Lung transplantation is a common treatment for end-stage lung disease (ESLD). Patients present to lung transplantation evaluation on various medications that could impact their candidacy and posttransplant course. In this review, we will discuss pretransplant optimization of pharmacotherapy to minimize complications while waiting for transplant and increase posttransplant success. We will also discuss important considerations for posttransplant immunosuppression, antimicrobial prophylaxis, and complex drug interactions.

Prior to lung transplantation, several medications should be optimized to promote posttransplant success including minimization of corticosteroids, opioids, and benzodiazepines. Lung transplantation candidates should be up to date on vaccinations. Most medications for ESLD are well tolerated to continue up until the point of transplant including antifibrotics, CFTR modulators, and pulmonary vasodilators. Mammalian target of rapamycin inhibitors and other immunosuppressants may need to be stopped or minimized before lung transplantation to minimize posttransplant infection and would healing complications. Medications that increase risk of posttransplant bleeding, thrombosis, or aspiration should be stopped prior to listing.

In this article, we discuss management of pharmacotherapy for lung transplantation candidates to minimize posttransplant complications. Changes in medications for ESLD should be done cautiously to prevent worsening of native disease while waiting for lung transplantation.

To explore the current applications of artificial intelligence and machine learning in lung transplantation, including outcome prediction, drug dosing, and the potential future uses and risks as the technology continues to evolve.

While the use of artificial intelligence (AI) and machine learning (ML) in lung transplantation is relatively new, several groups have developed models to predict short-term outcomes, such as primary graft dysfunction and time-to-extubation, as well as long-term outcomes related to survival and chronic lung allograft dysfunction. Additionally, drug dosing models for Tacrolimus levels have been designed, demonstrating proof of concept for modelling treatment as a time-series problem.

The integration of ML models with clinical decision-making has shown promise in improving post-transplant survival and optimizing donor lung utilization. As technology advances, the field will continue to evolve, with enhanced datasets supporting more sophisticated ML models, particularly through real-time monitoring of biological, biochemical, and physiological data.

To report differences between 2 anticoagulation protocols during venoarterial extracorporeal membrane oxygenation (VA-ECMO) intraoperative support and their effects on outcomes after lung transplantation.

We performed a retrospective analysis of patients undergoing double-lung transplantation with intraoperative VA-ECMO from January 1, 2016, to December 30, 2023. Two distinct anticoagulation protocols were in place during this period. One included targeted activated clotting time >180 seconds at all times with protamine reversal after decannulation. The second included 75 units per kilogram of heparin at the time of cannulation with no redosing plus a tranexamic acid infusion after ECMO initiation.

A total of 116 patients (46 low heparin, 70 standard) were included in the analysis. Cannulation strategies and ECMO circuit were equivalent between the groups. The low-dose heparin protocol group had a shorter surgical time (7.28 hours vs 8.53 hours, P < .001) and required significantly less intraoperative packed red blood cells (median 0 vs 4.37 units, P < .001), fresh-frozen plasma (median 0 vs 2 units, P < .001), platelets (median 0 vs 1 units, P < .001), cryoprecipitate (median 0 vs 0 units, P < .001), and total blood products (median 0 vs 9 units, P < .001) compared with the standard group. There were no differences in rates of deep vein thrombosis (P = .13), airway dehiscence (P > .99), pneumonia (P = .38), or acute kidney injury requiring renal-replacement therapy (P = .59). There was no difference in rates of severe grade 3 primary graft dysfunction at 72 hours after transplant (P = .42).

Our low-dose heparin VA-ECMO protocol for intraoperative support during lung transplantation led to a significant reduction of blood product use. Although this did not translate to a reduced rates of grade 3 primary graft dysfunction, the low-dose heparin protocol was associated with similar postoperative outcomes.

Optimization of donor heart and lung allografts is vital for the post-transplant outcome of the recipient, in terms of survival and quality of life. This requires a holistic approach to the transplant process ensuring optimal donor management, organ procurement and allograft preservation. Advances are being made in static cold storge techniques and in ex vivo organ perfusion. Normothermic perfusion techniques enable functional and/ or biochemical assessment of allografts. Future applications of ex vivo perfusion will enable a platform facilitating the advanced diagnostic assessment of allografts, the administration of advanced therapy to attenuate organ injury and to immunomodulate allografts.

Primary graft dysfunction (PGD) is a common complication after lung transplantation associated with poor outcomes. Although risk factors have been identified, the complex interactions between clinical variables affecting PGD risk are not well understood, which can complicate decisions about donor-lung acceptance. Previously, we developed a machine learning model to predict grade 3 PGD using donor and recipient electronic health record data, but it lacked granular information from donor-lung computed tomography (CT) scans, which are routinely assessed during offer review. In this study, we used a gated approach to determine optimal methods for analyzing donor-lung CT scans among patients receiving first-time, bilateral lung transplants at a single center over 10 years. We assessed 4 computer vision approaches and fused the best with electronic health record data at 3 points in the machine learning process. A total of 160 patients had donor-lung CT scans for analysis. The best imaging-only approach employed a 3D ResNet model, yielding median (interquartile range) areas under the receiver operating characteristic and precision-recall curves of 0.63 (0.49-0.72) and 0.48 (0.35-0.6), respectively. Combining imaging with clinical data using late fusion provided the highest performance, with median areas under the receiver operating characteristic and precision-recall curves of 0.74 (0.59-0.85) and 0.61 (0.47-0.72), respectively.

