Novel approaches for long-term lung transplant survival.

Allograft failure remains a major barrier in the field of lung transplantation and results primarily from acute and chronic rejection. To date, standard-of-care immunosuppressive regimens have proven unsuccessful in achieving acceptable long-term graft and patient survival. Recent insights into the unique immunologic properties of lung allografts provide an opportunity to develop more effective immunosuppressive strategies. Here we describe advances in our understanding of the mechanisms driving lung allograft rejection and highlight recent progress in the development of novel, lung-specific strategies aimed at promoting long-term allograft survival, including tolerance.

Management and outcomes of esophageal perforation.

BACKGROUND: Esophageal perforation is a morbid condition and remains a therapeutic challenge. We report the outcomes of a large institutional experience with esophageal perforation and identify risk factors for morbidity and mortality. METHODS: A retrospective analysis was conducted on 142 patients who presented with a thoracic or gastroesophageal junction esophageal perforation from 1995 to 2020. Baseline characteristics, operative or interventional strategies, and outcomes were analyzed by etiology of the perforation and management approach. Multivariable cox and logistic regression models were constructed to identify predictors of mortality and morbidity. RESULTS: Overall, 109 (77%) patients underwent operative intervention, including 80 primary reinforced repairs and 21 esophagectomies and 33 (23%) underwent esophageal stenting. Stenting was more common in iatrogenic (27%) and malignant (64%) perforations. Patients who presented with a postemetic or iatrogenic perforation had similar 90-day mortality (16% and 16%) and composite morbidity (51% and 45%), whereas patients who presented with a malignant perforation had a 45% 90-day mortality and 45% composite morbidity. Risk factors for mortality included age >65 years (hazard ratio [HR] 1.89 [1.02-3.26], P = 0.044) and a malignant perforation (HR 4.80 [1.31-17.48], P = 0.017). Risk factors for composite morbidity included pleural contamination (odds ratio [OR] 2.06 [1.39-4.43], P = 0.046) and sepsis (OR 3.26 [1.44-7.36], P = 0.005). Of the 33 patients who underwent stent placement, 67% were successfully managed with stenting alone and 30% required stent repositioning. CONCLUSIONS: Risk factors for morbidity and mortality after esophageal perforation include advanced age, pleural contamination, septic physiology, and malignant perforation. Primary reinforced repair remains a reasonable strategy for patients with an esophageal perforation from a benign etiology.

A Mixed-chimerism Protocol Utilizing Thymoglobulin and Belatacept Did Not Induce Lung Allograft Tolerance, Despite Previous Success in Renal Allotransplantation.

BACKGROUND: In kidney transplantation, long-term allograft acceptance in cynomolgus macaques was achieved using a mixed-chimerism protocol based on the clinically available reagents, rabbit anti-thymocyte globulin (ATG), and belatacept. Here, we have tested the same protocol in cynomolgus macaques transplanted with fully allogeneic lung grafts. METHODS: Five cynomolgus macaques underwent left orthotopic lung transplantation. Initial immunosuppression included equine ATG and anti-IL6RmAb induction, followed by triple-drug immunosuppression for 4 mo. Post-transplant, a nonmyeloablative conditioning regimen was applied, including total body and thymic irradiation. Rabbit ATG, belatacept, anti-IL6RmAb, and donor bone marrow transplantation (DBMT) were given, in addition to a 28-d course of cyclosporine. All immunosuppressant drugs were stopped on day 29 after DBMT. RESULTS: One monkey rejected its lung before DBMT due to AMR, after developing donor-specific antibodies. Two monkeys developed fatal post-transplant lymphoproliferative disorder, and both monkeys had signs of cellular rejection in their allografts upon autopsy. The remaining 2 monkeys showed severe cellular rejection on days 42 and 70 post-DBMT. Cytokine analysis suggested higher levels of pro-inflammatory markers in the lung transplant cohort, as compared to kidney recipients. CONCLUSION: Although the clinically applicable protocol showed success in kidney transplantation, the study did not show long-term survival in a lung transplant model, highlighting the organ-specific differences in tolerance induction.

