Lymphocytic bronchitis/bronchiolitis in lung allograft recipients

Clinical, radiologic, and induced sputum features of chronic obstructive pulmonary disease in nonsmokers: a descriptive study

Epidemiologic studies show that 5-12% of subjects with chronic obstructive pulmonary disease (COPD) are nonsmokers. Little is known about the pathophysiology of the fixed airflow obstruction in these subjects. We have prospectively identified 25 patients with COPD who had never smoked or had a less than 5 pack years smoking history and present the clinical, radiologic, and induced sputum features. Our population represented 5.7% of total referrals with fixed airflow obstruction over 2 years. Patients had a mean age of 70 years, were predominantly female (86%), and had a mean duration of respiratory symptoms of 7 years. The mean FEV(1) was 58%, and the FEV(1)/FVC was 55%. Features on high-resolution computed tomographic scanning were nonspecific and were considered typical of a wider population with COPD. An induced sputum differential inflammatory cell count suggested the presence of two distinct groups. Nine had significant sputum eosinophilia (mean, 8.1%; normal, less than 1.9%), and the remaining 13 had a normal sputum eosinophil and tended to have a raised sputum neutrophil count (mean, 70.1%; normal, less than 65%). Organ-specific autoimmune disease was present in 7 of the 22 patients (32%) and was particularly prevalent in those without sputum eosinophilia (6 of 13). In conclusion, COPD in nonsmokers predominantly affects females and has at least two pathologic subgroups, one of which may be associated with organ-specific autoimmune disease. Further investigation of this group may disclose novel mechanisms of fixed airflow obstruction.

Epithelial kinetics in mouse heterotopic tracheal allografts

Obliterative bronchiolitis (OB) is the most important cause of graft dysfunction post-lung transplantation. It is likely that the small airway epithelium is a target of the alloimmune response, and that epithelial integrity is a crucial determinant of airway patency. Our goals are to elucidate epithelial cell kinetics in the heterotopic mouse trachea model and to determine potential mechanisms of cell death in allografts. Allografts and isografts were obtained by transplanting BALB/c tracheas into C57BL/6 and BALB/c immunosuppressed and non-immunosuppressed hosts, respectively and harvested from day 3-20. Morphometry, BrdU and TUNEL labeling, and EM studies were performed. Columnar epithelium in isografts and allografts sloughs during day 0-3, but regenerates in both sets of grafts by day 10. Subsequently, allografts become inflamed and denuded, while isografts retain an intact epithelium. Prior to airway denudation, allografts exhibited significantly increased epithelial cell density, BrdU labeling index (LI), and TUNEL positive cells. Epithelial apoptosis was confirmed by electron microscopy. Allograft percent ciliated columnar epithelium and lumenal circumference were significantly decreased. Cyclosporin delayed airway fibrosis but did not alter the progression of the allograft through the phases of early ischemic injury, airway epithelial cell regeneration, and eventual cell death. These studies quantitatively demonstrate that the allograft epithelium actively regenerates in the alloimmune environment, but succumbs to increased apoptotic cell death, underscoring the importance of the airway epithelium as a self-renewing source of alloantigen.

Inhaled corticosteroids and the treatment of lymphocytic bronchiolitis following lung transplantation

Airway rejection after lung transplantation is recognized histologically as lymphocytic bronchiolitis (LB). We hypothesized that inhaled steroids could control LB and that changes in exhaled nitric oxide (eNO) would correlate with the development of LB and also have a role in monitoring response to treatment. A cohort of 120 lung transplant (LT) recipients attending for review and biopsy had eNO measurements, FEV1, lavage microbiology, and biopsy histology performed prospectively. Wilcoxon signed-rank test was used to assess the significance of changes in eNO and FEV1. The coefficient of reproducibility of eNO measurement in stable recipients was 2.36 ppb. Fourteen developed graft dysfunction owing to isolated LB and were treated with inhaled budesonide 800 microg twice daily. They showed significant increases in eNO at diagnosis, median (range) 10.9 ppb (4.6 to 48) ppb compared with baseline, 4.33 (1.0 to 10.76), p = 0.008, and a decrease in FEV1. After inhaled treatment, both eNO and FEV1 returned to baseline values. Seven developed acute vascular rejection (with or without LB) and were treated with oral corticosteroids; no changes in eNO occurred at diagnosis or after treatment. Serial eNO measurements provide a useful noninvasive method of identifying airway inflammation in LT recipients. Inhaled budesonide may be a useful addition to systemic immunosuppressants in controlling airway inflammation posttransplant.

