An Update in Antimicrobial Therapies and Infection Prevention in Pediatric Lung Transplant Recipients.

Lung transplantation can offer life-prolonging therapy to children with otherwise terminal end-stage lung disease. However, infectious complications, like those experienced by their adult counterparts, are a significant cause of morbidity and mortality. These include bacteria, viruses, and fungi that infect the patient pretransplant and those that may be acquired from the donor or by the recipient in the months to years posttransplant. An understanding of the approach to the management of each potential infecting organism is required to ensure optimal outcomes. In particular, emphasis on aggressive preoperative management of infections in pediatric patients with cystic fibrosis is important. These include multidrug-resistant Gram-negative bacteria, fungi, and Mycobacterium abscessus, the posttransplant outcome of which depends on optimal pretransplant management, including vaccination and other preventive, antibiotic-sparing strategies. Similarly, increasing the transplant donor pool to meet rising transplant demands is an issue of critical importance. Expanded-criteria donors-those at increased risk of blood-borne viruses in particular-are increasingly being considered and transplants undertaken to meet the rising demand. There is growing evidence in the adult pool that these transplants are safe and associated with comparable outcomes. Pediatric transplanters are therefore likely to be presented with increased-risk donors for their patients. Finally, numerous novel antibiotic-sparing therapeutic approaches are on the horizon to help combat infections that currently compromise transplant outcomes.

Anti-fibrotic Effects of CXCR4-Targeting i-body AD-114 in Preclinical Models of Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic fibrotic lung disease that is prevalent in individuals >50 years of age, with a median survival of 3-5 years and limited therapeutic options. The disease is characterized by collagen deposition and remodeling of the lung parenchyma in a process that is thought to be driven by collagen-expressing immune and structural cells. The G-protein coupled C-X-C chemokine receptor 4, CXCR4, is a candidate therapeutic target for IPF owing to its role in the recruitment of CXCR4+ fibrocytes from the bone marrow to fibrotic lung tissue and its increased expression levels by structural cells in fibrotic lung tissue. We have engineered a novel fully human single domain antibody "i-body" called AD-114 that binds with high affinity to human CXCR4. We demonstrate here that AD-114 inhibits invasive wound healing and collagen 1 secretion by human IPF fibroblasts but not non-diseased control lung fibroblasts. Furthermore, in a murine bleomycin model of pulmonary fibrosis, AD-114 reduced the accumulation of fibrocytes (CXCR4+/Col1+/CD45+) in fibrotic murine lungs and ameliorated the degree of lung injury. Collectively, these studies demonstrate that AD-114 holds promise as a new biological therapeutic for the treatment of IPF.

Intra-operative protective mechanical ventilation in lung transplantation: a randomised, controlled trial.

Primary graft dysfunction occurs in up to 25% of patients after lung transplantation. Contributing factors include ventilator-induced lung injury, cardiopulmonary bypass, ischaemia-reperfusion injury and excessive fluid administration. We evaluated the feasibility, safety and efficacy of an open-lung protective ventilation strategy aimed at reducing ventilator-induced lung injury. We enrolled adult patients scheduled to undergo bilateral sequential lung transplantation, and randomly assigned them to either a control group (volume-controlled ventilation with 5 cmH2 O, positive end-expiratory pressure, low tidal volumes (two-lung ventilation 6 ml.kg-1 , one-lung ventilation 4 ml.kg-1 )) or an alveolar recruitment group (regular step-wise positive end-expiratory pressure-based alveolar recruitment manoeuvres, pressure-controlled ventilation set at 16 cmH2 O with 10 cmH2 O positive end-expiratory pressure). Ventilation strategies were commenced from reperfusion of the first lung allograft and continued for the duration of surgery. Regular PaO2 /FI O2 ratios were calculated and venous blood samples collected for inflammatory marker evaluation during the procedure and for the first 24 h of intensive care stay. The primary end-point was the PaO2 /FI O2 ratio at 24 h after first lung reperfusion. Thirty adult patients were studied. The primary outcome was not different between groups (mean (SD) PaO2 /FI O2 ratio control group 340 (111) vs. alveolar recruitment group 404 (153); adjusted p = 0.26). Patients in the control group had poorer mean (SD) PaO2 /FI O2 ratios at the end of the surgical procedure and a longer median (IQR [range]) time to tracheal extubation compared with the alveolar recruitment group (308 (144) vs. 402 (154) (p = 0.03) and 18 (10-27 [5-468]) h vs. 15 (11-36 [5-115]) h (p = 0.01), respectively). An open-lung protective ventilation strategy during surgery for lung transplantation is feasible, safe and achieves favourable ventilation parameters.