Primary graft dysfunction (PGD) is the leading cause of early morbidity and mortality following lung transplantation, with neutrophils playing a central role in its inflammatory pathology. Here, we employ single-cell RNA sequencing and spatial transcriptomics to investigate neutrophil subtypes in the lung ischemia-reperfusion injury (IRI) model. We identify CD177+ neutrophils as an activated subpopulation that significantly contributes to lung injury and serves as an early biomarker for predicting severe PGD in human lung transplant recipients (area under the curve [AUC] = 0.871). CD177+ neutrophils exhibit elevated oxidative phosphorylation and increased mitochondrial complex I activity, driving inflammation and the formation of neutrophil extracellular traps. Targeting mitochondrial function with the complex I inhibitor IACS-010759 reduces CD177+ neutrophil activation and alleviates lung injury in both mouse IRI and rat left lung transplant models. These findings provide a comprehensive landscape of CD177+ neutrophil-driven inflammation in lung IRI and highlight its potential value for future early diagnosis and therapeutic interventions.

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.

To predict severe primary graft dysfunction (PGD3) after double-lung transplantation in cystic fibrosis (CF) patients using intraoperative data.

A retrospective single-center cohort study.

University Hospital, France.

CF patients who underwent double-lung transplantation between 2012 and 2019. Patients younger than age 18 and those with multiorgan transplants, retransplantation, or intraoperative cardiopulmonary bypass were excluded.

None.

Sixty-nine variables were recorded in real-time across the nine time-points. PGD3 occurred in 24 patients (15.5%). PGD3 WAS ASSESSED ON POSTOPERATIVE DAY 3: A logistic regression model to predict PGD3 was developed using data collected at nine predefined time-points during surgery, from start (recipient and donor variables) to finish. The model's area under the curve improved progressively during surgery, rising from 0.764 to 0.892. The optimal model incorporated five variables: three associated with reduced PGD3 risk (preoperative pulmonary hypertension, donor body mass index, and PaO₂/FiO₂ ratio at surgery's end) and two were linked to increased risk (lactate level at second pulmonary artery clamping and extracorporeal membrane oxygenation [ECMO] use at surgery's end). The risk of PGD3 increased by a factor of 11.48 (95% CI 4.48-29.39; p < 0.001) when ECMO was required at the end of surgery and by 1.29 (95% CI: 1.02-1.63; p = 0.035) for each 1 mEq/L rise in lactate concentration at time-point 7 (second pulmonary artery clamping).

This predictive model underscores the adverse impact of sustained ECMO placed at the end of surgery and elevated intraoperative lactate levels on PGD3 risk.

Primary graft dysfunction (PGD) after lung transplantation (LTx) heralds significantly worse short- and long-term outcomes. The preoperative presence of recipient left ventricular diastolic dysfunction elevates postcapillary hydrostatic pressures and increases the risk for PGD. In this study, we investigated the role of the left atrial strain (LAS), a recently established sensitive marker of left atrial compliance, as a predictor of PGD.

Preoperative echocardiography of all patients who underwent bilateral LTx at a single center from 2014 to 2024 was analyzed for global myocardial deformation, including the standard phases of LAS reservoir, conduit, and pump as well as left ventricular global longitudinal strain. The presence of PGD grade 3 was defined as P:F <200 at 48 or 72 hours after the operation. Right heart catheterization, standard echocardiographic, and strain indices were subjected to univariable and multivariable analysis to predict PGD.

In total, 132 patients were analyzed, from whom 35 (26.5%) developed PGD. There were no differences in traditional echocardiographic left ventricular diastolic dysfunction biomarkers, including Doppler and tissue Doppler indices, between the PGD (+) and PGD (-) groups. Preoperative right heart catheterization revealed increased mean pulmonary arterial pressure (36 vs 26 mm Hg, P = .003) and median pulmonary vascular resistance (7.8 vs 4.6, P = .001) in the PGD group. Reservoir LAS was reduced in PGD (22.7 ± 7.7 vs 31.5 ± 10.7%, P < .001), followed by reduced conduit LAS (-11.4 ± 6.6 vs -16.0 ± 8.2%, P = .002) and reduced LV GLS (-13.9 ± 3.6 vs -15.8 ± 3.7%, P = .014). In final multivariable model, conduit LAS was independently associated with a greater risk of PGD (odds ratio, 0.88; 95% confidence interval, 0.81-0.95; P = .002) along with greater pulmonary vascular resistance index (odds ratio, 1.13; 95% confidence interval, 1.05-1.25; P = .003). The final model yielded a c-statistic of 0.82, specificity of 93.8%, sensitivity of 40.0%, positive predictive value of 80.8%, and negative predictive value of 70.6%.

Patients with decreased preoperative left atrial compliance assessed by LAS who undergo LTx have a greater risk of developing PGD in the setting of normal LV systolic and diastolic function. Given the increasing use of strain indices, LAS should be considered a risk factor for PGD in prospective studies.

Lung transplantation (LTx) is an effective method for treating end-stage lung disease. The management of lung transplant recipients is a complex, multi-stage process that involves preoperative, intraoperative, and postoperative phases, integrating multidimensional data such as demographics, clinical data, pathology, imaging, and omics. Artificial intelligence (AI) and machine learning (ML) excel in handling such complex data and contribute to preoperative assessment and postoperative management of LTx, including the optimization of organ allocation, assessment of donor suitability, prediction of patient and graft survival, evaluation of quality of life, and early identification of complications, thereby enhancing the personalization of clinical decision-making. However, these technologies face numerous challenges in real-world clinical applications, such as the quality and reliability of datasets, model interpretability, physicians' trust in the technology, and legal and ethical issues. These problems require further research and resolution so that AI and ML can more effectively enhance the success rate of LTx and improve patients' quality of life.

