Cytomegalovirus serologic status and postoperative infection correlated with risk of developing chronic rejection after pulmonary transplantation

Antiviral medications for preventing cytomegalovirus disease in solid organ transplant recipients

BACKGROUND

The risk of cytomegalovirus (CMV) infection in solid organ transplant recipients has resulted in the frequent use of prophylaxis to prevent the clinical syndrome associated with CMV infection. This is an update of a review first published in 2005 and updated in 2008 and 2013.

OBJECTIVES

To determine the benefits and harms of antiviral medications to prevent CMV disease and all-cause death in solid organ transplant recipients.

SEARCH METHODS

We contacted the information specialist and searched the Cochrane Kidney and Transplant Register of Studies up to 5 February 2024 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs comparing antiviral medications with placebo or no treatment, comparing different antiviral medications or different regimens of the same antiviral medications for CMV prophylaxis in recipients of any solid organ transplant. Studies examining pre-emptive therapy for CMV infection are studied in a separate review and were excluded from this review.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study eligibility, risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

This 2024 update found four new studies, bringing the total number of included studies to 41 (5054 participants). The risk of bias was high or unclear across most studies, with a low risk of bias for sequence generation (12), allocation concealment (12), blinding (11) and selective outcome reporting (9) in fewer studies. There is high-certainty evidence that prophylaxis with aciclovir, ganciclovir or valaciclovir compared with placebo or no treatment is more effective in preventing CMV disease (19 studies: RR 0.42, 95% CI 0.34 to 0.52), all-cause death (17 studies: RR 0.63, 95% CI 0.43 to 0.92), and CMV infection (17 studies: RR 0.61, 95% CI 0.48 to 0.77). There is moderate-certainty evidence that prophylaxis probably reduces death from CMV disease (7 studies: RR 0.26, 95% CI 0.08 to 0.78). Prophylaxis reduces the risk of herpes simplex and herpes zoster disease, bacterial and protozoal infections but probably makes little to no difference to fungal infection, acute rejection or graft loss. No apparent differences in adverse events with aciclovir, ganciclovir or valaciclovir compared with placebo or no treatment were found. There is high certainty evidence that ganciclovir, when compared with aciclovir, is more effective in preventing CMV disease (7 studies: RR 0.37, 95% CI 0.23 to 0.60). There may be little to no difference in any outcome between valganciclovir and IV ganciclovir compared with oral ganciclovir (low certainty evidence). The efficacy and adverse effects of valganciclovir or ganciclovir were probably no different to valaciclovir in three studies (moderate certainty evidence). There is moderate certainty evidence that extended duration prophylaxis probably reduces the risk of CMV disease compared with three months of therapy (2 studies: RR 0.20, 95% CI 0.12 to 0.35), with probably little to no difference in rates of adverse events. Low certainty evidence suggests that 450 mg/day valganciclovir compared with 900 mg/day valganciclovir results in little to no difference in all-cause death, CMV infection, acute rejection, and graft loss (no information on adverse events). Maribavir may increase CMV infection compared with ganciclovir (1 study: RR 1.34, 95% CI: 1.10 to 1.65; moderate certainty evidence); however, little to no difference between the two treatments were found for CMV disease, all-cause death, acute rejection, and adverse events at six months (low certainty evidence).

AUTHORS' CONCLUSIONS

Prophylaxis with antiviral medications reduces CMV disease and CMV-associated death, compared with placebo or no treatment, in solid organ transplant recipients. These data support the continued routine use of antiviral prophylaxis in CMV-positive recipients and CMV-negative recipients of CMV-positive organ transplants.

Inferior outcomes in lung transplant recipients with serum Pseudomonas aeruginosa specific cloaking antibodies

BACKGROUND

Chronic Lung Allograft Dysfunction (CLAD) limits long-term survival following lung transplantation. Colonization of the allograft by Pseudomonas aeruginosa is associated with an increased risk of CLAD and inferior overall survival. Recent experimental data suggests that 'cloaking' antibodies targeting the O-antigen of the P. aeruginosa lipopolysaccharide cell wall (cAbs) attenuate complement-mediated bacteriolysis in suppurative lung disease.

METHODS

In this retrospective cohort analysis of 123 lung transplant recipients, we evaluated the prevalence, risk factors and clinical impact of serum cAbs following transplantation.

RESULTS

cAbs were detected in the sera of 40.7% of lung transplant recipients. Cystic fibrosis and younger age were associated with increased risk of serum cAbs (CF diagnosis, OR 6.62, 95% CI 2.83-15.46, p < .001; age at transplant, OR 0.69, 95% CI 0.59-0.81, p < .001). Serum cAbs and CMV mismatch were both independently associated with increased risk of CLAD (cAb, HR 4.34, 95% CI 1.91-9.83, p < .001; CMV mismatch (D+/R-), HR 5.40, 95% CI 2.36-12.32, p < .001) and all-cause mortality (cAb, HR 2.75, 95% CI 1.27-5.95, p = .010, CMV mismatch, HR 3.53, 95% CI 1.62-7.70, p = .002) in multivariable regression analyses.

CONCLUSIONS

Taken together, these findings suggest a potential role for 'cloaking' antibodies targeting P. aeruginosa LPS O-antigen in the immunopathogenesis of CLAD.

Role of CMV chemokine receptor M33 in airway graft rejection in a mouse transplant model

BACKGROUND

Cytomegalovirus (CMV) infection is a risk factor for bronchiolitis obliterans (BO), one form of chronic lung allograft dysfunction (CLAD). The viral chemokine receptor M33 is essential for successful spread of murine CMV to host salivary glands. In the present study we investigated the impact of M33 on chronic airway rejection.

METHODS

MHC I-mismatched tracheas of C·B10-H2^b/LilMcdJ mice were transplanted into BALB/c (H2^d) recipients and infected at different dates with wild type (WT) or M33-deleted (delM33) MCMV representing clinical settings of viral recipient (R)-donor (D)-serostatus: (D-/R+) or (D+/R-). Grafts were recovered for gene expression and histological / immunofluorescence analysis, respectively.

RESULTS

Evaluations showed significantly increased signs of chronic rejection in WT-infected mice compared to uninfected allografts seen in lower epithelium/lamina propria-ratio (ELR) (ELR 0.46 ± 0.07 [WT post] vs. ELR 0.66 ± 0.10 [non-inf.]; p < 0.05). The rejection in delM33-infected groups was significantly reduced vs. WT-infected groups (0.67 ± 0.04 [delM33 post]; vs. WT post p < 0.05). Furthermore, decreased rejection was observed in WT pre-infected compared to post-infected groups (0.56 ± 0.08 [WT pre]; vs. WT post p < 0.05). CD8⁺ T cell infiltration was significantly higher in WT-post compared to the delM33 infected or non-infected allografts.

CONCLUSIONS

These data support the role of the CMV in accelerating CLAD. The deletion of chemokine receptor M33 leads to attenuated rejection.

