In stable lung transplant recipients, exhaled nitric oxide levels positively correlate with airway neutrophilia and bronchial epithelial iNOS

Effect of positive perioperative donor and recipient respiratory bacterial cultures on early post-transplant outcomes in lung transplant recipients

BACKGROUND

It is standard practice to administer prophylactic antibiotics post lung transplantation. However, no studies have evaluated the impact of culture positivity. The purpose of this study was to evaluate early post-transplant outcomes of culture-positive and culture-negative lung transplant (LT) recipients and the appropriateness of the empiric regimens used.

METHODS

Adult patients who received an LT at Emory University Hospital between January 1, 2010 and August 31, 2015 were reviewed and stratified into three groups: (i) culture-positive appropriate empiric treatment, (ii) culture-positive inappropriate empiric treatment, and (iii) culture-negative. Antibiotics were defined as appropriate if bacteria were sensitive to the empiric regimen. The primary endpoint was 30-day mortality. Secondary endpoints included hospital length of stay (LOS), intensive care unit (ICU) LOS, percent neutrophil count in a bronchoalveolar lavage (BAL) sample, presence of airway ischemia, and appropriateness of the empiric antibiotic regimen.

RESULTS

Nine, zero, and four patients died within 30 days in the culture-positive appropriate (n = 113), culture-positive inappropriate (n = 5), and culture-negative groups (n = 29) (P = .564) respectively. The median hospital LOS was 19, 16, and 15 days respectively. Median ICU LOS was 6, 5, and 7 respectively. The respective percent neutrophil counts in the BAL fluid were 79, 83, and 65. The presence of airway ischemia was only documented in eight patients, all in the culture-positive appropriate group.

CONCLUSION

We did not identify an association between antibiotic appropriateness and 30-day mortality, hospital LOS, or ICU LOS in post-LT recipients.

Oxidative stress and inflammation are differentially affected by atorvastatin, pravastatin, rosuvastatin, and simvastatin on lungs from mice exposed to cigarette smoke

Our aim was to investigate the effects of four different statins on acute lung inflammation induced by cigarette smoke (CS). C57BL/6 male mice were divided into a control group (sham-smoked) and mice exposed to CS from 12 cigarettes/day for 5 days. Mice exposed to CS were grouped and treated with vehicle (i.p.), atorvastatin (10 mg/kg), pravastatin (10 mg/kg), rosuvastatin (5 mg/kg), or simvastatin (20 mg/kg). Treatment with statins differentially improved the pulmonary response when compared to the CS group. Atorvastatin and pravastatin demonstrated slightly effects on inflammation and oxidative stress. Rosuvastatin demonstrated the best anti-inflammatory effect, whereas simvastatin demonstrated the best antioxidant response.

Serial monitoring of exhaled nitric oxide in lung transplant recipients

BACKGROUND

Exhaled nitric oxide (FeNO), a marker of airway inflammation, is often elevated in lung transplant recipients (LTxRs) with acute rejection or infection. Isolated measurements in the setting of bronchiolitis obliterans syndrome have been variable. We sought to assess the utility of serial FeNO in predicting chronic allograft dysfunction or the presence of acute rejection or infection.

METHODS

Eighty-six LTxRs underwent 325 serial FeNO measurements at an expiratory flow rate of 50 ml/s. The change in FeNO (ΔFeNO) between two measurements obtained during a stable state (ΔFeNO-SS) was compared with ΔFeNO, where the first measurement was taken during a stable state and the second during an unstable state (defined as a subsequent decline in FEV1 > 10% over 3 months [ΔFeNO-SU]) or an acute complication (acute rejection, lymphocytic bronchiolitis or acute infection [ΔFeNO-SAC]). The median follow-up time after the baseline FeNO was 10 (range 3 to 25) months.

RESULTS

ΔFeNO-SS in 117 FeNO pairs was similar to ΔFeNO-SU in 26 pairs (2.1 ± 3 ppb vs 2.3 ± 4 ppb; p = 0.2). ΔFeNO-SAC in 17 pairs was markedly increased (27 ± 20 ppb; p < 0.001 vs ΔFeNO-SS). The area under the receiver-operating characteristic curve for ΔFeNO in detecting an acute complication was 0.93 (p < 0.001). By applying a cut-off of >10 ppb, the sensitivity and specificity was 82% and 100%, respectively, with positive and negative predictive values of 100% and 97.5%.

CONCLUSIONS

Changes in FeNO may serve as a useful adjunct in the detection of acute complications after lung transplantation. In this limited analysis, ΔFeNO was not predictive of a subsequent decline in allograft function.

Breath biomarkers in diagnosis of pulmonary diseases

Breath analysis provides a convenient and simple alternative to traditional specimen testing in clinical laboratory diagnosis. As such, substantial research has been devoted to the analysis and identification of breath biomarkers. Development of new analytes enhances the desirability of breath analysis especially for patients who monitor daily biochemical parameters. Elucidating the physiologic significance of volatile substances in breath is essential for clinical use. This review describes the use of breath biomarkers in diagnosis of asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), lung cancer, as well as other pulmonary diseases. A number of breath biomarkers in lung pathophysiology will be described including nitric oxide (NO), carbon monoxide (CO), hydrogen peroxide (H₂O₂) and other hydrocarbons.

Nitric oxide and related enzymes in asthma: relation to severity, enzyme function and inflammation

BACKGROUND

Exhaled nitric oxide (FeNO) associates with asthma and eosinophilic inflammation. However, relationships between nitric oxide synthases, arginase, FeNO, asthma severity and inflammation remain poorly understood.

