Preemptive treatment of de novo donor-specific antibodies in lung transplant patients reduces subsequent risk of chronic lung allograft dysfunction or death.

The development of donor-specific antibodies after lung transplantation is associated with downstream acute cellular rejection, antibody-mediated rejection (AMR), chronic lung allograft dysfunction (CLAD), or death. It is unknown whether preemptive (early) treatment of de novo donor-specific antibodies (dnDSAs), in the absence of clinical signs and symptoms of allograft dysfunction, reduces the risk of subsequent CLAD or death. We performed a multicenter, retrospective cohort study to determine if early treatment of dnDSAs in lung transplant patients reduces the risk of the composite endpoint of CLAD or death. In the cohort of 445 patients, 145 patients developed dnDSAs posttransplant. Thirty patients received early targeted treatment for dnDSAs in the absence of clinical signs and symptoms of AMR. Early treatment of dnDSAs was associated with a decreased risk of CLAD or death (hazard ratio, 0.36; 95% confidence interval, 0.17-0.76; P < .01). Deferring treatment until the development of clinical AMR was associated with an increased risk of CLAD or death (hazard ratio, 3.00; 95% confidence interval, 1.46-6.18; P < .01). This study suggests that early, preemptive treatment of donor-specific antibodies in lung transplant patients may reduce the subsequent risk of CLAD or death.

Elevated cell-free DNA in respiratory viral infection and associated lung allograft dysfunction.

Respiratory viral infection (RVI) in lung transplant recipients (LTRs) is a risk for chronic lung allograft dysfunction (CLAD). We hypothesize that donor-derived cell-free DNA (%ddcfDNA), at the time of RVI predicts CLAD progression. We followed 39 LTRs with RVI enrolled in the Genomic Research Alliance for Transplantation for 1 year. Plasma %ddcfDNA was measured by shotgun sequencing, with high %ddcfDNA as ≥1% within 7 days of RVI. We examined %ddcfDNA, spirometry, and a composite (progression/failure) of CLAD stage progression, re-transplant, and death from respiratory failure. Fifty-nine RVI episodes, 38 low and 21 high %ddcfDNA were analyzed. High %ddcfDNA subjects had a greater median %FEV1 decline at RVI (-13.83 vs. -1.83, p = .007), day 90 (-7.97 vs. 0.91, p = .04), and 365 (-20.05 vs. 1.09, p = .047), compared to those with low %ddcfDNA and experienced greater progression/failure within 365 days (52.4% vs. 21.6%, p = .01). Elevated %ddcfDNA at RVI was associated with an increased risk of progression/failure adjusting for symptoms and days post-transplant (HR = 1.11, p = .04). No difference in %FEV1 decline was seen at any time point when RVIs were grouped by histopathology result at RVI. %ddcfDNA delineates LTRs with RVI who will recover lung function and who will experience sustained decline, a utility not seen with histopathology.

Baseline Lung Allograft Dysfunction After Bilateral Lung Transplantation Is Associated With an Increased Risk of Death: Results From a Multicenter Cohort Study.

Background: A prior single-center, retrospective cohort study identified baseline lung allograft dysfunction (BLAD) as a risk factor for death in bilateral lung transplant recipients. In this multicenter prospective cohort study, we test the association of BLAD with death in bilateral lung transplant recipients, identify clinical risk factors for BLAD, and assess its association with allograft injury on the molecular level. Methods: This multicenter, prospective cohort study included 173 bilateral lung transplant recipients that underwent serial pulmonary function testing and plasma collection for donor-derived cell-free DNA at prespecified time points. BLAD was defined as failure to achieve ≥80% predicted for both forced expiratory volume in 1 s and forced vital capacity after lung transplant, on 2 consecutive measurements at least 3 mo apart. Results: BLAD was associated with increased risk of death (hazard ratio, 1.97; 95% confidence interval [CI], 1.05-3.69; P = 0.03) but not chronic lung allograft dysfunction alone (hazard ratio, 1.60; 95% CI, 0.87-2.95; P = 0.13). Recipient obesity (odds ratio, 1.69; 95% CI, 1.15-2.80; P = 0.04) and donor age (odds ratio, 1.03; 95% CI, 1.02-1.05; P = 0.004) increased the risk of developing BLAD. Patients with BLAD did not demonstrate higher log10(donor-derived cell-free DNA) levels compared with no BLAD (slope [SE]: -0.0095 [0.0007] versus -0.0109 [0.0007]; P = 0.15). Conclusions: BLAD is associated with an increased risk of death following lung transplantation, representing an important posttransplant outcome with valuable prognostic significance; however, early allograft specific injury on the molecular level does not increase the risk of BLAD, supporting further mechanistic insight into disease pathophysiology.

