Lymphocytic bronchitis/bronchiolitis in lung allograft recipients

Esophageal Evaluation for Patients Undergoing Lung Transplant Evaluation: What Should We Do for Evaluation and Management

Lung transplantation is a high-risk, but lifesaving, procedure for patients with end-stage lung disease. Although 1-year survival is high, long-term survival is not nearly as high, due mainly to acute and chronic rejection. Bronchiolitis obliterans syndrome is the most common type of chronic rejection and often leads to poor outcomes. For this reason, esophageal testing in the lung transplant population has become a major issue, and this article discusses the evidence behind esophageal testing, the importance of esophageal dysmotility gastroesophageal reflux disease, both acidic and nonacidic reflux, and aspiration and the treatment of these findings.

Modulation of NLRP3 Inflammasome through Formyl Peptide Receptor 1 (Fpr-1) Pathway as a New Therapeutic Target in Bronchiolitis Obliterans Syndrome

Chronic rejection is the major leading cause of morbidity and mortality after lung transplantation. Bronchiolitis obliterans syndrome (BOS), a fibroproliferative disorder of the small airways, is the main manifestation of chronic lung allograft rejection. We investigated, using transgenic mice, the mechanisms through which the deficiency of IL-1β/IL-18, Casp-1, or Fpr-1 genes could be protective in an experimental model of BOS, induced in mice by allogeneic heterotopic tracheal transplantation. Fpr-1 KO mice showed a marked reduction in histological markers of BOS and of mast cell numbers compared to other groups. Molecular analyses indicated that the absence of the Fpr-1 gene was able to decrease NF-κB nuclear translocation and modulate NLRP3 inflammasome signaling and the mitogen-activated protein kinase (MAPK) pathway in a more significant way compared to other groups. Additionally, Fpr-1 gene deletion caused a reduction in resistance to the apoptosis, assessed by the TUNEL assay. Immunohistochemical analyses indicated changes in nitrotyrosine, PARP, VEGF, and TGF-β expression associated with the pathology, which were reduced in the absence of the Fpr1 gene more so than by the deletion of IL-1β/IL-18 and Casp-1. We underline the importance of the NLRP3 inflammasome and the pathogenic role of Fpr-1 in experimental models of BOS, which is the result of the modulation of immune cell recruitment together with the modulation of local cellular activation, suggesting this gene as a new target in the control of the pathologic features of BOS.

Serum Amyloid A in lung transplantation

Background:

Serum Amyloid A (SAA) is an acute phase protein and we analyzed its concentrations in lung transplantated patients (LTX).

Methods:

26 LTX patients (58.6 ± 11 years) and 11 healthy controls (55 ± 11.3 years). Three groups of LTX patients: acute rejection (AR, 7) bronchiolitis obliterans syndrome (BOS, 3), acute infection (INF, 9) and stable patients (NEG, 7).

Results:

In LTX patients SAA concentrations were significantly increased, particularly in AR and INF. In LTX-AR patients were observed a correlation between SAA levels and peripheral CD4+ lymphocyte percentage (r=0.9, p<0.01) and a reverse correlation with FVC percentages (r -0.94, p=0.01).

Conclusions:

SAA may represent a potential biomarker of LTX acute complications, with a prognostic value in AR. (Sarcoidosis Vasc Diffuse Lung Dis 2020; 37 (1): 2-7)

Bronchiolitis obliterans syndrome and restrictive allograft syndrome after lung transplantation: why are there two distinct forms of chronic lung allograft dysfunction?

Bronchiolitis obliterans syndrome (BOS) had been considered to be the representative form of chronic rejection or chronic lung allograft dysfunction (CLAD) after lung transplantation. In BOS, small airways are affected by chronic inflammation and obliterative fibrosis, whereas peripheral lung tissue remains relatively intact. However, recognition of another form of CLAD involving multiple tissue compartments in the lung, termed restrictive allograft syndrome (RAS), raised a fundamental question: why there are two phenotypes of CLAD? Increasing clinical and experimental data suggest that RAS may be a prototype of chronic rejection after lung transplantation involving both cellular and antibody-mediated alloimmune responses. Some cases of RAS are also induced by fulminant general inflammation in lung allografts. However, BOS involves alloimmune responses and the airway-centered disease process can be explained by multiple mechanisms such as external alloimmune-independent stimuli (such as infection, aspiration and air pollution), exposure of airway-specific autoantigens and airway ischemia. Localization of immune responses in different anatomical compartments in different phenotypes of CLAD might be associated with lymphoid neogenesis or the de novo formation of lymphoid tissue in lung allografts. Better understanding of distinct mechanisms of BOS and RAS will facilitate the development of effective preventive and therapeutic strategies of CLAD.

Bone Marrow-derived Mesenchymal Stem Cells and Chronic Allograft Disease in a Bronchiolitis Obliterans Animal Model

INTRODUCTION

Bronchiolitis obliterans (BO) is the most common expression of chronic allograft dysfunction in lung transplantation. Moreover, BO represents the major cause of death in the long-term after this procedure. On the other hand, mesenchymal stem cells have been tested in animal models of BO aiming to interfere in its development. The aim of this experimental study is to explore the role of bone-marrow derived stem cells (BMSCs) as a preventive intervention of BO occurrence.

MATERIALS AND METHODS

This an experimental randomized study. A bronchiolitis obliterans animal model in rats was reproduced: heterotopical tracheal transplant model in lung parenchyma. Five of these animals were used as control group. After setting up the model, individuals were divided in 3 groups of treatment (n=15), in which BMSCs were administered in 3 different time points after the tracheal transplant (tracheal transplantation and BMSCs administration occurred the same day, group G0; after 7 days, group G7; after 14 days, group G14. In addition, within each group, BMSCs were administered through 3 different routes: endotracheally, endovascular and topically in the lung parenchyma). Animals were sacrificed at 21 days. Histology, fluorescence in situ hybridization and immunohistochemistry techniques were performed for identifying stem cells.

RESULTS

Compared to control group, animals receiving BMSCs showed large neovessels in a loose fibrous matrix. Group G7 showed less fibrosis (p<0.033) and edema (p<0.028). Moreover, G7 animals receiving stem cells endotracheally showed no fibrosis (p<0.008). Alveolar-like patches of tissue were observed among all groups (53.4%, 46.7% and 40% in G0, G7 and G14 respectively), consisting of cells expressing both stem and alveolar cells biomarkers.

CONCLUSION

BMSCs modify the course of bronchiolitis obliterans and differentiate into alveolar cells. Endotracheal administration of BMSCs 7 days after the heterotopical tracheal transplant might be considered an effective way to prevent BO in this animal model.

COPD and lung cancer in patients with pemphigus- a population based study

BACKGROUND

Recent evidence indicates that autoimmunity may contribute to the pathogenesis of chronic obstructive pulmonary disease (COPD). COPD was observed at higher frequency in patients with several autoimmune diseases. The association between pemphigus and COPD has not been evaluated in the past.

