David Zaas

Cyclic AMP–regulated exocytosis of Escherichia coli from infected bladder epithelial cells

The superficial bladder epithelium is a powerful barrier to urine and also serves as a regulator of bladder volume, which is achieved by apical exocytosis of specialized fusiform vesicles during distension of the bladder. We report that type 1 fimbriated uropathogenic Escherichia coli (UPEC) circumvents the bladder barrier by harboring in these Rab27b/CD63-positive and cAMP-regulatable fusiform vesicles within bladder epithelial cells (BECs). Incorporation of UPEC into BEC fusiform compartments enabled bacteria to escape elimination during voiding and to re-emerge in the urine as the bladder distended. Notably, treatment of UPEC-infected mice with a drug that increases intracellular cAMP and induces exocytosis of fusiform vesicles reduced the number of intracellular E. coli.

Active rehabilitation and physical therapy during extracorporeal membrane oxygenation while awaiting lung transplantation: a practical approach.

Objective:Extracorporeal membrane oxygenation as a bridge to lung transplantation has traditionally been associated with substantial morbidity and mortality. A major contributor to these complications may be weakness and overall deconditioning secondary to pretransplant critical illness and immobility. In an attempt to address this issue, we developed a collaborative program to allow for active rehabilitation and physical therapy for patients requiring life support with extracorporeal membrane oxygenation before lung transplantation. Design:An interdisciplinary team responded to an acute need to develop a mechanism for active rehabilitation and physical therapy for patients awaiting lung transplantation while being managed with extracorporeal membrane oxygenation. We describe a series of three patients who benefited from this new approach. Setting:A quaternary care pediatric intensive care unit in a childrens hospital set within an 800-bed university academic hospital with an active lung transplantation program for adolescent and adult patients. Patients, Interventions, and Main Results:Three patients (ages 16, 20, and 24 yrs) with end-stage respiratory failure were rehabilitated while on extracorporeal membrane oxygenation awaiting lung transplantation. These patients were involved in active rehabilitation and physical therapy and, ultimately, were ambulatory on extracorporeal membrane oxygenation before successful transplantation. Following lung transplantation, the patients were liberated from mechanical ventilation, weaned to room air, transitioned out of the intensive care unit, and ambulatory less than 1 wk posttransplant. Conclusions:A comprehensive, multidisciplinary system can be developed to safely allow for active rehabilitation, physical therapy, and ambulation of patients being managed with extracorporeal membrane oxygenation. Such programs may lead to a decreased threshold for the utilization of extracorporeal membrane oxygenation before transplant and have the potential to improve conditioning, decrease resource utilization, and lead to better outcomes in patients who require extracorporeal membrane oxygenation before lung transplantation.

Active Rehabilitation During Extracorporeal Membrane Oxygenation as a Bridge to Lung Transplantation

BACKGROUND: Patients with end-stage lung disease often progress to critical illness, which dramatically reduces their chance of survival following lung transplantation. Pre-transplant deconditioning has a significant impact on outcomes for all lung transplant patients, and is likely a major contributor to increased mortality in critically ill lung transplant recipients. The aim of this report is to describe a series of patients bridged to lung transplant with extracorporeal membrane oxygenation (ECMO) and to examine the potential impact of active rehabilitation and ambulation during pre-transplant ECMO. METHODS: This retrospective case series reviews all patients bridged to lung transplantation with ECMO at a single tertiary care lung transplant center. Pre-transplant ECMO patients receiving active rehabilitation and ambulation were compared to those patients who were bridged with ECMO but did not receive pre-transplant rehabilitation. RESULTS: Nine consecutive subjects between April 2007 and May 2012 were identified for inclusion. One-year survival for all subjects was 100%, with one subject alive at 4 months post-transplant. The 5 subjects participating in pre-transplant rehabilitation had shorter mean post-transplant mechanical ventilation (4 d vs 34 d, P = .01), ICU stay (11 d vs 45 d, P = .01), and hospital stay (26 d vs 80 d, P = .01). No subject who participated in active rehabilitation had post-transplant myopathy, compared to 3 of 4 subjects who did not participate in pre-transplant rehabilitation on ECMO. CONCLUSIONS: Bridging selected critically ill patients to transplant with ECMO is a viable treatment option, and active participation in physical therapy, including ambulation, may provide a more rapid post-transplantation recovery. This innovative strategy requires further study to fully evaluate potential benefits and risks.

