Human herpesvirus 6 in bronchalveolar lavage fluid after lung transplantation: a risk factor for bronchiolitis obliterans syndrome?

Evaluation of host cellular responses to Epstein-Barr virus (EBV) in adult lung transplant patients with EBV-associated diseases

Epstein-Barr virus (EBV) reactivation is commonly observed in lung transplant recipients (LTRs). However, cellular immune responses to EBV in adult LTRs have not been well described. We aimed to study CD4/CD8 ratio, EBV-specific T cells polyfunctional responses and phenotypic changes in natural killer (NK) cells in adult LTRs presenting with EBV-associated diseases. The CD4/CD8 ratio was significantly decreased in LTRs with EBV DNAemia compared with LTRs without EBV DNAemia and healthy controls (HCs). Stimulation with EBV lytic antigen BZLF1 peptide pools induced significant individual and polyfunctional responses from CD8+ CD69+ T cells. Frequencies of CD8+ CD69+ T cells expressing CD107a were significantly higher in LTRs without EBV DNAemia than in LTRs with DNAemia. Frequencies of CD8+ CD69+ T cells concurrently expressing CD107a, IFN-γ, and TNF-α were significantly greater in LTRs with and without EBV DNAemia than in HCs. Finally, BZLF1 induced significantly higher frequencies of CD8+ CD69+ T cells expressing CD107a and IFN-γ in LTRs without EBV DNAemia when compared with EBNA3B. Frequency of more differentiated CD56dim CD16pos NK cells was significantly decreased in LTRs with EBV DNAemia and PTLD compared with HCs. In conclusion, we noted the presence of significant changes in circulating cellular immune responses to EBV in adult LTRs.

Human herpesvirus 6, 7, and 8 in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of HHV-6A, HHV-6B, HHV-7, and HHV-8 in the pre- and post-transplant period. The majority of HHV-6 (A and B) and HHV-7 infections in transplant recipients are asymptomatic; symptomatic disease is reported infrequently across organs. Routine screening for HHV-6 and 7 DNAemia is not recommended in asymptomatic patients, nor is prophylaxis or preemptive therapy. Detection of viral nucleic acid by quantitative PCR in blood or CSF is the preferred method for diagnosis of HHV-6 and HHV-7 infection. The possibility of chromosomally integrated HHV-6 DNA should be considered in individuals with persistently high viral loads. Antiviral therapy should be initiated for HHV-6 encephalitis and should be considered for other manifestations of disease. HHV-8 causes Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman disease and is also associated with hemophagocytic syndrome and bone marrow failure. HHV-8 screening and monitoring may be indicated to prevent disease. Treatment of HHV-8 related disease centers on reduction of immunosuppression and conversion to sirolimus, while chemotherapy may be needed for unresponsive disease. The role of antiviral therapy for HHV-8 infection has not yet been defined.

Bone marrow transplant-induced alterations in Notch signaling promote pathologic Th17 responses to γ-herpesvirus infection

Idiopathic pneumonia syndrome (IPS) is a common, often fatal, complication following hematopoietic stem cell transplantation (HSCT) characterized by severe pneumonitis and interstitial fibrosis. Fully reconstituted syngeneic bone marrow transplant (BMT) mice infected with murine γ-herpesvirus-68 develop interleukin-17 (IL-17)-driven pneumonitis and fibrosis, which mimics clinical manifestations of IPS. We found CD103+ and CD11b+ dendritic cells (DCs) are selectively deficient for the Notch ligand, DLL4, following BMT and CD4+ T cells isolated from lungs and spleens of infected BMT mice display Notch signaling defects. Mice transplanted with CD4-Cre-driven dominant-negative Notch transcriptional regulator Mastermind-Like (CD4-Cre-DNMAML (CCD) mice) bone marrow displayed elevated IL-17 and transforming growth factor-β (TGF β) in the lungs, a further expansion of T-helper type 17 (Th17) cells, and developed more fibrosis than wild-type (WT)-BMT mice. Culture of BMT lung leukocytes with recombinant Notch ligand, DLL4, restored Notch signaling and decreased production of IL-17. Adoptive transfer of CD11c+ DCs could restore Th1 and limit Th17 in WT-BMT but not CCD-BMT mice, indicating that a specific DC/CD4+ T-cell Notch interaction modulates IL-17 production following reconstitution in syngeneic BMT mice. Given recent clinical observations showing that patients with pulmonary complications post-transplant harbor occult herpesvirus infections, these data provide mechanistic insight and suggest potential therapies for these devastating conditions.

