Proton Pump Inhibitors Independently Protect Against Early Allograft Injury or Chronic Rejection After Lung Transplantation.

BACKGROUND: Acid reflux has been associated with poor outcomes following lung transplantation. Unlike surgical fundoplication, the role of noninvasive, pharmacologic acid suppression remains uncertain. AIMS: To assess the relationship between post-transplant acid suppression with proton pump inhibitors (PPI) or histamine-2 receptor antagonists (H2RA) and onset of early allograft injury or chronic rejection following lung transplantation. METHODS: This was a retrospective cohort study of lung transplant recipients at a tertiary center in 2007-2014. Patients with pre-transplant antireflux surgery were excluded. Time-to-event analysis using the Cox proportional hazards model was applied to assess acid suppression therapy and onset of acute or chronic rejection, defined histologically and clinically. Subgroup analyses were performed to assess PPI versus H2RA use. RESULTS: A total of 188 subjects (60% men, mean age 54, follow-up 554 person-years) met inclusion criteria. During follow-up, 115 subjects (61.5%) developed rejection, with all-cause mortality of 27.6%. On univariate analyses, acid suppression and BMI, but not other patient demographics, were associated with rejection. The Kaplan-Meier curve demonstrated decreased rejection with use of acid suppression therapy (log-rank p = 0.03). On multivariate analyses, acid suppression (HR 0.39, p = 0.04) and lower BMI (HR 0.67, p = 0.04) were independently predicted against rejection. Subgroup analyses demonstrated that persistent PPI use was more protective than H2RA or no antireflux medications. CONCLUSIONS: Post-lung transplant exposure to persistent PPI therapy results in the greatest protection against rejection in lung transplant recipients, independent of other clinical predictors including BMI, suggesting that PPI may have antireflux or anti-inflammatory effects in enhancing allograft protection.

Impact of pretransplant anti-HLA antibodies on outcomes in lung transplant candidates.

RATIONALE: The prevalence of anti-HLA antibodies in lung transplant candidates and their impact on waitlist and transplant outcomes is not known. OBJECTIVES: We examined the prevalence of pretransplant anti-HLA antibodies at varying thresholds and evaluated their impact on outcomes before and after lung transplantation. METHODS: We performed a single-center retrospective cohort study including all patients listed for lung transplantation between January 2008 and August 2012. Per protocol, transplant candidates were assessed by solid phase LABscreen mixed Class I and II and LABscreen Single Antigen assays. MEASUREMENTS AND MAIN RESULTS: Among 224 patients, 34% had anti-HLA antibodies at mean fluorescent intensity (MFI) greater than or equal to 3,000 (group III), and 24% had antibodies at MFI 1,000 to 3,000 (group II). Ninety percent of the patients with pretransplant anti-HLA antibodies had class I antibodies, whereas only seven patients developed class II alone. Patients in group III were less likely to receive transplants than patients without any anti-HLA antibodies (group I) (45.5 vs. 67.7%, P = 0.005). Wait time to transplant was longer in group III than group I, although this difference did not meet statistical significance, and waitlist mortality was similar. Among transplant recipients, antibody-mediated rejection (AMR) was more frequent in group III than in group II (20% vs. 0%, P = 0.01) or group I (6.3%, P = 0.05). CONCLUSIONS: The presence of anti-HLA antibodies at the high MFI threshold (>3,000) was associated with lower transplant rate and higher rates of AMR. Screening for anti-HLA antibodies using the 3,000 MFI threshold may be important in managing transplant candidates and recipients.

Selenoprotein N deficiency in mice is associated with abnormal lung development.

Mutations in the human SEPN1 gene, encoding selenoprotein N (SepN), cause SEPN1-related myopathy (SEPN1-RM) characterized by muscle weakness, spinal rigidity, and respiratory insufficiency. As with other members of the selenoprotein family, selenoprotein N incorporates selenium in the form of selenocysteine (Sec). Most selenoproteins that have been functionally characterized are involved in oxidation-reduction (redox) reactions, with the Sec residue located at their catalytic site. To model SEPN1-RM, we generated a Sepn1-knockout (Sepn1(-/-)) mouse line. Homozygous Sepn1(-/-) mice are fertile, and their weight and lifespan are comparable to wild-type (WT) animals. Under baseline conditions, the muscle histology of Sepn1(-/-) mice remains normal, but subtle core lesions could be detected in skeletal muscle after inducing oxidative stress. Ryanodine receptor (RyR) calcium release channels showed lower sensitivity to caffeine in SepN deficient myofibers, suggesting a possible role of SepN in RyR regulation. SepN deficiency also leads to abnormal lung development characterized by enlarged alveoli, which is associated with decreased tissue elastance and increased quasi-static compliance of Sepn1(-/-) lungs. This finding raises the possibility that the respiratory syndrome observed in patients with SEPN1 mutations may have a primary pulmonary component in addition to the weakness of respiratory muscles.

