Predictors of Acute Rejection After Lung Transplantation

Center variability in the prognostic value of a cumulative acute cellular rejection "A-score" for long-term lung transplant outcomes

The acute rejection score (A-score) in lung transplant recipients, calculated as the average of acute cellular rejection A-grades across transbronchial biopsies, summarizes the cumulative burden of rejection over time. We assessed the association between A-score and transplant outcomes in 2 geographically distinct cohorts. The primary cohort included 772 double lung transplant recipients. The analysis was repeated in 300 patients from an independent comparison cohort. Time-dependent multivariable Cox models were constructed to evaluate the association between A-score and chronic lung allograft dysfunction or graft failure. Landmark analyses were performed with A-score calculated at 6 and 12 months posttransplant. In the primary cohort, no association was found between A-score and graft outcome. However, in the comparison cohort, time-dependent A-score was associated with chronic lung allograft dysfunction both as a time-dependent variable (hazard ratio, 1.51; P < .01) and when calculated at 6 months posttransplant (hazard ratio, 1.355; P = .031). The A-score can be a useful predictor of lung transplant outcomes in some settings but is not generalizable across all centers; its utility as a prognostication tool is therefore limited.

Differentiation between lung allograft rejection and infection using donor-derived cell-free DNA and pathogen detection by metagenomic next-generation sequencing

Background

In lung transplant recipients (LTRs), the primary causes of mortality are rejection and infection, which often present similar symptoms, making differentiation challenging. This study aimed to explore the diagnostic efficacy of plasma donor-derived cell-free DNA (dd-cfDNA) in conjunction with metagenomic next-generation sequencing (mNGS) for pathogen detection in differentiation between lung allograft rejection and infection in LTRs experiencing new-onset pulmonary complications.

Methods

We conducted a retrospective study on 188 LTRs who underwent lung or heart-lung transplantation at our institution from 2015 to 2021. The LTRs were categorized into three groups: stable, rejection, and infection. We measured plasma dd-cfDNA levels and utilized both mNGS and culture methods to identify pathogens in the bronchoalveolar lavage fluid (BALF).

Results

The rejection group exhibited the highest levels of plasma dd-cfDNA (median 1.34 %, interquartile range [IQR] 1.06-2.19 %) compared to the infection group (median 0.72 %, IQR 0.62-1.07 %) and the stable group (median 0.69 %, IQR 0.58-0.78 %) (both p < 0.001). Within the infection group, a significantly higher level of dd-cfDNA was observed in the cytomegalovirus infection subgroup (p < 0.001), but not in the fungal (p > 0.05) or bacterial infection subgroups (p > 0.05), when compared to the stable group. Elevated dd-cfDNA levels, in combination with negative mNGS results, strongly indicated lung allograft rejection, with a positive predictive value and negative predictive value of 88.7 % and 99.2 %, respectively.

Conclusions

Plasma dd-cfDNA in combination with BALF pathogen detection by mNGS shows satisfactory accuracy in differentiating lung allograft rejection from infectious complications.

Lung Allograft Rejection

Rejection is a major complication following lung transplantation. Acute cellular rejection (ACR), and antibody-mediated rejection (AMR) are risk factors for the subsequent development of chronic lung allograft dysfunction and worse outcomes after transplantation. Although ACR has well-defined histopathologic diagnostic criteria and grading, the diagnosis of AMR requires a multidisciplinary diagnostic approach. This article reviews the identification, clinical and pathologic features of, and therapeutic options for ACR and AMR.

Early postoperative complications in lung transplant recipients

Lung transplantation has become an established therapy for end-stage lung diseases. Early postoperative complications can impact immediate, mid-term, and long-term outcomes. Appropriate management, prevention, and early detection of these early postoperative complications can improve the overall transplant course. In this review, we highlight the incidence, detection, and management of these early postoperative complications in lung transplant recipients.

Acute Rejection in the Modern Lung Transplant Era

Acute cellular rejection (ACR) remains a common complication after lung transplantation. Mortality directly related to ACR is low and most patients respond to first-line immunosuppressive treatment. However, a subset of patients may develop refractory or recurrent ACR leading to an accelerated lung function decline and ultimately chronic lung allograft dysfunction. Infectious complications associated with the intensification of immunosuppression can also negatively impact long-term survival. In this review, we summarize the most recent evidence on the mechanisms, risk factors, diagnosis, treatment, and prognosis of ACR. We specifically focus on novel, promising biomarkers which are under investigation for their potential to improve the diagnostic performance of transbronchial biopsies. Finally, for each topic, we highlight current gaps in knowledge and areas for future research.

Desensitization and management of allograft rejection

PURPOSE OF REVIEW

Chronic lung allograft dysfunction (CLAD) limits the success of lung transplantation. Among the risk factors associated with CLAD, we recognize pretransplant circulating antibodies against the human leukocyte antigens (HLA), acute cellular rejection (ACR) and antibody-mediated rejection (AMR). This review will summarize current data surrounding management of desensitization, ACR, AMR, and CLAD.

RECENT FINDINGS

Strategies in managing in highly sensitized patients waiting for lung transplant include avoidance of specific HLA antigens and reduction of circulating anti-HLA antibodies at time of transplant. Several multimodal approaches have been studied in the treatment of AMR with a goal to clear circulating donor-specific antibodies (DSAs) and to halt the production of new antibodies. Different immunosuppressive strategies focus on influence of the host immune system, particularly T-cell responses, in order to prevent ACR and the progression of CLAD.

