Reciprocal regulation of airway rejection by the inducible gas-forming enzymes heme oxygenase and nitric oxide synthase

Obliterative bronchiolitis (OB) develops insidiously in nearly half of all lung transplant recipients. Although typically preceded by a CD8+ T cell–rich lymphocytic bronchitis, it remains unresponsive to conventional immunosuppression. Using an airflow permissive model to study the role of gases flowing over the transplanted airway, it is shown that prolonged inhalation of sublethal doses of carbon monoxide (CO), but not nitric oxide (NO), obliterate the appearance of the obstructive airway lesion. Induction of the enzyme responsible for the synthesis of CO, heme oxygenase (Hmox) 1, increased carboxyhemoglobin levels and suppressed lymphocytic bronchitis and airway luminal occlusion after transplantation. In contrast, zinc protoporphyrin IX, a competitive inhibitor of Hmox, increased airway luminal occlusion. Compared with wild-type allografts, expression of inducible NO synthase (iNOS), which promotes the influx of cytoeffector leukocytes and airway graft rejection, was strikingly reduced by either enhanced expression of Hmox-1 or exogenous CO. Hmox-1/CO decreased nuclear factor (NF)-κB binding activity to the iNOS promoter region and iNOS expression. Inhibition of soluble guanylate cyclase did not interfere with the ability of CO to suppress OB, implicating a cyclic guanosine 3′,5′-monophosphate–independent mechanism through which CO suppresses NF-κB, iNOS transcription, and OB. Prolonged CO inhalation represents a new immunosuppresive strategy to prevent OB

Course of FEV1 after Onset of Bronchiolitis Obliterans Syndrome in Lung Transplant Recipients

Rationale: Bronchiolitis obliterans syndrome (BOS), defined by loss of lung function, develops in the majority of lung transplant recipients. However, there is a paucity of information on the subsequent course of lung function in these patients. Objectives: To characterize the course of FEV1 over time after development of BOS and to determine the predictors that influence the rate of functional decline of FEV1. Methods: FEV1% predicted (FEV1%pred) trajectories were studied in 111 lung transplant recipients with BOS by multivariate, linear, mixed-effects statistical models. Measurements and Main Results: FEV1%pred varied over time after BOS onset, with the steepest decline typically seen in the first 6 months (12% decline; p < 0.0001). Bilateral lung transplant recipients had significantly higher FEV1%pred at BOS diagnosis (71 vs. 47%; p < 0.0001) and at 24 months after BOS onset (58 vs. 41%; p = 0.0001). Female gender and pretransplant diagnosis of idiopathic pulmonary fibrosis were associated with a steeper decline in FEV1%pred in the first 6 months after BOS diagnosis (p = 0.02 and 0.04, respectively). A fall in FEV1 greater than 20% in the 6 months preceding BOS (termed “rapid onset”) was associated with shorter time to BOS onset (p = 0.01), lower FEV1%pred at BOS onset (p < 0.0001), steeper decline in the first 6 months (p = 0.03), and lower FEV1%pred at 2 years after onset (p = 0.0002). Conclusions: Rapid onset of BOS, female gender, pretransplant diagnosis of idiopathic pulmonary fibrosis, and single-lung transplantation are associated with worse pulmonary function after BOS onset.Supported in part by National Institutes of Health grants K23 HL077719 (V.N.L.) and K24 HL04212 (F.J.M.), and by a grant from the American Society of Transplantation/ Chest Foundation (V.N.L.).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91969/1/2007 AJRCCM Course of FEV1 after Onset of Bronchiolitis Obliterans Syndrome in Lung Transplant Recipients.pd

Prognostic Value of Bronchiolitis Obliterans Syndrome Stage 0-p in Single-Lung Transplant Recipients