Extreme elevations of donor-derived cell-free DNA increases the risk of chronic lung allograft dysfunction and death, even without clinical manifestations of disease.

BACKGROUND: Lung transplant recipients are traditionally monitored with pulmonary function testing (PFT) and lung biopsy to detect post-transplant complications and guide treatment. Plasma donor-derived cell free DNA (dd-cfDNA) is a novel molecular approach of assessing allograft injury, including subclinical allograft dysfunction. The aim of this study was to determine if episodes of extreme molecular injury (EMI) in lung transplant recipients increases the risk of chronic lung allograft dysfunction (CLAD) or death. METHODS: This multicenter prospective cohort study included 238 lung transplant recipients. Serial plasma samples were collected for dd-cfDNA measurement by shotgun sequencing. EMI was defined as a dd-cfDNA above the third quartile of levels observed for acute rejection (dd-cfDNA level of ≥5% occurring after 45 days post-transplant). EMI was categorized as Secondary if associated with co-existing acute rejection, infection or PFT decline; or Primary if not associated with these conditions. RESULTS: EMI developed in 16% of patients at a median 343.5 (IQR: 177.3-535.5) days post-transplant. Over 50% of EMI episodes were classified as Primary. EMI was associated with an increased risk of severe CLAD or death (HR: 2.78, 95% CI: 1.26-6.22, p = 0.012). The risk remained consistent for the Primary EMI subgroup (HR: 2.34, 95% CI 1.18-4.85, p = 0.015). Time to first EMI episode was a significant predictor of the likelihood of developing CLAD or death (AUC=0.856, 95% CI=0.805-0.908, p < 0.001). CONCLUSIONS: Episodes of EMI in lung transplant recipients are often isolated and may not be detectable with traditional clinical monitoring approaches. EMI is associated with an increased risk of severe CLAD or death, independent of concomitant transplant complications.

Invasive fungal infections after respiratory viral infections in lung transplant recipients are associated with lung allograft failure and chronic lung allograft dysfunction within 1 year.

BACKGROUND: Respiratory viral infections (RVI) are associated with chronic lung allograft dysfunction (CLAD) and mortality in lung transplant recipients (LTRs). However, the prevalence and impact of secondary invasive fungal infections (IFIs) post RVIs in LTRs have not been investigated. METHODS: We performed a single center retrospective study including LTRs diagnosed with 5 different respiratory viral pathogens between January 2010 to May 2021 and evaluated their clinical outcomes in 1 year. The risk factors of IFIs were evaluated by logistic regression. The impact of IFIs on CLAD stage progression/death was examined by Cox regression. RESULTS: A total of 202 RVI episodes (50 influenza, 31 severe acute respiratory syndrome coronavirus-2, 30 metapneumovirus, 44 parainfluenza, and 47 respiratory syncytial virus) in 132 patients was included for analysis. Thirty-one episodes (15%) were associated with secondary IFIs, and 27 occurred in LTRs with lower respiratory tract infection (LRTI; 28% from 96 LRTI episodes). Aspergillosis was the most common IFI (80%). LTRs with IFIs had higher disease severity during RVI episodes. In multivariable analysis, RVI with LTRI was associated with IFI (adjusted odds ratio [95% confidence interval (CI)] of 7.85 (2.48-24.9). Secondary IFIs were associated with CLAD stage progression/death after accounting for LRTI, pre-existing CLAD, intensive care unit admission, secondary bacterial pneumonia and underlying lung diseases pre-transplant with adjusted hazard ratio (95%CI) of 2.45 (1.29-4.64). CONCLUSIONS: This cohort demonstrated 15% secondary IFI prevalence in LTRs with RVIs. Importantly, secondary IFIs were associated with CLAD stage progression/death, underscoring the importance of screening for fungal infections in this setting.