OBJECTIVES

To study the association between pemphigus and COPD using a large-scale real-life computerized database.

METHODS

A cross-sectional study was conducted comparing pemphigus patients with age-, sex- and ethnicity-matched control subjects regarding the prevalence of COPD and lung cancer. Chi-square and t-tests were used for bivariate analysis, and logistic regression model was used for multivariate analysis. The study was performed utilizing the computerized database of Clalit Health Services ensuring 4.4 million subjects.

RESULTS

A total of 1985 pemphigus patients and 9874 controls were included in the study. The prevalence of COPD was greater in patients with pemphigus as compared to the control group (13.4% vs. 10.1%, respectively; P < 0.001). In a multivariate analysis adjusting for smoking and other confounding factors, pemphigus was significantly associated with COPD (OR, 1.312-1. 5) but not with lung cancer. Study findings were robust to sensitivity analysis that included patients under pemphigus-specific treatments.

CONCLUSIONS

A significant association was found between COPD and pemphigus. Physicians treating patients with pemphigus might be aware of this possible association. This observation may further support the hypothesis that COPD has an autoimmune component.

The prognostic importance of CXCR3 chemokine during organizing pneumonia on the risk of chronic lung allograft dysfunction after lung transplantation

RATIONALE

Since the pathogenesis of chronic lung allograft dysfunction (CLAD) remains poorly defined with no known effective therapies, the identification and study of key events which increase CLAD risk is a critical step towards improving outcomes. We hypothesized that bronchoalveolar lavage fluid (BALF) CXCR3 ligand concentrations would be augmented during organizing pneumonia (OP) and that episodes of OP with marked chemokine elevations would be associated with significantly higher CLAD risk.

METHODS

All transbronchial biopsies (TBBX) from patients who received lung transplantation between 2000 to 2010 were reviewed. BALF concentrations of the CXCR3 ligands (CXCL9, CXCL10 and CXCL11) were compared between episodes of OP and "healthy" biopsies using linear mixed-effects models. The association between CXCR3 ligand concentrations during OP and CLAD risk was evaluated using proportional hazards models with time-dependent covariates.

RESULTS

There were 1894 bronchoscopies with TBBX evaluated from 441 lung transplant recipients with 169 (9%) episodes of OP and 907 (49%) non-OP histopathologic injuries. 62 (37%) episodes of OP were observed during routine surveillance bronchoscopy. Eight hundred thirty-eight (44%) TBBXs had no histopathology and were classified as "healthy" biopsies. There were marked elevations in BALF CXCR3 ligand concentrations during OP compared with "healthy" biopsies. In multivariable models adjusted for other injury patterns, OP did not significantly increase the risk of CLAD when BAL CXCR3 chemokine concentrations were not taken into account. However, OP with elevated CXCR3 ligands markedly increased CLAD risk in a dose-response manner. An episode of OP with CXCR3 concentrations greater than the 25th, 50th and 75th percentiles had HRs for CLAD of 1.5 (95% CI 1.0-2.3), 1.9 (95% CI 1.2-2.8) and 2.2 (95% CI 1.4-3.4), respectively.

CONCLUSIONS

This study identifies OP, a relatively uncommon histopathologic finding after lung transplantation, as a major risk factor for CLAD development when considered in the context of increased allograft expression of interferon-γ inducible ELR- CXC chemokines. We further demonstrate for the first time, the prognostic importance of BALF CXCR3 ligand concentrations during OP on subsequent CLAD risk.

Impact of Allograft Injury Time of Onset on the Development of Chronic Lung Allograft Dysfunction After Lung Transplantation

The impact of allograft injury time of onset on the risk of chronic lung allograft dysfunction (CLAD) remains unknown. We hypothesized that episodes of late-onset (≥6 months) allograft injury would produce an augmented CXCR3/ligand immune response, leading to increased CLAD. In a retrospective single-center study, 1894 transbronchial biopsy samples from 441 lung transplant recipients were reviewed for the presence of acute rejection (AR), lymphocytic bronchiolitis (LB), diffuse alveolar damage (DAD), and organizing pneumonia (OP). The association between the time of onset of each injury pattern and CLAD was assessed by using multivariable Cox models with time-dependent covariates. Bronchoalveolar lavage (BAL) CXCR3 ligand concentrations were compared between early- and late-onset injury patterns using linear mixed-effects models. Late-onset DAD and OP were strongly associated with CLAD: adjusted hazard ratio 2.8 (95% confidence interval 1.5-5.3) and 2.0 (1.1-3.4), respectively. The early-onset form of these injury patterns did not increase CLAD risk. Late-onset LB and acute rejection (AR) predicted CLAD in univariable models but lost significance after multivariable adjustment for late DAD and OP. AR was the only early-onset injury pattern associated with CLAD development. Elevated BAL CXCR3 ligand concentrations during late-onset allograft injury parallel the increase in CLAD risk and support our hypothesis that late allograft injuries result in a more profound CXCR3/ligand immune response.

Lung Transplantation: The State of the Airways

CONTEXT

Lung transplantation has become a viable option for definitive treatment of several end-stage lung diseases for which there are no other options available. However, long-term survival continues to be limited by chronic lung allograft dysfunction, which primarily affects the airways.

OBJECTIVE

To highlight the complications occurring mainly in the airways of the lung transplant recipient from the early to late posttransplant periods.

DATA SOURCES

Review literature focusing on the airways in patients with lung transplants and clinical experience of the authors.

CONCLUSIONS

Postsurgical complications and infections of the airways have decreased because of better techniques and management. Acute cellular rejection of the airways can be distinguished from infection pathologically and on cultures. Separating small from large airways need not be an issue because both are risk factors for bronchiolitis obliterans. Grading of airway rejection needs to be standardized. Chronic lung allograft dysfunction consists of both bronchiolitis obliterans and restrictive allograft syndrome, neither of which can be treated very effectively at present.

Adult bronchiolitis--a clinical and pathological interpretative classification

INTRODUCTION

Bronchiolitis is a heterogeneous group of diseases of an inflammatory nature, centered on small conducting airways and often associated with other pulmonary disorders. No single classification scheme for bronchiolar diseases has been widely accepted. In this retrospective study, it was decided to apply a new clinical and pathological interpretative classification.

OBJECTIVES

To propose a new clinical and pathological interpretative classification for adult bronchiolitis, based on statistical analysis of a population of 193 patients with histopathological diagnosis of bronchiolitis.

MATERIALS AND METHODS

A retrospective study analyzed the epidemiological characteristics, co-morbidities and radiological findings present in a group of patients with histopathological diagnosis of bronchiolitis.