To compare outcomes of single-lung retransplantation (SLRTx) and double-lung retransplantation (DLRTx) after an initial double-lung transplantation.

The Organ Procurement and Transplantation Network/United Network for Organ Sharing database between May 2005 and December 2022 was retrospectively analyzed. Multiorgan transplantations, repeated retransplantations, and lung retransplantations when the status of the initial transplantation was unknown were excluded.

A total of 891 patients were included in the analysis, included 698 (78.3%) with DLRTx and 193 (21.7%) with SLRTx. The mean lung allocation score was higher in the DLRTx group (59.6 ± 20.7 vs 55.1 ± 19.3; P = .007). The use of extracorporeal membrane oxygenation (ECMO) bridge to lung transplantation was similar in the 2 groups (P = .125), as was waitlist time (P = .610). The need for mechanical ventilation (54.6% vs 35.8%; P = .005) and ECMO (17.9% vs 9.0%; P = .069) at 72 hours post-transplantation was greater in the DLRTx group. However, median post-transplantation hospital stay (21.5 [interquartile range (IQR), 12-35] days versus 20 [IQR, 12-35] days; P = .119) and in-hospital mortality (10.9% [n = 76/698] vs 12.4% [n = 24/193]; P = .547) were comparable in the 2 groups. Long-term survival was significantly better in the DLRTx group (P < .001, log-rank test). In the propensity score-weighted multivariable model, the DLRTx group had 28% lower risk of mortality at any point during follow-up compared to the SLRTx group (hazard ratio, 0.72; 95% confidence interval, 0.57-0.91; P = .006).

The less invasiveness of single-lung transplantation in the retransplantation setting has minimal short-term benefit and is associated with significantly worse long-term survival. Double-lung retransplantation should remain the standard for lung retransplantation after initial double-lung transplantation.

Lung ischemia-reperfusion injury (LIRI) is a critical pathological process associated with various clinical conditions, characterised by excessive inflammatory responses and cell death, which can lead to severe respiratory dysfunction and even mortality. However, no effective therapeutic strategy is currently available. This study investigates the protective effects and underlying mechanisms of the Hsp90 inhibitor 17-dimethylaminoethylamino (17-DMAG) in LIRI. An in vivo mouse model of LIRI was established by transiently occluding the left pulmonary hilum with a microvascular clamp, followed by reperfusion. In vitro, necroptosis was induced in BEAS-2B cells using TSZ (TNF-α, Smac mimetic and z-VAD-FMK). Our results demonstrate that 17-DMAG significantly attenuates lung injury, inflammation and epithelial cell necroptosis in mice. Additionally, 17-DMAG mitigates TSZ-induced cell death and inflammatory responses in BEAS-2B cells. Mechanistically, 17-DMAG inhibits the phosphorylation of RIPK1, RIPK3 and MLKL-key necroptotic regulators and client proteins of Hsp90-thereby suppressing necroptosis and reducing the associated inflammatory response. In conclusion, 17-DMAG alleviates LIRI by inhibiting necroptosis and its consequent acute inflammatory cascade. These findings suggest that 17-DMAG may serve as a promising therapeutic candidate for LIRI treatment.

Donor/recipient (D/R) size matching is crucial to achieve proper organ allocation and outcome for lung transplantation (LT). However, studies in this regard have not shown consistent results. We analyzed the results of size-mismatched LT focusing on primary graft dysfunction (PGD) and survival.

A total of 446 patients underwent LT between January 2010 and December 2022. After exclusion, the patients were divided into 3 groups according to the donor/recipient size; D/R ratio >120% was grouped as Over (n = 87), 120%≥D/R ratio≥80% was grouped as Normal (n = 271), 80%>D/R was grouped as Under (n = 19). Early and long-term outcomes were analyzed.

Recipient height, weight, and proportion of male were the highest in the Under group, followed by the Normal and Over groups (P < 0.001). The ratio of extracorporeal membrane oxygenation weaning in the operating room was highest in the Under group, followed by the Normal and Over groups (P : 0.04). The proportions of PGD grade 3 within 48 h and 72 h were highest in the Over group, followed by the Normal and Under groups (P : 0.007 and 0.016, respectively). There was no statistical difference in the pulmonary function test results between the groups at 12 months postoperative follow-up. The 5-year survival rate did not differ among the groups (60.9% vs 56.8% vs 54.7%, Under vs Normal vs Over, P : 0.833) CONCLUSIONS: Although oversized D/R-matched LT demonstrated late recovery during the early postoperative period, their long-term results were non-inferior in terms of the D/R size ratio.

Primary graft dysfunction (PGD) is a major source of morbidity and mortality following lung transplantation, presenting as acute lung injury within 72 hours post-transplantation. Despite advances in surgical techniques and perioperative care, the complex interplay of donor, recipient, and perioperative factors contributes to its development, underscoring the multifactorial nature of PGD. Clinical management of recipients with PGD relies on supportive care strategies, including lung-protective ventilation, inhaled nitric oxide, and extracorporeal membrane oxygenation (ECMO). Severe cases of PGD may result in significant short- and long-term adverse outcomes, including early mortality. Even for patients who recover from PGD, there is also an associated increased risk of chronic lung allograft dysfunction, further compounding its clinical impact. This review provides a brief review of current knowledge regarding PGD, detailing risk factors, diagnostic criteria, and management approaches while identifying critical gaps in understanding its pathophysiology. Ongoing research is essential to develop innovative therapeutic strategies and improve outcomes for lung transplant recipients.