SUMMARY

The lack of significant evidence and consensus limits to draw conclusion regarding the impact of specific immunosuppressive regimens in the management of HLA antibodies, ACR, and CLAD. Development of novel therapeutic agents and use of multicenter randomized clinical trials will allow to better define patient-specific treatments and improve the length and quality of life of lung transplant recipients.

Advances in Human Lung Transplantation

Lung transplantation improves survival and quality of life in patients with advanced pulmonary disease. Over the past several decades, the volume of lung transplants has grown substantially, with increasing transplantation of older and acutely ill individuals facilitated by improved utilization and preservation of available donor organs. Other advances include improvements in the diagnosis and mechanistic understanding of frequent post-transplant complications, such as primary graft dysfunction, acute rejection, and chronic lung allograft dysfunction (CLAD). CLAD occurs as a result of the host immune response to the allograft and is the principal factor limiting long-term survival after lung transplantation. Two distinct clinical phenotypes of CLAD have emerged, bronchiolitis obliterans syndrome and restrictive allograft syndrome, and this distinction has enabled further understanding of underlying immune mechanisms. Building on these advances, ongoing studies are exploring novel approaches to diagnose, prevent, and treat CLAD. Such studies are necessary to improve long-term outcomes for lung transplant recipients.

The impact of HLA-DR mismatch status on retransplant-free survival and bronchiolitis obliterans syndrome‒free survival among sensitized lung transplant recipients

INTRODUCTION

Donor‒recipient HLA-DR locus matching may be protective against bronchiolitis obliterans syndrome (BOS) in lung transplant recipients. It is unknown whether this benefit is more significant among sensitized (calculated panel reactive antibodies (CPRAs) of >0%) and highly sensitized (CPRAs of ≥80%) recipients who may be at a higher risk for BOS.

METHODS

This was a retrospective cohort study of adults in the Scientific Registry of Transplant Recipients who underwent lung transplantation between May 5, 2005 and May 31, 2019. Retransplant-free survival and BOS-free survival were compared among recipients with 0 vs ≥1 DR mismatches, grouped according to sensitization.

RESULTS

Among all 20,355 included recipients, 0 DR mismatch status was associated with improved retransplant-free survival (hazard ratio [HR] = 0.83, 95% CI = 0.74-0.93, p = 0.002) and BOS-free survival (HR = 0.86, 95% CI = 0.77-0.96, p = 0.007). Among sensitized recipients, 0 DR mismatch status was also associated with improved retransplant-free survival (HR = 0.79, 95% CI = 0.65-0.97, p = 0.02) and BOS-free survival (HR = 0.82, 95% CI = 0.67-1.00, p = 0.04). There was however no difference in retransplant-free or BOS-free survival between sensitized and non-sensitized recipients with 0 DR mismatches. Among highly sensitized recipients, 0 DR mismatch status was not associated with retransplant-free or BOS-free survival. Among sensitized and highly sensitized recipients, 0 DR mismatch status was not associated with reduced use of plasmapheresis or reduced biopsy-proven, treated acute cellular rejection compared with non-sensitized recipients.

CONCLUSIONS

HLA-DR matching is associated with a similar improvement in retransplant-free and BOS-free survival among non-sensitized and sensitized lung transplant recipients. DR matching does not confer a more substantial retransplant-free or BOS-free survival benefit to highly sensitized recipients than to non-sensitized recipients.

Usefulness of a preoperative inflammatory marker as a predictor of asymptomatic acute rejection after lung transplantation: a Japanese single-institution study

Background

Surveillance bronchoscopy (SB) is performed as routine follow-up after lung transplantation (LTx), primarily for the early detection of clinically asymptomatic acute rejection (AR). To identify appropriate candidates for SB over a long period, we explored risk factors of asymptomatic AR after LTx.

Method

This study is a single-center and retrospective cohort study. Forty-five patients underwent cadaveric LTx between 2000 and 2016 in our institution. All enrolled patients had at least three months of follow-up. SB is scheduled at 1, 2, 3, 6, and 12 months after LTx routinely and annually thereafter until 5 years after LTx. A histological assessment for AR was performed according to the International Society for Heart and Lung Transplantation (ISHLT) criteria. The analysis of potential risk factors for AR was performed using a chi-square test and logistic regression analysis.

Results

The median period of follow-up after LTx for the entire cohort was 64 months. Asymptomatic AR (grade A1-A3) was detected in 22 patients, 14 of whom showed severe AR (worse than grade A2). The percentage of patients with AR was 5–24% at each time point, and 15% of patients still showed severe AR (A2 and A3) at 24 months after LTx. Potential risk factors included recipient factors (diagnosis, age, gender, BMI), donor factors (age, gender, smoking history, cause of brain death), HLA mismatch, operation-related factors, neutrophil-to-leucocyte ratio (NLR), platelet-to-leucocyte ratio (PLR), and other scores. Patients with a higher NLR showed a higher incidence of AR after LTx than others during follow-up (P=0.01).

Conclusions

An increased perioperative NLR was significantly associated with a higher odds ratio of AR during follow-up. Patients with a high NLR seem to be good candidates for long-term SB.