Pulmonary Artery Resection During Lung Resection for Malignancy.

BACKGROUND: Complete resection of central tumors invading the main pulmonary artery (PA) requires arterial reconstruction to avoid pneumonectomy. Oncologic equivalence with pneumonectomy has been suggested. We review clinical selection and outcome for these uncommon procedures in the context of candidacy for pneumonectomy. METHODS: From 2000 to 2018, 9 different surgeons performed 34 pulmonary arterial resections for primary or metastatic pulmonary malignancy, with independent determination of pneumonectomy candidacy and arterioplasty technique. Patients undergoing limited lateral stapled PA resection (n = 3) or resection for metastasis (n = 3) were excluded from survival analysis. RESULTS: The PA was resected as a sleeve with primary anastomosis (14.7%) or noncircumferentially with primary (61.8%), stapled (8.8%), or patch (14.7%) closure. Arterial resections represented between 2.5% and 43% of each surgeon's pneumonectomy volume. Sixteen (47%) patients were candidates for pneumonectomy. There was no operative mortality and 1 death at 47 days. Postoperative complications occurred in 21 (61.8%) patients. No patient required completion pneumonectomy. Overall 5-year survival was 33% (95% confidence interval [CI], 12-53). Compared with pulmonary arterioplasty alone, patients undergoing bronchial sleeve resection and pulmonary arterioplasty had better disease-free 5-year survival (50% [95% CI, 18-82] vs 19% [95% CI, 5-43]; P = .04), higher complete resection rate (100% [95% CI, 83-100] vs 80% [95% CI, 56-94]; P = .23) and lower disease recurrence (8% [n = 1 of 13] vs 47% [n = 7 of 15]; P = .04); 80% of disease recurrence was distant. CONCLUSIONS: Resection and reconstruction of the PA for malignant lung disease may be safely performed. In candidates for pneumonectomy, arterial resection offers low operative risk. Long-term survival is impaired by distant, not local, recurrence emphasizing the importance of systemic therapy.

Surgical Management of Esophageal Epiphrenic Diverticula: A Transthoracic Approach Over Four Decades.

BACKGROUND: Epiphrenic esophageal diverticula are infrequent. Although surgical treatment is generally recommended, technique varies widely and optimal management remains controversial. This study evaluated a single-institution experience for surgical treatment of epiphrenic diverticula. METHODS: A retrospective review was made of medical records of 31 patients undergoing surgical treatment for epiphrenic diverticula from 1974 to 2016. RESULTS: There were 17 men (55%); median age was 65 years. Dysphagia (87%) and regurgitation (71%) were the most common symptoms. Three patients (10%) presented acutely: 2 with ruptured diverticula and 1 with hematemesis. All patients underwent an open transthoracic approach. Diverticulectomy was performed in 28 patients (90%), myotomy in 28 (90%), and a concomitant antireflux procedure in 6 (19%). A total of 22 patients (71%) underwent diverticulectomy and myotomy, 4 (13%) underwent diverticulectomy with myotomy and antireflux procedure, 2 (6%) had myotomy and antireflux, 2 had diverticulectomy alone, and 1 patient had imbrication of the diverticulum after myotomy. Overall, morbidity occurred in 11 patients (35.5%), with major morbidity in 6 (19.4%). There was one postoperative esophageal leak (3%). Ninety-day mortality was zero. Mean follow-up was 30 ± 43 months in 28 patients. Additional procedures (ie, reoperation, balloon dilation) were needed in 7 patients (25%). An excellent outcome (ie, absence of symptoms) was accomplished in 21 patients (75%). Acute presentation was associated with need for further procedures (p = 0.011) and symptoms at follow-up (p = 0.011). CONCLUSIONS: A tailored transthoracic approach to the surgical management of epiphrenic diverticula can provide excellent results. The need for a concomitant antireflux procedure remains controversial and may not be routinely necessary. Acute presentation is associated with poor functional outcome.

