Late-Onset Exudative Pleural Effusions Without Concomitant Airway Obstruction or Lung Parenchymal Abnormalities: A Novel Presentation of Chronic Lung Allograft Dysfunction.

Restrictive allograft syndrome (RAS) is an aggressive variant of CLAD characterized by progressive restrictive ventilatory decline and persistent pleuro-parenchymal changes that can be seen on chest CT. We identified four lung transplant recipients with a progressive restrictive ventilatory defect due to lymphocyte-predominant exudative pleural effusions, but no pleuro-parenchymal abnormalities typical of RAS. Using molecular analysis, we also found increased levels of previously described immune markers of RAS, including NFkB, 20S proteasome, lipocalin, TNFα, and TGFß, within the circulating small extracellular vesicles of the remaining living lung transplant recipient. Despite the absence of lung parenchymal changes, these patients had a poor prognosis with rapid deterioration in allograft function and no response to pleural-based interventions such as thoracentesis, decortication, and pleurodesis. We hypothesize that these cases represent a distinct CLAD phenotype characterized by progressive restriction due to pleural inflammation, lymphocyte-predominant pleural effusion, resultant compressive atelectasis, and eventual respiratory failure in the absence of lung parenchymal involvement.

Evaluating the efficacy and safety of letermovir compared to valganciclovir for the prevention of human cytomegalovirus disease in adult lung transplant recipients.

BACKGROUND: Lung transplant recipients are at high risk for severe cytomegalovirus (CMV) disease. Off-label use of letermovir (LET) may avert myelotoxicity associated with valganciclovir (VGCV), but data in lung transplantation are limited. This study aims to evaluate the outcomes of LET prophylaxis among lung transplant recipients. METHODS: This retrospective, matched cohort study included lung transplant recipients who received LET for primary CMV prophylaxis following VGCV intolerance. Patients were matched 1:1 to historical VGCV controls based on age, serostatus group, and time from transplant. The primary outcome was CMV breakthrough within 1 year post-LET initiation; secondary outcomes included hematologic changes. RESULTS: A total of 124 lung transplant recipients were included per group (32% CMV mismatch, D+R-), with LET initiated a median of 9.6 months post-transplantation. One CMV breakthrough event (0.8%) was observed in the LET group versus four (3.2%) in the VGCV group (p = .370). The median (interquartile range) white blood cell (WBC) count was 3.1 (2.1-5.6) at LET initiation which increased to 5.1 (3.9-7.2) at the end of follow-up (p <.001). For VGCV controls, WBC was 4.8 (3.4-7.2) at baseline and 5.4 (3.6-7.2) at the end of follow-up; this difference was not statistically significant (p = .395). Additionally, 98.4% of LET patients experienced ≥1 leukopenia episode in the year prior to LET compared to 71.8% the year after initiation (p <.001). Similar results were observed for neutropenia (48.4% and 17.7%, p <.001). CONCLUSION: LET prophylaxis was associated with a low rate of CMV reactivation and leukopenia recovery. LET may represent a reasonable prophylaxis option for lung transplant recipients unable to tolerate VGCV.

Prior SARS-CoV-2 infection may not alter the clinical course of COVID-19 in lung transplant recipients: A single-center experience.

BACKGROUND: In the general population, prior infection with SARS-CoV-2 reduces the risk of severe COVID-19; however, studies in lung transplant recipients (LTRs) are lacking. We sought to describe the clinical course of COVID-19 recurrence and compare outcomes between the first and second episodes of COVID-19 in LTRs. METHODS: We conducted a retrospective, single-center cohort study of LTRs with COVID-19 between January 1, 2022, and September 30, 2022, during the Omicron wave. We compared the clinical course of a second episode of COVID-19 to that of the patients' own first episode and to that of LTRs who developed a first episode during the study period. RESULTS: During the study period, we identified 24 LTRs with COVID-19 recurrence and another 75 LTRs with a first episode of COVID-19. LTRs who survived the initial episode of COVID-19 had a similar disease course with recurrence, with a trend toward reduced hospitalization (10 (41.6%) vs. 4 (16.7%), p = .114). Furthermore, compared to LTRs with a primary infection during the Omicron wave, those with a reinfection had a non-statistically significant trend toward reduced hospitalizations (aOR .391, 95% CI [.115-1.321], p = .131), shorter lengths-of-stay (median, 4 vs. 9 days, p = .181), and reduced intensive care unit admissions, intubations, and COVID-19-related mortality. CONCLUSIONS: LTRs who survive the first episode of COVID-19 are likely to have a similar clinical course with recurrent episodes. Although recurrent COVID-19 may be milder, larger, well-powered studies are needed to confirm this observation. Ongoing precautions are warranted.