Loss of CCR2 signaling alters leukocyte recruitment and exacerbates γ-herpesvirus-induced pneumonitis and fibrosis following bone marrow transplantation

CCR2-expressing leukocytes are required for the progression of fibrosis in models of induced lung injury as well as models of bone marrow transplant (BMT)-related idiopathic pneumonia syndrome. Infection with murid γ-herpesvirus-68 (γHV-68) results in severe pneumonitis and pulmonary fibrosis following syngeneic BMT; however, the roles that various proinflammatory leukocyte populations play in this process remain unclear. Deletion of CCR2 in both non-BMT and BMT mice increased early lytic viral replication and resulted in a reduction in the numbers of lung-infiltrating GR1+,F4/80+ and CXCR1+ cells, while maintaining robust neutrophil infiltration. Similarly, in γHV-68-infected CCR2(-/-) BMT mice, recruitment of monocytes and lymphocytes were reduced whereas neutrophil recruitment was increased compared with wild-type (WT) BMT mice. Interestingly, levels of profibrotic IL-17 were increased in infected CCR2 BMT mice compared with WT BMT. Furthermore, an increase in lung-associated collagen was detected even though there was an overall decrease in the number of profibrotic CCR2+ fibrocytes detected in the lungs of CCR2(-/-) BMT mice. These data indicate that, contrary to most models of fibrosis, deletion of CCR2 offers no protection from γ-herpesvirus-induced pneumonitis and fibrosis, and, indeed, CCR2+ cells play a suppressive role during the development of pulmonary fibrosis following γ-herpesvirus infection post-BMT by limiting IL-7 and collagen production.

Infectious Triggers of Chronic Lung Allograft Dysfunction

Survival after lung transplantation is limited in large part due to the high incidence of chronic rejection, known as chronic lung allograft dysfunction (CLAD). Pulmonary infections are a frequent complication in lung transplant recipients, due both to immunosuppressive medications and constant exposure of the lung allograft to the external environment via the airways. Infection is a recognized risk factor for the development of CLAD, and both acute infection and chronic lung allograft colonization with microorganisms increase the risk for CLAD. Acute infection by community acquired respiratory viruses, and the bacteria Pseudomonas aeruginosa and Staphylococcus aureus are increasingly recognized as important risk factors for CLAD. Colonization by the fungus Aspergillus may also augment the risk of CLAD. Fostering this transition from healthy lung to CLAD in each of these infectious episodes is the persistence of an inflammatory lung allograft environment.

The Impact of Infection on Chronic Allograft Dysfunction and Allograft Survival After Solid Organ Transplantation

Infectious diseases after solid organ transplantation (SOT) are a significant cause of morbidity and reduced allograft and patient survival; however, the influence of infection on the development of chronic allograft dysfunction has not been completely delineated. Some viral infections appear to affect allograft function by both inducing direct tissue damage and immunologically related injury, including acute rejection. In particular, this has been observed for cytomegalovirus (CMV) infection in all SOT recipients and for BK virus infection in kidney transplant recipients, for community-acquired respiratory viruses in lung transplant recipients, and for hepatitis C virus in liver transplant recipients. The impact of bacterial and fungal infections is less clear, but bacterial urinary tract infections and respiratory tract colonization by Pseudomonas aeruginosa and Aspergillus spp appear to be correlated with higher rates of chronic allograft dysfunction in kidney and lung transplant recipients, respectively. Evidence supports the beneficial effects of the use of antiviral prophylaxis for CMV in improving allograft function and survival in SOT recipients. Nevertheless, there is still a need for prospective interventional trials assessing the potential effects of preventive and therapeutic strategies against bacterial and fungal infection for reducing or delaying the development of chronic allograft dysfunction.

The lung microbiome after lung transplantation

Lung transplantation survival remains significantly impacted by infections and the development of chronic rejection manifesting as bronchiolitis obliterans syndrome (BOS). Traditional microbiologic data has provided insight into the role of infections in BOS. Now, new non-culture-based techniques have been developed to characterize the entire population of microbes resident on the surfaces of the body, also known as the human microbiome. Early studies have identified that lung transplant patients have a different lung microbiome and have demonstrated the important finding that the transplant lung microbiome changes over time. Furthermore, both unique bacterial populations and longitudinal changes in the lung microbiome have now been suggested to play a role in the development of BOS. In the future, this technology will need to be combined with functional assays and assessment of the immune responses in the lung to help further explain the microbiome's role in the failing lung allograft.

