Predictors of early mortality after lung transplantation for idiopathic pulmonary arterial hypertension.

Lung transplantation remains an important therapeutic option for idiopathic pulmonary arterial hypertension (IPAH), yet short-term survival is the poorest among the major diagnostic categories. We sought to develop a prediction model for 90-day mortality using the United Network for Organ Sharing database for adults with IPAH transplanted between 2005 and 2021. Variables with a p value ≤ 0.1 on univariate testing were included in multivariable analysis to derive the best subset model. The cohort comprised 693 subjects, of whom 71 died (10.2%) within 90 days of transplant. Significant independent predictors of early mortality were: extracorporeal circulatory support and/or mechanical ventilation at transplant (OR: 3; CI: 1.4-5), pulmonary artery diastolic pressure (OR: 1.3 per 10 mmHg; CI: 1.07-1.56), forced expiratory volume in the first second percent predicted (OR: 0.8 per 10%; CI: 0.7-0.94), recipient total bilirubin >2 mg/dL (OR: 3; CI: 1.4-7.2) and ischemic time >6 h (OR: 1.7, CI: 1.01-2.86). The predictive model was able to distinguish 25% of the cohort with a mortality of ≥20% from 49% with a mortality of ≤5%. We conclude that recipient variables associated with increasing severity of pulmonary vascular disease, including pretransplant advanced life support, and prolonged ischemic time are important risk factors for 90-day mortality after lung transplant for IPAH.

Differential Transcriptomic Signatures of Small Airway Cell Cultures Derived from IPF and COVID-19-Induced Exacerbation of Interstitial Lung Disease.

Idiopathic pulmonary fibrosis (IPF) is a pathological condition wherein lung injury precipitates the deposition of scar tissue, ultimately leading to a decline in pulmonary function. Existing research indicates a notable exacerbation in the clinical prognosis of IPF patients following infection with COVID-19. This investigation employed bulk RNA-sequencing methodologies to describe the transcriptomic profiles of small airway cell cultures derived from IPF and post-COVID fibrosis patients. Differential gene expression analysis unveiled heightened activation of pathways associated with microtubule assembly and interferon signaling in IPF cell cultures. Conversely, post-COVID fibrosis cell cultures exhibited distinctive characteristics, including the upregulation of pathways linked to extracellular matrix remodeling, immune system response, and TGF-ß1 signaling. Notably, BMP signaling levels were elevated in cell cultures derived from IPF patients compared to non-IPF control and post-COVID fibrosis samples. These findings underscore the molecular distinctions between IPF and post-COVID fibrosis, particularly in the context of signaling pathways associated with each condition. A better understanding of the underlying molecular mechanisms holds the promise of identifying potential therapeutic targets for future interventions in these diseases.

Pulmonary, circulatory and renal considerations in the early postoperative management of the lung transplant recipient.

Lung transplantation volumes and survival rates continue to increase worldwide. Primary graft dysfunction (PGD) and acute kidney injury (AKI) are common early postoperative complications that significantly affect short-term mortality and long-term outcomes. These conditions share overlapping risk factors and are driven, in part, by circulatory derangements. The prevalence of severe PGD is up to 20% and is the leading cause of early death. Patients with pulmonary hypertension are at a higher risk. Prevention and management are based on principles learned from acute lung injury of other causes. Targeting the lowest effective cardiac filling pressure will reduce alveolar edema formation in the setting of increased pulmonary capillary permeability. AKI is reported in up to one-half of lung transplant recipients and is strongly associated with one-year mortality as well as long-term chronic kidney disease. Optimization of renal perfusion is critical to reduce the incidence and severity of AKI. In this review, we highlight key early post-transplant pulmonary, circulatory, and renal perturbations and our center's management approach.

Targeting ATP12A, a Nongastric Proton Pump α Subunit, for Idiopathic Pulmonary Fibrosis Treatment.