Pseudomonas-dominant microbiome elicits sustained IL-1ß upregulation in alveolar macrophages from lung transplant recipients.

BACKGROUND: Isolation of Pseudomonas aeruginosa (PsA) is associated with increased BAL (bronchoalveolar lavage) inflammation and lung allograft injury in lung transplant recipients (LTR). However, the effect of PsA on macrophage responses in this population is incompletely understood. We examined human alveolar macrophage (AMΦ) responses to PsA and Pseudomonas dominant microbiome in healthy LTR. METHODS: We stimulated THP-1 derived macrophages (THP-1MΦ) and human AMΦ from LTR with different bacteria and LTR BAL derived microbiome characterized as Pseudomonas-dominant. Macrophage responses were assessed by high dimensional flow cytometry, including their intracellular production of cytokines (TNF-α, IL-6, IL-8, IL-1ß, IL-10, IL-1RA, and TGF-ß). Pharmacological inhibitors were utilized to evaluate the role of the inflammasome in PsA-macrophage interaction. RESULTS: We observed upregulation of pro-inflammatory cytokines (TNF-α, IL-6, IL-8, IL-1ß) following stimulation by PsA compared to other bacteria (Staphylococcus aureus (S.Aur), Prevotella melaninogenica, Streptococcus pneumoniae) in both THP-1MΦ and LTR AMΦ, predominated by IL-1ß. IL-1ß production from THP-1MΦ was sustained after PsA stimulation for up to 96 hours and 48 hours in LTR AMΦ. Treatment with the inflammasome inhibitor BAY11-7082 abrogated THP-1MΦ IL-1ß production after PsA exposure. BAL Pseudomonas-dominant microbiota elicited an increased IL-1ß, similar to PsA, an effect abrogated by the addition of antibiotics. CONCLUSION: PsA and PsA-dominant lung microbiota induce sustained IL-1ß production in LTR AMΦ. Pharmacological targeting of the inflammasome reduces PsA-macrophage-IL-1ß responses, underscoring their use in lung transplant recipients.

Clinical features and allograft failure rates of pulmonary antibody-mediated rejection categories.

BACKGROUND: Pulmonary antibody-mediated rejection (AMR) consensus criteria categorize AMR by diagnostic certainty. This study aims to define the clinical features and associated outcomes of these recently defined AMR categories. METHODS: Adjudication committees reviewed clinical data of 335 lung transplant recipients to define clinical or subclinical AMR based on the presence of allograft dysfunction, and the primary endpoints, time from transplant to allograft failure, a composite endpoint of chronic lung allograft dysfunction and/or death. Clinical AMR was subcategorized based on diagnostic certainty as definite, probable or possible AMR if 4, 3, or 2 characteristic features were present, respectively. Allograft injury was assessed via plasma donor-derived cell-free DNA (ddcfDNA). Risk of allograft failure and allograft injury was compared for AMR categories using regression models. RESULTS: Over the 38.5 months follow-up, 28.7% of subjects developed clinical AMR (n = 96), 18.5% developed subclinical AMR (n = 62) or 58.3% were no AMR (n = 177). Clinical AMR showed higher risk of allograft failure and ddcfDNA levels compared to subclinical or no AMR. Clinical AMR included definite/probable (n = 21) or possible AMR (n = 75). These subcategories showed similar clinical characteristics, ddcfDNA levels, and risk of allograft failure. However, definite/probable AMR showed greater measures of AMR severity, including degree of allograft dysfunction and risk of death compared to possible AMR. CONCLUSIONS: Clinical AMR showed greater risk of allograft failure than subclinical AMR or no AMR. Subcategorization of clinical AMR based on diagnostic certainty correlated with AMR severity and risk of death, but not with the risk of allograft failure.