Morbidity of antireflux surgery in lung transplant and matched nontransplant cohorts is comparable.

BACKGROUND: Safety data on perioperative outcomes of laparoscopic antireflux surgery (LARS) after lung transplantation (LT) are lacking. We compared the 30-day readmission rate and short-term morbidity after LARS between LT recipients and matched nontransplant (NT) controls. METHODS: Adult patients who underwent LARS between January 1, 2015, and October 31, 2021, were included. The participants were divided into two groups: LT recipients and NT controls. First, we compared 30-day readmission rates after LARS between the LT and NT cohorts. Next, we compared 30-day morbidity after LARS between the LT cohort and a 1-to-2 propensity score-matched NT cohort. RESULTS: A total of 1328 patients (55 LT recipients and 1273 NT controls) were included. The post-LARS 30-day readmission rate was higher in LT recipients than in the overall NT controls (14.5% vs. 2.8%, p < 0.001). Compared to matched NT controls, LT recipients had a lower prevalence of paraesophageal hernia, a smaller median hernia size, and higher peristaltic vigor. Also compared to the matched NT controls, the LT recipients had a lower median operative time but a longer median length of hospital stay. The proportion of patients with a post-LARS event within 30 postoperative days was comparable between the LT and matched NT cohorts (21.8% vs 14.5%, p = 0.24). CONCLUSIONS: Despite a higher perceived risk of comorbidity burden, LT recipients and matched NT controls had similar rates of post-LARS 30-day morbidity at our large-volume center with expertise in transplant and foregut surgery. LARS after LT is safe.

Nocardia prophylaxis, treatment, and outcomes of infection in lung transplant recipients: A matched case-control study.

BACKGROUND: Lung transplant recipients are at heightened risk for nocardiosis compared to other solid organ transplant recipients, with incidence rates as high as 9% and up to 30% associated mortality. No controlled studies assessing risk factors for nocardiosis in this high-risk population have been reported. METHODS: Patients undergoing lung transplantation at a single center between 2012 and 2018 and diagnosed with nocardiosis post-transplant were matched 1:2 to uninfected control subjects on the basis of age, transplant date, and sex. RESULTS: The incidence of nocardiosis in this lung transplant population was 3.4% (20/586), occurring a median of 9.4 months (range 4.4-55.2) post-transplant. In multivariable analysis, consistent use of trimethoprim/sulfamethoxazole (TMP/SMX) in the 12 weeks prior to diagnosis was independently associated with protection against nocardiosis (OR 0.038; 95% CI 0.01-0.29; P = .002). Augmented immunosuppression in the 6 months prior to diagnosis was independently associated with the development of nocardiosis (OR 9.94; 95% CI 1.62- 61.00; P = .013). Six case patients (30%) had disseminated disease; all-cause 6-month mortality was 25%. The most common species was Nocardia farcinica (7/17 isolates), which was associated with dissemination and mortality. The most active antibiotics were TMP/SMX (100%), linezolid (100%), and amikacin (76%). Imipenem was only active against 4/17 isolates (24% susceptibility), with two isolates becoming non-susceptible later in therapy. CONCLUSIONS: Trimethoprim/sulfamethoxazole prophylaxis was shown to be protective against nocardiosis in lung transplant recipients, while augmented immunosuppression conferred increased risk. Institutional epidemiologic data are needed to best guide empiric therapy for Nocardia, as historical in vitro data may not predict local susceptibilities.

COVID-19 in a lung transplant recipient: Exploring the diagnostic role of circulating exosomes and the clinical impact of advanced immunosuppression.