OBJECTIVES

To determine the relationships of iNOS expression/activation and arginase 2 expression with asthma severity, FeNO, nitrotyrosine (NT) and eosinophilic inflammation.

METHODS

Bronchial brushings and sputum were obtained from 25 normal controls, eight mild/no inhaled corticosteroids (ICS), 16 mild-moderate/with ICS and 35 severe asthmatics. The FeNO was measured the same day by ATS/ERS standards. The iNOS, arginase2 mRNA/protein and NT protein were measured in lysates from bronchial brushings by quantitative real-time PCR and Western blot. Induced sputum differentials were obtained.

RESULTS

Severe asthma was associated with the highest levels of iNOS protein and mRNA, although the index of iNOS mRNA to arginase2 mRNA most strongly differentiated severe from milder asthma. When evaluating NO-related enzyme functionality, iNOS mRNA/protein expression both strongly predicted FeNO (r = 0.61, P < 0.0001 for both). Only iNOS protein predicted NT levels (r = 0.48, P = 0.003) with the strongest relationship in severe asthma (r = 0.61, P = 0.009). The iNOS protein, FeNO and NT, all correlated with sputum eosinophils, but the relationships were again strongest in severe asthma. Controlling for arginase 2 mRNA/protein did not impact any functional outcome.

CONCLUSIONS AND CLINICAL RELEVANCE

These data suggest that while iNOS expression from epithelial brushings is highest in severe asthma, factors controlling arginase2 mRNA expression significantly improve differentiation of severity. In contrast, functionality of the NO pathway as measured by FeNO, NT and eosinophilic inflammation, is strongly associated with iNOS expression alone, particularly in severe asthma.

Lung transplantation and lung volume reduction surgery

Since the publication of the last edition of the Handbook of Physiology, lung transplantation has become widely available, via specialized centers, for a variety of end-stage lung diseases. Lung volume reduction surgery, a procedure for emphysema first conceptualized in the 1950s, electrified the pulmonary medicine community when it was rediscovered in the 1990s. In parallel with their technical and clinical refinement, extensive investigation has explored the unique physiology of these procedures. In the case of lung transplantation, relevant issues include the discrepant mechanical function of the donor lungs and recipient thorax, the effects of surgical denervation, acute and chronic rejection, respiratory, chest wall, and limb muscle function, and response to exercise. For lung volume reduction surgery, there have been new insights into the counterintuitive observation that lung function in severe emphysema can be improved by resecting the most diseased portions of the lungs. For both procedures, insights from physiology have fed back to clinicians to refine patient selection and to scientists to design clinical trials. This section will first provide an overview of the clinical aspects of these procedures, including patient selection, surgical techniques, complications, and outcomes. It then reviews the extensive data on lung and muscle function following transplantation and its complications. Finally, it reviews the insights from the last 15 years on the mechanisms whereby removal of lung from an emphysema patient can improve the function of the lung left behind.

Chronic allograft dysfunction

Chronic, progressive, and irreversible loss of lung function is the major medium-term and long-term complication after lung transplantation and the leading cause of death. Over the past decade, progress has been made in understanding the pathogenesis of bronchiolitis obliterans. Alloimmune factors and nonalloimmune factors may contribute to its development. Understanding the precise mechanism of each type of chronic allograft dysfunction may open up the field for new preventive and therapeutic interventions. This article reviews major new insights into the clinical aspects, pathophysiology, risk factors, diagnosis, and management of chronic allograft dysfunction after lung transplantation.

Usefulness of exhaled nitric oxide to guide risk stratification for bronchiolitis obliterans syndrome after lung transplantation

The aim of this study was to assess fractional exhaled nitric oxide (FeNO) for the early diagnosis of bronchiolitis obliterans syndrome (BOS) after lung transplantation (LTX). 611 FeNO measurements in 166 consecutive patients were classified depending on BOS stage at the time of assessment and course during minimum follow-up of 3 months: (1) stable non-BOS, (2) unstable non-BOS, (3) stable BOS and (4) unstable BOS. Unstable course was defined as new onset of BOS≥1 or progression of BOS. FeNO before unstable course was significantly increased in comparison to their stable counterparts (non-BOS: 28.9 ± 1.2 ppb, n = 40 vs. 16.4 ± 0.8 ppb, n = 131 and BOS: 32.5 ± 1.3 ppb, n = 35 vs. 15.3 ± 0.8 ppb, n = 26; p = 0.01 each). Average time from FeNO reading to onset of deterioration was 117 ± 9 days in non-BOS and 136 ± 9 days in BOS patients. The positive and negative predictive value of FeNO >20 ppb for BOS was 69.0% and 96.9%, respectively. Serial measurements demonstrated significantly lower mean individual variation in stable recipients as compared to stable patients switching to unstable course (3.2 ± 0.3 ppb vs. 12.7 ± 1.4 ppb, p = 0.02). In particular, the excellent negative predictive value of persistently low FeNO readings for future BOS make FeNO assessments a useful tool for continuous risk stratification after LTX.

Early detection of chronic pulmonary allograft dysfunction by exhaled biomarkers

RATIONALE

Early detection of bronchiolitis obliterans syndrome (BOS) is important because therapies are more likely to be effective if employed early in the disease process.

OBJECTIVES

To compare the performance of exhaled NO and CO (which reflect airway inflammation) and the slope of the alveolar plateau for helium (which reflects heterogeneity of ventilation distribution) for detection of BOS stages 0-p and 1.

METHODS

Recipients of bilateral (n=64) and single (n=1) lung grafts were prospectively monitored for 1,249 days; the helium slope was derived from single-breath washouts and exhaled NO and CO were measured by chemiluminescence on 933 occasions.