RESULTS

This trial involved 193 cases collected over a period of eleven years; 48 (24.9%) patients had simultaneous pulmonary disease; non-pulmonary diseases, such as cardiovascular diseases, type II Diabetes mellitus and dyslipidemia were present in 57 cases. The image study was extremely important in order to integrate clinical and pathological aspects. In this study respiratory bronchiolitis related to smoking dominated. The radiological findings confirmed the secondary nature of the histopathological features, with prevalence of ground-glass patterns, pneumothorax and patterns of interstitial involvement, as described in the literature. It was also verified that clinical behavior of different forms of bronchiolitis was important to distinguish the various types, since they could progress without typical anatomopathological aspects.

CONCLUSION

This trial showed that the vast majority of diagnosis obtained corresponded to bronchiolitis as secondary to pulmonary pathology. In most cases, morphological findings had to be complemented with clinical and radiological characteristics, in order to obtain the final diagnosis.

Azithromycin and the treatment of lymphocytic airway inflammation after lung transplantation

Lymphocytic airway inflammation is a major risk factor for chronic lung allograft dysfunction, for which there is no established treatment. We investigated whether azithromycin could control lymphocytic airway inflammation and improve allograft function. Fifteen lung transplant recipients demonstrating acute allograft dysfunction due to isolated lymphocytic airway inflammation were prospectively treated with azithromycin for at least 6 months (NCT01109160). Spirometry (FVC, FEV1 , FEF25-75 , Tiffeneau index) and FeNO were assessed before and up to 12 months after initiation of azithromycin. Radiologic features, local inflammation assessed on airway biopsy (rejection score, IL-17(+)  cells/mm(2) lamina propria) and broncho-alveolar lavage fluid (total and differential cell counts, chemokine and cytokine levels); as well as systemic C-reactive protein levels were compared between baseline and after 3 months of treatment. Airflow improved and FeNO decreased to baseline levels after 1 month of azithromycin and were sustained thereafter. After 3 months of treatment, radiologic abnormalities, submucosal cellular inflammation, lavage protein levels of IL-1β, IL-8/CXCL-8, IP-10/CXCL-10, RANTES/CCL5, MIP1-α/CCL3, MIP-1β/CCL4, Eotaxin, PDGF-BB, total cell count, neutrophils and eosinophils, as well as plasma C-reactive protein levels all significantly decreased compared to baseline (p < 0.05). Administration of azithromycin was associated with suppression of posttransplant lymphocytic airway inflammation and clinical improvement in lung allograft function.

Update on Bronchiolitis Obliterans Syndrome in Lung Transplantation

Lung transplantation has become an important therapeutic option for patients with end-stage organ dysfunction; however, its clinical usefulness has been limited by the relatively early onset of chronic allograft dysfunction and progressive clinical decline. Obliterative bronchiolitis is characterized histologically by luminal fibrosis of the respiratory bronchioles and clinically by bronchiolitis obliterans syndrome (BOS) which is defined by a measured decline in lung function based on forced expiratory volume (FEV₁). Since its earliest description, a number of risk factors have been associated with the development of BOS, including acute rejection, lymphocytic bronchiolitis, primary graft dysfunction, infection, donor specific antibodies, and gastroesophageal reflux disease. However, despite this broadened understanding, the pathogenesis underlying BOS remains poorly understood and once begun, there are relatively few treatment options to battle the progressive deterioration in lung function.

At last: classification of human mammary cells elucidates breast cancer origins

Current breast cancer classification systems are based on molecular evaluation of tumor receptor status and do not account for distinct morphological phenotypes. In other types of cancer, taxonomy based on normal cell phenotypes has been extremely useful for diagnosis and treatment strategies. In this issue of the JCI, Santagata and colleagues developed a breast cancer classification scheme based on characterization of healthy mammary cells. Reclassification of breast cancer cells and breast cancer tissue microarrays with this system correlated with prognosis better than the standard receptor status designation. This scheme provides a major advance toward our understanding of the origin of the cells in the breast and breast cancers.

CXCR3 ligands are associated with the continuum of diffuse alveolar damage to chronic lung allograft dysfunction

RATIONALE

After lung transplantation, insults to the allograft generally result in one of four histopathologic patterns of injury: (1) acute rejection, (2) lymphocytic bronchiolitis, (3) organizing pneumonia, and (4) diffuse alveolar damage (DAD). We hypothesized that DAD, the most severe form of acute lung injury, would lead to the highest risk of chronic lung allograft dysfunction (CLAD) and that a type I immune response would mediate this process.

OBJECTIVES

Determine whether DAD is associated with CLAD and explore the potential role of CXCR3/ligand biology.

METHODS

Transbronchial biopsies from all lung transplant recipients were reviewed. The association between the four injury patterns and subsequent outcomes were evaluated using proportional hazards models with time-dependent covariates. Bronchoalveolar lavage (BAL) concentrations of the CXCR3 ligands (CXCL9/MIG, CXCL10/IP10, and CXCL11/ITAC) were compared between allograft injury patterns and "healthy" biopsies using linear mixed-effects models. The effect of these chemokine alterations on CLAD risk was assessed using Cox models with serial BAL measurements as time-dependent covariates.

MEASUREMENTS AND MAIN RESULTS

There were 1,585 biopsies from 441 recipients with 62 episodes of DAD. An episode of DAD was associated with increased risk of CLAD (hazard ratio, 3.0; 95% confidence interval, 1.9-4.7) and death (hazard ratio, 2.3; 95% confidence interval, 1.7-3.0). There were marked elevations in BAL CXCR3 ligand concentrations during DAD. Furthermore, prolonged elevation of these chemokines in serial BAL fluid measurements predicted the development of CLAD.

CONCLUSIONS

DAD is associated with marked increases in the risk of CLAD and death after lung transplantation. This association may be mediated in part by an aberrant type I immune response involving CXCR3/ligands.

Expression of calcineurin activity after lung transplantation: a 2-year follow-up

The objective of this pharmacodynamic study was to longitudinally assess the activity of calcineurin during the first 2 years after lung transplantation. From March 2004 to October 2008, 107 patients were prospectively enrolled and their follow-up was performed until 2009. Calcineurin activity was measured in peripheral blood mononuclear cells. We report that calcineurin activity was linked to both acute and chronic rejection. An optimal activity for calcineurin with two thresholds was defined, and we found that the risk of rejection was higher when the enzyme activity was above the upper threshold of 102 pmol/mg/min or below the lower threshold of 12 pmol/mg/min. In addition, we report that the occurrence of malignancies and viral infections was significantly higher in patients displaying very low levels of calcineurin activity. Taken together, these findings suggest that the measurement of calcineurin activity may provide useful information for the management of the prevention therapy of patients receiving lung transplantation.

Five-year update on the mouse model of orthotopic lung transplantation: Scientific uses, tricks of the trade, and tips for success

It has been 5 years since our team reported the first successful model of orthotopic single lung transplantation in the mouse. There has been great demand for this technique due to the obvious experimental advantages the mouse offers over other large and small animal models of lung transplantation. These include the availability of mouse-specific reagents as well as knockout and transgenic technology. Our laboratory has utilized this mouse model to study both immunological and non-immunological mechanisms of lung transplant physiology while others have focused on models of chronic rejection. It is surprising that despite our initial publication in 2007 only few other laboratories have published data using this model. This is likely due to the technical complexity of the surgical technique and perioperative complications, which can limit recipient survival. As two of the authors (XL and WL) have a combined experience of over 2500 left and right single lung transplants, this review will summarize their experience and delineate tips and tricks necessary for successful transplantation. We will also describe technical advances made since the original description of the model.

