Leonard J. Lobo

Donor-specific antibodies are associated with antibody-mediated rejection, acute cellular rejection, bronchiolitis obliterans syndrome, and cystic fibrosis after lung transplantation

BACKGROUND Lung transplantation is limited by chronic lung allograft dysfunction. Acute cellular rejection (ACR) is a risk factor for allograft dysfunction; however, the role of antibody-mediated rejection (AMR) is not well characterized. METHODS This was a retrospective review from 2007 to 2011 of lung transplant recipients with human leukocyte antigen (HLA) antibody testing using Luminex (Luminex Corp, Austin, TX) single-antigen beads. Statistics included Fishers exact test for significance. RESULTS Donor-specific antibodies (DSA) developed in 13 of 44 patients. Of the 13 with DSA, 12 had cystic fibrosis compared with 18 of 31 in the non-DSA group (p = 0.035). Of those with DSAs, 23.1% occurred within the first year, and 69.2% occurred between 1 and 3 years. Twelve of 13 DSA patients had anti-HLA DQ specificity compared with 2 of 31 non-DSA patients (p = 0.0007). AMR developed in 10 of the 13 DSA patients compared with 1 of 31 non-DSA patients (p = 0.0001). The DSA group experienced 2.6 episodes/patient of cellular rejection vs 1.7 episodes/patient in the non-DSA group (p = 0.059). Bronchiolitis obliterans syndrome developed in 11 of 13 in the DSA group vs 10 of 31 in the non-DSA group (p = 0.0024). In the DSA group, 11.5% HLAs matched compared with 20.4% in the non-DSA group (p = 0.093). AMR developed in 11 of 22 patients in the non-DSA HLA group compared with 0 of 22 in the group without non-DSA HLA antibodies (p = 0.002). Survival at 1 and 3 years was 92% and 36% in the DSA group, respectively, and 97% and 65% in the non-DSA group. CONCLUSIONS DSAs and non-DSAs occur frequently after lung transplantation. DSAs are prevalent in the cystic fibrosis population and are associated with AMR, bronchiolitis obliterans syndrome, and possibly, ACR.

Lung transplant outcomes in cystic fibrosis patients with pre‐operative Mycobacterium abscessus respiratory infections

Mycobacterium abscessus in cystic fibrosis (CF) patients is considered a contraindication to lung transplantation. We examine the post‐transplant outcomes of CF patients with M. abscessus pre‐transplant.

Primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder of cilia structure and function, leading to chronic infections of the respiratory tract, fertility problems and disorders of organ laterality. Making a definitive diagnosis is challenging, utilizing characteristic phenotypes, ciliary functional and ultra-structural defects in addition to newer screening tools such as nasal nitric oxide and genetic testing. There are 21 known PCD causing genes and in the future, comprehensive genetic testing may help diagnosis young infants prior to developing symptoms thus improving survival. Therapy includes surveillance of pulmonary function and microbiology in addition to, airway clearance, antibiotics and early referral to bronchiectasis centers. Standardized care at specialized centers using a multidisciplinary approach is likely to improve outcomes. In conjunction with the PCD foundation and lead investigators and clinicians are developing a network of PCD clinical centers to coordinate the effort in North America and Europe. As the network grows, care and knowledge will undoubtedly improve.

Adult Lung Spheroid Cells Contain Progenitor Cells and Mediate Regeneration in Rodents With Bleomycin-Induced Pulmonary Fibrosis