ABO incompatible renal transplantation following lung transplantation.

We present management strategies utilised for the first case of an urgent live-donor ABO incompatible B blood group renal transplant, in a patient with a prior A blood group lung transplant for cystic fibrosis. Three years on, renal function is excellent and stable, whilst lung function has improved.

Idiopathic pulmonary fibrosis: an Australian perspective.

Idiopathic pulmonary fibrosis is a progressive interstitial lung disease of unknown aetiology with a dismal median survival of 3 years. Patients typically develop progressive dyspnoea and increasing exercise limitation. With a rising incidence and prevalence, an unpredictable disease course and limited treatment options, it is rapidly becoming an important public health concern. To date, lung transplantation has been the sole viable hope for treatment for those who qualify. However, the landscape of idiopathic pulmonary fibrosis management is changing, with the recent emergence of novel pharmacotherapy shown to have a favourable influence on the natural history of this disease.

HLA Matching at the Eplet Level Protects Against Chronic Lung Allograft Dysfunction.

Donor selection in lung transplantation (LTx) is historically based upon clinical urgency, ABO compatibility, and donor size. HLA matching is not routinely considered; however, the presence or later development of anti-HLA antibodies is associated with poorer outcomes, particularly chronic lung allograft dysfunction (CLAD). Using eplet mismatches, we aimed to determine whether donor/recipient HLA incompatibility was a significant predictor of CLAD. One hundred seventy-five LTx undertaken at the Alfred Hospital between 2008 and 2012 met criteria. Post-LTx monitoring was continued for at least 12 months, or until patient death. HLA typing was performed by sequence-based typing and Luminex sequence-specific oligonucleotide. Using HLAMatchmaker, eplet mismatches between each donor/recipient pairing were analyzed and correlated against incidences of CLAD. HLA-DRB1/3/4/5+DQA/B eplet mismatch was a significant predictor of CLAD (hazard ratio [HR] 3.77, 95% confidence interval [CI]: 1.71-8.29 p < 0.001). When bronchiolitis obliterans syndrome (BOS) and restrictive allograft syndrome (RAS) were analyzed independently, HLA-DRB1/3/4/5 + DQA/B eplet mismatch was shown to significantly predict RAS (HR 8.3, 95% CI: 2.46-27.97 p < 0.001) but not BOS (HR 1.92, 95% CI: 0.64-5.72, p = 0.237). HLA-A/B eplet mismatch was shown not to be a significant predictor when analyzed independently but did provide additional stratification of results. This study illustrates the importance of epitope immunogenicity in defining donor-recipient immune compatibility in LTx.

Mycobacterium abscessus Complex - a Particular Challenge in the Setting of Lung Transplantation.

Mycobacterium abscessus complex is an emerging pathogen in lung transplant candidates and recipients. M. abscessus complex is widespread in the environment and can cause pulmonary, skin and soft tissue, and disseminated infection, particularly in lung transplant recipients. It is innately resistant to many antibiotics making it difficult to treat. Herein we describe the epidemiology, clinical manifestations, diagnosis and treatment of M. abscessus with an emphasis on lung transplant candidates and recipients. We also outline the areas where data are lacking and the areas where further research is urgently needed.

Comparative analysis of how immune sensitization is defined prior to lung transplantation.

BACKGROUND: Immune sensitization prior to lung transplantation may be associated with worse survival. Using solid phase assays to define sensitization, we assessed the relationship between PRA status, donor specific anti-HLA antibodies (DSA) pre-transplant, cytotoxic cross match results and the clinical outcomes following lung transplantation. METHODS: Luminex assays determined the presence of antibodies to class I and class II MHC molecules prior to lung transplantation. At the time of transplant, the PRA status, the presence of DSA and prospective cytotoxic cross match result were analysed in 195 patients undergoing lung transplantation between June 2008 and June 2012. Clinical outcomes analysed included acute cellular and antibody-mediated rejection, chronic lung allograft dysfunction (CLAD) and mortality. RESULTS: At the time of transplant, 45% of patients had a positive PRA and 29% had DSA. On univariate analysis, the presence of pre-transplant class I or II anti-HLA donor-specific antibodies was not associated with the development of chronic lung allograft dysfunction (CLAD) despite significant associations with PRA status and B-cell crossmatch. CONCLUSION: Defining sensitization using solid phase assays provide additional details regarding donor-specific sensitization but did not provide additional prognostic information to that provided by historically available cell-based cross-match assays.