Circulating fibrocytes correlate with bronchiolitis obliterans syndrome development after lung transplantation: a novel clinical biomarker

BACKGROUND

Development of bronchiolitis obliterans syndrome (BOS) after lung transplantation confers increased patient morbidity and mortality. Fibrocytes are circulating bone marrow-derived mesenchymal cell progenitors that influence tissue repair and fibrosis. Fibrocytes have been implicated in chronic pulmonary inflammatory processes. We investigated the correlation of circulating fibrocyte number with BOS development in lung transplant patients.

METHODS

We prospectively quantified circulating fibrocyte levels among lung transplant patients. Patients were stratified according to the development of BOS as indicated by predicted forced expiratory volume in 1 second. Fibrocyte activity was analyzed by flow cytometry (cluster of differentiation 45+, collagen 1+) in a blinded manner related to clinical presentation.

RESULTS

Thirty-nine patients (61.5% men) underwent double (33.3%), left (25.6%), or right (41.0%) lung transplantation. Average patient age was similar between BOS and non-BOS patients (58.3±3.9 vs 60.3±2.0 years, p=0.67). Chronic obstructive lung disease was the most common indication for lung transplantation (41.0%). Median forced expiratory volume in 1 second was lower among BOS patients compared with non-BOS patients (1.08 vs. 2.18 L/s, p=0.001). Importantly, circulating fibrocyte numbers were increased in BOS patients compared with non-BOS patients (8.91 vs 2.96×10(5) cells/mL, p=0.03) by flow cytometry and were incrementally increased with advancing BOS stage (p=0.02).

CONCLUSIONS

Increased circulating fibrocyte levels correlate with the development of BOS after lung transplantation and positively correlate with advancing BOS stage. Quantification of circulating fibrocytes could serve as a novel biomarker and possible therapeutic target for BOS development in lung transplant patients.

The controversial role of surveillance bronchoscopy after lung transplantation

PURPOSE OF REVIEW

Clinically mandated transbronchial biopsy is universally regarded as the most efficient tool to establish pathology in the allograft. However, the utility of surveillance transbronchial biopsy to facilitate early detection and treatment of acute pulmonary allograft rejection is a matter of current debate. The purpose of this review is to summarize the evidence for and against the performance of surveillance bronchoscopy postlung transplantation, to discuss the risk/benefit ratio and the application of this procedure in the individual patient.

RECENT FINDINGS

Detection of silent acute rejection of the pulmonary allograft remains an important benefit of surveillance bronchoscopy although definitive evidence for a positive impact on survival or prevention of development of the bronchiolitis syndrome (BOS) is yet to be demonstrated. Perhaps the wrong target has been the focus as new evidence suggests that high grade lymphocytic bronchiolitis is the important independent risk factor for the development of BOS and death after lung transplantation. Providing effective therapies for lymphocytic bronchiolitis can be developed there is now strong support for performance of surveillance transbronchial biopsy. Most studies attest to a low risk of severe complications.

SUMMARY

Surveillance bronchoscopy is useful to detect asymptomatic acute rejection but also to determine the presence and severity of lymphocytic bronchiolitis, which should be the new target of therapeutic endeavours. It is acknowledged that the true risk/benefit ratio of surveillance bronchoscopy may differ between programs so each case deserves individual consideration.

The role of intrapulmonary de novo lymphoid tissue in obliterative bronchiolitis after lung transplantation

Chronic rejection after lung transplantation is manifested as obliterative bronchiolitis (OB). The development of de novo lymphoid tissue (lymphoid neogenesis) may contribute to local immune responses in small airways. Compared with normal lungs, the lung tissue of 13 lung transplant recipients who developed OB demonstrated a significantly larger number of small, airway-associated, peripheral node addressin-positive (PNAd(+)) high endothelial venules (HEVs) unique to lymphoid tissue (p < 0.001). HEVs were most abundant in lesions of lymphocytic bronchiolitis and "active" OB infiltrated by lymphocytes compared with those of "inactive" OB. T cells in lymphocytic bronchiolitis and active OB were predominantly of the CD45RO(+)CCR7(-) effector memory phenotype. Similar lymphoid tissue was also observed in the rat lung after intrapulmonary transplantation of allograft trachea (Brown Norway (BN) to Lewis), but not after isograft transplantation. Subsequent orthotopic transplantation of the recipient Lewis lung containing a BN trachea into an F(1) (Lewis x BN) rat demonstrated stable homing of Lewis-derived T cells in the lung and their Ag-specific effector function against the secondary intrapulmonary BN trachea. In conclusion, we found de novo lymphoid tissue in the lung composed of effector memory T cells and HEVs but lacking delineated T cell and B cell zones. This de novo lymphoid tissue may play a critical role in chronic local immune responses after lung transplantation.

Quantitation of T lymphocytes in posttransplant transbronchial biopsies

The diagnostic role of immunohistochemical staining for T lymphocytes in grading acute airway rejection has not been fully explored. We examined 136 transbronchial biopsies from 52 lung transplant patients and 9 nontransplant controls. Transplant rejection was based on histologic assessment of perivascular (A) and bronchiolar (B) infiltrates. The clinical indication for the 136 allograft biopsies was routine surveillance (n = 72), decreased pulmonary function, rule out rejection (n = 36), suspect infection (n = 16), rule out obliterative bronchiolitis (n = 6), and persistent postoperative graft failure (n = 6). T lymphocytes were counted in bronchial mucosa per 100 bronchial epithelial cells, and in alveolar walls per square millimeters, after immunohistochemical staining with anti-CD3, CD4, and CD8. In controls, the mean alveolar wall CD3 cell count was 45 per square millimeter (95% confidence intervals, 30-52 per square millimeter) and the mean CD8 count was 15 per square millimeter (2-20 per square millimeter). In surveillance and negative patient biopsies, alveolar wall CD8 counts were significantly greater than controls (P = .03 and .02, respectively). Mean alveolar wall CD3 counts were significantly higher in type A rejection (88.7 +/- 12.9) than controls and negative biopsies (42 +/- 5.3, P < .001), but there was no difference compared to infections (119.7 +/- 22, P > .5). Mucosal CD3 cell counts were significantly higher in type B rejection (16.1 +/- 2.5) than controls and negative biopsies (1.5 +/- 0.4, P < .001), and also higher than infections (3.9 +/- 1.1, P < .001). In 7% of biopsies, T-cell staining identified perivascular circumferential infiltrates that were difficult to identify on routine stains, and in an additional 9% minor changes in grading were made after reviewing T-cell markers. Immunohistochemical staining may help in identifying perivascular infiltrates and demonstrates increased intraepithelial T-cells even in low-grade type B rejection. Type B rejection as assessed quantitatively is more specific than type A rejection in comparison to infection.