Chronic Lung Allograft Dysfunction: Evolving Concepts and Therapies

The primary factor that limits long-term survival after lung transplantation is chronic lung allograft dysfunction (CLAD). CLAD also impairs quality of life and increases the costs of medical care. Our understanding of CLAD continues to evolve. Consensus definitions of CLAD and the major CLAD phenotypes were recently updated and clarified, but it remains to be seen whether the current definitions will lead to advances in management or impact care. Understanding the potential differences in pathogenesis for each CLAD phenotype may lead to novel therapeutic strategies, including precision medicine. Recognition of CLAD risk factors may lead to earlier interventions to mitigate risk, or to avoid risk factors all together, to prevent the development of CLAD. Unfortunately, currently available therapies for CLAD are usually not effective. However, novel therapeutics aimed at both prevention and treatment are currently under investigation. We provide an overview of the updates to CLAD-related terminology, clinical phenotypes and their diagnosis, natural history, pathogenesis, and potential strategies to treat and prevent CLAD.

Chronic lung allograft dysfunction post-lung transplantation: The era of bronchiolitis obliterans syndrome and restrictive allograft syndrome

Chronic lung allograft dysfunction (CLAD) following lung transplantation limits long-term survival considerably. The main reason for this is a lack of knowledge regarding the pathological condition and the establishment of treatment. The consensus statement from the International Society for Heart and Lung Transplantation on CLAD in 2019 classified CLAD into two main phenotypes: Bronchiolitis obliterans syndrome and restrictive allograft syndrome. Along with this clear classification, further exploration of the mechanisms and the development of appropriate prevention and treatment strategies for each phenotype are desired. In this review, we summarize the new definition of CLAD and update and summarize the existing knowledge on the underlying mechanisms of bronchiolitis obliterans syndrome and restrictive allograft syndrome, which have been elucidated from clinicopathological observations and animal experiments worldwide.

Respiratory Viruses and Other Relevant Viral Infections in the Lung Transplant Recipient

As advances occur in surgical technique, postoperative care, and immunosuppressive therapy, the rate of mortality in the early postoperative period following lung transplantation continues to decline. With the improvements in immediate and early posttransplant mortality, infections and their sequel as well as rejection and chronic allograft dysfunction are increasingly a major cause of posttransplant mortality. This chapter will focus on infections by respiratory viruses and other viral infections relevant to lung transplantation, including data regarding the link between viral infections and allograft dysfunction.

Infection in Organ Transplantation

The prevention, diagnosis, and management of infectious disease in transplantation are major contributors to improved outcomes in organ transplantation. The risk of serious infections in organ recipients is determined by interactions between the patient's epidemiological exposures and net state of immune suppression. In organ recipients, there is a significant incidence of drug toxicity and a propensity for drug interactions with immunosuppressive agents used to maintain graft function. Thus, every effort must be made to establish specific microbiologic diagnoses to optimize therapy. A timeline can be created to develop a differential diagnosis of infection in transplantation based on common patterns of infectious exposures, immunosuppressive management, and antimicrobial prophylaxis. Application of quantitative molecular microbial assays and advanced antimicrobial therapies have advanced care. Pathogen-specific immunity, genetic polymorphisms in immune responses, and dynamic interactions between the microbiome and the risk of infection are beginning to be explored. The role of infection in the stimulation of alloimmune responses awaits further definition. Major hurdles include the shifting worldwide epidemiology of infections, increasing antimicrobial resistance, suboptimal assays for the microbiologic screening of organ donors, and virus-associated malignancies. Transplant infectious disease remains a key to the clinical and scientific investigation of organ transplantation.

Adoptive T-cell immunotherapy for ganciclovir-resistant CMV disease after lung transplantation

Infections with cytomegalovirus (CMV) can induce severe complications after solid organ transplantation (SOT). The prognosis for ganciclovir-resistant CMV infection and disease is particularly poor. Whereas adoptive transfer of CMV-specific T cells has emerged as a powerful tool in hematopoietic stem cell transplant patients, its translation into the SOT setting remains a significant challenge as underlying immunosuppression inhibits the virus-specific T-cell response in vivo. Here, we demonstrate successful expansion and adoptive transfer of autologous CMV-specific T cells from a seronegative recipient of a seropositive lung allograft with ganciclovir-resistant CMV disease, resulting in the long-term reconstitution of protective anti-viral immunity, CMV infection, disease-free survival and no allograft rejection.

An international ISHLT/ATS/ERS clinical practice guideline: diagnosis and management of bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS) is a major complication of lung transplantation that is associated with poor survival. The International Society for Heart and Lung Transplantation, American Thoracic Society, and European Respiratory Society convened a committee of international experts to describe and/or provide recommendations for 1) the definition of BOS, 2) the risk factors for developing BOS, 3) the diagnosis of BOS, and 4) the management and prevention of BOS. A pragmatic evidence synthesis was performed to identify all unique citations related to BOS published from 1980 through to March, 2013. The expert committee discussed the available research evidence upon which the updated definition of BOS, identified risk factors and recommendations are based. The committee followed the GRADE (Grading of Recommendation, Assessment, Development and Evaluation) approach to develop specific clinical recommendations. The term BOS should be used to describe a delayed allograft dysfunction with persistent decline in forced expiratory volume in 1 s that is not caused by other known and potentially reversible causes of post-transplant loss of lung function. The committee formulated specific recommendations about the use of systemic corticosteroids, cyclosporine, tacrolimus, azithromycin and about re-transplantation in patients with suspected and confirmed BOS. The diagnosis of BOS requires the careful exclusion of other post-transplant complications that can cause delayed lung allograft dysfunction, and several risk factors have been identified that have a significant association with the onset of BOS. Currently available therapies have not been proven to result in significant benefit in the prevention or treatment of BOS. Adequately designed and executed randomised controlled trials that properly measure and report all patient-important outcomes are needed to identify optimal therapies for established BOS and effective strategies for its prevention.

Bronchiolitis obliterans syndrome: the Achilles' heel of lung transplantation

Lung transplantation is a therapeutic option for patients with end-stage pulmonary disorders. Unfortunately, chronic lung allograft dysfunction (CLAD), most commonly manifest as bronchiolitis obliterans syndrome (BOS), continues to be highly prevalent and is the major limitation to long-term survival. The pathogenesis of BOS is complex and involves alloimmune and nonalloimmune pathways. Clinically, BOS manifests as airway obstruction and dyspnea that are classically progressive and ultimately fatal; however, the course is highly variable, and distinguishable phenotypes may exist. There are few controlled studies assessing treatment efficacy, but only a minority of patients respond to current treatment modalities. Ultimately, preventive strategies may prove more effective at prolonging survival after lung transplantation, but their remains considerable debate and little data regarding the best strategies to prevent BOS. A better understanding of the risk factors and their relationship to the pathological mechanisms of chronic lung allograft rejection should lead to better pharmacological targets to prevent or treat this syndrome.