Anaphylactic reactions with intravenous vitamin K: lessons from the bedside.

Vitamin K is used as a correction factor to avert the risk of bleeding due to warfarin overdose. Among the reported complications of this therapy, the most serious one is the anaphylactic cardiovascular collapse caused by intravenous infusion of the drug. We report herein a patient with over-anticoagulation from warfarin use and a subcapsular renal bleeding who developed a fatal anaphylactic shock after vitamin K administration via slow intravenous infusion. Vigilance with the intravenous formulation of this agent should always be sought in order to prevent fatal outcomes, especially in patients with severe comorbidities.

Biological Variation of Donor-Derived Cell-Free DNA in Stable Lung Transplant Recipients.

BACKGROUND: Prior studies demonstrate that donor-derived cell-free DNA (dd-cfDNA) in lung transplant recipients may serve as a marker of allograft injury for detecting allograft rejection and infection. Clinical interpretation of dd-cfDNA requires understanding its biological variation in stable lung transplant patients in order to identify abnormal results suggesting underlying allograft dysfunction. This study establishes the biological variation and reference change values (RCV) of dd-cfDNA in stable lung transplant recipients using an analytically validated assay with an established analytic coefficient of variation (CVA). METHODS: The AlloSure® assay, a targeted, sequencing-based approach, was used to measure plasma dd-cfDNA in a cohort of lung transplant patients at 4 centers that used dd-cfDNA to monitor for allograft dysfunction in preference to surveillance transbronchial biopsy. Patients with stable allograft function and ≥3 dd-cfDNA samples were included. Intraindividual coefficient of variation (CVI), interindividual CV (CVG), index of individuality (II) and the RCV were calculated. RESULTS: Thirty-five patients with a combined 124 dd-cfDNA samples were included in the final analysis. The median dd-cfDNA was 0.31% (interquartile range 0.18%-0.68%), the 97.5th percentile and 95th percentile were 1.3% and 1.0%, respectively. In 30 stable patients with an average of 3.7 tests, the CVI was 25%, CVG 19%, II 1.33, and RCV 70%. CONCLUSION: In stable lung transplant patients, fluctuations in dd-cfDNA levels of up to 70% or levels less than 1% are within normal biological variation. With further validation, these thresholds may be incorporated into surveillance monitoring algorithms to identify potentially abnormal results indicating allograft dysfunction.

Donor-derived cell-free DNA as a composite marker of acute lung allograft dysfunction in clinical care.

BACKGROUND: As a marker of underlying lung allograft injury, donor-derived cell-free DNA (dd-cfDNA) may be used to identify episodes of acute allograft injury in lung transplant recipients. We investigated the utility of dd-cfDNA to monitor subjects at risk of acute rejection or infection in routine clinical practice. METHODS: This multicenter, retrospective cohort study collected data from lung transplant recipients within 3 years of transplant at 4 centers between March 24, 2020 and September 1, 2020. During this period, as part of routine care during the COVID-19 pandemic, these centers implemented a home-based surveillance program using plasma dd-cfDNA in preference to surveillance bronchoscopy. Dd-cfDNA was used to detect acute lung allograft dysfunction (ALAD) - a composite endpoint of acute rejection and infection. dd-cfDNA levels in patients with ALAD were compared to stable patients. The performance characteristics of dd-cfDNA ≥ 1.0% to detect ALAD were estimated. RESULTS: A total of 175 patients underwent 380 dd-cfDNA measurements, of which 290 were for routine surveillance purposes. dd-cfDNA was higher in patients with ALAD than stable patients (Median (IQR) 1.7% (0.63, 3.1) vs 0.35% (0.22, 0.79), p < 0.001). As an indication of underlying ALAD during surveillance testing, the estimated sensitivity of dd-cfDNA ≥1% was 73.9%, specificity of 87.7%, positive predictive value of 43.4% and negative predictive value of 96.5%. CONCLUSIONS: dd-cfDNA identified acute lung allograft dysfunction in asymptomatic lung transplant patients that may not have been identified by using a clinically indicated biopsy strategy alone. dd-cfDNA <1.0% may be useful in ruling out acute rejection and infection, supporting its use as a potential noninvasive marker for surveillance monitoring.