Late primary graft dysfunction after lung transplantation and bronchiolitis obliterans syndrome

Primary graft dysfunction (PGD) is a common early complication after lung transplantation. We conducted a retrospective cohort study of 334 recipients to evaluate the impact of PGD graded at 24, 48 and 72 h on the risk of bronchiolitis obliterans syndrome (BOS) development (stage 1) and progression (stages 2 and 3). We constructed multivariable Cox proportional hazards models to determine the risk of BOS attributable to PGD in the context of other potential risk factors including acute rejection, lymphocytic bronchitis and respiratory viral infections. All grades of PGD at all time points were significant risk factors for BOS development and progression independent of acute rejection, lymphocytic bronchitis and respiratory viral infections. Specifically, PGD grade 1 at T24 was associated with a relative risk of BOS stage 1 of 1.93, grade 2 with a relative risk of 2.29 and grade 3 with a relative risk of 3.31. Furthermore, this direct relationship between the severity of PGD and the risk of BOS persisted at all time points. We conclude that all grades of PGD at all time points are independent risk factors for BOS development and progression. Future strategies that might attenuate the severity of PGD may mitigate the risk of BOS.

Revision of the 1996 working formulation for the standardization of nomenclature in the diagnosis of lung rejection

In 1990, an international grading scheme for the grading of pulmonary allograft rejection was adopted by the International Society for Heart and Lung Transplantation (ISHLT) and was modified in 1995 by an expanded group of pathologists. The original and revised classifications have served the lung transplant community well, facilitating communication between transplant centers with regard to both patient management and research. In 2006, under the direction of the ISHLT, a multi-disciplinary review of the biopsy grading system was undertaken to update the scheme, address inconsistencies of use, and consider the current knowledge of antibody-mediated rejection in the lung. This article summarizes the revised consensus classification of lung allograft rejection. In brief, acute rejection is based on perivascular and interstitial mononuclear infiltrates, Grade A0 (none), Grade A1 (minimal), Grade A2 (mild), Grade A3 (moderate) and Grade A4 (severe), as previously. The revised (R) categories of small airways inflammation, lymphocytic bronchiolitis, are as follows: Grade B0 (none), Grade B1R (low grade, 1996, B1 and B2), Grade B2R (high grade, 1996, B3 and B4) and BX (ungradeable). Chronic rejection, obliterative bronchiolitis (Grade C), is described as present (C1) or absent (C0), without reference to presence of inflammatory activity. Chronic vascular rejection is unchanged as Grade D. Recommendations are made for the evaluation of antibody-mediated rejection, recognizing that this is a controversial entity in the lung, less well developed and understood than in other solid-organ grafts, and with no consensus reached on diagnostic features. Differential diagnoses of acute rejection, airway inflammation and chronic rejection are described and technical considerations revisited. This consensus revision of the working formulation was approved by the ISHLT board of directors in April 2007.

Microvascular destruction identifies murine allografts that cannot be rescued from airway fibrosis

Small airway fibrosis (bronchiolitis obliterans syndrome) is the primary obstacle to long-term survival following lung transplantation. Here, we show the importance of functional microvasculature in the prevention of epithelial loss and fibrosis due to rejection and for the first time, relate allograft microvascular injury and loss of tissue perfusion to immunotherapy-resistant rejection. To explore the role of alloimmune rejection and airway ischemia in the development of fibroproliferation, we used a murine orthotopic tracheal transplant model. We determined that transplants were reperfused by connection of recipient vessels to donor vessels at the surgical anastomosis site. Microcirculation through the newly formed vascular anastomoses appeared partially dependent on VEGFR2 and CXCR2 pathways. In the absence of immunosuppression, the microvasculature in rejecting allografts exhibited vascular complement deposition, diminished endothelial CD31 expression, and absent perfusion prior to the onset of fibroproliferation. Rejecting grafts with extensive endothelial cell injury were refractory to immunotherapy. After early microvascular loss, neovascularization was eventually observed in the membranous trachea, indicating a reestablishment of graft perfusion in established fibrosis. One implication of this study is that bronchial artery revascularization at the time of lung transplantation may decrease the risk of subsequent airway fibrosis.

Severity of lymphocytic bronchiolitis predicts long-term outcome after lung transplantation

RATIONALE

Severe and recurrent acute vascular rejection of the pulmonary allograft is an accepted major risk factor for obliterative bronchiolitis.

OBJECTIVES

We assessed the role of lymphocytic bronchiolitis as a risk factor for bronchiolitis obliterans syndrome (BOS) and death after lung transplantation.

METHODS

Retrospective analysis of 341 90-day survivors of lung transplant performed in 1995-2005 who underwent 1,770 transbronchial lung biopsy procedures.

MEASUREMENTS AND MAIN RESULTS

Transbronchial biopsies showed grade B0 (normal) (n = 501), B1 (minimal) (n = 762), B2 (mild) (n = 176), B3 (moderate) (n = 70), B4 (severe) (n = 4) lymphocytic bronchiolitis, and Bx (no bronchiolar tissue) (n = 75). A total of 182 transbronchial biopsies were ungraded (8 inadequate, 142 cytomegalovirus, 32 other diagnoses). Lung transplant recipients were grouped by highest B grade before diagnosis of BOS: B0 (n = 12), B1 (n = 166), B2 (n = 89), and B3-B4 (n = 51). Twenty-three were unclassifiable. Cumulative incidence of BOS and death were dependent on highest B grade (Kaplan-Meier, P < 0.001, log-rank). Multivariable Cox proportional hazards analysis showed significant risks for BOS were highest B grade (relative risk [RR], 1.62; 95% confidence interval [CI], 1.31-2.00) (P < 0.001), longer ischemic time (RR, 1.00; CI, 1.00-1.00) (P < 0.05), and recent year of transplant (RR, 0.93; CI, 0.87-1.00) (P < 0.05), whereas risks for death were BOS as a time-dependent covariable (RR, 19.10; CI, 11.07-32.96) (P < 0.001) and highest B grade (RR, 1.36; CI, 1.07-1.72) (P < 0.05). Acute vascular rejection was not a significant risk factor in either model.

CONCLUSIONS

Severity of lymphocytic bronchiolitis is associated with increased risk of BOS and death after lung transplantation independent of acute vascular rejection.

A randomized controlled trial of tacrolimus versus cyclosporine after lung transplantation

BACKGROUND

The optimal maintenance immunosuppressive regimen after lung transplantation is uncertain.

METHODS

We conducted a randomized controlled trial of tacrolimus versus cyclosporine in combination with azathioprine and prednisone after lung transplantation. Ninety adults were randomized to tacrolimus (n = 44) or cyclosporine (n = 46). The primary end point was a composite of a cumulative acute rejection A score of 3 or higher, a cumulative lymphocytic bronchitis B score of 4 or higher, or the onset of bronchiolitis obliterans syndrome (BOS) stage 0-p.