MEASUREMENTS AND MAIN RESULTS

At the end of follow-up, 9 patients were in stage 0-p and 16 patients were in BOS stage 1 or higher; 21 patients had at least one measurement made in BOS stage 0-p. All markers increased in BOS stage 0-p, but only the helium slope increased in BOS stage 1. The helium slope had better sensitivity for detection of stages 0-p and 1 than either exhaled NO or CO, but considering exhaled NO and CO together improved their sensitivity; the best sensitivity was found with the three markers in combination. The biomarkers had high negative predictive values, but low specificity and positive predictive values.

CONCLUSIONS

After lung transplantation, (1) the helium slope and exhaled NO, but also exhaled CO, increase in BOS stage 0-p, (2) the helium slope has better sensitivity than exhaled NO and CO for the detection of BOS stages 0-p and 1, and (3) exhaled biomarkers have high negative predictive values, but low specificity and positive predictive values.

The pH of exhaled breath condensate of patients with allograft rejection after lung transplantation

Endogenous airway acidification, as assessed by the condensate pH, has been implicated in the pathophysiology of inflammatory airway diseases such as cystic fibrosis and asthma. The aim of this study was to investigate the pH of condensate in patients after lung transplantation (LTX). From the cohort of transplanted patients at our center, 83 patients (9 heart-lung transplantation, 48 double-lung transplantation, 26 single-lung transplantation) were recruited and analyzed in a cross-sectional manner: 26 patients were diagnosed with chronic rejection or bronchiolitis obliterans syndrome (BOS), 7 patients were diagnosed with acute rejection (AR) while 50 patients had no evidence of rejection according to the International Society for Heart and Lung Transplantation criteria. The condensate pH was significantly reduced in patients with BOS and AR when compared to patients without rejection and control subjects (5.8 +/- 0.5 and 6.2 +/- 0.4 versus 6.6 +/- 0.4 and 6.5 +/- 0 .4, respectively; p < 0.05). Moreover, there was a significant correlation between condensate pH levels and the BOS grade (r =-0.62; p < 0.01), the FEV(1) (r = 0.39; p < 0.01) and the total cell and neutrophil count in bronchoalveolar lavage fluid (r =-0.39 and r =-0.56, respectively; p < 0.01). Airway acidification occurs in BOS and may directly or indirectly reflect airway inflammation in patients with allograft rejection after LTX. Measuring condensate pH might thus be a new tool for the evaluation of rejection in lung transplant patients.

Markers of lung disease in exhaled breath: nitric oxide

Management of airway inflammation requires proper monitoring and treatment to improve long-term outcomes. However, achieving this goal is difficult, as current methods have limitations. Although nitric oxide (NO) was first identified 200 years ago, its physiological importance was not recognized until the early 1980s. Many studies have established the role of NO as an essential messenger molecule in body systems. In addition, studies have demonstrated a significant relationship between changes in exhaled NO levels and other markers of airway inflammation. The technique used to measure NO in exhaled breath is noninvasive, reproducible, sensitive, and easy to perform. Consequently, there is growing interest in the use of exhaled NO in the management of asthma and other pulmonary conditions. The purpose of this review is to promote a basic understanding of the physiologic actions of NO, measurement techniques, and ways that research findings might translate to future application in clinical practice. Specifically, the article will review the role of exhaled NO in regard to its historical background, mechanisms of action, measurement techniques, and implications for clinical practice and research.

Rat cytomegalovirus and Listeria monocytogenes infection enhance chronic rejection after allogenic rat lung transplantation

The role of infection in the pathomechanism of obliterative bronchiolitis (OB) after human lung transplantation is controversial. In a rat lung transplantation model, we analyzed the effect of viral [rat cytomegalovirus (RCMV)] and bacterial infection [Listeria monocytogenes (LM)] on the development of chronic allograft rejection. Fisher rats underwent single left lung transplantation with allografts from Lewis rats. Postoperatively, animals were infected with either RCMV or LM, or served as noninfected controls. Animals were killed on day 120 and both lungs were evaluated histopathologically for chronic airway and chronic vascular rejection. Infection with RCMV produced a significant increase in the incidence of chronic airway rejection (66.7% vs. 20%), compared with noninfected long-term surviving animals. In rats with bacterial infection (LM) a similar increase of chronic airway changes as in viral infection (50% vs. 20%) was observed. Chronic rejection of allografts infected with either RCMV or LM was associated with significantly enhanced expression of intercellular adhesion molecule-1 (ICAM-1) on the endothelium. More infiltrating leukocytes (CD18, CD11a, CD44) and ED1-positive macrophages were found in allografts of infected animals. In this experimental model of chronic airway rejection in long-term surviving rats, not only viral but also bacterial infection resulted in enhanced development of chronic airway and vascular rejection. These results support our hypothesis that infectious complications have a substantial influence on the development of OB in human lung allografts.

Pulmonary infections increase exhaled nitric oxide in lung transplant recipients: a longitudinal study

The aim of this longitudinal study was to test whether pulmonary infections influence fractional exhaled nitric oxide levels (FENO) in otherwise clinically-stable lung transplant recipients. Levels of FENO were measured at least on 11 occasions in nine lung transplant recipients who attended for routine or urgent clinical review over 27.0 +/- 3.2 months period. Diagnosis of infection was based on clinical symptoms, functional measurements and radiological findings. Concentrations of FENO were also determined in 12 healthy volunteers. During follow-up, six patients had one, two had three, and one had four episodes of pulmonary infections. Overall, six upper and 10 lower respiratory tract infections were noted. Recipients with active infections developed increased FENO levels as compared with their own baseline levels measured in the clinically well period (10.8 +/- 1.3 vs. 7.6 +/- 1.1 ppb, p < 0.05). After antibiotic treatment, elevated FENO concentrations returned to baseline in association with full clinical recovery. Baseline FENO levels in lung transplant recipients and in healthy volunteers (6.0 +/- 0.5 ppb) were similar. The sensitivity and specificity of FENO measurement in detecting pulmonary infections were 57 and 96%, respectively. Our data suggest that pulmonary infections are associated with increased FENO levels in patients with lung allografts. Nevertheless, the measurement of FENO by itself as a screening tool for infections seems to be limited by its low sensitivity.