Rationale: Early diagnosis of bronchiolitis obliterans syndrome (BOS) is critical in understanding pathogenesis and devising therapeutic trials. Although potential-BOS stage (BOS 0-p), encompassing early changes in FEV1 and forced expiratory flow, midexpiratory phase (FEF25–75%), has been proposed, there is a paucity of data validating its utility in single-lung transplantation. Objective: The aim of this study was to define the predictive ability of BOS 0-p in single-lung transplantation. Methods: We retrospectively analyzed spirometric data for 197 single-lung recipients. Sensitivity, specificity, and positive predictive value of BOS 0-p were examined over time using Kaplan-Meier methodology. Results: BOS 0-p FEV1 was associated with higher sensitivity, specificity, and positive predictive value than the FEF25–75% criterion over different time periods investigated. The probability of testing positive for BOS 0-p FEV1 in patients with BOS (sensitivity) was 71% at 2 years before the onset of BOS. The probability of being free from development of BOS 0-p FEV1 in patients free of BOS at follow-up (specificity) was 93% within the last year. Of patients who met the BOS 0-p FEV1 criterion, 81% developed BOS or died within 3 years. The specificity and positive predictive value curves for the BOS 0-p FEV1 were significantly different between patients with underlying restrictive versus obstructive physiology (p = 0.05 and 0.01, respectively). Conclusion: The FEV1 criterion for BOS 0-p provides useful predictive information regarding the risk of development of BOS or death in single-lung recipients. The predictive value of this criterion is higher in patients with underlying restriction and is superior to the FEF25–75% criterion.Supported in part by National Institutes of Health grants K23 HL077719 and K24HL04212 and American Lung Association RG-1059-N.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91970/1/2005 AJRCCM - Prognostic Value of Bronchiolitis Obliterans Syndrome Stage 0-p in Single-Lung Transplant Recipients.pd

Cell-associated bacteria in the human lung microbiome

Abstract Background Recent studies have revealed that bronchoalveolar lavage (BAL) fluid contains previously unappreciated communities of bacteria. In vitro and in vivo studies have shown that host inflammatory signals prompt bacteria to disperse from cell-associated biofilms and adopt a virulent free-living phenotype. The proportion of the lung microbiota that is cell-associated is unknown. Results Forty-six BAL specimens were obtained from lung transplant recipients and divided into two aliquots: ‘whole BAL’ and ‘acellular BAL,’ the latter processed with a low-speed, short-duration centrifugation step. Both aliquots were analyzed via bacterial 16S rRNA gene pyrosequencing. The BAL specimens represented a wide spectrum of lung health, ranging from healthy and asymptomatic to acutely infected. Bacterial signal was detected in 52% of acellular BAL aliquots, fewer than were detected in whole BAL (96%, p ≤ 0.0001). Detection of bacteria in acellular BAL was associated with indices of acute infection [BAL neutrophilia, high total bacterial (16S) DNA, low community diversity, p < 0.01 for all] and, independently, with low relative abundance of specific taxonomic groups (p < 0.05). When whole and acellular aliquots from the same bronchoscopy were directly compared, acellular BAL contained fewer bacterial species (p < 0.05); whole and acellular BAL similarity was positively associated with evidence of infection and negatively associated with relative abundance of several prominent taxa (p < 0.001). Acellular BAL contained decreased relative abundance of Prevotella spp. (p < 0.05) and Pseudomonas fluorescens (p < 0.05). Conclusions We present a novel methodological and analytical approach to the localization of lung microbiota and show that prominent members of the lung microbiome are cell-associated, potentially via biofilms, cell adhesion, or intracellularity.http://deepblue.lib.umich.edu/bitstream/2027.42/111056/1/40168_2014_Article_75.pd

Mesenchymal stromal cells in bronchoalveolar lavage as predictors of bronchiolitis obliterans syndrome