Exosomes isolated from plasma of lung transplant recipients with allograft injury contain donor-derived lung self-antigens (collagen V and Kα1 tubulin) and human leukocyte antigen (HLA) molecules. We present a case of a 76-year-old, female lung transplant recipient treated for acute cellular rejection with methylprednisolone and anti-thymocyte globulin, who subsequently contracted SARS-CoV-2 and developed a sharp increase in the mean fluorescent intensity of anti-HLA antibodies. Analysis of circulating exosomes during rejection, but before SARS-CoV-2 infection, revealed the presence of lung self-antigens and HLA class II molecules. After the patient contracted SARS-CoV-2, exosomes with the SARS-CoV-2 spike protein were also found. After resolution of infectious symptoms, exosomes with SARS-CoV-2 spike protein were no longer detected; however, exosomes with lung self-antigens and HLA class II molecules persisted, which coincided with a progressive decline in spirometric flows, suggesting chronic lung allograft dysfunction. We propose that the analysis of circulating exosomes may be used to detect allograft injury mediated by both rejection and infection. Furthermore, the detection of exosomes containing viral proteins may be helpful in identifying allograft injury driven by viral pathogens.

Chronic Lung Allograft Dysfunction: Immune Responses Induced by Circulating Exosomes with Lung-Associated Self-Antigens.

Exosomes, nanovesicles shown to regulate physiological processes in vivo, have been implicated in pathological conditions including cancer, autoimmune disease, infectious disease, neurodegenerative disease, and allograft rejection. Studies of lung transplant recipients with primary graft dysfunction, respiratory viral infection, and (acute) rejection have demonstrated circulating exosomes containing donor-mismatched human leukocyte antigen and lung-associated self-antigens, K-alpha 1 tubulin and collagen V, indicating that exosomes are originating from the transplanted organ. These circulating exosomes likely play a role in activating immune responses that lead to increased risk of chronic lung allograft dysfunction, as exosomes efficiently present their antigens to the immune system by all known pathways of antigen recognition (i.e., direct, indirect, and semidirect pathways). Here, we discuss exosome biogenesis, describe their contents, and address the mechanism of exosome-mediated activation of immune responses that lead to allograft rejection, especially after lung transplantation.

Emergence of letermovir resistance in a lung transplant recipient with ganciclovir-resistant cytomegalovirus infection.

Following a year of valganciclovir prophylaxis, a lung transplant recipient developed cytomegalovirus (CMV) infection that became resistant to ganciclovir, as confirmed by detection of UL97 kinase mutation M460V and a previously uncharacterized UL54 DNA polymerase mutation L516P. The latter mutation is now shown to confer ganciclovir and cidofovir resistance. As predicted from the viral genotype, foscarnet therapy was effective, but resumption of valganciclovir as secondary prophylaxis resulted in a plasma viral load rebound to 3.6 log10 copies/mL several weeks later. Valganciclovir was then replaced by letermovir, resulting in gradual viral load reduction in the first 5 weeks to below the quantitation limit (2.7 log10 copies/mL) for 1 week, followed by 10 weeks of rising viral loads reaching 4.3 log10 copies/mL while on letermovir. At this point, CMV genotypic testing revealed UL56 mutation C325Y, which confers absolute resistance to letermovir. Retreatment with foscarnet was successful. This case adds to the considerable list of proven ganciclovir resistance mutations, and provides an early experience with letermovir resistance after off-label therapeutic use. This experience is consistent with in vitro observations of rapid emergence of letermovir-resistant CMV after drug exposure.

Frailty Phenotypes, Disability, and Outcomes in Adult Candidates for Lung Transplantation.