Antiviral medications for preventing cytomegalovirus disease in solid organ transplant recipients

BACKGROUND

The risk of cytomegalovirus (CMV) infection in solid organ transplant recipients has resulted in the frequent use of prophylaxis with the aim of preventing the clinical syndrome associated with CMV infection. This is an update of a review first published in 2005 and updated in 2008.

OBJECTIVES

To determine the benefits and harms of antiviral medications to prevent CMV disease and all-cause mortality in solid organ transplant recipients.

SEARCH METHODS

We searched MEDLINE, EMBASE and the Cochrane Central Registry of Controlled Trials (CENTRAL) in The Cochrane Library to February 2004 for the first version of this review. The Cochrane Renal Group's specialised register was searched to February 2007 and to July 2011 for the first and current updates of the review without language restriction.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs comparing antiviral medications with placebo or no treatment, comparing different antiviral medications and comparing different regimens of the same antiviral medications in recipients of any solid organ transplant. Studies examining pre-emptive therapy were excluded.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study eligibility, risk of bias and extracted data. Results were reported as risk ratios (RR) or risk differences (RD) with 95% confidence intervals (CI) for dichotomous outcomes and by mean difference (MD) with 95% CI for continuous outcomes. Statistical analyses were performed using the random-effects model. Subgroup analysis and univariate meta-regression were performed using restricted maximum-likelihood to estimate the between study variance. Multivariate meta-regression was performed to investigate whether the results were altered after allowing for differences in drugs used, organ transplanted, and recipient CMV serostatus at the time of transplantation.

MAIN RESULTS

We identified 37 studies (4342 participants). Risk of bias attributes were poorly performed or reported with low risk of bias reported for sequence generation, allocation concealment, blinding and selective outcome reporting in 25% or fewer studies.Prophylaxis with aciclovir, ganciclovir or valaciclovir compared with placebo or no treatment significantly reduced the risk for CMV disease (19 studies; RR 0.42, 95% CI 0.34 to 0.52), CMV infection (17 studies; RR 0.61, 95% CI 0.48 to 0.77), and all-cause mortality (17 studies; RR 0.63, 95% CI 0.43 to 0.92) primarily due to reduced mortality from CMV disease (7 studies; RR 0.26, 95% CI 0.08 to 0.78). Prophylaxis reduced the risk of herpes simplex and herpes zoster disease, bacterial and protozoal infections but not fungal infection, acute rejection or graft loss.Meta-regression showed no significant difference in the relative benefit of treatment (risk of CMV disease or all-cause mortality) by organ transplanted or CMV serostatus; no conclusions were possible for CMV negative recipients of negative organs.Neurological dysfunction was more common with ganciclovir and valaciclovir compared with placebo/no treatment. In direct comparison studies, ganciclovir was more effective than aciclovir in preventing CMV disease (7 studies; RR 0.37, 95% CI 0.23 to 0.60) and leucopenia was more common with aciclovir. Valganciclovir and IV ganciclovir were as effective as oral ganciclovir. The efficacy and adverse effects of valganciclovir/ganciclovir did not differ from valaciclovir in three small studies. Extended duration prophylaxis significantly reduced the risk of CMV disease compared with three months therapy (2 studies; RR 0.20, 95% CI 0.12 to 0.35). Leucopenia was more common with extended duration prophylaxis but severe treatment associated adverse effects did not differ between extended and three month durations of treatment.

AUTHORS' CONCLUSIONS

Prophylaxis with antiviral medications reduces CMV disease and CMV-associated mortality in solid organ transplant recipients. These data suggest that antiviral prophylaxis should be used routinely in CMV positive recipients and in CMV negative recipients of CMV positive organ transplants.

Bronchiolitis Obliterans Syndrome and Chronic Lung Allograft Dysfunction: Evolving Concepts and Nomenclature

Bronchiolitis obliterans syndrome (BOS) eventually occurs in the majority of lung transplant recipients who survive beyond 1 year, can greatly impair quality of life, and is, directly or indirectly, the major cause of delayed allograft dysfunction and recipient death. A number of associated events or conditions are strongly associated with the risk for developing BOS; these include acute rejection, gastroesophageal reflux, infections, and autoimmune reactions that can occur in the setting of alloimmune responses to the lung allograft as recipients are given intense immunosuppression to prevent allograft rejection. The term chronic lung allograft dysfunction (CLAD) is being increasingly used to refer to recipients with late allograft dysfunction that meets the spirometric criteria for the diagnosis of BOS, but clinicians should recognize that such dysfunction can occur for a variety of reasons other than BOS. The recently identified entity of restrictive allograft syndrome, which is now recognized as a relatively distinct phenotype of CLAD, has features that differentiate it from classic obstructive BOS. A number of other entities that can also significantly affect allograft function must also be considered when significant allograft dysfunction is encountered following lung transplantation.

The Role of Infections in BOS

Background: Infectious agents, particularly cytomegalovirus (CMV), have long been considered to be potential triggers for BOS, although the exact magnitude of the role of infections and the mechanisms thereof remain an area of active research. Methods: This chapter will review previous literature and newer results concerning the possible roles of CMV, other herpesviruses, community-acquired respiratory viruses, bacteria (including Pseudomonas, other gram-negative, gram-positive, and atypical organisms), and fungi, including colonization as well as invasive infection. Results: The text reviews and evaluates the body of literature supporting a role for these infectious agents as risk factors for BOS and time to BOS. Changing patterns of infection over time are taken into account, and studies that have shown an association between BOS (or lack thereof) and CMV are reviewed. Strategies for prevention or early treatment of infections are discussed as potential means of preserving allograft function long term. Immunizations, stringent infection-control practices, and antimicrobial treatment including newer therapies will be discussed. Conclusion: In addition to the classic literature that has focused on CMV, an expanding spectrum of infectious organisms has been implicated as possible risk factors for BOS. Increasing knowledge of the impact of long-term antiviral suppression, prophylaxis, and outcomes of early therapy will help guide future recipient management.

A review of bronchiolitis obliterans syndrome and therapeutic strategies

Lung transplantation is an important treatment option for patients with advanced lung disease. Survival rates for lung transplant recipients have improved; however, the major obstacle limiting better survival is bronchiolitis obliterans syndrome (BOS). In the last decade, survival after lung retransplantation has improved for transplant recipients with BOS. This manuscript reviews BOS along with the current therapeutic strategies, including recent outcomes for lung retransplantation.

Non-tuberculous mycobacterium infection after lung transplantation is associated with increased mortality

BACKGROUND

Pulmonary non-tuberculous mycobacterial (NTM) infection is relatively common after lung transplantation, but the effect on mortality remains undetermined. Herein we describe our experience with pulmonary NTM infection after lung transplantation and hypothesized that non-tuberculous mycobacterial infection after lung transplantation would be associated with increased mortality.

