Stable Lung Transplant Recipients Research Articles

Variability of Exhaled Breath Condensate pH in Lung Transplant Recipients

Background: Measurement of pH in exhaled breath condensate (EBC) may represent a novel method for investigating airway pathology. Objectives: The aim of this longitudinal study was to assess the variability of EBC pH in stable lung transplant recipients (LTR). Methods: During routine clinical visits 74 EBC pH measurements were performed in 17 LTR. EBC pH was also measured in 19 healthy volunteers on four separate occasions. EBC pH was determined at standard CO₂ partial pressure by a blood gas analyzer. Results: Mean EBC pH in clinically stable LTR and in controls was similar (6.38 ± 0.09 vs. 6.44 ± 0.16; p =nonsignificant). Coefficient of variation for pH in LTR and controls was 2.1 and 2.3%, respectively. The limits of agreement for between-visit variability determined by the Bland-Altman test in LTR and healthy volunteers were also comparable (–0.29 and 0.46 vs. –0.53 and 0.44). Conclusions: Our data suggest that the variability of EBC pH in stable LTR is relatively small, and it is similar to that in healthy nontransplant subjects.

Chemokine redundancy in BOS pathogenesis. A possible role also for the CC chemokines: MIP3-beta, MIP3-alpha, MDC and their specific receptors

Bronchiolitis obliterans syndrome (BOS) is one of the most important factors limiting the long-term survival of lung transplant recipients (LTR), however its pathogenesis still remains unclear. We hypothesized that an increased production of certain specific proinflammatory mediators in the first post-transplant year would predispose to BOS.We retrospectively evaluated temporal kinetics of some CC chemokines that have not yet been evaluated, including CCL3/MIP1-α, CCL4/MIP1-β, CCL17/TARC, CCL19/MIP3-β, CCL20/MIP3-α, CCL22/MDC and CCL26/eotaxin, in broncho-alveolar lavage fluid (BAL-f) in the first post-transplant year in a cohort of 8 LTR before the development of BOS (pre-BOS LTR) and 8 LTR with long-term stable clinical conditions (stable LTR). Chemokine levels were assayed by means of a multiplex sandwich ELISA. Furthermore, for those ligands which resulted significantly predictive of BOS onset, we analyzed the expression of specific receptors (CCR) on BAL cells. The proportion of CCR-expressing BAL cells was assessed by flow cytometry.We demonstrated that MIP3-β/CCL19, MIP3-α/CCL20, MDC/CCL22 levels at 6 months post-transplant significantly predicted BOS onset. In addition, the temporal behavior of these factors resulted significantly different in pre-BOS patients as compared to stable LTR. Finally the expression of CCR was documented on BAL lymphocytes and macrophages, and, in some cases, their expression was found to vary between the two groups.Within the complexity of the chemokine network, these three CCL factors could play an additive role in the pathogenesis of the inflammatory process leading to bronchiolar fibro-obliteration.

Pepsin, a Biomarker of Gastric Aspiration in Lung Allografts

Human lung transplantation is a therapeutic option for selected patients with advanced cardiopulmonary disease, but long-term survival is limited by chronic rejection. Persistent acute rejection and gastric aspiration have been implicated as risk factors but there is little or no evidence to date that they are associated. We have tested the hypothesis that pepsin, a marker of gastric aspiration, is present in lung transplant recipients, and that high levels are associated with biopsy-diagnosed acute rejection and/or bronchiolitis obliterans syndrome. Levels of bronchoalveolar lavage (BAL) pepsin were measured by ELISA in 36 lung transplant recipients, 4 normal volunteers, and 17 subjects with unexplained chronic cough. Our primary finding was that, compared with control subjects, BAL pepsin levels were elevated in stable lung transplant recipients, subjects with acute rejection, and subjects with bronchiolitis obliterans syndrome. Our secondary finding was that the highest levels were found in recipients with acute vascular rejection grade > or = A2 (median, 11.2; range, 5.4 - 51.7 ng/ml; normal median, 1.1; range, 0-2.3 ng/ml; p = 0.004). We have shown that elevated levels of pepsin, a biomarker of gastric aspiration, are consistently identified in the BAL of lung allografts. The highest levels were seen in patients with > or = grade A2 acute rejection. This provides further evidence supporting the possible role of aspiration in the development of overall allograft injury.