RATIONALE: Frailty is associated with morbidity and mortality in abdominal organ transplantation but has not been examined in lung transplantation. OBJECTIVES: To examine the construct and predictive validity of frailty phenotypes in lung transplant candidates. METHODS: In a multicenter prospective cohort, we measured frailty with the Fried Frailty Phenotype (FFP) and Short Physical Performance Battery (SPPB). We evaluated construct validity through comparisons with conceptually related factors. In a nested case-control study of frail and nonfrail subjects, we measured serum IL-6, tumor necrosis factor receptor 1, insulin-like growth factor I, and leptin. We estimated the association between frailty and disability using the Lung Transplant Valued Life Activities disability scale. We estimated the association between frailty and risk of delisting or death before transplant using multivariate logistic and Cox models, respectively. MEASUREMENTS AND MAIN RESULTS: Of 395 subjects, 354 completed FFP assessments and 262 completed SPPB assessments; 28% were frail by FFP (95% confidence interval [CI], 24-33%) and 10% based on the SPPB (95% CI, 7-14%). By either measure, frailty correlated more strongly with exercise capacity and grip strength than with lung function. Frail subjects tended to have higher plasma IL-6 and tumor necrosis factor receptor 1 and lower insulin-like growth factor I and leptin. Frailty by either measure was associated with greater disability. After adjusting for age, sex, diagnosis, and transplant center, both FFP and SPPB were associated with increased risk of delisting or death before lung transplant. For every 1-point worsening in score, hazard ratios were 1.30 (95% CI, 1.01-1.67) for FFP and 1.53 (95% CI, 1.19-1.59) for SPPB. CONCLUSIONS: Frailty is prevalent among lung transplant candidates and is independently associated with greater disability and an increased risk of delisting or death.

Procalcitonin predicts mortality in HIV-infected Ugandan adults with lower respiratory tract infections.

BACKGROUND AND OBJECTIVE: In low and middle-income countries where HIV infection is prevalent, identifying patients at high risk of dying from lower respiratory tract infections is challenging and validated prognostic models are lacking. Serum procalcitonin may be a useful prognostic tool in these settings. We sought to determine if elevated serum procalcitonin is associated with increased in-hospital mortality and to combine serum procalcitonin with available clinical characteristics to create a clinically useful prognostic model. METHODS: We conducted a prospective, nested case-control study of 241 HIV-infected adults admitted to Mulago Hospital in Kampala, Uganda with cough ≥2 weeks in duration. We collected demographic and clinical information, baseline serum for procalcitonin analysis, and followed patients to determine in-hospital mortality. RESULTS: Serum procalcitonin was a strong and independent predictor of inpatient mortality (aOR = 7.69, p = 0.01, sensitivity = 93%, negative predictive value = 97%). Best subset multivariate analysis identified 3 variables that were combined into a prognostic model to risk stratify patients; these variables included respiratory rate ≥30 breaths/minute (aOR = 2.07, p = 0.11), oxygen saturation <90% (aOR = 3.07, p = 0.02), and serum procalcitonin >0.5 ng/ml (aOR = 7.69, p = 0.01). The predicted probability of inpatient mortality ranged from 1% when no variables were present, to 42% when all variables were present. CONCLUSIONS: Elevated serum procalcitonin >0.5 ng/ml is an independent predictor of in-hospital mortality. Elevated serum procalcitonin, tachypnea, and hypoxemia may be combined into a prognostic model to identify patients at high risk of dying in the hospital. This model may be used to estimate the probability of death and to guide triage and treatment decisions.

Remdesivir and molnupiravir had comparable efficacy in lung transplant recipients with mild-to-moderate COVID-19: a single center experience.

Introduction: Remdesivir (REM) and molnupiravir (MOL) are commonly used to treat lung transplant recipients (LTRs) with COVID-19; however, the clinical efficacy of these medications is yet to be compared. In this retrospective cohort study, we compared the clinical outcomes between LTRs with mild-to-moderate COVID-19 treated with REM and those treated with MOL. Methods and Results: Between March 2020 and August 2022, 195 LTRs developed COVID-19 at our center. After excluding 82 who presented with severe disease requiring hospitalization, the remaining 113 were included in the analysis: 54 did not receive antiviral treatment, 30 were treated with REM, and 29 were treated with MOL. Adjusted multivariable logistic regression analysis showed similar rates of hospitalization (adjusted odds ratio (aOR) 1.169, [95% confidence interval (95% CI) 0.105-12.997, p = 0.899], ICU admission (aOR 0.822, 95% CI 0.042-16.220, p = 0.898), mechanical ventilation (aOR 0.903, 95% CI 0.015-55.124, p = 0.961), and COVID-19-related mortality (aOR 0.822, 95% CI 0.042-16.220, p = 0.898) between LTRs treated with REM and those treated with MOL for mild-to-moderate COVID-19, irrespective of SARS-CoV-2 strain. Conclusion: MOL may be a suitable alternative to REM to treat LTRs with mild-to-moderate COVID-19, and the choice of antiviral therapy can be driven by practical considerations such as route of administration and drug availability.