Donation After Circulatory Determination of Death Lung Transplantation for Pulmonary Arterial Hypertension: Passing the Toughest Test.

Lung transplantation (LTx) is a therapeutic option for severe pulmonary arterial hypertension (PAH) patients failing optimal medical therapy. The use of donation after circulatory determination of death (DCDD) donor lungs for PAH LTx has rarely been reported, primarily reflecting concerns that DCDD lungs represent extended criteria donors, at risk of morbidity and mortality. A retrospective study of all Alfred Hospital DCDD and DNDD (donation after neurologic determination of death) PAH LTx was undertaken. Protocolized fluid/inotrope/ventilator and extracorporeal membrane oxygenation (ECMO) strategies were utilized. Since our first DCDD LTx in 2006, 512 LTx have been performed. Of 31 PAH recipients, 11 received DCDD lungs (11% of DCDD LTx) and 20 received DNDD lungs (5% of DNDD LTx) (p = 0.04). Only one PAH patient died on the LTx waiting list. Peri-LTx ECMO was utilized in 3/11 (27%) DCDD and 6/20 (30%) DNDD PAH LTx (p = 0.68). Primary graft dysfunction, intensive care, and overall stay were the same in both groups. Survival at 1 and 8 years was 100% and 80% for DCDD versus 100% and 70% for DNDD LTx (p = 0.88), respectively. In conclusion, excellent results can be achieved for PAH LTx. DCDD donor lungs are not extended lungs per se having passed the toughest test.

Evolving practice: X-linked agammaglobulinemia and lung transplantation.

X-linked agammaglobulinemia (XLA) is a rare primary humoral immunodeficiency syndrome characterized by agammaglobulinemia, recurrent infections and bronchiectasis. Despite the association with end-stage bronchiectasis, the literature on XLA and lung transplantation is extremely limited. We report a series of 6 XLA patients with bronchiectasis who underwent lung transplantation. Short-term outcomes were excellent however long-term outcomes were disappointing with a high incidence of pulmonary sepsis and chronic lung allograft dysfunction (CLAD).

Laboratory identification of donor-derived coxsackievirus b3 transmission.

Unexpected donor-to-recipient infectious disease transmission is an important, albeit rare, complication of solid organ transplantation. Greater work and understanding about the epidemiology of these donor-derived transmissions is continually required to further mitigate this risk. Herein we present the first reported case of proven donor-derived transmission of coxsackievirus serogroup-3, an enterovirus, following solid organ transplant. Swift and effective communication between the organ donation agency, treating physicians, laboratory testing and notification ensured a coordinated approach. The resulting clinical syndromes in the organ recipients were mild. This case highlights the requirement for ongoing surveillance over a broad range of infecting pathogens that may present as a donor-derived infection.

A randomized, double-blind, placebo-controlled, multicenter study of rabbit ATG in the prophylaxis of acute rejection in lung transplantation.

ATG-Fresenius S (ATG-F) is a polyclonal anti-human-T-lymphocyte immunoglobulin preparation that has been clinically developed to prevent episodes of acute cellular rejection. This study evaluated the efficacy and safety of ATG-F at doses of 5 and 9 mg/kg versus placebo in adult recipients of a primary lung allograft. The primary efficacy composite end point was defined as death, graft loss, acute rejection and/or loss to follow-up within 12 months of transplantation. The interim analysis showed the ATG-F 5 mg/kg treatment to be inefficacious, and it would be impossible to enroll enough patients to power the study to show a difference between the 9 mg/kg arm and the placebo arm. Therefore, the main focus of the study shifted to the safety end points and a descriptive analysis of the primary end point. At 12 months posttransplant, the efficacy failure rate was not significantly different between the ATG-F 9 mg/kg group and the placebo group (40.2% vs. 36.7%, respectively). This large study did not demonstrate a significant reduction in acute cellular rejection, graft loss or death with single-dose induction therapy with ATG-F within the first year after lung transplantation.

Lessons and insights from ABO-incompatible lung transplantation.