Low muscle mass (LMM) is recognized as a poor prognostic factor in various chronic lung diseases. However, its prognostic impact on recipients of lung transplants remains inconclusive.

We retrospectively analyzed patients who underwent lung transplantation at a tertiary referral center in South Korea. Pretransplant skeletal muscle mass was quantified at the L1 vertebral level by computed tomography scans of the chest using a commercially available body composition analysis software. Patients were classified into LMM and non-LMM group using a threshold for LMM that had been previously validated in the South Korean population. We then evaluated the prognostic impact of preoperative LMM on clinical outcomes after lung transplantation.

A total of 107 patients were included in this analysis, of whom 44 (41.1%) were classified into the LMM group. The median follow-up duration was 958 days posttransplantation. A preoperative LMM was identified as an independent factor associated with a greater risk of overall mortality (adjusted hazard ratio, 2.15; 95% confidence interval, 1.07-4.34). In addition, patients with LMM had a greater risk of developing primary graft dysfunction (adjusted odds ratio, 3.56; 95% confidence interval, 1.25-10.18). At the 1-year follow-up, 37.5% of the patients with baseline LMM had recovered and were reclassified into the non-LMM group, and this improvement was found to mitigate the negative impact of preoperative LMM.

Pretransplant LMM was significantly associated with poor clinical outcomes in recipients of lung transplants. These findings highlight the importance of maintaining adequate muscle mass during the waiting period for lung transplantation.

We conducted a randomized trial of open lung protective ventilation (OLPV) compared to conventional ventilation (CV) in deceased donors. The primary outcome was lung utilization for transplantation.

Eligible donors were ≥13 years with PaO2/FiO2 between 150 and 400 mmHg. Donors were randomized to volume control with OLPV [tidal volume (TV) 8 ml/kg, PEEP 10 cmH2O, protocolized recruitment maneuvers (RM)] or CV [TV 10 ml/kg, PEEP 5 cm H2O, RM only after vent disconnect] for duration of donor management. Lungs were evaluated for transplantation on standardized ventilator settings in both arms [TV 10 ml/kg, PEEP 5 cm H2O, FiO2 1.0].

One hundred and fifty three donors were randomized (74 to OLPV, 79 to CV) and included in the final analysis. Median duration of treatment was 50 hours and did not differ by arm. Donor lung utilization was 23% in the OLPV arm and 22% in the CV arm, p = 0.85. Change in PaO2/FiO2 from randomization to procurement did not differ by treatment; median increase (quartiles) in OLPV versus CV was 68 mmHg (18, 127) vs 74 (-27, 170), p = 0.72. There was no difference in need for vasopressors or serious adverse events between arms. Among 28 lung recipients in whom detailed outcomes were available, duration of mechanical ventilation, ICU stay and hospital stay were not different by treatment arm.

An open lung protective ventilator strategy was safe but did not improve donor lung utilization or oxygenation compared to a conventional ventilator strategy in a population of US organ donors. NCT03439995.

Lung transplantation is indicated for selected patients with advanced pulmonary arterial hypertension (PAH). We used a modified Delphi process to develop recommendations on care of patients with PAH undergoing lung transplantation. This Delphi panel was recruited from the Pulmonary Vascular Research Institute's Innovative Drug Discovery Initiative - Lung Transplantation Workstream, consisting of clinical and research experts in PAH and lung transplantation. In this process, 29 panelists were given open-ended questions, querying topics related to lung transplantation in PAH. A steering group converted the responses into discrete statements. Panelists then rated agreement using a Likert scale in two further survey rounds: -5 (strongly disagree) to 5 (strongly agree). Consensus was defined as mean ≥ 2.5 or ≤ -2.5, with a standard deviation not crossing zero. Consensus was reached on 141 of 223 statements. Notable areas of consensus were for early discussions about transplantation, and agreement with previously published referral and listing criteria. There was agreement that lung transplantation could be offered in sick candidates, including those with concurrent renal or hepatic insufficiency. Bilateral lung transplantation was considered the procedure of choice for most patients, with rare indications for heart-lung transplantation. Consensus on bridging strategies included use of veno-arterial extracorporeal membrane oxygenation and preemptive awake cannulation in those with severe right ventricular dysfunction. Consensus was also achieved on intraoperative use of invasive hemodynamic monitoring, and prolonged postoperative circulatory support guided by hemodynamic response and echocardiography. Patients with PAH undergoing transplantation require specialized management, which differs somewhat from other candidates.

Lower airway enrichment with oral commensals has been previously associated with severe primary graft dysfunction (PGD) after lung transplantation (LT). We aimed to determine whether this dysbiotic signature is present across all PGD severity grades and whether it is associated with a distinct host inflammatory endotype.

Lower airway samples from 96 LT recipients were used to evaluate the lung allograft microbiota via 16S rRNA gene sequencing. Bronchoalveolar lavage (BAL) cytokine concentrations and cell differential percentages were compared across PGD grades. In a subset of samples, we evaluated the lower airway host transcriptome using RNA sequencing methods.

