Ernestina Melicoff

Blockade of IL-6 Trans Signaling Attenuates Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a lethal lung disease with progressive fibrosis and death within 2–3 y of diagnosis. IPF incidence and prevalence rates are increasing annually with few effective treatments available. Inhibition of IL-6 results in the attenuation of pulmonary fibrosis in mice. It is unclear whether this is due to blockade of classical signaling, mediated by membrane-bound IL-6Rα, or trans signaling, mediated by soluble IL-6Rα (sIL-6Rα). Our study assessed the role of sIL-6Rα in IPF. We demonstrated elevations of sIL-6Rα in IPF patients and in mice during the onset and progression of fibrosis. We demonstrated that protease-mediated cleavage from lung macrophages was important in production of sIL-6Rα. In vivo neutralization of sIL-6Rα attenuated pulmonary fibrosis in mice as seen by reductions in myofibroblasts, fibronectin, and collagen in the lung. In vitro activation of IL-6 trans signaling enhanced fibroblast proliferation and extracellular matrix protein production, effects relevant in the progression of pulmonary fibrosis. Taken together, these findings demonstrate that the production of sIL-6Rα from macrophages in the diseased lung contributes to IL-6 trans signaling that in turn influences events crucial in pulmonary fibrosis.

The A2B adenosine receptor modulates pulmonary hypertension associated with interstitial lung disease

Development of pulmonary hypertension is a common and deadly complication of interstitial lung disease. Little is known regarding the cellular and molecular mechanisms that lead to pulmonary hypertension in patients with interstitial lung disease, and effective treatment options are lacking. The purpose of this study was to examine the adenosine 2B receptor (A2BR) as a regulator of vascular remodeling and pulmonary hypertension secondary to pulmonary fibrosis. To accomplish this, cellular and molecular changes in vascular remodeling were monitored in mice exposed to bleomycin in conjunction with genetic removal of the A2BR or treatment with the A2BR antagonist GS‐6201. Results demonstrated that GS‐6201 treatment or genetic removal of the A2BR attenuated vascular remodeling and hypertension in our model. Furthermore, direct A2BR activation on vascular cells promoted interleukin‐6 and endothelin‐1 release. These studies identify a novel mechanism of disease progression to pulmonary hypertension and support the development of A2BR antagonists for the treatment of pulmonary hypertension secondary to interstitial lung disease.—Karmouty‐Quintana, H., Zhong, H., Acero, L., Weng, T., Melicoff, E., West, J. D., Hemnes, A., Grenz, A., Eltzschig, H. K., Blackwell, T. S., Xia, Y., Johnston, R. A., Zeng, D., Belardinelli, L., Blackburn, M. R. The A2B adenosine receptor modulates pulmonary hypertension associated with interstitial lung disease. FASEB J. 26, 2546–2557 (2012). www.fasebj.org

Hypoxia-induced deoxycytidine kinase contributes to epithelial proliferation in pulmonary fibrosis.

RATIONALE Idiopathic pulmonary fibrosis (IPF) is a deadly lung disease with few therapeutic options. Apoptosis of alveolar epithelial cells, followed by abnormal tissue repair characterized by hyperplastic epithelial cell formation, is a pathogenic process that contributes to the progression of pulmonary fibrosis. However, the signaling pathways responsible for increased proliferation of epithelial cells remain poorly understood. OBJECTIVES To investigate the role of deoxycytidine kinase (DCK), an important enzyme for the salvage of deoxynucleotides, in the progression of pulmonary fibrosis. METHODS DCK expression was examined in the lungs of patients with IPF and mice exposed to bleomycin. The regulation of DCK expression by hypoxia was studied in vitro and the importance of DCK in experimental pulmonary fibrosis was examined using a DCK inhibitor and alveolar epithelial cell-specific knockout mice. MEASUREMENTS AND MAIN RESULTS DCK was elevated in hyperplastic alveolar epithelial cells of patients with IPF and in mice exposed to bleomycin. Increased DCK was localized to cells associated with hypoxia, and hypoxia directly induced DCK in alveolar epithelial cells in vitro. Hypoxia-induced DCK expression was abolished by silencing hypoxia-inducible factor 1α and treatment of bleomycin-exposed mice with a DCK inhibitor attenuated pulmonary fibrosis in association with decreased epithelial cell proliferation. Furthermore, DCK expression, and proliferation of epithelial cells and pulmonary fibrosis was attenuated in mice with conditional deletion of hypoxia-inducible factor 1α in the alveolar epithelium. CONCLUSIONS Our findings suggest that the induction of DCK after hypoxia plays a role in the progression of pulmonary fibrosis by contributing to alveolar epithelial cell proliferation.