Evolving impact of the COVID-19 pandemic on lung transplant recipients: A single-center experience.

BACKGROUND: Lung transplant recipients (LTRs) are at increased risk of morbidity and mortality from coronavirus disease 2019 (COVID-19); however, the disease course has changed as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants have mutated. We compared COVID-19-related clinical outcomes in LTRs at different stages of the pandemic. We also identified risk factors for developing severe COVID-19 independent of the dominant SARS-CoV-2 variant. METHODS: This single-center, retrospective cohort study of LTRs with COVID-19 used Cox regression analyses and bootstrapping to identify factors affecting COVID-19 severity. RESULTS: Between March 2020 and August 2022, 195 LTRs were diagnosed with COVID-19, almost half (89 [45.6%]) during the Omicron period. A total of 113 (58.5%) LTRs were hospitalized and 47 (24.1%) died. Age >65 years increased the risk of hospitalization and death. Although infection with the Omicron variant was associated with a lower risk of hospitalization, the median length of hospital stay (10 days, [interquartile range, 5-19]) was similar between the variants. Intensive care unit (ICU) admission and death were more common with the Delta variant but comparable between the original, Alpha, and Omicron variants. Remdesivir and molnupiravir reduced the risk of hospitalization, and monoclonal antibody therapy reduced the risk of ICU admission, intubation, and death. Vaccination and pre-exposure prophylaxis (PrEP) with tixagevimab-cilgavimab did not significantly reduce COVID-19-related ICU admission, intubation, or mortality among LTRs. CONCLUSIONS: LTRs with COVID-19 continue to have high hospitalization rates and prolonged hospital stays, despite the reduced virulence of the Omicron variant. More effective PrEP and therapeutic interventions for COVID-19 among vulnerable patient groups are needed.

Pre-exposure Prophylaxis with Tixagevimab-cilgavimab did not Reduce Severity of COVID-19 in Lung Transplant Recipients with Breakthrough Infection.

Lung transplant recipients (LTRs) have an increased risk of COVID-19-related morbidity and mortality. Tixagevimab-cilgavimab (tix-cil) is a long-acting monoclonal antibody combination granted Emergency Use Authorization approval by the US Food and Drug Administration for COVID-19 pre-exposure prophylaxis (PrEP) in immunocompromised patients. We sought to determine whether tix-cil 300-300 mg reduced the incidence and disease severity of severe acute respiratory syndrome coronavirus 2 infection in LTRs during the Omicron wave. Methods: We performed a retrospective, single-center cohort study of LTRs who had received a COVID-19 diagnosis between December 2021 and August 2022. We compared baseline characteristics and clinical outcomes after COVID-19 between LTRs who received tix-cil PrEP and those who did not. We then conducted propensity-score matching based on baseline characteristics and therapeutic interventions and compared clinical outcomes between the 2 groups. Results: Of 203 LTRs who received tix-cil PrEP and 343 who did not, 24 (11.8%) and 57 (16.6%), respectively, developed symptomatic COVID-19 (hazard ratio [HR], 0.669; 95% confidence interval [CI], 0.415-1.079; P = 0.099). The hospitalization rate of LTRs with COVID-19 during the Omicron wave trended lower in the tix-cil group than in the non-tix-cil group (20.8% versus 43.1%; HR, 0.430; 95% CI, 0.165-1.118; P = 0.083). In propensity-matched analyses, 17 LTRs who received tix-cil and 17 LTRs who did not had similar rates of hospitalization (HR, 0.468; 95% CI, 0.156-1.402; P = 0.175), intensive care unit admission (HR, 3.096; 95% CI, 0.322-29.771; P = 0.328), mechanical ventilation (HR, 1.958; 95% CI, 0.177-21.596; P = 0.583), and survival (HR, 1.015; 95% CI, 0.143-7.209; P = 0.988). COVID-19-related mortality was high in both propensity-score-matched groups (11.8%). Conclusions: Breakthrough COVID-19 was common among LTRs despite tix-cil PrEP, possibly due to reduced efficacy of monoclonal antibodies against the Omicron variant. Tix-cil PrEP may reduce the incidence of COVID-19 in LTRs, but it did not reduce disease severity during the Omicron wave.