Segmental nonanastomotic bronchial stenosis after lung transplantation

BACKGROUND

Nonanastomotic distal bronchial stenosis has been observed in some patients after lung transplantation. We investigated its relationship with acute cellular rejection (ACR), infection, and ischemia.

METHODS

Between January 1994 and December 1997, 246 lung transplantations were performed at our hospital. These cases were retrospectively reviewed and evaluated to identify those patients with nonanastomotic bronchial stenosis.

RESULTS

Six patients had bronchial stenosis within the grafted airway distal to the uninvolved anastomotic site. The average ACR before stenosis was 1.9 compared with 1.6 in a control group. ACR at the time of first recognition of the stenosis ranged from A2 to A3.5, with an average value of A2.9. All 6 patients demonstrated alloreactive airway inflammation before and at the time of stenosis. Four patients had evidence of ischemic damage in the perioperative period.

CONCLUSIONS

Segmental nonanastomotic large airway stenosis after lung transplantation should be assessed separately from anastomotic complications. Although the pathogenesis is unclear, certainly one should consider alloreactive injury, ischemic damage, and infection as individual and coercive causes.

Analysis of risk factors for the development of bronchiolitis obliterans syndrome

Chronic rejection after lung transplantation, manifesting as bronchiolitis obliterans syndrome (BOS), has become the dominant challenge to long-term patient and graft survival. In order to elucidate risk factors for development of BOS we utilized the 1995 revision of the working formulation for the classification of lung allograft rejection (), and devised a quantitative method to retrospectively study lung transplant biopsies from all patients who survived at least 90 d. All transbronchial biopsies were regraded 0 to 4 for acute perivascular rejection and lymphocytic bronchitis/bronchiolitis (LBB), and the grades were totaled over a period of time to give two scores, respectively, for each patient. Also examined were timing of acute rejection and LBB episodes and decreased immunosuppression defined as two or more cyclosporine A levels < 200 ng/ml. Sixty-six patients with BOS and 68 with no BOS (NBOS) satisfied our criteria for inclusion in the study. Demographics including age, sex, and primary diagnoses were similar. The mean perivascular score for BOS was 6.2 over a mean follow-up of 822 d (range, 113 to 2,146) compared with 3.2 for NBOS over 550 d (range, 97 to 1,734) mean follow-up. Airway scores were 5.3 and 1.7, respectively, for the same follow-up periods. There was no correlation between length of follow-up and rejection or LBB scores, although mean length of follow-up for the two groups was significantly different. Late acute rejection and LBB were significantly associated with BOS as was decreased immunosuppression. In addition to perivascular rejection, LBB, late acute rejection, and decreased immunosuppression are significant risk factors for the development of BOS. Analysis of the current data leads us to believe that LBB, in the absence of infection, is in fact a manifestation of acute rejection, with similar implications for graft function as acute perivascular rejection.

Constrictive (obliterative) bronchiolitis: diagnosis, etiology, and a critical review of the literature

