Aspiration, localized pulmonary inflammation, and predictors of early-onset bronchiolitis obliterans syndrome after lung transplantation. J Am Coll Surg. 2013;217:90-100; discussion 100-101. [PMID: 23628225 DOI: 10.1016/j.jamcollsurg.2013.03.008]

Pulmonary and esophageal function in lung transplantation: Fundamental principles and clinical application

The lungs and esophagus have a close anatomical and physiological relationship. Over the years, reflux-induced pulmonary injury has gained wider recognition, but the full effects of pulmonary disease on esophageal function are still unknown. Intrathoracic pressure dynamics potentially affect esophageal function, especially in patients with end-stage lung disease, both obstructive and restrictive. Lung transplantation is the only viable option for patients with end-stage pulmonary disease and has provided us with a unique opportunity to study these effects as transplantation restores the intrathoracic environment. Esophageal and foregut functional testing before and after transplantation provide insights into the pathophysiology of the foregut-pulmonary axis, such as how underlying pulmonary disease and intrathoracic pressure changes affect esophageal physiology. This review summarizes the available literature and shares the research experience of a lung transplant center, covering topics such as pre- and posttransplant foregut function, esophageal motility in lung transplant recipients, immune-mediated mechanisms of graft rejection associated with gastroesophageal reflux, and the role of antireflux surgery in this population.

Tolerability and Feasibility of the Upper Esophageal Sphincter Assist Device in Preventing Acute and Chronic Allograft Rejection Among Lung Transplant Recipients

GOALS

We aimed to evaluate a novel upper esophageal sphincter (UES) assist device loaner program for the prevention of acute cellular rejection and chronic lung allograft dysfunction among lung transplant (LTx) recipients.

BACKGROUND

Laryngopharyngeal reflux can lead to chronic microaspiration and LTx rejection. The UES assist device applies external pressure at the level of UES to decrease reflux.

STUDY

We prospectively enrolled and issued UES assist devices to consecutive transplant patients referred for gastrointestinal motility testing from 2016 to 2020. Device tolerability was defined by successful utilization as a bridge to ambulatory pH monitoring and/or antireflux procedure, or as permanent therapy. Incidence of rejection was analyzed before, during, and after device implementation.

RESULTS

Twenty-six participants were issued devices (15 pathologic, 5 physiological, 6 unknown reflux status), none of whom developed acute rejection episodes or chronic lung allograft dysfunction while using the device. Thirteen adopted the device promptly after transplantation (mean 1.7 mo) and remained free of rejection episodes over a mean 24.7 months of follow-up. Among those with pathologic reflux, lag time to device adoption strongly correlated with the development of rejection ( r =0.8, P =0.0006). There was no such correlation among those with physiological reflux. Five developed acute rejection after device return.

CONCLUSIONS

The device was tolerated by a majority of LTx patients and appears feasible as a barrier measure in the prevention of rejection. Delayed treatment of laryngopharyngeal reflux may lead to early allograft failure; therefore, the UES assist device should be given important consideration in transplant protection.

Association Between Antibodies Against Lung Self-Antigens and Gastroesophageal Reflux in Lung Transplant Candidates

Gastroesophageal reflux (GER) and pretransplant antibodies against lung self-antigens (SAbs) collagen-V and/or k-alpha 1 tubulin are both independently associated with allograft dysfunction after lung transplantation (LTx). The role of GER in inducing lung injury and SAbs is unknown. We aimed to study the association between pre-LTx GER and SAbs. After IRB approval, we retrieved SAb assays conducted between 2015 and 2019 and collected 24 hour GER data for these patients. Patients were divided into 2 groups: no reflux (GER-) and pathologic reflux (GER+) to compare the prevalence of SAbs. Multivariate analysis was used to study the association between GER and SAbs in the whole cohort and in restrictive lung disease (RLD) and obstructive lung disease (OLD) subsets. Proximal esophageal reflux (PER) events ≥5 was considered abnormal. Patients (n = 134; 73 men) were divided into groups: GER- (54.5%, n = 73) and GER+ (45.5%, n = 61). The prevalence of GER was higher in the RLD than in the OLD subset (p < 0.001). The overall prevalence of SAbs was 53.7% (n = 72), higher in the GER+ than the GER- group (65.6% vs 43.8%, p = 0.012), but comparable between RLD and OLD subsets. Overall, SAbs were associated with GER (p = 0.012) and abnormal PER (p = 0.017). GER and abnormal PER increased the odds of SAbs in the RLD subset (OR [95% CI]: 2.825 [1.033-7.725], p = 0.040 and OR [95% CI]: 3.551 [1.271-9.925], p = 0.014, respectively) but not in the OLD subset. LTx candidates have a high prevalence of SAbs, which are significantly associated with GER and abnormal PER in patients with RLD.

Cytokines in Lung Transplantation

Lung transplantation has developed significantly in recent years, but post-transplant care and patients' survival still need to be improved. Moreover, organ shortage urges novel modalities to improve the quality of unsuitable lungs. Cytokines, the chemical mediators of the immune system, might be used for diagnostic and therapeutic purposes in lung transplantation. Cytokine monitoring pre- and post-transplant could be applied to the prevention and early diagnosis of injurious inflammatory events including primary graft dysfunction, acute cellular rejection, bronchiolitis obliterans syndrome, restrictive allograft syndrome, and infections. In addition, preoperative cytokine removal, specific inhibition of proinflammatory cytokines, and enhancement of anti-inflammatory cytokines gene expression could be considered therapeutic options to improve lung allograft survival. Therefore, it is essential to describe the cytokines alteration during inflammatory events to gain a better insight into their role in developing the abovementioned complications. Herein, cytokine fluctuations in lung tissue, bronchoalveolar fluid, peripheral blood, and exhaled breath condensate in different phases of lung transplantation have been reviewed; besides, cytokine gene polymorphisms with clinical significance have been summarized.

