Acute Rejection and Antibody-Mediated Rejection in Lung Transplantation

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 Transplantation: A Viable Option for Connective Tissue Disease?

Interstitial lung disease (ILD) and pulmonary hypertension (PH) caused by connective tissue disease (CTD) are one of the main causes of morbidity and death in patients. Although the International Society for Heart & Lung Transplant suggested that ILD and PH related to CTD are rare indications for lung transplantation in 2006, many lung transplantation centers are concerned that the multisystem involvement of CTD will affect survival outcomes after lung transplantation, and CTD is regarded as a relative contraindication for lung transplantation. However, long-term and short-term survival after lung transplantation in CTD patients is similar compared with survival in common indications for lung transplantation such as idiopathic pulmonary fibrosis (IPF), and no higher incidence of complications after transplantation in many lung transplant centers. This suggests that lung transplantation may be beneficial in CTD patients with disease that progresses to end-stage lung disease, and CTD should not be considered a contraindication for lung transplantation. In the future, more prospective studies are needed to analyze the risk factors of lung transplantation in CTD patients to improve survival rates and reduce the risk of complications. This narrative review summarizes the selection and evaluation of candidates for CTD before lung transplantation and describes the clinical outcomes in CTD after lung transplantation in large-capacity lung transplantation center. The purpose of this review is to help rheumatologists decide when to refer patients with CTD-related lung involvement to a lung transplantation center and the conditions to consider before transplantation and to provide confidence to lung transplant experts.

Anti-CD20 Antibody and Calcineurin Inhibitor Combination Therapy Effectively Suppresses Antibody-Mediated Rejection in Murine Orthotopic Lung Transplantation

Antibody-mediated rejection (AMR) is a risk factor for chronic lung allograft dysfunction, which impedes long-term survival after lung transplantation. There are no reports evaluating the efficacy of the single use of anti-CD20 antibodies (aCD20s) in addition to calcineurin inhibitors in preventing AMR. Thus, this study aimed to evaluate the efficacy of aCD20 treatment in a murine orthotopic lung transplantation model. Murine left lung transplantation was performed using a major alloantigen strain mismatch model (BALBc (H-2d) → C57BL/6 (BL/6) (H-2b)). There were four groups: isograft (BL/6→BL/6) (Iso control), no-medication (Allo control), cyclosporine A (CyA) treated, and CyA plus murine aCD20 (CyA+aCD20) treated groups. Severe neutrophil capillaritis, arteritis, and positive lung C4d staining were observed in the allograft model and CyA-only-treated groups. These findings were significantly improved in the CyA+aCD20 group compared with those in the Allo control and CyA groups. The B cell population in the spleen, lymph node, and graft lung as well as the levels of serum donor-specific IgM and interferon γ were significantly lower in the CyA+aCD20 group than in the CyA group. Calcineurin inhibitor-mediated immunosuppression combined with aCD20 therapy effectively suppressed AMR in lung transplantation by reducing donor-specific antibodies and complement activation.

Rabbit Antithymocyte Globulin for Treatment of Corticosteroid Refractory Acute Cellular Rejection After Lung Transplantation

BACKGROUND

Chronic lung allograft dysfunction (CLAD) remains a major cause of death after the first year posttransplant, with acute cellular rejection (ACR) being a major risk factor for CLAD. We evaluated the use of rabbit antithymocyte globulin (rATG) for corticosteroid refractory ACR in lung transplant recipients.

METHODS

We retrospectively identified 112 adult lung transplant recipients who received rATG for refractory ACR after lung transplantation. The primary endpoint was the incidence of ACR on follow-up transbronchial biopsy. Secondary endpoints included freedom from ACR within 1 y post-rATG, CLAD progression at 1 y post-rATG, and all-cause mortality at 1 y post-rATG.

RESULTS

A complete resolution of ACR was observed in 60.2% of patients, an improvement but not complete resolution in 22.1%, and no response on follow-up biopsy in 17.8%. Mean A grade 1 y post-rATG was 0.51 in complete responders, 1.01 in partial responders, and 2.19 in nonresponders ( P  < 0.001). Complete responders had significantly less new or worsening CLAD at 1 y than partial responders (17% versus 40%; P  = 0.02). All-cause mortality rate was 14.9% in complete responders, 40% in partial responders, and 30% in nonresponders ( P  < 0.01).

