent PO2 and [3H]thymidine uptake (R2 = 0.62; P < 0.0001). In this model, deoxyribonucleic acid synthesis was a good index of postpreservation hemodynamics and gas exchange function.