Lung diseases are devastating conditions and ranked as one of the top five causes of mortality worldwide according to the World Health Organization. Stem cell therapy is a promising strategy for lung regeneration. Previous animal and clinical studies have focused on the use of mesenchymal stem cells (from other parts of the body) for lung regenerative therapies. We report a rapid and robust method to generate therapeutic resident lung progenitors from adult lung tissues. Outgrowth cells from healthy lung tissue explants are self‐aggregated into three‐dimensional lung spheroids in a suspension culture. Without antigenic sorting, the lung spheroids recapitulate the stem cell niche and contain a natural mixture of lung stem cells and supporting cells. In vitro, lung spheroid cells can be expanded to a large quantity and can form alveoli‐like structures and acquire mature lung epithelial phenotypes. In severe combined immunodeficiency mice with bleomycin‐induced pulmonary fibrosis, intravenous injection of human lung spheroid cells inhibited apoptosis, fibrosis, and infiltration but promoted angiogenesis. In a syngeneic rat model of pulmonary fibrosis, lung spheroid cells outperformed adipose‐derived mesenchymal stem cells in reducing fibrotic thickening and infiltration. Previously, lung spheroid cells (the spheroid model) had only been used to study lung cancer cells. Our data suggest that lung spheroids and lung spheroid cells from healthy lung tissues are excellent sources of regenerative lung cells for therapeutic lung regeneration.

Respiratory infections in patients with cystic fibrosis undergoing lung transplantation

Cystic fibrosis is an inherited disease characterised by chronic respiratory infections associated with bronchiectasis. Lung transplantation has helped to extend the lives of patients with cystic fibrosis who have advanced lung disease. However, persistent, recurrent, and newly acquired infections can be problematic. Classic cystic fibrosis-associated organisms, such as Staphylococcus aureus and Pseudomonas aeruginosa, are generally manageable post-transplantation, and are associated with favourable outcomes. Burkholderia cenocepacia poses particular challenges, although other Burkholderia species are less problematic. Despite concerns about non-tuberculous mycobacteria, especially Mycobacterium abscessus, post-transplantation survival has not been definitively shown to be less than average in patients with these infections. Fungal species can be prevalent before and after transplantation and are associated with high morbidity, so should be treated aggressively. Appropriate viral screening and antiviral prophylaxis are necessary to prevent infection with and reactivation of Epstein-Barr virus and cytomegalovirus and their associated complications. Awareness of drug pharmacokinetics and interactions in cystic fibrosis is crucial to prevent toxic effects and subtherapeutic or supratherapeutic drug dosing. With the large range of potential infectious organisms in patients with cystic fibrosis, infection control in hospital and outpatient settings is important. Despite its complexity, lung transplantation in the cystic fibrosis population is safe, with good outcomes if the clinician is aware of all the potential pathogens and remains vigilant by means of surveillance and proactive treatment.

Pan-Resistant Achromobacter xylosoxidans and Stenotrophomonas maltophilia Infection in Cystic Fibrosis Does Not Reduce Survival After Lung Transplantation.

Background The number of cystic fibrosis (CF) patients undergoing lung transplantation continues to grow, as does the prevalence of multidrug-resistant (MDR) gram-negative rods. However, the posttransplant survival of patients with MDR pathogens, specifically pan-resistant Achromobacter xylosoxidans and Stenotrophomonas maltophilia, is poorly characterized. Methods This was a retrospective review of CF patients (n = 186; all age, > 16 years) transplanted at the University of North Carolina from 1990 through 2013. Respiratory cultures before transplantation were reviewed for Achromobacter xylosoxidans and Stenotrophomonas maltophilia and their antibiotic susceptibility patterns. Bacteria were defined as pan-resistant if they were resistant or intermediate to all antibiotics tested; otherwise, organisms were defined as MDR. Patients were divided into 5 groups: pan-resistant Achromobacter xylosoxidans (n = 9), MDR Achromobacter xylosoxidans (n = 15), pan-resistant Stenotrophomonas maltophilia (n = 5), MDR Stenotrophomonas maltophilia (n = 26), and CF patients without Achromobacter xylosoxidans, Stenotrophomonas maltophilia or Bulkholderia cenocepacia (n = 131). Survival was compared, and cause of death was described. Results The survival was similar between all cohorts (P = 0.29). Recurrence of the primary pathogen was the most common with pan-resistant Achromobacter xylosoxidans (100%) followed by MDR Stenotrophomonas maltophilia (46%), MDR Achromobacter xylosoxidans (33%), and finally, pan-resistant Stenotrophomonas maltophilia (20%). Death attributable to the primary pathogen was uncommon, occurring in 2 patients with MDR Stenotrophomonas maltophilia and 2 patients with MDR Achromobacter xylosoxidans. Conclusions The CF patients with Achromobacter xylosoxidans and Stenotrophomonas maltophilia have similar posttransplant survival as compared to other CF patients, irrespective of their antibiotic susceptibility patterns. The presence of these organisms should not preclude lung transplantation.