Human Metapneumovirus and Parainfluenza Virus Infections in Lung Transplant Recipients: The Effects on Lung Allograft and Clinical Outcomes.

BACKGROUND: Human metapneumovirus (HMPVi) and parainfluenza virus (PIVi) infections are common community-acquired infections in lung transplant recipients (LTRs), but data are extremely limited. METHODS: A retrospective study including all LTRs at the Johns Hopkins Hospital during July 2010-June 2019 with positive HMPV and PIV polymerase chain reaction respiratory specimens was performed. RESULTS: Thirty-one HMPV- and 53 PIV-infected LTRs were identified. LTRs with HMPVi and PIVi had similar baseline characteristics, infection parameters, treatment allocation, and allograft function outcomes. Among entire cohort, 31.6% had chronic allograft dysfunction (CLAD) stage progression within 1 y postinfections (29.2% versus 35.5% for PIVi versus HMPVi, respectively, P = 0.56). In forced expiratory volume in 1 s percent (FEV1%) trajectory analysis showed steadily decline of FEV1 across time among CLAD stage progressors from both viruses. FEV1% decline ≥10% at 90 d had adjusted hazard ratio for CLAD stage progression of 18.4 (4.98-67.76) and 4.6 (1.36-15.34) for PIVi and HMPVi, respectively. PIVi caused higher donor-specific antigen development (11.8% versus 3.2%, P = 0.18) and 1-y mortality (9.4% versus 0%, P = 0.11), compared with HMPVi, even though the results were not statistically significant. Ribavirin did not show protective effect, and mycophenolate discontinuation during infection did not increase risk of CLAD stage progression. CONCLUSIONS: One-third of HMPV- and PIV-infected LTRs developed CLAD stage progression within 1 y. The lack of early lung function recovery may predict long-term CLAD progression.

Impact of COVID-19 on Lung Allograft and Clinical Outcomes in Lung Transplant Recipients: A Case-control Study.

BACKGROUND: The impacts of COVID-19 on lung allograft function, rejection, secondary infection, and clinical outcomes in lung transplant recipients (LTRs) remain unknown. METHODS: A 1:2 matched case-control study was performed to evaluate rehospitalization, lung allograft function, and secondary infections up to 90 d after COVID-19 diagnosis (or index dates for controls). RESULTS: Twenty-four LTRs with COVID-19 (cases) and 48 controls were identified. Cases and controls had similar baseline characteristics and lung allograft function. LTRs with COVID-19 had higher incidence of secondary bacterial infection (29.2% versus 6.3%, P = 0.008), readmission (29.2% versus 10.4%, P = 0.04), and for-cause bronchoscopy (33.3% versus 12.5%, P = 0.04) compared with controls. At d 90, mortality in cases versus controls was 8.3% versus 2.1% (P = 0.21), incidence of invasive fungal infections in cases versus controls was 20.8% versus 8.3% (P = 0.13) and forced expiratory volume in 1 s (FEV1) decline ≥10% from baseline occurred in 19% of cases versus 12.2% of controls (P = 0.46). No acute cellular rejection, acute antibody-mediated rejection, or new donor-specific anti-HLA antibodies were observed among cases or controls within 90 d post index date. CONCLUSIONS: We found LTRs with COVID-19 were at risk to develop secondary infections and rehospitalization post COVID-19, compared with controls. While we did not observe post viral acute cellular rejection or antibody-mediated rejection, further studies are needed to understand if LTRs with COVID-19 who did not recover baseline lung function within 90 d have developed chronic lung allograft dysfunction stage progression.