RESULTS

Recipients randomized to cyclosporine were significantly more likely to develop the primary end point than those randomized to tacrolimus. During the study period, the primary end point developed in 39 of 46 cyclosporine subjects compared with 24 of 44 tacrolimus subjects (p = 0.002); acute rejection or lymphocytic bronchitis end points developed in 29 of 46 cyclosporine subjects compared with 18 of 44 tacrolimus subjects (p = 0.036). Furthermore, BOS stage 0-p was more likely to develop in the cyclosporine group than in the tacrolimus group, but this was not statistically significant (log-rank p = 0.1). In addition, there was a trend to a higher incidence of diabetes among those in the tacrolimus group, but there was no significant difference in graft survival or the total number of infections, or in the incidence of hypertension, chronic kidney disease, or cancer between the 2 groups.

CONCLUSIONS

Tacrolimus is associated with a lower burden of acute rejection and lymphocytic bronchitis and a trend to a greater freedom from BOS stage 0-p than cyclosporine after lung transplantation.

Pathology of lung transplantation

The International Society for Heart and Lung Transplantation has a standardized nomenclature for the evaluation of lung allografts. Rejection of the lung allograft is divided into acute and chronic forms. Acute cellular rejection is characterized by perivascular accumulations of mononuclear cells and eosinophils; bronchiolar inflammation is also included in the grading scheme. Acute antibody-mediated rejection in lung allografts is not well defined. Chronic rejection is manifest by fibrous scarring narrowing the lumen of bronchioles, arteries, and veins. The diagnosis of rejection requires the exclusion of infection and other pathology in the allograft.

Early growth response gene-1 promotes airway allograft rejection

Chronic airway rejection, characterized by lymphocytic bronchitis, epithelial cell damage, and obliterative bronchiolitis (OB), limits long-term survival after lung transplantation. The transcription factor early growth response gene-1 (Egr-1) induces diverse inflammatory mediators, some involved in OB pathogenesis. An orthotopic mouse tracheal transplant model was used to determine whether Egr-1 promotes development of airway allograft rejection. Significantly higher Egr-1 mRNA levels were seen in allografts (3.2-fold increase vs. isografts, P = 0.012). Allografts revealed thickening of epithelial and subepithelial airway layers (51 +/- 4% luminal encroachment for allografts vs. 20 +/- 3% for isografts, P < 0.0001) marked by significant lymphocytic infiltration. Absence of the Egr-1 gene in donor (but not recipient) tissue resulted in significant reduction in luminal narrowing (34 +/- 4%, P = 0.0001) with corresponding diminution of T cell infiltration. Egr-1 null allografts exhibited a striking reduction in inducible nitric oxide synthase (iNOS) expression. Effector cytokines previously implicated in OB pathogenesis with known Egr-1 promoter motifs (IL-1beta and JE/monocyte chemoattractant protein-1) were reduced in Egr-1 null allografts. These data suggest a paradigm wherein local induction of Egr-1 in tracheal allografts drives expression of inflammatory mediators responsible for lymphocyte recruitment and tissue destruction characteristic of airway rejection.

Impact of immediate primary lung allograft dysfunction on bronchiolitis obliterans syndrome

RATIONALE

Primary graft dysfunction is a common complication after lung transplantation and a significant risk factor for short- and long-term mortality.

OBJECTIVE

We examined the impact of primary graft dysfunction on bronchiolitis obliterans syndrome.

METHODS

We performed a retrospective cohort study of 334 adult lung transplant recipients at our program and graded the severity of primary graft dysfunction according to the International Society for Heart and Lung Transplantation definition. We evaluated the impact of primary graft dysfunction on acute rejection, lymphocytic bronchitis, and bronchiolitis obliterans syndrome stage 1, using univariable and multivariable Cox proportional hazards models.

MAIN RESULTS

Among the 334 recipients, 65 did not have primary graft dysfunction (grade 0), 130 had grade 1, 69 had grade 2, and 70 had grade 3. In the univariable analysis, all grades of primary graft dysfunction were associated with a significantly increased risk of bronchiolitis obliterans syndrome stage 1 (grade 1: relative risk [RR] = 1.73; grade 2: RR = 2.13; and grade 3: RR = 2.53, compared with grade 0). The multivariable model demonstrated that the increased risk of bronchiolitis obliterans syndrome associated with primary graft dysfunction was independent of acute rejection, lymphocytic bronchitis, and community-acquired respiratory viral infections. However, there was no association between primary graft dysfunction and acute rejection or lymphocytic bronchitis.

CONCLUSIONS

Primary graft dysfunction is associated with an increased risk of bronchiolitis obliterans syndrome independent of acute rejection, lymphocytic bronchitis, and community-acquired respiratory viral infections, and this risk is directly related to the severity of primary graft dysfunction.

Surveillance bronchoscopy in children during the first year after lung transplantation: Is it worth it?

BACKGROUND

Since January 2002, routine surveillance bronchoscopy with bronchoalveolar lavage (BAL) and transbronchial biopsy has been performed in all paediatric recipients of lung and heart-lung transplants at the Great Ormond Street Hospital for Children, London, UK, using a newly revised treatment protocol.

AIMS

To report the prevalence of rejection and bacterial, viral or fungal pathogens in asymptomatic children and compare this with the prevalence in children with symptoms.

PARTICIPANTS

The study population included all paediatric patients undergoing single lung transplantation (SLTx), double lung transplantation (DLTx) or heart-lung transplantation between January 2002 and December 2005.

METHODS

Surveillance bronchoscopies were performed at 1 week, and 1, 3, 6 and 12 months after transplant. Bronchoscopies were classified according to whether subjects had symptoms, defined as the presence of cough, sputum production, dyspnoea, malaise, decrease in lung function or chest radiograph changes.

RESULTS

Results of biopsies and BAL were collected, and procedural complications recorded. 23 lung-transplant operations were performed, 12 DLTx, 10 heart-lung transplants and 1 SLTx (15 female patients). The median (range) age of patients was 14.0 (4.9-17.3) years. 17 patients had cystic fibrosis. 95 surveillance bronchoscopies were performed. Rejection (> or =A2) was diagnosed in 4% of biopsies of asymptomatic recipients, and in 12% of biopsies of recipients with symptoms. Potential pathogens were detected in 29% of asymptomatic patients and in 69% of patients with symptoms. The overall diagnostic yield was 35% for asymptomatic children, and 85% for children with symptoms (p < 0.001). The complication rate for bronchoscopies was 3.2%.

CONCLUSIONS

Many children have silent rejection or subclinical infection in the first year after lung transplantation. Routine surveillance bronchoscopy allows detection and targeted treatment of these complications.