Idiopathic pulmonary fibrosis (IPF) is a pathological condition of unknown etiology that results from injury to the lung and an ensuing fibrotic response that leads to the thickening of the alveolar walls and obliteration of the alveolar space. The pathogenesis is not clear, and there are currently no effective therapies for IPF. Small airway disease and mucus accumulation are prominent features in IPF lungs, similar to cystic fibrosis lung disease. The ATP12A gene encodes the α-subunit of the nongastric H+, K+-ATPase, which functions to acidify the airway surface fluid and impairs mucociliary transport function in patients with cystic fibrosis. It is hypothesized that the ATP12A protein may play a role in the pathogenesis of IPF. The authors' studies demonstrate that ATP12A protein is overexpressed in distal small airways from the lungs of patients with IPF compared with normal human lungs. In addition, overexpression of the ATP12A protein in mouse lungs worsened bleomycin induced experimental pulmonary fibrosis. This was prevented by a potassium competitive proton pump blocker, vonoprazan. These data support the concept that the ATP12A protein plays an important role in the pathogenesis of lung fibrosis. Inhibition of the ATP12A protein has potential as a novel therapeutic strategy in IPF treatment.

Outcomes of partial fundoplication for GERD-related allograft decline after lung transplantation.

INTRODUCTION: Gastroesophageal reflux disease contributes to allograft decline secondary to bronchiolitis obliterans after lung transplantation. Antireflux surgery (ARS) slows the decline in lung function related to GERD. ARS operations range from Nissen fundoplications to partial fundoplications, such as the Toupet and Dor. Research in the general population has indicated that partial fundoplication is effective at controlling reflux. We explored lung function and reflux outcomes in a cohort of lung transplant patients who received partial fundoplications. METHODS: Data from an institutional lung transplant registry was reviewed for patients between 2009 and 2020 who underwent fundoplication after transplant. Lung transplant patients underwent routine pulmonary function testing. Patients with FEV1 values within 180 days pre-fundoplication and two years post-fundoplication were included in the analysis. All patients referred for fundoplication underwent esophageal pH testing, manometry, UGI, and EGD. Most patients underwent Toupet fundoplication, but those with severe dysmotility underwent Dor fundoplication. RESULTS: 53 patients were included in the analysis. Median time to fundoplication after transplant was 403 days. 48 patients underwent Toupet fundoplication. Five underwent Dor fundoplication. 40% of patients had abnormal high-resolution manometry. A linear mixed-effects model tested for a change in FEV1 trajectory up to two years post-fundoplication with an auto-regressive correlation structure. Post-fundoplication FEV1 values decreased by 7 mL per month, and suggested a slow in the decline by 2 mL per month, but this was not significant (p = 0.8). In patients for whom postoperative DeMeester scores were available (19), there was a decline in acid exposure from a median of 45.8 to 1.8 after ARS (p = 0.0003). CONCLUSION: Although our results did not reach statistical significance, there was a trend towards a decrease in the rate of decline of allograft function before and after partial fundoplication. In the patients whom results were available, a partial fundoplication appropriately controlled acid exposure.

Treatment of Gastroesophageal Reflux Disease After Lung Transplant Using Radiofrequency Ablation to the Lower Esophageal Sphincter (Stretta Procedure).

BACKGROUND: Gastroesophageal reflux disease (GERD) is associated with chronic lung allograft dysfunction after lung transplant. Treating GERD after lung transplant has been shown to improve lung allograft function. This case series describes the efficacy of the Stretta procedure to control GERD after lung transplant at our institution. METHODS: Eleven patients underwent the Stretta procedure at our institution for GERD after lung transplant during the years 2016-2017. Pre- and post-Stretta reflux parameters were gathered. Pulmonary function was followed up until subsequent fundoplication surgery, death, or end of study observation. RESULTS: Reflux on esophagram was noted in 9 patients before Stretta and 8 patients after Stretta. The median number of acid reflux events was 31.5 vs. 26 after Stretta (P = .95), and median percent time in reflux was 17.7% before vs. 14.5% after Stretta (P = .76). Median DeMeester score before Stretta was 65.5 (range: 33.2-169.8) vs. 42.5 (range: 19.2-109.8) after the procedure (P = .14). Median lower esophageal resting pressure was 20.7 mm Hg (n = 7) compared to 25.9 mm Hg (n = 9) on post-Stretta follow-up (P = .99). Median FEV1% predicted was 84% (41-97%) before compared to 71% (23-108%) at 1 year after the procedure (P = .14). Seven patients required fundoplication surgery for continued reflux. All patients were on triple immunosuppression, most commonly prednisone, tacrolimus, and mycophenolate (n = 9). DISCUSSION: The Stretta procedure did not provide expected results at our institution after lung transplant surgery. Based on our limited series, we do not recommend routine use of the Stretta procedure for management of GERD in lung transplant patients.