Rationale: Bronchoalveolar lavage fluid (BAL) from human lung allografts demonstrates the presence of a multipotentmesenchymal stromal cell population. However, the clinical relevance of this novel cellular component of BAL and its association with bronchiolitis obliterans syndrome (BOS), a disease marked by progressive airflow limitation secondary to fibrotic obliteration of the small airways, remains to be determined. Objectives: In this study we investigate the association of number of mesenchymal stromal cells in BAL with development of BOS in human lung transplant recipients. Methods:Mesenchymal colony-forming units (CFUs)were quantitated in a cohort of 405 BAL samples obtained from 162 lung transplant recipients. Poisson generalized estimating equations were used to determine the predictors of BAL mesenchymal CFU count. Measurements and Main Results: Higher CFU counts were noted early post-transplantation; time from transplant to BAL of greater than 3 months predicted 0.4-fold lower CFU counts (P = 0.0001). BOS diagnosis less than or equal to 365 days before BAL was associated with a 2.11-fold higher CFU count (P = 0.02). There were 2.62- and 2.70-fold higher CFU counts noted in the presence of histologic diagnosis of bronchiolitis obliterans (P = 0.05) and organizing pneumonia (0.0003), respectively. In BAL samples obtained from BOS-free patients greater than 6 months post-transplantation (n = 173), higher mesenchymal CFU counts (>=10) significantly predicted BOS onset in both univariate (hazard ratio, 5.61; 95%CI, 3.03–10.38; P < 0.0001) andmultivariate (hazard ratio, 5.02; 95%CI, 2.40–10.51; P < 0.0001) Cox regression analysis. Conclusions: Measurement of mesenchymal CFUs in the BAL provides predictive information regarding future BOS onset.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91951/1/2011 AJRCCM Mesenchymal stromal cells in bronchoalveolar lavage as predictors of bronchiolitis obliterans syndrome.pd

Prognostic value of desaturation during a six minute walk test in Idiopathic Interstitial Pneumonia

Exercise-induced hypoxia is an index of the severity of interstitial lung disease. We hypothesized that desaturation during a 6-minute walk test would predict mortality for patients with usual interstitial pneumonia (n = 83) and nonspecific interstitial pneumonia (n = 22). Consecutive patients with biopsy-proven disease performed a 6-minute walk test between January 1996 and December 2001. Desaturation was defined as a fall in oxygen saturation to 88% or less during the 6-minute walk test. Desaturation was common (44 of 83 usual interstitial pneumonia and 8 of 22 nonspecific interstitial pneumonia; chi square, p = 0.39). Patients with usual interstitial pneumonia or nonspecific interstitial pneumonia who desaturated had a significantly higher mortality than patients who did not desaturate (respective log-rank tests, p = 0.0018, p = 0.0089). In patients with usual interstitial pneumonia, the presence of desaturation was associated with an increased hazard of death (hazard ratio, 4.2; 95% confidence interval, 1.40, 12.56; p = 0.01) after adjusting for age, sex, smoking, baseline diffusion capacity for carbon monoxide, FVC, and resting saturation.Weconclude that knowledge of desaturation during a 6-minute walk test adds prognostic information for patients with usual interstitial pneumonia and nonspecific interstitial pneumonia.Supported in part by National Institutes of Health NHLBI Grant #P50HL46487, NHLBI, 1 K24 HL04212, and 1 K23 HL68713.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91972/1/2003 AJRCCM - Prognostic value of desaturation during a six minute walk test in Idiopathic Interstitial Pneumonia.pd

Prognostic Value of Bronchiolitis Obliterans Syndrome Stage 0-p in Single-Lung Transplant Recipients