Altered Hypoxic–Adenosine Axis and Metabolism in Group III Pulmonary Hypertension

Group III pulmonary hypertension (PH) is a highly prevalent and deadly lung disorder with limited treatment options other than transplantation. Group III PH affects patients with ongoing chronic lung injury, such as idiopathic pulmonary fibrosis (IPF). Between 30 and 40% of patients with IPF are diagnosed with PH. The diagnosis of PH has devastating consequences to these patients, leading to increased morbidity and mortality, yet the molecular mechanisms involved in the development of PH in patients with chronic lung disease remain elusive. Our hypothesis was that the hypoxic-adenosinergic system is enhanced in patients with group III PH compared with patients with IPF with no PH. Explanted lung tissue was analyzed for markers of the hypoxic-adenosine axis, including expression levels of hypoxia-inducible factor (HIF)-1A, adenosine A2B receptor, CD73, and equilibrative nucleotide transporter-1. In addition, we assessed whether altered mitochondrial metabolism was present in these samples. Increased expression of HIF-1A was observed in tissues from patients with group III PH. These changes were consistent with increased evidence of adenosine accumulation in group III PH. A novel observation of our study was of evidence suggesting altered mitochondrial metabolism in lung tissue from group III PH leading to increased succinate levels that are able to further stabilize HIF-1A. Our data demonstrate that the hypoxic-adenosine axis is up-regulated in group III PH and that subsequent succinate accumulation may play a part in the development of group III PH.

Bronchial artery revascularization and en bloc lung transplant in children

BACKGROUND Long-term success in pediatric lung transplantation is limited by infection and bronchiolitis obliterans syndrome (BOS). The bilateral sequential lung transplantation (BSLT) technique may result in airway ischemia leading to bronchial stenosis, dehiscence, or loss of small airways. En bloc lung transplant (EBLT) with bronchial artery revascularization (BAR) minimizes airway ischemia, thus promoting superior airway healing. BAR also allows for safe tracheal anastomosis, circumventing the need for bilateral bronchial anastomoses in small children. METHODS This was a retrospective review of bilateral transplantations from 2005 to 2014. Both techniques were used in parallel. Redo and multiorgan transplants were excluded. RESULTS There were 119 recipients comprising 88 BSLTs and 31 EBLTs. Follow-up time was 3 years (interquartile range, 1-5 years). Donor ischemic and cardiopulmonary bypass times were not different between techniques (p = 0.48 and p = 0.18, respectively). Degree of graft dysfunction and cellular rejection scores were not different (p = 0.83 and p = 0.93, respectively). There were 3 hospital deaths after BSLT and 2 after EBLT (p = 0.60). Overall survival was 61% for the BSLT group and 77% for the EBLT group (p = 0.54). Freedom from BOS was 71% in the BSLT group and 94% in the EBLT group (p = 0.08). On routine bronchoscopy, 57% BSLT and 16% EBLT patients had 1 or more airway ischemic findings (p < 0.0001). Multivariate analysis showed BSLT was associated with higher ischemic injury (relative risk, 2.86; 95 confidence interval, 1.3-6.5; p = 0.01) and non-airway complications (relative risk, 4.62; 95% confidence interval, 1.1-20.2; p = 0.04) but not airway reinterventions (p = 0.07). Airway dehiscence occurred in 3 BSLT patients. CONCLUSIONS Pediatric EBLT with BAR can be safely performed without increasing operative or graft ischemic times. Airway ischemia and non-airway complications were significantly reduced when BAR was combined with tracheal anastomosis, potentially diminishing morbidity caused by anastomotic healing complications.