With ABO blood group incompatibility (ABOi) between donor and recipient becoming a part of mainstream living-donor renal transplantation, the applicability of ABOi to other areas of transplantation is being reconsidered. Here we present a case of inadvertent ABOi lung retransplantation managed successfully with initial plasmapheresis, antithymocyte globulin and intravenous immunoglobulin; and subsequently with oral cyclophosphamide and sirolimus in addition to tacrolimus and prednisolone. Interestingly, in the setting of solid levels of tacrolimus and sirolimus, the patient developed a fatal thrombotic microangiopathy of uncertain origin subsequent to the cessation of cyclophosphamide at 9 years posttransplant. It is apparent that ABOi lung transplantation can result in surprisingly successful long-term outcomes. Low pretransplant antibody titers likely aid this and, in pediatric neonatal or infant cases, this may not be uncommon. We must proceed cautiously as there are significant risks. Understanding the monitoring, prevention and treatment of lung transplant antibody-mediated rejection, while avoiding the long-term complications of overimmunosuppression, will be the keys to the success of future cases.

Lung transplantation in children following bone marrow transplantation: a multi-center experience.

Allogenic BMT has been successfully performed as a treatment for hematologic diseases with an expected long-term survival. This survival is truncated by respiratory complications including airway obstruction especially BO. Chronic GVHD has been reported to precede almost all cases reported. LTx has become a therapeutic life-saving option for patients with end-stage lung disease that maybe offered for the treatment of GVHD. We report a multi-center experience of pediatric LTx following BMT in 11 patients age- and gender-matched with 11 controls who received LTx for end-stage lung disease secondary to CF. Overall death was 36.4% over a follow-up period of 19 months (range 3-36 months) for the cases and 27.3% for the control group followed for 17 months (range 8-32 months). Median FEV1 one yr post-transplant for the cases was 78% predicted compared with 67.3% predicted for the controls. The median for episodes of infection was comparable at a median of one episode per patient through the entire follow-up period among both groups. Acute rejection episodes were significantly higher in the control group with a median of one episode per patient in the control group compared to none within the cases. Our data suggest that LTx may be a valuable therapeutic option for children with end-stage lung disease post-BMT with comparable survival outcome to that after LTx in children for other indications such as CF. Hospital stay was significantly longer in our case group. Infection rate was comparable between groups albeit type of infection varied. Significantly and of interest is that acute rejection episodes were non-existent in these cases.

Cytomegalovirus replication within the lung allograft is associated with bronchiolitis obliterans syndrome.

Early studies reported cytomegalovirus (CMV) pneumonitis as a risk factor for development of bronchiolitis obliterans syndrome (BOS) following lung transplantation. While improvements in antiviral prophylaxis have resulted in a decreased incidence of CMV pneumonitis, molecular diagnostic techniques allow diagnosis of subclinical CMV replication in the allograft. We hypothesized that this subclinical CMV replication was associated with development of BOS. We retrospectively evaluated 192 lung transplant recipients (LTR) from a single center between 2001 and 2009. Quantitative (PCR) analysis of CMV viral load and histological evidence of CMV pneumonitis and acute cellular rejection was determined on 1749 bronchoalveolar lavage (BAL) specimens and 1536 transbronchial biopsies. CMV was detected in the BAL of 41% of LTR and was significantly associated with the development of BOS (HR 1.8 [1.1-2.8], p = 0.02). This association persisted when CMV was considered more accurately as a time-dependent variable (HR 2.1 [1.3-3.3], p = 0.003) and after adjustment for significant covariates in a multivariate model. CMV replication in the lung allograft is common following lung transplantation and is associated with increased risk of BOS. As antiviral prophylaxis adequately suppresses CMV longer prophylactic strategies may improve long-term outcome in lung transplantation.

Lung transplantation in pulmonary fibrosis: challenging early outcomes counterbalanced by surprisingly good outcomes beyond 15 years.

Interstitial lung disease (ILD) has been reported to have a poor outcome following lung transplantation due to difficulties getting ill recipients to transplantation and challenging early postoperative outcomes. To assess long-term outcomes for this cohort, we performed a retrospective 18-year chart review of all ILD lung transplant recipients. ILD single (SLT) and bilateral sequential lung transplantations (BSLT) were compared with all other lung transplant patients and International Society for Heart and Lung Transplantation (ISHLT) Registry data over the same time period. Of 585 lung transplantations, 90 (15%) were ILD (53 SLT, 37 BSLT); 67 (74%) were idiopathic pulmonary fibrosis (IPF), 9 (10%) were sarcoidosis, 9 (10%) were lymphangioleiomyomatosis, and 5 (6%) had other indications. Mean age was 52 years (range, 34-69 years). Actuarial survival at 1, 5, 10, 15, and 18 years compared favorably to all other lung transplantations performed (77% vs 83%, 51% vs 50%, 42% vs 26%, 28% vs 17%, and 28% vs 8%, respectively). IPF actuarial survival at 1, 5, and 10 years appeared superior to ISHLT Registry data (76% vs 72%, 50% vs 44%, and 34% vs 20%, respectively). There was equivocal survival between SLT and BSLT at 1, 5, and 10 years (78% vs 68%, 49% vs 50%, and 29% vs 50%, respectively). Our ILD figures compared favorably to lung transplantation for other diseases and international standards, while survival from SLT was as successful as BSLT both in the short and the longer term. Consideration should be given to utilizing SLT to maximize the allocation of donor lungs and to decrease waiting list mortality associated with IPF.