Pharmacokinetics of Mycophenolic Acid and Its Glucuronidated Metabolites in Stable Lung Transplant Recipients

Mycophenolic acid (MPA) is the active metabolite of mycophenolate mofetil, an immunosuppressive agent commonly used in solid organ transplantation. MPA is metabolized to the inactive metabolite 7-O-mycophenolic acid glucuronide (MPAG) and the active metabolite acyl glucuronide (AcMPAG). Pharmacokinetic profiling of MPA by determining AUC is a tool for determining drug exposure. Many studies, conducted primarily in kidney and some heart and liver transplant recipients, have shown wide interpatient variability in MPA's pharmacokinetic parameters. There have been few studies in the lung transplant group and, even though the lung is not involved in drug elimination, these patients may have different MPA pharmacokinetic characteristics. To characterize the pharmacokinetic parameters and metabolic ratios of MPA in stable adult lung transplant recipients. In an open-label manner, lung transplant recipients were recruited. Blood samples were obtained at 0, 0.3, 0.6, 1, 1.5, 2, 4, 6, 8, 10, and 12 hours postdose. Plasma was separated and acidified for drug concentration analysis (MPA, MPAG, AcMPAG) by an HPLC-ultraviolet detection method. Conventional pharmacokinetic parameters were determined via noncompartmental methods. There was large interpatient variability in all pharmacokinetic parameters of MPA, MPAG, and AcMPAG. Similar variability was observed after stratifying patients into concomitant medication groups: cyclosporine and tacrolimus. There was a trend for the tacrolimus group to have a higher dose-normalized AUC, higher AUC, lower apparent clearance, and lower AUC ratio of AcMPAG/MPA compared with the cyclosporine group. In addition, the cyclosporine group had a lower minimum concentration and higher AUC ratio of MPAG/MPA than did the tacrolimus group (p < 0.05). Because of the large interpatient variability in the pharmacokinetic parameters of MPA, MPAG, and AcMPAG, therapeutic drug monitoring of MPA and its metabolites in lung transplant recipients may be beneficial.

Peripheral CD4+ CD25+ Treg cell expansion in lung transplant recipients is not affected by calcineurin inhibitors

CD4+CD25+ regulatory T (Treg) cells have been shown to play a role in allograft tolerance and their peripheral counts vary according to the degree of graft acceptance in lung transplant recipients (LTR). Recent studies demonstrate that certain drugs might modulate generation, expansion and activity of Treg cells. Aim of this study was to evaluate the effect of therapeutic regimens used in our institution on peripheral CD4+CD25 highCD69− Treg cell numbers in a group of 51 LTR with stable clinical conditions. They were treated with standard immunosuppression: calcineurin inhibitor (CNI) + azathioprine (AZA) + steroids ( n = 28) or with CNI + mycophenolate mofetil (MMF) + steroids ( n = 11) or with CNI + steroids ( n = 12). These stable LTR were compared with age-matched healthy controls ( n = 35) and with 19 LTR who developed bronchiolitis obliterans syndrome (BOS) and were treated analogously. Stable LTR showed higher peripheral Treg cell counts with respect to age-matched healthy controls (59.9 ± 31.8/μl versus 42.1 ± 16.9/μl, respectively; p < 0.05). This increase was detectable in all patients treated with CNI either in association with AZA or MMF. During these treatments a significant expansion of Treg cell counts was detectable during acute rejection (AR) episodes (86.03 ± 26.6/μl during AR versus 36.34 ± 7.6 before AR; p < 0,05). Moreover, the development of BOS was associated to a significant decrease of Treg cell counts irrespective to the immunosuppressive regimen used. In conclusion, therapeutic regimens based on CNI seem to allow a certain degree of peripheral Treg cell expansion in stable LTR.