Risk Factors for Acute Rejection in the First Year after Lung Transplant. A Multicenter Study

Rationale: Acute rejection, manifesting as lymphocytic inflammation in a perivascular (acute perivascular rejection [AR]) or peribronchiolar (lymphocytic bronchiolitis [LB]) distribution, is common in lung transplant recipients and increases the risk for chronic graft dysfunction.Objectives: To evaluate clinical factors associated with biopsy-proven acute rejection during the first post-transplant year in a present-day, five-center lung transplant cohort.Methods: We analyzed prospective diagnoses of AR and LB from over 2,000 lung biopsies in 400 newly transplanted adult lung recipients. Because LB without simultaneous AR was rare, our analyses focused on risk factors for AR. Multivariable Cox proportional hazards models were used to assess donor and recipient factors associated with the time to the first AR occurrence.Measurements and Main Results: During the first post-transplant year, 53.3% of patients experienced at least one AR episode. Multivariable proportional hazards analyses accounting for enrolling center effects identified four or more HLA mismatches (hazard ratio [HR], 2.06; P ≤ 0.01) as associated with increased AR hazards, whereas bilateral transplantation (HR, 0.57; P ≤ 0.01) was associated with protection from AR. In addition, Wilcoxon rank-sum analyses demonstrated bilateral (vs. single) lung recipients, and those with fewer than four (vs. more than four) HLA mismatches demonstrated reduced AR frequency and/or severity during the first post-transplant year.Conclusions: We found a high incidence of AR in a contemporary multicenter lung transplant cohort undergoing consistent biopsy sampling. Although not previously recognized, the finding of reduced AR in bilateral lung recipients is intriguing, warranting replication and mechanistic exploration.

Immunosuppressive strategies in lung transplantation

Lung transplantation is a viable option for those with end-stage lung disease which is evidenced by the continued increase in the number of lung transplantations worldwide. However, patients and clinicians are constantly faced with acute and chronic rejection, infectious complications, drug toxicities, and malignancies throughout the lifetime of the lung transplant recipient. Conventional maintenance immunosuppression therapy consisting of a calcineurin inhibitor (CNI), anti-metabolite, and corticosteroids have become the standard regimen but newer agents and modalities continue to be developed. Here we will review induction agents, maintenance immunosuppressives, adjunctive therapies and other strategies to improve long-term outcomes.

A Single Nucleotide C3 Polymorphism Associates With Clinical Outcome After Lung Transplantation

Background: Development of chronic rejection is still a severe problem and causes high mortality rates after lung transplantation (LTx). Complement activation is important in the development of acute rejection (AR) and bronchiolitis obliterans syndrome, with C3 as a key complement factor. Methods: We investigated a single nucleotide polymorphism (SNP) in the C3 gene (rs2230199) in relation to long-term outcome after LTx in 144 patient-donor pairs. In addition, we looked at local production of donor C3 by analyzing bronchoalveolar lavage fluid (BALF) of 6 LTx patients using isoelectric focusing (IEF). Results: We demonstrated the presence of C3 in BALF and showed that this is produced by the donor lung based on the genotype of SNP rs2230199. We also analyzed donor and patient SNP configurations and observed a significant association between the SNP configuration in patients and episodes of AR during 4-years follow-up. Survival analysis showed a lower AR-free survival in homozygous C3 slow patients (p = 0.005). Furthermore, we found a significant association between the SNP configuration in donors and BOS development. Patients receiving a graft from a donor with at least one C3 fast variant for rs2230199 had an inferior BOS-free survival (p = 0.044). Conclusions: In conclusion, our data indicate local C3 production by donor lung cells. In addition, a single C3 SNP present in recipients affects short-term outcome after LTx, while this SNP in donors has an opposite effect on long-term outcome after LTx. These results could contribute to an improved risk stratification after transplantation.

Impact of Donor Diabetes on Outcomes of Lung Transplantation in the United States

BACKGROUND

Diabetes mellitus is among several factors considered when assessing the suitability of donated organs for transplantation. Lungs from diabetic donors (LDD) are not contraindicated for use as allografts, despite established evidence of diabetes-mediated parenchymal damage. The present study used a national database to assess the impact of donor diabetes on the longevity of lung transplant recipients.

METHODS

This retrospective study of the United Network for Organ Sharing database analyzed all adult lung transplant recipients from June 2005 through September 2016. Donor and recipient demographics including the presence of diabetes were used to create a multivariable model. The primary outcome was 5-y mortality, with hazard ratios (HRs) assessed using multivariable Cox regression analysis. Survival curves were calculated using the Kaplan-Meier method.

RESULTS

Of the 17,839 lung transplant recipients analyzed, 1203 (6.7%) received LDD. Recipients of LDD were more likely to be female (44.1% versus 40.2%, P < 0.01) and have mismatched race (47.5% versus 42.2%, P < 0.01). Diabetic donors were more likely to have hypertension (74.6% versus 19.0%, P < 0.01). Multivariable analysis revealed LDD to be an independent predictor of mortality at 5 y (HR 1.16 [1.04-1.29], P < 0.01). However, among the subgroup of diabetic recipients, transplantation of LDD showed no independent association with 5-y mortality (HR 0.81 [0.63-1.06], P = 0.12).

CONCLUSIONS

Recipients of LDD had a lower 5-y post lung transplantation survival compared with recipients of lungs from nondiabetic donors. LDD allografts did not influence the survival of diabetic recipients.