Constrictive bronchiolitis (CB) (or obliterative bronchiolitis) designates inflammation and fibrosis occurring predominantly in the walls and contiguous tissues of membranous and respiratory bronchioles, with resultant narrowing of their lumens. It differs from bronchiolitis obliterans-organizing pneumonia in its histopathology and clinical course. Most cases of CB occur in the setting of organ transplants, particularly lung and heart-lung transplants, but also in bone marrow transplants. Other bona fide cases are rare: infection, particularly viral infection, appears to be a well-documented precursor to CB in children, but not in immunocompetent adults. Constrictive bronchiolitis also has been reported in the course of rheumatoid arthritis, in certain other autoimmune diseases such as pemphigus vulgaris, after inhalation of toxic gases such as nitrogen oxide, after ingestion of certain drugs or medicinal agents such as Sauropus androgynous, and as a cryptogenic illness. Recent reports suggest that CB, as defined by clinical criteria (that is, bronchiolitis obliterans syndrome), is very common in lung allograft recipients who survive more than 5 years and, although it is associated with significant mortality, it also can be clinically stable. Furthermore, with the current practice of close monitoring of these patients, it appears that CB may now be diagnosed at an earlier stage, at which resolution, or at least stabilization of progression, is possible. A histopathologic diagnosis of CB in lung transplant and other patients may be difficult to make due to the patchy distribution of lesions, the technical difficulty in obtaining tissue in late lesions with extensive fibrosis, and the failure to recognize lesions. With regard to the last of these, in early stages of disease, CB may be subtle and easily missed in routine hematoxylin-eosin-stained specimens, while in advanced stages the disease may be equally difficult to diagnose if the patchy scarring in the lung is interpreted as nonspecific. The relative loss of bronchioles and the relationship of the scars to contiguous arteries should signal the need for elastic stains to look for the residual elastica of the bronchioles amidst the foci of fibrosis. Increasingly, clinical grounds, including pulmonary functions studies and high-resolution computed tomography findings, are proving to be relatively sensitive methods of detecting CB. Finally, the progressive airway destruction in chronic transplantation rejection appears to be a T-cell-mediated process. The "active" form of constrictive bronchiolitis, with attendant lymphocytic inflammation of the airways, likely precedes the "inactive" or scarred form of constrictive bronchiolitis.

Immune cells in a mouse airway model of obliterative bronchiolitis

Obliterative bronchiolitis (OB), a form of chronic lung rejection, affects 50% of all lung-transplant recipients and is a major cause of morbidity and mortality. We used the mouse tracheal allograft model of OB to quantitate inflammatory cells during disease progression to evaluate the pathogenesis of this disorder. Tracheas of BALB/c mice were implanted into C57BL/6, severe combined immunodeficiency (SCID), and BALB/c mice. Cyclosporin was administered at 25 mg/kg/d. Grafts were harvested at 2, 6, 10, and 15 wk, and analyzed immunohistochemically. Tracheal allografts developed epithelial injury and cellular infiltrates at 2 wk, epithelial denudation and complete luminal obliteration at 6 wk, and dense collagenous scarring by 15 wk. SCID allografts and isografts demonstrated intact epithelium throughout, although a mononuclear infiltrate was initially present at 2 wk in the SCID allografts. Immunohistochemical staining, using antibodies to mouse CD4(+) (T-helper lymphocyte), CD8(+) (T-cytotoxic/suppressor lymphocyte), and B lymphocytes, macrophages, and myofibroblasts, revealed large numbers of macrophages and CD4(+) and CD8(+) lymphocytes in allografts at 2 wk, compared with isografts. The allograft CD4(+)/CD8(+) ratio was 0.75 at 2 wk. Allografts demonstrated macrophage, myofibroblast, and CD4(+) predominance at 6 and 10 wk (CD4(+)/CD8(+) = 2/1), but by 15 wk had minimal cellularity and were densely scarred. SCID allografts demonstrated a macrophage-predominant infiltrate at 2 wk, with minimal cellularity at later time points. These results indicate that: (1) OB is predominantly an immunologic airway injury; and (2) CD4(+) and CD8(+) lymphocytes and macrophages play an important role in the evolution of airway inflammation and fibrosis. Additionally, this model suggests that chronic airway fibrosis follows a period of intense airway-directed, cell-mediated rejection.

Cross sectional study of exhaled nitric oxide levels following lung transplantation

BACKGROUND

The role of nitric oxide (NO) in the pathophysiology of graft dysfunction following lung transplantation remains unclear. To determine whether measurement of NO in the exhaled breath of lung transplant recipients provides useful information about graft pathology, a cross sectional study was performed on a cohort of recipients as they attended for review.

METHODS

One hundred and four lung transplant recipients and 55 healthy non-smoking controls were included in the study. Each subject performed three consecutive single breath NO manoeuvres. In recipients NO levels were compared according to current clinical status, presence of any graft pathology, type of lung transplant procedure, indication for transplantation, and current level of immunosuppression.

