Update in lung transplantation 2013

Gastrointestinal complications in pediatric lung transplant recipients: Incidence, risk factors, and effects on patient outcomes

BACKGROUND

Gastrointestinal (GI) complications in lung transplant recipients can occur any time during the post-operative period, leading to prolonged morbidity and mortality. Despite the negative association between GI complications and patient outcomes, little is known about their incidence and risk factors for their development in pediatric lung transplant recipients.

METHODS

We performed a retrospective chart review at one pediatric tertiary center to describe the frequency of GI complications in lung transplant recipients. We identified potential risk factors for the diagnosis of gastroparesis, gastroesophageal reflux disease (GERD) and aspiration in the post-transplant period. Lastly, we investigated the association of these complications with mortality and graft survival.

RESULTS

84.3% of lung transplant recipients experienced at least one GI complication in the post-transplant period. Gastroparesis (52.9%), GERD (41.2%), and oropharyngeal dysphagia/laryngeal penetration (33.3%) were the most common complications diagnosed. Post-operative opioid exposure was a risk factor for gastroparesis, with the odds increasing 3.0% each day a patient was prescribed opioids (p = .021). The risk of death or retransplant in individuals who experienced gastroparesis was 2.7 times higher than those not diagnosed with gastroparesis (p = .027).

CONCLUSION

Exposure to opioids in the post-operative period is a risk factor for gastroparesis and a prolonged hospitalization placed patients at risk for aspiration. Gastroparesis was associated with increased patient mortality and graft failure, while aspiration and GERD had no effect on long term outcomes. Future prospective studies investigating the relationship between opioid use and the development of a gastroparesis are necessary to improve patient outcomes.

Insight on immune cells in rejection and infection postlung transplant

OBJECTIVE

The aim of this study is to provide a concise overview of the role of immune cells in rejection and infection after lung transplantation.

METHODS

Based on previous clinical and basic studies, the role of various types of immune cells in the development of rejection and infection after lung transplantation is summarized.

RESULTS

Immune cell functional status is strongly associated with common complications after lung transplantation, such as primary graft dysfunction, infection and occlusive bronchitis syndrome. Targeted balancing of immune cell tolerance and rejection is an important tool for successful lung transplantation.

CONCLUSION

A comprehensive understanding of immune cell function and the mechanisms that balance immune tolerance and immune rejection may be a crucial factor in improving survival after lung transplantation.

Molecular assessment of rejection and injury in lung transplant biopsies

BACKGROUND

Improved understanding of lung transplant disease states is essential because failure rates are high, often due to chronic lung allograft dysfunction. However, histologic assessment of lung transplant transbronchial biopsies (TBBs) is difficult and often uninterpretable even with 10 pieces.

METHODS

We prospectively studied whether microarray assessment of single TBB pieces could identify disease states and reduce the amount of tissue required for diagnosis. By following strategies successful for heart transplants, we used expression of rejection-associated transcripts (annotated in kidney transplant biopsies) in unsupervised machine learning to identify disease states.

RESULTS

All 242 single-piece TBBs produced reliable transcript measurements. Paired TBB pieces available from 12 patients showed significant similarity but also showed some sampling variance. Alveolar content, as estimated by surfactant transcript expression, was a source of sampling variance. To offset sampling variation, for analysis, we selected 152 single-piece TBBs with high surfactant transcripts. Unsupervised archetypal analysis identified 4 idealized phenotypes (archetypes) and scored biopsies for their similarity to each: normal; T-cell‒mediated rejection (TCMR; T-cell transcripts); antibody-mediated rejection (ABMR)-like (endothelial transcripts); and injury (macrophage transcripts). Molecular TCMR correlated with histologic TCMR. The relationship of molecular scores to histologic ABMR could not be assessed because of the paucity of ABMR in this population.

CONCLUSIONS

Molecular assessment of single-piece TBBs can be used to classify lung transplant biopsies and correlated with rejection histology. Two or 3 pieces for each TBB will probably be needed to offset sampling variance.

c-Jun N-terminal kinase (JNK)-mediated induction of mSin1 expression and mTORC2 activation in mesenchymal cells during fibrosis