Survival after Bronchiolitis Obliterans Syndrome among Bilateral Lung Transplant Recipients

RATIONALE Despite the importance of bronchiolitis obliterans syndrome (BOS) in lung transplantation, little is known regarding the factors that influence survival after the onset of this condition, particularly among bilateral transplant recipients. OBJECTIVES To identify factors that influence survival after the onset of BOS among bilateral lung transplant recipients. METHODS The effect of demographic or clinical factors, occurring before BOS, upon survival after the onset of BOS was studied in 95 bilateral lung transplant recipient using Cox proportional hazards models. MEASUREMENTS AND MAIN RESULTS Although many factors, including prior acute rejection or rejection treatments, were not associated with survival after BOS, BOS onset within 2 years of transplantation (early-onset BOS), or BOS onset grade of 2 or 3 (high-grade onset) were predictive of significantly worse survival (early onset P = 0.04; hazard ratio, 1.84; 95% confidence interval, 1.03-3.29; high-grade onset P = 0.003; hazard ratio, 2.40; 95% confidence interval, 1.34-4.32). The effects of both early onset and high-grade onset on survival persisted in multivariable analysis and after adjustment for concurrent treatments. Results suggested an interaction might exist between early onset and high-grade onset. In particular, high-grade onset of BOS, regardless of its timing after transplant, is associated with a very poor prognosis. CONCLUSIONS The course of BOS after bilateral lung transplantation is variable. Distinct patterns of survival after BOS are evident and related to timing or severity of onset. Further characterization of these subgroups should provide a more rational basis from which to design, stratify, and assess response in future BOS treatment trials.

Implications for Human Leukocyte Antigen Antibodies After Lung Transplantation: A 10-Year Experience in 441 Patients

BACKGROUND Long-term survival after lung transplant is limited by the development of chronic and progressive airflow obstruction, a condition known as bronchiolitis obliterans syndrome (BOS). While prior studies strongly implicate cellular rejection as a strong risk factor for BOS, less is known about the clinical significance of human leukocyte antigen (HLA) antibodies and donor HLA-specific antibodies in long-term outcomes. METHODS A single-center cohort of 441 lung transplant recipients, spanning a 10-year period, was prospectively screened for HLA antibodies after transplant using flow cytometry-based methods. The prevalence of and predictors for HLA antibodies were determined. The impact of HLA antibodies on survival after transplant and the development of BOS were determined using Cox models. RESULTS Of the 441 recipients, 139 (32%) had detectable antibodies to HLA. Of these 139, 54 (39%) developed antibodies specific to donor HLA. The detection of posttransplant HLA antibodies was associated with BOS (HR, 1.54; P=.04) and death (HR, 1.53; P=.02) in multivariable models. The detection of donor-specific HLA antibodies was associated with death (HR, 2.42; P<.0001). The detection of posttransplant HLA antibodies was associated with pretransplant HLA-antibody detection, platelet transfusions, and the development of BOS and cytomegalovirus pneumonitis. CONCLUSIONS Approximately one-third of lung transplant recipients have detectable HLA antibodies, which are associated with a worse prognosis regarding graft function and patient survival.

Original ResearchTransplantationImplications for Human Leukocyte Antigen Antibodies After Lung Transplantation: A 10-Year Experience in 441 Patients

BACKGROUND Long-term survival after lung transplant is limited by the development of chronic and progressive airflow obstruction, a condition known as bronchiolitis obliterans syndrome (BOS). While prior studies strongly implicate cellular rejection as a strong risk factor for BOS, less is known about the clinical significance of human leukocyte antigen (HLA) antibodies and donor HLA-specific antibodies in long-term outcomes. METHODS A single-center cohort of 441 lung transplant recipients, spanning a 10-year period, was prospectively screened for HLA antibodies after transplant using flow cytometry-based methods. The prevalence of and predictors for HLA antibodies were determined. The impact of HLA antibodies on survival after transplant and the development of BOS were determined using Cox models. RESULTS Of the 441 recipients, 139 (32%) had detectable antibodies to HLA. Of these 139, 54 (39%) developed antibodies specific to donor HLA. The detection of posttransplant HLA antibodies was associated with BOS (HR, 1.54; P=.04) and death (HR, 1.53; P=.02) in multivariable models. The detection of donor-specific HLA antibodies was associated with death (HR, 2.42; P<.0001). The detection of posttransplant HLA antibodies was associated with pretransplant HLA-antibody detection, platelet transfusions, and the development of BOS and cytomegalovirus pneumonitis. CONCLUSIONS Approximately one-third of lung transplant recipients have detectable HLA antibodies, which are associated with a worse prognosis regarding graft function and patient survival.

Solid-organ transplantation in older adults: Current status and future research

An increasing number of patients older than 65 years are referred for and have access to organ transplantation, and an increasing number of older adults are donating organs. Although short‐term outcomes are similar in older versus younger transplant recipients, older donor or recipient age is associated with inferior long‐term outcomes. However, age is often a proxy for other factors that might predict poor outcomes more strongly and better identify patients at risk for adverse events. Approaches to transplantation in older adults vary across programs, but despite recent gains in access and the increased use of marginal organs, older patients remain less likely than other groups to receive a transplant, and those who do are highly selected. Moreover, few studies have addressed geriatric issues in transplant patient selection or management, or the implications on health span and disability when patients age to late life with a transplanted organ. This paper summarizes a recent trans‐disciplinary workshop held by ASP, in collaboration with NHLBI, NIA, NIAID, NIDDK and AGS, to address issues related to kidney, liver, lung, or heart transplantation in older adults and to propose a research agenda in these areas.