CONCLUSIONS

rATG appears to be an effective treatment of refractory ACR in lung transplant recipients. Failure to respond to rATG carries an increased risk of early CLAD and death.

Metagenomic Next-Generation Sequencing for Diagnosing Infections in Lung Transplant Recipients: A Retrospective Study

Background: Accurate identification of pathogens is essential for the diagnosis and control of infections. We aimed to compare the diagnostic performance of metagenomic next-generation sequencing (mNGS) and conventional detection methods (CDM) in lung transplant recipients (LTRs).

Methods: We retrospectively analyzed 107 LTRs with suspected infection of pulmonary, blood, central nervous system or chest wall between March 2018 and November 2020. Bronchoalveolar lavage fluid and other body fluids were subject to pathogen detection by both mNGS and CDM.

Results: Of the 163 specimens, 84 (51.5%) tested positive for both mNGS and culture, 19 (11.7%) of which were completely consistent, 44 (27.0%) were partially congruent, and 21 (12.9%) were discordant (kappa = .215; p = .001). Compared with CDM, mNGS detected a higher diversity of pathogens. Moreover, the turn-around time was significantly shorter for mNGS compared with culture (2.7 ± .4 vs. 5.5 ± 1.6 days, p &lt; .001). As an auxiliary method, treatment strategies were adjusted according to mNGS findings in 31 cases (29.0%), including eight patients with non-infectious diseases, who were finally cured.

Conclusion: mNGS can identify pathogens with a shorter turn-around time and therefore provide a more accurate and timely diagnostic information to ascertaining pulmonary infections. mNGS might have a role in differentiating infectious from non-infectious lung diseases in LTRs.

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.

Assessment of Carfilzomib Treatment Response in Lung Transplant Recipients With Antibody-mediated Rejection

Supplemental Digital Content is available in the text.

Data supporting the use of carfilzomib (CFZ) for treatment of antibody-mediated rejection (AMR) in lung transplantation in combination with plasmapheresis and intravenous immunoglobulin suggest positive outcomes through donor-specific antibody (DSA) depletion or conversion to noncomplement-activating antibodies. Herein, we describe our center’s experience treating AMR with CFZ.

Cellular and humoral cytomegalovirus immunity changes in one-year combined prophylaxis after lung transplantation: suggestions from and for clinical practice

Background:

Immune responses, both cellular and humoral, against cytomegalovirus (CMV) are used to predict CMV manifestations in solid organ recipients. The aim of this study is to evaluate CMV enzyme-linked immunospot (ELISPOT) assay and serology during CMV infections, their concordance and variations after lung transplantation (LTx).

Methods:

We retrospectively analysed in one year the follow-up data of 43 patients receiving combined CMV prophylaxis with antiviral agents and CMV-specific immunoglobulin G (IgG). CMV infections were investigated by using molecular analyses on both 167 bronchoalveolar lavage and biopsy specimens and 1134 blood samples. Cellular CMV immunity was assessed with specific ELISPOT whereas the humoral one was assessed by quantifying specific immunoglobulins.

Results:

At the first month after LTx the majority of patients were ELISPOT responders (52.3%) and 30.9% were non-responders. ELISPOT responders had a lower incidence of CMV viremia (p = 0.047), whereas neither effects on CMV pulmonary asymptomatic infection nor on acute rejection were observed. Responders had a higher CMV IgG titre (p < 0.0001) in particular at the first month after LTx (p = 0.0001). Concordance among CMV ELISPOT assay and IgG levels was moderate (Cohen’s K 0.524), with an agreement of 89.8%. All ELISPOT responders maintained their status and almost all non-responders became responders during follow-up (92.3%); the percentage of IgG seropositive subjects increased from 74.4% at the first month of follow-up to 97.4% after 1 year.