Mammalian target of rapamycin complex 2 (mTORC2) has been shown to regulate mTORC1/4E-BP1/eIF4E signaling and collagen I expression in mesenchymal cells (MCs) during fibrotic activation. Here we investigated the regulation of the mTORC2 binding partner mammalian stress-activated protein kinase-interacting protein 1 (mSin1) in MCs derived from human lung allografts and identified a novel role for mSin1 during fibrosis. mSin1 was identified as a common downstream target of key fibrotic pathways, and its expression was increased in MCs in response to pro-fibrotic mediators: lysophosphatidic acid (LPA), transforming growth factor β, and interleukin 13. Fibrotic MCs had higher mSin1 protein levels than nonfibrotic MCs, and siRNA-mediated silencing of mSIN1 inhibited collagen I expression and mTORC1/2 activity in these cells. Autocrine LPA signaling contributed to constitutive up-regulation of mSin1 in fibrotic MCs, and mSin1 was decreased because of LPA receptor 1 siRNA treatment. We identified c-Jun N-terminal kinase (JNK) as a key intermediary in mSin1 up-regulation by the pro-fibrotic mediators, as pharmacological and siRNA-mediated inhibition of JNK prevented the LPA-induced mSin1 increase. Proteasomal inhibition rescued mSin1 levels after JNK inhibition in LPA-treated MCs, and the decrease in mSin1 ubiquitination in response to LPA was counteracted by JNK inhibitors. Constitutive JNK1 overexpression induced mSin1 expression and could drive mTORC2 and mTORC1 activation and collagen I expression in nonfibrotic MCs, effects that were reversed by siRNA-mediated mSIN1 silencing. These results indicate that LPA stabilizes mSin1 protein expression via JNK signaling by blocking its proteasomal degradation and identify the LPA/JNK/mSin1/mTORC/collagen I pathway as critical for fibrotic activation of MCs.

Role of biomarkers in early infectious complications after lung transplantation

Background

Infections and primary graft dysfunction are devastating complications in the immediate postoperative period following lung transplantation. Nowadays, reliable diagnostic tools are not available. Biomarkers could improve early infection diagnosis.

Methods

Multicentre prospective observational study that included all centres authorized to perform lung transplantation in Spain. Lung infection and/or primary graft dysfunction presentation during study period (first postoperative week) was determined. Biomarkers were measured on ICU admission and daily till ICU discharge or for the following 6 consecutive postoperative days.

Results

We included 233 patients. Median PCT levels were significantly lower in patients with no infection than in patients with Infection on all follow up days. PCT levels were similar for PGD grades 1 and 2 and increased significantly in grade 3. CRP levels were similar in all groups, and no significant differences were observed at any study time point. In the absence of PGD grade 3, PCT levels above median (0.50 ng/ml on admission or 1.17 ng/ml on day 1) were significantly associated with more than two- and three-fold increase in the risk of infection (adjusted Odds Ratio 2.37, 95% confidence interval 1.06 to 5.30 and 3.44, 95% confidence interval 1.52 to 7.78, respectively).

Conclusions

In the absence of severe primary graft dysfunction, procalcitonin can be useful in detecting infections during the first postoperative week. PGD grade 3 significantly increases PCT levels and interferes with the capacity of PCT as a marker of infection. PCT was superior to CRP in the diagnosis of infection during the study period.

Pleuroparenchymal fibroelastosis: the prevalence of secondary forms in hematopoietic stem cell and lung transplantation recipients

PURPOSE

Pleuroparenchymal fibroelastosis (PPFE) is a rare form of interstitial pneumonia, characterized by elastotic fibrosis involving the pleura and subpleural parenchyma, predominantly in the upper lobes. PPFE can be either idiopathic or secondary and mostly occurs as a late complication of lung or hematopoietic stem cell transplantation (HSCT). The aim of this study was to evaluate the prevalence of secondary forms in transplant recipients.

METHODS

An expert thoracic radiologist retrospectively reviewed high-resolution computed tomography exams of 700 HSCT recipients and 53 lung transplant recipients from the database of the Radiology Department of S. Orsola-Malpighi Hospital dating back from 2007. For each case that radiologically fulfilled PPFE criteria, the following details were retrieved: clinical characteristics, laboratory and functional data, pathologic findings (obtained from one patient) and metabolic data (obtained from three patients).

RESULTS

Six cases clinically and radiologically consistent with PPFE were identified: two HSCT recipients (0.28%) and four lung transplant recipients (7.54%).

CONCLUSION

In this study, PPFE was strongly associated with lung transplants as a late complication, with a prevalence of 7.54%.

Incidence and Risk Factors of Abdominal Complications After Lung Transplantation

BACKGROUND

Due to the underlying diseases and the need for immunosuppression, patients after lung transplantation are particularly at risk for gastrointestinal (GI) complications that may negatively influence long-term outcome. The present study assessed the incidences and impact of GI complications after lung transplantation and aimed to identify risk factors.

