G.A. Patterson

Successful outcome of lung transplantation is not compromised by the use of marginal donor lungs

Lung transplantation is limited by a shortage of suitable donors. To address this shortage, we have begun using donor lungs that do not meet all of our previous rigorous donor criteria. Of 133 consecutive lung transplants done between June 1991 and March 1994, 89 donors were considered ideal because they satisfied all of the following accepted donor criteria (group I): age younger than 55 years, smoking less than 20 pack-years, arterial oxygen tension greater than 300 mm Hg (using inspired oxygen fraction of 1.0 and positive end-expiratory pressure 5 cm H2O), and chest radiograph negative for infiltrate or trauma (contusion or pneumothorax). Thirty-seven donors failed to satisfy one of these criteria and seven donors failed to satisfy two of them, yielding 51 criteria denoting marginal status in the 44 donors in the marginal group (group II) as follows: age older than 55 years, 2; smoking history 20 or more pack-years, 9; unsatisfactory chest radiograph, 34; and arterial oxygen tension less than 300 mm Hg, 6. Sixty-three single lung transplants were done (group I, 44 versus group II, 19) compared with 70 bilateral sequential transplants (group I, 45 versus group II, 25). In 24 cases in group II, at least one of the lungs actually being implanted contained contusion or infiltrate. Evaluation of recipients from the two groups showed no significant difference in median duration of postoperative mechanical ventilation (3 days in both group I and group II) nor in alveolar-arterial oxygen gradient immediately after transplantation (group I, 304 +/- 14 mm Hg versus group II, 275 +/- 22 mm Hg; p = 0.266) or at 24 hours (group I, 125 +/- 12 mm Hg versus group II, 122 +/- 18 mm Hg; p = 0.933) (all values represent mean plus or minus the standard error). However, cardiopulmonary bypass was required to facilitate second graft insertion in bilateral sequential transplants more often in the marginal group (5 of 25, 20%) than in group I (6 of 45, 13%). There were three deaths within 30 days in group I (operative mortality, 3.4%) and none in group II. Currently, 74 (83.2%) of 89 remain alive in group I compared with 38 (86.4%) of 44 in group II. On the basis of these data, we conclude that successful outcome of lung transplantation can be achieved with the use of marginal donor lungs.

HLA-A locus mismatches and development of antibodies to HLA after lung transplantation correlate with the development of bronchiolitis obliterans syndrome

BACKGROUND Bronchiolitis obliterans syndrome (BOS) is the most common cause of morbidity and mortality after lung transplantation (LT). A retrospective analysis of clinical and immunologic variables were done to identify those that might predict the development of BOS. METHODS Of 112 LT performed over a 42-month interval, 94 survived at least 3 months and form the basis of this analysis. There was a minimum of 21 months follow-up. BOS was defined on the basis of declining spirometry (FEV1 <80% of baseline) and/or the presence of histologic obliterative bronchiolitis. All variables analyzed were subjected first to a univariate analysis; those variables appearing to carry significance were then subjected to a multivariate logistic regression analysis. RESULTS Univariate analysis revealed the following to be predictors of the development of BOS: age (the probability of developing BOS declined with advancing age); donor/recipient HLA-A locus mismatch, with actuarial freedom from BOS being significantly greater with no A-locus mismatches versus cases with one or two mismatches (P=0.031); and development of anti-HLA antibodies after transplantation (P=0.006 vs. recipients without detectable antibodies). In multivariate analysis, only HLA locus mismatch and development of anti-HLA antibodies were significant independent predictors of the development of BOS. The remaining clinical variables (gender, type of LT, indication for LT, graft ischemic time, use of cardiopulmonary bypass, cytomegalovirus) and immunologic variables (crossmatch, frequent early acute rejection) did not correlate with the development of BOS. CONCLUSIONS These data suggest that BOS is the result of an immune process, that differences at the HLA-A locus may play an important role in this process, and antibody-mediated injury may play a role in BOS.

Development of ELISA-detected anti-HLA antibodies precedes the development of bronchiolitis obliterans syndrome and correlates with progressive decline in pulmonary function after lung transplantation.

