Outcomes with alemtuzumab induction therapy in lung transplantation: a comprehensive large-scale single-center analysis

[Immunological Aspects after Lung Transplantation]

Since the 1980 s, lung transplantation has evolved into an established therapeutic procedure, due to advancements in surgical techniques and the introduction of immunosuppressants such as cyclosporine. Despite improved short-term outcomes, the long-term prognosis remains limited, primarily due to immunological complications. With a median survival of approximately six years, the lung is the most immunogenic solid organ, owing to its constant exposure to environmental antigens and its extensive vascular endothelial surface. After lung transplantation, various forms of alloreactivity, including T cell-mediated acute and chronic rejection, play a central role. Additionally, humoral immune responses, characterised by the production of donor-specific and non-HLA antibodies, contribute significantly to graft injury. Recurrent tissue damage, such as ischemia reperfusion injury, leads to the exposure of cryptic antigens, promotes autoreactive processes, and facilitates the formation of tertiary lymphoid organs. These mechanisms sustain persistent inflammation, ultimately resulting in chronic graft dysfunction. Rejection reactions remain a major challenge. Acute forms, such as cellular and humoral rejection, require rapid and targeted therapies to prevent irreversible damage. Chronic rejection, particularly chronic lung allograft dysfunction (CLAD), progressively impairs lung function. In the main phenotypes of CLAD, bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS), are crucial for prognosis and treatment. Nevertheless, therapeutic options remain limited, and retransplantation is often the last resort. Immunosuppressive therapy forms the cornerstone of rejection prevention, and typically employs a triple combination of calcineurin inhibitors, antiproliferative agents, and corticosteroids. Induction therapy frequently involves monoclonal or polyclonal antibodies. Modern strategies aim to effectively suppress immune responses while minimising severe side effects, such as infections, malignancies, and nephrotoxicity. Future research will focus on personalised immunosuppressive strategies, optimised diagnostics, and innovative therapies to improve the long-term prognosis of lung transplant recipients.

Pseudomonas aeruginosa infection correlates with high MFI donor-specific antibody development following lung transplantation with consequential graft loss and shortened CLAD-free survival

BACKGROUND

Donor-specific antibodies (DSAs) are common following lung transplantation (LuTx), yet their role in graft damage is inconclusive. Mean fluorescent intensity (MFI) is the main read-out of DSA diagnostics; however its value is often disregarded when analyzing unwanted post-transplant outcomes such as graft loss or chronic lung allograft dysfunction (CLAD). Here we aim to evaluate an MFI stratification method in these outcomes.

METHODS

A cohort of 87 LuTx recipients has been analyzed, in which a cutoff of 8000 MFI has been determined for high MFI based on clinically relevant data. Accordingly, recipients were divided into DSA-negative, DSA-low and DSA-high subgroups. Both graft survival and CLAD-free survival were evaluated. Among factors that may contribute to DSA development we analyzed Pseudomonas aeruginosa (P. aeruginosa) infection in bronchoalveolar lavage (BAL) specimens.

RESULTS

High MFI DSAs contributed to clinical antibody-mediated rejection (AMR) and were associated with significantly worse graft (HR: 5.77, p < 0.0001) and CLAD-free survival (HR: 6.47, p = 0.019) compared to low or negative MFI DSA levels. Analysis of BAL specimens revealed a strong correlation between DSA status, P. aeruginosa infection and BAL neutrophilia. DSA-high status and clinical AMR were both independent prognosticators for decreased graft and CLAD-free survival in our multivariate Cox-regression models, whereas BAL neutrophilia was associated with worse graft survival.

CONCLUSIONS

P. aeruginosa infection rates are elevated in recipients with a strong DSA response. Our results indicate that the simultaneous interpretation of MFI values and BAL neutrophilia is a feasible approach for risk evaluation and may help clinicians when to initiate DSA desensitization therapy, as early intervention could improve prognosis.

Impact of Transient and Persistent Donor-Specific Antibodies in Lung Transplantation

Lung transplantation (LuTx) is an established treatment for patients with end-stage lung diseases, however, outcomes are limited by acute and chronic rejection. One aspect that has received increasing attention is the role of the host's humoral alloresponse, particularly the formation of de novo donor-specific antibodies (dnDSAs). The aim of this study was to investigate the clinical significance of transient and persistent dnDSAs and to understand their impact on outcomes after LuTx. A retrospective analysis was conducted using DSA screening data from LuTx recipients obtained at the Medical University of Vienna between February 2016 and March 2021. Of the 405 LuTx recipients analyzed, 205 patients developed dnDSA during the follow-up period. Among these, 167 (81%) had transient dnDSA and 38 (19%) persistent dnDSA. Persistent but not transient dnDSAs were associated with chronic lung allograft dysfunction (CLAD) and antibody-mediated rejection (AMR) (p < 0.001 and p = 0.006, respectively). CLAD-free survival rates for persistent dnDSAs at 1-, 3-, and 5-year post-transplantation were significantly lower than for transient dnDSAs (89%, 59%, 56% vs. 91%, 79%, 77%; p = 0.004). Temporal dynamics of dnDSAs after LuTx have a substantial effect on patient outcomes. This study underlines that the persistence of dnDSAs poses a significant risk to graft and patient survival.

Serological findings following the second and third SARS-CoV-2 vaccines in lung transplant recipients

INTRODUCTION

Lung transplant recipients (LuTX) represent a vulnerable population for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Even though many vaccines are already developed, more clinical data need to support effective immunological response in immunocompromised patients.