COVID-19 in hospitalized lung and non-lung solid organ transplant recipients: A comparative analysis from a multicenter study.

Lung transplant recipients (LTR) with coronavirus disease 2019 (COVID-19) may have higher mortality than non-lung solid organ transplant recipients (SOTR), but direct comparisons are limited. Risk factors for mortality specifically in LTR have not been explored. We performed a multicenter cohort study of adult SOTR with COVID-19 to compare mortality by 28 days between hospitalized LTR and non-lung SOTR. Multivariable logistic regression models were used to assess comorbidity-adjusted mortality among LTR vs. non-lung SOTR and to determine risk factors for death in LTR. Of 1,616 SOTR with COVID-19, 1,081 (66%) were hospitalized including 120/159 (75%) LTR and 961/1457 (66%) non-lung SOTR (p = .02). Mortality was higher among LTR compared to non-lung SOTR (24% vs. 16%, respectively, p = .032), and lung transplant was independently associated with death after adjusting for age and comorbidities (aOR 1.7, 95% CI 1.0-2.6, p = .04). Among LTR, chronic lung allograft dysfunction (aOR 3.3, 95% CI 1.0-11.3, p = .05) was the only independent risk factor for mortality and age >65 years, heart failure and obesity were not independently associated with death. Among SOTR hospitalized for COVID-19, LTR had higher mortality than non-lung SOTR. In LTR, chronic allograft dysfunction was independently associated with mortality.

Pulmonary hypertension in fibrosing idiopathic interstitial pneumonia: Uncertainties, challenges and opportunities.

Pulmonary hypertension is a serious complication of chronic fibrosing idiopathic interstitial pneumonia (PH-fIIP) leading to greater morbidity and mortality. The pathophysiologic basis for PH in fIIP is not completely understood, but microvascular rarefaction may play a key role. Severe hypoxemia and reduced diffusion capacity are characteristic. Doppler echocardiography has limited diagnostic utility and right heart catheterization is required to confirm the diagnosis. Lung volumes can be minimally affected, and radiographic findings can be subtle, making the distinction from pulmonary arterial hypertension challenging. Several randomized controlled trials of pulmonary arterial hypertension targeted therapies have recently been completed. Endothelin-receptor antagonists have shown either no benefit or harm. Sildenafil may have some favorable short-term effects but does not appear to impact long-term outcomes. Riociguat treatment increased hospitalizations and mortality. A recent trial of inhaled treprostinil demonstrated improved exercise capacity, but the impact on long-term morbidity and mortality are unknown. Currently, the only viable option for improved survival is lung transplantation. Early referral is imperative to optimize post-transplant outcomes.

Transduction of Pig Small Airway Epithelial Cells and Distal Lung Progenitor Cells by AAV4.

Cystic fibrosis (CF) is caused by genetic mutations of the CF transmembrane conductance regulator (CFTR), leading to disrupted transport of Cl- and bicarbonate and CF lung disease featuring bacterial colonization and chronic infection in conducting airways. CF pigs engineered by mutating CFTR develop lung disease that mimics human CF, and are well-suited for investigating CF lung disease therapeutics. Clinical data suggest small airways play a key role in the early pathogenesis of CF lung disease, but few preclinical studies have focused on small airways. Efficient targeted delivery of CFTR cDNA to small airway epithelium may correct the CFTR defect and prevent lung infections. Adeno-associated virus 4 (AAV4) is a natural AAV serotype and a safe vector with lower immunogenicity than other gene therapy vectors such as adenovirus. Our analysis of AAV natural serotypes using cultured primary pig airway epithelia showed that AAV4 has high tropism for airway epithelia and higher transduction efficiency for small airways compared with large airways. AAV4 mediated the delivery of CFTR, and corrected Cl- transport in cultured primary small airway epithelia from CF pigs. Moreover, AAV4 was superior to all other natural AAV serotypes in transducing ITGα6ß4+ pig distal lung progenitor cells. In addition, AAV4 encoding eGFP can infect pig distal lung epithelia in vivo. This study demonstrates AAV4 tropism in small airway progenitor cells, which it efficiently transduces. AAV4 offers a novel tool for mechanistical study of the role of small airway in CF lung pathogenesis in a preclinical large animal model.