METHODS

We retrospectively evaluated 201 primary lung transplant recipients transplanted between January 2000 and August 2006. Serial bronchoscopies with bronchoalveolar lavage and transbronchial biopsy were performed according to a surveillance protocol and when clinically indicated. The diagnosis NTM infection was established by a positive NTM culture in a bronchoalveolar lavage sample or in at least two separate expectorated sputum samples. NTM infections were further classified as "disease" or "colonization," based on whether or not NTM infection patients developed symptoms and characteristic radiographic findings.

RESULTS

Thirty-six (18%) recipients were diagnosed with pulmonary NTM infection at a median of 97 days post-transplantation: 9 were classified as NTM disease and the remaining 27 as NTM colonization cases. Single lung transplant was a significant risk factor for NTM infection (HR 2.25, p = 0.02). NTM colonization was a risk factor for NTM disease (HR 8.39, p = 0.003). NTM infection significantly increased the risk of death after lung transplantation (HR 2.61, p = 0.001) and persisted in multivariate models controlling for single lung transplant and bronchiolitis obliterans syndrome. The increased risk was seen for both NTM colonization and NTM disease. Among the patients who died, non-NTM infection was a more common contributing factor in the cause of death for the NTM infection group (44% vs 12%, p = 0.04).

CONCLUSIONS

Non-tuberculous mycobacterial infection is common after lung transplantation. NTM colonization and treated acute rejection are risk factors for NTM disease. NTM infection is associated with increased risk of mortality independent of bronchiolitis obliterans syndrome.

Prevalence and clinical impact of polyomaviruses KI and WU in lung transplant recipients

The newly discovered polyomaviruses KI and WU (KIV and WUV) were isolated from secretions of patients with respiratory symptoms as well as in blood, spleen, lymphoid tissues, and stools, especially in immunocompromised conditions. The aim of this work was to evaluate the prevalence of KIV and WUV in bronchoalveolar lavage (BAL) from lung transplant recipients. We also examined potential correlations between these viruses and occurrences of pneumonia, acute respiratory insufficiency, or other acute respiratory conditions and acute rejection episodes. Discharge diagnosis was based on the International Classification of Diseases-Italian version 2002, based on the 9th-revision clinical modification. A rejection episode was diagnosed by transbronchial lung biopsy in accordance with the 2007 International Society for Heart and Lung Transplantation Working Formulation. Overall, we analyzed 53 BALs obtained from 24 transplant recipients. Positive polymerase chain reaction results were observed in 6 samples (11.3%) from 6 patients (25%), versus 7 samples (13.2%) from 7 patients (29.2%) for KIV and WUV, respectively. Regarding the diagnosis of pneumonia, the prevalence was 22.2% and 33.3% for KIV and WUV, respectively. In cases of acute respiratory insufficiency or other acute respiratory conditions, 2 out of 9 samples were positive for KIV (22.2%) and 4 out of 9 for WUV (44.4%). An Acute rejection episode (ARE) was diagnosed in 7 instances among 6 lung transplant patients: The corresponding BAL specimens showed positive results for KIV in 3 out of 7 (42.8%) cases with ARE vs 3 out of 46 (6.5%) without an ARE (P < .05), and for WUV in 3 out of 7 (42.8%) vs 4 out of 46 (8.7%) (P < .05), respectively. Although the small number of specimens limits the statistical analysis, our results showed a higher prevalence of WUV compared with KIV. The compromised pulmonary environment in the lung allograft may cause reactivation of these viruses. Their roles in this context need to be further evaluated.

Viral infections in lung transplant recipients

Viral infections, including beta-herpes viruses and community respiratory viruses, are frequent pathogens in lung transplant recipients. These pathogens have become increasingly recognized as having a significant role in long-term outcomes of lung transplantation, which has been limited by the frequent development of infections, and chronic allograft dysfunction. Community respiratory viruses, such as influenza and respiratory syncytial virus have been associated with both acute rejection and chronic allograft dysfunction, particularly if early treatment was not administered. beta-herpes viruses, particularly cytomegalovirus (CMV), have long been associated with increased mortality in lung transplant recipients, although the advent of effective antiviral strategies has led to improved morbidity and mortality. Because these pathogens have been associated with altered immune responses against the allograft, a better understanding of immunopathogenesis of viral infections may lead to a broader approach to limit the morbidity from these pathogens.

Aspergillus colonization of the lung allograft is a risk factor for bronchiolitis obliterans syndrome

Multiple infections have been linked with the development of bronchiolitis obliterans syndrome (BOS) post-lung transplantation. Lung allograft airway colonization by Aspergillus species is common among lung transplant recipients. We hypothesized that Aspergillus colonization may promote the development of BOS and may decrease survival post-lung transplantation. We reviewed all lung transplant recipients transplanted in our center between January 2000 and June 2006. Bronchoscopy was performed according to a surveillance protocol and when clinically indicated. Aspergillus colonization was defined as a positive culture from bronchoalveolar lavage or two sputum cultures positive for the same Aspergillus species, in the absence of invasive pulmonary Aspergillosis. We found that Aspergillus colonization was strongly associated with BOS and BOS related mortality in Cox regression analyses. Aspergillus colonization typically preceded the development of BOS by a median of 261 days (95% CI 87-520). Furthermore, in a multivariate Cox regression model, Aspergillus colonization was a distinct risk factor for BOS, independent of acute rejection. These data suggest a potential causative role for Aspergillus colonization in the development of BOS post-lung transplantation and raise the possibility that strategies aimed to prevent Aspergillus colonization may help delay or reduce the incidence of BOS.

Antiviral medications for preventing cytomegalovirus disease in solid organ transplant recipients

BACKGROUND

The risk of cytomegalovirus (CMV) infection in solid organ transplant recipients has resulted in the frequent use of prophylaxis with the aim of preventing the clinical syndrome associated with CMV infection.

OBJECTIVES

To determine the benefits and harms of antiviral medications to prevent CMV disease and all-cause mortality in solid organ transplant recipients.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, reference lists and abstracts from conference proceedings without language restriction. Date of last search: February 2007

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs comparing antiviral medications with placebo or no treatment, comparing different antiviral medications and comparing different regimens of the same antiviral medications in recipients of any solid organ transplant.

DATA COLLECTION AND ANALYSIS

Statistical analyses were performed using the random effects model and results expressed as relative risk (RR) for dichotomous outcomes with 95% confidence intervals (CI). Subgroup analysis and univariate meta-regression were performed using restricted maximum-likelihood to estimate the between study variance. Multivariate meta-regression was performed to investigate whether the results were altered after allowing for differences in drugs used, organ transplanted and recipient CMV serostatus at the time of transplantation.