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.

Infections due to human herpesvirus 6 in solid organ transplant recipients

PURPOSE OF REVIEW

This article summarizes the current state of the epidemiology, diagnosis, and management of human herpesvirus 6 (HHV-6) infection after solid organ transplantation.

RECENT FINDINGS

HHV-6 reactivates commonly during the early weeks after solid organ transplantation. However, disease due to HHV-6 is uncommon and is manifested as a febrile illness associated with rash and tissue-invasive manifestations such as encephalitis, hepatitis, pneumonitis, and gastrointestinal disease. HHV-6 has also been indirectly associated with other opportunistic infections such as cytomegalovirus and fungal infections. Molecular tests such as PCR assays are preferred methods for the diagnosis of HHV-6 infection. Recent guideline from the American Society of Transplantation Infectious Disease Community of Practice does not recommend specific antiviral prophylaxis or preemptive therapy for HHV-6 infection. For established disease, intravenous ganciclovir and foscarnet are considered first-line agents.

SUMMARY

Infection due to HHV-6 is a common after transplantation, but clinical disease is rare. Nonetheless, this infection has been indirectly associated with poor allograft and patient survival after transplantation. No specific prevention strategy is recommended, but treatment of established HHV-6 disease consists of antiviral therapy with intravenous ganciclovir and/or foscarnet, and reduction in immunosuppression.

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.

Human herpesviruses 6, 7 and 8 in solid organ transplant recipients

Human herpesviruses (HHV) 6 and 7 are ubiquitous infections that reactivate commonly in transplant recipients. However, clinical diseases due to these viruses are reported only in 1% of solid organ transplant recipients. Fever, rash and bone marrow suppression are the most common manifestations, but symptoms of tissue invasive disease may be observed. Treatment of HHV-6 and HHV-7 disease includes antiviral therapy and cautious reduction in immunosuppression. HHV-8 is an oncogenic gamma-herpesvirus that causes Kaposi's sarcoma, Castleman's disease and primary effusion lymphomas in transplant recipients. Nonmalignant diseases such as bone marrow suppression and multiorgan failure have also been associated with HHV-8. Reduction in immunosuppression is the first line treatment of HHV-8 infection. Other alternatives for treatment, especially for HHV-8 diseases not responsive to immuno-minimization strategies, are surgery and chemotherapy. Sirolimus has been shown to be a beneficial component for the treatment of Kaposi's sarcoma and the role of antivirals for HHV-8 infection is being investigated.

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.

Managing complications following lung transplantation

Lung transplantation has become a proven therapeutic option for patients with end-stage lung disease, extending life and providing improved quality of life to those who otherwise would continue to be breathless and oxygen-dependent. Over the past 20 years, considerable experience has been gained in understanding the multitude of medical and surgical issues that impact upon patient survival. Today, clinicians have an armamentarium of tools to manage diverse problems such as primary graft dysfunction, acute and chronic allograft rejection, airway anastomotic issues, infectious complications, renal dysfunction, diabetes and osteoporosis, hematological and gastrointestinal problems, malignancy, and other unique issues that confront immunosuppressed solid organ transplant recipients.

Human herpesvirus-6 infections in kidney, liver, lung, and heart transplantation: review

Human herpesvirus-6 (HHV-6), which comprises of HHV-6A and HHV-6B, is a common infection after solid organ transplantation. The rate of HHV-6 reactivation is high, although clinical disease is not common. Only 1% of transplant recipients will develop clinical illness associated with HHV-6 infection, and most are ascribable to HHV-6B. Fever, myelosuppression, and end-organ disease, including hepatitis and encephalitis, have been reported. HHV-6 has also been associated with various indirect effects, including a higher rate of CMV disease, acute and chronic graft rejection, and opportunistic infection such as invasive fungal disease. All-cause mortality is increased in solid organ transplant recipients with HHV-6 infection. HHV-6 is somewhat unique among human viruses because of its ability to integrate into the host chromosome. The clinical significance of chromosomally integrated HHV-6 is not yet defined, although a higher rate of bacterial infection and allograft rejection has been suggested. The diagnosis of HHV-6 is now commonly made using nucleic acid testing for HHV-6 DNA in clinical samples, but this can be difficult to interpret owing to the common nature of asymptomatic viral reactivation. Treatment of HHV-6 is indicated in established end-organ disease such as encephalitis. Foscarnet, ganciclovir, and cidofovir have been used for treatment.