A prospective randomized study to evaluate the effect of leukodepletion on the rate of alveolar production of exhaled nitric oxide during cardiopulmonary bypass

BACKGROUND

Cardiopulmonary bypass is associated with a whole body inflammatory reaction. Exhaled nitric oxide increases in inflammatory lung conditions (eg, asthma) in proportion to the severity of inflammation, and has been proposed as a marker of pulmonary inflammation during cardiopulmonary bypass. This study evaluated the effect of arterial line leukocyte depletion during cardiopulmonary bypass on the rate of alveolar production of exhaled nitric oxide.

METHODS

One hundred and ten patients with normal respiratory function, undergoing first time coronary artery bypass grafting, were randomized to two groups. Fifty-five patients had an arterial line leukocyte-depleting filter and 55 controls had a standard arterial line filter. Nitric oxide was sampled through an endotracheal Teflon tube after median sternotomy, but before cardiopulmonary bypass and 30 minutes after cardiopulmonary bypass, using a real time chemiluminescence analyzer, during the phase of the alveolar plateau.

RESULTS

There were no significant differences in the precardiopulmonary bypass values of exhaled nitric oxide between the control (2.92 +/- 1.51 ppb/s) and the leukodepletion group (3.11 +/- 1.53 ppb/s) (p = 0.4). After cardiopulmonary bypass, the rate of alveolar production of exhaled nitric oxide increased in both groups, being, however, significantly higher in the control group (4.68 +/- 1.89 vs 3.72 +/- 1.33 ppb/s) (p = 0.02).

CONCLUSIONS

Continuous arterial line leukocyte-depletion significantly reduces the rate of alveolar production of exhaled nitric oxide after cardiopulmonary bypass. Changes in the rate of alveolar production of exhaled nitric oxide may be used as a marker of pulmonary inflammation in coronary artery surgery.

Surrogate markers and risk factors for chronic lung allograft dysfunction

Obliterative bronchiolitis (OB) is the histologic correlate of chronic allograft dysfunction in pulmonary transplantation. The histologic diagnosis of OB is challenging, therefore a physiologic definition, bronchiolitis obliterans syndrome (BOS) based on pulmonary function tests has been used as a surrogate marker for OB for the last decade. BOS has proven to be the best available surrogate marker for OB and is predictive of the ultimate endpoints of graft and patient survival. Multiple other clinical markers have been reported and proposed as alternates for or complements to BOS grade, but all need further evaluation and validation in large, prospective clinical trials. Lastly, given the early occurrence and high incidence of chronic allograft dysfunction, the easily measurable endpoint of BOS grade, and our lack of understanding of ways to prevent or alter the course of BOS, lung transplant recipients represent an ideal population for clinical trials targeting prevention and treatment of chronic allograft dysfunction.

NO pathway in CF and non-CF children

Controversy exists concerning abnormalities of the nitric oxide (NO) pathway in cystic fibrosis (CF) lung disease. Although some studies suggested that NO activity is impaired in CF, changes in NO production in young children have not been studied. We hypothesized that nitric oxide synthase (NOS II) expression is decreased in young children with CF, leading to decreased production of lower airway NO, and that decreased NOS II expression is related to airway inflammation. Accordingly, we measured lower airway exhaled NO, nitrate, and NOS II expression in airway epithelium and macrophages by bronchoscopy, bronchoalveolar lavage (BAL), and bronchial brushing in 13 children with CF, 4 adolescent patients with CF, and 14 disease control children. Lower airway NO and nitrate were not different between CF and disease controls. Immunostaining studies of NOS II expression in airway epithelial cells and macrophages were similar in CF and control patients. Within the CF group, however, expression of NOS II was inversely related to BAL neutrophil counts and IL-8, two markers of airway inflammation. We conclude that lower airway NO, nitrate levels, and NOS II expression are not different in young children with CF and disease control patients, but that NOS II expression decreases in CF as airway inflammation increases.

Bronchiolitis obliterans

PURPOSE OF REVIEW

Bronchiolitis obliterans (BO) occurs in both post-lung transplant and nontransplant-related individuals, and is characterized by mainly irreversible airflow obstruction that is often ultimately progressive.

RECENT FINDINGS

While post-lung transplant BO is a major cause of lung allograft dysfunction, and hence is better characterized than nontransplant-related BO, it is likely that many similarities in pathogenesis and treatment apply to both categories.

SUMMARY

Optimal management for BO remains to be established, and the role of retransplantation in this disease requires further consensus. Minimization of risk factors for BO and earlier detection in the form of methacholine challenge testing and HRCT scans of the chest amongst other forms of detection, may help in the stabilization and possible resolution of early BO.

Hydroxyurea and arginine therapy: impact on nitric oxide production in sickle cell disease

PURPOSE

Recent data suggest that hydroxyurea (HU) increases the production of nitric oxide (NO), a potent vasodilator. NO is normally metabolized from l-Arginine (Arg). However, in vitro and animal experiments suggest that HU is the NO donor itself. In contrast, a recent study indicates that nitric oxide synthase (NOS) may play a role. Since adults with sickle cell disease (SCD) are Arg-deficient, Arg availability may limit the ability of HU to maximally impact NO production if an NOS mechanism is involved. The authors have previously shown that Arg supplementation alone induces a paradoxical decrease in NO metabolite (NO(x)) production.