Hospitalized patients with irreversible lung injury from COVID-19 have higher morbidity but similar 1-year survival after lung transplant compared to hospitalized patients transplanted for restrictive lung disease.

BACKGROUND: Hospitalized lung transplant (LT) recipients (LTRs) have higher post-LT morbidity and mortality than those who are well enough to wait for transplant at home. Outcomes after LT for COVID-19-associated acute respiratory distress syndrome (CARDS) may be even worse; thus, we compared post-LT outcomes between hospitalized LTRs transplanted for CARDS and those transplanted for restrictive lung disease (RLD). METHODS: Between 2014 and 2021, hospitalized LTRs ≥18 years old with CARDS or RLD were included. Primary and secondary outcomes were 1-year post-LT survival and postoperative morbidity. For each patient in the CARDS group, an analysis of 1-to-1 matched patients from the RLD group was performed using logistic regression modeling. RESULTS: Of 764 LTRs, 163 (21.3%) were hospitalized at the time of LT; 132 met the inclusion criteria: 11 (8.3%) were transplanted for CARDS and 121 (91.7%) for RLD. LTRs with CARDS were younger with longer pre-LT hospitalization stays and higher rates of pretransplant mechanical ventilation, dialysis, and ECMO as a bridge to transplant. A propensity-matched analysis demonstrated comparable rates of intrathoracic adhesions, posttransplant duration of mechanical ventilation, PGD3 at 72 hours, and delayed chest closure. Compared to LTRs with RLD, those with CARDS had significantly longer posttransplant hospital stays and a higher prevalence of ACR ≥A2 and DSA >2000 MFI, but comparable 1-year survival rates. CONCLUSION: Even with careful selection, LT for patients with CARDS was associated with significant morbidity; however, 1-year survival of recipients with CARDS was comparable to that of matched hospitalized recipients with RLD.

Immune responses of lung transplant recipients against SARS-CoV-2 and common respiratory coronaviruses: Evidence for pre-existing cross-reactive immunity.

Humoral and cellular immune responses to SARS-CoV-2 and other coronaviruses in lung transplant recipients are unknown. We measured antibodies and T cell responses against the SARS-CoV-2 spike S2 and nucleocapsid antigens and spike antigens from common respiratory coronaviruses (229E, NL63, OC43, and HKU1) after vaccination or infection of LTxRs. 148 LTxRs from single center were included in this study: 98 after vaccination and 50 following SARS-CoV-2 infection. Antibodies were quantified by enzyme-linked immunosorbent assay. The frequency of T cells secreting IL2, IL4, IL10, IL17, TNFα, and IFNγ were enumerated by enzyme-linked immunospot assay. Our results have shown the development of antibodies to SARS-CoV-2 spike protein in infected LTxRs (39/50) and vaccinated LTxRs (52/98). Vaccinated LTxRs had higher number of T cells producing TNFα but less cells producing IFNγ than infected LTxRs in response to the nucleocapsid antigen and other coronavirus spike antigens. We didn't find correlation between the development of antibodies and cellular immune responses against the SARS-CoV-2 spike protein after vaccination. Instead, LTxRs have pre-existing cellular immunity to common respiratory coronaviruses, leading to cross-reactive immunity against SARS-CoV-2 which likely will provide protection against SARS-Cov-2 infection.

Loss of IGFBP2 mediates alveolar type 2 cell senescence and promotes lung fibrosis.