Induced regulatory T cells in allograft tolerance via transient mixed chimerism.

Successful induction of allograft tolerance has been achieved in nonhuman primates (NHPs) and humans via induction of transient hematopoietic chimerism. Since allograft tolerance was achieved in these recipients without durable chimerism, peripheral mechanisms are postulated to play a major role. Here, we report our studies of T cell immunity in NHP recipients that achieved long-term tolerance versus those that rejected the allograft (AR). All kidney, heart, and lung transplant recipients underwent simultaneous or delayed donor bone marrow transplantation (DBMT) following conditioning with a nonmyeloablative regimen. After DBMT, mixed lymphocyte culture with CFSE consistently revealed donor-specific loss of CD8+ T cell responses in tolerant (TOL) recipients, while marked CD4+ T cell proliferation in response to donor antigens was found to persist. Interestingly, a significant proportion of the proliferated CD4+ cells were FOXP3+ in TOL recipients, but not in AR or naive NHPs. In TOL recipients, CD4+FOXP3+ cell proliferation against donor antigens was greater than that observed against third-party antigens. Finally, the expanded Tregs appeared to be induced Tregs (iTregs) that were converted from non-Tregs. These data provide support for the hypothesis that specific induction of iTregs by donor antigens is key to long-term allograft tolerance induced by transient mixed chimerism.

Use of Proteolytic Enzymes in the Treatment of Proteinaceous Esophageal Food Impaction.

BACKGROUND: Proteinaceous esophageal food impaction typically requires endoscopic intervention. An alternative approach is the use of proteolytic enzymes. Concerns regarding the use of proteolytic enzymes include the risk of perforation and aspiration pneumonitis. OBJECTIVE: We retrospectively reviewed our series of 69 patients treated with papain to determine the safety and efficacy of proteolytic enzymes. METHODS: Patients were retrospectively reviewed if treated for an esophageal food impaction from 1999 through 2008. RESULTS: Median age was 56 years (range 19-91 years), with 46 male and 23 female patients. In 27 patients (39%) this was their first presentation, in 14 (20%) it was the second, and 28 (41%) had multiple previous episodes. Meat was the cause in 49 (71%), chicken in 6 (9%), fish in 3 (4%), and unspecified in 11 (16%). All patients presented with dysphagia for solids, 56 (81%) could not tolerate liquids. Papain solution, 1 tsp in 8 oz of water, was given to patients in an unlimited quantity. Papain was successful in relieving the obstruction in 60 patients (87%). The remaining 9 patients (13%) underwent endoscopy with successful retrieval. No patient suffered a perforation, either with papain ingestion or endoscopy. There were no episodes of pneumonitis or pneumonia. CONCLUSIONS: We have used proteolytic enzymes with a high success rate and with minimal complication. Further, if proteolytic enzymes fail, endoscopy can be performed safely and effectively. We recommend the use of proteolytic enzymes as the initial management in all patients with proteinaceous food impaction of the esophagus.

Natural IgM Blockade Limits Infarct Expansion and Left Ventricular Dysfunction in a Swine Myocardial Infarct Model.