BACKGROUND Development of anti-HLA antibodies after lung transplantation (LT) is thought to play an important role in the etiology of bronchiolitis obliterans syndrome (BOS). However, a cause-effect relationship between anti-HLA antibodies and BOS has not been established. This study was conducted to determine the temporal relationship between the development of anti-HLA antibodies and BOS after LT, and to determine the antigenic specificity of the antibodies developed in BOS patients. METHODS Sera from 15 BOS+ LT patients and 12 BOS- LT patients were obtained before LT and collected again at 6, 12, 24, 36, and 48 months after LT. Anti-HLA antibodies were detected by the PRA-STAT ELISA system and by complement-dependent cytotoxicity assays. Anti-HLA reactivity was further characterized by flow cytometry and absorption/elution with human platelets. RESULTS When analyzed by ELISA, 10 of 15 BOS+ patients developed anti-HLA antibodies, whereas 0 of 12 BOS- patients developed anti-HLA antibodies (P<0.001). When analyzed by complement-dependent cytotoxicity, only 2 of 15 BOS+ patients developed anti-HLA antibodies and 1 of 12 BOS- patients developed anti-HLA antibodies (P = 0.99). There was a significant difference of 20.1 months between the time of anti-HLA antibody detection and the time of BOS diagnosis (P = 0.005). A progressive decrease in pulmonary function correlated with a progressive increase in the anti-HLA reactivity 36 months after LT. The anti-HLA reactivity was directed to one of the donor HLA class I antigens and to other unrelated HLA class I antigens. No anti-HLA reactivity was found against HLA class II molecules. CONCLUSIONS Our study indicates that anti-HLA class I antibodies play an important role in the pathogenesis of BOS and that monitoring of anti-HLA class I antibody development by a highly sensitive assay such as the PRA-STAT ELISA after LT can provide an early identification of an important subset of LT patients with an increased risk of developing BOS.

The efficacy of photopheresis for bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND Extracorporeal photopheresis (ECP) has been used to treat acute and chronic rejection after solid organ transplantation. However, data supporting the use of ECP for bronchiolitis obliterans syndrome (BOS) after lung transplantation are limited. METHODS We retrospectively analyzed the efficacy and safety of ECP for progressive BOS at our institution. Between January 1, 2000, and December 31, 2007, 60 lung allograft recipients were treated with ECP for progressive BOS. RESULTS During the 6-month period before the initiation of ECP, the average rate of decline in forced expiratory volume in 1 second (FEV(1)) was -116.0 ml/month, but the slope decreased to -28.9 ml/month during the 6-month period after the initiation of ECP, and the mean difference in the rate of decline was 87.1 ml/month (95% confidence interval, 57.3-116.9; p < 0.0001). The FEV(1) improved in 25.0% of patients after the initiation of ECP, with a mean increase of 20.1 ml/month. CONCLUSIONS ECP is associated with a reduction in the rate of decline in lung function associated with progressive BOS.

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.

CD4+25+ Regulatory T Cells Limit Th1-Autoimmunity by Inducing IL-10 Producing T Cells Following Human Lung Transplantation

Chronic human lung allograft rejection is manifested by bronchiolitis obliterans syndrome (BOS). BOS has a multifactorial etiology. Previous studies have indicated that both cellular and humoral alloimmunity play a significant role in the pathogenesis of BOS. Recently, autoimmunity has also been demonstrated to contribute to lung allograft rejection in animal models. However, the significance of autoimmunity in BOS remains unknown. In this report, we investigated the role of naturally occurring CD4+CD25+ regulatory T cells (T‐regs) in modulating cellular autoimmunity to collagen type V (col‐V), a ‘sequestered’ yet immunogenic self‐protein present in the lung tissue, following lung transplantation (LT). We demonstrated that col‐V reactive CD4+ T cells could be detected in the peripheral blood of lung transplant recipients. There was a predominance of IL‐10 producing T cells (TIL‐10) reactive to col‐V with significantly lower levels of IFN‐γ and IL‐2 producing T cells (Th1 cells). The col‐V specific TIL‐10 cells suppressed the proliferation and expansion of col‐V specific Th1 cells by IL‐10‐dependent and contact‐independent pathways. The TIL‐10 cells were distinct but their development was dependent on the presence of T‐regs. Furthermore, during chronic lung allograft rejection there was a significant decline of TIL‐10 cells with concomitant expansion of col‐V‐specific IFN‐γproducing Th1 cells.

Antibodies to K-α 1 tubulin and collagen V are associated with chronic rejection after lung transplantation.

Bronchiolitis obliterans syndrome (BOS), the clinical correlate of chronic rejection after lung transplantation, is the leading obstacle to better long‐term outcomes. We previously instituted a clinical protocol to screen for donor‐specific human leukocyte antigen (HLA) antibodies (DSA) and a preemptive antibody‐directed therapy protocol consisting of rituximab and/or intravenous immune globulin. In this study, we retrospectively analyzed serum samples from lung transplant recipients (n = 108) for antibodies to self‐antigens (K‐α 1 tubulin and collagen V) before and after antibody‐directed therapy and correlated the results with the subsequent development of BOS. Seventy‐two of the 108 recipients developed antibodies to self‐antigens. There was a correlation between the development of antibodies to self‐antigens and DSA. Sixteen of the 54 patients who had antibodies to self‐antigens and were treated with antibody‐directed therapy cleared the antibodies, and they were significantly less likely to develop BOS than those who had persistent antibodies. Furthermore, those who cleared DSA after treatment but had persistent antibodies to self‐antigens were significantly more likely to develop BOS than those who cleared these antibodies. We conclude that antibodies to self‐antigens are an important risk factor for the development of BOS.