METHODS

Stable LuTX recipients with no medical history of coronavirus disease (COVID-19) were enrolled. Currently available messenger RNA (mRNA) (BNT162b2-mRNA, mRNA-1273) and non-mRNA (ChAdOx1, BBIBP-CorV) vaccines were given according to availability, boosters were all mRNA-based. SARS-CoV-2 Spike1 immunoglobulin G (IgG) antibody titer was evaluated before and 2 weeks after second and third dose. Difference between mRNA versus non-mRNA vaccines was assessed.

RESULTS

Forty-one patients (49% men, age 48.4 ± 13.8 years) received two doses of SARS-CoV-2 vaccines: 23 of mRNA, 18 of non-mRNA, and 24/41 (58%) received a third dose. Median 92 months passed since transplantation, and serum level of tacrolimus was median 5.5 ng/ml. Positive serology was found in 37% of all patients after the second dose, 86% had mRNA vaccine. After the third dose, 29% became positive who had no antibody before. Significantly higher level of antibody was found after the second mRNA than non-mRNA vaccines (2.2 vs. 1568.8 U/ml, respectively, p = .002). 6/23 (26%) patients received two doses of mRNA vaccine developed COVID-19 after the second injection in an average of 178 days, half of them recovered, half of them died in intensive care unit (ICU). 3/6 (50%) patients with two doses mRNA and recovered from COVID-19 had significantly higher level of antibody (average 20847.3 U/ml) than without infection. After the booster vaccine, 1/24 (4%) developed infection.

CONCLUSION

Immunosuppression therapy may induce a weaker SARS-CoV-2 response in LuTX recipients; therefore, third dose is a priority in transplanted patients. The highest antibody level was measured recovering from COVID after two doses. Our data confirm that booster mRNA vaccine could increase antibody levels, even if immunization was started with non-mRNA vaccine.

Induction Strategies in Lung Transplantation: Alemtuzumab vs. Basiliximab a Single-Center Experience

Background

Induction therapy is used in about 80% of lung transplant centers and is increasing globally. Currently, there are no standards or guidelines for the use of induction therapy. At our institution, we have two induction strategies, basiliximab, and alemtuzumab. The goal of this manuscript is to share our experience and practice since this is an area of controversy.

Methods

We retrospectively reviewed 807 lung transplants performed at our institution between 2011 and 2020. Indications for the use of the basiliximab protocol were as follows: patients over the age of 70 years, history of cancer, hepatitis C virus or human immunodeficiency virus infection history, and cytomegalovirus or Epstein-Barr virus (donor positive/ recipient negative). In the absence of these clinical factors, the alemtuzumab protocol was used.

Results

453 patients underwent alemtuzumab induction and 354 patients underwent basiliximab. There were significant differences in delayed chest closure (24.7% alemtuzumab vs 31.4% basiliximab, p = 0.037), grade 3 primary graft dysfunction observed within 72 hours (19.9% alemtuzumab vs 29.9% basiliximab, p = 0.002), postoperative hepatic dysfunction (8.8% alemtuzumab vs 14.7% basiliximab, p = 0.009), acute cellular rejection in first year (39.1% alemtuzumab vs 53.4% basiliximab, p < 0.001). The overall survival rate of the patients with alemtuzumab induction was significantly higher than those of the patients with basiliximab induction (5 years survival rate: 64.1% alemtuzumab vs 52.3%, basiliximab, p < 0.001). Multivariate Cox regression analysis confirmed lower 5-year survival for basiliximab induction (HR = 1.41, p = 0.02), recipient cytomegalovirus positive (HR = 1.49, p = 0.01), postoperative hepatic dysfunction (HR = 2.20, p < 0.001), and acute kidney injury requiring renal replacement therapy (HR = 2.27, p < 0.001).

Conclusions

In this single center retrospective review, there was a significant difference in survival rates between induction strategies. This outcome may be attributable to differences in recipient characteristics between the groups. However, the Alemtuzumab group experienced less episodes of acute cellular rejection within the first year.

Differential expression of circulating miRNAs after alemtuzumab induction therapy in lung transplantation

Alemtuzumab is a monoclonal antibody targeting CD52, used as induction therapy after lung transplantation (LTx). Its engagement produces a long-lasting immunodepletion; however, the mechanisms driving cell reconstitution are poorly defined. We hypothesized that miRNAs are involved in this process. The expression of a set of miRNAs, cytokines and co-signaling molecules was measured with RT-qPCR and flow cytometry in prospectively collected serum samples of LTx recipients, after alemtuzumab or no induction therapy. Twenty-six LTx recipients who received alemtuzumab and twenty-seven matched LTx recipients without induction therapy were included in the analysis. One year after transplantation four miRNAs were differentially regulated: miR-23b (p = 0.05) miR-146 (p = 0.04), miR-155 (p < 0.001) and miR-486 (p < 0.001). Expression of 3 miRNAs changed within the alemtuzumab group: miR-146 (p < 0.001), miR-155 (p < 0.001) and miR-31 (p < 0.001). Levels of IL-13, IL-4, IFN-γ, BAFF, IL-5, IL-9, IL-17F, IL-17A and IL-22 were different one year after transplantation compared to baseline. In no-induction group, concentration of sCD27, sB7.2 and sPD-L1 increased overtime. Expression of miR-23b, miR-146, miR-486, miR-155 and miR-31 was different in LTx recipients who received alemtuzumab compared to recipients without induction therapy. The observed cytokine pattern suggested proliferation of specific B cell subsets in alemtuzumab group and co-stimulation of T-cells in no-induction group.