Targeted repair of heart injury by stem cells fused with platelet nanovesicles

Stem cell transplantation, as used clinically, suffers from low retention and engraftment of the transplanted cells. Inspired by the ability of platelets to recruit stem cells to sites of injury on blood vessels, we hypothesized that platelets might enhance the vascular delivery of cardiac stem cells (CSCs) to sites of myocardial infarction injury. Here, we show that CSCs with platelet nanovesicles fused onto their surface membranes express platelet surface markers that are associated with platelet adhesion to injury sites. We also find that the modified CSCs selectively bind collagen-coated surfaces and endothelium-denuded rat aortas, and that in rat and porcine models of acute myocardial infarction the modified CSCs increase retention in the heart and reduce infarct size. Platelet-nanovesicle-fused CSCs thus possess the natural targeting and repairing ability of their parental cell types. This stem cell manipulation approach is fast, straightforward and safe, does not require genetic alteration of the cells, and should be generalizable to multiple cell types.The attachment of platelet nanovesicles to the surface of cardiac stem cells increases the retention of the cells delivered to the heart and reduces infarct size in rat and pig models of acute myocardial infarction.

Rituximab-associated progressive multifocal leukoencephalopathy after lung transplantation

Several innovative techniques have been described to overcome obstacles to surgically placed MCS systems in patients with palliated atrial switch procedures but have limited applicability during acute cardiovascular collapse. Among options available in the United States, only the TandemHeart provides sufficient cardiac output and decompresses the systemic ventricle. The recently approved Impella CP (4.0 liters/min; AbioMed Inc, Danvers, MA) may now be an option. However, the percutaneously placed Impella 2.5 does not provide adequate support, and the larger Impella 5.0 device requires surgical placement. Although extracorporeal membrane oxygenation provides circulatory support, it does not decompress the systemic ventricle. To perform a trans-baffle puncture, the needle is directed to the right and anterior (opposite of normal), and it can also be performed from the superior vena cava, which is normally extremely difficult. To gain insight into the complexity of the systemic and pulmonary venous baffles, which are complex, 3-dimensional intraatrial pathways, it helps to use the analogy of a pair of trousers. The systemic baffle is created by connecting the legs/limbs of the trouser to the superior and inferior vena cava and across the atrial septum to the mitral valve (Figure 2A). The right and left pulmonary veins join and wrap around the right side of the systemic venous baffle from posterior to anterior, creating the pulmonary venous baffle (Figure 2B and C). In conclusion, patients palliated with an atrial switch procedure can also benefit from rapid percutaneous MCS. Innovative adaptation of existing technology and collaborative teams are essential to provide cardiovascular care to adults who have received palliation for congenital heart disease.

Safety and Efficacy of Allogeneic Lung Spheroid Cells in a Mismatched Rat Model of Pulmonary Fibrosis

Idiopathic pulmonary fibrosis is a devastating interstitial lung disease characterized by the relentless deposition of extracellular matrix causing lung distortions and dysfunctions. The prognosis after detection is merely 3–5 years and the only two Food and Drug Administration‐approved drugs treat the symptoms, not the disease, and have numerous side effects. Stem cell therapy is a promising treatment strategy for pulmonary fibrosis. Current animal and clinical studies focus on the use of adipose or bone marrow‐derived mesenchymal stem cells. We, instead, have established adult lung spheroid cells (LSCs) as an intrinsic source of therapeutic lung stem cells. In the present study, we compared the efficacy and safety of syngeneic and allogeneic LSCs in immuno‐competent rats with bleomycin‐induced pulmonary inflammation in an effort to mitigate fibrosis development. We found that infusion of allogeneic LSCs reduces the progression of inflammation and fibrotic manifestation and preserves epithelial and endothelial health without eliciting significant immune rejection. Our study sheds light on potential future developments of LSCs as an allogeneic cell therapy for humans with pulmonary fibrosis. Stem Cells Translational Medicine 2017;9:1905–1916

Does ischemia-reperfusion injury after solid organ transplantation damage native organs?