Endobronchial Ultrasonography for the Quantitative Assessment of Bronchial Mural Structures in Lung Transplant Recipients

BACKGROUND

Endobronchial ultrasonography (EBUS) has been shown to be an adequate tool to visualize the laminar structure of the bronchial wall. The purpose of this study was to investigate the potential of EBUS to identify and quantitatively assess bronchial wall structures in lung transplant recipients.

METHODS

EBUS was performed with a radial 20-MHz ultrasonic miniprobe in lung transplant recipients undergoing surveillance bronchoscopies. Sequential pictures were taken of the main bronchus (proximal of anastomosis) and proximal right intermedius bronchus or proximal left lower lobe bronchus (distal of anastomosis), respectively. From every localization, five slides were chosen. The quantitative assessment of the digitized pictures was done with the aid of image analysis software. In addition to the comparison of the different layers between patients with and without infection and rejection, respectively, the intraclass correlation coefficients (ICCs) of the different measurements were calculated.

RESULTS

From 20 EBUS examinations performed in 10 lung transplant recipients, 200 slides were selected for quantitative assessment. A five-layer composition could be identified in all selected slides. The relative area of layer two (hypoechoic submucosal tissue) of the autologous part was significantly smaller in patients with graft rejection (p = 0.04) compared to patients without rejection, and significantly larger in patients with graft infection (p = 0.02) compared to patients without graft infection. The ICC values were calculated in 50 different slides in a subset of five consecutive patients (0.91, 0.95, 0.88, and 0.91 for layers 1, 2, 3, and 5 of the autologous and 0.70, 0.92, 0.88, and 0.84 for the allogeneic parts, respectively).

CONCLUSIONS

EBUS enables to discriminate different layers of the bronchi in humans and to measure the thickness of these layers in a reproducible fashion. Therefore, EBUS may be used to investigate and quantify inflammatory alterations of bronchial wall structures in vivo.

A randomized trial of inhaled cyclosporine in lung-transplant recipients

BACKGROUND

Conventional regimens of immunosuppressive drugs often do not prevent chronic rejection after lung transplantation. Topical delivery of cyclosporine in addition to conventional systemic immunosuppression might help prevent acute and chronic rejection events.

METHODS

We conducted a single-center, randomized, double-blind, placebo-controlled trial of inhaled cyclosporine initiated within six weeks after transplantation and given in addition to systemic immunosuppression. A total of 58 patients were randomly assigned to inhale either 300 mg of aerosol cyclosporine (28 patients) or aerosol placebo (30 patients) three days a week for the first two years after transplantation. The primary end point was the rate of histologic acute rejection.

RESULTS

The rates of acute rejection of grade 2 or higher were similar in the cyclosporine and placebo groups: 0.44 episode (95 percent confidence interval, 0.31 to 0.62) vs. 0.46 episode (95 percent confidence interval, 0.33 to 0.64) per patient per year, respectively (P=0.87 by Poisson regression). Survival was improved with aerosolized cyclosporine, with 3 deaths among patients receiving cyclosporine and 14 deaths among patients receiving placebo (relative risk of death, 0.20; 95 percent confidence interval, 0.06 to 0.70; P=0.01). Chronic rejection-free survival also improved with cyclosporine, as determined by spirometric analysis (10 events in the cyclosporine group and 20 events in the placebo group; relative risk of chronic rejection, 0.38; 95 percent confidence interval, 0.18 to 0.82; P=0.01) and histologic analysis (6 vs. 19 events, respectively; relative risk, 0.27; 95 percent confidence interval, 0.11 to 0.67; P=0.005). The risks of nephrotoxic effects and opportunistic infection were similar for patients in the cyclosporine group and the placebo group.

CONCLUSIONS

Inhaled cyclosporine did not improve the rate of acute rejection, but it did improve survival and extend periods of chronic rejection-free survival. (ClinicalTrials.gov number, NCT00268515.).

Inflammation patterns in allogeneic and autologous airway tissue of lung transplant recipients

Inflammatory injuries directed toward airway structures play a key role in lung allograft rejection. However, data relating to the inflammation patterns of large airways are scarce and, in particular, the relation between autologous and allogeneic parts is unknown. For the first time, in this study, simultaneously collected endobronchial biopsies from the main (autologous) and upper lobe (allogeneic) carina of lung transplant recipients were assessed immunohistologically. A total of 27 pairs of EBBs were taken. Twelve endoscopies documented acute rejection and four examinations of patients with BOS were performed. Patients with acute rejection had more CD8-positive cells in the allogeneic parts compared with patients without acute rejection. Patients with BOS had more CD4- and CD45-positive cells in the autologous airways than stable patients. We conclude that distinct inflammatory changes do occur in large airways of lung transplant recipients and are not limited to the donor parts of airways.

Community acquired respiratory viral infections after lung transplantation: clinical features and long-term consequences

Community acquired respiratory viruses (CARVs) are increasingly recognized as serious threats to lung transplant recipients. While CARVs such as respiratory syncytial virus, parainfluenza, influenza, and adenovirus usually cause self-limited illnesses in immunocompetent subjects, infections in the transplant recipient can be dramatic. As transplant recipients live longer and diagnostic methods improve, the burden of CARVs will undoubtedly increase. Because of limited therapeutic options, some patients may succumb to CARV infections, while many survivors develop chronic allograft dysfunction. Recognition of this latter phenomenon has implicated CARVs in the pathogenesis of bronchiolitis obliterans.

Unusual Late Pulmonary Complication in a Child After Umbilical Cord Blood Transplantation

We encountered a late pulmonary complication after umbilical cord blood transplantation (UCBT) that has not been previously reported. High-resolution CT (HRCT) findings of this disease were compared with the pathology. HRCT obtained on inspiration showed dilated thick-walled bronchioli, and innumerable centrilobular linear and branching structures in the bilateral middle and lower lobes. Neither mosaic perfusion nor air-trapping was seen in HRCT on inspiration and expiration. These HRCT findings were atypical compared with those of former bronchiolitis obliterans (BO) after bone marrow transplant (BMT). Pathologic specimens obtained by open lung biopsy showed thickening of the wall from the distal bronchioli to the alveolar ducts due to submucosal and intraepithelial infiltration of lymphocytes, histiocytes and foamy macrophages, which was not accompanied by organizing changes. These changes resemble lymphocytic bronchiolitis in lung transplant recipients, which was well correlated with HRCT findings. We think that our case was a new late pulmonary complication after UCBT.

Airway function and markers of airway inflammation in patients with treated hypothyroidism

BACKGROUND

There is increasing evidence of an association between organ specific autoimmune diseases, particularly autoimmune thyroid disease and respiratory morbidity. A study was undertaken to determine whether patients with autoimmune thyroid disease have objective evidence of airway inflammation and dysfunction.

METHODS

Twenty six non-smoking women with treated hypothyroidism and 19 non-smoking controls completed a symptom questionnaire and underwent full lung function tests, capsaicin cough reflex sensitivity measurement, methacholine challenge test, and sputum induction over two visits.