Impact of human leukocyte antigen mismatch on lung transplant outcome

OBJECTIVES

Human leucocyte antigen (HLA) mismatch between donor and recipient has a differential impact on the outcome after transplant (Tx) among transplantable solid organs. Although the lung is considered a highly antigenic organ, the impact of HLA matching between the donor and the recipient has been shown to be heterogeneous on lung Tx outcome. To provide further evidence that HLA matching should be considered in the decision process prior to lung Tx, we evaluated the impact of donor/recipient HLA mismatch on the outcome after lung Tx at our institution.

METHODS

All patients who underwent lung Tx were analysed in this retrospective single-cohort study between 1994 and 2013 for HLA (-A, -B or -DR) matching between the donor and the recipient and their association with overall survival, the incidence of acute cellular rejection (ACR) and the development of chronic lung allograft dysfunction (CLAD).

RESULTS

In total, 371 (197 men) patients were included. Of these, 117 patients had no HLA match (0/6), 143 had a 1/6 match, 77 had 2/6 matches, 28 had 3/6 matches and 6 had 4/6 matches. One hundred and twenty-two (33%) patients experienced at least 1 episode of ACR and 172 (46%) patients developed CLAD. Univariate analysis showed a significant correlation between HLA mismatch and the development of CLAD, whereas multivariate analysis revealed that the number of HLA matches (hazard ratio 0.76; P = 0.002), antibodies to cytomegalovirus in either donors or recipients (hazard ratio 1.52; P = 0.036) and donor age (hazard ratio 1.03; P < 0.001) were independent risk factors for the development of CLAD. On the other hand, HLA matches did not correlate with the incidence of ACR and with the overall survival rate.

CONCLUSIONS

The number of HLA mismatches between donors and recipients after lung Tx did not correlate with ACR or with the overall survival. In contrast, HLA mismatch correlated with the development of CLAD and should therefore be considered a risk factor.

Fear of graft rejection 1-5 years after lung transplantation-A nationwide cohort study

AIM

To explore the perceived threat of the risk of graft rejection and its relationship to psychological general well-being and self-efficacy 1-5 years after lung transplantation.

DESIGN

A nationwide, cross-sectional cohort study as a part of the Self-management after thoracic transplantation study.

METHODS

A total of 117 lung transplant recipients due for their yearly follow-up one (N = 35), two (N = 28), three (N = 23), four (N = 20) and 5 years (N = 11) after lung transplantation were included. We used three instruments; the Perceived Threat of the Risk of Graft Rejection, the Psychological General Well-being and Self-efficacy in chronic illness.

RESULTS

The lung recipients reported an overall low perceived threat of the risk of graft rejection with no gender differences. Intrusive anxiety explained 24.7% of the variance in the PGWB-sum (p ≤ 0.001) and makes a statistically significant (β = -497; p ≤ 0.001) unique contribution to the overall psychological general well-being (95%CI 3.004-1.515).

Pathology of Lung Rejection: Cellular and Humoral Mediated

Acute rejection is an important risk factor for bronchiolitis obliterans syndrome, the clinical manifestation of chronic airway rejection in lung allograft recipients. Patients with acute rejection might be asymptomatic or present with symptoms that are not specific and can be also seen in other conditions. Clinical tests such as pulmonary function tests and imaging studies among others usually are abnormal; however, their results are also not specific for acute rejection. Histopathologic features of acute rejection in adequate samples of transbronchial lung biopsy of the lung allograft are currently the gold standard to assess for acute rejection in lung transplant recipients. Acute alloreactive injury can affect both the vasculature and the airways. Currently, the guidelines of the 2007 International Society of Heart and Lung Transplantation consensus conference are recommended for the histopathologic assessment of rejection. There are no specific morphologic features recognized to diagnose antibody-mediated rejection (AMR) in lung allografts. Therefore, the diagnosis of AMR currently requires a “triple test” including clinical features, serologic evidence of donor-specific antibodies, and pathologic findings supportive of AMR. Complement 4d deposition is used to support a diagnosis of AMR in many solid organ transplants; however, its significance for the diagnosis of AMR in lung allografts is not entirely clear. This chapter discusses the currently recommended guidelines for the assessment of cellular rejection of lung allografts and summarizes our knowledge about morphologic features and immunophenotypic tests that might help in the diagnosis of AMR.

Survival after lung transplantation in recipients with alpha-1-antitrypsin deficiency compared to other forms of chronic obstructive pulmonary disease: a national cohort study

Alpha-1-antitrypsin deficiency (AATD) is grouped with chronic obstructive pulmonary disease (COPD); however, this may not be appropriate. This study assessed whether AATD confers a different prognosis than COPD following lung transplantation. We employed the United Network for Organ Sharing (UNOS) database, grouping patients by diagnoses of AATD or COPD. Kaplan-Meier methods and Cox modeling were performed to determine the association of diagnosis and overall survival. Of 9569 patients, 1394 (14.6%) had a diagnosis of AATD. Patients with AATD who received a single-lung transplant had reduced 1-year survival [adjusted hazard ratio (AHR): 1.68, 95% CI: 1.26, 2.23]. Among patients who received a bilateral lung transplant, there was no significant difference in survival by diagnosis (AHR for AATD as compared to COPD: 0.96, 95% CI: 0.82, 1.12). After the implementation of the lung allocation score (LAS), there was no significant difference in survival among patients who received a single (AHR: 1.15, 95% CI: 0.69, 1.95) or bilateral (AHR: 0.99, 95% CI: 0.73, 1.34) lung transplant by diagnosis. Lung transplantation is increasingly employed in the care of the patient with COPD. Although recipients undergoing LTX for AATD are at increased risk of both acute rejection and airway dehiscence post-transplant, in the post-LAS era, survival rates are similar for recipients with AATD in comparison with COPD.