RESULTS

Mean (SE) exhaled NO levels were 6.5 (0.61) ppb in the control group, 5.3 (0.46) in clinically well recipients, 10.3 (1.4) in those with lymphocytic bronchiolitis, 10.5 (1.0) in recipients with infection, and 2.5 (0.6) in those with acute vascular rejection. There was no significant difference in NO levels between the control group and lung transplant recipients as a whole (mean difference 0.29 (95% CI -1.17 to 1.75), p = 0.7). Levels were increased significantly in the presence of lymphocytic bronchiolitis (4.98 (95% CI 1.6 to 8.36), p = 0.0002) and infection (5.28 (95% CI 2.9 to 7.56), p < 0.0001), but not in acute vascular rejection (2.76 (95% CI 0.97 to 4.55), p = 0.1) compared with exhaled NO in clinically well recipients. Recipients with obliterative bronchiolitis were subdivided according to the grade of their bronchiolitis obliterans syndrome (BOS). Exhaled NO levels in those with BOS grade 1 were 10.0 (1.3) ppb and in those with BOS grades 2 or 3 were 5.1 (0.7) ppb. Compared with those who were clinically well, NO levels were increased in those with BOS grade 1 (4.74 (95% CI 1.8 to 7.69), p < 0.0001) but not in those with BOS grades 2 or 3 (0.19 (95% CI -1.55 to 1.93), p = 0.82).

CONCLUSIONS

Exhaled NO levels are increased in lung transplant recipients with lymphocytic bronchiolitis, early obliterative bronchiolitis, and infection. These conditions are all associated with the presence of airway inflammation within the graft. The findings suggest that exhaled NO measurements may have a role as a marker of pulmonary allograft dysfunction.

Allograft colonization and infections with pseudomonas in cystic fibrosis lung transplant recipients

OBJECTIVE

To assess the incidence of pseudomonal infection, colonization, and inflammation in the allograft of lung transplant recipients with cystic fibrosis (CF) as compared with recipients with other end-stage lung disease.

DESIGN

Retrospective review.

SETTING

University medical center transplant service.

PATIENTS

All patients with CF and chronic pseudomonal infection (n=62) and patients with nonseptic end-stage lung disease (n=52) receiving a double lung transplant between October 1983 and March 1996.

RESULTS

Fifty lung transplant recipients with CF survived beyond postoperative day (POD) 15 and were subject to sequential bronchoscopy with BAL. Forty-four CF lung transplant recipients had Pseudomonas isolated from the allograft by median POD 15 as compared with 21 non-CF lung transplant recipients (p<0.001) with isolation at median POD 158 (p<0.0001). Thirteen CF lung transplant recipients had histologic evidence of infection when Pseudomonas was isolated as compared with only three of the non-CF lung transplant recipients (p<0.01). These infections occurred earlier in the CF lung transplant recipients (median POD 10 vs 261) (p<0.01). When compared with non-CF lung transplant recipients, CF lung transplant recipients with Pseudomonas isolated but without concomitant histologic infection (colonized) were demonstrated to have increased number of polymorphonuclear cells (PMNs) in the BAL fluid recovered from the allograft (17.66+/-24.94 x 10(6) cells vs 3.46+/-4.73 x 10(6)) (p<0.05). Non-CF lung transplant recipients who became colonized with Pseudomonas also had a greater number of PMNs recovered when compared with non-CF lung transplant recipients who did not have Pseudomonas (22.32+/-34.00 x 10(6) cells vs 0.21+/-0.18 x 10(6)) (p<0.01). Nine of 32 (28%) lung transplant recipients with CF have died from pseudomonal allograft infections, but this is no greater than 4 of 21 (19%) deaths related to Pseudomonas infection in recipients without CF (p=0.34).

CONCLUSIONS

Isolation of Pseudomonas from the lung allograft occurs more frequently and earlier after transplantation in recipients with CF. While infections related to Pseudomonas also occur more frequently in recipients with CF, there is no increase in mortality. There is an intense inflammatory response in the lung allograft associated with the isolation of Pseudomonas in recipients with and without CF.