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.

Chronic allograft dysfunction

Chronic, progressive, and irreversible loss of lung function is the major medium-term and long-term complication after lung transplantation and the leading cause of death. Over the past decade, progress has been made in understanding the pathogenesis of bronchiolitis obliterans. Alloimmune factors and nonalloimmune factors may contribute to its development. Understanding the precise mechanism of each type of chronic allograft dysfunction may open up the field for new preventive and therapeutic interventions. This article reviews major new insights into the clinical aspects, pathophysiology, risk factors, diagnosis, and management of chronic allograft dysfunction after lung transplantation.

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.

Herpesviruses detection by quantitative real-time polymerase chain reaction in bronchoalveolar lavage and transbronchial biopsy in lung transplant: viral infections and histopathological correlation

The monitoring of herpesvirus infection plays a central role in lung transplantation (LT). Herein we evaluated the prevalence of human cytomegalovirus (HCMV), human herpesvirus-6 (HHV-6), human herpesvirus-7 (HHV-7), and Epstein-Barr Virus (EBV) DNA in bronchoalveolar lavage (BAL) and transbronchial biopsy (TBB) specimens from LT patients. We associated the findings with the occurrence of interstitial pneumonia, acute rejection, or organizing pneumonia. Viral DNA was detected using real-time polymerase chain reaction (PCR) on 76 paired samples (BAL and TBB) from 27 patients who were receiving a universal combined prophylaxis (cytomegalovirus [CMV] immunoglobulin [Ig] + gancyclovir or valgancyclovir). Histopathological analysis was performed in accordance with the International Society for Heart and Lung Transplantation (ISHLT) criteria. Overall, HCMV results were positive in 25/76 (32.9%) specimens (BAL and/or TBB); HHV-6 in 16 (21.1%); HHV-7 in 40 (52.6%); and EBV in 13 (17.1%). Interstitial pneumonia was diagnosed in 6/76 (7.9%) cases: 5 (83.3%) were positive to HCMV (combined specimens; P < .0001); 5 (83.3%) to HHV-7; and 2 (33.3%) to EBV. An acute rejection episode was diagnosed in 19/76 (25%) cases: 7 (36.8%) were positive to HCMV; 5 (26.3%) to HHV-6; 10 (52.6%) to HHV-7, and 3 (15.8%) to EBV. No significant association was observed between virus detection or load and acute rejection. Organizing pneumonia was diagnosed in 4/76 (5.3%) cases: 1 (25%) positive to HCMV; 4 (100%) to HHV-6 (P < .05); 2 (50%) to HHV-7; and none to EBV. In conclusion, the prevalence of HCMV tended to be lower than that reported in the literature, confirming the importance of universal combined prophylaxis. HCMV was a relevant agent for interstitial pneumonia; although the small numbers limit the statistical analysis, our data did not support an association between herpesviruses and acute rejection episodes, whereas the role of HHV-6 in the pathogenesis of organizing pneumonia deserves further study. Viral detection on TBB could represent an adjunctive tool to complement that on BAL.

Epstein-Barr virus-associated pneumonia and bronchiolitis obliterans syndrome in a lung transplant recipient

We report the case of a 25-year-old lung and liver transplant recipient who developed respiratory failure. High levels of Epstein-Barr virus (EBV) genome copies were detectable in respiratory tract specimens, while the search for various other viral, bacterial or fungal pathogens remained empty. Post-transplant lymphoproliferative disease was excluded. Due to the rapid progression of respiratory insufficiency, a re-transplantation of the lung was performed. EBV-encoded small RNAs could be demonstrated by in situ hybridization within pneumocytes and lymphocytes of the explanted lung tissue. The clinical situation improved soon after re-transplantation, and the EBV load detected in the lower respiratory tract decreased significantly.

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.

Lack of association between beta-herpesvirus infection and bronchiolitis obliterans syndrome in lung transplant recipients in the era of antiviral prophylaxis

BACKGROUND

Cytomegalovirus (CMV), human herpesvirus-6 and -7 (HHV-6 and -7) are beta-herpesviruses that commonly reactivate and have been proposed to trigger acute rejection and chronic allograft injury. We assessed the contribution of these viruses in the development of bronchiolitis obliterans syndrome (BOS) after lung transplantation.