METHODS

Retrospective analysis of all 227 consecutively performed single- and double-lung transplantations at the University hospitals of Lausanne and Geneva was performed between January 1993 and December 2010. Logistic regressions were used to test the effect of potentially influencing variables on the binary outcomes overall, severe, and surgery-requiring complications, followed by a multiple logistic regression model.

RESULTS

Final analysis included 205 patients for the purpose of the present study, and 22 patients were excluded due to re-transplantation, multiorgan transplantation, or incomplete datasets. GI complications were observed in 127 patients (62%). Gastro-esophageal reflux disease was the most commonly observed complication (22.9%), followed by inflammatory or infectious colitis (20.5%) and gastroparesis (10.7%). Major GI complications (Dindo/Clavien III-V) were observed in 83 (40.5%) patients and were fatal in 4 patients (2.0%). Multivariate analysis identified double-lung transplantation (p = 0.012) and early (1993-1998) transplantation period (p = 0.008) as independent risk factors for developing major GI complications. Forty-three (21%) patients required surgery such as colectomy, cholecystectomy, and fundoplication in 6.8, 6.3, and 3.9% of the patients, respectively. Multivariate analysis identified Charlson comorbidity index of ≥3 as an independent risk factor for developing GI complications requiring surgery (p = 0.015).

CONCLUSION

GI complications after lung transplantation are common. Outcome was rather encouraging in the setting of our transplant center.

Endobronchial ultrasonography-guided transbronchial needle aspiration, an effective modality for sampling targeted thoracic lesions in adult lung transplant recipients

INTRODUCTION

Lung transplantation (LTx) is performed for end-stage lung diseases that would be otherwise fatal. Pulmonary allograft recipients are a unique patient population as they are at high risk for malignancy and infectious complications due to the need for immunosuppression. Endobronchial ultrasonography (EBUS)-guided fine-needle aspiration (FNA) is a minimally invasive technique for evaluating abnormalities of the mediastinum/lungs. To our knowledge, this report is the first in the literature addressing targeted EBUS-FNA biopsies in patients who have undergone LTx.

MATERIAL AND METHODS

During 5 years from May 1, 2009 to May 1, 2014, 582 patients underwent LTx at the Cleveland Clinic. A review of records indicated that 14 of these patients later underwent EBUS-FNA. Demographic and diagnostic parameters were recorded.

RESULTS

A total of 14 patients (mean age 64 years) underwent EBUS-FNA after LTx. The mean interval between LTx and EBUS-FNA was 15 months. EBUS-FNA yielded cytologic material diagnostic of malignancy in 10 patients (71%) with one-half of those cases being squamous carcinomas.

CONCLUSIONS

EBUS-FNA is a useful diagnostic modality in lung allograft recipients and is of value in confirming and staging thoracic malignancies in this population. Carcinoma subtyping is feasible by EBUS-FNA, and performance of ancillary studies to confirm clonality in post-transplant lymphoproliferative disorders is possible.

RC-3095, a selective gastrin-releasing peptide receptor antagonist, does not protect the lungs in an experimental model of lung ischemia-reperfusion injury

RC-3095, a selective GRPR antagonist, has been shown to have anti-inflammatory properties in different models of inflammation. However, its protective effect on lungs submitted to lung ischemia-reperfusion injury has not been addressed before. Then, we administrated RC-3095 intravenously before and after lung reperfusion using an animal model of lung ischemia-reperfusion injury (LIRI) by clamping the pulmonary hilum. Twenty Wistar rats were subjected to an experimental model in four groups: SHAM, ischemia-reperfusion (IR), RC-Pre, and RC-Post. The final mean arterial pressure significantly decreased in IR and RC-Pre compared to their values before reperfusion (P < 0.001). The RC-Post group showed significant decrease of partial pressure of arterial oxygen at the end of the observation when compared to baseline (P = 0.005). Caspase-9 activity was significantly higher in the RC-Post as compared to the other groups (P < 0.013). No significant differences were observed in eNOS activity among the groups. The groups RC-Pre and RC-Post did not show any significant decrease in IL-1β (P = 0.159) and TNF-α (P = 0.260), as compared to IR. The histological score showed no significant differences among the groups. In conclusion, RC-3095 does not demonstrate a protective effect in our LIRI model. Additionally, its use after reperfusion seems to potentiate cell damage, stimulating apoptosis.