Bronchiolitis obliterans: pathogenesis, prevention, and management

Increasing early success-post lung transplant has been tempered by the long-term development of histologic bronchiolitis obliterans (OB) or of the progressive airway obstruction which is called bronchiolitis obliterans syndrome (BOS). Multiple lines of evidence suggest that OB/BOS is due to an injury directed against the epithelial cells in the airways of the donor lung by the immune system of the recipient. Acute rejection is the strongest risk factor for the subsequent development of this process. Efforts to prevent or minimize acute rejection may reduce the prevalence of OB/BOS. Results of treatment with augmented immunosuppression have been disappointing but the treatment of complicating infections in the allograft can be beneficial. Multicenter studies are needed to assess the efficacy of new immunosuppressive agents in preventing or treating OB/BOS.

Adenovirus-mediated interleukin-10 gene transfer inhibits post-transplant fibrous airway obliteration in an animal model of bronchiolitis obliterans

Bronchiolitis obliterans, a form of chronic allograft rejection characterized by progressive fibrous obliteration of the airways, is the major obstacle limiting prolonged survival of lung transplant recipients. To date, no effective therapy against this fatal complication exists. Interleukin-10 (IL-10), an anti-inflammatory and immunosuppressive cytokine, inhibits various T cell and antigen-presenting cell functions. We examined the effect of IL-10 in an animal model for bronchiolitis obliterans. A heterotopic tracheal transplant model was used. IL-10 was administered to the recipient either in its recombinant form by osmotic minipump or by adenoviral-mediated IL-10 gene transfer (Ad5E1mIL-10). Successful gene transfection and expression was confirmed by measuring circulating IL-10 protein. Tracheal allografts were assessed histologically based on a scoring system. IL-10 administration (in recombinant form or by gene transfer) inhibited the development of fibrous airway obliteration 3 weeks after transplantation in comparison to untreated controls (p < 0.05). This was demonstrated only if the delivery was initiated 5 days after transplantation and not if it was started at the time of transplantation. A single administration of the gene construct was sufficient to achieve the desired effect. We have shown that IL-10 can prevent the development of airway fibro-obliteration in this model. Gene transfection at a site distant from a graft can be used to produce a desired effect on the graft. IL-10 may be of major importance in the control of post-transplant bronchiolitis obliterans. The timing of its administration is critical and further studies are required to determine the mechanisms underlying the observed effects of IL-10.

Experimental piglet lung transplantation: histological bioptic changes and autopsy findings

To investigate difficulties in diagnosing pulmonary rejection and to create a new model to observe long-term histological consequences, 21 piglets were subjected to left single lung transplantation. Five of these transplants served as targets for unmodified rejection in piglets without immunosuppression (Group I), 13 recipients were treated with cyclosporin A, azathioprine and methylprednisolone (Group II), and in 3 cases reimplantation of an autograft was performed (Group III). In the course of postoperative graft monitoring, transthoracic/bronchial biopsies were obtained on days 3, 5, 7, 10, 14, and 20, and thereafter less frequently up to 134 days. In the unmodified rejection group, grafts consolidated in one week and histologically presented perivascular mononuclear cell infiltrates, except for one case which showed vasculitis. Lymphocytic bronchiolitis and or peribronchiolar infiltrate was present in three of the four autopsied grafts. In Group II acute rejection was detected six times in three piglets, and all except one of these specimens had a peribronchiolar component. Although no incontestable bronchiolitis obliterans developed, mild to moderate chronic obliterative vascular lesions were detected in all immunosuppressed piglets (n = 3) surviving more than 80 days. Contralateral lungs and Group III autografts showed mild changes related to the operation itself and interstitial swine endemic pneumonia (SEP). Chronic changes related to rejection were limited to the vascular wall. The mainly inflammatory bronchiolar changes are thought to present an incipient phase leading to obliterative lesions.

Lymphocytic airway infiltration as a precursor to fibrous obliteration in a rat model of bronchiolitis obliterans

BACKGROUND

Bronchiolitis obliterans is the most significant complication adversely affecting prolonged survival of lung allograft recipients. The evolution from the initial insult to the final pathologic entity is largely unknown. The aim of this study was to characterize the evolution of transplant-induced fibrous airway obliteration in a rat tracheal transplant model of bronchiolitis obliterans.