Pepsin and the Lung—Exploring the Relationship between Micro-Aspiration and Respiratory Manifestations of Gastroesophageal Reflux Disease

Gastroesophageal reflux disease (GERD) is one of the most commonly encountered disorders in clinical practice nowadays, with an increasing burden on healthcare systems worldwide. GERD-related respiratory symptoms such as unexplained chronic cough, bronchial asthma or chronic obstructive pulmonary disease (COPD) with frequent exacerbations often pose diagnostic and therapeutic challenges and may require a multidisciplinary approach. Moreover, a potential role of GERD as a risk factor has been proposed for chronic rejection in patients who underwent lung transplantation. Pepsin has gained considerable attention from the scientific community in the last few years as a possible surrogate biomarker for GERD. The aim of this narrative review was to provide an overview of the potential utility of pepsin detection as a marker of micro-aspiration in various biological fluids retrieved from patients with suspected GERD-induced respiratory manifestations and in lung transplant patients with allograft dysfunction. Data on the subject remains highly contradictory, and while certain studies support its applicability in investigating atypical GERD manifestations, at the moment, it would be realistic to accept a modest utility at best. A major lack of consensus persists regarding topics such as the optimal timeframe for fluid collection and cut-off values. Further research is warranted in order to address these issues.

Markers of rejection of a lung allograft: state of the art

Chronic lung allograft dysfunction (CLAD) affects approximately 50% of all lung transplant recipients by 5 post-operative years and is the leading cause of death in lung transplant recipients. Early CLAD diagnosis or ideally prediction of CLAD is essential to enable early intervention before significant lung injury occurs. New technologies have emerged to facilitate biomarker discovery, including epigenetic modification and single-cell RNA sequencing. This review examines new and existing technologies for biomarker discovery and the current state of research on biomarkers for identifying lung transplant rejection.

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.

Effector immune cells in Chronic Lung Allograft Dysfunction: a Systematic Review

Chronic lung allograft dysfunction (CLAD) remains the major barrier to long‐term survival after lung transplantation and improved insight into its underlying immunological mechanisms is critical to better understand the disease and to identify treatment targets. We systematically searched the electronic databases of PubMed and EMBASE for original research publications, published between January 2000 and April 2021, to comprehensively assess current evidence on effector immune cells in lung tissue and bronchoalveolar lavage fluid from lung transplant recipients with CLAD. Literature search revealed 1351 articles, 76 of which met the criteria for inclusion in our analysis. Our results illustrate significant complexity in both innate and adaptive immune cell responses in CLAD, along with presence of numerous immune cell products, including cytokines, chemokines and proteases associated with tissue remodelling. A clear link between neutrophils and eosinophils and CLAD incidence has been seen, in which eosinophils more specifically predisposed to restrictive allograft syndrome. The presence of cytotoxic and T‐helper cells in CLAD pathogenesis is well‐documented, although it is challenging to draw conclusions about their role in tissue processes from predominantly bronchoalveolar lavage data. In restrictive allograft syndrome, a more prominent humoral immune involvement with increased B cells, immunoglobulins and complement deposition is seen. Our evaluation of published studies over the last 20 years summarizes the complex multifactorial immunopathology of CLAD onset and progression. It highlights the phenotype of several key effector immune cells involved in CLAD pathogenesis, as well as the paucity of single cell resolution spatial studies in lung tissue from patients with CLAD.

Esophageal Function Tests are Not Associated with Barium Swallow Findings in Advanced Lung Disease

Gastroesophageal reflux disease and esophageal dysmotility are common in patients with advanced lung disease (ALD) and are associated with worse outcomes. Assessing esophageal function in these patients is relevant for determining pulmonary transplant eligibility and prognosticating post-transplant outcomes. Barium Swallow (BaS) is a non-invasive testing modality often performed as a complement to formal esophageal function tests (EFTs), but its role and clinical utility in this context is unknown. Therefore, we aimed to determine the relationship between BaS and EFTs with high-resolution manometry (HRM) and 24-h ambulatory pH-metry in patients with ALD. We performed a retrospective study of 226 consecutive patients undergoing evaluation for lung transplantation at a single center. All patients underwent EFTs and BaS independent of clinical history or symptoms per institutional protocol. Appropriate statistical tests were performed to evaluate the relationship between EFTs and BaS. Mucosal, reflux and motility findings were categorized. Abnormal motility was reported in 133 (59%) patients by BaS and 99 (44%) by HRM, with a significant difference in the proportions of patients with abnormal studies (p < 0.01). There were 7 (26%) patients with abnormal barium tablet passage who had normal HRM. The sensitivity (35%) and specificity (77%) for detecting pathologic reflux with BaS was poor. Inducibility of reflux and barium column height were not associated with pH-metry results. No clinically significant luminal irregularities were identified. In conclusion, while BaS can non-invasively assess esophageal mucosa, its findings are not associated with EFTs in patients with ALD.

Jackhammer Esophagus After Lung Transplantation: Results of a Retrospective Multicenter Study

GOALS

We sought to determine the incidence of jackhammer esophagus (JE) after lung transplantation (LT) and identify potential risk factors for the development of JE after LT.

BACKGROUND

JE is a rare esophageal motility disorder, and its pathophysiology remains unclear. Lung transplantation has been implicated as a potential risk factor for JE, but the incidence of JE after LT is unknown.