Conclusions:

Despite a moderate concordance with serology, ELISPOT response predicted a lower incidence of CMV viremia in LTx patients; no effects were reported on pulmonary clinical manifestations nor on acute rejection. The ELISPOT response as well as serology changed during the follow-up, not only after first CMV contact.

The reviews of this paper are available via the supplemental material section.

Video Consultation During the COVID-19 Pandemic: A Single Center's Experience with Lung Transplant Recipients

Background: The coronavirus disease 2019 (COVID-19) pandemic has disrupted health care systems worldwide. This is due to both to the reallocation of resources toward COVID-19 patients as well as concern for the risk of nosocomial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure. The interruption of routine care is especially problematic for patients with chronic conditions requiring regular follow-up, such as lung transplant (LTx) recipients. Introduction: New methods such as telemedicine are needed to bridge the gap in follow-up care caused by the pandemic. Materials and Methods: A retrospective analysis of video consultations (VCs) in comparison with on-site visits (OSVs) was performed during a 6-week period in an LTx center in Germany. VC included a structured work-up questionnaire and vital sign documentation. Results: During the 6-week study period, 75 VCs were performed for 53 patients and 75 OSVs by 51 patients occurred. By the end of our study period, 77% of physician-patient contacts occurred through VC. Physician-patient consultations were reduced by 47% compared with the equivalent time frame in 2019. In 62% of cases, VC resulted in a concrete clinical decision. One COVID-19 patient in home quarantine was admitted due to respiratory failure detected by VC. Patient satisfaction with VC was high. Discussion: Implementation of VC helped to reduce the need for OSV and thus the risk of SARS-CoV-2 exposure in our patient cohort. This technology can be adopted to provide care for a wide range of chronic illnesses. Conclusions: VC can preserve access to specialist care while reducing SARS-CoV-2 exposure for patients with chronic illnesses during the pandemic.

Tacrolimus monitoring parameters are not associated with acute cellular rejection following lung transplantation

PURPOSE

The purpose of this study was to evaluate the impact of tacrolimus drug monitoring parameters on the incidence of acute cellular rejection (ACR) in lung transplant recipients (LTRs).

METHODS

This was a retrospective study of patients who underwent lung transplantation at a single center. LTRs who were given tacrolimus during the first 6 months after transplantation and who underwent at least one bronchoscopy with biopsy were included. Tacrolimus time in therapeutic range (TTR) was calculated using Rosendaal's method. Time to therapeutic level, coefficient of variance (CoV), and median trough concentrations were also determined.

RESULTS

The study included 157 LTRs. ACR ≥ A1 grade was present in 46.5% of patients, and ACR ≥ A2 grade was present in 17.2%. There was no difference between tacrolimus TTR in patients with ACR ≥ A1 compared with those without ACR (47.4 ± 16.1 versus 46.2 ± 18.9%, p = 0.67) or in patients with ACR ≥ A2 grade compared with those with A0 or A1 ACR (46.0 ± 16.3 versus 47.0 ± 17.9%, p = 0.81). When comparing patients with any ACR grade A1 or higher with those without ACR, there was no difference in tacrolimus CoV (42.7 ± 11.0 versus 44.6 ± 12.4, p = 0.30), median tacrolimus trough concentration (9.9 ± 1.3 versus 9.8 ± 1.4 ng/mL, p = 0.66), or days to therapeutic level (9 versus 12 days, p = 0.057).

CONCLUSIONS

The results suggest that tacrolimus TTR, time in therapeutic range, and variability are not related to the presence of ACR in LTRs.