CORRESPONDENCE Ischemia-reperfusion injury (IRI) is an unfortunate consequence of organ transplantation. During ischemia, macrophages and endothelial cells generate reactive oxygen species, nicotinamide adenine dinucleotide phosphate, nuclear factor-JB, nitric oxide synthases, and other proinflammatory cytokines. After blood reintroduces oxygen to the ischemic cells, the reactive oxygen species and cytokines activate neutrophils and alveolar macrophages further damaging cellular proteins, DNA, and plasma membranes. The damaged cells release allopeptides, glycolipids, and damage-associated molecular pattern molecules which are intracellular lipids and proteins that initiate and perpetuate the noninfectious inflammatory response. The allopeptides, damage-associated molecular pattern molecules, and glycolipids enter the circulation and are presented as foreign peptides or bind to the tolllike receptors on resident dendritic cells (DC), where an immune response is initiated. The triggered DCs interact with and activate natural killer (NK), NK T cells, and T cells (1). The activated lymphocytes release cytokines, activating other inflammatory cells, especially granulocytes and macrophages. This appears to be a mixed adaptive or innate immune response, and primary, secondary, and tertiary lymph organs, including the liver, augment IRI (Fig. 1). In this issue of Transplantation, Rancan et al. (2) confirmed previous studies demonstrating that IRI within the lung allograft might damage nontransplanted organs, namely, the liver, using a swine autotransplantation model. In addition, they showed that preconditioning with sevoflurane, a volatile anesthetic, attenuated these effects. Although these authors showed that lung IRI induced a proinflammatory cytokine response by measuring RNA and protein levels in the liver, they did not report an increase in liver enzymes, histologic evidence of leukocytes infiltration, or hepatocyte injury or apoptosis.Multiple studies have shown that volatile anesthetics can reduce the IRI in transplanted organs; however, no study has shown that it reduces the downstream effects outside the transplanted organ. In 2011, Casanova et al. (3) were the first to show that sevoflurane decreased the inflammatory response and oxidative stress in an ischemiareperfusion swine auto lung transplant model. Volatile anesthetics may be protective in several ways. First, they decrease the Na, K-ATPase, and sodium channel activities within the cells of the lung decreasing their metabolic needs; and second, they decrease the tumor necrosis factor->Yinduced microvascular endothelial permeability. Further studies are needed to determine if sevoflurane inhibits DC or NK-cell function. We analyzed the last 100 patients transplanted at our center to see if liver dysfunction was a notable downstream effect of lung transplantation. Surprisingly, posttransplant liver function testing was not routine so we were unable to determine if there was liver damage, even if transient, after transplantation. To further investigate, we reached out to the lung transplant programs at Duke University Medical Center in the United States (L. Snyder), University of Toronto Medical Center in Canada (S. Keshavjee), St Vincent’s Hospital in Australia (A. Glanville), University Hospital Zurich in Switzerland (A.Boehler), andHospital Foch inFrance (M.Stern). The other centers followed liver function immediately after transplantation and only noted episodes of ischemic hepatitis from operative complications. In addition, none noted significant long-term issues with liver dysfunction other than associated with azole antifungal therapy or pretransplant underlying liver disease. Several factors may contribute to the absence of clinically significant native organ inflammation after lung transplantation in humans. First, all transplants are done using a volatile anesthetic, such as isoflurane or sevoflurane. Second, all transplants use high-dose corticosteroids before implantation, and the corticosteroids downregulate the ischemiareperfusion inflammatory cascade by decreasing the numbers of circulating and organ-resident DCs, inhibiting interleukin-2 and tumor necrosis factor-> production and inhibiting a host of other proinflammatory mechanisms (4). Third, many centers use an induction agent at the time of transplant. Alemtuzumab and antithymocyte globulin suppress DC function and deplete a broad number of cell types, including most lymphocytes, which ANALYSIS AND COMMENTARY