Emergency Use of Occlutech® Atrial Flow Regulator Device Facilitates Weaning From Veno-Arterial Extracorporeal Membrane Oxygenation in a Patient With Severe Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is a severe and progressive disease. Treatment options include anti-PAH medications, continuous intravenous therapies, and diuretics. Lung transplant is required in many cases. Atrial septostomy is an under recognized option in symptomatic patients on maximal PAH therapy. However, creating a sustainable and restrictive atrial communication is challenging with existing devices. We describe emergency use of the Occlutech® Atrial Flow Regulator, a novel device, in a 35-year-old female with PAH supported on veno-arterial extracorporeal membrane oxygenation after postpartum decompensation.

Report from the 2018 consensus conference on immunomodulating agents in thoracic transplantation: Access, formulations, generics, therapeutic drug monitoring, and special populations.

In 2009, the International Society for Heart and Lung Transplantation recognized the importance and challenges surrounding generic drug immunosuppression. As experience with generics has expanded and comfort has increased, substantial issues have arisen since that time with other aspects of immunomodulation that have not been addressed, such as access to medicines, alternative immunosuppression formulations, additional generics, implications on therapeutic drug monitoring, and implications for special populations such as pediatrics and older adults. The aim of this consensus document is to address critically each of these concerns, expand on the challenges and barriers, and provide therapeutic considerations for practitioners who manage patients who need to undergo or have undergone cardiothoracic transplantation.

Everolimus Use for Intolerance or Failure of Baseline Immunosuppression in Adult Heart and Lung Transplantation.

BACKGROUND Everolimus can be utilized after heart or lung transplantation to reduce calcineurin inhibitor associated nephrotoxicity, due to cell cycle inhibitor adverse effects, and as adjunct therapy for rejection, cardiac allograft vasculopathy, and bronchiolitis obliterans syndrome. MATERIAL AND METHODS A single-center, retrospective cohort study was conducted including 51 adult heart transplant patients (n=32) and lung transplant patients (n=19) started on everolimus due to immunosuppressive therapy intolerance or failure, between 2010 and 2017. Everolimus indication, response, efficacy, and tolerability were assessed. RESULTS Everolimus was most commonly initiated due to leukopenia/neutropenia (n=17, 33%) or renal dysfunction (n=13, 25%). Leukopenia/neutropenia resolved in 76% of patients (13 out of 17 patients). Renal function (GFR) increased 7.4 mL/min from baseline to 3 months after everolimus initiation (P=0.011). The most common adverse effects were edema (n=23, 45%) and hyperlipidemia (n=25, 49%). A high discontinuation rate was observed (n=21, 41%), mostly from edema. CONCLUSIONS Everolimus might be beneficial in heart and lung transplant patients with leukopenia or neutropenia and lead to modest, short-term renal function improvement. Patient selection is crucial because adverse effects frequently lead to everolimus discontinuation.

Lung transplantation in idiopathic pulmonary fibrosis.

INTRODUCTION: Idiopathic Pulmonary Fibrosis (IPF) is a unique type of interstitial pneumonia in which progressive fibrosis can ultimately result in respiratory failure and death. The median survival of IPF remains dismal despite newer anti-fibrotic therapies. Lung transplantation is the only modality currently known to enhance survival for patients with IPF. Areas covered: Since IPF is predominantly a disorder of the elderly, determination of the impact of co-morbidities is crucial for risk stratification of the individual patient. We review the potential effect of anti-fibrotic therapy in the pre and post-transplant period; and also discuss the factors that need to be considered in deciding between single lung and bilateral lung transplantation. Expert commentary: Early referral to a transplant center is recommended for patients with IPF due to the high waiting list mortality. Evaluation of the transplant candidate should also be directed specifically at identifying co-morbidities that portend higher risk. While there has been a universal trend favoring bilateral lung transplantation over single lung transplantation for IPF, there are inherent pros and cons for both strategies and decisions should be individualized. Further studies are required to deduce the efficacy and safety of anti-fibrotic drugs in the immediate pre-and post-lung transplantation period.