HLA Matching at the Eplet Level Protects Against Chronic Lung Allograft Dysfunction

Donor selection in lung transplantation (LTx) is historically based upon clinical urgency, ABO compatibility, and donor size. HLA matching is not routinely considered; however, the presence or later development of anti-HLA antibodies is associated with poorer outcomes, particularly chronic lung allograft dysfunction (CLAD). Using eplet mismatches, we aimed to determine whether donor/recipient HLA incompatibility was a significant predictor of CLAD. One hundred seventy-five LTx undertaken at the Alfred Hospital between 2008 and 2012 met criteria. Post-LTx monitoring was continued for at least 12 months, or until patient death. HLA typing was performed by sequence-based typing and Luminex sequence-specific oligonucleotide. Using HLAMatchmaker, eplet mismatches between each donor/recipient pairing were analyzed and correlated against incidences of CLAD. HLA-DRB1/3/4/5+DQA/B eplet mismatch was a significant predictor of CLAD (hazard ratio [HR] 3.77, 95% confidence interval [CI]: 1.71-8.29 p < 0.001). When bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS) were analyzed independently, HLA-DRB1/3/4/5 + DQA/B eplet mismatch was shown to significantly predict RAS (HR 8.3, 95% CI: 2.46-27.97 p < 0.001) but not BOS (HR 1.92, 95% CI: 0.64-5.72, p = 0.237). HLA-A/B eplet mismatch was shown not to be a significant predictor when analyzed independently but did provide additional stratification of results. This study illustrates the importance of epitope immunogenicity in defining donor-recipient immune compatibility in LTx.

De-novo donor-specific anti-HLA antibodies 30 days after lung transplantation are associated with a worse outcome

BACKGROUND

The impact of de-novo donor-specific anti-HLA antibodies (DSA) on patient and graft survival after lung transplantation remains controversial. We analyzed DSA that developed at Day 7 and Month (M) 1, M3, M6 and M12 after lung transplantation and evaluated their impact on chronic lung allograft dysfunction (CLAD) development and survival.

METHODS

One hundred thirty-four patients who underwent lung transplantation at our institution between November 2007 and August 2013 were included in this study. During the first post-transplant year, 82 (61%) patients developed de novo DSA and 52 (39%) patients did not. Three mean fluorescence intensity (MFI) intervals were used to define scores of anti-HLA antibody positivity: score 4 if MFI was 500 to 1,000; score 6 if MFI was 1,000 to 3,000; and score 8 if MFI was ≥3,000. Patients' records were retrospectively reviewed.

RESULTS

DSA with MFI scores of ≥4 (hazard ratio [HR] 2.21, 95% confidence interval [CI] 1.08 to 4.54, p = 0.03), 6 (HR 2.63, 95% CI 1.27 to 5.20, p < 0.01) and 8 (HR 2.83, 95% CI 1.42 to 5.67, p < 0.01) at M1; female gender (HR 0.49, 95% CI 0.28 to 0.87, P = 0.01); and with post-operative extracorporeal membrane oxygenation (HR 0.09, 95% CI 0.01 to 0.28, p = 0.02) were significantly associated with CLAD. Multivariate analysis identified score 8 at M1 (HR 2.71, 95% CI 1.34 to 5.47, p < 0.01) as an independent risk factor for mortality. Overall, 1-, 3- and 5-year survival rates were 76%, 52% and 41% compared with 84%, 74% and 70% for patients with or without de-novo DSA at M1, respectively (p = 0.02).

CONCLUSION

Early de-novo DSA may significantly impact long-term outcomes after lung transplantation and should therefore prompt regular screening.

Timing and Frequency of Unplanned Readmissions After Lung Transplantation Impact Long-Term Survival

BACKGROUND

Adverse events that require hospital readmission frequently occur long after lung transplantation (LT) that has been successfully performed. We sought to identify the causes and rate of unplanned readmissions after LT and to determine whether unplanned readmissions have a significant impact on post-LT survival.

METHODS

We retrospectively reviewed the outcomes in 174 LT recipients who underwent LT at our center from June 2005 to May 2014. The median follow-up period was 38 months (range, 17 to 72 months).

RESULTS

One hundred sixty (92%) of the 174 recipients were readmitted 854 times (5.3 times per patient). The median time to first readmission was 71 days (interquartile range [IQR], 28 to 240 days), and the median hospital length of stay at readmission was 3 days (IQR, 2 to 6 days). Freedom from first readmission was observed for 65% of patients at 1 month, 48% at 3 months, 43% at 6 months, and 26% at 12 months. Gender, lung allocation score, body surface area, year of transplantation, air leak longer than 5 days after operation, and allograft function were risk factors for readmission. The causes of readmission included infections (33%), respiratory adverse events (18%), rejection (15%), gastrointestinal events (15%), renal dysfunction (5%), and cardiac events (4%). Patients who died were found to have had early readmissions (p = 0.04) and more frequent readmissions (p = 0.001).

CONCLUSIONS

The first year after LT remains a high-risk period for unplanned readmissions regardless of pretransplantation diagnosis. Readmissions soon after discharge at index hospitalization and multiple readmissions are associated with an increased risk of mortality.