METHODS

The authors studied the effects of HU and Arg supplementation on NO(x) production. HU alone or HU + Arg was administered to patients with SCD at steady state, and sequential levels of Arg, serum NO(x) and exhaled NO were followed over 4 hours.

RESULTS

After HU + Arg, all patients demonstrated a significant increase in serum NO(x) production within 2 hours. When the same patients were treated with HU alone (5.1 +/- 2 micromol/L), a mixed response occurred. NO(x) levels increased in four patients and decreased in one patient (-23.3 micromol/L).

CONCLUSIONS

While Arg alone does not increase serum NO(x) production in SCD patients at steady state, it does when given together with HU. Hence, co-administration of Arg with HU may augment the NO(x) response in SCD and improve utilization of Arg in patients at steady state.

Effect of switching from cyclosporine to tacrolimus on exhaled nitric oxide and pulmonary function in patients with chronic rejection after lung transplantation

BACKGROUND

Previous studies have demonstrated that shifting immunosuppressive therapy from cyclosporine (CyA) to tacrolimus (FK) may arrest the decline in forced expiratory volume in 1 second (FEV(1)) during chronic rejection after lung transplantation. Exhaled nitric oxide (eNO) has been shown to be elevated during chronic rejection. We report the concomitant stabilization of FEV(1) and decrease in eNO after changing from CyA to FK therapy in patients with chronic rejection after lung transplantation.

METHODS

We used a prospective design. The study included 10 lung transplant patients (5 men and 5 women), mean age 44 +/- 14 years at time of transplantation, with a progressive decline in FEV(1) that was attributed to chronic rejection. Four patients underwent heart-lung transplantation and 3 had a sequential single and 3 a single-lung transplantation. The switch from CyA to FK occurred at 36 +/- 23 months after transplantation (Time 0). The eNO was measured using a chemiluminescence analyzer, according to standardized European Respiratory Society (ERS) criteria.

RESULTS

At Time 0, there were 6 patients in bronchiolitis obliterans syndrome (BOS) Stage 0-p, with a mean decline in FEV(1) of 15 +/- 3%; 2 in BOS Stage 1; and 2 in BOS Stage 2. Compared with the best post-operative FEV(1), there was a progressive and significant decline until Time 0, from 2.56 +/- 0.9 liters to 2.03 +/- 0.94 liters (p = 0.0047). Thereafter, FEV(1) stabilized: 2.03 +/- 0.94 liters at Time 0 and 2.05 +/- 0.94 liters 6 months later (p = non-significant). Concomitantly, there was a gradual increase in eNO during the 6 months before Time 0, from 11.4 +/- 2.5 ppb at the time of best FEV(1) to 20.5 +/- 14.8 ppb at Time 0. After switching, there was a non-significant decline in eNO, from 20.5 +/- 14.8 ppb to 14.9 +/- 5.4 ppb. There was no significant difference in eNO levels between the patients in BOS Stage 0-p and patients in higher BOS stages at either timepoint in the study.

CONCLUSIONS

This study illustrates that a switch from CyA to FK can stabilize pulmonary function in lung transplant patients with chronic rejection. This stabilization of FEV(1) is accompanied by a decrease in eNO, indicating that this treatment shift can reduce inflammation of airways during the course of chronic rejection. Consequently, measuring eNO may be extremely valuable in guiding the treatment of chronic rejection after lung transplantation.

Effects of extracellular triphosphate nucleotides and nucleosides on airway smooth muscle cell proliferation

Extracellular ATP and uridine triphosphate (UTP) have a range of effects on a wide variety of cells through the activation of P(2) receptors. The aim of this work was to establish if stimulation with ATP and UTP enhances airway smooth muscle (ASM) cell proliferation and to determine the type of receptor mediating this effect. Proliferation of rat ASM cells was assessed through bromodeoxyuridine (BrdU) uptake and by cell counting. At concentrations of 10(-6) and 10(-5) M, ATP and UTP induced significant increases in BrdU incorporation. ATP analogs specific for the P(2X) and P(2Y1) receptor subtypes had no effect. UDP (a P(2Y6) receptor agonist) produced significant decreases in BrdU incorporation and cell counts. Adenosine, the metabolite of ATP, produced an increase in cell proliferation through stimulation of the A(1) receptor. A(2) and A(3) receptor stimulation had no effect. Reverse transcription and polymerase chain reaction analysis showed that mRNA transcripts for the P(2Y2), P(2Y4), P(2Y6), A(1), A(2), and A(3) receptor subtypes were present in cultured ASM cells. These data show that extracellular UTP, ATP, and their metabolites may affect airway remodeling by increasing or by reducing (P(2Y6) receptor) ASM cell proliferation.

Alveolar neutrophilia is a predictor for the bronchiolitis obliterans syndrome, and increases with degree of severity

BACKGROUND

Bronchiolitis obliterans syndrome (BOS) is a common complication of lung transplantation (LT), associated with a tremendous mortality and morbidity. Recent innovative research has focused on bronchoalveolar lavage (BAL) analysis, assuming that neutrophilia might be a marker of chronic rejection.

PATIENTS AND METHODS

To address this issue, we retrospectively analyzed 258 sequential BAL from 44 lung transplant recipients, having survived for more than 3 months after surgery.