Limited Effect of Prevention Strategies on Incidence of Clinically Detectable Venous Thromboembolism After Lung Transplantation.

BACKGROUND: Thromboembolic complications are common post-lung transplant, leading to significant morbidity. We instituted multiple interventions because of an observed 36.8% incidence of venous thromboembolism (VTE) (Incidence rate (IR) 5.74/1000 pt days) in our recipients. METHODS: Our initiative commenced January 2015 with enoxaparin initiation within 6-8 hours of intensive care unit arrival and continuation for 4-6 weeks. We evaluated the IR of VTE in lung transplant recipients within 90 days of transplant. In 2017, the protocol was modified to extend the time to initiation of prophylaxis to within 72 hours of ICU arrival. In 2019, we further amended our intraoperative vascular access strategy. RESULTS: Eighteen of 26 lung transplant recipients (LTR) met inclusion criteria in the 2015 cohort. Six of 18 (33.3%) developed VTE, 50% of which were upper extremity (UE), line associated. Fifty two of 75 LTR were eligible for enoxaparin prophylaxis in the 2017 cohort. Fifteen of 52 subjects (28.8%) developed VTE, 77.8% of which were UE and line associated. Despite improved adherence in 2017, there was little change in VTE IR (3.90/1000 pt days compared with 3.85/1000 pt days). Twenty six of 43 LTR met protocol inclusion criteria in the 2019 cohort. Ten subjects (38.5%) developed VTE, 67% of which were UE and line associated (IR 5.18/1000 pt days). CONCLUSION: Our prospective study found that LTR remain at high risk for VTE despite aggressive prophylaxis with 4-6 weeks of enoxaparin and adjustment of vascular access approach. Alternative interventions should be investigated to minimize VTE development in this vulnerable population.

The Presence of Pretransplant HLA Antibodies Does Not Impact the Development of Chronic Lung Allograft Dysfunction or CLAD-Related Death.

BACKGROUND: Development of donor-specific antibodies (DSA) after lung transplantation is associated with antibody mediated rejection, acute cellular rejection, and bronchiolitis obliterans syndrome; however, the significance of circulating antibodies before transplant remains unclear. METHODS: We performed a retrospective cohort study including recipients of primary lung transplants between 2008 and 2012. We assessed the impact of circulating HLA and noncytotoxic DSA detected before transplant on development of Chronic Lung Allograft Dysfunction (CLAD) or CLAD-related death. RESULTS: 30% of subjects had circulating class I antibodies alone, 4% Class II, and 14.4% class I and class II at mean fluorescent intensity greater than 1000. Nine percent of the subjects had DSA class I, 9% class II, and 2.4% both DSA classes 1 and 2. Neither the presence of circulating antibodies (adjusted hazard ratio, 0.87; 95% confidence interval, 0.50-1.54) nor the presence of DSA (adjusted hazard ratio, 1.56; 95% confidence interval, 0.77-3.18) before transplant at mean fluorescent intensity greater than 1000 was associated with the development of CLAD or CLAD-related death. CONCLUSIONS: Although in previous studies we have shown an increased incidence of antibody-mediated rejection in patients with pretransplant DSA, neither the presence of HLA antibodies nor DSA translated to an increased risk of allograft dysfunction or death if prospective crossmatch testing was negative. Prospective studies are needed to define the impact of pretransplant sensitization on lung transplant recipients.

Automated measurement of pulmonary emphysema and small airway remodeling in cigarette smoke-exposed mice.

COPD is projected to be the third most common cause of mortality world-wide by 2020((1)). Animal models of COPD are used to identify molecules that contribute to the disease process and to test the efficacy of novel therapies for COPD. Researchers use a number of models of COPD employing different species including rodents, guinea-pigs, rabbits, and dogs((2)). However, the most widely-used model is that in which mice are exposed to cigarette smoke. Mice are an especially useful species in which to model COPD because their genome can readily be manipulated to generate animals that are either deficient in, or over-express individual proteins. Studies of gene-targeted mice that have been exposed to cigarette smoke have provided valuable information about the contributions of individual molecules to different lung pathologies in COPD((3-5)). Most studies have focused on pathways involved in emphysema development which contributes to the airflow obstruction that is characteristic of COPD. However, small airway fibrosis also contributes significantly to airflow obstruction in human COPD patients((6)), but much less is known about the pathogenesis of this lesion in smoke-exposed animals. To address this knowledge gap, this protocol quantifies both emphysema development and small airway fibrosis in smoke-exposed mice. This protocol exposes mice to CS using a whole-body exposure technique, then measures respiratory mechanics in the mice, inflates the lungs of mice to a standard pressure, and fixes the lungs in formalin. The researcher then stains the lung sections with either Gill's stain to measure the mean alveolar chord length (as a readout of emphysema severity) or Masson's trichrome stain to measure deposition of extracellular matrix (ECM) proteins around small airways (as a readout of small airway fibrosis). Studies of the effects of molecular pathways on both of these lung pathologies will lead to a better understanding of the pathogenesis of COPD.