Rehabilitation and transition after lung transplantation in children.

We describe the key components of an outpatient pediatric recovery and rehabilitation program set up within the adult lung transplant service at the Alfred Hospital, Melbourne. Following discharge, pediatric lung transplant recipients and their families participated in an intensive 3-month outpatient rehabilitation program. Weekly sessions included education regarding transplant issues, physiotherapy, and occupational therapy sessions. The overall aim of the program was to comprehensively address physical rehabilitation and psychosocial and educational needs. Sessions tailored to meet the individual needs of the child were presented at an appropriate cognitive level. Education sessions for both the children and parents focused on medications, identification of infection and rejection, nutrition, physiotherapy/rehabilitation, occupational roles and stress management, donor issues, psychosocial readjustment, and transition issues. Physiotherapy included a progressive aerobic and strength training program, postural reeducation, and core stability. We incorporate Age-appropriate play activities: running, dancing, jumping, ball skills, and so on. Occupational therapy sessions addressed the primary roles of patient, students, and player. Transitions such as returning to school, friends, and the community were explored. Issues discussed included adjustment to new health status, strategies to manage side effects of medications, and altered body image issues. Weekly multidisciplinary team meetings were used to discuss and plan the rehabilitation progress. School liaison and visits occurred prior to school commencement with follow-up offered to review the ongoing transition process. Both patients and parents have reported a high level of satisfaction with the rehabilitation program. We plan to formally evaluate the program in the future.

Linking CMV serostatus to episodes of CMV reactivation following lung transplantation by measuring CMV-specific CD8+ T-cell immunity.

CMV-specific immunity was assessed in a longitudinal cohort of 39 lung transplant recipients (LTR) who were followed prospectively from the time of transplant using a novel assay. At the time of surveillance bronchoscopy, CMV-specific CD8(+) T-cell responses were assessed in the peripheral blood, using the QuantiFERON-CMV assay, which measures IFN-gamma-secreting T cells following stimulation with CMV peptides. In total, 297 samples were collected from 39 LTR (CMV D+/R-, n = 8; D+/R+, n = 18; D-/R+, n = 6; D-/R-, n = 7). CMV-specific T-cell immunity was not detected in any of the CMV D-/R- LTR. In CMV seropositive LTR levels of CMV immunity were lowest early posttransplant and increased thereafter. While levels of CMV-specific immunity varied between LTR, measurements at any one time point did not predict episodes of CMV reactivation. In CMV mismatched (D+/R-) LTR, primary CMV immunity was not observed during the period of antiviral prophylaxis, but typically developed during episodes of CMV reactivation. Measuring CMV-specific CD8(+) T-cell function with the QuantiFERON-CMV assay provides insights into the interrelationship between CMV immunity and CMV reactivation in individual LTR. A better understanding of these dynamics may allow the opportunity to individualize antiviral prophylaxis in the future.

A 'dangerous' group O donor: severe hemolysis in all recipients of organs from a donor with multiple red cell alloantibodies.

Alloimmune hemolysis is a recognized but infrequent complication of solid organ transplantation, particularly where there is incompatibility within the ABO blood group system. We describe severe hemolysis due to passenger lymphocyte syndrome (PLS) in all three recipients of organs from a single donor with multiple red cell (RC) alloantibodies. The first patient, a liver transplant recipient, required augmentation of immunosuppression to treat immune hemolysis due to anti-B, -D, -C and -Cellano (k). This is the first description of PLS caused by alloantibody to the high incidence RC antigen, k. The two single lung transplant recipients developed hemolysis due to anti-D. Both required escalation of immunosuppression and early transfusion support. Three months posttransplant, all three patients have ongoing evidence of compensated hemolysis. This series highlights the potential for severe non-ABO-mediated immune hemolysis following solid organ transplantation. A positive donor RC antibody screen should prompt careful monitoring of organ recipients for hemolysis.