METHODS

Quantitative real-time polymerase chain reaction of bronchoalveolar lavage samples were performed for CMV, HHV-6 and -7 in a prospective cohort of lung transplant recipients. A time-dependent Cox regression analysis was used to correlate the risk of BOS and acute rejection in patients with and without beta-herpesviruses infection.

RESULTS

Ninety-three patients were included in the study over a period of 3 years. A total of 581 samples from bronchoalveolar lavage were obtained. Sixty-one patients (65.6%) had at least one positive result for one of the beta-herpesviruses: 48 patients (51.6%) for CMV and 19 patients (20.4%) for both HHV-6 and -7. Median peak viral load was 3419 copies/mL for CMV, 258 copies/mL for HHV-6, and 665 copies/mL for HHV-7. Acute rejection (>or=grade 2) occurred in 46.2% and BOS (>or=stage 1) in 19.4% of the patients. In the Cox regression model the relative risk of acute rejection or BOS was not increased in patients with any beta-herpesviruses reactivation. Acute rejection was the only independently associated risk factor for BOS.

CONCLUSIONS

In lung transplant recipients receiving prolonged antiviral prophylaxis, reactivation of beta-herpesviruses within the allograft was common. However, despite high viral loads in many patients, virus replication was not associated with the development of rejection or BOS.

Tacrolimus and mycophenolate mofetil as first line immunosuppression after lung transplantation

The optimal maintenance therapy after lung transplantation remains to be established. The aim of this study was to analyse the impact of tacrolimus and mycophenolate mofetil (MMF) as first line immunosuppression on long-term survival and Bronchiolitis Obliterans Syndrome (BOS). From January 1996 through December 2006, all 155 recipients receiving tacrolimus and MMF as maintenance immunosuppression were included in this study. Tacrolimus and MMF was discontinued in 36 patients (23.2%). The overall survival rates were 91.6% at 6 months, 86.4% at 1 year, 74.9% at 3 years, 60.3% at 5 years and 32.4% at 10 years. The overall freedom from acute rejection was 74.6%, 63.2% and 59.4% at 1, 3, and 5 years respectively. The overall BOS-free survival was 95.6% at 1 year, 88.4% at 3 years, 69.5% at 5 years and 30.5% at 10 years. The development of BOS > or = 1 was associated with a significantly increased risk of death and reduced long-term survival. The combination of tacrolimus and MMF offers safe and reliable maintenance immunosuppression after lung transplantation. However, substantial improvements of long-term survival and freedom from BOS might only be achieved by a change in organ allocation policies and patient management beyond differential immunosuppressive protocols.

An assessment of herpesvirus co-infections in patients with CMV disease: correlation with clinical and virologic outcomes

The effect of herpesvirus co-infections (HHV-6, HHV-7) on cytomegalovirus (CMV) disease and its response to therapy is unknown. We prospectively analyzed herpesvirus co-infections in transplant recipients with CMV disease. All patients received 3 weeks of antiviral therapy. Samples were collected at baseline (day 0) and then day 3, 7, 14 and 21 poststart of therapy. Viral load testing for CMV, HHV-6 and HHV-7 was done using quantitative PCR assays in 302 patients of whom 256 had documented symptomatic CMV viremia. In this subset, day 0 HHV-6 co-infection was present in 23/253 (9.1%) and HHV-7 in 17/253 (6.7%). Including those positive at any time point raised the prevalence to 79/256 (30.9%) for HHV-6 and 75/256 (29.3%) for HHV-7. Viral co-infection did not influence the response of CMV disease to antiviral therapy. Baseline CMV viral loads, time to eradication and risk of recurrence were similar in patients with and without HHV-6 or HHV-7 co-infection. Ganciclovir and valganciclovir had no clear effect on HHV-6 and HHV-7 viremia. In conclusion, herpesvirus co-infections are common in patients with CMV disease but with standard antiviral therapy, no clear clinical effects are discernable. Routine monitoring for viral co-infection in patients with CMV disease is not indicated.