Accumulation of senescent cells contributes to age-related diseases including idiopathic pulmonary fibrosis (IPF). Insulin-like growth factor binding proteins (IGFBPs) regulate many biological processes; however, the functional contributions of IGFBP2 in lung fibrosis remain largely unclear. Here, we report that intranasal delivery of recombinant IGFBP2 protects aged mice from weight loss and demonstrated antifibrotic effects after bleomycin lung injury. Notably, aged human-Igfbp2 transgenic mice reveal reduced senescence and senescent-associated secretory phenotype factors in alveolar epithelial type 2 (AEC2) cells and they ameliorated bleomycin-induced lung fibrosis. Finally, we demonstrate that IGFBP2 expression is significantly suppressed in AEC2 cells isolated from fibrotic lung regions of patients with IPF and/or pulmonary hypertension compared with patients with hypersensitivity pneumonitis and/or chronic obstructive pulmonary disease. Altogether, our study provides insights into how IGFBP2 regulates AEC2-cell-specific senescence and that restoring IGFBP2 levels in fibrotic lungs can prove effective for patients with IPF.

Carfilzomib versus rituximab for treatment of de novo donor-specific antibodies in lung transplant recipients.

INTRODUCTION: De novo donor-specific antibodies (DSAs) increase the risk of chronic lung allograft dysfunction (CLAD) in lung transplant recipients (LTRs). Both carfilzomib (CFZ) and rituximab (RTX) lower the mean fluorescent intensity (MFI) of DSAs, but comparative data are lacking. We compared CLAD-free survival and the degree and duration of DSA depletion after treatment of LTRs with CFZ or RTX. METHODS: LTRs that received CFZ or RTX for DSA depletion between 08/01/2015 and 08/31/2020 were included. The primary outcome was CLAD-free survival. Secondary outcomes were change in MFI at corresponding loci within 6 months of treatment (ΔMFI), time to DSA rebound, and change in % predicted FEV1 6 months after treatment (ΔFEV1). RESULTS: Forty-four LTRs were identified, 7 of whom had ≥2 drug events; therefore, 53 drug events were divided into 2 groups, CFZ (n = 17) and RTX (n = 36). Use of plasmapheresis, immunoglobulin, and mycophenolate augmentation was equivalent in both groups. CLAD-free survival with a single RTX event was superior to that after ≥2 drug events (p = 0.001) but comparable to that with a single CFZ event (p = 0.399). Both drugs significantly lowered the MFI at DQ locus, and the median ΔMFI was comparable. Compared to the RTX group, the CFZ group had a shorter median interval to DSA rebound (p = 0.015) and a lower ΔFEV1 at 6 months (p = 0.014). CONCLUSION: Although both CFZ and RTX reduced the MFI of circulating DSAs, RTX prolonged the time to DSA rebound. Despite more pronounced improvement in FEV1 with RTX, comparable CLAD-free survival between the 2 groups suggests that both drugs offer a reasonable treatment strategy for DSAs in LTRs.

Restrictive allograft syndrome vs bronchiolitis obliterans syndrome: Immunological and molecular characterization of circulating exosomes.

BACKGROUND: Chronic lung allograft dysfunction in lung transplant recipients (LTxRs) has 2 phenotypes: obstructive bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS). Our goal was to define distinct immunologic markers of exosomes from LTxRs with BOS or RAS. METHODS: Plasma was collected from LTxRs with BOS (n = 18), RAS (n = 13), and from stable LTxRs (n = 5). Antibodies to lung self-antigens (SAgs) were determined by ELISA. Exosomes were isolated by ultracentrifugation. Donor specific antibodies to HLA were quantified using Luminex. Exosomes were characterized for lung SAgs, transcription factors, 20S proteasome, HLA class I and II, and polymeric immunoglobulin receptor protein using western blot. Exosome miRNA was analyzed using NanoString. The exosome-induced immune response was determined in mice. RESULTS: LTxRs with RAS, but not BOS, had donor specific antibodies at diagnosis. CIITA, NFkB, polymeric immunoglobulin receptor protein, 20S proteasome, HLA-DQ, and HLA-DR were significantly higher in RAS exosomes than in BOS exosomes. RAS plasma had high levels of proinflammatory cytokines and distinct exosomal miRNA. Immunization of C57BL/6 mice with RAS exosomes showed severe inflammation and peribronchial fibrosis, whereas BOS exosomes induced patchy inflammation and fibrosis. CONCLUSION: LTxRs with BOS or RAS had exosomes with distinct molecular and immunologic profiles. RAS samples had a higher concentration of proinflammatory factors, HLA class II, lung SAgs, and antibodies to HLA class II molecules, indicating severe allograft injury. Mice immunized with RAS exosomes developed lesions in airways, pleura, interlobular septum, and alveoli, whereas BOS exosomes induced mild to patchy inflammation with lung fibrosis.