Anellovirus loads are associated with outcomes in pediatric lung transplantation

Anelloviruses are DNA viruses ubiquitously present in human blood. Due to their elevated levels in immunosuppressed patients, anellovirus levels have been proposed as a marker of immune status. We hypothesized that low anellovirus levels, reflecting relative immunocompetence, would be associated with adverse outcomes in pediatric lung transplantation. We assayed blood samples from 57 patients in a multicenter study for alpha‐ and betatorquevirus, two anellovirus genera. The primary short‐term outcome of interest was acute rejection, and longer‐term outcomes were analyzed individually and as “composite” (death, chronic rejection, or retransplant within 2 years). Patients with low alphatorquevirus levels at 2 weeks post‐transplantation were more likely to develop acute rejection within 3 months after transplant (P = .013). Low betatorquevirus levels at 6 weeks and 6 months after transplant were associated with death (P = .047) and the composite outcome (P = .017), respectively. There was an association between low anellovirus levels and adverse outcomes in pediatric lung transplantation. Alphatorquevirus levels were associated with short‐term outcomes (ie, acute rejection), while betatorquevirus levels were associated with longer‐term outcomes (ie, death, or composite outcome within 2 years). These observations suggest that anelloviruses may serve as useful biomarkers of immune status and predictors of adverse outcomes.

Waitlist Outcomes in Pediatric Lung Transplantation: Poor Results for Children Listed in Adult Transplant Programs

BACKGROUND Low case volume has been associated with lower survival after pediatric lung transplantation. Our aim was to analyze waitlist outcomes among pediatric lung transplant centers in the USA. METHODS We studied a cohort of 1,139 pediatric candidates listed in the Organ Procurement and Transplantation Network for lung transplantation between 2002 and 2014. Of these candidates, 720 (63.2%) received a transplant. Candidates were divided into groups according to the clinical activity of the center of listing: high-volume pediatric (≥4 transplants per year); low-volume pediatric (<4 transplants per year); and adult (transplant volume predominantly in adults). We used multivariate Cox regression analysis to identify independent risk factors for waitlist mortality. We also determined the transplant rate-or likelihood of transplant after listing-over the study period. RESULTS Fifty-eight percent of the children and adolescents were listed in adult centers where the resultant transplant rate was low-only 42% received a transplant compared with 93% in pediatric programs. Listing in an adult program was also the most significant risk factor for death on the waiting list (hazard ratio 15.6, 95% confidence interval 5.8 to 42.1). CONCLUSIONS Most children (58%) are listed for lung transplantation in adult centers and have a reduced rate of transplantation and a greater chance of waitlist mortality.

Risk factors for infection after pediatric lung transplantation: XXXX

Although infection is the leading cause of death in the first year following pediatric lung transplantation, there are limited data on risk factors for early infection. Sepsis remains under‐recognized and under‐reported in the early post‐operative period for lung transplant recipients (LTR). We evaluated the incidence of infection and sepsis, and identified risk factors for infection in the early post‐operative period in pediatric LTRs. A retrospective review of medical records of LTRs at a large quaternary‐care hospital from January 2009 to March 2016 was conducted. Microbiology results on days 0‐7 after transplant were obtained. Sepsis was defined using the 2005 International Pediatric Consensus Conferencecriteria. Risk factors included history of recipient and donor infection, history of multi‐drug resistant (MDR) infection, nutritional status, and surgical times. Among the 98 LTRs, there were 22 (22%) with post‐operative infection. Prolonged donor ischemic time ≥7 hours, cardiopulmonary bypass(CPB) time ≥340 minutes, history of MDR infection and diagnosis of cystic fibrosis were significantly associated with infection. With multivariable regression analysis, only prolonged donor ischemic time remained significant (OR 4.4, 95% CI: 1.34‐14.48). Further research is needed to determine whether processes to reduce donor ischemic time could result in decreased post‐transplant morbidity.

Risk and outcomes of pulmonary fungal infection after pediatric lung transplantation

Prospective studies to determine associated risk factors and related outcomes for pulmonary fungal infection (PFI) after pediatric lung transplant (PLT) are lacking.