RESULTS

At the end of the follow-up, 22, 7, 7 and 8 patients had BOS stage 0, 1, 2 and 3, respectively. The total cell count and neutrophilia increased with BOS severity (P < 0.01). BOS occuring before and after the 12th month of LT were associated with early and more delayed increases of BAL neutrophils, respectively. Finally, the various kinetic profiles of neutrophil progression were identified, allowing for an earlier identification of BOS stages 2 and 3, by 3 and 6 months, respectively. Conversely, neutrophilia associated to BOS stage 1 remained low, and could not be distinguished from that of stage 0.

CONCLUSIONS

These results support the possible role of neutrophils in BOS pathogenesis, and may be of interest for an earlier detection and management of chronic rejection.

Resuscitation of hemorrhagic shock attenuates intrapulmonary nitric oxide formation

Hemorrhagic shock has been shown to upregulate intrapulmonary inducible nitric oxide (NO) synthase (iNOS) expression. Increased intrapulmonary iNOS expression is reflected by increases in concentrations of NO in the airways. The purpose of this study was to examine the effects of resuscitation on this induction of intrapulmonary NO formation caused by hemorrhage. Eighteen rats were randomized to one of three groups. One group of rats was simply sham-instrumented and monitored. Two other groups experienced hemorrhagic shock (mean systemic blood pressure of 40-45 mmHg) for 60 min. In one of the hemorrhagic shock groups, resuscitation was performed by re-infusing the shed blood and supplementing it with normal saline. Compared with sham-instrumented rats, those exposed to hemorrhagic shock without subsequent resuscitation exhibited a 10-fold increase in exhaled NO concentrations. Additionally, concentrations of both intrapulmonary iNOS protein and mRNA increased. Resuscitation attenuated the hemorrhage-induced upregulation of exhaled NO, iNOS protein and iNOS mRNA. This data suggests that resuscitation attenuates the hemorrhagic shock-induced formation of intrapulmonary NO by downregulating iNOS transcription. We believe that exhaled NO concentrations provide a useful, non-invasive method of monitoring the intrapulmonary inflammatory sequelae of hemorrhagic shock.

Nitric oxide and protein nitration in the cystic fibrosis airway

Cystic fibrosis (CF), characterized by chronic airway infection and inflammation, ultimately leads to respiratory failure. Exhaled nitric oxide (NO), elevated in most inflammatory airway diseases, is decreased in CF, suggesting either decreased production or accelerated metabolism of NO. The present studies performed on two groups of CF patients provide further support for a disordered NO airway metabolism in CF respiratory tract disease. Despite confirmation of subnormal NOS2 in the CF airway epithelium, alternative isoforms NOS1 and NOS3 were present, and inflammatory cells in the CF airway expressed abundant NOS2. Increased immunohistochemical staining for nitrotyrosine was demonstrated in lung tissues from patients with CF as compared to control. To our knowledge, this is the first report localizing nitrotyrosine in diseased CF lung tissue. While the relative NOS2 deficiency in CF respiratory tract epithelium may contribute to the lower expired NO levels, these results suggest that increased metabolism of NO is also present in advanced CF lung disease. The significance of altered NO metabolism and protein nitration in CF remains to be fully elucidated.

Exhaled nitric oxide does not reflect the severity of acute lung injury: an experimental study in a rat model of extracorporeal circulation

OBJECTIVE

This study was undertaken to determine whether an increase in exhaled nitric oxide would reflect the severity of the acute lung injury caused by extracorporeal circulation.

DESIGN

Prospective, controlled animal laboratory investigation.

SETTING

University laboratory.

SUBJECTS

Male, anesthetized, paralyzed, and mechanically ventilated Wistar rats (n = 34).

INTERVENTIONS

Twenty-three Wistar rats underwent a partial (100 mL.kg(-1).min(-1)) femoro-femoral extracorporeal circulation in normothermia for 90 mins. Eleven time-matched rats formed the sham group.

MEASUREMENTS AND MAIN RESULTS

Exhaled nitric oxide was monitored with a chemiluminescence analyzer. Acute lung injury was assessed by blood gas analysis and lung water content. Lung Evans blue dye content, lung myeloperoxidase, and heme oxygenase activities were determined. Compared with the sham rats, extracorporeal circulation was responsible for acute lung injury characterized by an increased lung water content (82.4 +/- 1.3% vs. 77.9 +/- 1.1%; p<.05), an increased Evans blue dye content (191.8 +/- 15.8 vs. 112.5 +/- 16.8 mg/g tissue wet weight; <.01), and an increased pulmonary heme oxygenase activity (332.9 +/- 107 vs. 113.7 +/- 46.5 pmol. hr(-1).mg of protein(-1); p<.05). Exhaled nitric oxide remained stable throughout the experiment in all sham rats. Among the 23 rats that underwent extracorporeal circulation, eight rats (35%) experienced an increase in exhaled nitric oxide concentration (16.9 +/- 12.7 ppb). There was no significant difference between rats that did or did not experience an increase in exhaled nitric oxide regarding each index of acute lung injury.

CONCLUSIONS

An increase in exhaled nitric oxide did not reflect the severity of the acute lung injury caused by extracorporeal circulation. Its significance remains to be determined.