BACKGROUND: Acute coronary syndrome is the leading cause of mortality worldwide. However, treatment of acute coronary occlusion inevitably results in ischemia-reperfusion injury. Circulating natural IgM has been shown to play a significant role in mouse models of ischemia-reperfusion injury. A highly conserved self-antigen, nonmuscle myosin heavy chain II, has been identified as a target of pathogenic IgM. We hypothesized that a monoclonal antibody (m21G6) directed against nonmuscle myosin heavy chain II may inhibit IgM binding and reduce injury in a preclinical model of myocardial infarction. Thus, our objective was to evaluate the efficacy of intravenous m21G6 treatment in limiting infarct expansion, troponin release, and left ventricular dysfunction in a swine myocardial infarction model. METHODS AND RESULTS: Massachusetts General Hospital miniature swine underwent occlusion of the midleft anterior descending coronary artery for 60 minutes, followed by 1 hour, 5-day, or 21-day reperfusion. Specificity and localization of m21G6 to injured myocardium were confirmed using fluorescently labeled m21G6. Treatment with m21G6 before reperfusion resulted in a 49% reduction in infarct size (P<0.005) and a 61% reduction in troponin-T levels (P<0.05) in comparison with saline controls at 5-day reperfusion. Furthermore, m21G6-treated animals recovered 85.4% of their baseline left ventricular function as measured by 2-dimensional transthoracic echocardiography in contrast to 67.1% in controls at 21-day reperfusion (P<0.05). CONCLUSIONS: Treatment with m21G6 significantly reduced infarct size and troponin-T release, and led to marked preservation of cardiac function in our study. Overall, these findings suggest that pathogenic IgM blockade represents a valid therapeutic strategy in mitigating myocardial ischemia-reperfusion injury.

Myeloid sarcoma: an unusual presentation for acute tracheal stenosis.

BACKGROUND AND AIMS: Extramedullary involvement of acute myelogenous leukemia (AML) is rare and has been reported under the terms myeloid sarcoma (MS), granulocytic sarcoma, chloroma, extramedullary acute myeloid leukemia, myeloblastoma and myelosarcoma. The most common extramedullary involvement includes soft tissues and lymph nodes, but it may arise in different sites of the body. There are only very few reports about MS in the pulmonary system, and involvement of the trachea is extremely rare. METHODS: This is the first report of initial presentation of MS by severe acute tracheal stenosis. RESULTS: After failed tracheal dilatation, a tracheostomy was performed where tracheal tissue was submitted for pathology. Histology of the tracheal biopsy and bone marrow revealed AML. The patient was subsequently referred to our oncology service for further management. CONCLUSION: Myeloid sarcoma should be part of the differential for acute tracheal stenosis.

Twelve-Hour Hypothermic Machine Perfusion for Donor Heart Preservation Leads to Improved Ultrastructural Characteristics Compared to Conventional Cold Storage.

BACKGROUND Hypothermic machine perfusion of donor hearts has the theoretical advantage of continuous aerobic metabolism and washes out toxic metabolic byproducts. Here, we studied the effect of hypothermic machine perfusion on cardiac myocyte integrity when hearts are preserved for longer ischemic times (12 hours). MATERIAL AND METHODS Pig hearts were harvested and stored in Celsior® solution for 12 hours using either conventional cold storage on ice (12 h CS, n=3) or pulsatile perfusion with the Paragonix Sherpa Perfusion™ Cardiac Transport System at different flow rates (12 h PP, n=3 or 12 h PP low flow, n=2). After cold preservation, hearts were reperfused using an LV isovolumic Langendorff system. Controls (n=3) were reperfused immediately after organ harvest. Biopsies were taken from the apex of the left ventricle before storage, after storage and after reperfusion to measure ATP and endothelin-1 content in the tissue. TUNEL staining for signs of apoptosis and electron microscopy of the donor hearts were performed. RESULTS 12 h PP hearts showed significantly more weight gain than 12 h CS and controls after preservation. Pulsatile perfused hearts showed less ATP depletion, lower endothelin-1 levels and less apoptosis after preservation compared to CS. Electron microscopy showed damaged muscle fibers, endothelial cell rupture, and injury of mitochondria in the 12 h CS group, while machine perfusion could preserve the cell structures. CONCLUSIONS Hypothermic machine perfusion of donor hearts can preserve the cell structures better than conventional cold storage in prolonged ischemic times. Hypothermic pulsatile perfusion may therefore enable longer preservation times of donor hearts. Whether this method is able to avoid primary graft failure after orthotopic heart transplantation remains to be evaluated in further studies.

Recipient-matching of Passenger Leukocytes Prolongs Survival of Donor Lung Allografts in Miniature Swine.