Tacrolimus Pharmacokinetics and Dose Monitoring After Lung Transplantation for Cystic Fibrosis and Other Conditions

In cystic fibrosis (CF), absorption of tacrolimus through the gastrointestinal tract may be impaired due to fat malabsorption. The aim of this pilot study was to compare tacrolimus pharmacokinetics and inter- and intrasubject variability of exposure in stable lung transplant recipients with and without CF, and to determine the best single-time predictors of exposure. The study included 11 lung transplant recipients with CF and 11 without CF who received tacrolimus twice daily. Blood samples were obtained predose and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8 and 12 h postdose on 3 separate days within 1 week. Tacrolimus pharmacokinetics and inter- and intrasubject variability of exposure were similar in the two groups, though exposure-per-milligram-dose was approximately 50% lower in CF patients. Tacrolimus trough concentration did not accurately predict the area under the concentration curve (AUC(0-12)), but the concentration measured 3 h postdose (C(3)) was tightly correlated with the AUC(0-12) in both CF (r(2)= 0.86) and non-CF (r(2)= 0.92) patients. In summary, patients with CF have a higher tacrolimus oral clearance, but nonsignificant differences in short-term inter- and intrasubject variability of exposure compared to patients without CF. C(3) is tightly correlated with AUC(0-12) in lung transplant recipients with and without CF.

Early Changes in Basement Membrane Thickness in Airway Walls Post-Lung Transplantation

Identification of early histopathologic markers of future bronchiolitis obliterans syndrome (BOS) may enable preemptive targeted intervention, delaying and perhaps preventing the onset of BOS. This study aimed to determine if early changes in airway epithelial basement membrane thickness predisposes transplant recipients to the subsequent development of BOS. Basement membrane thickness was measured in serial endobronchial biopsies taken from 29 initially stable lung transplant recipients (sLTR) recruited 148 +/- 80 days post-transplant and followed for 3 years. A further 2 years of clinical follow-up was undertaken without biopsies to follow lung function and define ultimate BOS status. Nine healthy subjects (non-atopic, non-asthmatic) were recruited as controls. Sections of paraffinized endobronchial biopsies were stained for collagen type I immunohistochemically, and basement membrane thickness was assessed by computer image analysis. BOS developed in 21 of 29 patients in the 5 years of follow-up, 16 of which had endobronchial biopsies available for analysis before BOS developed (ever-BOS). The first endobronchial biopsies showed increased BMT in the combined sLTR and ever-BOS patients compared with the controls. This initial increase in basement membrane thickness resolved to normal levels within 300 days post-transplant, with a strong negative correlation (r2 = 0.424, p < 0.0001) of basement membrane thickness vs time. Paradoxically, the sLTR tended to have the greatest basement membrane thickness at baseline. An initial increase in basement membrane thickness is seen in the airway walls of all lung transplant recipients. This is transient and does not appear to be a risk factor for the subsequent development of BOS in lung allograft recipients.

Airway Vascular Changes After Lung Transplant: Potential Contribution to the Pathophysiology of Bronchiolitis Obliterans Syndrome