Outcomes of minimally invasive lung transplantation in a single centre: the routine approach for the future or do we still need clamshell incision?

OBJECTIVES

Minimally invasive lung transplantation (MILT) via bilateral anterior thoracotomies has emerged as a novel surgical strategy with potential patient benefits when compared with transverse thoracosternotomy (clamshell incision, CS). The aim of this study is to compare MILT with CS by focusing on operative characteristics, postoperative organ function and support and mid-term clinical outcomes at Harefield Hospital.

METHODS

It was a retrospective observational study evaluating all bilateral sequential lung transplants between April 2010 and November 2013.

RESULTS

CS was performed in 124 patients and MILT in 70 patients. Skin-to-skin surgical time was less in the MILT group [285 (265, 339) min] compared with CS [380 (306, 565) min] and MILT-cardiopulmonary bypass [426 (360, 478) min]. Ischaemic time was significantly longer (502 ± 116 vs 395 ± 145 min) in the MILT group compared with CS (P < 0.01). Early postoperative physiological variables were similar between groups. Patients in the MILT group required less blood [2 (0, 4) vs 3 (1, 5) units, P = 0.16] and platelet transfusion [0 (0, 1) vs 1 (0, 2) units, P < 0.01]. The median duration of mechanical ventilation was shorter (26 vs 44 h, P < 0.01) and intensive therapy unit stay was 2 days shorter (5 vs 7) in the MILT group. While overall survival was similar, fraction of expired volume in 1 s (FEV1) and forced vital capacity (FVC) were consistently higher in the MILT group compared with CS during mid-term follow-up after transplantation. Specifically, FEV1 and FVC were, respectively, 86 ± 21 and 88 ± 18% predicted in the MILT group compared with 74 ± 21 and 74 ± 19% predicted in the CS group (P < 0.01) at the 6-month follow-up.

CONCLUSIONS

MILT was successfully introduced at our centre as a novel operative strategy. Despite longer ischaemic times and a more complex operation and management, MILT appears to offer early postoperative and mid-term clinical benefits compared with our traditional approach of clamshell operations. These observations warrant larger definite studies to further evaluate the impact of MILT on physiological, clinical and patient-reported outcomes.

Future direction of immunosuppression in lung transplantation

PURPOSE OF REVIEW

Immunosuppression regimens have helped improve rejection episodes following lung transplantation, but long-term outcomes are still not comparable with cardiac, hepatic, or renal transplantation. This review summarizes the immunobiology that contributes to rejection events and future opportunities in outcomes on the basis of providing optimized delivery of the immunosuppression based on immune-monitoring techniques, taking into account individual patient pharmacokinetics and phenotypic variance.

RECENT FINDINGS

Drug toxicities, narrow therapeutic drug monitoring windows, and current immunoassays currently do not assist in detecting the global degree of immunosuppression. The currently available randomized control trials for induction therapy or maintenance therapies do not provide additional benefits compared with previously reported retrospective trials. To push beyond the current barriers, transplant teams are focusing on the role of pharmacokinetics, assessing phenotypic variable to potentially modify to quadruple therapy and using extracorporeal photopheresis.

SUMMARY

Conventional practice for the choices of immunosuppression is being evaluated on the basis of randomized control trials as opposed to retrospective studies or single-center trials. The future direction of immunosuppression will be continued by dynamic processes taking into consideration measures to improve tolerance, reducing treatment burden, and providing the best level of evidence while accounting for rejection, infections, renal function, and other comorbidities.

Preemptive treatment with therapeutic plasma exchange and rituximab for early donor-specific antibodies after lung transplantation

OBJECTIVE

De novo donor-specific anti-human leukocyte antigen antibodies develop in a high proportion of lung transplant recipients early after lung transplantation. We recently showed that de novo donor-specific antibodies (DSA) occurrence is associated with significantly increased mortality. Here, we studied the efficacy of a preemptive treatment protocol.

METHODS

A retrospective observational study was conducted on all lung transplantations at Hanover Medical School between January 2009 and May 2013.

RESULTS

Among the 500 transplant recipients, early DSA developed in 86 (17%). Of these, 56 patients (65%; Group A) received therapeutic plasma exchange, and 30 patients (35%; Group B) did not. Among Group A patients, 51 also received rituximab. Between groups, there was no statistically significant difference in mortality, incidence of pulsed steroid therapies, rejections diagnosed by biopsy specimen, incidence of bronchitis obliterans syndrome (BOS), or infections requiring hospitalization at 1 year and 3 years. Also, there were no statistically significant differences after matching 21 Group A with 21 Group B patients through propensity score analysis. Significantly more Group A patients (65%) than Group B patients (34%) cleared DSA at hospital discharge (p = 0.01). At the last control after transplantation (median, 14 months; interquartile range, 5-24 months), 11 Group A (22%) and 9 Group B patients (33%) still showed DSA (p = 0.28).

CONCLUSIONS

Preemptive treatment with therapeutic plasma exchange and rituximab led to improved elimination of DSA early after lung transplantation (p = 0.01). However, spontaneous elimination in untreated Group B patients also occurred frequently. This treatment protocol was not associated with significantly improved outcome.