Individualizing immunosuppression in lung transplantation.

Immunosuppression management after lung transplantation continues to evolve, with an increasing number of agents available for use in various combinations allowing for more choice and individualization of immunosuppressive therapy. Therapeutic developments have led to improved outcomes including lower acute rejection rates and improved survival. However, a one size fits all approach for any immunosuppressive strategy may not be best suited to the individual patient and ultimately patient specific factors must be considered when designing the immunosuppressive regimen. Recipient factors including age, race, co-morbidities, immunologic risk, genetic polymorphisms, concomitant and previous pharmacotherapy, and overall immunosuppression burden should be considered. There are several significant drug-drug interactions with select immunosuppressive agents utilized in lung transplant pharmacotherapy that must be considered when choosing and devising a dosing strategy for an individual immunosuppressive agent. Herein, considerations for immunosuppression management in the individual patient will be reviewed.

The impact of ambrisentan and tadalafil upfront combination therapy on cardiac function in scleroderma associated pulmonary arterial hypertension patients: cardiac magnetic resonance feature tracking study.

The aim of this study was to evaluate the effect of upfront combination therapy with ambrisentan and tadalafil on left ventricular (LV) and right ventricular (RV) function in patients with systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH). LV and RV peak longitudinal and circumferential strain and strain rate (SR), which consisted of peak systolic SR (SRs), peak early diastolic SR (SRe), and peak atrial-diastolic SR (SRa) were analyzed using cardiac magnetic resonance imaging (CMRI) data from the recently published ATPAHSS-O trial (ambrisentan and tadalafil upfront combination therapy in SSc-PAH). Twenty-one patients completed the study protocol. Measures of RV systolic function (RV free wall [RVFW] peak longitudinal strain [pLS], RVFW peak longitudinal SRs [pLSRs]) and RV diastolic function (RVFW peak longitudinal SRa [pLSRa], RVFW peak circumferential SRe) were improved after treatment. LV systolic function (LV peak global longitudinal strain [pGLS]) and diastolic function (LV peak global longitudinal SRe [pGLSRe]) were also significantly improved at follow-up. Increased 6-min walk distance was significantly correlated with RVFW pLS and pLSRs, while the decrease in N-terminal pro-brain natriuretic peptide was correlated with LV pGLS. Increased cardiac index was associated with improved LV pGLSRe, and reduction in mean right atrial pressure was correlated with improved RVFW pLS and pLSRa. Combination therapy was associated with a significant improvement in both RV and LV function as assessed by CMR-derived strain and SR. Importantly, the improvement in RV and LV strain and SR correlated with improvements in known prognostic markers of PAH. (Approved by clinicaltrials.gov [NCT01042158] before patient recruitment.).

Procedural volume and survival after lung transplantation in the United States: the need to look beyond volume in the establishment of quality metrics.

BACKGROUND: We sought to evaluate the effect of center volume on patient survival. METHODS: We performed a retrospective analysis on nationwide data from the Scientific Registry of Transplant Recipients provided by United Network for Organ Sharing pertaining to lung transplantation (LT) recipients transplanted between 2005 and 2013. Centers were categorized into 4 groups based on their annual volume as follows: less than 20, 20 to 29, 30 to 39, and greater than or equal to 40 LTs. Baseline characteristics were compared and Kaplan-Meier analysis was used to estimate survival. RESULTS: A total of 13,506 adult recipients underwent LT during the study period. Of these, 2,491 (18.4%) patients were transplanted in centers with volume less than 20, 2,562 (19.0%) in centers with volume 20 to 29, 2,998 (22.2%) in centers with volume 30 to 39, and 5,455(40.4%) in centers with volume greater than or equal to 40. Survival was poorest in the lowest volume centers (1-year 81.4% vs 85.5% and 5-year 49.7% vs 56.5%, respectively). CONCLUSIONS: Post-LT survival in low volume centers is significantly lower than in high volume centers but the explanatory power of volume as a predictor of survival is low.