Bronchiolitis obliterans syndrome (BOS) remains the primary factor limiting successful lung transplantation. In asthma and lung transplantation BOS-increased sub-mucosal vascularity has been shown to contribute to airflow limitation. Vascularity has 2 components: sprouting angiogenesis (more vessels) and microvascular enlargement (larger vessels). We hypothesized that the lack of a reanastomosed bronchial arterial blood supply at the time of transplant might stimulate angiogenesis and be a risk factor for subsequent BOS. Twenty-seven initially stable lung transplant recipients (BOS 0) were recruited at 148 +/- 80 days post-transplant and underwent clinical and bronchoscopic longitudinal follow-up for at least 3 years. Eight remained stable and BOS developed in 19. Nine normal controls were also recruited. Airway vasculature was examined immunohistochemically in endobronchial biopsy (EBB) specimens with collagen IV antibody, quantified by computer image analysis, and expressed as average vessel size, vessel number, and overall vascularity. The effects of demographic, clinical, bronchoalveolar lavage (BAL), and EBB variables on airway vasculature were analyzed in a multivariate model. No significant differences in airway vascularity were found between stable and BOS lung transplant recipients cross-sectionally or longitudinally. However, both lung transplant groups at baseline showed significantly greater airway vascularity compared with normal controls (p < .05). Multivariate analysis suggested that the percentage of BAL CD3+ cells and acute rejection are the most influential variables on airway vasculature. This study suggests early and persistent airway vasculature changes occur in lung transplant recipients, mainly manifested as microvascular enlargement. Potentially this baseline change contributes to airway obstruction and also puts all lung transplant recipients at risk for further exponential loss of airway caliber with any subsequent airway inflammatory insult.

A Descriptive Study of Small Airway Reticular Basement Membrane Thickening in Clinically Stable Lung Transplant Recipients

Chronic rejection functionally manifested by fixed airflow limitation, bronchiolitis obliterans syndrome (BOS), is a major problem for all lung allograft programs. The inclusion of a pre-BOS category (BOS(0 approximately p)) in the newly revised guidelines, recognizes the potential importance of early changes. We tested the hypothesis that small airway reticular basement membrane thickening exists even in clinically stable lung transplant recipients with some evidence of inflammation but who are BOS-free. A bronchoscopic study was performed on 30 clinically stable lung allograft recipients at >/=3 months post-allograft, who were BOS-free but with some evidence of airway inflammation indicated by a pathologic diagnosis of lymphocytic bronchiolitis or raised exhaled nitric oxide (NO). After baseline physiologic assessment, small airway reticular basement membrane (Rbm) thickening was quantified in transbronchial biopsy (TBB) using image analysis, with inflammation assessed by bronchoalveolar lavage (BAL) differential cell counts. Twenty-one patients had technically satisfactory measurements of Rbm thickness. We detected small airway Rbm thickening when compared with published data for control lung diseases. There was no correlation between Rbm thickening and lung function (forced expiratory volume in 1 second [FEV(1)] best post-operatively and Rbm r = -0.10, not significant). Our data suggest that airway remodeling can occur early in lung allografts and before development of airflow limitation and BOS. Longitudinal pathophysiologic studies are needed to elucidate potential relationships between airway inflammation, Rbm thickening and allograft failure. Airway biopsies would be of value in such studies.

Up-regulation of Interleukin-8, Interleukin-10, Monocyte Chemotactic Protein-1, and Monocyte Chemotactic Protein-3 in Peripheral Blood Monocytes in Stable Lung Transplant Recipients: Are Immunosuppression Regimens Working?

Alveolar macrophages are a major source of inflammatory cytokines and chemokines involved in the pathogenesis of lung transplant rejection and are derived from blood monocytes that migrate to the lung. Levels of monocyte cytokines and chemokines that may be relevant in transplant rejection have not previously been determined in transplant recipients. We hypothesized that production of these inflammatory mediators by blood monocytes may be up-regulated despite the use of potent immunosuppression therapy. To investigate this, whole blood from 9 stable lung transplant recipients and 12 control volunteers was stimulated with lipopolysaccharide in vitro, and intracellular chemokine and cytokine production were determined with multiparameter flow cytometry. Monocyte production of chemokines interleukin (IL)-8, monocyte chemotactic protein (MCP)-1, and MCP-3, and anti-inflammatory cytokine IL-10 were significantly increased in the lung transplant group, but IL-6, tumor necrosis factor-alpha, IL-1alpha, IL-12, macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta, and transforming growth factor-beta levels were unchanged. Because MCP-3 is a major chemoattractant for leukocytes to sites of antigenic challenge and is a natural ligand for MCP-1 receptor, this novel finding has important implications for the pathogenesis of lung transplant rejection. We now provide evidence that current immunosuppression protocols have a limited effect on monocyte inflammatory cytokine production and do not adequately suppress monocyte IL-8, MCP-1, and MCP-3 chemokine production. Drugs that modulate the action of these chemokines may improve current protocols for reducing graft rejection. Intracellular chemokine and cytokine analysis with flow cytometry may be a more accurate indicator of immunosuppression than drug levels in these patients.