STUDY

A retrospective cohort of adult patients who underwent LT at 2 tertiary care centers over 7.5 years was reviewed. Analysis was performed on patients who underwent a high-resolution esophageal manometry (EM) study before and after LT. JE was defined according to the latest Chicago classification, version 3.0.

RESULTS

A total of 57 patients without JE identified on pre-LT EM also underwent an EM study after LT. Fifteen (25.4%) were found to have new JE after LT. Patients with newly diagnosed JE after LT were older (61.3±5.3 y vs. 51.6±15.6 y; P=0.02) and more often had chronic obstructive pulmonary disease (COPD; 47.6% vs. 16.6%; P=0.03) compared with those without COPD. There was a trend toward increased risk for JE among female individuals (60% vs. 33.3%; P=0.07) and those with shorter surgical anastomosis times (75.8±12.2 min vs. 84.4±14.3; P=0.06). There was no significant difference between body mass index, opioid use, pretransplant EM findings, surgical ischemic time, occurrence of gastroparesis, or measured post-LT outcomes between the 2 groups.

CONCLUSIONS

JE occurs not uncommonly in patients after LT. Older age and COPD pre-LT may be significant risk factors.

Esophageal contractility increases and gastroesophageal reflux does not worsen after lung transplantation

Gastroesophageal reflux and esophageal dysmotility are common in patients with advanced lung disease and are associated with allograft dysfunction after lung transplantation. The effect of transplantation on reflux and esophageal motility is unclear. The aim of this study was to describe the changes in esophageal function occurring after lung transplantation. A retrospective cohort study was performed on lung transplant candidates evaluated at a tertiary care center between 2015 and 2016. A total of 76 patients who underwent lung transplantation had high-resolution manometry and ambulatory pH-metry before and after transplant. Demographic data, esophageal function testing results, and clinical outcomes such as pulmonary function testing were collected and analyzed using appropriate statistical tests and multivariable regression. Of the 76 patients, 59 (78%) received a bilateral transplant. There was a significant increase in esophageal contractility posttransplant, with an increase in median distal contractile integral from 1470 to 2549 mmHg cm s (P < 0.01). There were 19 patients with Jackhammer esophagus posttransplant, including 15 patients with normal motility pretransplant. Nine patients with ineffective or fragmented peristalsis pretransplant had normal manometry posttransplant. Abnormal pH-metry was observed in 35 (46%) patients pretransplant and 29 (38%) patients posttransplant (P = 0.33). Patients with gastroesophageal reflux disease posttransplant had less improvement in pulmonary function at one year, as measured by forced expiratory volume (P = 0.04). These results demonstrate that esophageal contractility increases significantly after lung transplantation, with an associated change in motility classification. In comparison, gastroesophageal reflux does not worsen, but is associated with worse pulmonary function, posttransplant.

Terrestrosin D from Tribulus terrestris attenuates bleomycin-induced inflammation and suppresses fibrotic changes in the lungs of mice

Context: Terrestrosin D (TED), from Tribulus terrestris L. (Zygophyllaceae), exhibits anti-tumour and anti-inflammatory activities. However, its effects on bleomycin (BLM)-induced pulmonary inflammation and the subsequent fibrotic changes remain unclear. Objective: To examine the anti-inflammatory and anti-fibrotic effects of TED against BLM in murine pulmonary tissues. Materials and methods: Male SPF mice received saline (control), TED (10 mg/kg), BLM (2.5 mg/kg), or BLM (2.5 mg/kg) + TED (10 mg/kg) group. BLM was administered as a single intranasal inoculation, and TED was intraperitoneally administered once daily. After 2 and 6 weeks of treatment, cell number and differentiation (Giemsa staining) and TNF-α, IL-6, IL-8, TGF-β1, and PDGF-AB levels (ELISA) were determined in the bronchoalveolar lavage fluid (BALF). Hydroxyproline (Hyp) content in the left pulmonary tissue was also determined (ELISA). The right pulmonary tissue was H&E-stained and assessed for the severity of pulmonary fibrosis using the Ashcroft scoring method. Compared with the BLM group, TED decreased inflammatory cell infiltration; number of macrophages (p < 0.05), neutrophils (p < 0.05), lymphocytes (p < 0.05); percentage of macrophages in the monocyte-macrophage system (p < 0.05), and levels of TNF-α (p < 0.01), IL-6 (p < 0.01), IL-8 (p < 0.05), TGF-β1 (p < 0.05), and PDGF-AB (p < 0.05) in the BALF. TED also reduced Hyp content (p < 0.05) in the pulmonary tissue and attenuated the BLM-induced deterioration in lung histopathology. Discussion and conclusions: TED can inhibit BLM-induced inflammation and fibrosis in the lungs of mice, which may be related to reduced inflammatory and fibrotic markers. These results could be further tested in humans through clinical studies.

Esophageal pH-impedance monitoring in children: position paper on indications, methodology and interpretation by the SIGENP working group

Multichannel intraluminal impedance pH (MII-pH) monitoring currently represents the gold standard diagnostic technique for the detection of gastro-esophageal reflux (GER), since it allows to quantify and characterize all reflux events and their possible relation with symptoms. Over the last ten years, thanks to its strengths and along with the publication of several clinical studies, its worldwide use has gradually increased, particularly in infants and children. Nevertheless, factors such as the limited pediatric reference values and limited therapeutic options still weaken its current clinical impact. Through an up-to-date review of the available scientific evidence, our aim was to produce a position paper on behalf of the working group on neurogastroenterology and acid-related disorders of the Italian Society of Pediatric Gastroenterology, Hepatology and Nutrition (SIGENP) on MII-pH monitoring technique, indications and interpretation in pediatric age, in order to standardise its use and to help clinicians in the diagnostic approach to children with GER symptoms.