Prevalence and outcome of lung cancer in lung transplant recipients.

BACKGROUND: Lung transplant is the only available therapy for patients with advanced lung disease. The goal of this study was to examine the prevalence, origin, management and outcome of lung cancer in recipients of lung transplant at our institution. METHODS: After institutional review board approval, we conducted a retrospective chart review of all lung transplantations in our institution from January 1990 until June 2012. RESULTS: The prevalence of lung cancer in the explanted lung was 6 (1.2%) of 462 and all cases were in subjects with lung fibrosis. All 4 subjects with lymph node involvement died of causes related to the malignancy. Nine (1.9%) of 462 patients were found to have bronchogenic carcinoma after lung transplant. The most common location was in the native lung in recipients of a single lung transplant (6 out of 9 patients). In one case, the tumor originated in the allograft and was potentially donor related. The median time to diagnosis after lung transplant was 28 months with a range from 9 months to 10 years. Median survival was 8 months, with tumors involving lymph nodes or distant metastases associated with a markedly worse prognosis (median survival 7 months) than stage I disease (median survival 27 months). CONCLUSIONS: The prevalence of lung cancer in lung transplant recipients is low. Using accepted donor screening criteria, donor derived malignancy is exceptionally rare. While stage I disease is associated with improved survival in this cohort, survival is still not comparable to that of the general population, likely influenced by the need for aggressive immune suppression.

Serologic response to hepatitis B vaccination among lung transplantation candidates.

BACKGROUND: Optimal hepatitis B (HBV) vaccination strategies for lung transplantation (LT) candidates are not well established. METHODS: LT candidates with negative anti-HBs and anti-HBc antibody titers at baseline who received standard-dose HBV vaccination (Recombivax-HB 10 mcg/mL or Engerix-B 20 mcg/mL) administered at months 0, 1, and 6 or an accelerated vaccination schedule on days 0, 7 to 14, and 21 to 28 between June 1988 and October 2012 were studied. Patients who were more likely to undergo LT within 6 months of evaluation received the accelerated vaccination schedule starting in August 2009. RESULTS: Ninety-six HBV-seronegative patients who completed the vaccination series and had postvaccination anti-HBs titers available were identified. Median age was 60 years; 55.2% were female, and 92.7% were white. Underlying lung diseases included COPD (44.8%), idiopathic pulmonary fibrosis (22.9%), interstitial lung disease (15.6%), and cystic fibrosis (8.3%). The overall anti-HBs response rate was 54.2%. There was no significant difference in vaccine responses between accelerated and standard vaccination schedules (54.2% vs. 54.1%; P=1.0). Patients who received steroids or other immunosuppressants before transplantation had lower response rates compared with those who did not (38.9% vs. 63.3%; P=0.03). CONCLUSIONS: Better vaccination strategies to improve response rate are needed in this population. The accelerated HBV vaccination schedule elicited similar anti-HBs responses as the standard schedule and could be advantageous in this population, given current organ allocation practices, and it could allow repeat vaccination series for initial nonresponders before transplantation.

A targeted peritransplant antifungal strategy for the prevention of invasive fungal disease after lung transplantation: a sequential cohort analysis.

BACKGROUND: Lung transplant recipients are at high risk of invasive fungal disease (IFD), particularly invasive aspergillosis and candidiasis. The antifungal strategy that optimally balances effective reduction of IFD with a minimum of toxicity remains undefined; universal triazole prophylaxis is common at lung transplantation (LT) centers, despite the well-known toxicities and costs of this approach. METHODS: We implemented an antifungal strategy in March 2007 targeted at LT recipients at highest risk for IFD based on our institutional epidemiology. All patients received inhaled amphotericin B during their initial LT hospitalization, bilateral lung transplant recipients received 7 to 10 days of micafungin, and only patients with growth of yeast or mold in their day-of-transplant cultures received further oral antifungal therapy tailored to their fungal isolate. RESULTS: IFD events were assessed in sequential cohorts composed of 82 lung transplant recipients before and 83 patients after the implementation of this targeted antifungal strategy. We observed a sharp decline in IFD; in the second cohort, 87%, 91%, and 96% of patients were free of IFD, invasive candidiasis, and invasive aspergillosis at 1 year. Only 19% of patients in the second cohort received systemic antifungal therapy beyond the initial LT hospitalization, and no patients experienced antifungal drug-related toxicity or IFD-associated mortality. CONCLUSIONS: The targeted antifungal strategy studied seems to be a reasonable approach to reducing post-LT IFD events while limiting treatment-related toxicities and costs.