MAIN RESULTS

Thirty four studies (3850 participants) were identified. Prophylaxis with aciclovir, ganciclovir or valaciclovir compared with placebo or no treatment significantly reduced the risk for CMV disease (19 studies; RR 0.42, 95% CI 0.34 to 0.52), CMV infection (17 studies; RR 0.61, 95% CI 0.48 to 0.77), and all-cause mortality (17 studies; RR 0.63, 95% CI 0.43 to 0.92) primarily due to reduced mortality from CMV disease (7 studies; RR 0.26, 95% CI 0.08 to 0.78). Prophylaxis reduced the risk of herpes simplex and herpes zoster disease, bacterial and protozoal infections but not fungal infection, acute rejection or graft loss. Meta-regression showed no significant difference in the relative benefit of treatment (risk of CMV disease or all-cause mortality) by organ transplanted or CMV serostatus; no conclusions were possible for CMV negative recipients of negative organs. In direct comparison studies, ganciclovir was more effective than aciclovir in preventing CMV disease (7 studies; RR 0.37, 95% CI 0.23 to 0.60). Valganciclovir and IV ganciclovir were as effective as oral ganciclovir.

AUTHORS' CONCLUSIONS

Prophylaxis with antiviral medications reduces CMV disease and CMV-associated mortality in solid organ transplant recipients. They should be used routinely in CMV positive recipients and in CMV negative recipients of CMV positive organ transplants.

Postlung Transplant Survival is Equivalent Regardless of Cytomegalovirus Match Status

BACKGROUND

The purpose of this study was to assess (1) the relationship between donor-recipient cytomegalovirus (CMV) serologic status and posttransplant survival in the current era and (2) temporal changes in posttransplant survival by CMV matching status.

METHODS

De-identified data were obtained from the United Network for Organ Sharing. Based on pretransplant CMV serologic status (+ or -) of recipients (R) and donors (D), posttransplant survival was compared among three groups: D+ /R-, D+/- /R+, and D- /R-. Primary analysis focused on transplants performed January 1, 2000 to December 31, 2004, in recipients 18 years of age or older. To assess temporal trends in survival among groups, all lung transplants occurring between January 1, 1990, and December 31, 2004, were considered and divided into three periods based on transplant year: 1990 through 1994, 1995 through 1999, and 2000 through 2004. The primary outcome measure was survival, reported as rate of death per 100 patient-years. Kaplan-Meier analysis with log-rank test was used for time-to-event analysis.

RESULTS

During the current era (2000 through 2004), D+ /R- (n = 951), D+/- /R+ (n = 2,676), and D- /R- (n = 772) exhibited no differences in survival (p = 0.561), with rates of death per 100 patient-years of 16.6 (95% confidence interval, 14.9 to 18.5), 15.0 (95% confidence interval, 14.0 to 16.0), and 14.7 (95% confidence interval, 13.0 to 16.6), respectively. However, survival was significantly different for groups in the earlier eras of 1990 through 1994 (p < 0.001) and 1995 through 1999 (p < 0.001). During the three periods, survival improved significantly in D+ /R- (p < 0.001) and D+/- /R+ (p < 0.001), but survival in D- /R- (p = 0.351) did not change significantly with time.

CONCLUSIONS

In the current era, survival after lung transplantation is statistically equivalent regardless of CMV match status. Although in previous eras survival was worse among the D+/- /R+ and D+ /R- groups, in this era of aggressive CMV prophylaxis, CMV mismatch should not be sufficient grounds to decline a lung allograft offer.

Immunoglobulins, vaccines or interferon for preventing cytomegalovirus disease in solid organ transplant recipients

BACKGROUND

Cytomegalovirus (CMV) is the most common virus causing disease and death in solid organ transplant recipients during the first six months post-transplant. Previous systematic reviews have demonstrated the efficacy of antiviral medications used prophylactically or pre-emptively in preventing CMV disease. In this review the efficacy of older agents (immunoglobulins (IgG), anti CMV vaccines and interferon) are examined.

OBJECTIVES

To assess the benefits and harms of IgG, anti CMV vaccines or interferon for preventing symptomatic CMV disease in solid organ transplant recipients.

SEARCH STRATEGY

We searched the Cochrane Renal Group's Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL, in The Cochrane Library), MEDLINE, EMBASE, reference lists and abstracts from conference proceedings without language restriction. Date of last search: December 2005

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing IgG, anti CMV vaccine or interferon with placebo or no treatment, IgG alone or combined with antiviral medications with antiviral medications or IgG alone in recipients of any solid organ transplant.

DATA COLLECTION AND ANALYSIS

Two of four authors independently assessed trial quality and extracted data from each trial. Statistical analyses were performed using the random effects model and results expressed as relative risk (RR) for dichotomous outcomes with 95% confidence intervals (CI).

MAIN RESULTS

Thirty seven trials (2185 participants) were included in this review. There was no significant difference in the risk for CMV disease (16 trials, 770 patients: RR 0.80, 95% CI 0.61 to 1.05), CMV infection (14 trials, 775 patients: RR 0.94, 95% CI 0.80 to 1.10) or all-cause mortality (8 trials, 502 patients: RR 0.57, 95% CI 0.32 to 1.03) with IgG compared with placebo/no treatment. However IgG significantly reduced the risk of death from CMV disease (6 trials, 346 patients: RR 0.33, 95% CI 0.14 to 0.80). There was no difference in the risk for CMV disease (4 trials, 298 patients: RR 1.17, 95% CI 0.74 to 1.86), CMV infection (4 trials, 298 patients: RR 1.16, 95% CI 0.89 to 1.52) or all-cause mortality (2 trials, 217 patients: RR 0.92, 95% CI 0.37 to 2.29) between antiviral medication combined with IgG and antiviral medication alone. There was no significant difference in the risk of CMV disease with anti CMV vaccine or interferon compared with placebo or no treatment.

AUTHORS' CONCLUSIONS

Currently there are no indications for IgG in the prophylaxis of CMV disease in recipients of solid organ transplants.

Improved Survival Following Lung Transplantation with Long-Term Use Of Bilevel Positive Pressure Ventilation in Cystic Fibrosis

Bilevel positive airway pressure ventilation (BIPAP) has been used in cystic fibrosis (CF) patients as a bridge to transplantation. Our aim was to evaluate the effect of BIPAP use before transplantation on post-transplantation morbidity and mortality. We performed a retrospective study at a tertiary care center. Twelve CF patients (9 males; mean age = 26 years) were assessed. Group 1 consisted of eight patients that did not use BIPAP before lung transplantation. Group 2 comprised four patients who used BIPAP for 3-15 months while awaiting transplantation. Patients were evaluated before and two to ten years after transplantation. All eight patients who did not use BIPAP died two months to ten years after transplantation. All four BIPAP users are alive with no evidence of bronchiolitis obliterans two to eight years after lung transplantation. We demonstrated a significant improvement in acid-base balance (p < 0.01) and body mass index (p < 0.05) and a tendency toward improvement in the work of breathing and number of hospitalizations. We conclude that improvement in nutritional status and respiratory muscle strength before lung transplantation in BIPAP users may prevent post lung transplantation infection and acute rejection rate, which in turn may reduce chronic rejection (bronchiolitis obliterans) and improve long-term survival after lung transplantation.