RESULTS

Symptoms of cough (p = 0.01), dyspnoea (p = 0.01), sputum production (p = 0.004), and wheeze (p = 0.04) were reported more commonly in patients than controls. Patients with hypothyroidism had heightened cough reflex sensitivity compared with controls (geometric mean concentration of capsaicin causing five coughs: 40 v 108 mmol/l; mean difference 1.4 doubling doses; 95% confidence interval of difference 0.4 to 2.5; p = 0.008) and a significantly higher proportion of patients had airway hyperresponsiveness (methacholine provocative concentration (PC(20)) <8 mg/ml: 38% v 0%; p = 0.016). Patients with hypothyroidism also had a significantly higher induced sputum total neutrophil cell count (p = 0.01), total lymphocyte count (p = 0.02), and sputum supernatant interleukin-8 concentrations (p = 0.048).

CONCLUSION

Patients with treated hypothyroidism report more respiratory symptoms and have objective evidence of airway dysfunction and inflammation.

Bronchiolitis obliterans in children

Bronchiolitis obliterans (BO) in children is a relatively rare diagnosis. The increase in lung and bone marrow transplantation in children, however, has led to a heightened interest in BO, as this is one of the important complications of those procedures. This article will discuss BO as an entity that can follow any of several illnesses or toxic exposures, in addition to following allogeneic lung or bone marrow transplantation. The complex and incompletely understood pathology, pathogenesis, and molecular pathology involved in BO remain the subject of ongoing investigations. As the prognosis for BO is uncertain and treatment is often unsuccessful, the continued need for the recognition of surrogate markers for BO in patients at risk and the development of better forms of therapy are paramount. This review will describe our current understanding of BO, and will call attention to those research areas that require continuing efforts in order to prevent or treat this entity.

HLA-specific antibodies are risk factors for lymphocytic bronchiolitis and chronic lung allograft dysfunction

Bronchiolitis obliterans syndrome (BOS) represents a major limitation in lung transplantation. While acute rejection is widely considered the most important risk factor for BOS, the impact of HLA-specific antibodies is less understood. Of 51 lung recipients who were prospectively tested during a 4.2 +/- 1.6-year period, 14 patients developed HLA-specific antibodies. A multi-factorial analysis was performed to correlate the prevalence of BOS with HLA antibodies, persistent-recurrent acute rejection (ACR-PR), lymphocytic bronchiolitis, and HLA-A, -B, and -DR mismatches. HLA-specific antibodies were associated with ACR-PR (10/14 vs. 11/37 with no antibodies, p < 0.05), lymphocytic bronchiolitis (8/14 vs. 10/37, p < 0.05), and BOS (10/14, vs. 9/37, p < 0.005). Other risk factors for BOS were: lymphocytic bronchiolitis (13/18 vs. 6/33 with no lymphocytic bronchiolitis, p < 0.0001), ACR-PR (12/21 vs. 7/30 with no ACR-PR, p < 0.05), and the number of HLA-DR mismatches (1.7 +/- 0.48 in BOS vs. 1.2 +/- 0.63 without BOS, p < 0.05). The presence of antibodies exhibited a cumulative effect on BOS when it was associated with either lymphocytic bronchiolitis or ACR-PR. The complex relationship between the development of HLA antibodies and acute and chronic lung allograft rejection determines the importance of post-transplant screening for HLA-specific antibodies as a prognostic element for lung allograft outcome.

Bronchiolitis obliterans syndrome: Pathogenesis and management

Over the past 15 years, lung transplantation has become an established treatment for a variety of end-stage lung diseases, but medium- and long-term success has been limited by a high incidence of bronchiolitis obliterans syndrome (BOS). Immune mediated injury has been recognized as the leading cause of BOS, and the term is synonymous with chronic rejection. But recently, nonimmune mechanisms, such as gastroesophageal reflux, have been recognized as potential culprits. The results of various treatment options have generally been disappointing, and BOS has emerged as the leading cause of late morbidity and mortality after lung transplantation.

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.

Pattern and Predictors of Early Rejection After Lung Transplantation

• Background Most lung transplant recipients experience improvement in their underlying pulmonary condition but are faced with the threat of allograft rejection, the primary determinant of long-term survival. Several studies examined predictors of rejection, but few focused on the early period after transplantation.

• Objectives To describe the pattern and predictors of early rejection during the first year after transplantation to guide the development of interventions to facilitate earlier detection and treatment of rejection.

• Methods Data for donor, recipient, and posttransplant variables were retrieved retrospectively for 250 recipients of single or double lung transplants.

• Results Most recipients (85%) had at least 1 episode of acute rejection; 33% had a single episode; 23% had recurrent rejection; 3% had persistent rejection; 13% had refractory rejection; and 14% had clinicopathological evidence of chronic rejection. Serious rejection (refractory acute rejection or chronic rejection) developed in 27% of recipients. Compared with other recipients, recipients who had serious rejection had more episodes of acute rejection (P = .004), and the first acute episodes occurred sooner after transplantation (P = .01) and were of a higher grade (P = .002).

• Conclusions Recipients who experienced higher grades for their first episode of acute rejection (P=.03) and higher cumulative rejection scores (P = .004) were significantly more likely than other recipients to have serious rejection during the first year after transplantation.

Recipient iNOS but not eNOS deficiency reduces luminal narrowing in tracheal allografts

Chronic airway rejection is characterized by prolonged inflammation, epithelial damage, and eventual luminal obliterative bronchiolitis (OB). In cardiac allografts, the inducible nitric oxide synthase (iNOS) promotes acute rejection but paradoxically reduces neointimal formation, the hallmark of chronic rejection. The specific roles of NOS isoforms in modulating lymphocyte traffic and airway rejection are not known. Using a double lumen mouse tracheal transplant model, tracheal grafts from B10.A (allo) or C57BL/6J (iso) mice were transplanted into cyclosporine-treated wild-type (WT) iNOS(-/-) or endothelial NOS (eNOS)(-/-) recipients. OB was observed in WT tracheal allografts at 3 weeks (53 +/- 2% luminal occlusion vs. 17 +/- 1% for isografts, P < 0.05) with sites of obstructive lesion formation coinciding with areas of CD3(+) CD8(+) T cell-rich lymphocytic bronchitis. In contrast, allografts in iNOS(-/-) recipients exhibited reductions in local expression of proinflammatory chemokines and cytokines, graft T cell recruitment and apoptosis, and luminal obliteration (29 +/- 2%, P < 0.05 vs. WT allografts). Recipient eNOS deficiency, however, suppressed neither chemokine expression, lymphocyte infiltration, nor airway occlusion (54 +/- 2%). These data demonstrate that iNOS exacerbates luminal obliteration of airway allografts in contrast with the known suppression by iNOS of cardiac allograft vasculopathy. Because iNOS(-/-) airways transplanted into WT allograft hosts are not protected from rejection, these data suggest that iNOS expressed by graft-infiltrating leukocytes exerts the dominant influence on airway rejection.