BACKGROUND: Allograft rejection continues to be a vexing problem in clinical lung transplantation, and the role played by passenger leukocytes in the rejection or acceptance of an organ is unclear. We tested whether recipient-matching of donor graft passenger leukocytes would impact graft survival in a preclinical model of orthotopic left lung transplantation. METHODS: In the experimental group (group 1), donor lungs were obtained from chimeric swine, in which the passenger leukocytes (but not the parenchyma) were major histocompatibility complex-matched to the recipients (n = 3). In the control group (group 2), both the donor parenchyma and the passenger leukocytes were major histocompatibility complex-mismatched to the recipients (n = 3). RESULTS: Lungs harvested from swine previously rendered chimeric by hematopoietic stem cell transplantation using recipient-type cells showed a high degree of passenger leukocyte chimerism by immunohistochemistry and flow cytometry. The chimeric lungs containing passenger leukocytes matched to the lung recipient (group 1) survived on average 107 days (range, 80-156). Control lung allografts (group 2) survived on average 45 days (range, 29-64; P < 0.05). CONCLUSIONS: Our data indicate that recipient-matching of passenger leukocytes significantly prolongs lung allograft survival.

Preservation of donor hearts using hypothermic oxygenated perfusion.

BACKGROUND: Hypothermic machine perfusion of donor hearts enables continuous aerobic metabolism and washout of toxic metabolic byproducts. We evaluated the effect of machine perfusion on cardiac myocyte integrity in hearts preserved for 4 h in a novel device that provides pulsatile oxygenated hypothermic perfusion (Paragonix Sherpa Perfusion™ Cardiac Transport System). MATERIAL AND METHODS: Pig hearts were harvested and stored in Celsior® solution for 4 h using either conventional cold storage on ice (4-h CS, n=6) or the Sherpa device (4-h pulsatile perfusion (PP), n=6). After cold preservation, hearts were evaluated using a non-working heart Langendorff system. Controls (n=3) were reperfused immediately after organ harvest. Biopsies were taken from the apex of the left ventricle before storage, after storage, and after reperfusion to measure ATP content and endothelin-1 in the tissue. Ultrastructural analysis using electron microscopy was performed. RESULTS: Four-hour CS, 4-h PP, and control group did not show any significant differences in systolic or diastolic function (+dP/dt, -dP/dt, EDP). Four-hour PP hearts showed significantly more weight gain than 4-h CS after preservation, which shows that machine perfusion led to myocardial edema. Four-hour CS led to higher endothelin-1 levels after preservation, suggesting more endothelial dysfunction compared to 4-h PP. Electron microscopy revealed endothelial cell rupture and damaged muscle fibers in the 4-h CS group after reperfusion, but the cell structures were preserved in the 4-h PP group. CONCLUSIONS: Hypothermic pulsatile perfusion of donor hearts leads to a better-preserved cell structure compared to the conventional cold storage method. This may lead to less risk of primary graft failure after orthotopic heart transplantation.

Comparison of perioperative outcomes following open versus minimally invasive Ivor Lewis oesophagectomy at a single, high-volume centre.