Pre-transplant impedance measures of reflux are associated with early allograft injury after lung transplantation

BACKGROUND

Acid reflux has been associated with poorer outcomes after lung transplantation. Standard pre-transplant reflux assessment has not been universally adopted. Non-acid reflux may also induce a pulmonary inflammatory cascade, leading to acute and chronic rejection. Esophageal multichannel intraluminal impedance and pH testing (MII-pH) may be valuable in standard pre-transplant evaluation. We assessed the association between pre-transplant MII-pH measures and early allograft injury in lung transplant patients.

METHODS

This was a retrospective cohort study of lung transplant recipients who underwent pre-transplant MII-pH at a tertiary center from 2007 to 2012. Results from pre-transplant MII-pH, cardiopulmonary function testing, and results of biopsy specimen analysis of the transplanted lung were recorded. Time-to-event analyses were performed using Cox proportional hazards and Kaplan-Maier methods to assess the associations between MII-pH measures and development of acute rejection or lymphocytic bronchiolitis.

RESULTS

Thirty patients (46.7% men; age, 54.2 years) met the inclusion criteria. Pre-transplant cardiopulmonary function and pulmonary diagnoses were similar between outcome groups. Prolonged bolus clearance (hazard ratio [HR], 4.11; 95% confidence interval [CI], 1.34-12.57; p = 0.01), increased total distal reflux episodes (HR, 4.80; 95% CI, 1.33-17.25; p = 0.02), and increased total proximal reflux episodes (HR, 4.43; 95% CI, 1.14-17.31; p = 0.03) were significantly associated with decreased time to early allograft injury. Kaplan-Meier curves also demonstrated differences in time to rejection by prolonged bolus clearance (p = 0.01) and increased total distal reflux episodes (p = 0.01). Sub-group analysis including only patients with MII-pH performed off proton pump inhibitors (n = 24) showed similar results.

CONCLUSIONS

Prolonged bolus clearance, increased total distal reflux episodes, and increased total proximal reflux episodes on pre-transplant MII-pH were associated with decreased time to early allograft injury after lung transplantation. Routine pre-transplant MII-pH may provide clinically relevant data regarding transplant outcomes and peri-transplant care.

Early donor-specific antibodies in lung transplantation: risk factors and impact on survival

BACKGROUND

The impact of early donor-specific anti-HLA antibodies (DSA) on patient and graft survival after lung transplantation remains controversial. In this study we analyzed risk factors for DSA that developed before initial hospital discharge after lung transplantation (early DSA) and compared mid-term outcomes in patients with or without DSA.

METHODS

Between January 2009 and August 2013, 546 patients underwent lung transplantation at our institution. One hundred (18%) patients developed early DSA (Group A) and 446 (82%) patients (Group B) did not. Patient records were retrospectively reviewed.

RESULTS

Retransplantation (odds ratio [OR] = 2.7, 95% confidence interval [CI] 1.1 to 6.5, p = 0.03), pre-operative HLA antibodies (OR = 2.1, 95% CI 1.2 to 3.4, p = 0.003) and primary graft dysfunction (PGD) score Grade 2 or 3 at 48 hours (OR = 2.6, 95% CI 1.5 to 4.6, p = 0.001) were associated with early DSA development. Overall, 1- and 3-year survival in Group A and B patients was 79 ± 4% vs 88 ± 2% and 57 ± 8% vs 74 ± 3%, respectively (p = 0.019). Eleven Group A (11%) and 32 Group B (7%) patients died before hospital discharge (p = 0.34). Among patients surviving beyond discharge, 1- and 3-year survival in Group A and B patients was 89 ± 4% vs 95 ± 1% and 65 ± 8% vs 80 ± 3% in Group A and B patients, respectively (p = 0.04). Multivariate analysis identified early anti-HLA Class II DSA (OR = 1.9, 95% CI 1.0 to 3.4, p = 0.04) as an independent risk factor for post-discharge mortality but not for in-hospital mortality.

CONCLUSIONS

Pre-operative HLA antibodies, retransplantation or post-operative PGD increase the risk of developing early DSA, which were independently associated with an increased risk for mortality.

Mechanistic differences between phenotypes of chronic lung allograft dysfunction after lung transplantation

Distinct phenotypes of chronic lung allograft dysfunction (CLAD) after lung transplantation are emerging with lymphocytic bronchiolitis (LB)/azithromycin reversible allograft dysfunction (ARAD), classical or fibrotic bronchiolitis obliterans syndrome (BOS), and restrictive allograft syndrome (RAS) proposed as separate entities. We have additionally identified lung transplant recipients with prior LB, demonstrating persistent airway neutrophilia (PAN) despite azithromycin treatment. The aim of this study was to evaluate differences in the airway microenvironment in different phenotypes of CLAD. Bronchoalveolar lavage (BAL) from recipients identified as stable (control), LB/ARAD, PAN, BOS, and RAS were evaluated for differential cell counts and concentrations of IL-1α, IL-1β, IL-6, IL-8, and TNF-α. Primary human bronchial epithelial cells were exposed to BAL supernatants from different phenotypes and their viability measured. BOS and RAS showed increased BAL neutrophilia but no change in cytokine concentrations compared with prediagnosis. In both LB/ARAD and PAN, significant increases in IL-1α, IL-1β, and IL-8 were present. BAL IL-6 and TNF-α concentrations were increased in PAN and only this phenotype demonstrated decreased epithelial cell viability after exposure to BAL fluid. This study demonstrates clear differences in the airway microenvironment between different CLAD phenotypes. Systematic phenotyping of CLAD may help the development of more personalized approaches to treatment.