Rationale: Early diagnosis of bronchiolitis obliterans syndrome (BOS) is critical in understanding pathogenesis and devising therapeutic trials. Although potential-BOS stage (BOS 0-p), encompassing early changes in FEV 1 and forced expiratory flow, midexpiratory phase (FEF 25-75% ), has been proposed, there is a paucity of data validating its utility in single-lung transplantation. Objective: The aim of this study was to define the predictive ability of BOS 0-p in single-lung transplantation. Methods: We retrospectively analyzed spirometric data for 197 single-lung recipients. Sensitivity, specificity, and positive predictive value of BOS 0-p were examined over time using Kaplan-Meier methodology. Results: BOS 0-p FEV 1 was associated with higher sensitivity, specificity, and positive predictive value than the FEF 25-75% criterion over different time periods investigated. The probability of testing positive for BOS 0-p FEV 1 in patients with BOS (sensitivity) was 71% at 2 years before the onset of BOS. The probability of being free from development of BOS 0-p FEV 1 in patients free of BOS at follow-up (specificity) was 93% within the last year. Of patients who met the BOS 0-p FEV 1 criterion, 81% developed BOS or died within 3 years. The specificity and positive predictive value curves for the BOS 0-p FEV 1 were significantly different between patients with underlying restrictive versus obstructive physiology (p ϭ 0.05 and 0.01, respectively). Conclusion: The FEV 1 criterion for BOS 0-p provides useful predictive information regarding the risk of development of BOS or death in single-lung recipients. The predictive value of this criterion is higher in patients with underlying restriction and is superior to the FEF 25-75% criterion. Keywords: bronchiolitis obliterans syndrome; diagnosis; lung transplantation; staging Bronchiolitis obliterans is the major complication limiting outcomes in lung transplantation (1-3). Its clinical correlate, bronchiolitis obliterans syndrome (BOS), is defined as a fall in FEV 1 of greater than 20% from baseline determined by the average of two measurements made at least 3 weeks apart (4). Development of BOS is associated with progressive irreversible decline in lung function with a poor response to therapeutic interventions (1, 2). This feature, and the knowledge that pathogenesis of BO involves progressive fibroproliferation (2, 5), underscores the need for early intervention and the need to develop predictors of this disease. Implementation of increasingly sensitive criteria for identifying early decline in pulmonary function may allow the prediction of BOS. As such, a potential-BOS stage (BOS 0-p), defined by a 10 to 19% decrease in FEV 1 and/or by a 25% or greater decrease in forced expiratory flow, midexpiratory phase (FEF 25-75% ), from baseline was added to the original staging system in 2001 (4). In bilateral lung transplant recipients, the FEV 1 but not the FEF 25-75% criterion for BOS 0-p was shown to be a reasonable predictor of BOS (6). However, the role of various criteria of BOS 0-p in predicting recipients with BOS remains to be established in single-lung transplant (SLT) recipients. This population is of particular interest because spirometric criteria, such as FEV 1 and FEF 25-75% , are influenced by degree and nature of native lung pathology This study provides novel data defining the ability of both FEV 1 and FEF 25-75% criteria for BOS 0-p to predict development of BOS in a large cohort of SLT recipients. Some of these results have been previously reported in the form of an abstract (8). METHODS Patients The study group comprised 197 consecutive SLT recipients who were alive 3 months post-transplantation and had post-transplant pulmonary functions available. The study was approved by the University of Michigan Institutional Review Board. All patients were followed by a standardized protocol as previously described (9). Pulmonary function testing was performed following standards established by the American Thoracic Society at each clinic visit (10). Definition of BOS Baseline FEV 1 and FEF 25-75% were determined according to the published guidelines (4). The criterion for BOS was met when two consecutive FEV 1 values at least 3 weeks apart fell below 80% of baseline FEV 1 . Therefore, BOS diagnosis included stages 1, 2, and 3. Medical records of the patients during this time period were reviewed to exclude confounding variables, including infection, acute rejection, bronchial stenosis, and recurrence of primary disease or any other factors that might explain this decline in lung function. The date of onset of BOS was defined as the date of the first of the two FEV 1 measurements used to establish the diagnosis. Definition of BOS 0-p BOS 0-p was determined by the FEV 1 and the FEF 25-75% criteria, as defined by the new guidelines (4), using a similar method as described above. A modified FEF 25-75% criterion for stage 0-p as defined by Hachem and others (6) in the bilateral lung transplant population was also analyzed. This modified FEF 25-75% redefines the baseline FEF 25-75% as the average of the two FEF 25-75% measurements obtained with the two highest FEV 1 measurements (6). Data Analysis Correlated times to event were analyzed using years-of-life-saved statistics (11). Kaplan-Meier methodology was used to estimate sensitivity, specificity, and positive predictive value (PPV) curves for relating the diagnosis of BOS 0-p by various criteria to development of BOS. These diagnostic curves are functions of the time between meeting, or not meeting, the BOS 0-p and BOS criteria as well as the available follow-up window. The appropriate patient population, event time scale, and follow-up time scale used to construct sensitivity, specificity, and PP