Early Identification of Chronic Lung Allograft Dysfunction: The Need of Biomarkers

A growing number of patients with end-stage lung disease have benefited from lung transplantation (LT). Improvements in organ procurement, surgical techniques and intensive care management have greatly increased short-term graft survival. However, long-term outcomes remain limited, mainly due to the onset of chronic lung allograft dysfunction (CLAD), whose diagnosis is based on permanent loss of lung function after the development of irreversible lung lesions. CLAD is associated with high mortality and morbidity, and its exact physiopathology is still only partially understood. Many researchers and clinicians have searched for CLAD biomarkers to improve diagnosis, to refine the phenotypes associated with differential prognosis and to identify early biological processes that lead to CLAD to enable an early intervention that could modify the inevitable degradation of respiratory function. Donor-specific antibodies are currently the only biomarkers used in routine clinical practice, and their significance for accurately predicting CLAD is still debated. We describe here significant studies that have highlighted potential candidates for reliable and non-invasive biomarkers of CLAD in the fields of imaging and functional monitoring, humoral immunity, cell-mediated immunity, allograft injury, airway remodeling and gene expression. Such biomarkers would improve CLAD prediction and allow differential LT management regarding CLAD risk.

A Pilot Study to Investigate the Balance between Proteases and α1-Antitrypsin in Bronchoalveolar Lavage Fluid of Lung Transplant Recipients

The neutrophilic component in bronchiolitis obliterans syndrome (BOS, the main form of chronic lung rejection), plays a crucial role in the pathogenesis and maintenance of the disorder. Human Neutrophil Elastase (HNE), a serine protease responsible of elastin degradation whose action is counteracted by α1-antitrypsin (AAT), a serum inhibitor specific for this protease. This work aimed to investigate the relationship between HNE and AAT in bronchoalveolar lavage fluid (BALf) from stable lung transplant recipients and BOS patients to understand whether the imbalance between proteases and inhibitors is relevant to the development of BOS. To reach this goal a multidisciplinary procedure was applied which included: (i) the use of electrophoresis/western blotting coupled with liquid chromatography-mass spectrometric analysis; (ii) the functional evaluation of the residual antiprotease activity, and (iii) a neutrophil count. The results of these experiments demonstrated, for the first time, the presence of the complex between HNE and AAT in a number of BALf samples. The lack of this complex in a few specimens analyzed was investigated in relation to a patient’s lung inflammation. The neutrophil count and the determination of HNE and AAT activities allowed us to speculate that the presence of the complex correlated with the level of lung inflammation.

Chronic opioid use and clinical outcomes in lung transplant recipients: A single-center cohort study

INTRODUCTION

Chronic opioid use is common after organ transplantation, and has been associated with poor outcomes in transplantation of abdominal organs. However, little is known about possible influences of chronic opioid use on outcomes of lung transplantation (LTx).

OBJECTIVES

We assessed whether long-term chronic opioid use influenced clinical outcomes among LTx recipients at our program.

METHODS

We retrospectively evaluated chronic opioid use among bilateral LTx recipients ages 12 and older followed at our institution 1-5 years post-transplant. Chronic opioid use was defined as ≥3 months of consecutive prescribed use. Outcomes included survival, hospitalization, emergency department and urgent care visits, forced expiratory volume in one second (FEV1), and allograft rejection.

RESULTS

Twenty-one patients ages 15-50 years met inclusion criteria. On multivariable analysis, initiation of chronic opioid use was followed by increased mortality hazard (hazard ratio=7.1; 95% confidence interval [CI]: 1.1, 45.0, P = 0.037) and decreased FEV1 (-16%; 95% CI: -24%, -7%; P < 0.001), although no differences were observed in risk of acute care visits, inpatient admission, or chronic rejection.

CONCLUSION

This analysis presents the first evidence that late-onset chronic opioid use may be associated with decreased lung function and increased mortality after LTx. Therefore, evaluation of chronic opioid use should be included in the routine monitoring of transplant recipients, to better define the impact of this risk factor on LTx outcomes.

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.

Age-related variation in the cellular composition of equine bronchoalveolar lavage fluid

BACKGROUND

Previous reports reveal variation in the cellular composition of equine bronchoalveolar lavage fluid (BALF).

OBJECTIVES

The purpose of this study was to compare the profiles of BALF from horses to assess age-related differences. Serial BALF samples were collected from the same individuals over a one-year period to identify changes in individual animals as they aged.

METHODS

Collection of BALF was performed on horses aged one week and one, 2, 6, and 12 months. Total nucleated cell count (TNCC), protein concentration, and cytology were assessed. Longitudinal analysis was performed and compared to healthy adults.

RESULTS

Foals at one week and 6 months of age had significantly higher TNCC than adults (medians: 320/μL, 285/μL, and 90/μL, respectively); no differences in total protein were found. Foals at one month had the highest proportion of macrophages (median: 87.3%), differing significantly from both yearlings and adults (medians: 45.5% and 48.7%, respectively). Foals aged one week and one month had significantly lower proportions of lymphocytes than yearlings and adults (medians: 3.2% and 4.7% vs 43.2% and 45.8%, respectively). Eosinophil percentage was lowest in foals aged one week, one month, and 2 months (median: 0.0%) and highest in foals aged 6 months (median: 2.2%). Mast cell percentages were highest in yearlings and adults (medians: 2.2% and 3.3%, respectively) and neutrophil percentage was highest in foals aged one week (13.7%).