Low exhaled nitric oxide and a polymorphism in the NOS I gene is associated with acute chest syndrome

Abnormalities of nitric oxide metabolism have been implicated in the pathogenesis of acute chest syndrome in subjects with sickle cell anemia. It is not known whether exhaled nitric oxide levels (FE(NO)) are abnormal in children with a history of the acute chest syndrome (ACS). We compared FE(NO), plasma nitric oxide metabolites (NO(x)), serum arginine and citrulline levels, and the number of AAT repeats in intron 20 of NOS I in subjects with sickle cell disease (SCD) and a history of at least one episode of ACS (ACS(+), n = 13), subjects with SCD and no prior history of ACS (ACS(-), n = 7), and healthy children (HC, n = 6). Mean +/- SD FE(NO) (ppb) was lower in ACS(+) than in ACS(-) and HC: (10.4 +/- 4.3 versus 23.4 +/- 6.1 p = 0.002] and 30.4 +/- 15.8 [p = 0.0001], respectively). Plasma NO(x) (microM) were similar in all three groups (37.3 +/- 19.4, 33.0 +/- 13.2, 44.7 +/- 7.8, respectively). Arginine and citrulline levels (microM) did not differ between ACS(+) and ACS(-) groups. Spirometric data revealed a mildly diminished FEV(1) and FVC in ACS(+) that was statistically different from HC but not ACS(-): (FEV(1) as % of predicted for ACS(+), ACS(-), and HC; 83 +/- 17 versus 87 +/- 16 versus 102 +/- 16, respectively, p < 0.05 between ACS(+) and HC). The level of FE(NO) was significantly associated with the sum of AAT repeats in intron 20 of NOS I gene alleles. The correlation coefficient (r) was 0.62 (p < 0.005). We conclude that FE(NO) levels are significantly reduced in subjects who have a history of ACS and that the FE(NO) levels are significantly correlated with the number of NOS I AAT repeats. FE(NO) is a sensitive marker and may be a predictor of ACS prone children.

Exhaled monoxides as a pulmonary function test: use of exhaled nitric oxide and carbon monoxide

Although there has been tremendous improvement in the technologic ability to measure exhaled gases and monitor biologic processes in the lung, it has not yet found a clinical role outside the research laboratory. Common themes seem to be significant overlap in the amount of exhaled gases in clinically distinct populations, confounding variables such as infection, smoking, and environmental exposure, and lack of consistent change with disease management. If these tests are ever to be used by the general pulmonologist, consistent links between the measurements and the response to disease modification will need to be demonstrated at the very least and, ideally, the clinician would like to see improved outcomes when these noninvasive tests are employed regularly.

Patterns and significance of exhaled-breath biomarkers in lung transplant recipients with acute allograft rejection

BACKGROUND

Obliterative bronchiolitis (OB) remains one of the leading causes of death in lung transplant recipients after 2 years, and acute rejection (AR) of lung allograft is a major risk factor for OB. Treatment of AR may reduce the incidence of OB, although diagnosis of AR often requires bronchoscopic lung biopsy. In this study, we evaluated the utility of exhaled-breath biomarkers for the non-invasive diagnosis of AR.

METHODS

We obtained breath samples from 44 consecutive lung transplant recipients who attended ambulatory follow-up visits for the Johns Hopkins Lung Transplant Program. Bronchoscopy within 7 days of their breath samples showed histopathology in 21 of these patients, and we included them in our analysis. We measured hydrocarbon markers of pro-oxidant events (ethane and 1-pentane), isoprene, acetone, and sulfur-containing compounds (hydrogen sulfide and carbonyl sulfide) in exhaled breath and compared their levels to the lung histopathology, graded as stable (non-rejection) or AR. None of the study subjects were diagnosed with OB or infection at the time of the clinical bronchoscopy.

RESULTS

We found no significant difference in exhaled levels of hydrocarbons, acetone, or hydrogen sulfide between the stable and AR groups. However, we did find significant increase in exhaled carbonyl sulfide (COS) levels in AR subjects compared with stable subjects. We also observed a trend in 7 of 8 patients who had serial sets of breath and histopathology data that supported a role for COS as a breath biomarker of AR.

CONCLUSIONS

This study demonstrated elevations in exhaled COS levels in subjects with AR compared with stable subjects, suggesting a diagnostic role for this non-invasive biomarker. Further exploration of breath analysis in lung transplant recipients is warranted to complement fiberoptic bronchoscopy and obviate the need for this procedure in some patients.

Bronchoalveolar lavage macrophage and lymphocyte phenotypes in lung transplant recipients

Recent publications have demonstrated potentially pathologic changes in bronchoalveolar lavage (BAL) from clinically stable lung transplant recipients (SLTRs), but there are few available data on alveolar macrophages (AMs). We formulated the hypothesis that changes in BAL AM and lymphocyte phenotypes would be apparent even in SLTRs.A cross-sectional study using a standardized 3 x 60 ml BAL, investigating lymphocyte and AM phenotypes in 19 SLTRs, 5 subjects with bronchiolitis obliterans syndrome (BOS) and 18 normal control volunteers. BAL lymphocyte and AM markers were assessed using flow cytometry. We confirmed a significant elevation of neutrophils in all lung transplant recipients with a more marked elevation in the BOS subjects. Flow-cytometric analysis showed increased numbers of natural killer (NK; CD56/CD16-positive) cells, increased CD11b- and CD11c-positive CD3 lymphocytes, increased CD8-positive lymphocytes and increased HLA-DR expression in CD8 cells from the lung transplant recipients, when compared with normals (p <.005). In contrast, the expression of a number of AM surface markers, associated with a range of host defense functions against bacteria, fungi and viruses (CD11a, CD11b, CD11c, HLA-DR, CD14), was lower in both SLTRs and those with BOS (p <.05). These novel findings are consistent with complex lymphocyte and macrophage changes that may result from clinically silent infection, partially suppressed rejection, or both.