Pharmacokinetics of mycophenolate and its glucuronidated metabolites in stable lung transplant recipients

Pharmacokinetics of mycophenolate and its glucuronidated metabolites in stable lung transplant recipients

Epithelial to mesenchymal transition in clinically stable lung transplant recipients

Epithelial to mesenchymal transition in clinically stable lung transplant recipients

A multicenter trial to investigate the efficacy and safety of everolimus versus Azathioprine in stable Lung Transplant Recipients (LTR) -24 months results

A multicenter trial to investigate the efficacy and safety of everolimus versus Azathioprine in stable Lung Transplant Recipients (LTR) -24 months results

Determinants of Health Utility in Lung and Heart-Lung Transplant Recipients

Bronchiolitis obliterans syndrome (BOS) is associated with poor health-related quality of life (HRQL) following lung and heart-lung transplantation, but few other determinants of HRQL have been described. We performed a cross-sectional study of standard gamble utility, a preference-based measure of HRQL, in 90 stable lung and heart-lung transplant recipients. We used bivariate analyses and multiple linear regression to evaluate associations between utility scores and candidate predictor variables including age, sex, indication for transplant (obstructive, interstitial, suppurative and pulmonary vascular diseases), transplant type (bilateral, single and heart-lung), time since transplant, body mass index, arterial PO(2), creatinine clearance, number of medications, presence of BOS and risk-attitude score. The median utility was 0.88 (inter-quartile range: 0.50-0.99). Multivariable analysis showed that female sex, absence of BOS, better renal function and longer time since transplantation were associated with higher utility scores, and that there were utility differences across diagnostic groups. Although BOS is a major determinant of utility following lung and heart-lung transplantation, other demographic and clinical factors are also associated with significant differences in this measure of HRQL.

Reticular basement membrane thickening in airways of lung transplant recipients is not affected by inhaled corticosteroids

Chronic rejection is a major problem for all lung transplant programmes, which is functionally manifested by fixed airflow limitation, Bronchiolitis Obliterans Syndrome (BOS). The inclusion of a Pre-BOS category, BOS(0 approximately p), in newly revised guidelines, recognizes the potential importance of early changes. We have previously demonstrated reticular basement membrane (Rbm) thickening in clinically stable lung transplant recipients free from BOS. The present study extends this, testing the hypothesis that inhaled corticosteroid (ICS) therapy will lead to a decrease in Rbm thickness in lung transplant recipients. A parallel group, bronchoscopic intervention study of clinically stable lung allograft recipients, free from BOS, but with evidence of airway inflammation. Following baseline assessment of Rbm thickening, subjects were randomized to 3 months of either chlorofluorocarbon-driven beclomethasone diproprionate (BDP) 400 microg b.i.d., or a formulation designed to yield at least an equivalent dose, hydrofluoroalkane-driven BDP, 200 microg b.i.d. Three months treatment with a moderate dose of ICS, including a formulation designed for preferential small airway deposition, had no effect on Rbm thickening (13+/-3 vs. 14+/-5 microm post-ICS). Our data would suggest that airway remodelling can occur early in lung allografts and is not affected by moderate dose ICS therapy. Longitudinal studies are required to describe the pathophysiological processes involved in BOS, and specifically to elucidate potential relationships between airway remodelling, airflow obstruction and allograft failure.