Altered levels of CC chemokines during pulmonary CMV predict BOS and mortality post-lung transplantation

Pulmonary CMV infection (CMVI) and disease (CMVD) is associated with reduced long-term survival post-lung transplantation, however, the specific biologic mechanisms remain unclear. We have demonstrated a role of CC chemokines during lung allograft dysfunction. Based on these findings, we hypothesized that pulmonary CMV upregulates the expression of multiple CC chemokines that leads to allograft dysfunction and decreased long-term survival. We performed a nested case control study in lung transplant recipients to investigate alterations in CC chemokine biology during pulmonary CMV. Levels of CC chemokines were measured in bronchoalveolar lavage fluid (BALF) from recipients with CMVI (n = 33), CMVD (n = 6), and in healthy lung transplant controls (n = 33). We found a trend toward increased levels of MIP-1alpha/CCL3 during pulmonary CMVI. Levels of MCP-1/CCL2 and RANTES/CCL5 were significantly elevated during pulmonary CMV. Interestingly, elevated levels of CCL3 in BALF were protective with regards to survival. Importantly, elevated levels of CCL2 in BALF predicted the development of BOS, while elevated levels of CCL5 in BALF predicted an increase in mortality post-lung transplant. Altered levels of specific CC chemokines during pulmonary CMV are associated with future clinical outcomes. These results suggest a possible utility of BALF CC chemokines as biomarkers for guiding risk assessment during pulmonary CMV post-lung transplantation.

Human Herpesvirus-6 and -7 After Lung and Heart–Lung Transplantation

BACKGROUND

The impact of herpesvirus-6 and -7 (HHV-6, HHV-7) activation in lung transplant recipients is still poorly understood. We report the appearance of HHV-6 and HHV-7 antigenemia after lung transplantation and evaluate the efficacy of anti-viral drugs against these viruses.

METHODS

Twenty-two lung or heart-lung recipients were monitored for HHV-6, HHV-7 and cytomegalovirus (CMV) during 12 post-operative months. HHV-6- and HHV-7-specific antigens and CMV pp65 antigens were analyzed in blood leukocytes and bronchoalveolar lavage fluid cells by monoclonal antibodies. Ganciclovir or valganciclovir prophylaxis for a minimum of 3 months was given to 19 recipients at risk for CMV infection.

RESULTS

HHV-6, HHV-7 and CMV antigenemia was detected in 20 (91%), 11 (50%) and 12 (55%) recipients (median 16, 31 and 165 days) after transplantation, respectively. HHV-6 antigenemia occurred in 15 (79%), HHV-7 antigenemia in 7 (37%) and CMV antigenemia in 1 (7%) of these patients during anti-viral prophylaxis. HHV-6 or HHV-7 antigenemia was frequently associated with CMV antigenemia, which was detected 3 to 12 months after transplantation. Ganciclovir or valganciclovir treatment of CMV infection was effective against the concomitant HHV-6 and HHV-7 antigenemia in 9 of 12 (75%) and 5 of 6 (83%) cases, respectively. One case of pneumonitis and 1 of encephalitis were temporally associated with HHV-6. No other clinical manifestations could be linked solely to HHV-6 or -7.

CONCLUSIONS

HHV-6 and -7 antigenemia was common and appeared early after lung transplantation. CMV prophylaxis was not able to prevent the appearance of HHV-6 and -7 antigenemia.

Quantitative detection of herpes simplex virus DNA in the lower respiratory tract

Quantitation of herpes simplex virus (HSV) DNA in bronchoalveolar lavage specimens could indicate an infectious role in the lower respiratory tract. The aim of this study was to compare quantitative HSV DNA results from adult bronchoalveolar lavage specimens to clinical outcome. Quantitative real-time PCR assays targeting HSV and other herpes viruses were performed on adult bronchoalveolar lavage specimens obtained from a largely immunocompromised population during a 1-year period. The results were compared to patient characteristics and outcome. HSV DNA was detected in 11 (19%) of 57 bronchoalveolar lavage specimens with a mean viral level of 5.6 log genome equivalents/ml (range, 2.9-8.1 log). A threshold of HSV DNA levels equal or higher than 5.0 log (n = 7) was associated with mortality within 28 days following hospital admission (odds ratio [OR], 6.8; 95% confidence interval [CI], 1.2-39.2). A threshold level of 5.5 log was associated with mortality within 28 days of sampling (OR 8.5; 95% CI 1.2-62.1), only after excluding patients receiving specific antiviral medication. Patients with HSV DNA levels equal or higher than 7.5 log had severe respiratory failure. Viral pneumonia was histologically proven in one patient with 8.0 log at autopsy. No patient with HSV DNA levels below 5.5 log (n = 5) or DNA levels higher than 5.0 log of cytomegalovirus (CMV) (n = 3), Epstein-Barr virus (EBV) (n = 9), varicella-zoster virus (VZV) (n = 1), or human herpesvirus 6 (HHV-6) (n = 0) died within 28 days of hospital admission. We conclude that quantitative detection of HSV DNA in bronchoalveolar lavage fluid is a potential diagnostic tool for detection of relevant viral infection of the lower respiratory tract.