Differential analyses demonstrated lower airway enrichment with supraglottic-predominant taxa (SPT) in moderate and severe PGD. Dirichlet multinomial mixtures modeling identified 2 distinct microbial clusters. A greater percentage of subjects with moderate-severe PGD than no PGD were identified within the dysbiotic cluster (C-SPT, 48% and 29%, respectively) though this did not reach statistical significance (p = 0.06). PGD severity associated with increased BAL neutrophil concentration (p = 0.03) and correlated with BAL concentrations of MCP-1/CCL2, IP-10/CXCL10, IL-10, and TNF-α (p < 0.05). Furthermore, signatures of dysbiosis correlated with neutrophils, MCP-1/CCL-2, IL-10, and TNF-α (p < 0.05). C-SPT exhibited differential expression of TNF, SERPINE1, MPO, and MMP1 genes and upregulation of MAPK pathways, host signling associated with neutrophilic inflammation.

Lower airway dysbiosis within the lung allograft is associated with a neutrophilic inflammatory endotype, an immune profile commonly recognized as the hallmark for PGD. These data highlight a putative role of lower airway microbial dysbiosis in the pathogenesis of this syndrome.

Ischemia-reperfusion injury (IRI) plays a crucial role in the development of primary graft dysfunction (PGD) following lung transplantation. A promising novel approach to optimize donor organs before transplantation and reduce the incidence of PGD is mitochondrial transplantation.

In this study, we explored the delivery of isolated mitochondria in 4 hours ex vivo lung perfusion (EVLP) before transplantation as a means to mitigate IRI. To provide a fresh and viable source of mitochondria, as well as to streamline the workflow without the need for donor muscle biopsies, we investigated the impact of autologous, allogeneic, and xenogeneic mitochondrial transplantation. In the xenogeneic settings, isolated mitochondria from mouse liver were utilized while autologous and allogeneic sources came from pig skeletal muscle biopsies.

Treatment with mitochondrial transplantation increased the P/F ratio and reduced pulmonary peak pressure of the lungs during EVLP, compared to lungs without any mitochondrial transplantation, indicating IRI mitigation. Extensive investigations using advanced light and scanning electron microscopy did not reveal evidence of acute rejection in any of the groups, indicating safe xenotransplantation of mitochondria.

Future work is needed to further explore this novel therapy for combating IRI in lung transplantation, where xenotransplantation of mitochondria may serve as a fresh, viable source to reduce IRI.

Lung transplantation (LTx) significantly improves outcomes for patients with end-stage respiratory failure. However, primary graft dysfunction (PGD) remains one of the most relevant hurdles. Although PGD is attributed to ischemia-reperfusion injury (IRI), immune responses, primarily T cell-mediated, may play a pivotal role in its pathogenesis. Additionally, innate immune activation following IRI links PGD to adaptive alloimmunity, highlighting the impact of early events on LTx outcomes. Immune checkpoints (ICPs) such as PD-1/PD-L1, CD40/CD40LG, and OX40/OX40L, regulate post-LTx T cell responses, and dysregulation of microRNAs (miRNAs) has been implicated in altering ICP expression, influencing the amplification of immune responses. In this preliminary study, we used the taqMan low-density array (TLDA) cards to investigate miRNA dysregulation's prognostic potential as a PGD marker in pre-transplant back-table lung biopsies. Our analysis revealed differential miRNA expression in donor lung tissues, potentially associated with PGD onset, targeting immune regulatory pathways. Specifically, deregulated miRNAs targeted key ICP proteins, including PD-L1, CD40LG, and OX40L. Moreover, the differential expression of these miRNAs was observed in grafts with future PGD compared to grafts without PGD, suggesting a potential prognostic benefit and a possible role for lung tissue miRNAs in the onset of early graft dysfunction. These findings provide a basis for future investigations into their mechanistic roles and therapeutic potential for PGD. Although based on a limited number of cases, our results imply that miRNAs might be involved in early graft dysfunction. While requiring validation in larger cohorts, our data raise the possibility that the evaluation of the aforementioned markers during the pre-transplant phase, might offer a prognostic benefit in monitoring the onset of PGD. Additionally, the use of compounds that can modulate the function of these molecules could be evaluated for the management of LTx patients.

Lung transplantation is the primary treatment for end-stage lung diseases. However, ischemia-reperfusion injury (IRI) significantly impacts transplant outcomes. 4-Octyl itaconate (4-OI) has shown potential in mitigating organ IRI, although its effects in lung transplantation require further exploration.

BEAS-2B cells were used to model transplantation, assessing the effects of 4-OI through viability, apoptosis, and ROS assays. qRT-PCR analyzed cytokine transcription post-cold ischemia/reperfusion (CI/R). RNA sequencing and Gene Ontology analysis elucidated 4-OI's mechanisms of action, confirmed by Western blotting. ALI-airway and lung transplantation organoid models evaluated improvements in bronchial epithelial morphology and function due to 4-OI. ELISA measured IL-6 and IL-8 levels. Rat models of extended cold preservation and non-heart-beating transplantation assessed 4-OI's impact on lung function, injury, and inflammation.