Transplantation genetics: current status and prospects

Over the last decade, advances in genetic technologies have accelerated our understanding of the genetic diversity across individuals and populations. Case-control and population-based studies have led to several thousand genetic associations across a range of phenotypes and traits being unveiled. Despite widespread and successful use of organ transplantation as a curative therapy for organ failure, genetic research has yet to make a major impact on transplantation practice aside from HLA matching. New studies indicate that non-HLA loci, termed minor histocompatibility antigens (mHAs), may play an important role in graft rejection. With several million common and rare polymorphisms observed between any two unrelated individuals, a number of these polymorphisms represent mHAs, and may underpin transplantation rejection. Genetic variation is also recognized as contributing to clinical outcomes including response to immunosuppressants, introducing the possibility of genotype-guided prescribing in the very near future. This review summarizes existing knowledge of the impact of genetics on transplantation outcomes and therapeutic responses, and highlights the translational potential that new genomic knowledge may bring to this field.

Aktueller Stand der Lungentransplantation

Die Lungentransplantation ist eine akzeptierte Behandlungsmethode für ausgewählte Patienten mit Lungenerkrankungen im Endstadium. Durch die Transplantation können die Überlebenszeit und die Lebensqualität der Betroffenen verbessert werden. Sowohl pulmonale als auch nichtpulmonale Komplikationen beeinträchtigen die Kurz- und die Langzeitergebnisse. Entscheidend bei der Therapie dieser Komplikationen sind das frühzeitige Erkennen und die schnelle Behandlung zur Verhinderung von sekundären Folgekomplikationen. Dieser Beitrag gibt einen Überblick über die häufigsten Probleme der Lungentransplantation, die im peri- und postoperativen Verlauf auftreten können.

Consensus guidelines on the testing and clinical management issues associated with HLA and non-HLA antibodies in transplantation

BACKGROUND

The introduction of solid-phase immunoassay (SPI) technology for the detection and characterization of human leukocyte antigen (HLA) antibodies in transplantation while providing greater sensitivity than was obtainable by complement-dependent lymphocytotoxicity (CDC) assays has resulted in a new paradigm with respect to the interpretation of donor-specific antibodies (DSA). Although the SPI assay performed on the Luminex instrument (hereafter referred to as the Luminex assay), in particular, has permitted the detection of antibodies not detectable by CDC, the clinical significance of these antibodies is incompletely understood. Nevertheless, the detection of these antibodies has led to changes in the clinical management of sensitized patients. In addition, SPI testing raises technical issues that require resolution and careful consideration when interpreting antibody results.

METHODS

With this background, The Transplantation Society convened a group of laboratory and clinical experts in the field of transplantation to prepare a consensus report and make recommendations on the use of this new technology based on both published evidence and expert opinion. Three working groups were formed to address (a) the technical issues with respect to the use of this technology, (b) the interpretation of pretransplantation antibody testing in the context of various clinical settings and organ transplant types (kidney, heart, lung, liver, pancreas, intestinal, and islet cells), and (c) the application of antibody testing in the posttransplantation setting. The three groups were established in November 2011 and convened for a "Consensus Conference on Antibodies in Transplantation" in Rome, Italy, in May 2012. The deliberations of the three groups meeting independently and then together are the bases for this report.

RESULTS

A comprehensive list of recommendations was prepared by each group. A summary of the key recommendations follows. Technical Group: (a) SPI must be used for the detection of pretransplantation HLA antibodies in solid organ transplant recipients and, in particular, the use of the single-antigen bead assay to detect antibodies to HLA loci, such as Cw, DQA, DPA, and DPB, which are not readily detected by other methods. (b) The use of SPI for antibody detection should be supplemented with cell-based assays to examine the correlations between the two types of assays and to establish the likelihood of a positive crossmatch (XM). (c) There must be an awareness of the technical factors that can influence the results and their clinical interpretation when using the Luminex bead technology, such as variation in antigen density and the presence of denatured antigen on the beads. Pretransplantation Group: (a) Risk categories should be established based on the antibody and the XM results obtained. (b) DSA detected by CDC and a positive XM should be avoided due to their strong association with antibody-mediated rejection and graft loss. (c) A renal transplantation can be performed in the absence of a prospective XM if single-antigen bead screening for antibodies to all class I and II HLA loci is negative. This decision, however, needs to be taken in agreement with local clinical programs and the relevant regulatory bodies. (d) The presence of DSA HLA antibodies should be avoided in heart and lung transplantation and considered a risk factor for liver, intestinal, and islet cell transplantation. Posttransplantation Group: (a) High-risk patients (i.e., desensitized or DSA positive/XM negative) should be monitored by measurement of DSA and protocol biopsies in the first 3 months after transplantation. (b) Intermediate-risk patients (history of DSA but currently negative) should be monitored for DSA within the first month. If DSA is present, a biopsy should be performed. (c) Low-risk patients (nonsensitized first transplantation) should be screened for DSA at least once 3 to 12 months after transplantation. If DSA is detected, a biopsy should be performed. In all three categories, the recommendations for subsequent treatment are based on the biopsy results.

CONCLUSIONS

A comprehensive list of recommendations is provided covering the technical and pretransplantation and posttransplantation monitoring of HLA antibodies in solid organ transplantation. The recommendations are intended to provide state-of-the-art guidance in the use and clinical application of recently developed methods for HLA antibody detection when used in conjunction with traditional methods.