Multicenter evaluation of parametric response mapping as an indicator of bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156134/2/ajt15814_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156134/1/ajt15814.pd

Quantitative Evidence for Revising the Definition of Primary Graft Dysfunction after Lung Transplant

RATIONALE: Primary graft dysfunction (PGD) is a form of acute lung injury that occurs after lung transplantation. The definition of PGD was standardized in 2005. Since that time, clinical practice has evolved, and this definition is increasingly used as a primary endpoint for clinical trials; therefore, validation is warranted. OBJECTIVES: We sought to determine whether refinements to the 2005 consensus definition could further improve construct validity. METHODS: Data from the Lung Transplant Outcomes Group multicenter cohort were used to compare variations on the PGD definition, including alternate oxygenation thresholds, inclusion of additional severity groups, and effects of procedure type and mechanical ventilation. Convergent and divergent validity were compared for mortality prediction and concurrent lung injury biomarker discrimination. MEASUREMENTS AND MAIN RESULTS: A total of 1,179 subjects from 10 centers were enrolled from 2007 to 2012. Median length of follow-up was 4 years (interquartile range = 2.4-5.9). No mortality differences were noted between no PGD (grade 0) and mild PGD (grade 1). Significantly better mortality discrimination was evident for all definitions using later time points (48, 72, or 48-72 hours; P < 0.001). Biomarker divergent discrimination was superior when collapsing grades 0 and 1. Additional severity grades, use of mechanical ventilation, and transplant procedure type had minimal or no effect on mortality or biomarker discrimination. CONCLUSIONS: The PGD consensus definition can be simplified by combining lower PGD grades. Construct validity of grading was present regardless of transplant procedure type or use of mechanical ventilation. Additional severity categories had minimal impact on mortality or biomarker discrimination

The relationship between plasma lipid peroxidation products and primary graft dysfunction after lung transplantation is modified by donor smoking and reperfusion hyperoxia

BACKGROUND: Donor smoking history and higher fraction of inspired oxygen (FIO2) at reperfusion are associated with primary graft dysfunction (PGD) after lung transplantation. We hypothesized that oxidative injury biomarkers would be elevated in PGD, with higher levels associated with donor exposure to cigarette smoke and recipient hyperoxia at reperfusion. METHODS: We performed a nested case-control study of 72 lung transplant recipients from the Lung Transplant Outcomes Group cohort. Using mass spectroscopy, F2-isoprostanes and isofurans were measured in plasma collected after transplantation. Cases were defined in 2 ways: grade 3 PGD present at day 2 or day 3 after reperfusion (severe PGD) or any grade 3 PGD (any PGD). RESULTS: There were 31 severe PGD cases with 41 controls and 35 any PGD cases with 37 controls. Plasma F2-isoprostane levels were higher in severe PGD cases compared with controls (28.6 pg/ml vs 19.8 pg/ml, p = 0.03). Plasma F2-isoprostane levels were higher in severe PGD cases compared with controls (29.6 pg/ml vs 19.0 pg/ml, p = 0.03) among patients reperfused with FIO2 >40%. Among recipients of lungs from donors with smoke exposure, plasma F2-isoprostane (38.2 pg/ml vs 22.5 pg/ml, p = 0.046) and isofuran (66.9 pg/ml vs 34.6 pg/ml, p = 0.046) levels were higher in severe PGD compared with control subjects. CONCLUSIONS: Plasma levels of lipid peroxidation products are higher in patients with severe PGD, in recipients of lungs from donors with smoke exposure, and in recipients exposed to higher Fio2 at reperfusion. Oxidative injury is an important mechanism of PGD and may be magnified by donor exposure to cigarette smoke and hyperoxia at reperfusion