Iron overload and nitric oxide-derived oxidative stress following lung transplantation

BACKGROUND

Reactive oxygen species (ROS) may contribute to airway injury and the development of the bronchiolitis obliterans syndrome (BOS) following lung transplantation (LT). Chemically active iron released from ferritin stores and nitric oxide (NO)-derived radicals may add to the oxidative burden.

METHODS

We determined the concentrations of ferritin and the aqueous NO derivative nitrite (NO2(-)) within bronchoalveolar lavage fluid (BALF) of 14 stable LT recipients (ST) and 7 subjects with BOS and 21 normal controls. We also assessed the relationship between BALF ferritin and hemosiderin-laden macrophages (HLMs) using a hemosiderin score (HS) and determined BALF albumin concentration as a marker of microvascular leakage.

RESULTS

BALF ferritin concentrations and HSs were significantly elevated in LT recipients overall compared with normal controls (p < 0.05). BALF NO2(-) levels were elevated in BOS subjects and STs compared with normal controls (p = 0.002 and p = 0.09, respectively), but there was no difference between transplant groups. BALF albumin concentrations were elevated in BOS patients compared with normal controls (p = 0.02) and ST (p = 0.05), but there was no difference between STs and controls. There was a significant relationship between BALF ferritin concentration and HS in LT recipients overall (r(s) = 0.7, p < 0.001). In BOS subjects, but not ST, BALF ferritin was significantly related to BALF albumin (r(s) = 0.8, p = 0.05) and there was a weak relationship with NO2(-) concentration (r(s) = 0.6, p = 0.1). BALF NO2(-) was strongly related to BALF % neutrophils in BOS subjects (r(s) = 0.9, p < 0.01), but there was no such relationship in STs.

CONCLUSIONS

Our findings suggest that the allograft could be subject to significant iron-generated oxidative stress, which may be exacerbated by NO and neutrophil-derived ROS, particularly in BOS. Microvascular leakage may be a feature of established chronic rejection, which potentiates the iron overload and contributes to further airway damage and remodeling.

Extended exhaled NO measurement differentiates between alveolar and bronchial inflammation

Lower respiratory tract inflammation can be detected by measuring exhaled nitric oxide (NO) concentration at a single exhalation flow rate, but this does not differentiate between alveolar and bronchial NO production. We assessed alveolar NO concentration and bronchial NO flux with an extended method of measuring exhaled NO at several exhalation flow rates in 40 patients with asthma, 17 patients with alveolitis, and 57 healthy control subjects. Bronchial NO flux was higher in asthma (2.5 +/- 0.3 nl/s, p < 0.001) than in alveolitis (0.7 +/- 0.1 nl/s) and healthy control subjects (0.7 +/- 0.1 nl/s). Alveolar NO concentration was higher in alveolitis (4.1 +/- 0.3 ppb, p < 0.001) than in asthma (1.1 +/- 0.2 ppb) and healthy control subjects (1.1 +/- 0.1 ppb). In asthma, bronchial NO flux correlated with serum level of eosinophil protein X (EPX) (r = 0.60, p < 0.001) and bronchial hyperresponsiveness (r = 0.55, p < 0.001). In alveolitis, alveolar NO concentration correlated inversely with pulmonary diffusing capacity (r = -0.55, p = 0.022) and pulmonary restriction. Glucocorticoid treatment or allergen avoidance normalized bronchial NO flux in asthma and decreased alveolar NO concentration toward normal in alveolitis. In conclusion, extended exhaled NO measurement can be used to separately assess alveolar and bronchial inflammation and to assess disease activity/severity in asthma and alveolitis.

Post-lung transplant bronchiolitis obliterans syndrome (BOS) is characterized by increased exhaled nitric oxide levels and epithelial inducible nitric oxide synthase

In conditions characterized by airway inflammation, exhaled nitric oxide (eNO) levels are increased. Post-lung transplant bronchiolitis obliterans syndrome (BOS) is characterized by airway inflammation and development of progressive airway narrowing and fibrosis. We have previously shown that in stable lung transplant recipients (LTR), mean eNO levels were not elevated but were still related to the degree of airway neutrophilia within the group. The hypothesis now tested is that in BOS, eNO levels are increased in association with even greater airway neutrophilia and enhanced expression of inducible (iNOS) nitric oxide synthase in the bronchial epithelium. We determined eNO levels in 40 LTR in four groups: well and "stable": LTR (n = 20), BOS (n = 8), bacterial airway infection (BI, n = 6), and acute rejection (AR, n = 6). Following bronchoscopic sampling, we performed a quantitative assessment of iNOS and constitutive nitric oxide synthase (cNOS) expression in endobronchial biopsies by immunohistochemistry. Mean +/- SEM eNO levels in BOS and BI were significantly higher than in stable LTR (20 +/- 1.2 parts per billion [ppb] and 24.7 +/- 1.7 ppb versus 12.5 +/- 0.9 ppb; p < 0.01 for both). In AR, eNO levels (13.4 ppb +/- 0.5) were not different in stable LTR (p = 0.34). When compared with stable LTR, there was increased expression of iNOS in the bronchial epithelium and generally in the lamina propria (LP) in patients with BOS and BI. In AR, iNOS expression was increased but only in the LP in a perivascular distribution. Expression of cNOS was reduced in BOS but not in BI and AR compared with the stable group. Using regression analysis, only iNOS expression in the bronchial epithelium (r(2) = 0.77; p < 0.0001) and %BAL neutrophils (r(2) = 0. 79; p < 0.0001) were positively related to eNO in stable LTR and BOS. We conclude that epithelial iNOS appears to be the major source of eNO. Exhaled NO levels also appear to reflect the degree of airway neutrophilia in both stable LTR and BOS groups. This suggests that serial eNO measurements may be able to predict the early development of BOS.