Relationship between cytomegalovirus DNA load in epithelial lining fluid and plasma of lung transplant recipients and analysis of coinfection with Epstein-Barr virus and human herpesvirus 6 in the lung compartment

Cytomegalovirus (CMV) is a significant cause of morbidity and mortality in lung transplant recipients (LTRs). The aim of the present study was to elucidate the relationship between the CMV DNA load in the lung compartment and that in plasma. For CMV load determination, the level of CMV DNA in plasma and bronchoalveolar lavage (BAL) samples was measured in a total of 97 paired BAL and plasma samples obtained from 25 LTRs. The original virus concentration in the epithelial lining fluid (ELF) was calculated from the BAL samples by correcting for dilution using the urea dilution method. In addition, the load of Epstein-Barr virus (EBV) and that of human herpesvirus 6 (HHV-6) DNA also were determined in BAL samples, recalculated for their concentrations in the ELF, and compared with the CMV DNA load. CMV DNA was found more frequently and at significantly higher levels in the lung compartment than in plasma (P<0.001, Wilcoxon test), and the CMV load in the ELF was associated with symptomatic CMV disease. EBV and HHV-6 were detected in 43.6% and 21.7% of the ELF samples, respectively. A statistically significant association was found between the CMV and EBV DNA loads in the ELF (P<0.001; Spearman's rho=0.651). Thus, in LTRs, determination of the CMV DNA load in the lung compartment may be advantageous compared to monitoring only viremia. The significant relationship between EBV and CMV DNA loads in the ELF of LTRs and its clinical impact require further investigation.

Sleeping Beauty-based gene therapy with indoleamine 2,3-dioxygenase inhibits lung allograft fibrosis

Sleeping Beauty (SB) transposon is a natural nonviral gene transfer system that can mediate long-term transgene expression. Its potential utility in treating organ transplantation-associated long-term complications has not yet been explored. In the present study we generated an improved SB transposon encoding the human gene indoleamine-2,3-dioxygenase (hIDO), an enzyme that possesses both T cell-suppressive and antioxidant properties and selectively delivered the SB transposon in combination with a hyperactive transposase plasmid to donor lung using the cationic polymer polyethylenimine (PEI) as transfection reagent. This nonviral gene therapeutic approach led to persistent and uniform transgene expression in the rat lung tissue without noticeable toxicity and inflammation. Importantly, IDO activity produced by hIDO transgene showed a remarkable therapeutic response, as evident by near normal pulmonary function (peak airway pressure and oxygenation), histological appearance, and reduced collagen content in lung allografts. In addition, we established a hIDO-overexpressing type II cell line using the SB-based gene transfer system and found that hIDO-overexpressing lung cells effectively inhibited transforming growth factor-beta-stimulated fibroblast proliferation in vitro. In summary, the SB-based gene therapy with hIDO represents a new strategy for treating lung transplantation-associated chronic complications, e.g., obliterative bronchiolitis.

Biological and clinical advances in human herpesvirus-6 and -7 research

Since its isolation more than 20 years ago, human herpesvirus (HHV)-6 has been considered an opportunistic pathogen whose infection and/or reactivation is associated with diseases such as roseola, organ transplant anomalies and central nervous system disorders. The lack of relevant animal models, standardized diagnostic reagents and specific anti-HHV-6 drugs has impaired our ability to prove a causal relationship between the presence of this virus and the development of many diseases. Unless such models and reagents are developed and clinical trials performed, speculations on the role for this virus in various pathologies will continue to grow. In this review, recent biological, clinical and epidemiological research advances in the HHV-6 field as well as that of its closest relative, HHV-7, will be presented. Additionally, priority research areas that will help move the field forward are discussed.