Effect of inhaled fluticasone propionate on BAL TGF-β 1 and bFGF concentrations in clinically stable lung transplant recipients

Background Inhaled fluticasone propionate (FP) therapy decreases inflammation and sub-basement membrane thickness in asthmatic airways. Bronchiolitis obliterans syndrome (BOS) in lung transplant recipients (LTRs) involves progressive airway fibrosis and obliteration. Therefore, augmented immunosuppression may be of some benefit in treating BOS. In this study, we examined the effect of 3 months of treatment with high-dose inhaled FP on the concentrations of 2 fibrogenic factors, transforming growth factor (TGF)–β 1 and beta fibrogenic growth factor (bFGF) in bronchoalveolar lavage (BAL) fluid from clinically stable LTRs. Methods We conducted a randomized, double-blind, placebo-controlled, parallel group study with inhaled FP (750 μg, twice/day for 3 months) in 28 LTRs (15 FP and 13 placebo). We recruited 23 healthy controls. We performed spirometry, bronchoscopy, and bronchoalveolar lavage procedures before treatment and after 3 months of treatment. We used commercially available enzyme-linked immunosorbent assay kits to measure BAL fluid TGF-β 1 and bFGF concentrations. Results In LTRs before treatment, BAL TGF-β 1 concentrations (but not bFGF concentrations), total cell counts, and neutrophil percentage increased compared with controls ( p < 0.05). We found no significant differences between FP and placebo groups at baseline measurements. After treatment, BAL TGF-β 1 concentrations significantly increased in the FP group ( p = 0.03), but we found no difference between FP and placebo groups; BAL bFGF concentrations increased during treatment in both groups compared with controls ( p < 0.05), but not significantly within either patient group ( p > 0.05). We found a reverse correlation between forced expiratory volume in 1 second (FEV 1) and BAL TGF-β 1 concentration in the FP group ( r = −0.53, p = 0.04), and between FEV 1 and BAL TGF-β 1 concentration in the placebo group ( r = −0.74, p = 0.004). Multivariable analysis indicated no significant independent effects of inhaled FP in either BAL TGF-β 1 or bFGF concentrations. Conclusions Bronchoalveolar fluid TGF-β 1 concentrations increased in LTRs after transplantation and may correlate with the decrease in lung function. Inhaled FP added to conventional immunosuppression had no effect on TGF-β 1 or bFGF production in BAL fluid.

A multicenter trial to investigate the efficacy and safety of everolimus versus azathioprine in stable lung transplant recipients (LTR) –12 months results

A multicenter trial to investigate the efficacy and safety of everolimus versus azathioprine in stable lung transplant recipients (LTR) –12 months results

Two-year results of an international, randomized, double-blind study of everolimus (RAD) vs azathioprine to inhibit the decline of pulmonary function in stable lung transplant recipients

Two-year results of an international, randomized, double-blind study of everolimus (RAD) vs azathioprine to inhibit the decline of pulmonary function in stable lung transplant recipients

Therapeutic drug monotoring of everolimus (RAD) may be beneficial in stable lung transplant recipients

Purpose: The potential utility of therapeutic drug monitoring (TDM) in optimizing the use of the proliferation signal inhibitor everolimus was examined in a large double-blind trial of 213 stable lung transplant recipients comparing everolimus (3 mg/day) vs azathioprine (AZA, 1-3 mg/kg/day), in combination with Neoral (CsA microemulsion) and corticosteroids. 12-month efficacy results showed that everolimus was statistically significantly superior over AZA. The purpose of this investigation was to assess the future role of everolimus TDM in this population.

Co-Localisation of Mmp-9 (Gelatinase B) with Airway Neutrophils in Stable Lung Transplant Recipients — a Potential Role in Bronchiolitis Obliterans Syndrome

Co-Localisation of Mmp-9 (Gelatinase B) with Airway Neutrophils in Stable Lung Transplant Recipients — a Potential Role in Bronchiolitis Obliterans Syndrome