Bronchiolitis obliterans following lung transplantation

Bronchiolitis obliterans syndrome (BOS) is the main and late chronic complication after lung transplantation. It remains a major impediment to long-term outcome. Unfortunately, the survival rate of lung transplant recipients lags behind that of other organ transplant recipients, and BOS accounts for more than 30% of all mortality after the third year following lung transplantation. Most recent studies suggest that immune injury is the main pathogenic event in small airway obliteration and the development of BOS. Early detection of BOS is possible as well as essential because prompt initiation of treatment may halt the progress of the disease and the development of chronic graft failure. Current treatment of BOS is disappointing despite advances in surgical techniques and improvements in immunosuppressive therapies. Therefore, a clear understanding of the pathogenesis of BOS plays a major role in the search for new and effective therapeutic strategies for better long-term survival and quality of life after lung transplantation.

Role of airway epithelial injury in murine orthotopic tracheal allograft rejection

BACKGROUND

Murine tracheal transplantation is a model used to study bronchiolitis obliterans syndrome, a major cause of morbidity and mortality after lung transplantation. Unlike murine heterotopic tracheal transplants, orthotopic transplantation does not cause luminal obliteration despite major histocompatibility antigen mismatch. Repopulation of the tracheal allografts with recipient-derived epithelium confers protection against luminal obliteration. The purpose of this study was to determine whether (1) orthotopic tracheal transplantation showed signs of allograft rejection, and (2) airway epithelial cell injury promoted orthotopic tracheal allograft rejection.

METHODS

Forty isogeneic (C57BL/6 to C57BL/6) and 40 allogeneic (BALB/c to C57BL/6) orthotopic tracheal transplants were performed. Damage to airway epithelial cells was induced by Sendai viral (SdV) infection and tracheal transplantation into non-reepithelializing matrix metalloproteinase-7 knockout (MMP7-KO) recipient mice. Percent fibrosis and lamina propria to cartilage ratio were calculated with computer assistance on harvested allografts.

RESULTS

Allografts showed significantly more intramural fibrosis compared with isografts at 30, 60, and 180 days after transplant without luminal occlusion. Tracheal allografts infected with SdV showed an increase in fibrosis and lamina propria to cartilage ratio compared with noninfected controls. Allografts retrieved from MMP7-KO recipients also showed a significant increase in fibrosis and lamina propria to cartilage ratio.

CONCLUSIONS

Although orthotopic tracheal transplantation does not cause luminal obliteration, it results in increased fibrosis in allografts. Damage to the respiratory epithelium by viral infection or defective reepithelialization after transplant as seen in MMP7-KO recipient mice leads to changes consistent with chronic allograft rejection, suggesting a role for epithelial injury in bronchiolitis obliterans syndrome development.

Antiviral medications for preventing cytomegalovirus disease in solid organ transplant recipients

BACKGROUND

The risk of cytomegalovirus (CMV) infection in solid organ transplant recipients has resulted in the frequent use of prophylaxis with the aim of preventing the clinical syndrome associated with CMV infection.

OBJECTIVES

To determine the benefits and harms of antiviral medications to prevent CMV disease and all-cause mortality in solid organ transplant recipients.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, reference lists and abstracts from conference proceedings without language restriction.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing antiviral medications with placebo or no treatment, trials comparing different antiviral medications and trials comparing different regimens of the same antiviral medications in recipients of any solid organ transplant.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data from each trial. Statistical analyses were performed using the random effects model and results expressed as relative risk (RR) for dichotomous outcomes with 95% confidence intervals (CI). Subgroup analysis and univariate meta-regression were performed using restricted maximum-likelihood to estimate the between study variance. Multivariate meta-regression was performed to investigate whether the results were altered after allowing for differences in drugs used, organ transplanted and recipient CMV serostatus at the time of transplantation.

MAIN RESULTS

Thirty two trials (3737 participants) were identified. Prophylaxis with aciclovir, ganciclovir or valaciclovir compared with placebo or no treatment significantly reduced the risk for CMV disease (19 trials; RR 0.42, 95% CI 0.34 to 0.52), CMV infection (17 trials; RR 0.61, 95% CI 0.48 to 0.77), and all-cause mortality (17 trials; RR 0.63, 95% CI 0.43 to 0.92) primarily due to reduced mortality from CMV disease (seven trials; RR 0.26, 95% CI 0.08 to 0.78). Prophylaxis reduced the risk of herpes simplex and herpes zoster disease, bacterial and protozoal infections but not fungal infection, acute rejection or graft loss. Meta-regression showed no significant difference in the risk of CMV disease or all-cause mortality by organ transplanted or CMV serostatus; no conclusions were possible for CMV negative recipients of negative organs. In direct comparison trials, ganciclovir was more effective than aciclovir in preventing CMV disease (seven trials; RR 0.37, 95% Cl 0.23 to 0.60). Valganciclovir and intravenous ganciclovir were as effective as oral ganciclovir.

AUTHORS' CONCLUSIONS

Prophylaxis with antiviral medications reduces CMV disease and CMV-associated mortality in solid organ transplant recipients. They should be used routinely in CMV positive recipients and in CMV negative recipients of CMV positive organ transplants.

Rat cytomegalovirus and Listeria monocytogenes infection enhance chronic rejection after allogenic rat lung transplantation

The role of infection in the pathomechanism of obliterative bronchiolitis (OB) after human lung transplantation is controversial. In a rat lung transplantation model, we analyzed the effect of viral [rat cytomegalovirus (RCMV)] and bacterial infection [Listeria monocytogenes (LM)] on the development of chronic allograft rejection. Fisher rats underwent single left lung transplantation with allografts from Lewis rats. Postoperatively, animals were infected with either RCMV or LM, or served as noninfected controls. Animals were killed on day 120 and both lungs were evaluated histopathologically for chronic airway and chronic vascular rejection. Infection with RCMV produced a significant increase in the incidence of chronic airway rejection (66.7% vs. 20%), compared with noninfected long-term surviving animals. In rats with bacterial infection (LM) a similar increase of chronic airway changes as in viral infection (50% vs. 20%) was observed. Chronic rejection of allografts infected with either RCMV or LM was associated with significantly enhanced expression of intercellular adhesion molecule-1 (ICAM-1) on the endothelium. More infiltrating leukocytes (CD18, CD11a, CD44) and ED1-positive macrophages were found in allografts of infected animals. In this experimental model of chronic airway rejection in long-term surviving rats, not only viral but also bacterial infection resulted in enhanced development of chronic airway and vascular rejection. These results support our hypothesis that infectious complications have a substantial influence on the development of OB in human lung allografts.