CONCLUSIONS

Cytologic profiles of BALF from foals and adult horses differed considerably. Significant changes in TNCC and percentages of lymphocytes, macrophages, and eosinophils occurred with age.

Advanced Role of Neutrophils in Common Respiratory Diseases

Respiratory diseases, always being a threat towards the health of people all over the world, are most tightly associated with immune system. Neutrophils serve as an important component of immune defense barrier linking innate and adaptive immunity. They participate in the clearance of exogenous pathogens and endogenous cell debris and play an essential role in the pathogenesis of many respiratory diseases. However, the pathological mechanism of neutrophils remains complex and obscure. The traditional roles of neutrophils in severe asthma, chronic obstructive pulmonary diseases (COPD), pneumonia, lung cancer, pulmonary fibrosis, bronchitis, and bronchiolitis had already been reviewed. With the development of scientific research, the involvement of neutrophils in respiratory diseases is being brought to light with emerging data on neutrophil subsets, trafficking, and cell death mechanism (e.g., NETosis, apoptosis) in diseases. We reviewed all these recent studies here to provide you with the latest advances about the role of neutrophils in respiratory diseases.

Role of gastroesophageal reflux disease in lung transplantation

Lung transplantation is one of the highest risk solid organ transplant modalities. Recent studies have demonstrated a relationship between gastroesophageal reflux disease (GERD) and lung transplant outcomes, including acute and chronic rejection. The aim of this review is to discuss the pathophysiology, evaluation, and management of GERD in lung transplantation, as informed by the most recent publications in the field. The pathophysiology of reflux-induced lung injury includes the effects of aspiration and local immunomodulation in the development of pulmonary decline and histologic rejection, as reflective of allograft injury. Modalities of reflux and esophageal assessment, including ambulatory pH testing, impedance, and esophageal manometry, are discussed, as well as timing of these evaluations relative to transplantation. Finally, antireflux treatments are reviewed, including medical acid suppression and surgical fundoplication, as well as the safety, efficacy, and timing of such treatments relative to transplantation. Our review of the data supports an association between GERD and allograft injury, encouraging a strategy of early diagnosis and aggressive reflux management in lung transplant recipients to improve transplant outcomes. Further studies are needed to explore additional objective measures of reflux and aspiration, better compare medical and surgical antireflux treatment options, extend follow-up times to capture longer-term clinical outcomes, and investigate newer interventions including minimally invasive surgery and advanced endoscopic techniques.

Early extracellular matrix changes are associated with later development of bronchiolitis obliterans syndrome after lung transplantation

Background

Chronic lung allograft dysfunction in the form of bronchiolitis obliterans syndrome (BOS) is the main cause of death beyond 1-year post-lung transplantation. The disease-initiating triggers as well as the molecular changes leading to fibrotic alterations in the transplanted lung are largely unknown. The aim of this study was to identify potential early changes in the extracellular matrix (ECM) in different compartments of the transplanted lung prior to the development of BOS.

Methods

Transbronchial biopsies from a cohort of 58 lung transplantation patients at the Copenhagen University hospital between 2005 and 2006, with or without development of BOS in a 5-year follow-up, were obtained 3 and 12 months after transplantation. Biopsies were assessed for total collagen, collagen type IV and biglycan in the alveolar and small airway compartments using Masson's Trichrome staining and immunohistochemistry.

Results

A time-specific and compartment-specific pattern of ECM changes was detected. Alveolar total collagen (p=0.0190) and small airway biglycan (p=0.0199) increased between 3 and 12 months after transplantation in patients developing BOS, while collagen type IV (p=0.0124) increased in patients without BOS. Patients with early-onset BOS mirrored this increase. Patients developing grade 3 BOS showed distinct ECM changes already at 3 months. Patients with BOS with treated acute rejections displayed reduced alveolar total collagen (p=0.0501) and small airway biglycan (p=0.0485) at 3 months.

Conclusions

Patients with future BOS displayed distinct ECM changes compared with patients without BOS. Our data indicate an involvement of alveolar and small airway compartments in post-transplantation changes in the development of BOS.

The Intersection of GERD, Aspiration, and Lung Transplantation

Lung transplantation is a radical but life-saving treatment option for patients with end-stage lung diseases, such as idiopathic pulmonary fibrosis (IPF) and scleroderma. In light of the proposed association and controversy linking gastroesophageal reflux disease (GERD) to IPF and lung transplant outcome, the American Gastroenterological Association convened during the DDW in Washington in May 2015 a multidisciplinary group of experts in the field of GERD and lung transplantation to make considerations about the care of these patients based on available data and subsequent expert panel discussion at this symposium. The following topics were discussed: (1) pathophysiology of GERD-induced pulmonary symptoms, (2) GERD evaluation before and after lung transplantation, (3) outcome of lung transplantation for IPF and scleroderma, and (4) role of laparoscopic fundoplication before or after lung transplantation.

Both Pre-Transplant and Early Post-Transplant Antireflux Surgery Prevent Development of Early Allograft Injury After Lung Transplantation

BACKGROUND

Antireflux surgery (ARS) has been associated with improved lung transplant outcomes. Pre-transplant ARS has been shown in small studies to improve pulmonary function among transplant candidates with gastroesophageal reflux disease (GERD). Although early post-transplant ARS has been shown to be effective in reducing chronic rejection, the optimal timing of ARS in transplant recipients remains unclear. The aim of this study is to evaluate the time to early allograft injury among lung transplant recipients by timing of ARS.