Our findings indicate that 4-OI (100 µM) during cold preservation effectively maintained cell viability, decreased apoptosis, and reduced ROS production in BEAS-2B cells under CI/R conditions. It also downregulated pro-inflammatory cytokine transcription, including IL1B, IL6, and TNF. Inhibition of Nrf2 partially reversed these protective effects. In cold preservation solutions, 4-OI upregulated Nrf2 target genes such as NQO1, HMOX1, and SLC7A11. In ALI airway models, 4-OI enhanced bronchial epithelial barrier integrity and ciliary beat function after CI/R. In rat models, 4-OI administration improved lung function and reduced pulmonary edema, tissue injury, apoptosis, and systemic inflammation following extended cold preservation or non-heart-beating lung transplantation.

Incorporating 4-OI into cold preservation solutions appears promising for alleviating CI/R-induced bronchial epithelial injury and enhancing lung transplant outcomes via Nrf2 pathway activation.

Functional regeneration of the lung's gas exchange surface following injury requires the coordination of a complex series of cell behaviors within the alveolar niche. Using single-cell transcriptomics combined with lineage tracing of proliferating progenitors, we examined mouse lung regeneration after influenza injury, demonstrating an asynchronously phased response across different cellular compartments. This longitudinal atlas of injury responses has produced a catalog of transient and persistent transcriptional alterations in cells as they transit across axes of differentiation. These cell states include an injury-induced capillary endothelial cell (iCAP) that arises after injury, persists indefinitely, and shares hallmarks with developing lung endothelium and endothelial aberrations found in degenerative human lung diseases. This dataset provides a foundational resource to understand the complexity of cellular and molecular responses to injury and correlations to responses found in human development and disease.

Primary graft dysfunction (PGD) affects survival after lung transplant (LT). The current hypothesis was that prone positioning (PP), proposed as a rescue maneuver to treat refractory hypoxemia due to PGD, may improve LT outcomes, especially when applied early.

Bilateral LT recipients developing moderate-to-severe PGD within 24 hours from intensive care unit admission were enrolled. From January 2020 to November 2021, patients developing PGD after LT were turned prone between 24 and 48 hours after diagnosis, only in case of radiological or oxygenation worsening ("late PP" group). After November 2021, patients were routinely turned prone within 24 hours from PGD diagnosis ("early PP"). A propensity score-weighted analysis, adjusted for clinically relevant covariates, was applied.

Intensive care unit.

Bilateral LT recipients.

Early PP, late PP, or supine position.

130 LT patients were screened and 67 were enrolled. A total of 25 (37%) recipients were treated in the supine position, 24 (36%) in early PP, and 18 (27%) in late PP. After propensity score weighting, both supine treatment (estimated effect for 1 ventilator-free day = 8.23, standard error: 2.97, p = 0.007) and early PP treatment (estimated effect = 9.42, standard error: 2.59, p < 0.001) were associated with greater 28-day ventilator-free days than late PP treatment (reference). Compared with late PP, early PP was also associated with better oxygenation, driving pressure, and static respiratory system compliance. Compared with supine recipients, the early PP group showed better oxygenation at 72 hours after PGD diagnosis.

Early PP in LT recipients with moderate-to-severe PGD seems to be associated with better 28-day ventilator-free days, oxygenation, and driving pressure than late PP.

Ischemia-reperfusion injury (IRI) stands as a major trigger for primary graft dysfunction (PGD) in lung transplantation (LTx). Especially in LTx from donation after cardiac death (DCD), effective control of IRI following warm ischemia (WIRI) is crucial to prevent PGD. This study aimed to identify the key factors affecting WIRI in LTx from DCD.

Previously reported RNA-sequencing dataset of lung WIRI was reanalyzed to identify nuclear receptor subfamily 4 group A member 1 (NR4A1) as the immediate early gene for WIRI. Dynamics of NR4A1 expression were verified using a mouse hilar clamp model. To investigate the role of NR4A1 in WIRI, a mouse model of LTx from DCD was established using Nr4a1 knockout (Nr4a1-/-) mice.

NR4A1 was located around vascular cells, and its protein levels in the lungs increased rapidly and transiently during WIRI. LTｘ from Nr4a1-/- donors significantly improved pulmonary graft function compared to wild-type donors. Histological analysis showed decreased microvascular endothelial cell death, neutrophil infiltration, and albumin leakage. Evans blue permeability assay demonstrated maintained pulmonary microvascular barrier integrity in grafts from Nr4a1-/- donors, correlating with diminished pulmonary edema. However, NR4A1 did not significantly affect the inflammatory response during WIRI, and IRI was not suppressed when a wild-type donor lung was transplanted into the Nr4a1-/- recipient.

Donor NR4A1 plays a specialized role in the positive regulation of endothelial cell injury and microvascular hyperpermeability. These findings demonstrate the potential of targeting NR4A1 interventions to alleviate PGD and improve outcomes in LTx from DCD.

Post-capillary hypertension resulting from mitral regurgitation is typically considered a contraindication for single lung transplantation due to heightened risks of primary graft dysfunction. This case report highlights a 66-year-old COPD patient with severe mitral regurgitation who was deemed ineligible for surgical mitral replacement. As an alternative, transcatheter mitral valve replacement was successfully performed, resulting in the normalization of pulmonary artery pressures. Consequently, the patient became eligible for single lung transplantation, which was conducted successfully in the subsequent months. Eighteen months post-lung transplantation, the patient now experiences a normal functional status and excellent lung function. In conclusion, transcatheter mitral valve replacement appears to be a safe alternative to surgery for normalizing post-capillary pulmonary hypertension in patients with chronic respiratory diseases. This approach could potentially facilitate lung transplantation (LTx) in eligible candidates.