Antibody-mediated rejection after lung transplantation

Antibody-mediated rejection (AMR) has been identified as a significant form of acute allograft dysfunction in lung transplantation. The development of consensus diagnostic criteria has created a uniform definition of AMR; however, significant limitations of these criteria have been identified. Treatment modalities for AMR have been adapted from other areas of medicine and data on the effectiveness of these therapies in AMR are limited. AMR is often refractory to these therapies, and graft failure and death are common. AMR is associated with increased rates of chronic lung allograft dysfunction (CLAD) and poor long-term survival. In this review, we discuss the history of AMR and describe known mechanisms, application of the consensus diagnostic criteria, data for current treatment strategies, and long-term outcomes. In addition, we highlight current gaps in knowledge, ongoing research, and future directions to address these gaps. Promising diagnostic techniques are actively being investigated that may allow for early detection and treatment of AMR. We conclude that further investigation is required to identify and define chronic and subclinical AMR, and head-to-head comparisons of currently used treatment protocols are necessary to identify an optimal treatment approach. Gaps in knowledge regarding the epidemiology, mechanisms, diagnosis, and treatment of AMR continue to exist and future research should focus on these aspects.

Comparison of outcomes in lung and heart transplant recipients from the same multiorgan donor

BACKGROUND

Primary graft dysfunction (PGD) and acute cellular rejection (ACR) are important causes of early morbidity and mortality following lung and heart transplantation. While many studies have elucidated donor-related risk factors of PGD and ACR, these complications often occur even with "ideal" donors. Therefore, we investigated potential associations of PGD and ACR between bilateral lung and heart transplant recipients from the same multiorgan donor, respectively.

METHODS

Between 2011 and 2017, 100 donors contributed 100 bilateral lung transplants and 100 heart transplants performed. Logistic regression analysis for PGD and Cox proportional hazards regression analysis for ACR were used to estimate the relationship of heart and lung transplants.

RESULTS

The incidence of PGD was 33% among lung and 17% among heart transplant recipients. Similarly, the incidence of ACR grade ≥ A2 for lung recipients was 38% (30/80), and the incidence of ACR grade ≥ 2R for heart recipients was 19% (15/80). There was no association between the development of PGD and ACR in lung and heart transplant recipients from the same donor, respectively.

CONCLUSIONS

These findings suggest that inherent donor factors are not critical to the development of PGD and ACR after lung and heart transplantation.

Acute cellular rejection in lung transplantation

Lung transplantation is an important therapy for end-stage respiratory failure in patients who have exhausted other therapeutic options. The lung is unique among solid-organ transplants in that it is exposed to the outside environment, and undergoes continuous stimulation from infectious and non-infectious agents, which may play a part in upregulating the immune response to the allograft. Despite induction immunosuppression and the use of aggressive maintenance regimens, acute allograft rejection is still a major problem, especially in the first year after transplant, with important diagnostic and therapeutic challenges. As well as being responsible for early graft failure and death, acute rejection also initiates alloimmune responses that predispose patients to chronic lung allograft dysfunction, in particular bronchiolitis obliterans syndrome. Cellular responses to human leukocyte antigens (HLAs) on the allograft have traditionally been considered the main mechanism of acute rejection, although the influence of humoral immunity is increasingly recognised. Here, we present two cases of acute cellular rejection (ACR) in the early post-transplant period and review the pathophysiology, diagnosis, clinical presentation and treatment of ACR.

Human lung tissue resident memory T cells in health and disease

The human lung contains a heterogeneous population of immune cells which mediate protective responses, maintain tissue homeostasis, but can also promote immunopathology in disease. The majority of T cells in the human lung are tissue resident memory T cells (T_RM) which have been shown in mouse models to provide vital roles in the protection against multiple respiratory pathogens, and contribute to heterosubtypic protection in the context of vaccination. In this review, we will discuss recent studies in humans identifying lung TRM, their role in maintaining tissue homeostasis, and emerging evidence implicating T_RM in anti-tumor immunity and immune surveillance as well as their potential for immunopathology in chronic airway inflammation.

Lung Transplantation

Lung transplantation is an appropriate therapeutic option for select patients with end-stage lung diseases and offers the possibility of improved quality of life and longer survival. Unfortunately, the transplant recipient is at risk for numerous immunologic, infectious, and medical complications that threaten both of these goals. Median survival after lung transplantation is approximately 6 years. Optimizing outcomes requires close partnership between the patient, transplant center, and primary medical team. Early referral to a transplant center should be considered for patients with idiopathic pulmonary fibrosis and related interstitial lung diseases due to risk of acute exacerbation and accelerated development of respiratory failure.