METHODS

This was a retrospective cohort study of lung transplant recipients undergoing ARS before or after transplantation at a tertiary care center since 2007, with at least 1-year follow-up. Early allograft injury was defined clinically and histologically as acute rejection or lymphocytic bronchiolitis, occurring within the first year after transplantation. In accordance with prior studies, the cutoff between early and late post-transplant ARS was set at 6 months. Time-to-event analysis using the Cox proportional hazards model was applied to assess the relationship between timing of surgery and early allograft injury. Subjects not meeting this outcome were censored at 1 year in the time-to-event analysis. Fisher’s exact test for binary variables and Student’s t test for continuous variables were performed to assess for differences among the three groups: ARS pre-transplant, ARS early post-transplant, and ARS late post-transplant.

RESULTS

Forty-eight subjects (60% men, mean age 55) met the inclusion criteria for the study. Patient demographics, pre-transplant cardiopulmonary function, BMI, CMV status, and PPI exposure were similar between groups. Kaplan-Meier analysis demonstrated significantly increased early allograft injury in late post-transplant ARS patients compared with both pre-transplant (log-rank p = 0.007) and early post-transplant (log-rank p = 0.05) patients, as well as a significant trend across groups (log-rank p = 0.005). No significant difference between pre- and early post-transplant groups was noted. Three ARS failures were noted in the pre- and late post-transplant groups. Complications included one death due to aspiration pneumonia in a late post-transplant ARS recipient. No early post-transplant ARS patients experienced ARS failure or complications.

CONCLUSION

Late post-lung transplant ARS resulted in increased risk of early allograft injury compared to pre-transplant and early post-transplant ARS. Both pre- and early post-transplant ARS appear equally safe and effective in improving lung transplant outcomes. These findings support consideration of aggressive reflux testing and application of antireflux measures before or soon after transplantation to minimize the impact of reflux on allograft injury.

Molecular Profiling in Lung Biopsies of Human Pulmonary Allografts to Predict Chronic Lung Allograft Dysfunction

Chronic lung allograft dysfunction (CLAD) is the main reason for poor long-term outcome of lung transplantation, with bronchiolitis obliterans (BO) representing the predominant pathological feature. BO is defined as a progressive fibrous obliteration of the small airways, thought to be triggered by a combination of nonimmune bronchial injury and alloimmune and autoimmune mechanisms. Because biopsy samples are too insensitive to reliably detect BO and a decline in lung function test results, which is clinically used to define CLAD, does not detect early stages, there is need for alternative biomarkers for early diagnosis. Herein, we analyzed the cellular composition and differential expression of 45 tissue remodeling-associated genes in transbronchial lung biopsy specimens from two cohorts with 18 patients each: patients who did not develop CLAD within 3 years after transplantation (48 biopsy specimens) and patients rapidly developing CLAD within the first 3 postoperative years (57 biopsy specimens). Integrating the mRNA expression levels of the five most significantly dysregulated genes from the transforming growth factor-β axis (BMP4, IL6, MMP1, SMAD1, and THBS1) into a score, patient groups could be confidently separated and the outcome predicted (P < 0.001). We conclude that overexpression of fibrosis-associated genes may be valuable as a tissue-based molecular biomarker to more accurately diagnose or predict the development of CLAD.

Idiopathic pulmonary fibrosis is associated with increased impedance measures of reflux compared to non-fibrotic disease among pre-lung transplant patients

BACKGROUND

Gastroesophageal reflux (GER) has been associated with idiopathic pulmonary fibrosis (IPF), although the mechanism remains unclear. Gastroesophageal reflux/microaspiration may lead to lung fibrosis, while increased pulmonary workload may also worsen GER. Comparing the GER profile of IPF patients to chronic obstructive pulmonary disease (COPD) patients with similar lung function may help delineate the role of GER in IPF pathogenesis.

METHODS

This was a retrospective cohort study of IPF and COPD patients undergoing pre-lung transplant multichannel intraluminal impedance and pH study (MII-pH) off acid suppression at a tertiary center in 2008-2014. Patients with prior fundoplication were excluded. Baseline demographics, pulmonary function test, and MII-pH results were recorded. Univariate analyses were performed using Fisher's exact (binary variables) and Student's t (continuous variables) tests. Logistic regression was performed to adjust for potential confounders.

KEY RESULTS

A total of 90 subjects (54 IPF, 36 COPD) met inclusion criteria. Compared to COPD, IPF patients had increased total reflux episodes (65.9 vs 46.1, p = 0.02), proximal reflux episodes (30.3 vs 20.3, p = 0.04), and prevalence of abnormal total reflux episodes (38.9% vs 16.7%, p = 0.02). On multivariate analyses, abnormal total reflux episodes (OR: 4.9, p = 0.05) and bolus reflux exposure time (OR: 4, p = 0.04) remained significantly associated with IPF.

CONCLUSIONS & INFERENCES

Abnormal reflux was significantly more prevalent among IPF patients after controlling for lung disease severity. Gastroesophageal reflux/microaspiration likely plays a role in fibrosis in IPF. A significant portion of IPF patients had increased non-acid reflux. Therapies aiming to prevent reflux of gastric contents may be more beneficial than antisecretory medications alone in these patients.

Pre-lung transplant measures of reflux on impedance are superior to pH testing alone in predicting early allograft injury

AIM: To evaluate pre-lung transplant acid reflux on pH-testing vs corresponding bolus reflux on multichannel intraluminal impedance (MII) to predict early allograft injury.