METHODS

Tracheal segments were transplanted from Brown Norway rats to Brown Norway rats (isografts) or to Lewis rats (allografts). Grafts were implanted into a subcutaneous pouch and an abdominal omental wrap. They were harvested at 14 different time points (from 1 day to 1 year after transplantation) and assessed histologically.

RESULTS

The fibrous airway obliteration developed only in allografts showing a triphasic time course: an initial ischemic phase (observed in both isografts and allografts) was followed by a marked lymphocytic infiltrative phase with complete epithelial loss (observed only in allografts, P<0.01), and finally by an obliterative phase with fibrous obliteration of the allograft airway lumen (P<0.01).

CONCLUSIONS

This animal model shows a distinct and reproducible triphasic time course in the development of obliterative airway lesions in allografts. It confirms that the mechanism leading to airway obliteration is immune mediated as only allografts showed this lesion and that lymphocytic infiltration is a precursor of the lesion in this model. The insights into the different phases demonstrated may lead to novel approaches regarding the type and timing of therapeutic interventions.

Obliterative bronchiolitis

Obliterative bronchiolitis following lung transplantation is common and potentially devastating. Its exact cause is undefined, but multiple immune and nonimmune processes contribute to its pathogenesis. Severe acute rejection and recurrent acute rejection have been shown to confer the greatest risk for obliterative bronchiolitis, signifying the central importance of alloimmunity in the disease process. Treatment of established disease with intensification of immune suppression has been of limited benefit, so current clinical strategies include early detection and minimization of risk. As our understanding of the disease evolves, it is hoped that effective interventions targeted at specific pathogenetic steps will emerge. In the meantime, obliterative bronchiolitis remains the most important and sinister long-term complication of lung transplantation.

Pathology of lung allografts in children and young adults

Heart-lung and lung transplantation have become acceptable therapeutic modalities for end-stage lung and heart conditions in children and young adults, but the posttransplantation pulmonary pathology in this age-group is poorly characterized. We present our experience with the pathology of lung transplantation in a cohort of 11 patients with a median age of 12.5 years, and median posttransplantation follow-up of 8.3 months. The findings are based on histological examination of 98 specimens, including five autopsy specimens from patients 20 years of age or younger. Our experience, combined with the data in other pediatric series, suggest that there is not a significant difference in the prevalence or severity of acute rejection or bronchiolitis obliterans (BO) between adult and pediatric lung transplant recipients. Lymphocytic bronchitis/bronchiolitis showed a more prominent association with BO in our series than previously reported in adult studies. Chronic vascular rejection in the pediatric lung transplant recipients can occur earlier than reported in adults and is associated with a grave prognosis. Overwhelming infection was a major cause of death in our experience. In particular, our data combined with the previous reports indicate that adenoviral pneumonia is a relatively common pathogen in the pediatric population and is a major cause of mortality in this age-group.

Development of bronchiolitis obliterans syndrome in recipients of heart-lung transplantation--early risk factors

Given the internationally recognized definition of bronchiolitis obliterans syndrome (BOS) and longer follow up of heart-lung transplant recipients, it is possible to establish some of the major risk factors for development and progression of BOS. Between April 1984 and 31 December 1993, 157 patients underwent heart-lung transplantation; 126 survived at least six months after operation and so were at risk of developing BOS. The following early risk factors were assessed for development of BOS grade 1 (21-35% decline in FEV1) and progression from grade 1 to grade 2 (36-50% decline in FEV1): age, gender and underlying diagnosis of the recipient, evidence of acute rejection and cytomegalovirus (CMV) infection within 6 months of operation, peak FEV1 achieved, age and gender of the donor, cold ischemic time of the graft, and matching of CMV serological status and HLA antigens of donor and recipient. The number of acute rejection episodes observed remained the single most important determinant of development of BOS grade 1 (relative risk 1.17 (1.06, 1.29), P=0.002) and progression to BOS grade 2 (relative risk 1.58 (1.02, 2.46), P=0.03). No other factors were significantly related to development or progression of BOS, although both evidence of CMV infection and disease and the number of HLA mismatches increased the risk. Bronchiolitis obliterans syndrome is a major problem for medium-to-long-term survivors of cardiothoracic transplantation. Acute rejection early after transplantation is a sensitive prognostic indicator of subsequent functional decline and requires prompt attention.