J. Maxwell Chamberlain Memorial Paper. Early fundoplication prevents chronic allograft dysfunction in patients with gastroesophageal reflux disease

BACKGROUND

Chronic allograft dysfunction limits the long-term success of lung transplantation. Increasing evidence suggests nonimmune mediated injury such as due to reflux contributes to the development of bronchiolitis obliterans syndrome. We have previously demonstrated that fundoplication can reverse bronchiolitis obliterans syndrome in some lung transplant recipients with reflux. We hypothesized that treatment of reflux with early fundoplication would prevent bronchiolitis obliterans syndrome and improve survival.

METHODS

A retrospective analysis of 457 patients who underwent lung transplantation from April 1992 through July 2003 was conducted. Patients were stratified into four groups: no history of reflux, history of reflux, history of reflux and early (< 90 days) fundoplication and history of reflux and late fundoplication.

RESULTS

Incidence of postoperative reflux was 76% (127 of 167 patients) in pH confirmed subgroups. In 14 patients with early fundoplication, actuarial survival was 100% at 1 and 3 years when compared with those with reflux and no intervention (92% +/- 3.3, 76% +/- 5.8; p < 0.02). Further, those who underwent early fundoplication had improved freedom from bronchiolitis obliterans syndrome at 1 and 3 years (100%, 100%) when compared with no fundoplication in patients with reflux (96% +/- 2.5, 60% +/- 7.5; p < 0.01).

CONCLUSIONS

Reflux is a frequent medical complication after lung transplantation. Although the number of patients undergoing early fundoplication is small, our results suggest early aggressive surgical treatment of reflux results in improved rates of bronchiolitis obliterans syndrome and survival. Further research into the mechanisms and treatment of nonalloimmune mediated lung allograft injury is needed to reduce rates of chronic lung failure.

Viral prophylaxis in organ transplant patients

Viral pathogens have emerged as the most important microbial agents having deleterious effects on solid organ transplant (SOT) recipients. Antiviral chemoprophylaxis involves the administration of medications to abort transmission of, avoid reactivation of, or prevent progression to disease from, active viral infection. Cytomegalovirus (CMV) is the major microbial pathogen having a negative effect on SOT recipients. CMV causes infectious disease syndromes, augments iatrogenic immunosuppression and is commonly associated with opportunistic superinfection. CMV has also been implicated in the pathogenesis of rejection. Chemoprophylactic regimens for CMV have included oral aciclovir (acyclovir) at medium and high doses, intravenous and oral ganciclovir, and the prodrugs valaciclovir (valacyclovir) and valganciclovir. CMV prophylactic strategies should be stratified, with the highest-risk patients receiving the most 'potent' prophylactic regimens. Herpes simplex virus (HSV) reactivation in SOT recipients is more frequent, may become more invasive, takes longer to heal, and has greater potential for dissemination to visceral organs than it does in the immunocompetent host. Prophylactic regimens for CMV are also effective chemoprophylaxis against HSV; in the absence of CMV prophylaxis, aciclovir, valaciclovir or famciclovir should be used as HSV prophylaxis in seropositive recipients. Primary varicella-zoster virus (VZV) after SOT is rare and most commonly seen in the paediatric transplant population because of VZV epidemiology. Zoster occurs in 5-15% of patients, usually after the sixth post-transplant month. Prophylactic regimens for zoster are neither practical nor cost effective after SOT because of the late onset of disease and low proportion of affected individuals. All SOT recipients should receive VZV immune globulin after contact with either varicella or zoster. Epstein-Barr virus has its most significant effect in SOT as the precipitating factor in the development of post-transplant lymphoproliferative disorders. Antiviral agents that could be effective are the same as those used for CMV, but indications for and effectiveness of prophylaxis are poorly established. Hepatitis B virus (HBV) and hepatitis C virus (HCV) are important pathogens in the SOT population as indications for transplantation. So-called 'prophylaxis' for recurrent HBV and HCV after liver transplantation is controversial, suppressive rather than preventive, and potentially lifelong. Influenza infection after SOT is acquired by person-to-person contact. During epidemic periods of influenza, transplant populations experience a relatively high frequency of infection, and influenza may affect immunosuppressed SOT recipients more adversely than immunocompetent individuals. Antiviral medications for prevention of influenza are administered as post-exposure prophylaxis to SOT recipients, in addition to yearly vaccine, in circumstances such as influenza epidemics and nosocomial outbreaks, and after exposure to a symptomatic individual during 'flu season'.

CMV-infected allogeneic endothelial cells initiate responder and bystander donor HLA class I release via the metalloproteinase cleavage pathway

Although cytomegalovirus (CMV) interferes with major histocompatibility expression in infected cells, both host and donor soluble human leukocyte antigen class I (sHLA-I) are often released into the serum of transplant recipients during CMV infection and may contribute to anti-HLA antibody production and graft rejection. We hypothesized that CMV infection of endothelial cells (EC) induces host T cells to release interferon (IFN)-gamma, which in turn drives the metalloproteinase (MPase)-cleavage pathway of sHLA-I generation in "bystander" uninfected ECs. To test this hypothesis, cultures of peripheral blood mononuclear cells (PBMCs) and either uninfected ECs or CMV-infected ECs (EC/CMV) were established and supernatants were tested in enzyme-linked immunosorbent assay for sHLA-I. Responder PBMC became activated and released sHLA-I via the MPase pathway when stimulated with allogeneic EC/CMV; the sHLA-I release was contact dependent and cytokine independent. In transwell cultures, IFN-gamma released by PBMCs in response to EC/CMV stimulated a release of sHLA-I from uninfected allogeneic ECs across the transwell; this release was also MPase dependent. This implies that CMV infection within the transplanted allograft will not only stimulate the release of self HLA from responding PBMCs, but will also stimulate the release of donor sHLA-I from uninfected bystander ECs, both via the class I MPase-pathway.

Bronchiolitis obliterans syndrome: Pathogenesis and management

Over the past 15 years, lung transplantation has become an established treatment for a variety of end-stage lung diseases, but medium- and long-term success has been limited by a high incidence of bronchiolitis obliterans syndrome (BOS). Immune mediated injury has been recognized as the leading cause of BOS, and the term is synonymous with chronic rejection. But recently, nonimmune mechanisms, such as gastroesophageal reflux, have been recognized as potential culprits. The results of various treatment options have generally been disappointing, and BOS has emerged as the leading cause of late morbidity and mortality after lung transplantation.