Lung Transplant Candidates With Pretransplant Gastroesophageal Reflux and Antibodies to Lung Self-antigens Have Shorter CLAD-free Survival After Transplant.

Pre-lung transplant (LTx) gastroesophageal reflux (GER) and circulating antibodies against the lung self-antigens (SAbs) collagen V and K-alpha-1 tubulin may predispose recipients to chronic lung allograft dysfunction (CLAD). We aimed to study the association of pre-LTx GER or pre-LTx SAbs with CLAD. METHODS: In this retrospective analysis of patients who underwent LTx between 2015 and 2019, pre-LTx GER and SAbs were dichotomously defined as present or absent. The study group comprised recipients with either GER' SAbs, or both, and the control group comprised recipients without GER or SAbs. Endpoints included CLAD and survival. RESULTS: Ninety-five LTx recipients were divided into a study group (n = 71; 75%) and a control group (n = 24; 25%). Pretransplant GER was associated with pre-LTx SAbs (odds ratio [95% confidence intervals], 5.022 [1.419-17.770]; P = 0.012). In addition, the study group (either GER' SAbs, or both) had a higher risk of CLAD (hazard ratio [95% confidence intervals], 8.787 [1.694-45.567]; P = 0.010) and lower CLAD-free survival after LTx than the control group (P = 0.007); however, overall survival was similar between the 2 groups (P = 0.618). CONCLUSIONS: GER was associated with elevated SAbs in LTx candidates, and either GER, SAbs, or both were associated with CLAD in LTx recipients. This association suggests that GER may cause an immune response to normally sequestered lung-associated self-antigens that drives ongoing lung injury.

Incidentally Detected Malignancies in Lung Explants.

Introduction: Incidentally detected malignancies in lung explants portend risk of early cancer recurrence and metastases with posttransplant immunosuppression. We present a series of lung transplant recipients with previously unverified malignancies in native lung explants. Design: We reviewed the histopathology, radiographic imaging, and management of lung explant malignancies at our institution over 10 years (2011-2020). Endpoints were survival and allograft rejection. Results: An explant malignancy was found in 1.3% (11/855) of lung transplant recipients (6 [55%] men; median age 68 years; 6 [55%] ex-smokers [median pack-years, 25]). Nine (82%) were adenocarcinoma, 1 (9%) was squamous cell carcinoma (SCC), and 1 (9%) was follicular lymphoma. Three patients (27%) had multifocal involvement (≥3 lobes), 4 (36%) had nodal involvement, and the median (range) tumor size was 2.7 (0.4-19) cm. The median interval between last imaging and transplant was 58 (29-144) days. Mycophenolate mofetil was discontinued or reduced in all; everolimus was used in 2 patients, and cisplatin-pemetrexed chemotherapy was used in 2 patients. The prevalence of acute cellular rejection and chronic rejection was 27% and 9%, respectively. Lung recipients with cancer had significantly lower survival than those without (36.4% vs 67.3%, p = 0.002); median survival was 27 (17, 65) months in 4 recipients who were alive and cancer-free at the end of the study period. Conclusions: Unidentified malignancies, commonly adenocarcinoma, can be detected in explanted native lungs. Pneumonectomy may be curative in SCC, lymphoproliferative disorders, and stage I adenocarcinoma. Modulating immunosuppression to prevent allograft rejection and tumor proliferation is warranted.