Primary graft dysfunction (PGD) develops within 72 h after lung transplantation (Lung Tx) and greatly influences patients' prognosis. This study aimed to establish an accurate machine learning (ML) model for predicting grade 3 PGD (PGD3) after Lung Tx.

This retrospective study incorporated 802 patients receiving Lung Tx between July 2018 and October 2023 (640 in the derivation cohort and 162 in the external validation cohort), and 640 patients were randomly assigned to training and internal validation cohorts in a 7:3 ratio. Independent risk factors for PGD3 were determined by integrating the univariate logistic regression and least absolute shrinkage and selection operator regression analyses. Subsequently, 9 ML models were used to construct prediction models for PGD3 based on selected variables. Their prediction performances were further evaluated. Besides, model stratification performance was assessed with 3 posttransplant metrics. Finally, the SHapley Additive exPlanations algorithm was used to understand the predictive importance of selected variables.

We identified 9 independent clinical risk factors as selected variables. Among 9 ML models, the random forest (RF) model displayed optimal performance (area under the curve [AUC] = 0.9415, sensitivity [Se] = 0.8972, specificity [Sp] = 0.8795 in the training cohort; AUC = 0.7975, Se = 0.7520, Sp = 0.7313 in the internal validation cohort; and AUC = 0.8214, Se = 0.8235, Sp = 0.6667 in the external validation cohort). Further assessments on calibration and clinical usefulness indicated the promising applicability of the RF model in PGD3 prediction. Meanwhile, the RF model also performed best in terms of risk stratification for postoperative support (extracorporeal membrane oxygenation time: P < 0.001, mechanical ventilation time: P = 0.006, intensive care unit time: P < 0.001).

The RF model had the optimal performance in PGD3 prediction and postoperative risk stratification for patients after Lung Tx.

Primary graft dysfunction (PGD) contributes substantially to both short- and long-term mortality after lung transplantation, but the mechanisms that lead to PGD are not well understood. Exposure to ambient air pollutants is associated with adverse events during waitlisting for lung transplantation and chronic lung allograft dysfunction, but its association with PGD has not been studied. We hypothesized that long-term exposure of the lung donor and recipient to high levels of ambient air pollutants would increase the risk of PGD in lung transplant recipients.

Using data from 1428 lung transplant recipients and their donors enrolled in the Lung Transplant Outcomes Group observational cohort study, we evaluated the association between the development of PGD and zip-code-based estimates of long-term exposure to 6 major air pollutants (ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, particulate matter 2.5, and particulate matter 10) in both the lung donor and the lung recipient. Exposure estimates used daily EPA air pollutant monitoring data and were based on the geographic centroid of each subject's residential zip code. Associations were tested in both univariable and multivariable models controlling for known PGD risk factors.

We did not find strong associations between air pollutant exposures in either the donor or the recipient and PGD.

Exposure to ambient air pollutants, at the levels observed in this study, may not be sufficiently harmful to prime the donor lung or the recipient to develop PGD, particularly when considering the robust associations with other established PGD risk factors.

Cell dysfunction and death induced by lung ischaemia-reperfusion injury (LIRI) are the main causes of death in transplant patients. Activation of the cGAS-STING-induced immune response and death plays a critical role in multiple organ injuries. However, no study has yet investigated the role of the cGAS-STING pathway in LIRI after lung transplantation.

Sprague-Dawley (SD) rats were subjected to left lung transplantation and administered inhibitors of cGAS and STING. The expression of cGAS-STING-TBK1-IRF3, histological injury, pulmonary permeability, and the levels of cytokines and pyroptotic proteins in transplanted lungs were tested. Endothelial cells were subjected to hypoxemia and reoxygenation and treated with inhibitors of cGAS and STING. Mitochondrial DNA (mtDNA), the cGAS-STING axis and cytokine levels in cells, cellular activity and death were evaluated. Moreover, after the administration of deoxyribonuclease (DNase) I, the reoxygenated endothelial cells were also examined for cellular function and inflammatory factor expression. Finally, we administered an agonist of STING and an inhibitor of cathepsin B to the normal endothelium and investigated pyroptosis and pyroptotic proteins.

After 24 h of reperfusion, the expression of cGAS-STING-TBK1-IRF3 and pyroptotic proteins was significantly increased, and inhibitors of cGAS or STING ameliorated lung injury and reduced pyroptotic protein levels. In vitro, the inhibition of cGAS and STING reduced the activation of TBK and IRF3 and reduced cellular injury and death. The activation of cGAS-STING and cellular inflammation were suppressed by DNase I. Cathepsin B and NLRP3 were upregulated by an agonist of STING, and an inhibitor of cathepsin B reduced NLRP3 levels.

cGAS-STING participated in LIRI by promoting endothelial cell pyroptosis via cathepsin B.

Lung transplant (LUTX) candidates have subclinical right ventricular (RV) dysfunction, which has not yet been assessed by speckle-tracking echocardiography (STE)-derived RV free-wall longitudinal strain (RVFWLS). To evaluate the prevalence of RV dysfunction by RVFWLS and its relationship with conventional RV echocardiographic indexes in LUTX candidates.

In a single-center prospective observational cohort study, from January 2021 to March 2023 consecutive LUTX candidates underwent cardiac catheterization, radionuclide ventriculography, standard and STE. The diagnostic accuracy of RV ejection fraction by ventriculography (RVEF), tricuspid annular plane excursion (TAPSE), fractional area change (FAC), tricuspid peak annulus systolic velocity (S') versus RVFWS were computed.