Treated Cytomegalovirus Pneumonia Is Not Associated with Bronchiolitis Obliterans Syndrome

The association of cytomegalovirus (CMV) infection with the development of bronchiolitis obliterans syndrome (BOS) is unclear. We studied 341 lung transplant recipients to assess whether histopathologically diagnosed CMV pneumonia treated with ganciclovir was a risk factor for development of BOS and patient survival. We also analyzed the relationship between CMV donor/recipient serologic status and BOS plus the temporal association between acute rejection and CMV pneumonia. Freedom from BOS for patients with (n = 151) and without (n = 190) CMV pneumonia was 83 and 90% (1 year), 52 and 56% (3 years), and 29 and 38% (5 years), respectively (p = 0.2660). Cumulative survival of patients with and without CMV pneumonia was 90 and 93% (1 year), 70 and 74% (3 years), and 58 and 63% (5 years), respectively (p = 0.1811). There were no significant differences in either development of BOS or patient survival with any combination of donor/recipient serostatus for CMV. Acute rejection occurred in the month preceding CMV pneumonia in 62 of 193 (32%) cases. Histopathologically confirmed CMV pneumonia treated with ganciclovir is not a risk factor for BOS or patient survival, nor is any particular CMV serologic donor/recipient group. CMV pneumonia often follows acute rejection, perhaps as a result of augmented immunosuppression.

An overview of paediatric lung transplantation

Paediatric lung transplantation is indicated in selected children with end-stage lung disease that is not amenable to conventional medical or surgical therapy. The indications and complications differ from adult lung transplant patients. Due to the long waiting times for suitable cadaveric lungs, other types of lung transplantation, such as living donor lobar and split-lung procedures, have been utilised in paediatric patients. Unlike adult candidates, cystic fibrosis and primary pulmonary hypertension are the primary indications. Most recipients are in the adolescent age group. Complications that occur with greater frequency in paediatric lung recipients include somatic growth and graft function, post-transplant lymphoproliferative disease and medical non-adherence. While long-term outcome remains similar between adult and paediatric lung transplant recipients, there is a lower risk of bronchiolitis obliterans in very young recipients and in those who receive living donor lobar lung transplantation. Research into these clinical problems is hampered by the fact that only a small number of paediatric transplants are performed at each centre. Hence, improvement in outcome for these children will be dependent on developing methods to produce better tolerance, understanding the mechanisms/treatment of bronchiolitis obliterans and multi-centre studies that focus on the problems that primarily affect the paediatric lung transplant recipient.

Surrogate markers and risk factors for chronic lung allograft dysfunction

Obliterative bronchiolitis (OB) is the histologic correlate of chronic allograft dysfunction in pulmonary transplantation. The histologic diagnosis of OB is challenging, therefore a physiologic definition, bronchiolitis obliterans syndrome (BOS) based on pulmonary function tests has been used as a surrogate marker for OB for the last decade. BOS has proven to be the best available surrogate marker for OB and is predictive of the ultimate endpoints of graft and patient survival. Multiple other clinical markers have been reported and proposed as alternates for or complements to BOS grade, but all need further evaluation and validation in large, prospective clinical trials. Lastly, given the early occurrence and high incidence of chronic allograft dysfunction, the easily measurable endpoint of BOS grade, and our lack of understanding of ways to prevent or alter the course of BOS, lung transplant recipients represent an ideal population for clinical trials targeting prevention and treatment of chronic allograft dysfunction.

Bronchiolitis obliterans

PURPOSE OF REVIEW

Bronchiolitis obliterans (BO) occurs in both post-lung transplant and nontransplant-related individuals, and is characterized by mainly irreversible airflow obstruction that is often ultimately progressive.

RECENT FINDINGS

While post-lung transplant BO is a major cause of lung allograft dysfunction, and hence is better characterized than nontransplant-related BO, it is likely that many similarities in pathogenesis and treatment apply to both categories.

SUMMARY

Optimal management for BO remains to be established, and the role of retransplantation in this disease requires further consensus. Minimization of risk factors for BO and earlier detection in the form of methacholine challenge testing and HRCT scans of the chest amongst other forms of detection, may help in the stabilization and possible resolution of early BO.

Role of CMV pneumonia in the development of obliterative bronchiolitis in heart-lung and double-lung transplant recipients

Obliterative bronchiolitis (OB) is the main cause of late mortality after lung transplantation. Cytomegalovirus infection has been associated with late graft failure. The aim of this study was to determine whether the development of OB was related to CMV pretransplant serological status and to CMV infections. The study group comprised 36 lung transplant recipients (27 HLT and 9 DLT) who survived more than 4 months, of whom 47% developed OB (defined by the persistence of an unexplained obstructive disease: FEV1/VC < 0.7). OB occurred more frequently: (1) in seronegative recipients with seropositive donors (8/9) than in seropositive recipients (7/19) or seronegative well-matched recipients (2/8); and (2) in patients who experienced CMV pneumonia (11/16) and CMV recurrence (11/16). Since matching seronegative recipients is the best way to prevent CMV infection, we believe that seronegative grafts must be reserved for seronegative recipients.

Pediatric lung transplantation: update 2003

In the past 15 years there have been more than 1200 pediatric lung and heart-lung transplants worldwide. This article regarding the current status of pediatric lung transplantation describes indications, outcomes, and complications, with particular emphasis on issues specific to pediatrics, including growth. Information useful to the pediatrician and pediatric pulmonologist is also included. Issues important to the future are reviewed.

Infectious complications in pediatric solid organ transplantation

Transplantation has emerged as one of the remarkable achievements of the latter half of the twentieth century for treatment of many end-stage organ disorders. Survival in pediatric solid organ transplantation continues to improve as strategies for immunosuppression, prevention and treatment of infectious complications progress. This article presents the summaries of the common and opportunistic pathogens that cause infectious complications for the pediatric transplant recipient. In addition, an approach to the pediatric transplant patient who presents with specific symptoms suggestive of infection is provided.

Pulmonary involvement during cytomegalovirus infection in immunosuppressed patients

Although cytomegalovirus (CMV) pulmonary involvement after solid organ transplantation is infrequently seen nowadays, CMV pneumonitis is still a potential lethal complication. Introduction of the pp65 antigenemia assay enabled early and rapid diagnosis of CMV viremia in transplant patients prior to symptoms. Also, in asymptomatic patients with CMV viremia, a decreased pulmonary diffusion capacity could be demonstrated. In this review, we discuss clinical and subclinical pulmonary involvement of CMV infection in the immunocompromised host with an emphasis on transplant recipients. The clinical course, diagnosis, therapy, prophylaxis, and pathophysiology of CMV pneumonitis are discussed.

Transplant histopathology for the general histopathologist

The number of patients undergoing solid organ transplants and surviving long-term has increased enormously in the last 10 years. This means that pathologists in non-specialist transplant centres are increasingly involved in the interpretation of biopsy and autopsy material from allograft recipients. This includes evaluation of allograft histology, or specimens from other native tissues, which nonetheless still have to be assessed in the setting of transplantation and immunosuppressive therapy. In this first review article we will provide an overview of the pathology of lung transplantation, and briefly describe heart and pancreatic transplants, as well as aspects of general surgical pathology and the role of the autopsy in these patients.