METHODS: This was a retrospective cohort study of lung transplant recipients who underwent pre-transplant combined MII-pH-testing at a tertiary care center from January 2007 to November 2012. Patients with pre-transplant fundoplication were excluded. Time-to-event analysis was performed using a Cox proportional hazards model to assess associations between measures of reflux on MII-pH testing and early allograft injury. Area under the receiver operating characteristic (ROC) curve (c-statistic) of the Cox model was calculated to assess the predictive value of each reflux parameter for early allograft injury. Six pH-testing parameters and their corresponding MII measures were specified a priori. The pH parameters were upright, recumbent, and overall acid reflux exposure; elevated acid reflux exposure; total acid reflux episodes; and acid clearance time. The corresponding MII measures were upright, recumbent, and overall bolus reflux exposure; elevated bolus reflux exposure; total bolus reflux episodes; and bolus clearance time.

RESULTS: Thirty-two subjects (47% men, mean age: 55 years old) met the inclusion criteria of the study. Idiopathic pulmonary fibrosis (46.9%) represented the most common pulmonary diagnosis leading to transplantation. Baseline demographics, pre-transplant cardiopulmonary function, number of lungs transplanted (unilateral vs bilateral), and post-transplant proton pump inhibitor use were similar between reflux severity groups. The area under the ROC curve, or c-statistic, of each acid reflux parameter on pre-transplant pH-testing was lower than its bolus reflux counterpart on MII in the prediction of early allograft injury. In addition, the development of early allograft injury was significantly associated with three pre-transplant MII measures of bolus reflux: overall reflux exposure (HR = 1.18, 95%CI: 1.01-1.36, P = 0.03), recumbent reflux exposure (HR = 1.25, 95%CI: 1.04-1.50, P = 0.01) and bolus clearance (HR = 1.09, 95%CI: 1.01-1.17, P = 0.02), but not with any pH-testing parameter measuring acid reflux alone.

CONCLUSION: Pre-transplant MII measures of bolus reflux perform better than their pH-testing counterparts in predicting early allograft injury post-lung transplantation.

Aspiration-related pulmonary syndromes

Aspiration of foreign matter into the airways and lungs can cause a wide spectrum of pulmonary disorders with various presentations. The type of syndrome resulting from aspiration depends on the quantity and nature of the aspirated material, the chronicity, and the host responses. Aspiration is most likely to occur in subjects with a decreased level of consciousness, compromised airway defense mechanisms, dysphagia, gastroesophageal reflux, and recurrent vomiting. These aspiration-related syndromes can be categorized into airway disorders, including vocal cord dysfunction, large airway obstruction with a foreign body, bronchiectasis, bronchoconstriction, and diffuse aspiration bronchiolitis, or parenchymal disorders, including aspiration pneumonitis, aspiration pneumonia, and exogenous lipoid pneumonia. In idiopathic pulmonary fibrosis, aspiration has been implicated in disease progression and acute exacerbation. Aspiration may increase the risk of bronchiolitis obliterans syndrome in patients who have undergone a lung transplant. Accumulating evidence suggests that a causative role for aspiration is often unsuspected in patients presenting with aspiration-related pulmonary diseases; thus, many cases go undiagnosed. Herein, we discuss the broadening spectrum of these pulmonary syndromes with a focus on presenting features and diagnostic aspects.

Pre-transplant impedance measures of reflux are associated with early allograft injury after lung transplantation

BACKGROUND

Acid reflux has been associated with poorer outcomes after lung transplantation. Standard pre-transplant reflux assessment has not been universally adopted. Non-acid reflux may also induce a pulmonary inflammatory cascade, leading to acute and chronic rejection. Esophageal multichannel intraluminal impedance and pH testing (MII-pH) may be valuable in standard pre-transplant evaluation. We assessed the association between pre-transplant MII-pH measures and early allograft injury in lung transplant patients.

METHODS

This was a retrospective cohort study of lung transplant recipients who underwent pre-transplant MII-pH at a tertiary center from 2007 to 2012. Results from pre-transplant MII-pH, cardiopulmonary function testing, and results of biopsy specimen analysis of the transplanted lung were recorded. Time-to-event analyses were performed using Cox proportional hazards and Kaplan-Maier methods to assess the associations between MII-pH measures and development of acute rejection or lymphocytic bronchiolitis.

RESULTS

Thirty patients (46.7% men; age, 54.2 years) met the inclusion criteria. Pre-transplant cardiopulmonary function and pulmonary diagnoses were similar between outcome groups. Prolonged bolus clearance (hazard ratio [HR], 4.11; 95% confidence interval [CI], 1.34-12.57; p = 0.01), increased total distal reflux episodes (HR, 4.80; 95% CI, 1.33-17.25; p = 0.02), and increased total proximal reflux episodes (HR, 4.43; 95% CI, 1.14-17.31; p = 0.03) were significantly associated with decreased time to early allograft injury. Kaplan-Meier curves also demonstrated differences in time to rejection by prolonged bolus clearance (p = 0.01) and increased total distal reflux episodes (p = 0.01). Sub-group analysis including only patients with MII-pH performed off proton pump inhibitors (n = 24) showed similar results.

CONCLUSIONS

Prolonged bolus clearance, increased total distal reflux episodes, and increased total proximal reflux episodes on pre-transplant MII-pH were associated with decreased time to early allograft injury after lung transplantation. Routine pre-transplant MII-pH may provide clinically relevant data regarding transplant outcomes and peri-transplant care.