Thirty-four patients (female, 41%) with a mean age of 48 [36-59] years old enlisted for pulmonary fibrosis (35%) and cystic fibrosis (30%) were included. At cardiac catheterization, only 7 (23%) had pulmonary hypertension. Around 15-25% presented right heart enlargement. Tricuspid regurgitation was present in 20 (60%) of the patients. Median RVFWLS was -20.1% [-22.5%--17%], being impaired (> -20%) in 16 (47%) of the patients. RVFWLS identified the highest percentage (47%) of RV dysfunction, compared to TAPSE (32%), S' (27%), FAC (26%), and ventriculography (15%), which had very low sensitivity for detecting RV dysfunction compared to RVFWLS.

In patients enlisted for LUTX, RV dysfunction assessed by STE-derived RVFWLS is highly prevalent. STE can detect RV dysfunction better than standard two-dimensional echocardiography and ventriculography. Further studies are urgently needed to define the clinical implications and the prognostic value of RV dysfunction measured with RVFWLS.

Hermansky-Pudlak syndrome (HPS) is a genetic disorder of endosomal protein trafficking associated with pulmonary fibrosis in specific subtypes, including HPS-1 and HPS-2. Single-mutant HPS1 and HPS2 mice display increased fibrotic sensitivity while double-mutant HPS1/2 mice exhibit spontaneous fibrosis with aging, which has been attributed to HPS mutations in alveolar epithelial type II (AT2) cells. We utilized HPS mouse models and human lung tissue to investigate mechanisms of AT2 cell dysfunction driving fibrotic remodeling in HPS. Starting at 8 weeks of age, HPS mice exhibited progressive loss of AT2 cell numbers. HPS AT2 cell function was impaired ex vivo and in vivo. Incorporating AT2 cell lineage tracing in HPS mice, we observed aberrant differentiation with increased AT2-derived alveolar epithelial type I cells. Transcriptomic analysis of HPS AT2 cells revealed elevated expression of genes associated with aberrant differentiation and p53 activation. Lineage-tracing and organoid-modeling studies demonstrated that HPS AT2 cells were primed to persist in a Keratin-8-positive reprogrammed transitional state, mediated by p53 activity. Intrinsic AT2 progenitor cell dysfunction and p53 pathway dysregulation are mechanisms of disease in HPS-related pulmonary fibrosis, with the potential for early targeted intervention before the onset of fibrotic lung disease.

Hermansky-Pudlak syndrome (HPS) is a genetic disorder of endosomal protein trafficking associated with pulmonary fibrosis in specific subtypes, including HPS-1 and HPS-2. Single mutant HPS1 and HPS2 mice display increased fibrotic sensitivity while double mutant HPS1/2 mice exhibit spontaneous fibrosis with aging, which has been attributed to HPS mutations in alveolar epithelial type II (AT2) cells. We utilized HPS mouse models and human lung tissue to investigate mechanisms of AT2 cell dysfunction driving fibrotic remodeling in HPS. Starting at 8 weeks of age, HPS mice exhibited progressive loss of AT2 cell numbers. HPS AT2 cell function was impaired ex vivo and in vivo . Incorporating AT2 cell lineage tracing in HPS mice, we observed aberrant differentiation with increased AT2-derived alveolar epithelial type I cells. Transcriptomic analysis of HPS AT2 cells revealed elevated expression of genes associated with aberrant differentiation and p53 activation. Lineage tracing and organoid modeling studies demonstrated that HPS AT2 cells were primed to persist in a Krt8 + reprogrammed transitional state, mediated by p53 activity. Intrinsic AT2 progenitor cell dysfunction and p53 pathway dysregulation are novel mechanisms of disease in HPS-related pulmonary fibrosis, with the potential for early targeted intervention before the onset of fibrotic lung disease.

By causing inflammation and tissue damage, neutrophil extracellular traps (NETs) constitute an underlying mechanism of aspiration-induced lung injury, a major factor of the low utilization of donor lungs in lung transplantation (LTx).

To determine whether NET removal during ex vivo lung perfusion (EVLP) can restore lung function and morphology in aspiration-damaged lungs, gastric aspiration lung injury was induced in 12 pigs. After confirmation of acute respiratory distress syndrome, the lungs were explanted and assigned to NET removal connected to EVLP (treated) (n = 6) or EVLP only (nontreated) (n = 6). Hemodynamic measurements were taken, and blood and tissue samples were collected to assess lung function, morphology, levels of cell-free DNA, extracellular histones, and nucleosomes as markers of NETs, as well as cytokine levels.

After EVLP and NET removal in porcine lungs, PaO2/FiO2 ratios increased significantly compared to those undergoing EVLP alone (p = 0.0411). Treated lungs had lower cell-free DNA (p = 0.0260) and lower levels of extracellular histones in EVLP perfusate (p= 0.0260) than nontreated lungs. According to histopathology, treated lungs showed less immune cell infiltration and less edema compared with nontreated lungs, which was reflected in decreased levels of proinflammatory cytokines in EVLP perfusate and bronchoalveolar lavage fluid.

To conclude, removing NETs during EVLP improved lung function and morphology in aspiration-damaged donor lungs. The ability to remove NETs during EVLP could represent a new therapeutic approach for LTx and potentially expand the donor pool for transplantation.