Immune mechanisms in the pathogenesis of bronchiolitis obliterans syndrome after lung transplantation

Abstract:  Lung transplantation is recognized as the only viable treatment option in a variety of end‐stage pulmonary diseases. However, the long‐term survival after lung transplantation is limited by the development of obliterative bronchiolitis, and its clinical correlate bronchiolitis obliterans syndrome (BOS), which is considered to represent chronic lung allograft rejection. Histopathologically, BOS is an inflammatory process that leads to fibrous scarring of the terminal and respiratory bronchioles and subsequent total occlusion of the airways. The specific etiology and pathogenesis of BOS are not well understood. The current premise is that BOS represents a common lesion in which different inflammatory insults such as ischemia‐reperfusion, rejection, and infection can lead to a similar histological and clinical outcome. However, the low incidence of BOS in non‐transplanted individuals and the observation that early development of BOS is predicted by the frequency and severity of acute rejection episodes indicate that alloimmune‐dependent mechanisms play a crucial role in the pathogenesis of BOS. The evidence presented in this review indicates that BOS is the result of humoral and cellular immune responses developed against major histocompatibility complex molecules expressed by airway epithelial cells of the lung allograft. This process is aggravated by alloimmune‐independent mechanisms such as ischemia‐reperfusion and infection. Currently, treatment of BOS is frequently unsuccessful. Therefore, a better understanding of the immunopathogenesis of BOS is of paramount importance toward improving long‐term patient and graft survival after lung transplantation.

The effect of low-potassium-dextran versus Euro-Collins solution for preservation of isolated type II pneumocytes.

Limited availability of donor organs is a major factor restricting the clinical application of lung transplantation. Improvements in preservation techniques are essential for prolonging storage time and improving lung function following transplantation. The present investigation used primary cultures of adult rat alveolar type II cells as a model for evaluating lung-preservation solutions. Type II cells were plated onto tissue-culture plastic at a density 5×105 cells/cm2 and maintained in Dulbeccos modified Eagles medium containing 10% fetal bovine serum (D10) for 40 hr. Cells were then exposed to Euro-Collins solution or a low-potassium-dextran solution (LPD). At designated time points, measurements of lactate-dehydrogenase (LDH) release, protein content, and incorporation of 3H-thymidine into cellular DNA were made. During 12 hr of “storage” at 37°C, cells maintained in LPD released less LDH (14.3± 1.2% of cellular total, mean ±SEM, n=5) than their

Different kinetics of obliterative airway disease development in heterotopic murine tracheal allografts induced by CD4+ and CD8+ T cells.

Background. Both T and B cells have been shown to be implicated in the pathogenesis of bronchiolitis obliterans syndrome, which is considered to represent chronic lung allograft rejection. However, the relative contributions of T cells and alloantibodies in the pathogenesis of the disease are still unknown. In this study, we used an heterotopic murine tracheal transplantation model to determine the contribution of these components of the immune system in the pathogenesis of posttransplant obliterative airway disease (OAD). Methods. Tracheal allografts from BALB/c and HLA-A2-transgenic (HLA-A2+) mice were heterotopically transplanted into C57BL/6, CD4-knockout (KO), CD8-KO, Ig-KO, and Rag1-KO mice. In additional experiments, recipient mice were pretreated with depleting antibodies against CD4+, CD8+, and NK1.1+ cells. Development of OAD was determined by histopathology at days 10, 30, 60, 90, and 180 after transplantation. Results. HLA-A2+ allografts transplanted into C57BL/6, CD8-KO, and Ig-KO mice demonstrated OAD lesions by day 30. In contrast, allografts transplanted into CD4-KO mice showed no OAD lesions at day 30, partial OAD development by days 60 and 90, and complete OAD development by day 180. No OAD development was observed in allografts transplanted into Rag1-KO mice. Treatment with anti-NK1.1 antibody did not show any effect on posttransplant OAD development. In contrast, anti-CD4+ or anti-CD8+ antibody treatments partially reduced the OAD histopathology and combined anti-CD4/CD8 antibody treatment further abrogated the histopathology of the disease. Conclusion. These results show that both CD4+ and CD8+ T cells have a role in the pathogenesis of OAD and that natural killer cells and alloantibodies are not necessary for the development of this disease.