Parametric response mapping as an indicator of bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation

The management of bronchiolitis obliterans syndrome (BOS) after hematopoietic cell transplantation presents many challenges, both diagnostically and therapeutically. We developed a computed tomography (CT) voxel-wise methodology termed parametric response mapping (PRM) that quantifies normal parenchyma, functional small airway disease (PRM(fSAD)), emphysema, and parenchymal disease as relative lung volumes. We now investigate the use of PRM as an imaging biomarker in the diagnosis of BOS. PRM was applied to CT data from 4 patient cohorts: acute infection (n = 11), BOS at onset (n = 34), BOS plus infection (n = 9), and age-matched, nontransplant control subjects (n = 23). Pulmonary function tests and bronchoalveolar lavage were used for group classification. Mean values for PRM(fSAD) were significantly greater in patients with BOS (38% ± 2%) when compared with those with infection alone (17% ± 4%, P < .0001) and age-matched control subjects (8.4% ± 1%, P < .0001). Patients with BOS had similar PRM(fSAD) profiles, whether a concurrent infection was present or not. An optimal cut-point for PRM(fSAD) of 28% of the total lung volume was identified, with values >28% highly indicative of BOS occurrence. PRM may provide a major advance in our ability to identify the small airway obstruction that characterizes BOS, even in the presence of concurrent infection.

Usefulness of pH monitoring in predicting the survival status of patients with scleroderma awaiting lung transplantation

BACKGROUND

Patients with scleroderma and end-stage lung disease (ESLD) have a very high prevalence of gastroesophageal reflux disease (GERD). Because GERD has been associated with aspiration in those with ESLD, and because those with scleroderma are particularly prone to develop severe GERD, there is some concern that GERD may contribute to shorten survival in patients with scleroderma awaiting lung transplantation. Therefore, we hypothesized that esophageal pH monitoring could predict survival of those with scleroderma and ESLD awaiting lung transplantation and that the severity of reflux can impact survival.

METHODS

We conducted a retrospective analysis of all scleroderma patients referred for lung transplantation who underwent esophageal manometry and pH monitoring since August 2008. We identified 10 patients in whom we calculated and compared the area under the curve for each receiver operating characteristic curve of the following variables: DeMeester score, forced expiratory volume in 1 s (FEV1), %predicted FEV1, forced vital capacity (FVC), %predicted FVC, diffusion capacity for carbon monoxide (DLco), and %predicted DLco.

RESULTS

The DeMeester score nominally outperformed FEV1, FVC, and DLco. Receiver operating characteristic curve analysis was also used to define the optimal DeMeester score (65.2) in differentiating survival status, as determined by maximizing sensitivity and specificity. Based on this value, we calculated the 1-y survival from the time of the esophageal function testing, which was 100% in seven patients with a DeMeester score of <65.2, and 33% in three patients with a score >65.2 (P = 0.01). The latter patients had greater total time pH < 4, greater time pH < 4 in the supine position, greater total episodes of reflux, and higher prevalence of absent peristalsis. The single survivor with a DeMeester score >70 had also proximal reflux, underwent antireflux surgery, and is alive 1201 d after transplant.

CONCLUSIONS

Our study shows that esophageal pH monitoring can predict survival status in patients with scleroderma awaiting lung transplantation and that the severity of reflux can impact the 1-y survival rate. Therefore, esophageal pH monitoring should be considered early in patients with scleroderma and ESLD, as this test could appropriately identify those in whom laparoscopic antireflux surgery should be performed quicker to prevent GERD and its detrimental effects in patients awaiting lung transplantation.

The pulmonary side of reflux disease: from heartburn to lung fibrosis

INTRODUCTION

Gastroesophageal reflux disease (GERD) is the most prevalent gastrointestinal disorder in the USA. Heartburn is the symptom most commonly associated with this disease, and the highly commercialized medical treatment directed toward relief of this symptom represents a 10-billion-dollar-per-year industry.

DISCUSSION

Unfortunately, there is often little awareness that GERD can be potentially a lethal disease as it can cause esophageal cancer. Furthermore, there is even less awareness about the relationship between GERD and respiratory disorders with the potential for severe morbidity and even mortality.

Pepsin concentrations are elevated in the bronchoalveolar lavage fluid of patients with idiopathic pulmonary fibrosis after lung transplantation

BACKGROUND

Aspiration of gastroesophageal refluxate has been implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF) and the progression of bronchiolitis obliterans syndrome after lung transplantation. The goals of the present study were to identify lung transplant patients at the greatest risk of aspiration and to investigate the causative factors.

MATERIALS AND METHODS

From September 2009 to November 2011, 252 bronchoalveolar lavage fluid (BALF) samples were collected from 100 lung transplant patients. The BALF pepsin concentrations and the results of transbronchial biopsy, esophageal function testing, barium swallow, and gastric emptying scan were compared among those with the most common end-stage lung diseases requiring lung transplantation: IPF, chronic obstructive pulmonary disease, cystic fibrosis, and α1-antitrypsin deficiency.

RESULTS

Patients with IPF had higher BALF pepsin concentrations and a greater frequency of acute rejection than those with α1-antitrypsin deficiency, cystic fibrosis, or chronic obstructive pulmonary disease (P = 0.037). Moreover, the BALF pepsin concentrations correlated negatively with a lower esophageal sphincter pressure and distal esophageal amplitude; negatively with distal esophageal amplitude and positively with total esophageal acid time, longest reflux episode, and DeMeester score in those with chronic obstructive pulmonary disease; and negatively with the upright acid clearance time in those with IPF.

CONCLUSIONS

Our results suggest that patients with IPF after lung transplantation are at increased risk of aspiration and a greater frequency of acute rejection episodes, and that the risk factors for aspiration might be different among those with the most common end-stage lung diseases who have undergone lung transplantation. These results support the role of evaluating the BALF for markers of aspiration in assessing lung transplant patients as candidates for antireflux surgery.