An Official American Thoracic Society/International Society for Heart and Lung Transplantation/Society of Critical Care Medicine/Association of Organ and Procurement Organizations/United Network of Organ Sharing Statement: Ethical and Policy Considerations in Organ Donation after Circulatory Determination of Death

RATIONALE Donation after circulatory determination of death (DCDD) has the potential to increase the number of organs available for transplantation. Because consent and management of potential donors must occur before death, DCDD raises unique ethical and policy issues. OBJECTIVES To develop an ethics and health policy statement on adult and pediatric DCDD relevant to critical care and transplantation stakeholders. METHODS A multidisciplinary panel of stakeholders was convened to develop an ethics and health policy statement. The panel consisted of representatives from the American Thoracic Society, Society of Critical Care Medicine, International Society for Heart and Lung Transplantation, Association of Organ Procurement Organizations, and the United Network of Organ Sharing. The panel reviewed the literature, discussed important ethics and health policy considerations, and developed a guiding framework for decision making by stakeholders. RESULTS A framework to guide ethics and health policy statement was established, which addressed the consent process, pre- and post mortem interventions, the determination of death, provisions of end-of-life care, and pediatric DCDD. CONCLUSIONS The information presented in this Statement is based on the current evidence, experience, and clinical rationale. New clinical research and the development and dissemination of new technologies will eventually necessitate an update of this Statement.

Alemtuzumab in the Treatment of Refractory Acute Rejection and Bronchiolitis Obliterans Syndrome After Human Lung Transplantation

Despite substantial improvements in early survival after lung transplantation, refractory acute rejection (RAR) and bronchiolitis obliterans syndrome (BOS) remain major contributors to transplant‐related morbidity and mortality. We have utilized alemtuzumab, a humanized anti‐CD52 antibody which results in potent lymphocyte depletion, in consecutive patients with RAR (n = 12) or BOS (n = 10). All patients failed conventional treatment with methylprednisolone and antithymocyte globulin and received strict infection prophylaxis. Alemtuzumab significantly improved histological rejection scores in RAR. Total rejection grade/biopsy was 1.98 ± 0.25 preceding alemtuzumab versus 0.33 ± 0.14 posttreatment, p‐value <0.0001 (with a similar number of biopsies/patient per respective time interval). Freedom from BOS was observed in 65% of RAR patients 2 years after alemtuzumab treatment. Although there was no statistically significant change in forced expiratory volume in 1 second (FEV1) before and after alemtuzumab treatment in patients with BOS, a stabilization or improvement in BOS grade occurred in 70% of patients. Patient survival 2 years after alemtuzumab for BOS was 69%. Despite a dramatic decline in CD4 counts in alemtuzumab‐treated patients, only one patient developed a lethal infection. Thus, we provide the first evidence that alemtuzumab is a potentially useful therapy in lung transplant recipients with RAR or BOS.

Counteracting signaling activities in lipid rafts associated with the invasion of lung epithelial cells by Pseudomonas aeruginosa

Pseudomonas aeruginosa has the capacity to invade lung epithelial cells by co-opting the intrinsic endocytic properties of lipid rafts, which are rich in cholesterol, sphingolipids, and proteins, such as caveolin-1 and -2. We compared intratracheal Pseudomonas infection in wild type and caveolin-deficient mice to investigate the role of caveolin proteins in the pathogenesis of Pseudomonas pneumonia. Unlike wild type mice, which succumb to pneumonia, caveolin-deficient mice are resistant to Pseudomonas. We observed that Pseudomonas invasion of lung epithelial cells is dependent on caveolin-2 but not caveolin-1. Phosphorylation of caveolin-2 by Src family kinases is an essential event for Pseudomonas invasion. Our studies also reveal the existence of a distinct signaling mechanism in lung epithelial cells mediated by COOH-terminal Src kinase (Csk) that negatively regulates Pseudomonas invasion. Csk migrates to lipid raft domains, where it decreases phosphorylation of caveolin-2 by inactivating c-Src. Whereas Pseudomonas co-opts the endocytic properties of caveolin-2 for invasion, there also exists in these cells an intrinsic Csk-dependent cellular defense mechanism aimed at impairing this activity. The success of Pseudomonas in co-opting lipid raft-mediated endocytosis to invade lung epithelial cells may depend on the relative strengths of these counteracting signaling activities.