OBJECTIVES: With the increasing popularity of minimally invasive oesophageal resections, equivalence, if not superiority, to open techniques must be demonstrated. Here we compare our open and minimally invasive Ivor Lewis oesophagectomy (MIE) experience. METHODS: A prospective database of all oesophagectomies performed at Massachusetts General Hospital in Boston, MA between November 2007 and January 2011 was analysed. A total of 38 MIE and 76 open Ivor Lewis (OIE) oesophagectomies were performed for oesophageal carcinoma. Sixty-day surgical, oncological and postoperative outcomes were examined between the two groups. RESULTS: Groups had similar demographics in terms of age, gender, tumour histology, clinical stage, preoperative comorbidities and neoadjuvant therapy. No difference was found with respect to adequacy of oncological resections. The median number of lymph nodes retrieved (OIE: 21, inter-quartile range (IQR): (16, 27) versus MIE: 19, IQR: (15, 28)), resection margins (OIE: 6.6% positive versus MIE: no positive margins) and 60-day mortality (OIE: 2.6% versus MIE: no deaths) were comparable. However, rates of pulmonary complications were significantly lower in the MIE group (OIE: 43.4 versus MIE: 2.6%, P < 0.001). Additionally, the median length of ICU and hospital stay, intraoperative blood loss and amount of intravenous fluids infused intraoperatively were also significantly decreased with MIE, while median operative times and the requirement for intraoperative blood transfusion were not significantly different between the two groups. Multivariate logistic regression analysis identified MIE as the only variable associated with a significant reduction in the rate of pulmonary complications in our study, while pre-existing pulmonary comborbidity was associated with an increased risk of pulmonary complications. CONCLUSIONS: Open and MIE appear equivalent with regard to early oncological outcomes. A minimally invasive approach, however, appears to lead to a significant reduction in the rate of postoperative pulmonary complications. Length of ICU and hospital stay, as well as intraoperative blood loss and intravenous fluid requirements are also reduced in the setting of MIE. Long-term survival data will need to be followed closely. A large, multi-centred, randomized, controlled trial is warranted to confirm these results.

Absence of Gal epitope prolongs survival of swine lungs in an ex vivo model of hyperacute rejection.

BACKGROUND: Galactosyl transferase gene knock-out (GalTKO) swine offer a unique tool to evaluate the role of the Gal antigen in xenogenic lung hyperacute rejection. METHODS: We perfused GalTKO miniature swine lungs with human blood. Results were compared with those from previous studies using wild-type and human decay-accelerating factor-transgenic (hDAF(+/+) ) pig lungs. RESULTS: GalTKO lungs survived 132 ± 52 min compared to 10 ± 9 min for wild-type lungs (P = 0.001) and 45 ± 60 min for hDAF(+/+) lungs (P = 0.18). GalTKO lungs displayed stable physiologic flow and pulmonary vascular resistance (PVR) until shortly before graft demise, similar to autologous perfusion, and unlike wild-type or hDAF(+/+) lungs. Early (15 and 60 min) complement (C3a) and platelet activation and intrapulmonary platelet deposition were significantly diminished in GalTKO lungs relative to wild-type or hDAF(+/+) lungs. However, GalTKO lungs adsorbed cytotoxic anti-non-Gal antibody and elaborated high levels of thrombin; their demise was associated with increased PVR, capillary congestion, intravascular thrombi and strong CD41 deposition not seen at earlier time points. CONCLUSIONS: In summary, GalTKO lungs are substantially protected from injury but, in addition to anti-non-Gal antibody and complement, platelet adhesion and non-physiologic intravascular coagulation contribute to Gal-independent lung injury mechanisms.

Autoimmune sensitization to cardiac myosin leads to acute rejection of cardiac allografts in miniature swine.

BACKGROUND: Recent studies in mice and patients suggest that posttransplantation induction of autoimmune responses to tissue-specific antigens contributes to the rejection of major histocompatibility complex mismatched allotransplants. The relevance of this phenomenon to the rejection of major and minor histocompatibility-mismatched allografts performed in large-animal models remains to be established. METHODS: Miniature swine were immunized with cardiac myosin (CM) in Freund's adjuvant and received heterotopic, minor antigen-mismatched heart transplants. T-cell (proliferation and delayed type hypersensitivity [DTH]) and B-cell (antibody) responses specific to CM were measured. The rejection of heart transplants was assessed histologically. RESULTS: Three of four swine that were immunized with CM before receiving a minor antigen-mismatched heart transplant exhibited potent DTH, T-cell proliferation and antibody responses to CM and rejected their grafts acutely. The fourth swine, which failed to mount a significant DTH response to CM and displayed low and transient anti-CM antibody titers, demonstrated long-term allograft survival. CONCLUSIONS: This large-animal study supports the relevance of autoimmunity to CM in the rejection of minor antigen disparate cardiac allotransplants.